Contemporary Earth system models mostly ignore the sub-grid scale (SGS) heterogeneous coupling between the land surface and atmosphere. To aid in the development of coupled land and atmosphere SGS parameterizations for global models, we present a study of different aspects of highly-realistic sub-100 km scale land-surface heterogeneity. The primary experiment is a set of simulations of September 24, 2017 over the Southern Great Plains (SGP) site using the Weather Research and Forecasting (WRF) model with 100-m horizontal resolution. The overall impact of land-surface heterogeneity is evaluated by comparing cloud and turbulent kinetic energy (TKE) production in large-eddy simulations (LESs) using heterogeneous and homogeneous surface fields (namely sensible and latent heat fluxes) specified by an offline field-scale resolving land-surface model (LSM). The heterogeneous land surface leads to significantly more cloud and TKE production. We then isolate specific sources of heterogeneity by using selectively domain-wide averaged fields in the LSM. It is found that heterogeneity in the land surface created by precipitation is effectively responsible for the increases in cloud and TKE production, while rivers and soil type have a negligible impact and land cover has only a small impact. Additional experiments modify the Bowen ratio in the surface fields and the initial wind profile of the heterogeneous case to clarify the results seen. Finally two additional days at the SGP site are simulated showing a similar increase in cloud production in heterogeneous cases.

中文翻译：

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场尺度分辨地表模型和 WRF-LES 的半耦合研究地表非均质性对云发展的影响

当代地球系统模型大多忽略了地表和大气之间的亚格网尺度（SGS）异质耦合。为了帮助开发全球模型的耦合陆地和大气 SGS 参数化，我们对高度逼真的 100 公里以下地表异质性的不同方面进行了研究。主要实验是 2017 年 9 月 24 日在南部大平原 (SGP) 站点上使用水平分辨率为 100 米的天气研究和预报 (WRF) 模型进行的一组模拟。通过使用离线场尺度指定的非均质和均质表面场（即感热和潜热通量）比较大涡模拟 (LES) 中的云和湍流动能 (TKE) 产生来评估陆面非均质性的总体影响解析地表模型 (LSM)。异质的地表导致明显更多的云和 TKE 产生。然后，我们通过在 LSM 中选择性地使用域范围的平均字段来隔离特定的异质性来源。研究发现，降水造成的地表异质性是云和 TKE 产量增加的有效原因，而河流和土壤类型的影响可以忽略不计，土地覆盖的影响很小。额外的实验修改了地表场中的鲍温比和异质情况的初始风廓线，以澄清所看到的结果。最后，模拟了 SGP 站点的另外两天，显示了在异构情况下云生产的类似增加。