积雪对南极冰盖自动气象站气温观测影响的研究

CORRECTION OF SNOW ACCUMULATION IMPACTED ON AIR TEMPERATURE FROM AUTOMATIC WEATHER STATION ON THE ANTARCTIC ICE SHEET

随着冰盖表面雪的累积或消融,自动气象站(AWS)传感器相对地表的高度随之发生变化,故所记录的观测资料不能直接反映相对地表固定高度上的气象参数。为了使南极冰盖上AWS所获取的气象资料具有可靠性,在积累率对AWS观测气温影响的基础上,将东南极冰盖上中山站至DomeA断面3个AWS的连续观测气温修正到相对于雪表面的某一真实高度上。结果表明:(1)DomeA,Eagle和LGB69年平均1m气温分别为-53.19℃,-41.33℃和-26.29℃,年平均积累率分别为0.11m、0.30m和0.49m,对应的1m气温年平均修正量分别为0.34℃、0.29℃和0.35℃,2m和4m气温的年平均修正量均小于0.1℃;(2)积累率变化对离地表最近层次上的气温影响最大,越往上层影响越小;(3)气温的修正量大小与积累率并非成简单的正比关系,它与气温本身的季节变化特征以及局地近地表逆温强度有很大的关系。气温的平均修正量冬季为正,夏季修正量的正负由局地是否存在逆温决定,修正量值的大小主要由逆温强度和积累率决定。

The heights of the Automatic Weather Station （AWS） sensors are nominal, which change with the snow accumulation or ablation, over the Antarctic ice sheet. Therefore, the measured data can not be used directly. In this study, air temperatures from three AWSs, deployed on the traverse route from Zhongshan station to Dome A on East Antarctica ice sheet, are corrected to a certain real height relative to the snow surface with the impacts of snow accumulation, to improve the authenticity and representativeness of the observation data from AWS. The results showed that （ 1 ） the average accumulation at Dome A, Eagle and LGB69 is approximately 0.11 m, 0.30 m and 0.49 m snow per year, and the corresponding annual mean air temperature difference at 1 m height between corrected and measured is 0.34 ℃, 0.29 0（2 and 0.35 ℃, respectively. The values are less than 0.1 ℃ at 2 m and 4 m heights. （2） The impact on air temperature from accumulation is decreasing with the height from the surface. （3） The relationship between air temperature correction and accumulation is not a simple direct proportion. It also relates to the characteristics of air temperature seasonal variation and the intensity of the local surface inversion. （4） The average air temperature correction is almost positive except in summer without inversion at times. The magnitude of it is mainly determined by accumulation and the intensity of surface inversion.