Dynamics of Tropical Waves and Instabilities

9724987伊曼纽尔热带大气表现出各种各样的波动现象，从数千公里的“天气尺度”波动到行星尺度的马登-朱利安振荡。热带大气的复杂数值模拟也显示了波谱，但它们的特征在不同的模型之间有明显的不同。关于这些波的动力学，特别是它们与湿对流的相互作用，有相当大的争议。一些人认为这种相互作用可能是不稳定的，这会导致波的放大，而另一些人则认为对流抑制了波。由于这些波在热带天气和气候中发挥着相当大的作用，包括热带气旋的形成，因此通过改善对波的基本动力学的一般了解可以获得很大的收获。该项目试图通过在各种条件下用简化模型进行若干实验来提高这一认识。通过排除现实世界的许多复杂性，如陆地和海洋的对比，强烈变化的背景风和温度，甚至地球的自转，可以实现对最基本的潜在动力学的欣赏。实验将使用从单柱模型到全三维准地转模型的一系列模型进行。所有人都将共享一个共同的设计，即基本状态是一种统计平衡状态，其中对流、辐射和大尺度环流处于平衡状态，并尽可能准确地表示对流和辐射的物理过程。这项研究工作最终将有助于改进热带大气的模型和预测。

9724987 Emanuel The tropical atmosphere exhibits a large variety of wave phenomena, ranging from "synoptic-scale " waves of several thousand kilometers in dimension to the planetary-scale Madden-Julian Oscillation. Complex numerical simulations of the tropical atmosphere also exhibit a spectrum of waves, but their characteristics differ appreciably from one model to another. There is considerable controversy about the dynamics of these waves, particularly concerning their interaction with moist convection. Some argue that such an interaction can be unstable an result in wave amplification while others argue that convection damps the waves. As these waves play a considerable role in tropical weather and climate, including the genesis of tropical cyclones, there is much to be gained by improving general understanding of the basic dynamics of the waves. This project seeks to improve that understanding by carrying out a number of experiments with simplified models under a variety of conditions. By excluding many of the complexities of the real world, such as land-sea contrasts, strongly varying background wind and temperature, and even the Earth's rotation, an appreciation of the most basic underlying dynamics can be attained. Experiments will be performed with a hierarchy of models ranging form sing-column models to fully three-dimensional quasi-geostrophic models. All will share a common design in that the basic state is one of statistical equilibrium in which convection, radiation, and large-scale circulation are in balance and the physical processes of convection and radiation are represented as accurately as possible. This research effort ultimately will contribute to improved models and prediction of the tropical atmosphere.