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JGR Space Physics - 2022 - Milan - Influence of Off‐Sun‐Earth Line Distance on the Accuracy of L1 Solar Wind Monitoring.pdf (991.53 kB)

Influence of Off‐Sun‐Earth Line Distance on the Accuracy of L1 Solar Wind Monitoring

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posted on 2022-07-08, 15:22 authored by SE Milan, JA Carter, GE Bower, AL Fleetham, BJ Anderson

 Upstream solar wind measurements from near the L1 Lagrangian point are commonly used to investigate solar wind-magnetosphere coupling. The off-Sun-Earth line distance of such solar wind monitors can be large, up to 100 RE. We investigate how the correlation between measurements of the interplanetary magnetic field and associated ionospheric responses deteriorates as the off-Sun-Earth line distance increases. Specifically, we use the magnitude and polarity of the dayside region 0 field-aligned currents (R0 FACs) as a measure of interplanetary magnetic field (IMF) BY-associated magnetic tension effects on newly-reconnected field lines, related to the Svalgaard-Mansurov effect. The R0 FACs are derived from Advanced Magnetosphere and Planetary Electrodynamics Response Experiment measurements by a principal component analysis, for the years 2010–2016. We perform cross-correlation analyses between time-series of IMF BY, measured by the Wind spacecraft and propagated to the nose of the bow shock by the OMNI technique, and these R0 FAC measurements. Typically, in the summer hemisphere, cross-correlation coefficients between 0.6 and 0.9 are found. However, there is a reduction of order 0.1–0.15 in correlation coefficient between periods when Wind is close to (within 45 RE) and distant from (beyond 70 RE) the Sun-Earth line. We find a time-lag of around 17 min between predictions of the arrival of IMF features at the bow shock and their effect in the ionosphere, irrespective of the location of Wind. 

Funding

SEM and JAC were supported by the Science and Technology Facilities Council (STFC), UK, grant no. ST/S000429/1; GEB and ALF were supported by STFC studentships. The work at the Birkeland Centre for Space Centre, University of Bergen, Norway, was supported by the Research Council of Norway/CoE under contract 223252/F50.

History

Citation

Milan, S. E., Carter, J. A., Bower, G. E., Fleetham, A. L., & Anderson, B.J. (2022). Influence of off-Sun-Earth line distance on the accuracy of L1 solar wind monitoring. Journal of Geophysical Research: Space Physics, 127, e2021JA030212. https://doi.org/10.1029/2021JA030212

Author affiliation

Department of Physics and Astronomy

Version

  • VoR (Version of Record)

Published in

Journal of Geophysical Research: Space Physics

Volume

127

Issue

6

Pagination

e2021JA030212

Publisher

American Geophysical Union (AGU)

issn

2169-9380

eissn

2169-9402

Acceptance date

2022-05-19

Copyright date

2022

Available date

2022-07-08

Language

en

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