Diurnal and Secular Variability of the Venus Mesosphere

AST 0098614克兰西金星中间层是一个动力学的过渡区域，介于大质量低层大气的纬向旋转和热层的亚音速昼夜环流之间。 它也是一个关键的光化学活性的区域，其中SOx、考克斯和HOx催化循环控制在其下边界处的大量硫酸盐云层的形成，维持CO2大气的稳定性以光解解离，并限制大气水的长期逃逸。 金星中间层上方和下方的大气环流和化学的极端差异导致其环流和组成的极大日变化和年际变化，这混淆了我们对这一显着动态制度的理解。 Dr. R.空间科学研究所的托德克兰西将领导一个数据分析和观测研究计划，调查金星中层大气的可变热和成分状态。12 CO、13 CO和HDO的毫米谱线使得能够在中间层内70-110公里高度处对温度、CO和水汽密度进行独特的垂直廓线反演。现有的，未经分析的12 CO，13 CO和HDO毫米和亚毫米光谱的100多个单独的测量将被建模，以确定在1990-1999年期间的CO和温度的日变化和年际变化。对这些观测结果的粗略分析表明，在80-95公里高度的全球中层温度有突然的短期变化，在95-100公里高度有一个向阳面中层顶，中层水汽丰度有强烈的日变化。这些都是金星中层大气中日变化和长期变化的独特发现，需要对全部数据集进行全面分析，以量化和公布结果。此外，在2000-2003年期间将进行新的毫米和亚毫米测量，以扩大CO/温度/水反演的时间和垂直覆盖范围，并确定中间层SO，SO2，H2SO 4和O2的丰度。 分析的主要目的是定义金星中间层的昼夜和大的年际变化，最广泛的垂直，参数（温度和成分），和时间的描述可能。1990-2003年期间的这些观测将放在以前的毫米（1982-1990），先锋金星轨道器（1978-1985）和伽利略（1991）飞越观测的背景下，以最大限度地提高这些现有中间层测量的科学回报，并支持未来航天器对金星大气的探索。特别是对金星中间层的研究，与最近才被定义为控制脆弱的地球平流层的化学和动力学过程有很强的相似之处。

AST 0098614ClancyThe Venus mesosphere is a dynamical transition region between the zonal rotation of the massive lower atmosphere and the subsonic day-to- night circulation of the thermosphere. It is also a region of key photochemical activity, in which SOx, COx, and HOx catalytic cycles control formation of the massive sulfate cloud layer at its lower boundary, maintain stability of the C02 atmosphere to photolytic dissociation, and limit long-term escape of atmospheric water. The extreme differences in atmospheric circulation and chemistry above and below the Venus mesosphere lead to very large diurnal and interannual variations in its circulation and composition, which have confounded our understanding of this remarkably dynamic regime. Dr. R. Todd Clancy, of the Space Science Institute, will lead a data analysis and observing research program to investigate the variable thermal and compositional state of the Venus middle atmosphere. Millimeter spectral lines of 12CO, 13CO, and HDO enable unique vertical profile retrievals for temperature, and CO and water vapor densities at 70-110 km altitudes within the mesosphere. Over 100 separate measurements of existing, unanalyzed 12CO, 13CO, and HDO millimeter and sub-millimeter spectra will be modeled to determine the diurnal and interannual variabilities of CO and temperatures over the 1990-1999 period. Cursory analysis of these observations indicates abrupt, short-term variations in global mesospheric temperatures at 80-95 km altitudes, a dayside mesopause at 95-100 km altitudes, and strong diurnal variation in mesospheric water vapor abundances. These are unique discoveries of diurnal and secular variabilities in the Venus middle atmosphere that require comprehensive analyses of the full data set to quantify and publish results. In addition, new millimeter and sub-millimeter measurements will be taken over the 2000-2003 period to extend the temporal and vertical coverages of the C0/temperature/water retrievals, and to determine mesospheric abundances for SO, S02, H2SO4, and O2. A primary objective of the analysis is to define the diurnal and large interannual variations of the Venus mesosphere with the broadest vertical, parameter {temperature and composition) , and temporal description possible. The 1990-2003 period of these observations will be placed in the context of prior millimeter (1982-1990), Pioneer Venus orbiter (1978-1985) , and Galileo (1991) flyby observations to maximize the scientific return of these existing mesospheric measurements, and to support future spacecraft exploration of the Venus atmosphere. Study of the Venus mesosphere, in particular, draws strong parallels from the chemical and dynamical processes only recently defined to control the fragile terrestrial stratosphere.***