宁夏地表湿润状况及极端干湿事件演变规律

Evolvement Law of Surface Humid Status and Extreme Dry/Wet Events in Ningxia

利用宁夏1961—2004年月平均气温、月降水量资料,计算了地表湿润指数,以此为基础对宁夏地表湿润状况及极端干湿事件的分布特征进行了较为深入的研究。结果表明:近40多年来,宁夏大致经历了冷湿期、冷干期、暖干期;自20世纪60年代以来,宁夏年极端干旱频率有增加的趋势,极端湿年高频区逐渐缩小;80年代以来,宁夏极端干旱年事件高频区明显扩大;不同气候型态下,极端干湿事件频率具有明显差异,冷干期极端干旱事件最多,极端湿润事件最少,冷湿期极端干旱频率最小,极端湿润频率最大。

Using the monthly precipitation and the monthly mean temperature data in 1961-2004 from 20 meteorological stations,, we calculated the surface humid indexes throughout Ningxia province. According to the indexes, we further studied the distribution characteristics of the surface humid status and the extreme dry/wet events in Ningxia. The results indicated that the climate of Ningxia has undergone the cold-wet period, the cold-dry period and the warm-dry period in recent 40 years; the extreme arid event frequency ap- peared increasing trend; the high-frequency area of extreme wet years shrank gradually since 1960s, whereas the high-frequency area of extreme dry years obviously expanded since 1980s. The frequency of extreme dry/wet events in Ningxia showed obvious differences among different climate types： more extreme dry events or less extremewet events in cold-dry period, smaller arid frequency or larger humid frequency in cold-wet period.