DPRE: Dry Pressure-Level Modules

    All variables found within the DPRE module are "dry" variables (i.e. not explicitly
    affected by water and/or convection), and are considered to be "pressure-level"
    variables by ECMWF reanalysis. This means that they are variables where information is
    saved at a predefined list of 37 pressure levels from 1000hPa to 1hPa.

    Note: ECMWF reanalysis data is also stored in model levels (67 for ERA-Interim and 137
    for ERA5) but ClimateERA.jl does not currently support this feature.  If you are
    interested in collaborating to add this feature, please contact me (Nathanael).

    To select this module in erainitialize, use:
        - erainitialize(modID="dpre")

    Examples of DPRE variables are:
        - Wind (all three directions)
        - Temperature
        - Divergence and Vorticity

    In ERA5, DPRE variables are identified as:
        - reanalysis-era5-pressure-levels
        - pressure_level: xxx (hPa)

    In ERA-Interim, DPRE variables are identified as:
        - levtype: pl
        - levelist: xxx (hPa)

    Note: If you are interested in collaborating to add other variables this feature,
    please contact me (Nathanael), and/or create a pull request.
