DART provides a selection of options for the coordinate system in which all observations and all model state vector
locations are described. All executables are built with a single choice from the available location modules. The names
of these modules are all location_mod.
The core algorithms of DART work with many different models which have a variety of coordinate systems. This directory provides code for creating, setting/getting, copying location information (coordinates) independently of the actual specific coordinate information. It also contains distance routines needed by the DART algorithms.
Each of the different location_mod.f90 files provides the same set of interfaces and defines a 'module location_mod', so by selecting the proper version in your path_names_xxx file you can compile your model code with the main DART routines.
- :doc:`../../assimilation_code/location/threed_sphere/location_mod`: The most frequently used version for real-world 3d models. It uses latitude and longitude for horizontal coordinates, plus a vertical coordinate which can be meters, pressure, model level, surface, or no specific vertical location.
- :doc:`../../assimilation_code/location/oned/location_mod`: The most frequently used for small models (e.g. the Lorenz family). It has a cyclic domain from 0 to 1.
- :doc:`../../assimilation_code/location/threed_cartesian/location_mod`:
- A full 3D X,Y,Z coordinate system.
- :doc:`../../assimilation_code/location/channel/location_mod`: a 3d domain periodic in x, limited in y, and unlimited z.
- column: no x,y but 1d height, pressure, or model level for vertical.
- annulus: a hollow 3d cylinder with azimuth, radius, and depth.
- twod: a periodic 2d domain with x,y coordinates between 0 and 1.
- twod_sphere: a 2d shell with latitude, longitude pairs.
- threed: a periodic 3d domain with x,y,z coordinates between 0 and 1.
Other schemes can be added, as needed by the models. Possible ideas are a non-periodic version of the 1d, 2d cartesian versions. Email dart at ucar.edu if you have a different coordinate scheme which we might want to support.
Each location module option has a different namelist. See the specific documentation for the location option of choice.
- none
- none
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