A wavelet analysis of active region oscillations

The wavelet transform is applied to the analysis of active region oscillations. The localised (in time) nature of the wavelet transform allows us to study both the duration of any statistically significant oscillations as well as their period. Time series arising from SOHO (Solar and Heliospheric Observatory) CDS-NIS (Coronal Diagnostic Spectrometer Normal Incidence Spectrometer) active region observations on 14th-15th November 1996 are used to demonstrate the applicability of wavelet methods. High cadence (approximately 14 seconds) observations were made in {He I} 584.33 Ä (log T_e=4.3), {O V} 629.73 Ä (log T_e=5.3), {Mg IX} 368.06 Ä (log T_e=6.0), {Fe XVI} 360.76 Ä (log T_e=6.4) provide detailed intensity information on the active region over a wide range of temperatures. The distribution of statistically significant periods found varies from line to line, as does their duration.