era5 data

era5 data loading

Create either a data handler that can load era5 data or implement a fully new loading method that is used to load the data.

collection of tasks

• use BallTree from sklearn to calculate nearest neighbor https://stackoverflow.com/questions/61952561/how-do-i-find-the-neighbors-of-points-containing-coordinates-in-python
• using haversine distance metric: https://scikit-learn.org/stable/modules/generated/sklearn.metrics.pairwise.haversine_distances.html?highlight=haversine#sklearn.metrics.pairwise.haversine_distances
• for now: use "nearest" option from xarrays sel command (a more elaborated neighboring or interpolation method can be implemented later)

todos

• check inside DataHandlerSingleStation for data origin. If origin not equal to era5 use the join downloader. Otherwise use new era5 data loading
• implement era5 data loading method
  • use station coordinate to find nearest grid cell
  • load all data for given variables (maybe in given time range)
  • store locally as .nc (as for join data)
  • return data and meta
• be able to handle mixed data origins: e.g. chem with None origin and meteo with era5 origin.
  • either use two separate files or combine files. Think about what is best option?
• inspect if meta data check works still properly which triggers new a download or just loading from disk