武威市初、终霜日气候特征

Climate Characteristic of First and Last Frost Dates in Wuwei

为了因地制宜,合理调整种植结构和布局,有效利用农业气候资源。利用1961—2014年武威市4个气象站点初、终霜日（最低地温≤0℃）观测资料,采用现代气候诊断分析方法,系统分析了该市年初、终霜日的时空变化特征。结果表明：受海拔高度、地形地势以及植被覆盖情况的影响,在空间分布上,武威市初霜日为山区早于荒漠区早于绿洲平原区,终霜日为山区晚于荒漠区晚于绿洲平原区,各地初、终霜日存在一定的异常性,正常初、终霜日均在60%左右,对农业生产造成危害的偏早和特早初霜日、偏晚和特晚终霜日的概率均在20%左右。在时间变化上,武威市初霜日呈显著推迟趋势,终霜日呈显著提早趋势,霜期呈显著缩短趋势,终霜日提早的幅度比初霜日推迟的幅度更大。初霜日和终霜日的时间序列均分别存在着8～10年和9～11年的准周期变化。初霜日在1998年发生了气候突变,终霜日在1996年发生了气候突变。

Aiming to adjust measures to local conditions,reasonably adjust planting structure and layout,and effectively utilize agricultural climate resources,based on the observation dates of first frost day and last frost day（the minimum ground temperature less than 0 ℃）of 4meteorological stations in from 1961 to 2014over Wuwei,the spatial and temporal variation characteristics of the dates of first and last frost days are analyzed systematically with the climate diagnosis analysis method.The results show that the spatial distribution of the first frost date is the earliest in mountain regions,earlier in desert regions,and the latest in oasis plains in Wuwei;that of the last frost date is the latest in mountain regions,later in deserts and the earliest in oasis plains,because of the influence of altitude,topography,and vegetation cover.First and the last frost dates have certain abnormality in various regions.The occurrence possibility of normal first and the last frost dates is about 60%,and that of the abnormal cases such as the earlier and early frost,later and late frost dates that may cause hazards on agricultural production is all about 20%.First frost date assumes a significantly delayed trend,and last frost date assumes a significantly early trend.Frost period assumes a significantly short trend,and the advanced magnitude of last frost date is greater than the delayed magnitude of first frost date.The time series of first and last frost dates have the quasi-periodic variation of 8to 10 years and 9to 11 years,respectively.First frost date and last frost date have a climate abrupt change in 1998 and in 1996,respectively.