Analysis of the causes of extreme precipitation in major cities of Peninsular India using remotely sensed data

The frequent occurrence of Extreme Precipitation Events (EPEs) over the last decade has really created havoc in Indian cities. Anthropogenic emissions are one of the components that can influence the climatology over large urban conglomerates and cause the occurrence of EPEs. Aerosols are one of the emissions-related elements that can change the characteristics, production, and lifetime of clouds, leading to changes in precipitation dynamics. The goal of the current study is to investigate the influence of aerosols in causing EPEs by analyzing remotely sensed data of aerosols, clouds, and atmospheric features (K-index) from MODIS (Moderate Resolution Imaging Spectrometer) and precipitation from GPM-IMERG for major cities in Peninsular India. The last 10 days of remotely sensed data before the occurrence of an EPE event are analyzed. Along with Aerosol Optical Depth (AOD), cloud properties such as Cloud Fraction (CF), Cloud Top Pressure (CTP), and Cloud Top Temperature (CTT) are used in the analysis. The factors influencing precipitation in each city are analyzed through multiple linear regression models. For the major cities, the parameters that together caused extreme events are examined. All the observed EPEs had intensified precipitation due to a combination of middle-level clouds (CTP in the range of 440 hPa to 680 hPa), low AOD (0.4), with many thunderstorm states (K > 35(degrees)C), and CTT 0 C-degrees. Other elements that contributed to the occurrence of EPEs included low-level clouds (CTP >680 hPa), an AOD in the range of 0.4-0.6, an isolated thunderstorm state (20 C-degrees < K < 25 C-degrees), and CTT > 0 C-degrees.

Automated summary

The frequent occurrence of Extreme Precipitation Events (EPEs) in Indian cities over the last decade has caused significant damage. Anthropogenic emissions, including aerosols, have been identified as contributing factors to the occurrence of EPEs. This study aims to investigate the influence of aerosols on EPEs by analyzing remotely sensed data. The results show that middle-level clouds, low AOD, thunderstorm states, and cloud top temperature are the main factors causing intensified precipitation during EPEs.