A MODELING STUDY OF INHOMOGENEOUS COASTAL GALES ASSOCIATED WITH THE LANDFALL OF TYPHOON SOUDELOR (2015)

Abstract:

In this study, coastal gales and rainfall attributed to the landfall of Typhoon Soudelor (2015) are analyzed based on observational dense automatic weather stations data, advanced scatterometer-retrieved 10-m ocean surface wind data and simulations using the Weather Research and Forecast (WRF) model. This study focuses on gale bands in the right-front quadrant of the typhoon and associated coastal winds over Zhejiang and Fujian Provinces in China before the landfall of the typhoon. The results are summarized as follows. (1) 10-m surface wind data from automatic weather stations over land and islands, advanced scatterometer-retrieved 10-m ocean surface wind data, and the WRF simulation indicate similar mesoscale offshore gales. (2) The model simulation with a 333-m grid mesh indicates a gale zone over the right-front quadrant of the typhoon; the gale is “broken” over the coastal areas, and formed an inhomogeneous gale band. (3) The model-simulated winds agree well with the island observations. (4) Non-uniform gales over boundary layers result in horizontal wind-speed gradients and strong convergence that favors the development of convection and the maintenance of ocean surface gales.