Phys.org May 27, 2024
Researchers at the University of Michigan statistically studied large magnetic field vector residuals between Swarm observations and the 13th generation International Geomagnetic Reference Field (IGRF-13) model under quiet to moderate geomagnetic conditions. All large residuals appeared in the high latitude auroral zone region peaking around 70° magnetic latitude (MLAT) with a secondary occurrence peak just below 80° MLAT. However, the two hemispheres showed clear asymmetries in the magnetic longitude and magnetic local time distribution where both hemispheres showed high concentration of large residuals around the geographic poles. Since polar satellite’s orbits give rise to highly biased number of observations around the geographic poles, they suggested that the asymmetries of large residuals in the two hemispheres around the geographic pole were not geophysical, but due to satellite orbit bias around the geographic poles and difference between IGRF and observations due to model error and geophysical processes not included in the model. Identifying these biases was helpful to better separate out geophysical electric current signatures from non-geophysical ones… read more. Open Access TECHNICAL ARTICLEÂ
Maps of large residuals in geomagnetic coordinates. Credit: JGR Space Physics, 06 May 2024