During geomagnetically active times, the enhanced ion convection and particle precipitation at high latitudes cause substantial disturbances in the ionosphere and thermosphere. Large‐scale traveling ionospheric disturbances (LSTIDs) were identified from Global Positioning System (GPS) total electron content (TEC) measurements from 06:30 to 08:30 UT on 26 March 2014 as a result of southward turning of the interplanetary magnetic field (IMF) Bzand enhanced particle precipitation during a substorm. The comparison of LSTIDs from the global ionosphere‐thermosphere model (GITM) simulations with GPS TEC measurements shows a general agreement. Further theoretical analyses with GITM were conducted to sperate the influence of ion convection and particle precipitation on the total Joule heating as well as on the resulting large‐scale traveling atmospheric disturbances (LSTADs) and LSTIDs. It was found that ion convection and particle precipitation have comparable contributions to the total Joule heating, although the changes of height‐integrated Joule heating due to these two forcing terms may display different distributions. In addition, the magnitudes of neutral density and TEC perturbations due to these two forcing terms were found to be comparable. Using the total energy flux versus time derived from all‐sky imager measurements for this event to drive GITM improves the data‐model comparison of LSTIDs. However, data‐model discrepancies still exist in the timing of LSTIDs and the magnitude of TEC perturbations, which calls for further investigation and realistic event‐specific specifications.
Techniques developed in the past few years enable the derivation of high‐resolution regional ion convection and particle precipitation patterns from the Super Dual Auroral Radar Network (SuperDARN) and Time History of Events and Macroscale Interactions during Substorms All‐Sky Imager (ASI) observations, respectively. For the first time in this study, a global ionosphere‐thermosphere model (GITM) is driven by such high‐resolution patterns to simulate the I‐T response to the multi‐scale geomagnetic forcing during a real event. Specifically, GITM simulations have been conducted for the 26 March 2014 event with different ways to specify the high‐latitude forcing, including empirical models, high‐resolution SuperDARN convection patterns, and high‐resolution ASI particle precipitation maps. Multi‐scale ion convection forcing estimated from high‐resolution SuperDARN observations is found to have a very strong meso‐scale component. Multi‐scale convection forcing increases the regional Joule heating (integrated over the high‐resolution SuperDARN observation domain) by ∼30% on average, which is mostly contributed by the meso‐scale component. Meso‐scale electron precipitation derived from ASI measurements contributes on average about 30% to the total electron energy flux, and its impact on the I‐T system is comparable to the meso‐scale convection forcing estimated from SuperDARN observations. Both meso‐scale convection and precipitation forcing are found to enhance ionospheric and thermospheric disturbances with prominent structures and magnitudes of a few tens of meters per second in the horizontal neutral winds at 270 km and a few percent in the neutral density at 400 km through comparisons between simulations driven by the original and smoothed high‐resolution forcing patterns.
more » « less- PAR ID:
- 10443496
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Space Weather
- Volume:
- 20
- Issue:
- 12
- ISSN:
- 1542-7390
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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