The Effects of Flow Patterns over the Northwest Pacific on Typhoon Tracks

Based on the analysis of wind field in the troposphere over the Northwest Pacific, the effects of the environmental flow—patterns on typhoon tracks have been examined. For seven categories of normal tracks of typhoons, the anticyclonic circulation of the subtropical high over the Northwest Pacific is believed to be the key circulation feature directly affecting the typhoon tracks. The circulation features in the westerlies, especially, distribution and variation of the upper–level westerlies play an important role in controlling the different tracks. The analysis further indicates that typhoons tend to move along the axis line of warm area of deep tropospheric layer in the direction of the thermal wind.