FY 1993

FERRET: A Mathematica-style visualization and analysis tool for gridded oceanographic and meteorological data

Hankin, S., and D.E. Harrison

In Ninth International Conference on Interactive Information and Processing Systems for Meteorology, Oceanography, and Hydrology, 73rd AMS Annual Meeting, Anaheim, CA, 17–22 January 1993, 168–171 (1993)

An overview of the program, FERRET, will be provided. FERRET is an interactive computer visualization and analysis environment designed to meet the needs of oceanographers and meteorologists analyzing large and complex gridded data sets. FERRET was developed by the Thermal Modeling and Analysis Project (TMAP) at NOAA's Pacific Marine Environmental Laboratory in Seattle, Washington to analyze the outputs of its numerical ocean models and compare them with gridded, observational data. Model data sets, which are typically sequences of three dimensional "snapshots", are commonly multi-gigabyte in size and often contain mixed 3-dimensional and 4-dimensional variables defined on staggered grids. FERRET offers a Mathematica-like approach to analysis; new variables may be defined interactively as mathematical transformations of data set variables. A symmetric, 4-dimensional command syntax is used to designate arbitrary rectangular regions in 3-space and time and "IF-THEN" logic permits calculations to be applied over arbitrarily shaped regions. Fully documented graphics are produced with a single command. FERRET is available on SUN, DEC/Ultrix, SGI and VAX/VMS computers. It supports most modern graphics hard-copy devices.

Many excellent software packages have been developed recently for scientific visualization. The features that make FERRET distinctive among these packages are

• flexibility:

  FERRET provides a collection of basic transformations (averaging, integrating, smoothing, arithmetic and trigonometric operators, etc.) and a familiar, Mathematica-like language for interactively defining new variables from older ones.

• integration of analytical power into the graphical environment:

  FERRET's graphical and analytical tools can be applied as readily to variables defined by the user as they can to the "raw" data. FERRET's graphical tools include animations, color shaded plots, contour plots, line and scatter plots, 3-dimensional fish nets, multiple windows and overlays.

• symmetrical processing in four dimensions:

  FERRET treats all four axes of the space-time coordinate system as equivalent. No special commands are required and no limitations are imposed when working with time series data.

• "intelligent" connection of FERRET to its data base:

  FERRET automatically provides full labelling and titling of all plots with information pulled from the data in a self-describing format. This feature provides an important quality assurance on the results a user obtains from FERRET.

• able to analyze very large data sets:

  FERRET has built-in memory and disk management capabilities to handle data sets too large to fit within the limitations of on-line storage. FERRET renders these machine limitations invisible to the user for most applications, giving the user the impression of a greatly enlarged virtual storage environment.

• geophysical coordinates:

  FERRET is designed to work computationally and graphically on latitude/longitude grids.