Abstract We quantify the asymmetry between the Birkeland currents (also known as field‐aligned currents) in the Northern and Southern Hemispheres. We use data from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) in 2010–2024 inclusive for both hemispheres, compute the observed asymmetry, and then subtract the modeled asymmetry. We use Block 1 data (based on the original Iridium constellation) and NEXT data (based on Iridium‐NEXT spacecraft), and compare the effect of changing the data processing pipeline on the latter (yielding NEXT v1 and NEXT v2 subdatasets). We find that the asymmetry is significantly smaller in NEXT v2 data than in Block 1 or NEXT v1 data . The previously reported asymmetry seen in Swarm is , indicating that the new data processing pipeline goes from approximately twice the Swarm asymmetry to approximately half. This may indicate that the new AMPERE processing pipeline overestimates the amount of current flowing in the Southern Hemisphere, whereas the old one underestimated this quantity. We use frequency analysis to find that the asymmetry varies with frequencies corresponding to seasonal effects, CME occurrence, Iridium constellation orbit precession, and geomagnetic storms. We find a correlation with IMF , indicating that more current flows in the Northern Hemisphere during positive and vice versa. We find that Block 1 data in 2010–2017 shows correlations with AL, AU, , PCN, and PCS index which indicate that the asymmetry is less pronounced when Dungey Cycle convection is stronger, but NEXT data in 2019–2024 do not show this.
Coxon et al. (Fri,) studied this question.