The Pixelised Wavelet Filtering Method to Study Waves and Oscillations in Time Sequences of Solar Atmospheric Images

Abstract

Pixelised wavelet filtering (PWF) for the determination of the spatial, temporal, and phase structure of oscillation sources in temporal sequences of 2D images, based upon the continuous wavelet transform, has been designed and tested. The PWF method allows us to obtain information about the presence of propagating and nonpropagating waves in the data and localise them precisely in time and in space. The method is tested on the data sets obtained in microwaves with the Nobeyama Radioheliograph and in the EUV with TRACE. The method reveals fine spatial structuring of the sources of 3-, 5-, and 15-minute periodicities in the microwave and EUV emission generated in sunspot atmospheres. In addition, the PWF method provides us with unique information about the temporal variability of the power, amplitude, and phase narrowband maps of the observed oscillations and waves. The applicability of the method to the analysis of coronal wave phenomena is discussed.