# Example 18: deri_o2sat_garcia, derived O2 saturation from concentration

Consider an RBR*concerto³* C.T.D.DO logger, where the DO channel is a RBR*coda* ODO. The RBR*coda* ODO transfers both the foil temperature and the dissolved oxygen concentration (not compensated for salinity). The RBR*concerto³* 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 O_{2} saturation equation was revised in firmware 1.094 of the RBR*concerto*^{3}, RBR*maestro*^{3}, RBR*duo*^{3}, RBR*legato*^{3} and RBR*argo*^{3}. 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.