Variability of the parameters derived from broadband spectral modelling of Swift and HST COS data of NGC 5548 in Sect. 3. The X-ray hardness ratio R and the UVW2 flux are also displayed on the top two panels for comparison. On the vertical axis of each panel the name of the corresponding parameter is given. The normalisation of the warm Comptonisation (comt) component (modelling the optical/UV continuum and the soft X-ray excess) is shown in units of 10⁵⁶ photons s^-1 keV^-1. The power-law (pow) normalisation is in 10⁵² photons s^-1 keV^-1 at 1 keV. In the bottom panel, the goodness of the fits are shown, with blue open circles indicating the obtained C-stat and the filled red circles indicating the expected C-stat with its rms uncertainties. The range of the above time-series is from 1 February 2012 to 4 February 2015. The vertical dotted lines in green indicate two interesting periods in 2013 and 2014, which were selected for the temporal variability analysis of Sect. 4 and production of rms spectra in Fig. 8. The vertical dashed lines in black indicate the start of each year for reference. The horizontal dashed lines in magenta represent the averages from previous years (2005 and 2007 Swift data from the unobscured epoch) derived in this work with the same model.