Project Title: Estimation of Regional
Evapotranspiration through Remote Sensing.
Project PIs: Derrel L. Martin, A. Irmak, Suat Irmak, Shashi
B. Verma.
Grant period: 10/01/2006-12/31/2010.
Spatial distribution
of ET (mm) computed from Landsat 5 TM for Path 29 and Row 32; August 07, 2005.
Landsat Path-29 Row-32 Image Footprint
Presentation
(lecture given for GIS water resources class in 2006) on the Estimation of
Regional Evapotranspiration through Remote Sensing.
Poster presentation at Water
Colloquium.
October 27, 2006.
This project is on the
regional estimation of evapotranspiration (ET) with satellite-remote sensing
technique. We
are using a physically based multi step Surface Energy Balance Algorithm for
Land (SEBAL) to calculate daily ET from remotely sensed satellite data. We are
also measuring energy fluxes using Bowen Ratio Energy Balance System and Eddy
Correlation System over different land surfaces.
a) Eddy Correlation System, b)
Bowen Ratio Energy Balance System, c) Color composite
(bands 4,3,2) of Landsat 5 (08/07/06).
High
Frequency Evapotranspiration measurements during growing and the non-growing season in South Central Agricultural
Lab near Clay Center, NE.
Proposed Surface Energy Balance Methods
•
Surface Energy Balance Algorithm for Land (SEBAL)
•
Mapping Evapotranspiration at High Resolution and with
Internalized Calibration (METRIC)
Why
Remote Sensing
·
Synoptic coverage
·
Temporal resolution
·
Spatial domain
·
GIS compatible
·
Cost effective
Surface
Energy Balance with SEBAL/METRIC methods
Rn - G - λET - H + Δ = 0
where
Rn = Net radiation
G =
Soil heat flux
λET = Latent heat flux
H =
Sensible heat flux
Δ =
Change in storage
Assumptions
•
Principle of Energy Conservation
•
Energy arriving at the surface = Energy leaving the
surface
•
Only vertical fluxes considered (Advection ignored)
•
Minor energy components also ignored.
Methodology
for SEBAL/METRIC methods
