Atmospheric meridional circulation as seen from a moist static energy perspective

大气的一个主要作用是维持热带地区相对寒冷的气候条件和两极地区相对温暖的气候条件。大气环流的这一方面可以想象成一个巨大的行星热动力机器，向低纬度地区输入低能空气，向高纬度地区输出高能空气。虽然这是气候的一个非常基本的方面，但迄今为止还没有理论来预测这种从低纬度到高纬度的质量交换的强度是多少，也没有理论来预测由大气环流向极地和赤道输送的空气的能量。本建议旨在深入探讨控制这两个主题的机制。这种努力对于准确预测由于自然波动或对人为强迫作出反应而引起的大气向极地能量输送和地表温度的变化至关重要。为了解决这些问题，我们提出了以下关键的工作假设：(1)从表面温度可以预测向极地和赤道方向携带的空气能量，表面温度本身在很大程度上受大尺度海洋-大气相互作用的控制。（ii）大气质量输运强度是辐射冷却强度和赤道至极表面温度梯度的简单函数。这个建议最新颖的方面是用观测数据集和在理想几何形状中运行的简单气候模型模拟来检验这些假设。

A major role of the atmosphere is to maintain relatively cold climate conditions in the Tropics and relatively warm climate conditions at the Poles. This aspect of the atmospheric circulation can be envisioned as a gigantic (planetary thermodynamic machine importing low energy air to low latitudes and exporting high energy air to high latitudes. Although this is a very basic aspect of climate, there is to date no theory to predict what the intensity of this mass exchange from low to hig latitudes is, nor is there a theory to predict the energy of the air that is being carried poleward and equatorward by the atmospheric circulation. This proposal aims at investing at depth the mechanisms controlling both topics. Such effort is crucial to obtain an accurate prediction of the change in poleward energy transport of the atmosphere and surface temperature arising either because of natural fluctuations, or in response to anthropogenic forcing. To tackle these problems, we put forward the following key working hypotheses: (i) the energy of the air carried both poleward and equatorward can be predicted from the surface temperature, itself largely controlled by large scale ocean-atmosphere interactions. (ii) the intensity of the atmospheric mass transport is a simple function of the intensity of radiative cooling and the equator to pole surface temperature gradient. The most novel aspect of this proposal is to test these hypotheses against observational datasets AND simple climate model simulations run in idealized geometries.