Sensitivity of grass- and alfalfa-reference evapotranspiration to weather station sensor accuracy

Authors

Dana O. Porter, Dept. of Biological and Agricultural Engineering and Texas AgriLife Research and Extension Service, Lubbock, TexasFollow
Prasanna H. Gowda, USDA-ARS Conservation and Production Research Laboratory Soil and Water Management Research Unit, Bushland, Texas
Thomas H. Marek, North Research Field, Etter, Texas, Texas AgriLife Research, Amarillo, Texas
Terry A. Howell, USDA-ARSFollow
Jerry Moorhead, USDA-ARS Conservation and Production Research Laboratory Soil and Water Management Research Unit, Bushland, Texas
Suat Irmak, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2012

Citation

Applied Engineering in Agriculture Vol. 28(4): 543-549

Comments

Copyright 2012 American Society of Agricultural and Biological Engineers

Abstract

A 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 an automated weather station located at the USDA-ARS Conservation and Production Research Laboratory at Bushland, Texas were used for the analysis. Results

indicated that grass (ET_os) and alfalfa (ET_rs) 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. Given the highly advective conditions of the Texas High Plains and the relative sensitivity of ET calculations to errors in wind speed, special care is recommended in siting, sensor placement, and sensor maintenance for agriculturally-based ET weather stations.