At a Glance
- Researchers analyzed discrepancies between satellite observations and the IGRF-13 model of Earth’s magnetic field.
- Fluctuations in the magnetic field strength due to daily solar wind changes and solar storms significantly impact the accuracy of geomagnetic models.
- Differences in magnetic field vectors were concentrated in high-latitude auroral zones, with noticeable asymmetries between the northern and southern poles.
- Satellite orbit bias, especially around geographic poles, and unaccounted geophysical processes contribute to the model differences.
- The study’s findings are crucial for improving geomagnetic field models, satellite operation, and navigation systems, highlighting rapid polar magnetic field changes over the past decade.
A research team from the University of Michigan has comprehensively analyzed the Earth’s magnetic field, shedding light on the discrepancies between satellite observations and the 13th-generation International Geomagnetic Reference Field (IGRF-13) model. The study, published in the Journal of Geophysical Research: Space Physics, reveals that fluctuations in the strength of the Earth’s magnetic field, influenced by daily changes in solar wind structure and intermittent solar storms, can significantly impact the accuracy of geomagnetic field models. The team’s six-year analysis, spanning from 2014 to 2020, focused on differences during low to moderate geomagnetic conditions, which account for 98.1% of the observed period.
The study highlights the asymmetry between the north and south polar regions as a significant factor driving model differences. The researchers found that large magnetic field vector residuals between Swarm satellite observations and the IGRF-13 model were concentrated in the high-latitude auroral zone, with evident asymmetries in the magnetic longitude and magnetic local time distribution in both hemispheres. Notably, the polar satellite’s orbits create a sampling bias, resulting in a high concentration of measurements around the geographic poles, exacerbating the model differences. The team suggests that these asymmetries are not solely geophysical but are also influenced by satellite orbit bias and differences between the IGRF and observations due to modeling errors and geophysical processes are not accounted for in the model.
The findings have significant implications for satellite operation, mainly when using IGRF-13 as a reference, and for research on the physics of the Earth’s magnetosphere, ionosphere, and thermosphere. Understanding and identifying these biases is crucial for creating more accurate geomagnetic field models and improving satellite and aviation navigation systems. Additionally, the study underscores the rapid changes in the polar magnetic field over the past decade, adding further complexity to accurately modeling the Earth’s magnetic field.
References
- DeLacey, P. & University of Michigan College of Engineering. (2024, May 27). The Earth’s changing, irregular magnetic field is causing headaches for polar navigation. Phys.Org; University of Michigan. https://phys.org/news/2024-05-earth-irregular-magnetic-field-headaches.html
- Shi, Y., & Moldwin, M. B. (2024). Non-Geophysical Interhemispheric Asymmetries in Large Magnetic Field Residuals Between Swarm Observations and Earth Magnetic Field Models During Moderate to Quiet Geomagnetic Conditions. Journal of Geophysical Research: Space Physics, 129(5), e2023JA032092. https://doi.org/10.1029/2023JA032092
