关键词: 地表湿润指数, 气候型态, 极端干湿事件, 演变规律, 宁夏

Abstract: 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 appeared 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 extreme wet events in cold-dry period, smaller arid frequency or larger humid frequency in cold-wet period.

Key words: surface humid index, climate type, extreme dry/wet events, evolvement law, Ningxia