1

The CEOS Leaf Area Index Inter-comparison as aprototype activity

Global Vegetation Workshop, University of Montana

2

Global Vegetation Workshop, University of Montana

Outline

1)1) Background: CEOSBackground: CEOS

2)2) Global validation and inter-Global validation and inter-comparisoncomparison approachapproach

3)3) Inter-Inter-comparisoncomparison of: GLOBCARBON, CYCLOPES, MODIS, of: GLOBCARBON, CYCLOPES, MODIS,

ECOCLIMAP and CCRS global ECOCLIMAP and CCRS global datasetsdatasets

4)4) ConclusionsConclusions

3

Background (1/3):Leaf Area Index Product

• Leaf Area Index:

• Key surface characteristic for land surface modeling

• Essential Climate Variable as defined by GCOS

• LAI definition: half the total developed area of leaves per unit ground horizontal

surface area (Chen and Black, 1992)

Global Vegetation Workshop, University of Montana

4

Global Vegetation Workshop, University of Montana

Background (2/3)Rationale for validation and inter-comparison of LAI

5

Global Vegetation Workshop, University of Montana

• CEOS/WGCV subgroup created in 1999 to

Background (3/3)Land Product Validation group

6

Method (1/5)The BELMANIP Global Network of Sites

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CC C

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-180 -150 -120 -90 -60 -30 0 30 60 90 120 150

90

60

30

0

-30

-60

Bare Water DBF ENF EBF Crops Grass

•representative sampling of global land surface types

•about 400 sites from several networks: direct validation sites (D: BIGFOOT, VALERI… )

AERONET (A), FLUXNET (F)…

Global Vegetation Workshop, University of Montana

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0 5 10 15 20 25 30 35

-60

-40

-20

0

20

40

60

component fraction (%)

latitude (°)

GrassCropsEvergreen broadleafConifersDeciduous BroadleafBare surface

GrassCropsEvergreen broadleafEvergreen NeedleleafDeciduous BroadleafBare surface

0 5 10 15 20 25 30 35

-60

-40

-20

0

20

40

60

component fraction (%)

latitude (°)

GrassCropsEvergreen broadleafEvergreen NeedleleafDeciduous BroadleafBare surface

Global surface type distribution BELMANIP surface type distribution

76 sites were added to FLUXNET, AERONET and Direct Validation sites to

better sample latitude, longitude and surface types (grass, bare surface,

evergreen broadleaf forest)

ECOCLIMAP global classification (Masson et al, 2003)

Method (2/5)The BELMANIP Global Network of sites

Global Vegetation Workshop, University of Montana

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Global Vegetation Workshop, University of Montana

Method (3/5): Direct Validation approach

Accuracy Assessment

LAI Field

data

High resolution

imagery

High resolution

LAI map Moderate resolution

LAI

Transfer

function

Aggregate&

Relate

9

Global Vegetation Workshop, University of Montana

Method (4/5)High Spatial Resolution LAI Map Database

10

Global Vegetation Workshop, University of Montana

Method (5/5): LAI inter-comparison approach

Projection&

resampling

Extractionover

BELMANIP sites

Inter-comparison metrics:Map of difference

Global histogram

Transect

Product/product scatter plot

11

Global Vegetation Workshop, University of Montana

Results: Products investigated

no

yes

yes

yes

yes

Total

LAI

yes

yes

yes

no

yes

Woody

correction

yesClimatology from global

climate distribution and

NOAA AVHRR time series

ECOCLIMAP

(Masson, et al.,2003)

yesSemi-empirical (SR, ISR,

BRDF correction, land use

specific retrieval, temporal

filter)

CCRS

(Fernandes, et al., 2003)

yesRadiative Transfer Inversion

by LUT

MODIS

(Myneni et al., 2002)

noRadiative Transfer Inversion

by neural network

CYCLOPES

yesSemi-empirical relationship

(SR,RSR VI, BRDF

Correction and temporal

filter)

GLOBCARBON

(Plummer et al)

Clumping

correction

AlgorithmProduct

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Global Vegetation Workshop, University of Montana

Results: Global maps (Aug 2002)

13

0 2 4 6 80

0.2

0.4

0.6

0.8

1

Cumulative frequency (

LAI values

01/2002

Global Vegetation Workshop, University of Montana

Results: Global histogram

0 2 4 6 80

0.2

0.4

0.6

0.8

1

Cumulative frequency (

LAI values

07/2002

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Global Vegetation Workshop, University of Montana

Results: Map of differences over CanadaJuly 2002

15

Global Vegetation Workshop, University of Montana

Results: Map of differences over Canada

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Global Vegetation Workshop, University of Montana

Results: Map of differences over CanadaJuly 2002

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Global Vegetation Workshop, University of Montana

Results:Transect over Africa (25˚ est)

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Global Vegetation Workshop, University of Montana

Results:Time series over crop sites

Jan Dec Jan Dec0

0.5

1

1.5

2

2.5

3

3.5

4Crops (Fundulea, Romania)

2002 2003month

LA

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Global Vegetation Workshop, University of Montana

Results: Time series over grassland

Jan Dec Jan Dec0

0.5

1

1.5

2

2.5

3

3.5

4Grass (Larzac, France)

2002 2003month

LAI

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Global Vegetation Workshop, University of Montana

Results: Time series over DBF

Jan Dec Jan Dec0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5Decid. Broad. For. (Larose2, Canada)

2002 2003month

LAI

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Global Vegetation Workshop, University of Montana

Results: Time series over ENF

Jan Dec Jan Dec0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5Ever. Needle. Forest (NOBS, Canada)

2002 2003month

LAI

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Global Vegetation Workshop, University of Montana

Results: Time series over ENF

Jan Dec Jan Dec0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5Ever. Needle. Forest (WatsonLake, Yukon, Canada)

2002 2003month

LAI

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Global Vegetation Workshop, University of Montana

Results: Time series over EBF

Jan Dec Jan Dec0

1

2

3

4

5

6

7

8Ever. Broad. Forest (TAPA, Brazil)

2002 2003month

LAI

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Global Vegetation Workshop, University of Montana

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7Crops(RMSE=0.941, R 2=0.61)

GLOBCARBON

MODIS

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7Crops(RMSE=1.23, R 2=0.35)

ECOCLIMAP

MODIS

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7Crops(RMSE=1.45, R 2=0.307)

ECOCLIMAP

GLOBCARBON

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7Crops(RMSE=0.827, R 2=0.674)

CYCLOPES

MODIS

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7Crops(RMSE=0.604, R 2=0.62)

CYCLOPES

GLOBCARBON

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7Crops(RMSE=1.32, R 2=0.485)

CYCLOPES

ECOCLIMAP

Scatter plot over the BELMANIP sites-class=crop

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Global Vegetation Workshop, University of Montana

Scatter plot over the BELMANIP sites-class=ENF

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=1.27, R 2=0.527

GLOBCARBON

MODIS

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=0.999, R 2=0.532

ECOCLIMAP

MODIS

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=1.38, R 2=0.527

ECOCLIMAP

GLOBCARBON

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=1.3, R 2=0.587

CYCLOPES

MODIS

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=1.27, R 2=0.553

CYCLOPES

GLOBCARBON

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=1.5, R 2=0.386

CYCLOPES

ECOCLIMAP

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Global Vegetation Workshop, University of Montana

Scatter plot over the BELMANIP sites-class=EBF

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=2.09, R 2=0.021

GLOBCARBON

MODIS

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=1.59, R 2=0.0389

ECOCLIMAP

MODIS

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=2.44, R 2=0.0579

ECOCLIMAP

GLOBCARBON

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=1.74, R 2=0.486

CYCLOPES

MODIS

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=2.33, R 2=0.167

CYCLOPES

ECOCLIMAP

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7RMSE=1.48, R 2=0.254

CYCLOPES

GLOBCARBON

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Global Vegetation Workshop, University of Montana

Direct validation: Product versus HR LAI Map

0 1 2 3 4 5 60

1

2

3

4

5

6

LAI map

MODIS

RMSE=1.4, R 2=0.566

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7

LAI map

GLOBCARBON

RMSE=1.5, R 2=0.411

0 1 2 3 4 5 60

1

2

3

4

5

6

LAI map

ECOCLIMAP

RMSE=1.37, R 2=0.459

0 1 2 3 4 5 60

1

2

3

4

5

6

LAI map

CYCLOPES

RMSE=0.888, R 2=0.7

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Global Vegetation Workshop, University of Montana

Results summary

++++++++++++++Seasonal

trends

++++++++++Magnitude

NA++++++++++In situ data

NA++++++++++++Spatial

gradient

NA++++++++++++global LAI

distribution

+++++++++++Missing data

CCRSCYCLGLOBCARMODISECOCLI

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Global Vegetation Workshop, University of Montana

Pending issues

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Global Vegetation Workshop, University of Montana

Concluding Remarks