a project linking in-situ and satellite measurements to validate modis terrestrial ecology products...
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A Project Linking In-situ and Satellite Measurementsto Validate MODIS Terrestrial Ecology Products
Warren B. Cohen, US Forest Service; Stith T. Gower, University of Wisconsin;
David P. Turner, Oregon State University; Peter B. Reich, University of Minnesota;
Steven W. Running, University of Montana
Objectives
• Develop better understanding of the climaticand ecological controls on total net primaryproduction and carbon allocation within andamong biomes
• Learn how flux tower-measured NEE andfield-measured NPP co-vary in time & how totranslate between them using ecological models
• Explore errors and information losses thataccrue when extrapolating field data to coarse-grained (1 km) surfaces
• Provide high quality site-specific data layersat four sites that can be compared to MODISand other sensor products
Technical
Scientific
Sites
BOREAS Northern Old Black Spruce (NOBS)
Muskeg (open black spruce),
“Closed” black spruce, Aspen,
Wetlands, Jack pine
Harvard Forest (HARV) LTER
Mixed hardwoods, Eastern hemlock,
Red pine, Old-field meadow
Konza Prairie Biological Station (KONZ) LTER
Tallgrass, Shortgrass, Shrub, Gallery forest; grazing and burning regimes
Bondville Agricultural Farmland (AGRO) Corn, Soybeans, Fallow
Field-BasedSampling Design
100 25m2 plots
80 in a nested spatial series
20 plots broadly distributed
Plot measurements
Vegetation cover
LAI, fPAR
Aboveground biomass
Aboveground productivity
Belowground productivity
AGRO (29 July 99)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0-1 2-3 4-5 6-7 8-9 10-11 12-13
LAI
Fra
ctio
n o
f O
bse
rvat
ion
s
Corn Soybeans
27 July 99
P vs. O r^2 = 0.72
LAI
98 % accurate(cross validation)
3.0
3.5
4.0
4.5
5.0
0 2 4 6 8 10 12
LAI
TM
1 R
efle
ctan
ce (
%)
Corn Soybeans
3.0
3.5
4.0
4.5
5.0
5.5
6.0
0 2 4 6 8 10 12
LAI
TM
2 R
efle
ctan
ce (
%)
Corn Soybeans
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0 2 4 6 8 10 12
LAI
TM
3 R
efle
ctan
ce (
%)
Corn Soybeans
30
35
40
45
50
55
60
0 2 4 6 8 10 12
LAI
TM
4 R
efle
ctan
ce (
%)
Corn Soybeans
14.0
14.5
15.0
15.5
16.0
16.5
17.0
0 2 4 6 8 10 12
LAI
TM
5 R
efle
ctan
ce (
%)
Corn Soybeans
4
5
6
7
8
9
10
0 2 4 6 8 10 12
LAI
TM
7 R
efle
ctan
ce (
%)
Corn Soybeans
0.75
0.80
0.85
0.90
0.95
0 2 4 6 8 10 12
LAI
ND
VI
Corn Soybeans
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
0 2 4 6 8 10 12
LAI
Sp
ectr
al I
nd
ex
Corn Soybeans
Combined Spectral Index
0
5
10
15
0 5 10 15
Observed LAI
Pre
dic
ted
LA
ICorn
Soybeans
Indiv idual Spectral Index, Inverse
0
5
10
15
0 5 10 15
Observed LAI
Pre
dic
ted
LA
I
Corn
Soybeans
Indiv idual NDVI, Inverse
0
5
10
15
0 5 10 15
Observed LAI
Pre
dic
ted
LA
I
Corn
Soybeans
Indiv idual Spectral Index
0
5
10
15
0 5 10 15
Observed LAI
Pre
dic
ted
LA
I
Corn
Soybeans
SoybeanTM1 0.867TM2 1.070TM3 0.240TM4 0.154TM5 -1.496TM7 0.399
CornTM1 -1.770TM2 0.268TM3 -0.480TM4 0.491TM5 1.633TM7 -0.703
ETM+ band 3
ETM+ band 3
ET
M+
band 4
ET
M+
band 5
ET
M+
band 5
NOBS57 % accurate(cross validation)
Spectral Index
0
4
8
12
0 4 8 12
Predicted LAI
Obs
erv
ed
LA
I
ETM+ band 4r = 0.422
7
0
2.5
3.0
3.5
4.0
4.5
0 2 4 6 8 10 12
LAI
TM
1 R
efle
ctan
ce (
%)
3.0
3.5
4.0
4.5
5.0
5.5
0 2 4 6 8 10 12
LAI
TM
2 R
efle
ctan
ce (
%)
3.0
3.5
4.0
4.5
5.0
0 2 4 6 8 10 12
LAI
TM
3 R
efle
ctan
ce (
%)
14
16
18
20
22
24
26
28
0 2 4 6 8 10 12
LAI
TM
4 R
efle
ctan
ce (
%)
8
10
12
14
16
18
20
22
0 2 4 6 8 10 12
LAI
TM
5 R
efle
ctan
ce (
%)
5
6
7
8
9
10
11
12
0 2 4 6 8 10 12
LAI
TM
7 R
efle
ctan
ce (
%)
0.60
0.65
0.70
0.75
0.80
0 2 4 6 8 10 12
LAI
ND
VI
-3
-2
-1
0
1
2
3
0 2 4 6 8 10 12
LAI
Sp
ectr
al In
dex
TM1 -0.086TM2 0.108TM3 -0.256TM4 -0.102TM5 -0.221TM7 1.466
Vegetation Cover Component Characterization System (3CS):
• Quantitative measurements of cover proportions• Basic building blocks for variety of classification systems• Improved LAI mapping?
Ground Cover - NormalizedPlot 2
45%
5%8%
11%
7%
16%
8% 0%
Moss
Lichen
Herb
Shrub
Litter
Tree Regen
CWD
Water
Ground Data - NormalizedPlot 4
1%
34%
19%
6%
11%
10%4%
15%
Moss
Lichen
Herb
Shrub
Litter
Tree Regen
CWD
Water
Plot 4 Canopy Cover
18%
3%
7%
72%
Conifer
Hardwood
Snag
Sky
Plot 2 Canopy Cover
52%
2%
3%
43%Conifer
Hardwood
Snag
Sky
sphagnum
feathermoss
n=48
All Plots Moss Lichen Herb Shrub Litter Tree Dead Water Conifer Hardwood DeadMoss 1.000Lichen -0.041 1.000Herb -0.334 -0.197 1.000Shrub -0.296 -0.045 -0.031 1.000Litter 0.102 -0.016 -0.003 -0.049 1.000Tree Regen. -0.174 -0.144 -0.323 -0.275 -0.229 1.000Dead Wood -0.101 -0.135 -0.282 -0.176 -0.149 0.008 1.000Water -0.179 -0.118 0.048 -0.104 0.063 -0.119 0.115 1.000Confier Canopy 0.343 0.011 -0.238 -0.214 -0.108 0.117 0.144 -0.176 1.000Hardwood Canopy -0.043 0.019 0.117 -0.003 0.101 -0.050 -0.099 -0.057 -0.200 1.000Dead Canopy -0.055 -0.045 -0.011 -0.174 0.139 0.004 0.047 0.293 -0.163 -0.023 1.000
Plot 1Mean and Standard Deviation
-20
0
20
40
60
80
100
1
cove
rMoss
Lichen
Herb
Shrub
Litter
Tree Regen
CWD
Water
Unknown
Conifer
Hardwood
Snag
Plot 3Mean and Standard Deviation
-20
0
20
40
60
80
100
1
cove
r
Moss
Lichen
Herb
Shrub
Litter
Tree Regen
CWD
Water
Unknown
Conifer
Hardwood
Snag
Correlations
n=48
n=192
Meeting Our Land Cover Mapping NeedsAGRO• corn (class--label fields in-situ)• soybean (class--label fields in-situ)• other (classes--label clusters in-situ & HD imagery)
HARV• hardwood/conifer (relative proportions--from HD imagery)• other (classes--label clusters in-situ & HD imagery)
KONZ• grass (short/tall combined class--labels from plots & HD imagery)• forest (one class--labels from plots & HD imagery)• shrub (percent--from HD imagery calibrated with camera observations, plots)• other (classes--label clusters in-situ & HD imagery)
HD (high definition) imagery: ADAR, IKONOS, AVIRIS mission photos, MQUALS
NOBS• conifer/hardwood/standing dead (relative proportions--from camera observations, HD imagery)• “ground” cover (relative proportions--from camera observations, moss classes from ocular estimate)• other (classes--label clusters in-situ, camera observations, & HD imagery)
“ground” cover classes: moss, lichen, herbaceous, shrub, fine litter, tree regeneration, coarse wood debris, water
Leaf-off HARV
Capturing seasonalityWith ETM+ is important to both landcover and LAI mapping
Leaf-on
JulyApril September
HARV
KONZ
0
1
2
3
4
5
6
7
8
27-May-99 22-Jun-99 27-Jul-99 11-Sep-99
Sample Date
LA
ICorn No Till Corn Conventional Till
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0-1 2-3 4-5 6-7 8-9 10-11 12-13
LAI
Fra
ctio
n o
f O
bse
rvat
ion
s
Corn Soybeans
27-Jul-99
LAI0 - 1 1 - 2 2 - 3 3 - 4 4 - 5 5 - 6 6 - 7 7 - 8
Fra
ctio
n of
Obs
erva
tions
0.0
0.1
0.2
0.3
0.4
NO TILL CONV. TILL
Range of LAI for the 108 BigFoot Plots
LAI
0 - 1
1 - 2
2 - 3
3 - 4
4 - 5
5 - 6
6 - 7
7 - 8
Fra
ctio
n of
Obs
erva
tions
0.00
0.05
0.10
0.15
0.20
0.25
AVG. for 4 BOREAS tower plots = 4.2
27-Jul-99
Preliminary calculations
Preliminary calculations
Regression
Kriged residualsKriging
IGPB: Cropland
UMD: Cropland
Biome: Broadleaf Crops
Percent Tree Cover: 0
MODLand/BigFoot Comparisons
Land cover (e.g.,…)• aspatial: compare frequency distribution of translated site-specific classes with same from MODLand• spatially explicit: summaries of site-specific cover proportions within MODLand- labeled cells
LAI/fPAR (e.g.,…)• mean 1 km cell values vs. MODLand values• distributions of fine-grained values within MODLand cells
NPP (e.g.,…)• integrated 1 km cell values vs. MODLand values• distributions of fine-grained values within MODLand cells• spatially degrade land cover and LAI, repeat modeling, redo above NPP comparisons• informationally degrade land cover, repeat modeling at fine grain, redo comparisons