Evaluation and comparison of multiangle implementation of the atmospheric correction algorithm, Dark Target, and Deep Blue aerosol products over China

摘要

A new multiangle implementation of the atmospheric correction (MAIAC)algorithm has been applied in the Moderate Resolution ImagingSpectroradiometer (MODIS) sensor and has recently provided globally high-spatial-resolution aerosol optical depth (AOD) products at 1 km. Moreover,several improvements have been modified in the classical Dark Target (DT) andDeep Blue (DB) aerosol retrieval algorithms in MODIS Collection 6.1 products.Thus, validation and comparison of the MAIAC, DT, and DB algorithms are urgentin China. In this paper, we present a comprehensive assessment and comparisonof AOD products at a 550 nm wavelength based on three aerosol retrievalalgorithms in the MODIS sensor using ground-truth measurements from AErosolRObotic NETwork (AERONET) sites over China from 2000 to 2017. In general,MAIAC products achieved better accuracy than DT and DB products in theoverall validation and accuracy improvement of DB products after the QAfilter, demonstrating the highest values among the three products. Inaddition, the DT algorithms had higher aerosol retrievals in cropland,forest, and ocean land types than the other two products, and the MAIACalgorithms were more accurate in grassland, built-up, unoccupied, andmixed land types among the three products. In the geometry dependencyanalysis, the solar zenith angle, scattering angle, and relative azimuthangle, excluding the view zenith angle, significantly affected theperformance of the three aerosol retrieval algorithms. The three productsshowed different accuracies with varying regions and seasons. Similar spatialpatterns were found for the three products, but the MAIAC retrievals weresmaller in the North China Plain and higher in Yunnan Province compared withthe DT and DB retrievals before the QA filter. After the QA filter, the DBretrievals were significantly lower than the MAIAC retrievals in south China.Moreover, the spatiotemporal completeness of the MAIAC product was alsobetter than the DT and DB products.