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首页> 外文期刊>Journal of the Atmospheric Sciences >The Influence of Wind Speed on Shallow Marine Cumulus Convection
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The Influence of Wind Speed on Shallow Marine Cumulus Convection

机译：风速对浅海积云对流的影响

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The role of wind speed on shallow marine cumulus convection is explored using large-eddy simulations and concepts from bulk theory. Focusing on cases characteristic of the trades, the equilibrium trade wind layer is found to be deeper at stronger winds, with larger surface moisture fluxes and smaller surface heat fluxes. The opposing behavior of the surface fluxes is caused by more warm and dry air being mixed to the surface as the cloud layer deepens. This leads to little difference in equilibrium surface buoyancy fluxes and cloud-base mass fluxes. Shallow cumuli are deeper, but not more numerous or more energetic. The deepening response is necessary to resolve an inconsistency in the subcloud layer. This argument follows from bulk concepts and assumes that the lapse rate and flux divergence of moist-conserved variables do not change, based on simulation results. With that assumption, stronger winds and a fixed inversion height imply larger surface moisture and buoyancy fluxes (heat fluxes are small initially). The consequent moistening tends to decrease cloud-base height, which is inconsistent with a larger surface buoyancy flux that tends to increase cloud-base height, in order to maintain the buoyancy flux at cloud base at a fixed fraction of its surface value (entrainment closure). Deepening the cloud layer by increasing the inversion height resolves this inconsistency by allowing the surface buoyancy flux to remain constant without further moistening the subcloud layer. Because this explanation follows from simple bulk concepts, it is suggested that the internal dynamics (mixing) of clouds is only secondary to the deepening response.
机译：利用大涡模拟和体积理论的概念，探索了风速在浅海积云对流中的作用。着眼于交易的特征案例，发现均衡交易风层在强风下更深，具有较大的表面水分通量和较小的表面热通量。表面通量的相反行为是由于随着云层加深，更多的温暖和干燥的空气混合到表面引起的。这导致平衡表面浮力通量和云基质量通量的差异很小。浅层积积层较深，但数量不多或充满活力。加深响应对于解决子云层中的不一致是必要的。该论点从整体概念出发，并基于模拟结果，假定湿润变量的消失率和通量散度不变。在此假设下，较强的风和固定的反演高度意味着较大的表面湿度和浮力通量（最初的热通量较小）。随后的润湿趋向于降低云底高度，这与较大的表面浮力通量不一致，后者倾向于增加云底高度，以便将云底的浮力通量保持在其表面值的固定分数（夹带关闭） ）。通过增加反演高度来加深云层，可以在不进一步润湿亚云层的情况下，使表面浮力通量保持恒定，从而解决这一矛盾。因为此解释来自简单的整体概念，所以建议云的内部动力学（混合）仅是加深响应的次要条件。

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