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Relative Humidity

Performs a variable conversion from specific_humidity (or mixing ratio), temperature, and pressure to relative humidity. The newly calculated variable is included in the same obs space.

Transform: ["RelativeHumidity"]

obs filters:
- filter: Variables Transform
Transform: ["RelativeHumidity"]
Method: UKMO            
Formulation: Sonntag

Observation parameters needed (JEDI name)

  • specific_humidity (q)
  • air_temperature (T)
  • air_pressure or surface_pressure (P)
  • humidity_mixing_ratio (w) (needed when using Method: UKMOmixingratio)

Method(s) available

Various methods are available, shared across all center options. (Any setting of METHOD will result in using formulations associated with the method.) Setting METHOD can be omitted.

options:
  • methodDEFAULT
  • methodUKMOmixingratio
  • methodUKMO

The relative humidity (Rh) is retrieved as follow:


Rh = w/wsat

with wsat (saturated water vapor mixing ratio) derived using esat (saturated vapor pressure):


wsat = ϵ × esat/(P − esat)

and w (water vapor mixing ratio) derived using q (specific humidity):


w = q/(1 − q)

ϵ is ratio of the gas constant for dry air (Rd) over the gas constant for water vapor (Rv). The value of esat (saturated vapor pressure) is derived using SatVaporPres_fromTemp.

Formulation(s) available

Various formulations are available to derive SatVaporPres_fromTemp.

Specific Humidity

Performs a variable conversion from relative humidity, temperature, and pressure to specific humidity. The newly calculated variable is included in the same obs space.

Transform: ["SpecificHumidity"]

obs filters:
- filter: Variables Transform
Transform: ["SpecificHumidity"]
Method: UKMO            
Formulation: Sonntag

Observation parameters needed (JEDI name)

  • relative_humidity (Rh)
  • air_temperature (T)
  • air_pressure or surface_pressure (P)

Method(s) available

Only one method is avalable, shared accross all center options. (Any setting of METHOD will result in using this unique method.) Setting METHOD can be omitted.

The specific humidity (q) is retrieved as follows:


q = w/(1 + w)

where water vapor mixing ratio (w) is derived from relative humidity (Rh)


w = Rh × wsat

with wsat (saturated water vapor mixing ratio) derived using esat (saturated vapor pressure):


wsat = ϵ × esat/(P − esat)

With ϵ is ratio of the gas constant for dry air (Rd) over the gas constant for water vapor (Rv). The value of esat (saturated vapor pressure) is derived using SatVaporPres_fromTemp.

Formulation(s) available

Various formulation are available to derive SatVaporPres_fromTemp.