Zhetao Tan

Zhetao Tan

he/him

Ph.D. in Meteorology

CODC-S: a quality-controlled global ocean salinity profiles dataset

Published in Scientific Data, 2025

Changes in the global ocean salinity reflect the evolution of the global hydrological cycle. These secular changes are assessed using seawater salinity profiles obtained during the past ~80 years. Here, A new study recently published in Scientific Data introduces a new global ocean salinity profiles database named CODC-S (the Chinese Academy of Science (CAS) Oceanography Data Center – Salinity component), which encompasses over 11 million in-situ salinity profiles from 1940 to 2023 obtained by means of several instrument types. These salinity profiles are quality-controlled (QC-ed) using a new automated salinity quality control system named CODC-QC-S (the CODC Quality Control system – Salinity component), consisting of 11 distinct quality checks. By applying time-varying, flow-dependent, and topographical-dependent 0.5% and 99.5% quantile thresholds, the CODC-QC-S defines local climatology salinity ranges without the assumption of Gaussian distribution. The CODC-S database, together with the newly proposed QC algorithm, has undergone extensive evaluations, including comparisons with the benchmark data and climatology, as well as analyses of global and basin-scale long-term salinity changes before and after QC. These validations demonstrate that the quality of salinity data in the CODC-S is time-, depth-, region- and instrument type-dependent.

This eight-decade quality-homogeneous salinity profiles dataset can support diverse oceanographic and climatic research such as monitoring water cycle changes and freshwater/overturning transports.

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Figure. Geographical distribution of all salinity profiles from different instruments in the CODC-S dataset for several decadal periods.

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Figure. The reconstructed SSS (left) and 0–2000 m (right) salinity time series before (dashed grey line) and after (solid colored line) QC for Global, Pacific, Atlantic and Indian oceans, separately. The dashed lines represent results before QC (NoQC), and the solid lines show after CODC-QC-S. The anomalies are calculated relative to the 2000–2015 climatology.

Citations: Tan Z, Zhu Y, Cheng L, Gouretski V, Pan Y, Yuan H, Wang Z, Li G, Song X, Zhang B, Bao S, Li Y, Zhu J. 2025. CODC-S: A quality-controlled global ocean salinity profiles dataset. Scientific Data, 12: 917. https://doi.org/10.1038/s41597-025-05172-9

Recommended citation: Tan Z, Zhu Y, Cheng L, Gouretski V, Pan Y, Yuan H, Wang Z, Li G, Song X, Zhang B, Bao S, Li Y, Zhu J. 2025. CODC-S: A quality-controlled global ocean salinity profiles dataset. Scientific Data, 12: 917. https://doi.org/10.1038/s41597-025-05172-9
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