GEWEX WORKING GROUP: AEROSOLS
MEMBERSHIP
Zhanqing Li (co-chair, GRP representative), T. Zhao (co-chair), M. Mishchenko (GACP representative).
Report for the GEWEX Newsletter
1st Workshop on the GEWEX Global Aerosol Products Assessment (GAPA)
2006 September 14-15, College Park, University of Maryland, USA
Aerosols are a major atmospheric variable influencing both the transfer of
radiative energy, and the conversion of water vapor into cloud droplets and
raindrops. As such, most GCMs are now incorporating aerosol parameters and
physical processes linking aerosols with the energy and water cycles so that
aerosol direct and indirect effects on climate can be computed. Over the years,
numerous global aerosol products have been generated from past (e.g. AVHRR,
TOMS, POLDER) and current satellite sensors (e.g. MODIS, MISR, CALIPSO), and
more are expected from future sensors (e.g. APS, OMPS, and VIIRS). As the number
of aerosol products increases, discrepancies among the products also increase.
Data users, especially modelers, are confronted with an ever-increasing
challenge to decide which product to use and how much uncertainty exists in the
different products.
Under the auspices of the Global Energy and Water Cycle Experiment (GEWEX)
and the GEWEX Radiation Panel (GRP), a working group (GAPA) was recently established to
assess the quality and compatibility of global aerosol product with a focus on
the GEWEX Aerosol Climatology Product (GACP). The group is led by
Z. Li (a GRP member) and X. Zhao from the University of Maryland (UMD), with members
representing all major teams producing global aerosol
products. The photo shows a partial list of the members attending the first
kick-off meeting held from September 14-15, 2006, in College Park, Maryland, USA.
First row from left: A. Higurashi (NIES, Japan), C. Hsu (GSFC/NASA), L. Remer
(GSFC/NASA), M. Chin (GSFC/NASA), O. Torres (UMD/NASA); Centre row from left: R.
Kahn (JPL/NASA), D. Diner (JPL/NASA), M. Wang (NOAA), I. Laszlo (NOAA), D.
Winker (LaRC/NASA), Z. Obradovic (Temple University); last row: H. Maring
(HQ/NASA), B. Holben (GSFC/NASA), S. Vucetic (Temple University), Z. Li (UMD),
S. Tsay (GSFC/NASA), C. Ichoku (UMD/NASA), T. Zhao (UMD/NOAA), M. Schulz (CEA,
France), M. Mishchenko (GISS/NASA)
PLAN OF WORK
The objectives of the working group are to:
1) Use current data sets to assess and improve the confidence level in the
30-year satellite aerosol climatology of aerosol optical depth (AOD) and
Angstrom exponent from AVHRR/TOMS;
2) Understand and resolve discrepancies among all major global aerosol
products and to document uncertainties;
3) Produce improved, consistent, unified global aerosol products that link
both historical, current, and future satellite observations for long-term trend
studies and climate studies.
The workshop was charged to:
1) Review major global aerosol products;
2) Evaluate all key issues in aerosol retrievals such as sensor calibration,
cloud screening, algorithm, surface effects, synergy;
3) Develop a strategy for identifying major sources of discrepancies among
the aerosol products;
4) Estimate the range of uncertainties on various time and space scales;
5) Develop a roadmap for reconciling the differences and for generating
unified consistent products.
During the two-day meeting, aerosol product development teams provided
updates of various products (AVHRR-GACP, AVHRR-PATMOS, AVHRR-NIES, TOMS,
SeaWiFS, MODIS, MODIS-Deep Blue, MISR, CALIPSO) and detailed descriptions of the
retrieval procedures. Such information is instrumental in understanding the
causes for any discrepancies. A couple of comparative studies/analyses were
presented that helped gain some insight into the impact of different assumptions
made in the retrieval algorithms (e.g. aerosol size distribution, refractive
index, surface spectral albedo ratio, etc.) on the differences in the retrieved
aerosol quantities. It was noted that the MODIS aerosol product is upgraded in
its latest release (version 5) to correct some errors in the AOD retrieval over
land. New advances in aerosol remote sensing technology were introduced, such as
the CALIPSO mission and the deep-blue method. An upcoming newer version (version
2) of the widely used ground-based AERONET product is expected to produce more
realistic aerosol size distributions and single scattering albedos. Issues
associated with spatial and temporal matching between satellite and ground
aerosol retrievals were discussed. A new computationally more efficient
retrieval approach based on machine-learning techniques appears to offer some
guidance toward the development of a highly integrated algorithm that can
incorporate all available satellite data. In parallel with satellite remote
sensing of aerosols, model simulations of global aerosol distributions have made
remarkable progress. Over land, the quality of the AODs simulated by some models
is at par with that of remotely sensed AODs, while the latter is superior over
oceans. This suggests the importance of exploiting the synergy between model
simulations and remote sensing. Joint experimental studies are planned to
quantify and eventually remove discrepancies between the various aerosol
products, which will lead to a coherent aerosol product derived from all
available sensors that is compatible with the long-term historical product of
the GACP.
For more information and update of the GAPA activities, please visit:
http://www.atmos.umd.edu/~zli/GAPA/gapa_main.htm
List of GAPA Members Attending the 1st Workshop
1. Dr. Mian Chin (NASA/GSFC)
Voice: 301-614-6007
mian.chin@nasa.gov
2. Dr. David J. Diner (JPL)
Voice: 818-354-6319
David.J.Diner@jpl.nasa.gov
3. Dr. Akiko Higurashi (NIES, Japan)
Voice: +81-29-850-2423
hakiko@nies.go.jp
4. Dr. Brent N. Holben (NASA/GSFC)
Voice: 301-614-6658
brent@aeronet.gsfc.nasa.gov
5. Dr. Christine Hsu (NASA/GSFC)
Voice: 301-614-5554
Christina.Hsu@nasa.gov
6. Dr. Charles Ichoku (ESSIC/UMCP & NASA/GSFC)
Voice: 301-614-6212
ichoku@climate.gsfc.nasa.gov
7. Dr. Ralph A. Kahn (JPL)
Voice: 818-354-9024
Ralph.kahn@jpl.nsa.gov
8. Dr. Istvan Laszlo (NOAA/NESDIS/ORA)
Voice: 301-763-8053 (Ext. 111)
Istvan.Laszlo@noaa.gov
9. Prof. Zhanqing Li (ESSIC/UMCP)
Voice: 301-405-6699; Cell: 443-538-8185
zli@atmos.umd.edu
10. Dr. Hal Maring (NASA Headquarter)
Voice: 202-358-1679
Hal.maring@nasa.gov
11. Dr. Michael Mishchenko
Voice: 212-678-5590
mmishchenko@giss.nasa.gov
12. Prof. Zoran Obradovic (CISD/Temple University)
Voice: 215-204-6265
zoran@ist.temple.edu
13. Dr. Lorraine A. Remer (NASA/GSFC)
Voice: 301-614-6194
Lorraine.A.Remer@nasa.gov
14. Dr. William B. Rossow (NASA/GISS)
Voice: 212-687-5567
wrossow@giss.nasa.gov
15. Dr. Michael Schulz (AeroCom)
Voice: +33-1-6908-7725
Michael.schulz@cea.fr
16. Dr. Omar Torres (UMBC/GSFC)
Voice: 301-614-5551
torres@tparty.gsfc.nasa.gov
17. Dr. Menghua Wang (NOAA/NESDIS/STAR)
Voice: 301-763-8102 (Ext. 163)
Menghua.Wang@noaa.gov
18. Dr. David Winker (NASA/Langley)
Voice: 757-864-6747
David.m.winker@nasa.gov
19. Dr. Tom Zhao (ESSIC/UMCP & NOAA/NESDIS/ORA)
Voice: 301-763-8059 (Ext. 213)
Xuepeng.Zhao@noaa.gov
1st Workshop on the Assessment of Global Aerosol Products
Aerosol Working Group (AWG) for the GEWEX Radiation Panel
14-15 September 2006
Earth System Science Interdisciplinary Center
University of Maryland, College Park, MD 20742
Meeting Goals
(1) Formation of the new aerosol working group (AWG) under the GEWEX Radiation Panel (GRP)
(2) Planning for joint assessment of satellite aerosol retrievals in support of the production of consistent long-term aerosol data products for climate studies.
Agenda - Final
Thursday AM
Chair: Z. Li
0830-0835: Welcome Remarks and Meeting Logistics (Z. Li, P. Arkin, R. Dickerson, Linda Carter)
0835-0900: Introduction of the GEWEX Products Assessment Initiative (W.B. Rossow)
0900-0930: GACP report (M. Mischenko)
0930-1000: The TOMS long-term record of aerosol properties from near UV observations (O. Torres).
1000-1030: A critical examination of the MODIS aerosol products and their usefulness in
estimating global aerosol radiative effects and forcing (L. Remer)
1030-1100: Break
Chair: H. Maring
1100-1130: Inter-comparison of MODIS, AVHRR and TOMS aerosol products and algorithms (Z. Li)
1130-1200: MISR Aerosol Product Strengths and Limitations for Large-Scale and Long-Term
Climate Studies (R. Kahn)
1200-1300: Lunch (provided)
Thursday PM
Chair: W. Rossow
1300-1330: Analysis of historical PATMOS AVHRR aerosol data in support of long-term trend study (T. Zhao)
1330-1400: An evaluation of single- and multi-channel aerosol optical depth retrievals (I. Laszlo)
1400-1430: MODIS and GLI aerosol analysis with 4-channel algorithm and the comparison with SPRINTARS
model simulations (A. Higurashi).
1430-1500: Progress toward the CALIPSO aerosol product (D. Winker)
1500-1530: Break
Chair: T. Zhao
1530-1600: Improvements in AERONET aerosol products based on Version 2 processing and synergism with
parameters (B. Holben)
1600-1630: Issues in validating satellite aerosol products against ground-based observations (C. Ichoku)
1630-1700: Aerosol products over oceans derived from SeaWifs and MODIS (M. Wang)
1730: End of the day
Friday AM
Chair: M. Mishchenko
0900-0930: Developing a long-term vision: Recommendations from the August 2005
Williamsburg NASA Aerosol Strategy Workshop (D. Diner)
0930-1000: Combined use of model and satellite data for evaluating near-term to long-term
aerosol trends (M. Chin)
1000-1030: Aerosol model evaluation challenges with reference to AeroCom (M. Schulz)
1030-1100: Break
Chair: L. Remer
1100-1130: Global MODIS aerosol product using the deep algorithm over land (C. Hsu)
1130-1200: Data mining support for aerosol retrieval and analysis (Z. Obradovic)
1200-1300: Lunch (Provided)
Friday PM
1300-1600: Group discussions
Issues to be addressed
(1) Cloud screening methods
(2) Surface effects
(3) Aerosol models
(4) Retrieval algorithm
(5) satellite-ground comparison issues
(6) Synergy issues
(7) Strategy and roadmap for generating integrated consensus long-term global aerosol products
(8) Organization and collaboration
1600-1630: Break
1630-1730: Action items and recommendations
Concluding Remarks (Hal Maring)
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