气候变暖背景下祁连山区对流云变化特征分析

利用祁连山区及其周边29个地面气象观测站1961-2000年的云状和气温资料,采用线性趋势分析、相关分析、多项式拟合和墨西哥帽小波分析等方法,分析了祁连山区对流云出现频率的分布及其年代际变化特征,并探讨了与气温变化的关系。结果表明:祁连山区对流云出现频率明显高于河西走廊和柴达木盆地;近40年来,祁连山区增温1.3℃,增温率达0.32℃/10a,自20世纪80年代中期之后,气温上升趋势极为明显;祁连山区对流云的出现频率近40年来减少了近10%,与同期祁连山区显著增温相对应,20世纪80年代中期以后对流云的出现频率呈明显的下降趋势;小波分析表明,在30年以上的时间尺度上,祁连山区气温和对流云出现频率基本为反位相变化。在15、10和5年尺度上,气温和对流云出现频率在20世纪80年代以前为反位相结构,而自80年代以后,呈现出同位相变化结构;祁连山区对流出现频率与气温为显著的负相关关系,在平均气温升高1℃的情况下,祁连山及其周围地区对流云出现频率一致为减少,绝大部地方减少2%～5%,祁连山中部减少最多,减少4%～5.7%。

Change characteristics of convective cloud in the Qilian Mt. region under background of global warming

Based on the climatic data of cloud form and surface air temperature at 29 meteorological stations during 1961-2000 in Qilian Mountain and the surrounding areas,the climatic characteristics of cloud form,its variation features and the relationship between cloud form and air temperature were studied by linear regression analysis,correlation analysis and wavelet transforms using the Mexican Hat Function.The results showed that:⑴The occurrence frequency of convective cloud in the Qilian Mt.Region was higher than Qaidam basin and Gansu corridor.⑵The annual mean air temperature increased 1.3℃ with the increase rate of 0.32 ℃/10a in the Qilian Mt.region over the recent 40 years,especially since the mid-1980's.⑶The occurrence frequency of convective cloud decreased 10% in the Qilian Mt.region over the recent 40 years,especially since the mid-1980's,corresponding to the synchronous remarkable warming.⑷In the time scale of more than 30 years,the occurrence frequency of convective cloud and air temperature present reverse phase changed in Qilian mountain areas.In the time scale of 15 years,10 years and 5 years their characteristics of variations were in opposite phase before 1980's,but in synchronous phase after 1980's.⑸The correlation analysis indicated that there is a obvious negative relation between the occurrence frequency of convective cloud and annual mean air temperature in Qilian Mountain.when the average temperature increased 1℃,the occurrence frequency of convective cloud was found to decrease 2%～5% over the majority region of Qilian mountain area,and decreased by 4%～5.7% mostly over its middle area.