Fig. 5.

Root Mean Square Error (RMSE) of calibration (blue) and cross-validation (red) with respect to number of components used – (a). Absolute regression coefficients of the 10 components model with respect to wavelength – (b). Benchmarking prediction of NO2 values with the 10-components model – (c). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)