Floating point refers to a three-part representation of a real number. The number is represented first by the sign, then the number itself, then the decimal position. Although 32-bit data can represent numbers to a much greater precision, the CoastWatch temperature data is only accurate to 1 decimal place. The greater precision allows actual data values to be incorporated into the raster grid, facilitating analysis and manipulation of the gridded data. Although the GRID format is not directly available through CoastWatch, ArcView contains utilities to convert binary raster data easily into the GRID format.
Grids are geographic data models representing information as an array of equally sized square cells.
Each grid cell has a value that corresponds to the feature or characteristic at that location, such as a soil type, vegetation class, or in this case, temperature. Values of each cell are stored in a database file that is connected to its geographic x, y location and can be queried using the Identify tool by clicking on any point on the map. ArcView GRID themes provide a much flexibility in adjusting both color and scaling of the legend used. In this example, two different color schemes with the same scaling are shown above, and two different scalings with the same color scheme are shown below.