Variability and Changes of Unfrozen Soils Below Snowpack
Variability and Changes of Unfrozen Soils Below Snowpack
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DOI：
10.1029/2021gl095354
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发表时间：
2022
影响因子：
5.2
通讯作者：
Lun Gao;A. Ebtehaj;J. Cohen;J. Wigneron
中科院分区：
文献类型：
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作者：
Lun Gao;A. Ebtehaj;J. Cohen;J. Wigneron
本文利用四组再分析资料和地面观测资料发现，北半球积雪平均有30%的时间经历未冻结的底层土壤。结果表明，冻土发生的概率与积雪类型有关，短暂积雪发生的概率最大，其次是海雪和草原积雪。基于再分析资料的结果表明，未冻土地区的季节演变与积雪范围不同步，表现出亚年度双峰型特征，在4月和10月出现两个年最大值。年际趋势分析表明，在过去几十年中，春季雪的萎缩伴随着未冻结底层土壤比例的增加，在以苔原和泰加雪为主的极地气候体系中尤为明显。这些发现表明，由于全球变暖，积雪的底部融化可能已经增加。
Using four reanalysis data sets and ground‐based observations, this paper uncovers that on average, 30% of the time, Northern Hemisphere snow cover experiences unfrozen bottom soil. It is demonstrated that the probability of occurrence of unfrozen soils is correlated with the snow types and is maximum over the ephemeral followed by the maritime and prairie snow. The results based on reanalysis data unveil that the seasonal evolution of the unfrozen soil areas is not synchronous with the snow cover extent and exhibits sub‐annual bi‐modality with two annual maxima in April and October. Interannual trend analyses indicate that shrinkage of spring snow in the past few decades has been accompanied by an increase in the proportion of unfrozen bottom soils, more significantly over polar climate regimes dominated by the tundra and taiga snow. The findings imply that the snowpack basal melting could have increased due to global warming.