Paradigm of surface wind fields generated using Scatsat-1 and low-level adjusted INSAT-3D winds during tropical cyclone Amphan

Abstract

ABSTRACT Ocean surface vector winds are of paramount importance for studying almost all meteorological and oceanographic processes. Wind vector products over the oceans are available from polar orbiting scatterometers and infrared imagers onboard geostationary satellites. The scatterometers provide wind vectors at the surface level, whereas imagers provide winds at different pressure levels in the form of Atmospheric Motion Vectors (AMVs). In this study, an attempt has been made to first project the low-level AMVs from INSAT-3D to the sea surface level followed by combining winds from Scatsat-1 scatterometer for typical case of a super cyclone Amphan. Swath-based observations from a scatterometer cannot cover the entire area affected by a cyclone, whereas AMV products have limited coverage during cyclones because of cloud cover. Thus, the wind products generated by combining the two types of satellite observations surely have sufficient merit in terms of enhanced number of observations to cater to various meteorological aspects related to the cyclones. The generated winds are subsequently validated using operational products from the National Centre for Medium Range Weather Forecast numerical weather prediction model, yielding root mean square errors of ~2 m s−1 and ~20° in wind speed and direction respectively.