宁夏夏季日数相关要素的变化特征及其对气候变暖的响应

采用1961—2010年宁夏逐日最高气温资料,分区域分析了夏季日数相关要素的变化特征及其对气候变暖的响应.结果表明,各区域夏季日数均有上升趋势,于1997—1998年发生突变,夏季日数上升速率为2.6~3.9 d/10 a,其中引黄灌区最大;日最高气温〉25℃的起始和终止日期分别有提前和推迟趋势,起始日期提前增加了春季发生霜冻的风险性,引黄灌区和南部山区分别有以起始日期显著提前和终止日期明显推迟为特征的延长趋势;中北部地区夏季日数的极端性趋势显著.各要素对气候变暖有不同程度的响应,响应趋势及显著性与各要素变化趋势基本一致;年平均气温每增加1℃,夏季日数增加9.5~11.1 d,南部山区增加最多;日最高气温〉25℃的终止日期对气候变暖最为敏感,其他要素突变时间均滞后于年平均气温的突变时间.

Characteristic of key elements variation of summer day number in Ningxia and its response to climate warming

Using the daily data of extreme high-temperature from 1961 to 2010 in Ningxia,the changes of characteristic and responses of relating factors of summer day number to climate warming were analyzed regionally.The results indicate that the summer day number has ascending trend and have a break around form 1997 to 1998.The ascending coefficients are 2.6 to 3.9 days per 10 years,and the largest is in Yellow River irrigation region.The beginning and ending dates of extreme high-temperature,more than 25 ℃,advances and delays respectively.And then,the earlier of the beginning dates,the heavier of frost risk in spring.The prolong trend for characteristic of beginning date moving up and ending date delay remarkably makes the summer day number prolong in Yellow River irrigation region and southern region in Ningxia respectively.The extremism trend in north-central is more noticeable.Each factor responds to climate warming differently,and the response trend and significance are accord with the change trend of the factor on the whole.The summer days will ascends 9.5 to 11.1 days as annual average temperature increase 1 ℃,which in southern region is remarkable.The ending time of extreme high-temperature which is above 25 ℃ is the most sensitive to climate warming,and other factor’s break point are later than that of the average temperature.