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ISCCP ASTEX Data Formats

DX data is available for downloading on a 0.5 degree square grid, and D1 data is available on a 2.5 degree square grid. Both DX and D1 are available in either IEEE floating point, scaled integer, or ASCII text format.

DX grid
This is a 0.5 degree square latitude/longitude grid. The grid is 100 x 70 (longitude x latitude) and has a total of 7000 cells. Longitude varies first, and begins at 40W and proceeds eastward to 10E in increments of 0.5 degrees. Latitude begins at 10N and proceeds northward to 45N in increments of 0.5 degrees.
D1 grid
This is a 2.5 degree square latitude/longitude grid. The grid is 20 x 14 (longitude x latitude) and has a total of 280 cells. Longitude varies first, and begins at 40W and proceeds eastward to 10E in increments of 2.5 degrees. Latitude begins at 10N and proceeds northward to 45N in increments of 2.5 degrees.Special data values
There are two special values that may be present in the data set:
  • -1000.0 indicates "no data"
  • -500.0 indicates "clear" for those variables that represent cloud parameters
IEEE floating point format
Data is written using the IEEE standard for floating-point representation.
Scaled integer format
Data is written as scaled integers. Scale factors used are:
  • Cloud Amounts: 10
  • Cloud Top Pressures: 1
  • Cloud Top Temperatures: 10
  • Cloud Optical Depths: 100
  • Surface Temperatures: 10
  • Surface Reflectances: 100
  • Cloud/Clear Flags: 1
  • Radiance Counts: 1
ASCII text format
Data is written 80 characters per record. Each record contains values for 8 grid boxes, each with a field width of 10 characters. The precision is 3 decimal places.
File sizes
  • D1 grid, IEEE floating point: 1,120 bytes
  • D1 grid, Scaled integer: 1,120 bytes
  • D1 grid, ASCII text: 2,800 bytes
  • DX grid, IEEE floating point: 28,000 bytes
  • DX grid, Scaled integer: 28,000 bytes
  • DX grid, ASCII text: 70,000 bytes

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