HR: 0830h
AN: A21A-20    [Abstracts]
TI: Geographical variability of fine and coarse mode aerosol properties derived from MFRSR datasets
AU: * Alexandrov, M
EM: malexandrov@giss.nasa.gov
AF: Columbia University, 2880 Broadway, New York, NY 10025 United States
AU: * Alexandrov, M
EM: malexandrov@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 United States
AU: Carlson, B E
EM: bcarlson@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 United States
AU: Lacis, A A
EM: alacis@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 United States
AU: Cairns, B
EM: bcairns@giss.nasa.gov
AF: Columbia University, 2880 Broadway, New York, NY 10025 United States
AU: Cairns, B
EM: bcairns@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 United States
AB: A new version of data analysis algorithm for Multi-Filter Rotating Shadowband Radiometer (MFRSR) was applied to several long-term datasets to study seasonal and geographical variability of aerosol parameters. In distinction from our older method that used a monomodal aerosol size distribution, the new algorithm allows us to partition the aerosol optical thickness into fine and coarse modes. In addition we retrieve the fine mode effective radius and Angstrom exponent. A bimodal gamma distribution is used to model the aerosol particle size distribution. Development of an automated cloud screening procedure based on optical thickness variability analysis allows us to make the data processing more objective and fully automatic. The algorithm has been applied to a multi-year dataset from the local MFRSR network at the DOE Atmospheric Radiation Measurement (ARM) Program site in Southern Great Plains (SGP). Our retrieved aerosol optical thicknesses (total, fine, and coarse) are compared with AERONET almucantar retrieval results derived from a CIMEL sunphotometer co-located with the MFRSR at the SGP Central Facility. A constrained variant of the algorithm (zero nitrogen dioxide column amount) has been used to demonstrate the range of physically viable values of the fine mode effective radius, and for comparison with AERONET retrievals of particle size. A correspondence has been found between the geographical variation in the fine mode particle size and aerosol composition (nitrates vs. sulfates) as measured by National Atmospheric Deposition Program. Comparison with sampling measurements performed at the SGP's Central Facility by NOAA Pacific Marine Environmental Laboratory (PMEL) also showed correspondence in temporal (both seasonal and day-to-day) variability between our fine mode size and nitrate/sulfate ion mass concentration ratios.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0360 Transmission and scattering of radiation
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly