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Gridspec: A standard for the description of grids used in Earth System models

V. Balaji*
Princeton University
Alistair Adcroft
Princeton University

Zhi Liang

7 June 2007


The comparative analysis of output from multiple models, and against observational data analysis archives, has become a key methodology in reducing uncertainty in climate projections, and in improving forecast skill of medium- and long-term forecasts. There is considerable momentum toward simplifying such analyses by applying comprehensive community-standard metadata to observational and model output data archives.

The representation of gridded data is a critical element in describing the contents of model output. We seek here to propose a standard for describing the grids on which such data are discretized. The standard is drafted specifically for inclusion within the Climate and Forecasting (CF) metadata conventions.

1 Introduction
 1.1 Methodology of international modeling campaigns
 1.2 Community approaches to models and data
 1.3 Rationale for a grid standard
 1.4 Overview of paper
2 Grid terminology for Earth System science
 2.1 Geometry
 2.2 Vertical coordinate
 2.3 Horizontal coordinates
 2.4 Time coordinate
 2.5 Discretization
 2.6 Staggering, refinement, and the supergrid
 2.7 Mosaics
 2.8 Boundary contact regions
 2.9 Overlap contact regions: Exchange grids and masks
3 Representing the grid vocabulary in the CF conventions
 3.1 Linkages between files
 3.2 Grid mosaic
 3.3 Grid tile
 3.4 Unstructured grid tile
 3.5 Contact regions
 3.6 Variables
4 Examples
 4.1 Cartesian geometry
 4.2 Gaussian grid
 4.3 Reduced gaussian grid
 4.4 Tripolar grid
 4.5 Unstructured triangular grid
5 Gridspec implementations
 5.1 The GENIE Gridspec
 5.2 The GFDL implementation
6 Summary

* Corresponding author: V. Balaji, Princeton University and NOAA/GFDL, 201 Forrestal Road, Princeton NJ 08540-6646. Email:

TeX4HT created by v. balaji ( in emacs using Tex4HT.
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