Abstract:The meteorological evaporation sensor uses the principle of ultrasonic distance measurement to measure the height of the water level in the evaporation cylinder.During evaporation calibration,the collector can directly read the water value and measure its output current,and obtain the water level value through the water level current conversion coefficient.The water level current conversion coefficient can be divided into ideal state,full range,and calibration section according to the measurement principle and actual measurement reuirements.By comparing the calibration results of four AG2.0 evaporation sensors under different water level value acquisition methods,it was found that the measurement error of the water level values directly read by the collector and obtained from the water level current conversion coefficient of the calibration section was significantly better than other methods.Therefore,it is recommended to use a collector to directly read during on-site calibration,and to use calibration segment current conversion in laboratory calibration to improve measurement accuracy and further reduce measurement errors.