沿海风工程设计风速中泊松-耿贝尔法的应用

每年西北太平洋热带气旋(TC)发生的次数、移动路径和强度都是随机的,我国东南沿海各地每年受TC影响的次数便构成了某种离散型分布,而TC影响下的最大风速则可以构成某种连续型分布。该文采用上海台风研究所提供的1961—2006年TC中心风速和TC影响期间各台站大风资料,利用泊松-耿贝尔联合极值风速计算方法,计算了沿海各气象站TC影响大风的多年一遇风工程设计最大风速。结果表明:当观测资料样本序列较短,特别是像TC这样随机性很强的天气事件,泊松-耿贝尔联合极值算法更具优势;我国沿海地区有53.9%的台站50年一遇最大风速在25 m/s以下,最大风速大于42.5 m/s以上的台站分布于浙江的大陈岛、嵊山、石浦,福建的北茭和台山,广东的遮浪、上川岛和海南的西沙岛,在这些地区进行风电开发风险较大,应引起足够重视。

Application of Poisson Gumbel Distribution to Wind Speed Calculation for the Southeast Coastland of China

Tropical cyclone(TC) is the main cause of extreme wind in China southeast coastal,especially in coast to the south of the Yangtze River delta.The TC maximum wind speed may exceed 40 m·s-1,raising the risks for engineering design near the coast.The 1961-2006 TC/typhoon almanacs published by Shanghai Typhoon Institute and wind data of ground stations are investigated,and the TCs that pass with-in 3 latitudes away from the coast are defined as influential ones.There are 428 TCs passing through this area from 1961 to 2006.Typhoons and strong tropical storms are major TCs with the percentage up to 33.6% and 25.7%,and 59.3% in total.Super strong tropical cyclones and strong tropical cyclones often cause losses to wind farm,and the percentage of them is 7.9% and 13.69%,respectively.The percentage of tropical storm and cyclone is 10.3% and 8.9%,and these TCs usually bring lots of power for coastal wind farms.The numbers,motion paths and intensity of TCs generated from Northwest Pacific Ocean are stochas-tic every year.Therefore,the number of influential tropical cyclones make some kind of discrete distribu-tion in China southeast coast,obeying the Poisson distribution.But maximum wind speed under the influ-ential tropical cvclones (TC) may satisfy some kind of continual distribution,obeying the Gumbel distribu-tion.Based on the Poisson-Gumbel compound extreme distribution,the extreme wind speeds of different time scales can be obtained using TC data of coastal weather stations for the period of 1961-2006.The re-sult indicates that the Poisson-Gumbel joint distributing algorithm is superior and gives stable and accurate results when the observed data sample sequence is short,especially for the strong weather event like TC which is very random.For 53.9% of the stations,the extreme wind speed of 50 years is less than 50 m·s-1.The extreme wind speed of 50 years exceeds 42.5 m·s-1 in Dacheng,Shengshan,Shanmen,Nanjishan Islands of Zhejiang Province,Beijiao coast and Taishan Island of Fujian Province,Zhelang and Shangchuan Isiand of Guangdong Province,and Xisha Island of Hainan Province.In these areas,the risks of tropical cyclone for wind farms construction should be paid enough attention.