对南海不同区域热带气旋气候特征的分析

Climatic Characteristics of Tropical Cyclones Entering the Different Regions of the South China Sea

利用1949—2015年CMA-STI热带气旋(TC)的最佳路径数据集分析了影响南海及其不同区域的TC频数、强度、源地和路径等气候特征.结果表明:影响南海、南海北部、南海南部热带气旋的年平均频数分别为11个、7.5个和3.0个,其年变化均为单峰型,峰值月分别出现在9月、8月和11月;影响南海中部的TC的年平均频数为6.1个,其年变化为双峰型,主峰出现在10月,次峰出现在7月.在影响南海的TC中,有52%的TC来源于西北太平洋,48%的TC来源于南海;在影响南海北部、中部和南部区域的TC中,来源于西北太平洋的TC频数占比分别为52%、52%、54%,并且西北太平洋生成的TC强度明显强于南海生成的TC强度.在南海的不同区域中,影响南海北部区域的TC强度最强,南部区域最弱.对于影响南海区域的TC,其生成源地主要集中在5°N以北的南海海域和菲律宾以东至150°E和6°~16°N的西太平洋海域;对于影响南海北部到南部区域的TC,其生成源地的纬度依次向南移、经度依次向西移.对于影响南海及其北部、中部和南部区域的TC,其路径移动方向分别集中在WSW-NW、W-NW、W-NW、WSW-WNW扇区,累计频率均在55%以上,对于主导方向,除南部为W方向(频率23.9%)外,其他均为WNW方向(频率均在24%以上).1949—2015年期间,影响南海和南海北部的TC年频数呈显著的减少趋势,减少速率分别达到0.6个/10a和0.5个/10a,南海中部区域的TC年频数呈微弱的减少趋势,而南部区域的TC年频数则无变化趋势.影响南海及其北部和中部区域的TC强度均有显著增强的趋势,而影响南海南部的TC强度则仅有弱的增强趋势.

In the report, the best path data set of CMA-STI tropical cyclones （TC） from 1949 to 2015 were used to analyze the climatic characteristics which affect the frequency, intensity, source, and path of the South China Sea and some other regions~ The results indicated that annual average frequency of TC entering the South China Sea and its northern, southern regions were 11,7.5, and 3, respectively, with single peak appeared in Septem- ber, August and November; the annual average frequency of TC entering the central South China Sea was 6.1, with double peak appeared in October and July; among the TC affecting the South China Sea, 52% TC were from the Northwest Pacific, and 48% were locally generated; among the TC affecting the northern, central and southern region of the South China Sea, the ratio of TC from the Northwest Pacific was 52% , 52% , and 54% , respectively, and TC intensity from the Northwest Pacific was significantly stronger than those from the South China Sea. In the different regions of the South China Sea, the intensity of TC affecting the northern region were the strongest, while those affecting the southern region were the weakest. TC affecting the South China Sea main- ly ranged from the South China Sea （〉5~N） , and east ocean of Philippine Islands till 150~E, 6~ -16~N of the Northwest Pacific; the latitudes of the source regions of TC affecting the southern and northern regions of the South China Sea in order to the south, while the longitudes of it in order to the western. The path directions of TC affecting the South China Sea and its northern, central and southern region were concentrated in WSW-NW, W-NW, W-NW, and WSW-WNW, respectively, with total frequency over 55% , the leading directions of all re- gions were WNW with frequency over 24% , except that the south was W （23.9%）. From 1949 to 2015, the TC frequency of the South China Sea and its northern region significantly decreased （ -0.6 and -0.5 per dec- ade） , which reach 0.6/10a 和 0.5/10a, respectively, the TC frequency of the South China Sea and its central region was faint decreased, while no significant change trends in the central and the southern region; the TC in- tensity of the South China Sea and its northern region and central regions showed a significant increasing trend, while the trend was not significant in southern region.