[PEM11-P16] Large-scale characteristics of pulsating aurora periodicities:multi-point high-speed optical observations in Scandinavia
Keywords:Pulsating aurora, Chorus wave, Main pulsation, Internal modulation
For this purpose, we have employed data from electron multiplying charge-coupled device (EMCCD) cameras deployed at multiple sites in Scandinavia to derive the large-scale characteristics of PsA. EMCCD cameras have been operative in Kevo and Sodankyla in Finland, Tromsoe in Norway, and Tjautjas in Sweden and their temporal resolution is 100 Hz. We conducted a frequency analysis for a PsA event on March 28, 2017 (23:30 to 24:10 UT). During the event studied, there existed three different regions of PsA, regions A, B and C, showing different modulation periods. It was also found that the boundaries between these three regions were sharp. We derived the 2D frequency map by using data from all the available stations. As a result, it became clear that the higher latitude region (region C) showed faster internal modulation than the lower latitude region (region A). In addition, region B, which was sandwiched by regions A and C, did not show any internal modulations (i.e., main pulsation without internal modulation). In the presentation, we discuss why the three regions showed different modulation periods with sharp boundaries. In particular, we address what ambient conditions can control the absence of internal modulation in region B. We also derived similar frequency maps of chorus waves by tracing the PsA modulation with the Tsyganenko 04 magnetic field model, which could be used to estimate the spatial extent of chorus wave generation region.