Testing the Unified System of Equations in Atmospheric Models

根据这项赠款进行的研究将开发和测试一个新的全球非静力大气模型方程系统。 目前的全球大气模式假定空气运动是流体静力学的，这是一个适当的假设，只要模式的网格间距是几十到几百公里。 但是，计算能力的提高导致了人们对具有更高分辨率（从1公里到10公里）的全球“云解析”大气模型的兴趣，以便可以解析云尺度上发生的非静力运动。 这种模式被认为是研究各种多尺度大气现象的适当工具，并解决了由于对流参数化在静力模式中出现的问题。 对于全球流体静力模式，有一个标准形式的运动方程，一般称为“原始方程”，但目前还没有一套标准化的非流体静力全球模式方程。 本项目的工作将基于统一方程系统（UN）开发和测试模型。 UN系统适用于全球域，允许气象学感兴趣的非静力学运动，同时过滤掉声波，否则会使大气运动的数值模拟复杂化。 这项工作的目标是测试联合国系统，并将其与非静力学全球模拟的替代方程组进行比较，包括滞弹性系统，伪不可压缩系统和可压缩系统。这项工作将通过促进下一代模型的开发来产生更广泛的影响，用于天气和气候的模拟和预测。

Research conducted under this grant will develop and test a new system of equations for global nonhydrostatic atmospheric models. Current global atmospheric models assume that air motions are hydrostatic, which is an appropriate assumption provided that the grid spacing of the model is tens to hundreds of kilometers. But increases in computing power have led to interest in global "cloud resolving" atmospheric models with much higher resolutions, from 1 to 10 kilometers, so that the nonhydrostatic motions occurring on the cloud scale can be resolved. Such models are considered appropriate tools for studying a variety of multiscale atmospheric phenomena, and resolve the problems that arise due to the parameterization of convection in hydrostatic models. For global hydrostatic models there is a standard form of the equations of motion, generally referred to as the "primitive equations", but a standardized set of equations for nonhydrostatic global models does not presently exist. Work in this project will develop and test models based on the Unified System (UN) of equations. The UN system is applicable on a global domain and allows nonhydrostatic motions of meteorological interest while filtering out sound waves, which would otherwise complicate the numerical simulation of atmospheric motions. The goal of the work is to test the UN system and compare it against alternative equations sets for nonhydrostatic global modeling, including the anelastic system, pseudo-incompressible, and the compressible systems.The work will have broader impacts by contributing to the development of next-generation models to be used for the simulation and prediction of weather and climate.