geocat.comp.meteorology.delta_pressure

geocat.comp.meteorology.delta_pressure(pressure_lev, surface_pressure, pressure_top=None)

Calculates the pressure layer thickness, i.e. the change in pressure (delta pressure), for each layer in a specified constant pressure level coordinate system and accounting for specified surface pressure(s).

Calculated as described by Simmons & Burridge (1981) in equation (3.1):

\[\Delta p = p_{k+1/2} - p_{k-1/2}\]

Returns an array of shape matching (surface_pressure, pressure_lev).

Parameters:

• pressure_lev (numpy.ndarray, xarray.DataArray) – The pressure level array. May be in ascending or descending order. Must have the same units as surface_pressure.

• surface_pressure (int, float, numpy.ndarray, xarray.DataArray) – The scalar or N-dimensional surface pressure array. Must have the same units as pressure_lev.

• pressure_top (float, optional) – A scalar specifying the top of the column. Should be <= min(pressure_lev) and have the same units as pressure_lev. If left as None, min(pressure_lev) will be used.

Returns:

delta_pressure (numpy.ndarray, xarray.DataArray) – The pressure layer thickness array. Shares units with pressure_lev. If surface_pressure is scalar, shares dimensions with pressure_level. If surface_pressure is an array than the returned array will have an additional dimension [e.g. (lat, lon, time) becomes (lat, lon, time, lev)]. Will always be the same type as surface_pressure.

See also

Related NCL Functions: dpres_plev