Seasonal cap dynamics at the South Pole of Mars in the 36th Martian year, observed by Tianwen-1

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

Icarus Pub Date : 2024-08-15 DOI:10.1016/j.icarus.2024.116266

Zhibin Li , Jianjun Liu , Zhaopeng Chen , Wei Yan , Zongyu Zhang , Qing Zhang , Yuxuan Luo

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引用次数: 0

Abstract

The seasonal variation of the Martian South Polar Seasonal Cap (SPSC) is a significant factor to influence Mars atmospheric cycle, which has been continuously observed in previous missions. The SPSC degrades asymmetrically throughout the Martian seasons. However, developing a general description for this asymmetric recession is challenging, and this is crucial for identifying key stages (timesteps) which represents moments of special attribute throughout the recession. Here, we present the Martian Year 36 (MY36) results from the continuous observation of the Martian SPSC by the Moderate Resolution Imaging Camera (MoRIC) onboard the Tianwen-1 orbiter. A time-series of digital orthophoto maps (DOMs) characterizing the south cap were collected ranging from the solar longitude (L_s) 210° to 332°. A seasonal recession model of the cap was established by incorporating a 5th-order polynomial fitting of the time-series on cap latitude, from which the first derivative (recession rate), second derivative (acceleration), and third derivative (jerk) can be obtained. This methodology enables the extraction of critical timesteps that facilitate the categorization of the recession into distinct phases, each characterized by its recession rate and other factors. By the visual interpretation of remote sensing images obtained by Tianwen-1 and the result of timesteps showed that the pause time of the South Polar Residual Cap (SPRC) is about L_s = 324.5°-328° with an area of 7.9 × 10⁴ km². The discrepancies between our results and previous investigations indicate that the Martian climate presents inter-annual fluctuations. The MoRIC image data can be used to quantitatively capture the fine recession dynamic of the southern polar cap.The continuous operation of the Tianwen-1 orbiter will enable further data analysis for the dynamics of the Martian polar caps. This will provide observational constraints for Martian climate models and crucial information for the research of the Martian modern climate.

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天文一号观测到的第 36 个火星年火星南极的季节性盖层动态

火星南极季相冠（SPSC）的季节变化是影响火星大气循环的一个重要因素，这在以前的任务中已被持续观测到。火星南极季冠在整个火星季节中不对称地衰退。然而，对这种非对称衰退进行一般性描述具有挑战性，这对于确定代表整个衰退过程中特殊属性时刻的关键阶段（时间步）至关重要。在此，我们介绍了天文一号轨道飞行器上的中分辨率成像相机（MoRIC）对火星SPSC进行连续观测的火星第36年（MY36）的结果。采集了从太阳经度（Ls）210°到332°的一系列描述南冠特征的时间序列数字正射影像图（DOMs）。通过将时间序列与南帽纬度进行五阶多项式拟合，建立了南帽的季节性衰退模型，从中可以得到一阶导数（衰退率）、二阶导数（加速度）和三阶导数（挺进）。通过这种方法，可以提取关键的时间步，从而将衰退分为不同的阶段，每个阶段都有其衰退速率和其他因素。通过对 "天文一号 "获取的遥感图像的目视判读和时间步的结果表明，南极残余盖（SPRC）的停顿时间约为 Ls = 324.5°-328°，面积为 7.9 × 104 平方公里。我们的研究结果与之前的研究结果存在差异，这表明火星气候存在年际波动。MoRIC图像数据可用于定量捕捉南极盖的细微衰退动态。"天文一号 "轨道飞行器的持续运行将有助于对火星极盖的动态进行进一步的数据分析。天文一号轨道飞行器的持续运行将能够对火星极冠的动态进行进一步的数据分析，这将为火星气候模型提供观测约束，并为火星现代气候研究提供重要信息。

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 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.