Clear-column closure studies of lower tropospheric aerosol extinction during ACE-Asia using airborne sunphotometer, airborne in-situ and ship-based lidar measurements Beat Schmid et al. NASA Ames/BAER Institute, Sonoma, CA

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Clear-column closure studies of lower
tropospheric aerosol extinction during ACE-Asia
using airborne sunphotometer, airborne in-situ
and ship-based lidar measurementsBeat Schmid et
al. NASA Ames/BAER Institute, Sonoma, CA
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Co-authors
Hegg, D, Covert, D, Univ. of Washington,
Atmospheric Sciences, WA Redemann, J, Bay Area
Environmental Research, Institute, Sonoma, CA
Livingston, J , SRI, International, Menlo Park,
CA Russell P, NASA, Ames Research Institute,
Moffett Field, CA Wang, J, Flagan, R, Seinfeld,
J, California Institute of Technology, Pasadena,
CA Bates, D, University of, Miami, Coral Gables,
FL Jonsson, H, CIRPAS, Marina, CA Welton, E,
GEST/UMBC, NASA Goddard Space Flight Center,
Greenbelt, MD
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NASA Ames Airborne Sunphotometers (AATS)
AOD and H2O
AATS-6
AATS-14
(350-1558 nm)
(380-1020 nm)
C-130
Twin Otter
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AATS vertical profiles during ACE-Asia
l AATS-14 l AATS-6
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In situ measurement of Extinction

• Absorption
• Particle Soot Absorption Photometer (PSAP,
  ?550nm)
• noisy (averaging)
• low RH
• Corrections (Bond et al., 1999)
• scattering contribution
• inlet-cutoff (Da8?m)
• correct to ambient RH

• Scattering
• Nephelometers
• TSI ? 450, 550, 700 nm,
  low RH
• RR ? 550 nm,
  RH20,60,85
• Corrections (AndersonOgren, 1998)
• light source
• angular truncation (7-170)
• inlet-cutoff (Da8?m)
• correct to ambient RH

correction not required or done
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Extinction the hard way Compute from in situ
measurement of size distribution and composition
Wang et al. 2002, JGR (in press)

• Twin DMA, D 15 - 1000 nm (close to ambient RH)
• Aerodynamic Particle Sizer, D 0.5 - 8 mm (drier
  than ambient RH),
• adjust to ambient RH
• compute extinction, needs m

needs composition
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Chemical Composition and size distributions,
flight 11, April 17, 2001
Wang et al. 2002
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Extinction closure between AATS-14 and NephPSAP
for 14 profiles
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H2O closure between AATS-14 and in-situ for 26
profiles
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How well did past campaigns do on AATS vs
NephPSAP comparisons?
U.S. East Coast, 1996 (Hegg et
al., 1997, Hartley et al., 2000)
Eastern Asia, 2001 C-130 Redemann et al., 2003
Twin Otter Schmid et al., 2003
Canary Islands, 1997 (Schmid et al., 2000)
U.S. East Coast, 2001 Hobbs
et al., (in preparation)
Southern Africa (Magi et al., 2002)