气候变暖将改变农业气候资源尤其是热量资源的时空分布。本文通过分析西北干旱区67个气象站点的气象数据, 研究了西北干旱区近50年气温、积温、霜冻的变化特征与规律。结果表明, 西北干旱区气温呈上升趋势, 上升幅度为0.33 ℃·10a-1, 高于全国平均水平, 其中北疆增温幅度大于其他地区。年内变化上, 冬季增温幅度最大。近50年, 西北干旱区≥0 ℃、≥10 ℃积温变化率分别为67.8 ℃·10a-1和68.8 ℃·10a-1, ≥0 ℃和≥10 ℃积温持续的时间也呈增加趋势, 其中≥0 ℃积温持续天数的增加主要是由于结束日期的推迟引起的, 而≥10 ℃积温天数的增加主要是因为初始日期的提前。研究区无霜期呈增加趋势, 主要表现为初霜日的延迟和终霜日的提前, 其趋势分别可达2 d·10a-1和 1.4 d·10a-1, 前者贡献略大。西北干旱区初霜出现日期的年际波动小于终霜日, 终霜出现日期晚于≥10 ℃积温开始日期约10 d, 且气温变暖的趋势并没有引起这一状况的改变, 而多数站点≥10 ℃积温结束日期早于初霜开始日期。
Climate change has changed agro-climatic resources, especially the degree of heat and the spatio-temporal distributions of resources. Against global warming, temperature has increased in arid Northwest China. Also arid Northwest China has been most influenced by climate change. Using daily meteorological data from 67 stations in arid Northwest China, this paper analyzed change patterns and trends of temperature, accumulated temperature, frost over the period for 1961-2011. The results showed that in the arid northwest region, temperature increased at 0.33 ℃·10a-1, higher than the national average. The warming trend in Northern Xinjiang was larger than in other areas and winter season having the highest yearly variation in temperature. Accumulated temperature higher than 0 ℃ and 10 ℃ increased by 67.8 ℃·10a-1 and 68.8 ℃·10a-1. Accumulated temperature duration also increased over the 1961-2011 period. The increased days with ≥0 ℃ and ≥10 ℃ accumulated temperature were mainly caused by the delayed ending dates and the earlier initial dates, respectively. In the study area, there was delayed first frost, earlier last frost and lengthened frost free period. The rates of change in the first and last frost were 2 d·10a-1 and 1.4 d·10a-1, respectively. In the region, the longer frost-free period was mainly driven by delayed first frost. Inter-annual fluctuation in the first frost was less than that in the last frost in the arid Northwest China. The last frost date was more or less 10 days later than it used to be; even though climate warming caused no change in frost condition. Mostly, the last date of ≥10 ℃ accumulated temperature occurred earlier than the first frost date.