Ionospheric Joule heating, fast flow channels, and magnetic field line topology for IMF By‐dominant conditions: Observations and comparisons with predicted reconnection jet speeds

摘要: [1] When the interplanetary magnetic field (IMF) is dawnward or duskward, merging between IMF and geomagnetic occurs near cusp on dayside flanks of magnetosphere. While these periods are usually considered “quiet,” they can lead to intense localized energy deposition into ionosphere. We analyze two intervals during storm 24 August 2005: one with steady duskward IMF. Using outputs from Assimilative Mapping Ionospheric Electrodynamics (AMIE) data Defense Meteorological Satellite Program, we show that Joule heating exists fast ionospheric flow channels which lie open lines. In addition, lines have large components in sunward direction therefore resist bulk solar wind magnetosheath flow. compare observed velocities predicted reconnection jet speeds using parameters an MHD simulation. Results suggest corresponds portions populated by low-density plasma. The importance conductance determining also discussed.