Compute $$\alpha/\beta$$ using McDougall's (1987) algorithm.

swAlphaOverBeta(
salinity,
temperature = NULL,
pressure = NULL,
longitude = NULL,
latitude = NULL,
eos = getOption("oceEOS", default = "gsw")
)

## Arguments

salinity either practical salinity (in which case temperature and pressure must be provided) or an oce object (in which case salinity, etc. are inferred from the object). in-situ temperature ($$^\circ$$C) pressure (dbar) longitude of observation (only used if eos="gsw"; see ‘Details’). latitude of observation (only used if eos="gsw"; see ‘Details’). equation of state, either "unesco" or "gsw".

## Value

Value in psu/$$^\circ$$C.

The eos="unesco" formulae are based on the UNESCO equation of state, but are formulated empirically by Trevor J. McDougall, 1987, Neutral Surfaces, Journal of Physical Oceanography, volume 17, pages 1950-1964. The eos="gsw" formulae come from GSW; see references in the swRho() documentation.

Other functions that calculate seawater properties: T68fromT90(), T90fromT48(), T90fromT68(), swAbsoluteSalinity(), swAlpha(), swBeta(), swCSTp(), swConservativeTemperature(), swDepth(), swDynamicHeight(), swLapseRate(), swN2(), swPressure(), swRho(), swRrho(), swSCTp(), swSTrho(), swSigma0(), swSigma1(), swSigma2(), swSigma3(), swSigma4(), swSigmaTheta(), swSigmaT(), swSigma(), swSoundAbsorption(), swSoundSpeed(), swSpecificHeat(), swSpice(), swTFreeze(), swTSrho(), swThermalConductivity(), swTheta(), swViscosity(), swZ()
swAlphaOverBeta(40, 10, 4000, eos="unesco") # 0.3476#>  0.3416053