Conjugate observations of quasi-periodic emissions by Cluster and DEMETER spacecraft

摘要: Quasi-periodic (QP) emissions are electromagnetic at frequencies of about 0.5-4 kHz that characterized by a periodic time modulation the wave intensity. Typical periods this on order minutes. We present case study large-scale long-lasting QP event observed simultaneously board DEMETER (Detection Electro-Magnetic Emissions Transmitted from Earthquake Regions) and Cluster spacecraft. The measurements Wide-Band Data instrument spacecraft enabled us to obtain high-resolution frequency-time spectrograms close equatorial region over large range radial distances, while STAFF-SA allowed perform detailed analysis. Conjugate observations have been used estimate spatial temporal extent emissions. analyzed lasted as long 5 h it spanned L-shells 1.5 5.5. Simultaneous same show intensity is very different locations in inner magnetosphere. ULF magnetic field fluctuations with period roughly comparable to, but somewhat larger than were detected fluxgate magnetometers near region, suggesting these likely be related generation. Results analysis propagate unducted, oblique normal angles higher geomagnetic latitudes.