Fig. 1. Normalized SO₂ absorption cross-section and filter transmittance curves

Fig. 2. Comparison of acquisition information field of view. (a) Schematic of the field of view of the information acquired by four-image method; (b) schematic of the field of view of the information acquired by image reconstruction method

Fig. 3. Self-developed experimental instrument for remote sensing monitoring of ship exhaust. (a) Field test site situation; (b) experimental prototype of ship exhaust imaging remote sensing monitoring system

Fig. 4. Geographic orientation map of the experimental site, where the dot indicates the target pollution source and the triangle represents the measurement location

Fig. 5. Process comparison of image reconstruction method and four-image method

Fig. 6. Background fitting process for image reconstruction method. (a) Original image; (b) plume characteristic rejection; (c) comparison of the actual signal strength with the fitting signal strength; (d) background image obtained by fitting

Fig. 7. SO₂ column concentration inversion results of ship exhaust. (a) SO₂ column concentration inversion results of four-image method; (b) vertical pixel intensities at different locations obtained by four-image method; (c) SO₂ column concentration inversion results of image reconstruction method; (d) vertical pixel intensities at different locations obtained by image reconstruction method

Fig. 8. Comparison of three groups of SO₂ column concentration inversion results. (a) SO₂ column concentration inversion results of four-image method; (b) SO₂ column concentration inversion results of image reconstruction method

Fig. 9. Comparison of sky background variation between image reconstruction method and traditional method

Fig. 10. Comparison of emission rates between four-image and image reconstruction methods