Structure and processes of the upper troposphere and lower stratosphere, and their sensitivity to changes in atmospheric CO2 concentrations

对流层和平流层的分离传统上是以垂直温度结构的标准为基础的，在大约10公里的高度有一个尖锐的对流层顶，在副热带上空陡峭地向上隆起，直到热带上空大约17公里的高度。然而，其他特征，如辐射特性或痕量气体浓度的相关性，表明从对流层上层(UT)延伸到平流层下层(LS)的垂直层上有更渐进的过渡。UT/LS的结构由对流层和平流层过程决定，可能对大气二氧化碳浓度的变化很敏感。相反，UT/LS的变化可能会对气候产生强烈的反馈。拟议的项目将有助于提高我们对控制UT/LS结构的过程的理解，以便更好地预测这一层在不断变化的气候中如何变化，以及这一层的变化可能如何影响气候。为此，我们将利用空间大气观测，以及高空飞行飞行器上仪器的现场观测。对这些观测结果的分析将有助于形成假说，这些假说将在大规模数值模型的帮助下进行测试，这些模型的复杂性从原始方程模型到化学/气候耦合模型。

The separation of troposphere and stratosphere is traditionally based on criteria of the vertical temperature structure, with a sharp tropopause at an altitude of about 10 km, that bulges steeply upward over the subtropics to an altitude of about 17 km over the tropics. However, other characteristics such as radiative properties or correlations of trace gas concentrations suggest a more gradual transition over a vertical layer extending from the upper troposphere (UT) into the lower stratosphere (LS). The structure of the UT/LS is determined both by tropospheric and stratospheric processes, and may be sensitive to changes in atmospheric carbon dioxide concentrations. Conversely, changes in the UT/LS may have a strong feedback on climate. The proposed project will help to improve our understanding of the processes that control the UT/LS structure in order to provide improved predictions of how this layer changes in a changing climate, and how the changes in this layer may have an impact on climate. To this end, we will make use of space-borne atmospheric observations, as well as of in-situ observations from instruments onboard of high flying aircrafts. The analysis of these observations will help to formulate hypotheses, which will be tested with the help of large-scale numerical models, ranging in complexity from primitive equation models to coupled chemistry/climate models.