wiki:udg/ecoms/dataserver/interfaces/matlab

Version 1 (modified by rodri, 9 years ago) (diff)

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Function:

As for Phyton, a Matlab function (loadSystem4.m) has been created in order to access the SPECS-EUPORIAS Data Portal in a user-friendly way. The loadSystem4 function is called this way:

 [data,run,ens,frc,lat,lon] = loadSystem4(dataset,var,season,leadMonth,'members',members,'xlim',xlim,'ylim',ylim,'user',user,'password',password);

The input arguments are next described:

  • dataset: A character string indicating the full URL path to the OPeNDAP dataset. Currently, the accepted values correspond to the System4 datasets described in Section Available Datasets.
  • var: Variable code. Argument values currently accepted are tas, tasmin, tasmax, pr or mslp, as internally defined in the vocabulary for System4 following the nomenclature displayed in the table below. However, note that new variables and datasets will be progressively included.
  • season: A cell of two strings indicating the first and final months of analysis. A single month can be specified (as in the above example) or a standard season (e.g. season = [12,1,2] for standard Boreal winter, DJF).
  • leadMonth: Lead month forecast time corresponding to the first month of the specified season. Note that leadMonth = 1 for season = [1] (January) corresponds to the December initialization forecasts. In this way the effect of the lead time forecast in the analysis of a particular season can be analyzed by just changing this parameter.
  • members: Vector with the list of members to select.
  • xlim: Vector of length = 2, with minimum and maximum longitude coordinates, in decimal degrees, of the bounding box selected.
  • ylim: Vector of length = 2, with minimum and maximum latitude coordinates, in decimal degrees, of the bounding box selected.
  • user: Username for accessing the OPeNPAD dataset.
  • passwork: Password for accessing the OPeNPAD dataset.

These are the arguments returned by the function:

  • data: Cell with n elements (one for each year), in which each element (a 2-D matrix) is the data for a particular year. A 2-D matrix of i rows and j columns, i represents the forecast times and j the grid-points selected.
  • run: Cell with n elements (one for each year) corresponding to the initialization times selected. Note that there is an initialization time associated to each forecast time.
  • ens: List of length n, where n is the number of members of the ensemble selected by the members argument.
  • frc: Cell with n elements (one for each year) corresponding to the forecasts times.
  • lat: Vector with the latitudes of the selected domain.
  • lon: Vector with the longitudes of the selected domain.

Example:

In this example, the loadSystem4 function is used to read the maximum temperature for the Iberian Peninsula in August for the whole hindcast period (1981-2010), considering the initialization of the first of June (two-month lead time thus) for a single member (member5, for instance).

dataset = 'http://www.meteo.unican.es/tds5/dodsC/system4/System4_Seasonal_15Members.ncml';
var = 'Maximum_temperature_at_2_metres_since_last_24_hours_surface';
 [data,run,ens,frc,lat,lon] = loadSystem4(dataset,var,{'Aug';'Aug'},2,'members',5,'xlim',[-10 5],'ylim',[35 45]);

The data can be plotted by using the functions from MeteoLab, the open-source Matlab toolbox for statistical analysis and data mining in Meteorology created by the Santander Meteorology Group.

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