Estimation The Surface Evapotranspiration Based On The SEBS Model

Evapotranspiration consists of two parts:soil evaporation and vegetation transpiration.It is an important part of surface water and heat transfer and water cycle.Accurate estimation of evapotranspiration can provide a good theoretical basis for optimal allocation of water resources and farmland irrigation research.Due to the wide distribution of China's regions,complex terrain and geomorphological conditions,and expensive equipments for evapotranspiration monitoring,it is difficult to monitor the regional evapotranspiration in a wide range through the traditional approaches.The development of remote sensing technology provides an economically permissible,technically feasible solution for obtaining a wide range of land surface evapotranspiration.This paper takes Jinan-Taian City as the research area,obtains Landsat 5 remote sensing data and micro-meteorological data,The study used the inverse distance weight method to spatially interpolate the air temperature and applied the interpolated air temperature as one of the important input parameters of the mono-window algorithm to estimate the land surface temperature,which aimed for improving the inversion accuracy of the mono-window algorithm,Combined the surface temperature with the SEBS model,the surface evapotranspiration was simulated and the daily evapotranspiration of evapotranspiration was obtained by the constant EF method.In order to evaluate the application effect of the SEBS model in the region,the results of the estimated evapotranspiration were verified by using the observation data of the Yucheng station.The results showed that estimation error of the SEBS is between 6.6%and 35%.The temporal and spatial characteristics analysis of the evapotranspiration inversion results showed that the spatial distribution of evapotranspiration in the study area was relatively uniform,and the central part was affected by Taishan to form a local evapotranspiration area.The evapotranspiration was different from the surrounding area.Affected by human activities,the impervious layer?town construction land?replaced the natural underlying surface,changing the surface energy change,forming a unique urban heat island effect.Based on the spatial distribution of remote sensing inversion evapotranspiration,the micro-meteorological data and flux data of Yucheng Station,the relationship between evapotranspiration variation and response factors.Evapotranspiration is affected by the growth pattern of crops and irrigation,and the law is significant.It is roughly summarized as follows.the evapotranspiration is declined?winter wheat sowing period?from December to January;evapotranspiration rose back from January to March,?wintering to greening?;evapotranspiration increased from March to May,?from jointing to flowering?;evapotranspiration fell sharply in June,?winter wheat harvest,summer corn planting?;evapotranspiration is gentle from July to September,?sowing silk to mature tillage?;evapotranspiration is reduced in October,?summer maize harvest?.The correlation of evapotranspiration and its influencing factors in different seasons is different.The correlation between the impact factors and evapotranspiration is in spring and autumn:temperature>water vapor density>horizontal wind speed>CO₂>vertical wind speed;summer water vapor density>temperature>CO₂ concentration>vertical wind speed>horizontal wind speed;Water Vapor Density>Horizontal Wind Speed>CO₂ Concentration>Vertical Wind Speed.Based on the partial correlation,the fitting equations of evapotranspiration and its influencing factors are obtained.The main influencing factors of spring evapotranspiration are temperature and vertical wind speed,and the main influencing factors in autumn and winter are temperature.