APPLICATION OF DYNAMICAL VORTEX INITIALIZATION SCHEME ON INTENSITY FORECAST AND STRUCTURE STUDY OF TYPHOON DAMREY (2017) DURING NEAR-SHORE AND LANDFALLING PERIOD

Abstract

This study applies the dynamical vortex initialization method with the Weather Research Forecasting (WRF) to forecast intensity and investigate structure of typhoon Damrey (2017) during the near-shore and landfall period. The model was run with two cases: With and without vortex initialization with input from the Global Forecast System (GFS).

The results showed that the vortex initial significantly improves the quality of storm intensity forecast. Analysis of the model output with vortex initialzation shows that while the sea level pressure has a relatively symmetrical structure, the 10-m wind, the wind speed, the total condensated mixing ratio are asymmetric with larger values to the west of the typhon center and toward the land mass region.

As the typhoon approachs to the land, stronger winds and the move convection are simulated inland. The stronger wind speed to the west of typhoon center may be due to the interaction of the typhoon circulation with the northwest monsoon circulation. When the typhoon made landfall, more intensive deep convections are simulated due to the interaction between the storm circulation and terrain. In contrast to the convection, the maximum wind at 10-m level in the land-side of the typhoon is much weaker than the maximum 10-m wind speed over sea due to the strong influence of surface friction and mixing of low momentum air inland into typhoon region.