Testing theories of baroclinic adjustment in the laboratory and in simple atmospheric models

地球的气候状况可以被视为是辐射强迫过程与系统在寻求将热量输送到整个地球时的动力反应之间微妙平衡的结果。最近的研究往往侧重于量化辐射强迫过程及其相关的不确定性，以及导致气候变化的各种因素（包括人为因素）。但辐射强迫主要限制气候系统的能量通量，仅间接影响关键的气候变量，如平均地表温度。大气和海洋中的动态过程如何有效地将热量重新分配到地球上，也会对气候变量产生很大影响。这些本质上是非线性的，并且受到内部反馈的影响，这些反馈仍然没有得到很好的理解。这就留下了一些基本问题：是什么决定了热带外大气的平均直减率，是什么决定了赤道和两极或大陆和海洋之间大气的热反差？因此，在本项目中，我们将研究数值模式模拟中的相关动力学过程，基于气象局ENDGame动力学核心，（a）在精心控制的条件下，代表真实的流体中纬度气候系统的新型实验室模拟（目前在牛津的Read教授的小组中正在进行实验研究），以及（B）在简化的全球大气模式中受到理想化的辐射和边界强迫。将进行数值模型模拟，并（针对（a））与牛津实验中的流动和热结构的详细测量结果进行比较。这将使我们能够确定连接对流和斜压区域的热传递效率，以确定传输效率如何与关键参数成比例，以及流本身如何确定平均静态稳定度。我们还将能够评估充分发展的湍流能量级联出现或可能被抑制的条件。然后将在一系列大气条件、分辨率和具有理想强迫的完整ENDGame模式中的对流参数化上对此进行研究（在（B）中）。

The state of the Earth's climate can be viewed as resulting from a delicate balance between radiative forcing processes and the dynamical response of the system as it seeks to transport heat across the planet. Recent research has tended to focus on quantifying the radiative forcing processes and their associated uncertainties, and various factors (including those human-induced) leading to changes in the climate. But radiative forcing primarily constrains the energy throughput of the climate system and only indirectly influences key climate variables such as the mean surface temperature. Climate variables are also strongly affected by how efficiently heat is redistributed across the planet by dynamical processes in the atmosphere and oceans. These are intrinsically nonlinear, and are affected by internal feedbacks that are still not well understood. This leaves open such fundamental questions as: what determines the mean lapse rate in the extra-tropical atmosphere, and what determines the thermal contrast in the atmosphere between equator and poles or continents and oceans?In this project, therefore, we will study the relevant dynamical processes in numerical model simulations, based on the Met Office ENDGame dynamical core, (a) in a configuration representing a novel laboratory analogue of the mid-latitude climate system in a real fluid under carefully controlled conditions (currently being investigated experimentally in Prof. Read's group in Oxford), and (b) in simplified global atmospheric models subject to idealized radiative and boundary forcing. Numerical model simulations will be carried out and (for (a)) compared with detailed measurements of the flow and thermal structure in the Oxford experiments. This will enable us to determine the efficiency of heat transfer linking convective and baroclinic regions in order to determine how transport efficiency scales with key parameters and how the flow itself determines the mean static stability. We will also be able to assess the conditions under which fully developed turbulent energy cascades emerge or may be suppressed. This will then be investigated (in (b)) over a range of atmospheric conditions, resolutions and convective parameterizations in the full ENDGame model with idealized forcing.