Efficiency of Electromagnetic Energy Transfer from Solar Wind to Ionosphere through Magnetospheric Ultra-Low Frequency Waves

whawkins — Wed, 13 Aug 2025 20:10:55 +0000

Efficiency of Electromagnetic Energy Transfer from Solar Wind to Ionosphere through Magnetospheric Ultra-Low Frequency Waves whawkins Wed, 08/13/2025 - 14:10

Author:

whawkins

Aug 13, 2025

(a) 5-200 s bandpassed $S_{A//}$ mapped to the ionospheric altitude and averaged over the four-hour interval. (b) 5-200s bandpassed $S_{A//}$ in the 7 MLT plane. (c) 4.5-5.5 mHz root-integrated power (RIP) of radial electric field $E_r$ in the equatorial plane. (d) 4.5-5.5 mHz RIP of azimuthal magnetic field $B_\phi$ in the meridional plane of 7 MLT. (e-f) Field-aligned keograms of $E_{mrd}$ and $B_\phi$ along the green field line with the largest $S_{A//}$. The green curve in (b) and (d) is a magnetic field line in the 7 MLT plane connecting to the green cross in (a) which marks the location with the peak $S_{A//}$. This field line crosses the equatorial plane at the green cross in (c).

Geophysical Research Letter: Scientists have long been interested in how energy from the Sun is transferred into Earth’s space environment. The Earth's magnetosphere is an important intermediate environment between the solar wind and the upper atmosphere. Consisting of plasma and magnetic field, the magnetosphere is full of intrinsic plasma waves that are capable of energy transport, particularly a group in the frequency range of a few to a few tens Millihertz that are especially efficient in connecting the magnetosphere and the ionosphere. However, due to the global presence and propagation features of those waves, it has been very challenging with measurements from a limited number of locations to understand the efficiency of the wave based energy transfer mechanism. This study uses a first-principles computational model that can resolve the fundamental physics related to the low frequency plasma waves, to carry out idealized numerical experiments to investigate the electromagnetic energy flow in response to undulating solar wind. The theoretical study provides new understanding of the significance of the electromagnetic energy flow and its dependence on different parameters.

Penetrating electric field with/without disturbed electric fields During the 7-8 July 2022 geomagnetic storm simulated by MAGE and observed by ICON MIGHTI

whawkins — Wed, 09 Apr 2025 21:17:49 +0000

Penetrating electric field with/without disturbed electric fields During the 7-8 July 2022 geomagnetic storm simulated by MAGE and observed by ICON MIGHTI whawkins Wed, 04/09/2025 - 15:17

Author:

whawkins

Apr 9, 2025

7 July, MAGE simulation and ICON observation of zonal thermospheric winds and ion drifts. ICON MIGHTI observed zonal wind and MAGE simulations along the MIGHTI sampling points (right) are plotted. Data from each orbit are plotted according to the longitude. The starting time for each orbit is provided. The midnight is marked by blue triangles. MIGHTI data gaps are due to SAA (South Atlantic Anomaly) or day-night transitions (see Englert et al., 2023). The IMF Bz southward turning occurred after 12 UT, which is highlighted by a dashed oval. The nightside zonal wind start to see reaction in the next orbit. Not much change is seen on the dayside. The ExB meridional ion drifts (vertical upward at the magnetic equator) for each orbit are plotted on the right.

JGR Space Physics: Using a numerical model where the coupled physical processes of the magnetosphere, ionosphere, and thermosphere are represented, we simulated the nighttime ionospheric disturbances caused by electric fields that enter this system from the magnetosphere and electric fields generated internally by changes in the thermospheric winds. The former is quick to reach the low latitudes, and the latter is delayed by the slower response of the neutral winds. The coupled model and NASA satellite observation showed good agreement. The results show good capability and lend themselves to the future effort to forecasting space weather at low latitudes.

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Efficiency of Electromagnetic Energy Transfer from Solar Wind to Ionosphere through Magnetospheric Ultra-Low Frequency Waves

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