辽宁省积雪对自动气象站观测地气温差的影响

利用1971—2016年辽宁省61个气象站气温、地表温度、积雪日数和积雪深度资料,分析了积雪的保温作用及其对地气温差的影响。结果表明：更换自动站前后地表温度观测方式的差异导致地气温差显著增大,地气温差的增大程度受所在区域积雪日数、积雪深度的影响显著。在积雪期较长、积雪较厚的地区,积雪引起反照率增大,使得雪面温度降低,导致雪气温差减小,而雪的保温作用使得地气温差显著增大。因此,更换自动站前地（雪）气温差与积雪日数呈显著负相关,而更换自动站后地气温差与积雪日数呈显著正相关。各台站之间地气温差随积雪深度的变化系数差异较大,为0.045~0.858 ℃?cm^-1,在年平均积雪日数＜40 d、年平均极端积雪深度＜10 cm的区域,积雪的保温作用随积雪深度增大而显著增大;在年平均积雪日数＞40 d、年平均极端积雪深度＞10 cm的区域,10 cm以下的积雪对土壤保温作用随积雪深度增大显著,当积雪深度＞10 cm后,其保温作用随积雪深度增大的幅度明显减小。

Effect of snowcover on ground-air temperature difference observed by automatic weatherstations in Liaoning Province

Based on airtemperature, ground temperature, snow cover duration and snow cover depth recordsfrom 61 weather stations in Liaoning Province from 1971 to 2016,the effect of snow cover on ground-air temperaturedifference were analyzed. Theanalyses show that the difference of ground temperature caused by differentobservation ways before and after replacement of automatic weather stationplays a dominant role for ground-air temperature difference increasingsignificantly; ground-air temperature difference change was influencedby snow cover duration and snow cover depth obviously. In thearea with long snow cover duration, snow cover increases the albedo, resultingin snow cover surface temperature decreasing and snow-air temperaturedifference increasing. Besides, due to the insulating effect of snow on theground, ground-air temperature difference increases significantly. Therefore, ground(snow)-air temperature difference has a negative correlation with snow cover duration before replacement of automatic weather station, and ground-air temperaturedifference has a positive correlation with snow cover duration after the replacement.Variation coefficients of daily mean ground-air temperature difference withdaily snow depth changes between 0.045-0.858 ℃·cm^-1 from station tostation. In the area where annual snow cover duration is less than 40 days and snowcover depth is below 10 cm, the heat preservation effect of snow increasessignificantly with the increase of snow depth. In the area where annual snowcover duration is more than 40 days and maximum snow cover depth is above 10 cm,when snow cover depth below 10 cm, the heat preservation effect of snow has increasedsignificantly with the increase of snow depth, however, when snow cover depthabove 10 cm, the heat preservation effect of snow has increased slowly with theincrease of snow depth.