Modeling Responses of Polar Mesospheric Clouds to Gravity Wave and Instability Dynamics and Induced Large‐Scale Motions
Modeling Responses of Polar Mesospheric Clouds to Gravity Wave and Instability Dynamics and Induced Large‐Scale Motions
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DOI：
10.1029/2021jd034643
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发表时间：
2021-06
期刊：
影响因子：
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通讯作者：
W. Dong;D. Fritts;G. Thomas;T. Lund
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作者：
W. Dong;D. Fritts;G. Thomas;T. Lund
建立了一个重力波（GW）模式，该模式考虑了温度变化和大尺度平流对极地中层云（PMC）亮度的影响，并对粒子半径有不同的依赖性。本文描述了PMC的复杂几何可压缩大气模型（CGCAM-PMC），并将其应用于PMC高度以下和高度处经历自加速（SA）动力学、断裂、动量沉积和二次GW（SGW）生成的三维（3-D）GW数据包。结果表明，表现出较强的SA和不稳定动力学的GW包可以诱导显着的PMC平流和大规模的传输，并导致部分或全部PMC升华。模拟的响应包括GW传播和SA动力学的PMC特征，直径为500- 1，200 km的“空洞”和水平范围为400-800 km的“前沿”。其中一些特征与中间层冰的高层大气学（AIM）卫星上的云成像和颗粒大小（CIPS）仪器的PMC成像非常相似。具体而言，初始CGCAM-PMC结果非常接近各种CIPS图像，即大空洞被较小空洞包围，迄今为止尚未提供动力学解释。在这些情况下，初始GW分组的GW和不稳定动力学是形成大空隙的原因。大空泡后缘处的小空泡与较低或较高高度的SGW生成和主要平均流强迫有关。我们预计这种建模的一个重要好处是，当CGCAM-PMC建模能够合理地复制PMC响应时，能够推断中间层和低热层（MLT）在显著深度上的局部强迫。
A gravity wave (GW) model that includes influences of temperature variations and large‐scale advection on polar mesospheric cloud (PMC) brightness having variable dependence on particle radius is developed. This Complex Geometry Compressible Atmosphere Model for PMCs (CGCAM‐PMC) is described and applied here for three‐dimensional (3‐D) GW packets undergoing self‐acceleration (SA) dynamics, breaking, momentum deposition, and secondary GW (SGW) generation below and at PMC altitudes. Results reveal that GW packets exhibiting strong SA and instability dynamics can induce significant PMC advection and large‐scale transport, and cause partial or total PMC sublimation. Responses modeled include PMC signatures of GW propagation and SA dynamics, “voids” having diameters of ∼500–1,200 km, and “fronts” with horizontal extents of ∼400–800 km. A number of these features closely resemble PMC imaging by the Cloud Imaging and Particle Size (CIPS) instrument aboard the Aeronomy of Ice in the Mesosphere (AIM) satellite. Specifically, initial CGCAM‐PMC results closely approximate various CIPS images of large voids surrounded by smaller void(s) for which dynamical explanations have not been offered to date. In these cases, the GW and instabilities dynamics of the initial GW packet are responsible for formation of the large void. The smaller void(s) at the trailing edge of a large void is (are) linked to the lower‐ or higher‐altitude SGW generation and primary mean‐flow forcing. We expect an important benefit of such modeling to be the ability to infer local forcing of the mesosphere and lower thermosphere (MLT) over significant depths when CGCAM‐PMC modeling is able to reasonably replicate PMC responses.