Study On Quick Determination Method Of Aerosol Type Based On Multiband Aerosol Optical Depth

Atmospheric aerosols can directly affect the Earth's radiation energy transmission, climate change, air quality and quantitative remote sensing.Aerosol type determination plays a vital role in the study of aerosol optical properties, especially for high-accuracy aerosol optical depth(AOD) retrieval. Considering limitations of conventional AOD retrieval methods and difficulties of current study, this paper proposes a method to determine aerosol type using multi-band AOD data. AOD data at 440 ?m,670 ?m, 870 ?m and 1020 ?m are used to determine the aerosol particle quantities and volume percentage of dust aerosol, water soluble aerosol and soot aerosol, that is, to determine aerosol types. Primary researches are as follows:(1) Principles and methods in aerosol type determination.Combining with Mie scattering theory and analysis of physical and optical properties of atmospheric particulate matter, parameters such as scale distribution and extinction efficiency are determined; besides, the relationship between the quantities of different aerosol particles and the multi-bands optical thickness is analyzed based on AOD expressions, in order to select suitable principles. AOD obtained from 440 ?m, 670 pm,870 ?m and 102?m are applied to determine aerosol types, in the meantime, the proportion of each aerosol particle quantities to the whole quantities and the AOD proportion of each band to the whole four bands are used to identify mutual relationships. Based on which, the look-up table (LUT) of the aerosol type is constructed by the forward simulation.Simultaneously, the transformation calculation from aerosol particle quantities proportion to volume proportion is also studied for the application in radiation transfer computation.(2) The LUT is analyzed in view of radiation transfer computation.The influence of particle quantities proportion error on volume proportion is researched according to their transform relation. In accord with application error requirements, relevant constraints were set to determine the range, interval segmentation, and step size, considering different combinations of aerosols. The LUT is finally constructed via multi-band AOD data, and is simplified to improve the efficiency of LUT search and algorithm speed under the guarantee of accuracy.(3) To evaluate this method, simulated multi-bands AOD data is applied to carry out validation, stability analysis and error analysis experiments, showing a high accuracy of this method. Wherein, the RMB,MAE, MRE and RMSE in the accuracy validation indicate high precision;and the error analysis reveals that AOD accuracy has great influence on aerosol type determination. In general, the proposed method can determine aerosol particle quantities of dust aerosol, water-soluble aerosol and soot aerosol with high accuracy, which can be used to determine aerosol types.