modis estimate of canopy water content susan l. ustin university of california davis july 14, 2004
TRANSCRIPT
MODIS Estimate of
Canopy Water Content
Susan L. UstinUniversity of California Davis
July 14, 2004
(Ustin et al., 1999)AVIRIS Composite 980 nm Water Absoroption
Cw/LAI Estimation from MODIS
0
0.1
0.2
0.3
0.4
0.5
0.6
400 900 1400 1900 2400
W ave le ngth (nm )
Ref
lect
ance
cw=0.001 cw=0.002 cw=0.003 cw=0.01
cw=0.015 cw=0.02 cw=0.03
cw=0.001
cw=0.03
Band4R858.5nm
Band5R1240nm
MODIS Water Index (SRWI):
1240
858SRWI
R
R
(Pablo Zarco-Tejada et al., 2001 IEEE; Rem. Sens. Env. 2003)
y = 0.04x - 0.0208R2 = 0.7238
0.00
0.01
0.02
0.03
0.04
0 0.5 1 1.5 2
Leaf (fw-dw)/dw
Est
ima
ted
Cw
(cm
)y = 0.0173x - 0.0095
R2 = 0.7772
0.00
0.01
0.02
0.03
0.04
0 0.5 1 1.5 2 2.5
Leaf (fw-dw)/dw
Est
ima
ted
Cw
(cm
)
y = 1.3355x - 0.0124R2 = 0.7183
0.00
0.01
0.02
0.03
0.04
0 0.01 0.02 0.03 0.04 0.05
Leaf [(fw-dw)/dw]*LHSAV
Est
ima
ted
Cw
(cm
)
y = 1.1134x - 0.0088R2 = 0.8644
0.000
0.005
0.010
0.015
0.020
0 0.01 0.02 0.03
Tim e Averaged [(fw-dw)/dw]*LHSAV
Est
ima
ted
Cw
(cm
)
Comparison between Field Measured Water Content VS. MODIS Prediction
Water Content estimation from MOD09A1: seasonal variation
Cw=0.03
Cw=0.02
Cw=0.01
Cw=0
(Zarco-Tejada et al., 2003 Rem. Sens. Env.)
Canopy water content in Southern California VegetationMeasured by MODIS Satellite
Seasonal Drought and Wildfire Potential
+
_
H2O
Canopy Water Content
• Estimates of LAI
• Estimates of Plant Water Stress
• Estimates of Wildfire Fuel Moisture Content
Roberts et al., Ecosystems 2004
LAI Estimated by NDVI VS EWT
Wind River Ameriflux Site
Wisconsin Tall Tower Flux Site
S.N. Burrows et al.Ecosystems 2002
MODIS Data 2000-2001
0
2
4
6
8
10
12
14
1 5 9 13 17 21 25 29 33 37 41 45 49 53 57
Week Number
LA
IModel1
MODIS
Model2
Estimate of LAI from MODIS Water Content vs. MOD09A1
San Francisco
Los Angeles
1-980 CR AVIRIS Image
Estimating Water StressFrom Water Content
1-CR Ratio (899-1060 nm) vs. Time
0.00
0.01
0.02
0.03
0.04
0.05
0.06
8/25/99 8/30/99 9/4/99 9/9/99 9/14/99 9/19/99 9/24/99 9/29/99
Date of Year 1999
1-98
0 C
ontin
uum
Rem
oval
l
Changes in Canopy Water Content after Irrigation Cutoff
+ Water
- Water
Within Field Water Content vs.Days Since Last Irrigation
y = -469.4x + 54.649
R2 = 0.3251
0
2
4
6
8
10
12
14
16
18
0.08 0.085 0.09 0.095 0.1 0.105 0.11 0.115 0.12
1-980 Value
Days
Sin
ce L
ast I
rriga
tion
y = -409.06x + 51.855
R2 = 0.8128
0
2
4
6
8
10
12
14
16
18
0.08 0.085 0.09 0.095 0.1 0.105 0.11 0.115 0.12 0.125
1-980 CR
Days
Sin
ce L
ast I
rriga
tion
Pima Fields Only Acala Fields Only
Estimating Fuel Moisture Content
■ Dry Matter in Fresh Samples
y = 0.8308x + 0.0009
R2 = 0.342
0.00
0.01
0.01
0.02
0.02
0.03
0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016
Inv-PROSPECT Dry matter (g/cm2)
Mea
sure
d D
ry m
atte
r fr
om f
resh
sam
ples
(g
/cm
2 )
Stephane Jacquemoud et al, 1996
P-value<0.0001
Estimates of Fuel Moisture Content■ dry matter estimated seasonally
■ water content from Water Index
0
50
100
150
200
250
300
96 112
128
144
160
176
192
208
224
240
256
272
Day of the year
FM
C
0
0.5
1
1.5
Fu
nct
ion
of
Da
y
Cistus
Grassland
Func-cistus
Func-grass
Emilio Chuvieco et al., in press