Affiliation:
1. Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China
2. College of Earth and Planetary Sciences University of Chinese Academy of Sciences Beijing China
3. Beijing National Observatory of Space Environment Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China
4. CAS Key Laboratory of Geospace Environment School of Earth and Space Sciences University of Science and Technology of China Hefei China
Abstract
AbstractUsing the high spatial‐temporal resolution electron density profiles observed by the newly built Sanya Incoherent Scatter Radar at Sanya (18.3°N, 109.6°E) in its first 1‐month‐long continuous run with Barker code, we identified a substantial ionospheric pre‐sunrise uplift at low latitudes associated with the upward movement of ions. The uplift mainly occurs during local solar time 01:00–06:00 and is ∼52–240 km with significant night‐to‐night variability. With increasing geomagnetic and/or interplanetary activity, the uplift can have a larger amplitude. Further TIEGCM simulations show that the pre‐sunrise ionospheric uplift is jointly determined by the net effect of ambipolar diffusion, neutral wind, and E × B drift. The neutral wind during 00:00–05:00 usually lifts the ionosphere through equatorward wind. After 02:00, the weakening and/or even the reversal of downward E × B drift, which is not sufficient to offset the net uplift effect of wind and diffusion combination, triggers uplifting.
Publisher
American Geophysical Union (AGU)
Subject
Space and Planetary Science,Geophysics