ISCCP GTE/TRACE-A DATA FORMATS

DX grid

This is a 0.5 degree square latitude/longitude grid. The grid is 120 x 100 (longitude x latitude) and has a total of 12000 cells. Longitude varies first, and begins at 80W and proceeds eastward to 20W in increments of 0.5 degrees. Latitude begins at the 40S and proceeds northward to 10N in increments of 0.5 degrees.

D1 grid

This is a 2.5 degree square latitude/longitude grid. The grid is 24 x 20 (longitude x latitude) and has a total of 480 cells. Longitude varies first, and begins at 80W and proceeds eastward to 20W in increments of 2.5 degrees. Latitude begins at 40S and proceeds northward to 10N 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: 1,920 bytes
• D1 grid, Scaled integer: 1,920 bytes
• D1 grid, ASCII text: 4,800 bytes
• DX grid, IEEE floating point: 48,000 bytes
• DX grid, Scaled integer: 48,000 bytes
• DX grid, ASCII text: 120,000 bytes

TRACE-A Field Campaign