Spontaneous Imbalance (SI)

自发不平衡 (SI)

• 批准号: 258697604
• 负责人: Professor Dr. Ulrich Achatz
• 金额: --
• 依托单位: The University of St Andrews
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/258697604?language=en
• 关键词: Spontaneous; Imbalance; SI

Gravity waves (GWs), spatially often too small to be resolved by present day weather and climate models, need to be parameterized since they have a profound effect on the large scales. While several flow-dependent parameterizations for the radiation of GWs from orographic and convective sources do exist, the situation is less developed for waves emitted from large-scale baroclinic flows. This source of GWs is related to spontaneous imbalance (SI), i.e. the spontaneous breakdown of balance in a supposed quasi-geostrophic flow that in consequence radiates GWs. Studying spontaneous GW emission and validating parameterization schemes is challenging due to the fact that GWs will always be embedded in the complex frontal flow with a large number of interacting processes. Therefore, we combine theory and numerical modelling with complementary laboratory experiments. The latter guarantee the full repeatability of the large-scale flow situation under consideration. The direct correspondence between experimental and model data and the data reproducibility makes the lab experiment a powerful testing environment for parameterizations and climate related processes. The differentially heated rotating annulus experiment, built and conducted at BTU (Brandenburg Technische Universität Cottbus-Senftenberg) provides the necessary reference data for benchmarks of model simulations at GU-F (Goethe Universität Frankfurt) and IAP (Leibniz Institute for Atmospheric Physics, Kühlungsborn). We will focus on experimentally delineating preferred conditions for the occurrence of SI and relevant background flow properties for the atmosphere-like big tank. Complementary, an efficient description of GW variability and the related spontaneous emission process will be developed by GU-F and IAP, using idealized simulations. Core issue here is the identification of a useful relationship between the large-scale flow and the source of meso-scale GWs, and the validation of this approach in self-consistent coarse-resolution ray-tracing simulations. The goal is to construct a resolution-dependent SI parameterization. This source parameterization identified from model data will be validated against the annulus experiment at BTU. This will be accompanied by an analysis of UA-ICON simulations with high and low resolution. Finally, the parameterized GWs will be coupled to the ray-tracing GW model MS-GWaM in UA-ICON.

引力波（GWs）在空间上往往太小，无法由目前的天气和气候模式解决，因此需要参数化，因为它们在大尺度上具有深远的影响。虽然对于地形源和对流源的GWs辐射，确实存在一些与流相关的参数化，但对于大尺度斜压流发射的波，这种情况还不太发达。这种gw的来源与自发不平衡（SI）有关，即在假定的准地转流中自发破坏平衡，从而辐射gw。由于GW始终处于具有大量相互作用过程的复杂锋面流中，因此研究GW自发辐射并验证参数化方案具有挑战性。因此，我们将理论和数值模拟与互补的实验室实验相结合。后者保证了所考虑的大规模流动情况的完全可重复性。实验数据与模式数据的直接对应以及数据的可重复性使实验室实验成为参数化和气候相关过程的有力测试环境。在BTU （Brandenburg Technische Universität Cottbus-Senftenberg）建立和进行的差热旋转环空实验为GU-F （Goethe Universität Frankfurt）和IAP （Leibniz Institute for Atmospheric Physics, k<s:1> hlunsborn）的模型模拟基准提供了必要的参考数据。我们将重点在实验上描述发生SI的首选条件和类似大气的大罐的相关背景流动特性。此外，GU-F和IAP将利用理想化的模拟，对GW变率和相关的自发排放过程进行有效的描述。这里的核心问题是确定大尺度流与中尺度gw源之间的有用关系，并在自一致的粗分辨率射线追踪模拟中验证这种方法。目标是构建一个与分辨率相关的SI参数化。从模型数据中确定的源参数化将在BTU的环空实验中进行验证。这将伴随着高分辨率和低分辨率的UA-ICON模拟分析。最后，将参数化的GW与UA-ICON中的射线追踪GW模型MS-GWaM进行耦合。