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Execute generation

The Synthetic Data generation tool in Databases is meant to generate hourly or sub-hourly data from monthly weather data. Afer creating a site for your location of interest, you may generate a .MET file with this tool by following these steps:

  • Select the Source data in the list, (you can verify if it is the site you want with "Open").
  • Choose the First Random Seed (between 1 and 10).
  • Chose the time step : 1 hour or 1 minute.
  • Press the Execute Generation button.

The option "Use monthly diffuse" will renormalize the generated diffuse values to the initial monthly input (close but not guarantied by default)

Dialog_Synthetic_hourly_data_generation_sample

Random Seed

The stochastic generation process relies on a random number generator, which must be initialised with a starting value called a random seed. Two runs using the same seed will always produce the same sequence of synthetic data. By changing the seed, a different but equally statistically valid time series is generated — the monthly means remain unchanged, but the day-to-day and hour-to-hour sequences differ.

Diffuse renormalization

If checked, the (sub-)hourly diffuse values are renormalized in order to match the monthly diffuse, (when present in .SIT). This is done through a correction which is not Kt dependant: each hourly value is corrected by the ratio between the specified monthly value and the as-generated-hourly-cumulated monthly diffuse.

Region topology

When running a the synthetic data generation, the region topology can be specified. This will add a slight variation of the generated temperature profile as explained in the Meteonorm theory manual, table 7.2.2.

By default, the synthetic generation uses Meteonorm default mn_situation = open region typology. All options are:

  • open: Open site, open terrain, north-facing incline, no raised skyline. Applies to most sites.
  • depression: Depression or very flat valley floor, in which cold air collects. In Switzerland, for example, particularly in the Jura and the Alps.
  • cold_air_lake: Extensively cold hollows (above 1000 m).
  • sea_lake: Shore of sea or larger lake (up to 1 km from the shore).
  • city: Centre of a larger city (over 100'000 inhabitants).
  • slope_south: South-facing incline (more than approx. 10° inclination, facing between SE–S–SW). At least 200 m above valley floor.
  • slope_west_east: West or east-facing incline (more than approx. 10° inclination, facing between SW–W–NW or NE–E–SE). At least 200 m above valley floor.
  • valley: Valley floor in mountainous valley at higher altitudes. Valley floor inclined (flat valleys are often treated as depressions).
  • valley_foehn: Valley floor of Föhn valley (regions with warm descending air currents).
  • valley_central_alps: Floor of large central Alpine valley (e.g., Alpine regions of Valais, Switzerland).
  • valley_alpine_foothills: Valley floor in northern Alpine foothills.
  • valley_slope_south: South-facing incline (more than approx. 10° inclination, facing between SE–S–SW) up to 200 m above valley floor.
  • valley_slope_west_east: West or east-facing incline (more than approx. 10° inclination, facing between SW–W–NW or NE–E–SE) up to 200 m above valley floor.
  • summit: Open summit above 500 m. Overlooking surroundings in all directions.

Please note that these region classification was developed on swiss wether data and might not extrapolate well to other climates.