Assimilation of Sentinel-1 SAR winds in the forecasting of typhoon Lionrock

Abstract

The C-band synthetic aperture radar on-board ESA’s Sentinel satellites have the capability to provide high resolution wind vector information over the ocean surface. These wind vector data derived from SAR observations are available to the data assimilation system with real-time information of high accuracy. In this study, several comparison experiments are designed to investigate the impact of Sentinel-1 SAR winds data in the three-dimensional variational assimilation system for the Weather Research and Forecast model (WRF 3DVAR). The powerful Typhoon Lionrock is selected for this case study. Typhoon Lionrock struck and caused significant flooding and casualties in Japan and Russia in late August 2016. Its route changed several times and there are also several rapid intensification processes during its lifetime, which made its track very difficult to predict. Totally, 10 SAR images from 3 overpasses from August 27 to 29, 2016 are used in this study. The preliminary results demonstrate that SAR wind data can complement the scarce observations over the sea surface and improve the prediction of wind and pressure fields of Typhoon Lionrock. More detailed experimental results and analyses will be provided in the Dragon-4 symposium