AN OBSERVATIONAL STUDY OF THE CHANGES IN THE INTENSITY AND MOTION OF TROPICAL CYCLONES CROSSING LUZON

作者：WU MAN-CHI,CHOY CHUN-WING

摘要：Tropical cyclones(TCs) moving across Luzon from east to west are likely to affect Hong Kong. As such, it is important for forecasters take into account the likely changes in intensity and movement characteristics of TCs crossing Luzon. 50 TCs in the period 1980-2014 were examined to determine the effect of Luzon’s terrain on their intensity and movement.The results indicated that TCs generally weakened as they passed through the terrain of Luzon. The decrease in the maximum sustained winds(MSW) for TCs with intensity of severe tropical storms or below was normally < 10 knot. For typhoons, the decrease in the MSW was usually ≥10 knot. The study also showed that TCs moving across Luzon were likely to accelerate(decelerate) as they approached(moved away) from Luzon. Furthermore, while there was a slight bias for TCs to defl ect leftwards on leaving Luzon, a signifi cant negative correlation was found between the defl ection tendency before and after crossing Luzon. A TC defl ected to the right(left) before landfall was likely to defl ect to the left(right) after leaving Luzon. Also, defl ection upon/near landfalling is found to be related to the intensity, moving speed and the direction of motion of a TC.

發文機構：Hong Kong Observatory

關鍵詞：ANOBSERVATIONALSTUDYOFTHECHANGESINTHEINTENSITYANDMOTIONOFTROPICALCYCLONESCROSSINGLUZONAPTCFigure

分類號： P444[天文地球—大氣科學及氣象學]