IMAPP MODIS Direct Broadcast Ice Mask
  and Ice Concentration Product Description
  -------------------------------------------

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  The IMAPP Ice Mask and Ice Concentration software produces retrievals 
  of the percentage of ice cover on water bodies within a 1 km
  MODIS pixel, as well as an Ice Mask that includes whether ice
  was found using wavelengths in the visible wavelength spectrum or 
  infrared wavelengths.  The output is at 1 km resolution.  The 
  inputs are the MODIS 1 km resolution L1B file, the MODIS Geolocation
  file and the and the MODIS 1 km Cloud Mask file. The software 
  was created by Yinhui Liu, University of Wisconsin-Madison, Space
  Science and Engineering Center, and integrated into
  IMAPP by Kathleen Strabala, kathy.strabala@ssec.wisc.edu.

  For a description of the algorithm, please see:

  Liu Y., and J.R. Key, 2010: Algorithm theoretical basis document 
    for ABI ice cover and concentration. NOAA NESDIS center for 
    satellite applications and research.

  Output for this product is a flat binary file and an HDF4 file.

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Binary Output File
------------------
  The software produces output files in binary format (.icecon.bin 
  extension) which consist of 4 bands of 4 byte data and no
  scaling at 1 km resolution.  The data is band sequential, meaning
  each band contains a complete swath of data prior to the beginning of the
  next band. The size of the file will depend upon the size of the 
  pass that is being processed (1354 x number_of_lines x 4 bands  x 4 bytes).

   Example file name:  t1.11110.0246.icecon.bin
   4 - 4 byte fields
   1). Latitude  4 byte float
   2). Longitude  4 byte float
   3). Ice Mask Long Integer (4 bytes)
        Values:
         -2: water, -1: land, 0: cloud over water, 1: visible technique 
         found ice, 2: infrared technique found ice, -999: missing
   4). Ice Concentration  4 byte float
         Values 0.-100. percent.  Missing values -999.

   Scale factor:  1.0
   1 km pixel resolution

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HDF4 OUTPUT FILE
------------------
  The HDF4 output file (*icecon.hdf) contains 4 SDS arrays.  
  Latitude, Longitude at 5km resolution, Ice Mask at 1 km resolution
  and Ice Concentration in percent (%) at 1 km resolution.

  The Latitude and Longitude arrays are stored as 4 byte float values
  at 5 km resolution.

  The Ice_Mask SDS is stored as a long integer (4 byte) at 1 km.

  The Ice_Concentration is stored a 4 byte float value  at 1 km.
  
  Example filename:  a1.08055.1850.icecon.hdf


 (Example ncdump -h of an IMAPP MODIS Ice Concentration HDF4 file)

netcdf a1.08055.1850.icecon {

dimensions:
        Cell_Along_Swath_5km = 406 ;
        Cell_Across_Swath_5km = 271 ;
        Cell_Along_Swath_1km = 2030 ;
        Cell_Across_Swath_1km = 1354 ;

variables:
        float Latitude(Cell_Along_Swath_5km, Cell_Across_Swath_5km) ;
                Latitude:_FillValue = -999.98999f ;
        float Longitude(Cell_Along_Swath_5km, Cell_Across_Swath_5km) ;
                Longitude:_FillValue = -999.98999f ;
        long Ice_Mask(Cell_Along_Swath_1km, Cell_Across_Swath_1km) ;
                Ice_Mask:units = "None" ;
                Ice_Mask:scale_factor = 1. ;
                Ice_Mask:add_offset = 0. ;
                Ice_Mask:valid_range = -2, 2 ;
                Ice_Mask:_FillValue = -999 ;
        float Ice_Concentration(Cell_Along_Swath_1km, Cell_Across_Swath_1km) ;
                Ice_Concentration:units = "%" ;
                Ice_Concentration:scale_factor = 1. ;
                Ice_Concentration:add_offset = 0. ;
                Ice_Concentration:valid_range = 0.f, 100.f ;
                Ice_Concentration:_FillValue = -999.f ;
}