This project investigates the use of satellite remote sensing
technology for extrapolating point measurements of ET over broader
spatial scales. For this analysis, atmospheric corrections were
applied to Landsat thematic mapper (TM) multispectral data spanning
the visible, near-infrared, and thermal regions of the
electromagnetic spectrum. These data were processed to yield
reflectance, NDVI, and Tr values. Detailed meteorological and
hydrologic data collected at nine locations as part of the South
Florida Ecosystem Program (German, 1996) were used to model ET.
Assuming the proportion of available energy going to latent heat of
vaporization is constant (that is, a constant ET fraction) throughout
the day (Hall and others, 1992), the values for reflectance, NDVI,
and Tr for the areas of sufficient distances surrounding ground
meteorological sites were regressed against the daily total ET for
the date of the satellite overpass. The observed relation was used to
extrapolate ET to all locations within the scene.
For longer term monitoring and modeling, the ability to estimate ET
by means of satellite remote sensing without the need for extensive
ground-based data collection is desirable. The methods and data sets
developed through the above analysis will serve as one measure of
spatially distributed ET against which subsequently developed
techniques can be compared.