Profiling Floats for Ocean Data Collection

The floats must carry proven temperature, salinity and pressure sensors that meet the following standards. The temperatures are accurate to ±0.002°C and pressures are accurate to ±2.4dbar. For salinity, the data delivered in real time are sometimes affected by sensor drift, for many floats this drift is small and the uncorrected salinities are accurate to ±0.01 psu. (At a later stage, salinities are checked by comparing older floats with newly deployed instruments and ship-based data, where salinity drifts may be corrected for.) The data must be transmitted with at least the following resolution 0.001 °C in temperature, 0.001 in salinity and 0.1 dbar in pressure.

Bio-geochemical-Argo is the extension of the Argo array of profiling floats to include floats that are equipped with additional sensors for pH, oxygen, nitrate, chlorophyll fluorescence, suspended particles and down-welling irradiance. With respect to Lot 2, it is likely that purchases of such floats will range from those with a single additional sensor (most likely dissolved oxygen) through to the full six variables sensor suite as noted above.