| Intro |
Land surface temperature (LST), and normalized difference vegetation index
(NDVI) are the key surface biophysical parameters which are used to estimate
Evapotranspiration (ET) at regional scale. Due to the distortions and noises caused by the resence of the atmosphere on the Sun-target-Sensor path, the reflectance and radiance nformation recorded by the remote sensor is fiercely influenced by the sensor characteristics,atmospheric conditions, the geometry of illumination and viewing directions, terrain and others,which becomes impediments for the quantitative analysis and measurement especially in land
surface parameters and disables multi-temporal comparisons in long-term land surface ET monitoring. Uncertainties also are brought into satellite data under haze weather condition.
In this case, a haze removal algorithm is applied to multi-temporal Landsat TM images,then atmospheric correction of visible to thermal band of images over land surfaces is done by using actor-2 model.
Finally, derived parameters and Evapotranspiration data are analyzed: (1)Sensitivity analysis is conducted by comparisons of corrected and uncorrected surface biophysical parameters including surface energy flux(net surface radiation flux Rn, soil heat flux G0,sensible flux H and latent flux LE); (2)Multi-temporal variation on corrected parameters is analyzed in areas of interested. |
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