The Effect of Subauroral Polarization Streams on Ionosphere and Thermosphere During the 2015 St. Patrick's Day Storm: Global Ionosphere‐Thermosphere Model Simulations

Abstract

Using the Millstone Hill incoherent scatter radar observations during 2015 St. Patrick's Day storm, subauroral polarization streams (SAPSs) have been specified in the nonhydrostatic Global Ionosphere‐Thermosphere Model simulations. The results reveal that the effect of SAPS on the coupled thermosphere‐ionosphere system includes the following: (1) Sudden frictional heating of SAPS results in acoustic‐gravity waves in the thermosphere. The vertical oscillation is localized, while the meridional disturbance propagates poleward and equatorward. (2) The SAPS‐associated horizontal wind field includes an enhanced westward wind within SAPS channel and a twin of vortex‐like winds north (clockwise) and south (anticlockwise) of subauroral latitudes. (3) Due to the neutral‐ion drag, ions in the vicinity of SAPS channel oscillate vertically with neutrals, resulting in a perturbation of ~0.3 TECu in ionospheric total electron content. The SAPS‐induced traveling atmospheric disturbances can elevate the plasma and increase the total electron content in midlatitude ionosphere. (4) It is confirmed that the Coriolis force can contribute to the poleward turning of the neutral wind during the post‐SAPS interval. In addition, the traveling atmospheric disturbance induced by the variation of auroral input and high‐latitude convection is possibly the primary cause of the poleward neutral wind surge during the magnetic storm on 17–18 March 2015. The combination of the two factors can make the northward meridional wind surge reach a magnitude of 100 m/s. This study improves our understanding of the SAPS's effect on neutral dynamics and ion‐neutral coupling processes during geomagnetically disturbed intervals.

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

“…TOI shown in the figure was observed off the magnetic pole, more close to the dusk cell when the IMF By became negative. Simulations by Guo et al (2018) have suggested that SAPS related thermospheric heating can possibly induce regional thermospheric and ionospheric disturbances taking the form of TIDs/AGWs as anticipated in . 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.…”

“…A secondary westward drift subsequently moved into the radar's field of view slightly after 00 UT on 8 September. SAPS can cause strong frictional heating (e.g., to both neutrals and ions and therefore can change the neutral density and composition in nearby regions (Guo et al, 2018;Wang et al, 2012). TOI shown in the figure was observed off the magnetic pole, more close to the dusk cell when the IMF By became negative.…”

“…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.…”

“…The presence of SAPS channels during the September event provided several potential impacts relevant to TID dynamics. Another alternative MSTID excitation process could come from local ion and neutral heating, as mentioned earlier, due to the presence of a strong SAPS electric field (Guo et al, 2018). SAPS can cause strong frictional heating (e.g., to both neutrals and ions and therefore can change the neutral density and composition in nearby regions (Guo et al, 2018;Wang et al, 2012).…”

Effects of Energetic Electron and Proton Precipitations on Thermospheric Nitric Oxide Cooling During Shock‐Led Interplanetary Coronal Mass Ejections

“…Particle precipitations during geo-effective events often initiate traveling ionospheric disturbances (TIDs). These TIDs have been observed in TEC observations (e.g., Hajkowicz, 1990;Pradipta et al, 2016) as well as GCM simulations, including GITM (Guo et al, 2018;Lin, Deng, Venkataramani, et al, 2018). These TIDs can travel away from the source region, such as the auroral zone.…”