On the impact of the vertical structure of Martian water ice clouds on nadir atmospheric retrievals from simultaneous EMM/EXI and TGO/ACS-MIR observations.

IF 2.5 2区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS
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Abstract

Retrieving the optical depth of the Martian clouds (τcld) is a powerful way to monitor their spatial and temporal evolution. However, such retrievals from nadir imagery rely on several assumptions, including the vertical structure of the clouds in the atmosphere. Here we compare the results of cloud optical depth retrievals at 320 nm from the Emirates eXploration Imager (EXI) onboard the Emirates Mars Mission (EMM) “Hope” orbiter performed using a basic uniform cloud profile used in previous studies and using derived cloud profiles obtained from near-simultaneous Solar Occultation observations in the 3.1–3.4 μm spectral range from the Middle-Infrared channel of the Atmospheric Chemistry Suite (ACS) instrument onboard the ESA Trace Gas Orbiter (TGO). We show that the latitudinal dependence of the cloud vertical profiles can have a strong impact on the nadir retrievals; neglecting it can lead to a significant underestimation of τcld in the polar regions (up to 25 % to 50 %, depending on the vertical distribution of the dust in the atmosphere) and to a lesser extent, to an overestimation of τcld around the equator. We also discuss the impact of a vertically-dependent particle size profile, as previous studies have shown the presence of very small water ice particles at the top of the clouds. From this analysis, we provide recommendations for the improvement of water ice cloud parameterization in radiative transfer algorithms in nadir atmospheric retrievals.
关于火星水冰云垂直结构对 EMM/EXI 和 TGO/ACS-MIR 同步观测的天底大气检索的影响。
检索火星云层的光学深度(τcld)是监测其空间和时间演变的有力方法。然而,从天底图像进行此类检索依赖于若干假设,包括大气中云层的垂直结构。在这里,我们比较了阿联酋火星任务(EMM)"希望 "号轨道飞行器上的阿联酋增殖成像仪(EXI)在320纳米波长处的云光学深度检索结果,该检索使用了以往研究中使用的基本均匀云剖面,以及欧空局痕量气体轨道飞行器(TGO)上大气化学套件(ACS)仪器的中红外通道在3.1-3.4微米光谱范围内近同步太阳掩星观测所获得的衍生云剖面。我们的研究表明,云垂直剖面的纬度依赖性会对天底数据检索产生很大影响;忽略纬度依赖性会导致极地地区的 τcld 被严重低估(高达 25% 至 50%,取决于大气中尘埃的垂直分布),其次会导致赤道附近的 τcld 被高估。我们还讨论了与垂直方向有关的粒径分布的影响,因为之前的研究显示云层顶部存在非常小的水冰颗粒。通过上述分析,我们为改进天底大气探测辐射传递算法中的水冰云参数化提出了建议。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Icarus
Icarus 地学天文-天文与天体物理
CiteScore
6.30
自引率
18.80%
发文量
356
审稿时长
2-4 weeks
期刊介绍: Icarus is devoted to the publication of original contributions in the field of Solar System studies. Manuscripts reporting the results of new research - observational, experimental, or theoretical - concerning the astronomy, geology, meteorology, physics, chemistry, biology, and other scientific aspects of our Solar System or extrasolar systems are welcome. The journal generally does not publish papers devoted exclusively to the Sun, the Earth, celestial mechanics, meteoritics, or astrophysics. Icarus does not publish papers that provide "improved" versions of Bode''s law, or other numerical relations, without a sound physical basis. Icarus does not publish meeting announcements or general notices. Reviews, historical papers, and manuscripts describing spacecraft instrumentation may be considered, but only with prior approval of the editor. An entire issue of the journal is occasionally devoted to a single subject, usually arising from a conference on the same topic. The language of publication is English. American or British usage is accepted, but not a mixture of these.
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