A Gaussian grid is used in the earth science
Earth science or geoscience includes all fields of natural science related to the planet Earth. This is a branch of science dealing with the physical, chemical, and biological complex constitutions and synergistic linkages of Earth's four spher ...
s 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 k ...
on a sphere
A sphere () is a Geometry, geometrical object that is a solid geometry, three-dimensional analogue to a two-dimensional circle. A sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three ...
(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 on ...
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 surf ...
). The grid is rectangular, with a set number of orthogonal coordinates (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 po ...
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 let ...
).
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 m ...
. 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.
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
* CCCmaglobal 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 f ...
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
See also
*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 f ...
* Spectral method
*Spherical harmonics
In mathematics and physical science, spherical harmonics are special functions defined on the surface of a sphere. They are often employed in solving partial differential equations in many scientific fields.
Since the spherical harmonics form a ...
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