雪盖影响下活动层变化的统计预报模式

A Statistical Forecasting Model of the Variations in Active Layer Influenced by Snow Cover: Examplified by a Study in Northeastern China

季节性稳定积雪对冻土的温度状况和活动层的变化有重要影响。但在以往的冻土温度场计算中,因引进雪盖影响使计算变得非常复杂,再加之从气象站获得的资料缺乏雪盖密度和导热系数方面的实测资料,在实际计算中常常忽略了雪盖的影响。本文以东北三省和内蒙古部分地区71个气象台站30a(1951～1980)观测资料的多年平均值为基础,选择气温、气温年较差、1月份的最大积雪厚度为预报的特征量,以活动层底板的温度为预报的目标量,进行多元线性回归分析,建立了考虑雪盖影响的预报活动层底板温度变化的统计预报模型。经用5个具有代表性的台站后10a(1981～1990)的观测资料所作的验证性预报的误差比较表明,如果能对未来气候变暖的各种情形做出较为符合实际的预测,以这一模型为基础,则可对冻土活动层对未来气候变暖的响应程度在已有经验的基础上做出定量的回答。

Seasonal stable snow cover has significant influence on the temperature regime of frozen ground and the variation in the active layer. Nevertheless the calculation of temperature field in the frozen ground may become very complex when taking the influence of snow cover into consideration. Owing to the lack of density and thermal conductivity data at meterological stations, the influence of the snow cover is always neglected in computation of the temperature field in the frozen ground.Based on the yearly mean values observed at 71 meterological stations in the northeastern three provinces and the partial area of Inner Mongolia of China in the past 30 years (1951-1980), choosing air temperature, amplitude of air temperature and the maximum snow depth in January as the independent variables, and taking the temperature at active layer table as forecasting objective variable, a model which forecasts the temperature variation influenced by the snow cover at the active layer table is developed by the linear multi regression method in this paper. Verification of the forecasting model has been made by the observed data over the latter ten years (1981-1990) at the representative five stations, the comparison of errors shows that if various climatic warming scenarios in the future can be predicted, quantitative answers for response extent of the active layer to the coming climatic warming will be given on the basis of present experience.