台风“南玛都”路径突变原因分析

Analysis of the Causes for the Abrupt Turning of Typhoon Nanmadol's Path

对0428号冬季台风“南玛都”的移动路径分析表明,台风“南玛都”在南海移动路径发生明显突变转向是一小概率事件,“南玛都”路径突变前的移动路径与500hpa副热带高压南侧的环流相平行,突变点与副热带高压西脊点相一致;高空槽东移与副热带高压东退是“南玛都”路径突变的重要原因,突变后的路径基本上与θse的高值区相一致。在高空低槽(500hpa)前部大范围深厚的西南气流和低层(地面层和850hpa)干冷空气的共同作用下,台风的强度有明显的减弱,且移动速度明显加快。

The analysis of typhoon Nanmadol＇s path shows that it is rare for typhoon Nanmadol to turn its path in South China Sea. The movement of typhoon Nanmadol before turning its path parallels with circumfluence of 500hpa south subtropical high, and the turning point is consistent with the west ridge point of subtropical high. The turning of Nanmadol＇s path is mainly caused by the east movement of the upper trough and the east recede of subtropical high, and its path after turning point basically accords with the high value of θse. Under the coinfluence of a large ara of profound southwest flow in front of trough on upper level （500 hpa） and cold and dry air on lower level （surface and 850hpa）, the typhoon is obviously weakened while its movement speed increases.