Aerosol Optical Depth Analysis with NOAA Goes and Poes in the Western Atlantic

Download or read book Aerosol Optical Depth Analysis with NOAA Goes and Poes in the Western Atlantic written by Arunas P. Kuciauskas and published by . This book was released on 2002-06-01 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: An aerosol optical depth retrieval algorithm in the visible wavelengths for the NOAA POES AVHRR and GOES-8 visible imager is presented for the cloud free, marine atmosphere. The algorithm combines linearized single- scatter theory with an estimate of surface reflectance. Phase functions are parameterized using an aerosol size distribution model and the ratio of radiance values measured in channels 1 and 2 of the AVHRR. Retrieved satellite aerosol optical depth (AOD) is compared to three land-based sun photometer stations located on islands in the western Atlantic during July and September, 2001. GOES-8 channel 1 (visible wavelength) radiance values were initially calibrated using techniques developed by Rao. Additional connections to the channel 1 GOES- 8 radiances were made by applying a linear offset factor obtained during the experimental time period through comparison with AVHRR radiances. The results for the GOES -derived AOD compare favorably to the AERONET-measured AOD values. For both NOAA and GOES data, the comparison dataset has a correlation coefficient of 0.67 with a standard error of 0.07. For higher AOD cases (d = 0. 25), the general trend was for the satellite-derived AOD values to underestimate AERONET-observed conditions. During these higher conditions, the scattering phase function pattern contained within the algorithm deviated from the expected pattern, especially between 1400 1800. Overall, the more accurate calculations of AOD occurred over scatter angles between 140 deg - 150 deg and 170 deg - 180 deg.