热带气旋强度资料的差异性分析

COMPARISON OF THREE TROPICAL CYCLONE STRENGTH DATASETS

通过对比西北太平洋3个主要预报中心(中国气象局(CMA)、日本东京台风中心(RSMC Tokyo)和美国联合台风警报中心(JTWC))的16 a数据,分析了不同来源的热带气旋(TC)强度资料的差异性。结果表明:CMA与RSMCTokyo和JTWC的TC强度均值分别相差0.6和1.7 m/s,均通过1%信度的统计检验,即存在显著差异;3个中心对同一TC确定的强度最大差异超过30 m/s;CMA资料的台风数多于RSMC Tokyo和JTWC,年台风频数的均方差也最大,但是3个中心资料的各级TC频数差异均无统计显著性。对比有、无飞机探测时段的资料发现,对TC进行飞机探测可在一定程度上减小各中心在确定TC强度方面的分歧。为了初步了解上述资料问题对TC强度预报的可能影响,采用一个气候持续性预报方法,取不同来源的TC强度资料进行了4 a(2000—2003年)的预报。发现据JTWC资料所得TC强度预报有最大的均方根误差,RSMCTokyo的最小,CMA居中;据CMA和RSMC Tokyo(CMA和JTWC)资料,对相同TC相同时次24 h预报的平均绝对偏差达2.5(4.0)m/s,最大可相差16(21)m/s。可见,西北太平洋TC强度的基本资料问题增加了预报的难度。

Analyzed in this paper are the 16-year （1988 - 2003） tropical cyclone （TC） intensity data from three major forecast centers for Northwest Pacific typhoons, i.e. China Meteorological Administration （CMA）, Regional Specialized Meteorological Center Tokyo （RSMC Tokyo）, and Joint Typhoon Warning Center （JTWC）. Analysis results show that the mean strength difference of tropical cyclones between the CMA and RSMC Tokyo datasets and between the CMA and JTWC datasets are 0.6 and 1.7 m/s, respectively, which are both significant at the 1% confidence level; the maximum difference in the strength of the same tropical cyclone determined by three major typhoon forecast centers is more than 30 m/s; and the number of typhoons of the CMA dataset is greater than those of the RSMC Tokyo and JTWC datasets, and the mean square deviation of the annual frequency of typhoons of the CMA datasets is also largest, but there is no significant difference in the frequency of various category tropical cyclones among the three center datasets. The comparison of the data of different time periods with and without flight reconnaissance suggests that the flight reconnaissance over TC can to some extent reduce the discrepancy in determining the strength of TC among different centers. A climatic persistence prediction model for TC strength is established to assess the possible impact of initial values on the prediction of TC strength, and four years （2000 -2003） prediction experiments using different initial values from different forecast centers are performed. The experimental results indicate that the root mean square error （RMSE） of the 4-year independent forecasts is largest using the JTWC data, smallest using the RSMC Tokyo data, and in between using the CMA data. The averaged absolute deviation of 24h strength prediction using the CMA and RSMC Tokyo data/CMA and JTWC data is 2.5/4.0 m/s, with the maximum deviation reaching 16/21 m/s, respectively. Such a problem of the initial value arose from the basic data of the strength of Northwest Pacific tropical cyclones raises the difficulty in the strength prediction of TCs.