Abstract
Land surface reflectance (LSR) and aerosol types are the two main factors that affect aerosol inversions over land. According to LSR determination methods, Moderate resolution Imaging Spectroradiometer (MODIS) aerosol products are produced using the Deep Blue (DB) and Dark Target (DT) algorithms. Five aerosol types that are determined from Aerosol Robotic Network (AERONET) ground measurements are used to describe the global distribution of aerosol types in each algorithm. To assess the influence of LSR and the method used to determine aerosol type from aerosol retrievals, 10-km global aerosol products that cover 2013 are selected for validation using Level 2.0 aerosol observations from 175 AERONET sites. The variations in the retrieval accuracy of the DB and DT algorithms for different LSR values are analyzed by combining them with a global 10-km LSR database. Meanwhile, the adaptability of the MODIS products over areas covered with different aerosols is also explored. The results are as follows. (1) Compared with DT retrievals, the DB algorithm yields lower root mean squared error (RMSE) and mean absolut error (MAE) values, and a greater number of appropriate sample points fall within the expected error (EE). The DB algorithm shows higher overall reliability; (2) The aerosol retrieval accuracy of the DB and DT algorithms decline irregularly as the surface reflectance increases; the DB algorithm displays relatively high accuracy; (3) Both algorithms have a high retrieval accuracy over areas covered by weak absorbing aerosols, whereas dust aerosols and continental aerosols produce a low retrieval accuracy. The DB algorithm shows good retrieval results for most aerosols, but a lower accuracy for strong absorbing aerosols.
Highlights
Atmospheric aerosols are solid, liquid, and gaseous particles that are suspended in the atmosphere, and their diameters range from 10−3 to 102 μm [1,2]
The results clearly indicate that the Deep Blue (DB) algorithm produces more continuous aerosol optical depth (AOD) results with wider retrieval scales and compensates for the errors generatedAtmosphere by the2017, DT8,algorithm over the Sahara Desert
The accuracy of the DB product is higher than that of the Dark Target (DT) product over most areas, This study aims to investigate the global accuracy of the Moderate resolution Imaging Spectroradiometer (MODIS) DT and DB aerosol products except for those with strong absorbing over continental in areas with different aerosol types and land surface reflectance (LSR) variations
Summary
Atmospheric aerosols are solid, liquid, and gaseous particles that are suspended in the atmosphere, and their diameters range from 10−3 to 102 μm [1,2]. Aerosol particles affect the atmospheric radiation balance through direct and indirect radiation forcing, and they lead to important effects on local and global ecological environments and climate change [3,4]. They cause decreases in atmospheric visibility and affect transportation; they present a hazard to human health through the distribution of harmful substances and cause respiratory and cardiopulmonary disease [5,6]. The wide coverage and continuous monitoring provided by remote sensing techniques compensate for the limited nature of ground observations and permit effective large-scale aerosol detection [7,8]
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