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，这既是因为它很容易到达，也是因为需要理解为什么地球和它最近的邻居如此不同。几次前往金星的任务都返回了遥感和现场观测，通过精密的近红外滤光片和自适应光学装置，金星和土卫六的地球视野都有了显著改善。历史已经安排好了，大多数用于模拟大气动力学的现代工具都是在金星航天器的大部分任务完成后开发出来的。其结果是，所有数据都是新鲜的，地球是一本打开的书。土卫六本身即将成为一本打开的书，它在动态上最接近金星，因为它也是一颗缓慢的自转行星，因此，传统上将两者配对进行比较研究。此外，有迹象表明，土卫六的大气层表现出与金星类似的超自转。人们对金星和土卫六的兴趣增强有几个原因，其中两个原因是最近一个可信的说法，即在低分辨率大气模型中模拟了金星的完全超自转，以及卡西尼号轨道器/惠更斯探测器前往土卫六任务的到来。对赤道超自转进行建模的尝试主要集中在简化模型上，这些简化模型在逻辑上减少了正在测试的候选物理过程的数量。一些数值模拟支持Gierasch机制，在该机制中，动量作为Hadley环流的一部分垂直传输，并通过不稳定波传输到赤道，但也支持其他涡源，如热潮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地区贡献最大。到目前为止，许多金星衍生模型中缺失的一个主要细节是地形。金星有高山，这些山应该会产生内波现象，改变行星边界层和表面对大气的影响。在这个项目中，蒂莫西·道林博士为金星/泰坦研究带来了一个新的工具，一个高分辨率的大气环流模型EPIC，它使用了一个混合的等熵/地形跟踪垂直坐标。在第一年，道林博士将首先复制山本和高桥对金星的超自转结果，并对牛顿冷却剖面和水平分辨率进行额外的敏感性测试，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能力，将硫酸云添加到金星模型中，并将该模型的云模式与对金星的紫外线(UV)观测进行比较。随着惠更斯探测器和卡西尼号轨道器的新数据可用，预计泰坦将成为第三年的主要焦点。因为金星和土卫六有很小的科里奥利加速度，所以在理解它们的大气动力学方面的进步可以转化为理解任何行星上的赤道或热带气象学的进步。与过去一样，EPIC模型将以开放源代码的形式免费提供，为行星天文学界提供一个新的金星/土卫六研究工具。在人口方面，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. ***