Asymmetric Structure of Uranus' Magnetopause Controlled by IMF and Planetary Rotation.

To investigate the diurnal variations of the magnetopause boundary under different Interplanetary Magnetic Field (IMF) orientations during the solstice season, we implemented a multifluid magnetohydrodynamic model of Uranus' magnetosphere in combination with Voyager 2 observations, which provided a good ability to simulate and predict the variability of the magnetospheric boundaries. In this study, we quantitatively studied Uranus' magnetopause in terms of the subsolar stand‐off distance and the flaring parameter and tracked the variation in cusp indentation, which are good indicators to describe the general topology of the boundary. During this season, the stand‐off distance fluctuated within a small range. In contrast, the flaring parameter and cusp indentation were strongly impacted by Uranus' rotation. Meanwhile, the IMF orientation also modulated the variation of the flaring parameter and cusp indentation. These results show that the asymmetry of the magnetopause is highly dependent on the rotation of Uranus and its IMF orientations. Plain Language Summary: The magnetopause of Uranus is the upstream boundary of Uranus' global magnetosphere and the solar wind, which has not sufficiently studied since there was only one fly‐by measurement by Voyager 2 spacecraft. To investigate the variation of magnetopause is important for us to deeply understand the magnetospheric dynamics of Uranus and can help us predict the space environment when future spacecrafts encounter Uranus. We utilized a multifluid magnetohydrodynamic model to study Uranus' magnetopause, based on the measurement by Voyager 2 mission. The results reveal that the boundary structure is highly asymmetric and dynamic and is mainly controlled by the planetary rotation and modulated by the Interplanetary Magnetic Field orientation. Key Points: The magnetopause of Uranus is very dynamic and asymmetric on a daily basisThe characteristics of the magnetopause stand‐off distance, flaring parameter, and cusp indentation are important to study the magnetopauseOur results indicate that the magnetopause morphology is mainly controlled by the planetary rotation and modulated by the IMF orientation [ABSTRACT FROM AUTHOR]