Ocean surface wind from ERS-1 scatterometer and its use in inferring cyclone parameters for storm surge modelling

Abstract

The present paper deals with the use of satellite scatterometer derived ocean surface wind vectors in inferring cyclone parameters useful for the storm surge modelling. The high density of satellite surface wind data of a cyclone formed over ocean has been utilised in determining the cyclone parameters like location of cyclone centre and the radius and intensity of maximum winds. These parameters are necessary for obtaining the distribution of wind field under the influence of a cyclone which is an essential input for the storm surge modelling and prediction. Due to certain reasons like coarser spatial resolution of scatterometer compared to the size of cyclone core and the saturation of radar backscatter with increasing wind speed and the inadequacies of the model functions used for retrieval of winds, the high intensity winds in the core region of the cyclone are underestimated by the scatterometer. The method proposed here makes use of the high spatial density of wind data from scatterometer and the axially symmetric distribution of cyclonic winds around its centre to infer the cyclone parameters like the location of cyclone centre, radius and intensity of maximum winds. Results of analyses of ERS-1 scatterometer wind data for few cyclones formed over Indian oceanic region in inferring, the cyclone parameters have been presented here. Comparison of cyclone parameters inferred from ERS-1 scatterometer derived winds with those available from India Meteorological Department (IMD) has been performed which indicate the usefulness of the satellite data for the purpose.