Function AOU(S, T, O2) 'AOU computes the apparant oxygen utilization from the difference ' between measured O2 concentration and the expected O2 conc ' for seawater saturated with air at the sea surface. ' Source: The solubility of nitrogen, oxygen and argon in water and ' seawater - Weiss (1970) Deep Sea Research V17(4): 721-735. ' Molar volume of oxygen at STP obtained from NIST website on the ' thermophysical properties of fluid systems: ' ' http://webbook.nist.gov/chemistry/fluid/ ' ' ' CALCULATE AOU BY DIFFERENCE: ' AOU (umol/kg) = sat O2 (umol/kg) - obs o2 (umol/kg). ' ' ' Input: S = Salinity (pss-78) ' T = Potential Temp (deg C) ' O2 = Meas'd Oxygen Conc (umol/kg) ' ' Output: Apparant Oxygen Utilization (umol/kg). ' ' AOU = aou(S,T,O2). ' DEFINE CONSTANTS, ETC FOR SATURATION CALCULATION ' The constants -177.7888, etc., are used for units of ml O2/kg. T1 = (T + 273.15) / 100 OSAT = -177.7888 + 255.5907 / T1 + 146.4813 * log(T1) - 22.2040 * T1 OSAT = OSAT + S * (-0.037362 + T1 * (0.016504 - 0.0020564 * T1)) OSAT = exp(OSAT) ' CONVERT FROM ML/KG TO UM/KG OSAT = OSAT * 1000 / 22.392 ' CALCULATE AOU AOU = OSAT - O2 End Function