Evaluation of Calibration Sensitivity on Dust Detection scheme based on MODIS Thermal Emissive Channels

Dust monitoring is one of the perplexing issues in modern day aerosol remote sensing. Several dust detection techniques have been developed over the last decade using observations made by the MODIS instruments. In this work, we employ a previously developed dust detection scheme based on thermal emissive wavelengths of the MODIS sensor, fusing improvements to the scheme using the Ozone Monitoring Instrument level 2 - aerosol type pixel-level classification. The thermal emissive wavelengths used in this study include bands 20, 29, 31, and 32 respectively. These correspond to center wavelengths of approximately 3.7 μm, 8.55 μm, 11 μm, and 12 μm respectively. The dust index based on the thermal emissive wavelengths served as a good proxy to the traditional AOT from the level 2 MODIS products. However, with both the MODIS sensors well beyond their design lifetime and over 30 + years of combined mission time, some of the key instrument performance parameters have, as expected, undergone various degrees of degradation over time. Since the thermal channels are well calibrated using an on-board Blackbody, it is pertinent to check the robustness and sensitivity of the calibration over the lifetime. In this work, we perform a sensitivity analysis of the various thermal bands on the dust detection scheme. The results of the work will help understand the impacts of calibration on the higher level products and would be useful for future follow on mission such as S-NPP VIIRS and so on.