w_from_omega

w_from_omega(omega, t[, p])

Computes the hydrostatic vertical velocity from pressure velocity (omega) for a given temperature (t) and pressure (p).

Parameters

  • omega (number, ndarray or Fieldset) – hydrostatic pressure velocity (Pa/s)

  • t (number, ndarray or Fieldset) – temperature (K)

  • p (number, ndarray or Fieldset) – pressure (Pa)

Return type

same type as omega or None

The result is the vertical velocity in m/s units. On error None is returned. The following rules are applied when omega is a Fieldset:

  • if omega is a pressure level Fieldset no p is needed

  • if omega is defined on ECMWF model levels (hybrid/eta) p must be either a single LNSP (logarithm of surface pressure, identified by paramId=152) field or a Fieldset defining the pressure on the same levels as omega

  • for other level types p must be a Fieldset defining the pressure on the same levels as omega.

The computation is based on the following hydrostatic formula:

\[w = - \frac{\omega T R_{d}}{p g}\]

where

  • \(R_{d}\) is the specific gas constant for dry air (287.058 J/(kg K)).

  • g is the gravitational acceleration (9.81 m/s2)