Modeling Evapotranspiration and Its Components in Qianyanzhou Plantation Based on Remote Sensing Data

In this study,with the verification and improvement to the evapotranspiration(ET)model(PT-Fi model),we simulate the ET and its components of the planted coniferous forest ecosystem at Qianyanzhou during 2003 and 2008 by using remote sensing data from MODIS and meteorological data.The estimated ET is compared with the observation from eddy flux tower sites.The results show that the simulated annual ET is about 2.4% lower than measurement,with a decision coefficient value(R2) of 0.83 and root mean square error of 0.61 mm·d-1.As to the ET components,soil evaporation is 12% of simulated ET with relative stability at seasonal and interannual scale.With obvious seasonal and interannaual variability,interception evaporation contribute 23% of the ET and with the same change tendency as precipitation.Canopy transpiration is about 65% of ET with obvious seasonal variation and interannual stability.During January to March,photosynthesis isn't to be strong,canopy transpiration and evapotranspiration ration(T/ET) less than 30%,with the enhance of canopy transpiration,T/ET increases rapidly after April,in the end of July up to about 90%.Because of the data is easy to get at regional dimension in this model,which can lay a foundation for the further scaling up of evapotranspiration estimation in subtropical coniferous forest.