Subauroral Neutral Wind Driving and Its Feedback to SAPS During the 17 March 2013 Geomagnetic Storm

Abstract

Subauroral Polarization Streams (SAPS) are associated with closure of region 2 field-aligned current (R2 FAC) through the low conductivity region. Although SAPS have often been studied from a magnetosphere-ionosphere coupling perspective, recent observations suggest strong interaction also exists between SAPS and the thermosphere. Our study focuses on thermospheric wind driving and its impact on SAPS and R2 FAC during the 17 March 2013 geomagnetic storm using both observations and the physics-based Rice Convection Model-Coupled Thermosphere, Ionosphere, Plasmasphere, electrodynamics (RCM-CTIPe) model that self-consistently couples the magnetosphere-ionosphere-thermosphere system. Defense Meteorological Satellite Program (DMSP)-18 and Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite observations show that, as the storm progresses, sunward ion flows intensify and expand equatorward and are accompanied by strengthening of subauroral neutral winds with some delay. Our model successfully reproduces time evolution and overall structure of the sunward ion drift and neutral wind. A force term analysis is performed to investigate the momentum transfer to the neutrals from the ions. Contrary to previous studies showing that Coriolis force is the main driver of neutrals during storm time, we find that the ion drag is the largest force driving westward neutral wind in the SAPS region where the ion density is low in the trough region. Furthermore, simulations with and without the neutral wind dynamo effect are compared to quantify the effect of the neutral to plasma flow. The comparison shows that the self-consistent active ionosphere thermosphere coupling increases the R2 FAC and the westward ion drift equatorward of the SAPS region by 20% and 40% by the flywheel effect, respectively.

Temporal and Spatial Variations of Total Electron Content Enhancements During a Geomagnetic Storm on 27 and 28 September 2017

“…This time difference is almost consistent with our observational results. Ferdousi et al (2019) also showed that the electron density enhancement appeared in the daytime (10:00–16:00 MLT) midlatitude region (50–60° GMLAT) in the results of the physics‐based Rice Convection Model‐Coupled Thermosphere, Ionosphere, Plasmasphere, electrodynamics (RCM‐CTIPe) simulation. They interpreted the reason as a transportation of ionospheric plasmas to a higher altitude where the recombination rate is low by the equatorward neutral wind (e.g., Prölss, 1997).…”

“…Many previous studies on the response of the magnetosphere, ionosphere, and thermosphere associated with solar wind disturbances and geomagnetic storms using ground‐based and satellite observations and simulation have been conducted (e.g., Aa et al, 2019; Astafyeva et al, 2016; Blanc & Richmond, 1980; Bruinsma & Forbes, 2007; David et al, 2011; Ferdousi et al, 2019; Huang, 2008; Kikuchi et al, 1996, 2008; Liu, Wang, Burns, Yue, et al, 2016; Liu, Wang, Burns, Solomon, et al, 2016; Nishida, 1968; Sori et al, 2019; Tanaka, 1995; Tanaka et al, 2016). According to previous knowledge, when the southward IMF arrives at the magnetopause and the merging process between the IMF and geomagnetic field occurs at the dayside magnetopause, the solar wind energy effectively enters the magnetosphere and the intensity of FACs and high‐latitude convection is enhanced significantly.…”

“…Recently, Ferdousi et al (2019) reported that a significant enhancement of the equatorward natural wind occurred in the high‐ and middle‐latitude regions with several‐hour delay of an increase of the sunward SAPS flow associated with a geomagnetic storm that occurred on 17 March 2013 using DMSP‐18 and Gravity Field and Steady‐State Ocean Circulation Explorer (GOCE) satellite observations. This time difference is almost consistent with our observational results.…”

Subauroral and Polar Traveling Ionospheric Disturbances During the 7–9 September 2017 Storms

“…These magnetic latitude aligned velocities, with latitudinal width of a few degrees, formed a clear signature of a Space Weather 10.1029/2019SW002325 strong SAPS (Foster & Burke, 2002). Studies have found that SAPS can directly accelerate the background zonal wind via strong ion drag (e.g., Ferdousi et al, 2019;Wang et al, 2011;Zhang et al, 2015) and can indirectly change the meridional wind through the Coriolis force (Zhang et al, 2015). A large storm enhanced density (SED) plume was also observed during this time frame but emerged prior to the SAPS launch at Millstone Hill latitudes, with SED plume and Tongue of Ionization (TOI) structures persisting for a few hours (Figure 6).…”

“…These results suggest that SAPS-related strong westward ion drift might have induced the enhancement of LSSTID westward propagation components and may have even excited MSTIDs. They modified the TAD (AGW) associated with the LSSTID due to changing thermospheric winds (Ferdousi et al, 2019;Wang et al, 2011;Zhang et al, 2015), composition and temperature conditions (Guo et al, 2018;Wang et al, 2012) as a result of SAPS induced ion-neutral coupling. The presence of SAPS channels during the September event provided several potential impacts relevant to TID dynamics.…”