Vertical Profiles of Aerosol Parameters from Inversion of Airborne Multiwavelength High-Spectral-Resolution Lidar Data During TCAP
Abstract
The first intensive observational period of the Two-Column Aerosol Project (TCAP) field campaign was carried out on Cape Cod, Massachusetts from 7 - 29 July 2012. The ARM Mobile Facility (AMF) and the Mobile Aerosol Observing System (MAOS) measured aerosol properties, radiation, and cloud characteristics on Cape Cod. Two aircraft were deployed during the intensive observational period. The first aircraft was equipped with a suite of in situ instrumentation to provide measurements of aerosol optical properties, particle composition and direct-beam irradiance. The second aircraft flew directly over the first aircraft. This second aircraft flew the world's first airborne 3 backscatter - 2 extinction High-Spectral-Resolution Lidar (HSRL) and a Research Scanning Polarimeter (RSP) to provide continuous aerosol and cloud properties in the column below. The multiwavelength HSRL was built and deployed by NASA Langley Research Center. The RSP was developed by NASA GISS. The measurements were characterized by periods of comparatively high optical depth resulting from the transport of polluted air out over the North Atlantic Ocean. Urban haze was advected from the east coast of the US and Canada. Forest fires in Canada likely injected smoke into the air which was detected by the lidar system after a comparably short transport time of one or two days. In this contribution we present for the first time vertical profiles of aerosol optical and microphysical properties inferred from a newly developed automated and unsupervised data inversion algorithm. This algorithm processes the profiles of the backscatter and extinction coefficients measured with this novel multiwavelength HSRL. The lidar system provides us with the measured optical extensive properties, i.e. particle backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm (i.e. '3+2'). From the extinction and backscatter coefficients we obtain the particle intensive properties, i.e., extinction-to-backscatter (lidar) ratios, backscatter-related Angstrom exponents and extinction-related Angstrom exponents. The depolarization ratio is measured at 532 nm. The inversion of the profiles of the optical data provides us with profiles of particle effective radius and integral properties of the particle size distribution (number, surface-area and volume concentration) and complex refractive index. From this information we compute additional optical properties, e.g. profiles of single-scattering albedo, scattering and absorption. We present initial results of these parameters retrievals for some of the pollution cases observed during TCAP.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.A33A0121M
- Keywords:
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- 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE / Aerosols and particles;
- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: composition and chemistry;
- 0394 ATMOSPHERIC COMPOSITION AND STRUCTURE / Instruments and techniques