1998年台风与飓风异常成因分析
ANALYSIS ON THE ANNUAL FREQUENCY ANOMALIES OF TYPHOON AND HURRICANE IN 1998
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摘要: 1998年,西北太平洋台风年发生频数创下14个的谷值,打破了建国以来1951年全年生成20个台风的最低纪录。而在同年,大西洋飓风发生数目却创下了14个的近年最高纪录。本文利用NCEP/NCAR再分析等资料,分析了台风发生与越赤道气流活动异常之间的关系。发现:1998年夏季(6~9月)东半球90°E~180°区间里越赤道气流明显地偏弱,而0~90°E区间里,特别是位于40~45°E的索马里急流处,越赤道气流极强,是造成1998年南海及西北太平洋台风发生数目特少的重要原因。而1998年大西洋飓风发生数比气候平均发生数目明显偏多以及当年强烈飓风造成重大灾害的主要原因,也正是由于1998年夏季40°W及75°W处越赤道气流异常强劲所引起的。Abstract: In 1998, the annual frequency of the Typhoon(including the tropical storm) genesis created a minimum value—14, it is far lower than the minimum of 20 in 1950 over North-West Pacific, while in the Atlantic Ocean, the annual frequency of the hurricane (including the tropical storm) created a maximum value—14, it is far higher than the average number—9.2. In this paper, an analysis on the relationship between the generation of Typhoon, Hurricane and the Cross-Equatorial Flow(CEF) was made by using the NCEP/NCAR reanalysis data during 1979~1995. The result points out that the anomalies of the CEF over the Pacific and Atlantic Ocean is the main cause for the 1998 annual frequency anomalies of Typhoon and Hurricane, respectively.
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Key words:
- typhoon /
- hurricane /
- anomalies of the gross-equatorial flow
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