Relationship between the observed and modeled modulation of the dayside ionospheric convection by the IMF By component

Abstract

The Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) electrodynamic model (IZMEM) provides global patterns of polar ionospheric potential and is parameterized by the interplanetary magnetic field (IMF). Given IMF conditions measured by an upstream satellite, the model yields a good global approximation to the polar ionospheric convection patterns assuming the proper time delay. While the model assumes static patterns and is based upon statistical regression analysis of high‐latitude magnetometer data, it can furnish an appropriate global context within which to examine time‐varying phenomena. We use the IZMEM model to further develop our understanding of the coordinated analysis of Greenland radar, riometer, and magnetometer data on August 2, 1991, which is one of the geospace environment modeling program intervals. The event is characterized by geomagnetic pulsations observed near local magnetic noon, having a 25‐min period and poleward phase propagation. A modulation of the intensity and orientation of the convection electric field is observed by the Sondrestrom incoherent scatter radar. Modeled global convection patterns show striking agreement with observations in the area covered by the radar field of view. We interpret observed phenomena as a direct ground‐based evidence of the IMF By component reconnection at the dayside magnetopause.