A warm layer in Venus' cryosphere and high-altitude measurements of HF, HCl, H2O and HDO
A warm layer in Venus' cryosphere and high-altitude measurements of HF, HCl, H2O and HDO
复制标题
金星冰冻圈中的温暖层以及 HF、HCl、H2O 和 HDO 的高空测量
作者：
J. Bertaux;A. Vandaele;O. Korablev;E. Villard;A. Fedorova;D. Fussen;E. Quémerais;D. Belyaev;A. Mahieux;F. Montmessin;C. Muller;E. Neefs;D. Nevejans;V. Wilquet;J. Dubois;Alain Hauchecorne;A. Stepanov;I. Vinogradov;A. Rodin
金星有厚厚的H2SO 4气溶胶粒子云，从40到60公里的高度延伸。60-100 km区域（中间层）是厚云顶部4天逆行超旋与热层（100 km以上）太阳-反太阳环流之间的过渡区，在太阳下点有上升流并向夜面输送。中间层有一层光学厚度可变的薄雾，CO、SO2、HCl、HF、H2O和HDO是最重要的次要气体成分，但薄雾和分子的垂直分布情况知之甚少，因为以前的下降探测器是在60公里或以下开始测量的。在这里，我们报告检测到一个广泛的暖空气层在海拔90-120公里的夜晚，我们解释为绝热加热的结果，在空气沉降。如此强烈的逆温是没有预料到的，因为金星的夜晚是如此寒冷，以至于它被命名为100公里以上的“冰冻圈”。我们还测量了HF，HCl，H2O和HDO的中间层分布。HCl的丰度低于40年前的报告。HDO/H2O相对于低层大气增加了2.5倍，在80-90公里附近H2O普遍减少，对此我们无法解释。
Venus has thick clouds of H2SO4 aerosol particles extending from altitudes of 40 to 60 km. The 60–100 km region (the mesosphere) is a transition region between the 4 day retrograde superrotation at the top of the thick clouds and the solar–antisolar circulation in the thermosphere (above 100 km), which has upwelling over the subsolar point and transport to the nightside. The mesosphere has a light haze of variable optical thickness, with CO, SO2, HCl, HF, H2O and HDO as the most important minor gaseous constituents, but the vertical distribution of the haze and molecules is poorly known because previous descent probes began their measurements at or below 60 km. Here we report the detection of an extensive layer of warm air at altitudes 90–120 km on the night side that we interpret as the result of adiabatic heating during air subsidence. Such a strong temperature inversion was not expected, because the night side of Venus was otherwise so cold that it was named the ‘cryosphere’ above 100 km. We also measured the mesospheric distributions of HF, HCl, H2O and HDO. HCl is less abundant than reported 40 years ago. HDO/H2O is enhanced by a factor of ∼2.5 with respect to the lower atmosphere, and there is a general depletion of H2O around 80–90 km for which we have no explanation.