摘要
自20世纪50年代以来,宁夏气温具有明显的上升趋势,尤其是60年代中后期以来,增温趋势更加明显,每10年增温0.514℃。近40多年来,宁夏气候总体上趋于干旱,虽然自80年代到90年代初降水有增多的趋势,但90年代中期以来又有明显的减少趋势。经功率谱分析发现,ENSO和降水有14年、3.75年、准2年和1.5年的周期。宁夏气温对ElNino事件响应有滞后的现象,并且在滞后7～18月期间的相关程度都通过了0.01显著性水平检验,对于LaNina事件,并没有发现这种现象。而降水对ENSO的响应也存在滞后现象,对ElNino事件滞后4个月时达到最大响应,而对LaNina事件只需滞后1个月,它们的相关显著性都通过了0.01显著性水平检验。宁夏降水对ENSO响应存在明显的区内差异,南部地区降水对ENSO事件达到最显著响应比中北部地区迟缓1个月,中北部地区对ENSO的相关显著性强于南部地区。ElNino发生时,降水偏少,4～6月份降水偏少非常明显,与往年相比偏少大约20%左右。LaNina发生时,降水偏多,冬季降水增多尤其明显,其中12月增多20%以上。
There is an obvious warming trend in Ningxia Hui Autonomous Region, China since the 1950s, especially the warming trend has become more and more obvious since the mid-1960s, and the average temperature increases by 0.514℃ in every decade. Ningxia experienced a dry period in recent 4 decades. Precipitation in Ningxia decreases sharply from the mid-1990s comparing with the gradual precipitation increase during the period from the 1980s to the early-1990s. Through power spectrum analysis, it is found that there are 4 periods in precipitation and the ENSO events in Ningxia, i.e., the periods of 14 years, 3.75 years, approximately 2 years and 1.5 years. There is a hysteresis in response of temperature in Ningxia to El Nino events. When the response of temperature lags one year than the occurrence of an El Nino event, they come to the most obvious correlation, and the correlation degree passes the significant level test of 0.001 in the lagging time of 7～18 months, but there is no such hysteresis between temperature and La Nina events. There is also a hysteresis between precipitation and ENSO events, the most obvious response of the hysteresis occurs when precipitation in Ningxia lags four months than the occurrence of an El Nino event and one month than the occurrence of a La Nina event, the correlation between the precipitation anomalies in Ningxia and ENSO is obvious, and both of them pass the significant level test of 0.01. The response of precipitation in Ningxia to ENSO varies greatly, it is the strongest in south Ningxia comparing with that in the central and northern parts of Ningxia. When an El Nino event occurs, the precipitation in Ningxia decreases, especially during the period from April to June. However, the precipitation increases when a La Nina event occurs, especially in winter.
出处
《干旱区地理》
CSCD
北大核心
2005年第2期239-243,共5页
Arid Land Geography
基金
国家自然科学基金项目(40171008)资助
