testing remotely sensed evapotranspiration estimates using airborne and ground measurements may 2004...
TRANSCRIPT
Testing Remotely Sensed Evapotranspiration Estimates Using Airborne and Ground
Measurements
May 2004
Cressida Savige, Andrew French, Andrew Western, Jeffrey Walker, Mohammad Abuzar, Jorg Hacker and
Jetse Kalma
Land Surface
Satellite
Satellite Image
Aircraft
LELE
MODEL
Surface Energy Balance Rn = H + LE + G
RnC
LEC
HS
RnS
LES
HC
G
2-SOURCE
G
H
Rn
LE
1-SOURCE
Irrigation Region
0 50Km
25
Airborne Flux Measurements
SENSIBLE HEAT FLUX
0
100
200
300
400
500
600
332500 333500 334500 335500 336500 337500
Easting
En
erg
y F
lux
De
ns
ity
(W
m-2
)
x 10 flights
wi = 109 Wm-2
btw = 43 Wm-2
NR ~ 1
LELATENT HEAT FLUX
0
50
100
150
200
250
300
332500 333500 334500 335500 336500 337500 338500
Easting
En
erg
y F
lux
De
ns
ity
(W
m-2
)
2-SOURCE = 183 Wm-2
SEBAL = 182 Wm-2
AIRBORNE = 136 Wm-2
H SENSIBLE HEAT FLUX
0
50
100
150
200
250
300
332500 333500 334500 335500 336500 337500 338500
Easting
En
erg
y F
lux
De
ns
ity
(W
m-2
)
SEBAL = 220 Wm-2
2-SOURCE = 217 Wm-2
AIRBORNE = 157 Wm-2
B = 1.2
AIRBORNE
B = 1.2
2-SOURCE
B = 1.2
SEBAL
LATENT HEAT FLUX (Wm-2)
0
50
100
150
200
250
300
0 50 100 150 200 250 300
Observed
Mo
de
lled
2-SOURCE
SEBAL
SENSIBLE HEAT FLUX (Wm-2)
0
50
100
150
200
250
300
0 50 100 150 200 250 300
Observed
Mo
de
lled
2-SOURCE
SEBAL
Regional Fluxes
0 5Km
2.5
0
50
100
150
200
250
300
H LE
En
erg
y F
lux
De
ns
ity
(W
m-2
)
2-SOURCE
2-SOURCE
SEBAL
SEBAL
AIRBORNE
AIRBORNE
B = 3.2
AIRBORNE
B = 2.8
2-SOURCE
B = 1.7
SEBAL
Model ComparisonDifference = 2-SOURCE - SEBAL
Sensible Heat Flux Difference Latent Heat Flux Difference
-160 1600 Wm-2
0 5Km
2.5 0 5Km
2.5
Findings…
• Model estimates are
• Scale of surface heterogeneity is important…
• Model agreement…Pasture: good
Sparse cover: poor
This project was supported by:
• Australian Research Council
• University of Melbourne
• Hydrological Sciences Branch, NASA Goddard Space Flight Centre
& Nanneella LandCare Group