Parameters MET Nordic - tnipen/NWPdocs GitHub Wiki

Here are the variables that are available in the dataset. The starting point is the raw model output at 2.5 km resolution, which is then downscaled to 1km and then in some cases bias-corrected using observations.

NetCDF name	Description
air_temperature_2m	Instantaneous temperature at 2 m. Downscaling from 2.5 km to 1 km using elevation gradient approach. Bias-correction using optimal interpolation observations from Netatmo, WMO-stations from MET and FMI, Bergensværet, Norwegian road authority, and other non-WMO stations in Norway. Forecast correction using a weighted average of recent temperature biases.
precipitation_amount	Precipitation accumulated over the hour leading up to the timestamp. Nearest neighbour downscaling. Bias-correction using observations from Netatmo, WMO-stations from MET and FMI, non-WMO stations in Norway, and radar. No forecast correction.
wind_speed_10m	10 minute average speed of wind at 10m. Downscaling using an elevation gradient method
wind_direction_10m	10 minute average direction of wind at 10m. Direction is where wind is from, and 0 indicates wind from North. The direction is the same as in the raw model output.
relative_humidity_2m	Instantaneous relative humidity at 2 m. Nearest neighbour.
air_pressure_at_sea_level	Instantaneous air pressure reduced to sea level. Nearest neighbour.
integral_of_surface_down...	The time integral of incoming solar radiation at the surface over the hour leading up to the timestamp. The units are therefore W/m^2 s. Nearest neighbour.
cloud_area_fraction	Fraction of sky covered by cloud. Nearest neighbour.

(*) "integral_of_Y_wrt_X" means int Y dX. The data variable should have an axis for X specifying the limits of the integral as bounds. "wrt" means with respect to. The surface called "surface" means the lower boundary of the atmosphere. "shortwave" means shortwave radiation. Downwelling radiation is radiation from above. It does not mean "net downward". Surface downwelling shortwave is the sum of direct and diffuse solar radiation incident on the surface, and is sometimes called "global radiation". When thought of as being incident on a surface, a radiative flux is sometimes called "irradiance". In addition, it is identical with the quantity measured by a cosine-collector light-meter and sometimes called "vector irradiance". In accordance with common usage in geophysical disciplines, "flux" implies per unit area, called "flux density" in physics.

Note that Rerun version 1 provides the following instead of wind_speed_10m and wind_direction_10m:

NetCDF name	Description
x_wind_10m	10 minute average x-component (relative to the lambert projection) of wind at 10m. Downscaling using an elevation gradient method
y_wind_10m	10 minute average y-component (relative to the lambert projection) of wind at 10m.Downscaling using an elevation gradient method