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首页> 外文期刊>Journal of the Atmospheric Sciences >Response of Atmospheric Convection to Vertical Wind Shear: Cloud-System-Resolving Simulations with Parameterized Large-Scale Circulation. Part I: Specified Radiative Cooling
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Response of Atmospheric Convection to Vertical Wind Shear: Cloud-System-Resolving Simulations with Parameterized Large-Scale Circulation. Part I: Specified Radiative Cooling

机译：大气对流对垂直风切变的响应：带参数化大规模环流的云系统解析模拟。第一部分：指定的辐射冷却

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It is well known that vertical wind shear can organize deep convective systems and greatly extend their lifetimes. Much less is known about the influence of shear on the bulk properties of tropical convection in statistical equilibrium. To address the latter question, the authors present a series of cloud-resolving simulations on a doubly periodic domain with parameterized large-scale dynamics based on the weak temperature gradient (WTG) approximation. The horizontal-mean horizontal wind is relaxed strongly in these simulations toward a simple unidirectional linear vertical shear profile in the troposphere. The strength and depth of the shear layer are varied as control parameters. Surface enthalpy fluxes are prescribed. The results fall in two distinct regimes. For weak wind shear, time-averaged rainfall decreases with shear and convection remains disorganized. For larger wind shear, rainfall increases with shear, as convection becomes organized into linear mesoscale systems. This nonmonotonic dependence of rainfall on shear is observed when the imposed surface fluxes are moderate. For larger surface fluxes, convection in the unsheared basic state is already strongly organized, but increasing wind shear still leads to increasing rainfall. In addition to surface rainfall, the impacts of shear on the parameterized large-scale vertical velocity, convective mass fluxes, cloud fraction, and momentum transport are also discussed.
机译：众所周知，垂直风切变可以组织深层对流系统并大大延长其寿命。在统计平衡中，关于剪切对热带对流总体性质的影响知之甚少。为了解决后一个问题，作者在基于弱温度梯度（WTG）近似的参数化大规模动力学的双重周期域上，提出了一系列云解析模拟。在这些模拟中，水平平均水平风向对流层中的一个简单的单向线性垂直剪切剖面强烈放宽。剪切层的强度和深度作为控制参数而变化。规定了表面焓通量。结果分为两种不同的方案。对于弱风切变，时间平均降雨量随切变而减小，对流仍保持混乱。对于较大的风切变，随着对流组织成线性中尺度系统，降雨随切变而增加。当施加的表面通量适中时，观察到降雨对剪切的这种非单调依赖性。对于较大的表面通量，在未剪切基本状态下的对流已经强烈组织，但是风切变的增加仍然导致降雨增加。除地表降雨外，还讨论了剪切对参数化的大规模垂直速度，对流质量通量，云量和动量传递的影响。

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