A statistical study: Relations Between the Directional Changes in Solar Wind Flow and Magnetotail Response

We explore relationship between the interplanetary magnetic field configuration and the direction of the solar wind flow analyzing few substorm onset lists, produced by different methods over the few years.  We investigate the impact of upstream conditions, such as the interplanetary magnetic field (IMF) configuration and  the changing direction of the solar wind flow on the occurrence of substorms by using substorm onset lists between time1-time2. Large directional changes in the solar wind flow can result in large-scale windsock motions and current sheet thinnings forcing magnetic reconnection to occur in magnetospheric tail, which consequently can lead to substorm onset. Magnetic reconnection is a process, which can explain fast and energetic releases of plasmas in the tail during southward oriented IMF, leading to energetic substorms. However, it is more difficult to explain substorms which are associated with northward oriented IMF. Here we aim to analyse substorms associated with northward oriented IMF with the additional challenge to understand whether the substorm onsets are externally triggered by some upstream conditions or internally initiated by some instabilities in the magnetotail, observed for example during northward oriented interplanetary magnetic field i.e. in the time when there is no significant flux transfer. For our analysis we use concurrent OMNI data of solar wind, substorm databases, Geotail, THEMIS satellite data and ground base data.