| In situ measurement of chlorophyll-a concentration by sensors is an important means to obtain real-time, continuous and long time series data. Based on the principle analysis of RBR and ECO (Environmental Characterization Optics) chlorophyll-a fluorescence sensors and basic performance tests such as linearity, stability and repeatability, this paper uses a single algae seed culture solution and field data in the northern waters of the South China Sea in 2020 to calibrate the sensors, and verifies the new sensor calibration coefficient. The results show that the accuracy of chlorophyll-a concentration measurement with the new coefficient of the two sensors is obviously improved compared with the original factory-produced coefficient. For RBR sensor, the mean absolute error decreases from 1.93 μg/L to 0.35 μg/L, and the mean relative error decreases from 55.1% to 10.9%. The algal fluid coefficient of ECO sensor is significantly better than the calculated results of factory coefficient and field data calibration coefficient.Themeanabsoluteerrordecreasesfrom1.76μg/Lto0.59 μg/L, and the mean relative error decreases from 50.3% to 15.1%. The improvement of sensor measurement accuracy can provide important data support for marine environment monitoring and marine ecological disaster early warning. |
