Geomagnetic activity driven by solar wind turbulence

Abstract

Within the framework of the solar wind—magnetosphere coupled system, intense perturbations in the solar wind, causing geomagnetic storms and substorms, have been widely studied by means of the so-called coupling parameters. However, remarkable variations in the geomagnetic field occur even in absence of such perturbations. In those conditions, solar wind MHD turbulence might have a role. Recent results have shown that solar wind turbulence can be described not only as a mixture of inward and outward stochastic Alfvénic fluctuations, but includes also advected structures, dominated by an excess of magnetic energy. The present study focuses on the relationship between solar wind MHD turbulence and geomagnetic activity at high and low latitudes as measured by the AE and Dst indices, respectively. We performed this study as a function of the solar cycle and found that at solar minimum Alfvénic turbulence affects the high-latitude geomagnetic response.