airDensity {masscor}

Models for calculating air density based on environmental conditions

Description

The function uses environmental conditions information (barometric pressure, temperature and relative humidity.) to calculate a local air density value. If no parameter is defined, the air density at 20^oC, 1013.25 hPa and 50% relative humidity is returned. The air density value value can later be used to calculate the Magnitude of Air Buoyancy Correction (MABC()). The uncertainty of the air density value can be calculated using the function uncertAirDensity().

Usage

airDensity(Temp = 20, p = 1013.25, h = 50, unitsENV = c("deg.C", "hPa",
  "%"), x_CO2 = 4e-04, model = "CIMP2007")

Arguments

Temp

ambient temperature in weighing room.

p

barometric pressure in weighing room.

h

relative humidity in weighing room.

unitsENV

character vector of length three with the units of p, Temp and h. Default is c('deg.C', 'hPa', '%'). See unitsENV below for more options.

x_CO2

molar fraction of carbon dioxide in the air inside weighing room.

model

model to use for air density calculation. Must be one of 'CIMP2007' (default), 'CIMP.approx' or 'Jones1978'. See See Details for references.

Details

Local air density can be estimated using one of several methods. The most complete approach is the CIMP complete formula (the default, method = 'CIMP2007') as described in Picard et al (2008). The CIMP approximated exponential formula (method = 'CIMP.approx') and the method reported by Jones, (method = 'Jones1978') (Harris, 2019) are also included.

Value

Numeric value of air density in g~cm^{-3}, according to chosen model.

unitsENV

Temperature units (Temp) can be either 'deg.C' (for Celsius degrees) or 'K'. Pressure units (p) can be any of 'mmHg', 'Pa', 'hPa' or 'kPa'. Relative humidity (h) can be expressed as fraction ('frac') or as percentage ('%'). A typical arrangement for the parameter unitsENV would be c('deg.C', 'hPa', '%').

References

Picard, A; Davis, R S; Gläser, M; Fujii, K (2008). Revised formula for the density of moist air (CIPM-2007). Metrologia, 45(2), 149–155. doi:10.1088/0026-1394/45/2/004

Harris, G. (2019). Selected Laboratory and Measurement Practices and Procedures to Support Basic Mass Calibrations. SOP 2 - Recommended Standard Operating Procedure for Applying Air Buoyancy Corrections. National Institute of Standards and Technology (NIST). doi:10.6028/NIST.IR.6969-2019

Preguntar a andres referencia de la f'ormula simplificada exponencial

See Also

MABC() to calculate the Magnitude of Air Buoyancy Correction and uncertAirDensity() to estimate the uncertainty of the calculated air density.

Examples

airDensity(Temp = 23.4, p = 612.3, h = 23,
           unitsENV = c('deg.C', 'mmHg', '%')) # [g/cm^3]
airDensity(Temp = 23.4, p = 612.3, h = 23,
           unitsENV = c('deg.C', 'mmHg', '%'), model = 'CIMP.approx') # [g/cm^3]
airDensity(Temp = 23.4, p = 612.3, h = 23,
           unitsENV = c('deg.C', 'mmHg', '%'), model = 'Jones1978')   # [g/cm^3]