Energy transfer and flow in the solar wind‐magnetosphere‐ionosphere system: A new coupling function

Abstract

In this paper we describe and quantify the energy transfer, flow, and distribution. Our high‐resolution data set covers 13 years of OMNI, SuperMAG, and Kyoto data. We employ what we consider to be the best estimates for energy sinks and relate these to SuperMAG indices for better coverage and spatial resolution. For the energy input, we have used the method of dimensional analysis that is presented in unit power and makes it appropriate for energy analysis. A cross‐correlation analysis parameterizes the magnetospheric response on the solar wind parameters during a wide range of conditions, ranging from substorms and storms up to a decade. The determined functional form is then evaluated and scaled using superposed epoch analysis of geomagnetic storms, revealing that the effective area of interaction cannot be considered static. Instead, we present a dynamic area which depends to the first order on the cube of the interplanetary magnetic field B z component. Also, we find that for longer time periods, this area must be increased compared to the area used for geomagnetic storms. We argue that some of the terms in the energy coupling function are contributory to describing magnetosheath conditions and discuss how our coupling function can be related to Maxwell stress components. Also, we quantify the relative importance of the different energy sinks during substorms, geomagnetic storms, and long time series and present the coupling efficiency of the solar wind. Our energy coupling functions are compared with the ε parameter and perform better for almost any event.