Spatial Variability in Sensitivity of Reference Crop ET to Accuracy of Climate Data in the Texas High Plains.

A detailed sensitivity analysis was conducted to determine the relative effects of measurement errors in climate data input parameters on the accuracy of calculated reference crop evapotranspiration (ET) using the ASCE-EWRI Standardized Reference ET Equation. Data for the period of 1995 to 2008 from 18 automated weather stations in the Texas High Plains were used for the analysis. Results indicated that grass and alfalfa reference crop ET were most sensitive to measurement errors in wind speed and air temperature followed by incoming shortwave (solar) radiation, and that data sensitivity was greater during the mid-summer growing season in this semi-arid region. Further, sensitivity of reference crop ET to errors in the climate data input significantly varied in both latitude and longitudinal directions.