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Magnetotail Boundary Crossings at Lunar Distances: ARTEMIS ObservationsWe compare results from a preliminary analysis of two years of ARTEMIS magnetopause boundary crossings at lunar distances with available empirical models. We remove the effects of variable solar wind flow directions and aberration angles to study the magnetotail cross-section as a function of solar wind conditions. The average magnetopause distance from the central axis is 26 RE, but this distance ranges from 10 RE for high solar wind dynamic pressures and strong northward IMF orientations to 39 RE for low solar wind dynamic pressures and weak southward IMF orientations compared to the nominal solar wind conditions. The time-independent Howe and Binsack (1972) model describes the average location of the crossings very well. For high solar wind dynamic pressures, the Lu et al., (2011) model performs best, while for low pressures the Petrinec and Russell (1996) model gives the closest prediction. As predicted by theory and seen in past studies, the magnetotail cross-section is suggestive of prolate during intervals of strong IMF By, but oblate during intervals of strong IMF Bz. Any asymmetric variation of the tail boundary with respect to the sign of IMF By was not observed. The decreasing size of boundary with the increasing dynamic pressure was found when dynamic pressures are smaller than 2nPa. Although the scatter is larger, the tail size for pressures larger than 2nPa suggests a constant radius. The tail boundary size decreases as the strength of IMF Bz increases regardless of its polarity. However, it was also observed that an even stronger southward IMF Bz can cause larger magnetopause size in the presence of large dynamic pressures.
Document ID
20190001669
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Akay, Iklim Gencturk
(Istanbul Technical Univ. Istanbul, Turkey)
Kaymaz, Zerefsan
(Istanbul Technical Univ. Istanbul, Turkey)
Sibeck, David G.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
March 20, 2019
Publication Date
November 3, 2018
Publication Information
Publication: Journal of Atmospheric and Solar-Terrestrial Physics
Publisher: Elsevier
Volume: 182
ISSN: 1364-6826
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
GSFC-E-DAA-TN65902
Funding Number(s)
WBS: WBS 960804.01.01.01
Distribution Limits
Public
Copyright
Other
Keywords
Magnetotail
IMF bz
Magnetopause
Dynamic pressure
Non-radial flows

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