Abstract
This study aims to create a 21-year, high spatiotemporal resolution
Global Satellite Mapping of Precipitation (GSMaP) rainfall product
adjusted by rain gauge measurements over the Indian mainland. The
targeted resolutions of the GSMaP are hourly and 0.1°× 0.1°. The
National Oceanic and Atmospheric Administration (NOAA) Climate
Prediction Center (CPC) daily gauge analysis (0.5° × 0.5°) and Indian
Meteorological Department (IMD) daily gridded rainfall product (0.25° ×
0.25°) were utilized to generate two long-term rainfall products,
GSMaP_CPC and GSMaP_IMD rainfall, respectively. After preliminary
verification of the GSMaP_CPC and GSMaP_IMD rainfalls with IMD gauges,
these rainfall products are evaluated for the Indian Summer Monsoon
(ISM) periods of 2000–2020 with comparisons of other merged rainfall
products such as the Integrated Multi-satellitE Retrievals for Global
Precipitation Measurement (IMERG). The results suggest GSMaP_IMD has a
smaller root-mean-square difference (RMSD) and higher correlation than
GSMaP_CPC, evaluated against independent rainfall products. In the
three-hour mean analysis with spaceborne precipitation radar data, it is
found that the value of RMSD decreases in GSMaP_IMD with respect to
GSMaP_CPC throughout the day. The statistics against the hourly dense
rain gauge network in Karnataka suggests that the GSMaP_IMD is more
effective in capturing large spatiotemporal rainfall variation over
India. Thus, validation results with the independent sources suggest
that GSMaP_IMD rainfall generally improved over GSMaP_CPC rainfall.
These improvements are significant in orographic regions with high
rainfall amounts, mainly the western Ghats and northeastern parts of
India.