Effects of water clarity on lake stratification and lake-atmosphere heat exchange
Effects of water clarity on lake stratification and lake-atmosphere heat exchange
复制标题
DOI：
10.1002/2014jd022938
复制
发表时间：
2015-08-16
影响因子：
4.4
通讯作者：
Nordbo, Annika
中科院分区：
文献类型：
--
作者：
Heiskanen, Jouni J.;Mammarella, Ivan;Nordbo, Annika
最近的进展，包括湖泊子程序在数值天气预报（NWP）模式，导致更准确的预报。在湖泊模型中，一个基本参数是水的透明度，通过消光系数K-d进行参数化，通常使用全局常数值。我们使用直接涡动协方差通量和基本的气象测量，再加上湖水温度和透明度测量从北方湖泊估计两个湖泊模型，湖和FLake的性能。这些模型代表了NWP中广泛使用的两个1-D建模框架。结果表明，当K-d小于0.5m（-1）时，湖泊模型对K-d的变化非常敏感。热分层的进展强烈依赖于K-d。在暗水模拟的混合层较浅，长波和湍流热损失较高，因此平均水柱温度低于清水模拟。因此，水透明度的变化也会影响冰盖的形成。更复杂的湖模拟季节性温跃层加深，而它几乎保持不变，在夏季的Flake模型。两种模式都高估了地表水温约1摄氏度和潜热通量> 30%，但热储存和感热通量的变化都得到了充分的模拟。我们的结果表明，至少对于腐植型湖泊，可以使用特定于湖泊但不依赖于时间的K-d恒定值，并且K-d的全球绘图在湖泊相对清晰的地区最有益，例如，在高海拔的湖泊里
Recent progress of including lake subroutines in numerical weather prediction (NWP) models has led to more accurate forecasts. In lake models, one essential parameter is water clarity, parameterized via the light extinction coefficient, K-d, for which a global constant value is usually used. We used direct eddy covariance fluxes and basic meteorological measurements coupled with lake water temperature and clarity measurements from a boreal lake to estimate the performance of two lake models, LAKE and FLake. These models represent two 1-D modeling frameworks broadly used in NWP. The results show that the lake models are very sensitive to changes in K-d when it is lower than 0.5m(-1). The progress of thermal stratification depended strongly on K-d. In dark-water simulations the mixed layer was shallower, longwave and turbulent heat losses higher, and therefore the average water column temperatures lower than in clear-water simulations. Thus, changes in water clarity can also affect the onset of ice cover. The more complex LAKE modeled the seasonal thermocline deepening, whereas it remained virtually constant during summer in the FLake model. Both models overestimated the surface water temperatures by about 1 degrees C and latent heat flux by >30%, but the variations in heat storage and sensible heat flux were adequately simulated. Our results suggest that, at least for humic lakes, a lake-specific, but not time-depending, constant value for K-d can be used and that a global mapping of K-d would be most beneficial in regions with relatively clear lakes, e.g., in lakes at high altitudes.