Developmentevaluation of an actual evapotranspiration estimation algorithm using satellite remote sensingmeteorological observational network in Oklahoma

Abstract

Actual evapotranspiration (AET) estimation using satellite sensors can improve water resources planningwater regulation in irrigated areas. This paper evaluates an AET estimation algorithm developed by integrating satellite remote sensingan environmental monitoring network in Oklahoma, USA for operational daily water management purpose. First, a surface energy balance evapotranspiration (ET) algorithm is implemented to estimate actual ET by integrating the twice-daily overpass of Moderate Resolution Imaging Spectroradiometer (MODIS) sensor dataOklahoma's world-class environmental monitoring network—Mesonet—with 5-minute data acquisition in real time. Second, accuracy of the estimated ET is evaluated at the site scale using Ameriflux tower latent heat fluxMesonet site crop ET on daily, 8-dayseasonal basis. The results showed that MODIS/Mesonet-AET (MM-AET) estimation showed agreement with ground observations, with daily ET bias less than 15%seasonal bias less than 8%. Additionally, actual ET modelled from a water balance budget analysis in a heavily instrumented basin compares favourably (bias < 3%) with the MM-AET at catchment scales with an order of several hundreds square kilometres. This study demonstrates that (1) the MM-AET estimation is acceptable for daily actual ET estimation(2) it is feasible to implement the proposed MM-AET algorithm in real time for irrigational water resources management at the scale of irrigation projects in Oklahoma.