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arXiv 0801.1013physics.ao-ph
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SST和北美热带气旋登陆:统计模拟研究

SST and North American Tropical Cyclone Landfall: A Statistical Modeling Study

Timothy Hall, Stephen Jewson

摘要:

利用一个北大西洋热带气旋(TC)路径的统计模式,研究了海表温度(SST)与北美TC登陆率之间的关系。该跟踪模型是以1950-2005年期间热带北大西洋夏季SST处于19个最热或19个最冷年份为条件的。对于每种条件,都会生成许多合成TC并计算登陆率。与直接分析历史登陆相比,轨迹模型通过将整个流域的信息投影到海岸上来减少采样误差。在模型中,热年份的TC比冷年份多46%,与随机抽样相比,这是非常重要的,并证实了近几十年来北大西洋TC数量的有据可查的趋势。在没有其他影响的情况下,这种差异导致在炎热的年份,沿海岸均匀的模型登陆率显着增加。在地理分布的成因和TC传播的冷热差异并没有显着改变整体的登陆率差异的模型中,和净登陆率是1/4.7年,在炎热的年份和1/3.1年,在寒冷的年份。然而,SST对生成地点和传播的影响确实改变了登陆的地理分布。尤卡坦半岛在炎热年份的登陆率是寒冷年份的3倍,而美国大西洋中部海岸没有明显变化。与佛罗里达州、美国墨西哥湾沿岸、墨西哥湾沿岸和尤卡坦半岛的所有年份相比,炎热年份的登陆概率增加,置信度至少为95%。

英文摘要:

We employ a statistical model of North Atlantic tropical cyclone (TC) tracks to investigate the relationship between sea-surface temperature (SST) and North American TC landfall rates. The track model is conditioned on summer SST in the tropical North Atlantic being in either the 19 hottest or the 19 coldest years in the period 1950-2005. For each conditioning many synthetic TCs are generated and landfall rates computed. Compared to direct analysis of historical landfall, the track model reduces the sampling error by projecting information from the entire basin onto the coast. There are 46% more TCs in hot years than cold in the model, which is highly significant compared to random sampling and corroborates well documented trends in North Atlantic TC number in recent decades. In the absence of other effects, this difference results in a significant increase in model landfall rates in hot years, uniform along the coast. Hot-cold differences in the geographic distribution of genesis and in TC propagation do not significantly alter the overall landfall-rate difference in the model, and the net landfall rate is 1/4.7 yr in hot years and 1/3.1 yr in cold years. SST influence on genesis site and propagation does modify the geographic distribution of landfall, however. The Yucatan suffers 3 times greater landfall rate in hot years than cold, while the U.S. mid-Atlantic coast exhibits no significant change. Landfall probabilities increase in hot years compared to all years in Florida, the U.S Gulf coast, the Mexican Gulf coast, and Yucatan with at least 95% confidence.

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