An empirical model of energetic electrons in Saturn’s magnetosphere based on Cassini data

Abstract

Based on one-hour average data observed by the MIMI/LEMMS instrument onboard the Cassini spacecraft from 2004 to 2017, we present an empirical model of energetic electrons (27 ​keV–1937 ​keV) in Saturn’s magnetosphere. This model distinguishes between two different regions. In the inner magnetosphere (<20RS, RS ​= ​60268 ​km is the radius of Saturn), this model is constructed based on L-shell and includes dayside-nightside asymmetry, which is caused by the interaction between solar wind and Saturn’s magnetosphere. This model is also adjusted for magnetodisk warping according to the seasonal variation of solar latitude. In the outer magnetosphere (>20RS), this model is constructed based on magnetodisk coordinates and represents the sheet-like structure at magnetotail. Gaussian distribution is used to fit the data along with the perpendicular distance to the warped magnetodisk. We also include a magnetopause model to filter the flux data. Finally, the results from this model are compared with those from SATRAD (SATurn RADiation model). Our new model based on Cassini data provides a picture of the energetic electron environment from 2.5 RS to 40 RS in Saturn’s magnetosphere.