On the exchange of sensible and latent heat between the atmosphere and melting snow
On the exchange of sensible and latent heat between the atmosphere and melting snow
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DOI：
10.1016/j.agrformet.2018.01.028
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发表时间：
2018-04
影响因子：
6.2
通讯作者：
P. Stoy;E. Peitzsch;David J. A. Wood;Daniel Rottinghaus;G. Wohlfahrt;M. Goulden;H. C. Ward
中科院分区：
文献类型：
--
作者：
P. Stoy;E. Peitzsch;David J. A. Wood;Daniel Rottinghaus;G. Wohlfahrt;M. Goulden;H. C. Ward
融雪期间的雪能平衡很难测量，但对于预测积雪地区的水量至关重要。融雪能量平衡的稳健简化可以帮助我们了解气候变化中的水资源。迄今为止的研究表明，如果大气蒸气压 (ea) 和温度 (Ta) 之和等于一个常数，则融化的积雪和大气之间的净湍流通量 (FT) 可以忽略不计，但尚不清楚这种情况在不同地点发生的频率。在这里，我们对 FLUXNET2015 数据库中 11 个站点的 59 个融雪周期内的积雪能量平衡的贡献进行了量化，并对瑞典阿比斯库附近的亚北极苔原的融雪进行了详细分析。在阿比斯库现场，我们调查了显热通量 (H) 和潜热通量 (λE) 具有（大约）相等但符号相反的情况的发生频率，因此，如果这些项的总和 FT 在融雪期间可以忽略不计。在不到 50% 的融雪期间，大约等于 -λE，并且 FT 在阿比斯库的融雪能量平衡中很少是一个微不足道的项。原因是观察到的ea和Ta之间的关系大致与“平等线”正交，在该“平等线”上，He等于-λE，在融化期间，温度升高通常会导致更大的ea。这种关系在 FLUXNET2015 数据库中的各个地点和不同地点的融化期内都成立，其中 FT 占可用于融化雪的能量 Qm 的不到 20%，在此研究的 44% 的融雪期内。FT/Qm 与融化期间的平均值显着相关，但与平均值 Ta 无关，并且当平均值 ca 时，FT 往往接近 0W m−2。 0.5kPa.FT 可能成为全球许多地区融雪能量平衡中越来越重要的术语，因为预计气温升高将导致在净辐射 (Rn) 较低的条件下，雪在一年中融化得更慢、更早。 Ameriflux 等涡流协方差研究网络必须提高观察冷季过程的能力，以增强我们对气候变化中水资源和地表大气交换的了解。
The snow energy balance is difficult to measure during the snowmelt period, yet critical for predictions of water yield in regions characterized by snow cover. Robust simplifications of the snowmelt energy balance can aid our understanding of water resources in a changing climate. Research to date has demonstrated that the net turbulent flux (FT) between a melting snowpack and the atmosphere is negligible if the sum of atmospheric vapor pressure (ea) and temperature (Ta) equals a constant, but it is unclear how frequently this situation holds across different sites. Here, we quantified the contribution ofFTto the snowpack energy balance during 59 snowmelt periods across 11 sites in the FLUXNET2015 database with a detailed analysis of snowmelt in subarctic tundra near Abisko, Sweden. At the Abisko site we investigated the frequency of occurrences during which sensible heat flux (H) and latent heat flux (λE) are of (approximately) equal but opposite sign, and if the sum of these terms,FT, is therefore negligible during the snowmelt period.Happroximately equaled -λEfor less than 50% of the melt period andFTwas infrequently a trivial term in the snowmelt energy balance at Abisko. The reason is that the relationship between observedeaandTais roughly orthogonal to the “line of equality” at whichHequals -λEas warmerTaduring the melt period usually resulted in greaterea. This relationship holds both within melt periods at individual sites and across different sites in the FLUXNET2015 database, whereFTcomprised less than 20% of the energy available to melt snow,Qm, in 44% of the snowmelt periods studied here.FT/Qmwas significantly related to the meaneaduring the melt period, but not meanTa, andFTtended to be near 0 W m−2wheneaaveragedca. 0.5 kPa.FTmay become an increasingly important term in the snowmelt energy balance across many global regions as warmer temperatures are projected to cause snow to melt more slowly and earlier in the year under conditions of lower net radiation (Rn). Eddy covariance research networks such asAmerifluxmust improve their ability to observe cold-season processes to enhance our understanding of water resources and surface-atmosphere exchange in a changing climate.