MODIS Albedo Subsets for Selected Field sites

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MODIS Albedo Subsets for Selected Field sites

• Bob Cook, Steve Margle,
• Susan Holladay, and Lisa Olsen
• Oak Ridge National Laboratory
• Oak Ridge, Tennessee, USA
• 2nd CEOS/WGCV/
• Land Product Validation (LPV)
• Workshop on Albedo Products
• Vienna, Austria
• April 2829, 2005

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Collaborators / Contributors

• Jeff Morrisette, Nazmi El Saleous
  (NASA GSFC)
• Crystal Schaaf and Ranga Myneni (Boston
  University)
• Steve Running and Faith Ann Heinsch (University
  of Montana)
• Giri Palanisamy and Tammy Beaty (ORNL)

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Goal

• To provide subsets of MODIS Land Products in a
  format and spatial scale useful to field
  investigators
• Facilitates interaction between remote sensing
  scientists and field investigators
• Easily compare satellite data with ground-based
  measurements
• Used for validation of MODIS Land Products

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MODIS ASCII Subsets

• Subsets of Terra and Aqua MODIS Land Products for
  280 sites worldwide (field sites or flux towers)
  in an easy-to-use ASCII format
• 7 km x 7 km centered on flux tower or field sites
• Two annual products, four 8-day products, two
  16-day product, and calculated albedo, from 2000
  to present

MODIS Products
Surface Reflectance
Surface Temperature
Land Cover
NDVI / EVI
LAI / fPAR
Net Photosynthesis
Annual NPP
Albedo
Reflectance BRDF Adjusted
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MODIS Subset Sites Albedo Related

• BSRN Sites
• Toravere, Estonia
• Tateno, Japan
• Payerne, Switzerland
• Barrow, Alaska
• S. Great Plains, Oklahoma
• Fort Peck, Montana
• Bondville, Illinois
• Boulder Colorado
• Penn State, Pennsylvania
• Goodwin Creek, Mississippi

• Other Sites
• Guzelyayla , Turkey
• Ovacik, Turkey
• Arabia1, Saudi Arabia
• Ngotto Forest, Cent.African Rep.
• RAC, Central African Republic
• Nile Delta, Eqypt
• Novara, Italy
• Po Valley, Italy
• Hapex-Sahel, Niger
• Lamto, Cote D'Ivoire
• Nigeria, Nigeria
• Suchow, China
• Mammoth Mountain, CA, USA
• ARS-NE PLRC, PA, USA
• Pleasant Plains, IL, USA
• Allegheny Nat. Forest, PA, USA

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MODIS Subset Sites Albedo Related

• Greenland (Denmark)
• Crawford_Point 2
• Crawford_Point 1
• DYE-2
• JAR1
• JAR2
• Saddle
• South Dome
• SM2
• Summit
• ETH/CU Swiss Camp

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MODIS ASCII Subset Web Site http//www.modis.orn
l.gov/modis/
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User-selects optical depth and szn
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Albedo Calculated from MODIS BRDF Product

• MODIS BRDF Albedo Model Product (MOD43B1)
  contains parameters for calculating albedo for
  visible, near-IR, and shortwave
• Black Sky albedo
• ƒ(parm 1, parm 2, parm 3, szn)
• White Sky albedo
• ƒ(parm 1, parm 2, parm 3)
• Blue Sky albedo
• ƒ(white sky albedo, black sky albedo, optical
  thickness)

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Quality Assurance

• Provide quality assurance data layers
• Including snow

Toravere BSRN, Estonia, January 1, 2005
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Information at bottom of Grid Display
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MODIS ASCII Subsets Web-Based Data
Visualization GridToravere BSRN, Estonia
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MODIS ASCII Subsets Web-Based Data
Visualization Time Series Toravere BSRN,
Estonia
Visible Broadband Blue Sky Albedo (fraction)
Pixel Values
Mean Value of Pixels
Percent of Pixels that met QC Criteria
Year
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Additional data compiled for albedo validation

• Broadband Diffuse Irradiance Climatology for the
  selected MODIS ASCII Subset Sites (n 254)
• Based on AERONET data
• Prepared by Privette and Hoffman
• Available from ORNL
• ftp//daac.ornl.gov/data/eos_land_val/albedo/
• Subsets of Optical Depth (MOD04) for 24 sites
• Summit, ETH_CU_Swiss_Camp, Tateno,
  Fort_Peck_Montana, Payerne, BARC, Barton_Bendish,
  BOREAS_BERMS, Jornada, Lake_Tahoe, Mandalgobi,
  Metolius_Old_Pine, Tapajos, North_Temperate_Lakes
• Available from NASA GSFC
• ftp//windhoek.nascom.nasa.gov/private/ichoku/MAPS
  S/

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Future Plans MODIS ASCII Subsets

• Continue to offer subsets of Collection 4 MODIS
  Land Products from Terra and Aqua
• Add Continuous Vegetation Field subsets when
  available
• Evaluate current sites and seek additional sites
  for future processing / reprocessing (e.g.,
  Collection 5 in late-2005)
• To have your field site added to the MODIS Subset
  Collection, we need the geographic coordinates
  (to four significant decimal places 10s of
  meters) and your commitment to share data

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Need site location good to 0.0001 degree
1 minute uncertainty yields /- 2 km or 25 pixels
Uncertainty of /- 1 minute
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Future Plans MODIS Subset Pilot

• Tool to enable on-the-fly subsetting and
  visualization
• For any area in North America up to 200 x 200 km
• For pre-selected sites for the rest of the world
• Incorporate albedo calculation from MOD43B
  parameters

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MODIS ASCII Subsets Web Site www.modis.ornl.g
ov/modis/
Contact Bob Cook ORNL DAAC cookrb_at_ornl.gov