how well can we measure the vertical profile of tropospheric aerosol extinction?

aerosol extinction? B. Schmid 1 , R. Ferrare 2 , C. Flynn 3 , R. Elleman 4 , D. Covert 4 , A. Strawa 5 , E. Welton 6 , D. Turner 3 , H. Jonsson 7 , J. Redemann 1 , J. Eilers 5 , K. Ricci 8 , A. Hallar 5 , M. Clayton 9 , J. Michalsky 10 , A. Smirnov 11 , B. Holben 6 , J. Barnard 3 1 Bay Area Environmental Research Institute, Sonoma, CA 2 NASA Langley Research Center, Hampton, VA 3 Pacific Northwest National Laboratory, Richland, WA 4 University of Washington, Seattle, WA 5 NASA Ames Research Center, Moffett Field, CA 6 NASA GSFC, Greenbelt, MD 7 Center for Interdisciplinary Remotely-Piloted Aircraft Studies, Marina, CA 8 Los Gatos Research Inc., Mountain View, CA 9 SAIC/NASA Langley Research Center, Hampton, VA 10 NOAA/ARL, Boulder, CO 11 GEST/UMBC/ NASA GSFC, Greenbelt, MD Goal We assess the accuracy with which the vertical profile of aerosol extinction (a fundamental aerosol property) can currently be measured with state-of-the art instrumentation. We cannot stress enough that for climate considerations it is the properties of the unaltered aerosol at its ambient concentration and thermodynamic state that are of interest. We compare ambient aerosol extinction profiles obtained in coordinated field campaigns that include in situ and remote sensing measurements of aerosols aboard airborne platforms over surface- based lidars. We start with the results of a recent campaign, the Department of Energy Atmospheric Radiation Measurement (ARM) Aerosol Intensive Operations Period (AIOP, May 2003), and then consider these results in the context of findings from other field campaigns conducted since 1996. Conclusion While we find that each of the methods investigated here has its strengths and weaknesses, there is no definitive proof that one of the methods is fundamentally flawed. From the biases found in AIOP and previous studies, we conclude that the systematic error associated with measuring the tropospheric vertical profile of the ambient aerosol extinction with current state-of-the art instrumentation is 15- 20% at visible wavelengths and potentially larger in the UV and near-infrared. Random errors, as measured by rms differences are considerably larger, ranging from 26% to 98%. How did we measure the vertical profile of aerosol extinction during AIOP? Sum m ary ofA IO P Extinction C om parisons R am an Neph+PSAP M PLNET C adenza C adenza Neph+PSAP M PLARM Neph+PSAP -50% -40% -30% -20% -10% 0% 10% 20% 30% 40% 50% R el.B ias to A A TS-14 = 354 nm = 453 nm = 519 nm = 675 nm = 1550 nm Extinction comparisons in previous field campaigns TARFOX, 1996 ACE-2, 1997 PRIDE, 2000 SAFARI, 2000 ACE-Asia, 2001 ARM Aerosol IOP, 2003 CLAMS, 2001 x y # proﬁles # data points AATS-14 N eph+P S A P 26 3484 AATS-14 C adenza 26 2856 AATS-14 M P LN E T 2.0 13 587 AATS-14 M P LA R M 19 2073 AATS-14 R am an Lidar 11 468 AATS-14 in-situ H 2O 35 6705 Focus on data obtained in vertical profiles over SGP CF Altitudes: ~90 – 5600 m CIRPAS Twin Otter AATS-14 AATS-14 on UW CV-580 AATS-14 on CIRPAS Pelican AATS-6 SPAWAR Navajo UW C-131A NCAR C-130 Future SGP Lidar Validation IOP An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP leading to a significant bias in derived aerosol extinction. The Raman lidar has recently been restored/upgraded. Therefore the ARM Aerosol Working group is proposing further validation using AATS-14 aboard a profiling aircraft (~20 flight hours, profiles 300 – 23,000 ft altitude, ~Sep 2005). AATS-14 on Sky Research J-31 Photo courtesy Yin-Nan Lee, BNL Airborne: • Nephelometer+PSAP • Cavity-Ring-Down (Cadenza) • Sunphotometry (AATS- 14) Ground based: • Raman Lidar (CARL) • MPLNET • MPLARM 0 1 2 3 4 5 6 0 0.1 0.2 0.3 A erosolExtinction (1/km ) A ltitude (km ) N eph+PSAP (453 nm )18:34-18:52 U T May 27, 2003

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Extinction comparisons in previous field campaigns. May 27, 2003. TARFOX, 1996. ACE-Asia, 2001. CLAMS, 2001. Airborne: Nephelometer+PSAP Cavity-Ring-Down (Cadenza) Sunphotometry (AATS-14). ACE-2, 1997. ARM Aerosol IOP, 2003. PRIDE, 2000. Ground based: Raman Lidar (CARL) - PowerPoint PPT Presentation

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How well can we measure the vertical profile of tropospheric aerosol extinction?

B. Schmid1, R. Ferrare2, C. Flynn3, R. Elleman4, D. Covert4, A. Strawa5, E. Welton6, D. Turner3, H. Jonsson7, J. Redemann1, J. Eilers5, K. Ricci8, A. Hallar5, M. Clayton9, J. Michalsky10, A. Smirnov11, B. Holben6, J. Barnard3

1Bay Area Environmental Research Institute, Sonoma, CA 2NASA Langley Research Center, Hampton, VA 3Pacific Northwest National Laboratory, Richland, WA4University of Washington, Seattle, WA 5NASA Ames Research Center, Moffett Field, CA 6NASA GSFC, Greenbelt, MD 7Center for Interdisciplinary Remotely-Piloted Aircraft Studies, Marina, CA

8Los Gatos Research Inc., Mountain View, CA 9SAIC/NASA Langley Research Center, Hampton, VA 10NOAA/ARL, Boulder, CO 11GEST/UMBC/ NASA GSFC, Greenbelt, MD

Goal

We assess the accuracy with which the vertical profile of aerosol extinction (a fundamental aerosol property) can currently be measured with state-of-the art instrumentation.

We cannot stress enough that for climate considerations it is the properties of the unaltered aerosol at its ambient concentration and thermodynamic state that are of interest.

We compare ambient aerosol extinction profiles obtained in coordinated field campaigns that include in situ and remote sensing measurements of aerosols aboard airborne platforms over surface-based lidars.

We start with the results of a recent campaign, the Department of Energy Atmospheric Radiation Measurement (ARM) Aerosol Intensive Operations Period (AIOP, May 2003), and then consider these results in the context of findings from other field campaigns conducted since 1996.

Conclusion

While we find that each of the methods investigated here has its strengths and weaknesses, there is no definitive proof that one of the methods is fundamentally flawed. From the biases found in AIOP and previous studies, we conclude that the systematic error associated with measuring the tropospheric vertical profile of the ambient aerosol extinction with current state-of-the art instrumentation is 15-20% at visible wavelengths and potentially larger in the UV and near-infrared. Random errors, as measured by rms differences are considerably larger, ranging from 26% to 98%.

How did we measure the vertical profile of aerosol extinction during AIOP?

Summary of AIOP Extinction ComparisonsRaman

Neph+PSAP

MPLNET

Cadenza

CadenzaNeph+PSAP

MPLARM

Neph+PSAP

-50%

-40%

-30%

-20%

-10%

10%

20%

30%

40%

50%

l. B

ias

-14

= 354 nm

= 453 nm

= 519 nm

= 675 nm = 1550 nm

Extinction comparisons in previous field campaigns

TARFOX, 1996

ACE-2, 1997

PRIDE, 2000

SAFARI, 2000

ACE-Asia, 2001

ARM Aerosol IOP, 2003

CLAMS, 2001

x y # profiles # data points

AATS-14 Neph+PSAP 26 3484AATS-14 Cadenza 26 2856

AATS-14 MPLNET 2.0 13 587AATS-14 MPLARM 19 2073

AATS-14 Raman Lidar 11 468

AATS-14 in-situ H2O 35 6705

Focus on data obtained in vertical profiles over SGP CF Altitudes: ~90 – 5600 m

CIRPAS Twin Otter

AATS-14

AATS-14 on UW CV-580 AATS-14 on CIRPAS Pelican

AATS-6

SPAWAR Navajo

UW C-131A

NCAR C-130

Future SGP Lidar Validation IOP

An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP leading to a significant bias in derived aerosol extinction. The Raman lidar has recently been restored/upgraded. Therefore the ARM Aerosol Working group is proposing further validation using AATS-14 aboard a profiling aircraft (~20 flight hours, profiles 300 – 23,000 ft altitude, ~Sep 2005).

AATS-14 on Sky Research J-31

Photo courtesy Yin-Nan Lee, BNL

Airborne:• Nephelometer+PSAP• Cavity-Ring-Down (Cadenza) • Sunphotometry (AATS-14)

Ground based:• Raman Lidar (CARL)• MPLNET• MPLARM

0 0.1 0.2 0.3

Aerosol Extinction (1/km)

Alt

itu

(km

)

Neph+PSAP (453 nm) 18:34-18:52 UT

May 27, 2003