HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Ibáñez, M. Articles by Castellví, F. Search for Related Content PubMed Articles by Ibáñez, M. Articles by Castellví, F. Agricola Articles by Ibáñez, M. Articles by Castellví, F. Related Collections Agroclimatology

AGROCLIMATOLOGY

Simplifying Daily Evapotranspiration Estimates over Short Full-Canopy Crops

Dep. Medi Ambient i Ciències del Sòl, Universitat de Lleida, Av. Rovira Roure 177, 25198 Lleida, Spain

m.ibanez{at}macs.udl.es

A knowledge of daily evapotranspiration (E) from surface radiative temperature at a regional scale is of interest in agronomy. The aerodynamic formulation and the radiative Bowen ratio–energy balance method provide good estimates of instantaneous E based on remote-sensed canopy temperatures. Instantaneous latent heat flux estimates for the daytime period can be integrated to obtain a value for daily E when detailed crop knowledge and continuous meteorological measurements are available. We propose a different method for estimating daily evapotranspiration for short, unstressed crops with a leaf area index (LAI) > 3. The method is based on the radiative Bowen ratio–energy balance method and on the similarity between the diurnal course of E and solar irradiance. This regression-based approach uses continuous measurements of air vapor pressure, air temperature, surface radiative temperature, and solar irradiance during daylight hours. Moreover, detailed crop knowledge is not required. The method was tested in a Mediterranean area with semicontinental climatic characteristics on grass (Festuca arundinacea Schreb.), wheat (Triticum aestivum L.), and alfalfa (Medicago sativa L.). Daily E was estimated with an error <15% compared with estimates of E made using a Bowen ratio–energy balance equipment. This new approach is promising for remote sensing applications at a regional scale, although it requires further verification for other climatological conditions.

Abbreviations: E, evapotranspiration • DOY, day of year • LAI, leaf area index • RMSE, root mean square error