Temperature background and perturbations after consecutively applying a temporal and a vertical butterworth filter. (a) shows the background overlaid by the ERA5 in purple, (b) shows the absolute temperature profile of the measurement (black) and ERA5 (violet). Panel (c) shows perturbations with a large vertical wavelength and relatively short period in the time-height diagram. (e) represents stationary waves with short vertical wavelengths like mountain waves (MWs) and (g) are the remaining perturbations with a small vertical wavelength and short period.