Assessing the long-term variability of Venus winds at cloud level from VIRTIS-Venus Express
Assessing the long-term variability of Venus winds at cloud level from VIRTIS-Venus Express
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DOI：
10.1016/j.icarus.2011.04.020
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发表时间：
2012-02-01
期刊：
影响因子：
3.2
通讯作者：
Sanchez-Lavega, A.
中科院分区：
文献类型：
--
作者：
Hueso, R.;Peralta, J.;Sanchez-Lavega, A.
金星快车（VEX）使命已经在金星轨道上运行了4年多。VEX上的可见光和红外热成像光谱仪（VIRTIS）仪器通过两个通道（可见光和红外线）观测金星，获得该行星的光谱和多波长图像，可用于在不同高度对大气进行采样。日侧紫外线（380纳米）图像用于研究66-72公里高空云层的动态，而夜侧近红外线（1.74微米）图像则用于绘制44-48公里低空云层的不透明度。在这里，我们提出了一个长期的全球大气动力学分析，在这些水平上使用了大量的轨道选择从VIRTIS-M数据集覆盖860个地球日，扩展了我们以前的工作（桑切斯Lavega，A。等人[2008]。地球物理学家。保留信函35，L13204），并允许研究全球环流的变化在两个高度水平。在赤道到中纬度向西的速度为100和60 m s（-1）的上层和下层云层中，大气的超旋转是明显的。这些纬向速度在从赤道到南纬50度的纬度上几乎是恒定的。从南纬50度到南纬90度，两个云层的纬向风稳定地减少到极点的零。单个云跟踪风的误差为3-10 m s（-1），平均值为5 m s（-1），我们的纬向和纬向风的标准偏差为9 m s（-1）。上层云的纬向风随当地时间的变化可以用太阳潮来解释。低层云中的纬向风在中纬度到热带地区是稳定的，而在副极纬度地区则存在明显的变化，这显然与南极涡旋的活动有关。虽然上层云呈现出与Hadley环流的上分支一致的净纬向运动，在50 ° S处具有峰值速度v = 10 m s（-1），但下层云纬向运动的组织性较差，一些云特征以强烈的向北和向南运动（v = +/- 15 m s（-1））移动，但平均而言，在所有纬度上几乎没有全球纬向运动。我们还通过将我们的扩展风跟踪数据与以前任务的结果进行比较，研究了这两个垂直层的风的长期行为。(C)2011 Elsevier Inc. All rights reserved.
The Venus Express (VEX) mission has been in orbit to Venus for more than 4 years now. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument onboard VEX observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet that can be used to sample the atmosphere at different altitudes. Day-side images in the ultraviolet range (380 nm) are used to study the dynamics of the upper cloud at 66-72 km while night-side images in the near infrared (1.74 mu m) map the opacity of the lower cloud deck at 44-48 km. Here we present a long-term analysis of the global atmospheric dynamics at these levels using a large selection of orbits from the VIRTIS-M dataset covering 860 Earth days that extends our previous work (Sanchez-Lavega, A. et al. [2008]. Geophys. Res. Lett. 35, L13204) and allows studying the variability of the global circulation at the two altitude levels. The atmospheric superrotation is evident with equatorial to mid-latitudes westward velocities of 100 and 60 m s(-1) in the upper and lower cloud layers. These zonal velocities are almost constant in latitude from the equator to 50 degrees S. From 50 degrees S to 90 degrees S the zonal winds at both cloud layers decrease steadily to zero at the pole. Individual cloud tracked winds have errors of 3-10 m s(-1) with a mean of 5 m s(-1) and the standard deviations for a given latitude of our zonal and meridional winds are 9 m s(-1). The zonal winds in the upper cloud change with the local time in a way that can be interpreted in terms of a solar tide. The zonal winds in the lower cloud are stable at mid-latitudes to the tropics and present variability at subpolar latitudes apparently linked to the activity of the South polar vortex. While the upper cloud presents a net meridional motion consistent with the upper branch of a Hadley cell with peak velocity v = 10 m s(-1) at 50 degrees S, the lower cloud meridional motions are less organized with some cloud features moving with intense northwards and southwards motions up to v = +/- 15 m s(-1) but, on average, with almost null global meridional motions at all latitudes. We also examine the long-term behavior of the winds at these two vertical layers by comparing our extended wind tracked data with results from previous missions. (C) 2011 Elsevier Inc. All rights reserved.