Cover photo credits 

First top left: The sun photometers shown is part of a global network that measures aerosols from the ground. This 

station is in the Canadian Arctic. Photograph by Ovidiu Pancrati, ©2007 CANDAC; available from the National 

Aeronautics and Space Administration, http://earthobservatory.nasa.gov/Features/Aerosols/printall.php

Second top left: Two-dimensional scanning electron microscope image (a) and elemental maps (b, c) of 

carbonaceous particle with Ba and Ca inclusions. Photo: NIST, J. Conney 

Across center: Satellite image from iStockphoto 

Disclaimer 

This report was prepared as an account of work sponsored by the National Institute of Standards and Technology (NIST), a nonregulatory agency of the U.S. Department of Commerce. NIST promotes U.S. innovation and competitiveness by advancing 

measurement science, standards, and technology. The views and opinions expressed herein do not necessarily state or reflect 

those of NIST. Certain commercial entities, equipment, or materials may be identified in this document in order to illustrate a

point or concept. Such identification is not intended to imply recommendation or endorsement by NIST, nor is it intended to 

imply that the entities, materials, or equipment are necessarily the best available for the purpose.
Acknowledgements

Many thanks to all who participated in the workshop on Aerosol Metrology for Climate held at the National Institute of Standards 

and Technology (NIST) on March 14-15, 2011. The presentations and discussions that took place at the workshop provided the 

foundation for this report. A complete list of attendees is provided in Appendix A. 

Special thanks are extended to the members of the NIST organizing committee, plenary speakers, and session chairs, listed 

below. A complete list of presentations is provided in Appendix B; these can be downloaded at 

http://www.nist.gov/mml/aerosol_metrology_for_climate_workshop.cfm

NIST Organizing Committee 

Carlos Gonzalez 

Sean McGivern 

Dianne Poster 

John Small 

Roger van Zee 

James Whetstone

Plenary Speakers 

Peter Buseck, Arizona State University 

Raymond Hoff, University of Maryland, Baltimore County 

Mark Jacobson, Stanford University 

Ralph Kahn, NASA Goddard Space Flight Center 

Dorothy Koch, United States Department of Energy 

Charles Kolb, Aerodyne Research, Inc. 

Rao Kotamarthi, Argonne National Laboratory 

Daniel Lack, National Oceanic and Atmospheric Administration, ESRL Chemical 

Carrie Masiello, Rice University 

Frank Raes, European Commission Joint Research Centre 

Stephen Schwartz, Brookhaven National Laboratory 

Rodney Weber, Georgia Institute of Technology 

Ping Yang, Texas A&M University 

Session Chairs 

Chemical/Dimensional Metrology 

Peter Buseck, Arizona State University 

Charles Kolb, Aerodyne Research, Inc. 

Rodney Weber, Georgia Institute of Technology 

Optical Properties 

Stephen Schwartz, Brookhaven National Laboratory 

Daniel Lack, National Oceanic and Atmospheric Administration, ESRL Chemical 

Carrie Masiello, Rice University 

Ping Yang, Texas A&M University 

Modeling 

Rao Kotamarthi, Argonne National Laboratory 

Ralph Kahn, NASA Goddard Space Flight Center 

Mark Jacobson, Stanford University 

Special thanks are extended to: the Energetics Incorporated team who provided support for workshop registration, planning, 

facilitation, and preparation of the final report; Donna Kimball of the NIST Materials Measurement Laboratory, for outstanding 

logistical and administrative support; and to Angela Ellis and the staff of NIST Conference Services for their diligent support of 

workshop preparation and logistics. 

For more information about this report, please contact the NIST Office of Special Programs at 301-975-2000.
Preface 

The National Institute of Standards and Technology (NIST) held a workshop on Aerosol Metrology for Climate on 

March 14–15, 2011, to assess the measurement science challenges faced by the atmospheric aerosol community and 

identify strategies to best address these challenges. The workshop brought together leading experts from industry, 

government, and academia to identify areas where actions are needed to enable better measurement of aerosols and 

further understand their potential role in climate change. This report is based on discussions held during the 

workshop, and will potentially guide NIST and other organizations as they set future research priorities for aerosols 

measurement and standards. 
Table of Contents 

1. Introduction ................................................................................................................ 1

2. Chemical/Dimensional Metrology ............................................................................... 3

3. Optical Properties .................................................................................................... 15

4. Modeling .................................................................................................................. 27

Collaborative Models ..................................................................................................... 37

Appendix A. Workshop Participants .............................................................................. 39

Appendix B. Speaker Presentations .............................................................................. 41

Appendix C. References and Additional Resources ...................................................... 43
The Blue Marble: Next Generation is a series of images that show the color of the Earth’s surface for each month of 2004 

at very high resolution (500 meters/pixel) at a global scale. Source: NASA 

http://earthobservatory.nasa.gov/Features/BlueMarble/

The Visible Infrared Imager Radiometer Suite (VIIRS) on the NPOESS Preparatory Project (NPP) satellite gets a 

complete view of our planet every day from a vantage 500 miles above. Shown above is the first complete global image 

from VIIRS taken November 24, 2011. Once VIIRS is fully operational it will produce a range of measurements from 

ocean temperature to clouds to the locations of fires. Source: NASA 

http://earthobservatory.nasa.gov/IOTD/view.php?id=76674
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

1

1. Introduction 

Background on Aerosols and Climate 

Aerosols in the atmosphere have a profound influence on regional and global climate primarily through 

interaction with solar radiation. Atmospheric aerosols are suspensions of liquid or solid particles in air 

with diameters that span a wide range, from nanometers to tens of micrometers. Aerosols have a range of 

compositions and shapes depending on their source and how they change with atmospheric processes. In 

many cases, the aerosols of greatest interest are those of in the 0.05 to 10 micrometer (μm) diameter size 

range, which are dominant in the direct interaction of aerosols with sunlight. Particles outside this size 

range can also have a significant impact on solar radiation. Smaller particles play a major role in cloud 

formation, resulting in an indirect effect on incoming solar radiation. Larger particles, generally derived 

from dust and volcanic sources, have substantial atmospheric mass loadings and can also have important 

effects on the regional and global radiation budget.

Policy makers, regulators, industrial leaders, and climate scientists require quantitative information about 

the physical and chemical properties of aerosol particles, particularly how these affect the interaction of 

aerosols with solar radiation in the atmosphere. While the importance of a range of aerosol characteristics 

and processes in the climate system is becoming better understood, many questions remain to be 

answered. For example, how much of a climate-cooling influence do aerosols presently exert? How 

effective are climate models at accounting for the influence of aerosols? How do uncertainties in aerosol 

properties affect model uncertainties, and how large are those uncertainties?

Answering these questions will depend in many cases on adequate measurement science capabilities. 

Atmospheric aerosols show large variations in size, morphology, chemical composition, and optical 

properties, and these characteristics can create complex measurement challenges. 

Workshop Scope and Objectives 

To explore the measurement challenges impeding characterization of aerosols for climate, the National 

Institute of Standards and Technology (NIST) sponsored the Aerosol Metrology for Climate workshop on 

March 14-15, 2011, in Gaithersburg, Maryland. The 

workshop brought together experts from government, 

industry and academia to explore the state of the art in 

measuring the size, shape, chemical composition, 

atmospheric evolution, and optical properties of 

aerosol particles. From that springboard, participants 

identified areas of high uncertainty in aerosol 

properties and generated ideas for overcoming the 

current challenges—information that will accelerate 

the development of new measurement technologies and 

shape the aerosol metrology climate research agenda. 

The workshop discussions and presentations are the 

foundation for this report. 

Three important topical areas were covered, as shown 

in Figure 1.1: chemical/dimensional metrology, optical 

properties of aerosols, and modeling. 

Figure 1.1. Workshop Topics 

Chemical/dimensional metrology – 

measurement challenges related to 

understanding the chemical makeup of 

aerosols, which is needed to understand 

their absorptive and reflective radiative 

properties. 

Optical properties – measurement science 

issues related to measurement and 

characterization of aerosols properties via 

optical schemes. 

Modeling of aerosols – challenges related to 

improving the representation of processes 

contributing to aerosol climate effects in 

models and simulations. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

2 

Issues considered for each of the three areas included: 

 Vision and goals for the future. 

– What are the most important properties to measure? Are existing methods/ 

technologies adequate? Where is innovation needed? What classes/sizes of aerosols 

should be investigated? 

– What would we like to achieve in aerosols metrology over the next 5, 10, and 15 years 

and beyond? 

– What capabilities will be needed in this area that we do not have today? What 

classes/sizes of aerosols should be investigated? 

– What are some specific goals or targets for aerosol metrology relevant to the topic? 

What are the most important properties to measure? 

 Challenges and barriers to achieving the vision and goals. 

– What are the major technical impediments, challenges, limitations, or barriers 

preventing us from reaching the vision for the future and goals? 

– What specific measurement problems must be addressed to enable useful 

measurements of aerosols and their impacts on climate? 

– Are existing methods/technologies adequate? Where are innovations and 

improvements required? 

– What infrastructure is currently lacking to support aerosols metrology? 

 Potential pathways, solutions, and approaches to overcoming the challenges and barriers. 

– What actions are needed (e.g., research, development, demonstration, reference 

materials and standards) and in what timeframe? 

– What will be gained by these actions? 

This report is organized around the three topic areas shown in Figure 1-1, and covers workshop 

discussions for the key issues noted above. In addition, for each topic, a set of actionable priorities have 

been identified and these are outlined in detail. These represent some of the most important actions that 

could be taken to address the current measurement challenges for aerosols. References and additional 

sources for the report are provided in Appendix C. 

Overall, this report provides a snapshot of the modern aerosol metrology landscape and a visionary guide 

for future research directions throughout the aerosol and climate community.
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

3

2. Chemical/Dimensional Metrology 

Understanding an atmospheric particle’s chemical composition is important as it determines the optical 

properties of the particle (absorptive and reflective radiative properties) and affects atmospheric chemistry 

in both the gas and particulate phase. Of particular interest is how aerosol chemical composition 

influences the ability of particles to act as cloud condensation nuclei (CCN) or ice nuclei (IN) which can 

impact cloud formation or patterns and lead to changes in climate. The chemical composition, size, and 

number of particles in a unit volume of air will define the aerosol’s light extinction (scattering and 

absorption) properties and radiative forcing potential. 

Chemical metrology involves the measurement of the chemical characteristics (e.g., elemental and 

subcomponent composition) of aerosols; dimensional metrology provides information about the physical 

size and characteristics. Chemical metrology relies primarily on spectroscopy and traditional chemical 

methods. Dimensional metrology requires the use of a variety of physical scales to determine dimension, 

with the most accurate of these being holographic etalons or laser interferometers. While techniques are 

available today, there are a number of challenges that must be overcome. 

State of the Art 

Core tools for chemical/dimensional metrology include analytical atomic spectrometry and inorganic 

mass spectrometry, gas and liquid chromatography, organic mass spectrometry, and chemical separations 

for both organic and inorganic trace analysis. The scanning electron microscope (SEM) and transmission 

electron microscope (TEM) are powerful methods for the nanoscale characterization of materials and can 

be applied to aerosol particles. To gain the most from these tools, it is necessary to understand 

uncertainties in the measurement process and allow for errors during the data capture and analysis stages. 

Replicated measurements and statistical analyses enable consideration of repeatability and reproducibility 

issues and give precision to the measurements. Addressing 

accuracy issues is more problematic because some of the 

errors are systematic and non-statistical in nature, and in 

almost all cases the true value of the measurand is 

unknown.1

 

An overview of some of the measurement tools and 

methods used to characterize the chemical and 

dimensional properties of aerosols is shown in Table 2.1. 

Today these measurements are used for research studies, 

to provide input to climate models, and for various 

monitoring purposes (e.g., regional air quality, climate 

trends). There are a number of efforts ongoing to 

characterize and study aerosols within the context of 

climate. These involve developing capabilities for a range 

of applications from basic science to field measurement. 

The emphasis in most cases is a combination of 

atmospheric science, fundamental chemistry, and aerosol 

chemistry. 

 

1 Accuracy issues in chemical and dimensional metrology in the SEM and TEM, John Henry Scott, 

http://iopscience.iop.org/0957-0233/18/9/003; http://www.nrc-cnrc.gc.ca/eng/programs/inms/chemical-metrology.html 

Image of cubes of magnesium oxide using 3-dimensional 

(3-D) chemical imaging methods and a scanning 

transmission electron microscope. Photo: NIST, 

J.H. Scott, J. Bonevich. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

4 

Table 2.1. Selected Tools and Instrumentation for 

Chemical and Dimensional Metrology for Aerosols 

Characterization Methods by Instrument/Type2,3

Sealed Wave Channel 

While common use is for physical oceanography and fluid mechanics studies, the wave 

channel can be modified by adding a sealed atmospheric chamber to enable 

measurements of aerosol composition and microphysics, trace gas and heterogeneous 

chemistry, and wave-induced bubble bursting 

Aerosol Time of Flight 

Mass Spectrometer 

(ATOFMS) 

This instrument is capable of measuring the size, density, optical properties, and chemical 

composition of single aerosol particles in real time, simultaneously; used extensively in 

both laboratory and field experiments for 15 years; provides data on the mixing state of 

airborne particulate matter 

Chemical Ionization of 

Flight Mass Spectrometer 

(CI-TOFMS) 

Now used to understand the behavior of key gaseous compounds in a simulated marine 

environment and relevant gas-particle interactions in the atmosphere 

Fourier Transform Infrared 

(FT-IR) Spectroscopy of 

Aerosol Particles 

Offline FT-IR spectroscopy offers capability for detailed characterization of the chemical 

composition and magnitude of organic fractions in sea spray under a range of different 

meteorological and oceanic conditions 

Computational Methods 

for Modeling 

Heterogeneous Chemistry 

New methodologies for modeling heterogeneous physicochemical processes on aerosol 

particles are being developed and implemented in the AMBER4 suites of programs for 

molecular dynamics simulations; treatment of molecular motion at the quantum-mechanical 

level is combined with the underlying multidimensional potential energy surface 

Condensation Particle 

Counters Measures total particle number concentrations for particles larger than 3 nanometers (nm) 

Particle Size Distribution 

Optical particle counters measure particle size distributions in the size range from 0.1 μm 

to 3 nm with selectable size-bin ranges (e.g., Passive Cavity Aerosol Spectrometer Probe); 

differential electrical mobility analyzer systems size particle concentrations in the range 

from 3 nm to 1 μm (e.g., Scanning Mobility Particle Sizing System, Electrostatic Classifier) 

Particle Chemical 

Composition 

Semi-continuous bulk organic carbon (OC)/elemental carbon (EC) composition (Sunset 

Laboratory OC/EC Analyzer); real-time single particle composition of major inorganic 

(sulfate, nitrate, ammonium) and some organic species (Aerodyne Aerosol Mass 

Spectrometer); time-resolved aerosol collector (TRAC) for post-analysis of particle 

composition (PNNL-built) 

SEM/TEM/ESEM 

Both the scanning electron microscope (SEM) and transmission electron microscope 

(TEM) are powerful methods for the nanoscale characterization of materials. 

Environmental scanning electron microscope (ESEM) can analyze wet, uncoated samples 

in a low-pressure gaseous environment 

 

2 http://caice.ucsd.edu/Research_Tools.html 3 http://www.pnl.gov/atmospheric/programs/aerosol.stm 4

 Assisted Model Building with Energy Refinement. http://ambermd.org/
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

5

Table 2.2 illustrates some of these efforts and the type of methodologies being employed.

Table 2.2. 

Selected Ongoing Efforts in Chemical/Dimensional Metrology for Aerosols 

Organization Measurement Focus 

Aerosol Chemistry and 

Climate Institute5

 R&D bridging the fields of atmospheric science and fundamental molecular science 

and chemistry; partnership between the U.S. Department of Energy’s Pacific 

Northwest National Laboratory and the University of California at San Diego 

The Center for Aerosol 

Impacts on Climate and the 

Environment (CAICE) 

 Understanding heterogeneous chemical processes at a level that allows predictions 

to be made on atmospheric chemistry and climate; developing new approaches to 

perform fundamental studies in a controlled manner on complex multiphase chemical 

systems located at the University of California San Diego, is a Phase I Center for 

Chemical Innovation funded by the National Science Foundation 

National Oceanic and 

Atmospheric Administration 

(NOAA), Earth System 

Research Laboratory (ESRL), 

Chemical Sciences Division6

 Measurement methods for aerosol optical and chemical properties; airborne field 

studies to characterize the "real world' aerosol properties and sources; and remotesensing measurements of aerosols using both ground-based and airborne platforms; 

development of aerosol-cloud models; and model evaluation 

World Meteorological 

Organization (WMO)7

 Global Atmospheric Watch (GAW) stations conducting aerosol chemical size and 

distribution measurements for multiple purposes: long-term trending, assessing 

impact of aerosols on regional and global climate, monitoring regional air quality, 

improving aerosol chemical transport models used in air quality forecast and climate 

models 

Aerodyne Research 

 Instruments for real-time and near real-time quantification of fine particulate matter 

necessary to understand climate impacts; developing instruments to quantify major 

inorganic components (SO4, NO3, CI, NH4); quantifying a general chemical 

characterization of organic fractions; development of less expensive, automated 

instruments for routine monitoring 

Arizona State University 

 Studies of the nature of aerosol particles such as airborne minerals, soot, and other 

small grains, their chemical and physical reactions (e.g., deliquescence, 

efflorescence) in the atmosphere, and their effects on air quality and climate change, 

using high-resolution transmission electron microscopy (HRTEM) 

Vision 

Chemical/dimensional metrology for aerosols will involve developing reliable methodologies for 

inorganic and organic trace analysis with emphasis on environmental applications, development of new 

types of analytical instrumentation for potential commercialization, and provision of certified reference 

materials to verify procedures for the determination of inorganic and organic contaminants in 

environmental samples. 

Chemical/dimensional metrology for climate is working towards predictions that are accurate and serve as 

a solid foundation for future climate efforts. A critical component of the vision is chemical analysis tools 

 

5 http://www.pnl.gov/atmospheric/programs/acci/ 6 http://www.esrl.noaa.gov/research/themes/aerosols/aerosols.html 7 http://www.wmo.int/pages/prog/arep/gaw/aerosol.html
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

6 

that provide enough certainty to reliably understand the impacts of climate change mitigation. These tools 

will increase the understanding of key issues, such as “good” aerosols (e.g., for cooling or geoengineering) or the link between gases and aerosols. The tools will allow insight beyond characterization 

of organic aerosols to understanding how aerosol particles change over time (e.g., hygroscopic changes). 

Changes can be effected in the models to reflect the newly acquired knowledge and produce predictions 

that approach field measurements. 

Ideally, environmental microscopy would encompass the analysis of particle size, shape, and composition 

at the atomic and molecular level. Distinctions between the properties of black carbon, brown carbon, 

char, soot, and other important particles would be readily ascertained. In situ aerosol/cloud interaction 

processes would be precisely and accurately measured. Information would be shared through a global 

aerosol microphysics network where particle characteristics could be measured online. 

Elements of the envisioned future for chemical/dimensional metrology are described in Table 2.3. 

Table 2.3. Chemical/Dimensional Metrology Vision Elements Votes 

Methods  Develop one instrument that characterizes integrated size, shape, composition of fine 

particles (e.g., mass mobility) in situ, in real time, and size resolved 



 Develop methods for differentiating between black carbon (BC), brown carbon, (BrC), 

char, and soot; identifying the start and end of the chemical continuum; differentiating 

between liquids and gas; reliably looking at BrC and separating it into possible 

components; ensuring BC properties and quantities are clearly defined and directly 

measured; and exploring other definitions beyond absorption in lower wavelengths 



 Measure aerosol/cloud interaction processes precisely and accurately in situ 

 Develop analytical techniques to characterize the chemical composition of aerosols at 

an atomic and molecular level 



 Develop statistical experiment design techniques to scale-up nm scale measurements 

to kilometer (km) scale properties 

Instruments  Support transmission electron microscopy (TEM) mass spectrometer instruments along 

with automated TEM stage for particle analyses 

 Develop global aerosol microphysics network (probes for chemical and optical 

properties) to enable inexpensive access to optical properties 

 Develop online measurement of particle shape 

 Support advances in environmental microscopy with atomic or near-atomic resolution to 

study chemical transformations on particle surfaces 

 Automate particle energy dispersive spectroscopy (EDS) measurement and sizing 

using high resolution microscopes 



 Measure smoke emission source strength and properties directly over wildfires using 

unmanned aircrafts and suitable small, accurate instrumentation 

 Develop metrology across the ultraviolet (UV)/visible spectrum of particle shapes, 

including biological-origin particle (e.g., plant scrapings, viruses, bacteria, and spores) 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

7

Table 2.3. Chemical/Dimensional Metrology Vision Elements Votes 

Standards & 

Protocols 

 Develop an absorbing carbon standard that is readily processed, robust, and 

transferrable 

 Support standard reference materials and methods for concentration composition 

(building on current NIST developments) 

 Create size standards across measurement methods such as optical, geometric, and 

operational 



 Establish well-defined basic global terminology/nomenclature and definitions for optimal 

communication in the scientific community 

 Develop a “chemical mass standard” instrument to generate aerosol chemical standard 

of specific mass/size 

 Establish standards for imaging soot structure inside a droplet 

 Establish fungal spore standards (bioaerosols) 

 Standardize methods to relate satellite aerosol optical measurements (e.g., aerosol 

optical depth [AOD]) to in situ measurement, such as mass, particulate matter (PM) 

2.5/10, or size distribution 



Data  Compare methods for aerosol, soil, sediment, and water measurement techniques 

 Understand the series of reactions leading up to formation of secondary organic 

aerosols (SOA), the chemical composition of SOAs, and the mechanisms for creation of 

new atmospheric particles (gas-to-particles conversion) 



 Establish better understanding of uptake via flux with “real” measurements and a 

detailed source inventory of composition and size resolved surface flux measurements 

of fine particle matter (speciated) network 



 Establish data to distinguish organic/carbonaceous components versus composition 

 Create accessible online data, such as the index of refraction 

Other 

Elements 

 Understand how the aerosol phase affects chemistry and the ability to measure 

(e.g., liquid, solid, amorphous) 

 Understand gas particle distribution 

 Develop a molecular-level understanding of nucleation from the gas phase (birth and 

growth of particle) 

 Enhance knowledge of particle oxidation, which occurs quickly, including the oxidation 

potential and concentration needed to oxidize 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

8 

Challenges and Barriers 

Aerosol metrology for climate faces numerous challenges. One overarching challenging is the difficulty 

of working in the Earth’s atmosphere. In complex, natural systems it is difficult to identify with certainty 

the key parameters that must be measured to evaluate climate impacts. For chemical/dimensional 

metrology in particular, attaining the vision for metrology described previously will require overcoming 

some significant challenges. Underlying problems exist, such as a lack of central information, basic 

global terminology and definitions, and instrumentation for generating aerosol chemical standards. 

Addressing these challenges will take resources, time, and skilled personnel. 

The infrastructure for addressing these challenges also needs improvement, particularly in the availability 

of consistently reported international trend and baseline data, global measurement networks, and ready 

access to instrumentation and test equipment. 

Table 2.4 lists the major challenges and barriers facing chemical/dimensional metrology for climate. 

Table 2.4. Chemical/Dimensional Metrology Challenges and Barriers Votes 

Instruments  No single “aerosols community” exists for communication and cross-disciplinary 

collaboration; a central source for instrument standards, validation, and comparison is 

lacking 



 Working in the atmosphere—large (25 billion cubic km), heterogeneous, and dynamic—is 

challenging and a huge sampling problem 

- Appropriate tools are lacking (fast response ground sensors, remote LIDAR, millions of 

cheap sensors) 

- Even with tools it is uncertain whether the questions on climate impacts can be 

answered 

- The key parameters to be measured in the atmosphere’s complex natural system are 

still uncertain 



 Some tools will require long-term research (e.g., seven years to actual field use) 

Data  Long-term trend and baseline data (high quality, climate-focused, often updated) with 

spatial and time components are lacking, particularly dynamic emission inventories for 

area sources 

 Global measurement networks and a global, standardized database of measurements do 

not exist 

Other 

Barriers 

 The need for investment in aerosols metrology is not well-understood; the result is a lack 

of strong drivers for research and development and sustained funding 



 Concerted effort to understand and address unintended consequences is lacking 

(e.g., consequences of removing controls on black carbon or other types of particles) 

 Complex, multi-disciplinary research may be required; the pipeline of trained personnel is 

not robust, and the skill sets are not easily assembled 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

9

Solutions and Approaches 

Participants selected four priority areas to address, which are summarized below. More detailed pathways 

to success for each area are provided in Figures 2.1 through 2.4 on the following pages. 

 Large-scale aerosol instrumentation calibration, validation and comparison (see 

Figure 2.1). Aerosol instrumentation requires calibration with dynamic aerosol standard 

sources. Such a standard source would produce an aerosol stream flow with controlled gas 

phase composition and known particle and droplet size and composition. An aerosol 

instrumentation calibration facility is needed to enable users to periodically calibrate 

individual instruments and to house instrument inter-comparison and cross-validation 

results. 

 Harmonized definitions and characteristics of black carbon, brown carbon, and soot for 

climate studies (see Figure 2.2). Multiple definitions of soot and black carbon preclude effective 

data inter-comparison of these species. A lack of standards precludes effective instrument 

calibration and data archiving; different methods will require standards with a wide range of 

properties. 

 Automated Transmission Electron Microscope for micro-physical properties of 

aerosols (see Figure 2.3). TEM automation will enable the measurement of the microphysical characteristics of aerosols. These measurements would provide fundamental 

information on statistically significant numbers of particles, data which is currently 

difficult or impossible to obtain. Instrumentation and software will need to be developed to 

enable automation. 

 Reconciliation of atmospheric (top-down) and ground-based (bottom-up) emissions 

data (see Figure 2.4). Reconciling top-down and bottom-up data is hampered by the lack 

of accurate emissions data, at the source and for vertical distributions, as well as the 

differences in spatial and temporal resolutions between ground and space in situ data. 

Reconciliation of this data would expand scientific understanding of the global carbon 

balance. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

10 Milestones

Figure 2.1. 

Chemical/Dimensional Metrology Priority Topic: 

Large-scale Aerosol Instrumentation Calibration, Validation, and 

Comparison

 

Measurement Challenge/Barrier

Aerosol instrumentation requires calibration with dynamic aerosol standard sources. Such a standard source would 

produce an aerosol stream flow with controlled gas phase composition and known particle and droplet size and 

composition. An aerosol instrumentation calibration facility is needed to enable users to periodically calibrate 

individual instruments and to house instrument inter-comparison and cross-validation results. 

Actions and Approach 

 Develop generation methods for aerosol particle flows 

of known particle size (1nm to 10,000 nm), chemical 

composition, and mass loading. 

 Control carrier gas composition, including relative 

humidity and trace gas composition. 

 Understand particle/droplet composition to include 

characteristic atmospheric aerosol components: 

sulfate, nitrate, chloride, ammonium, sea salt, and a 

wide range of organic species, soot, and major 

mineral dust. 

 Develop capabilities to produce crystalline and 

amorphous solid particles of known shape and 

morphology. 

 Develop capabilities to produce solid and liquid 

particles with known surface composition.

Performance Targets/Goals 

 An aerosol instrument calibration facility supporting 

the broad aerosol science community (government, 

academia, private sector labs, instruments development 

programs, and commercial instrument calibration 

needs). 

 A new generation of dynamic aerosols standard 

sources.

Applications 

Provide calibration services to: 

 a wide range of climate oriented R&D and trend 

monitoring activities 

 aerosol PM health impact and exposure studies 

 new generations of commercial aerosol composition 

instruments

Potential Stakeholders and Roles 

Government

Metrology laboratories: aerosol instrument 

calibration facility. 

Basic science, aerospace, environment and 

ocean: improved accuracy and precision for 

climate research. 

Environment/regulatory: improved 

speciated/size resolved measurements of 

ambient particulates affecting human health, 

and better calibration of instruments used to 

control health/human exposure studies. 

Industry Instrument companies: ability to calibrate 

new generations of aerosol measurement 

instrumentation. 

Impacts 

 Significantly improves data on atmospheric 

aerosol particulate matter composition and mass 

loading. 

 Enables ability to accurately inter-compare 

performance for a wide range of both research 

grade and routine monitoring instruments. 

 Contributes to U.S. and international agencies 

active in U.S. research programs.

2011-2012 2015 2020 

 Develop an initial white paper 

specifying phase I capabilities for 

aerosol calibration facility. 

 Develop specifications for initial 

range of dynamic calibration 

standard system.

 Create and staff facility, host 

instrument, inter-comparison/ 

calibration studies for several 

aerosol types. 

 Continue to refine and 

expand facility as needed. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

11

Milestones

Figure 2.2. 

Chemical/Dimensional Metrology Priority Topic: 

Harmonized Definitions and Characteristics of Black Carbon, Brown 

Carbon, and Soot for Climate Studies 

Measurement Challenge/Barrier

Multiple definitions of soot and black carbon preclude effective data inter-comparison of these species. A lack of 

standards precludes effective instrument calibration and data archiving; different methods will require standards 

with a wide range of properties.

Actions and Approach 

 Set up a committee similar to the international Union 

of Pure and Applied Chemistry (IUPAC) to define 

carbon-based particulate matter terms for standards; 

focus on black and brown carbon and soot; consider 

other species. 

 Develop standard dispersion methods for the relevant 

aerosols. 

 Develop a synthetic approach to make reproducible 

materials. 

 Coordinate across professional communities. 

 Assemble a panel to assess needs for standards: who 

should develop materials, compositions, and 

techniques. 

 Establish test capability for instrumentation 

calibration/inter-comparison for species of interest.

Performance Targets/Goals 

 A suite of particle standards to address a range of user 

goals. 

 Goals for standards: 

- Stable, transferable, usable 

- Known size, shelf-life, surface composition and charge

- Optical properties (extinction, scattering, albedo, 

index) for organic carbon (OC) and elemental carbon 

(EC)

Applications 

 Instrument calibration for black and brown carbon 

and soot 

 Reduction of uncertainties for these species 

 Instrument comparisons

Potential Stakeholders and Roles 

Government Metrology laboratories:

standards and reference materials. 

Research Groups Science organizations: Aerosol 

and black carbon-geosphere 

(soils, sediments) communities to 

conduct research. 

Industry Instrument manufacturers: test 

instruments and provide data. 

Impacts 

 Grows scientific knowledge by reducing 

uncertainties in measurements. 

 Increases confidence in climate change models. 

 Provides consistent standards for studying 

particulate species that are currently poorlycharacterized.

2011-2012 2015 2020 

Assemble committee on 

standards 

 Establish specific 

requirements for standards

Prepare and characterize standards 

 Establish test capability to calibrate instruments 

for these species

 Continue to refine and expand 

capability. 

Support inter-comparisons 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

12 Milestones

Figure 2.3.

Chemical/Dimensional Metrology Priority Topic: 

Automated Transmission Electron Microscope for Micro-physical 

Properties of Aerosols 

 

Measurement Challenge/Barrier

TEM automation will enable the measurement of the micro-physical characteristics of aerosols. These 

measurements would provide fundamental information on statistically significant numbers of particles, data which is 

currently difficult or impossible to obtain. Instrumentation and software will need to be developed to enable 

automation. 

Actions and Approach 

 Develop capability for 3-D stage (xyz) manipulation 

on the TEM; the stage must be automated for 

detection and measurement to be accomplished. 

 Collect energy dispersive X-ray spectroscopy 

(EDX) X-rays and diffraction data on individual 

particles. 

 Collect digital images and develop data storage 

capabilities. 

 Develop hierarchy for categorization of 

measurements.

Performance Targets/Goals 

 Automated TEM xyz stage and automated 3D imaging 

capabilities. 

 Organized hierarchy of measurements in standardized 

categories. 

 A particle property inventory that is readily accessible.

Applications

 Aerosol studies (climate, health, and safety) 

 Emissions source apportionment 

 Compliance testing for emissions quantification and 

verification 

Potential Stakeholders and Roles 

Government

All stakeholder groups 

interested in atmospheric 

aerosols and climate models 

National Laboratories

Academia

Research Groups 

Impacts 

 Promotes health and safety through better 

characterization of aerosols. 

 Provides fundamental information about the 

characteristics of statistically significant numbers 

of particles in a time-efficient manner. 

 Supports protection of environment and climate.

2011-2012 2015 2020 

Develop automated xyz stage Develop automated 3-D imaging Organize and bin measurements into sets 

of standard categories (i.e., shape, 

chemistry, other factors) 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

13

Milestones

Figure 2.4. 

Chemical/Dimensional Metrology Priority Topic: 

Reconciliation of Atmospheric (top-down) and Ground-based 

(bottom-up) Emissions Data 

 

Measurement Challenge/Barrier

Reconciling top-down and bottom-up data is hampered by the lack of accurate emissions data, at the source and for 

vertical distributions, as well as the differences in spatial and temporal resolutions between ground and space in situ

data. Reconciliation of this data would expand scientific understanding of the global carbon balance.

Actions and Approach 

 Explore pathways to ensure diverse agency 

representation for integration at the scientific level. 

 Pursue application of standard measurements for 

compatibility and comparability across various 

inventories and data uses. 

 Establish a prioritized work plan for harmonization of 

data. 

 Integrate efforts with the Intergovernmental Panel on 

Climate Change (IPCC) to assure scientific coherence 

and accountability.

Performance Targets/Goals 

 Scientific advancement in understanding of the global 

carbon balance. 

 Standardization in measurements and adaptation to 

different communities. 

 Reconciliation of top-down/bottom-up in situ data. 

 Integration of science and data with policies and 

stakeholders.

Applications 

 Regulations 

 Emission controls 

 Energy efficiency 

 Renewable energy 

 Forecasting emissions profiles 

 Education and public outreach 

 Economic planning Potential Stakeholders and Roles 

Government 

 Metrology laboratories: Definitions, terminology, standardization, 

instrumentation, calibration, accuracies. 

 Environmental/regulatory: Atmospheric—spatial coverage, link 

between space and time, aircraft and satellite instruments, vertical 

profiles, fluxes, transport. Ground-based—continuous localized 

emissions temporally resolved; emissions inventories, forecasting, 

regulatory issues. 

 Aerospace: Space- and air-borne measurements; close data gap; 

global climate modeling 

 Energy: Energy use and emissions estimates and impacts and 

projections; policies. 

 Forestry and agriculture: Land-use changes, biomass burning, 

fuels, seasonality. 

International 

 IPCC: Robust scientific reference frame 

Industry 

 Translating knowledge to technology 

Impacts 

 Supports protection of environment and 

understanding of climate change. 

 Grows scientific knowledge of climate impacts. 

 Promotes health and safety via better science. 

 Accelerates competiveness through more 

accurate baselines for industrial emissions.

 

2011-2012 2015 2020 2025+ 

 Standardize and develop 

methods 

 Organize stakeholder 

committee 

 Asses current metrology 

understanding/standards 

 Identify short- and long-term 

goals 

 Coordinate measurements from 

ground/in situ/space, and 

modeling 

 Compare-understand-evaluatevalidate-standardize-establish 

integration approaches for 

consistency

 Fine-tune harmonized measurement 

techniques and integration 

Compare measurements and constrain 

models 

Reevaluate knowledge gaps and model 

requirements 

 Reiterate processes, validate models, 

reevaluate standards

Extend standardized 

measurements globally 

 Stabilize all processes 

Develop climatologies and trends 

 Inform stakeholders and public of 

findings 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

14 

Photo courtesy of NASA, New Zealand GeoNet. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

15

3. Optical Properties 

Aerosols in the atmosphere are measured usually either by mass concentration or by optical schemes8

. 

Atmospheric aerosols show large variations in their optical properties based on a number of factors 

including size, chemical makeup, shape, and other characteristics. These variations, combined with an 

incomplete understanding of how aerosols evolve in the atmosphere, create significant uncertainties in 

how global aerosol loading effects climate change. To address these shortcomings, existing optical 

capabilities will need to be augmented and new optical measurement methods and technologies will need 

to be developed and exploited. 

Aerosols possess important optical properties such as scattering and absorption, which dictate their 

interaction with incoming radiation from the sun. Understanding these aerosol optical properties is 

essential to a full understanding of radiative effects of emissions and aerosol forcing. The important 

aerosol optical properties needed to calculate radiative influences include aerosol scattering coefficient, 

absorption coefficient, and asymmetry parameter, as well as phase function and polarization. Size is also a 

very important single-particle optical property to measure, where size can refer to a number of quantities, 

including wet size, dry size, size at formation, and size at a specified formation. The uncertainties in 

measuring these individual input parameters results in a substantial overall uncertainty in the context of 

forcing over a time period.9

State of the Art 

Currently, most information to measure quantities (e.g., extinction, scattering, or absorption), comes from 

measurements of mass.10 Optic properties are then inferred from in situ laboratory measurement results or 

field studies. These measurements currently result in uncertainties of 1% to 10% for extinction, 3% to 

10% for scattering, and 5% to 50% for absorption. Methods to measure aerosol extinction include cavity 

ring-down spectroscopy, extinction cells, or cavity attenuated phase shift spectroscopy techniques. 

Scattering is measured through nephelometers or integrating spheres, while absorption can be measured 

using filter-based or photo-acoustic spectroscopy. 

Aerosol optical depth (AOD) is another important optical property, which is one of several properties 

(including the light scattering coefficient) measured by the Global Atmosphere Watch (GAW) aerosol 

program. GAW aims “to determine the spatio-temporal distribution of aerosol properties related to 

climate forcing and air quality up to multidecadal time scales.” Since GAW measurements are made at 

surface-based stations, global climatologies (series of charts indicating the long-term average of 

atmospheric and oceanic conditions) are difficult without satellite measurements. However, 

correspondence with satellite measurements requires understanding of the column and precision AOD 

measurements. Furthermore, AOD measurements are difficult to understand without the aerosol profile. 

More detailed information on the vertical aerosol distribution is measured by the GAW Atmospheric 

LIDAR (Light Detection and Ranging) Observation Network (GALION), which uses advanced laser 

remote sensing in a network of ground-based stations.11 Multiple aerosol properties can be derived from 

light detection and ranging (LIDAR) measurements, including backscatter coefficient, extinction 

coefficient, and optical depth. These and other properties are determined through the use of multiple types 

of LIDAR, including elastic LIDAR, (multi wavelength) Raman LIDAR, high spectral resolution LIDAR 

 

8

 http://downloads.climatescience.gov/sap/sap2-3/sap2-3-final-report-all.pdf 9

 Stephen E. Schwartz, Variation of Aerosol Optical Properties and Radiative Implications, Aerosol Metrology for Climate 

Workshop, March 14-15, 2011. 

10 Dan Lack, Measurement Needs and Challenges for Absorbing Aerosol, Aerosol Metrology for Climate Workshop, March 14-

15, 2011.

11 http://www.wmo.int/pages/prog/arep/gaw/aerosol.html  
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

16 

(HSRL) and the state-of-the-art LIDAR systems that measure multiple quantities simultaneously. 

GALION, however, still leaves researchers with multiple unanswered questions. There is uncertainty in 

the precision of the GALION-measured extinction profiles. It is unclear if extinction climatology can be 

derived and made into a climate record. In addition, it is also unclear how to validate the retrieved 

microphysical values of real index of refraction (nr), imaginary index of refraction (ni), droplet 

concentration with a given radii.12 

There are several areas of research and technology development that could aid in the measurement of 

optical properties. This research includes source and detector characterization, calibration on polarimetry 

channels, validation of the inverse methods in LIDAR and the calibrations for fixed magnitude starobserving experiments. In addition, new technology development is needed, including new sources, 

detectors, filters, and notch filters. In general, instrumentation needs to become smaller and less expensive 

to allow for the use of a wide range of instruments spaced geographically and temporally, which cannot 

be achieved with current expensive instrumentation. 

Vision 

A number of advances in measurement techniques, instruments, and standards are needed in order to 

allow for more useful and advanced measurements of optical properties that include absorption, 

scattering, asymmetry, index of refraction, extinction, and polarization. In the area of measurement 

techniques, the continued development of multiple measurement capabilities is expected to lead to great 

advances in the aerosols field. These capabilities include measurements of vertical distributions of optical 

properties, UV to far-IR spectral measurements, real-time morphology, consistent size measurements 

using different techniques (e.g., optical or mobility techniques), and miniaturized and well-characterized 

aerosol measurement techniques that will allow for routine measurements utilizing transport means such 

as balloon-borne sounding system (sondes). In the area of standards, the community envisions an aerosol 

calibration facility for both optical and morphological measurements in addition to absorbing aerosol 

standards. In terms of instruments, it is envisioned that smaller, miniaturized instrumentation will lead to 

routine measurements of aerosol vertical distributions, extinction, scattering, and other important optical 

properties. In addition, optical means of determining particle shape and morphology and the development 

of a multi-wavelength, high spectral resolution LIDAR for the measurement of aerosol vertical 

distributions are also important aspects envisioned. 

 

12 Raymond Hoff, Optical Properties: The Global Atmosphere Watch (GAW) Aerosol LIDAR Observation Network (GALION): 

Issues Involved with Obtaining Precise Optical Extinction Profiles for Climate Records, Aerosol Metrology for Climate 

Workshop, March 14-15, 2011. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

17

Elements of the envisioned future for optical properties are described in Table 3.1. 

Table 3.1. Optical Properties Vision Elements 

Methods  Achieve consistent size measurements using multiple measurement techniques (e.g., optical 

techniques, mobility techniques, etc.) (five years) 

- Measurements of diameter depends on community measurements—geometric diameter versus 

mobility diameter versus aerodynamic diameter 

 Augment collaboration of theorists and experimentalists to arrive at a more complete understanding of 

climate change (five years) 

- AEROCOM-project13 model of collaboration (AEROCOM – aerosol comparisons between 

observations and models)

 Improve understanding of whether micro-physics and nanoscale properties translates to macroscopic 

predictability of forcing (a macroscopic property) (10 years) 

Instruments  Develop multi-wavelength, high spectral resolution LIDAR for measurement of aerosol vertical 

distribution (five years) 

 Establish a method for relating light absorption by filter deposit to in-situ absorption (five years) 

 Develop inexpensive, well characterized, accurate, and precise absorption instruments 

- Global surface monitoring or vertical profiling (five years) 

 Develop optical determination of particle shape/morphology (five years) 

 Create portable, automated aerosol measurement units (10 years) 

- Solar-powered, self-contained, for optical total mass measurements 

 Develop routine measurement of aerosol vertical distribution (particle sensors, balloon sounding 

systems) (15 years) 

- Smaller, miniaturized instrumentation, potentially disposable, measure extinction, scattering 

(e.g., place on weather balloon platforms, sample twice daily across the world) 

 Measure asymmetry parameter, the fraction of light sent into the forward hemisphere. 

- Enable radiative forcing calculations 

Standards/ 

Protocols

 Understand spectral consistency from UV to far-IR (five years) 

 Establish mono-disperse, absorbing, calibrated refractive index (across multiple wavelengths), aerosol 

standards (five years) 

 Establish aerosol calibration facility (optical and morphological) (five years) 

- Generate and characterize sizes, types, shapes of aerosols 

 Calibrate particle density and devices, e.g., “standardized soot” and other shapes (five years) 

- Measured in individual laboratories 

- For equipment-makers: equipment is only as precise as means of calibration—better standards are 

needed 

- Incorporate both particle and gas perspectives 

 

13 See http://dataipsl.ipsl.jussieu.fr/AEROCOM/ 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

18 

Table 3.1. Optical Properties Vision Elements 

 Develop standards for calibrating non-filter methods (five years) 

- Extinction, scattering, absorption using gases and standard particles 

 Establish a sensitivity study (five years) for key optical properties 

 Formulate the ability to calibrate and measure large particles (five years) 

- Largely ignored, typically for particle diameters > 5 μm 

 Optimize and validate particle counting methods (10 years) 

Data  Establish spectral characterization of aerosol absorption (wavelength: 0.3 μm to 5 μm) by type 

(smoke, pollution, etc) (five years) 

- Expand to regional United States (10 years) 

- Expand to global (15 years) 

 Develop inter-comparison of calculations/theory/modeling for scattering and absorption of mixed 

particles, non-spherical particles with measurements; theory should match measurements (five years) 

Important 

Properties to 

Measure 

 Measure absorption coefficient, scattering coefficient, asymmetry parameter, and index of refraction 

 Address additional forcing needs: 

- Altitude-dependent optical properties 

- Extinction coefficients 

- Wavelength-dependent optical properties 

 Understand polarization: full Mueller matrix 

 Establish reference standards for shortwave absorption by carbonaceous aerosol 

 Predict optical properties such as phase-function 

 Validate optical properties with laboratory results 

 Measure classes of particles morphologically; correlate morphological properties with optical properties 

Challenges and Barriers 

There are many technical challenges that must be addressed to improve the gathering of quantitative 

information from optical interrogation methods on aerosol particles; these advances should provide 

significantly more information about the physical and chemical properties of aerosol particles. Among the 

challenges, one of the most critical areas is the lack of a strong correlation between measurement data and 

simulation models—i.e., making models look realistic. Furthermore, optical aerosol measurement 

equipment has not followed the miniaturization and cost reduction pathways that have been observed by a 

number of other industries, such as mobile phones and health diagnostics. Other challenges include the 

lack of conversion relationships for different aerosol-type definitions, lack of simplified systems to 

calibrate instruments used to measure optical properties derived of aerosols, an inability to quantify the 

morphology of unique particles in analogy to the fractal aggregate concept, and an insufficient number of 

technically trained personnel/staff. An overview of the challenges identified for optical properties is given 

in Table 3.2. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

19

Table 3.2. Optical Properties Challenges and Barriers Votes 

Instruments  Instruments lack the miniaturization of devices such as cell phones. 

- Development of “lab-on-chip” for aerosol metrology, i.e., instruments on chip 



 Equipment is expensive; basic cost reductions are needed 

Standards/ 

Protocols 

 A strong linkage has not been established between measurements and simulations 

(e.g., definitions) 

 Conversion relationships are lacking for different definitions of the same properties. 

- Standardized terms and procedures in the form of a glossary are needed 



 Standardized terminology is not available in Network Common Data Form 

(NetCDF) and Hierarchical Data Format (HDF); e.g., a term like “diameter” does 

not have a standard definition and often needs an additional qualifier 



Data  Tools for measurements of mixed carbonaceous aerosols are lacking, including 

spatial coverage, evolution of coatings, and optical properties 

 Quantitatively describing the features of unique aggregates is difficult or not 

possible 



Infrastructure  A standardized air calibration facility is not available 

 An optical calibration facility (e.g., filters, sources, detectors) does not exist 

- Increased access and broad awareness of facility capabilities should be 

provided 

- Facility needs to be self-supporting based on demand 



Other  There is no clear national vision about the impacts of climate change 

 A shortfall of technologically-trained personnel is anticipated by 2015; more 

education is needed 



Solutions and Approaches 

Participants selected seven priority areas to address, which are summarized below. More detailed 

pathways to success for each area are provided in Figures 3-1 through 3-6 on the following pages. 

 Morphology Quantification for Unique Particles (see Figure 3.1). The ability to quantify 

the morphology of unique particles and compare particle morphology is a fundamental 

need for all types of aerosol measurement. Some difficult types of particles requiring 

quantification include: fractals, non-spherical shapes, mixed particles, and particle 

combinations. This capability will allow a quantitative correlation of physical properties to 

morphological properties. Quantitative particle descriptions would help to standardize 

aerosol science and allow easy comparison of collected data. 

 Standardization of Data Formats (see Figure 3.2). Currently, there is inadequate 

standardization of terminology in databases using Network Common Data Form (NetCDF) 

and Hierarchical Data Format (HDF) NetCDF. In order to address this barrier, data naming 

conventions of the aerosol science community needs to be coordinated with the climate and 

forecast (CF) metadata. NIST in particular could take the lead in this coordination. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

20 

Additional coordination is needed with the Hierarchical Data Format (HDF5) community. 

Modelers, in particular, will use the NetCDF data inputs. 

 Education and Training for Aerosol Measurement (see Figure 3.3). There is a current 

need for more technical-trained personnel/staff in the area of aerosol measurement, optical 

methods or otherwise. Opportunities for increasing the number of aerosol scientists include 

implementing training programs on aerosol technology or encouraging scientists in a 

variety of other fields to concentrate on the issues in aerosol science. Increasing the 

number of investigators and integrating researchers from other disciplines would augment 

how data is collected and analyzed. 

 Affordable, Portable, Smaller-scale Instrumentation for Measuring Optical 

Properties (see Figure 3.4). Reducing the size and cost of optical properties measurement 

instrumentation is needed to allow for its pervasive use across a number of existing 

platforms (commercial aircraft, ships, etc.). While various technologies have pursued 

aggressive miniaturization and cost reduction strategies—e.g., microchips, optical aerosol 

measurement equipment has not adhered to this type of progression. Instrumentation 

miniaturization will enable unobtrusive collection of significantly more data. 

 Effective Linkage between Measurements and Simulations (see Figure 3.5). Increased 

communication and linkages between modelers and experimentalists is needed in order to 

create more precise models that better simulate real world conditions. These more precise 

models would ultimately enable forecasting climate forcing and other more complex 

climate processes. This increased communication should allow for basic parameters for 

models mapped out by experimentalists, as well as the co-validation of model parameters 

that can be measured in laboratories. 

 Standards and Methods for Calibration of Aerosol Photometers (see Figure 3.6).

Standards and methods for the calibration of aerosol photometers are needed in order to 

develop a simple system to calibrate instruments used to measure optical properties derived 

of aerosols. These properties can include absorption, scattering, or extinction as derived 

from morphology and indices. The end result can be a laboratory capability of producing 

well-characterized aerosols for the evaluation, validation, and performance calibration of 

sensing technologies.
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

21

Milestones

Figure 3.1. 

Optical Properties Priority Topic: 

Morphology Quantification for Unique Particles

 

Measurement Challenge/Barrier

The ability to quantify the morphology of unique particles and compare particle morphology is a fundamental need 

for all types of aerosol measurement. Particles requiring quantification that pose significant challenges include: 

fractals, non-spherical shapes, mixed particles, and particle combinations. Quantitative particle descriptions would 

allow correlation of physical and morphological properties and help to standardize aerosol science. 

Actions and Approach 

 Identify and begin to characterize unusual particle 

morphologies: fractals, non-spherical shapes, mixed 

particles, and combinations of these (e.g., fractals 

composed of non-spherical primary particles). 

 Validate/develop conversion relationships between 

aerosol diameters from varied instruments. 

 Quantify fractal, non-spherical, mixed state, and 

hybrid combinations. 

 Explore quantities needed for different applications. 

– Fractal aggregates have fractal dimension, but 

recently it has been shown this is not sufficient for 

a full description; relevance of quantities will vary 

for various applications (e.g., scattering, 

absorption of light, mobility, etc.)

Performance Targets/Goals 

 Useful, relevant quantitative descriptors for any particle 

morphology.

 Ability to compare any particle morphology to another 

quantitatively. 

 Ability to correlate other physical properties to 

morphological properties, quantitatively.

 Unification of overall particle geometry, convexity.

Applications 

 Quantitative particle morphology for aerosols 

 Correlation of physical properties with morphology 

for a variety of particles 

 Standardization of particle size definition and 

morphology

Potential Stakeholders and Roles 

Government 

International 

Standards Organizations 

National Laboratories 

Industry 

Private Research Groups 

Trade Groups 

Academia 

All stakeholders need 

quantitative descriptive 

abilities 

Impacts 

 Supports protection of environment and climate 

via expansion of scientific knowledge on unusual 

particles. 

 Establishes broad systemic quantification 

capability for particle morphology.

2011-2012 2015 2020 

 Identify candidate particles and 

morphologies for characterization 

 Begin to quantify morphologies

 Complete development of known 

morphologies 

 Develop methods for physicalmorphology correlations

 Identify new particles for 

characterization and continue to 

quantify 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

22 Milestones

Figure 3.2. 

Optical Properties Priority Topic: 

Standardization of Data Formats

 

Measurement Challenge/Barrier

Currently, there is inadequate standardization of terminology in databases using Network Common Data Form (NetCDF) 

and Hierarchical Data Format (HDF) NetCDF. To address this barrier, data-naming conventions of the aerosol science 

community need to be coordinated with climate and forecast metadata. In addition, strengthened conversion relationships 

for different aerosol and atmospheric science terms to enable a common vocabulary for physical properties. 

Actions and Approach 

 Develop multi-organization plan for coordinating the 

data naming conventions of aerosol science 

community with climate and forecast metadata. 

(http://cf-pcmdi.llnl.gov/governance) 

 Convene researchers (theorists, experimentalists, and 

field) to agree on common usage of terms for 

conversion relationships. 

 Coordinate with the HDF5, a well-known data model, 

library, and file format for storing and managing 

data. www.hdfgroup.org/HDF5

 Finalize conventions and gain consensus from 

diverse stakeholders and users.

Performance Targets/Goals 

 Standardized naming conventions that will enable 

common usage of data. 

 Interoperability with common data formats already in 

use by climate and forecasting groups.

Applications 

 Modelers using NetCDF inputs 

 Scientific studies on aerosols

Potential Stakeholders and Roles 

Government Aerospace, environment and ocean, 

energy, science, metrology 

laboratories: coordination and 

consensus on data-naming 

conventions

Academia University Corporation for 

Atmospheric Research (UCAR)

Impacts 

 Enables wider, more consistent and reliable use 

of data (less uncertainty of results as definitions 

are clear). 

 Agreed-upon conventions that could be used 

globally in large databases. 

 Better and more consistent inputs to climate 

models leading to more comparable model 

outputs.

2011-2012 2015 2020 

 Identify lead organization for 

reviewing and developing naming 

conventions 

 Complete data terminology 

activities; results vetted with user 

community 

 Common data terminology usage in 

large databases 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

23

Milestones

Figure 3.3. 

Optical Properties Priority Topic: 

Education and Training for Aerosol Measurement

 

Measurement Challenge/Barrier

There is a current need for more technically trained personnel in aerosol measurement, optical methods, and other 

areas. Increasing the number of investigators and integrating researchers from other disciplines would augment 

how effectively aerosols data is collected and analyzed.

Actions and Approach 

 Motivate the transfer of the existing knowledge pool 

to other disciplines (e.g., a material science/chemical 

engineer could move to the aerosol science 

technology development area). 

 Implement a training program on aerosol technology 

and operation of calibration facilities and equipment.

Performance Targets/Goals 

 Increase/keep constant the number of R&D personnel 

in aerosol science. 

 Established curricula in universities, and increased 

awareness of the need for scientists trained in the 

field. 

 Established technical training programs.

Applications 

 Workforce in aerosol science 

 Aerosols research community 

 Quantification and verification of greenhouse gas 

emissions

Potential Stakeholders and Roles 

National 

Laboratories 

Training programs, post-doctoral 

research 

Academia Curricula for undergraduate and 

graduate studies; programs in 

aerosol science 

Industry Training programs for 

instrumentation and calibration 

Impacts 

 Contributes to economy and jobs by providing 

high-skilled positions in aerosols science. 

 Ensures continuing trained workforce for 

quantification of climate-related compounds. 

 Supports continued research and scientific 

understanding of aerosols and impact on climate.

2011-2012 2015 2020 

 Initiate development of curricula 

and training programs 

 Conduct industry-governmentacademia education/training

 Continue implementation of 

training and education programs 

Continue implementation of training 

and education programs 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

24 Milestones

Figure 3.4. 

Optical Properties Priority Topic: 

Affordable, Portable, Smaller-Scale Instrumentation for 

Measuring Optical Properties 

Measurement Challenge/Barrier

Reducing the size and cost of optical properties measurement instrumentation is needed to allow for its pervasive 

use across a number of existing platforms (commercial aircraft, ships, etc.). While various technologies have 

pursued aggressive miniaturization and cost reduction strategies (e.g., microchips), optical aerosol measurement 

equipment has not followed this progression. 

Actions and Approach 

 Design systems to maintain performance and cost 

requirements. 

 Identify opportunities for applications 

(e.g., transportation carriers) and possible 

demonstrations. 

 Minimize instrument electric power consumption 

(battery operated). 

 Ensure non-intrusive nature of instrumentation 

products (low noise, minimized heat dissipation, 

small size).

Performance Targets/Goals 

 Adequate tradeoff between cost and performance. 

 Includes the following attributes: reduced size, rock 

mount, portable, balloon launch, radio-sonde 

capability. 

 Utilization of platforms of opportunity (commercial 

aircraft, ships, etc.).

Applications 

 Ambient air quality and exposure studies 

 Long-term climate studies 

 Occupational health and safety monitoring 

 Commercial and medical applications

Potential Stakeholders and Roles 

Government Regulatory 

National Laboratories Standards and verification 

Industry Customers 

Small Business Innovations in instruments 

Impacts 

 Supports protection of environment and climate 

and promotes health and safety via greater access 

to key data on aerosols. 

 Accelerates competiveness via new 

instrumentation and potential for export. 

 Contributes to economy and jobs through new 

instruments and small business start-ups. 

2011-2012 2013 2015 2018 2020 2025+ 

Create 

blueprint for 

instrument 

development 

Apply 

resources 

Conduct 

demonstrations 

and prototyping 

Seek and gain 

agreements 

with platform 

providers 

Achieve 

commercial 

production 

Evaluation of 

technology and 

impacts on 

data, baselines 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

25

Milestones

Figure 3.5. 

Optical Properties Priority Topic: 

Effective Linkage Between Measurements and Simulations

 

Measurement Challenge/Barrier

Increased communication and linkages between modelers and experimentalists is needed to create more precise 

models that better simulate real world conditions. This increased communication should allow basic parameters 

for models to be mapped out by experimentalists, as well as co-validation of model parameters that can be 

measured in laboratories. 

Actions and Approach 

 Ensure measurement providers have enough 

measurements and the right data for modelers; 

explore gaps and challenges. 

 Map out basic parameters needed for models and 

correlate with experimentalists. 

 Co-validate what modelers use with what can 

actually be measured in laboratories. 

Performance Targets/Goals 

 Creation of an optical data perspective that is 

globally applicable for climate studies, including 

identification of the optical properties that are most 

important. 

 Increased collaboration between modelers and 

experimentalists. 

Applications

 Forecast of climate forcing 

 Modeling of greenhouse gas emissions 

 

Potential Stakeholders and Roles 

International AEROCOM-project 

(international science initiative 

on aerosols and climate) 

National Laboratories Data and parameters for models 

Private Research 

Groups/Associations 

American Association of 

Aerosols Research (AAAR), 

American Geophysical Union 

(AGU) 

Impacts 

 Supports protection of environment and climate 

and promotes health and safety via more 

accurate models and simulations. 

 Greater consistency between experiment and 

simulation.

2011-2012 2015 2020 

 Increase people and information 

exchange between AEROCOM, 

AAAR, and AGU 

 Identify basic parameters

 Co-validate data from experiments 

with model outputs 

•Add new models and 

experiments
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

26 Milestones

Figure 3.6. 

Optical Properties Priority Topic: 

Standards/Methods for Calibration of Aerosol Photometers 

 

Measurement Challenge/Barrier

Standards and methods are needed to develop a simple system to calibrate instruments used to measure optical 

properties of aerosols. These properties can include absorption, scattering, or extinction coefficients as derived 

from morphology and indices.

Actions and Approach 

Generate particles of interest: 

 Particles: poly-styrene, gold, suspended silicon, soot, 

carbonized spheres 

 Aerosolization: nebulizer, electrospray 

 Spectrum: dyes, plasmatic structure 

 Scattering: size and morphology 

Conduct characterization studies of particles: 

 Standard imaging technology particle counters 

 Cavity ring down spectroscopy (CRDS) 

 UV-visible spectroscopy 

 Bulk material characterization 

 Imaging Mie theory 

 Aerosol types (i.e., glass bead, Arizona dust, Savannah 

smoke) tor instrument calibration 

Performance Targets/Goals 

 A laboratory capability of producing characterized 

aerosols for validity/evaluation and calibrating 

performance of sensing technologies. 

Applications 

 Calibration of field instruments 

 Technology evaluation 

 Re-evaluation of historical data-sets 

 Reference data for particle classes

Potential Stakeholders and Roles 

Government Regulators 

Industry Instrument vendors 

Academia Atmospheric scientists 

Impacts 

 Supports protection of environment and climate and 

promotes health and safety via greater 

understanding of the science of aerosols. 

 Provides simpler, more cost-effective, and 

standardized measurement of optical properties to 

provide consistency across studies and enable 

greater number of measurements.

2011-2012 2015 2020 

Generate particles of many types 

 Initiate characterization studies

Functional laboratory available to 

calibrate and test equipment 

 Continued refinement and 

improvement as needed
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

27

4. Modeling 

Models of climate processes provide tools to quantitatively describe interactions between the atmosphere, 

land, and oceans. Models can range from simple estimations to complex simulations of various processes. 

Two critical components of models are the mathematical equations and input data, both which depend on 

accuracy to achieve realistic simulations. Models can be created to investigate a specific question, such as 

SOA and cloud interaction. Modeling depends on outputs from Optical Properties and 

Chemical/Dimensional Metrology for both data inputs to the models and model validation via field 

measurements. 

State of the Art 

Modeling of aerosols usually falls into the more general category of climate models. These models use 

various methodologies, such as box models and radiative-convective models, to accurately model climate 

processes across all scales. Some general climate models currently in use include the National 

Aeronautics and Space Administration (NASA)/Goddard Institute for Space Studies (GISS) General 

Circulation Model (GCM), NOAA/Geophysical Fluid Dynamics Laboratory CM2 global climate mode, 

and NCAR/UCAR Community Climate System Model (CCSM), NCAR Whole Atmosphere Community 

Climate Model (WACCM). A recent report on aerosols and climate science from the U.S. Climate 

Change Science Program contains a good overview of measurement issues and the climate models 

currently in use.14

Aerosol interactions can be simulated with stand alone models or as components of larger scale climate 

models. Recent research at Pacific Northwest National Laboratory resulted in a cloud-resolving model 

embedded within each grid cell to account for small features such as aerosols. Aerosol effects on clouds, 

and vice versa, can be simulated using cloud and aerosol properties statistics from the reference material. 

Small features, such as aerosols, clouds, and pollution point sources, can greatly impact global climate. 

Improved modeling and understanding of these small features will improve predictions of climate change. 

Vision 

Participants identified a wide range of needs and visions for the future (see Table 4.1). Goals specifically 

applicable to measurement include: 

 Expanded database of chemical physical properties of organics including refractive indices, 

solute activity co-efficient and water activity, and mass absorption co-efficient. 

 Improved source emission characterization including, size distribution, standardization of black 

carbon measurements, particle morphology, and characterization of ambient aerosols and 

elemental carbon for modeling. 

 Achieving better than 1% absolute radiometric calibration for on-orbit imagers. 

 A global database of aerosol size distribution, shape, and mixing state for black carbon, 

elemental carbon, and organic carbon (including near source and ambient measurements). 

 Achieving aerosol standards for climate change solutions by developing a suite of updated and 

relevant reference materials. 

 

14 http://www.climatescience.gov/Library/sap/sap2-3/final-report/default.htm
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

28 

Table 4.1. Modeling Vision Elements 

Methods  Accurately quantify BC in snow/ice measurement techniques 

 Achieve greater than 1% absolute radiometric calibration for space-based spectroradiometerology/VIS (visible light at 400-700 nm)/IR (750 nm – 1 mm) imagers 

 Develop sensitivity analysis of aerosol characteristics that can make radio frequency (RF) of BC go 

from positive to negative 

 Quantify brown carbon mass absorption cross-sections 

 Understand the role of black carbon as ice nuclei 

 Develop secondary organic aerosols production theory 

- Volatility basis 

- Smog chamber studies 

 Develop high throughput particle analysis in three dimensions 

Standards 

and Protocols 

 Understand parametric uncertainty (constraining measurements, standardized tests) 

 Develop reference materials for organic carbon/elemental carbon sampling and analysis 

 Understand inter-comparisons for theoretical simulations 

Data and 

Instruments 

 Develop validated and transparent database for modeling 

 Establish global database of aerosol size distribution, shape and mixing state (chemistry), including 

surface and aircraft 

 Understand extent of variation in single scattering albedo as a function of the internal mixing state of 

aerosol type and spatial distribution of mixing phases 

 Measure spectral refractive indices of many individual organic chemicals (particularly UV/short visible) 

 Create in-situ networks for validation of satellite observations and models 

 Understand precision/source-based emission factors 

 Measure particle size, shape, and mixing state for a range of important aerosol sources—both near 

source and within a typical model grid space (e.g., 1 degree longitude x 1 degree latitude x 100 

meters) 

 Establish a database of morphology (particle shape effect) 

 Use models for predictions—measure Henry’s constants, activity coefficients of the many thousands 

of organic chemicals used in chemistry mechanisms 

Reference 

Material 

 Attain calibrated celestial sources for nighttime atmospheric data 

 Validate light detection and ranging (LIDAR) with in situ data 

Other  Measure size-resolved particle albedo in real time 

 Robustly assess the impact of human activities (sector by sector, activity by activity) on the 

atmosphere, climate, and the environment 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

29

Challenges and Barriers 

The challenges outlined in Table 4.2 were identified as those most impeding progress toward the goals 

identified for modeling of aerosols for climate. 

Table 4.2. Modeling Challenges and Barriers Votes 

Instruments  Instrumentation for advanced measurements is lacking 

 Technology for isolating black carbon in liquids is limited 

Standards/ 

Protocols 

 Uniformity is lacking in current measurements 

 There is little traceability of models in use today 

Data  Improve dissemination of evaluated data for use in models 

 Satellite and sub-ordinal measurements are not well-integrated with models 

 The accuracy of archived BC records in snow, ice cores, and lake sediments and 

translation of deposited BC to historic ambient concentrations is low; there are also 

technical issues with isolating BC in liquid or soil matrix and uncertainties when 

reproducing ambient values 



 International access, coverage, and remote data are all lacking 

 Other countries do not adequately share information and data 

Other  Significant resources are required to overcome challenges 

 Limitations exist in computations in finely grained models 

 There is a lack of prioritization and knowledge of the measurements and data that 

are needed to support climate programs 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

30 

Solutions and Approaches 

Five priority areas were identified and are summarized in Table 4.3. More detailed pathways to success 

for each area are provided in Figures 4-1 through 4-5 on the following pages. 

 Expanded Database of Fundamental Chemical and Physical Properties of Organic 

Compounds (see Figure 4.1). Understanding the properties of organics will require an 

expanded database of fundamental chemical and physical properties. The database should 

include refractive indices, solute activity coefficients and water activity, and mass 

absorption coefficients. Building this database will be a large task and should include wide 

involvement from the aerosol metrology community. 

 Expanded/Improved Source Emissions and Ambient Characterization (see 

Figure 4.2). Achieving better source emissions and ambient location characterization 

requires new measurements, instruments, standards, and database development. Improved 

characterization should include, size distribution, standardization of BC measurements, 

particle morphology, and characterization of ambient aerosols and elemental carbon for 

modeling. The current tendency is to focus only on absorption in this area; emissions 

should have equal representation. 

 Improved Radiometric Calibration for On-Orbit Imagers (see Figure 4.3). The 

problem of maintaining quality (greater than 1%) spectral radiometric calibration of 

imagers on orbit involves characterizing multiple pixels and understanding how they 

respond with clouds and scattered light—a highly complex scientific problem. 

Collaborative activities could accelerate progress in developing a calibrated hyper-spectral 

image projector that can record information on-orbit and last for 10–20 years. 

 Global Database of Aerosol Size Distribution, Shape, and Mixing State (see Figure 4.4). A 

database is needed that focuses on black carbon, elemental carbon, and organic carbon (including 

near-source and ambient conditions). Developing the database will require identifying 

instruments, methods, quality assurance/quality control (QA/QC) issues, accuracy, precision, and 

uncertainty of current measurements and generating a uniform global database, with metadata and 

common format. This activity builds on the new capabilities developed under Modeling Priority 

Topic: Source Emissions and Ambient Characterization. 

 Reference Materials for Aerosols Relevant to Climate (see Figure 4.5). A suite of updated and 

relevant reference materials for aerosols will provide the scientific community with access to a 

vital set of aerosol standards for climate change solutions. A greater number of measurements are 

needed as well as calibrated celestial sources for nighttime atmospheric data.
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

31

Milestones

Figure 4.1. 

Modeling Priority Topic: 

Expanded Database of Fundamental Chemical and Physical 

Properties of Organic Aerosol Compounds 

Measurement Challenge/Barrier

Understanding the properties of organics will require an expanded database of fundamental chemical and 

physical properties. The database should include refractive indices, solute activity coefficients and water 

activity, and mass absorption coefficients. Building this database will be a large task and should include wide 

involvement from the aerosol metrology community. 

Actions and Approach 

 Create a database for properties of organic 

compounds found or potentially found in organic 

aerosols. 

 Organize physical properties, including refractive 

indices) and activity coefficients (e.g., water/solute). 

 Organize chemical properties, including rate 

coefficients, gas, and aqueous; include other factors 

such as Henry’s law constant, equilibrium 

constant/crystallization, deliquescence, and 

reference material.

Performance Targets/Goals 

 Better data organization structure and broad 

involvement of scientific community. 

 Collection of existing data and determination of 

capabilities. 

 Effective inputs to models and simulation tools. 

 Large amount of accessible data on organic aerosols. 

Applications 

 Atmospheric and ground-based models to 

determine effect of aerosols on environment, 

climate, and health 

 Understanding/allocating source emissions

Potential Stakeholders and Roles 

Government Metrology laboratories: 

Properties and database 

development

National Laboratories Properties development 

Academia Properties development 

Decision makers Users of data 

Impacts 

 Contributes to economy and jobs by creating 

a basis for economic decisions. 

 Supports protection of environment and 

climate; provides basis for environmental 

decisions. 

 Promotes health and safety via data to study 

health effects. 

 Grows scientific knowledge via expanded 

basis for future scientific knowledge.

2011-2012 2015 2020 

Organize community to collect and 

compare data 

Validate data and optimized 

models 

 Improve and assimilate data 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

32 Milestones

Figure 4.2. 

Modeling Priority Topic: 

Source Emissions and Ambient Characterization

 

Measurement Challenge/Barrier

Achieving better source emissions and ambient location characterization requires new measurements, instruments, 

standards, and database development. Improved characterization should include, size distribution, standardization of 

BC measurements, particle morphology, and characterization of ambient aerosols and elemental carbon for modeling. 

The current tendency is to focus only on absorption in this area; emissions should have equal representation. 

Actions and Approach 

 Establish inter-comparisons and performance of 

instrumentation, including reference materials and 

uncertainty assignments per instrument. 

 Measure specific sources and ambient locations 

where data quantity is low or non-existent. Sources 

for example, include biomass (open, cook stoves); 

ambient locations could include remote sites 

(Eastern Arctic). 

 Develop laboratory and field studies characterizing 

atmospheric processing of emissions and 

physical/chemical transformation of particles. 

 Develop instrumentation for online particle 

morphology and mixing state.

Performance Targets/Goals 

 New measurements for distribution, particle morphology, 

(all species), and mixing state. 

 Standardized BC measurements—as mass concentration 

(carbon-based measurements), organic carbon (lightabsorbing carbonaceous matter) and absorption/scattering.

 Emissions inventory database and ambient database of 

chemical BC/OC, and particle shape.

 Portable, low-cost field instrument for widespread 

measurement of particle shape and mixing state.

Applications 

 Assessment of mitigation options for decision-makers 

 Understanding of aerosols and climate, especially in 

remote locations 

 

Potential Stakeholders and Roles 

Government Metrology laboratories, environment 

and ocean, energy, and regulatory:

instruments, testing, database 

development, inter-comparisons 

Academia Extension of existing activities 

International World Meteorological Organization 

(WMO) and Global Atmosphere 

Watch (GAW): Participation in data 

comparisons, other activities 

Impacts 

 Supports protection of environment and climate 

and promotes health and safety via improved 

scientific knowledge. 

 Accelerates competitiveness via better baseline 

information and understanding of mitigation 

options. 

2011-2012 2015 2020 

Develop and test 

Instrumentation for new 

measurements and intercomparisons 

 Implement technology in field and 

emissions studies 

 Meet deadline for carbon reductions 

according to the Intergovernmental Panel 

on Climate Change 

 Continue to refine 

methodologies based on results 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

33

Milestones

Figure 4.3. 

Modeling Priority Topic: 

Improved Radiometric Calibration for On-Orbit Imagers 

Measurement Challenge/Barrier

The problem of maintaining quality (greater than 1%) spectral radiometric calibration of imagers on orbit involves 

characterizing multiple pixels and understanding how they respond with clouds and scattered light—a highly 

complex scientific problem. Collaborative activities could accelerate progress in developing a calibrated hyperspectral image projector that can record information on-orbit and last for 10–20 years. 

Actions and Approach 

 Image a standard extended source from orbit. 

 Develop a hyperspectral image projector for onground calibration and characterization. 

 Develop sources for ground-based thermal vacuum 

calibrations. 

Performance Targets/Goals 

 Better than 1% absolute spectral radiometric 

calibration for UV, visible, near infrared spectroscopy, 

and possibly thermal infrared for on-orbit imagers. 

Applications 

 Improving applicability of quantitative space-based 

imagery for long-term climate studies and for accurate 

aerosol, surface, cloud, and resource remote sensing 

analyses 

Potential Stakeholders and Roles 

Government Aerospace, environment and ocean, 

defense, metrology laboratories: 

agencies that build and fly space-based 

imagers; agencies producing calibration 

standards; remote observing and 

instrument users and makers; test and 

validation of instruments and methods 

International World Meteorological Organization 

(WMO) and Global Atmosphere 

Watch (GAW): collaboration and 

validation 

Impacts 

 Supports protection of environment and climate 

via improved scientific knowledge. 

 Enhances credibility and accuracy of baseline 

atmospheric data. 

 Promotes health and safety via better 

understanding of potential impacts.

2011-2012 2015 2020 

Establish collaborative plan Image standard extended source from 

orbit 

 Develop hyper-spectral image projector 

for on-ground calibration

 Develop sources for groundbased thermal calibrations 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

34 Milestones

Figure 4.4. 

Modeling Priority Topic: 

Global Database of Aerosol Size Distribution, Shape, and 

Mixing State 

Measurement Challenge/Barrier

A database is needed that focuses on black carbon, elemental carbon, and organic carbon (including near-source 

and ambient conditions). Developing the database will require identifying instruments, methods, QA/QC issues, 

accuracy, precision, and uncertainty of current measurements and generating a uniform global database, with 

metadata and common format. This activity builds on the new capabilities developed under Modeling Priority 

Topic: Source Emissions and Ambient Characterization. 

Actions and Approach 

 Create database of aerosol particle size, optical 

properties, chemical BC/OC, particle shape, and 

mixing state, building on existing databases at 

NASA, NOAA, DOE, and EPA.

 Achieve monthly or weekly averages of data. 

 Implement particle surface measurements. 

 Develop methods for estimating measurement 

uncertainty of aerosols data. 

 Develop methods to process global, gridded data.

Performance Targets/Goals 

 Integrated, global, gridded aerosol data set for selected 

aerosol types. 

 Accessible database of size, shape, and mixing state.

Applications 

 Climate modeling 

 Locating future measurements 

 Satellite data validation

Potential Stakeholders and Roles 

Government Metrology laboratories: generate 

standard aerosols for analysis 

Aerospace: satellite data sets, surface 

networks 

Environment and ocean: climate 

relevant data sets form few locations, 

aircraft measurements 

Environment/regulatory: select 

surface, remote and aircraft data sets 

PM 2.5/PM 10 date networks for the 

United States

Impacts 

 Accelerates competitiveness by facilitating data 

sharing. 

 Promotes health and safety, protection of 

environment and climate, via expanded scientific 

knowledge. 

 Provides consistent accessible data for 

international use. 

 Provides new understanding of black and brown 

carbon and organic carbon aerosols.

2011-2012 2015 2020 2025+ 

Develop a detailed plan Establish methods, 

identify data sets, identify 

gaps in data 

Release first version of 

interpreted data sets of 

surface measurement for 

selected aerosol types 

Gridded data sets and 

vertical profiles 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

35

Milestones

Figure 4.5. 

Modeling Priority Topic: 

Reference Materials for Aerosols Relevant to Climate 

Measurement Challenge/Barrier

A suite of updated and relevant reference materials for aerosols will provide the scientific community with access to 

a vital set of aerosol standards for climate change solutions. A greater number of measurements are needed as well 

as calibrated celestial sources for nighttime atmospheric data.

 

Actions and Approach 

 Develop a suite of reference materials for instrument 

calibration to address source emissions and ambient 

aerosols. 

– Particles with known refractive index and size, 

mixed composition 

– Example: silver/gold—use internally mixed lightscattering natural dust with organics to address 

source emissions 

 Develop calibrated celestial sources.

Performance Targets/Goals 

 Improved measurement accuracy through relevant 

instrument calibration. 

 Reconciliation of emission source measurements with 

ambient aerosols measurements. 

 High precision measurements to assess availability 

and optical properties for relevant species and aged 

aerosols.

Applications 

 Instrument calibration 

 Aerosol climate studies 

 Related studies (health, safety, environment)

Potential Stakeholders and Roles 

Government Metrology laboratories: 

reference materials 

Environment/regulatory:

guidance for standards 

International International Organization 

for Standardization(ISO):

standards 

Standards 

Organizations 

American Society for 

Microbiology (ASM):

standards

National Laboratories 

Industry, Private 

Research Groups 

Users of standards 

Impacts 

 Supports protection of environment and climate 

via expansion of scientific knowledge. 

 Standardizes results to allow comparison across 

studies both domestically and globally.

2011-2012 2015 2020 

 Identify key reference materials 

needed 

 Identify properties and applications 

 Calibrate celestial sources

 Complete development of reference 

materials and standards/protocols 

 Develop capability for high precision 

measurements and calibration

 Update and refine standards as 

needed 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

36 Satellite image from iStockphoto. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

37

Collaborative Models 

Existing Collaborations 

A number of potential collaborative models were identified that could be effective in solving some of the 

problems in aerosol metrology. 

 Hubs modeled after the Manhattan Project, and similar to those now underway at the U.S. 

Department of Energy (DOE) (http://science.energy.gov/bes/research/doe-energy-innovationhubs/), and could include multiple agencies and organizations. 

 Non-profit organizations like Fiatech (construction) and Sematech (electronics), where research 

could be cost-shared through member-pooled contributions, and would include a board of 

directors making decisions on research directions. 

 Collaborations where efforts are centralized and focused, including the DOE Bioenergy Centers, 

DOE Advanced Research Projects Agency – Energy (ARPA-E), and Department of Defense 

(DOD), Defense Advanced Research Projects Agency (DARPA). 

Collaborative Success Factors 

Centralized, organized management of research has been a key factor for success in some collaborative 

activities, including the Hub model, ARPA-E and others. Overall this approach allows for greater 

leverage and coordination of resources among many different organizations with various objectives. This 

is particularly important for those collaborations where multi-disciplinary research is required. 

Centralization of research management could provide a number of benefits: 

 Collaboration on recruiting of critical communities and scientists would bring multi-disciplinary 

skills together. 

 Providing a framework where many different communities involved can work under common 

goals and definitions would provide consistency. 

 Definition of needs for community infrastructure, such as calibration facilities, tools, and data, 

would broadly increase capabilities for key measurements. 

Mechanisms for Encouraging Collaboration 

Many different communities are involved in aerosols metrology. As a result, research can often be stovepiped, which can inhibit collaboration. 

Potential approaches for encouraging work among diverse disciplines and stakeholder communities 

include: 

 A single facility with the capability to generate live aerosols is lacking and could be accessed 

widely for calibration. Such a facility could start at a minimum level and build capability and user 

communities over time. Initially it should consist of well-characterized aerosol size distribution 

and then build additional capability. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

38 

 One of the impediments to collaborating is distance. Virtual collaboration, which is cheap and 

easy to do, could include seminars and social media (e.g., similar to the NanoHub) to keep people 

involved. This would broaden the community at low cost. 

 Greater interaction of modelers and researchers is needed. Modelers and lab researchers should 

interact more to understand the details of measurements and definitions (e.g., Aerocom for data 

collection). 

 Many authorities on aerosol standards exist and there is a need to establish a common framework 

and legitimacy. 

 This is a global community, and challenges need to be tackled at the international level, bringing 

together all stakeholders and communities. 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

39

Appendix A. Workshop Participants 

Magdalena Anguelova, Naval Research Laboratory 

W. Patrick Arnott, University of Nevada 

Pedro Bueno, National Institute of Standards and Technology 

Peter Buseck, Arizona State University 

Joseph Conny, National Institute of Standards and Technology 

Claire Cramer, National Institute of Standards and Technology 

Gerald Fraser, National Institute of Standards and Technology 

Andrew Freedman, Aerodyne Research, Inc. 

Kirk Fuller, University of Alabama in Huntsville 

Santiago Gasso, University of Maryland, Baltimore County 

Carlos Gonzalez, National Institute of Standards and Technology 

Gayle Hagler, United States Environmental Protection Agency 

Michael Hays, United States Environmental Protection Agency 

Joseph Hodges, National Institute of Standards and Technology 

Raymond Hoff, University of Maryland, Baltimore County 

Amara Holder, United States Environmental Protection Agency 

Cody Howard, United States Department of Agriculture 

Alex Huffman, Max Planck Institute 

Charles Ichoku, NASA Goddard Space Flight Center 

Mark Jacobson, Stanford University 

Ralph Kahn, NASA Goddard Space Flight Center 

Alicia Kalafut-Pettibone, National Institute of Standards and Technology 

Beth Kautzman, National Institute of Standards and Technology 

Dorothy Koch, United States Department of Energy 

Charles Kolb, Aerodyne Research, Inc. 

Rao Kotamarthi, Argonne National Laboratory 

Daniel Lack, National Oceanic and Atmospheric Administration, ESRL Chemical 

Traci Lersch, RJ Lee Group 

John Lu, National Institute of Standards and Technology 

Xiaofei Ma, National Institute of Standards and Technology 

Carrie Maseillo, Rice University 

W. Sean McGivern, National Institute of Standards and Technology 

Peter McMurry, University of Minnesota 
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE

40 

George Mulholland, University of Maryland 

Falguni Patadia, GEST/UMBC 

Dianne Poster, National Institute of Standards and Technology 

Cary Presser, National Institute of Standards and Technology 

Frank Raes, European Commission Joint Research Centre 

Subramanian Ramachandran, Droplet Measurement Technologies 

Claudette Rosado-Reyes, National Institute of Standards and Technology 

Michele Schantz, National Institute of Standards and Technology 

Stephen Schwartz, Brookhaven National Laboratory 

David Sheen, National Institute of Standards and Technology 

John Small, National Institute of Standards and Technology 

Christopher Sorenson, Kansas State University 

Wing Tsang, National Institute of Standards and Technology 

Greg Turk, National Institute of Standards and Technology 

Roger van Zee, National Institute of Standards and Technology 

Rodney Weber, Georgia Institute of Technology 

James Whetstone, National Institute of Standards and Technology 

Ashley Williamson, United States Department of Energy 

John Woodward, National Institute of Standards and Technology 

Ping Yang, Texas A&M University 

Michael Zachariah, National Institute of Standards and Technology 

Chris Zangmeister, National Institute of Standards and Technology
AEROSOL METROLOGY NEEDS FOR CLIMATE SCIENCE 

41

Appendix B. Speaker Presentations 

Peter Buseck, Arizona State University 

Chemical/Dimensional Metrology: Identification and Analysis of Atmospheric Particles 

Raymond Hoff, University of Maryland, Baltimore County (UMBC) 

Optical Properties: The Global Atmosphere Watch (GAW) Aerosol Lidar Observation Network 

(GALION): Issues Involved with Obtaining Precise Optical Extinction Profiles for Climate Records 

Mark Jacobson, Stanford University 

Modeling: Incorporation of Aerosol Optical Properties into Climate Models 

Ralph Kahn, National Aeronautics and Space Administration, Goddard Space Flight Center 

From Measurement to Models: What Satellite and Sub-Orbital Instruments Can and Must Contribute 

Dorothy Koch, United States Department of Energy 

Programmatic Plenary: Uncertainties and Frontiers in Aerosols Research 

Charles Kolb, Aerodyne Research, Inc. 

Chemical/Dimension Metrology: Development of Advanced Field Measurement Techniques for 

Sampling Ambient Atmospheric Particles 

Rao Kotamarthi, Argonne National Laboratory 

Modeling: Aerosol Parameterizations and Evaluations using Observational Data 

Daniel Lack, National Oceanic and Atmospheric Administration 

Optical Properties: Challenges for In-Situ Measurements of Aerosol Absorption and Influence on 

Climate Forcing 

Carrie Masiello, Rice University 

Optical Properties: Elucidation of Environmental Carbon Cycles; Optical Properties: Elucidation of 

Environmental Carbon Cycles 

Frank Raes, European Commission Joint Research Centre 

Opening Plenary: The Role of Aerosols in Climate Change 

Stephen Schwartz, Brookhaven National Laboratory 

Optical Properties: Variation of Aerosol Optical Properties and Radiative Implications 

Rodney J. Weber, Georgia Institute of Technology 

Chemical/Dimension Metrology: How Physical and Chemical Properties Data Reflects Aerosol 

Formation Processes and their Evolution 

Ping Yang, Texas A&M University 

Optical Properties of Airborne Dust: The Effect of Particle’s Nonsphericity on the Single-Scattering 

Properties and Downstream Applications 
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42 Photo courtesy of NASA. 
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Appendix C. References and Additional 

Resources 

CCSP 2009. Atmospheric Aerosol Properties and Climate Impacts. U.S. Climate Change 

Science Program and the Subcommittee on Global Change Research. National 

Aeronautics and Space Administration, Washington, D.C., USA. 2009. 

http://www.climatescience.gov/Library/sap/sap2-3/final-report/default.htm

Scott 2007. John Henry J. Scott. “Accuracy issues in chemical and dimensional metrology in 

the SEM and TEM.” Measurement Science and Technology, Volume 18, Number 

9 (2755), 2007. http://iopscience.iop.org/0957-0233/18/9/003 

NRCC 2011. National Research Council Canada. Chemical Metrology Program. 2011. 

http://www.nrc-cnrc.gc.ca/eng/programs/inms/chemical-metrology.html

NSF 2011. National Science Foundation, Center for Aerosol Impacts on Climate and the 

Environment. http://caice.ucsd.edu/Research_Tools.html 

PNL 2011. Pacific Northwest National Laboratory, Atmospheric Sciences and Global 

Change. http://www.pnl.gov/atmospheric/programs/aerosol.stm 

Amber 2011. Assisted Model Building with Energy Refinement. http://ambermd.org/

PNL-UCSD 2011. Pacific Northwest Laboratory and University of California, San Diego. Aerosol 

Chemistry and Climate Institute. http://www.pnl.gov/atmospheric/programs/acci/ 

ESRL 2011. U.S. Department of Commerce, National Oceanic and Atmospheric 

Administration (NOAA), Earth System Research Laboratory (ESRL): Aerosols: 

Climate and Air Quality. 

http://www.esrl.noaa.gov/research/themes/aerosols/aerosols.html

GAW 2011. World Meteorological Organization, Global Atmosphere Watch, Aerosols 

Research. http://www.wmo.int/pages/prog/arep/gaw/aerosol.html 

Aero 2011. The Aerocom Project. 2011. http://dataipsl.ipsl.jussieu.fr/AEROCOM/
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