新疆阿勒泰地区积雪变化特征及其对冻土的影响

依据新疆阿勒泰地区气象台站观测的1961-2011年最大积雪深度、 积雪日数资料与安装在库威水文站的雪特性站观测的积雪密度资料, 讨论了新疆阿勒泰地区积雪的变化特征. 结果表明: 阿勒泰地区近50 a来最大积雪深度变化均呈显著增加的趋势, 且西部最大积雪深增加趋势大于东部. 积雪日数变化较为复杂, 在空间分布上有差异, 位于最东面的富蕴和青河50 a来积雪日数呈减少趋势, 其余各站均为增加趋势, 且东部历年平均积雪日数略高于西部, 积雪日数的增加趋势比最大积雪深度增长得平缓. 2011年8月-2012年9月在阿勒泰额尔齐斯河上游库威水文站架设的雪特性站观测资料表明, 在额尔齐斯河源头高山区冬季积雪主要是空心化的密实化过程, 升华可能是其主要的物质损失过程, 引起升华的主要气象要素是气温、 风速和水汽压. 各站月最大冻结深度与海拔关系较为密切, 随海拔的增加而增大. 积雪20 cm厚是积雪对下伏土壤冻结影响的一个界限, 积雪厚度超过20 cm就有一定的保温作用; 积雪超过40 cm时, 气温变化对下伏土壤冻结的影响保持稳定, 冻结深度也达到稳定值; 但当积雪厚度超过70 cm之后, 冻结深度会再次发生变化, 可能是由于地温从下向上的影响或地温不能与气温交换而产生的又一次变化.

Changes in Snow Covers during 1961-2011 and Its Effects on Frozen Ground in Altay Region,Xinjiang

Based on the data of the maximum snow depth and the snow days of 7 meteorologicalstations in Altay region from 1961 to 2010 and the snow density from November 2011 to April2012 on the snow characteristics observations station in Kuwei Hydrological Station, Xinjiang, the characteristics of snow cover change were analyzed, the results showed that the maximum snow depth is on a significant increasing trend, and the trend of the maximum snow depth in the western is greater than that of in the eastern. There are differences in the change of snow days because of the spatial distribution. The snow cover days tended to decrease in Fuyun and Qinghe stations, which are located in the eastern Altay region. That of the other 5 stations is on an increasing trend. The average snow cover days in eastern is slightly more than that of in western Altay region. The data of the snow density shows the snow cover process in winter in alpine areas is a hollow densification process; the sublimation may be a process of snow mass losses, which is caused by temperature, wind speed and vapor pressure. There is a closer relationship between the monthly maximum freeze depth and altitude, but not with latitude. When the depth of snow cover is more 20 cm, it haveinsulation for the underlying frozen soil, and if it is more than 40 cm, its effects is stable on frozen ground, but when snow cover depthis exceeding to 70 cmand more, the freezing depth will change again, which may be caused by the ground temperature.