Fig. 1. Simulation of edge detection process

Fig. 2. Relationship between temperature and full width at half height (FWHM)

Fig. 3. Relationship between temperature and normalized intensity

Fig. 4. Experimental block diagram

Fig. 5. Relationship between detector output intensity ratio or intensity ratio difference with temperature when salinity is 35‰. (a) Relationship between intensity ratio with temperature; (b) intensity ratio difference with temperature

Fig. 6. Detector output intensity ratio and intensity ratio difference curves when salinity is 30‰40‰. (a) Intensity ratio curves; (b) intensity ratio difference curves

Fig. 7. Salinity profiles of Bohai Sea and East Sea in China. (a) Bohai Sea; (b) East Sea

Fig. 8. Inversion algorithm

Fig. 9. Temperature inversion error under different salinities

Fig. 10. Convergence of iterative algorithm. (a) Temperature convergence curve; (b) salinity convergence curve

Fig. 11. Temperature inversion error when adding different degrees of jitter to intensity ratio. (a) Adding 1.3 per 1000 jitter; (b) adding 1 per 1000 jitter; (c) 0.2 K error tolerance