EVAPOTRANSPIRATION ESTIMATION OVER AGRICULTURAL PLAINS USING MODIS DATA FOR ALL SKY CONDITIONS.
Agricultural, water resources and forest management applications require adequate
information about evapotranspiration (ET) over a range of spatial and temporal scales.
Several methods, with reasonable accuracy, exist for computing ET for clear sky
conditions using satellite remote sensing data. However, estimation of ET for cloudy
days using remote sensing data remains a challenge. ... read moreWe have developed an ET estimation
algorithm for all sky conditions using primarily remote sensing data. The proposed
approach is based on an extension of the Priestley-Taylor form of representation, a
contextual triangular interpretation of remotely sensed surface temperature and
vegetation index, and requires estimation of evaporative fraction, soil heat flux and
land surface net radiation that can be derived from the Moderate Resolution Imaging
Spectroradiometer (MODIS). For cloudy pixels, a regression-based algorithm utilizes the
MODIS cloud data product for cloud top temperature, cloud fraction, cloud emissivity,
cloud optical thickness and land surface temperature to calculate net radiation and
thereafter ET. The algorithm has been tested and validated with ground observations from
South Great Plains in the United States with reasonable accuracy of R2 ranging between
56.7% and 66.9% and an average root mean square of around 70 W/m^2, we then, applied the
algorithm over the agricultural plains of the Ganges Basin. We anticipate that our
algorithm has capabilities to provide a continuous estimation ET, which can then be used
for computing several processes such as water stress in croplands over a range of
spatial and temporal scales.
Thesis (M.S.)--Tufts University, 2012.
Submitted to the Dept. of Civil Engineering.
Advisor: Shafiqul Islam.
Committee: Laurie Baise, and Antarpreet Jutla.
Keywords: Environmental engineering, Remote sensing, and Agriculture engineering.read less