Heavy precipitation characteristics over India during the summer monsoon season using rain gauge, satellite and reanalysis products

Ground-based India Meteorological Department, Aphrodite (Aphro) and satellite-based observations Tropical Rainfall Measuring Mission 3B42V6 and V7 and GPCP, high-resolution Climate Prediction Center merged daily precipitation estimates based on satellite and rain gauge data available for the period 2001–2007 and reanalysis products (ERA-INTERIM and MERRA) are analysed to determine the spatio-temporal variability of heavy precipitation during the summer monsoon season over the Indian subcontinent. The purpose of this work is to compare the representation of heavy precipitation by different datasets with different resolutions, and the focus of this study is to compare the heavy rainfall data over the Central Indian land and different subdivisions within India. Day-to-day variation in rainfall activity over the Central Indian region obtained from these datasets is compared among the different datasets from gauge observation, satellite, merged products and reanalysis products. The study showed that, over most of India, the mean and extremes in rainfall are captured well by the all the datasets. However, considerable differences exist among the datasets. The spatial and temporal variation of the summer monsoon rainfall is examined by computing various indices using different datasets for wet years (2003, 2005, 2006) and dry years (2001, 2002, 2004). The spatial pattern of the rainy days and heavy precipitation indices follows the spatial pattern of the seasonal rainfall. Large interannual variability is observed in the spatial distribution of the indices of precipitation extremes. The heavy precipitation (90 percentile) indices over Central India show low/high values during drought/excess years and also follow the mean precipitation indices in all the datasets. The study shows that gauge and remote sensing through satellite and gauge satellite merged products play an important role in monitoring climate and provide continuous datasets at high resolution and also useful in studying the climate of data-sparse regions. Comparison with the reanalysis products shows promising signs of capturing heavy precipitation in ERA-INT and MERRA dataset during the monsoon season. In spite of varied resolutions the datasets have consensus in capturing the light, moderate and heavy precipitation; however, considerable differences exist among the datasets.