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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. MODIS Land Science Team Products. Goals :

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MODIS Land and HDF-EOS

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  1. MODIS Land and HDF-EOS HDF-EOS Workshop Presentation September 20, 2000 Robert WolfeNASA GSFC Code 922, Raytheon ITSSMODIS Land Science Team Support

  2. 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 developpeer-reviewed product generation algorithms (10 Principal Investigators, lead: Chris Justice, UVA)

  3. MODIS Land Product Overview (1/3) • Radiation Budget Variables • Surface Reflectance • Surface Temperature and Emissivity • Snow and Ice Cover • BRDF and Albedo

  4. 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)

  5. MODIS Land Product Overview (3/3) • Land Cover Characteristics • Fire and Thermal Anomalies • Land Cover • Vegetation Cover Conversion

  6. MODIS Production and Distribution • 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

  7. 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.

  8. ISIN Grid

  9. HDF-EOS Usage (1/2) • Both swath and grid format • 2d, 3d and some 4d SDS arrays • Global and SDS attributes

  10. 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.

  11. 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

  12. 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

  13. 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

  14. For More Information URL: http://modis.gsfc.nasa.gov/

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