Consistent and flexible thermodynamics in atmospheric models using internal energy as a thermodynamic potential. Part II: Non-equilibrium regime
Consistent and flexible thermodynamics in atmospheric models using internal energy as a thermodynamic potential. Part II: Non-equilibrium regime
复制标题
使用内能作为热力学势的大气模型中一致且灵活的热力学。
DOI：
10.1002/qj.4373
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发表时间：
2022
影响因子：
8.9
通讯作者：
Bowen P
中科院分区：
文献类型：
--
作者：
Bowen P
在大气的数值模型中，涉及水分的非平衡热力学过程并不总是得到一致的处理，这可能导致能量收支的不一致和错误。因此，对于短时间尺度天气模式和长时间尺度气候模式来说，一个更一致的（湿）热力学公式是很重要的。在这项工作的第一部分中，我们推导出了一个热力学一致的框架，描述了云滴的凝结，蒸发，冻结和融化，其中所有感兴趣的热力学量都来自内部能量势，并且湿热力学耦合到二维半隐式半拉格朗日动力学核心。虽然这个框架是为表达非平衡过程而准备的，但它只适用于平衡状态。在这里，我们遵循第一部分中的方法，但是“打开”非平衡过程的表达式，例如，允许过冷水冻结或蒸发成亚饱和空气。为了实现所提出的方法，有必要将云滴内部和周围的物质和熵的传输速率的传统大气微物理表达式转换为非平衡态热力学的形式主义。这个过程首先是针对一些简单的理想化情况导出的，从蒸汽扩散引起的液滴增长开始，然后进行到更复杂的三相情况。为了证明这种方法，我们模拟了一些理想化的多云热气流，比较了平衡和非平衡状态，发现在非平衡状态下垂直速度的鲁棒下降，正如预期的那样。因此，这项工作证明了建立一个数值模型的可行性，该模型包括一个用于一致地模拟大气系统的潮湿非平衡热力学的框架，并为这种类型的更一致的大气建模提供了一个步骤。
In numerical models of the atmosphere, the non‐equilibrium thermodynamic processes involving moisture are not always treated consistently—possibly leading to inconsistencies and errors in the energy budget. Therefore, a more consistent formulation of (moist) thermodynamics is important, for short‐timescale weather models and long‐timescale climate models. In Part I of this work, we derived a thermodynamically consistent framework, describing condensation, evaporation, freezing, and melting of cloud droplets, in which all thermodynamic quantities of interest were derived from an internal energy potential and with the moist thermodynamics coupled to a 2D semi‐implicit semi‐Lagrangian dynamical core. While this framework was primed to express non‐equilibrium processes, it was solved for the equilibrium regime only. Here, we follow the methods in Part I, but with the expression for the non‐equilibrium processes “turned on”, for example, allowing freezing of supercooled water or evaporation into subsaturated air. To implement the proposed approach, it is necessary to translate conventional atmospheric microphysics expressions for transfer rates of matter and entropy in and around a cloud droplet into the formalism of non‐equilibrium thermodynamics. This procedure is first derived for some simple idealised cases, beginning with liquid droplet growth by vapour diffusion, and proceeding to more complex three‐phase cases. To demonstrate the approach, we then simulate some idealised cloudy thermals, comparing the equilibrium and non‐equilibrium regimes—finding a robust decrease in the vertical velocity in the non‐equilibrium regime, as expected. Thus, this work demonstrates the feasibility of building a numerical model that includes a framework for modelling the moist non‐equilibrium thermodynamics of an atmospheric system consistently and provides a step towards this type of more consistent atmospheric modelling.