In this paper, we use the high resolution weather forecast model (HRM), which is able to simulate meso-scale phenomena in limited regions, to predict motion of TCs in the South China Sea in 2002-2004, including two typical weak, slow-moving and unexpected changing TCs Mekhala and Nepartc;tk. Vve have chosen two forecast domains with different areas and resolutions. The results show that with the smaller domain, appropriate buffer and higher resolution HRM can predict better motion of TCs operating in the South China Sea. | Vietnam Journal of Mechanics, VAST, Vol. 27, No. 4 (2005), pp. 193-203 ON THE HIGH RESOLUTION REGIONAL WEATHER FORECAST MODEL (HRM) AND FORECASTING TROPICAL CYCLONE MOTION OVER THE SOUTH CHINA SEA LE D uc 1 ' LE CONG THANH 2 ' KIEU THI XIN 1 1 2 Hanoi National University National Hydro-m eteorological Service of Vietnam Abstract. Chan (1995) [2] has found that, only 70% in 60 cases of the tropical cyclone (TC) movement test (TMT-90) developed from steering flows. The 30% remain of cases have to be explained by nonbarotropic processes. Vie are of the opinion that all weak, slow-moving and unexpected changing TCs over the South China Sea are in t his 30% set. The nonlinear interaction between barotropic and nonbarotropic processes has affected on motion and structure of such TCs. In this paper, we use the high resolution weather forecast model (HRM), which is able to simulate meso-scale phenomena in limited regions, to predict motion of TCs in the South China Sea in 2002-2004, including two typical weak, slow-moving and unexpected changing TCs Mekhala and Nepartc;tk. Vve have chosen two forecast domains with different areas and resolutions. The results show that with the smaller domain, appropriate buffer and higher resolution HRM can predict better motion of TCs operating in the South China Sea. 1. INTRODUCTION In recent years, the theory about tropical cyclone (TC) motion focus on the ideas which assume that TC-motion is caused by b arotropic processes on the base of the conservation of t he absolute vorticity with two main mechanisms: the advective adjustment by environment flows of the relative vorticity related to TCs (steering flows) and the advective process including the nonlinear impact between steering flows and the gradient of planet vorticity and the circulations of vorticities. Chang (1995) [3] mentioned that those impacts are generated during the evolution of flows with different wave numbers . Advective process resulting from each wave number .
