ASSESSMENT OF THE ACCURACY OF METEOROLOGICAL DATA OBTAINED FROM A VIRTUAL WEATHER STATION FOR THE PURPOSE OF ESTIMATING ETO FOR THE CONDITIONS OF THE SOUTH UKRAINE

The article presents an assessment of the accuracy of meteorological data obtained from the Visual Crossing Weather Data (VWS VCWD) virtual meteorological station and the calculated reference evapotranspiration (ETo) based on these data for the conditions of southern Ukraine. It has been established that the data on air temperature and relative humidity are obtained with high accuracy, with MAPE and RMSE errors of 4,5% and 0,94°C and 9,1% and 7,53%, respectively. Good accuracy is characteristic of dew point temperature and solar radiation, with MAPE and RMSE errors of 20,9% and 1,44 °C and 17,4% and 3,41 MJ/m²·day, respectively. Dew point temperature data can also be obtained with satisfactory accuracy depending on the observation period. The MAPE and RMSE errors for water vapor pressure deficit are 46,2% and 0,21 kPa, respectively, which corresponds to satisfactory accuracy. Depending on the observation period, water vapor pressure deficit data can also be obtained with unsatisfactory accuracy. Wind speed data at a height of 2 m, obtained with unsatisfactory accuracy, have MAPE and RMSE errors of 104,3% and 1,20 m/s, respectively. To improve the accuracy of the meteorological data obtained, correction factors were calculated, and when applied, the accuracy of all meteorological data obtained is improved. The possibility of calculating ET using data from the Visual Crossing Weather Data virtual meteorological station for the period April-September with good accuracy has been confirmed. The MAPE error was 13,7%, and the RMSE was 0.62 mm. To improve the accuracy of ET calculations in southern Ukraine, a correction factor of 0.95 must be used. Taking this into account, the accuracy of ET calculations for the period May-August increases to 89%, and the RMSE is 0,63 mm. The use of refined meteorological data reduces the accuracy of ET calculations by 4,8% and increases the RMSE by 0,15 mm. Based on the results of the research, a web application will be developed to calculate ET and ETc using the FAO56-RM methodology with data from VWS Visual Crossing Weather Data.