石羊河流域季节性冻土的时空分布及对气温变化的响应

The Spatial-Temporal Distribution State of Seasonal Frozen Soil and Responses to Temperature Change in the Shiyang River Basin

利用1961—2010年石羊河流域4个气象站点的冻土深度、冻土日数和气温观测数据以及邻近地区气象站点冻土数据，采用气候统计学分析方法，对石羊河流域最大冻土深度和冻土日数的时间演变、空间分布及与气温的关系进行了分析。结果表明：石羊河流域年代、年最大冻土深度和冻土日数呈显著减少趋势，减少速率分别为4．537cm／10a、6．001d／10a，均通过了a=0．01的显著性水平检验。年最大冻土深度和冻土日数的时间序列分别存在7～8a和8～9a的准周期变化，并发生了突变。冻土主要出现在11月至次年3月，年最大冻土深度几乎都出现在1月和2月，年冻土日数以12月和1月最多。石羊河流域冻土的空间分布与海拔高度、地表植被、地层岩性、土层含水量等局域性因素有关。石羊河流域与冻土同期的年平均气温呈显著升高趋势，上升的速率为0．553℃／10a。、年最大冻土深度和冻土日数与平均气温呈极显著负相关，其相关系数分别为-0．7486、-0．8058，气温每升高1℃，冻土深度减小9．3cm，冻土日数减少8．3d；冻土深度和气温具有相同的周期变化，冻土日数的周期变化比气温滞后1a，气温随时间变化对冻土深度和冻土日数随时间变化具有显著负作用。冻土深度的减小和冻土日数的减少可能是对气温升高的响应。

Based on the depth and number of days of frozen soil and temperature across four meteorological stations in the Shiyang River Basin from 1961-2010, the temporal evolution and spatial distribution of maximum depth and days of frozen soil were analyzed. The results show that the maximum depth and number of days of frozen soil have declined by 4.537 cm/10a and 6.001 d/ 10a, respectively. A time series of maximum depth and frozen soil days have seven to eight years and eight to nine years quasi-periodic variation respectively. Frozen soil occurs mainly from November to March. The annual maximum frozen depth almost always occurs in January and February, the number of frozen days is the greatest in December and January. The spatial distribution on depth and frozen soil days are related to altitude, vegetation, formation lithology and soil moisture. Annual mean temperature of the frozen period has increased significantly across the basin at 0.553℃/10a. The maximum depth and days of frozen soil are negatively correlated with average temperature and the correlation coefficients are-0.7486 and-0.8058, respectively. The depth of frozen soil declined by 9.3 cm and the days of frozen soil by 8.3 d if the temperature increased 1 ℃. Periodic variation in the depth of frozen soil and temperature are the same. Annual variation in temperature has a remarkable negative effect on annual variation of depth and the number of days of frozen soil.