ORIGINAL RESEARCH article
Front. Astron. Space Sci.
Sec. Space Physics
Volume 12 - 2025 | doi: 10.3389/fspas.2025.1601296
This article is part of the Research TopicVariability in the Solar Wind and its Impact on the Coupled Magnetosphere-Ionosphere-Thermosphere SystemView all 13 articles
Characterization of F-Region Neutral Wind Response Times and Its Controlling Factors During Substorms
Provisionally accepted
- 1University of Alabama in Huntsville, Huntsville, United States
- 2Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, United States
- 3SRI International, Menlo Park, California, United States
- 4University of Alaska Fairbanks, Fairbanks, Alaska, United States
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Ion-neutral coupling is responsible for dissipating energy deposited into the high-latitude ionosphere during geomagnetically active periods. The neutral wind response time, or the ion-neutral coupling efficiency, is not well characterized, with a wide range of reported response times. Additionally, how this coupling efficiency varies with geomagnetic activity level is not well understood, with few studies addressing the impact of geomagnetic activity level on neutral wind response time. In this study, a statistical analysis of the neutral wind response time during substorm periods is performed. We use data from Scanning Doppler Imagers (SDIs) and the Poker Flat Incoherent Scatter Radar (PFISR) to calculate the neutral wind response time using the new weighted windowed time-lagged correlation method. Substorm events were found using SuperMAG substorm lists and All Sky Imagers (ASIs). This statistical analysis resulted in 23 substorm events, with an average response time of ∼16 minutes. To determine the controlling factors of this response time, geomagnetic and ionospheric parameters, such as IMF strength and orientation, SYM/H index, AE index, and electron density, are investigated for the statistical substorm set. A superposed epoch analysis of the parameters is performed to determine average geospace conditions required for fast neutral wind responses. It was found that quiet-time conditions in AE and SYM-H indices, a southward turning of IMF around 1.5 hr before substorm onset time, and large electron densities lead to faster neutral wind response times. Based on the geomagnetic indices results, it was suggested that thermospheric pre-conditioning may play a role in neutral wind response times.
Keywords: Ionosphere, thermosphere, Space weather, systems coupling, substorm
Received: 27 Mar 2025; Accepted: 24 Apr 2025.
Copyright: © 2025 Davidson, Zou, Lamarche, Bhatt and Conde. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Katherine Davidson, University of Alabama in Huntsville, Huntsville, United States
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