西北太平洋热带气旋的时空分布特征分析

西北太平洋是世界上热带气旋(TC)发生频率最高、强度最强的一个海区,因此对西北太平洋TC进行气候分析是很有意义的.根据1945-2006年JTWC的数据资料对西北太平洋的热带气旋时空分布特征进行了统计分析,得到TC活动的一些最新概况.从时间分布特征上来看:TC频数呈增加趋势,有两个上升阶段,两个下降阶段;台风和强台风与TC的变化趋势大致相同,但自2000年至今有上升趋势;在季节上分布上,热带气旋,台风和强台风频数存在时间上的延迟现象.从空间分布特征来看:TC源地在0°～30°N范围内,纬向发生高频区轴线位于12.6°N,经向对应于南海海区和菲律宾以东及关岛附近洋面有两个峰值;TC强度越强,其发生高频区纬向轴线向赤道方向移动,而经向轴线向东移动;南海海区不是强台风的高发区;台风和强台风源地高频区经向轴线在145°～155°E之间移动;纬向轴线在6°～14°E之间移动,强台风的源地高频区经向轴线始终位于台风轴线的东侧,而纬向轴线位于其南侧.

Spatiotemporal distribution of tropic cyclones in north-west Pacific Ocean

The northwest Pacific (NWP) Ocean is one of the places where has the maximal frequency and highest intensity of tropical cyclones (TC) in the world. It does make sense to investigate the climatic features of TCs in the NWP. Based on the Joint Typhoon Warning Center (JTWC) data on TCs in the NWP from 1945 to 2006, the characteristics of spatiotemporal distribution were statistically analyzed, and some latest conclusions about TC activities were obtained in this paper. The temporal distribution of TC in NWP shows that, although it includes two increasing phases and two decreasing ones, the total trend of the frequency of TCs keeps increasing during this period as a whole. The frequency of typhoon (TY) and super typhoon (STY) has the similar trend as TC, with a exception of the increasing trend since 2000. As the seasonal distribution is concerned, it is found that there exists time delay on the frequency distributions of TC, TY and STY. The analysis of the spatial distribution of TCs indicates that the original locations of TCs varied from 0°N to 30°N and the latitudinal axis of maximal occurrence of TCs lies in 12.6°N with one peak occurring at South China Sea and the other at the east of Philippines and Sea surface near Guam. As the intensity of TC increases, the axis of zonal maximal occurrence of TCs moves toward the equator, and the longitudinal peaks shifted eastward. In addition, it is found that TY and STY usually occur in the area between 145°～155°E and 6°～14°E and the zonal axes of maximal occurrence of STY always located at the east of that of TY, and the longitudinal axes of STY lies in the north of that of TY.