Large eddy simulation (LES) of the Martian convective boundary layer (CBL) with a Mars-adapted version of the Weather Research and Forecasting model is used to examine the impact of aerosol dust radiative-dynamical feedbacks on turbulent mixing. The LES is validated against spacecraft observations and prior modeling. To study dust redistribution by coherent dynamical structures within the CBL, two radiatively active dust distribution scenarios are used: one in which the dust distribution remains fixed and another in which dust is freely transported by CBL motions. In the fixed dust scenario, increasing atmospheric dust loading shades the surface from sunlight and weakens convection. However, a competing effect emerges in the free dust scenario, resulting from the lateral concentration of dust in updrafts. The resulting enhancement of dust radiative heating in upwelling plumes both generates horizontal thermal contrasts in the CBL and increases buoyancy production, jointly enhancing CBL convection. We define a dust inhomogeneity index (DII) to quantify how much dust is concentrated in upwelling plumes. If the DII is large enough, the destabilizing effect of lateral heating contrasts can exceed the stabilizing effect of surface shading such that the CBL depth increases with increasing dust optical depth. Thus, under certain combinations of total dust optical depth and the lateral inhomogeneity of dust, a positive feedback exists between dust optical depth, the vigor and depth of CBL mixing, and—to the extent that dust lifting is controlled by the depth and vigor of CBL mixing—the further lifting of dust from the surface.

中文翻译：

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使用 MarsWRF 对尘土飞扬的火星对流边界层进行大涡模拟

火星对流边界层 (CBL) 的大涡模拟 (LES) 和火星适应版本的天气研究和预测模型用于检查气溶胶尘埃辐射-动力反馈对湍流混合的影响。LES 已针对航天器观测和先验建模进行了验证。为了研究 CBL 内相干动力学结构的灰尘再分布，使用了两种辐射活跃的灰尘分布场景：一种是灰尘分布保持固定，另一种是通过 CBL 运动自由传输灰尘。在固定灰尘情况下，增加大气灰尘负载会使表面遮挡阳光并减弱对流。然而，由于上升气流中灰尘的横向浓度，在自由灰尘场景中出现了一种竞争效应。由此产生的上升流羽流中尘埃辐射加热的增强既在 CBL 中产生了水平热对比，又增加了浮力产生，共同增强了 CBL 对流。我们定义了一个灰尘不均匀性指数 (DII) 来量化有多少灰尘集中在上升流羽流中。如果 DII 足够大，横向加热对比度的不稳定效应会超过表面阴影的稳定效应，使得 CBL 深度随着灰尘光学深度的增加而增加。因此，在尘埃总光学深度和尘埃横向不均匀性的某些组合下，尘埃光学深度、CBL 混合的活力和深度之间存在正反馈，并且——在某种程度上，扬尘受尘埃的深度和活力控制。 CBL 混合——进一步从表面去除灰尘。