Self-consistent retrieval of temperature profiles and cloud structure in the northern hemisphere of Venus using VIRTIS/VEX and PMV/VENERA-15 radiation measurements
Self-consistent retrieval of temperature profiles and cloud structure in the northern hemisphere of Venus using VIRTIS/VEX and PMV/VENERA-15 radiation measurements
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DOI：
10.1016/j.pss.2013.09.020
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发表时间：
2013-12-01
影响因子：
2.4
通讯作者：
Arnold, G.
中科院分区：
文献类型：
--
作者：
Haus, R.;Kappel, D.;Arnold, G.
本文介绍了改进的辐射传输模拟和多窗口反演程序（MWR），并应用于研究金星北方半球夜侧大气的热结构和云特征。光谱数据的比较分析与自洽温度廓线和云参数反演相结合，这些数据是在早期苏联Venera-15实验期间由欧空局金星快车空间探测器上的可见光和红外热成像光谱仪（VIRTIS-M-IR）和金星廓线测量仪（PMV，傅立叶光谱仪FS-1/4）在红外光谱的不同部分独立记录的。MWR性能研究使用合成光谱在不同的纬度和不同的大气温度廓线和云参数。VIRTIS和PMV反演结果的比较被用来确定物理状态参数变化的约束条件，特别是对不同的云模式的适用性。提出了一个四模态云高度分布的解析参数化初始模式。连同检索的云参数，其中包括个人模式的因素和云的高空边界，它允许最佳拟合的测量辐射和亮度温度在4.3和15 μ m的CO2波段用于大气温度廓线检索。一种新的多光谱检索（MSR）方法（卡佩尔等人，2012.卡佩尔，出版中）提供了影响短波发射窗口云参数反演的深大气CO2不透明度校正参数，反演的纬度和高度相关温度场（纬向平均）的主要特征与以前的结果在定量上有很好的一致性。突出的结构，如“冷领”和“热偶极子”重新审查。逆温层的中心约在62-66公里，北纬55和75度。在环圈以下，温度通常随着纬度在相同的高度下降，而它通常会向70公里以上的极点增加。VIRTIS和PMV结果的纬向平均值之间的绝对温度差通常低于3 K之间的58和80公里，而一个9 K低VIRTIS温度只观察到在75度N近60公里。VIRTIS和PMV反演都显示云顶高度从赤道的约71公里缓慢下降到中纬度的约70公里。向北55度N，它迅速下降到约61.5公里，在极地纬度根据早期的结果。云粒子大小和云总光学厚度在北纬50度处最小，向赤道和北极方向增加。由VIRTIS资料得到的云不透明度半球平均值为34.7 μ m。(C)2013爱思唯尔有限公司保留所有权利。
Improved radiative transfer simulation and multi-window retrieval procedures (MWR) are described that are applied to investigate thermal structure and cloud features in the nightside atmosphere of Venus over the northern hemisphere. Comparative analyses of spectroscopic data, which were recorded independently in different parts of the infrared spectrum by the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS-M-IR) aboard ESA's Venus Express space probe and the Profile Measuring Instrument for Venus (PMV, Fourier spectrometer FS-1/4) during the earlier Soviet Venera-15 experiment, are combined with self-consistent temperature profile and cloud parameter retrievals. MWR performance is studied using synthetic spectra at different latitudes and for different atmospheric temperature profiles and cloud parameters. VIRTIS and PMV retrieval result comparisons are used to determine constraints on physical state parameter variations, especially on applicability of different cloud models. An analytically parameterized initial model of four-modal cloud altitude distributions is proposed. Together with retrieved cloud parameters, which encompass individual mode factors and cloud upper altitude boundary, it permits optimum fits of measured radiances and brightness temperatures in the 4.3 and 15 mu m CO2 bands utilized for atmospheric temperature profile retrievals. A new multi-spectrum retrieval (MSR) method (Kappel et al., 2012. Kappel, in press) provides deep atmosphere CO2 opacity correction parameters, which affect cloud parameter retrievals from short-wavelength emission windows.The main features of retrieved latitude and altitude-dependent temperature fields (zonal averages) are in good quantitative accordance with earlier obtained results. Prominent structures like 'cold collar' and 'hot dipole' are re-examined. The cold inversion layer is centered at about 62-66 km and 55 and 75 degrees N. Below the collar, temperature usually decreases with latitude at the same altitude, while it typically increases toward the pole above 70 km. Absolute temperature differences between zonal averages of VIRTIS and PMV results are usually below 3 K between 58 and 80 km, while a 9 K lower VIRTIS temperature is only observed at 75 degrees N near 60 km. Both VIRTIS and PMV retrievals reveal a slow decrease of cloud top altitude from about 71 km at the equator to about 70 km at mid latitudes. Northward of 55 degrees N, it quickly descends down to about 61.5 km at polar latitudes in accordance with earlier results. Cloud particle size and total cloud optical depth exhibit a minimum at 50 degrees N and increase towards the equator and the North Pole. The hemispheric average of cloud opacity derived from VIRTIS data is 34.7 at 1 mu m. (C) 2013 Elsevier Ltd. All rights reserved.