Improvement of Fine-mesh Numerical Meteorological Modeling

研究人员将研究大气科学和海洋科学数值模拟中一个基本但尚未解决的问题——当数值模型中网格尺寸的尺度(d)与含能湍流(L)的尺度相同时，亚网格尺度湍流数值模型的适当表述。目前的中尺度模型倾向于包含多年前提出的涡流扩散模型，当d远远大于l时，这种近似是足够的。然而，研究小组的初步工作表明，当d接近l时，需要新的公式。研究人员将首先在高分辨率大涡模拟（LES）模型中安装新的公式。他们将把得到的标量和速度统计数据与大气边界层（ABL）模拟的标准公式和新公式进行比较。由于两组结果不应该有显著差异，因此这提供了一个模型验证测试。然后，研究人员将把新的公式安装到一个先进的中尺度模型中，并研究对湿对流模拟的影响。他们还将继续模拟ABL流动。目标是记录d接近l时新模型的性能。这项工作预计将影响网格尺寸与湍流尺度相同的应用中的数值模拟。这种情况发生在从区域天气预报到强风暴和飓风模拟等应用的高分辨率气象模拟中。

The investigators will attack a basic but unsolved problem in numerical modeling in the atmospheric and oceanic sciences -the proper formulation in a numerical model of the subgridscale turbulence when the scale of the grid size in the numerical model (d) is of the order of the scale of the energy-containing turbulence (L). Current mesoscale models tend to contain eddy-diffusivity models of the type proposed many years ago and this approximation was adequate when d was much greater than L. Preliminary work by the research team has revealed, however, that new formulations are required as d approaches L. The investigators will first install the new formulation in a high-resolution large eddy simulation (LES) model. They will compare the scalar and velocity statistics obtained with the standard and new formulation in atmospheric boundary-layer (ABL) simulations. Since the two sets of results should not be significantly different, this provides a model validation test.The investigators will then install the new formulation into an advanced mesoscale model and study the impact on simulations of moist convection. They will also continue the simulations of ABL flows. The goal is to document the performance of the new model as d approaches L.The work is expected to impact numerical modeling in applications where the grid mesh size is of the order of the scale of the turbulence. This occurs in high resolution meteorological modeling in applications ranging from regional weather prediction to simulations of severe storms and hurricanes.