MeteoIODoc  MeteoIODoc-2.6.0
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Groups Pages
Virtual stations handling

It is possible to use spatially interpolated meteorological fields or time series of 2D grids to extract meteorological time series for a set of points. This is handled as "virtual stations" since the data will seem to originate from these virtual stations points where no station is present. This obviously comes at the cost of much higher run times.

From spatial interpolations

The data from real input stations (as read by the plugin defined with the METEO key in the [input] section) is filtered/processed, temporally interpolated and spatially interpolated as defined in the configuration file. Then time series are reconstructed from these grids at a set of defined points. This behavior is configured by the following keys (in the [Input] section):

  • VIRTUAL_STATIONS set to true;
  • VSTATION# : provide the lat, lon and (optionally) the epsg code for a virtual station;
  • VIRTUAL_PARAMETERS: list of MeteoData::Parameters that have to be interpolated to populate the virtual stations;
  • VSTATIONS_REFRESH_RATE: how often to rebuild the spatial interpolations, in seconds;
  • VSTATIONS_REFRESH_OFFSET: time offset to the stations' refresh rate, in seconds;
  • INTERPOL_USE_FULL_DEM: should the spatial interpolations be performed on the whole DEM? (this is necessary for some algorithms, for example WINSTAL);

Currently, a DEM also has to be provided since this will be used to retrieve the elevation, slope and azimuth of the virtual stations.

In the example provided below, 4 stations provide the original data that will be spatially interpolated at 2 points (virtual stations) for 7 meteorological parameters. Every 6 hours, with starting offset of on hour, the original data will be spatially interpolated (so at 01:00, 07:00, 13:00 and 19:00). Any data requested at other time steps will be temporally resampled from the spatially interpolated data.

DEM = ARC
DEMFILE = ./input/surface-grids/davos.asc
#here, the real data as measured by some stations
METEO = IMIS
DBNAME = sdbo
DBUSER = xxx
DBPASS = xxx
STATION1 = *WFJ
STATION2 = STB2
STATION3 = WFJ2
STATION4 = *DAV
#here the locations where the data will be generated. The caller will only see these stations!
Virtual_stations = true
VSTATION1 = 46.793029 9.821343
VSTATION2 = 46.793031 9.831572
Virtual_parameters = TA RH PSUM ILWR P VW RSWR
VSTATIONS_REFRESH_RATE = 21600
VSTATIONS_REFRESH_OFFSET = 3600
vstations_sampling.png
virtual stations workflow

From gridded data

The meteorological time series are extracted from time series of user-provided grids. therefore a plugin for 2D grids must have been defined (with the GRID2D key in the [Input] section). The following keys control this downscaling process:

  • DOWNSCALING set to true;
  • VSTATION# : provide the lat, lon and (optionally) the epsg code for a virtual station;
  • VIRTUAL_PARAMETERS: list of MeteoData::Parameters that have to be interpolated to populate the virtual stations;
  • VSTATIONS_REFRESH_RATE: how often to rebuild the spatial interpolations, in seconds;
  • VSTATIONS_REFRESH_OFFSET: time offset to the stations' refresh rate, in seconds;

Currently, a DEM has to be provided in order to check the position of the stations and the consistency of the grids.