Scaling Issues in the Direct Use of Satellite Data in Mesoscale Model Land-Surface Parameterizations

本项目致力于中尺度大气预报模式中地表的准确表征。研究方法是将亚网格地表参数化与已证实的中尺度大气模式相结合。子网格参数化是专门用来根据卫星数据估计地表特性（如反照率、热和水分通量）的。为了评估该子网格方案的有效性，将把大气-子网格耦合模式的结果与现场观测和远程估算的地表能通量进行比较。模式结果将与大气特性的网格化分析进行比较。此外，还将研究尺度效应对模型系统精度的重要性。这些尺度效应包括(a)模型输出对子网格分辨率的敏感性；(b)用于将大气数据分配到子网格的方法以及如何将计算出的子网格通量传回大气模式的网格；(c)模式输出对大气模式网格和地表子网格方向的敏感性；(d)确定大气模式和子网格分辨率之间的物理合理比例。该项目将为中尺度模拟界提供一种将亚网格变率引入中尺度模式的改进方法，从而改善数值天气预报，从而使中尺度模拟界受益。这项研究也将有利于遥感界，因为许多待研究的尺度问题在地表参数的遥感估计中很重要。卫星导出的地表参数化的改进将提供验证各种数值模拟方案的地表成分所需的尺度通量数据。

This project addresses the accurate representation of the surface in mesoscale atmospheric prediction models. The research methodology is to couple a subgrid land-surface parameterization to a proven mesoscale atmospheric model. The subgrid parameterization is specifically designed to estimate surface properties (e.g., albedo; heat and moisture fluxes) from satellite data. In order to assess the effectiveness of this subgrid scheme, results of the coupled atmospheric-subgrid model will be compared to in-situ observations and remotely-derived estimates of surface energy fluxes. Model results will be compared to gridded analyses of atmospheric properties. In addition, the importance of scale effects on the accuracy of the model system will be investigated. These scale effects include (a) sensitivity of model output to the resolution of the subgrid; (b) the method used to distribute atmospheric data to the subgrid and how calculated subgrid fluxes are transferred back to the atmospheric model's grid; (c) the sensitivity of model output to the orientation of the atmospheric model grid and the surface subgrid; and (d) the determination of a physically reasonable ratio between the atmospheric model and subgrid resolutions.This project will benefit the mesoscale modeling community by providing an improved method for introducing subgrid variability into mesoscale models which should lead to improved numerical weather prediction. This study also will benefit the remote sensing community since many of the scale issues to be investigated are of importance in the remote estimation of surface parameters. Improvements in satellite derived surface parameterizations will provide flux data at scales required to validate the surface component of various numerical modeling schemes.