Air Quality Observation Systems in the 

United States

NOVEMBER 2013

PRODUCT OF THE

Committee on Environment, Natural Resources, and 

Sustainability 

OF THE NATIONAL SCIENCE AND TECHNOLOGY COUNCIL
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THIS DOCUMENT IS A PRODUCT OF

THE NATIONAL SCIENCE & TECHNOLOGY COUNCIL’S 

COMMITTEE ON ENVIRONMENT, NATURAL RESOURCES, AND SUSTAINABILITY

About the National Science and Technology Council

The National Science and Technology Council (NSTC) is the principal means by which the Executive 

Branch coordinates science and technology policy across the diverse entities that make up the Federal 

research and development enterprise. A primary objective of the NSTC is establishing clear national 

goals for Federal science and technology investments. The NSTC prepares research and development 

strategies that are coordinated across Federal departments and agencies to form investment packages 

aimed at accomplishing multiple national goals. The work of the NSTC is organized under five 

committees: Environment, Natural Resources and Sustainability; Homeland and National Security; 

Science, Technology, Engineering, and Math (STEM) Education; Science; and Technology. Each of these 

committees oversees subcommittees and working groups focused on different aspects of science and 

technology. More information is available at http://www.whitehouse.gov/ostp/nstc.

About the Office of Science and Technology Policy

The Office of Science and Technology Policy (OSTP) was established by the National Science and 

Technology Policy, Organization, and Priorities Act of 1976. OSTP’s responsibilities include advising the 

President in policy formulation and budget development on questions in which science and technology 

are important elements; articulating the President’s science and technology policy and programs; and 

fostering strong partnerships among Federal, state, and local governments, and the scientific 

communities in industry and academia. The Director of OSTP also serves as Assistant to the President for 

Science and Technology and manages the NSTC. More information is available at 

http://www.whitehouse.gov/ostp.

About Subcommittee on Air Quality Research (AQRS)

The Subcommittee on Air Quality Research (AQRS) is chartered to advise and assist in the coordination 

and enhancement of the effectiveness of U.S. air quality research. Its scope includes the observation, 

understanding, prediction, and assessment of the causes and consequences, both physical and

biological, of degraded air quality, and the development of effective preservation and remediation 

strategies. In reporting to the CENRS, AQRS functions to: identify research information required to 

inform policy decisions; develop Federal interagency research strategies and priorities; serve as a forum 

to facilitate research planning; coordinate with other NSTC, Federal interagency, and private sector 

groups (as permitted by law); and periodically assess the effectiveness of Federal air quality research 

programs. 

Federal Copyright Information

This document is a work of the United States Government and is in the public domain (see 17 U.S.C. 

§105). Subject to the stipulations below, it may be distributed and copied with acknowledgment to 

OSTP. Copyrights to graphics included in this document are reserved by the original copyright holders or 

their assignees and are used here under the government’s license and by permission. Requests to use 

any images must be made to the provider identified in the image credits or to OSTP if no provider is 

identified. 
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National Science and Technology Council

Chair Staff

John P. Holdren Pedro I. Espina (through May 31, 2013)

Assistant to the President for Science and Executive Director

Technology and Director, Jayne B. Morrow (beginning June 1, 2013)

Office of Science and Technology Policy Executive Director

Committee on Environment, Natural Resources, and Sustainability

Chairs

Tamara Dickinson Kathryn Sullivan

Principal Assistant Director for Environment and Acting Undersecretary for Oceans and Atmosphere

Energy; Assistant Director for Disaster Resilience Administrator of the National Oceanic and

and Space Science Atmospheric Administration

Office of Science and Technology Policy Department of Commerce

Glenn Paulson Staff

Science Advisor Lisa Matthews

Environmental Protection Agency Executive Secretary

Environmental Protection Agency

Subcommittee on Air Quality Research

Chair Staff

Dan Costa Jeanne Waters

Environmental Protection Agency Executive Secretary

National Oceanic and Atmospheric Administration

Akkihebbal Ravishankara

National Oceanic and Atmospheric Administration

Acknowledgments

This report was prepared by the Air Quality Research Subcommittee (AQRS) of the National Science and 

Technology Council’s Committee on Environment, Natural Resources, and Sustainability. It updates an 

earlier AQRS report on the Nation’s air quality networks and explores the broader integration of 

observational-based resources across several Federal agencies. The principal authors of this report are 

Richard Scheffe and Joseph Tikvart, based in the Office of Air Quality Planning and Standards of the U.S. 

Environment Protection Agency (EPA). Substantial assistance was provided by David McCabe of EPA’s 

Clean Air Task Force during his tenure as an American Association for the Advancement of Science 

Fellow. Significant review and advice was provided by the following: John Dawson, Terry Keating, Jim 

Szykman, and Richard Haeuber (EPA); Marc Pitchford, Richard Artz, David Parrish, John McNulty, Shobha 

Kondragunta, Steve Fine, and Jim Meagher (National Oceanic and Atmospheric Administration); John 

Ray, Julie Thomas, and Bill Malm (National Park Service); Jay Al-Saadi, Bruce Doddridge, and Doreen Neil 

(National Aeronautics and Space Administration); and Ray Knighton and Rich Pouyat (U.S. Department of 

Agriculture).
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Air Quality Observation Systems in the 

United States
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Table of Contents

Executive Summary .....................................................................................................................................7

Introduction................................................................................................................................................10

Overview of Observation Programs ..........................................................................................................15

Maintaining and Advancing Observation Programs.................................................................................42

Conclusions.................................................................................................................................................54

References..................................................................................................................................................56

Appendices.................................................................................................................................................... i
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Executive Summary – Air Quality Observation Systems in the United 

States 

In June 2013, President Obama released his Climate Action Plan. The Plan calls for a range of 

activities to help mitigate the impacts of carbon pollution, prepare for and adapt to those 

impacts that cannot be avoided, and enhance international efforts to reduce the harmful global 

effects of climate change. Success in each of the Plan’s three components will require access to 

and application of the highest quality atmospheric science. 

Fortunately, as a result of decades of attention to the issue of air quality generally – from ozone 

and carbon dioxide to soot and other particulates – the United States is in good position to 

address the added observational and modeling challenges posed by climate change. Federal 

agencies and state and local partners invest hundreds of millions of dollars annually to maintain 

and operate the Nation’s ground- and space-based air quality observation networks, and to 

conduct short-term field studies relating to air quality. The data collected by these activities 

have been indispensable to the effective development and implementation of policies to 

protect public health and the environment, and will be even more so as the Nation addresses 

the emerging impacts of climate change. 

This report catalogs the wide range of U.S. air quality measurement modalities and programs, 

including routine regulatory and deposition networks, intensive field studies, satellites, and 

fixed-site special-purpose networks operated or overseen by Federal departments and agencies 

– including the Environmental Protection Agency (EPA), National Oceanic and Atmospheric 

Administration (NOAA), National Aeronautics and Space Administration (NASA), U.S. 

Department of Agriculture (USDA), Department of Energy (DOE), Department of Health and 

Human Services (DHHS), Department of Homeland Security (DHS), and Department of the 

Interior (DOI) – and by various state, local and tribal partners. It also highlights some leading 

observational needs and opportunities, and identifies some of the barriers to fulfilling those 

needs and leveraging those opportunities. Specific programs and the pollutants they measure 

are documented in detail in the appendices. Among this report’s findings (not ranked in priority 

order) are:

Observational Needs

1. Although local and regional observation and emissions reduction efforts are generally 

well advanced in the United States, there is a need to improve characterization of 

pollutants from distant/international sources to better evaluate their contribution to 

domestic air quality.

2. There is a need for enhanced atmospheric, deposition, and effects monitoring to 

understand deposition impacts on aquatic and terrestrial ecosystems. 

3. There is a growing need to document global changes in climate that have the potential 

to affect the natural release or atmospheric processing of pollutants.

4. There is a need for greater attention to precursors of ozone and particulate matter in 

order to accurately assess the success of emissions control strategies. 
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5. There is an ongoing need for more cost effective means of compliance monitoring, to 

reduce financial burdens on state and local governments. 

6. There is a need for vertically resolved observations of ozone, particulate matter 

(including its composition), and their precursors, to evaluate and improve air quality 

modeling.

Opportunities

1. Satellite sensing of air quality and emissions is rapidly maturing in its capability to 

augment and extend the spatial and temporal coverage offered by fixed-site monitoring 

networks and short-term special studies, allowing for unprecedented, high value 

ventures into satellite-based, ecosystem-characteristic measurements. U.S. agency 

geostationary missions in the near future will provide coverage at scales highly relevant 

to urban air quality, presenting notable future opportunities for analysis and 

integration.

2. Air quality models are increasingly able to reliably augment direct observations with 

credible spatial, temporal, and compositional information lacking in direct 

measurements.

3. Open access policies are providing enhanced access to observational data, metadata, 

and processing tools, facilitating harmonization and consolidation of disparate datasets 

and collaboration among previously unrelated research teams.

Barriers to Progress 

1. Funding for long-term maintenance and updates of observation infrastructure is often 

subject to annual budgeting processes that inhibit long-range planning. 

2. Agencies often support their own priority programs rather than pooling resources on 

joint efforts in domains of shared responsibility.

3. Some issues are not adequately addressed because they do not fall clearly within any 

one entity’s regulatory purview.

4. Funding is often focused on the development of advanced technologies without 

adequate accompanying support for the development of tools for processing and 

transferring the resulting data streams.

5. In the absence of government mandates or other incentives, commercialization of air 

quality monitoring technologies suffers from weak market incentives.

Conclusion

The United States has a robust and invaluable network of air quality observation systems, and 

recent improvements in technology are providing unprecedented opportunities to enhance 

current capabilities. However, current funding patterns and limited coordination among 

departments and agencies with equities in air quality observations are preventing the Nation 

from reaching its full potential in this important domain. 
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The NSTC Committee on Environment, Natural Resources, and Sustainability (CENRS) should 

consider establishing a standing, multi-agency Observations Working Group under the Air 

Quality Research Subcommittee (AQRS) whose responsibilities could include: 

a. conducting periodic adequacy reviews of the Nation’s air quality observational 

capabilities;

b. identifying and addressing gaps and overlaps among programs;

c. building cooperation and coordination among government programs; 

d. advising on minimum standards for program design/implementation;

e. promoting the use of common data formats and communications protocols; 

f. identifying opportunities for development of, and review/recommending the use 

of, new observational technology;

g. fostering data quality elements, monitoring across appropriate gradients, and 

the role of modeling;

h. identifying low-priority networks that can be discontinued and defunded in order 

to offset the costs of new investments. 

The Working Group could also develop strategies to address such needs as: 

a. initiating monitoring of reactive gas and particulate nitrogen compounds, which 

are precursors of ozone and particulate matter, contributors to acid deposition, 

and nutrients in ecosystems;

b. collocating instrumentation at core measurement sites to facilitate intercomparison with satellite observations;

c. targeting observations in rural/remote areas to measure regional backgrounds 

and contributions from long-range transport of pollutants; 

d. establishing more robust air toxics monitoring near major industrial facilities to 

help investigate whether air toxics emissions are associated with reported 

human health effects in nearby communities; and

e. targeting intensive field studies designed to elucidate critical processes that 

determine atmospheric concentrations of ozone and particulate matter and 

other air pollutants.
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Introduction

Accurate information about air pollutants in the troposphere, such as ozone, 

particulates, and their respective precursors, is essential to decision-making in domains 

as diverse as human health, environmental protection, climate change, and agriculture, 

as well as for assessments of air quality management strategies and policies. 

Atmospheric observations have only grown in importance as the risks posed by global 

climate change have come more clearly into focus, and observations will be critical in 

the years ahead both for tracking the impacts of mitigation strategies and predicting 

national needs in the realm of adaptation and preparedness.

Modeling of the emissions and processes that affect air quality is improving rapidly. But 

direct observation remains the gold standard for tracking man-made and naturally 

occurring atmospheric species, the spatial and temporal distribution of which are 

governed by such complex influences as: the sources of those species; relevant 

meteorology; physical and chemical processes that transport, transform, and remove 

various species; and exchanges between the atmosphere and terrestrial and aquatic 

environs. 

Reliable assessments of atmospheric composition are especially important given the 

high financial stakes; the costs and benefits of Clean Air Act requirements alone are 

estimated to be on the order of tens of billions of dollars per year (National Research 

Council, 2004). In response to such regulatory and other incentives, a wide variety of 

Federal agencies and organizations make air quality observations or process or take 

advantage of air quality data, including EPA, NOAA, NASA, USDA, DOE, DHHS, DHS, and 

DOI, as do associated state, local and tribal partners. In many cases, these agencies 

share common information needs, and the value of air quality observations could be 

enhanced by coordinated planning or shared operations. Opportunities also exist to 

increase the value of air quality observations by integrating them across environmental 

media, pollutant categories, and spatial scales. 

This report (1) describes the measurement parameters, locations, and sponsoring 

organizations of ambient monitoring and other air quality observation and assessment 

efforts, focusing primarily on U.S. assets; and (2) identifies observational gaps and 

opportunities to enhance the value of existing measurement programs through interagency cooperation and collaboration. Appendices provide a comprehensive inventory 

of monitoring networks, observation programs, and pollutants measured.

Current and Emerging Air Quality Assessment Challenges

Over the last two decades, air quality management in the United States has focused on 

regional-scale air pollutants such as ozone, particulate matter, and acid deposition, all of 

which remain issues of concern and are likely to continue as such for the foreseeable 

future, especially if air quality standards continue to tighten. 
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Traditional management strategies typically involve independent, specific approaches 

based on targeted monitoring of individual pollutants. Increasingly, however, air quality 

management requires a more comprehensive and well-integrated assessment 

framework:

 Multiple pollutants – Typically, multiple pollutants are emitted by individual 

emission sources and participate in interrelated atmospheric, chemical, and 

physical transformation and loss processes. Too often, however, measurement 

systems are still structured to support only single-pollutant assessments. 

 Multiple environmental media – The atmosphere is closely coupled with 

terrestrial and aquatic systems. These systems are major sinks for air pollutants, 

leading to effects on ecosystems from acids, nutrients, and toxics. In turn, soils, 

vegetation, and aquatic systems re-emit mercury and persistent organic 

pollutants (POPs), and meteorology and climate affect biogenic and biomass 

burning emissions. These linkages require a broader perspective on 

environmental monitoring, which traditionally addresses issues on an isolated, 

single-media basis. Coordinated monitoring across multiple media is required to 

accurately assess progress mitigating the effects of atmospheric pollution on 

human health, ecosystems, and agriculture. 

 Multiple spatial scales – Long-range (inter-regional and intercontinental) 

pollutant transport is becoming increasingly important as transport across U.S. 

borders increases from expanded world development and as local emissions 

decline (NRC, 2009a). Meanwhile, urban-based field studies have demonstrated 

high pollutant levels in the near-source/roadway environment, where a majority 

of the North American population lives and the chemical environment is dynamic 

and poorly understood. These scale issues, at opposite ends of the spatial 

spectrum, challenge the current assessment framework that emphasizes 

regional air quality management.

 Climate-air quality interactions – The bi-directional interaction between air 

quality and climate change impacts air quality management. A variety of 

emissions, atmospheric chemistry, and transport processes that affect air quality 

are modified by climate change. Conversely, several air pollutants, particularly 

greenhouse gases, ozone, and black carbon particulate matter, are significant 

climate forcers, and air quality changes impact atmospheric and emissions 

processes, impacting climate. Moreover, climate forcers and conventional air 

pollutants are largely emitted from common sources. Consequently, emerging 

energy policies designed for moderating climate and policies designed to 

improve air quality are intrinsically connected, and measurement-system design 

should reflect this relationship.

Addressing these challenges would also address several challenges highlighted in 

integrated observational strategies (see Appendix A) and in three reports by the 

National Academies. 
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In Global Sources of Local Pollution: An Assessment of Long-Range Transport of Key Air 

Pollutants to and from the United States (NRC, 2009a), improved satellite observations, 

in situ monitoring, and intensive field campaigns were all highlighted as ways to improve 

understanding of air pollution transport. In Air Quality Management in the United States

(NRC, 2004), the highest priority recommendation for improving air quality 

management was to “strengthen the scientific and technical capacity of the [air quality 

management] system to assess risk and track progress.” Carefully designed and 

maintained monitoring can contribute to this progress by improving understanding of 

ambient concentrations, emissions, transport, and deposition and by improving 

modeling through more complete data for model evaluation. 

A third National Academies report, Observing Weather and Climate from the Ground Up: 

A Nationwide Network of Networks (NRC, 2009b), cited four types of observations as the 

“highest priority observations needed to address current inadequacies,” all of which are 

relevant for air quality monitoring:

 Height of the planetary boundary layer

 Soil moisture and temperature profiles

 High-resolution vertical profiles of humidity

 Measurements of air quality and related chemical composition above the 

surface layer.

Uses of Air Quality Observations

The air quality observation systems discussed in this report serve four broad disciplines: 

(1) human exposure and health effects, (2) ecosystem exposure and effects, (3) air 

quality management efforts, and (4) basic atmospheric science, including linkages 

between air quality and climate change. Although disciplines (1) and (2) are described in 

general terms below, this report does not attempt to elucidate the major needs or gaps 

of U.S. observation programs focused specifically on human exposure and health effects 

or ecosystem impacts—including studies of physical or chemical properties of aquatic 

and terrestrial systems—which generally need especially high-resolution data over 

multiple observational axes. 

Human Exposure and Health Effects

Relating health effects to observed concentrations of pollutants is a critical use of air 

quality observations. Forecasting of future air quality conditions allows the general 

public, particularly sensitive groups, to modify behavior and protect their health by 

reducing potential exposure to poor air quality. Verification and improvement of model 

predictions and interpretative forecasts relies on timely availability of accurate and 

precise observations. In addition to surface observations of criteria pollutants, such as 

ozone and particulate matter, measurements of their precursors, particulate matter 

composition, and the vertical distribution of pollutants are needed to improve model 

predictions. 
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Many epidemiological studies of the health effects of air pollution use data from existing 

monitoring networks. For example, Pope et al. (2009) used measurements from EPA 

monitoring networks to show that decreases in PM2.5 concentrations lead to increased 

life expectancy. In general, however, the use of existing monitoring networks for 

epidemiological studies of air pollution poses challenges. Monitoring networks typically 

involve air quality observations from relatively small numbers of instruments in 

metropolitan areas, placed in areas that may not capture the full range of 

concentrations to which people within the area are exposed. Likewise, monitoring 

networks of criteria pollutants are designed to provide pollutant levels over an 

averaging time defined by the National Ambient Air Quality Standards (NAAQS), which 

can prove limiting for some health studies. 

For measurements not directly related to compliance with air quality standards, such as 

air toxics or speciation of particulate matter, the frequency of measurements can be 

considerably lower than ideal for epidemiological studies. 

Further, when data from an existing monitoring network are used to study health 

effects, the research is limited to the chemical species being measured by the network, 

as well as by pre-determined measurement periods and spatial coverage. 

It is important to note that health impacts are the primary inputs into the evolution of 

NAAQS, which in turn influence monitoring design. Other types of health impacts 

research (e.g., for air toxics) complement the epidemiological studies that use ambient 

monitors, but the inter-relationship of the monitoring design and health effects studies 

illustrates the need for careful design of ambient monitoring programs. This network 

design should generally consider the same scale (e.g., local, regional) as the 

epidemiology studies used to set the health-based standards.

Ecosystem Exposure and Effects

Atmospheric observations are a major part of ecological effects assessment efforts, 

either directly or through air quality models. Watershed acidification, eutrophication, 

and direct damage to vegetation are examples of major ecosystem welfare issues whose 

understanding can be enhanced by atmospheric characterization studies. The ecosystem 

assessment community is an important client of air quality observations, using available 

data as inputs to ecosystem exposure models and as trend indicators relating the 

effectiveness of emissions strategies on atmospheric deposition. The characterization 

demands for ecosystem analyses may be as demanding as those associated with human 

health and exposure communities, given the spatial heterogeneity of vegetation, soil 

types, and microclimates within and across watersheds and ecosystems that affect, and 

are affected by, atmospheric deposition. Furthermore, most U.S. monitoring stations 

are distributed according to population-weighted criteria, creating major information 

gaps in sensitive ecosystems. 
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Air Quality Management Efforts

Air quality management practice includes the establishment of human and ecosystem 

health-based standards and the subsequent development of rules, programs, and 

implementation steps designed to achieve the emission changes needed to meet air 

quality targets. The cyclic nature of air quality management reflects both the evolution 

of air quality standards (based on improving knowledge of the effects of air pollution) 

and evaluation of whether implemented programs produced intended results. In recent 

years, air quality management has sought more direct evidence of the connections 

along the source-to-effects continuum, and of the relationship between emissions 

changes and air quality improvements, to better assess the effectiveness of emissions 

strategies. 

The regulatory nature of air quality management decisions places special demands on 

the observations used to support this work. Ambient monitoring of criteria air pollutants 

such as ozone, particulate matter, etc., is designed to be used to determine if an area is 

compliant with a specified NAAQS. Only certified measurements from Federal Reference 

or Equivalent Methods (FRM/FEM) can be used for comparison to the NAAQS. However, 

FRM/FEMs have not been established for toxic air pollutants, in part because the 

regulatory structure of the Clean Air Act (CAA) does not require ambient monitoring for 

these pollutants. In practice, the reliance on FRM/FEM certification and a lack of 

regulatory drivers has hindered development and commercialization of potentially 

useful air quality monitoring technologies. 

Basic Atmospheric Science, Including Linkages between Air Quality and Climate Change

Air quality data can improve the characterization of physical and chemical processes 

underlying pollutant release, transformation, and removal and can inform the 

development, evaluation, and refinement of quantitative atmospheric chemistry 

models. Such models, in turn, can be critical to air quality management efforts and to 

assessments of air quality on health, ecosystems, and climate. And while models are 

essential for making predictions, such as air quality forecasts, climate predictions, and 

estimated impacts of future emissions changes, they are also key to characterizing the 

multi-dimensional (space, time, and species) chemical state of the current atmosphere 

and to understanding historical conditions. 
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Overview of Observation Programs

A variety of measurement programs support air quality assessments. These include:

 routine regulatory and deposition networks

 intensive aircraft and ground-based field studies

 radiosonde programs

 satellite measurements

 ground-based remote-sensing networks

 focused, fixed-site, special purpose networks

The following inventory of representative programs is not intended to be 

comprehensive but focuses on extant, routinely operating North American networks, 

with some mention of European and international efforts relevant to North American 

assessments. More detailed information is available in the appendices.

Routine Surface-Based Ambient Air and Deposition Networks 

Routine ambient air and deposition monitoring networks in North America comprise 

more than 3000 fixed platforms (Figure 1), measuring numerous gaseous species and 

aerosol properties (Appendices B and C). Many of these longstanding U.S. networks 

were required or catalyzed by the 1970 Clean Air Act (CAA), subsequent CAA 

amendments, National Ambient Air Quality Standard (NAAQS) reviews, and/or National 

Academy of Sciences (NAS) recommendations. Examples include the Clean Air Status 

and Trends Network (CASTNET) and National Atmospheric Deposition Program (NADP) 

addressing acidification; the Photochemical Assessment Monitoring Stations (PAMS) in 

response to persistent ozone pollution; and the PM2.5 monitoring networks following 

promulgation of the 1997 NAAQS. Federal regulations describe how sites in these 

networks are to be located, and the Federal Reference Methods (FRM) or Federal 

Equivalent Methods (FEM) for the measurements made at many of the required sites. 

Most routine air quality monitoring stations in the United States are owned and 

operated by nearly 300 state and local government and Tribal agencies. 

These state and local air monitoring stations (SLAMS) are the principal source of 

ambient measurements of the six criteria air pollutants (ozone, nitrogen dioxide, carbon 

monoxide, sulfur dioxide, lead, particulate matter - PM10 and PM2.5), each of which has 

one or more NAAQS specifying a concentration level and averaging period 

(http://www.epa.gov/ttn/naaqs/). Most of these networks also include stations 

operated by Federal agencies, typically in rural / remote sites. These networks are 

indirectly supported by extensive meteorological networks (Appendix D).

National air monitoring regulations for U.S. programs are codified in Parts 50, 53, and 58 

of Title 40 of the Code of Federal Regulations (CFR). 
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Funding for these programs is through CAA Sections 103 and 105 concerning Federal 

grants to agencies and tribes. States and local agencies are required to match Federal 

Section 105 contributions.

Figure 1. Aggregate map of the majority of routine U.S. monitoring stations, illustrating 

relatively broad coverage across the continental United States. Note spatial gaps in 

sparsely populated areas.

Criteria Gas and Ozone Precursor Monitoring

Criteria Gas Networks -- Approximately 1500 surface stations measure some combination 

of criteria gases, with nearly 1100 of these stations measuring ozone, using FRMs or 

FEMs. Several hundred monitors report concentrations for CO, SO2, and NO/NOx. The 

majority of these stations are SLAMS, although Federal agency networks such as 

CASTNET, National Park Service (NPS) monitors, and a variety of special purpose 

monitors provide additional coverage (Appendices B and C). CASTNET and NPS provide 

the majority of rural criteria pollutant platforms.
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Photochemical Assessment Monitoring Stations (PAMS) -- Approximately 75 sites in 22 

cities were deployed by state and local agencies in the early 1990s to measure ozone 

precursors, largely in response to a 1991 National Academy of Sciences study (NRC, 

1991). PAMS and the air toxics network (see below) provide the majority of routinely 

available non-methane organic carbon (NMOC) measurements. A number of ozone 

precursor C2-C10 alkanes and alkenes, aromatics, formaldehyde, and acetaldehyde are 

measured using a combination of continuous methods and sampling techniques over 3-

and 24-hour collection periods, often limited to the ozone season (April – October). The 

1990 CAA Amendments required areas classified as serious and above with respect to 

the contemporary (1990-1992) ozone NAAQS to implement PAMS, which has undergone 

minor modifications since then. Most volatile organic compound (VOC) sampling sites 

include instrumentation for O3 and NO/NOx.

Particulate Monitoring

PM2.5, PM10, and PM10-2.5 Mass Networks -- The 1997 promulgation of a fine particulate 

NAAQS (EPA, 1997) led to deployment of over 1500 PM2.5 sites (about 1000 currently), 

used to determine whether an area complies with the standard. These sites use an FRM 

or FEM, sampling over 24 hours daily, or every third or sixth day. Nearly 300 additional 

measurements not meeting FRM or FEM specifications are provided by the chemical 

speciation sites (see below). Approximately 600 stations provide indirect measurements 

of continuous (hourly resolution) PM2.5 mass, using a variety of techniques. Continuous 

PM2.5 mass measurements have been granted FEM status based on revised monitoring 

regulations issued in 2006 (EPA, 2006) that provided new approaches for demonstrating 

equivalency. 

Approximately 1000 PM10 samplers (24-hr sampling period, typically collected every 

sixth day) remain in operation. Although a PM10-2.5 standard has not been promulgated, 

EPA developed a PM10-2.5 FRM based on mass difference of concurrent PM10 and PM2.5

measurements. PM10-2.5 measurements are incorporated in the NCore network (see 

below). 

Interagency Monitoring of Protected Visual Environments (IMPROVE) Program -- The 

IMPROVE network, with over 100 sites, has provided nearly a two-decade record of 

major components of PM2.5 (sulfate, nitrate, organic and elemental carbon fractions, 

and trace metals) in pristine areas of the United States (Figure 2). IMPROVE is led by the 

National Park Service, with various other Federal and state agencies providing support 

operations. The primary focus of the network is to track visibility and trends in visibility. 

PM2.5 Chemical Speciation Monitoring -- In addition to the IMPROVE network, over 300 EPA 

speciation sites were added from the years 2000 - 2002 in urban areas of the United 

States to assist PM2.5 assessment efforts. No FRM exists for particulate speciation, which 

is not directly required to determine attainment, and there are slight differences among 

the different monitors used in the Chemical Speciation Network (CSN). 
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However, the network’s coverage (Figure 2) across urban and rural areas has proven 

essential for a wide range of research and analysis. The speciation networks typically 

collect a 24-hour sample every three, and sometimes six, days. Daily 24-hour speciation 

collection is limited to occasional efforts in the SEARCH (see below) network. Similarly, 

only a handful of sites provide near continuous speciation data, usually limited to some 

combination of sulfate, carbon (organic and elemental splits), and nitrate. This enables 

insights into diurnal speciation patterns, helpful in diagnosing various cause-effect 

phenomena related to emissions characterization, source attribution analysis, and 

model evaluation. In addition, the National Air Toxics Trends Stations (NATTS; see 

below) include near continuous aethalometer measurements based on optical 

absorption as a surrogate for absorbing aerosol (e.g., elemental carbon). 

Figure 2. Locations of chemical speciation sites delineated by program type.

SouthEastern Aerosol Research and Characterization (SEARCH) Study -- SEARCH is an 

industry-funded network that originally emerged from the Southern Oxidants Study 

(SOS) in the 1990s. It has operated for over a decade in response to 1997 revisions to 

the NAAQS for ground-level ozone and particulate matter. SEARCH provides an array of 

standard criteria pollutant measurements, in addition to daily PM speciation at selected 

times and locations, gaseous ammonia (NH3), total peroxyacetyl nitrate (PAN), nitric acid 

(HNO3), reactive oxidized nitrogen (NOy), and true nitrogen dioxide (i.e., a 

measurement of NO2 concentration unaffected by other nitrogen oxides, which 

contaminate FRM NO2 measurements). 
19

These measurements typically had not been available in major government-funded 

routine networks. Measurements of pollutant composition, as well as mass, are 

necessary in order to identify sources of ozone precursors and fine particulate matter, 

and to attribute health effects to specific components.

PM Supersites Program -- This program (Solomon et al., 2008) provided highly resolved 

aerosol measurements at eight U.S. cities for several time periods from 1999 through 

2004, with some sites collecting data after 2004. A number of instrument configurations 

were deployed, ranging from additional locations for standard speciation monitors, to 

systems capturing near-continuous size-dependent speciation profiles.

The National Core (NCore) Network 

NCore (Scheffe et al., 2009) is an 80-site multiple pollutant supplement to the routine 

monitoring networks. It was fostered by the Ambient Air Monitoring Strategy for State, 

Local, and Tribal Air Agencies (EPA, 2008), and promulgated in the 2006 Code of Federal 

Regulations as part of the new monitoring rule (EPA, 2006). NCore is designed to 

capture urban- and regional-scale representative concentrations of a variety of trace 

gases (CO, SO2, NOy, and NO) and aerosols (PM10 and PM2.5 mass and chemical 

speciation) to support a range of health effect, model evaluation, and other research 

studies. The NCore sites are designated multiple pollutant sites that require co-location 

with existing PM2.5 chemical speciation measurements. Deployment of the network took 

place through 2011. 

Air Toxics Monitoring Program

National Air Toxics Trends Stations (NATTS) Network -- State and local agencies have 

measured a variety of metallic and gaseous toxic air pollutants at over 200 locations 

since the 1980s. Broad access to and use of these data was hampered by a lack of 

centralized databases and multiple sampling and laboratory protocols, creating data 

quality and consistency concerns. To address these inconsistencies, the NATTS network 

was conceived in 2001, consisting of 27 sites. The sampling protocol typically has been 

every sixth day for 24 hours. 

Among the priority ranked 33 air toxics of U.S. concern, observations of benzene and 

other common aromatics are generally widespread and relatively reliable. However, 

other potentially important air toxics are less well represented in air monitoring. During 

the initial start-up of the NATTS, six priority pollutants (formaldehyde, benzene, 1,3-

butadiene, hexavalent chromium, acrolein, and arsenic) were targeted for inclusion, 

based on results of the 1996 National Air Toxics Assessment (NATA; 

http://www.epa.gov/ttn/atw/natamain/index.html). 
20

Building on efficiencies in methodologies and the 1999 and 2002 NATAs, NATTS 

observations expanded to include the following:

 Gas-phase compounds: acetaldehyde, acrolein, benzene, carbon tetrachloride, 

chloroform, dichloropropane, dichloromethane, formaldehyde, naphthalene, 

perchloroethylene, trichloroethylene, vinyl chloride, and 1,3-butadiene. 

 Metals in PM10: nickel, arsenic, cadmium, manganese, beryllium, and lead. 

 Total suspended particle (TSP) mass: hexavalent chromium.

 Combined gas-phase and TSP: naphthalene and benzo(a)pyrene. 

 Light absorbing carbon through aethalometers at a subset of sites.

In 2009, the EPA initiated a school air toxics study (http://www.epa.gov/schoolair/) to 

sample and analyze for a variety of hazardous air pollutants (HAPs; “air toxics”) at 63 

schools in 22 states. The Integrated Atmospheric Deposition Network (IADN) program 

(see below) also analyzes for selected metals (As, Pb, Cd, and Se) and other air toxics, 

while the National Atmospheric Deposition Program (NADP) includes mercury (Hg) 

monitoring in some sites. These programs are discussed below. The spatial and 

temporal patterns of many HAPs have strong localized signals associated with near field 

source emissions. 

This makes characterization of air toxics concentrations especially challenging, given 

both the number of chemical species of concern and the difficulty in accounting for 

impacts of a myriad of emission sources. Consequently, the U.S. EPA has primarily relied 

on air quality modeling to communicate risks associated with air toxics in the NATA 

reports.

Deposition Networks

Precipitation-Based Networks: NADP and IADN -- Precipitation chemistry is an important 

link between the atmosphere and terrestrial and aquatic systems. The National 

Atmospheric Deposition Program (NADP) currently consists of five subnetworks. Two of 

these subnetworks, the National Trends Network (NTN) and the Atmospheric Integrated 

Research Monitoring Network (AIRMoN), oversee approximately 250 sites that analyze 

for ions that have significant acidification and eutrophication effects. AIRMoN provides 

precipitation samples that facilitate temporal resolution. NTN data have described 

trends in precipitation chemistry across the United States since about 1978.

Two additional NADP subnetworks measure mercury. The Mercury Deposition Network 

(MDN) includes over 90 sites that measure total mercury in precipitation. The 

Atmospheric Mercury Network (AMNet) provides data on the atmospheric 

concentrations of mercury in gaseous and particulate forms, and other data needed to 

estimate dry deposition at twenty sites across North America. Monitoring mercury in 

the atmosphere is important for model evaluation and tracking the atmospheric 

response to emissions reductions. 
21

AMNet, which began as a pilot partnership networking and standardizing previously 

deployed instruments, was formally adopted by NADP in 2009. The joint CanadianUnited States Integrated Atmospheric Deposition Network (IADN) includes a mix of 

stations across the Great Lakes that sample both precipitation and ambient air for a 

range of toxic compounds. IADN emphasizes measurement of many of the more 

persistent organic compounds, including polychlorinated biphenyls (PCBs), pesticides, 

dioxins, and toxic metals (lead, cadmium, arsenic, and selenium).

Clean Air Status and Trends Network (CASTNET) -- CASTNET was established in the early 

1990s to track changes in dry deposition of major inorganic ions (nitrate and sulfate) 

and gaseous precursors associated with CAA Title 4 reductions in sulfur and nitrogen, 

designed to address surface water acidification in eastern North America. The network 

of over 80 sites has expanded from an eastern United States focus to cover large areas 

in the West. CASTNET provides weekly averaged ambient measurements of major ions 

(sulfate, nitrate, and ammonium) and gaseous sulfur dioxide and nitric acid. A subset of 

sites includes ozone and IMPROVE PM2.5 speciation instruments. CASTNET site locations 

were designed to reflect regional scale air mass samples, relatively free from local urban 

source signals. The ambient concentrations are used in algorithms that estimate 

deposition velocity to calculate dry deposition.

The Ammonia Monitoring Network (AMoN) is the only network providing a consistent, 

long-term record of ammonia gas concentrations across the United States. AMoN is an 

approved NADP network and uses passive samplers collecting weekly integrated 

measurements, located at nearly 50 of the CASTNET locations.

Other Air Monitoring Networks

For completeness, European air monitoring networks and national/international 

networks for monitoring persistent organic pollutants (POPs) are listed respectively in 

Appendices E and F.

Accessing Surface Network Data

Access to routine measurements is available through the following portals:

 EPA’s Air Quality System (http://www.epa.gov/ttn/airs/airsaqs/) and related 

DataMart (http://www.epa.gov/ttn/airs/aqsdatamart/) house criteria gas, PAMS, 

PM mass, PM speciation, and air toxics data.

 EPA’s AIRNow (http://www.airnow.gov/) and AIRNowTech 

(http://www.airnowtech.org/) provide near real time access to ozone and 

continuous PM2.5 mass data.

 VIEWS (Visualization Information Exchange Web System -

http://vista.cira.colostate.edu/views/ developed by the Regional Planning 

Organizations (RPOs) in support of visibility assessments) houses IMPROVE and 

EPA PM2.5 speciation data.
22

 CASTNET (http://www.epa.gov/castnet/), NADP (http://nadp.sws.uiuc.edu/), 

and IADN (http://www.epa.gov/glnpo/monitoring/air2/index.html) provide 

direct access to deposition data. NADP data includes sub-networks (NTN, MDN, 

AMNet, AMoN) and AIRMoN (http://nadp.sws.uiuc.edu/airmon/). 

 The Health Effects Institute (HEI) air quality database provides access to, and 

analysis tools for, processed PM2.5 chemical speciation data 

(http://www.healtheffects.org/research.htm).

 Supersites Integrated Relational Database (SIRD) is described at 

http://www.epa.gov/ttn/amtic/ssdatamg.html.

 SouthEastern Aerosol Research and CHaracterization (SEARCH) is described and 

data availability identified at 

http://www.atmospheric-research.com/studies/SEARCH/index.html.

 Interagency Real-Time Smoke Particulate Monitoring provides real-time smoke 

concentration data (along with other meteorological information) from portable 

smoke monitors, and is described at http://app.airsis.com/USFS/.

Intensive Field Campaigns

Intensive field campaigns (Appendix G) of relatively short duration supplement routine 

long term monitoring networks by measuring spatial, temporal, and compositional 

distribution of pollutants and precursors. 

These studies are designed to investigate the emission and physical and chemical 

processing of precursors and pollutants to understand their source, fate, transport, and 

removal. Typically, field campaigns use some combination of aircraft- and/or ship-based 

studies, satellite- and ground-based remote sensing, research-grade instrumentation, 

and advanced analytical methods. These efforts complement routine ground-based 

measurements, which usually do not address reactive gaseous species, aerosol size 

distributions, organic chemistry characterization, and vertically stratified data. 

There is a long history of intensive field campaigns, starting with the Regional Air 

Pollution Study (RAPS) in the 1970s which formed the basis for evaluating the early 

photochemical models used in ozone assessments. Landmark campaigns in the United 

States through the 1980s and 1990s were reviewed as part of the 2000 NARSTO ozone 

assessment (Solomon et al, 2000), including the Southern California Air Quality Study, 

the San Joaquin Valley Air Quality Study (SJAQS)/Atmospheric Utility Signatures, 

Predictions, and EXperiments (AUSPEX), and the Southern Oxidant Study (SOS). Over the 

last decade, there has been a series of field campaigns focusing on characterization of 

surface-level aerosols through the PM Supersites program (Solomon et al., 2008). 

While early campaigns focused on urban environments, the Eulerian Model Evaluation 

Field Study (EMEFS) and SOS during the early 1990s shifted the focus toward regional 

spatial scales. This was consistent with the dominant air pollution concerns of the time, 

notably acid rain and ozone. 
23

In addition to addressing urban areas of concern, such as Houston and Los Angeles, 

more recent campaigns have extended spatial scales beyond regional studies to address 

long-range transport and continental-scale atmospheric processes. Some of these 

campaigns include local and regional studies for the northeast and southeast United 

States, portions of Texas, and central and southern California, and intercontinental 

studies of transport across North America and the Atlantic, Pacific, and Indian Oceans. A 

variety of Federal agencies (particularly NOAA and NASA) and state entities have served 

as leads for these studies. Appendix G provides a listing of key studies conducted since 

the late 1990s, with important earlier campaigns identified in footnotes. Several recent, 

highly relevant, campaigns are briefly described below.

The Intercontinental Transport and Chemical Transformations project of 2002 (ITCT-2k2) 

investigated springtime transport along the Pacific coast of North America. The 

campaign combined ground- and aircraft-based measurements with model simulations 

and satellite data products. The focus was on tropospheric chemistry and transport of 

ozone, fine particles, and chemically-active greenhouse compounds. The study shed 

light on the intercontinental transport of ozone and aerosols, and the impacts this 

transport has on local air quality and climate.

In 2004, the International Consortium for Atmospheric Research on Transport and 

Transformation (ICARTT) served as an organizing umbrella for North American and 

European field campaigns addressing regional scale processes in both continents, as well 

as trans-Atlantic transport phenomena (Fehsenfeld et al., 2006). The North American 

studies included the Intercontinental Chemical Transport Experiment - North America 

(INTEX-NA 2004) and the New England Air Quality Study - Intercontinental Transport 

and Chemical Transformation (NEAQS – ITCT 2004) programs. Analysis was based on a 

variety of satellite, aircraft, ship-based, and ground-based measurements. The ICARTT 

campaigns provided insights into trans-Atlantic processing of ozone precursors, 

lightning-generated NOx emissions, secondary organic aerosol processes, and biomass 

burning.

The ICARTT campaigns had been preceded by the North American Regional Experiment 

(NARE) in the 1990s, which studied synoptic scale transport in the North Atlantic 

(Fehsenfeld et al., 1996; Penkett et al., 1998). The Transport and Chemical Evolution 

over the Pacific (TRACE-P) campaign of 2001 catalyzed much of our current 

understanding of Asian outflow to North America. The INTEX-NA mission was followed 

by the 2006 Intercontinental Chemical Transport Experiment (Phase B) (INTEX-B) aircraft 

mission, which studied pollutant transport flow across the north Pacific and into the 

western United States. INTEX-B was also linked with the 2006 Megacity Initiative: Local 

and Global Research Observations (MILAGRO) mission, which studied pollutant outflow 

from Mexico City. Most of the large intercontinental scale field campaigns are 

considered key parts of the IGAC program (Appendix A). Findings specific to Northern 

Hemisphere transport have been synthesized by the Hemispheric Transport of Air 

Pollution (HTAP) task force (Keating and Zuber, 2007). 
24

The Texas Air Quality Study (TexAQS and TexAQS II) during 2000 and 2006 involved 

intensive research campaigns designed to address some of the unique VOC chemistry 

and transport features of southeastern Texas. The 2006 program extended the earlier 

study to address climate-air quality linkages and probe nighttime NOx and NOy 

chemistry.

The Bay Region Atmospheric Chemistry Experiment (BRACE) was conceived in response 

to persistent increasing trends of nitrogen oxide emissions in Florida, in order to assess 

potential effects on air quality and the ecological health of Tampa Bay and its 

surroundings. BRACE began in 2000 and has included both long-term and short-term 

intensive measurement campaigns, focusing on assessment of atmospheric nitrogen 

deposition to Tampa Bay. This program helped develop modeling approaches for 

numerous eastern U.S. estuaries, and has been augmented by additional field 

campaigns elsewhere, most notably in eastern North Carolina. Key participants included 

the Florida Department of Environmental Protection, Tampa Bay Electric Company, EPA, 

NOAA, Argonne National Laboratory, numerous universities, and several additional 

Florida state agencies.

The PM Supersites program complemented routine PM2.5 monitoring by deploying 

research instrumentation in intensive field campaigns to obtain highly time-resolved 

data on multiple aerosol physical and chemical properties in major U.S. cities (Atlanta, 

Baltimore, Fresno, Houston, Los Angeles, Pittsburgh, St. Louis, and New York). 

These data sets, spanning portions of 1999 – 2004 with some sites operating in later 

years, addressed three primary objectives: development of monitoring methods and 

transfer to operational agencies; support for health effects research; and State 

Implementation Plan (SIP) development. Several findings are synthesized in dedicated 

special journal issues (Pandis et al., 2005; Geller and Solomon, 2006; Solomon et al., 

2008). 

The Los Angeles Supersite and the Southern California Particle Matter Center spawned 

interest in near-roadway characterizations by providing measurements of particles near 

highways, particularly ultrafine particle numbers. This work showed very high particle 

concentrations near the highway (Zhu et al., 2002), with concentrations decreasing and 

size distributions changing with increased distance from the roadway. Near-roadway 

studies have since been undertaken, primarily by EPA, in several other cities, including 

Detroit, Raleigh, and Las Vegas. Near-roadway measurements and studies provide an 

important bridge between atmospheric and health sciences, given the combination of 

highly variable pollutant concentrations in populated locations. The EPA is developing 

technical requirements for monitoring to improve the understanding of exposures in 

near roadway environments.

The Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models of 

Climate Chemistry, Aerosols, and Transport (POLARCAT) was a coordinated international 

series of field studies conducted as part of the International Polar Year 2007-2008 (IPY). 
25

Under this activity, NASA led the 2008 Arctic Research of the Composition of the 

Troposphere from Aircraft and Satellites (ARCTAS) project, largely based in Canada. This 

field study addressed a variety of issues impacting the Arctic atmosphere, including 

Eurasian and North American fires, halogen chemistry, light absorbing carbon, and 

persistent pollutants. Prior to ARCTAS deployment in Canada, NASA had conducted a 

series of flights with scientists from the California Air Resources Board (CARB). 

These flights, already configured for the ARCTAS mission, examined California’s 

atmosphere to better understand the chemical dynamics of smog and greenhouse gases 

over the state. 

NOAA also led two field studies as part of the IPY: Aerosol, Radiation, and Cloud 

Processes affecting Arctic Climate (ARCPAC) and International Chemistry Experiment in 

the Arctic LOwer Troposphere (ICEALOT). ARCPAC involved the deployment of the NOAA 

WP-3D aircraft in Alaska, and ICEALOT involved the deployment of the Woods Hole 

Research Vessel Knorr in the North Atlantic. Additionally, DOE led the Indirect and SemiDirect Aerosol Campaign (ISDAC) as part of the IPY.

The CalNex campaign took place during the spring/summer of 2010, and was designed 

to build on existing California programs that address air quality and climate linkages.

Under NASA’s Earth Venture missions in the Earth Science System Pathfinder program, 

the Deriving Information on Surface Conditions from Column and Vertically Resolved 

Observations Relevant to Air Quality (DISCOVER-AQ) mission is conducting a series of 

field missions.

The overarching objective is to use targeted airborne and ground-based observations to 

improve the interpretation of satellite observations in diagnosing near‐surface 

conditions relating to air quality. The first of the field studies was conducted over the 

greater metropolitan area of Baltimore, MD, with a complex multi-platform observing 

system, providing multiple perspectives on the factors that control air quality and 

influence the ability to monitor pollution events from space. Subsequent deployments 

were conducted in California’s San Joaquin Valley in January 2013 and Houston, Texas, 

in September 2013. The DISCOVER-AQ mission will conduct a final deployment in 

Denver, Colorado, in summer 2014. 

Field Campaign Websites

ARCTAS: http://www.espo.nasa.gov/arctas/

CalNex: http://www.esrl.noaa.gov/csd/calnex/

DISCOVER-AQ: http://discover-aq.larc.nasa.gov

ICARTT: http://www.esrl.noaa.gov/csd/ICARTT/index.shtml

INTEX-B: http://www.espo.nasa.gov/intex-b/index.html

INTEX-NA: http://cloud1.arc.nasa.gov/intex-na/

MILAGRO: http://www.eol.ucar.edu/projects/milagro/

NEAQS - ITCT 2004: http://www.esrl.noaa.gov/csd/2004/
26

POLARCAT: http://www.nilu.no/Portals/0/IMG/Forskning/NILU-Polaraaret-A4-webNY.pdf

TRACE-P: http://www-air.larc.nasa.gov/missions/tracep/tracep.htm

TexAQS & TexAQS II: http://www.esrl.noaa.gov/csd/2006/

Satellite–Based Air Quality Observations

An extensive array of satellite-based systems (Appendix H) has been established by the 

United States and European Union countries to measure total atmospheric columns and 

limited vertical profiles of several key species. In the United States, these programs are 

led by the National Aeronautics and Space Administration (NASA) and the National 

Oceanic and Atmospheric Administration (NOAA). Non-government organizations have 

also played significant roles, such as the Harvard-Smithsonian Astrophysical Laboratory 

and the National Center for Atmospheric Research (NCAR). In Europe, the satellite 

measurements relevant to air quality are part of the large Global Monitoring for 

Environmental and Security (GMES) program, now renamed Copernicus. The satellite 

component is led by the European Space Agency (ESA) and the European Organization 

for the Exploitation of Meteorological Satellites (EUMETSAT). A number of other 

national programs, beyond the U.S. and European programs, provide relevant 

measurements (listed in Appendix H). NASA and ESA typically demonstrate new 

capabilities for Earth observations, while NOAA and EUMETSAT conduct long-term 

operational observations. Under U.S. programs, a suite of satellites including Terra, 

Aqua, Aura, CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation), 

as well as NOAA-17, NOAA-18, NOAA-19, and Suomi NPP (National Polar-orbiting 

Partnership), have been launched in the last two decades. Collectively, they measure 

columns and/or profiles of aerosol optical depth (AOD), O3, H2O, CO, CH4, SO2, NO2, 

CFCs, other pollutants, and atmospheric parameters such as temperature, cloud 

properties, and water vapor. Most of these satellites have a near-polar low Earth orbit 

(LEO), passing twice per day over a given location. For many species, measurements are 

only possible during daylight, so only one measurement is made per day per instrument. 

The Earth Observing System (EOS) Afternoon Constellation, or “A-Train,” is a group of 

several of these satellites (Aqua, Aura, CALIPSO, CloudSat, and (previously) PARASOL 

(Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with 

Observations from a Lidar) that fly in formation, crossing the equator a few minutes 

apart near 1:30 PM local time. The near-simultaneous observations from these satellites 

produce a rich picture of earth weather, climate, and atmospheric conditions. The OCO 

(Orbiting Carbon Observatory) mission, which suffered a launch vehicle failure in early 

2009, was to join the A-Train to measure CO2 with the precision required to map global 

distribution of CO2 sources and sinks on regional scales. A U.S. replacement mission for 

OCO is scheduled for a July 2014 launch. In the meantime, Japan’s Greenhouse gases 

Observing Satellite (GOSAT), launched in January, 2009, is globally monitoring CO2, CH4, 

and aerosols.
27

NOAA’s National Environmental Satellite and Data Information Service (NESDIS) 

oversees operations of U.S. Geostationary and Polar-orbiting Operational Environmental 

Satellite programs (GOES and POES), providing imagery for weather forecasting and 

observations of light scattering relevant to aerosol characterizations. Under the GOES 

program, NOAA is scheduled to launch in 2016 the first of the GOES-R series of next 

generation geostationary weather satellites with the Advanced Baseline Imager (ABI). 

The ABI will provide aerosol optical depth measurements at a spatial resolution of 2 km 

every 5 minutes over the continental U.S. and Canada and, every 15 minutes, the entire 

disk of the northern and southern hemispheres. The Suomi National Polar-orbiting 

Partnership (NPP) satellite launched on October 28, 2011, with sensors such as OMPS 

(Ozone Mapping and Profiler Suite), VIIRS (Visible/Infrared Imaging Radiometer Suite), 

and CrIS (Cross-track Infrared Sounder), provides aerosol and trace gas information at 

much higher spatial resolutions than previously possible. For example, VIIRS aerosol 

optical depth and suspended matter (aerosol type) products are available at 750 m 

resolution. The joint NASA-NOAA Suomi NPP mission serves as a proving ground for the 

series of NOAA Joint Polar Satellite System (JPSS) operational satellites to be flown in 

the next two decades.

Beginning in 1995, ESA and EUMETSAT have flown a series of LEO satellites that typically 

provide measurements of these same air quality relevant species at approximately 9:30 

AM local time (Ingmann et al., 2012). Europe is planning to continue these observations 

through the mid-2020’s with the operational MetOp satellite series. Europe is also 

planning to continue and improve the data records available in the 1:30 PM orbit 

(currently provided from NASA Aura) by launching the Sentinel-5 precursor satellite 

(Veefkind at al., 2012) and Sentinel-5 missions in 2015 and 2022 respectively.

For the future, NASA and partner agencies are studying additional satellite platforms 

capable of measuring trace gases and aerosols to enhance the characterization of 

tropospheric air quality from space (NRC, 2007; Fishman et al., 2008; Fishman et al., 

2012). The National Research Council (NRC) has recommended that NASA implement a 

number of “Decadal Survey Missions” over the next decade, in addition to implementing 

the JPSS and GOES programs. 

These “Decadal Survey Missions” include the following: 

(1) The Geostationary Coastal and Air Pollution Events (GEO-CAPE) will partially 

focus on supporting air quality assessments and forecasts by measuring 

atmospheric columns with a frequency of one hour from a geostationary space 

platform.

(2) The Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) 

mission will produce global atmospheric column CO2 measurements without 

seasonal, latitudinal, or diurnal bias using simultaneous laser remote sensing.
28

(3) The Aerosols, Clouds and Ecosystems (ACE) mission will consist of a lidar for 

characterizing aerosol height and properties, and a polarimeter for determining 

aerosol types.

(4) The Global Atmospheric Composition Mission (GACM) will focus on ozone and 

related gases for intercontinental air quality and stratospheric ozone layer 

monitoring, from a LEO space platform. 

Several nations (including the United States and countries in Europe and Asia) are 

currently planning to launch geostationary satellites capable of providing a common 

suite of air quality relevant measurements (O3, NO2, HCHO, aerosol, CO, SO2, and other 

pollutant species) at hourly temporal resolution throughout daylight hours and at 5-10 

km horizontal resolution (Committee on Earth Observation Satellites [CEOS], 2011). 

Geostationary Earth Orbit (GEO) satellites provide continuous observations over one 

part of the globe. A constellation of at least three GEO satellites can together provide 

hourly near-global observations of populated regions. Such observations will bring 

revolutionary new capability for satellite monitoring of emissions and receptor 

processes (Lahoz et al., 2012). Under the European GMES (Copernicus) program, ESA 

will launch the Sentinel-4 platform in 2019. The East Asia mission, Geo-KOMPSAT 

(Geostationary Korea Multi-Purpose Satellite) is led by the Korea Aerospace Research 

Institute (KARI) and scheduled to launch in 2018. GEO-CAPE is the NASA Decadal Survey 

mission under consideration in this category. In November 2012, NASA selected the 

Tropospheric Emissions: Monitoring of Pollution (TEMPO) proposal as the first 

investigation in the new Earth Venture-Instrument mission. TEMPO provides much, but 

not all, of the capability planned for GEO-CAPE atmospheric observations. The TEMPO 

instrument will be delivered in 2017 for an anticipated 2018 launch on a geostationary 

host satellite. TEMPO will be placed in an orbit location from which it can observe much 

of North America. TEMPO and the ESA and KARI missions will each provide hourly 

measurements of ozone, aerosols, and their precursors, such as NO2, SO2, and HCHO 

over their respective regions, together providing unprecedented highly space- and timeresolved observations of the Northern Hemisphere. 

Satellite data complement surface networks and aircraft campaigns, and are essential 

tools for evaluating models and improving emissions inventories. 

There has been inter-agency cooperation between the National Institute of 

Environmental Health Sciences (NIEHS), EPA, NASA, and NOAA in exploring the use of 

satellite observations to support epidemiologic studies. Satellite observations do not 

directly correspond to in situ measurements of pollutant concentrations. Thus, the use 

of satellite data for air quality forecasting, management, health effects studies, and 

climate change assessments is complex and involves integration of models and surface 

observations. While satellites offer global or near-global coverage of several important 

species, there are basic limitations in using a space platform to effectively probe the 

lower levels of the atmosphere where pollution exposures occur. Understanding these 

limitations is important for gauging how these systems can best complement groundbased networks and support air quality management assessments. 
29

Attributes of Air Quality Satellite Data Products 

Fundamental Limitations -- Most satellite air quality observations are based on 

spectroscopic techniques using reflected, scattered, or emitted solar radiation as a 

broad source of radiation. Although the science of measuring trace gases and aerosols 

from space is relatively mature, interference related to variable surface reflectivity, 

cloud attenuation, and overlapping spectra of other chemical species require significant 

data processing and treatment. Even with this sophisticated data retrieval, data 

products will contain spatial gaps for a given time period due to cloud interference and 

other issues, such as sun glint, etc. This is particularly true for instruments in a polar 

orbit, where the instrument may see an area only one time during the daytime. For 

example, aerosol events occurring at the same time as clouds are often screened as a 

result of cloud fractions being too high to produce an accurate aerosol optical depth 

(AOD) product for NASA’s Moderate Resolution Imaging Spectroradiometers (MODIS) 

aboard the Aqua and Terra satellites. 

Most satellite sensors sum over the entire column of air from satellite to ground, 

providing total column densities of trace gases or aerosols, whereas concentrations near 

the surface are used to define air quality. Some information on the vertical distribution 

of certain species can be obtained by using multiple observing angles for instruments in 

LEO, by limb sounding, active sensing, or other methods. For example, CALIOP aboard 

the CALIPSO satellite resolves aerosol vertical distributions every 30 meters. It is 

important to note that, for certain important trace gases (e.g., NO2, SO2, and HCHO) and 

aerosols, the majority of mass resides in the boundary layer of the lower troposphere, 

enabling associations linking column data to surface concentrations or emissions fields. 

In the eastern United States, reasonable correlations (Engel-Cox et al., 2004) have been 

developed between concentrations from ground level PM2.5 stations and MODIS AOD 

using a fixed relationship. In the western United States, correlations are poor due to 

excessive surface light scattering from the relatively barren land surfaces. To better 

account for aerosols aloft, output from a chemical transport model has been applied to 

develop concentrations of PM2.5 from MISR AOD (Liu et al., 2004). 

In contrast to aerosols, most ozone resides in the stratosphere. Various techniques have 

been developed to extract the stratospheric signal to yield a tropospheric ozone residual 

(TOR), based on known homogeneities in the stratosphere and the use of chemical 

transport models and multiple measurements. Early approaches (Fishman, 1978), 

before and during the Total Ozone Mapping Spectrometer (TOMS) missions, combined 

limb (angled view to characterize the stratosphere) and nadir (downward view, 

characterizing the total column) techniques to derive tropospheric ozone residuals. The 

2004 launch of NASA’s Aura mission, with multiple ozone sensors, is starting to produce 

more refined tropospheric ozone maps. For example, direct derivation of tropospheric 

column ozone is possible from the Ozone Monitoring Instrument (OMI) on Aura (Liu et 

al., 2009). However, differentiating ozone in the boundary layer from that in the free 

troposphere continues to pose significant challenges. 
30

This difficulty stems from strong molecular scattering of UV radiation in the boundary 

layer, and surface emission in the thermal IR range. Notably, the geostationary TEMPO 

instrument will make ozone measurements in both UV and visible (Chappuis-band) 

wavelengths to provide improved sensitivity to ozone in the boundary layer using 

multispectral retrievals.

Temporal Coverage -- The near polar orbiting tracks of most LEO satellites deliver at most 

twice daily snapshot measurements of trace gas species (approximately 12 hours apart). 

Measurements of many species can only be taken once during the single daytime 

overpass. Consequently, these instruments can only observe temporal patterns of 

pollutants or time-integrations of pollutant concentrations at daily or longer scales. 

Furthermore, instruments in LEO have only a short exposure to each Earth scene, 

limiting the signal-to-noise ratio. For many LEO products, observations for a given day 

are quite noisy, and weekly or monthly averages are more typically used. Geostationary 

(GEO) satellite platforms, such as the NOAA GOES systems 

(http://www.oso.noaa.gov/goes/index.htm), do provide near-continuous monitoring of 

physical parameters for weather tracking and forecasting purposes. The ability of a GEO 

instrument to observe an area for longer time periods potentially enables a sufficient 

signal-to-noise ratio to make short time period observations meaningful, on the order of 

one hour. TEMPO will provide the first-ever observations of tropospheric ozone and its 

precursors over North America from geostationary orbit.

Spatial Coverage -- Polar orbiting satellites typically provide horizontal spatial resolution 

between 10 and 100 km for atmospheric composition. Spatial resolution less than 10 km 

is possible with GEO and LEO platforms. Satellite observations of pollutants above the 

surface complement ground-based in-situ measurement networks – especially 

considering that a considerable fraction of pollutant mass resides well above the Earth’s 

surface. As noted above, the sensitivity of satellites to pollutants at elevated heights can 

obscure measurements of the boundary layer, and, in general, satellite data products 

contain little or no information about the vertical distribution of pollutants. 

Furthermore, one technique used to obtain vertical distribution information, the 

comparison of nadir and limb observations, is usable from GEO only if complementary 

limb observations are available from one or more polar orbiting satellites. The 

limitations of satellite data are further enumerated and elaborated (Vijayaraghavan et 

al., 2007) for the Global Ozone Monitoring Experiments (GOME) sensors for O3, NO2, 

and HCHO. 

Measuring near‐surface pollution is one of the most challenging problems for Earth 

observations from space. The NASA DISCOVER-AQ missions (2011-2014) are expected to 

help address this issue, along with some of the fundamental limitations discussed 

above. These missions are anticipated to help bridge the existing knowledge gap limiting 

the relevance of satellite observations to air quality. At the same time, they will provide 

insights into the potential benefits of higher time and space resolved measurements, as 

anticipated by GEO platforms. 
31

Current Use of Satellite Data in Air Quality Management

In broad terms, satellite measurements serve as complements to other surface-based 

and aircraft measurement programs and air quality models. Satellite applications for air 

quality forecasting and assessments are covered extensively in the published literature 

(Martin, 2008; Fishman et al., 2008; Vijayaraghavan et al., 2007). The following summary 

describes how these data are most effectively incorporated in air quality assessments, 

albeit not capturing the full breadth of applications of satellite observations. Four 

general methods are applied in the use of satellite observations for air quality 

assessments: 

Detecting Evidence of Long-Range Transport -- Satellite data support assessments of air 

quality on hemispheric and global scales, and assessments of long-range transport. 

These are projected to be of increasing importance to North American air quality 

management. Trans-oceanic air pollution transport can be observed with satellites, and 

direct observational evidence of this phenomenon has been clearly visible in satellite 

imagery (Figure 3).

Figure 3. Panels capturing trans-Atlantic transport. Top: summer 1997 tropospheric 

ozone from GOME (Liu et al., 2006). Middle: CO column totals from MOPITT for July 

2004 (Pfister et al., 2005). Bottom: Tropospheric NO2 from SCIAMACHY for summer 

2004 (Martin et al., 2006).

Characterizing Emissions and Air Quality Model Support -- Satellite observations play an 

important role in emissions characterization, particularly for source regions and sectors 

that have inadequate bottom-up inventories. 

Dobson Units
32

Applications include improving inventories from poorly-characterized, developing 

regions in Asia, and from “natural” sources such as lightning and soil NOx, biogenically 

emitted VOCs, wildfire particulate matter emissions, and agricultural based 

ammonia/NH3. 

The location and source strength of wildfire plumes detected from space serve as 

important inputs for annual emissions inventories (Martin et al., 2006; Soja et al., 2009) 

used in EPA air quality models, such as the Community Multiscale Air Quality Model 

(CMAQ), and processed as part of EPA’s National Emissions Inventory. Satellite-based 

NO2 (Wang et al., 2010) and SO2 (Lu et al., 2010) data have illustrated the dramatic 

increases in Asian NOx and SOx emissions over the last decade. Increasing NOx and SOx 

emissions associated with gas and oil extraction from 2005 - 2010 in the Canadian oil 

sands have been identified by satellite NO2 and SO2 observations (McLinden et al., 

2012). Biogenic VOC emission estimates have also been developed (Millet et al., 2008) 

using satellite measurements of formaldehyde, an oxidized product of directly-emitted 

isoprene. Advances in processing NH3 signals from the Tropospheric Emission 

Spectrometer (TES) have led to improved spatial and temporal characterization of NH3

surface patterns (Pinder et al., 2011), affording a potentially valuable tool to improve 

emissions estimates and evaluate models for sparsely measured air pollutants at the 

surface. 

Air quality management depends on models for complex environmental 

characterizations that cannot be achieved through observations alone. Satellite-based 

enhancements to surface monitoring networks support the evaluation of these models 

by inter-comparison and improving emission inventories. Inverse modeling (the process 

of using a chemistry transport model (CTM) to estimate the emissions that reproduce 

the satellite observations) is frequently used in deriving "top-down" emissions that can 

improve and update emissions estimates from "bottom-up" inventories. Satellite 

observations of tropospheric ozone can be used as the basis for boundary condition 

inputs to regional air quality models. Satellite (OMI, GOME, and GOME-2) observations 

of NO2 and HCHO can also be used to diagnose the sensitivity of ozone production to 

NOx or VOCs (Martin et al., 2004; Duncan et al., 2010).

Sustained long-term satellite observations support accountability analyses of the 

efficacy of environmental regulations. Due to a lack of surface-based true NO2

measurements, satellite observations have been the most useful indicators of progress 

in the NOx State Implementation Plan (SIP) Call for Revision (Figure 4). Similarly, 

substantial declines in SO2 emissions from coal power production facilities in the Eastern 

United States from 2005–2010, implemented through various cap and trade rules for 

major emission sources, are well correlated with satellite-derived, observed, SO2 trends 

(Fioletov et al., 2011). A particular advantage of satellite observations is their ability to 

provide an abundance of observations with the same methodology across all locations 

on the planet. Consequently, global views emerge of pollutant trends capturing United 

States and European progress in emissions abatement, contrasted with emissions 

growth due to industrial expansion in Asia and elsewhere (Figure 5). 
33

These success stories of infusing satellite observations into air quality assessments are 

notable as many of these “natural” and international emission source areas constitute a 

substantial fraction of atmospheric mass loadings that historically were generated 

without the benefit of an observation based evaluation component.

Serving as Surrogates to Filling Gaps in Surface Network -- Satellite observations are 

assisting the air quality community by providing data that cover broad spatial areas 

lacking ground-based monitors and, more importantly, a vertical (or column) 

complement to surface-based networks (Al-Saadi et al., 2005). Although ‘breathingzone’ monitoring is essential, most pollutant mass resides outside the domain of surface 

stations. Pollutant levels aloft often correlate well with surface conditions during wellmixed afternoon conditions in stable pressure systems. This offers the potential for “gap 

filling” in the surface-based networks (Figure 6). However, the appeal of satellite 

observations to fill gaps in surface measurement must be tempered by the limitations of 

using space-based measurements to characterize near surface conditions. 

 

Figure 4. Percentage difference (July 2008 minus July 2005) in satellite-derived 

tropospheric NO2 column amounts. Satellite data provide measurements that can be 

compared over large domains, suitable for trends analysis (Neil et al., 2009).
34

Figure 5. Percentage differences (2010 – 2005) in satellite-derived tropospheric 

NO2 column amounts based on OMI observations following the methodology of Lamsal 

et al., (2011).

 

Figure 6. Correlation Coefficient between MODIS Aerosol Optical Depth (AOD) and 

hourly PM2.5 surface sites from April - September, 2002 (Engel-Cox et al., 2004).
35

Providing Support During Episodes and Forecasting Air Quality -- Fire and dust events 

can produce atypically bad air quality in areas that do not usually experience poor air 

quality. Satellite data have played an important role in "exceptional event" analyses in 

determining attainment of the National Ambient Air Quality Standards. Satellite data 

can act as a surrogate for gaps in surface monitoring data, and the imagery can have an 

important public information role. Air quality forecast models rely on satellite data for 

verification (Al-Saadi et al., 2005; Kondragunta et al., 2008), offering the potential for 

assimilating aerosol and ozone gaseous precursor satellite data to constrain model 

predictions in field studies and next day air quality (Mathur, 2008; Pierce et al., 2009). 

Observation Programs for Climate, Background Concentrations, Stratospheric Ozone, and 

Long-Range Pollutant Transport

NOAA and NASA are the lead Federal agencies for a variety of observation programs 

focused on climate change, background concentrations of trace gases in areas free of 

large local sources, stratospheric ozone, and pollutant transport. These data systems 

and networks include surface measurements, vertical profiling, and measurements of 

atmospheric columns (Appendix I). The Department of Energy (DOE) is also engaged in 

observation programs addressing climate change. Many of these observation programs 

rely on partnerships across U.S. Federal agencies and collaborations with international 

organizations, such as the World Meteorological Organization (WMO). 

This section focuses on observation networks in the United States, which are largely the 

responsibility of NOAA, NASA, and DOE, with various levels of participation from partner 

agencies. The assortment of gases and aerosols that are important climate moderators 

and/or key air quality indicator and precursor species include: CO2, N2O, H2O, CH4, O3, 

CO, aerosols, and halogenated compounds, including CFC replacements. 

Greenhouse Gas (GHG) Observation Systems

NOAA, NASA, and DOE are lead Federal agencies for several programs addressing 

greenhouse gas trends, sources, sinks, and fluxes, many in partnership with each other 

and with international organizations. Although these programs are focused on carbon 

dioxide budgets, other important GHGs are included where feasible. In particular, 

methane (CH4) acts as a strong climate forcing gas and influences global background 

levels of tropospheric ozone (West et al., 2007). The major GHG observation programs 

with sites in the United States include:

NOAA Global Cooperative Air Sampling Network -- This cooperative network includes over 

100 remotely located surface stations worldwide, and a series of ship routes. Weekly 

samples from this network are used to determine global CO2, N2O, CH4, and CFC 

concentration trends. 

AmeriFlux Network -- DOE coordinates a multi-Federal agency group (with NOAA, USDA, 

NSF) overseeing the AmeriFlux network of ~90 active sites in the United States. 
36

The network sites are largely micrometeorological towers ranging from a few to 

hundreds of meters in height. Each tower is instrumented with a fast CO2 monitor and 

wind sensors, allowing calculation of the flux of CO2 between the surface, vegetation, 

and the atmosphere. AmeriFlux is a component of the worldwide Fluxnet system of CO2

flux networks, tracking storage of carbon in terrestrial systems 

(http://www.fluxnet.ornl.gov/fluxnet/index.cfm). The emerging NEON (National 

Ecological Observatory Network; http://www.neoninc.org/science/domains) is an NSF 

supported program that will provide 62 sites across the U.S., some of which are colocated with AMERIFLUX sites.

Vertical Profile, Atmospheric Column, and Satellite Observations -- The NOAA network of 8 

tall towers (100 – 500 m) provides regionally representative, near-continuous, boundary 

layer measurements of CO2 and related gases. As noted in Section 2, NASA’s Orbiting 

Carbon Observatory (OCO) satellite mission was intended to be the Nation’s primary 

remote sensing platform for CO2, providing a continental and oceanic scale complement 

to ground based systems and aircraft programs. In light of OCO’s 2009 launch failure, 

and delay of a replacement mission, climate monitoring relies for the present on Japan’s 

Greenhouse Gases Observing Satellite (GOSAT). GOSAT was launched in January 2009, 

and measures CO2 and CH4 globally. Several United States and European satellite 

sensors (Aqua AIRS, NPP CrIS, and MetOp-1 IASI) also provide some profiling capabilities 

of greenhouse gases (O3, CH4, and CO2) globally. 

Monitoring of Background Air Quality and Long-Range Transport

Network of Remote (Sentinel) Surface Observation Stations -- Remote surface stations, 

located in areas relatively free from nearby sources, can characterize background 

pollutant levels, transport on regional and hemispheric scales, and boundary conditions 

for air quality models. NOAA maintains six baseline sites or surface “sentinel” stations 

designed to capture long-term trends and atmospheric background air pollutant 

concentrations (Mauna Loa, HI; Trinidad Head, CA; Barrow, AK; American Samoa; South 

Pole; and Greenland). These are part of a worldwide Global Atmospheric Watch (GAW) 

network of baseline sites coordinated by the WMO (Figure 7). 
37

Figure 7. Network of surface-based remote observatories organized through the World 

Meteorological Organization’s Global Atmospheric Watch (GAW).

NASA Fixed Site Observation Networks -- The AGAGE (Advanced Global Atmospheric Gases 

Experiment; http://agage.eas.gatech.edu/) and its predecessors (the Atmospheric Life 

Experiment, ALE, and the Global Atmospheric Gases Experiment, GAGE) monitor a 

variety of climate forcing gases, CFCs, and reactive trace gases at remote “sentinel” sites 

throughout the world.

Monitoring of Pollutants Aloft: Profiles and Total Columns

Vertical profiling and total atmospheric column measurements provide important 

complements to near surface observations. Observations aloft provide insight into 

background levels and transport phenomena, and are key metrics for model evaluation. 

It is difficult to rely on surface-based measurements to characterize these higher 

elevations because of complex near-surface deposition, removal, and 

micrometeorological processes. Programs to improve vertical profiles include a variety 

of aircraft, sondes (self-contained signal transmitters), remote sensing, tall towers, and 

special field programs. 

These are largely managed by NOAA, NASA, NSF, and DOE. Proper siting and 

measurement techniques can produce observations that support assessments of climate 

change, stratospheric ozone, baseline concentrations, and long range and regional 

transport. These approaches include sampling throughout the atmospheric column (for 

total column and vertical profiles) and, particularly for fixed surface observations, 

measurements in locations that are relatively source free. Although climate and 

stratospheric ozone depletion assessments benefit from characterizing the full 

atmospheric column through the stratosphere (~35 km), systems designed to capture 

the entire atmospheric column often have insufficient resolution or precision in the 

boundary layer (~5 km) for surface-oriented air quality assessments. 
38

NOAA Surface and Aircraft Based Air Quality Measurement Programs -- NOAA conducts a 

variety of routinely scheduled fixed-site and aircraft-based measurement programs, 

along with a series of intensive special field campaigns, to provide observations 

addressing a variety of climate, stratospheric ozone depletion, and planetary boundary 

layer air quality issues. These programs are a source of data on conditions aloft. Core 

elements of these measurement programs include:

 An ozone radiosonde network (8 sites, 4 in the United States) providing one 

day per week vertical ozone profiles with approximately 100m resolution 

from the surface through the stratosphere; 

 The Dobson ozone spectrometer network (16 station cooperative network, 11 

in the United States) providing near continuous daytime total atmospheric 

column ozone data; 

 Routine aircraft flights that characterize the vertical distribution of air 

pollutant species (O3, CO, CH4, CO2, N2O, SF6) for climate and air quality 

assessments; 

 Tall tower sites (8) that are part of the larger interagency North American 

Carbon Program (NACP), designed to characterize carbon sources, sinks, and 

removal processes. These towers are currently located throughout the 

continental United States using television and cell phone towers (100 – 500 m 

tall). They provide near-continuous regionally representative boundary layer 

measurements of CO2, CO, CH4, and associated fluxes, various trace gases, and 

meteorological parameters 

(http://www.esrl.noaa.gov/gmd/ccgg/towers/index.html); 

 Special intensive studies, often in collaboration with NASA, with aircraft 

focusing on regional U.S. air quality issues, typically conducted every two 

years (Section 2) and for satellite validation.

These programs, in combination with NOAA remote surface-based measurement 

observatories (http://www.esrl.noaa.gov/gmd/about/airquality.html), provide long 

term records of baseline air quality from the surface through the stratosphere. They 

represent a substantial component of the United States’ contribution to international 

monitoring, much of which is organized through WMO’s GAW program. 

European-Based Aircraft Programs -- Two programs, MOZAIC (Measurement of OZone and 

water vapour by AIrbus in-service aircraft; operated since 1994) and CARIBIC (Civil 

Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument 

Container; operated since 2004) measure air quality parameters from in-service, 

scheduled passenger aircraft based in Europe. These programs provide widely 

distributed, frequent, measurements in the upper troposphere, including over the 

Atlantic. 
39

On takeoff and landing, they provide vertical profiles over cities, including cities in North 

America. These programs provide the most extensive, routinely-collected, verticallydistributed air quality data from throughout the troposphere.

MOZAIC: http://www.iagos.fr/web/rubrique3.html

CARIBIC: http://www.caribic-atmospheric.com/

Aircraft based observation programs are transitioning to the newly initiated IAGOS (Inservice Aircraft for the Global Observing System) program, a partnership between 

European research institutions, universities, Airbus Industries, and commercial airlines 

around the world, including the United States. The purpose of IAGOS is to establish and 

operate a distributed infrastructure for long-term observations of atmospheric trace 

gases (O3, CO, CO2, CH4, NOy, NOx, H2O), particulate matter, and cloud droplet 

backscatter on a global scale. The initial fleet comprises 10 - 20 long-range in-service 

aircraft belonging to airlines based throughout the world. The data will be relevant for 

studies of air quality, long-range transport of pollution plumes, climate change, and the 

impacts of aviation on the composition of the atmosphere. The data will also be made 

available in near real-time for use by air quality forecast models, and in air quality 

modeling for environmental policy-making.

Satellite Air Quality Validation Programs -- NASA oversees the operation of several 

programs monitoring the lower atmosphere, designed to complement and evaluate 

satellite products described in Section 2. These programs generally have a broader 

hemispheric- or global-scale perspective, which often overlaps with regionally-focused 

initiatives. 

Network for the Detection of Atmospheric Composition Change (NDACC) -- The NDACC is an 

international activity focused on obtaining high quality measurements of a broad range 

of atmospheric chemical species and parameters. This network includes more than 70 

remote-sensing research stations. Originally focused on the stratosphere, with an 

emphasis on the ozone layer, the scope of the NDACC has expanded to cover both the 

stratosphere and troposphere. 

A variety of working groups operate under NDACC, each focused on a particular 

measurement or technique, including Dobson/Brewer, FTIR spectrometers, lidar, 

microwave radiometers, satellite measurements, sondes, UV/Vis spectrometers, 

spectral UV, and water vapor. This network has been in operation since 1991 

(http://www.ndsc.ncep.noaa.gov/).

Lidar Networks -- Lidar, analogous to radar, uses backscattered laser light to profile 

aerosols, gas-phase species, or other parameters, such as temperature, above a site. In 

addition to use during individual field studies, there are three fixed-site, long-term lidar 

monitoring networks in the United States. 
40

The Micro Pulse Lidar Network (MPLNET) is coordinated by NASA, and operates from 14 

stations (4 in the United States). MPLNET profiles aerosols, and most sensors are colocated with AERONET (see below). The NOAA CREST lidar network comprises four 

sensors that profile aerosols, and are operated by academic institutions in the eastern 

United States. Three of these sites can also profile water vapor. The international 

Network for the Detection of Atmospheric Composition Change (NDACC, described 

above) includes 17 lidars (3 in the United States). These networks are affiliated with a 

number of networks operating overseas in the WMO/GAW Aerosol Lidar Observation 

Network (GALION). 

Selected Meteorological Observation Systems

Two categories of above-surface meteorological systems are included here because of 

their linkage to air quality assessments. First, solar radiation networks provide estimates 

of atmospheric aerosols and various trace gases, in addition to basic data for the 

radiation components of models. Second, systems that enable estimation of the height 

of the planetary boundary layer are important for near-surface air quality analyses and 

model applications.

Solar Radiation Networks -- Full spectrum and wavelength-specific solar radiation 

measurements provide data used to characterize energy budgets for meteorological 

models, climate change assessments, and atmospheric column aerosol light scattering. 

They also serve as direct indicators of UV radiation exposure, relevant to human and 

ecosystem health and agriculture. A variety of Federal agencies have participated in 

measurement programs, including NOAA, NASA, EPA, USDA, and the National Park 

Service. 

The Aerosol Robotic Network (AERONET) is a NASA-organized, collaborative, global 

network of sun photometers providing ground-based aerosol optical depth (AOD) 

estimates used primarily to evaluate satellite aerosol measurements. NOAA’s Surface 

Radiation Budget Network (SURFRAD) is part of the global Baseline Surface Radiation 

Network (BSRN). It is an important surface complement to satellites, and is used to 

characterize surface energy balances and support a variety of global scale climate 

models. 

The Brewer UV spectrophotometer networks started in 1994 with EPA’s UVNet 

program. UVNet included over 20 sites until funding ended in 2004. A subset of six sites 

supported by EPA and NOAA is operating as the NOAA-EPA Brewer Spectrophotometer 

UV and Ozone Network (NEUBrew). Brewer networks are designed to monitor UV 

radiation at the surface to understand effects on human and ecosystem health and 

agriculture. EPA has provided funding to study the relationship between changes in 

stratospheric ozone and UV at the surface. The Brewer instruments are capable of 

providing total column ozone and SO2 estimates.
41

Observations for Evaluating PBL Heights -- Planetary boundary layer (PBL) height (or mixed 

layer height) is an important physical parameter in air quality models. PBL is a derived 

quantity based largely on vertical temperature profiles and refractive index structure 

parameters. The deployment of the NOAA Profiler Network (NPN: 

http://www.profiler.noaa.gov/npn/) over the last decade has added a near-continuous 

stream of wind vector data to complement the National Weather Service’s (NWS) 

rawinsonde (radio tracked sonde) network, which provides twice daily soundings spread 

across nearly 100 locations throughout the United States. NPN consists of 35 unmanned 

Doppler radar sites profiling the troposphere, concentrated in the central United States 

and designed for forecasting violent weather. The PAMS program supports ~20 radar 

profilers that provide highly resolved wind profiles of the boundary layer. The boundary 

layer radar profilers, especially when complemented by temperature profiles generated 

by a Radio-Acoustic Sounding System (RASS), offer a source of relatively untapped data 

for model evaluation. 

Cloud base height measurements from ceilometers are also reasonable PBL depth 

indicators for non-clear sky conditions. A spatially extensive network for broad 

application is available through the NOAA Automated Surface Observing System (ASOS). 

In addition, since 2004, over 400 commercial aircraft have been collecting 

meteorological variables (temperature, pressure, relative humidity, winds) as a part of 

the Tropospheric Airborne Meteorological Data Reporting (TAMDAR) system 

(http://www.airdat.com/technology/tamdar-sensor-network/). While TAMDAR is 

designed to provide near-real-time data for forecasting, the system provides valuable 

vertical profile temperature data (and other variables) during ascents and descents. 

These data can potentially be synthesized to fill temporal and spatial gaps in groundbased profilers.

The Meteorological Assimilation Data Ingest System (MADIS - http://madis.noaa.gov/) is 

an integrated system incorporating observations from a variety of surface-based, 

vertical profile, and satellite networks. MADIS ingests data files from NOAA and nonNOAA sources, decodes the data, and then encodes all of the observations into a 

common format with uniform observation units and time stamps. These surface and 

aloft meteorological data provide a finer density, higher frequency, observational 

database for use as inputs to air quality modeling systems that are designed to 

characterize air chemistry. Air chemistry and meteorological observations are used in 

combination for diagnosing air quality model behavior.
42

Maintaining and Advancing Observation Programs

Emerging challenges in air quality management will require pollutant monitoring 

programs to become both more comprehensive – that is, they will have to fill existing 

gaps -- and more integrated. 

Measurement Gaps of Specific Species or Parameters

Nitrogen Species -- Nitrogen chemistry plays an important role in a variety of 

environmental problems, such as ozone, particulate matter, acidification, 

eutrophication, and visibility. Unfortunately, an adequate observation base does not 

exist to determine if ambient nitrogen responses are consistent with measured and 

predicted changes in NOx emissions resulting from recent regulations. The ability of the 

existing urban-oriented measurement network to detect ambient NOx changes 

associated with regional scale emission reductions from power stations is compromised 

by strong local NOx emissions. Also, NO2 data from most network NOx monitors is 

affected by other oxidized nitrogen species. The NCore network will provide a modest 

advancement by measuring reactive nitrogen (NOy) in over 70 locations and, together 

with a more stringent NO2 NAAQS (EPA, 2010), should spur greater coverage and 

deployment of instruments producing true NO2 observations. True NO2 is an important 

diagnostic species for atmospheric chemistry processes. These data are needed to 

validate satellite NO2 observations and develop scaling of column data to boundary 

layer concentrations, facilitating the use of satellite data for locations without ground 

monitors. 

Further measurements of oxidized nitrogen species, including peroxy acetyl nitrate 

(PAN) and nitric acid (HNO3), would assist diagnosis of deposition and ozone production 

during atmospheric transport. Increased use of biofuels will potentially elevate PAN 

concentrations, and, along with observations of other carbonyl compounds, PAN will be 

an important indicator of the air quality impact of new fuels. Additionally, HNO3 can be 

a key indicator species for understanding the NOx versus VOC limitation on ozone 

production in a given area.

Two reduced nitrogen species, gas-phase ammonia (NH3) and particulate ammonium 

ion, are important components of nitrogen mass balance and for assessments of 

visibility, fine particles, and ecosystem deposition. There are few ambient NH3

measurements, as most monitoring of this species occurs in strong source (agricultural) 

locations to estimate emissions flux. Also, ammonium ion is analyzed as part of the 

chemical speciation program, but NH3 volatilization creates a negative bias in those 

values.

Routine measurements of nitrate radical (NO3), the dominant nighttime oxidizer, at one 

or two representative locations would enable diagnosis of model predictions of overall 

nitrogen characterization. 
43

Nitrous acid (HONO) is an important precursor of hydroxyl radicals (Stutz et al., 2004, 

Zhou et al., 2002), which are critical in daytime atmospheric chemistry. HONO also 

reacts heterogeneously with aerosols. Its sources and chemistry are not well 

understood, and are likely to be poorly characterized in air quality models. Among these 

needs, a reasonable priority would be to enhance measurements of true NO2 and NH3 in 

our national networks. 

CO and SO2 -- The atmospheric lifetime of carbon monoxide (CO) is one to three months, 

making it a useful tracer for evaluating emissions and physical process approximations 

in air quality models. Sulfur dioxide (SO2) is the predominant precursor of sulfate, which 

is a major contributor to PM, acid precipitation, and regional haze. The available SO2 and 

CO measurements are largely urban and often in proximity to major sources, limiting 

their representativeness for broader areas. In addition, most of the current instruments 

were designed to capture high concentrations for compliance purposes, and are not 

designed to measure the lower concentrations typical of rural areas. Column amounts 

of both CO and SO2 available from sensors on current NASA research satellites are 

planned to be sustained on NOAA JPSS. In addition, the hourly CO measurements 

planned for GEO-CAPE will provide improved sensitivity to near-surface CO. The value of 

total column CO and SO2 from satellites would be enhanced by more spatially rich 

surface observations.

Mercury -- Mercury has significant impacts on ecosystems and human health, but its 

chemistry in the atmosphere remains unclear. MercNet is a planning effort organized 

through NADP to standardize and network multi-media mercury measurements. This 

network will combine existing and new monitors to the extent possible. Speciated 

mercury measurements are important for model evaluation and tracking of emission 

reduction strategies, although the existing technology presents challenges in 

transitioning from research grade instruments to routine operations.

Volatile Organic Compounds -- Biogenically generated VOCs (isoprene, terpenes, 

sesquiterpenes) contribute significantly to the formation of ozone and secondarily 

formed PM2.5. These compounds are not monitored by the urban-based PAMS or toxics 

networks, which are the primary sources of VOC data in the United States. The absence 

of VOC data in most moderately sized cities raises concerns regarding the overall 

representativeness of a network that is based primarily on the severity of ozone 

problems in the early 1990s. More troubling is the lack of rural VOC data, especially 

formaldehyde, a designated hazardous air pollutant (HAP) that is also used as a proxy 

for biogenic emissions and a useful diagnostic for model evaluations. Formaldehyde 

levels could also indicate alterations in atmospheric chemistry resulting from a future 

transition to alternative transportation fuels (e.g., alcohols or natural gas). The 

availability of more spatially rich surface observations would complement the value of 

total column formaldehyde measurements from satellites.
44

Organic PM Composition -- Planned programs to reduce emissions of inorganic precursors 

from mobile sources and power plants will increase the organic carbon fraction of the 

total aerosol budget. This effect is accentuated by large, uncontrollable organic 

emissions from biogenic and biomass burning sources. Chemical speciation networks 

provide an aggregated total organic carbon estimate, since it is not practical to resolve 

the full molecular spectrum of organic aerosols. Nevertheless, key molecular markers 

would assist source apportionment and distinguishing primary and secondary aerosol. 

Additional monitoring sites with representative mixes of aerosols and aerosol sources

will be needed to supplement or replace current routine speciation analyses.

Aerosol Physical Properties -- Improved particle property measurements have been 

motivated by interest in near roadway and ultrafine particle exposures, particle 

nucleation processes, and tracking changes in aerosol size distributions associated with 

alternative transportation fuels (Wahlin et al., 2001). Recent advances in 

instrumentation produce relatively reliable and low cost estimates of particle number 

and surface area. These offer potential for application to routine network operations. 

This will necessitate additional permanent sites that capture long term changes in 

particle size characteristics. Particle size measurements could be incorporated into a 

more focused effort to characterize the range of particle and gaseous attributes 

associated with the near roadway environments.

Spatial Gaps

Integrated assessments necessarily deal with the behavior of pollutants over multiple 

spatial scales. This is because physicochemical processes occur on overlapping scales of 

time and distance. Matching actual pollutant exposure to individual humans requires 

monitoring at a finer spatial scale than provided by current networks. This is a key link in 

the source-to-outcome accountability chain. Primary emitted pollutants are subject to 

very dramatic gradients in the near-source region, including most of the 187 designated 

HAPs as well as a significant fraction of PM. These gradients often coincide with high 

population density. Characterization of regional- to urban-scale pollutant gradients 

provides insight on the relative contribution of regional and local sources to local 

pollutant levels. 

Juxtaposed with the need for finer-scale monitoring is an emerging understanding of 

long range transport and a gradual rise in background pollutant levels. Rising 

background levels have resulted from increases in world-wide anthropogenic pollutant 

emissions. The relative significance of these background contributions to U.S. air quality 

is increasing, given the progress in North American pollution abatement relative to the 

increased atmospheric loading from expanding economies in Asia. As a result, 

monitoring pollutant flow across North American borders, as well as global tracking of 

“background” levels, has become increasingly relevant to North American multipollutant air quality management and accountability. 
45

Spatial gaps in U.S. observation networks include:

Near Source - Fine Scale Characterization -- Ambient monitoring networks typically provide 

primary data to support a broad range of exposure, epidemiological, and risk 

assessment studies relating pollutant exposures to health outcomes. 

Epidemiological studies traditionally use air monitoring data from single, centrallylocated urban stations as a surrogate for human exposure. However, urban 

environments in North America often have large and variable pollutant gradients raising 

uncertainties in outdoor and personal exposures. Neither of these issues is addressed 

effectively in current monitoring programs. 

Internal Rural Coverage -- Three national networks form the backbone of rural air quality 

measurements: IMPROVE, CASTNET, and the NADP (Section 2). Although these 

networks were designed for specific objectives, they have also proven very useful for 

general air quality model evaluation and transport assessments. However, major spatial 

gaps exist in monitoring of surface-based ozone and key source indicator and precursor 

species (CO, SO2, VOCs, speciated aerosol, NOx, and NOy) throughout the mid-section of 

the Nation (Figure 1 in Section 2). EPA’s primary NAAQS, which are set to protect public 

health, have led to an urban focus in monitoring these species. Rising background 

pollutant levels (Cooper et al., 2010) have resulted from increases in world-wide 

anthropogenic pollutant emissions. This is particularly relevant to western mountainous 

regions, which are confounded by a mix of long distance pollutant transport, 

stratospheric ozone intrusion, increasing localized emissions from energy exploration 

and extraction operations, and population growth. 

Sentinel Stations to Link Transport Regimes -- The addition of two or three remote stations 

on the east and west coasts of North America would support trans-oceanic transport 

assessments, global and regional air quality model evaluation, boundary conditions for 

models, and insight on background air quality trends. Sentinel sites need to be 

supported by a stable resource base, since their most significant benefit is often derived 

from analyzing long-term trends. Coincident measurements are needed of O3 and 

aerosol components (nitrate, sulfate, organic and elemental carbon, trace metals), 

precursors of O3 and aerosol (total reactive nitrogen, PAN, VOCs, and SO2), and 

atmospheric tracers (such as CO, CO2, and mercury). Because transported pollution is 

mostly aloft, sentinel stations are especially effective when they are located at altitude 

and/or include vertical profile measurements.

Vertical Profiles of Key Atmospheric Species -- Vertical profiling of boundary layer and free 

troposphere air chemistry in North America is limited to lidar networks, specialized field 

campaigns, and a small number of ozone sonde releases. The CALIOP instrument 

provides lidar profiles from space, producing several narrow “curtains” per day over the 

United States. More routine boundary layer profiling of meteorology and air chemistry 

would provide valuable support for model evaluation and emerging efforts to integrate 

models and observations. 
46

Surface-based networks typically monitor the lower ten meters of the atmosphere, 

where most of the air we breathe is located. There are usually significant differences 

between this air and the PBL, which models attempt to characterize as a homogenous 

system. Coverage of these vertical transitions is difficult. 

The rawinsonde network lacks adequate temporal resolution to adequately track the 

diurnal patterns of PBL heights, while NPN radar profiling does not provide sufficient 

vertical resolution for PBL characterization. Moreover, radar profilers have inadequate 

spatial coverage and lack consensus methodology to synthesize raw data into derived 

PBL heights conducive to model evaluation. Similar gaps were noted by a recent 

National Academies report on climate and weather observations (NRC, 2009b), which 

listed PBL height, air quality measurements above the PBL, and vertical profiles of 

humidity among the “highest priority observations needed to address current 

inadequacies.”

Since satellite total column data do not simply correspond to surface conditions, routine 

vertical profiles of key species such as ozone, NO2, CO, SO2, and aerosols are needed to 

establish the relationship between surface-based point and satellite observations. This 

would increase the value of each system, and help satellite data fill gaps in sparsely 

monitored areas. Potential investments in vertical profiling programs to help leverage 

satellite data include:

 Expansion of NOAA’s ozone sonde program to provide added spatial coverage in 

the continental United States, along with the addition of key trace gas 

measurements.

 A sustained U.S.-based aircraft campaign (national and international flights), 

similar to the European IAGOS (formerly MOZAIC and CARIBE) effort, to produce 

routine vertical profiles of key trace gases and aerosols. 

 Deployment of fixed-site lidars (aerosol and/or ozone) at key locations 

throughout North America to provide continuous profiles of aerosol backscattered light and ozone which can provide a direct link between ground-based, 

in-situ samplers and column densities from satellite instruments. NASA and 

NOAA are developing a small number of fixed-site and field-deployable ozone 

lidars through the Tropospheric Ozone Lidar Network (TOLNet) to assess the 

potential of such systems. Such a network could build on and complement the 

existing NDACC lidars and semi-routine aircraft-based measurements by NOAA.

Temporal Gaps 

Temporal gaps in measurements include challenges in harmonizing continuous and 

gravimetric PM mass monitoring, and the lack of continuous or daily speciated

particulate observations. As noted elsewhere, measurements from most satellites and 

sondes are only available once or twice per day, limiting their usefulness. 
47

However, TEMPO in geostationary orbit will begin providing hourly satellite 

observations for several species when it launches later this decade. 

The demand for higher temporal resolution for particulate matter observations has 

increased as a result of findings regarding human health response (Peters et al., 2001), 

and with our developing understanding of multi-scale atmospheric processes. With the 

exception of PM mass, particle properties are not monitored continuously on most 

networks. Consequently, surface based observations often miss parts of episodic events 

associated with fires and dust storms, in addition to limiting the number of pairings 

relating air quality to health outcome records.

While North American networks have deployed over 500 routinely operating continuous 

PM2.5 mass samplers, harmonization of continuous and gravimetric (i.e., Federal 

reference) methods for PM mass remains a challenge. Measurement artifacts associated 

with the filter-based, gravimetric techniques creates significant ambiguity in the PM 

data, such as loss of mass of semi-volatile constituents. Harmonization could make 

continuous data more comparable with gravimetric data, allowing characterization of 

particle concentration distributions across large areas, but this could detract from 

efforts to produce “true” atmospheric aerosol measurements. Correlation techniques 

could avoid this problem. Eventually, harmonization of these measurements could 

address both temporal and spatial gaps in PM2.5 monitoring. 

Routine PM chemical speciation networks acquire 24-hour averaged samples, collected 

every third or sixth day. This sampling design is adequate for supporting the annual 

PM2.5 standard and the U.S. regional haze program. However, the timing schedule limits 

the investigation of PM associations with adverse health effects, evaluation of 

emissions, development of air quality models, and application of source attribution 

techniques. Continuous PM speciation technology has been incorporated in the 

Supersites program, and light absorbing aethalometers (an indicator for elemental 

carbon) are included in the U.S. air toxics NATTS. Ten to twenty continuous sulfate and 

organic carbon analyzers are located in a mix of SEARCH and state or local agency 

platforms. 

Satellite Observations

As surveyed in Section 2, satellites provide nominally global, daily monitoring of a 

number of species important for air quality and climate analyses. Recognizing the 

limitations noted previously, satellites can complement other monitoring systems. Both 

satellite and ambient observation systems become more valuable when they are 

integrated. Satellites observe parameters relevant to air quality where little or no 

routine in-situ monitoring occurs, such as over oceans and rural areas. Low Earth orbit 

missions provide near-global coverage, with limited temporal resolution and coverage. 
48

Geostationary missions offer much better temporal coverage of a defined region and 

will begin acquiring observations over much of the Northern Hemisphere by the end of 

the decade. Although a tremendous advance will occur when TEMPO begins providing 

many of the measurements planned for GEO-CAPE in approximately 2018, a remaining 

challenge is to obtain the key companion observations, including CO and CH4. 

Current and future air quality satellite missions provide a stream of parameters directly 

relevant to air quality information for North America, and should strongly influence the 

design of our routine monitoring programs. These satellite data will improve near-term 

air quality characterizations and offer the potential to enhance air quality assessments. 

However, considerably greater value is realized from satellite observations when they 

are integrated with complementary ground-based point and vertical profile 

observations. This begins with validation efforts, when the algorithms used to produce 

column densities from raw satellite readings are refined and calibrated. Validation 

depends on independent measurements underneath the satellite. Several of the 

surface-based recommendations discussed above for trace gas measurements, such as 

formaldehyde, NO2, CO, and SO2, would be very helpful in validation. Intensive field 

studies have been useful to provide vertical information for satellite validation, but they 

have limited temporal and spatial coverage.

When validated, satellite data become useful for addressing spatial and/or temporal 

gaps in ambient monitoring through integration with existing monitoring networks. The 

integration of satellite information enhances both regional and global scale air quality 

characterizations, addressing important criteria pollutants such as O3 and PM2.5, and 

selected air toxics such as formaldehyde. 

In addition to the technical challenges and limitations of using satellite data discussed 

above, it remains organizationally challenging for agencies, such as EPA, to effectively 

support planning and development of satellite missions. 

Integration Opportunities

The assessment of any particular air quality issue, or related set of issues, is best served 

by the use of many types of observations and models. Likewise, these individual 

observations and data streams can serve multiple objectives, for disparate organizations 

and user communities. The integration of observations of different types, from different 

organizations, is both a major opportunity and a significant challenge. 

Conceptually straightforward integration opportunities include:

 Enhancing the horizontal and vertical characterization of key species:

– horizontally by combining urban- and rural-based networks (e.g., urbanbased speciation networks with the rural-based IMPROVE program; SLAMs 

(urban) and CASTNET (rural) O3 stations);
49

– vertically through the atmospheric column by blending surface 

measurements, vertically-resolved observations from ground-based and 

aircraft platforms, and satellite data;

 Combining precipitation and dry observation networks to develop deposition 

fields, as performed currently through the CASTNET and NADP programs;

 Collocating atmospheric deposition observations with soil and surface water 

measurement campaigns and select long-term ecological monitoring sites, such 

as NEON and the Long Term Ecological Research (LTER – www.lternet.edu) 

Network;

 Collocating a variety of different species measurements to yield multiple 

pollutant characterizations within a consistent spatial frame; 

 Matching ambient measurement fields to human activity patterns to estimate 

exposures, and matching ambient measurements to emissions fields, via inverse 

modeling, to refine emission estimates;

 Using air quality models in combination with observations to address spatial and 

temporal gaps associated with limited observations.

Some of these examples are straightforward, like-to-like combinations of two networks 

with different but overlapping domains. Others, such as blending of satellite, surface, 

and aircraft data, or combinations of models with observations, are technically and 

scientifically challenging. Finally, organizational barriers exist for all of these 

recommendations, particularly for those that require moving monitors or modifying 

methods.

Observations and Models to Improve Environmental Characterization

Increasingly, models and observations are being used together, in a variety of ways, due to 

advances in computational efficiencies and in response to the complexities discussed in 

Section 1. Air quality models have typically been used in prognostic applications that 

address hypothetical questions regarding the effects of management programs and 

rules on future emissions and air quality changes – a function outside the scope of this 

observations report. More recently, air quality models have been used for forecasting 

(next day) air pollution, and providing more spatial texture beyond central site monitors 

to drive human exposure models. Observations alone lack adequate resolution (space, 

time, and composition) to support integrated assessments. 

The integration of chemical observations and transport models is evolving, sharing 

common attributes with weather characterization and forecasting but less technically 

mature. Observation and model integration efforts range from using measurements to 

evaluate model performance, to four dimensional data assimilation (FDDA), as used in 

meteorological models. 
50

Variations and intermediate levels of integration exist. Areas of observation-model 

linkages include:

 Model results to guide monitoring site design for placement in areas of expected 

high concentrations, steep concentration gradients, and important transport 

corridors;

 Observations supplying direct inputs for initial and/or boundary conditions in 

models;

 Observations to indirectly improve model inputs through inverse modeling of 

emissions;

 Observations to evaluate model performance, diagnose model behavior, and 

constrain model adjustments;

 Observations combined or “fused” with model estimates to add spatial, 

temporal, and compositional texture to air quality gradients; and,

 Dynamic assimilation of observations to nudge model estimates, analogous to 

FDDA in meteorological systems.

The linkages between observations and models are emphasized here as a means to 

influence a shift in monitoring design to explicitly recognize these relationships.

Information Technology to Facilitate Data Access, Integration, and Use

Integrated air quality management requires technology to facilitate discovery, access, 

handling, archiving, and harmonization of numerous disparate information sources. 

Accessing and handling observations from single networks or databases remain a 

challenge, despite large investments. Some applications and tools to access and 

integrate multiple data systems have eased the integration of disparate data from 

multiple programs, but by and large differing formats, standards, and gaps in metadata 

significantly hamper integration of different types of data and models. This prevents 

analysts from realizing the full value of air quality data. 

The EPA system for accessing air quality observations was designed primarily as a 

repository for data, and covers only a part of U.S. observational archives. Several other 

organizations have recently built publicly accessible, user-friendly, air quality data 

reduction, integration, analysis, and visualization systems. These include VIEWS, the 

Visualization Information Exchange Web System developed by the Regional Planning 

Organizations (RPOs; http://views.cira.colostate.edu/web/) in support of visibility 

assessments, the Health Effects Institute’s air quality database (Section 2), and ADAM 

(Airborne Data for Assessing Models; http://www-adam.larc.nasa.gov/main.htm). 

NARSTO (http://www.narsto.org/) also has constructed an accessible database for 

intensive field campaigns of historical interest. 

GEOSS, the Global Earth Observation System of Systems (Appendix A), is a current effort 

to build a framework to enable national governments to make Earth science data more 

accessible and usable for decision support. 
51

GEOSS is designed to make data easier to find and access, as well as to support a 

service-oriented, interoperable, systems approach. This is in contrast to the end-to-end 

systems typically built to process, handle, and visualize air quality and satellite data. The 

GEOSS approach is designed to produce more cost-effective, nimble, and usable tools to 

allow analysts to integrate different types of monitoring data, models, and emissions 

inventories, etc. This approach has been demonstrated and piloted by several Federally 

supported projects, including:

 DataFed (http://datafedwiki.wustl.edu/index.php/DataFed_Wiki), which mediates 

between autonomous, distributed, air quality data providers and users. 

This facilitates access to and flow of atmospheric data from provider to users, 

supporting the development of user-driven data processing value chains and 

improving inputs to comprehensive integrated environmental assessments.

 GEOSS Architecture Implementation Pilot (AIP) Air Quality Workgroup, which 

developed the GEOSS infrastructure for air quality data and built “Air Quality 

Community Infrastructure” to serve as an interface between air quality analysts and 

GEOSS. 

https://sites.google.com/site/geosspilot2/air quality-and-health-working-group

 Cyberinfrastructure for Air Quality Management (CyAir), which contributes to the 

planning, development, maintenance, and coordination of systems to help the air 

quality community better utilize air quality information. The cyberinfrastructure is 

envisioned as a service-oriented, open-source, web-based network of air quality and 

pollutant emissions data providers and repositories, supported by existing and new 

data analysis tools for use by the air quality management and research communities. 

http://cyair.net

These emerging integrated systems will help address technology needs for 

comprehensive assessments, but will require substantial, sustained investment and 

engagement from supporting and user communities. 

Barriers to Progress

Any approach to addressing the emerging air quality and assessment issues must 

recognize the resource, technological, and institutional constraints that impede the 

progress of air quality monitoring programs. 

Sustaining Infrastructure

As documented in many fields of endeavor, it is challenging for organizations to 

maintain infrastructure. Monitoring systems are no different. Users are often in 

different organizations than providers, and take the data for granted. Indeed, the 

provision of seamless, automated access to data lets users work with minimal 

awareness of who produced the data. 
52

Many measurement networks struggle with outdated technology, old equipment, and 

aging workforces. Downstream assessments are more visible than the monitoring 

systems that support them, the latter being sustained by a “trickling down” of 

resources.

Organizational Priorities

Organizations often lack the resource flexibility to support medium or low priority 

measurements. For example, EPA relies on Federal Reference Methods (FRM) and 

Federal Equivalent Methods (FEM) to assess compliance with air quality standards. 

Under constrained budgets, new and improved measurements of high scientific value 

are generally difficult to fund. A recent example is the continued acceptance of existing 

NOx instruments with known biases, despite development of a new NO2 standard. 

Transitioning Research and Technology Development to Operations

Measurement programs supported by research organizations are particularly vulnerable 

to loss of funding, compromising long-term records and other applications. In the case 

of satellites, “research” sensors/platforms with finite lifetimes are typically not replaced. 

Although analysis of long-term air quality patterns is a research interest, research 

organizations typically focus on methods development and physicochemical process 

characterization. The expectation is that routine measurement programs will transition 

to operational organizations. For example, NASA satellite missions have defined 

operational time spans, yet the transition to longer term operational status through 

partner agencies is generally not planned in advance. Successful transitions have 

included the LANDSAT mission partnership between USGS and NASA, as well as EPA’s 

management of CASTNET, which was transitioned from EPA’s research office to EPA’s air 

office in the late 1990s. 

The original NCore monitoring strategy for proposed Level 1 sites had been to form 

partnerships between universities and state and local agencies to test emerging 

instrumentation, and jointly share in the transition of research grade equipment to 

operations. However, Level 1 sites have not been deployed, even though more than 70 

Level 2 multiple pollutant measurement sites relying on routine instruments have been 

deployed. As a result, there has been inadequate incorporation of continuously 

operated speciated particulate matter, mercury, and inorganic nitrogen species

(reduced and oxidized forms) measurements.

Challenges of Long-Term Support for Future Satellite Missions

A particular research-to-operations challenge is the difficulty that recipient agencies 

face in supporting the development and funding of future satellite missions. Satellite 

instruments are planned, developed, and funded years before the platform is launched, 

due partly to the high costs associated with satellite missions. This time frame often 

extends beyond the planning time horizon of a regulatory agency. 
53

EPA does not fund satellite missions, but it would be useful for it and other recipient 

agencies to have a mechanism to identify how specific instruments/missions will jointly 

help monitor and manage ambient air quality. Although it is difficult for a recipient 

agency to commit to use data many years in the future, such commitments could 

influence mission funding and instrument design decisions. Conversely, satellite 

instruments have proven essential for air quality analysis and management, and the 

provision of data to address emerging air quality assessment challenges should remain 

high in mission agency planning priorities. 

Market Incentives

Beyond the need for FRM/FEM instruments, there are few market incentives for 

instrumentation firms to pursue the engineering and development steps necessary to 

produce operational grade methods. This financial barrier is linked to the above noted 

issues regarding agency priorities, transition from research to operations, and 

communication impediments between regulatory agencies and instrument developers 

over anticipated future needs.

Observation technology is typically developed by individual research groups for specific 

applications associated with a laboratory or field campaign objective. This technology

can then be passed on to other users. For example, NASA develops satellite observation 

platforms in space and on aircraft typically for single-use (or short-term), promising 

technologies. These are then transferred to NOAA, and the satellite sensors made 

operational by NESDIS. There is no similar development path for technologies to inform 

surface air chemistry monitoring for use by EPA or state and local air quality managers. 
54

Conclusions

The United States has a robust and invaluable network of air quality observation 

systems, and recent improvements in technology are providing unprecedented 

opportunities to enhance current capabilities. However, there also exist substantial 

opportunities for improvement in the U.S. air quality observation system as currently 

implemented. 

Establish Standing Multi-Agency Observations Working Group

As a first step to taking advantage of these opportunities, the NSTC should consider 

chartering an interagency working group on air quality observations under the AQRS of 

the CENRS. This group would maintain close coordination with national Civil Earth 

Observations planning and the U.S. Group on Earth Observations (USGEO) activities, 

including consideration of existing partnership models (e.g., NADP, IMPROVE). The 

objectives of this working group could include:

 Provide a forum to facilitate cooperation and collaboration among the Federal 

agencies with air quality observation programs. Air quality measurements are 

important to so many users that a broader view of the health, relevancy, and 

evolution of observation programs should complement the existing singleorganization focus on discrete network elements.

 Provide an interface between the various user communities (e.g., air quality 

managers, health scientists, air quality forecasters, etc.) and those involved in 

making air quality observations to ensure the benefits are maximized for both 

communities.

 Extend the analysis presented in this report and develop specific 

recommendations for improvements to the Nation’s air quality observing system 

and track progress towards the goals established. Specifically, the Working 

Group on Air Quality Observations would:

o assess the adequacy of current networks and measurement technologies, 

including maintenance shortfalls and modernization needs

o identify important measurement gaps

o identify important information gaps and opportunities for advancing technology 

and sharing and utilization of observation programs.

 Coordinate the development of multi-agency initiatives to address deficiencies 

that have been identified and enhance and extend air quality observations in the 

U.S.
55

Address Current Observation Gaps

Numerous important measurements that are missing or in short supply were described 

in Section 3. This analysis will need to be revisited as monitoring systems and our 

understanding of the atmosphere evolve, and it will be appropriate for the working 

group to add their perspective to the analysis presented there. 

While requests for added observations have been raised periodically, this renewed 

effort is intended to (a) increase the overall value-to-cost ratio incurred collectively 

through a system of measurement programs and (b) improve the comprehensive 

effectiveness of measurement programs where past requests have focused on specific 

topics without recognition of the broader opportunities for leverage and cooperation. 

Suggested steps include:

1. initiate monitoring of reactive gas and particulate nitrogen compounds, which 

are precursors of ozone and particulate matter, contributors to acid deposition, 

and nutrients in ecosystems,

2. collocate instrumentation at core monitoring sites to facilitate inter-comparison 

with satellite observations, 

3. target monitoring in rural/remote areas to measure regional backgrounds and 

contributions from long-range transport of pollutants, 

4. establish more robust air toxics monitoring near major industrial facilities to help 

investigate whether air toxics emissions are associated with human health 

effects in nearby communities, 

5. target intensive field studies designed to elucidate critical processes that 

determine atmospheric concentrations of ozone and particulate matter and 

other air pollutants, and

6. establish routine monitoring of vertically resolved observations of ozone, fine 

particulate matter (including its composition), and their precursors, to evaluate 

and improve air quality modeling.
56

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i

Introduction to Appendices for Existing Air Quality Monitoring 

Programs

Observation programs supporting air quality and related assessments include routine 

regulatory networks, deposition networks, intensive field studies, remote sensing 

systems, sondes, aircraft campaigns, satellites, and focused fixed-site special purpose 

networks. Appendices A – I provide information on a wide variety of these air 

monitoring networks. Major networks that are currently operating are emphasized; in 

some cases, reference to other networks that have been discontinued or were intended 

only for a specific operating period is also provided. The focus is on networks located in 

the United States, but attention is also given to other North American, European, and 

international efforts that contribute to U.S. assessments.

Information on monitoring networks represents the recent status of these networks (in 

terms of monitor number, placement, and measurement parameters). The actual status 

will likely have changed as of the publication date of this report for at least some of 

these networks as they expand or contract, consistent with current needs. For latest 

information on the status of many air quality monitoring networks, readers should 

consult AirData at http://www.epa.gov/airdata/ad_maps.html. Alternately, website 

links (which also periodically change) in these appendices should be consulted for the 

latest information on networks.

This information is the product of extensive Internet searches and information provided 

by knowledgeable representatives from the agencies responsible for the networks. In 

most cases, the information provided has been taken directly from the referenced 

Internet site, especially for supplemental information for the non-routine special 

intensive studies. Attribution of this information should be to those Internet websites.
ii

Appendix A. Integrated Observational Strategies 

Intensive field campaigns and observations from space provide valuable measurements 

not captured in routine, ground-based observation networks and can have direct 

impacts on the air quality management process. For example, results from the Texas Air 

Quality Study were incorporated into the ozone State Implementation Plan for the 

Houston area within two years. Similarly, satellite observations have played important 

roles in improving the quality of fire-based emissions estimates in EPA’s systems for 

driving air quality models. And in the absence of an adequate surface-based network, 

satellite observations have been used to demonstrate the progress of major national 

programs to reduce emissions of nitrogen oxides.

Integrating these various types of observations with one another and with models to 

produce the best multi-dimensional characterization of air quality is a significant

scientific and information-technology challenge, even in a research setting. Integration 

for decision-support purposes, near-real-time forecasting applications, and other 

operational purposes is even more challenging. 

Over the last several years, a number of observational strategies and umbrella 

organizations have formed that convey and promote integration across disciplines, 

observational modalities, and/or organizations. Some of these efforts are focused on air 

quality or atmospheric chemistry, while some are far broader. These strategies and 

organizations include:

USGEO and GEO – The U.S. Group on Earth Observations (USGEO) exists as a 

subcommittee of the NSTC Committee on Environment, Natural Resources, and 

Sustainability (CENRS). USGEO’s mandate is to: (1) coordinate, plan, and assess Federal 

Earth observation activities in cooperation with domestic stakeholders; (2) foster 

improved Earth system data management and interoperability throughout the Federal 

Government; and (3) engage international stakeholders by formulating the U.S. position 

for, and coordinating U.S. participation in, the intergovernmental GEO based in Geneva, 

Switzerland. GEO, a voluntary partnership of national governments and international 

organizations, is developing the Global Earth Observation System of Systems (GEOSS). 

GEOSS provides a voluntary, multidisciplinary framework to make all types of Earth 

observations more discoverable, accessible, and useable for decision support. 

In October 2010, Congress charged OSTP with a new “mechanism to ensure greater 

coordination of the research, operations, and activities relating to civilian Earth 

observation” [emphasis added] that would also produce and routinely update the 

strategic plan for Earth observations.1 In response, OSTP developed and released a U.S. 

National Strategy in April 2013 and concurrently performed an internal assessment of 

362 Federal Earth observing systems. 

 

1 National Aeronautics and Space Administration Authorization Act of 2010 (Public Law 111–267), § 703 

“Interagency Collaboration Implementation Approach.” 
iii

Summary results of this assessment will form the foundation for a new U.S. National 

Plan for Civil Earth Observations, to be published in 2014. This air quality observations 

report, along with other reports of the NSTC and the National Academies, provides 

important technical input to the development of the National Plan.

IGAC / AC&C – The International Global Atmospheric Chemistry (IGAC: 

http://www.igacproject.org/) program was created in the late 1980s to address growing 

international concern about atmospheric changes. IGAC is jointly sponsored by the 

Commission on Atmospheric Chemistry and Global Pollution (CACGP) of the 

International Association of Meteorology and Atmospheric Sciences (IAMAS) and the 

International Geosphere-Biosphere Programme (IGBP). IGAC has initiated or 

coordinated much of the research over the last decade focusing on chemical 

composition, transformations, and transport in the troposphere. Together with the 

Stratospheric Processes And their Role in Climate (SPARC) project of the World Climate 

Research Programme (WCRP), IGAC has started the Atmospheric Chemistry and Climate 

(AC&C; http://www.igacproject.org/node/8/) initiative, which examines the interplay 

between chemistry, chemically-active species, and climate change.

IGACO – Integrated Global Atmospheric Chemistry Observations (IGACO; 

http://www.igaco-o3.fi) is a strategy for bringing together ground-based aircraft and 

satellite observations of 13 chemical species in the atmosphere. IGACO will be 

implemented as a strategic element of the Global Atmospheric Watch (GAW) program 

of the World Meteorological Organization (WMO). IGACO will be organized around four 

focus areas, one of which is air quality / long-range transport. IGACO provides specific 

recommendations on measurement parameters, and facilitates integration across 

satellite- and ground-based stations. Although IGACO is focused on large, global-scale 

characterizations, the strategy provides useful guidance that should be considered in 

any air-based observation program design. Several of the core IGACO measurement 

parameters (O3, CO, NO2, and CO2) are important regional- and urban-scale air quality 

indicators. 

MACC – Monitoring Atmospheric Composition and Climate (MACC; 

http://www.gmes.info/pages-principales/projects/atmosphere-projects/macc/) is a 

recently initiated collaborative effort, funded by the European Commission, to monitor 

the global distribution and long-range transport of long-lived greenhouse gases, 

aerosols, and reactive pollutants that degrade air quality. MACC's product lines include 

data records on atmospheric composition for recent years, and current data for 

monitoring present conditions and forecasting the distribution of key constituents a few 

days ahead. (MACC is a continuation of the Global and regional Earth-system 

(Atmosphere) Monitoring using Satellite and in-situ data (GEMS) and PROtocol 

MOniToring for the GMES Service Element: Atmosphere (PROMOTE) programs under 

Global Monitoring for Environment and Security (GMES), see above website for details.)
iv

NARSTO – NARSTO (formerly the North American Research Strategy for Tropospheric 

Ozone; http://www.narsto.org/) is a public-private partnership of government agencies, 

industry, and academic institutions. The partnership sponsors a variety of workshops 

and assessments addressing current air quality research interests. NARSTO has focused 

on the atmospheric sciences, with assessments addressing ozone and particulate matter 

air pollution, emissions inventories, and, more recently, multiple-pollutant air quality 

management. These assessments generally complement preceding NAS studies 

addressing air pollution management. The NARSTO archive stores data from a variety of 

intensive field campaigns. 

NAAMS – The National Ambient Air Monitoring Strategy (NAAMS; 

http://www.epa.gov/ttnamti1/monitor.html) was developed jointly by the EPA and 

numerous state and local agencies. Developed in the early 2000s, NAAMS (Scheffe et al., 

2009) was intended to make the design of U.S. regulatory-based networks more 

efficient in supporting the development of air quality standards and emission control 

strategies. The multi-pollutant National Core network (NCore, see Section 2) emerged 

from the NAAMS process.

AQAST – Air Quality Applied Sciences Team (AQAST; 

http://acmg.seas.harvard.edu/aqast/index.html) is a NASA team of atmospheric 

scientists working in partnership with U.S. air quality managers from local to national 

levels. The goal is to exploit the power of Earth science tools and data sets, available 

from NASA and other agencies, to address multi-faceted air quality problems. A wide 

range of projects using satellite data, suborbital data, and models are conducted 

through pooled expertise under the program. 
v

Appendix B. Evolution of United States Air Monitoring Networks

The 1970 Clean Air Act (CAA) established a framework for the original National Ambient 

Air Quality Standards (NAAQS), and drove the design and implementation of the NAMS 

and SLAMS networks in the late 1970s. These networks were intended primarily to 

establish non-attainment areas with respect to the NAAQS, which include ozone, sulfur 

dioxide, nitrogen dioxide, carbon dioxide, lead (Pb), and particulate matter (PM). The 

NAMS/SLAMS networks have evolved over time (Figure A.1) as a result of cyclical 

NAAQS review and promulgation efforts, leading to changes in measurement 

requirements related to averaging times, locations, and the various size cuts associated 

with PM. 

Relatively wide geographical distribution and persistence of ozone and PM2.5 NAAQS 

exceedances (Figure A.2) have led to these pollutants dominating the national 

monitoring landscape.

Figure B.2. 2006 air quality summaries for ozone, annual average PM2.5, and daily PM2.5.

Figure B.1. Evolution of U.S. air network growth.
vi

Yellow and red sites indicate values exceeding NAAQS levels (source, EPA).

Two important ambient air networks focused on environmental welfare effects were 

established in the mid -1980’s. The Interagency Agency Monitoring of Protected Visual 

Environments (IMPROVE) network consists of 212 sites (170 current and 42 

discontinued) representing 156 visibility-protected federal areas (national parks, 

wilderness areas, and wildlife refuges). IMPROVE is used primarily to assess visibility 

impairment, but has provided a reliable long term record of PM mass and major 

speciation components. It served as a model for the later deployment of EPA’s CSN 

network (Figure 2 of the full report), which has provided an urban complement to 

characterize aerosol composition (Figure A.3). 

Figure B.3. Regional chemical composition of PM2.5 aerosols -- composition of PM2.5 for 15 

selected urban areas in the United States. Annual average PM2.5 concentrations (ug/m3) are 

presented, the circle size representing the magnitude of PM2.5 mass. 

The Clean Air Status and Trends Network (CASTNET) was established in the early 1990s 

to track changes in dry deposition of major inorganic ions and gaseous precursors 

associated with the CAA Title 4 reductions in sulfur and nitrogen. Title 4 was designed to 

address surface water acidification in eastern North America. Complementing ongoing 

precipitation measurements from the National Atmospheric Deposition Program 

(NADP), CASTNET has provided a valuable source of model evaluation data for many of 

the large regional scale applications since the 1990’s. 

Deployment of the Photochemical Assessment and Measurements Stations (PAMS) and 

the PM2.5 networks from the early 1990’s through 2002 markedly enhanced the spatial, 

temporal, and compositional measurement of gases and aerosols. PAMS partially 

supports user needs beyond NAAQS compliance, such as public reporting and 
vii

forecasting of adverse air quality, implementation efforts including air quality model 

evaluation, and source apportionment and pattern (spatial and temporal) analysis of 

precursor species.

State and local air agencies have measured a variety of metallic and gaseous hazardous 

air pollutants (HAPs) at over 200 locations since the 1980’s. Typically, broad access to 

and use of data was compromised by a lack of centralized databases and multiple 

sampling and laboratory protocols leading to data uncertainty. In response to this gap in 

accessible and centralized HAPs observations, a modest 27 site National Air Toxics 

Trends (NATTS) network was initiated in 2001. Current NATTS species include: acrolein, 

perchloroethylene, benzene, carbon tetrachloride, chloroform, trichloroethylene, 1,3-

butadiene, 1,2-dichloropropane, dichloromethane, tetrachloroethylene, vinyl chloride, 

formaldehyde, acetaldehyde, nickel compounds, arsenic compounds, cadmium 

compounds, manganese compounds, beryllium, lead, hexavalent chromium, and 

expected additions of benzo(a)pyrene and naphthalene. 

A new multi-pollutant monitoring network, referred to as NCore, was incorporated in 

the 2006 revisions to the particulate matter standards. When fully implemented, NCore 

will provide a minimum of 75 Level 2 sites (Figure A.4) in most major urban areas and 

important transport corridor and background locations. NCore will include a variety of 

trace gas, aerosol mass and speciation measurements which are intended to support 

multiple data user needs (e.g., air quality model evaluation, long term epidemiological 

studies). In addition to establishing a multiple pollutant measurement framework, the 

NCore sites are intended to provide a backbone of central location sites that can be 

complemented by additional (existing and new) stations to address more specific spatial 

resolution requirements. Intensive Level 1 sites, intended to promote transition of new 

technologies into routine networks, have not been implemented to date. 

Figure B.4. Original 3-tiered NCore design (left) and proposed site locations (see 

http://www.epa.gov/ttn/amtic/ncore/networks.html for updated site locations)

Level 2: ~ 75 Multipollutant (MP) Sites,“Core Species”

Plus Leveraging From 

PAMS, Speciation Program, Air Toxics

Level 1. 3-10 Master Sites Comprehensive Measurements, Advance Methods Serving Science and Technology Transfer Needs

Level 3: Minimum Single Pollutant Sites (e.g.> 500 

sites each for O3 and PM2.5 and 

related spatial Mapping Support

L2

Level 3

L1

NCore Measurements

Minimum “Core” Level 2 Measurements Continuous NO,NOy,SO2,CO, PM2.5, 

PM10/PMc,O3,Meteorology (T,RH,WS,WD); 

Integrated PM2.5 FRM, HNO3, NH3, 

Level 2: ~ 75 Multipollutant (MP) Sites,“Core Species”

Plus Leveraging From 

PAMS, Speciation Program, Air Toxics

Level 1. 3-10 Master Sites Comprehensive Measurements, Advance Methods Serving Science and Technology Transfer Needs

Level 3: Minimum Single Pollutant Sites (e.g.> 500 

sites each for O3 and PM2.5 and 

related spatial Mapping Support

L2

Level 3

L1

NCore Measurements

Minimum “Core” Level 2 Measurements Continuous NO,NOy,SO2,CO, PM2.5, 

PM10/PMc,O3,Meteorology (T,RH,WS,WD); 

Integrated PM2.5 FRM, HNO3, NH3, 
viii

APPENDIX C. MAJOR ROUTINE OPERATING AIR MONITORING NETWORKS3

Network Lead 

Agency

Number of 

Sites Initiated Measurement Parameters Location of Information and/or Data

State / Local / Federal Networks

NCore – National Core 

Monitoring Network EPA 80 2008

O3, NO/NO2/NOy, SO2, CO, PM2.5/PM10-2.5, 

PM2.5 speciation, NH3, HNO3, Surface 

Meteorology1

http://www.epa.gov/ttn/amtic/

ncore/index.html

SLAMS – State and Local 

Ambient Monitoring 

Stations

EPA ~1500 1978 O3, NOx/NO2, SO2, PM2.5/PM10, CO, Pb http://www.epa.gov/air/oaqps/

qa/monprog.html

CSN – Chemical Speciation 

Network EPA ~200 1999 PM2.5, PM2.5 speciation, Major Ions, Metals http://www.epa.gov/ttnamti1/specgen.html

PAMS—Photochemical 

Assessment Monitoring 

Network

EPA 50+ 1994 O3, NOx/NOy, CO, Speciated VOCs, Carbonyls, 

Surface Meteorology & Upper Air

http://www.epa.gov/ttn/amtic/

pamsmain.html

IMPROVE—Interagency 

Monitoring of Protected 

Visual Environments

DOI

(NPS) ~160 1988 PM2.5/PM10, Major Ions, Metals, Light Extinction, Scattering Coefficient

http://vista.cira.colostate.edu/I

MPROVE/

CASTNet – Clean Air Status 

and Trends Network EPA 80+ 1987

O3, SO2, Major Ions, Calculated Dry Deposition, 

Wet Deposition, Total Deposition for 

Sulfur/Nitrogen

http://www.epa.gov/castnet/

GPMN—Gaseous Pollutant 

Monitoring Network

DOI

(NPS) 33 1987

O3, NOx/NO/NO2, SO2, CO, Surface 

Meteorology, (plus enhanced monitoring of CO, 

NO, NOx, NOy, and SO2 plus canister samples for 

VOC at three sites)

http://www2.nature.nps.gov/air

/Monitoring/network.cfm#data

POMS—Portable Ozone 

Monitoring Stations

DOI

(NPS) 14 2002

O3, surface meteorology, with CASTNet-protocol 

filter pack (optional) sulfate, nitrate, ammonium, 

nitric acid, sulfur dioxide

http://www2.nature.nps.gov/air

/studies/portO3.cfm

Passive Ozone Sampler 

Monitoring Program

DOI

(NPS) 32

1995

(ended 

2005)

O3 dose (weekly) http://www2.nature.nps.gov/air

/Studies/Passives.cfm

NADP/AMoN—National 

Atmospheric Deposition 

Program / Ammonia 

Monitoring Network

Multiagency

~50 2010 NH3 http://nadp.sws.uiuc.edu/AMo

N/

NADP/AMNet—National 

Atmospheric Deposition 

Program / Atmospheric 

Mercury Network

Multiagency

~20 2009

Gaseous elemental mercury (GEM)

Gaseous oxidized mercury (GOM)

Particulate-bound mercury (PBM2.5)

Surface Meteorology

http://nadp.sws.uiuc.edu/amn/

NADP/MDN—National 

Atmospheric Deposition 

Program / Mercury 

Deposition Network

Multiagency

110+ 1996 Mercury from precipitation chemistry http://nadp.sws.uiuc.edu/mdn/

NADP/NTN—National 

Atmospheric Deposition 

Program / National Trends 

Network

Multiagency

~250 1978 Major Ions from precipitation chemistry http://nadp.sws.uiuc.edu/NTN/

NADP/AIRMoN—National 

Atmospheric Deposition 

Program / Atmospheric 

Integrated Research 

Monitoring Network

Multiagency

7 1992

Major Ions from precipitation chemistry

Note: some sites began in 1976 as part of the 

DOE MAP3S program; early data are archived on 

NADP and ARL servers.

http://nadp.sws.uiuc.edu/AIRM

oN/

IADN—Integrated 

Atmospheric Deposition 

Network

EPA 15 1990 PAHs, PCBs, and organochlorine compounds are 

measured in air and precipitation samples

http://www.epa.gov/greatlakes

/monitoring/air2/
ix

APPENDIX C. MAJOR ROUTINE OPERATING AIR MONITORING NETWORKS3 (continued)

Network Lead 

Agency

Number of 

Sites Initiated Measurement Parameters Location of Information and/or Data

State / Local / Federal Networks (continued)

NAPS—National Air 

Pollution Surveillance 

Network

Canada 250+ 1969 SO2, CO, O3, NO, NO2, NOx, VOCs, SVOCs, 

PM10, PM2.5, TSP, metals

http://www.ec.gc.ca/natchem/d

efault.asp?lang=en&n=EE0E216

9-1

CAPMoN—Canadian Air 

and Precipitation 

Monitoring Network

Canada 33 2002

O3, NO, NO2, NOy, PAN, NH3, PM2.5, PM10 and 

coarse fraction mass, PM2.5 speciation, major 

ions for particles and trace gases, precipitation 

chemistry for major ions

http://www.ec.gc.ca/rsmn/default.asp?lang=En&n=752

CE271-1

Mexican Air Quality 

Network Mexico 52-62 Late 1960’s O3, NOx, CO, SO2, PM10, TSP,VOC http://www.ine.gob.mx/dgicur/calaire/indicadores.html

Mexican City Ambient Air 

Quality Monitoring 

Network

Mexico 49 Late 1960’s O3, NOx, CO, SO2, PM10, TSP,VOC http://www.ine.gob.mx/dgicur/

calaire/indicadores.html

Air Toxics Monitoring Networks

NATTS—National Air 

Toxics Trends Stations EPA 27 2005 VOCs, Carbonyls, PM10 metals2

, Hg http://www.epa.gov/ttn/amtic/airt

oxpg.html

State/Local Air Toxics 

Monitoring EPA 250+ 1987 VOCs, Carbonyls, PM10 metals2

, Hg http://www.epa.gov/ttn/amtic/airt

oxpg.html

NDAMN—National Dioxin 

Air Monitoring Network EPA 32 1998 - 2005 CDDs, CDFs, dioxin-like PCBs http://cfpub.epa.gov/ncea/CFM/recordisplay.cfm?deid=54811

Tribal Monitoring Networks

Tribal Monitoring4EPA 90+ 1995 O3, NOx/NO2, SO2, PM2.5/PM10, CO, Pb http://www.epa.gov/air/tribal/airp

rogs.html#ambmon

Industry / Research Networks

New Source Permit 

Monitoring None variable variable O3, NOx/NO2, SO2, PM2.5/PM10, CO, Pb Contact specific industrial facilities

HRM Network—Houston 

Regional Monitoring 

Network

None 9 1980 O3, NOx, PM2.5/PM10, CO, SO2, Pb, VOCs, 

Surface Meteorology

http://hrm.radian.com/houston/ho

w/index.htm

ARIES / SEARCH—Aerosol 

Research Inhalation 

Epidemiology Study / 

SouthEastern Aerosol 

Research and 

Characterization Study 

experiment

None 6 1992

O3, NO/NO2/NOy, SO2, CO, PM2.5/PM10, 

PM2.5 speciation, Major Ions, NH3, HNO3, 

scattering coefficient, Surface Meteorology

http://www.atmosphericresearch.com/studies/SEARCH/inde

x.html

SOS – SERON—Southern 

Oxidant Study -

Southeastern Regional 

Oxidant Networks

EPA ~40 1990 O3, NO, NOy, VOCs, CO, Surface Meteorology http://www.ncsu.edu/sos/pubs/sos

3/State_of_SOS_3.pdf

National/Global Radiation Networks

RadNet—formerly 

Environmental Radiation 

Ambient Monitoring 

System (ERAMS)

EPA 200+ 1973 Radionuclides and radiation http://www.epa.gov/enviro/html/e

rams/

SASP -- Surface Air 

Sampling Program DHS 41

1963

(no data 

after 1993)

89Sr, 90Sr, naturally occurring radionuclides, 

7

Be, 210Pb

http://www.nbl.doe.gov/htm/EML_

Legacy_Website/databases.htm

NEWNET—Neighborhood 

Environmental Watch 

Network

DOE 11 1993 Ionizing gamma radiation, Surface 

Meteorology http://newnet.lanl.gov/
x

APPENDIX C. MAJOR ROUTINE OPERATING AIR MONITORING NETWORKS3 (continued)

Network Lead 

Agency

Number of 

Sites Initiated Measurement Parameters Location of Information and/or Data

Solar Radiation Networks

UV Index – EPA Sunrise

Program5 EPA ~50 U.S. cities 2002 Calculated UV radiation index http://www.epa.gov/sunwise/uvindex.html

UV Net -- Ultraviolet 

Monitoring Program EPA 21 1995/2004 Ultraviolet solar radiation (UV-B and UV-A bands), irradiance, ozone, NO2

http://www.epa.gov/uvnet/access.

html

NEUBrew (NOAA-EPA 

Brewer 

Spectrophotometer UV 

and Ozone Network)6

NOAA 6 2005 Ultraviolet solar radiation (UV-B and UV-A 

bands), irradiance, ozone, SO2

http://www.esrl.noaa.gov/gmd/gra

d/neubrew/

UV-B Monitoring and 

Research Program USDA 37 1992 Ultraviolet-B radiation http://uvb.nrel.colostate.edu/UVB/index.jsf

SURFRAD – Surface 

Radiation Budget Network NOAA 8 1993

solar and infrared radiation, direct and 

diffuse solar radiation, photosynthetically 

active radiation, UVB, spectral solar, and 

meteorological parameters

http://www.srrb.noaa.gov/surfrad/

index.html

AERONET – Aerosol

RObotic NETwork

MPLNET – Micro-pulse 

Lidar Network

NASA colocated 

networks

~500

35

1998

2000

Aerosol spectral optical depths, aerosol size 

distributions, and precipitable water 

Aerosols and cloud layer heights

http://aeronet.gsfc.nasa.gov/index.

html

http://mplnet.gsfc.nasa.gov/

PRIMENet -- Park Research 

and Intensive Monitoring 

of Ecosystems NETwork6

DOI

(NPS) 14

1997

(ended 

2004)

ozone, wet and dry deposition, visibility, 

surface meteorology, and ultraviolet 

radiation

http://www.cfc.umt.edu/primenet/

Assets/Announcements/99PReport.

pdf

Footnotes:

1. Surface Meteorology includes wind direction and speed, temperature, precipitation, relative humidity, solar radiation (PAMS only).

2. PM10 metals may include arsenic, beryllium, cadmium, chromium, lead, manganese, nickel, and others.

3. Some networks listed separately may also serve as subcomponents of other larger listed networks; as a result, some double counting of the number of individual 

monitors is likely.

4. The number of sites indicated for tribal monitoring is actually the number of monitors, rather than sites. 

5. Sunrise program estimates UV exposure levels through modeling - does not include measurements.

6. NEUBrew is a subset of Original UV brewer network (UV Net); PRIMENET participated in UV Net program.
xi

APPENDIX D. NATIONAL ROUTINE METEOROLOGICAL MONITORING NETWORKS

Network Lead Agency Number of 

Sites Initiated Measurement Parameters

Location of 

Information 

and/or Data

ASOS -- Automated Surface 

Observing System NOAA

~1000 

(supplemented by 

military weather 

observation sites)

1992 

(replaced routine 

surface observations 

collected manually at 

260 Weather Service 

facilities)

Continuous measurements of: Wind 

Direction and Wind Speed; Visibility; 

Runway Visual Range; Type, intensity and 

amount of rain, snow, etc.; Obstructions 

due to fog, mist, etc.; Cloud Height and 

Amount; Ambient Temperature; Dew Point 

Temperature; Pressure; Lightning 

detection; Automated, manual, and plain 

language remarks on special weather 

conditions (depending on level of service); 

and Additive and automated maintenance 

data on precipitation amount, max/min 

temperature, pressure tendency, etc.

http://www.nws.no

aa.gov/asos/pdfs/au

m-toc.pdf

Cooperative Observer 

Program NOAA ~11,400 1890

24-hour maximum and minimum 

temperatures, Liquid equivalent of 

precipitation, snowfall, snow depth, and 

Other special phenomena such as days 

with thunder, hail, etc.

http://www.nws.no

aa.gov/om/coop/

SLAMS – State and Local 

Ambient Monitoring Stations EPA ~1500 1978 Wind direction and speed, Temperature, Precipitation, Relative humidity

http://www.epa.gov

/air/oaqps/qa/monp

rog.html

Remote Automated Weather 

Stations

USDA

(USFS) ~2200 ~1978

Wind direction and speed, Precipitation, 

Pressure, Temperature, Relative humidity, 

Fuel moisture and temperature

http://raws.fam.nw

cg.gov/

NOAA Profiler Network (and 

Cooperative Agency Profilers) NOAA

35

(plus ~100 CAP 

sites)

1992

Vertical profiles of wind direction and 

speed (and vertical profiles of temperature 

at RASS sites)

http://www.profiler.

noaa.gov/npn/

Upper Air Stations 

(Weather Balloons) NOAA

~100 in North 

America, Pacific 

Islands, and the 

Caribbean

1937

Measurements of temperature, relative 

humidity, wind direction and speed, and 

altitude/height at selected pressure levels.

http://www.ua.nws.

noaa.gov/netinfo.htm

Forecast Systems Laboratory 

Aircraft Communications 

Addressing and Reporting 

System

NOAA ~4000 commercial 

aircraft

2001 (routinely 

available database; 

discontinued in 2008)

Wind direction, wind speed and 

temperature reported for various altitudes 

at which aircraft typically operate

http://www.arm.go

v/instruments/acars

National Doppler Radar Sites NOAA ~160

1990 (national radar 

network originated 

prior to 1960)

Base Reflectivity, Composite Reflectivity, 

One-Hour Precipitation, and Storm Total 

Precipitation

http://www.srh.noa

a.gov/radar/radinfo

/radinfo.html

National Lightning Detection 

Network Commercial 100+ 1989 Detection of cloud-to-ground lightning flashes at distances up to 400 km

http://www.nwstc.n

oaa.gov/METEOR/Li

ghtning/detection.h

tm

National Environmental 

Satellite, Data, and 

Information Service

NOAA 2 GOES satellites 

2 POES satellites

1994 (earlier satellite 

systems replaced)

Vertical profiles of temperature, moisture, 

and wind; visible and infrared imagery of 

clouds; water vapor imagery

http://www.goes.no

aa.gov/

C-MAN – Buoy and CoastalMarine Observing Network NOAA 51 Early 1980s

Pressure, wind direction, wind speed and 

gust, and air temperature, relative 

humidity, precipitation, visibility, sea water 

temperature, water level, and waves

http://www.ndbc.n

oaa.gov/cman.php
xii

APPENDIX E. EUROPEAN AIR MONITORING NETWORKS

Network Lead 

Agency

Number 

of Sites Initiated Measurement Parameters

Location of 

Information 

and/or Data

EMEP – Co-operative 

Programme for 

Monitoring and 

Evaluation of the 

Long-range 

Transmission of Air 

Pollutants in Europe 

(encompasses 

networks for ~37 

European countries 

and organizations)

UNECE ~200 1977

Acidifying / Eutrophying Compounds (precipitation): 

SO4, NO3, NH4, trace elements,

pH, acidity

(air): SO2, NO2, HNO3, NH3, PM10, PM2.5, 

major ions

O3 

Heavy Metals 

precipitation, major ions, PM2.5, PM10, Hg, 

wet deposition 

POPs 

precipitation, air, deposition 

Particulate Matter 

PM2.5, PM10, EC, OC, TC, BC 

VOC 

Hydrocarbons, Carbonyls

http://www.nilu.no/pro

jects/ccc/emepdata.ht

ml

EUROTRAC – The 

European 

Experiment on the 

Transport and 

Transformation of 

Environmentally 

Relevant Trace 

Constituents over 

Europe

International 

Executive 

Committee 

(European 

Countries)

N/A 1986

EUROTRAC programs performed analyses utilizing 

data from existing or specially designed monitoring 

networks in order to: 

1. elucidate the chemistry and transport of ozone 

and other photo-oxidants in the troposphere, e.g., 

TOR -- 30 O3 stations and ALPTRAC -- 15 snow 

monitoring sites

2. identify processes leading to the formation of 

acidity in the atmosphere, particularly those 

involving aerosols and clouds. 

3. understand uptake and release of atmospheric 

trace substances by the biosphere.

http://www.helmholtzmuenchen.de/eurotrac/

index_what_is.html

EUROTRAC-2 -- The 

EUREKA project on 

the transport and 

chemical 

transformation of 

trace constituents in 

the troposphere over 

Europe; second 

phase. Subprojects:

– AEROSOL 

– BIATEX-2 

– CAPMAN 

– CMD 

– EXPORT-E2 

– GENEMIS 

– GLOREAM 

– LOOP 

– MEPOP 

– PROCLOUD 

– SATURN 

– TOR-2 

– TRAP45 

– TROPOSAT

International 

Scientific 

Secretariat 

(European 

Countries 

and EU)

N/A 1996

EUROTRAC-2 programs performed analyses utilizing 

data from existing monitoring networks in order to 

support the further development of abatement 

strategies within Europe by providing an improved 

scientific basis for the quantification of sourcereceptor relationships for photo-oxidants and 

acidifying substances.

http://www.gsf.de/euro

trac/index_what_is.htm

l
xiii

APPENDIX F. MONITORING NETWORKS FOR PERSISTENT ORGANIC POLLUTANTS (POPs) 

Network Lead Agency Number 

of Sites Initiated Measurement Parameters

Location of 

Information and/or 

Data

Global Monitoring 

of Persistent 

Organic Pollutants 

(POPs)1

UNEP – United 

Nations 

Environment 

Programme

N/A 2003

Activities include developing guidance on sampling 

and analysis of POPs, QA/QC procedures, data 

treatment and communication and data 

assessment. In addition, the program will include an 

electronic discussion group on POPs monitoring 

issues where existing programs and laboratories are 

invited to participate and share their experience on 

this subject.

http://www.chem.unep.ch

/gmn/default.htm

AMAP – Artic 

Monitoring and 

Assessment 

Programme

NOAA

(as U.S. 

representative 

to the 8 nation 

Artic Council)

N/A ~1991

Air/aerosol sampling for POPs, heavy metals, 

radioactivity and acidification parameters; bulk 

precipitation and snowpack sampling to estimate 

deposition2 

http://www.amap.no/

EMEP -- Cooperative 

Programme for 

Monitoring and 

Evaluation of the 

Long-Range 

Transmission of 

Air Pollutants in 

Europe

UNECE – United 

Nations 

Economic 

Commission for 

Europe

17 1991

Benzo(a)pyrene, PCBs, hexachlorobenzene, 

chlordane, lindane, hexachlorocyclohexane, 

DDT/DDE in precipitation and gas particles

http://www.chem.unep.ch

/gmn/012_emep.htm

GAPS – Global 

Atmospheric 

Passive Sampling

UNEP – United 

Nations 

Environment 

Programme

50 2004

12 chemicals including Aldrin, Chlordane, DDT, 

Deldrin, Endrin, Heptachlor, Hexachlorobenzene, 

Mirex, PCBs, Dioxins(PCDDs), Furans(PCDFs), 

Toxaphene and other pollutants

http://www.ec.gc.ca/rsmn/default.asp?lang=En&

n=A31231AF-1

NDAMN –

National Dioxin Air 

Monitoring 

Network

EPA 34 1998 - 2005 CDDs. CDFs, dioxin-like PCBs

http://cfpub.epa.gov/ncea

/CFM/recordisplay.cfm?de

id=54811

IADN -- Integrated 

Atmospheric 

Deposition 

Network

EPA 20 1990 PAHs, PCBs, and organochlorine compounds are 

measured in air and precipitation samples

http://www.epa.gov/great

lakes/monitoring/air2/

EMAP –

Environmental 

Monitoring and 

Assessment 

Program

EPA 12,600 1988 Oriented to ecological and water monitoring http://www.epa.gov/ema

p/index.html
xiv

APPENDIX G. FIELD CAMPAIGNS FOR NON-ROUTINE SPECIAL INTENSIVE STUDIES3,4

Network Lead 

Agency1

Number 

of Sites Initiated Measurement Parameters

Location of 

Information 

and/or Data

Notes

Deriving Information on 

Surface Conditions from 

Column and Vertically 

Resolved Observations 

Relevant to Air Quality

(DISCOVER-AQ)

NASA 

with MDE 

other 

organization

s

3 aircraft

1 ship

6 MDE 

Surface air 

quality sites

Ozonesonde

s

Pandoras

Dragon 

network, 

2011

Total column measurements 

of O3, NO2, CH2O, and AOD. 

In situ profiles of O3, NO2, 

CH2O, NO, NOy, CO, CO2, 

CH4, H2O, VOC, aerosol 

properties (size distribution, 

scattering, absorption, 

extinction, non‐sphericity, 

f(RH), black carbon, soluble 

ions), and PBL height. 

Ground-based in situ 

measurements of O3, NO2, 

NO, NOy, H2O, PM2.5, 

aerosol scattering. Groundbased lidar observations of 

aerosols and PBL height.

http://discoveraq.larc.nasa.gov/data.

php

Deriving Information on Surface Conditions from Column and Vertically Resolved 

Observations Relevant to Air Quality (DISCOVER-AQ) is a NASA Earth Venture (EV) 1 

mission. DISCOVER-AQ will conduct a series of field missions with an overarching 

objective to improve the interpretation of satellite observations to diagnose near‐

surface conditions relating to air quality and the following science objectives 1: Relate 

column observations to surface conditions for aerosols and key trace gases O3, NO2, 

and CH2O; 2: Characterize differences in diurnal variation of surface and column 

observations for key trace gases and aerosols; 3: Examine horizontal scales of variability 

affecting satellites and model calculations

The first of the field missions was conducted over the greater metropolitan area of 

Baltimore, MD. With two NASA aircraft and an extensive ground network, DISCOVERAQ operated as a complex observing system, providing multiple perspectives on the 

factors that control air quality and influence the ability to monitor pollution events 

from space. To emulate a satellite observing system NASA’s UC-12 King Air flew at an 

altitude of 27,000 feet with an UV/VIS spectrometer and High Spectral Resolution Lidar 

to collect remote sensing observations of particulate matter and gaseous pollutants. 

Detailed profile observations were collected underneath the UC-12 with the NASA’s P3B using in situ sampling to provide detailed information on the distribution of 

pollutants from 1000 to 10,000 feet. These flights were anchored to a network of 

ground sites measuring surface air quality of particulate and trace gas pollutants, with 

additional profiles and total column measurements collected from the surface using 

tethered balloons, lidars, passive remote sensors, and ozonesondes. The DISCOVER-AQ 

mission will continue until 2014, with future deployments to California, San Joaquin 

Valley in January-February 2103, Houston, TX in September 2013, and a final 

deployment in Summer 2014 with the location to be determined. 
xv

APPENDIX G. FIELD CAMPAIGNS FOR NON-ROUTINE SPECIAL INTENSIVE STUDIES (continued)

CalNex 2010 NOAA

with CARB 

1 ship

4 aircraft

2 monitoring 

sites

Ozonesonde 

network

Radar wind

profiler 

network

2010

Primary pollutants (CO, NO, 

NO2, SO2, NMHC, CO2, NH3, 

PM, VOC, black carbon, and 

greenhouse gases); 

Secondary species: O3, CH2O, 

aldehydes, PAN, HNO3, NO3, 

N2O5, sulfuric acid, hydroxyl 

and peroxy radicals, aerosol 

size distribution and chemical

composition; Other 

parameters (H2O, aerosol 

properties, radiation, and 

meteorological parameters).

http://www.esrl.noaa.

gov/csd/calnex/white

paper.pdf

This is a joint field study of atmospheric processes over California and the eastern 

Pacific coastal region that emphasizes the interactions between air quality and climate 

change issues, including those affecting the hydrologic cycle. The study constitutes one 

of a series of comprehensive regional air quality and climate assessments conducted by 

NOAA with expansion of CARB’s leadership of California air quality studies. It 

complements the ongoing CEC regional climate change studies and brings together 

specialized, complementary resources such that the outcome will be able to address 

important scientific questions that have an impact on environmental policy. Airborne 

(NOAA WP-3D Orion, NOAA Twin Otter Remote Sensing Aircraft), ship (NOAA R/V 

Ronald H. Brown), on-going ground-based instrument packages (upper-air observations, 

ground-based chemical measurements), and satellite observations (MODIS, GOES) will 

be employed. The collaboration of agencies will link short-term data gathered during 

the field program to extensive surface observations, long term data sets, and 

California’s advanced modeling capabilities for both regional air quality and climate.

Arctic Research of the 

Composition of the 

Troposphere from Aircraft 

and Satellites (ARCTAS / 

POLARCAT)

NASA

(with various 

universities 

& research 

institutions)

3 aircraft

1 monitoring 

site

2008

(spring / 

summer)

Primary pollutants (CO, NO, 

NO2, SO2, NMHC, CO2, NH3, 

PM, VOC, black carbon, and 

greenhouse gases); 

Secondary species: O3, CH2O, 

aldehydes, PAN, HNO3, NO3, 

N2O5, sulfuric acid, hydroxyl 

and peroxy radicals, aerosol 

size distribution and chemical 

composition; Other 

parameters (H2O, aerosol 

properties, radiation, and 

meteorological parameters)

http://wwwair.larc.nasa.gov/missi

ons/arctas/arctas.htm

l

&

data workshop

ARCTAS is a study of the impact of air pollution and forest fires on the arctic climate 

that integrates measurements from multiple aircraft and satellites. It has four major 

scientific themes: (1) long range transport of pollution to the Arctic including arctic 

haze, tropospheric ozone, and persistent pollutants such as mercury; (2) boreal forest 

fires and their implications for atmospheric composition and climate; (3) aerosol 

radiative forcing from arctic haze, boreal fires, surface deposited black carbon, and 

other perturbations; and (4) chemical processes with focus on ozone, aerosols, 

mercury, and halogens. ARCTAS is part of a larger interagency and international IPY 

effort collectively identified as POLARCAT which is intended to execute a series of 

aircraft experiments following pollution plumes as they are transported into the Arctic.
xvi

APPENDIX G. FIELD CAMPAIGNS FOR NON-ROUTINE SPECIAL INTENSIVE STUDIES (continued)

Aerosol, Radiation, and 

Cloud Processes Affecting 

Arctic Climate (ARCPAC)

NOAA

(with 

University of 

Colorado, 

Georgia 

Institute of 

Technology, 

and NASA, 

University of 

AlaskaFairbanks)

1 aircraft 

(NOAA WP3D) in 

Fairbanks, 

Alaska

2008 

(Spring)

Primary pollutants--CO, NO, 

NO2, SO2, CO2, PM, VOCs, BC, 

GHGs; 

Secondary species-- O3, PAN, 

HNO3, sulfuric acid, BrO, BrCl, 

Cl2, Br2+HOBr, aerosol size 

distribution and chemical 

composition: 

Other parameters--H2O, 

aerosol optical properties, 

radiation, sea surface 

temperature, and 

meteorological parameters.

http://www.esrl.noaa.

gov/csd/arcpac/

ARCPAC is a field and modeling study of atmospheric chemical, microphysical, and 

radiative processes that affect Arctic climate. Particular foci of study are 1) the sources, 

transport and radiative effects of black carbon (soot) and non-absorbing particles in the 

Arctic, 2) the deposition of black carbon particles to the snow and sea-ice surface, and 

3) the effects of aerosol particles on cloud microphysical and radiative properties. 

Additional topics include the characteristics of halogen chemistry near the sea-ice 

surface, and the characteristics and atmospheric processing of pollutants emitted from 

anthropogenic sources at cold temperatures. The program includes a substantial effort 

to model the transport and transformations of pollutants in the Arctic, including 

assimilation of chemical data from satellite observations, and the effects of such 

pollutants on radiative transfer. ARCPAC is a participating campaign of the international 

POLARCAT program of the IPY, and includes substantial collaboration with the NASA 

ARCTAS and DOE ISDAC programs.

International Chemistry 

Experiment in the Arctic 

LOwer Troposphere 

(ICEALOT)

--Organized as part of the 

International Polar Year 

(IPY), and a POLARCAT 

activity--

NOAA

(with various 

universities, 

research 

institutes, 

and a 

research 

corporation)

Research 

Vessel Knorr 

(Woods Hole 

Oceanograp

hic Institute) 

with funding 

from NOAA 

/OAR Marine 

Charter Fund

2008 

(MarchApril); 

Woods Hole, 

MA; Long 

Island 

Sound/NYC; 

Tromso, 

Norway; 

Svalbard,

Norway; 

Reykjavik, 

Iceland

Aerosol measurements: light 

absorption, scattering, and 

extinction; particle 

concentration and size 

distributions; chemical 

composition; cloud nuclei 

concentrations; vertical 

profiles of aerosol 

backscatter; AOD; 

Trace gas measurements: 

ANs, ClNO2, CO, CO2, DMS, 

H2O, NO, NO2, NO3, N2O5 

NOy, O3, PANs, POPs, Rn, 

SO2, VOCs;

Meteorological and 

dynamical parameters 

http://saga.pmel.noaa

.gov/Field/icealot/

The ICEALOT field mission examined the transport and transformation of pollutants to 

and within the ice-free waters of the Arctic Ocean during springtime. The primary 

objectives were 1) to identify sources (local, regional, long-range) of pollutants in the 

marine boundary layer (MBL); 2) to examine the chemical evolution of aerosols and 

gases in the Arctic MBL, including photochemistry (both halogen and OH initiated), 

nocturnal chemistry, and physical transformations; and 3) to determine the impacts on 

the surface radiative balance from MBL aerosols and ozone, with specific focus on 

aerosol-cloud-radiative effects. A secondary objective of ICEALOT was to explore the 

wintertime chemical, photochemical, and physical processes associated with the 

evolution and transport of urban pollution into the North Atlantic MBL.

Texas Air Quality Study II 

(2005 - 2006) Texas 17 2006

O3, NOx, NOy, SO2, Haze, 

Visibility, CO, VOC, Solar 

Radiation, Surface 

Meteorology, Upper Air

http://www.utexas.ed

u/research/ceer/texa

qsII/PDF/12-12-

04_Projected_Surface

Sites_tbl.pdf

Researchers from universities, state and Federal agencies, private industry, and local 

governments joined forces to conduct a major field study to address air quality issues in 

the eastern half of Texas. The study, conducted in 2005 and 2006, examined regional 

ozone formation, transport of ozone and ozone precursors, meteorological and 

chemical modeling, issues related to ozone formation by highly reactive emissions, and 

particulate matter formation. The information from the study served as a scientific 

basis for State Implementation Plans (SIPs) for ozone (with concentrations averaged 

over 8 hours), regional haze, and fine particulate matter (particulate matter less than 

2.5 microns in diameter, PM2.5
xvii

APPENDIX G. FIELD CAMPAIGNS FOR NON-ROUTINE SPECIAL INTENSIVE STUDIES (continued)

2006 Texas Air Quality 

Study/ Gulf of Mexico 

Atmospheric Composition 

and Climate Study 

(TexAQS/GoMACCS)

NOAA 1 ship, 

2 aircraft 2006

O3, NO, NO2, NOy, VOCs, 

CO2, CO, SO2, HNO3, NH3, 

other reactive pollutants, 

aerosols, meteorological 

parameters & upper air

http://esrl.noaa.gov/c

sd/2006/

For TexAQS 2006, the NOAA air quality component investigated, through airborne and 

sea-based measurements, the sources and processes that are responsible for 

photochemical pollution and regional haze during the summertime in Texas. The focus 

of the study was the transport of ozone and ozone precursors within the state and the 

impact of the long-range transport of ozone or its precursors.

Intercontinental Chemical 

Transport Experiment -

North America (INTEX-B) --

Intercontinental Transport 

and Chemical 

Transformation (ITCT/IGAC) 

NOAA 3 aircraft 2006

O3, NO, NO2, NOy, VOCs, 

CO2, CO, SO2, HNO3, NH3, 

other reactive pollutants, 

aerosols, meteorological 

parameters, altitude -- NOAA 

aircraft

http://cloud1.arc.nasa

.gov/intex-b/

The export of air pollutants from urban to regional and global environments is a major 

concern because of wide-ranging potential consequences for human health, cultivated 

and natural ecosystems, visibility degradation, weather modification, changes in 

radiative forcing, and tropospheric oxidizing capacity. During the spring of 2006 a highly 

integrated atmospheric field experiment was performed over and around North 

America. The Megacity Initiative: Local and Global Research Observations (MILAGRO), 

http://www.eol.ucar.edu/projects/milagro/, resulted through a highly coordinated 

collaboration between NSF (through MIRAGE-Mex), DOE (through MAX-Mex), NASA 

(through INTEX-B) and a variety of research institution in the U.S. and Mexico and 

involved ground and air borne activities centered on Mexico City, Mexico during March 

2006. MILAGRO goals were greatly facilitated and enhanced by a number of concurrent 

and coordinated national and international field campaigns and global satellite 

observations. After MILAGRO, NASA continued investigating this issue, this time 

focusing on the influence of Asian pollutants on North America, through a second 

airborne field element of INTEX-B in collaboration with NSF and NCAR. The integrated 

goals of MILAGRO and INTEX are:

-To study the extent, persistence, and transformation of Mexico City pollution plumes;

-To relate atmospheric composition to sources and sinks;

-To quantify radiative properties and effects of aerosols, clouds, water vapor & 

surfaces;

-To map anthopogenic and biogenic emissions;

-To characterize transport and evolution of Asian pollution to North America and 

beyond and determine implications for regional air quality and climate;

-To achieve science-based validation of satellite observations of tropospheric 

composition
xviii

APPENDIX G. FIELD CAMPAIGNS FOR NON-ROUTINE SPECIAL INTENSIVE STUDIES (continued)

International Consortium for 

Atmospheric Research on 

Transport and 

Transformation (ICARTT)

NOAA

(with various 

other 

agencies and 

research 

institutions)

Multiple 

aircraft and 

other 

measuremen

t platforms

2004

Surface sites and networks, 

mobile platforms (aircraft 

and ship) and satellite data 

were used for 

measurement parameters; 

see 

http://www.esrl.noaa.gov/

csd/ICARTT/fieldoperations

/ for detailed information

http://www.esrl.noaa.

gov/csd/ICARTT/index

.shtml

ICARTT was formed to study the sources, sinks, chemical transformations and transport 

of ozone, aerosols and their precursors to, and over, the North Atlantic Ocean. Groups 

in North America and Europe had independently developed plans for field experiments 

in the summer of 2004 that shared many of the same goals and objectives in 

overlapping study areas; the plans were aimed at developing a better understanding of 

the factors that shape air quality in their respective countries and the remote regions of 

the North Atlantic. ICARTT was formed to take advantage of this synergy by planning 

and executing a series of coordinated experiments to study the emissions of aerosol 

and ozone precursors and their chemical transformations and removal during transport 

to, and over, the North Atlantic. The combined research conducted in the programs 

that make up ICARTT focus on regional air quality, intercontinental transport, and 

radiation balance in the atmosphere.

Intercontinental Chemical 

Transport Experiment -

North America (INTEX-NA) --

Intercontinental Transport 

and Chemical 

Transformation (ITCT/IGAC) 

NASA

aircraft, 

sondes, 

satellites

2004

O3, NO, NO2, NOy, VOCs, 

CO2, CO, SO2, HNO3, NH3, 

other reactive pollutants, 

aerosols, meteorological 

parameters, altitude -- NOAA 

aircraft

http://cloud1.arc.nasa

.gov/intexna/desc.html

INTEX-NA is an integrated atmospheric field experiment performed over and around 

North America. It seeks to understand the transport and transformation of gases and 

aerosols on transcontinental/intercontinental scales and their impact on air quality and 

climate. A particular focus in this study is to quantify and characterize the inflow and 

outflow of pollution over North America. The main constituents of interest are ozone 

and precursors, aerosols and precursors, and the long-lived greenhouse gases. INTEXNA is part of a larger international ITCT (Intercontinental Transport and Chemical 

Transformation) initiative. INTEX-NA goals are greatly facilitated and enhanced by a 

number of concurrent and coordinated national and international field campaigns and 

satellite observations. Synthesis of the ensemble of observations from surface, 

airborne, and space platforms, with the help of a hierarchy of models is an important 

goal of INTEX-NA. 

New England Air Quality 

Study (NEAQS) --

Intercontinental Transport 

and Chemical 

Transformation (ITCT) 2004

NOAA

4 site,

1 ship,

2 aircraft,

profiler 

network

2004

O3, NO, NO2, NOy, VOCs, 

CO2, CO, SO2, HNO3, NH3, 

other reactive pollutants, 

aerosols, meteorological 

parameters & upper air

http://esrl.noaa.gov/c

sd/2004/

NOAA continues a joint regional air quality and climate change study combining 

elements of the previous NEAQS study and the Intercontinental Transport and Chemical 

Transformation (ITCT) research activity to focus on air quality along the Eastern 

Seaboard and transport of North American emissions into the North Atlantic. The major 

NOAA assets (the two aircraft and the ship) are deployed in a manner that supports the 

objectives of both components.
xix

APPENDIX G. FIELD CAMPAIGNS FOR NON-ROUTINE SPECIAL INTENSIVE STUDIES (continued)

East Tennessee Ozone Study 

(ETOS) NOAA 15+ 2003 O3, Surface Meteorology http://www.arl.noaa.gov/etos_122005.php

ETOS 2003 developed a regional ozone database to include both mean hourly averages 

and hourly histograms of individual measurement readings. The 2003 study period 

(based on scoping studies 1999 - 2002) provides a regional view to supplement 

Tennessee's regulatory network and serves as a demonstration and 

evaluation/validation database for various operational and developmental air quality 

forecast model components. The full scope of ETOS 2000 is continuously under 

planning and review, and is refined each year using the previous year’s analysis and 

experience to focus on particular issues within the East Tennessee region.

Texas Air Quality Study 

(TexAQS) 2000 Texas ~20 2002

O3, NOx, PM2.5/PM10, CO, 

SO2, VOCs, Surface 

Meteorology

http://www.utexas.ed

u/research/ceer/texa

qs/visitors/about.html

The study is designed to improve understanding of the factors that control the 

formation and transport of air pollutants along the Gulf Coast of southeastern Texas. Six 

weeks of intensive sampling, including measurements of gaseous, particulate, and 

hazardous air pollutants, are made at approximately 20 ground stations, located 

throughout the eastern half of the state. Experts in meteorology, atmospheric 

chemistry, and other areas of science study the formation, composition, and day-night 

cycles of ozone and particulate matter, as well as how these pollutants are affected by 

weather.

Texas Air Quality Study 

(TexAQS) 2000 Field 

Campaign

NOAA 2 aircraft 2002

O3, CO, CO2, SO2, NO, NO2, 

NOy, PAN, HNO3, NH3, VOCs, 

Solar Radiation, 

Meteorological Parameters, 

aerosols

http://www.utexas.ed

u/research/ceer/texa

qs/visitors/about.html

Additional sampling in TexAQS 2000 is carried out with specially equipped aircraft that 

can detect air pollutants very quickly, at very low concentrations.

Bay Region Atmospheric 

Chemistry Experiment 

(BRACE)

NOAA 1 aircraft 2002 NO3, NH4, O3, SO2, NOx, CO, 

trace metals, particulates

http://hsc.usf.edu/pu

blichealth/EOH/BRAC

E/

The Florida Department of Environmental Protection (FDEP), with the support of a team 

of Federal, state, local, university and private scientists (including NOAA), conducted a 

month-long series of intensive studies to determine the level of influence of nitrogen 

deposited into Tampa Bay from local and regional sources of air pollutants on water 

quality. During the Bay Region Atmospheric Chemistry Experiment (BRACE), NOAA 

operated a research aircraft over the Tampa Bay region to collect air quality 

measurements of the many atmospheric forms of nitrogen and related pollutants that 

may potentially influence the water quality of Tampa Bay.

New England Air Quality 

Study (NEAQS) 2002 --

AIRMAP

NOAA 4 2002

O3, NOx, NOy, SO2, CO, 

VOCs, PM2.5, Precipitation 

Chemistry, Surface 

Meteorology

http://airmap.unh.ed

u/data/

AIRMAP is a research program focused on atmospheric chemical and physical 

observations in rural to semi-remote areas of New Hampshire with the goal of 

understanding inter-relationships in regional air quality, meteorology, and climatic 

phenomena. Research goals are to: (1) document and analyze current trends in the 

regional air quality of New England which is affected by transport from upwind regions 

of the U.S. and Canada and by local emission sources; (2) document and analyze current 

and past (the last 100 years) synoptic-to-local meteorological patterns, features, and 

extreme events in New England; and (3) numerically simulate the coupled evolution of 

atmospheric transport and chemistry in New England using various modeling tools.
xx

APPENDIX G. FIELD CAMPAIGNS FOR NON-ROUTINE SPECIAL INTENSIVE STUDIES (continued)

New England Air Quality 

Study (NEAQS) 2002 NOAA 1 ship, 2 aircraft 2002

O3, NO, NO2, NOy, VOCs, 

CO2, CO, SO2, HNO3, NH3, 

other reactive pollutants, 

aerosols, meteorological 

parameters & upper air

http://esrl.noaa.gov/c

sd/NEAQS/

The NOAA component of this multi-institutional effort addresses the analysis of existing 

climate data, and the development of new air quality monitoring programs. A 

background of information is to be developed that addresses New England's changing 

climate and air quality so as to improve understanding of the relationship between air 

quality and weather and determine the causes of climate change in New England

Intercontinental Transport 

and Chemical 

Transformation (ITCT) 2002 

Activities

NOAA 1 site, 

1 aircraft 2002

CO2, CO, CH4, SO2, O3, SF6, 

N2O, CFCs, Aerosols, Solar 

Radiation, Surface 

Meteorology & Upper Air --

surface. 

O3, NO, NO2, NOy, VOCs, 

CO2, CO, SO2, HNO3, NH3, 

other reactive pollutants, 

aerosols, meteorological 

parameters & upper air --

aircraft

http://esrl.noaa.gov/c

sd/ITCT/2k2/

This field program in spring 2002 investigated the composition of air masses along the 

Pacific coast of North America, is part of the Intercontinental Transport and Chemical 

Transformation (ITCT) research activity of the International Global Atmospheric 

Chemistry Program (IGAC) Program. Goals of this field study are to: characterize the 

chemical composition of the air masses coming ashore at the West Coast; explore the 

composition of these air masses as they are transported inland; and investigate the 

alteration in composition associated with the addition of emissions from U.S. West 

Coast sources. The NOAA WP-3D aircraft deployed a wide array of instrumentation for 

the in situ measurement of gaseous and aerosol parameters plus radiation and remote 

aerosol sensing by LIDAR. The Trinidad Head baseline observatory characterizes 

chemical composition of marine boundary layer at the U.S. West Coast and provides 

linkage between composition measurements and radiative properties of the aerosols. 

The NOAA ETL Laboratory network of 915-MHz radar wind profilers that are deployed 

in California provide additional meteorological information.

TRAnsport and Chemical 

Evolution over the Pacific 

(TRACE-P)

NASA 2 aircraft 2001 

(2 months)

O3, NO, NO2, N2O, CH4, SO2, 

NH3, CO, CO2, aerosols, PAN, 

HNO3, aldehydes, peroxides, 

speciated hydrocarbons, 

other pollutants, 

meteorological parameters

http://wwwgte.larc.nasa.gov/gte_

fld.htm#TRACE

TRACE-P is part of a series of aircraft missions aimed at better understanding of global 

tropospheric chemistry, and more specifically in this case, the effects of outflow from 

the Asian continent on the composition of the global atmosphere. Objectives are to 

determine: (1) pathways for outflow of chemically and radiatively important gases and 

aerosols, and their precursors, from eastern Asia to the western Pacific; and (2) the 

chemical evolution of the Asian outflow over the western Pacific, and the ensemble of 

processes that control this evolution. Approximately 20 aircraft measurement flights 

involving horizontal and vertical profiles for a total of over 300 hours were supported 

by surface-based measurements and soundings.

Aerosol Characterization 

Experiments - Asia 

(ACE-Asia)

NSF

sites, 

ships, 

aircraft, 

satellites

2001 

(spring)

aerosol chemical, physical, 

and radiative properties and 

radiative fluxes, 

meteorological parameters

http://saga.pmel.noaa

.gov/Field/aceasia/AC

EAsiaDescription.html

The Aerosol Characterization Experiments (ACE) are designed to increase understanding 

of how atmospheric aerosol particles affect the Earth’s climate system. ACE-Asia took 

place during the spring of 2001 off the coast of China, Japan and Korea which includes 

many types of aerosol particles of widely varying composition and size. These particles 

include those emitted by human activities and industrial sources, as well as wind-blown 

dust. Data from ACE-Asia is improving understanding of how atmospheric aerosols 

influence the chemical and radiative properties of the Earth’s atmosphere.
xxi

APPENDIX G. FIELD CAMPAIGNS FOR NON-ROUTINE SPECIAL INTENSIVE STUDIES (continued)

Central California Ozone 

Study (CCOS)2 California

100+ sites, 

6 aircraft, 

profilers, 

sondes

2000

O3, VOC, NOx, NO, NOy, CO, 

PM10, PM2.5, solar radiation, 

surface meteorology, upper 

air

http://www.arb.ca.go

v/airways/

For the summer season, this study collected meteorological and air quality data for the 

central section of California in 2000. Planes and weather balloons collected data at 

ground level and aloft. The data collected is used to improve the understanding of the 

role of meteorology on the formation and behavior of air pollutants and their 

precursors and emission sources and patterns. The information gathered will be used to 

develop an improved modeling system that will be used in preparing plans to attain the 

new federal 8-hour ozone standard, as well as to update the Clean Air Plan to attain the 

state ozone standard.

California Regional 

Particulate Air Quality Study 

(CRPAQS)2

California ~60 1999 

to 2001

PM2.5, PM10, nephelometer, 

with some sites adding 

SO4/NO3, OC/EC, NO2, NOy, 

PAN, SO2, surface 

meteorology

http://www.arb.ca.go

v/airways/

The California Regional PM10/PM2.5 Air Quality Study is a comprehensive 

public/private sector collaborative program to provide an improved understanding of 

particulate matter and visibility in central California. It is intended to evaluate both the 

national and State air quality standards for PM10 and PM2.5. The field programs 

consisted of 14 months of monitoring throughout the San Joaquin Valley (SJV) and 

surrounding regions, as well as intensive monitoring during summer, fall, and winter 

seasonal periods.

Southern Oxidant Study 

(SOS) 1999 Field Campaign -

- Nashville

NOAA 3 sites, 

4 aircraft 1999

O3, NO, NO2, NOy, VOCs, 

aerosols, Surface 

Meteorology & Upper Air 

(profiler), ozonesonde -- 

Surface 

O3, NO, NO2, NOy, VOCs, 

CO2, CO, SO2, HNO3, NH3, 

other reactive pollutants, 

aerosols, meteorological 

parameters, altitude -- 

Aircraft

http://esrl.noaa.gov/c

sd/SOS99/

The Southern Oxidants Study (SOS), in collaboration with other organizations and 

programs, conducted this major Field Campaign during June/July 1999. The 

Nashville/Middle Tennessee region measurements focused on an improved 

understanding of the processes that control the formation and distribution of fine 

particles and ozone. Three study themes were: local vs. regional contrasts, ozone and 

PM formation in plumes, and diurnal cycle in chemistry and meteorology. These themes 

were addressed through a series of coordinated measurements involving instrumented 

aircraft and a ground-based network of chemistry and meteorological measurements.

PM Supersite Program EPA

2 Phase I 

Sites 

7 Phase II 

Sites

1999

Measurement may include: 

PM2.5, PM10, TSP, SO4, NO3, 

EC, OC, light absorption & 

extinction, O3, CO , NOx, NO, 

NO2, NOy, HNO3, NH3, VOCs, 

Carbonyls, PAH, major ions 

and elements, surface and 

upper air meteorology

http://www.epa.gov/t

tn/amtic/supersites.ht

ml

A “Supersites Conceptual Plan” was developed and implemented in response to 

Executive and Congressional mandates and recommendations from the National 

Research Council. Atlanta and Fresno were selected as initial Phase I sites and, as a 

result of a competitive process, Baltimore, Fresno, Houston, Los Angeles, New York, 

Pittsburgh, and St. Louis were selected for Phase II. Goals generally were to characterize 

particulate matter, support health effects and exposure research, and conduct methods 

testing. Extensive monitoring, data analysis, and publication continued to 2005 with the 

preparation of a Final Report for each city.
xxii

APPENDIX G. FIELD CAMPAIGNS FOR NON-ROUTINE SPECIAL INTENSIVE STUDIES (continued)

Big Bend Regional Aerosol 

and Visibility Observational 

(BRAVO) Study

NPS/EPA 38 fixed, 

6 tracer sites 1999

SO2, SO4, PM2.5, NO3, NH4, 

major ions and elements, 

nephelometer, 

transmissometer, 

meteorological parameters & 

upper air, PFC tracer

http://vista.cira.colost

ate.edu/improve/stud

ies/BRAVO/reports/pr

ojectplan/BRAVOStud

yPlan.htm

http://www.nature.np

s.gov/air/studies/brav

o/index.cfm

The BRAVO study was conducted for four months during 1999 with the primary 

objective of identifying the causes of haze in the Big Bend National Park located in West 

Texas. This very large, collaborative study enlisted numerous participants with 

sponsorship from Federal/state agencies, private industry, and research organizations. 

The BRAVO study utilized data from a 38-site network to characterize spatial and 

temporal aerosol patterns in the atmosphere. In addition, upper-air measurements and 

extensive optical measurements of light scattering and absorption were made. Because 

monitoring and source characterization activities were conducted only in the United 

States, the study design included additional monitoring and tracer studies along the 

U.S./Mexican border. 

Indian Ocean Experiment 

(INDOEX) UCSD

6 sites, 

2 ships, 

5 aircraft, 

satellites

1999 

(4 months)

O3, NO, NO2, VOCs, CO2, CO, 

SO2, HNO3, NH3, other 

reactive pollutants, trace 

gases, aerosols, 

meteorological parameters & 

upper air

http://data.eol.ucar.e

du/codiac/projs?INDO

EX

The Indian Ocean Experiment (INDOEX) addresses questions of climate change through 

collection of in-situ data on the regional cooling effect of sulfate and other aerosols. 

The project's goal is to study natural and anthropogenic climate forcing by aerosols and 

feedbacks on regional and global climate. INDOEX field studies occur where pristine air 

masses from the southern Indian Ocean including Antarctica and not-so-clean air from 

the Indian subcontinent meet over the tropical Indian Ocean to provide a unique 

natural laboratory for studying aerosols. Scientists collect data from the water surface 

through the lower stratosphere, on the aerosol composition, reactive atmospheric 

gases, solar radiation fluxes, wind and water vapor distribution. To this end, 

investigators use multiple aircraft, ships and island stations over the Arabian Sea and 

the Indian Ocean.

Eulerian Model Evaluation 

Field Study (EMEFS) Canada ~135 1998 O3, NO2, SO2, NH3, HNO3, major ions,

http://www.ec.gc.ca/

natchem/default.asp?l

ang=en&n=9E05341A1

Under EMEFS, air and precipitation chemistry data were collected daily for two years 

over much of the eastern United States and Canada to provide data for assessing the 

performance of acid deposition and other regional scale models.

NARSTO-Northeast 1995 Multiple 559 1995 O3, NO, NOx

http://eosweb.larc.na

sa.gov/GUIDE/dataset

_documents/narsto_n

e_model.html

Measurements were made during the NARSTO-Northeast 1995 intensive field campaign 

during the period May through September. One-hour average O3, NO, and NOX 

measurement results are reported for ground surface monitoring stations operated by 

various agencies including EPA AIRS, CASTNet, ESE, Harvard University, NYSEG, PEPCO, 

and the University of Maryland.
xxiii

Footnotes:

1. EPA -- Environmental Protection Agency

 MDE -- Maryland Department of Environment

 NASA -- National Aeronautics and Space Administration

 NOAA -- National Oceanic and Atmospheric Administration

 NPS -- National Park Service

 NSF -- National Science Foundation

 CARB -- California Air Resources Board

 CEC -- California Energy Commission

 UCSD -- University of California San Diego (Scripps Institution of Oceanography)

2. This study is part of the Central California Air Quality Studies (CCAQS) which comprise the California Regional Particulate Air Quality Study (CRPAQS) and the Central California Ozone Study (CCOS). 

CCAQS is a multi-year effort of meteorological and air quality monitoring, emission inventory development, data analysis, and air quality simulation modeling. Prior studies in California included: 

Southern California Ozone Study (SCOS97) -- 1997; Integrated Monitoring Study (IMS95) -- 1995; San Joaquin Valley Air Quality Study (SJVAQS) -- 1990; SARMAP Ozone Study -- 1990; Southern 

California Air Quality Study (SCAQS) -- 1987.

APPENDIX G. FIELD CAMPAIGNS FOR NON-ROUTINE SPECIAL INTENSIVE STUDIES (continued)

SOS Nashville/Middle 

Tennessee Ozone Study TVA 116 1994-1995

O3, SO2, NO, NOy, and CO, 

VOC, Surface Meteorology, 

rawinsonde and ozonesonde 

releases, and a radar 

profiler/radar acoustic 

sounding system. -- surface 

Airborne ozone and aerosol 

lidar – aircraft

http://www.ncsu.edu/

sos/pubs/sos2/State_

of_SOS_2.pdf

This ozone-focused field study was carried out in the 11-state region surrounding 

Nashville/Middle Tennessee, beginning with a 3-week exploratory study during the 

summer of 1994 and culminating in a six-week field measurement campaign June/July 

1995. Measurements were taken at 116 ground-based and tall building and towerbased chemical and meteorological measurement sites and a series of six airborne 

chemical measurement platforms. The most significant feature of the Nashville/Middle 

Tennessee Ozone Study was a coordinated series of 40+ aircraft studies to measure 

physical and chemical characteristics of urban and industrial plumes. 

(Note: an earlier ozone-focused set of field studies was also conducted in the Atlanta, 

GA area during the summers of 1990 - 1992.)

North Atlantic Regional 

Experiment (NARE) NOAA various sites, 1 ship

1993, 1996, 

1997

O3, NO, NO2, NOx, NOy, 

VOC, Surface Meteorology

http://www.igacproje

ct.org/Newsletters

(Issue24/August 2001)

The NARE program measured the type and amount of air pollutants being transported 

from the North American continent to the Northern Atlantic Ocean. Since the Northeast 

United States and Nova Scotia, Canada, are the last land locations as air masses move 

out over the ocean, measurements were made a number of land and island sites in 

Maine, Nova Scotia, and Sable Island. Acadia National Park participated in this study
xxiv

3. Historically, there have been many other field studies in the 1960's - 1990's that are not reflected in this table that involve both fixed monitoring sites and aircraft; well known examples include 

Regional Air Pollution Study (RAPS), Large Power Plant Effluent Study (LAPPES), Northeast Corridor Regional Modeling Program (NECRMP), Northeast Regional Oxidant Study (NEROS), Persistent 

Elevated Pollutant Episode (PEPE), and Lake Michigan Ozone Study (LMOS).

4. In addition to the air monitoring networks and related studies detailed in this table that are primarily concerned with lower tropospheric air pollution, there are a large number of observations and 

studies conducted by NASA, NOAA, and others that address such topics as (1) upper tropospheric and stratospheric ozone and aerosols, (2) cloud processes, and (3) validation experiments for satellite 

observations. These studies include but are not limited to: 

-- Stratospheric Tropospheric Exchange Project (STEP) – 1987

-- Airborne Antarctic Ozone Experiment (AAOE) – 1987

-- Airborne Arctic Stratospheric Experiment (AASE) – 1989

-- Airborne Arctic Stratospheric Experiment II (AASE2) – 1992

-- Stratospheric Photochemistry Aerosols and Dynamics Experiment (SPADE) – 1993

-- Airborne Southern Hemisphere Ozone Experiment / Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA) – 1994

-- Stratospheric Tracers of Atmospheric Transport (STRAT) – 1995-1996

-- Tropical Ozone Transport Experiment (TOTE) and Vortex Ozone Transport Experiment (VOTE) – 1995-1996

-- Subsonic Aircraft: Contrail and Clouds Effects Special Study (SUCCESS) – 1996

-- Photochemistry and Ozone Loss in the Arctic Region in Summer (POLARIS) – 1997

-- Subsonic Assessment: Ozone and Nitrogen Oxide Experiment (SONEX) – 1997

-- Texas Florida Underflights A (TEFLUN) – 1998

-- The Third Convection and Moisture Experiment (CAMEX 3) – 1998

-- TRMM Brazil Validation Experiment (TRMM-LBA) – 1999

-- TRMM Kwajalein Validation Experiment (KWAJEX) – 1999

-- Nauru 1999 Field Campaign – 1999

-- South African Fire-Atmosphere Research Initiative 2000 (SAFARI) – 2000

-- SAGE III Ozone Loss and Validation Experiment (SOLVE) – 1999-2000

-- ERAST Predator-B RPV Homepage (ERAST) – 2000

-- CAMEX 4 The Fourth Convection and Moisture Experiment (CAMEX 4) – 2001

-- East Pacific Investigation of Climate (EPIC) 2001 Field Program – 2001

-- The Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL FACE) – 2002

-- The SAGE III Ozone Loss and Validation Experiment (SOLVE II) – 2003

-- The Aura Validation Experiment (AVE) – 2004

-- The Intercontinental Chemical Transport Experiment – North America (INTEX-NA) – 2004

-- The Aura Validation Experiment Houston (AVE Houston) – 2004

-- North American Monsoon Experiment (NAME) – 2004

-- Winter Storms Reconnaissance Program 2004 (WSR2004) – 2004

-- Polar Aura Validation Experiment (PAVE) – 2005

-- The Tropical Cloud Systems and Processes Mission (TCSP) – 2005

-- UAS Flight Demonstration Project 2005 – 2005
xxv

APPENDIX H. SATELLITE – BASED AIR QUALITY OBSERVING SYSTEMS1

Instrument Satellite 

Platform4

Lead 

Agency

Initiated 

/Planned Measurement Parameters2

Orbit & 

Horizontal 

Resolution

Location of 

Information 

and/or Data

OLS

(Operational Linescan System)

DMSP 

satellites DOD 1962? Identify fires and smoke plumes Polar Imagery only

http://www.losan

geles.af.mil/librar

y/factsheets/facts

heet.asp?id=5317

BUV

(Backscatter Ultraviolet 

Spectrometer)

Nimbus 4 NASA 1970-1980 O3, CO2, SO2 Sun synchronous

http://nssdc.gsfc.

nasa.gov/earth/ni

mbus_sensor.htm

l

SBUV

(Solar Backscatter Ultraviolet 

Spectrometer)

Nimbus 7 NASA 1978-1993 O3, SO2 Polar

http://nssdc.gsfc.

nasa.gov/earth/ni

mbus_sensor.htm

l

TOMS

(Total Ozone Mapping 

Spectrometer)

Nimbus 7 

Meteor 3 

Earth-Probe

NASA

1978-1993

1991-1994

1996-2005

O3, SO2, Aerosols Polar 

~100km2

http://nssdc.gsfc.

nasa.gov/earth/ni

mbus_sensor.htm

l

LIMS 

(Limb Infrared Monitor of the 

Stratosphere)

Nimbus 7 NASA 1978-1979 O3, HNO3, NO2, Polar

hhttp://nssdc.gsfc

.nasa.gov/earth/ni

mbus_sensor.htm

l

ATMOS

(Atmospheric Trace Molecule 

Spectroscopy)

Spacelab 3 

ATLAS -- 1,2,3 NASA 1985, 1992, 1993, 1994

O3, CFCl3, CF2Cl2, ClONO2, HCl, HF, 

CO, CH4, HCN, HNO3, NO, NO2, N2O, 

N2O5, Aerosols

http://asdwww.larc.nasa.go

v/spectroscopy/A

SDatmos.html

CLAES

(Cryogenic Limb Array Etalon 

Spectrometer)

UARS NASA 1991-1993 O3, CFCl3, CF2Cl2 ClONO2, CH4, HNO3, 

NO, NO2, N2O, N2O5, Aerosols

http://umpgal.gsf

c.nasa.gov/

HALOE

(Halogen Occultation 

Experiment)

UARS NASA 1991-2005 O3, HCl, HF, CH4, NO, NO2, Aerosols http://umpgal.gsf

c.nasa.gov/

ISAMS 

(Improved Stratospheric and 

Mesospheric Sounder)

UARS NASA 1991-1992 O3, CO, CH4, NO2, N2O, N2O5, 

Aerosols

http://umpgal.gsf

c.nasa.gov/

MLS

(Microwave Limb Sounder) UARS NASA 1991-1999 O3, ClO, CH3CN, HNO3, SO2 http://umpgal.gsfc.nasa.gov/

GOES Imager 

(Geostationary Operational 

Environmental Satellites)

GOES-13 

GOES-15 NOAA 1994

Fire products for WF_ABBA, HMS 

(imagery) and GASP (aerosol optical 

depth)

Geostationary

4x4 km2

http://cimss.ssec.

wisc.edu/goes/da

ta.html

GOES Sounder

(Geostationary Operational 

Environmental Satellites)

GOES-13 

GOES-15 NOAA 1994 Total column O3 Geostationary

http://cimss.ssec.

wisc.edu/goes/da

ta.html

AVHRR3 (Advanced 

Very High Resolution 

Radiometer)

AVHRR/3

NOAA-15 

NOAA-16 

NOAA-17

NOAA-18

NOAA-19

MetOp-B

NOAA

EUMETSAT

ESA

1998

2012

Aerosol optical depth, particle size 

information (over ocean) and 

vegetation/drought index products 

related to air quality through fires, and 

thermal fire products

Polar 

~1x1 km2

http://noaasis.no

aa.gov/NOAASIS/

ml/avhrr.html

http://www.esa.in

t/esaLP/SEMV68L

8IOE_LPmetop_0.

html
xxvi

APPENDIX H. SATELLITE – BASED AIR QUALITY OBSERVING SYSTEMS1 (continued)

Instrument Satellite 

Platform4

Lead 

Agency

Initiated

/Planned Measurement Parameters2

Orbit & 

Horizontal 

Resolution

Location of 

Information 

and/or Data

SBUV/23

(Solar Backscattered Ultraviolet 

Radiometer Model 2)

NOAA-16 

NOAA-17

NOAA-18

NOAA-19

NOAA 2000

Total and profile O3 from surface to 

top of atmosphere in ~5 km thick 

Umkehr layers

Polar

http://www.ozon

elayer.noaa.gov/a

ction/sbuv2.htm

MOPITT 

(Measurement of Pollution in 

the Troposphere)

EOS Terra NASA 1999 CO, CH4 Polar 

22 x 22 km2

http://www.eos.uc

ar.edu/mopitt/

MISR

(Multi-angle Imaging 

SpectroRadiomenter)

EOS Terra NASA 1999 Aerosol properties and plume height 

information near the vicinity of fires

Polar 

~1x1 km2

http://misr.jpl.nasa

.gov/

MODIS

(Moderate Resolution Imaging 

Spectroradiometer)

EOS Terra 

EOS Aqua5 NASA 19992002

O3, Aerosol optical depth, particle size 

information, fine particle fraction, and 

thermal fire products

Polar 

~1x1 km2

http://modarch.gsf

c.nasa.gov/index.p

hp

AIRS (Atmospheric 

Infrared Sounder) EOS Aqua5

NASA 2002

Total column ozone, surface 

temperature, temperature and 

moisture vertical profiles, (plus under 

development are CO and CO2 total 

column, O3 vertical distribution, and 

CH4 distribution)

Polar 

50km

http://airs.jpl.nasa.

gov/

ACE-FTS

(Atmospheric Chemistry 

Experiment – Fourier 

Transform Spectrometer)

SCISAT-1

Canadian 

Space 

Agency

2003

O3, CO,SO2, PAN, H2O, CO2, CH4, CFC11, CFC-12, N2O, NHO3, NH3, C2H4, 

CH3OH, HCOOH

Polar

http://www.ace.uw

aterloo.ca/index.ht

ml

HIRDLS

(High Resolution Dynamics 

Limb Sounder)

EOS Aura5NASA 2004 O3, CFC11, CFC12, ClONO2, CH4, 

HNO3, NO2, N2O, N2O5, Aerosols Polar

http://aura.gsfc.nas

a.gov/index.html

http://www.nasa.g

ov/mission_pages/

aura/spacecraft/ind

ex.html

MLS

(Microwave Limb Sounder) EOS Aura5

NASA 2004 O3, BrO, ClO, HOCl, HCl, CO, HCN, 

CH3CN, HNO3, N2O, OH, HO2 Polar

http://aura.gsfc.nas

a.gov/index.html

http://www.nasa.g

ov/mission_pages/

aura/spacecraft/ind

ex.html

OMI 

(Ozone Monitoring Instrument) EOS Aura5

NASA 2004 O3, BrO, OClO, HCHO, CHOCHO, NO2, 

SO2 and absorbing aerosols

Polar 

48 x 48 km2

http://aura.gsfc.nas

a.gov/index.html

http://www.nasa.g

ov/mission_pages/

aura/spacecraft/ind

ex.html

TES

 (Total Emission Spectrometer) EOS Aura5

NASA 2004 O3, CO, CH4, HNO3, NH3 Polar 

26 x 42 km2

http://aura.gsfc.nas

a.gov/index.html

http://www.nasa.g

ov/mission_pages/

aura/spacecraft/ind

ex.html

CALIOP

(Cloud Aerosol Lidar with 

Orthogonal Polarization)

CALIPSO5NASA 2005 Total aerosol backscatter, aerosol 

optical depth, and extinction

Polar 

0.3 x 0.3 km2

http://wwwcalipso.larc.nasa.go

v/about/
xxvii

APPENDIX H. SATELLITE – BASED AIR QUALITY OBSERVING SYSTEMS1 (continued)

Instrument Satellite 

Platform4

Lead 

Agency

Initiated

/Planned Measurement Parameters2

Orbit & 

Horizontal 

Resolution

Location of 

Information 

and/or Data

OMPS

(Ozone Mapping and Profiling 

Suite)

Suomi NPP 

(Suomi National 

Polar-orbiting 

Partnership)

,JPSS-1 

(Joint Polar 

Satellite System)

JPSS-2

NOAA, 

NASA, 

EUMETSAT

2011

2017

2023

Total column and vertical profile ozone 

data, aerosol index, aerosol optical 

depth, and SO2

Polar

http://jointmission.

gsfc.nasa.gov/spac

ecraft_inst.html

http://www.nesdis.

noaa.gov/jpss/

 

VIIRS

(Visible Infrared Imaging 

Radiometer Suite)

Suomi NPP

(Suomi National 

Polar-orbiting 

Partnership),

JPSS-1 

(Joint Polar 

Satellite System)

JPSS-2

NOAA, 

NASA, 

EUMETSAT

2011

2017

2023

Aerosol optical depth, suspended 

matter, aerosol particle size , and 

thermal fire products

Polar

8 x 8 km2

http://jointmission.

gsfc.nasa.gov/spac

ecraft_inst.html

http://www.nesdis.

noaa.gov/jpss/

CrIS

(Cross Track Infrared Sounder)

Suomi NPP 

(Suomi

National Polarorbiting 

Partnership),

JPSS-1

(Joint Polar 

Satellite System)

JPSS-2

NOAA, 

NASA, 

EUMETSAT

2011

2017

2023

CO, CH4, and CO2 Polar

50 x 50 km2

http://jointmission.

gsfc.nasa.gov/spac

ecraft_inst.html

http://www.nesdis.

noaa.gov/jpss/

OCO-2

(Orbiting Carbon 

Observatory-2)

OCO-2

5

NASA 2014

(planned) CO2 Polar http://oco.jpl.nasa.gov/

SAGE-III

(Stratospheric Aerosol and Gas 

Experiment)

ISS

(International 

Space Station)

NASA 2015

Aerosol extinction, ozone, water vapor, 

nitrogen dioxide, nitrogen trioxide, 

chlorine dioxide, in the mesosphere, 

stratosphere, and upper troposphere 

with a vertical resolution of 0.5 - 1 km 

resolution.

Inclined, nonsun-synchronos

http://www.nasa.g

ov/mission_pages/s

tation/research/ex

periments/1004.ht

ml

ABI

(Advanced Baseline Imager )

GOES-R 

(Geostationar

y Operational 

Environmental 

Satellite)

GOES-S

NOAA 2016

2017

Aerosol optical depth, thermal fire 

products

Geostationary

2 x2 km2

http://www.goes

-r.gov/

GLM (Geostationary Lightening 

Mapper)

GOES-R 

(Geostationar

y Operational 

Environmental 

Satellite)

GOES-S

NOAA 2016

2017

Total lightening, (in-Cloud, CloudCloud, Cloud-Ground) detection for NO 

parameterization

Geostationary

http://www.goes

-r.gov/
xxviii

 

APPENDIX H. SATELLITE – BASED AIR QUALITY OBSERVING SYSTEMS1 (continued)

Instrument Satellite 

Platform4

Lead 

Agency

Initiated

/Planned Measurement Parameters2

Orbit & 

Horizontal 

Resolution

Location of 

Information 

and/or Data

TEMPO UV-Vis Imaging 

Spectrometer

TEMPO 

(Tropospheric 

Emissions: 

Monitoring of 

Pollution

NASA NET22018

O3, NO2, SO2, HCHO, CHOCHO, AOD, 

AAOD, AI, cloud fraction, cloud top 

pressure, hourly depending on species 

and solar zenith angle (SZA)

Geostationary

8 x 4.5 km2

https://directory.eo

portal.org/web/eop

ortal/satellitemissions/t/tempo

Next Generation Aerosol 

Polarimetry Sensor (APS), 

Ocean Ecosystem 

Spectrometer/Radiometer 

(OES)

PACE 

(Preliminary 

Aerosol, 

Cloud, 

Ecosystem)

NASA NET62020 Aerosol and cloud profiles, aerosol 

optical depth, aerosol subtype Polar http://dsm.gsfc.nasa.gov/PACE.html

Cloud radar,

High Spectral Resolution Lidar

(HSRL), Multi-band UV/VIS 

Spectrometer,

Next generation Aerosol 

Polarimetry Sensor (APS)

ACE

(Aerosol 

Clouds and 

Ecosystem 

Mission)

NASA NET62023 Aerosol and cloud profiles, aerosol 

optical depth, aerosol subtype Polar

http://dsm.gsfc.n

asa.gov/ace/scie

nce.html

CO2 LIDAR

ASCENDS 

(Active 

Sensing of 

CO2 Emissions 

over Nights, 

Days, and 

Seasons)

NASA NET62023 Day/night, all-latitude, all-season CO2 

column integrals Polar

http://cce.nasa.g

ov/ascends/index

.htm

Event Imaging Spectrometer 

from GEO, 

IR Correlation Radiometer, 

UV/Vis Near IR Wide Imaging 

Spectrometer

GEO-CAPE 

(Geostationar

y Coastal and 

Air Pollution 

Events)

NASA NET32023

Baseline measurements:

O3, NO2, CO, SO2, HCHO, CH4, NH3, 

CHOCHO, different temporal sampling 

frequencies; AOD, AAOD, AI, aerosol 

optical centroid height (AOCH), hourly 

for solar zenith angle (SZA) <70

Geostationary

4 x 4 km2

http://geocape.larc.nasa.go

v/

SCIAMACHY

(Scanning Imaging Absorption 

Spectrometer for Atmospheric 

Chartography)

Envisat ESA 2002 Total column for O3, NO2, BrO, OClO, 

SO2, HCHO, CHOCHO, aerosols

Polar

60 x 30 km2

http://envisat.esa.i

nt/instruments/scia

machy/

GOME & GOME-2 

(Global Ozone Monitoring 

Experiment)

ERS-2

MetOp-A

MetOp-B

MetOp-C

EUMETSAT

ESA

1995

2006

2012

2016

Total column for O3, NO2, BrO, SO2, 

HCHO, aerosols

Polar

40 x 40 km2

http://earth.esa.int

/ers/gome/

http://www.esa.int

/esaLP/SEMTTEG23

IE_LPmetop_0.html

IASI

(Infrared Atmospheric 

Sounding Interferometer)

MetOp-A

MetOp-B

MetOp-C

ESA

2006

2012

2016

O3, CO, CH4, NH3 Polar

50 x 50 km2

http://smsc.cnes.fr

/IASI/index.htm

TROPOMI 

(Tropospheric Ozone 

Monitoring Instrument)

Sentinel-5 

Precursor 

(S5p)

ESA 2015

O3, NO2, HCHO, CHOCHO, SO2, 

aerosols. aerosol height distribution, 

CO, and CH4

Polar

http://www.esa.int

/esaLP/SEM3ZT4KX

MF_LPgmes_0.html

GEMS 

(Geostationary Environmental 

Monitoring Sensor)

GeoKOMPSAT 

(Geostationar

y Korea MultiPurpose 

Satellite)

KARI

NIER-ME 2018 O3, NO2, HCHO, SO2, aerosols Geostationary

http://database.eo

handbook.com/dat

abase/missionsum

mary.aspx?missionI

D=669
xxix

APPENDIX H. SATELLITE – BASED AIR QUALITY OBSERVING SYSTEMS1 (continued)

Sentinel 4A (Ultraviolet Visible 

Near-infrared (UVN) 

spectrometer) and thermal 

InfraRed Sounder (IRS)IRS

MTG-S1 

(Meteosat 

Third 

Generation 

Sounding 

Satellite)

EUMETSAT

EC, ESA 2019 O3, NO2, HCHO, SO2, aerosols aerosol 

height distribution CO and CH4 Geostationary

http://www.eumet

sat.int/Home/Main

/Satellites/Meteosa

tThirdGeneration/i

ndex.htm?l=en

Footnotes:

1. Some instrument systems listed (e.g., UARS/HALOE) are oriented primarily to stratospheric measurements and may have limited application to the troposphere.

2. Note that many of the satellite instruments also have the capability to measure temperature, H2O, and other parameters.

3. NOAA satellites as early as 1978 have carried AVHRR, and as early as 1985 have carried SBUV/2; as part of a cooperative effort, it is planned to carry AVHRR/3 on 

MetOp-B in 2012.

4. CALIPSO -- Cloud-Aerosol Lidar & Infrared Pathfinder Satellite Observations

 DMSP -- Defense Meteorological Satellite Program

 EC -- European Countries

 EOS -- Earth Observing System

 ESA -- European Space Agency

 EUMETSET --European Organisation for the Exploitation of Meteorological Satellites

 GOES -- Geostationary Operational Environmental Satellites

 KARI -- Korea Aerospace Research Institute

 KMA -- Korean Meteorological Agency 

 NASA -- National Aeronautics and Space Administration

NIER-ME -- National Institute of Environmental Research, Ministry of Environment, Rep. of Korea

 NOAA -- National Oceanic and Atmospheric Administration

 NPOESS -- National Polar-orbiting Operational Environmental Satellite System

 OCO-2 -- Orbiting Carbon Observatory

 UARS -- Upper Atmosphere Research Satellite

5. This satellite is part of the A-Train group of satellites. It involves satellites flying in a formation that cross the equator one satellite at a time, a few minutes apart, at 

around 1:30 pm local time. The A-Train is made up of Aqua, Aura, CALIPSO, and may eventually include OCO-2 and Glory; it also includes CloudSat (2005) – data on 

the structure of ice and water clouds, and has included PARASOL (2004) – data on the directional characteristics and polarization of light reflected by the Earth and 

atmosphere, including aerosol optical depth. Together their overlapping science instruments will give a comprehensive picture of Earth weather and climate. 

6. “NET” -- No Earlier Than
xxx

APPENDIX I.

AIR MONITORING NETWORKS FOR CLIMATE FORCING, TRANSPORT,

VERTICAL PROFILE INFORMATION, AND STRATOSPHERIC OZONE

Network

Lead 

Federal 

Agency

Number 

of Sites Initiated Measurement Parameters Location of Information and/or Data

Global Monitoring Division Baseline Observatories

Mauna Loa NOAA 1 1957

CO2, CO, CH4, SO2, O3, SF6, N2O, H2, CFCs, 

HCFCs, HFC's, Aerosols, Solar Radiation, 

Surface Meteorology

http://www.esrl.noaa.gov/gmd/o

bop/mlo/

Point Barrow NOAA 1 1973

CO2, CO, CH4, SO2, O3, SF6, N2O, H2, CFCs, 

HCFCs, HFC's, Aerosols, Solar Radiation, 

Surface Meteorology

http://www.esrl.noaa.gov/gmd/o

bop/brw/

Samoa NOAA 1 1974

CO2, CO, CH4, SO2, O3, SF6, N2O, H2, CFCs, 

HCFCs, HFC's, Aerosols, Solar Radiation, 

Surface Meteorology

http://www.esrl.noaa.gov/gmd/o

bop/smo/

South Pole NOAA 1 1957

CO2, CO, CH4, SO2, O3, SF6, N2O, H2, CFCs, 

HCFCs, HFC's, Aerosols, Solar Radiation, 

Surface Meteorology

http://www.esrl.noaa.gov/gmd/o

bop/spo/

Trinidad Head NOAA 1 2002

CO2, CO, CH4, SO2, O3, SF6, N2O, H2, CFCs, 

HCFCs, HFC's, Aerosols, Solar Radiation, 

Surface Meteorology

http://www.esrl.noaa.gov/gmd/o

bop/thd/

Summit

(Greenland) NOAA 1 2009 CO2, CH4, O3, SF6, N2O, CFCs, Surface Meteorology

http://www.esrl.noaa.gov/gmd/o

bop/sum/

Global Monitoring Division

Observatory Measurements NOAA 4 1957 See above baseline observatories http://www.esrl.noaa.gov/gmd/c

cgg/insitu.html

Cooperative fixed sites

(CCGG) NOAA 72 1967 CO2, CH4, CO, H2, N2O, and SF6, stable isotopes of CO2 and CH4

http://www.esrl.noaa.gov/gmd/c

cgg/flask.html

Surface Aerosol Measurements NOAA 29 1976 Absorption, scattering, particle number, and 

chemical composition

http://www.esrl.noaa.gov/gmd/a

ero/

Cooperative fixed sites (Ozone) NOAA 14 1974 Ozone http://www.esrl.noaa.gov/gmd/o

zwv/surfoz/index.html

SURFRAD Measurements (Solar 

radiation) NOAA 7 1993

Downwelling short wave, and long wave 

radiation. Albedo, aerosol optical depth, 

direct beam and diffuse radiation and UV 

radiation.

http://www.srrb.noaa.gov/surfra

d/

Cooperative fixed sites (Solar 

Radiation) NOAA 40 1966

Downwelling short wave, and long wave 

radiation. Albedo, aerosol optical depth, 

direct beam and diffuse radiation and UV 

radiation.

http://www.esrl.noaa.gov/gmd/g

rad/field.html

Commercial Ships NOAA 5 1986 CO2, CH4, CO, H2, N2O, and SF6, stable 

isotopes of CO2 and CH4

http://www.esrl.noaa.gov/gmd/c

cgg/flask.html

University of Washington

Cheeka Peak Observatory None 1 1997 O3, CO, Aerosols, Solar Radiation, Surface 

Meteorology

http://www.washington.edu/rese

arch/field/

Mt. Bachelor Observatory None 1 2004 O3, CO, NO/NO2, Aerosols, Hg, Surface 

Meteorology

http://research.uwb.edu/jaffegro

up/modules/mbo_plot/
xxxi

APPENDIX I. 

AIR MONITORING NETWORKS FOR CLIMATE FORCING, TRANSPORT,

VERTICAL PROFILE INFORMATION, AND STRATOSPHERIC OZONE (continued)

Vertical Profile and Other Measurement Networks

ALE / GAGE / AGAGE Network NASA 7 1978

CO, CH4, SF6, N2O, H2, CFCs, HCFCs, HFC's, 

methyl chloroform, carbon tetrachloride, 

chloroform, perchloroethylene, halons & 

others

http://cdiac.ornl.gov/ndps/alegag

e.html

Tall Tower Measurements

(GHG) NOAA 8 1992

CO2, CO, CH4, H2, CFCs, methyl chloroform, 

carbon tetrachloride, chloroform, sulfur 

hexafluoride, perchloroethylene

http://www.esrl.noaa.gov/gmd/c

cgg/towers/index.html

http://www.nacarbon.org/cginacp/web/investigations/inv_pgp

.pl?pgid=171

Aircraft Measurements

(GHG) NOAA 15 1992 CO2, CH4, CO, H2, N2O, and SF6, stable isotopes of CO2 and CH4

http://www.esrl.noaa.gov/gmd/c

cgg/aircraft/

Lidar Aerosol Measurements NOAA 4 1979 Aerosol light scattering versus altitude

http://www.esrl.noaa.gov/gmd/o

bop/mlo/programs/gmdlidar/mlo

/gmdlidar_mlo.html

NOAA Profiler Network NOAA 35 1992 Vertical wind and temperature profiles, 

surface meteorology

http://www.etl.noaa.gov/et7/dat

a/

http://www.profiler.noaa.gov/np

n/index.jsp

REALM – Regional East 

Atmospheric Lidar Mesonet NOAA 13 2004

Lidar measurements for mixing height and 

vertical profiling of aerosols, ozone and 

water vapor

http://alg.umbc.edu/REALM/REA

LM-LIDAR-Locations.htm

Ozonesonde Network NOAA 12 1986

Weekly upper air measurements of ozone, 

temperature, and humidity information 

from surface to approximately 32 km

http://www.esrl.noaa.gov/gmd/d

v/site/site_table.php

SHADOZ Network 

(Southern Hemisphere 

ADditional Ozonesondes)

NASA 12 1998 Upper air measurements of ozone, 

temperature, and humidity http://croc.gsfc.nasa.gov/shadoz/

Dobson Total Column Ozone NOAA 19 1962 Ozone http://www.esrl.noaa.gov/gmd/o

zwv/dobson/

Aircraft Measurements 

(Ozone) NOAA 9 2004 Ozone http://www.esrl.noaa.gov/gmd/ozwv/aircraft/aircraft.html

Balloon Water Vapor 

Measurements NOAA 3 1980 Water Vapor http://www.esrl.noaa.gov/gmd/ozwv/wvap/

Cooperative fixed sites 

(Halocarbons) NOAA 15 1977

CFC-11 & -12, HCFC-142b, CH2Br2, N2O, 

CS2, CHBr3, CFC-113, HCFC-22, C6H6, HCFC141b, CS2, HFC-134a, HFC-152a, CH3Br, 

CH3Cl, CH3I, SF6, CH3CCl3, CCl4, CH2Cl2, 

CHCl3, C2Cl4, C2HCl, Halon 1211,-1301,-

2402.

http://www.esrl.noaa.gov/gmd/h

ats/flask/flasks.html

Observatory Measurements 

(Halocarbons) NOAA 8 1999 See above baseline observatories http://www.esrl.noaa.gov/gmd/hats/insitu/cats/cats_conc.html

Aircraft Measurements 

(Halocarbons) NOAA 5 1989

CFC-11 & -12, HCFC-142b, CH2Br2, N2O, 

CS2, CHBr3, CFC-113, HCFC-22, C6H6, HCFC141b, CS2, HFC-134a, HFC-152a, CH3Br, 

CH3Cl, CH3I, SF6, CH3CCl3, CCl4, CH2Cl2, 

CHCl3, C2Cl4, C2HCl, Halon 1211,-1301,-

2402.

http://www.esrl.noaa.gov/gmd/c

cgg/aircraft/
xxxii

APPENDIX I. 

AIR MONITORING NETWORKS FOR CLIMATE FORCING, TRANSPORT,

VERTICAL PROFILE INFORMATION, AND STRATOSPHERIC OZONE (continued)

NEON –

The National Ecological 

Observatory Network

NSF 20

Towers 2012

Site/Flux measurements of CO2, H2O, and 

meteorological variables, 

Site measurements of AOD, incoming 

radiation, dry/wet deposition (nitrogen, 

carbon, sulfur)

Airborne/satellite remote sensing with 

spectrometer, lidar, digital camera

http://www.neoninc.org/

Ameriflux 

CO2 exchange network

DOE, NOAA, 

USDA, NASA

~50

Micrometero

logical

Towers

1996 CO2, meteorological variables http://ameriflux.ornl.gov/

FluxNet 

CO2 exchange network International

~500

Micrometero

logical

Tower Sites

1996 CO2, meteorological variables http://www.fluxnet.ornl.gov/flux

net/index.cfm

North American Carbon 

Program Atmospheric 

Observing System

Multiple 

participants

Multiple 

platforms 2001 CO, CO2, CH4 http://www.nacarbon.org/nacp/

AERONET –

AErosol RObotic NETwork

MPLNET – Micro-pulse Lidar 

Network

NASA 

co-located 

networks

~500

35

1998

2000

Aerosol spectral optical depths, aerosol size 

distributions, and precipitable water 

Aerosols and cloud layer heights

http://aeronet.gsfc.nasa.gov/inde

x.html

http://mplnet.gsfc.nasa.gov/

International Aircraft Measurements

MOZAIC 

(Measurement of ozone, 

water vapor, carbon monoxide 

and nitrogen oxides aboard 

Airbus in-service aircraft)

None

2500 Airbus 

international 

flights/year

1994 O3, H2O, CO, NOx http://www.iagos.fr/web/rubriqu

e3.html

NOXAR 

(Measurements of Nitrogen 

Oxides and Ozone Along Air 

Routes)

None

500 Swiss Air 

flights to 

U.S. and far 

east

1995 - 1996 O3, NO, NO2 http://www.iac.ethz.ch/en/resea

rch/chemie/tpeter/Noxar.html

CARIBIC

(Civil Aircraft for the Regular 

Investigation of the 

atmosphere Based on an 

Instrument Container)

None

~100 

Lufthansa 

flights

1997 CO, O3, CO, CH4, CO2, N2O, SF6, NMHC, 

Position & Meteorology and Cloud cover.

http://www.caribicatmospheric.com/

AMATRAS 

(Atmospheric Measurement 

by Airliners for Trace Species)

None

262 flights 

between 

Japan and 

Australia

1993 CO2, CH4, CO and SF6 http://www.jal.com/en/press/00

00336/img/AMATRAS.pdf

NOAA Research Observing Systems

(Systems typically incorporated in intensive field campaigns)

R/V Ronald H. Brown, 

Lockheed WP-3D 

Twin Otter

NOAA

ship

aircraft

aircraft

N/A

O3, NO, NO2, NOy, VOCs, CO2, CO, SO2, 

HNO3, NH3, other reactive pollutants, 

aerosols, meteorological parameters & 

upper air, altitude

http://esrl.noaa.gov/csd/projects

/2006/data/
xxxiii

Appendix J. Abbreviations and Acronyms

Monitoring-Related Terminology

AOD – Aerosol Optical Depth

AQI – Air Quality Index

AQS – Air Quality System

CAA – Clean Air Act

CFR – Code of Federal Regulations

CMAQ – Community Multiscale Air Quality Model

CTM – Chemical Transport Model

FEM – Federal Equivalent Method

FDDA – Four-Dimensional Data Assimilation

FRM – Federal Reference Method

FTIR – Fourier transform infrared spectroscopy

GHG – Greenhouse Gas

HAPs – Hazardous Air Pollutants

LIDAR – LIght Detection And Ranging

NAAMS – National Ambient Air Monitoring Strategy

NAAQS – National Ambient Air Quality Standards

NATA – National Air Toxics Assessment

NMOC – Non-Methane Organic Carbon

PBL – Planetary Boundary Layer

POP – Persistent Organic Pollutant

RASS – Radio-Acoustic Sounding System

SIP – State Implementation Plan

VOC – Volatile Organic Compound

Government Agencies and Sponsored Organizations

AQRS – Air Quality Research Subcommittee (CENRS)

CENRS – Committee on Environment, Natural Resources, and Sustainability

CEQ – Council on Environmental Quality

DHHS – Department of Health and Human Services

DHS – Department of Homeland Security

DOE – Department of Energy

DOI – Department of the Interior

EPA – Environmental Protection Agency

ESA – European Space Agency

EUMETSAT – European Organisation for the Exploitation of Meteorological Satellites 

GEO – Group on Earth Observations

GMES – Global Monitoring for Environment and Security

HEI – Health Effects Institute

IGAC – International Global Atmospheric Chemistry Project

NACP – North American Carbon Program

NARSTO – North American Research Strategy for Tropospheric Ozone

NAS – National Academy of Sciences

NASA – National Aeronautics and Space Administration

NCAR – National Center for Atmospheric Research
xxxiv

NOAA – National Oceanic and Atmospheric Administration

NPS – National Park Service

NRC – National Research Council

NSF – National Science Foundation

NSTC – National Science and Technology Council

NWS – National Weather Service

OFCM – Office for the Federal Coordinator for Meteorology

OMB – Office of Management and Budget

OSTP – Office of Science & Technology Policy

USGEO – United States Group on Earth Observations

USDA – United States Department of Agriculture

USFS – United States Forest Service

USGS – United States Geological Survey

WMO – World Meteorological Organization

Monitoring Networks

AERONET – Aerosol Robotic NETwork

AGAGE – Advanced Global Atmospheric Gases Experiment

AIRMoN – Atmospheric Integrated Research Monitoring Network

ALE – Atmospheric Lifetime Experiment

AMNET – Atmospheric Mercury Network (NADP)

AMoN – Ammonia Monitoring Network (NADP)

ASOS – Automated Surface Observing System (NOAA)

BSRN – Baseline Surface Radiation Network

CARIBIC – Civil Aircraft for Regular Investigation of the atmosphere Based on an Instrument 

Container

CASTNET – Clean Air Status and Trends Network

CSN – Chemical Speciation Network

GAGE – Global Atmospheric Gases Experiment

GALION – GAW Atmospheric Lidar Observation Network

GAW – Global Atmospheric Watch

GEMS – Global & regional Earth-system (Atmosphere) Monitoring using Satellite and in-situ data

GEOSS – Global Earth Observation System of Systems

IADN – Integrated Atmospheric Deposition Network

IAGOS - In-Service Aircraft for the Global Observing System

IGACO – Integrated Global Atmospheric Chemistry Observations

IMPROVE – Interagency Monitoring of Protected Visual Environments

MACC – Monitoring Atmospheric Composition and Climate

MADIS – Meteorological Data Ingest System

MDN – Mercury Deposition Network

MOZAIC – Measurement of Ozone, water vapor, carbon monoxide and nitrogen oxides aboard inservice Airbus aircraft

MPLNET – Micro Pulse Lidar Network

NADP – National Atmospheric Deposition Program (NADP)

NATTS – National Air Toxics Trends Stations

NCore – National Core Network

NDACC – Network for the Detection of Atmospheric Composition Change

NEUBREW – NOAA-EPA Brewer Spectrophotometer UV and Ozone Network
xxxv

NPN – NOAA Profiler Network

NTN – National Trends Network (NADP)

PAMS – Photochemical Assessment Monitoring Stations

SEARCH – South Eastern Aerosol Research and Characterization Study

REALM – Regional East Atmospheric Lidar Mesonet

SIRD – Supersites Integrated Relational Database

SLAMS – State and Local Air Monitoring System

SOS – Southern Oxidants Study

SURFRAD – SURFace RADiation budget observing network

TAMDAR – Tropospheric Airborne Meteorological Data Reporting

TOLNet Tropospheric Ozone Lidar Network

VIEWS – Visibility Information Exchange Web System

UATMP – Urban Air Toxics Monitoring Program

Intensive Field Campaigns

ARCTAS – Arctic Research of the Composition of the Troposphere from Aircraft and Satellites

AUSPEX – Atmospheric Utility Signatures, Predictions and Experiments

DISCOVER- AQ - Deriving Information on Surface Conditions from Column and Vertically Resolved 

Observations Relevant to Air Quality

EMEFS – Eulerian model evaluation field study

HTAP – Hemispheric Transport of Air Pollution

ICARTT – International Consortium for Atmospheric Research on Transport 

and Transformation

INTEX-NA – Intercontinental Chemical Transport Experiment North America

INTEX-B – Intercontinental Chemical Transport Experiment Phase B

ITCT – Intercontinental Transport and Chemical Transformation 

MILAGRO – Megacity Initiative: Local and Global Research Observations

NARE – North American Regional Experiment

NEAQS - ITCT 2004 – New England Air Quality Study - Intercontinental Transport and Chemical 

Transformation

POLARCAT – Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of 

Climate Chemistry, Aerosols, and Transport

RAPS – Regional Air Pollution Study

SJVAQS – San Joaquin Valley Air Quality Study

TexAQS – Texas Air Quality Study

TRACE-P – Transport and Chemical Evolution over the Pacific

Satellite-Oriented Programs, Systems & Terms

ACE – Aerosol-Cloud-Ecosystems mission

EOS – Earth Orbiting System

CALIPSO – Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellite

GEO – Geostationary satellite platform

GEO-CAPE – Geostationary Coastal and Air Pollution Events

GACM – Global Atmospheric Composition Mission

GOES – Geostationary Operational Environmental Satellites

GOME – Global Ozone Monitoring Experiment

GOSAT – Greenhouse gases Observing SATellite

JPSS – Joint Polar Satellite System
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LEO – Low Earth Orbit

MODIS – Moderate Resolution Imaging Spectroradiometer

MOPITT – Measurements of Pollution in the Troposphere

NESDIS – National Environmental Satellite, Data, and Information Service (NOAA)

NPOESS – National Polar-orbiting Operational Environmental Satellite System

NPP – NPOESS Preparatory Project

OCO – Orbiting Carbon Observatory

OMI – Ozone Monitoring Instrument

PARASOL – Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with 

Observations from a Lidar

POES – Polar Operational Environmental Satellite

PROMOTE – PROtocol MOniToring for the GMES Service Element: Atmosphere

SCIAMACHY – SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY

TEMPO – Tropospheric Emissions: Monitoring of Pollution

TOMS – Total Ozone Mapping Spectrometer

TOR – Tropospheric Ozone Residual