A Survey of Photoelectrons on the Nightside of Mars

Abstract Despite produced exclusively on the dayside, photoelectrons, as an important population of the Martian ionosphere, have also been observed on the nightside. Here we present a statistical survey of nightside photoelectrons using the suprathermal electron measurements, made by the Solar Wind...

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Main Authors: Y. ‐T. Cao, J. Cui, X. ‐S. Wu, D. ‐D. Niu, H. ‐R. Lai, B. ‐B. Ni, Q. Luo, J. Yu, Y. Wei
Format: Article
Language:English
Published: Wiley 2021-01-01
Series:Geophysical Research Letters
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Online Access:https://doi.org/10.1029/2020GL089998
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author Y. ‐T. Cao
J. Cui
X. ‐S. Wu
D. ‐D. Niu
H. ‐R. Lai
B. ‐B. Ni
Q. Luo
J. Yu
Y. Wei
author_facet Y. ‐T. Cao
J. Cui
X. ‐S. Wu
D. ‐D. Niu
H. ‐R. Lai
B. ‐B. Ni
Q. Luo
J. Yu
Y. Wei
author_sort Y. ‐T. Cao
collection DOAJ
description Abstract Despite produced exclusively on the dayside, photoelectrons, as an important population of the Martian ionosphere, have also been observed on the nightside. Here we present a statistical survey of nightside photoelectrons using the suprathermal electron measurements, made by the Solar Wind Electron Analyzer onboard the Mars Atmosphere and Volatile Evolution. We find that nearly 30% of the available nightside suprathermal electron spectra show clear photoelectron signatures. Nightside photoelectrons have an occurrence rate that decreases with increasing solar zenith angle and they are characterized by a preferentially field‐aligned pitch angle distribution. Our analysis also suggests that nightside photoelectrons are less likely observed under the high solar wind condition. These observations are favorably interpreted by the scenario of photoelectron transport along cross‐terminator magnetic field lines, as supported by a simplified test particle model. Our study highlights a complex plasma environment near Mars modulated by both internal and external conditions.
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publishDate 2021-01-01
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series Geophysical Research Letters
spelling doaj-art-a0ed19c41d4741fcbfbf2eacdfcd67f42025-08-20T03:07:23ZengWileyGeophysical Research Letters0094-82761944-80072021-01-01482n/an/a10.1029/2020GL089998A Survey of Photoelectrons on the Nightside of MarsY. ‐T. Cao0J. Cui1X. ‐S. Wu2D. ‐D. Niu3H. ‐R. Lai4B. ‐B. Ni5Q. Luo6J. Yu7Y. Wei8School of Atmospheric Sciences Sun Yat‐sen University Zhuhai Guangdong ChinaSchool of Atmospheric Sciences Sun Yat‐sen University Zhuhai Guangdong ChinaNational Astronomical Observatories Chinese Academy of Sciences Beijing ChinaInstitute of Space Science and Applied Technology Harbin Institute of Technology Shenzhen Guangdong ChinaSchool of Atmospheric Sciences Sun Yat‐sen University Zhuhai Guangdong ChinaDepartment of Space Physics, School of Electronic Information Wuhan University Wuhan Hubei ChinaDepartment of Space Physics, School of Electronic Information Wuhan University Wuhan Hubei ChinaSchool of Atmospheric Sciences Sun Yat‐sen University Zhuhai Guangdong ChinaInstitute of Geology and Geophysics Chinese Academy of Sciences Beijing ChinaAbstract Despite produced exclusively on the dayside, photoelectrons, as an important population of the Martian ionosphere, have also been observed on the nightside. Here we present a statistical survey of nightside photoelectrons using the suprathermal electron measurements, made by the Solar Wind Electron Analyzer onboard the Mars Atmosphere and Volatile Evolution. We find that nearly 30% of the available nightside suprathermal electron spectra show clear photoelectron signatures. Nightside photoelectrons have an occurrence rate that decreases with increasing solar zenith angle and they are characterized by a preferentially field‐aligned pitch angle distribution. Our analysis also suggests that nightside photoelectrons are less likely observed under the high solar wind condition. These observations are favorably interpreted by the scenario of photoelectron transport along cross‐terminator magnetic field lines, as supported by a simplified test particle model. Our study highlights a complex plasma environment near Mars modulated by both internal and external conditions.https://doi.org/10.1029/2020GL089998Martian ionosphereMAVENPhotoelectrons
spellingShingle Y. ‐T. Cao
J. Cui
X. ‐S. Wu
D. ‐D. Niu
H. ‐R. Lai
B. ‐B. Ni
Q. Luo
J. Yu
Y. Wei
A Survey of Photoelectrons on the Nightside of Mars
Geophysical Research Letters
Martian ionosphere
MAVEN
Photoelectrons
title A Survey of Photoelectrons on the Nightside of Mars
title_full A Survey of Photoelectrons on the Nightside of Mars
title_fullStr A Survey of Photoelectrons on the Nightside of Mars
title_full_unstemmed A Survey of Photoelectrons on the Nightside of Mars
title_short A Survey of Photoelectrons on the Nightside of Mars
title_sort survey of photoelectrons on the nightside of mars
topic Martian ionosphere
MAVEN
Photoelectrons
url https://doi.org/10.1029/2020GL089998
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