Abstract:
The study was carried out to design, construct and evaluate the field performance of an Automated Weather Station (AWS) capable of remote access via the internet. The AWS consisting of a datalogger and electronic sensors to measure net solar radiation, global solar radiation, air temperature, wind speed and rainfall were developed using locally sourced materials. The sensors were calibrated against standard sensors at West Africa Science Centre on Climate and Adapted Land Use (WASCAL) Meteorology observatory, Federal University of Technology, Akure, Nigeria. The net radiation, global radiation, air temperature and wind speed sensors were calibrated against standard Kipp & Zonen net radiation sensor, Apogee Instrument global radiation sensor, Vaisala HMP45C Thermometer & Hygrometer air temperature sensor and R.M. Young Company wind speed sensor respectively. The calibration yielded the following sensitivity values 0.032637mv/W/m2, 0.0220799mv/W/m2, 10mv/deg, 10.86956count/m/s and 7.0423tip /mm respectively, for the net, global radiation, air temperature, wind speed sensors and tipping bucket rain guage respectively. The observed offsets were -123.3W/m2, + 5.773W/m2 and -0.001oC respectively, for the net, global radiation and air temperature sensors respectively. The performance and the coefficient of efficiency of the constructed sensors were compared with standard sensors and objectively evaluated using the Mean Bias Error (MBE), Root Mean Square Error (RMSE) and Standard Deviation (STDEV). The coefficient of correlation (R) values for the net radiation, global radiation, air temperature and wind speed sensors were 0.862554, 0.690, 0.9818 and 0.625 respectively, thus showing good association between data obtained with the constructed sensors and the standards. The MBE results for net radiation, global radiation, air temperature and wind speed sensors were -0.01099W/m2, -0.01036W/m2, 0.000012oC and -0.000824m/s respectively and the RMSE values 0.188137W/m2, 0.176444W/m2, 0.000557oC and
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0.014033m/s respectively. The STDEV for net radiation, global radiation, air temperature and
wind speed sensors were 36.303W/m2, 95.758W/m2, 0.06oC and 0.087m/s respectively. In
conclusion, the locally assembled AWS is viable and has promise for field deployment.
