Fig. 1. Flow chart of data processing of BTX-DOAS

Fig. 2. Variation of absorption coefficient with incident light intensity

Fig. 3. Variation of differential absorption coefficient with incident light intensity

Fig. 4. BTX concentrations retrieving. (a) No particles, no random noise (fitting residual with a standard deviation of 1.78×10^-7 cm^-1); (b) no particles, random noise (fitting residual with a standard deviation of 3.65×10^-6 cm^-1); (c) particles, no random noise (fitting residual with a standard deviation of 1.18×10^-6 cm^-1); (d) particles, random noise (fitting residual with a standard deviation of 4.83×10^-6 cm^-1)

Fig. 5. Variations of differential absorption coefficient in the absence of particles and the change of particle parameters

Table 1. Initial parameters setting for DOAS numerical simulation

Table 2. Influence of variation of incident light intensity on retrieved concentrations of BTX

Table 3. Effects of particle parameters on retrieved concentrations of BTX