Overview of ACE-Asia Spring 2001 Investigations on Aerosol-Radiation Interactions P. B. Russell1, P. J. Flatau2,3, F. P. J. Valero2, T. Nakajima4, B. Holben5, P. Pilewskie1, M. Bergin6, B. Schmid7, R. W. Bergstrom7, A. Vogelmann2, B. Bush2, J.

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Overview of ACE-Asia Spring 2001 Investigations
on Aerosol-Radiation Interactions P. B.
Russell1, P. J. Flatau2,3, F. P. J. Valero2, T.
Nakajima4, B. Holben5, P. Pilewskie1, M.
Bergin6, B. Schmid7, R. W. Bergstrom7, A.
Vogelmann2, B. Bush2, J. Redemann7, S. Pope2, J.
Livingston8, S. Leitner2, N. C. Hsu9, J. Wang10,
J. Seinfeld10, D. Hegg11, P. Quinn12, and D.
Covert11
1NASA Ames Research Center, Moffett Field,
CA2University of California, San Diego,
CA3Naval Research Laboratory, Monterey,
CA6Georgia Institute of Technology, Atlanta,
GA 5NASA Goddard Space Flight Center, Greenbelt,
MD 4University of Tokyo, Tokyo, JAPAN
7Bay Area Environmental Research Institute,
Sonoma, CA 8SRI International, Menlo Park,
CA 10California Institute of Technology,
Pasadena, CA 9GEST/NASA Goddard Space Flight
Center, Greenbelt, MD 11University of
Washington, Seattle, WA 12NOAA/PMEL OCRD,
Seattle, WA
IGAC/CACGP Atmospheric Chemistry Conference 18-25
September 2002 Hersonissos, Heraklion, Crete,
GREECE
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ACE-Asia 2001 3 Goals, greatest emphasis on first
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1. Determine the physical, chemical, and
radiative properties of the major aerosol types
in the Eastern Asia and Northwest Pacific region
and investigate the relationships among these
properties.
2. Quantify the interactions between aerosols and
radiation in the Eastern Asia and Northwest
Pacific region
3. Quantify the physical and chemical processes
controlling the evolution of the major aerosol
types and in particular of their physical,
chemical, and radiative properties.
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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Land - Ship - Aircraft -
Satellites

Regional assessment of aerosol radiative forcing
Analyses still in progress (e.g., JGR section).
We have gone end-to-end to get a first-cut
regional forcing assessment. Ill show that
assessment then indicate what needs to be
done to improve it.
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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Land
-- AERONET retrievals, 13 sites China, S.
Korea, Taiwan, Japan Holben, Lu et al. --
Composition SSA, Amami Island, Japan
Ohta -- Radiative Fluxes, Yulin, China
Bergin et al. -- Radiative Fluxes, Kosan,
Korea Valero et al.
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AERONET--Beijing example from 13 sites in China,
S. Korea, Taiwan, Japan
Holben, Lu et al.
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AERONET--Beijing example from 13 sites in China,
S. Korea, Taiwan, Japan
Holben, Lu et al.
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AERONET--Beijing example from 13 sites in China,
S. Korea, Taiwan, Japan
Holben, Lu et al.
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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Land
-- AERONET retrievals, 13 sites China, S.
Korea, Taiwan, Japan Holben, Lu et al. --
Composition SSA, Amami Island, Japan
Ohta -- Radiative Fluxes, Yulin, China
Bergin Xu -- Radiative Fluxes, Kosan, Korea
Valero et al.
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PAR Sensors, Yulin, China
M. Bergin J. Xu
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Comparison of the Modeled (TUV(NCAR)) and
Measured Downward PAR Values

• PAR Photosynthetically Active Radiation (400
  700 nm)
• The model underestimates measured PAR by 2.
• Model results are based on measured single
  scattering albedo (?) and Aerosol optical
  depth (?500) at each data point, asymmetry factor
  (g) 0.8, surface albedo (?s) 0.3.

M. Bergin J. Xu
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Estimation of the 24-h Mean Aerosol Radiative
Forcing Efficiency in Yulin
24-h mean aerosol radiative forcing, W m-2
M. Bergin J. Xu

• Calculated 24-h mean aerosol radiative forcing
  efficiency for PAR (400 700 nm) and total solar
  radiation (TSR, 0.2 4.0 mm) at surface and top
  of atmosphere (TOA) on 4 / 15 / 2001 (single
  scattering albedo ? 0.93 , asymmetry factor g
  0.8, surface albedo ?s 0.3).

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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Ship
-- AOD along cruise Markowicz, Flatau et al. --
In situ Scat, Abs, SSA Quinn et al. -- Aerosol
longwave effects from FTIR Vogelmann,
Flatau et al. -- Ocean surface reflectance
Mitchell et al.
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Aerosol Optical Depth Measured by Solar
Photometry Aboard RV Ron Brown
Mar 16 Mar 26
Apr 5 Apr 15
Hachijo to Sea of Japan
Sea of Japan to Yokosuka
l 500 nm
Hawaii to Hachijo
Aerosol Optical Depth
Markowicz, Flatau et al.
Julian Day
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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Ship
-- AOD along cruise Markowicz, Flatau et al. --
In situ Scat, Abs, SSA Quinn et al. -- Aerosol
longwave effects from FTIR Vogelmann,
Markowicz et al. -- Ocean surface reflectance
Mitchell et al.
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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Ship
-- AOD along cruise Markowicz, Flatau et al. --
In situ Scat, Abs, SSA Quinn et al. -- Aerosol
longwave effects from FTIR Vogelmann,
Markowicz et al. -- Ocean surface reflectance
Mitchell et al.
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Longwave Radiance Measured by FTIR Aboard RV Ron
Brown
10 mm
Vogelmann, Markowicz, Szczodrak, Flatau, Minnett
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Vogelmann, Markowicz, Szczodrak, Flatau, Minnett
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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Aircraft
-- Vertical dependence of
AOD(l) Livingston, Redemann, Schmid et
al. Composition Wang et al. Size Wang et
al. Scatt. Abs. Masonis, Anderson, et al.
Hegg et al. Hygroscopicity Clarke et
al. Radiative Flux(l) Pilewskie et al., Pope,
Valero et al.
-- Closure among the above many authors --
Aerosol absorption from radiative flux profiles
Pilewskie et al. -- Horizontal gradients of
AOD and Rad Flux Redemann, Pilewskie, Pope,
Valero, et al.
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Twin Otter research flight 11, April 17, 2001
33ºN 128ºE, West of Kyusyu Island
BLBoundary layer PLPollution layer FT Free
troposphere
Wang et al. 2002
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Aerosol Optical Depth Extinction Profiles From
AATS-14 on Twin Otter, 4/17/2001
Schmid et al.
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Chemical Composition and size distributions,
flight 11, April 17, 2001
Wang et al. JGR 2002
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Wang, Schmid, et al. JGR 2002
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Free Troposphere
Pollution Layer
Boundary Layer
Wang, Schmid, et al. JGR 2002
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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Aircraft
-- Vertical dependence of
AOD(l) Livingston, Redemann, Schmid et
al. Composition Wang et al. Size Wang et
al. Scatt. Abs. Masonis, Anderson, et al.
Hegg et al. Hygroscopicity Clarke et
al. Radiative Flux(l) Pilewskie et al., Pope,
Valero et al.
-- Closure among the above Redemann et al.
poster -- Aerosol absorption from radiative flux
profiles Pilewskie et al. -- Horizontal
gradients of AOD and Rad Flux Redemann,
Pilewskie, Pope, Valero, et al.
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C-130 PBL AOD Comparison
l550 nm
AOD from Neph PSAP
AOD from AATS-6 Airborne Sunphotometer
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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Aircraft
-- Vertical dependence of
AOD(l) Livingston, Redemann, Schmid et
al. Composition Wang et al. Size Wang et
al. Scatt. Abs. Masonis, Anderson, et al.
Hegg et al. Hygroscopicity Clarke et
al. Radiative Flux(l) Pilewskie et al., Pope,
Valero et al.
-- Closure among the above many authors,
e.g. Redemann et al. poster -- Aerosol
absorption from radiative flux profiles
Pilewskie et al. -- Horizontal gradients of AOD
and Rad Flux Redemann, Pilewskie, Pope,
Valero, et al.
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• Downwelling Flux F?
• Upwelling Flux F?
• Net Flux F?- F?
• Flux Divergence (absorption)
• (F?- F?)2000m- (F?- F?)43m
• Fractional absorption
• (F?- F?)2000m- (F?- F?)43m/ F?2000m

2000 m
43 m
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Pilewskie, Bergstrom, Schmid et al.
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Aerosol Single Scattering Albedo Spectrum
Derived from measured flux and AOD spectra
Single scattering albedo
Bergstrom,Pilewskie, Schmid et al.
Wavelength, nm
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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Satellites
-- SeaWiFS imagery NASA/GSFC ORBIMAGE --
SeaWiFS retrievals standard advanced Hsu
et al., Higurashi et al.. -- SeaWiFS validation
Schmid, Redemann et al. -- MISR imagery and
validation, etc. Kahn, Schmid, Redemann et
al.
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12 Apr 2001 SeaWiFS Project NASA/GSFC ORBIMAGE
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Schmid, Hsu et al.
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Regional Assessment of Aerosol Radiative
ForcingNorth Pacific, 20-55 N
Needs
Approach

• Combine Satellite and Suborbital Data

• ta(l,x,y,z,t)
• wa(l,x,y,z,t)
• ba(l,x,y,z,t)
• As(l,x,y,m0)

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Regional Assessment of Aerosol Shortwave
Radiative ForcingNorth Pacific, 20-55 N
Suborbital (ACE-Asia)
Satellite ta(865 nm,x,y,t)

• ta(l)/ta(865 nm) Models constr. by Sat.
  Sunphot.
• ta(z) A/C, Lidar Meas (dust above pollution)
• wa(z,l) A/C Meas, Models
• ba(l,m0) Size distributions sunphot in situ
  meas
• As(m0) models

0 0.2 0.4 0.6 0.8
SeaWiFS, April 2001 C. Hsu retrieval
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Aerosol Vertical Profiles Assumed for Forcing
Calculations
tdust /tpoll adjusted to make amodel aSeaWiFS
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Calculated Aerosol Shortwave Forcing vs Optical
Depth
Ratio, DF?, Surface
2 to 3
DFnet, TOA
Dust
Pollution
Larger over land
Bergstrom
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Regional Assessment of Aerosol Shortwave
Radiative ForcingNorth Pacific, 20-55 N
Satellite Suborbital
Satellite
0 -20 -40
-60 Downward Flux Change at Surface (W m-2)
0 0.2 0.4 0.6 0.8
SeaWiFS ta(865 nm) April 2001, C. Hsu retrieval
24-h avg, dust (wa0.95) over pollution
(wa0.90), no clouds.
Bergstrom
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Conclusions
This sampling of results indicates how
ACE-Asias measurements from land, sea, air
space are being used to get a first-cut regional
assessment of aerosol direct radiative forcing.
Journal papers mainly still in preparation.
E.g., gt100 titles listed for JGR special section.
Much remains to be done--Whats most important?
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Whats Next?
Continued analyses of suborbital data
(including closure tests) to reduce error bars on
aerosol intensive radiative properties SSA(l),
g(l) -- Dust vs Pollution vs Mixed --
Vertical distributions Continued tests of
satellite retrievals (esp. advanced SeaWiFS new
sensors like MODIS MISR) to get the best
regional map of AOD(l), g(l), aerosol type,
SSA(l) Continued tests of CTMs, especially
vertical distributions by aerosol type
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Whats Next? (contd)
Incorporate cloud effects into direct
radiative forcing estimates -
Cloud-filter effects on satellite retrievals of
AOD, aerosol type. - Effect of clouds
above below aerosols on direct aerosol
forcing Extend satellite retrievals and
forcing calculations over land Treat ocean
surface reflectance(x,y,l) more accurately,
using ship measurements Aerosol indirect
effects
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l550 nm
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l550 nm
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l550 nm
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Aerosol type analysis with SeaWiFS data
APEX, ACE-Asia 15 April 2001
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Monthly mean aerosol type classfication by SeaWiFS
Higurashi (2001)
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ACE-Asia 2001 Aerosol-Radiation Interactions
Measurements - Land
-- AERONET retrievals, 13 sites China, S.
Korea, Taiwan, Japan Holben, Lu et al. --
Composition SSA, Amami Island, Japan
Ohta -- Radiative Fluxes, Yulin, China Bergin
et al. -- Radiative Fluxes, Kosan, Korea Bush
Valero
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Dust events of 10 and 11-16 April at Amami
S. Ohta 2001
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13 Apr 2001 0242 0449 UTC? SeaWiFS
Project NASA/GSFC ORBIMAGE
http//visibleearth.nasa.gov/cgi-bin/viewrecord?79
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ACE-Asia 2001 Interactions between aerosols and
radiation Were studied by
Measurements - Land - Ship - Aircraft -
Satellites
Models - Used to guide measurements - Now
being tested by measurements - Goal Pull
measurements into overall coherent picture
Purpose of this talk Show how all the above are
being used together to quantify aerosol-radiation
interactions
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Boundary layer
Pollution layer
Free trop layer
Schmid, Wang, Hegg et al. 2001
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Regional Assessment of Aerosol Shortwave
Radiative ForcingNorth Pacific, 20-55 N
0 0.2 0.4 0.6 0.8
SeaWiFS ta(865 nm) April 2001, Std retrieval
SeaWiFS ta(865 nm) April 2001, C. Hsu retrieval
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Regional Assessment of Aerosol Shortwave
Radiative ForcingNorth Pacific, 20-55 N
Satellite Suborbital
Satellite
0 -20 -40
-60 Downward Flux Change at Surface (W m-2)
0 0.2 0.4 0.6 0.8
SeaWiFS ta(865 nm) April 2001, C. Hsu retrieval
24-h avg, dust (wa0.95) over pollution
(wa0.90), no clouds.
Bergstrom
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Regional Assessment of Aerosol Shortwave
Radiative ForcingNorth Pacific, 20-55 N
New (tdust /tpoll from SeaWiFS a)
Old (tdust /tpoll 1)
0 -20 -40
-60 Downward Flux Change at Surface (W m-2)
0 -20 -40
-60 Downward Flux Change at Surface (W m-2)
24-h avg, dust (wa0.95) over pollution
(wa0.90), no clouds.
Bergstrom, Hsu et al.
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April 2001 Monthly Average Optical Depth
Angstrom Exponent from SeaWiFSNorth Pacific,
20-55 N
Angstrom Exponent a
ta(865 nm)
0 0.2 0.4 0.6 0.8
0 0.4 0.8 1.2
C. Hsu