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The Long and Winding Road to MODIS Data

The Long and Winding Road to MODIS Data. MODIS Land Products. MODIS Land Products – Quick review MODIS Land Products Web Sites – Where to get specifics on land products. MODIS Land Products. Radiation Budget Variables Surface Reflectances Land Surface Temperature (LST) and Emissivity

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The Long and Winding Road to MODIS Data

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  1. The Long and Winding Road to MODIS Data

  2. MODIS Land Products • MODIS Land Products – Quick review • MODIS Land Products Web Sites – • Where to get specifics on land products

  3. MODIS Land Products Radiation Budget Variables Surface Reflectances Land Surface Temperature (LST) and Emissivity Snow and Ice Cover Bi-directional Reflection (BRDF) and Albedo Land Cover Characteristics Fire and Thermal Anomalies Land Cover Vegetation Cover Conversion Vegetation Continuous Fields At-Launch Land Cover (derived from AVHRR) Ecosystem Variables Vegetation Indices (NDVI & EVI) Leaf Area Index (LAI) and Fraction Photosynthetically Active Radiation (FPAR) Vegetation Production, Net Primary Productivity (NPP)

  4. MODIS Land Products Available Resolutions note: not all products are currently available Product Spatial Resolution Temporal Resolution (MOD09) Land Surface Reflectance 500m 8 day composite 7 band product (MOD10) Snow Cover 500m daily, 8-day, monthly (MOD12) Land Cover Type/Change 1 km at-launch, quarterly (MOD13) Vegetation Indices 250m*, 500m, 1km 16-day, monthly (MOD15) LAI/FPAR 1km 8-day (MOD17) Vegetation Productivity 1km 8-day

  5. http://modarch.gsfc.nasa.gov Land

  6. Algorithm Technical Basis Document PI Web Site

  7. PI Web Sites LOOK FOR “User’s Guide”

  8. The MODIS Web Organigram EOS DataGateway Land Validation Home Site Direct to PI Websites

  9. MODIS Land Products • MODIS Data Processing • What’s up with L1, L2, L3, L4 Data ??

  10. MODIS Land Products The amount of processing performed by NASA for MODIS Land Application Products has never been applied for publicly distributed data.

  11. Level 1 - Level 4 Data Level 1B = Raw, Un-calibrated Swath Data (Scene), Not projected = Includes radiometric and calibration coefficients and parameters, but not applied Level 2 = Derived geophysical variables at the same resolution and location as the Level 1 source data Level 2G = Calibrated, IS Map Projection*, Tiled = Multiple Coincident Swaths (e.g. overlapping pixels) *Integerized Sinusoidal

  12. Level 1 - Level 4 Data Level 3 Data = Variables mapped on uniform space-time grid scales = “MODIS Land End User” = Usually composite data = Tiled, IS Projection, “Best” pixel selection (e.g. one value/pixel) Level 4 Data = Model output or results from analysis of lower level data = LAI/FPAR, PSN/NPP

  13. MODIS Land Tile StructureIntegerized Sinusoidal (IS) ProjectionReferenced by horizontal and vertical position h18v04 h19v04

  14. MODIS Land Tile StructureIntegerized Sinusoidal (IS) ProjectionReferenced by horizontal and vertical position IS Projection 1 km tile = 1200 x 1200 500 m tile = 2400 x 2400 250 m tile = 4800 x 4800

  15. MODIS Land Tiles for U.S.Lambert Azimuthal Equal Area

  16. Relationship of MODIS tiles to TM scenes

  17. MODIS Land Products • Obtaining MODIS (Terra, EOS) data

  18. Obtaining MODIS (Terra, EOS) data • Data are available from eight EOSDIS Distributed Active Archive Centers (DAACs), two affiliated datacenters, and a growing number of international partners. • Data centers process, archive, and/or distribute EOS and other NASA Earth Science data, and provide full support to users of these data. • Each data center holds and provides data pertaining to a particular Earth science discipline. • Collectively provide a physically distributed but logically integrated database.

  19. Distributed Active Archive Centers (DAACs)

  20. Single point of entry for multiple Distributed Active Archive Centers (DAACs) Data and documentation Wide variety of search parameters Location, Time period, Sensor, Product, Quality Can save queries for later use Good tutorial The Good NewsThe EOS Data Gateway(http://eos.nasa.gov/imswelcome)

  21. Granule ID MOD13A1.A2000161.h18v04.002.2000203002556.hdf MODXXX.Ayyyyddd.hxxvxx.vvv.yyyydddhhmmss.hdf MODXXX = product and level of product A = Terra (formally known as EOS-AM1) yyyyddd = year and year day (001 – 366) for the start of the granule hxxvxx = MODIS land tile vvv = a three-digit version number assigned by ECS yyyydddhhmmss = 4 digit year, 3 digit day, hr, min, and sec of the time (UTC)at which the granule is processed.

  22. HDFEOS File Formats Integerized Sinusiodal Projection The BAD News

  23. MODIS Land Tile StructureIntegerized Sinusoidal (IS) Projectionapprox. 10  x 10  (1200 x 1200, 1km tile) No common RS/GIS software supports this projection (yet). We will work with software developed at NTSG (P. Thornton and J. Glassy)

  24. HDF Files HDF = Hierarchical Data Format Developed by the National Center for Supercomputing HDF = Features include platform independence, user extendibility, and embedded metadata for units, labels, and other descriptors. HDF = Standard data types include: multidimensional array, text, table, raster image, and palette (all packaged into 1 file). HDF = Structures of different resolutions can be stored in the same file.

  25. HDF-EOS Files HDFEOS = Standard HDF with ECS (EOSDIS Core System) conventions, data types, and metadata added. HDFEOS = ECS core metadata is essential for search services. HDFEOS = Read by any tool that processes standard HDF files, although HDFEOS geolocation and temporal information generally is not accessible.

  26. HDF-EOS Files Objects: Grids (Swaths and Points) Science Data Fields (SDS): 2D+ arrays Coded biophysical values (8 - 16 bit) Defined Projection Metadata QC Fields (for each grid) Per pixel quality codes Tile Level Metadata

  27. The Good News Many tools currently exist or are being developed that will read the hdfeos file format. Current Tools Hdflook Webwinds IDL/ENVI extensions NOESYS http://hdfeos.gsfc.nasa.gov/hdfeos/workshop.html http://www-loa.univ-lille1.fr/Hdflook/hdflook_gb.html http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/MODIS/index.html

  28. Data Flows 1) Search and download data in HDF format (EOS Data Gateway) 2) Extract data and metadata from HDF files (HDFLook, IDL/ENVI, future tools) 3) Project from Integerized Sinusoidal to lat/long or other supported projection (? Custom program, future tools) 4) Import raw binary rasters into GIS/RS package GIS/RS Package Arc/Info ArcView Imagine 5) Decode raster values into physical units 6) Tile or subset rasters

  29. And the Result !

  30. The metadata text file that is posted with the hdf file is generally meant for sophisticated queries of EOS data. The hdf file has embedded metadata that the “user” will generally find more meaningful. Read through tools that read hdfeos files. A little bit about Metadata MOD13A1.A2000161.h18v04.002.2000203002556.hdf.met

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