A homogeneous aa index: 2. Hemispheric asymmetries and the equinoctial variationMike Lockwood, Ivan D. Finch, Aude Chambodut, Luke A. Barnard, Mathew J. Owens and Ellen ClarkeJ. Space Weather Space Clim., 8 (2018) A58DOI: https://doi.org/10.1051/swsc/2018044
