Production of high quality hydrographic data

The ocean is the dominant reservoir of heat and carbon in the climate system on time scales from years to centuries. Thus, historical ocean observations are essential to understand the processes that control the variability in environmental conditions and climate on these time scales. High quality observations are essential to address both regional and global problems. Because environmental changes involve a wide range of spatial and temporal scales, and given the high cost of oceanographic surveys, calibration protocols and widely documented procedures are necessary to ensure the highest possible data quality and to preserve the information for future use.

Vertical quasi-continuous conductivity-temperature-depth (CTD) profiles have become the backbone of ocean hydrographic observations. Factory CTD sensor calibrations are not always easy to carry out. Especially in these cases, in situ discrete bottle data are of crucial importance as complementary information of the water column for the analysis of vertical changes in highly variable temperature-salinity structures. This work will address CTD data processing steps and describe the laboratory and field calibrations and the associated documentation required for future users.