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

地球气候的状态可以被视为是辐射强迫过程和系统在寻求将热量输送到地球上时的动力响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吞吐量，仅间接影响关键气候变量，如平均表面温度。气候变量还受到大气和海洋中的动力过程在地球上重新分配热量的效率的强烈影响。这些本质上是非线性的，并且受到内部反馈的影响，这些反馈仍然没有被很好地理解。这就留下了这样的基本问题：是什么决定了热带外大气的平均衰减率，是什么决定了赤道和极地之间的大气热对比，或者大陆和海洋之间的热对比？因此，在这个项目中，我们将在数值模式模拟中研究相关的动力学过程，基于Met Office EndGame动力核心，(A)在严格控制的条件下，在真实流体中代表一种新的实验室模拟中纬度气候系统的构型(目前正在牛津大学里德教授的小组进行实验研究)，以及(B)在理想的辐射和边界强迫下的简化全球大气模型。将进行数值模型模拟，并(对于(A))与牛津实验中对流动和热结构的详细测量进行比较。这将使我们能够确定连接对流和斜压区的热传递效率，以便确定传输效率如何随关键参数变化，以及气流本身如何确定平均静态稳定性。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。这将研究(在(B))在一个范围的大气条件，分辨率和对流参数的全部结束模式的理想化强迫。

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.