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The Earth’s magnetic field is dominated by the dipole moment, which magnetically connects the northern and southern hemispheres. Because ionospheric and magnetospheric plasmas preferentially move along magnetic field lines, local processes that affect the ionosphere or magnetosphere in one hemisphere can cause changes in the opposite hemisphere. The polar regions are uniquely valuable in geospace science, in part because much of the solar wind’s energy enters the system in polar regions and their magnetospheric, ionospheric, and atmospheric connections are markedly different from the lower latitudes. Geomagnetic conjugates are points in the northern and southern hemispheres linked by Earth’s magnetic field, including both points connected by closed magnetic field lines and points in open-field line regions that are in similar magnetic domains. Conjugate locations are both affected asymmetrically by external factors and have also been shown to alter each other’s environment on the order of minutes, which makes interhemispheric comparisons crucial to understanding the full dynamics of the geospace system. Here, we present conjugate_map, a Python library for flexible geomagnetic coordinate conversions that was designed to facilitate interhemispheric comparisons of geospace events and deployment of polar geospace instruments. As the fifth International Polar Year approaches in 2032–33, this work will help researchers to incorporate interhemispheric geospace investigations into the instrument planning process.
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This content will become publicly available on April 1, 2027
Universal Time Influence on Stormtime Magnetosphere Ionosphere Coupling
Abstract The offset between Earth's magnetic and rotational axes introduces a diurnal dependence in the high‐latitude EUV exposure of the northern hemisphere (NH) and southern hemisphere (SH). This variation raises the question: Does the Universal Time (UT) of geomagnetic storm onset impact its geospace consequences? To address this question, we used the Multiscale Atmosphere‐Geospace Environment (MAGE) model to simulate the 10 October 2024, geomagnetic storm—the year's second strongest (SYM‐H minimum of −346 nT). Since the storm occurred near equinox, we did not expect, but found, significant interhemispheric asymmetries in magnetosphere‐ionosphere‐thermosphere (M‐I‐T) coupling parameters such as the cross‐polar cap potential, hemispherically integrated field‐aligned current, and hemispheric power of electron precipitation. Controlled simulations show that interplanetary magnetic field (IMF) and solar wind have negligible effects on these asymmetries, whereas the EUV variation arising from the diurnal dipole tilt produces noticeable interhemispheric differences. Coincidentally, during this storm, IMFBzturned southward when the SH was tilted toward the Sun, and it maintained this orientation for 12 hr. A controlled simulation with storm onset shifted by 12 hr exhibits a substantial reduction in interhemispheric asymmetry. Differences in integrated Joule heating power and the SML/SMU indices also occurred with the shifted onset, underscoring the importance of UT in stormtime magnetosphere‐ionosphere coupling.
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- Award ID(s):
- 2347149
- PAR ID:
- 10688527
- Publisher / Repository:
- AGU
- Date Published:
- Journal Name:
- AGU Advances
- Volume:
- 7
- Issue:
- 2
- ISSN:
- 2576-604X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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