“Gray Zone” Simulations using a Three-Dimensional Planetary Boundary Layer Parameterization in the Weather Research and Forecasting Model
“Gray Zone” Simulations using a Three-Dimensional Planetary Boundary Layer Parameterization in the Weather Research and Forecasting Model
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在天气研究和预报模型中使用三维行星边界层参数化的“灰色区域”模拟
DOI：
10.1175/mwr-d-21-0164.1
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发表时间：
2021
影响因子：
3.2
通讯作者：
A. Martilli
中科院分区：
文献类型：
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作者：
T. Juliano;B. Kosović;P. Jiménez;M. Eghdami;S. E. Haupt;A. Martilli
在许多地理区域中，生成行星边界层（PBL）特性的准确天气预报是具有挑战性的，这通常是由于复杂的地形或例如陆地特征的水平变化。虽然高性能计算平台的最新进展已经导致数值天气预报（NWP）模式的空间分辨率增加，但许多区域尺度NWP模式的水平网格单元间距（Δ x）目前落入或开始接近灰色区域（即，Δ x ≤ 100 - 1000 m）。在这些网格单元间距下，三维（3D）效应很重要，因为最具活力的湍流涡旋既没有完全参数化（如传统的中尺度模拟），也没有完全解析（如传统的大涡模拟（LES））。鉴于这一建模挑战，我们已经实现了三维PBL参数化的高分辨率中尺度模拟使用天气研究和预报模型。PBL方案是基于梅洛尔和山田提出的代数模型，通过计算湍流动能和动量、热量和水分通量散度来考虑湍流的三维效应。在这项研究中，我们提出了理想化的模拟结果，在灰色区域，说明了在对流条件下使用完全一致的湍流闭合框架的好处。虽然三维PBL方案再现对流功能的演变比传统的一维PBL方案更合适，我们强调需要改进的湍流长度尺度的制定。
Generating accurate weather forecasts of planetary boundary layer (PBL) properties is challenging in many geographical regions, oftentimes due to complex topography or horizontal variability in, for example, land characteristics. While recent advances in high-performance computing platforms have led to an increase in the spatial resolution of numerical weather prediction (NWP) models, the horizontal grid cell spacing (Δ x) of many regional-scale NWP models currently fall within or are beginning to approach the gray zone (i.e., Δ x ≈ 100 – 1000 m). At these grid cell spacings, three-dimensional (3D) effects are important, as the most energetic turbulent eddies are neither fully parameterized (as in traditional mesoscale simulations) nor fully resolved [as in traditional large eddy simulations (LES)]. In light of this modeling challenge, we have implemented a 3D PBL parameterization for high-resolution mesoscale simulations using the Weather Research and Forecasting model. The PBL scheme, which is based on the algebraic model developed by Mellor and Yamada, accounts for the 3D effects of turbulence by calculating explicitly the momentum, heat, and moisture flux divergences in addition to the turbulent kinetic energy. In this study, we present results from idealized simulations in the gray zone that illustrate the benefit of using a fully consistent turbulence closure framework under convective conditions. While the 3D PBL scheme reproduces the evolution of convective features more appropriately than the traditional 1D PBL scheme, we highlight the need to improve the turbulent length scale formulation.