Flux–Model–MODISFlux–Model–MODISEvaluationEvaluation

Dick Olson, Tom Boden,Bob Cook, Lisa Olsen,

Steve Margle, many othersOak Ridge National Laboratory*

Oak Ridge, Tennessee, USA

*Managed by the University of Tennessee-Battelle LLC under contract DE-AC05-00OR22725 with the U.S. Department of Energy.

EMDI 3 Working GroupApril 2002

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Components NEE – eddy covariance flux towers NPP – ecosystem field measurements MODIS – EOS Validation program Modeled NPP – ad hoc participation EMDI 3 Prototype exercise:

– 3 sites (history of timely data processing)° Harvard Forest – Bill Monger° UMBS – Peter Curtis° Metolius – Bev Law

– Scaling issues: ° NEE vs NPP° >1 km2 vs point° 0.5 hr vs daily

– Comparison statistics: correlations?

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Flux-Model-MODIS Comparison

Fluxes: 17 towers – Micrometeorology posted near real-time

– Gap-filled flux estimates posted annually Models: 5 models participating (open to others)

– Common site characteristics–model driver data MODIS: 7 products for 52 sites (8-day composites)

– Surface Temperature, Vegetation Index, LAI, fPAR, Photosynthesis (8-day and annual), Surface Reflectance, BRDF

– Sites include Core Validation Sites, Flux Tower Sites, BigFoot Sites, Real Time Validation activity, and LAINet Sites

Format is 7 km x 7 km cutouts in ISIN projection in ASCII files

Re-projecting MODIS DataPark Falls, WI

UTMUTMIntegerized SinusoidalIntegerized Sinusoidal

MODIS sinusoidalMODIS sinusoidal

Harvard Forest, ISIN, all pixels in 5x5 km area: LAI, fPAR, EVI, PSN

Harvard Forest, ISIN, good pixels in 3x3 km area: LAI, fPAR, EVI, PSN

Metolius •PSN product•All pixels in 3x3 area Two distinct setsof PSN values, may bedue to different land cover types

Metolius •PSN product•All pixels in 3x3 area Two distinct setsof PSN values, may bedue to different land cover types

Heterogeneity in MODIS

pixels near tower

Walker Branch•Pixels with LAI and PSN•All pixels in 5x5km area• MODIS landcover: broadleaf crops (8 pixels) broadleaf forest (8 pixels) needleleaf forest (9 pixels)

No differences between types, may be due to mixed pixels

Walker Branch•Pixels with LAI and PSN•All pixels in 5x5km area• MODIS landcover: broadleaf crops (8 pixels) broadleaf forest (8 pixels) needleleaf forest (9 pixels)

No differences between types, may be due to mixed pixels

Lack of Heterogeneity

in MODIS pixels near tower

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MODIS Products- Walker Branch

PSN

fPAR

LAIEVI

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MODIS Products - Harvard Forest

WB Flux 1995-98

Lotec NEP 2000-01

MODIS PSN 2001

Lotec / MODIS

WB Flux 1995-98

BGC NEP 2000-01

MODIS PSN 2001

BGC / MODIS

HF Flux 1992-99

MODIS PSN 2001

Lotec NEP 2000-2001

Lotec / MODIS

HF Flux 1992-99

MODIS PSN 2001

BGC NEP 2000-2001

BGC / MODIS

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Measured Relative LAI - WB

Time to 50% LAIMax as Function of

Average Spring Temp.

Time to 50% LAIMax as Function of

Degree GrowingDays

UMBS, ISIN, good pixels in 3x3 km area: LAI, fPAR, EVI, PSN

Metolius, ISIN, good pixels in 3x3 km area: LAI, fPAR, EVI, PSN

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Comparison of Flux-Model-MODIS

Walker Branch– MODIS LAI compares favorably to 10-yrs LAI field

measurements– Springtime pattern is about the same

° Lotec is later

° MODIS PSN is earlier

– Lotec model NEP is about half measured NEE

Harvard Forest– Springtime pattern is about the same

° Lotec is later

° MODIS PSN is earlier

– Lotec model NEP is about same as measured NEE