Influence of the seasonal snow cover on the ground thermal regime: An overview
Influence of the seasonal snow cover on the ground thermal regime: An overview
复制标题
DOI：
10.1029/2004rg000157
复制
发表时间：
2005-12
影响因子：
25.2
通讯作者：
Tingjun Zhang
中科院分区：
文献类型：
--
作者：
Tingjun Zhang
年气温循环冷季季节积雪的存在对寒冷地区的地热状况有重要影响。雪具有冷却雪面的高反照率和发射率，倾向于加热雪面的高吸收率，低导热系数使雪层充当绝缘体，以及由于融雪而产生的高潜热，这是一个热沉。积雪对地热状况的总体影响取决于季节性积雪的时间、持续时间、积累和融化过程；季节性积雪的密度、结构和厚度；以及积雪与微气象条件、当地微地形、植被和地理位置的相互作用。在不同的时间尺度上，季节性积雪的降温或变暖影响可能占主导地位。在连续多年冻土区，季节性积雪的影响可导致年平均地面和多年冻土表面温度升高几度，而在不连续和零星的多年冻土区，季节性积雪的缺乏可能是永久冻土发育的关键因素。在季节性冰冻的地面地区，积雪可以大大减少季节性冰冻深度。然而，季节性积雪对季节冻土的影响相对较少，有待于进一步研究。根据深井温度梯度重建的地表温度在过去几个世纪中增加了高达4摄氏度，并被广泛用作古气候变化的证据。然而，仅靠气温的变化不能解释地面温度的变化。季节性降雪条件的变化可能是地面温度上升的重要原因。季节性积雪对土壤温度、土壤冻融过程和多年冻土的影响，对寒冷地区/寒冷季节大气与地面之间的碳交换和水文循环有相当大的影响。
The presence of seasonal snow cover during the cold season of the annual air temperature cycle has significant influence on the ground thermal regime in cold regions. Snow has high albedo and emissivity that cool the snow surface, high absorptivity that tends to warm the snow surface, low thermal conductivity so that a snow layer acts as an insulator, and high latent heat due to snowmelt that is a heat sink. The overall impact of snow cover on the ground thermal regime depends on the timing, duration, accumulation, and melting processes of seasonal snow cover; density, structure, and thickness of seasonal snow cover; and interactions of snow cover with micrometeorological conditions, local microrelief, vegetation, and the geographical locations. Over different timescales either the cooling or warming impact of seasonal snow cover may dominate. In the continuous permafrost regions, impact of seasonal snow cover can result in an increase of the mean annual ground and permafrost surface temperature by several degrees, whereas in discontinuous and sporadic permafrost regions the absence of seasonal snow cover may be a key factor for permafrost development. In seasonally frozen ground regions, snow cover can substantially reduce the seasonal freezing depth. However, the influence of seasonal snow cover on seasonally frozen ground has received relatively little attention, and further study is needed. Ground surface temperatures, reconstructed from deep borehole temperature gradients, have increased by up to 4°C in the past centuries and have been widely used as evidence of paleoclimate change. However, changes in air temperature alone cannot account for the changes in ground temperatures. Changes in seasonal snow conditions might have significantly contributed to the ground surface temperature increase. The influence of seasonal snow cover on soil temperature, soil freezing and thawing processes, and permafrost has considerable impact on carbon exchange between the atmosphere and the ground and on the hydrological cycle in cold regions/cold seasons.