why sensor of automatic meteorological station often verification - Radiation sensor calibration

in order to guarantee the business of automatic meteorological station observation data accurate and reliable, and regularly carry out verification and calibration of automatic meteorological station is very important for a business work. Automatic meteorological station test is divided into the machine test and sensor laboratory verification and calibration data collector at the scene of one of two ways

radiant energy measurement and other physical quantities, also need to establish a benchmark instrument, determine the measurement method of benchmark instrument, and maintain and pass the benchmark methods. At present, the radiation measuring standard by national meteorological metrology station is responsible for the preservation and maintenance, by a PMO Absolute radiometer and two H - 6 F cavity is absolute, firing table, according to WRR, uncertainty is less than 0. 25% and every 2 years to radiation instrument for a verification of the network, to keep the station net radiation the accuracy of the measurement data.

radiation sensor sensitivity test under solar radiation conditions, the sky was clear and the sun more than 30 & deg; , direct irradiance is greater than 500 w/m&sup 2; , the temperature is 20 ℃ & plusmn; 10 ℃, wind speed is less than 5 m/s, relative humidity is less than 80%. Will work standards around the radiation form parallel to checked the instrument inside empty, instrument induction surface without any obstacle of outdoor test platform, using high accuracy multi-channel data collector ( Six and a half DMMS) Measurement of solar radiation instantaneous value at the same time, to be seized sensor voltage output value and the standard radiation table corresponding to time radiation worth ratio as the sensitivity of test table, complete radiation sensor calibration.