Creating a new observation type

Observation types for Datasets

The toolkit comes with a set of predefined observation types. Each observation type has a standard-toolkit-unit, this is the unit the toolkit will store and display the values.

An overview can be found on this page.

Each observation type is represented by an instance of the Obstype class.

As an example, here is the definition of the temperature observation type:

temperature = Obstype(obsname='temp', #The name of the observation type
                      std_unit= 'Celsius', #The standard unit
                      description="2m - temperature", #A more detailed description (optional)
                      unit_aliases={
                         # Common units and a list of aliases for them.
                          'Celsius': ['celsius', '°C', '°c', 'celcius', 'Celcius'],
                          'Kelvin': ['K', 'kelvin'],
                          'Farenheit': ['farenheit']},
                         # Conversion schemes for common units to the standard unit.
                      unit_conversions={
                          'Kelvin': ["x - 273.15"], #result is in tlk_std_units (aka Celsius)
                          'Farenheit' : ["x-32.0", "x/1.8"]}, # -->execute from left to write  = (x-32)/1.8},
                      )

Similar as this example a user can create a new observation type and add it to a Dataset, using the add_new_observationtype() method.

import metobs_toolkit

#create an new observationtype
wind_component_east = metobs_toolkit.Obstype(
                      obsname='wind_u_comp', #The name of the observation type
                      std_unit= 'm/s', #The standard unit
                      description="2m - u component of the wind (5min averages)", #A more detailed description (optional)
                      unit_aliases={
                         # Common units and a list of aliases for them.
                          'm/s': ['meter/s'],
                         # Conversion schemes for common units to the standard unit.
                      unit_conversions={'km/s': ["x / 3.6"]} #result is in tlk_std_units (aka m/s)
                      )

#add your observation type to a dataset
your_dataset = metobs_toolkit.Dataset()
your_dataset.add_new_observationtype(Obstype=wind_component_east)

# Now you can import a datafile with wind_u_comp data!

If you want to add a new unit to an existing observation type you can do so by using the add_new_unit() method.

Observation types for (ERA5) Modeldata

Modeldata objects also holds a similar set of observation types. But in addition to the observation types stored in the Dataset, extra information is stored on where which (ERA5) band and unit the observation type represents. Here is an example on how to create a new observation type for a Modeldata instance.

import metobs_toolkit

#create an new observationtype
wind_component_east = metobs_toolkit.Obstype(
                      obsname='wind_u_comp', #The name of the observation type
                      std_unit= 'm/s', #The standard unit
                      description="10m - east component of the wind ", #A more detailed description (optional)
                      unit_aliases={
                         # Common units and a list of aliases for them.
                          'm/s': ['meter/s'],
                         # Conversion schemes for common units to the standard unit.
                      unit_conversions={'km/s': ["x / 3.6"]} #result is in tlk_std_units (aka m/s)
                      )
# create a modeldata instance
model_data = metobs_toolkit.Modeldata("ERA5_hourly")

# add new obstype to model_data
model_data.add_obstype(Obstype=wind_component_east,
                       bandname='u_component_of_wind_10m', #See: https://developers.google.com/earth-engine/datasets/catalog/ECMWF_ERA5_LAND_HOURLY#bands
                       band_units='m/s',
                       )

# Collect the U-wind component for your stations:
model_data = your_dataset.get_modeldata(modeldata=model_data,
                                        obstype = 'wind_u_comp')