Strong sunward propagating flow bursts in the night sector during quiet solar wind conditions : SuperDARN and satellite observations

• Main Authors: C. Senior, J. C. Cerisier, F. Rich, Mark Lester, G. K. Parks
• Format: Other Non-Article Part of Journal/Newspaper
• Language: unknown
• Published: 2002
• Subjects: Uncategorized; Science & Technology; Physical Sciences; Astronomy & Astrophysics; Geosciences; Multidisciplinary; Meteorology & Atmospheric Sciences; Geology; ionosphere; auroral ionosphere; ionosphere-magnetosphere interactions; particle precipitation; INTERPLANETARY MAGNETIC-FIELD; HIGH-LATITUDE CONVECTION; RADAR OBSERVATIONS; PLASMA SHEET; BULK FLOWS; MAGNETOSPHERE; NORTHWARD; INTENSIFICATIONS; ASSOCIATION; Iceland
• Online Access: https://figshare.com/articles/journal_contribution/Strong_sunward_propagating_flow_bursts_in_the_night_sector_during_quiet_solar_wind_conditions_SuperDARN_and_satellite_observations/10164092

High-time resolution data from the two Iceland SuperDARN HF radars show very strong nightside convection activity during a prolonged period of low geomagnetic activity and northward interplanetary magnetic field (IMF). Flows bursts with velocities ranging from 0.8 to 1.7 km/s are observed to propagate in the sunward direction with phase velocities up to 1.5 km/s. These bursts occur over several hours of MLT in the 20:00–01:00 MLT sector, in the evening-side sunward convection. Data from a simultaneous DMSP pass and POLAR UVI images show a very contracted polar cap and extended regions of auroral particle precipitation from the magnetospheric boundaries. A DMSP pass over the Iceland-West field-of-view while one of these sporadic bursts of enhanced flow is observed, indicates that the flow bursts appear within the plasma sheet and at its outward edge, which excludes Kelvin-Helmholtz instabilities at the magnetopause boundary as the generation mechanism. In the nightside region, the precipitation is more spot-like and the convection organizes itself as clockwise U-shaped structures. We interpret these flow bursts as the convective transport following plasma injection events from the tail into the night-side ionosphere. We show that during this period, where the IMF clock angle is around 70°, the dayside magnetosphere is not completely closed.