Sun-Photometer Observations of Aerosol Optical Thickness over the North Atlantic from a Soviet Research Vessel for Validation of Satellite Measurements

Abstract

This paper deals with the problem of aerosol optical thickness (τA) retrieval using sun-photometer measurements. The results of the theoretical analysis and computer processing of the dataset collected during the 40th cruise of the R/V Akademik Vernadsky are presented. Accuracy of retrieved τA is investigated in detail. It is concluded that 1) the τA measurements from the three shortest wavelength channels are sufficiently accurate (0.02?0.03) for evaluation of the NOAA Advanced Very High Resolution Radiometer aerosol optical thickness operational product; 2) serious discrepancies exist between observation and theory for the two longest wavelength channels, which preclude their use in aerosol optical property studies. Further investigations are required, with emphasis on the computation of atmospheric gaseous absorption, before these channels can be used. Shipboard τA will be compared with satellite data from the NOAA/National Environment Satellite Data and Information Service in a subsequent paper.