Decadal climatology of the spatial and vertical distributions of tropospheric aerosol over the Arabian Sea based on satellite observations

Abstract

The climatology of aerosol optical properties is retrieved and analysed for the period from June 2006 to November 2017 over the Arabian Sea from the Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua satellite. Strong seasonality and latitudinal gradients in the columnar aerosol optical depth, dust aerosol optical depth (DOD) over the Arabian Sea are observed. Most of the aerosols over the North Arabian Sea (NAS) and the Central Arabian Sea are confined to the surface (i.e., 0–3 km). However, the seasonal mean high extinction coefficient is found during summer over the Arabian Sea. The high vertical extent of aerosols (with higher extinction coefficient) at altitudes >4 km emphasizes the continental aerosol effluence from the southwestern peninsular Indian subcontinent during winter, spring and autumn seasons. The contribution of dust extinction coefficient to the total columnar DOD has been observed to be high over NAS (>35%) at 0–1 km altitude bin during all the seasons and it is lowest ( −1 ). This is due to the strong westerly winds over NAS from the coast of Oman during spring. A positive difference between DF derived from MODIS and CALIPSO is noticed, and it might be due to the limitation of MODIS in discriminating the aerosol and the cloud from its passive sensor reliable than an active sensor like lidar in CALIPSO. The outcomes of the present study will serve as a reliable source for future studies of dust‐regional scale climate interactions over the Arabian Sea.

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