Global 

Monitoring

Division

2013-2017 Research Plan
Acknowledgments

Director, ESRL Global Monitoring Division, Dr. James Butler

Deputy Director, ESRL Global Monitoring Division, Dr. Russ Schnell

Lead Author, Dr. John Miller, CIRES/ESRL Global Monitoring Division

Layout and Technical Editing, Annie Reiser, ESRL Director’s Office

Photographic contributions from:

Kenneth & Gabrielle Adelman, California Coastal Records Project

Patrick Cullis, ESRL Global Monitoring Division

Forrest M. Mims III

Will von Dauster, ESRL Global Systems Division

Thanks to former and present GMD staff for additional photo and text contributions.
3 GMD 2013-2017 Research Plan

GMD Vision

A society that has access to and uses the best possible information on 

atmospheric constituents that drive climate change, stratospheric ozone 

depletion, and baseline air quality.

GMD Mission

To acquire, evaluate, and make available accurate, long-term records of 

atmospheric gases, aerosol particles, and solar radiation in a manner 

that allows the causes of change to be understood.

Global Monitoring Division (GMD)

5 GMD 2013-2017 Research Plan

Message from the Director

I was recently asked in an interview what I thought GMD’s greatest 

accomplishment to date was. I thought of the myriad significant 

publications, contributions to assessments, calibration and quality 

assurance activities, leadership roles, partnerships, and baseline 

observatories. But I ultimately had to say that the greatest success for 

GMD was having produced and maintained high-quality, long-term 

data records of atmospheric composition at over 100 sites around the 

world for up to five decades. That is not trivial and requires skilled 

scientists, technicians, and communicators to sustain it year in and year out. Collectively, 

GMD’s is a unique contribution to understanding the changing composition of Earth’s 

atmosphere and its influence on the Earth system as a whole. Though many partner with us, 

no organization in the world does what we do. 

I concluded the interview by noting that virtually all of our observations help to improve 

understanding of what is causing climate change. Many contribute to tracking the progress, 

causes, and consequences of stratospheric ozone depletion, and many also contribute to a 

better understanding of background air quality. These records, among the best in the world, 

are fundamental to the success of IPCC assessments, the quadrennial Scientific Assessments 

of Ozone Depletion, and numerous national and regional assessments and annual State of 

the Climate reports. Based entirely or in large part on data we produce, thousands of papers 

have been published in refereed literature, not only by our scientists, but by the global community as well, to whom we make all of our data available and with whom we work closely.

Over the decades, GMD’s role has been fundamentally the same – its stated objective in its 

first annual report (1972), its raison d’etre, was “to measure the necessary parameters for 

establishing trends of trace constituents important to climate change and of those elements 

that can assist in apportioning the source of changes to natural or anthropogenic sources, 

or both.” Since its beginning, GMD’s mission has not changed, and the critical data records 

continue. 

This research plan underscores that role and provides a path forward for maintaining it over 

the next five years. But it also provides directions for research coming from these records 

that is relevant to today’s scientific questions. This document guides us as we go forward 

and helps us stay on target, yet also conveys the important and unique role our mission and 

collective observations play in ensuring an adequate understanding of changes in the Earth 

System.

James H. Butler

Director
Carbon dioxide concentrations in the global atmosphere on December 31, 2010 as simulated by the CarbonTracker model. The 

Northern Hemisphere concentrations are higher at this time of the year (red colors) due to the absence of plant carbon uptake and 

the presence of fossil fuel emissions. 
 GMD 2013-2017 Research Plan 7

Table of Contents

GMD Observing Systems

Atmospheric Baseline Observatories 42

Baseline Observatory Activities 44

GMD OutreacH

Scientific Outreach—Helping Other Nations 

Develop Observing Systems 52

Public Outreach 53

GMD in the Future

Transformative Opportunities 54

Appendices

Milestones 58

A) Climate Forcing (CF) 58

B) Ozone depletion (OD) 59

C) Air Quality (AQ) 60

List of Acronyms 61 

Acknowledgments 2

About the Global Mon ito ring

Division

Background for GMD Research 10

Highlights of GMD Research 10

Global Monito ring Division

Research Struct ure

Research Structure 14

GMD’s National and International Linkages 16

GMD’s Workforce 18

Research Question s and Action s

Research Questions and Actions 22

I. Climate Forcing 23

II. Ozone Depletion 31

III. Air Quality 35
About the 

Global 

Monitoring

Division
9 GMD 2013-2017 Research Plan
Background for GMD 

Research

Highlights of GMD Research

GMD scientists have unique and globally recognized expertise in making sustained 

atmospheric observations over extended periods, interpreting those observations, 

and communicating their findings to other researchers and the public. For

example, we have:

 documented the global atmospheric distribution and varying trends of carbon 

dioxide and methane for decades, including identifying the Northern Hemisphere 

terrestrial biosphere as a large sink for carbon dioxide;

 determined that the ocean and terrestrial biosphere continue to absorb half of all 

fossil fuel-CO2

 emissions, even as they increase over time; 

 detected a 30+ year trend of increasing stratospheric water vapor that has a 

significant impact on climate.

 reported the turnaround and reduction of ozone-depleting chlorine and bromine in 

the atmosphere, and documented the stabilization of ozone depletion at the South 

Pole, the Arctic, Tropics, and Northern Hemisphere mid-latitudes.
11 GMD 2013-2017 Research Plan

Above Photo: The NOAA /

ESRL /GMD Mauna Loa 

Observatory laser radar 

(lidar). The lidar measures 

particle, water vapor, 

and temperature profiles 

in the troposphere and 

stratosphere.

 determined the amount of methane and pollutant emissions from 

oil and gas extraction at sites in the Western U.S.;

 consistently reported on the role of a multitude of long-lived gases 

other than CO2 in forcing changes in climate;

 measured a surprisingly large 12 W/m2 increase in net radiation 

over the continental United States in the last 15 years most likely 

resulting from decreasing clouds; and

 measured an increase of stratospheric aerosol since 2000 that may 

have reduced the expected warming of climate due to greenhouse 

gases over this period by 25%.

GMD scientists play a critical leadership role in the global 

atmospheric monitoring community by:

 developing and disseminating methods for highly accurate and 

precise monitoring of important atmospheric gases and surface 

radiation;

 training researchers and institutions throughout the world to 

establish new monitoring programs, including private, educational, 

and domestic and international government agencies;

 creating, maintaining, and distributing globally recognized 

calibration scales, so that the goal of integrating diverse observing 

systems throughout the world can be achieved;

 providing data critical as inputs to and for evaluation of satellite 

retrievals and global and regional atmospheric models; and

 serving on national and international committees and commissions 

to ensure coherent observing systems, high-quality data, and 

relevant science.
Global 

Monitoring

Division 

Research 

Structure
13 GMD 2013-2017 Research Plan
Research emanating from GMD’s networks addresses three major themes – climate forcing, 

stratospheric ozone depletion, and background air quality. To address these, GMD’s five 

research groups are aligned according to the observations they make and, consequently, the 

skill-sets they require – Carbon Cycle and Greenhouse Gases (CCGG), Halocarbons and other 

Trace Species (HATS), Ozone and Water Vapor (OZWV), Aerosols (AERO), and Global Surface 

Radiation (GRAD). The unique observing systems operated by each research group join at 

GMD’s baseline observatories, which serve as the backbone of the GMD observing system. 

GMD’s research groups work together in both developing and maintaining their observing 

networks and especially in understanding, interpreting, and publishing results. 

Research Structure
15 GMD 2013-2017 Research Plan

GMD’s observations and research are critical to 

sustaining and preserving long-term observing 

records around the world. Because of GMD’s 

observing systems’ broad geographic coverage, 

consistent high quality, and relevance to ongoing scientific endeavors, GMD’s influence goes 

well beyond monitoring, research, and scientific 

publications. Ultimately, GMD provides numerous products and services; fundamental, worldclass data sets and analyses for national and 

international assessments; calibration, quality 

control, and observing sites to support international networks; leadership in national and 

international organizations; and the basis for 

ensuring initialization and validation of satellite 

and modeling studies. 
There are numerous national and international drivers for GMD’s research, but three 

legislative drivers stand out. First is the National Climate Protection Act (1970), which 

underscored the importance of having a solid scientific understanding of 

climate change, virtually requiring long-term observations. GMD’s 

mission was developed in response to that Act and a 

Presidential Executive Order at about the same time. The 

next two primary drivers of GMD’s activities are the 

Global Change Research Act and the Clean Air Act, 

both in 1990, which called for a comprehensive 

and integrated United States research 

program which will assist the nation and the 

world to understand, assess, predict, and 

respond to human-induced and 

natural processes of global change, 

and brought climate and ozone 

research to the forefront. GMD’s 

mission was strengthened with 

both of these pieces of

legislation. The Clean Air Act 

specifically required NOAA 

and NASA to monitor 

stratospheric ozone and 

the compounds that 

GMD’s National and International Linkages
17 GMD 2013-2017 Research Plan

deplete it. GMD’s mission, vision, and research support the broader objectives of the 

Department of Commerce, NOAA, and OAR strategic plans, and are consistent with the 

NOAA Research Plan. But GMD’s reach goes far beyond its position within an 

agency structure. Owing to the high relevance of its measurements, 

calibrations, and quality control efforts, GMD’s contributions are 

crucial to several aspects of the U.S Global Change Research 

Program. They are central and absolutely necessary to the 

World Meteorological Organization’s (WMO) Global 

Atmospheric Watch Programme, they are a major 

component of atmospheric composition 

measurements in the Global Climate 

Observing System (GCOS), and are 

captured in the broader mission of the 

Global Earth Observing System of 

Systems (GEOSS). GMD provides 

leadership on a number of 

committees, commissions, and 

steering groups within these 

broader organizations to assist 

in achieving and sustaining 

relevant, high-quality

obsevations in the service of 

science.
The Global Monitoring Division maintains 

a federal workforce that works together 

with scientists from the University of 

Colorado’s Cooperative Institute for 

Research in Environmental Sciences 

(CIRES) and Colorado State University’s 

Cooperative Institute for Research in the 

Atmosphere (CIRA). CIRES and CIRA

Research Scientists work side-by-side with 

NOAA federal scientists in GMD’s 

laboratories and in the field, sharing in 

both the research efforts and the presentation of results at conferences and publications. The collaboration with CIRES and 

CIRA and other institutions such as the 

University of Colorado’s Institute for Arctic 

and Alpine Research (INSTAAR) provides 

GMD access to a broader range of expertise in the academic community. 

GMD’s Workforce
19 GMD 2013-2017 Research Plan

GMD federal and contracted staff collaborate with 

scientists, engineers, and technicians from over 60 

universities and agencies in the collection of 

samples and operation of instruments at the 

numerous field sites other than the six observatories. 

GMD is also involved in collaborative projects around 

the world – projects ranging from designing 

instruments, making measurements at the observatories, and conducting studies from manned and 

unmanned aircraft, ships, temporary field sites, and 

vehicles modified to take samples while in motion. 

GMD scientists are actively engaged in the scientific 

analysis of their data, leading to the publication of 

results on the web, in peer-reviewed publications, 

and international assessments.
Research 

Questions 

and Actions
21 GMD 2013-2017 Research Plan
Research Questions and 

Actions

The ultimate drivers of GMD’s observing systems 

and research are scientific questions that can be 

addressed by engaging the unique skills, 

capabilities, and observations of GMD. GMD’s 

comprehensive networks provide accurate, 

long-term measurements of greenhouse gases 

(GHGs), ozone-depleting gases, aerosols, and 

atmospheric radiation to establish a basis for

understanding the underlying causes for changes 

in climate, stratospheric ozone, and air quality— the three themes of our research. GMD’s 

long data records add greatly to understanding 

the processes that impact the budgets of greenhouse gases, ozone, aerosols, and pollutants on 

timescales of days to centuries.

Although much of GMD’s work is related to more 

than one of its themes, this document identifies 

the relevance, findings, and impacts of scientific 

questions according to the primary theme it 

supports. However, several actions stand out as 

supporting all three research themes.

Actions common to all GMD research 

questions:

 Maintain existing global and U.S. observing 

networks (Observing System Section, pp. 

41–45), including baseline observatories, 

remote sensing sites, and surface, tall tower, 

shipboard, aircraft, and balloon platforms.

These observing systems form the core 

of GMD’s research and are essential 

to international networks. Ensuring 

their continuity and quality remains 

GMD’s highest priority. They will allow 

us to continue to make research-quality 

observations of gases, aerosols, and 

radiation.

 Sustain, update, and disseminate 

measurement standard scales to help 

 ensure the quality of GMD’s measurements

 and to assure the use of the accurate scales

 throughout the entire global scientific 

 community. Global networks and the 

 science that comes from them can only be

 as good as compatibility of their

 measurements and the continuity and

 accuracy of the calibrations that support

 them. 

 Make all data and products freely available 

to scientists, the general public, and 

policy-makers in a manner that is easy to 

understand. Keeping our measurements 

and research transparent to all ensures their 

relevance and usefulness. 

 Analyze and synthesize our data and 

disseminate these results via peer-reviewed 

publications and international syntheses 

like the WMO/UNEP Ozone Assessments 

and the IPCC Assessment Reports. Scientific 

publications are the essential building 

blocks of assessments and environmental 

policy.
23 GMD 2013-2017 Research Plan

I. Climate Forcing

Fig. 2 IPCC AR4 components of radiative forcing with 

ovals highlighting GMD contributions.

Understanding the mechanisms 

of Earth’s changing climate is one 

of the grand challenges in 

Earth-system science and has 

significant implications for both 

ecosystems and society. Its

importance only increases with 

time as society grapples with 

efforts to mitigate and adapt to 

climate change. GMD is at the 

forefront of understanding the 

primary driver of this change – 

the climate forcing that arises 

from increasing levels of 

greenhouse gases and aerosols 

at global, continental, and 

regional scales.

GMD is a world leader in producing the 

regional to global-scale, long-term 

measurement records that allow 

quantification of most of the factors 

affecting climate forcing today (Fig. 2).

Greenhouse Gases:  Global monitoring of 

atmospheric greenhouse gases, in particular 

carbon dioxide (CO2), has been part of NOAA’s 

mission for over 40 years. GMD provides and 

interprets high-precision, high-accuracy 

measurements of the global abundance and 

spatial distribution of a suite of long-lived 

greenhouse gases that are the most significant 

contributors to climate forcing.  Ozone and 

stratospheric water vapor, which also have 

significant climate impacts, have been monitored 

by GMD as well.

Aerosols: Aerosols (including black carbon) are 

the largest uncertainty in climate forcing 

calculations, and are highly variable in space, 

time, and composition. Their role in radiative 

forcing is complex and can be either positive 

or negative, but they most often have a cooling effect.  Aerosols affect climate directly 

via absorption and scattering and indirectly 

through influences on cloud properties.  GMD 

focuses on the direct effects with measurements 

of aerosol optical properties that began in the 

1970s, and underwent substantial improvement 

in the 1990s.

Radiation: Changes in the radiative balance at 

Earth’s surface and at the top of the atmosphere 

result from forcing by greenhouse gases, 

aerosols, and other phenomena. Broadband 

measurements of incoming and outgoing solar 

and infrared radiation are made by GMD to 

quantify the surface radiation balance. GMD 

and its national and international partners have 

made substantial improvements in the accuracy 

of both solar and infrared measurements over 

the past 20 years, allowing detection of small 

changes in the radiation balance that have 

dramatic consequences for weather and climate.
Question CF1:  How are atmospheric levels of greenhouse gases changing and what 

are their impacts on radiative forcing?

Relevance: Long-lived GHGs like CO2, CH4, 

N2

O and halogenated gases are the most 

important contributors to global radiative 

forcing (RF). RF is the primary cause of 

climate change.

Actions Taken:  GMD has monitored greenhouse gases since 1967, and has created the 

Annual Greenhouse Gas Index (AGGI) based 

upon these high-quality data (Fig. 3) to 

track changes in RF.

What we’ve discovered: Although CO2

accounts for the majority of RF, other 

gases also make substantial contributions; 

nevertheless, 80% of the increase in RF 

since 1990 is due to increases in global CO2

concentrations.

Future Actions: GMD will continue to 

calculate the climate impact of long-lived 

GHGs, expand measurements to additional 

GHGs, and report results to the scientific 

community and public through the AGGI. 

Impact: Beyond radiative forcing, the 

continued availability of on-going, robust, 

high-quality greenhouse gas measurements 

will improve model reanalyses and 

predictions and satellite retrievals. 

Fig. 3. Greenhouse gas forcing from long-lived atmospheric 

gases has increased more than 30% since 1990.
25 GMD 2013-2017 Research Plan

Relevance: Understanding variations in sources 

and sinks of greenhouse gases is fundamental 

to any attempt at emission management and 

future predictions.

Actions Taken:  GMD has used its long-term 

atmospheric observations of GHGs to quantify 

their sources and sinks for more than 20 years. 

The most recent examples of this are the

CarbonTracker data assimilation systems for CO2

and CH4 (See p. 26). Our source/sink calculations 

are limited in accuracy by number of data, and in 

the past ten years we have increased the density 

of measurements over the U.S. as part of the 

North American Carbon Program (NACP). We 

have also begun to measure more anthropogenic 

tracers over the U.S., including halocarbons and 

a limited set of 14CO2 observations for fossil fuel 

emission identification.

What we’ve discovered: Global CO2 sinks have 

stayed roughly constant as a fraction of emissions 

over the past 50 years. U.S. sinks absorb one 

third of U.S. fossil fuel emissions, though with 

large variability (See p. 26). Global CH4 emissions 

have increased since 2007 after having been 

steady for the previous decade.

Future Actions: GMD will:

a) Improve the CarbonTracker model by 

enhancing atmospheric transport with higher 

resolution and multiple wind field inputs, by 

developing methods for assimilating aircraft 

and remote-sensing data, and by extending the 

system to analyze multiple chemical species 

such as SF6 and halocarbons.

b) Restore weekly airborne GHG measurements 

in the U.S. and collaborate with other groups 

(Earth Networks, NEON, etc.) to increase the 

number of tower-based GHG measurements, 

thereby improving the resolution and accuracy 

of emissions estimates over the U.S.

c) Take steps to initiate automated measurements of CO2

 and CH4 on commercial airliners 

and expand the use of the AirCore vertical 

profiling system. These measurements will 

improve our ability to derive sources and sinks, 

understand transport of air in and out of the 

stratosphere, and help evaluate remote sensing 

measurements.

d) In collaboration with University of Colorado, 

INSTAAR, expand the limited set of 14CO2 observations over the U.S and East Asia to provide an 

independent quantification of fossil-fuel-CO2

emissions and other greenhouse gases (e.g., 

halocarbons).

Impact: Expanding the number, location, and 

kinds of greenhouse gas measurements will 

improve calculation of North American and 

global emissions. Improved understanding of 

the North American and global carbon cycles 

(and budgets of other GHGs) will allow for better 

informed policy decisions, and enhance 

predictive capability of carbon cycle (and 

climate) models.

Question CF2:  What are the anthropogenic and natural sources and sinks of long-lived 

greenhouse gases and how are they changing over time?
CarbonTracker

Biospheric carbon flux over temperate North America derived from 

atmospheric CO2 data show inter-annual variability in carbon sources and sinks.

−8

−6

−4

−2

0

2

CO2 flux (PgCyr−1

)

2000 2002 2004 2006 2008 2010

The CarbonTracker-CO2 carbon data 

assimilation system is a global inverse 

model that focuses on North America, and 

allows us to estimate sources and sinks 

of CO2

. Its North America focus relies on 

a higher data density in this region (See 

CCGG map on p. 41). In addition to sources 

and sinks of CO2

, CarbonTracker also 

calculates atmospheric CO2 concentrations 

that are increasingly being used in regional 

carbon flux studies. CarbonTracker has 

recently been extended to allow for 

calculation of methane (CH4) emissions.

A snapshot of average CO2 concentration in the free 

troposphere (~ 2 – 10 km asl) as calculated by 

CarbonTracker. 
27 GMD 2013-2017 Research Plan

Question CF3:  How sensitive are the large reservoirs of arctic and tropical terrestrial 

carbon to rising temperatures?

Relevance: Carbon-climate feedbacks are a 

first-order uncertainty in predicting future 

climate. An enhanced understanding is critical 

for improving climate predictions and projections 

and for assessing the probability of potentially 

damaging climate feedbacks.

Actions Taken:  GMD has measured CO2 and 

CH4 at multiple arctic sites over the past 40 

years. In 2004 GMD helped establish a GHG 

measurement laboratory in Brazil that now 

measures CO2, CH4, and CO from an 

emerging Amazonian network (Outreach 

Section pp. 52–53). 

What we’ve discovered: Despite high rates of 

warming, arctic-wide CH4

 emissions have been 

stable over the past decades. 

Question CF4:  What are the historic, present, and future drivers of upper tropospheric, 

lower stratospheric water vapor abundances?

Relevance: Upper tropospheric, lower 

stratospheric (UTLS) water vapor has both 

strong sensitivity to and impact on Earth’s 

climate. Satellite measurements of water 

vapor are broad-scale, but need continual 

evaluation.

Actions Taken:  GMD has measured water 

vapor by balloon (from 2 – 30 km) since 

1980 over Boulder, CO and now does so 

above Hilo, HI and Lauder, New Zealand. 

The number of sites is minimal but 

captures the basic global features.

What we’ve discovered: Measurements 

over Boulder (Fig. 4), the longest in 

existence, show a 27% net increase in 

stratospheric water vapor since 1980. 

These measurements have played a 

significant part in improving understanding of the influence of upper-atmospheric 

water vapor on climate. 

Our measurements of the CH4

 global distribution 

indicate the recent increases in global CH4

abundance originate mainly in the tropics.

Future Actions: GMD will:

a) Continue inverse modeling of CO2, CH4 and 

other gases at more than a dozen arctic and 

boreal sites to determine how sources and sinks 

vary.

b) Add new arctic measurement sites via 

collaboration with other groups and continue 

to work with Brazilian partners on making and 

interpreting tropical measurements.

Impact: Understanding climate sensitivity of 

arctic and tropical carbon cycles will improve our 

ability to predict the probability and timing of 

potentially abrupt climate change.

Future Actions: GMD will:

a) Continue to work with the satellite and modeling communities to ensure the continuity and accuracy of global 

satellite-based water vapor retrievals.

b) Expand the number of water vapor vertical profiling sites 

to better understand drivers of trends.

Impact: An improved, ground-based observing network 

will put more confidence in estimates of water vapor feedbacks and impacts on climate change and ozone depletion. 

Fig. 4 Stratospheric water vapor trends above Boulder, as measured by 

the GMD Frost Point Hygrometer (FPH).
Question CF5:  How do the means, variability, and trends of climatically important 

aerosol optical properties vary as a function of location, time, and atmospheric 

conditions?

Relevance: The contribution of aerosol 

particles to direct radiative forcing remains 

one of the largest uncertainties in determining 

radiative forcing. It may be similar in 

magnitude (but opposite in sign) to that of 

GHGs.

Actions Taken:  GMD measures aerosol 

scattering and absorption at 24 locations 

around the globe, ranging from clean, remote 

sites (e.g. Mauna Loa), to sites with regionally 

representative aerosol types from, e.g., dust 

and biomass burning.

What we’ve discovered: Recent analyses show 

decreases in tropospheric aerosol at most 

sites with >10 year measurements. Satellite 

evaluations of aerosol extinction using GMD 

in situ data have suggested limitations in the 

satellite measurements including sensitivity 

and cloud screening errors. 

Future Actions: GMD will:

a) Collaborate with other agencies to add 

additional sites to improve spatial and 

temporal coverage of different aerosol types.

b) Augment current aerosol measurement 

systems with improved aerosol absorption, 

size distribution, and chemistry measurements

to improve determination of climate relevant 

parameters.

c) Continue to evaluate trends in aerosol 

properties (particularly absorbing aerosol, e.g. 

“black carbon”).

d) Assess surface measurements and restore 

some aerosol vertical profile measurements 

with the goal of evaluating chemical transport 

models and satellite retrievals as well as 

improving satellite algorithms based on 

aerosol type.

Impact: Addition observations will increase 

confidence in modeled calculations of aerosol 

impacts on climate change. This will decrease 

uncertainty in calculations of Earth’s climate 

sensitivity. 

Question CF6:  What changes in the worldwide radiation budget are we detecting at 

Earth’s surface and what are the causes?

Relevance: Changes in Earth’s radiation 

budget reflect the integrated influence 

of all direct and indirect climate forcing. 

Understanding these changes may be critical 

in efforts to plan solar energy development.

Actions Taken:  Increasingly accurate 

broadband solar and infrared measurements 

have been made by GMD at 15 sites in 

the U.S. and around the world since the 

mid-1990s in cooperation with the global 

Baseline Surface Radiation Network.

Fig. 5 The change in net radiation at the surface derived for continental 

U.S. over 15 years of SURFRA D measurements. This increase is mostly in 

the shortwave and is likely associated with reduced cloud cover.
29 GMD 2013-2017 Research Plan

What we’ve discovered: U.S. measurements show a 12 Wm-2 increase in net radiation since 1996, likely due 

to reduced cloud cover, much larger than expected from the direct influence of GHGs alone (Fig. 5).

Future Actions: GMD will:

a) Collaborate with agency and university partners to expand measurements and include latent and sensible 

heat flux measurements to allow for full energy budget analysis.

b) Upgrade a portion of equipment to allow for higher accuracy observations, which will allow for more rapid 

trend detection.

Impact: A ground-based measurement capability to calculate a full global energy budget will lead to a better 

understanding of the relative influences of increasing greenhouse gases and aerosols and of Earth-system 

feedbacks on climate change. It will also provide surface coverage to support and complement satellite 

retrievals.

Question CF7:  How will spectral surface albedo measurements improve our 

understanding of long-term changes in cloud and aerosol optical properties?

Relevance: Spectral surface albedo is essential 

to reconcile observed clear-sky radiation and 

the models used to predict it. It is also an 

important parameter for a broad spectrum of 

satellite retrievals.

Actions Taken:  GMD has developed a mobile 

SURFRAD site with spectral capability.

What we’ve discovered: Initial findings 

show that spectral surface albedo is highly 

variable over space and time and not correctly 

represented by models, thus demonstrating the 

need for a larger, sustained, observing network.

Ells Dutton at the 

National Renewable 

Energy Laboratory 

in 2008 installing 

pyrheliometers for a 

year-long comparison 

of commercial 

instruments used 

for direct solar beam 

measurements.

Future Actions: GMD will:

a) Augment current stationary SURFRAD 

sites with spectral surface albedo 

capabilities.

b) Add an additional mobile site.

Impact: Besides providing essential 

spectral information for better satellite 

retrievals, the ability to measure and 

understand Earth’s spectral surface albedo 

will allow retrievals of cloud optical depth 

and effective radius, retrievals of aerosol 

asymmetry parameter as a function of 

wavelength, and improved assessments of 

renewable energy potential.
GMD Calibrations

Accurate, reliable calibrations are an essential component of all high-quality monitoring programs, and are 

required for proper interpretation of measurements of atmospheric gases, aerosols, and radiation. Long-term 

drift or bias among different instruments and components must be characterized or minimized if data are to 

be reliable. For data from multiple networks to be interpreted together, they must be linked to a common 

calibration scale. Global atmospheric measurement communities, be they surface-based, in situ, or remote, 

rely on GMD to provide that linkage.

Natural-air gas standards are prepared in the 

Rocky Mountains, near Boulder. Over 500 

compressed gas cylinders were filled, calibrated, 

and distributed world-wide in 2012.

GMD calibration activities include greenhouse and other 

trace gases, column ozone, and solar radiation. GMD serves 

as the WMO/GAW Central Calibration Laboratory for five 

greenhouse gases: CO2, CH4, CO, N2O, and SF6. The GMD Solar 

Radiation Calibration Facility supports measurements at GMD 

baseline observatories and within the international Baseline 

Surface Radiation Network (BSRN). The Central Ultraviolet 

(UV) Calibration Facility provides calibration of UV monitoring 

instruments at GMD and at field sites using a portable calibrator. 

Over the years, GMD has developed instruments and 

procedures specifically for the purpose of calibration and 

quality assurance in support of long-term measurement 

goals. We also conduct research to improve the quality of our 

calibrations and to understand any differences in application of 

GMD scales among laboratories around the world.

To improve the quality of radiation, aerosol, and trace gas 

measurements worldwide, GMD will continue to:

 Maintain and improve GMD’s calibration capabilities in 

support of being the WMO calibration laboratory for a 

number of greenhouse and ozone-depleting gases, solar 

radiation, and column ozone.

 Supply calibrated reference gases, calibration services, field 

and lab instrument comparisons, exchange of samples and 

reference gases to the domestic and international science 

communities.

 Provide end-to-end (instrument-to-data archive) support 

for collaborative aerosol and WMO World Dobson Ozone 

Networks.

 Provide surface, balloon, and aircraft data necessary 

to evaluate ground and space-based remote sensing 

measurements. (See p. 34)

 Create accurate and robust calibration scales for gases we 

will begin to measure (e.g. perfluorocarbons, NF3, some 

hydrocarbons).
31 GMD 2013-2017 Research Plan

II. Ozone Depletion

Depletion of stratospheric ozone can result in enhanced UV radiation levels that increase skin cancer rates 

and adversely affect organisms and ecosystems.  Concern over these effects provided impetus for ratifying 

the 1987 Montreal Protocol, enacting the U.S. Clean Air Act of 1990, and initiating GMD’s global-scale 

monitoring of stratospheric ozone and the gases responsible for its destruction.

GMD has implemented a carefully designed network to monitor variations in ozone, ozone depleting 

substances, stratospheric aerosols, and UV radiation. GMD research has been critical in determining 

long-term changes in concentrations of stratospheric ozone and chemicals causing ozone depletion. Our 

unique long-term observational records have led to an improved understanding of the production and 

fate of stratospheric ozone and the compounds and processes that influence ozone’s abundance.  These 

advances have furthered our understanding of the fundamental atmospheric processes affecting 

stratospheric ozone and provide useable information to policy-makers for guiding the recovery of the 

ozone layer.   

OD1: Is the fully revised and amended Montreal Protocol successfully reducing the 

threat to stratospheric ozone posed by ozone-depleting substances?

Relevance: International and national controls 

on the production of ozone-depleting 

substances (ODSs) are intended to “heal” the 

ozone hole and bring UV radiation levels and 

skin cancer rates back to their pre-ozone hole 

levels.

Actions taken: GMD continues to monitor the 

abundance and global distribution of ozonedepleting substances at surface sites across the 

globe.  Changes in the summed atmospheric 

concentration of ODSs are tracked and updated 

annually with GMD’s Ozone-Depleting Gas 

Index (ODGI Fig. 6). GMD also coordinates 

with other groups (e.g. AGAGE) to compare 

independent global measurements and 

calibration scales for ODSs.

What we’ve discovered: GMD results have 

demonstrated the ongoing success of the 

Montreal Protocol and U.S. Clean Air Act in 

reducing the threat to the ozone layer. The 

summed concentration of ozone depleting 

substances has decreased steadily for over a 

decade. 

Fig. 6. NOAA Ozone-Depleting Gas Index (ODGI) derived 

from GMD’s surface observations, showing a gradual return 

towards benchmark levels (ODGI= 0 in 1980) in two regions of 

the stratosphere.
Future actions: GMD will:

a) Continue ongoing measurements of gases currently in the ODGI, and add new gases that have high 

potential for ozone depletion.

b) Inform policy-makers on the effectiveness of existing international legislation for controlling atmospheric 

levels of ODSs though international scientific assessments, the extent to which “natural” processes and climate 

change affect atmospheric concentrations of ODSs, and the extent to which ODS substitutes are offsetting the 

climate benefits provided by the Montreal Protocol.

c) Further guide ozone recovery by providing U.S. emissions estimates of ODSs and their substitutes.

Impact: National and international policy-makers will continue to have the best possible information for 

guiding recovery of the ozone layer and understanding unanticipated consequences of CFC replacements on 

climate change.

OD2: Given the atmospheric reductions in ozone-depleting substances, is stratospheric 

ozone recovering as expected?

Actions taken: GMD’s global, long-term monitoring of ozone (O3), a core element of international networks, 

helps to distinguish between short and long-term processes, and guides science to properly attribute ozone 

depletion and recovery to chemical and climate processes. GMD measures the vertical and temporal extent of 

ozone depletion at sites across the globe from its long-term record of balloon profiles and ground-based total 

column and vertical profile (Umkehr) O3 measurements and provides the only year-round measurements at 

the South Pole.

What we’ve discovered: Historically, ozone has decreased substantially as the concentrations of ODSs 

increased. During the 2000s ODSs began to decrease, which is observed in stabilization of GMD-measured 

ozone levels in Antarctica (Fig. 7).

Future actions: GMD will:

a) Evaluate whether observed changes in O3 are consistent with those expected on the basis of GMDs 

measured changes in ODSs.

b) Gauge the impact of other processes on stratospheric ozone trends such as volcanoes, increased methane 

and nitrous oxide concentrations and changes in stratospheric temperatures and circulation.

Impact: These continued efforts help ensure that policies achieve the desired goal of pre-1980 levels of 

stratospheric ozone in a about a half-century, and help understand the influence of climate change decisions 

on ozone depletion. Society will no longer face the impacts of increased UV radiation on human health and 

agriculture.
33 GMD 2013-2017 Research Plan

Figure 7: (Left) Total ozone time series capture the development of ozone hole over 50 years of GMD operations 

at South Pole. (Right) Long-term variability in the annual averages of total ozone record over Northern Middle 

latitudes as represented by data from five GMD sites.

OD3: How does ozone variability affect UV radiation at Earth’s surface?

Relevance: Although many processes affect UV radiation at Earth’s surface, decreases in UV are expected in 

areas where significant ozone recovery is observed. 

Actions taken: GMD has measured total horizontal UV spectral irradiance at two Northern Hemisphere 

sites since 1998. Since 2009, GMD has also operated six spectrometers in Antarctica (formerly operated by 

NSF). The Antarctic data record includes 24 years of continuous spectral UV measurements in a region that 

experiences the most dramatic column ozone changes on Earth.

What we’ve discovered: Total surface UV changes cannot be attributed simply to changes in column 

ozone, but that there are other atmospheric properties and processes influencing UV variability.

Future actions: GMD will focus analyses on recent data streams that will allow partitioning of observed 

UV variability into those resulting from changes in cloud cover, aerosols, and ozone.

Impact: Further understanding the influences of various human-related activities on ultraviolet 

radiation will help alleviate or prevent increased damage to agriculture and incidences of cancer in 

humans.
Comparison of GMD and satellite-based stratospheric 

water vapor measurements over Boulder, CO, showing 

how the long GMD time series helps to link the two 

shorter satellite series.

Comparison of mean 

aerosol extinction 

profiles from GMD’s 

aircraft (AA O) and 

the CALI OP lidar on 

CALIPS O based on 

flights coincident with 

satellite overpasses. 

The shaded envelopes 

are standard 

deviations of the 

observations and the 

CALIPS O error bars 

are the propagated 

uncertainties of 

the satellite lidar 

measurement.

Using GMD Data to Evaluate 

Satellite Measurements

GMD’s high-quality trace gas, aerosol, and solar radiation data are essential for evaluation and 

homogenization of various satellite records. Satellite measurements can be limited by lack of sensitivity 

to the near-surface concentrations of trace gas species, low-temporal sampling frequency, and retrieval 

algorithm assumptions. Some of GMD’s recent satellite-related activities include:

 GMD’s 30+ year record of balloon-based ozone and water vapor profiles provides an essential 

reference for merged, global satellite ozone records (TOMS, UARS, SAGE, SBUV2, Aura). In addition, 

near-real-time measurements from GMD ground-based ozone sites have helped bring new SNPP 

ozone products to maturity.

 SURFRAD data have been used to develop surface albedo products for GOES-R and MODIS. It is used 

to validate operational GOES surface down-welling shortwave radiation, EOS CERES and MODIS 

photosynthetically active radiation products, as well as several GOES-8, ASTER, and MODIS land 

surface temperature and emissivity products. Other projects include validation of the CALIOP/CloudSat 

estimates of the up- and down-welling longwave radiation.

 GMD in situ aircraft profile measurements and CALIPSO retrievals of aerosol extinction are generally in 

good agreement. However, cloud screening issues and CALIOP lidar sensitivity may limit retrievals in 

some locations.

 Data from GMD aircraft, surface sites and tall towers have been used to evaluate satellite 

measurements of CO2 (GOSAT, AIRS, TES), CH4 (SCIAMACHY, AIRS), and CO (MOPITT). Comparison with 

ground-based and aircraft data has revealed large biases, e.g. SCIAMACHY CH4 measurements were 

too high over the Amazon and GOSAT CO2 retrievals are biased over the oceans (Also see pp. 46–47).

 Unmanned and manned aircraft measurements have been successfully used for validation of Aura 

satellite accuracy in measurements of ozone and ozone-depleting substances across a range of 

latitudes and altitude.
35 GMD 2013-2017 Research Plan

III. Air Quality

aerosols, has the ability to affect the health 

of millions of Americans.  GMD strives to 

document and understand long-term trends 

and large-scale variations of these constituents 

across the United States and in the upwind 

atmosphere.  This information is critical for 

defining appropriate mitigation strategies and 

assessing the efficacy of those strategies once 

they are implemented.

GMD has made significant contributions 

to understanding air quality by making 

measurements of ozone, aerosols, and 

carbon monoxide at remote sites upwind 

of the U.S.  These results have allowed us 

to evaluate the effects of intercontinental 

transport of pollutants on background air 

quality.  Long-term changes observed by 

GMD and associated networks allow us to 

assess impacts of air quality legislation.  More 

recently, observations made at locations 

closer to pollutant emissions have been 

used to understand the distribution, sources, 

sinks, character, and chemical modification 

of atmospheric constituents (see p. 38),

including several measurement campaigns 

to understand pollutant emissions associated 

with oil and gas extraction. 

AQ1. How is intercontinental transport of pollutants influencing air quality over the 

United States and adjacent oceans?  How are these influences changing over time?

Relevance: Intercontinental transport of pollutant emissions from expanding Asian countries can 

adversely affect air quality and human health in the U.S. This influence can also restrict policy-makers’ 

options for pollution mitigation.

Actions Taken: GMD monitors ozone and other pollutants at sites both upwind of the continental U.S., 

within the continent, and downwind.

What we’ve discovered: GMD’s ozone data have played a major role in analyses showing that reductions 

in locally produced ozone are counteracted by increasing levels of episodic Asian ozone pollution. 

Long range transport has also been shown to deliver carcinogenic chemicals at one-in-a-million cancer 

benchmark concentrations.

Poor air quality, including high levels of 

hazardous pollutants, tropospheric ozone, and 
Future Actions: GMD will:

a) Continue to evaluate the contribution of long-range transport on the concentrations of ozone, carbon 

monoxide, and other pollutants reaching the U.S.

b) Quantify the effects of short-lived halogenated gases and products on tropospheric ozone and mercury 

deposition over broad atmospheric scales.

Impact: Understanding these influences, which today are poorly quantified, will afford national and 

regional policy-makers the opportunity to place realistic guidelines for emissions affecting air 

quality.

AQ2: How does the cleansing capacity of the global atmosphere vary over time, and 

how sensitive is it to anthropogenic emissions?

Relevance: Naturally-occurring atmospheric oxidants remove pollutants from the atmosphere and limit 

their environmental impacts; they are also central to the formation of tropospheric ozone. Atmospheric 

concentrations of these oxidants may be sensitive to changes in human activities and natural processes.

Actions Taken: GMD has indirectly estimated the stability of the primary atmospheric oxidant (the hydroxyl 

radical, OH by monitoring atmospheric concentrations of gases that react with this oxidant, such as methyl 

chloroform, methane, methyl halides, and chlorinated solvents.

What we’ve discovered: Measurements on a global scale demonstrated that concentrations of the OH, and 

therefore lifetimes of many trace gases, do not vary substantially from year to year. 

Future Actions: GMD will:

Continue monitoring methyl chloroform concentrations and explore the usefulness of other trace gases for 

inferring longer-term changes in atmospheric oxidant concentrations. 

Impact: Because of increasing global emissions of pollutants that are oxidized in the atmosphere, 

monitoring OH will be important for implementation of successful policies relating to emissions of a variety 

of gases.

AQ3: How does the production and extraction of fossil fuels affect air quality?

Relevance: Natural gas extraction has dramatically increased over the past decade but its 

influence on air quality is not well-quantified.

Actions Taken: GMD has initiated and participated in measurement campaigns in areas of the western 

U.S. strongly impacted by natural gas production GMD has brought a unique set of 

capabilities to these studies, drawing from the instrumentation and measurement strategies of our global 

networks.

What we’ve discovered: Elevated levels of ozone (particularly in winter) and a number of other air pollutants appear to be directly related to drill site activities (see p. 38). GMD’s published records and analyses 
37 GMD 2013-2017 Research Plan

have strongly suggested that accounting-based (i.e. “bottom-up”) calculations of emissions do 

not adequately explain observations.

Future Actions: GMD will:

a) Continue to develop airborne and mobile ground-based systems for measuring emissions associated 

with fossil-fuel extraction.

b) Continue to improve methodologies and participate in campaigns designed to characterize and 

quantify emissions associated with fossil fuel extraction.

Impact: In addition to assessing how fossil fuel extraction affects air quality, quantifying these emissions 

is essential for the assessment of the climate impact of natural gas. These findings will aid policy-makers 

in their efforts to ensure high air quality across the nation and to minimize impact of large scale, fossil 

fuel development on climate.

AQ4: How are changes in climate affecting air quality?

Relevance: Climate change can 

alter the frequency and intensity of 

natural processes (e.g., stratosphere/

troposphere exchange of ozone, forest 

fires, and dust storms) with associated 

detrimental effects on air quality. 

Actions Taken: GMD monitors vertical 

profiles of ozone at several sites and 

has recently established additional 

surface sites in the continental U.S. 

for atmospheric gas and aerosol 

measurements.

What we’ve discovered: The frequency 

of major tropospheric ozone-depletion 

events in the Arctic at Barrow appears 

to be increasing over time. Although 

substantial trends have not yet been 

noted in other regions, the long-term 

observational records we are creating 

provide the only means for quantifying 

future changes. 

Future Actions : GMD will:

a) Assess the role of climate change in long-term changes in U.S. pollutant levels.

b) Restore some capability for vertical profile measurements of aerosols and ozone.

Impact: Understanding the sensitivity of pollution to climate change is essential for design of effective 

pollution mitigation policies.
Inter-disciplinary Research: Oil

and Gas Extraction Impacts on 

Climate and Air Quality

Three GMD studies of oil and gas producing 

regions in the Rocky Mountain West (Fig. A), 

have shown enhanced amounts of pollutants 

like ozone and benzene in addition to leakage 

of the potent greenhouse gas methane. In 

2005, a study in Wyoming’s Green River 

Basin showed potentially hazardous levels of 

surface ozone resulting from emissions of NOx 

and volatile organic carbon (VOC) effluents 

associated with the production of natural gas 

in the area. In 2007, GMD began routinely 

monitoring the atmosphere’s composition at 

a tower in northeastern Colorado. Instruments 

on the tower immediately detected plumes 

of air rich with chemical pollutants including 

the potent greenhouse gas methane. Custom 

air sampling devices, including a mobile 

laboratory were developed and deployed 

in the region downwind of possible sources 

to collect chemical “fingerprints” that would 

help identify the possible sources. This study 

showed that oil and gas extraction leaked or 

vented an estimated 4 percent of all natural 

gas produced to the atmosphere. The study 

further found that emissions of benzene, a 

known carcinogen tracked and regulated by 

the EPA, also had been underestimated, and 

that oil- and gas-related emissions of volatile 

organic compounds, which contribute to 

lung-damaging ozone pollution, had been 

underestimated. Most recently, a field study in 

Utah used airborne and surface measurement 

platforms to observe large amounts of methane 

being released due to oil and gas production. 

Photo above: Mobile sampling lab. Photo (Top Right): Gaby Petron 

tells U.S. Rep. Jared Polis how she uses the mobile lab to monitor 

conditions in local oil and gas fields i.e. in Utah (Bottom Right).

Fig. A
39 GMD 2013-2017 Research Plan
GMD 

Observing

Systems
41 GMD 2013-2017 Research Plan

GMD’s data originate from its monitoring 

sites, which are functionally divided into 

five separate networks that use distinct 

technologies to measure different 

atmospheric properties. Carbon cycle 

(CCGG) and halocarbon (HATS) groups 

use in situ measurements and discrete 

air sampling to characterize trace gas 

concentrations. These measurements are 

made from a variety of platforms: e.g., 

surface sites using portable samplers, 

automated sensor suites at observatories 

and very tall (> 300 m) radio and TV towers, 

and aboard light aircraft, flying from the 

surface to as high as 8 km above sea level. 

Ozone and water vapor measurements 

(OZWV), on the other hand, are made 

regularly from surface-based, remote 

sensing instruments, balloon-based in situ 

sensors, and surface insitu instruments 

at a variety of locations worldwide. 

Measurements of in situ aerosol optical 

properties (AERO) are made at 24 regionally 

representative, long-term, surface sites 

around the globe. (Measurements of aerosol 

aircraft vertical profiles were shut down in 

2007 and 2009, but plans remain to restore 

them.) Downwelling solar and infrared 

radiation measurements (GRAD) are made 

on sun-tracking platforms at surface-based 

sites. A nearby 10-m tower is the mounting 

point for matching upwelling solar and 

infrared measurements.

Figure 8. Red circles indicate surface, balloon, 

tower or aircraft sites (See left). Several surface 

and airborne sites have ceased operation recently 

and are shown by unfilled red circles. Blue squares 

show the baseline observatories.

CCGG HATS OZWV AERO GRAD
Atmospheric Baseline Observatories

At the core of GMD’s measurement networks are the baseline observatories located at Mauna Loa, 

Hawaii; South Pole, Antarctica; Barrow, Alaska; Cape Matatula, American Samoa; Trinidad Head, 

California; and Summit, Greenland. The sites were established in order to provide sampling of very clean 

air, away from sources of pollution, so that the background atmosphere could be monitored, resulting 

in, for example, the iconic Mauna Loa CO2 time series. These observatories form the backbone of NOAA’s 

and the WMO’s efforts to monitor climate forcing, background air quality, ozone depletion and related 

phenomena.

The Baseline Observatories host monitoring projects from other federal agencies, universities, and 

international partners in order to assess the distributions and fluxes of measured greenhouse gases, 

ozone and ozone depleting compounds, aerosols, and solar radiation in the remote atmosphere.  The 

observatories conduct about 250 different measurements related to climate, ozone depletion, and 

atmospheric composition. These measurements are calibrated and maintained by a highly trained 

and stable workforce. As the need for an understanding of the climate system increases, the role of 

the atmospheric baseline observatories and the global cooperative networks will become even more 

crucial to the study of atmospheric composition as it influences climate change, ozone depletion, and 

air quality.

South Pole Observatory
43 GMD 2013-2017 Research Plan

Future Actions and Impacts: In an effort to 

strengthen the contribution of the observatories 

to our scientific understanding GMD will do the 

following:

Action: Improve infrastructure to facilitate and 

support research. 

Impact: Increased research programs and 

partnership networks collocated at the six 

baseline observatories will extend national and 

international networks. Better understanding of 

the climate, ozone, and air quality is possible with 

increased co-located data sets.

Action: Promote inter-disciplinary research 

programs at the baseline observatories.

Impact: Crosscutting “super-sites” that allow for 

multi-disciplinary and complementary science 

reduce overall logistical costs and better inform 

society with how climate impacts affect the 

planet. This will further enhance the linkages 

between the atmospheric climate system and 

oceanic, ecological, and social systems. 

American Samoa Observatory 

Mauna Loa, Hawaii Observatory

Barrow, Alaska Observatory 

Summit Greenland Observatory

Trinidad Head, California Observatory,

Copyright (C) 2002-2013 Kenneth & Gabrielle Adelman, California 

Coastal Records Project, www.Californiacoastline.org
Baseline Observatory Activities

Mauna Loa, Hawaii (Established 1957)

The Mauna Loa Observatory (MLO), located at 3397 m elevation on the Mauna Loa volcano 

massif, is the premier, long-term, atmospheric observations and research facility that has been 

continuously monitoring and collecting data related to changes in atmospheric composition 

since the 1950s. The undisturbed air, remote location, and minimal influences of vegetation and 

human activity at MLO are ideal for monitoring constituents in Earth’s background air that can 

cause climate change. MLO is also critically important for optical depth and ozone instrument 

calibrations and comparisons. 

South Pole, Antarctica (Established 1957) 

The South Pole Observatory (SPO) is located at the geographic South Pole on the Antarctic plateau 

at an elevation of 2837 m. The National Science Foundation provides the infrastructure for the 

GMD scientific operations. SPO was recently remodeled with construction completed in 2010. A 

Clean Air Sector (CAS) isolates the unique atmospheric and terrestrial conditions from South Pole 

station influences. Like MLO, the remoteness and minimal impact of life (animal or vegetable) 

provides pristine air samples.   SPO is the prime location for detecting changes in stratospheric 

ozone.

Barrow, Alaska (Established 1973)

The Barrow Observatory (BRW) is located near sea level on the north coast of Alaska. As the 

northernmost observatory, BRW is critical for defining the north-south gradients of many gases and 

other atmospheric properties.  As the Arctic continues to warm, BRW will become an increasingly 

important site for monitoring atmospheric change. Due to its unique location, dedicated staff, and 

excellent power and communications infrastructure, the Barrow Observatory is host to numerous 

cooperative research projects from around the world. Within the past decade, the number of 

scientific programs has doubled, but at present BRW has reached physical capacity and cannot 

support additional research programs without expansion of facilities.
45 GMD 2013-2017 Research Plan

Cape Matatula, American Samoa (Established 1973) 

The American Samoa Observatory (SMO) is located in the middle of the South Pacific, on the 

northeastern tip of Tutuila Island, American Samoa. SMO is a key site in the GMD networks, because 

it is the only baseline observatory in the tropical Southern Hemisphere. It is important in defining 

north-south gradients of atmospheric composition and how they change with time. It also hosts 

a long-standing comparison between measurements of the Advanced Global Atmospheric Gases 

Experiment (AGAGE) and the GMD trace gas measurements.

Trinidad Head, California (Established 2002)

Trinidad Head Observatory (THD) is located on a point jutting into the ocean along the remote 

northern coast of California approximately 40 km north of Eureka, the main regional population 

center (pop. 27,000). To the immediate west of Trinidad Head is the unobstructed Pacific Ocean 

and to the east are redwood-dominated forested lands. Trinidad Head Observatory provides an 

opportunity to observe and monitor both regional and global influences because of the relatively 

remote coastal location. 

Summit, Greenland (Established 2005)

The Greenland Environmental Observatory (SUM), on the summit of the Greenland Ice Sheet at 

3200 m elevation, was established by the U.S. National Science Foundations and the Government 

of Greenland to provide opportunities for arctic research in the 1990s. With NOAA’s engagement 

in 2003, it became a year-round, long-term monitoring site for atmospheric composition and 

investigations of the arctic environment. Summit is a unique, high-altitude, arctic site that offers 

access to the free troposphere and is free of local influences that could corrupt climatic records. 

Summit is situated ideally for studies aimed at identifying and understanding long-range, 

intercontinental transport and its influences on air and snow chemistry and surface albedo. For 

radiation measurements, it is the only arctic site with a year-round dry snow and ice background. 
New Technologies for Air

Column Sampling: 

AirCore and Global Hawk 
47 GMD 2013-2017 Research Plan

The AirCore air sampler was developed by GMD scientists and 

is carried by a weather balloon to altitudes above 30 km 

(> 98% of the atmospheric column). AirCore captures a 

vertically resolved sample of the air column in a long, 

small-diameter tube (below). After landing, its contents are 

analyzed to retrieve profiles of CO2 and CH4 that are ideal for 

evaluating satellite measurements and may prove useful for 

validating atmospheric transport models commonly used in 

weather and climate analyses.

The NASA Global Hawk Unmanned Aircraft Systems (UAS ) can 

fly continuously for 26+ hours and reach altitudes of 20 km. 

GMD measurements on the Global Hawk include greenhouse 

gases, ozone, and water vapor, which give us a unique view 

of transport in the upper troposphere and lower stratosphere.

(Right) AirCore Launch – AirCore coil is suspended below 

balloon. (Right) AirCore coil removed from flight package. 

(Left) Example profiles for CO2 and CH4 from AirCore from 

surface to the top of the atmosphere (red and green lines 

are separate profiles from the same day) (Lower Left) The 

NASA Global Hawk UAS in flight over California, where NOAA

is an equal partner by providing pilots, crew, and research 

scientists. Current and near-term future research involves 

tropical transport and chemistry trace gases, ozone, and 

water vapor.
(Right) The highly correlated time series of the 

annual disappearance of snow at Barrow (black 

line: using measured surface albedo) and the 

date of the appearance of the ‘first egg’ laid 

by black guillemots (red line) that migrate to 

Cooper Island (about 40 km away). Time for 

‘actual first egg’ (dashed line) are offset from 

melt data by about 13 days due to time required 

for gestation.

U.S. Coast Guard C130 used by GMD for regular greenhouse 

gas sampling throughout Alaska. 

Arctic Research

The Arctic is warming nearly twice as fast as the global average. In addition to affecting natural, 

economic, and cultural resources, arctic climate change may also be a driver of global climate via 

changes in surface albedo and warming-induced emissions of greenhouse gases from permafrost 

and ocean sediments. GMD has been making measurements at the Barrow observatory in 

northern Alaska since the 1970s, added another observatory at Summit, Greenland, in 2005, and 

has collaborated with international partnering observatories throughout the Arctic. Over the 

past decade GMD has worked with national and international institutions to initiate additional 

long-term surface and aircraft measurements at sites in Alaska, Canada, and Siberia. GMD has also 

participated in several short-term arctic campaigns using surface and mobile platforms to address 

various science questions related to climate forcing, ozone depletion, and air quality. Some recent 

findings from GMD’s expanded arctic measurement portfolio include:

 A 38-year record of surface ozone ties the increased frequency of ozone depletion events to the 

multi-year decline in sea ice,

 Earlier egg laying by the black guillemot is strongly correlated with surface albedo and earlier 

snowmelt dates,

 Identification of the importance of Asian biomass burning on trace gases and aerosols in the 

Arctic,

 Determination that decreasing trends in Arctic aerosol are dominated by changes in emissions 

from Eurasia rather than changes in atmospheric circulation.
49 GMD 2013-2017 Research Plan

 Greenland ice edge.

GMD Baseline Observatory in Barrow, Alaska.
GMD 

Outreach
51 GMD 2013-2017 Research Plan
Delegation of Chinese scientists during 2010 visit to GMD. Dr. Luciana Gatti with greenhouse gas analysis 

system in Sao Paulo, Brazil.

Scientific Outreach—Helping Other Nations Develop Observing Systems

By sharing expertise, GMD scientists have helped institutions throughout the world develop and improve 

their observing systems. Many of GMD’s global networks have expanded via collaboration between GMD 

scientists and scientists at various domestic and international agencies, institutions, and universities. The 

advantage of this cooperative approach is increased global coverage and collection of high-quality data 

which would not otherwise be possible by GMD alone. GMD’s efforts in this respect are strongly endorsed 

by WMO in its efforts to build observing and research capacity. Some ways in which GMD has reached out 

to the wider scientific community include: 

 In 1994, GMD scientists helped the Chinese Meteorological Agency (CMA) establish an air sampling 

and in situ CO2 measurement capability at the Mt. Waliguan Observatory (WLG) in Qinghai Province, 

China. 

 In 2005, GMD helped deploy a full aerosol system at WLG. WLG continues to operate today and is a 

background WMO Global Atmosphere Watch (GAW) site and the anchor for an emerging greenhouse 

gas monitoring network. 

 In 2010, a delegation of 15 CMA scientists spent ten days in Boulder and two at Mauna Loa to learn 

about everything from measurement approaches to site logistics to CarbonTracker.

 Starting in 2003, GMD established a replica of our high-accuracy, high-precision, greenhouse 

gas analysis system in Sao Paulo, Brazil. Since 2004, this system has measured greenhouse gas 

concentrations from background sites on the Brazilian Atlantic coast and at four aircraft sites in the 

Brazilian Amazon, which represent some of the only regular greenhouse gas observations above the 

tropical terrestrial biosphere.

 GMD was instrumental in expanding the Baseline Surface Radiation Network (BSRN), establishing 

radiation monitoring sites for numerous countries.

 GMD scientists continue to assist with Peru’s Dobson ozone observing program and with regional 

ozone calibration centers in South America and Africa.
53 GMD 2013-2017 Research Plan

Public Outreach

GMD’s educational outreach is two-tiered. The first tier is directed at K-12 education so that 

children are exposed to the environmental sciences. Familiarity with environmental sciences 

at an early age may pique an interest in a student who will go on to study in this important 

research area.

The second tier is management of the ESRL Student Program. This program is specifically 

directed toward advanced high school students, undergraduates, graduate students, and, in 

some cases, post-doctoral scientists. The purpose of the ESRL Student Program is to actively 

involve highly motivated students in the scientific research process. Several of the students 

are currently in Master’s and Ph.D. programs. This program began in 2008 and is housed within 

GMD. 

Outreach is a significant part of the lives of GMD staff working at our six observatory sites. The 

remote locations provide a unique opportunity to educate and inform societies that otherwise 

may have limited access to this kind of information. For example, scientists and technicians 

at our baseline observatory in Barrow, Alaska were fundamental in implementing a summer 

science program for Inupiat high school students in the North Slope region of Alaska. Visits to 

our observatories aid in carrying our message to the general public.

 GMD scientists are active in supporting events such as science fairs and science open 

houses, giving talks to secondary school children both in the classroom and in the 

laboratories, and inviting domestic and international visitors to the laboratory for tours. 

 The South Pole winter-over crew responds to e-mail queries from classrooms throughout 

the world about life in Antarctica. 

 Educational activities conducted at Mauna Loa and Barrow directly involve students at local 

schools. The Samoa Observatory staff has been involved with the tribal communities of the 

island, fostering a sense of community and promoting science education.

Patricia Lang teaches kids about air sampling during Earth Day 

demonstrations at NOAA .

The future success of scientific research 

conducted at GMD and elsewhere 

depends on educating the public and 

providing forums to bring scientists and the 

community together. As a broad range of 

decisions made by society around the world 

will increasingly require an understanding 

of science in general and Earth-system 

science in particular, the need to inform 

and educate the public becomes a growing 

responsibility of all.
GMD in the 

Future

Transformative Opportunities 

Should opportunities arise, GMD currently has the capability to transform existing observing systems, 

greatly enhancing the information needed for society to mitigate and adapt to climate change, and to 

make optimal decisions regarding ozone depletion and air quality. Today we see a near-term demand for 

increased information relative to greenhouse gas emissions, climate change feedbacks, renewable energy 

development, air quality, and ozone depletion. Some specific examples are listed below. 

Commercial Aircraft Greenhouse Gas Observations

Instrumentation for the primary greenhouse gases (CO2 and CH4) that is sufficiently precise and stable to run 

unattended for a long time has recently become available. GMD is poised to initiate a program that deploys 

them on a few dozen commercial aircraft. This would increase the number of vertical profile measurements 

by two orders of magnitude at very modest cost, transforming the use of inverse models for estimating 

sources and sinks of greenhouse gases. 

Carbon-14 Measurements

It is feasible today to start an intensive systematic program for measuring 14C in CO2. Five thousand samples per 

year around North America, requiring one dedicated accelerator mass spectrometer, would cleanly separate 

the observation of CO2 emitted by fossil fuel combustion from natural CO2 sources and sinks. This would 

provide an independent verification of reported fossil fuel CO2 emission inventories, especially needed in times 

where greenhouse gas emissions have an economic cost attached. Additionally, unbiased, observationallybased estimates of fossil fuel CO2

 would minimize bias in estimates of natural sources and sinks in models like 

CarbonTracker.

Global Greenhouse Gas Reference Network

GMD could significantly boost its calibration, data management and quality control activities to ensure 

coherent measurements among emerging independent networks. GMD would serve as a greenhouse gas 

reference network for a diverse set of regional, national, and international networks. This would substantially 

enhance the value and use of information from diverse networks.

Upper Atmospheric Research

Intensify measurements of water vapor in the upper troposphere and lower stratosphere. With increasing 

climate change, water vapor amounts are now rising in the upper atmosphere, producing both ozone-depletion 

impacts and climate change feedbacks. We can combine the balloon-borne water vapor measurements with 

AirCore, so that we would not only track H2O vapor, but also provide a diagnosis of ongoing changes of 

stratospheric circulation. 
55 GMD 2013-2017 Research Plan

Renewable Energy 

GMD has the potential to help transform the nation’s electric power system from one that depends mostly 

on coal and gas for generation to one that increasingly depends on renewable sources. Integrating solar 

collecting systems into the nation’s grid requires reliable forecasts, which in turn depend upon high-quality 

observations to support them. GMD has the expertise to provide the required ground-based measurements 

of solar irradiance for data assimilation, model improvement, and verification. Accurate forecasts will enable 

power grid operators to schedule the optimal mix of power generation sources and avoid excessive backup reserves. This would be a key step in any successful climate-change mitigation strategy. 

Arctic Observations

The Arctic has been warming more rapidly than any other large region on Earth, and part of this warming 

has been attributed to absorption of sunlight by black carbon aerosols in the air, snow, and ice.  An enhanced 

black carbon measurement network in the Arctic, including improved instrumentation at new and existing 

stations, as well as instrumented aircraft monitoring black carbon aerosols above clouds, would transform 

our understanding of the role of black carbon in driving Arctic climate change and greatly improve arctic 

forecast models.

Can natural gas be a “bridge” fuel toward renewable energy sources? 

GMD measurements are showing that the current emissions inventories of leaks associated with the full “life 

cycle” of natural gas are inadequate, potentially misleading policy choices. A carefully designed, transparent, 

and objective atmospheric observing system can provide useful, accurate information for industry and 

policy-makers that is necessary for achieving the potential of natural gas as a low-carbon energy source.
Appendices
57 GMD 2013-2017 Research Plan
Milestones

A) Climate Forcing (CF)

Action Milestone 2013 2014 2015 2016 2017

CF1: Update the AGGI X X X X X

CF2a: Update standard CarbonTracker (CT) X X X X X

CF2b: Implement multiple transport models for CT X X 

CF2c: Use aircraft in situ, and ground- and satellite-remote 

sensing data in CT

X X

CF2d: Enhance measurement capacity and capability for 

non-CO2 GHG measurements

X

CF2e: Provide N. American non-CO2

 GHG emission from 

CT and data-centric approaches. 

 X 

CF2f: Incorporate 14CO2 (Fossil Fuel) into CT X

CF2g: Add four new 14CO2 sites X X 

CF2h: Add four regular AirCore sites X X

CF2i: Begin commercial aircraft CO2 and CH4 X

CF3a: Develop Arctic Regional Inverse model X

CF3b: Develop S. American Regional Inverse model X

CF4: Add one new water vapor profile site X X

CF5a: Add one new aerosol site X X

CF5b: Upgrade instrumentation at current aerosol sites X X X

CF6a: Add latent and sensible heat measurements to sites X

CF6b: Upgrade accuracy of current equipment at radiation 

sites

X X

CF7a: Add spectral albedo to SURFRAD sites X X X X

CF7b: Add one mobile SURFRAD site X
59 GMD 2013-2017 Research Plan

Action Milestone 2013 2014 2015 2016 2017

OD1a: Update the ODGI X X X X X

OD1b: Publish 17-yr global datasets for CHBr3

, CH2Br2, and 

CH3

I

X

OD1c:

Provide N. American emissions of ODSs derived 

from modeling and data-centric (using CO and 

14CO2

) techniques

X X X

OD1d: Provide Aircore stratospheric measurements of 

ODSs

X X X

OD2: Contribute to WMO/UNEP Ozone Assessment X X

OD3: Add two additional UV sites X X

OD4: Reprocess all GMD ozone-sonde historical records 

for homogenization of long-term time series

X

OD5:

Reprocess all GMD Dobson ozone data with the 

new ozone absorption cross sections, and automate 

using new software

X X

OD6: Publish cross-platform comparisons of ozone 

profiles at MLO

X

OD7: Calibrate World standard Dobson at MLO X X

OD8: Calibrate JMA and BoM Dobson Regional Standards 

in Boulder

X

OD9: Calibrate NOAA network Dobson instruments 

against World Standard

X X

B) Ozone depletion (OD)
Action Milestone 2013 2014 2015 2016 2017

AQ1a: Use North American data to assess formation 

mechanisms of ozone over the U.S.

X

AQ1b:

Use North American data to assess cancer 

risks from Hazardous Air Pollutants entering 

the U.S.

X

AQ1c: Use observations of brominated gases to 

assess the atmospheric mercury budget

X

AQ2: Optimize OH in global inverse model using 

multiple gases 

X

AQ3a: Add aerosol and ozone sensors to mobile lab X X

AQ3b: Measure oil and gas emissions in important 

basins

X X

AQ4: Convert all surface ozone data collection to 

an automated data processing system

X X X

C) Air Quality (AQ)
61 GMD 2013-2017 Research Plan

List of Acronyms

Organizations and Networks

AERO – AEROsols, GMD group 

AGAGE – Advanced Global Atmospheric Gases Experiment network

BSRN – Baseline Surface Radiation Network

CCGG – Carbon Cycle and Greenhouse Gases, GMD group

CIRA – Cooperative Institute for Research in the Atmosphere

CIRES – Cooperative Institute for Research in Environmental Sciences

EPA – Environmental Protection Agency

ESRL – NOAA’s Earth System Research Laboratory

GAW – WMO’s Global Atmosphere Watch

GCOS – Global Climate Observing System

GEO – Group on Earth Observations

GMD – Global Monitoring Division

GRAD – Global surface RADiation, GMD group

HATS – HAlocarbons and other Trace Species, GMD group

INSTAAR – Institute of Arctic and Alpine Research, University of Colorado

IPCC – Intergovernmental Panel on Climate Change

NACP – North American Carbon Program

NASA – National Aeronautics and Space Administration

NEON – National Ecological Observatory Network

NOAA – National Oceanic and Atmospheric Administration

NSF – National Science Foundation

OAR – NOAA’s office of Oceanic and Atmospheric Research

OZWV – Ozone and Water Vapor, GMD group

SURFRAD – Surface Radiation network

UNEP – United Nations Environment Programme

WCRP -- World Climate Research Programme

WMO – World Meteorological Organization

Chemical compounds

CFC – Chlorofluorocarbon

CHBr3

 -- Bromoform

CH2

Br2 -- Dibromomethane

CH3I – Methyl Iodide

CH4

 – Methane

CO – Carbon Monoxide

14C – Carbon-14, or radiocarbon

14CO2

 – Carbon-14 CO2

CO2 – Carbon Dioxide

O3 – Ozone

OH – Hydroxyl (radical)

N2O – Nitrous Oxide

NF3 – Nitrogen Triflouride

NOx

 – Nitrogen Oxides

SF6 – Sulfur Hexafluoride

VOC – volatile organic carbon
Satellites and Satellite Sensors

AIRS – Atmospheric InfraRed Sounder; satellite sensor

CALIOP – Cloud-Aerosol LIdar with Orthogonal Polarization (sensor on CALIPSO)

CALIPSO – Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations

CERES – Clouds and the Earth’s Radiant Energy System satellite

CloudSat – Part of EOS, uses radar to observe clouds

EOS – Earth Observing System satellites

GOES, GOES-R, GOES-8 – Geostationary Operational Environmental Satellites

GOSAT – Greenhouse gases Observing SATellite

MODIS – MODerate resolution Imaging Spectroradiometer satellite

MOPITT – Measurements Of Pollution In The Troposphere satellite

OCO-2 - Orbiting Carbon Observatory satellite

SAGE – Stratospheric Aerosol and Gas Experiment satellite

SBUV2 – Solar Backscatter Ultraviolet Radiometer satellite

SCHIMACHY - SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY 

SNPP – Suomi National Polar Partnership satellite 

TES – Tropospheric Emission Spectrometer sensor

TOMS – Total Ozone Mapping Spectrometer sensor

UARS – Upper Atmosphere Research Satellite

Other

AAO – Airborne Atmospheric Observatory

AGGI – Annual Greenhouse Gas Index

AR4 – Fourth Assessment Report of the IPCC

ARO – Atmospheric Research Observatory

asl – above sea level

CAS – clean air sector

CT – CarbonTracker

GHG – Greenhouse Gas

HAP – Hazardous air pollutant

NOAA FPH – NOAA GMD Frost Point Hygrometer

ODGI – Ozone-Depleting Gas Index

ODS – Ozone-Depleting Substance

PgCyr-1 – Petagrams of Carbon per year, or Billion Tonnes of Carbon per year

ppb – parts per billion

ppm – parts per million

ppmV – parts per million (by volume)

RF – Radiative Forcing

TOA – Top of Atmosphere

UAV – Unmanned Ariel Vehicle

UTLS – Upper Troposphere/Lower Stratosphere

UV – Ultraviolet

W m-2 – Watts per meter squared, unit of radiative forcing

WLG – Mt Waliguan, China, Observatory
63 GMD 2013-2017 Research Plan

Smoothed representation of the north-south distributions of CO2 (top) and CH4 (bottom) between 2003 and 2012. 

Measurements of CO2 and CH4 at remote sites are smoothed in time and then smoothed in latitude (north-south). 

Warmer colors in the Northern Hemisphere for both CO2 and CH4 are indicative of the presence of emissions. Both 

gases also exhibit strong seasonal cycles in their atmospheric abundances.
Global Monitoring Division 

NOAA/OAR/ESRL/GMD

325 Broadway

Boulder, CO 80305-3328

303-497-6074

http://esrl.noaa.gov/gmd/

NOAA Research 

NOAA/OAR

1315 East West Highway

Silver Spring, MD 20910

301-713-2458

http://oar.noaa.gov