基于遥感双层模型的宝鸡峡灌区日蒸散发估算

本文选取了陕西宝鸡峡灌区为研究区,基于遥感双层模型,选择2000-2011年不同季节典型日的TM 数据,辅以气象观测资料,估算了宝鸡峡灌区典型日蒸散发,分析灌区内日蒸散发的时空分布以及不同土地利用类型日蒸散发季节变化.结果表明,基于遥感双层模型估算半干旱区的日蒸散发是可行的.模拟典型日中,春季晴日灌区日蒸散发约为5.06mm、夏季约为5.36mm、秋季约为4.24mm、冬季约1.03mm,呈单峰型分布,有较好的季节变化特征;不同季节日蒸散发的空间分布差异较大,不同土地利用类型的日蒸散发季节变化特征相似,但略有不同.利用Penman-Monteith公式计算值结合作物系数验证日蒸散发估算精度,其中耕地和林地相对误差约为20%,相关系数R2>0.7,表明遥感反演的日蒸散发精度较高. 

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 about 5.06 mm in spring,5.36 mm in summer,4.24 mm in autumn,and 1.03mm 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 in daily evapotranspiration characteristics was found to be similar in different land use types.Actual evapotranspiration of the study area was calculated from Penman-Monteith equation to compare with remote sensing retrieval system estimates.The correlation coefficient R2 was found to be greater than 0.9 in farmland and forests.Therefore the current system could be used for accurate estimation of evapotranspiration in Baojixia irrigation area.