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In-Situ Measurements of Aerosol Optical Properties using New Cavity Ring-Down and Photoacoustics Instruments and Comparison with more Traditional TechniquesCarbonaceous species (BC and OC) are responsible for most of the absorption associated with aerosol particles. The amount of radiant energy an aerosol absorbs has profound effects on climate and air quality. It is ironic that aerosol absorption coefficient is one of the most difficult aerosol properties to measure. A new cavity ring-down (CRD) instrument, called Cadenza (NASA-ARC), measures the aerosol extinction coefficient for 675 nm and 1550 nm light, and simultaneously measures the scattering coefficient at 675 nm. Absorption coefficient is obtained from the difference of measured extinction and scattering within the instrument. Aerosol absorption coefficient is also measured by a photoacoustic (PA) instrument (DRI) that was operated on an aircraft for the first time during the DOE Aerosol Intensive Operating Period (IOP). This paper will report on measurements made with this new instrument and other in-situ instruments during two field recent field studies. The first field study was an airborne cam;oaign, the DOE Aerosol Intensive Operating Period flown in May, 2003 over northern Oklahoma. One of the main purposes of the IOP was to assess our ability to measure extinction and absorption coefficient in situ. This paper compares measurements of these aerosol optical properties made by the CRD, PA, nephelometer, and Particle Soot Absorption Photometer (PSAP) aboard the CIRPAS Twin-Otter. During the IOP, several significant aerosol layers were sampled aloft. These layers are identified in the remote (AATS-14) as well as in situ measurements. Extinction profiles measured by Cadenza are compared to those derived from the Ames Airborne Tracking Sunphotometer (AATS-14, NASA-ARC). The regional radiative impact of these layers is assessed by using the measured aerosol optical properties in a radiative transfer model. The second study was conducted in the Caldecott Tunnel, a heavily-used tunnel located north of San Francisco, Ca. The aerosol sampled in this study was characterized by fresh automobile and diesel exhaust. Measurements from Cadenza and from an aethalometer are presented. The aethalometer is a filter-based photometer and the infrared channel is calibrated to produce a measure of BC mass loading.
Document ID
20040161169
Document Type
Conference Paper
Authors
Strawa, A. W. (NASA Langley Research Center Hampton, VA, United States)
Arnott, P. (Desert Research Inst. Reno, NV, United States)
Covert, D. (Washington Univ. Seattle, WA, United States)
Elleman, R. (Washington Univ. Seattle, WA, United States)
Ferrare, R. (NASA Langley Research Center Hampton, VA, United States)
Hallar, A. G. (NASA Langley Research Center Hampton, VA, United States)
Jonsson, H. (Center for Interdisciplinary Remotely-Piloted Aircraft Studies Marina, CA, United States)
Kirchstetter, T. W. (California Univ., Lawrence Berkeley National Lab. Berkeley, CA, United States)
Luu, A. P. (San Jose State Univ. CA, United States)
Ogren, J. (National Oceanic and Atmospheric Administration Boulder, CO, United States)
Date Acquired
August 22, 2013
Publication Date
January 1, 2004
Subject Category
Instrumentation and Photography
Meeting Information
8th International Conference on Carbonaceous Particles in the Atmosphere(Vienna)
Distribution Limits
Public
Copyright
Other