On meso-scale coupling between ionospheric Joule heating and electrojet activity

Kauristie, K.1, Amm, O.1, Aikio, A.2, Juusola, L.1, Sillanpää, I.1 and Vanhamäki, H.1

1 Finnish Meteorological Institute, Helsinki, Finland
2 Department of Physical Sciences, University of Oulu, Oulu, Finland

With a data set of ~17 hours of EISCAT-based estimates of ionospheric conductances and MIRACLE observations of equivalent currents and electric field we investigate the relationship between ionospheric currents and Joule heating. The events selected for the analysis are roughly homogeneous in the longitudinal direction and thus can be studied with the 1-dimensional method of characteristics and with data collected along the central meridian of our instrumentation. The alpha-parameter (Hall to Pedersen conductance ratio) which the method needs as an input is derived from EISCAT data. Hall conductance estimates fix the boundary conditions of the differential equations that the method solves. The latitudinal variations of alpha can be estimated with recently published empirical formulas linking this parameter with equivalent current intensities. Our analysis will yield new information about the relationship between ionospheric currents (or ground-based magnetic activity) and energy dissipation in meso-scale phenomena. These results will be discussed in the context of previously published formulas suggesting simple linear relationship between the global energy dissipation and the AE-index.