PFISR observation of intense ion upflow fluxes associated with an SED during the 1 June 2013 geomagnetic storm

Abstract

The Earth's ionosphere plays an important role in supplying plasma into the magnetosphere through ion upflow/outflow, particularly during periods of strong solar wind driving. An intense ion upflow flux event during the 1 June 2013 storm has been studied using observations from multiple instruments. When the open‐closed field line boundary (OCB) moved into the Poker Flat incoherent scatter radar (PFISR) field of view, divergent ion fluxes were observed by PFISR with intense upflow fluxes reaching ~1.9 × 1014 m−2 s−1 at ~600 km altitude. Both ion and electron temperatures increased significantly within the ion upflow, and thus, this event has been classified as a type 2 upflow. We discuss factors contributing to the high electron density and intense ion upflow fluxes, including plasma temperature effect and preconditioning by storm‐enhanced density (SED). Our analysis shows that the significantly enhanced electron temperature due to soft electron precipitation in the cusp can reduce the dissociative recombination rate of molecular ions above ~400 km and contributed to the density increase. In addition, this intense ion upflow flux event is preconditioned by the lifted F region ionosphere due to northwestward convection flows in the SED plume. During this event, the OCB and cusp were detected by DMSP between 15 and 16 magnetic local times, unusually duskward. Results from a global magnetohydrodynamics simulation using the Space Weather Modeling Framework have been used to provide a global context for this event. This case study provides a more comprehensive mechanism for the generation of intense ion upflow fluxes observed in association with SEDs.

GPS Scintillations and Losses of Signal Lock at High Latitudes During the 2015 St. Patrick's Day Storm

“…The high flow velocity may cause strong ion‐frictional heating and enhanced ion temperature (e.g., St.‐Maurice & Hanson, ; Carlson, ; Bjoland et al, ). The enhanced ion temperature can cause rapid recombination of the ionosphere and depletion of the electron density (Rodger et al, ; Zou et al, ).…”

Ionospheric Electron Heating Associated With Pulsating Auroras: Joint Optical and PFISR Observations

“…In this scenario, the T e enhancement seen in the F region ionosphere is a remote effect, meaning that the low‐energy magnetospheric electrons do not actually penetrate to F region altitudes, so no significant ionization or red‐line auroral excitation is expected to accompany the heating there. However, the change of T e profile would affect the plasma density in the upper F region, for example, due to T e ‐dependent recombination rates of ions (e.g., Bekerat et al, ; David et al, ; Zhu et al, ; Zou et al, ). Also, when T e is sufficiently high the high‐energy tail in the thermal distribution of electrons may exceed the excitation threshold of O ( 1 D ) and cause some moderate 630 nm emissions (Solomon et al, ).…”

Effects of sudden commencement on the ionosphere: PFISR observations and global MHD simulation

“…Strangeway et al [2005] suggested that ion outflow usually occurs as a two-step process with ion upflow caused by increased ion (so-called Type 1 upflow) and/or increased electron (so-called Type 2 upflow) temperatures in the F region and topside ionosphere as the first step. Recently, enhanced F region and topside ionosphere density within the storm-enhanced density (SED) region [Foster et al, 2005;Zou et al, 2013Zou et al, , 2014 has been suggested to be a third mechanism of contributing large ion upflow fluxes [Semeter et al, 2003;Yuan et al, 2008;Zou et al, 2017]. The first two mechanisms described above arise from plasma temperature increase, while the third one associated with SED is due to increased plasma source population.…”

“…Such vertical drift and lifting of the F region ionosphere have been frequently observed within the SED[Zou et al, 2013[Zou et al, , 2014] although the convection flows are associated with different magnetospheric dynamic processes. These vertical drifts and F Geophysical Research Letters 10.1002/2017GL072678 region lifting have been suggested to play an important role in preconditioning intense ion upflow fluxes[Zou et al, 2017].…”