Regional evapotranspiration estimation by a two layer model based on remote sensing in Baojixia irrigation area

TM data and relevant meteorological data for typical days in different seasons from 2000—2011
in Baojixia irrigation area was used to develop land-surface evapotranspiration (ET)remote sensing retrieval
 system, and to estimate daily ET in Baojixia irrigation area.Tendencies in temporal and spatial distribution of
 ET and ET changes of different land use in representative seasonal days were analyzed. The average daily ET
 on typical days was found to be about5 .06 mm in spring,5.36mm in summer,4.24mm in autumn, and1.03
mm in winter.A unimodal distribution seemed to dominate.Seasonal variation was found to be significant.
Spatial distribution in different seasonal representative days showed large discrepancies. The seasonal variation
 indaily evapotranspiration characteristics wasfoundto besimilarin differentland usetypes. Actual
 evapotranspiration of the study area was calculated from Penman-Monteithe quation to compare with remote
sensing retrieval system estimates. The correlation coefficient R2 was found to be greater than 0.9 in farmland
 and forests. Therefor ethe current system could be used for accurate estimation of evapotranspiration in
Baojixia irrigation area.