Synergistic Use of EOS-06 Scatterometer and Doppler Weather Radar Observations for Coastal Wind Field Assessment: A Case Study

Abstract

Abstract: The Oceansat-3 Ku-band Scatterometer (OSCAT-3) payload onboard the Earth Observation Satellite-06 (EOS-06), provides valuable global sea surface winds. The scatterometer was launched on November 26, 2022 by the Indian Space Research Organisation (ISRO). It is well known that the scatterometer measurements are contaminated in the presence of isolated rain events. The idea of the present study is to (i) study the impact of rain on OSCAT-3 wind retrievals in the presence of isolated rain events and (ii) explore the complementary role of Doppler Weather Radar (DWR) wind data in characterizing wind conditions near the coast during a pre-monsoon convection event. The study utilises OSCAT-3 observations from May 2024 collocated with ECMWF ERA5 and GPM-IMERG rain-rate over the Indian Summer Monsoon Region (ISMR). The statistical analysis reveals that the OSCAT-3 increasingly overestimate in low to moderate wind speed regime under increasing rain-rates. Furthermore, a case study of a pre-monsoon heavy rainfall event on May 18, 2024, revealed intense convection with INSAT-3D OLR values below 150 W/m2 and high CAPE values reaching 3751.22 J/kg. DWR retrieved high-resolution 2D horizontal wind fields supplementing OSCAT-3 surface winds providing detailed insights into the precipitation system's dynamics. The DWR retrieved winds shows a significant convergence of the winds near the coast. The combined use of OSCAT-3 and DWR data enhances coastal wind analysis, providing a comprehensive understanding of wind field variations in the presence of heavy rainfall. Article Highlights: Assessing the impact of rain on OSCAT-3 Ku-band scatterometer winds. OSCAT-3 winds tend to increasingly overestimate in low to moderate wind speed regime with increasing rain rates. Investigation of a pre-monsoon heavy rainfall event that occurred on May 18, 2024, over the southern peninsula. Combined OSCAT-3 and Doppler Weather Radar retrieved horizontal winds to enhance wind observations near coastal regions. © Indian Society of Remote Sensing 2025.