A new approach to magnetopause and bow shock modeling based on automated region identification

The present empirical models describing a location and shape of the magnetopause and bow shock are based on a statistical evaluation of magnetopause and bow shock crossings. The crossings are usually identified by a visual inspection of the plots or by automatic methods which are less reliable. We present a new method of determination of the most probable boundary locations. The method is based on continuous plasma and magnetic field measurements in the regions visited by a sounding spacecraft (the solar wind, magnetosheath, and magnetosphere) and on the determination of ratios of these parameters to simultaneously monitored upstream parameters. The regions identified by this method are then used for development of simple models of the magnetopause and bow shock locations parameterized by the upstream pressure. The performance of the models is tested with corresponding boundary crossings based mainly on the THEMIS observations. Both developed models are in a good agreement with the results obtained from identification of crossings.