A31C-3048:
Vertical Profiles of Light-Absorbing Aerosol: A Combination of In-situ and AERONET Observations during NASA DISCOVER-AQ

Wednesday, 17 December 2014
Luke D Ziemba1, Andreas Joel Beyersdorf1, Gao Chen2, Chelsea Corr3, Suzanne Crumeyrolle4, David Matthew Giles5, Brent N Holben6, Charles Hudgins1, Robert Martin1, Richard Moore1, Michael Shook1, Kenneth Lee Thornhill II7, Edward Winstead7 and Bruce E Anderson1, (1)NASA Langley Research Center, Hampton, VA, United States, (2)NASA Langley Research Ctr, Hampton, VA, United States, (3)Oak Ridge Associated Universities Inc., Oak Ridge, TN, United States, (4)Laboratoire d'Optique Atmosphérique (Lille), Villeneuve, France, (5)NASA Goddard SFC, Greenbelt, MD, United States, (6)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (7)Science Systems and Applications, Inc. Hampton, Hampton, VA, United States
Abstract:
Understanding the vertical profile of atmospheric aerosols plays a vital role in utilizing spaceborne, column-integrated satellite observations. The properties and distribution of light-absorbing aerosol are particularly uncertain despite significant air quality and climate ramifications. Advanced retrieval algorithms are able to derive complex aerosol properties (e.g., wavelength-dependent absorption coefficient and single scattering albedo) from remote-sensing measurements, but quantitative relationships to surface conditions remain a challenge. Highly systematic atmospheric profiling during four unique deployments for the NASA DISCOVER-AQ project (Baltimore, MD, 2011; San Joaquin Valley, CA, 2013; Houston, TX, 2013; Denver, CO, 2014) allow statistical assessment of spatial, temporal, and source-related variability for light-absorbing aerosol properties in these distinct regions. In-situ sampling in conjunction with a dense network of AERONET sensors also allows evaluation of the sensitivity, limitations, and advantages of remote-sensing data products over a wide range of conditions.

In-situ aerosol and gas-phase observations were made during DISCOVER-AQ aboard the NASA P-3B aircraft. Aerosol absorption coefficients were measured by a Particle Soot Absorption Photometer (PSAP). Approximately 200 profiles for each of the four deployments were obtained, from the surface (25-300m altitude) to 5 km, and are used to calculate absorption aerosol optical depths (AAODs). These are quantitatively compared to AAOD derived from AERONET Level 1.5 retrievals to 1) explore discrepancies between measurements, 2) quantify the fraction of AAOD that exists directly at the surface and is often missed by airborne sampling, and 3) evaluate the potential for deriving ground-level black carbon (BC) concentrations for air quality prediction. Aerosol size distributions are used to assess absorption contributions from mineral dust, both at the surface and aloft. SP2 (Single Particle Soot Photometer) mixing state and coating thickness analyses will be explored to explain in-situ/AERONET discrepancies, and ground-based absorption coefficient and BC-mass observations will be utilized whenever possible to fully obtain the true absorption vertical profile.