A wavelet analysis of quasi-periodic variability across a solar coronal hole region

Centre for Astrophysics, University of Central Lancashire, Preston, PR1 2HE, UK

Corresponding author: M. S. Marsh, mmarsh@uclan.ac.uk

Received: 3 May 2002
Accepted: 18 July 2002

Abstract

High time resolution (≈13 s cadence) Solar and Heliospheric Observatory (SOHO) Coronal Diagnostic Spectrometer (CDS) Grazing Incidence Spectrometer (GIS) time series data is analysed for evidence of quasi-periodic variability in the solar corona. The observations are obtained from a GIS study of a coronal hole boundary region taken in October 1997. A wavelet analysis is applied to EUV emission lines covering a temperature range of 5.3–6.1 K. Wavelet analysis allows the frequency and temporal information of any periods present within the data to be analysed. Statistically significant periods are found within the range 100–900 s and 1500 s. Observations of short wavepackets with periods of the order 50–100 s with durations of 2–5 cycles are reported. Observations of a decay in the driving period over time are also described.