Consider an RBRconcerto³ C.T.D.DO logger, where the DO channel is a RBRoptode. The RBRoptode 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:
$\text{Air saturation} = 2.24145 \cdot \dfrac{(Patm - Pav) \cdot Cc}{(10.1325 - Pav) \cdot \text{Solubility}}$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:
\begin{equation*} \begin{aligned} \text{Solubility} = exp((&Ga_0 + Ga_1 \cdot Ts + Ga_2 \cdot Ts^2 + Ga_3 \cdot Ts^3 + Ga_4 \cdot Ts^4 + Ga_5 \cdot Ts^5) \\ + S \cdot (&Gb_0 + Gb_1 \cdot Ts + Gb_2 \cdot Ts^2 + Gb_3 \cdot Ts^3) + Gc_0 \cdot S^2) \end{aligned} \end{equation*}where S is the salinity in PSU and Ts is defined as:
$Ts = ln(\dfrac{298.15 - T}{273.15 + T})$with T being the water temperature in °C and:
\begin{equation*} \begin{aligned} Ga_0 & = 2.00856 \\ Ga_1 & = 3.22400 \\ Ga_2 & = 3.99063 \\ Ga_3 & = 4.80299 \\ Ga_4 & = 9.78188e-1 \\ Ga_5 & = 1.71069 \\ Gb_0 & = -6.24097e-3 \\ Gb_1 & = -6.93498e-3 \\ Gb_2 & = -6.90358e-3 \\ Gb_3 & = -4.29155e-3 \\ Gc_0 & = -3.11680e-7 \end{aligned} \end{equation*}Air vapour pressure (in dbar) is calculated as:
$Pav = \dfrac{exp(52.57 - \dfrac{6690.9}{T + 273.15} - 4.6818 \cdot ln(T + 273.15))}{100}$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)
Confirm the channel type. Request confirmation of all channel indices.Examples
<< calibration 9 type = doxy22
<< calibration 9 type = doxy22, datetime = 20171201000000, n0 = 4, n1 = 5, n2 = 8, n3 = value