Retrieval of Aerosol Properties from Multispectral Direct Sun Measurements.

摘要

From measurements, made with a new sunphotometer, the multispectral aerosol optical thickness has been derived. This has been done by using the Langley method. An algorithm has been developed for the automatic removal of data points taken during unstable atmospheric conditions between July and November 1997 the aerosol optical thickness has been determined. The aerosol optical thickness appeared most of the time to be higher in summer than in autumn. To derive the aerosol optical thickness for unstable atmospheric conditions, an accurate calibration of the sunphotometer is needed. This can be done by the Langley method but more Langley plots are needed for this than are available now. From the multispectral measurements of the aerosol optical thickness the aerosol size distribution has been retrieved using a constrained linear inversion method. The inversion algorithm was first applied to simulated data of the aerosol optical thickness to find optimal setting for parameters used in the inversion and to obtain insight in the accuracy of the inversion algorithm.