Atmospheric Dynamics Modeling of Venus with Realistic Topography and Structure and Comparative Modeling of Titan

金星离地球很近，这使它成为行星探索的主要目标，因为它很容易到达，也因为需要了解为什么地球和它最近的邻居如此不同。对金星的几次任务已经返回了遥感和原位观测，从地球上看到的金星和土卫六的远景都有了精确的近红外滤光片和自适应光学系统的显著改善。历史是这样安排的，大多数用于模拟大气动力学的现代工具都是在大部分金星探测器任务完成后开发出来的。结果是所有的数据都是新鲜的，地球是一本公开的书。土卫六，即将成为一本开放的书，动态上最接近金星，因为它也是一个缓慢的旋转体，因此，将两者配对进行比较研究是传统的。此外，有迹象表明，土卫六的大气层表现出与金星类似的超旋转。人们对金星和土卫六的兴趣越来越浓厚，原因有几个，其中两个是最近可信的说法，即在一个低分辨率的大气模型中模拟了金星从静止开始的完全超旋转，以及卡西尼轨道飞行器/惠更斯探测器前往土卫六的任务的出现。模拟赤道超旋转的尝试集中在简化模型上，这些模型在逻辑上减少并分离了正在测试的候选物理过程的数量。一些数值模拟支持吉拉斯机制，其中动量作为哈德利环流的一部分垂直输送，并通过不稳定的波浪输送到赤道，但也支持其他涡旋源，如热潮汐和地形激发的重力波。问题的一部分是区分哪些影响对给定的海拔区域贡献最大。到目前为止，许多金星自转模型中缺失的一个重要细节是地形。金星有高大的山脉，这些山脉应该会产生内波现象，并改变行星边界层和表面对大气的影响。在这个项目中，Timothy Dowling博士为金星/泰坦的研究带来了一个新工具，一个高分辨率的大气环流模型EPIC，它使用混合等熵/地形跟踪垂直坐标。在第一年，道林博士将首先重现山本和高桥对金星的超旋转结果，并对牛顿冷却剖面和水平分辨率进行额外的灵敏度测试，这将对结果进行有价值的确认。同样在第一年，研究人员将系统地测试地形对大气环流的影响。这项工作将持续到第二年。在第二年，他们将利用EPIC模型现有的云微物理功能，在金星模型中添加硫酸云，并将模型的云模式与金星的紫外线（UV）观测结果进行比较。随着惠更斯探测器和卡西尼轨道器的新数据的出现，预计土卫六将成为第三年的主要焦点。因为金星和土卫六的科里奥利加速度很小，了解它们的大气动力学的进展转化为了解任何行星的赤道或热带气象学的进展。与过去一样，EPIC模型将作为开放源代码免费提供，为行星天文学界提供金星/泰坦研究的新工具。在人口统计方面，该项目促进了肯塔基州扩大大气动力学研究的努力。＊＊＊

AST 0407186DowlingThe proximity of Venus to Earth makes it a major target for planetary exploration, both because it is easy to reach and because of the need to understand why Earth and its closest neighbor are so different. Several missions to Venus have returned remote sensing and in situ observations, and the vista from Earth of both Venus and Titan has dramatically improved with precise near-infrared filters and adaptive optics. History has ordered itself such that most of the modern toolsused to simulate atmospheric dynamics have been developed after the bulk of Venus spacecraft missions have been completed. The result is that all the data are fresh and the planet is an open book. Titan, about to become an open book itself, is dynamically closest to Venus because it is also a slow rotator, hence, it is traditional to pair the two for comparative studies. Furthermore, indications are that Titan's atmosphere exhibits a superrotation that is similar to that of Venus. There is heightened interest in Venus and Titan for several reasons, two being a recent credible claim for simulating the full Venus superrotation starting at rest in a low-resolution atmospheric model, and the advent of the Cassini Orbiter/ Huygens-Probe mission to Titan. Attempts to model equatorial superrotation have focused on simplified models that logically reduce andisolate the number of candidate physical processes being tested. Some numerical simulations lend support to the Gierasch mechanism wherein momentum is transported vertically as part of the Hadley-cell circulation, and to the equator by waves from instability, but there is also support for other eddy sources such as thermal tides and topographically excited gravity waves. Part of the problem is to distinguish which effects contribute most to a given altitude region. A leading detail missing from many Venus spinup models to date is topography. Venus has tall mountains, and these should generate internal-wave phenomena and modify the planetary boundary layer and the influence of the surface on the atmosphere. In this project, Dr. Timothy Dowling brings to Venus/Titan research a new tool, a high-resolution general circulation model, EPIC, which uses a hybrid isentropic/terrain-following vertical coordinate. In the first year, Dr. Dowling will begin by reproducing the superrotation results of Yamamoto and Takahashi for Venus, with additional sensitivity tests regarding the Newtonian cooling profile and the horizontal resolution, which will yield a valuable confirmation of the results. Also in Year 1, the researchers will systematically test the effects of topography on the general circulation. This work will continue into the second year. In Year 2, they will add sulfuric-acid clouds to the Venus model, taking advantage of the EPIC model's existing cloud-microphysics capabilities, and compare the model's cloud patterns with ultraviolet (UV) observations of Venus. It is anticipated that Titan will be the primary focus in the third year, as new data from the Huygens Probe and Cassini Orbiter become available. Because Venus and Titan have small Coriolis accelerations progress in understanding their atmospheric dynamics translates into advances in understanding equatorial or tropical meteorology on any planet. As in the past, the EPIC model will be made freely available as open source code, providing a new tool for Venus/Titan studies to the planetary astronomy community. On the demographic front, this project promotes an effort to expand atmospheric dynamics research in Kentucky. ***