Comparing ASTER and Landsat 7 ETM+ imagery to estimate daily evapotranspiration in Mediterranean environment

Carlo Montes, NASA Goddard Institute for Space Studies, carlo.montes@nasa.gov (Presenter)
Wenjing Ma, Institute of Research for Development, France, mawenjing.mwj@gmail.com
Frederic Jacob, Institute of Research for Development, France, frederic.jacob@ird.fr

The estimation and monitoring of evapotranspiration (ET) in agricultural watersheds for hydrological and/or agricultural purposes requires considering its variability both in the space and time domain. Long-term remotely sensed data, especially in the thermal infrared (TIR) and at hectometric resolution, can provide a basis to assess ET and the involved processes and scales. In this work, we estimated daily ET at the regional extent over a small agricultural Mediterranean catchment (65 km²) in Southern France by using Landsat 7 ETM+ and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery. We used 4 ASTER (90 m TIR) and Landsat (60 m TIR) images collected for the same date during the growing season in 2007 and 2008 in order to compare the performance of both instruments to retrieve ET by applying the Simplified Energy Balance Index (S-SEBI) remote sensing contextual model. This model allows estimating daily ET as a function of the observed within-image relationship between surface radiometric temperature and albedo. Results show that uncertainties associated with differences in radiometric quality (lower for Landsat), spectral configuration and atmospheric corrections applied to Landsat lead to a different performance for input (surface temperature and albedo) and intermediate variables (e.g. net radiation, soil heat flux). However, given that the S-SEBI model is based on the difference in surface temperature for each albedo class, a similar performance in terms of daily ET was obtained for ASTER and Landsat. Being ASTER an experimental instrument (images collected according to the scientific and programmatic context), obtaining similar results with an operational instrument such as Landsat allows considering the use of the latter to obtain long-term ET estimations at the regional extent.

Presentation: 2015_Poster_Montes_232_147.pdf (6392k)

Presentation Type:  Poster

Session:  Theme 1: Tracking habitat change through new integrative approaches and products   (Mon 1:30 PM)

Associated Project(s): 

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Poster Location ID: 232