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MODIS Land ISIN Grid

MODIS Land ISIN Grid. MODIS Land Validation Workshop January 22, 2001 Robert Wolfe NASA GSFC Code 922, Raytheon ITSS MODIS Land Science Team Support Group. Land Product Characteristics. HDF-EOS Format Average size is about 70 MB. MODLAND Grids.

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MODIS Land ISIN Grid

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  1. MODIS Land ISIN Grid MODIS Land Validation Workshop January 22, 2001 Robert WolfeNASA GSFC Code 922, Raytheon ITSSMODIS Land Science Team Support Group

  2. Land Product Characteristics • HDF-EOS Format • Average size is about 70 MB

  3. 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.

  4. ISIN Grid Grid Cell Sizes: 30 arcsec (0.93 km) 15 arcsec (0.46 km) 7.5 arcsec (0.23 km) 10 degree Tiles

  5. History • Selected 5 years ago for overall MODIS grid • Compromise between land, ocean and atmosphere requirements • First recommended for use for data analysis by Rossow & Garder (1984) • Used in the past by: WMO, International Satellite Cloud Climatology Project (ISCCP), Oceans Pathfinder and SeaWiFS project, SSM/I and POLDER

  6. Example: 5 Degree Grid

  7. Normal vs. Integerized Grid • Normal grid has partially filled cells along edges of grid Full Cell Partial Cell Integerized Grid Normal Grid

  8. Brick-like Shifts Before Projection Before Projection • Brick-like shifts between rows After Projection After Projection 250 m Normal Grid Integerized Grid

  9. Advantages/Disadvantages • Advantages: • Global • Non-interrupted • Almost equal area (not quite near poles) • Can be aligned at any meridian by sliding rows • Continuous across end of rows • Disadvantages: • Not supported by most tools • Distorts shape of land areas • Difficult to nest multiple resolutions • Brick-like layout makes many geometric operations difficult: non-horizontal gradients, resampling, frequency filtering, etc. • No heritage in Land community

  10. Tools • Reprojection tool developed by USGS EDC and South Dakota School of Mines • Converts MODIS L3 products to other grids (also converts format) • Currently beta testing by MODIS Science Team • Release expected on Feb. 28 • General Cartographic Transformation Package (GCTP) • Updated by ECS to support ISIN and part of SDP toolkit • USGS/EDC adding ISIN to official version • Used by many vendors – precursor for support • Other vendor support • Seems to coming along, but not as quickly as we would like

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