中美两套西北太平洋热带气旋资料集的差异分析

Study on the differences between CMA and JTWC tropical cyclone datasets for northwest Pacific

利用中国气象局(CMA)和美国联合台风预警中心(JTWC)两套西北太平洋热带气旋(TC)资料集,对比分析了两者在1951—2005年TC定位和定强方面的差异。结果表明:两套资料定位差在20世纪50年代至60年代初及1988年至90年代差异较大;地理分布上主要是在TC登陆后所在的地区及高纬度洋面上差别较大。定强方面,CMA资料在20世纪50年代及60年代末至70年代初TC强度明显大于JTWC资料,JTWC资料则在80年代末以后的时段TC强度显著大于CMA资料;地理分布上定强差大的区域在80年代以前分布较零散,之后随着JTWC资料定强增大,其在西北太平洋洋面上强度显著偏强,CMA资料同期则在亚洲大陆沿岸部分地区强度较强。进一步分析显示,两套资料集之间的差异和TC观测技术的变化之间存在密切关系。在气象卫星使用以前(1951年至60年代初),以及美国空军飞机观测终止之后(1988年以后),两者无论是在定位还是定强上都存在很大差异;而两者定强差最小的时期(1973—1987年)则正好对应了飞机观测和Dvorak技术在TC观测上同时被使用的时段。两套西北太平洋TC资料集总体差异明显,却又各具特点,目前很难判断哪一套资料集更加可靠。但对于影响中国TC,CMA资料集具有明显优势。

By using two tropical cyclone datasets for northwest Pacific（NWP） of China Meteorological Administration（CMA） and Joint Typhoon Warning Center（JTWC）,the differences with respect to TC location and intensity between them were analyzed.Results showed that for TC location,large discrepancies existed in two periods： 1951-early 1960s and 1988-1990s,and geographically always appeared in regions where TC landed or high-latitude areas.For TC intensity,the CMA dataset was apparently overestimated in 1950s and from the late 1960s to the early 1970s,while the JTWC dataset overestimated in 1993-2003.TC Intensity discrepancies showed scattered large values in different regions before 1980s,after which with the increase of intensity for JTWC dataset,it was significantly greater than that of CMA dataset in most of NWP,while the latter was greater in the coast regions of East Asia.Further analysis reveals that the discrepancies are obviously related to the TC observational techniques.Before the era of application of meteorological satellite in operational typhoon Centers（1951-early 1960s）,and after the termination of aircraft reconnaissance（1988-）,large discrepancies existed in not only TC intensity but also TC location.The smaller discrepancies period（1973-1987） for TC intensity also coincided with timeframe when aircraft reconnaissance data and the Dvorak technique were both available in TC operational centers.For the two TC datasets,although obvious discrepancies existed between them,each had its own characteristics.Currently,it is still difficult to judge which one is better,but for TC activities affecting China,the CMA dataset has obvious advantages.