A Gaussian grid is used in the earth sciences as a gridded horizontal coordinate system for

scientific modeling Scientific modelling is a scientific activity, the aim of which is to make a particular part or feature of the world easier to understand, define, quantify, visualize, or simulate by referencing it to existing and usually commonly accepted ...

on a

sphere A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is th ...

(i.e., the approximate

shape A shape or figure is a graphical representation of an object or its external boundary, outline, or external surface, as opposed to other properties such as color, texture, or material type. A plane shape or plane figure is constrained to lie ...

of the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

). The grid is rectangular, with a set number of

orthogonal coordinates In mathematics, orthogonal coordinates are defined as a set of ''d'' coordinates q = (''q''1, ''q''2, ..., ''q'd'') in which the coordinate hypersurfaces all meet at right angles (note: superscripts are indices, not exponents). A coordinate su ...

(usually

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...

and

longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek lette ...

). At a given latitude (or ''parallel''), the gridpoints are ''equally'' spaced. On the contrary along a longitude (or ''meridian'') the gridpoints are ''unequally'' spaced. The spacing between grid points is defined by

Gaussian quadrature In numerical analysis, a quadrature rule is an approximation of the definite integral of a function, usually stated as a weighted sum of function values at specified points within the domain of integration. (See numerical integration for mor ...

. By contrast, in the "normal" geographic latitude-longitude grid, gridpoints are equally spaced along both latitudes and longitudes. Gaussian grids also have no grid points at the

poles Poles,, ; singular masculine: ''Polak'', singular feminine: ''Polka'' or Polish people, are a West Slavic nation and ethnic group, who share a common history, culture, the Polish language and are identified with the country of Poland in C ...

. In a ''regular'' Gaussian grid, the number of gridpoints along the longitudes is constant, usually double the number along the latitudes. In a ''reduced'' (or ''thinned'') Gaussian grid, the number of gridpoints in the rows decreases towards the poles, which keeps the gridpoint separation approximately constant across the sphere.

Examples of Gaussian grids

CCCma CCCma (Canadian Centre for Climate Modelling and Analysis) is part of the Climate Research Division of Environment Canada and is located at the University of Victoria, Victoria, British Columbia. Its purpose is to develop and apply climate models ...

global climate model A general circulation model (GCM) is a type of climate model. It employs a mathematical model of the general circulation of a planetary atmosphere or ocean. It uses the Navier–Stokes equations on a rotating sphere with thermodynamic terms ...

s of

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

** 6×48** 28×64*

European Centre for Medium-Range Weather Forecasts The European Centre for Medium-Range Weather Forecasts (ECMWF) is an independent intergovernmental organisation supported by most of the nations of Europe. It is based at three sites: Shinfield Park, Reading, United Kingdom; Bologna, Italy; an ...

** 192×96 ** 320×160 ** 512×256 ** 640×320 ** 800×400 ** 1024×512 ** 1600×800 ** 2048×1024 ** 2560×1280
Features for ERA-40 grids

References

NCAR Command Language documentation
* W.M. Washington and C.L. Parkinson, 2005. An Introduction to Three-Dimensional Climate Modeling. Sausalito, CA, University Science Books. 368 pp. * Hortal, Mariano, and A. J. Simmons, 1991. Use of reduced Gaussian grids in spectral models. Monthly Weather Review 119.4 : 1057-1074. Geodesy Geographic coordinate systems {{geodesy-stub

Examples of Gaussian grids

See also

References