资源环境科技发展态势分析平台

In this letter, the statistical characteristics of the structures of giant undulations (GUs) during geomagnetic storms are studied for the first time, based on aurora images during 2005-2019. The GUs mainly occur within ∼4 hours following the beginning of the storm main phase and finish in ±4 hours around the storm peak. The most interesting feature is that the antisunward edge of GUs is quasi-stable (18-19 h MLT) during their lifetime. The latitudinal amplitudes of GUs (A_GU) peak at 200-300 km while the azimuthal wavelengths (W_GU) occupy several discrete values between 100 and 900 km. Both A_GU and W_GU are quasi-proportional to the strength of the storms, and A_GU is also proportional to W_GU. There are some differences in the characteristics of A_GU and W_GU between pre-dusk and post-dusk sectors. These results would provide both statistical insight for mechanisms of dynamic auroral structures and data sources for validating magnetosphere-plasmasphere-ionosphere coupling models.