Recent increases in computing power mean that atmospheric models for numerical weather prediction are now able to operate at grid spacings of the order of a few hundred meters, comparable to the dominant turbulence length scales in the atmospheric boundary layer. As a result, models are starting to partially resolve the coherent overturning structures in the boundary layer. In this resolution regime, the so‐called boundary layer “gray zone,” neither the techniques of high‐resolution atmospheric modeling (a few tens of meters resolution) nor those of traditional meteorological models (a few kilometers resolution) are appropriate because fundamental assumptions behind the parameterizations are violated. Nonetheless, model simulations in this regime may remain highly useful. In this paper, a newly formed gray zone boundary layer community lays the basis for parameterizing gray zone turbulence, identifies the challenges in high‐resolution atmospheric modeling and presents different gray zone boundary layer models. We discuss both the successful applications and the limitations of current parameterization approaches, and consider various issues in extending promising research approaches into use for numerical weather prediction. The ultimate goal of the research is the development of unified boundary layer parameterizations valid across all scales.

中文翻译：

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大气边界层和湍流的“灰色地带”：评论

最近计算能力的提高意味着，用于数值天气预报的大气模型现在能够在几百米量级的网格间距下运行，这与大气边界层中占主导地位的湍流长度尺度相当。结果，模型开始部分解析边界层中的相干翻转结构。在这种分辨率体制下，所谓的边界层“灰色地带”既不适合高分辨率大气建模技术（几十米分辨率），也不适合传统气象模型技术（几十公里分辨率），因为基本假设后面的参数设置被违反。但是，在这种情况下的模型仿真可能仍然非常有用。在本文中，一个新形成的灰色地带边界层群落为参数化灰色地带湍流奠定了基础，确定了高分辨率大气建模中的挑战，并提出了不同的灰色地带边界层模型。我们讨论了当前参数化方法的成功应用和局限性，并考虑了将有前途的研究方法扩展为数值天气预报所使用的各种问题。该研究的最终目标是开发适用于所有尺度的统一边界层参数化。并考虑各种问题，以扩展有前途的研究方法用于数值天气预报。该研究的最终目标是开发适用于所有尺度的统一边界层参数化。并考虑各种问题，以扩展有前途的研究方法用于数值天气预报。该研究的最终目标是开发适用于所有尺度的统一边界层参数化。