The Collection 6 'dark-target' MODIS Aerosol Products

摘要: Aerosol retrieval algorithms are applied to Moderate resolution Imaging Spectroradiometer (MODIS) sensors on both Terra and Aqua, creating two streams of decade-plus aerosol information. Products optical depth (AOD) size used for many applications, but the primary concern is that these global products comprehensive consistent enough use in climate studies. One our major customers international modeling comparison study known as AEROCOM, which relies MODIS data a benchmark. In order keep up with needs AEROCOM other users, while utilizing new science tools, we have improved products. The code, associated products, will be Collection 6 (C6). While not overhaul from previous 5 (C5) version, there changes significant impacts their interpretation. its entirety, C6 algorithm comprised three sub-algorithms retrieving properties over different surfaces: These include dark-target DT retrieve (1) ocean (2) vegetated-dark-soiled land, plus (3) Deep Blue (DB) algorithm, originally developed desert-arid land. Focusing algorithms, updated assumptions central wavelengths, Rayleigh depths gas (H2O, O3, CO2, etc.) absorption corrections, relaxing solar zenith angle limit (up 84) increase pole-ward coverage. For DT-land, cloud mask allow heavy smoke retrievals, fine-tuned assignments type function season location, corrected bugs Quality Assurance (QA) logic, added diagnostic parameters such topographic altitude. DT-ocean, improvements revised thin-cirrus detection, inclusion wind speed dependence retrieval, updates logic QA Confidence flag (QAC) assignment, additions important At same time introduced changes, also accounted upstream including: instrument calibration, land-sea masking, changed masking. Upstream impact coverage statistics retrieved AOD. Although responsibility code product merges DB semi-arid land surfaces provide more gap-free dataset, primarily visualization purposes. Preliminary validation shows compared surface-based sunphotometer data, C6, Level 2 (along swath) DT-products compare at least well those C5. information about clouds field, including an 500 m resolution, calculations distance nearest clear pixels. Finally, strategy aggregating averaging (swath) become 3 (gridded) data. All together, result reduced AOD (by 0.02) increased along spatial Changes calibration Terras series, especially This reduction artificial differences Aqua datasets, stabilize target studie