Time series of hydrographic variables in the Coastal Transition Zone of the Canary Current Upwelling System (RaproCAN programme, BICC region)

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Three hydrographic time series have been constructed to characterize long-term thermohaline variability in a representative sector of the Coastal Transition Zone of the Canary Current Upwelling System, close to 28°N between 10°W and 14°W. The dataset corresponds to the averaged of the stations 5–10 of the Radial Profunda de Canarias (RaproCAN) deep section, east of the Canary Islands. The Canary Archipelago is located on the eastern margin of this subtropical gyre, within the Canary Current system, making this region a strategic location for studying ocean variability in the northeastern Atlantic. However, there are still few long-term oceanographic time series that allow analysis of the evolution of water masses and the processes associated with subtropical circulation in this region. RaproCAN is funded and coordinated by the Instituto Español de Oceanografía (IEO-CSIC) and consists of repeated high-quality CTD stations. Although RaproCAN formally started in 2006, the time series presented here extend back to 1997, integrating historical hydrographic data. Sampling frequency is yearly or twice per year, depending on cruise availability. Each series represents a depth-integrated layer associated with a major water mass in the coastal transition zone of the Canary current upwelling system: (i) Surface Waters (SW) – 25-150 dbar This layer represents the surface waters, including upwelloing waters from the Canary Current Upwelling System. Variability reflects changes in the upweeling intesity. (ii) Eastern North Atlantic Central Water (ENACW) – 200–800 dbar This layer represents the main thermocline waters of the subtropical gyre. Variability reflects changes in ventilation, stratification, and large-scale circulation within the upper ocean. (iii) Mediterranean Water / Antarctic Intermediate Water (MW–AAIW) – 800–1200 dbar This intermediate layer captures the influence of saline Mediterranean Water and the fresher Antarctic Intermediate Water signal. Variability in this depth range is linked to changes in intermediate circulation and mixing processes. Each time series includes temperature (°C) and salinity, derived from calibrated conductivity–temperature–depth (CTD) profiles. Values correspond to depth-averaged properties within the specified pressure ranges. Standard quality control procedures were applied to ensure temporal consistency across cruises. Together, these three records provide a multi-decadal perspective (1997–present) on thermohaline variability in the Coastal Transition zone between the Canary Current Upwelling System and the open ocean in the Canary Basin, supporting studies of subtropical gyre and upweeling dynamics, intermediate water transformations, and deep-water variability linked to the Atlantic Meridional Overturning Circulation. The time series are included in the ICES Report on Ocean Climate, prepared by the ICES Working Group on Oceanic Hydrography, and are also published at https://ocean.ices.dk/iroc/home Data are provided as separate CSV files, but also were formatted following the MEDAR/MEDATLAS standard in a single file. These actions ensure compliance with FAIR data principles and facilitate their inclusion in international repositories, thereby promoting data reuse and open science.

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