Study of p-mode excitation and damping rate variations from IRIS⁺⁺ observations

¹ Laboratoire Universitaire d'Astrophysique de Nice, Université de Nice-Sophia Antipolis, 06108 Nice Cedex 2, France
² School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
³ Themis, Instituto de Astrofísica de Canarias, 38701, La Laguna, Tenerife, Spain
⁴ High Altitude Observatory, NCAR, PO Box 3000, Boulder, CO 80307, USA

Corresponding author: D. Salabert, david.salabert@unice.fr

Received: 31 March 2003
Accepted: 4 June 2003

Abstract

11 years of low degree helioseismic data collected by the IRIS⁺⁺ network (International Research of the Interior of the Sun) have been analyzed. The epoch covered (mid-1989 to end-1999) spans the maximum and the falling phase of solar cycle 22 and the rising phase of the current solar cycle 23. Annual timeseries with an overlap of 6 months are used to study the variations with solar activity of the p-mode frequencies , heights , and linewidths , taking into account the effects of the window function. These are used to infer variations in the velocity power and the energy supply rate which relate to changes in the excitation and the damping of the modes. We find global changes over the range 2600 Hz of about -26%, 11%, -11% for the heights, the linewidths, and the velocity power respectively, and a constant energy supply to the modes.