Direct observations of the full Dungey convection cycle in the polar ionosphere for southward interplanetary magnetic field conditions

Abstract

Tracking the formation and full evolution of polar cap ionization patches in the polar ionosphere, we directly observe the full Dungey convection cycle for southward interplanetary magnetic field (IMF) conditions. This enables us to study how the Dungey cycle influences the patches' evolution. The patches were initially segmented from the dayside storm enhanced density plume at the equatorward edge of the cusp, by the expansion and contraction of the polar cap boundary due to pulsed dayside magnetopause reconnection, as indicated by in situ Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations. Convection led to the patches entering the polar cap and being transported antisunward, while being continuously monitored by the globally distributed arrays of GPS receivers and Super Dual Auroral Radar Network radars. Changes in convection over time resulted in the patches following a range of trajectories, each of which differed somewhat from the classical twin‐cell convection streamlines. Pulsed nightside reconnection, occurring as part of the magnetospheric substorm cycle, modulated the exit of the patches from the polar cap, as confirmed by coordinated observations of the magnetometer at Tromsø and European Incoherent Scatter Tromsø UHF radar. After exiting the polar cap, the patches broke up into a number of plasma blobs and returned sunward in the auroral return flow of the dawn and/or dusk convection cell. The full circulation time was about 3 h.

The AUTUMNX magnetometer meridian chain in Québec, Canada

“…This is further backed up by yet stronger increases in B X and B Z at VLDR and STFL seen in With the developments in the eastward electrojet underway, a major rotation (note that | B | was constant) in the solar wind magnetic field arrived essentially at the time of the impulse observed on the ground. This seems a short delay for propagation of expected solar wind effects, for example through the Dungey cycle (Cowley 2000), (Zhang et al 2015), yet the low latitude seems to speak against more direct effects such as those possible near the cusp. The possible error in timing does support the idea that the rotation, in the form of a +Y change of 15 nT and -Z of about 10 nT, was causative.…”

“…The AUTUMNX secondary chain is close to this complementary meridian, and the main East Hudson Bay chain about one hour of magnetic local time west of it. Plasma transport across the polar cap links the day and night sides (Cowley 2000;Zhang et al 2015). Details of this, such as the link to substorms (Nishimura et al 2010) continue to be investigated.…”

The Behaviors of Ionospheric Scintillations Around Different Types of Nightside Auroral Boundaries Seen at the Chinese Yellow River Station, Svalbard

“…IMF is measured at the dayside, and the IMF takes time to influences the nightside auroral zone. The delay time is inversely proportional to the dayside reconnection rate (Zhang et al, 2015;Browett et al, 2017). On the nightside IMF delay depends on the solar wind velocity.…”

“…PMAFs are the poleward moving auroral forms and they cause severe degradation on the GNSS signals by causing scintillation and the loss of lock between satellite signal and the GNSS ground based receiver . Crowley et al (2000) and Zhang et al (2013aZhang et al ( , 2015 mentioned that nighttime aurora are occasionally due to the dayside high plasma density, which enters the nightside auroral oval and generate aurora thereafter, these high density plasma returns back to the dayside region. Inside the nightime auroral oval if the polarcap patches enters and produce aurora, the strongest scintillation is mostly found at the poleward edge of the nighttime auroral oval .…”

“…Further, recent research studies related to the auroral emission and the polar ionospheric (e.g., Crowley et al, 2000;Zhang et al, 2013aZhang et al, , 2015Jin et al, 2015Jin et al, , 2016Jin et al, , 2017Liu et al, 2015;Lyons et al, 2015;Oksavik et al, 2015;Prikryl et al, 2015;van der Meeren et al, 2015;Hosokawa et al, 2016;Baddeley et al, 2017;Chen et al, 2017 and many others) have covered many important aspects of magnetosphere-ionosphere-thermosphere coupling, such as nightside patch related aurora and poleward edge brightening of the nightside auroral oval; nightside auroral blobs and their associated scintillations; throat aurora as the precursor of PMAFs; equatorward driven auroral arcs due to the ULF waves and their energy dissipation caused due to joule/ion frictional heating etc. Still the long time duration (3-5 h) auroral emissions neither were studied nor characterized based on their boundary movement.…”