A Rational Approach to Cumulus Parameterization in Large-Scale Models

该项目采用一种独特的方法来开发一种在大尺度天气和气候模式（即任何空间分辨率低到不能直接解决云过程的模式）中表示积云对流的新方法。该项目将深入研究对流与环境的相互作用——对流加热产生的浮力异常会被波浪作用迅速消除，波浪作用产生平均垂直速度，产生足以抵消加热的绝热冷却。作为它的主要作用之一，这种“弱温度梯度垂直速度”使水汽平流。这种认识激发了“测试单元”的发展，其中显式积云系综模型和对流的参数处理将被测试。研究人员将利用这些结果来修改和调整现有的原型积云参数化。然后，这种参数化将用于大尺度模式，以评估其对模拟大气环流特征的影响，如热带东风波和季节内振荡。日循环也将在简化的情况下加以审查。该项目将支持本科生和研究生的研究。

This project takes a unique approach to develop a new method for representing cumulus convection in large-scale weather and climate models (i.e., any models with spatial resolution low enough that they do not resolve cloud processes directly). The project will exploit insights into how convection interacts with its environment -- buoyancy anomalies produced by convective heating are quickly removed by wave action, a process which produces a mean vertical velocity that creates adiabatic cooling just sufficient to counterbalance the heating. As one of its main effects, this "weak temperature gradient vertical velocity" advects moisture. This realization motivates the development of a "test cell" in which explicit cumulus ensemble models and parametric treatments of convection will be tested. The investigators will use these results to modify and tune an existing prototype cumulus parameterization. This parameterization would then be used in a large-scale model to evaluate its effects on simulated features of the general circulation of the atmosphere such as tropical easterly waves and intraseasonal oscillations. The diurnal cycle will also be examined in a simplified context. The project will support research by undergraduate students as well as graduate students.