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The derivatives are computed with a second order finite-difference approximation. The resulting fields contain missing values on the poles. If the input fields are horizontal wind components the GRIB paramId
of the resulting field is set to 138
(relative vorticity). Please note that this function is only implemented for regular latitude-longitude grids.
Anchor w_from_omega w_from_omega
number w_from_omega(omega: number, t: number, p: number)
vector w_from_omega(omega: number, t: number, p: number)
fieldset w_from_omega(omega: fieldset, t: fieldset)
fieldset w_from_omega(omega: fieldset, t: fieldset, p: fieldset)
Computes the hydrostatic vertical velocity from pressure velocity (omega) for a given temperature and pressure, where
omega
: pressure velocity (Pa/s)t
: temperature (K)p
: pressure (Pa)
The result is the vertical velocity in m/s units. On error nil
is returned. The following rules are applied when omega
is a fieldset:
- if
omega
is a pressure level fieldset no pressure argument is needed - if
omega
is defined on ECMWF model levels (hybrid/eta)p
is either a single LNSP (logarithm of surface pressure, identified byparamId
=152
) field or a fieldset defining the pressure on the levels ofomega
- for other level types
p
is a fieldset defining the pressure on the levels ofomega
- if
The computation is based on the following hydrostatic formula:
Mathdisplay |
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w = - \frac{\omega T R_{d}}{p g} |
where
Rd
is the specific gas constant for dry air (287.058 J/(kg K)).g
is the gravitational acceleration (9.81 m/s2)
This functions was introduced in version 5.10.0.