Incorporating field wind data to improve crop evapotranspiration parameterization in heterogeneous regions

Authors

Ray G. Anderson, USDA-ARSFollow
Jorge F.S. Ferreira, USDA-ARSFollow
Dennise L. Jenkins, USDA-ARSFollow
Nildo da Silva Dias, USDA-ARSFollow
Donald L. Suarez, USDA-ARSFollow

Document Type

Article

Date of this Version

2017

Citation

Irrig Sci (2017) 35:533–547, DOI 10.1007/s00271-017-0560-x.

Comments

U.S. government work.

Abstract

Accurate parameterization of reference evapotranspiration ( ET₀) is necessary for optimizing irrigation scheduling and avoiding costs associated with over-irrigation (water expense, loss of water productivity, energy costs, and pollution) or with under-irrigation (crop stress and suboptimal yields or quality). ET₀ is often estimated using the FAO-56 method with meteorological data gathered over a reference surface, usually short grass. However, the density of suitable ET₀ stations is often low relative to the microclimatic variability of many arid and semi-arid regions, leading to a potentially inaccurate ET₀ for irrigation scheduling. In this study, we investigated multiple ET₀ products from six meteorological stations, a satellite ET₀ product, and integration (merger) of two stations’ data in Southern California, USA. We evaluated ET₀ against lysimetric ET observations from two lysimeter systems (weighing and volumetric) and two crops (wine grapes and Jerusalem artichoke) by calculating crop ET ( ET_c) using crop coefficients for the lysimetric crops with the different ET₀. ET_c calculated with ET₀ products that incorporated field-specific wind speed had closer agreement with lysimetric ET, with RMSE reduced by 36 and 45% for grape and Jerusalem artichoke, respectively, with on-field anemometer data compared to wind data from the nearest station. The results indicate the potential importance of on-site meteorological sensors for ET₀ parameterization; particularly where microclimates are highly variable and/or irrigation water is expensive or scarce.