Error Analysis of Evapotranspiration Measurements

• Main Author: Hartman, Robert K.
• Other Authors: University of Arizona
• Language: en_US
• Published: Arizona-Nevada Academy of Science 1980
• Subjects: Water resources development > Arizona.; Hydrology > Southwestern states.; Water resources development > Southwestern states.
• Online Access: http://hdl.handle.net/10150/301223

From the Proceedings of the 1980 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona - Nevada Academy of Science - April 11-12, 1980, Las Vegas, Nevada === This paper examines the effects of random errors in the precision of latent energy estimates from the Bowen ratio model. The analysis identifies improvements in the instrumentation and in the field measurement techniques. Bowen ratio energy budget measurements were made over an extensive stand of mesquite (Prosopis pubescens) in the San Pedro River valley near Mammoth, Arizona. The error analysis indicated mean half -hour 95 percent confidence intervals for latent energy and sensible heat flux of 0.48 ± 0.09 and 0.21 ± 0.09 cal/cm²/min, respectively. A majority of the random error was associated with the temperature and humidity measurements used in the Bowen ratio model. Psychrometer circuitry and calibration procedures were modified to reduce measurement errors. Subsequent Bowen ratio measurements were made over a kochea (Kochea scoparia) pasture adjacent to the Pecos River near Roswell, New Mexico. The improvements were effective in reducing the mean half-hour 95 percent confidence intervals for latent energy and sensible heat flux to 0.27 ± 0.01 and 0.23 ± 0.01 cal/cm²/min, respectively.