Accurate and Consistent Microwave Observations of Venus and Their Implications
Accurate and Consistent Microwave Observations of Venus and Their Implications
复制标题
金星准确一致的微波观测及其意义
DOI：
10.1006/icar.2001.6710
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发表时间：
2001
期刊：
影响因子：
3.2
通讯作者：
J. Jenkins
中科院分区：
文献类型：
--
作者：
B. Butler;P. Steffes;S. Suleiman;M. Kolodner;J. Jenkins
摘要介绍了金星在1.385、1.465、4.86、8.44、14.94和22.46 GHz六个频率上的观测结果。这些是用甚大阵列获得的，并以一致的方式校准。推导了金星在六个频率下的亮度温度，并与包含金星大气、地表和地下辐射的模型进行了比较。一组单一的模型输入可以拟合更高频率的数据，其中排放主要来自大气。在较低的频率，发射主要来自地表和地下，模型很难再现测量结果，最低的两个频率根本不能很好地再现。与过去的模型相比，该模型的改进包括so2和h2so4微波不透明度的新形式，以及麦哲伦号测量的地形和表面特征的结合。最适合高频数据的模型输入包括相对温暖的温度剖面（与水手V掩星温度剖面比先锋-金星探测仪更一致），在较低云层及其下方的圆盘平均气体h2so4丰度为1-2.5 ppm，以及云层以下所有高度的so2平均丰度为⋦50 ppm。考虑到赤道和极地位置的差异，这个h2so4丰度与麦哲伦掩星推断的值是一致的。低层大气中so2的丰度与P. G. Steffes、M. J. Klein和J. M. Jenkins （1990, Icarus 83,83 - 92）的早期结果一致，但远低于从先锋号探测仪探测器推断的180 ppm或从红外观测推断的130 ppm。只有在大气几乎完全没有h2so4的情况下，并且使用比先锋-金星探测器测量的温度曲线要高得多的情况下，so2含量高达130 ppm的模型才符合测量结果。
Abstract We present observations of Venus at six frequencies: 1.385, 1.465, 4.86, 8.44, 14.94, and 22.46 GHz. These were obtained with the Very Large Array and calibrated in a consistent fashion. The brightness temperature of Venus at the six frequencies is derived and compared to a model which includes the emission from the atmosphere, surface, and subsurface of Venus. A single set of model inputs can fit the higher frequency data, where the emission comes mostly from the atmosphere. At the lower frequencies, where emission comes mostly from the surface and subsurface, the model has difficulty reproducing the measurements, and the lowest two frequencies are not reproduced well at all. Improvements in this model over past models include new formalisms for the microwave opacity of SO 2 and H 2 SO 4 and incorporation of measured topography and surface characteristics from Magellan. The inputs to the model which best fit the higher frequency data include a relatively warm temperature profile (more consistent with the Mariner V occultation temperature profile than that from the Pioneer–Venus sounders), a disk-averaged abundance of gaseous H 2 SO 4 of 1–2.5 ppm at and just below the lower cloud layer, and an average SO 2 abundance of ⋦50 ppm for all altitudes below the cloud layers. This H 2 SO 4 abundance is consistent with the values inferred from Magellan occultations, taking into account the differences between equatorial and polar locations. The SO 2 abundance in the lower atmosphere is in agreement with earlier results of P. G. Steffes, M. J. Klein, and J. M. Jenkins (1990, Icarus 84, 83–92), but much lower than the 180 ppm inferred from the Pioneer sounder probe or the 130 ppm inferred from infrared observations. Models with as much as 130 ppm of SO 2 fit the measurements only if the atmosphere is nearly completely devoid of H 2 SO 4 and the temperature profile which is much warmer than that measured by the Pioneer–Venus probes is used.