U.S. Dept. of Commerce / NOAA / ERL / PMEL....[Ferret]

## Grid indices in Ferret

In these data sets the index "I" refers to longitude, "J" to latitude, "K" to the vertical dimension, and "L" to time. In the listing the values under each qualifier present the points available along that axis. For example 1:180 indicates that locations 1 through 180 are represented in the data set.

FERRET allows the user to probe the data set by slicing along various planes and axes, interactively examining raw and transformed data.

In FERRET all variables are regarded as defined on grids. The grids tell FERRET how to locate the data in space and time (or whatever the underlying units of the grid axes are). Information describing a region in space/time, a data set and a grid is collectively referred to as the "context".

The indices I, J, K, and L refer to positions on a line along one of the dimensions of a grid. The line is divided into n points, or more precisely, n grid boxes where each grid box is a length along the axis. A grid is a group of 1 to 4 axes defining a coordinate space.

The indices refer to grid locations in which the points along an axis are regarded as integers from 1 to the number of points on the axis. The qualifiers I, J, K and L are provided to specify locations by subscript.