DIVA
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Revision as of 16:10, 12 November 2012
DIVA (Data-Interpolating Variational Analysis) allows the spatial interpolation of data (analysis) in an optimal way, comparable to optimal interpolation (OI). In comparison to OI it takes into account coastlines, sub-basins and advection. Calculations are highly optimized and rely on a finite element resolution. Tools to generate the finite element mesh are provided as well as tools to optimize the parameters of the analysis. Quality control of data can be performed and error fields can be calculated. Also detrending of data is possible. Finally 3D and 4D extensions are included with emphasis on direct computations of climatologies from ODV spreadsheet files.
The research leading to the development of DIVA has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n°283607, SeaDataNet 2.
Contents |
In a few words
Diva is a software developed for gridding in situ data.
It uses a finite-element method to solve a variational principle which takes into account
- the distance between analysis and data (observation constraint),
- the regularity of the analysis (smoothness constraint),
- physical laws (behaviour constraint).
The advantage of the method over classic interpolation methods is multiple:
- the coastline are taken into account during the analysis, since the variational principle is solved only in the region covered by the sea. This prevents the information from traveling across boundaries (e.g., peninsula, islands, etc) and then produce artificial mixing between water masses.
- the numerical cost is not dependent on the number of data, but on the number of degrees of freedom, itself related to the size of the finite-element mesh.
How to get the code?
Diva is copyright © 2006-2012 by the GHER group and is distributed under the terms of the GNU General Public License (GPL) http://www.gnu.org/copyleft/gpl.html
- Latest version (July 2012): GODIVA_07_2012.tar.gz
- Previous releases: here
The code runs preferentially with Lunix operating system, but can also be used under Windows, provided a unix-like environment is installed (Cygwin, Msys, ...)
The binary sources can be provided for several platforms, but if the code has to be re-compiled, then a Fortran compiler (gfortran, ifort, pgi) is needed, along with the NetCDF library if this format is to be used for the outputs.
We also recommend you to register on the Diva Users Group
Diva_installation: for more details about the installation.
The manual and documentation are available here.
A simple matlab interface for basic operations is available divaformatlab.zip
How to try DIVA without installing ?
If you are familiar with Ocean Data View (ODV) you can access DIVA gridding when plotting vertical or horizontal sections.
You can also use basic DIVA features in a web application Diva on Web
User workshops
Since 2006, we organize a workshop for the users, principally members of the region groups responsible for the climatology production in SeaDataNet. Please contact us if you are interested.
- Last workshop: Roumaillac, 8-12 October 2012: Diva_workshop_2012_Roumaillac
- Next workshop in 2013.
- Previous_workshops: information about the previous workshops.
The method
In oceanography, a typical concern consists in determining a field on a regular grid of positions r knowing N;_{d} data in locations r_{j}, j=1,..., N_{d}. This is called the gridding problem and is useful for many applications such as data analysis, graphical display, forcing or initialization of a model.
It is designed to solve 2-D differential or variational problems of elliptic type with a finite element method. Its end is to obtain a gridded field from the knowledge of sparse data points.
You can discover more details about the method here: DIVA_method
Publications & documents
- Related publications: a list of publications where Diva is described or employed to generate gridded fields.
- Documents: user manuals, presentations and posters.
- Applications: examples of climatologies from region groups of SeaDataNet.
- How to cite?
BibTeX entry:
@ARTICLE{TROUPIN2012OM, author = {Troupin, C. and Barth, A. and Sirjacobs, D. and Ouberdous, M. and Brankart, J.-M. and Brasseur, P. and Rixen, M. and Alvera-Azc\'{a}rate, A. and Belounis, M. and Capet, A. and Lenartz, F. and Toussaint, M.-E. and Beckers, J.-M.}, title = {Generation of analysis and consistent error fields using the Data Interpolating Variational Analysis (Diva)}, journal = Ocean Modelling, year = {2012}, volume = {52-53}, pages = {90-101}, doi = {10.1016/j.ocemod.2012.05.002}, url = {http://www.sciencedirect.com/science/article/pii/S1463500312000790 } }
Matlab/Octave tools
Some scripts in matlab for helping in the preparation of figures: Diva_matlab
For calculating within matlab, some basic interface is divaformatlab.zip
Quality control of products
The issue of the quality of the products has been addressed by the EC. This page deals with the successive steps that have to be followed in order to ensure the quality of the products generated by the application of DIVA.
Testing new versions
Every time a significant modification is made to the source code, a set of tests have to be performed to insure that no error was introduced. These tests will be described in the following page: Testing new versions
SVN commands for Diva
A list of commands used to manage the subversions of Diva.