SA004-0010
Investigation of Ionospheric Conductance and Joule Heating during Geomagnetic Storms using DMSP
Investigation of Ionospheric Conductance and Joule Heating during Geomagnetic Storms using DMSP
Tuesday, 8 December 2020
Poster
Abstract:
The electrical conductivity of the ionosphere is an essential parameter in characterizing the
electrodynamics of the coupling of the magnetosphere, ionosphere, and thermosphere
systems. In order to investigate the energy dissipation of electromagnetic energy in the
ionosphere and thermosphere during geomagnetic storms, we have created a conductivity
model which uses specified precipitating electron and ion spectra to calculate the Hall and
Pedersen conductivity along a single field line in the ionosphere. This allows us to calculate the
ionospheric conductance using observations by Defense Meteorological Satellite Program
(DMSP) spacecraft, which also measure the in situ electric and magnetic fields. This allows for a
comparison of Poynting flux and Joule heating. Using a database of 36 geomagnetic storms, we
investigate the storm-time conductivity and Joule heating. The conductivity model shows
agreement with the Global Airglow (GLOW) model, but also incorporates the effects of ions,
which are shown to be a significant driver of ionospheric conductivity during the storm main
phase. The full incorporation of the particle spectra can produce a substantially different
integrated conductance than the assumption of a Maxwellian distribution. At high energies,
precipitating ions are more efficient at producing Pedersen conductance than electrons, and
there are often regions where the electron energy flux is low but the ion energy flux is
significant. During storms, the enhanced convection and increased rate of substorm injections
leads to day/night and dawn/dusk asymmetries in the characteristic energy and energy flux of
precipitating ions and electrons, which drives asymmetries in the ionospheric conductance
dependent upon storm-time processes. Although the total Poynting flux over the high-latitudes
is nearly the same as our estimated Joule heating during the main phase of the storms, Joule
heating exceeds the Poynting flux in the aurora, and Poynting flux exceeds the Joule heating
over the polar cap.
electrodynamics of the coupling of the magnetosphere, ionosphere, and thermosphere
systems. In order to investigate the energy dissipation of electromagnetic energy in the
ionosphere and thermosphere during geomagnetic storms, we have created a conductivity
model which uses specified precipitating electron and ion spectra to calculate the Hall and
Pedersen conductivity along a single field line in the ionosphere. This allows us to calculate the
ionospheric conductance using observations by Defense Meteorological Satellite Program
(DMSP) spacecraft, which also measure the in situ electric and magnetic fields. This allows for a
comparison of Poynting flux and Joule heating. Using a database of 36 geomagnetic storms, we
investigate the storm-time conductivity and Joule heating. The conductivity model shows
agreement with the Global Airglow (GLOW) model, but also incorporates the effects of ions,
which are shown to be a significant driver of ionospheric conductivity during the storm main
phase. The full incorporation of the particle spectra can produce a substantially different
integrated conductance than the assumption of a Maxwellian distribution. At high energies,
precipitating ions are more efficient at producing Pedersen conductance than electrons, and
there are often regions where the electron energy flux is low but the ion energy flux is
significant. During storms, the enhanced convection and increased rate of substorm injections
leads to day/night and dawn/dusk asymmetries in the characteristic energy and energy flux of
precipitating ions and electrons, which drives asymmetries in the ionospheric conductance
dependent upon storm-time processes. Although the total Poynting flux over the high-latitudes
is nearly the same as our estimated Joule heating during the main phase of the storms, Joule
heating exceeds the Poynting flux in the aurora, and Poynting flux exceeds the Joule heating
over the polar cap.