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Inherent Dissipation of Upwind‐Biased Potential Temperature Advection and its Feedback on Model Dynamics
Journal of Advances in Modeling Earth Systems ( IF 4.4 ) Pub Date : 2021-03-10 , DOI: 10.1029/2020ms002384
A. Gassmann 1
Affiliation  

Higher order upwind‐biased advection schemes are often used for potential temperature advection in dynamical cores of atmospheric models. The inherent diffusive and antidiffusive fluxes are interpreted here as the effect of irreversible sub‐gridscale dynamics. For those, total energy conservation and positive internal entropy production must be guaranteed. As a consequence of energy conservation, the pressure gradient term should be formulated in Exner pressure form. The presence of local antidiffusive fluxes in potential temperature advection schemes foils the validity of the second law of thermodynamics. Due to this failure, a spurious wind acceleration into the wrong direction is locally induced via the pressure gradient term. When correcting the advection scheme to be more entropically consistent, the spurious acceleration is avoided, but two side effects come to the fore: (i) the overall accuracy of the advection scheme decreases and (ii) the now purely diffusive fluxes become more discontinuous compared to the original ones, which leads to more sudden body forces in the momentum equation. Therefore, the amplitudes of excited gravity waves from jets and fronts increase compared to the original formulation with inherent local antidiffusive fluxes. The means used for supporting the argumentation line are theoretical arguments concerning total energy conservation and internal entropy production, pure advection tests, one‐dimensional advection‐dynamics interaction tests and evaluation of runs with a global atmospheric dry dynamical core.

中文翻译:

逆风势对流的固有耗散及其对模型动力学的反馈

高阶逆风对流方案通常用于大气模型动力核心中的潜在温度对流。固有的扩散通量和反扩散通量在这里被解释为不可逆亚网格动力学的影响。对于这些,必须保证总的能量守恒和正的内部熵产生。由于节约能源,压力梯度项应以Exner压力形式表示。潜在的温度对流方案中局部抗扩散通量的存在阻碍了热力学第二定律的有效性。由于该故障,通过压力梯度项会局部导致向错误方向的杂散风加速。当将对流方案校正为更加熵一致时,可以避免杂散加速度,但是出现了两个副作用:(i)对流方案的整体精度降低;(ii)与原始通量相比,现在的纯扩散通量变得更加不连续,这导致了动量方程中突然出现的更大的机体力。因此,与具有固有局部抗扩散通量的原始公式相比,来自喷头和前沿的激发重力波的振幅增加了。支持论据线的手段是关于总能量守恒和内部熵产生,纯对流试验,一维对流-动力学相互作用试验以及具有全球大气干动力核心的运行评估的理论论证。(i)对流方案的整体精度降低,并且(ii)现在的纯扩散通量与原始通量相比变得更加不连续,这导致动量方程中出现了更多的突然的体力。因此,与具有固有局部抗扩散通量的原始公式相比,来自喷头和前沿的激发重力波的振幅增加了。支持论据线的手段是关于总能量守恒和内部熵产生,纯对流试验,一维对流-动力学相互作用试验以及具有全球大气干动力核心的运行评估的理论论证。(i)对流方案的整体精度降低,并且(ii)现在的纯扩散通量与原始通量相比变得更加不连续,这导致动量方程中出现了更多的突然的体力。因此,与具有固有局部抗扩散通量的原始公式相比,来自喷头和前沿的激发重力波的振幅增加了。支持论据线的手段是关于总能量守恒和内部熵产生,纯对流试验,一维对流-动力学相互作用试验以及具有全球大气干动力核心的运行评估的理论论证。与具有固有局部抗扩散通量的原始公式相比,来自喷头和前沿的激发重力波的振幅增加了。支持论据线的手段是关于总能量守恒和内部熵产生,纯对流试验,一维对流-动力学相互作用试验以及具有全球大气干动力核心的运行评估的理论论证。与具有固有局部抗扩散通量的原始公式相比,来自喷头和前沿的激发重力波的振幅增加了。支持论据线的手段是关于总能量守恒和内部熵产生,纯对流试验,一维对流-动力学相互作用试验以及具有全球大气干动力核心的运行评估的理论论证。
更新日期:2021-03-19
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