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Photoelectron pitch angle distribution near Mars and implications on cross terminator magnetic field connectivity

Earth and Planetary Physics 2020年第1期4卷 17-22页

作者： YuTian Cao Jun Cui XiaoShu Wu JiaHao Zhong Key Laboratory of Lunar and Deep Space Exploration National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China School of Atmospheric Sciences Sun Yat-sen UniversityZhuhai Guangdong 519082China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefei 230026China

The photoelectron peak at 22 27 eV, a distinctive feature of the energetic electron distribution in the dayside Martian ionosphere, is a useful diagnostic of solar extreme ultraviolet (EUV) and X-ray ionization as well as of large-scale transport along magnetic field lines. In this work, we analyze the pitch angle distribution (PAD) of energetic electrons at 22 27 eV measured during several representative Mars Atmosphere and Volatile Evolution (maven) orbits, based on the electron spectra gathered by maven’s Solar Wind Electron Analyzer (SWEA) instrument. On the dayside, most photoelectron spectra show an isotropic PAD as is expected from production via solar EUV/X-ray ionization. The photoelectron spectra occasionally observed on the nightside show instead a strongly anisotropic PAD, indicative of cross-terminator transport along ambient magnetic field lines. This would in turn predict the presence of dayside photoelectrons, also with a strongly anisotropic PAD, which was indeed revealed in SWEA data. Comparison with magnetic field measurements made by the maven Magnetometer suggests that on average the photoelectrons with anisotropic PAD stream away from Mars on the dayside and towards Mars on the nightside, further supporting the scenario of day-to-night transport. On both sides, anisotropic photoelectrons tend to be observed above the photoelectron exobase at ~160 km where photoelectron transport dominates over local production and energy degradation.

关键词： Mars maven photoelectron Day-to-night transport

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Response of photoelectron peaks in the Martian ionosphere to solar EUV/X-ray irradiance

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Earth and Planetary Physics 2020年第4期4卷 390-395页

作者： XiaoShu Wu Jun Cui YuTian Cao WeiQin Sun Qiong Luo BinBin Ni National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China Planetary Environmental and Astrobiological Research Laboratory(PEARL) School of Atmospheric SciencesSun Yat-sen UniversityZhuhai Guangdong 519082China Chinese Academy of Sciences Center for Excellence in Comparative Planetology Hefei 230026China Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430074China

An important population of the dayside Martian ionosphere are photoelectrons that are produced by solar Extreme Ultraviolet and X-ray ionization of atmospheric neutrals.A typical photoelectron energy spectrum is characterized by a distinctive peak near 27 eV related to the strong solar HeⅡ emission line at 30.4 nm,and an additional peak near 500 eV related to O Auger *** this study,the extensive measurements made by the Solar Wind Electron Analyzer on board the recent Mars Atmosphere and Volatile Evolution spacecraft are analyzed and found to verify the scenario that Martian ionosphere photoelectrons are driven by solar *** report that the photoelectron intensities at the centers of both peaks increase steadily with increasing solar ionizing flux below 90 nm and that the observed solar cycle variation is substantially more prominent near the O Auger peak than near the HeⅡ *** latter observation is clearly driven by a larger variability in solar irradiance at shorter *** the solar ionizing flux increases from 1 mW·m^-2 to 2.5 mW·m^-2,the photoelectron intensity increases by a factor of 3.2 at the HeⅡ peak and by a much larger factor of 10.5 at the O Auger peak,both within the optically thin regions of the Martian atmosphere.

关键词： Mars ionosphere photoelectron solar irradiance maven

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The variations of the Martian exobase altitude

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Earth and Planetary Physics 2020年第1期4卷 4-10页

作者： MengHao Fu Jun Cui XiaoShu Wu ZhaoPeng Wu Jing Li Key Laboratory of Lunar and Deep Space Exploration National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China School of Atmospheric Sciences Sun Yat-sen UniversityZhuhai Guangdong 519082China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefei 230026China

The exobase is defined as the interface between the strongly collisional and the collisionless parts of an atmosphere. Although in reality the exobase is a transition region of finite depth, it is conventionally defined as the boundary above which an upwardly ejected neutral particle makes one collision at higher altitudes. Such an idealized definition is of practical use and serves as a good tracer of the overall size of an atmosphere as it expands and contracts under the influences of both external and internal sources. Knowledge of the atmospheric properties near the exobase is crucial to first-order estimates of atmospheric escape rates on terrestrial planets. Since its arrival at Mars on 21 September 2014, the Mars Atmosphere and Volatile Evolution (maven) spacecraft has provided comprehensive maps of the Martian upper atmosphere under a variety of conditions. This allows, for the first time, a thorough investigation of the variations of the exobase altitude on this red planet. In this study, we use the N2 density measurements accumulated by maven’s Neutral Gas and Ion Mass Spectrometer from October 2014 to November 2018 to determine the exobase altitudes for a large number of maven orbits. Our analysis reveals clearly the variations of exobase altitude with local time and solar extreme ultraviolet (EUV) flux, as well as tentative evidence for the impact of global dust storms. These observations are indicative of thermal expansion of the Martian upper atmosphere, driven either externally by solar EUV energy deposition or internally by global dust storms.

关键词： Mars Exobase maven

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Solar control of CO2^+ultraviolet doublet emission on Mars

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Earth and Planetary Physics 2020年第6期4卷 543-549页

作者： ZiChuan Li Jun Cui Jing Li XiaoShu Wu JiaHao Zhong FaYu Jiang National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China Planetary Environmental and Astrobiological Research Laboratory(PEARL) School of Atmospheric SciencesSun Yat-Sen UniversityZhuhai Guangdong 519082China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefei 230026China Lunar and Planetary Laboratory University of ArizonaTucsonArizonaUSA

The CO2^+;ultraviolet doublet(UVD)emission near 289 nm is an important feature of dayside airglow emission from planetaryupper *** this study,we analyzed the brightness profiles of CO2^+;UVDemission on Mars by using the extensive observationsmade by the lmaging Ultraviolet Spectrograph on board the recent Mars Atmosphere and Volatle Evolution *** solar cycleand solar zenith angle variations in peak emission intensity and altitude were revealed by the data:(1)Both the peak intensity and altitude increase with increasing solar activity,and(2)the peak intensity decreases,whereas the peak altitude increases,with increasingsolar zenith *** observations can be favorably interpreted by the solar-driven scenario combined with the fact that photoionization and photoelectron impact ionization are the two most important processes responsible for the production of excited-state cotand consequently the intensity of CO2^+;*** this,we propose that an extra driver,presumably related to thecomplicated variation in the background atmosphere,such as the occurrence of globaldust storms is required to fuly interpret *** general,our analysis suggests that the CO2^+;UVD emission is a useful diagnostic of the variability of the dayside Martianatmosphere under the influences of both internal and external drivers.

关键词： Mars dayglow CO2^+ maven

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Photoelectron balance in the dayside Martian upper atmosphere

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Earth and Planetary Physics 2019年第5期3卷 373-379页

作者： XiaoShu Wu Jun Cui Jiang Yu LiJuan Liu ZhenJun Zhou National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Atmospheric Sciences Sun Yat-sen UniversityZhuhai Guangdong 519082China Chinese Academy of Sciences Center for Excellence in Comparative Planetology Hefei 230026China Space Science Institute Macao University of Science and TechnologyMacaoChina

Photoelectrons are produced by solar Extreme Ultraviolet radiation and contribute significantly to the local ionization and heat balances in planetary upper *** the effect of transport is negligible,the photoelectron energy distribution is controlled by a balance between local production and loss,a condition usually referred to as local energy *** this study,we examine such a condition for photoelectrons near Mars,with the aid of a multi-instrument Mars Atmosphere and Volatile Evolution data set gathered over the inbound portions of a representative dayside maven *** photoelectron production and loss processes considered here include primary and secondary ionization,inelastic collisions with atmospheric neutrals associated with both excitation and ionization,as well as Coulomb collisions with ionospheric thermal *** calculations indicate that photoelectron production occurs mainly via primary ionization and degradation from higher energy states during inelastic collisions;photoelectron loss appears to occur almost exclusively via degradation towards lower energy states via inelastic collisions above 10 eV,but the effect of Coulomb collisions becomes important at lower *** the energy range of 30–55 eV(chosen to reduce the influence of the uncertainty in spacecraft charging),we find that the condition of local energy degradation is very well satisfied for dayside photoelectrons from 160 to 250 *** evidence of photoelectron transport is present over this energy range.

关键词： Mars Photoelectron maven

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火星电离层电子浓度昼夜变化特性研究

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地球物理学报 2018年第8期61卷 3113-3123页

作者：张学习雷久侯万卫星钟嘉豪中国科学技术大学地球和空间科学学院合肥230026 中国科学院地质与地球物理研究所北京100029

本文利用maven卫星Langmuir Probe and Waves(LPW)仪器的在轨电子浓度探测数据,研究了火星电离层电子浓度随太阳天顶角(Solar Zenith Angle,SZA)的变化以及昼夜电子浓度变化的异同.基于2014年至2017年期间maven的电子浓度数据,我们发现:... 详细信息

本文利用maven卫星Langmuir Probe and Waves(LPW)仪器的在轨电子浓度探测数据,研究了火星电离层电子浓度随太阳天顶角(Solar Zenith Angle,SZA)的变化以及昼夜电子浓度变化的异同.基于2014年至2017年期间maven的电子浓度数据,我们发现:在200km以下,白天电离层电子浓度主要受光化学平衡控制,由于白天光电离过程使得昼夜电子浓度差异较大,此时电离层昼夜传输能影响到的最大范围约在SZA=110°;而在200km以上,白天电离层受输运过程控制,此时昼夜电子浓度差别较小,电离层昼夜间电子浓度变化较为缓慢.通过研究maven在deep-dip(低高度深入探测)期间的电子浓度数据,我们发现火星磁场会显著影响夜间200km以下的电子浓度分布结构,强磁场中闭合磁力线对电子沉降过程的阻碍作用使得在夜间该区域的电子浓度小于相邻区域.同时,通过比较deep-dip期间昼夜电子浓度随高度的变化,发现夜间电子沉降作用的影响可能主要集中在160km以下.

关键词：火星 maven 电离层电子浓度太阳天顶角昼夜

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火星弓激波上游高能拾起氧离子实例分析

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地球物理学报 2024年第1期67卷 12-20页

作者：雷桓郭建鹏何林峡林海博常克文陈艳北京师范大学天文与天体物理前沿科学研究所北京102206 北京师范大学天文系行星与空间物理研究团组北京100875

火星外逸层中的氧原子(O)经光致电离、电荷交换或电子碰撞产生氧离子(O^(+)),新生O^(+)随即被太阳风拾起,进而被对流电场加速.这些O^(+)被称为“拾起”O^(+).2018年11月17日08∶54∶00—10∶24∶00 UT期间,火星大气和挥发物演化任务(Mar... 详细信息

火星外逸层中的氧原子(O)经光致电离、电荷交换或电子碰撞产生氧离子(O^(+)),新生O^(+)随即被太阳风拾起,进而被对流电场加速.这些O^(+)被称为“拾起”O^(+).2018年11月17日08∶54∶00—10∶24∶00 UT期间,火星大气和挥发物演化任务(Mars Atmosphere and Volatile EvolutioN,maven)卫星从上游太阳风进入磁鞘中,持续观测到背离太阳运动的高能拾起O^(+)(约30 keV),在相空间呈现为初速度不为零的部分环分布.分析表明:这部分高能O^(+)的初始能量较高,回旋半径较大,位于摆线运动的高能区域,穿越火星弓激波进入磁鞘,离子在该范围内能量变化不显著,只是使得相应环分布在穿越弓激波后发生偏转.这些结果有助于进一步认识火星空间高能拾起O^(+)的产生与运动轨迹.

关键词：火星拾起氧离子 maven

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火星磁鞘区反射拾起氧离子事件分析

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地球物理学报 2023年第12期66卷 4840-4849页

作者：常克文郭建鹏何林峡林海博雷桓陈艳孔令高北京师范大学天文与天体物理前沿科学研究所北京102206 北京师范大学天文系行星与空间物理研究团组北京100875 南京大学(苏州校区)深空探测科学与技术研究院江苏苏州215163 中国科学院国家空间科学中心北京100190

火星逃逸层中性成分经光致电离、电荷交换和电子碰撞产生新生离子,新生离子随即被太阳风和火星磁鞘电磁场拾起,称为“拾起”离子.已有观测表明拾起氧离子(O^(+))在朝向火星沉降途中会被反射,但发生反射的空间位置和反射机制尚不十分明确... 详细信息

火星逃逸层中性成分经光致电离、电荷交换和电子碰撞产生新生离子,新生离子随即被太阳风和火星磁鞘电磁场拾起,称为“拾起”离子.已有观测表明拾起氧离子(O^(+))在朝向火星沉降途中会被反射,但发生反射的空间位置和反射机制尚不十分明确.若反射离子持续进入探测器,将为我们追踪反射发生的空间位置提供重要机遇.本文将报道这样一个观测实例,2016年9月25日04∶18∶30—04∶24∶54 UT期间,火星大气和挥发物演化任务(Mars Atmosphere and Volatile EvolutioN,maven)运行在-E半球(对流电场E指向火星)的磁鞘区,轨道高度逐渐降低,持续观测到背离火星运动的O^(+)(10^(3)~10^(4)eV)束流,即正在反射的拾起O^(+).反射拾起O^(+)大致可分为两部分:相空间密度较高、能量较低的部分是由磁鞘拾起O^(+)被反射后形成;相空间密度较低、能量较高的部分则源于太阳风拾起O^(+)发生反射后形成.我们推断反射发生在感应磁层边界附近的强磁场区域.

关键词：火星拾起离子离子反射 maven

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火星电离层不规则体的分类研究

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中国科学：地球科学 2024年第10期54卷 3340-3363页

作者：万欣钟嘉豪郝永强熊超王慧曹雨田崔峻刘裔文李巧玲蒯家伟中山大学大气科学学院行星环境与宜居性研究实验室(PEARL) 珠海519082 教育部热带大气海洋系统重点实验室珠海519082 武汉大学电子信息学院武汉430079 上饶师范学院物理与电子信息学院上饶334001 中国石油大学(北京)克拉玛依校区克拉玛依834000 南京航空航天大学航空航天学院南京210016

基于火星大气与挥发物演化任务(maven)的就位观测数据,本文对火星电离层等离子体密度的不规则结构进行初步的气候学分类研究.依据离子密度的扰动形式将不规则体分为增强、耗空和振荡类型.而通过判断离子密度扰动和的磁场扰动之间的相关... 详细信息

基于火星大气与挥发物演化任务(maven)的就位观测数据,本文对火星电离层等离子体密度的不规则结构进行初步的气候学分类研究.依据离子密度的扰动形式将不规则体分为增强、耗空和振荡类型.而通过判断离子密度扰动和的磁场扰动之间的相关性,可将这些不规则体进一步按照有无磁信号进行划分.研究表明,具有磁信号的不规则体倾向于出现在岩石圈磁异常区(MA)的外边界,而无磁信号的不规则体更倾向于出现在MA内部或外部,其具体分布特性与不规则体的类型和所在太阳天顶角有关.在大多数情况下,不规则体在电离层发电机高度以上(高于200km)依旧具有较高的发生率,说明其与离子的磁化状态无关.此外,无磁信号的增强型不规则体倾向于发生在垂直磁力线附近,与以往研究中发现的局地隆起结构类似,而其他类型的不规则体则几乎未表现出对磁场几何构型的依赖性.与以往研究相比,本文发现的诸多不规则体发生特性既存在相似性也存在差异性.本文揭示的火星电离层不规则体的气候学特征一方面可以作为以往研究的重要补充,另一方面也为未来阐明火星电离层不规则体的内在机理提供了关键的研究线索.

关键词：火星 maven 电离层电离层不规则体岩石圈磁异常等离子体

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基于CC和STAF的分布式持续集成和自动测试方案

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计算机工程与设计 2010年第23期31卷 5028-5031页

作者：贺旭李洪奇康璐遥中国石油大学计算机科学与技术系北京102249

为缩短大型软件的构建和测试时间以适应持续集成的要求,提出了分布式持续集成和自动测试方案。以CruiseCon-trol和STAF&STAX搭建分布式框架,把功能模块和测试案例分别以编译依赖性和测试相关性进行分组,以组为单位把源代码部署到多个编... 详细信息

为缩短大型软件的构建和测试时间以适应持续集成的要求,提出了分布式持续集成和自动测试方案。以CruiseCon-trol和STAF&STAX搭建分布式框架,把功能模块和测试案例分别以编译依赖性和测试相关性进行分组,以组为单位把源代码部署到多个编译机或测试机上并行地执行编译和测试,从而成倍地提高编译和测试效率。通过在大型石油测井软件项目实现持续集成的实例,验证了该方案的有效性。

关键词：软件测试自动化框架持续集成分布式持续集成分布式自动测试 maven CruiseControl STAX

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