A Long Baseline Investigation of Clouds, Haze and Methane Distributions on Titan

该奖项是根据2009年《美国复苏与再投资法案》(Public Law 111-5)资助的。土星最大的卫星土卫六可能是太阳系中唯一一个正在经历熟悉的大气过程的天体，这些过程包括降水、液体和风沙侵蚀，以及雾霾的形成和消散。该项目将解决关于土卫六的几个悬而未决的问题，如大气中甲烷的来源(不需要补给就应该存在数千万年)，为什么在特定的纬度范围内出现云，以及灰霾如何在南北半球之间迁移。该项目有五个目标：1)研究能否从土卫六的地图上探测到局部的甲烷源；2)表征甲烷凝结的条件随时间、纬度和海拔的变化；3)将泰坦区域大气模拟系统(TRAMS)的预报与高分辨率对流云图像序列进行比较；4)调查是否存在“晨光”现象，即东西边缘亮度的日不对称现象；5)绘制1996年至2007年霾的纬度和高度分布图。这项研究对土卫六的大气和甲烷云的性质施加了限制，这些限制来自卡西尼号航天器的数据，哈勃太空望远镜的观测，以及部分由有轨电车解释的地面凯克图像。分析将包括构建甲烷和雾霾剖面的三维半球图，从卡西尼复合红外光谱仪获得的光谱确定温度剖面，以及研究卡西尼成像科学子系统图像序列中的云以确定对流云成分的规模和寿命。由于类似的过程在地球上运行，土卫六是一个重要的实验室，用于研究常见的过程，如降水、侵蚀和雾霾的性质。该项目还将支持爱达荷大学的暑期本科生，他们将在天文数据处理方面提供帮助和接受培训。这项工作支持马里兰大学增加一名博士后学者。

AST-0909137YoungThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Saturn's largest moon, Titan, is perhaps the only other body in the solar system currently experiencing the familiar atmospheric processes of precipitation, liquid and aeolian erosion, and the formation and dissipation of smog-like haze. This project will resolve several outstanding questions about Titan, such as the source of the atmospheric methane (which should survive for tens of millions of years without being replenished), why clouds appear over specific latitude ranges at certain times, and how the haze migrates between north and south hemispheres.The project has five goals: 1) investigate whether localized sources of methane can be detected from maps of Titan; 2) characterize the conditions for methane condensation as a function of time, latitude and altitude; 3) compare the predictions of the Titan Regional Atmospheric Modeling System (TRAMS) with high-resolution image sequences of convective clouds; 4) investigate if there is such a phenomenon as "morning brightening", a diurnal asymmetry in the east/west limb brightnesses; 5) map the latitudinal and height distributions of haze from 1996 through 2007. The study applies constraints on the properties of Titan's atmosphere and its methane clouds which come from Cassini Spacecraft data, Hubble Space Telescope observations, and ground-based Keck images, interpreted in part with TRAMS. The analysis will include the construction of three-dimensional hemispherical maps of methane and haze profiles, the determination of temperature profiles from spectra obtained with the Cassini Composite Infrared Spectrometer, and a study of clouds in Cassini Imaging Science Subsystem image sequences to determine the scale and lifetime of convective cloud components.Because similar processes are operating on Earth, Titan is an important laboratory for investigating familiar processes like precipitation, erosion, and the properties of smog-like hazes. The project will also support summer undergraduate students at the University of Idaho who will assist and be trained in astronomical data processing. The work supports an additional postdoctoral scholar at the University of Maryland.