A numerical simulation of a strong wind event in January 2013 at King Sejong station, Antarctica

Abstract

A strong wind event (SWE), so-called "severe gale", with a 10 min average wind speed of above 22m/s occurred on 7 January 2013 at the King Sejong station (KSJ) on the tip of the Antarctic Peninsula (AP). We examine the cause of the SWE and assess the short-term predictability of such an event, using the state-of-the-art Polar Weather Research and Forecasting (Polar WRF) model. The simulation results, initialized at 0000UTC 6 January 2013, the day prior to the occurrence of the SWE, produce the most accurate representation of the SWE in terms of strength (∼94% of the peak wind speed). Both model results and observational records reveal that the SWE ismainly caused by the approach of a deep depression with the central pressure of 950 hPa. On top of this synoptic configuration, a particular shape of topography of the AP plays a non-negligible role for further intensification of the wind at KSJ. As the cyclone approaches theAP, the sea-level pressure becomes lower and is deformed around the AP due to the topography, driving southeasterly winds traversing the AP. The continuous flow overriding the AP generates a downslope windstorm at the lee side of the AP. The windstorm effect driven by the deformation of sea-level pressure by the topography of the AP is not properly represented in the coarser-resolution (27 km) model domain compared with higher (3 and 9 km) resolutions. We conclude that the SWE at KSJ on 7 January 2013 is caused by the combined effect of a synoptic-scale low-pressure system with local topography of the AP.