cdfentropy, cdfmr, cdfnewent − computes the moist entropy using the formula of Iribarne and Godson as well as saturation mixing ratio, or computes the mixing ratio, or computes Lopez-Carrillo entropy
cdfentropy −d|q pressure temperature dewpoint|mixing_ratio entropy sat_mixing_ratio [liq_water]
cdfmr pressure temperature dewpoint mixing_ratio
cdfnewent pressure temperature mixing_ratio entropy sat_entropy
Cdfentropy computes moist entropy (J/K/kg) from the pressure (mb), temperature (C), either dewpoint (C) or water vapor mixing ratio (g/kg), and optionally, the liquid water content (g/m^3). The flag -d indicates dewpoint is expected, while -q indicates that mixing ratio is expected. The first three command line arguments, and optionally the last, indicate the names of the respective variable fields in the Candis file expected on the standard input. The result is written to the standard output with the entropy named in the fifth command line argument and the saturation mixing ratio in the sixth argument. The formula for entropy is that of Iribarne and Godson, which is the same as that used by Raymond and Blyth in their stochastic mixing model.
The effect of liquid water content is generally small.
Cdfmr computes the mixing ratio (g/kg) from the pressure (mb), temperature (C), and the dewpoint (C). The first three command line arguments indicate the names of the respective variable fields in the Candis file expected on the standard input. The result is written to the standard output with the mixing ratio named in the fourth command line argument.
Cdfnewent computes moist entropy (J/K/kg) from the pressure (mb), temperature (C), and total cloud water mixing ratio (g/kg). The moist entropy is named by the fourth command line argument and the saturated moist entropy is named by the fifth. This result should closely match Iribarne and Godson below the freezing level.
The dewpoint is not allowed to exceed the temperature. Some would consider this to be a feature. However, no such constraint is applied to the mixing ratio if that is given as the moisture parameter.
The new fields have the same size and shape as the pressure field. The program checks the temperature, mixing ratio, and liquid water content fields only for compatible size with the pressure field, not for compatible shape.
All fields must be in the variable slice rather than in the static slice. Thus, if pressure is used as an index field, it must be copied to the variable slice, using, for instance, cdfmath.