Ionization Efficiency in the Dayside Martian Upper Atmosphere

被引：27

作者：

Cui, J. ^{[1
,2
,3
]}

Wu, X. -S. ^{[2
]}

Xu, S. -S. ^{[4
]}

Wang, X. -D. ^{[5
]}

Wellbrock, A. ^{[6
,7
]}

Nordheim, T. A. ^{[8
]}

Cao, Y. -T. ^{[2
]}

Wang, W. -R. ^{[2
]}

Sun, W. -Q. ^{[3
]}

Wu, S. -Q. ^{[9
]}

Wei, Y. ^{[10
]}

机构：

[1] Sun Yat Sen Univ, Sch Atmospher Sci, Zhuhai, Guangdong, Peoples R China

[2] Chinese Acad Sci, Natl Astron Observ, Beijing, Peoples R China

[3] Macau Univ Sci & Technol, Lunar & Planetary Sci Lab, Macau, Peoples R China

[4] Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA

[5] Swedish Inst Space Phys, Kiruna, Sweden

[6] Univ Coll London, Mullard Space Sci Lab, Dorking, Surrey, England

[7] Univ Coll London Birkbeck, Ctr Planetary Sci, London, England

[8] CALTECH, Jet Prop Lab, Pasadena, CA USA

[9] Beihang Univ, Sch Space & Environm, Beijing, Peoples R China

[10] Chinese Acad Sci, Inst Geol & Geophys, Beijing, Peoples R China

来源：

ASTROPHYSICAL JOURNAL LETTERS | 2018年 / 857卷 / 02期

基金：

美国国家科学基金会;

关键词：

planets and satellites: atmospheres; planets and satellites: individual (Mars); CRUSTAL MAGNETIC-FIELD; SOLAR-WIND INTERACTION; MARS; PHOTOELECTRONS; MODEL; MAVEN; IONOSPHERE; ANOMALIES; REGIONS; WAVES;

D O I：

10.3847/2041-8213/aabcc6

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Combining the Mars Atmosphere and Volatile Evolution measurements of neutral atmospheric density, solar EUV/X-ray flux, and differential photoelectron intensity made during 240 nominal orbits, we calculate the ionization efficiency, defined as the ratio of the secondary (photoelectron impact) ionization rate to the primary (photon impact) ionization rate, in the dayside Martian upper atmosphere under a range of solar illumination conditions. Both the CO2 and O ionization efficiencies tend to be constant from 160. km up to 250. km, with respective median values of 0.19 +/- 0.03 and 0.27 +/- 0.04. These values are useful for fast calculation of the ionization rate in the dayside Martian upper atmosphere, without the need to construct photoelectron transport models. No substantial diurnal and solar cycle variations can be identified, except for a marginal trend of reduced ionization efficiency approaching the terminator. These observations are favorably interpreted by a simple scenario with ionization efficiencies, as a first approximation, determined by a comparison between relevant cross sections. Our analysis further reveals a connection between regions with strong crustal magnetic fields and regions with high ionization efficiencies, which are likely indicative of more efficient vertical transport of photoelectrons near magnetic anomalies.

引用

页数：7

共 39 条

[1] Global distribution of crustal magnetization discovered by the Mars Global Surveyor MAG/ER experiment [J].

Acuña, MH ;

Connerney, JEP ;

Ness, NF ;

Lin, RP ;

Mitchell, D ;

Carlson, CW ;

McFadden, J ;

Anderson, KA ;

Rème, H ;

Mazelle, C ;

Vignes, D ;

Wasilewski, P ;

Cloutier, P .

SCIENCE, 1999, 284 (5415) :790-793

[2] Monte Carlo model of electron energy degradation in a CO2 atmosphere [J].

Bhardwaj, Anil ;

Jain, Sonal Kumar .

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2009, 114

[3] Electron pitch angle distributions as indicators of magnetic field topology near Mars [J].

Brain, D. A. ;

Lillis, R. J. ;

Mitchell, D. L. ;

Halekas, J. S. ;

Lin, R. P. .

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2007, 112 (A9)

[4] The Impact of Crustal Magnetic Fields on the Thermal Structure of the Martian Upper Atmosphere [J].

Cui, J. ;

Yelle, R. V. ;

Zhao, L. -L. ;

Stone, S. ;

Jiang, F. -Y. ;

Cao, Y. -T. ;

Yao, M. -J. ;

Koskinen, T. T. ;

Wei, Y. .

ASTROPHYSICAL JOURNAL LETTERS, 2018, 853 (02)

[5] Day-to-night transport in the Martian ionosphere: Implications from total electron content measurements [J].

Cui, J. ;

Galand, M. ;

Yelle, R. V. ;

Wei, Y. ;

Zhang, S. -J. .

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2015, 120 (03) :2333-2346

[6] Density waves in Titan's upper atmosphere [J].

Cui, J. ;

Yelle, R. V. ;

Li, T. ;

Snowden, D. S. ;

Mueller-Wodarg, I. C. F. .

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2014, 119 (01) :490-518

[7] Compositional effects in Titan's thermospheric gravity waves [J].

Cui, J. ;

Lian, Y. ;

Mueller-Wodarg, I. C. F. .

GEOPHYSICAL RESEARCH LETTERS, 2013, 40 (01) :43-47

[8] Suprathermal electron spectra in the Venus ionosphere [J].

Cui, J. ;

Galand, M. ;

Coates, A. J. ;

Zhang, T. L. ;

Mueller-Wodarg, I. C. F. .

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2011, 116

[9] Analysis of Titan's neutral upper atmosphere from Cassini Ion Neutral Mass Spectrometer measurements [J].

Cui, J. ;

Yelle, R. V. ;

Vuitton, V. ;

Waite, J. H., Jr. ;

Kasprzak, W. T. ;

Gell, D. A. ;

Niemann, H. B. ;

Mueller-Wodarg, I. C. F. ;

Borggren, N. ;

Fletcher, G. G. ;

Patrick, E. L. ;

Raaen, E. ;

Magee, B. A. .

ICARUS, 2009, 200 (02) :581-615

[10] Response of Mars O+ pickup ions to the 8 March 2015 ICME: Inferences from MAVEN data-based models [J].

Curry, S. M. ;

Luhmann, J. G. ;

Ma, Y. J. ;

Dong, C. F. ;

Brain, D. ;

Leblanc, F. ;

Modolo, R. ;

Dong, Y. ;

McFadden, J. ;

Halekas, J. ;

Connerney, J. ;

Espley, J. ;

Hara, T. ;

Harada, Y. ;

Lee, C. ;

Fang, X. ;

Jakosky, B. .

GEOPHYSICAL RESEARCH LETTERS, 2015, 42 (21) :9095-9102

← 1 2 3 4 →