35
Oxygen calculation and compensation 9.5
The calibration for this instrument uses traceable reference gases according to the Japanese national standard.
The calibration coefficients (
,
, and
) are derived from 16 calibration points (4 temperature
points and 4 oxygen concentrations). The oxygen concentration () is calculated from the equation below:
=
1 +
+
+
+
1
1
+
+
Uchida et al. (2010)
: Dissolved Oxygen [μmol L
-1
]
,
,
: Calibration coefficients
: Temperature [°C]
: (AD value of DO) / 10000
: LED accumulated time
The pressure-compensated oxygen concentration (
pc
) is calculated from the equation below:
pc
=
1 +
: Pressure [MPa]
: Calibration coefficient
The salinity-compensated oxygen concentration (
sc
) is calculated by multiplying the factor of the effect of
salt on the oxygen solubility (Benson and Krause 1984, García and Gordon 1992). The salinity &
pressure-compensated oxygen concentration can be calculated by using
pc
in the following equation:
sc
= exp
0
+
1
+
2
2
+
3
3
+
0
2
= ln
298.15
273.15 +
: Temperature [°C]
: Salinity [‰ or PSU]
The oxygen concentration in volumetric units (μmol L
-1
) can be converted to gravimetric units (μmol kg
-1
) by
dividing by the potential density calculated from the CTD data.
= - 6.24523 × 10
-3
= - 7.37614 × 10
-3
= - 1.03410 × 10
-2
= - 8.17083 × 10
-3
= - 4.88682 × 10
-7
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