The possible linkage of satellite based cloud microphysical parameters (CMP) to the Indian Summer Monsoon (ISM) active and break phase

摘要

The unpredictability of Indian Summer Monsoon (ISM) remains an area of major challenge for operational forecasters. The distribution of active and break days in a monsoon season, though of utmost importance is very difficult to predict. In this regard, the geostationary satellite observations from Indian National Satellite System-3D (INSAT-3D) satellite over the Indian region provide significant insights into the propagation of ISM. In this manuscript, the correlation of satellite derived cloud microphysical parameters (CMP) to the strength and development of the ISM is studied objectively for the years 2017 and 2018. In particular, the association of the CMP to the active and break spell has also been investigated. It is found that the Cloud Particle Effective radius (CER) and the Cloud Optical Thickness (COT) bears a maximum correlation of 0.67 and 0.65 with the daily average rainfall at 1 day lag. The histogram analysis with active/break conditions show that CER exhibit a bimodal distribution (～27 μm and ～36 μm) during an active spell, while in case of break phase, smaller cloud droplets ranging in size between 15 and 25 μm is prevalent. The findings of the study will contribute towards better understanding and prediction of active and break spells of ISM.