1961-2010年新疆季节性最大冻土深度对冬季负积温的响应

基于新疆96个气象站1961-2010年的逐日平均气温和冻土深度资料,使用线性趋势分析、Mann-Kendall检测以及基于ArcGIS的混合插值法,对新疆冬季负积温和季节性最大冻土深度的时空变化及其相互关系进行了分析. 结果表明：50 a来,新疆冬季负积温绝对值总体以51.5 ℃·d·(10a)^-1的倾向率减少,并于1985年发生了突变. 受其影响,最大冻土深度以-3.5 cm·(10a)^-1的倾向率减小,也于1988年发生了突变. 就全疆平均而言,1961-2010年,负积温每减少100 ℃·d,最大冻土深度将减小4.6 cm.但这种影响区域性差异显著,最大冻土深度减小量呈现"南疆小,北疆和天山山区大"的格局.南疆大部最大冻土深度对负积温变化的响应相对较敏感,一般为-3.0~-12.7 cm·(100℃·d)^-1;北疆和天山山区响应的敏感性较小,多为0.0~-4.9 cm·(100℃·d)^-1,其成因很可能是北疆和天山山区冬季积雪较南疆厚,较厚的积雪所具有的低导热性和较大的容积热容减小了气候变暖对冻土热状况的影响.负积温减少、最大冻土深度变浅将改变土壤的水热物理性状,加剧土壤干化、草场退化以及土地的荒漠化,对新疆脆弱的生态环境产生更加不利的影响.因此,应根据最大冻土深度对负积温变化响应的实际,采取趋利避害的技术措施积极应对.

Response of the Maximum Depth of Seasonal Freezing to the Cumulated Negative Temperature in Xinjiang

Based on daily mean air temperature and frozen soil depth data of 96 meteorological stations in Xinjiang from 1961 to 2010, the fundamental spatial-temporal change characteristics of cumulated negative temperature and maximum frozen soil depth and the relationship between them were analyzed by using the methods of linear regression, Mann-Kendall test and mixed spatial interpolation technology based on ArcGIS. The main results are as the follows: In the 50 years from 1961 to 2010, the cumulated negative temperature had significantly decreased, with the rate of 51.5 ℃·d · (10a)^-1, and had a significantly abrupt decreasing in 1985. Affected by this, the maximum frozen soil depth had significantly decreased, with the rate of -3.5 cm·d · (10a)^-1, and had a significantly abrupt decreasing in 1988. When cumulated negative temperature decreases 100 ℃·d, the maximum frozen soil depth will decrease 4.6 cm. The decreasing range of maximum frozen soil depth in South Xinjiang is larger than that in North Xinjiang and Tianshan Mountains. Similar to the cumulated negative temperature in winter, maximum frozen soil depth decrease rate and decrease range before and after the mutations in North Xinjiang and Tianshan Mountains were larger than those in South Xinjiang.