Measurements of Forbush decreases at Mars: both by MSL on ground and by MAVEN in orbit
Measurements of Forbush decreases at Mars: both by MSL on ground and by MAVEN in orbit
复制标题
DOI：
10.1051/0004-6361/201732087
复制
发表时间：
2017-12
影响因子：
6.5
通讯作者：
Jingnan Guo;R. Lillis;R. Wimmer–Schweingruber;C. Zeitlin;Patrick Simonson;A. Rahmati;A. Posner;A. Papaioannou;Niklas Lundt;Christina O. Lee;D. Larson;J. Halekas;D. Hassler;B. Ehresmann;P. Dunn;S. Boettcher
中科院分区：
文献类型：
--
作者：
Jingnan Guo;R. Lillis;R. Wimmer–Schweingruber;C. Zeitlin;Patrick Simonson;A. Rahmati;A. Posner;A. Papaioannou;Niklas Lundt;Christina O. Lee;D. Larson;J. Halekas;D. Hassler;B. Ehresmann;P. Dunn;S. Boettcher
自2012年8月以来，火星科学实验室（MSL）的好奇号火星车上的辐射评估探测器（RAD）一直在测量火星表面的地面粒子通量和辐射剂量率。与地球上的中子监测器类似，RAD在银河宇宙射线（GCR）引起的表面通量和剂量率中看到许多福布什衰减（FDs）。这些fd与日冕物质抛射（cme）和/或流/旋转相互作用区（SIRs/CIRs）有关。自2014年9月以来，火星大气和挥发物演化（MAVEN）航天器一直在火星大气层上方运行，监测火星的空间天气状况。MAVEN上的太阳高能粒子（SEP）仪器的穿透粒子通量通道也可用于探测fd。我们首次研究了在火星现场观测到的fd的统计和性质，这些fd分别是由MSL/RAD在火星表面观测到的，以及由MAVEN/SEP仪器在火星轨道上探测到的。这样的fd列表可以用于研究星际CME （ICME）的传播和SIR通过内日球层的演变。不同fd的大小可以用幂律分布很好地拟合。火星大气内外fd大小的系统差异可能主要归因于经过的ICMEs/SIRs和火星大气对GCR粒子的能量依赖性调制。
The Radiation Assessment Detector (RAD), on board Mars Science Laboratory's (MSL) Curiosity rover, has been measuring ground level particle fluxes along with the radiation dose rate at the surface of Mars since August 2012. Similar to neutron monitors at Earth, RAD sees many Forbush decreases (FDs) in the galactic cosmic ray (GCR) induced surface fluxes and dose rates. These FDs are associated with coronal mass ejections (CMEs) and/or stream/corotating interaction regions (SIRs/CIRs). Orbiting above the Martian atmosphere, the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has also been monitoring space weather conditions at Mars since September 2014. The penetrating particle flux channels in the Solar Energetic Particle (SEP) instrument onboard MAVEN can also be employed to detect FDs. For the first time, we study the statistics and properties of a list of FDs observed in-situ at Mars, seen both on the surface by MSL/RAD and in orbit detected by the MAVEN/SEP instrument. Such a list of FDs can be used for studying interplanetary CME (ICME) propagation and SIR evolution through the inner heliosphere. The magnitudes of different FDs can be well-fitted by a power-law distribution. The systematic difference between the magnitudes of the FDs within and outside the Martian atmosphere may be mostly attributed to the energy-dependent modulation of the GCR particles by both the pass-by ICMEs/SIRs and the Martian atmosphere.