On the measurement bias of low-ℓ solar p-mode excitation parameters: The impact of a ground-based window function

We present a study of the impact of a ground-based, multi-station window function on estimates of the power and damping of low-l solar p modes extracted from fits to resonant structure in the frequency domain. The window functions come from six-site observations made by the Birmingham Solar-Oscillations Network (BiSON) over the 10-yr period beginning 1991 January. Two strategies were adopted. In the first, we used an 800-d time series of continuous observations made by the GOLF instrument on board the ESA/NASA SOHO satellite. These data were modulated by a variety of BISON window functions, with fractional duty cycles ranging from ∼0.4 to ∼0.8, and the resulting series analyzed. In the second we generated artificial 10-yr time series and studied the effect on these of the complete BISON window.