Overview of ACE-Asia Spring 2001 Investigations on

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 NASA Ames Research Center, Moffett Field, CA 2 University of California, San Diego, CA 3 Naval Research Laboratory, Monterey, CA 6 Georgia Institute of Technology, Atlanta, GA 5 NASA Goddard Space Flight Center, Greenbelt, MD 4 University of Tokyo, Tokyo, JAPAN 1 Bay Area Environmental Research Institute, Sonoma, CA 8 SRI International, Menlo Park, CA 7 California Institute of Technology, Pasadena, CA GEST/NASA Goddard Space Flight Center, Greenbelt, MD 11 University of Washington, Seattle, WA 12 NOAA/PMEL OCRD, Seattle, WA 10 9 IGAC/CACGP Atmospheric Chemistry Conference 18-25 September 2002 Hersonissos, Heraklion, Crete, GREECE

ACE-Asia 2001 3 Goals, greatest emphasis on first 2 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. 02/27/24 05:41 PM 2 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

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. I’ll show that assessment & then indicate what needs to be done to improve it. 02/27/24 05:41 PM 3 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

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.] 02/27/24 05:41 PM 4 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

AERONET--Beijing example from 13 sites in China, S. Korea, Taiwan, Japan Ångstrom Exponent Aerosol Optical Depth Beijing AOD & Ångstrom Exponent Daily Ave March - May 2001 1.5 3 2.5 2 1 Optical1.5 Depth Ångstrom Exponent 1 0.5 0.5 0 60 70 80 90 100 110 120 130 [Holben, Lu et al.] Day of Year 02/27/24 05:41 PM 0 140 5 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

AERONET--Beijing example from 13 sites in China, S. Korea, Taiwan, Japan Ångstrom Exponent Aerosol Optical Depth Beijing AOD & Ångstrom Exponent Daily Ave March - May 2001 1.5 3 0.4 Beijing, Ace Asia: March-May 2001 Volume Size Distribution 0.35 t 0.18 440 2.5 1 Optical1.5 Depth dV/dlnR ( m3/ m2) 2 ) 2 m m 3/ m m t 0.21 440 0.3 t 0.26 440 t 0.33 440 0.25 t440 0.42 t 0.50 440 t440 0.65 0.2 Ångstrom Exponent dV/dlnR ( 1 0.5 t 0.86 440 t440 1.39 0.15 0.1 0.05 0.5 0 60 70 80 90 100 110 120 130 0 0.01 0 140 0.1 1 10 Radius (( m) mm) Radius Day of Year [Holben, Lu et al.] 02/27/24 05:41 PM 6 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

AERONET--Beijing example from 13 sites in China, S. Korea, Taiwan, Japan Beijing SSA, March-May 2001 1 Ångstrom Exponent Aerosol Optical Depth Beijing AOD & Ångstrom Exponent Daily Ave March - May 2001 1.5 3 440 nm 870 nm Dust Episodes 0.95 2.5 2 0.9 1 Single Scattering Albedo Optical1.5 Depth Ångstrom Exponent 0.85 1 0.5 0.5 0 60 0.8 Urban aerosols 70 80 90 100 110 120 Day of Year 130 0 140 0.75 60 70 80 90 100 110 120 130 140 Day of Year [Holben, Lu et al.] 02/27/24 05:41 PM 7 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

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.] 02/27/24 05:41 PM 8 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

PAR Sensors, Yulin, China [M. Bergin & J. Xu] 02/27/24 05:41 PM 9 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Comparison of the Modeled (TUV(NCAR)) and Measured Downward PAR Values 500.00 450.00 -2 ) 400.00 350.00 Modeled PAR 0.98 Measured PAR 300.00 Modeled PAR (W m 2 R 0.95 250.00 200.00 200.00 250.00 300.00 350.00 Measured PAR (W m 400.00 -2 10 500.00 ) 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. 02/27/24 05:41 PM 450.00 [M. Bergin & J. Xu] P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Estimation of the 24-h Mean Aerosol Radiative Forcing Efficiency in Yulin 24-h mean aerosol radiative forcing, W m-2 10.00 -2 y 0.8x 2 R 0.92 0.00 y -3.4x 2 R 0.86 -10.00 )-20.00 (W m -30.00 y -27.0x 2 R 0.99 PAR(Surface) PAR(TOA) TSR(Surface) Daily-50.00 mean aerosol radiaitve forcing TSR(TOA) -40.00 y -49.2x 2 R 0.996 -60.00 0 0.2 0.4 0.6 0.8 1 1.2 Aerosol Optical Depth (500 nm) Calculated 24-h mean aerosol radiative forcing efficiency for PAR (400 – 700 nm) and total solar radiation (TSR, 0.2 – 4.0 m) 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). 02/27/24 05:41 PM 11 [M. Bergin & J. Xu] P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

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.] 02/27/24 05:41 PM 12 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Aerosol Optical Depth Measured by Solar Photometry Aboard RV Ron Brown Mar 26 Apr 5 H S e ac a o hij f J o to ap an Aerosol Optical Depth Mar 16 500 nm Apr 15 Se to a o Yo f J ko ap su an ka Hawaii to Hachijo Julian Day 02/27/24 05:41 PM 13 Markowicz, Flatau et al. P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

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.] 02/27/24 05:41 PM 14 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Aerosol Single-Scattering Albedo o (18 m asl, 330 nm, 55% RH) From in situ scattering & absorption aboard RV Ron Brown Single Scattering Albedo, D aero 10 m Marine Very Polluted Very Polluted with Dust [Quinn et al.] 02/27/24 05:41 PM 15 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

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.] 02/27/24 05:41 PM 16 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Longwave Radiance Measured by FTIR Aboard RV Ron Brown 10 m Vogelmann, Markowicz, Szczodrak, Flatau, Minnett 02/27/24 05:41 PM 17 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Aerosol Effect on Longwave Radiance from FTIR Measurements Aboard RV Ron Brown, April 9 10 μm W indow Longwave forcing Estimates: 2 to 9 W m-2 Flatau, Minnett, Szczodrak, Markowicz Vogelmann, Markowicz, Szczodrak, Flatau, Minnett 23 18 5/21/2001 1:13:32 02/27/24 05:41 PM AM Russell et al., AMS Radiation, June 4,2002 2002 P. Russell etP.al., IGAC/CACGP Atmos Chem,Ogden, Crete, UT, 18-25 Sep

ACE-Asia 2001 Aerosol-Radiation Interactions Measurements - Aircraft -- Vertical dependence of: AOD( ) [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( ) [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.] 19 02/27/24 05:41 PM P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Twin Otter research flight 11, April 17, 2001 33ºN 128ºE, West of Kyusyu Island 3500 FT 3000 2 10 2500 BL Boundary layer PL Pollution layer FT Free troposphere 2000 Altitude (m) 1500 Profile PL 4 2 ) 10 500 04:30 20 05:00 05:30 06:00 -3 3 6 BL Wang et al. [2002] 02/27/24 05:41 PM 6 1000 0 4Conc 4 06:30 UTC (Hours) P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002 (

Aerosol Optical Depth & Extinction Profiles From AATS-14 on Twin Otter, 4/17/2001 2.23.4 km 0.6-2.2 km 0.09-0.6 km Schmid et al. 02/27/24 05:41 PM 21 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Chemical Composition and size distributions, flight 11, April 17, 2001 Wang et al. [JGR 2002] 02/27/24 05:41 PM 22 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

3 -3 (cm ) o ( C) 1 2 3 45x10 0 15 λ 525 nm λ 1059 nm 3 3.0x10 RH T N 2.5 Predicted AATS-14 AATS-14 (averaged) 2.0 Altitude (m) 1.5 1.0 0.5 0.0 20 40 60 800 RH (%) 0.1 0.2 0 0.05 0.10 0.15 Aerosol Extinction (1/km) Wang, Schmid, et al. [JGR 2002] 02/27/24 05:41 PM 23 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

AATS-14 Predicted Averaged aersol extinction (1/km) 0.1 Free Troposphere 6 5 4 2 Pollution Layer 0.1 0. 0.1 8 6 Boundary Layer 4 4 Wang, Schmid, et al. [JGR 2002] 02/27/24 05:41 PM 5 6 7 8 λ(μm ) 1 24 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

ACE-Asia 2001 Aerosol-Radiation Interactions Measurements - Aircraft -- Vertical dependence of: AOD( ) [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( ) [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.] 02/27/24 05:41 PM 25 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

C-130 PBL AOD Comparison AOD from Neph PSAP 550 nm AOD from AATS-6 Airborne Sunphotometer 02/27/24 05:41 PM 26 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

ACE-Asia 2001 Aerosol-Radiation Interactions Measurements - Aircraft -- Vertical dependence of: AOD( ) [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( ) [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.] 02/27/24 05:41 PM 27 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Downwelling Flux: F 2000 m 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 02/27/24 05:41 PM 28 43 m P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Pilewskie, Bergstrom, Schmid et 02/27/24 05:41 PM 29 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Aerosol Single Scattering Albedo Spectrum Single scattering albedo Derived from measured flux and AOD spectra 02/27/24 05:41 PM Wavelength, nm 30 Bergstrom, Pilewskie, Schmid et al. P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

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.] 02/27/24 05:41 PM 31 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

12 Apr 2001 SeaWiFS Project NASA/GSFC ORBIMAGE 02/27/24 05:41 PM 32 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

SeaWiFS Aerosol Optical Depth 510 nm AATS-14 on Twin Otter N. C. Hsu, UMBC/NASA 02/27/24 05:41 PM 33 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Schmid, Hsu et al. 02/27/24 05:41 PM 34 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Regional Assessment of Aerosol Radiative Forcing North Pacific, 20 -55 N Needs a( ,x,y,z,t) a( ,x,y,z,t) a( ,x,y,z,t) As( ,x,y, 0) 02/27/24 05:41 PM Approach 35 Combine Satellite and Suborbital Data P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Regional Assessment of Aerosol Shortwave Radiative Forcing North Pacific, 20 -55 N Suborbital (ACE-Asia) Satellite: a(865 nm,x,y,t) 0 a( )/ a(865 nm): Models constr. by Sat. & Sunphot. a(z): A/C, Lidar Meas (dust above pollution) a(z, ): A/C Meas, Models a( 0): Size distributions: sunphot & in situ meas As( 0): models 0.2 0.4 0.6 0.8 SeaWiFS, April 2001 C. Hsu retrieval 02/27/24 05:41 PM 36 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Aerosol Vertical Profiles Assumed for Forcing Calculations dust / poll adjusted to make model SeaWiFS 02/27/24 05:41 PM 37 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Calculated Aerosol Shortwave Forcing vs Optical Depth Flux change, W m-2 Fnet, TOA Ratio, F , Surface F , Surface Fnet, TOA 2 to 3 Dust Over ocean, 24-h avg April, 34 N, No clouds Pollution Larger over land Aerosol Optical Depth at 550 nm 02/27/24 05:41 PM 38 [Bergstrom] P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Regional Assessment of Aerosol Shortwave Radiative Forcing North Pacific, 20 -55 N Satellite Suborbital: Satellite: 0 0 0.2 0.4 0.6 0.8 -40 -60 Downward Flux Change at Surface (W m-2) SeaWiFS a(865 nm) April 2001, C. Hsu retrieval 02/27/24 05:41 PM -20 24-h avg, dust ( a 0.95) over pollution ( a 0.90), no clouds. 39 [Bergstrom] P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Conclusions This sampling of results indicates how ACE-Asia’s 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., 100 titles listed for JGR special section. Much remains to be done--What’s most important? 02/27/24 05:41 PM 40 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

What’s Next? Continued analyses of suborbital data (including closure tests) to reduce error bars on aerosol intensive radiative properties [SSA( ), g( )]: -- 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( ), g( ), aerosol type, SSA( ) Continued tests of CTMs, especially vertical distributions by aerosol type 02/27/24 05:41 PM 41 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

What’s Next? (cont’d) 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, ) more accurately, using ship measurements Aerosol indirect effects 02/27/24 05:41 PM 42 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

550 nm 02/27/24 05:41 PM 43 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

550 nm 02/27/24 05:41 PM 44 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

550 nm 02/27/24 05:41 PM 45 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Aerosol type analysis with SeaWiFS data APEX, ACE-Asia 15 April 2001 TOMS Aerosol Index by Hsu, N. C. (NASA/GSFC) (http://hyperion.gsfc.nasa.gov /Mission/ACEASIA/satellite) 02/27/24 05:41 PM 46 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Monthly mean aerosol type classfication by SeaWiFS Higurashi (2001) 02/27/24 05:41 PM 47 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

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] 02/27/24 05:41 PM 48 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Dust events of 10 and 11-16 April at Amami S. Ohta [2001] 02/27/24 05:41 PM 49 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

13 Apr 2001 02:42 & 04:49 UTC? SeaWiFS Project NASA/GSFC ORBIMAGE http://visibleearth.nasa.gov/cgi-bin/viewrecord?7924 02/27/24 05:41 PM 50 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

02/27/24 05:41 PM 51 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

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 02/27/24 05:41 PM 52 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Boundary layer Pollution layer Free trop layer Schmid, Wang, Hegg et al. [2001] 02/27/24 05:41 PM 53 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Regional Assessment of Aerosol Shortwave Radiative Forcing North Pacific, 20 -55 N Satellite: 0 0.08 0.20 0.32 0.45 0 0.2 0.4 0.6 0.8 SeaWiFS a(865 nm) April 2001, Std retrieval 02/27/24 05:41 PM SeaWiFS a(865 nm) April 2001, C. Hsu retrieval 54 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Regional Assessment of Aerosol Shortwave Radiative Forcing North Pacific, 20 -55 N Satellite Suborbital: Satellite: 0 0.2 0.4 0.6 0.8 0 -40 -60 Downward Flux Change at Surface (W m-2) SeaWiFS a(865 nm) April 2001, C. Hsu retrieval 02/27/24 05:41 PM -20 24-h avg, dust ( a 0.95) over pollution ( a 0.90), no clouds. 55 [Bergstrom] P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

Regional Assessment of Aerosol Shortwave Radiative Forcing North Pacific, 20 -55 N Old ( ( dust / / poll 1) : 0 -20 -40 New ( ( dust / / poll from SeaWiFS -60 0 Downward Flux Change at Surface (W m ) -2 -20 -40 -60 Downward Flux Change at Surface (W m-2) 24-h avg, dust ( a 0.95) over pollution ( a 0.90), no clouds. [Bergstrom, Hsu et al.] 02/27/24 05:41 PM 56 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002

April 2001 Monthly Average Optical Depth & Angstrom Exponent from SeaWiFS North Pacific, 20 -55 N Angstrom Exponent a(865 nm) 0 0.2 0.4 0.6 0.8 0 0.4 0.8 1.2 [C. Hsu] 02/27/24 05:41 PM 57 P. Russell et al., IGAC/CACGP Atmos Chem, Crete, 18-25 Sep 2002