Abstract
<title>Abstract</title> <p>Auroral emissions modulated at geomagnetic pulsation periods signal magnetospheric wave–particle interactions, yet how pulsations synchronize chorus waves, electron scattering, precipitation, and aurora has not been fully understood. Here we analyze a well-conjugated event observed by the Arase satellite, the EISCAT radar, and auroral imaging, combining high-time-, energy-, and pitch-angle-resolution satellite measurements with high-energy-resolution ionospheric precipitation measurements. These observations reveal synchronization among chorus waves, electron pitch-angle scattering, precipitating electron fluxes, and diffuse aurora at the pulsation period, linking chorus-driven scattering to periodic precipitation. We further suggest that geomagnetic pulsations regulate chorus waves not only by modulating source electrons but also by facilitating chorus-wave propagation. The westward propagation of the modulated diffuse aurora was consistent with that of the geomagnetic pulsations, indicating that the spatial propagation of precipitation reflected the geomagnetic pulsation structure. These results show that geomagnetic pulsations can organize chorus-driven precipitation in both time and space, revealing multiscale magnetosphere–ionosphere coupling.</p>