Development of a general circulation model of the middle atmosphere

在这个项目中，我们开发了一个中层大气的社区环流模式。该模式是在东京大学A.Sumi提出的对流层和平流层低层社区环流气候模式的基础上发展起来的，该模式最初是由Kanamitu et.艾尔这个项目中开发的模式是一个T21水平分辨率的光谱模式，它包括从地面到83公里高度(模式1)和从地面到160公里高度(模式2)。作为垂直坐标系，使用了分辨率约为2.5公里的西格玛杂交系。平流层、中间层和低热层采用牛顿冷却辐射方案。在不久的将来，将推出一种更精确的辐射方案。利用模式1进行了两个模式年的试积分。结果表明，该模式有能力描述中层大气环流的定性结构。模式中还模拟了北半球冬季的平流层突然变暖事件，模式中包含了辐射的日循环。在模型2中，上边界足够高，可以模拟潮波的垂直传播。用模式2进行的积分试验表明，潮汐波在100公里高度处破裂，并由破裂引起的动量沉积引起东风。该模式也可用作非线性积分。作为例子，研究了日潮波的非线性传播。结果表明，模式中的干对流调整和非线性能较好地模拟100公里左右高度的海浪饱和。

In this project we have developed a community general circulation model of the middle atmosphere. This model is based on the community general circulation climate model for troposphere and lower stratosphere developed by A. Sumi at University of Tokyo, this model was originally developed by kanamitu et. al. at Japan Meteorological Agency.The model developed in this project is a spectral model with T21 horizontal resolution, which includes from the ground to 83km height(Model 1) and from the ground to 160km height(Model 2). As a vertical coordinate system, a sigma phybrid coordinate is used with a resolution of about 2.5km. Newtonian cooling radiation scheme is used in the stratosphere, mesosphere and lower thermosphere. In the near future a more accurate radiation scheme will be introduced.A trial integration was conducted for two Model years using model 1. It is shown that the model has a capability to represent a qualitative structure of the middle atmosphere circulation. A stratospheric sudden warming like events are also simulated in the models northern hemisphere winter.A diurnal cycle of the radiation is included in the model. In Model 2, the upper boundary is high enough to simulate the vertical propagation of the tidal waves. A trial integration using Model 2 shows that the tidal waves are breaking at about 100km height and easterlies are induced by the momentum deposition due to the breaking.This model is also used as an nonlinear integrator. As an example, a non-linear propagation of the diurnal tidal waves is investigated. It is shown that the dry convective adjustment and the nonlinearity in the model can simulate the saturation of the wave at about 100km height.