吉林省季节冻土冻结深度变化及对气候的响应

为了掌握季节冻土冻结深度的变化对气候的响应，利用1961-2015年吉林省46个气象站的逐日平均气温、地表温度、积雪深度、冻土冻结深度等数据，采用线性倾向估计、突变分析等方法，研究了吉林省季节冻土冻结深度的时空演变规律及其与气温、积雪的关系。结果表明：吉林省季节冻土最大冻结深度呈由西向东逐渐减小的空间分布特征，绝大多数站最大冻结深度呈减小趋势。基本上在10月开始冻结，次年3月达到最深，6月完全融化。西部冻土冻结深度变幅较大，其次是中部，东部最小。1961-2015年季节冻土最大冻结深度以-5.8 cm·（10a）^-1的速率显著减小（P<0.01）。最大冻结深度基本上呈逐年代减小的趋势，从20世纪90年代开始，最大冻结深度明显减小。最大冻结深度在1987年发生了突变，突变后平均最大冻结深度比突变前平均最大冻结深度减小了22.2 cm。通过分析气温和积雪深度对冻结深度的影响，认为冻土冻结深度对气温变化较为敏感，绝大多数站最大冻结深度与平均气温呈负相关关系。在年际变化上，气温的上升是最大冻结深度减小的主要原因。在季节冻土稳定冻结期，积雪深度超过10 cm，保温作用逐渐变强；当积雪深度达到20 cm时，保温作用显著，冻土冻结深度变浅。

The change of frost depth of seasonally frozen soil and its response to climate change in Jilin Province

In order to understand the response frost depth of seasonally frozen soil to climate change, based on the meteorological data about daily air temperature, surface temperature, snow cover depth and frost depth from 46 meteorological stations in Jilin Province from 1961 to 2015, the spatial-temporal distribution of frost depth of seasonally frozen soil in Jilin Province and its response to air temperature and snow cover were studied through the method of linear tendency estimation and abrupt change analysis. The result showed that the maximum frost depth decreased gradually from west to east, the maximum frost depth of most stations showed a downward trend. Frozen soil occurred mainly from October to June, and the annual maximum frost depth almost always occurred in March. The frost depth varied greatly in the west, followed by the middle and the east. From 1961 to 2015, the maximum frost depth had decreased significantly at a rate of -5.8 cm·(10a)^-1. The maximum frost depth had basically decreased years by years. Since the 1990s, the maximum frost depth has decreased significantly. The maximum frost depth changed abruptly in 1987, and then decreased by 22.2 cm. The frost depth was sensitive to air temperature, and the maximum frost depth of most stations was negatively correlated with average air temperature. In terms of annual variation, the rise of temperature was the main reason for the decrease of maximum frost depth. During the stable frost period of seasonally frozen soil, the ground surface was covered with snow; when the snow depth exceeded 10 cm, the effect of heat preservation become stronger gradually; when the snow depth reached 20 cm, the effect of heat preservation was more significant and the frost depth was lesser.