EGU21-12045, updated on 04 Jan 2024
https://doi.org/10.5194/egusphere-egu21-12045
EGU General Assembly 2021
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Dayside ionospheric electrodynamics in association with high-latitude dayside aurora (HiLDA)

Lei Cai1, Anita Kullen1, Tomas Karlson1, Andris Vaivads1, and Yongliang Zhang2
Lei Cai et al.
  • 1KTH Royal Institute of Technology, Space and Plasma Physics, Stockholm, Sweden
  • 2The Johns Hopkins University Applied Physics Laboratory, USA

The Defense Meteorological Satellite Program (DMSP) Special Sensor Ultraviolet Spectrographic Imager (SSUSI) has observed the large-scale high-latitude dayside aurora (HiLDA) during its long lifetime of hours. HiLDA has dynamical changes in form, size, location, and development of fine structures. However, the associated electrodynamics is not fully understood. In general, HiLDA occurs in the dayside polar cap during IMF By+ (By-) prevailing conditions in the sunlit northern (southern) hemisphere.  The prevailing conditions drive strong upward field-aligned current in the polar cap. Within the upward field-aligned current region, the field-aligned potential drop can be set up and accelerate the electrons, forming the monoenergetic electron precipitation (up to 10s keV) and producing HiLDA.

 

This study investigates the ionospheric flows, currents, and auroral precipitation in association with HiLDA, benified from the simultaneous measurements from the DMSP satellites, the AMPERE project, and ground-based magnetometers and SuperDARN coherent radars. We will show HiLDA interacts with duskside oval-aligned arcs or transpolar arcs. The interactions are associated with the cusp and the dayside reconnection at the duskside flank/high latitudes. The reconnection produces strong dusk-dawn convection with flow shears in the polar cap, which generates the upward Region 0 current. We find that HiLDA is formed in the high-latitude part of the upward Region 0 current. We apply the Knight relation and identify the lobe electrons (< 0.3 cm-3) as the source of HiLDA. The fine structures revealed in the emission intensity of HiLDA may suggest the uneven distribution of the electron density in the high-latitude lobe.

How to cite: Cai, L., Kullen, A., Karlson, T., Vaivads, A., and Zhang, Y.: Dayside ionospheric electrodynamics in association with high-latitude dayside aurora (HiLDA), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12045, https://doi.org/10.5194/egusphere-egu21-12045, 2021.

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