(a): Relative intensity variations averaged along a set of LOS rays as shown in Fig. 9, as a function of time, obtained numerically simulated by lare2d for an oscillation beginning at 11:19 UT. (b): Relative intensity averaged over the transverse coordinate as a function of time, taken from the same region, as a function of time. The dashed line is a smooth slow trend fitted using a Savitzky-Golay filter (Savitzky & Golay 1964). (c): Relative intensity as a function of time found after subtracting the slow trend. The dashed line is a damped sinusoidal fit. (d) Relative intensity as a function of time found after subtracting the slow trend from a time series where the relative intensity in panel a has been averaged only over the transverse interval for x between −228 and −185 Mm in the numerical domain. The dashed line is a damped sinusoidal fit.