Select a set of stations: amount of data, distance, elevation
The station set can be reduced by these additional criteria.
- The number of years with data. In the case of monthly data
there sometimes is enough metadata to demand this for a specific
season. If not, the only guarantee is that there is some data in
each of the years.
- Distance between stations. Which stations are chosen depends on
the ordering in the database and is therefore approximately random.
- Altitude (elevation): for some analyses it is useful to exclude