Over the past three decades, a variety of programs have conducted extensive measurements of ocean properties at fixed stations throughout the water column, as well as in the surface ocean via oceanographic ships and ships of opportunity. Ships of opportunity were particularly used to determine the air-sea CO2 fluxes from automated measurements of sea-surface temperature, salinity, and CO2 fugacity. These underway measurements, often recorded at a frequency of every minute, generate large data files that need to be quality controlled, stored and analyzed. For practical use these data are often binned by 1° latitude x 1° longitude. Unfortunately, by doing so, there is a consequential loss of accuracy for these data sets.

Here, using the original 2010 underway data sets of sea-surface temperature, sea-surface salinity, total alkalinity and total inorganic carbon, along the cruise track from Hobart (Tasmania) to Dumont D'Urville (Antarctica), we show what would had been a more appropriate sampling strategy for each of these properties, maintaining their full measurement accuracy, while improving their interpolation accuracy. Furthermore, this analysis illustrates a general methodology for objectively determining, under suitable conditions, the appropriate locations for each property measurement according to a required accuracy. These results should greatly facilitate future cruise preparation and reduce the cost of measurements, while improving their scientific value.