Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter-猫眼课题宝

DOI：

10.1038/s41586-019-1097-3

发表时间：

2019-04

期刊：

Nature

影响因子：

64.8

通讯作者：

中科院分区：

综合性期刊1区

文献类型：

作者：

A. Vandaele;O. Korablev;F. Daerden;S. Aoki;I. Thomas;F. Altieri;M. López‐Valverde;G. Villanueva;G. Liuzzi;Michael D. Smith;J. Erwin;L. Trompet;A. Fedorova;F. Montmessin;A. Trokhimovskiy;D. Belyaev;N. Ignatiev;M. Luginin;K. Olsen;L. Baggio;J. Alday;J. Bertaux;D. Betsis;D. Bolsée;R. Clancy;E. Cloutis;C. Depiesse;B. Funke;M. García-Comas;J. Gérard;M. Giuranna;F. González-Galindo;A. Grigoriev;Y. Ivanov;J. Kaminski;O. Karatekin;F. Lefévre;S. Lewis;M. López‐Puertas;A. Mahieux;I. Maslov;J. Mason;M. Mumma;L. Neary;E. Neefs;A. Patrakeev;D. Patsaev;B. Ristic;S. Robert;F. Schmidt;A. Shakun;N. Teanby;S. Viscardy;Y. Willame;J. Whiteway;V. Wilquet;M. Wolff;G. Bellucci;Manish R. Patel;J. Lopez‐Moreno;F. Forget;Colin F. Wilson;H. Svedhem;J. Vago;D. Rodionov;Nomad Team;Acs Science Team

火星上的全球沙尘暴很罕见，但可以影响火星大气层长达数月。它们可以引起大气动力学的变化和大气的膨胀，主要是由于太阳能加热尘埃。反过来，大气动力学的变化会影响大气水蒸气的分布，从而对火星的大气光化学和气候产生潜在影响。最近对沙尘暴期间火星大气中水蒸气丰度的观测表明，大气中的水蒸气在高海拔地区增加，在北方高纬度地区更为明显，而在低纬度地区水柱减少。在这里，我们提出了并发的，高分辨率的测量灰尘，水和半重水（HDO）在全球沙尘暴的开始，获得了NOMAD和ACS仪器板载ExoMars微量气体轨道器。我们报告了从行星边界层到80公里高度的HDO/H2O比（D/H）的垂直分布。我们的研究结果表明，在沙尘暴开始之前，HDO丰度在40公里以上的高度降低到低于可探测性的水平。HDO的减少与水冰云的存在相吻合。在风暴期间，在40至80公里的高度观察到H2O和HDO的丰度增加。我们认为，这些增加的丰度可能是沙尘暴期间温度升高的结果，造成更强的大气环流，防止冰云形成，这可能会通过重力下降和随后的冰晶升华将水蒸气限制在较低的高度。观测到的H2O和HDO丰度的变化发生在沙尘暴发展的几天内，表明沙尘暴对火星大气的快速影响。

Global dust storms on Mars are rare,but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere, primarily owing to solar heating of the dust. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes,, as well as a decrease in the water column at low latitudes,. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H2O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.

Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter

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