Example 18: deri_o2sat_garcia, derived O2 saturation from concentration
Consider an RBRconcerto³ C.T.D.DO logger, where the DO channel is a RBRcoda ODO. The RBRcoda ODO transfers both the foil temperature and the dissolved oxygen concentration (not compensated for salinity). The RBRconcerto³ calculates the concentration compensated for salinity first, then the air saturation (in %) via the following equation:
where
Cc is the concentration in uMol/L, compensated for salinity,
Patm is atmospheric pressure, and
Pav is air vapour pressure.
Solubility is calculated via Gordon and Garcia as:
where S is the salinity in PSU and Ts is defined as:
with T being the water temperature in °C and:
Air vapour pressure (in dbar) is calculated as:
The corresponding logger coefficients are:
n0, the index of the concentration channel, already compensated for salinity
n1, the index of the water temperature channel
n2, the index of the salinity channel
n3, the index of the atmospheric pressure channel (set to value in order to use settings atmosphere)
The O2 saturation equation was revised in firmware 1.094 of the RBRconcerto3, RBRmaestro3, RBRduo3, RBRlegato3 and RBRargo3. For the previous implementation of this equation, refer to the version B of this document.
Examples
>> calibration 9 type
<< calibration 9 type = doxy22
Confirm the channel type.
>> calibration 9
<< calibration 9 type = doxy22, datetime = 20171201000000, n0 = 4, n1 = 5, n2 = 8, n3 = value
Request confirmation of all channel indices.