Characterizing and Constraining Uncertainty Associated with Surface and Boundary Layer Turbulent Fluxes in Simulations of Lake-Effect Snowfall
Characterizing and Constraining Uncertainty Associated with Surface and Boundary Layer Turbulent Fluxes in Simulations of Lake-Effect Snowfall
复制标题
湖泊效应降雪模拟中与表面和边界层湍流通量相关的不确定性的表征和约束
DOI：
10.1175/waf-d-19-0153.1
复制
发表时间：
2019
影响因子：
2.9
通讯作者：
J. Lenters
中科院分区：
文献类型：
--
作者：
J. Minder;W. M. Bartolini;C. Spence;N. Hedstrom;P. Blanken;J. Lenters
湖效应雪（LeS）风暴是由冷空气流过相对温暖的水面引起的强烈湍流表面层（SL）和行星边界层（PBL）热量和湿气通量驱动的。为了研究模拟 LeS 对 SL 和 PBL 湍流参数化的敏感性，使用天气研究和预报模型对苏必利尔湖和安大略湖的顺风两个主要风暴进行了高分辨率模拟。进行了多方案和参数敏感性实验。湖上通量和顺风降雪的测量用于评估模拟。与之前的研究一致，LeS 对 SL 和 PBL 参数化选择非常敏感。根据所使用的方案，模拟降水累积量最多可相差 2 倍。 SL 方案之间的差异是这种敏感性的主要来源。 SL 方案之间的显热和潜热参数化表面通量的差异可能超过 100 W m−2。这些通量的大小与顺风降水量相关。 PBL 方案之间的差异起着次要作用，但对风暴形态有显着影响。许多方案对湖上通量和顺风降雪进行了可靠的模拟。然而，产生最大表面通量的方案产生的通量和降水积累相对于观测值偏高。对于详细研究的两个 SL 方案，不切实际的大通量可归因于参数选择：中性稳定性湍流普朗特数和用于定义水面粗糙度计算中的状态的阈值摩擦速度。
Lake-effect snow (LeS) storms are driven by strong turbulent surface layer (SL) and planetary boundary layer (PBL) fluxes of heat and moisture caused by the flow of cold air over relatively warm water. To investigate the sensitivity of simulated LeS to the parameterization of SL and PBL turbulence, high-resolution simulations of two major storms, downwind of Lakes Superior and Ontario, are conducted using the Weather Research and Forecasting Model. Multischeme and parameter sensitivity experiments are conducted. Measurements of overlake fluxes and downwind snowfall are used to evaluate the simulations. Consistent with previous studies, LeS is found to be strongly sensitive to SL and PBL parameterization choices. Simulated precipitation accumulations differ by up to a factor of 2 depending on the schemes used. Differences between SL schemes are the dominant source of this sensitivity. Parameterized surface fluxes of sensible and latent heat can each vary by over 100 W m−2 between SL schemes. The magnitude of these fluxes is correlated with the amount of downwind precipitation. Differences between PBL schemes play a secondary role, but have notable impacts on storm morphology. Many schemes produce credible simulations of overlake fluxes and downwind snowfall. However, the schemes that produce the largest surface fluxes produce fluxes and precipitation accumulations that are biased high relative to observations. For two SL schemes studied in detail, unrealistically large fluxes can be attributed to parameter choices: the neutral stability turbulent Prandtl number and the threshold friction velocity used for defining regimes in the overwater surface roughness calculation.