Assessment of ionospheric Joule heating by GUMICS-4 MHD simulation, AMIE, and satellite-based statistics: towards a synthesis
We investigate the Northern Hemisphere Joule heating from several observational and computational sources with the purpose of calibrating a previously identified functional dependence between solar wind parameters and ionospheric total energy consumption computed from a global magnetohydrodynamic...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2005-09-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/23/2051/2005/angeo-23-2051-2005.pdf |
| Summary: | We investigate the Northern Hemisphere Joule heating from several observational and computational sources with the purpose
of calibrating a previously identified functional dependence between solar wind parameters and ionospheric total energy consumption computed
from a global magnetohydrodynamic (MHD) simulation (Grand Unified Magnetosphere Ionosphere Coupling Simulation, GUMICS-4). In this paper,
the calibration focuses on determining the amount and temporal characteristics of Northern Hemisphere Joule heating. Joule heating during
a substorm is estimated from global observations, including electric fields provided by Super Dual Auroral Network (SuperDARN) and Pedersen
conductances given by the ultraviolet (UV) and X-ray imagers on board the Polar satellite. Furthermore, Joule heating is assessed from several
activity index proxies, large statistical surveys, assimilative data methods (AMIE), and the global MHD simulation GUMICS-4. We show that the
temporal and spatial variation of the Joule heating computed from the GUMICS-4 simulation is consistent with observational and statistical methods.
However, the different observational methods do not give a consistent estimate for the magnitude of the global Joule heating. We suggest that
multiplying the GUMICS-4 total Joule heating by a factor of 10 approximates the observed Joule heating reasonably well. The lesser amount of
Joule heating in GUMICS-4 is essentially caused by weaker Region 2 currents and polar cap potentials. We also show by theoretical arguments
that multiplying independent measurements of averaged electric fields and Pedersen conductances yields an overestimation of Joule heating.<br><br>
<b>Keywords.</b> Ionosphere (Auroral ionosphere; Modeling and
forecasting; Electric fields and currents) |
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| ISSN: | 0992-7689 1432-0576 |