Pressure on model levels — cdo_delta

This module contains operators to calculate the pressure on model levels. To calculate the pressure on model levels, the a and b coefficients defining the model levels and the surface pressure are required. The a and b coefficients are normally part of the model level data. If not available, the surface pressure can be derived from the logarithm of the surface pressure. The surface pressure is identified by the GRIB1 code number or NetCDF CF standard name. Name & Units & GRIB1 code & CF standard name log surface pressure & Pa & 152 & surface pressure & Pa & 134 & surface_air_pressure

Usage

cdo_delta_pressure(ifile, ofile = NULL)

cdo_pressure(ifile, ofile = NULL)

cdo_pressure_half(ifile, ofile = NULL)

Arguments

ifile: String with the path to the input file.
ofile: String with the path to the output file.

Value

Operators that output one or more files return a character vector to the output files.

Operators that output an indefinite number of files return a string with the basename of the files.

Operatos that don't return filenames return a character vector with the string output.

Details

pressure_half   Pressure on half-levels
                This operator computes the pressure on model half-levels in pascal.
                The model half-level pressure (p_half) is given by:


                        p_half = a + b * sp

                with
                   a, b: coefficients defining the model levels
                   sp: surface pressure
pressure        Pressure on full-levels
                This operator computes the pressure on model full-levels in pascal.
                The pressure on model full-levels (p_full) is in the middle of the layers defined by the model half-levels:

                        p_full = (p_half_above + p_half_below) / 2

delta_pressure  Pressure difference of half-levels
                This operator computes the pressure difference between to model half-levels.

                        delta_p = p_half_below - p_half_above