Any space-based observation and forecasting system is critically dependent upon in-situ ocean data, since satellites can only sense ocean properties at or very near the sea surface. 1n contrast, in-situ platforms such as Argo Floats provide the inside view of the ocean. However, despite the impressive increase in the number of temperature and salinity profiles from the Argo array, in-situ data still undersample the temporal and spatial variability of the ocean thermohaline structure. Mersea will contribute to the Argo program by filling this gap... [NOT CONTROLLED OCR]