资源环境科技发展态势分析平台

Taking advantage of the high spatial‐resolution and global coverage of DMSP/SSUSI observations, we investigated the critical interplanetary factors in controlling the cusp auroral emission by dividing the midday auroras into the gap (weak emission) and non‐gap (intense emission) events. Although the cusp auroral intensity is essentially determined by a parameter related to the IMF direction, IMF magnitude (|B_y|), and solar wind speed (V), we found that the cusp aurora is statistically weak during the southward IMF but intense when the V and IMF |B_y| are greater. Further, we confirmed that even with V > 600km/s, the intense‐aurora event still shows a minimum occurrence near the IMF |B_y| = 0. However, when the IMF |B_y| is greater, the V becomes less significant for the intense‐aurora occurrence. These results demonstrate that the IMF |B_y| is critical in controlling the cusp auroral intensity, most likely by producing an electric field through .