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Flux–Model–MODIS Evaluation

Flux–Model–MODIS Evaluation. EMDI 3 Working Group April 2002. Dick Olson, Tom Boden, Bob Cook, Lisa Olsen, Steve Margle, many others Oak Ridge National Laboratory* Oak Ridge, Tennessee, USA. *Managed by the University of Tennessee-Battelle LLC

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Flux–Model–MODIS Evaluation

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  1. Flux–Model–MODISEvaluation EMDI 3 Working Group April 2002 Dick Olson, Tom Boden, Bob Cook, Lisa Olsen, Steve Margle, many others Oak 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.

  2. 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?

  3. 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

  4. Re-projecting MODIS DataPark Falls, WI MODIS sinusoidal UTM Integerized Sinusoidal

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

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

  7. Heterogeneity in MODIS pixels near tower • Metolius • PSN product • All pixels in 3x3 area • Two distinct sets • of PSN values, may be • due to different land • cover types

  8. Lack of 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

  9. MODIS Products- Walker Branch PSN fPAR LAI EVI

  10. MODIS Products - Harvard Forest

  11. MODIS PSN 2001 Lotec NEP 2000-01 Lotec / MODIS WB Flux 1995-98

  12. MODIS PSN 2001 BGC NEP 2000-01 BGC / MODIS WB Flux 1995-98

  13. HF Flux 1992-99 MODIS PSN 2001 Lotec NEP 2000-2001 Lotec / MODIS

  14. HF Flux 1992-99 MODIS PSN 2001 BGC NEP 2000-2001 BGC / MODIS

  15. Measured Relative LAI - WB Time to 50% LAI Max as Function of Average Spring Temp. Time to 50% LAI Max as Function of Degree Growing Days

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

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

  18. 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

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