Fig. 6.

Multi-Gas^Direct SO2-AE, H2S-AE and HCl-A1 sensor signals with SO₂, H₂S and HCl gas abundances derived by standard data analysis. Noise in the H₂S time series is primarily caused by sensor response effects, and the HCl time series shows evidence for slow sensor response relative to SO₂. The SO₂ time series derived from SO2-AE is shown alongside measurements by two other electrochemical sensors, SO2-A4 in Multi-Gas^Direct and SO2-3ST/F in Multi-Gas^Pump. Time periods for analysis of VOR, NEC and BN gas ratios are indicated