铜仁市夏季干旱指数适应性研究

基于铜仁市10个县区气象台站的降水和气温资料,计算出了1961 ～2011年铜仁市夏季Z指数、降水距平百分率Pa、气象干旱综合指数CI、相对湿润指数MI以及标准化降水指数SPI,并与干旱实况进行了详细对比,得出5种干旱指数在铜仁的适应性.结果表明,5种干旱指数中Z指数在夏季运用的总体效果最好,铜仁市10个台站中,Z指数除了对德江的旱情反映较差外,其余9站中运用效果在5种干旱指数中均是最好;其次为降水距平百分率Pa,Pa在铜仁市的东南部运用效果好于西北部;而修正后的非等权的CI指数在西北部的运用效果较好;在强度分布上,Z指数的效果比Pa指数在中旱以上量级更为精准,在此基础上,运用EOF方法对铜仁市夏季Z指数场进行展开,得出前5个特征向量的方差贡献达91.3％,其中第1特征向量占67.0％,第1特征向量为清一色的正值,说明整个铜仁市的夏季旱涝在变化趋势上具有相当好的一致性,此外还有南北反向和西北—东南反向2种空间型.

Study of the Adaptability of Summer Drought Indices in Tongren City

Based on the precipitation and temperature data of 10 county meteorological stations in Tongren City during 1961-2011,Z,Pa,CI,SPI and MI index of summer were calculated and were compared with the drought situation,the adaptability of five kinds of drought index in Tongren City was obtained.The results showed that：Z index effect is the best,followed by Pa,Pa used in the southeast of Tongren City is better than that.of the northwest.The modified CI index used in the northwest has better effect.In the intensity,the Z index effect is more accurate than the Pa index.On the basis of this,the summer Z index in Tongren City was launched using the EOF method,the variance contribution of the first 5 eigenvectors reached 91.3％,which accounted for 67.0％ of the first eigenvector.In addition,there are two space styles of south north reverse and northwest and southeast reverse.