MODIS Land and HDF-EOS

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Source: http://hdfeos.org/workshops/ws04/presentations/Wolfe/Wolfe.ppt

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MODIS Land and HDF-EOS

  1. 1. MODIS Land and HDF-EOS MODIS Land and HDF-EOS HDF-EOS Workshop Presentation September 20, 2000 Robert Wolfe NASA GSFC Code 922, Raytheon ITSS MODIS Land Science Team Support
  2. 2. MODIS Land Science Team Products MODIS Land Science Team Products • Goals : – operationally produce terrestrial remotely sensed products that may be used by expert and non-expert community – establish a 10 year record that has continuity with precursor systems, e.g., AVHRR, and the future NPP and NPOESS VIIRS missions • The MODIS products were developed primarily to serve the global change research community (MODIS has global, near daily coverage) and have many other potential applications • The MODIS Land Science team was completively selected to develop peer-reviewed product generation algorithms (10 Principal Investigators, lead: Chris Justice, UVA) HDF-EOS 2
  3. 3. MODIS Land Product Overview (1/3) MODIS Land Product Overview (1/3) • Radiation Budget Variables – Surface Reflectance – Surface Temperature and Emissivity – Snow and Ice Cover – BRDF and Albedo HDF-EOS 3
  4. 4. MODIS Land Product Overview (2/3) MODIS Land Product Overview (2/3) • Ecosystem Variables – Vegetation Indices – Leaf Area Index (LAI) and Fractional Photosynthetically Active Radiation (FPAR) – Vegetation Production – Net Primary Productivity (NPP) HDF-EOS 4
  5. 5. MODIS Land Product Overview (3/3) MODIS Land Product Overview (3/3) • Land Cover Characteristics • Fire and Thermal Anomalies • Land Cover • Vegetation Cover Conversion HDF-EOS 5
  6. 6. MODIS Production and Distribution MODIS Production and Distribution Level 0 Instrument Data Level 1, Ocean and Atmos. Products GSFC DAAC • User Community MODIS Land production commenced 02/26/2000 • Product checkout is underway, driven by instrument calibration, geolocation, algorithm code stability and data dependencies • Land products Beta release from the DAACs began 08/04/2000 • Current products are for evaluation purposes Ocean and Atmosphere Products Level 1 Products MODAPS Land Snow and Ice Cover Products Land Non-cryospheric Products NSIDC DAAC EDC DAAC User Community HDF-EOS 6
  7. 7. MODLAND Grids MODLAND Grids • • Fine resolution grids for the L2G, 3 and 4 products are based on two map projections: – Integerized Sinusoidal Grid (ISIN) – Lambert Azimuthal Equal-Area (LAEA) (polar grids) – Almost all of the fine resolution products will be made in the ISIN • Exception: Sea-ice products are made in the in the LAEA projection with the grid centered at the north and south poles (EASI Grid implementation) – Grid cell size varies by product and is either (approx.) 0.25 km, 0.5 km or 1 km – actual size depends on the projection – Each grid is broken into non-overlapping tiles which cover approx. 10 x 10 deg. area Coarse resolution global Climate Modeling Grid (CMG) products are made in a geographic projection with grid cell sizes of 0.25 or 0.5 deg. HDF-EOS 7
  8. 8. ISIN Grid ISIN Grid HDF-EOS 8
  9. 9. HDF-EOS Usage (1/2) HDF-EOS Usage (1/2) • Both swath and grid format Type Interim Archive L2 Swath 1 5 ISIN 8 30 LAEA (Polar) 3 2 CMG (Geog.) 0 19 Total 12 56 Total 6 38 5 19 68 • 2d, 3d and some 4d SDS arrays • Global and SDS attributes HDF-EOS 9
  10. 10. HDF-EOS Usage (2/2) HDF-EOS Usage (2/2) • Subsetting/mosaicing – Collaborated with UAH in HEW development – Used operationally for 24 Core Validation Sites and planned for Fluxnet sites • Resampler – Collaborating with EDC/SDSM&T to develop resampler – Could be used for DAAC services and end user – L2 and L3 regridding support • MODLAND developed QA Tools for Team – Extensions to IDL/ENVI and Unix command line – Bit field handling, etc. HDF-EOS 10
  11. 11. Good things about HDF/HDF-EOS Good things about HDF/HDF-EOS • Made collaboration easier between geographically distant scientists/developers – Self documenting file format allows easy exchange of information between processes • Standard method of representing geolocation HDF-EOS 11
  12. 12. HDF-EOS Gripes (1/2) HDF-EOS Gripes (1/2) • Toolkit doesn't support all HDF objects and access types – Hybrid HDF and HDF-EOS approach used to create/read files – Also need to use SDP toolkit to manipulate metadata • Subsettting on 3/4 dimensional arrays is difficult – ex. take bands 3 & 5 from 7 bands array (3d) and store in 2 band array (3d) – downstream users need to which 2 bands were selected • HDF Specific – No convention for support of bit fields – Performance depends on layout in 3 or 4 dimensional arrays HDF-EOS 12
  13. 13. HDF-EOS Gripes (2/2) HDF-EOS Gripes (2/2) • Swath format does not support external geolocation files – workaround -- two geolocation arrays: one accurate 1 km external file and one 5 km internal array – 5 km array takes up more space and not as accurate • Vendor support growing but still lacking HDF-EOS 13
  14. 14. For More Information For More Information URL: http://modis.gsfc.nasa.gov/ HDF-EOS 14

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