Latitudinal and Longitudinal Variations of Pulsating Aurora Periodicities: Digital Camera Observations from International Space Station

Various ground-based and space-based imagers have enable us to capture the dynamical characteristics of aurorae. However, it still remains difficult to observe their fine-scale structures in a wide area with a reasonable temporal resolution. For example, the THEMIS All-Sky Imagers (ASI) network succeeded in capturing aurora in a wide area. But, since the temporal resolution of the ASIs is 3 seconds, they are not good at observing rapidly varying aurorae such as pulsating aurora (PsA). In addition, since ground-based observations are affected by the weather, it is rare to be able to observe auroras at all the stations. Space-based ultraviolet imagers such as ones onboard the IMAGE and DMSP satellites can observe the large-scale structure, but it is, in turn, difficult to observe their fine structures, as they do not have sufficient temporal resolutions.

The photographs taken with a digital single-lens reflex cameras from the International Space Station (ISS) have sensible spatial and temporal resolutions and a wide field-of-view that can overcome the limitation mentioned above. With the remarkable development of digital imaging technology, it is possible to capture aurorae from the ISS with a temporal resolution less than 1 second. Besides, the high spatial resolution, that is one of the big advantages of digital camera images, enables us to distinguish the spatial structure of aurora within 1 km. At the JpGU meeting, we presented methods for mapping the images. By showing that we confirmed that the accuracy of mapping is sufficient for studies of PsA. In this presentation, we will present several case studies to show the spatial distribution of the PsA periodicities in a wide area. We will compare the tendency of the period to be longer at the high latitude suggested in the previous research, and discuss what factor controls the longitudinal variations of PsA based on the wide area visualization of their periodicities.