Hiss emitting auroral activity.

Real-time auroral records on a video tape obtained by use of a highly sensitive TV camera, and simultaneous records of VLF waves on the sound track of the same video tape were analyzed and specific small scale auroral activities were found to be associated with specific burst-like hiss enhancements with durations of 0.1-1 s. The hiss emitting auroral activities were identified by cross correlation analysis between the temporal variations in luminosity of auroral structures and the temporal variations of hiss intensities. The hiss emitting aurora were long-rayed sheet fragments or folds of a few km to several tens of km in horizontal scale which rapidly changes in luminosity, and displayed rapid motions such as splittings and rotations. The enhancements of local auroral electron precipitations responsible for the local auroral activity and of hiss emissions are concluded to be simultaneous within a time accuracy of 200 ms at worst and within a few tens of ms at best.