High-Resolution CTD Profiles from the SIMSVAL and FANS Oceanographic Campaigns (Greenland Expedition 2025)

High-Resolution CTD Profiles from the SIMSVAL and FANS Oceanographic Campaigns (Greenland Expedition 2025) "Version 2 adds the raw Ruskin (.rsk) data files for both campaigns." This repository hosts the high-resolution oceanographic datasets collected during the SIMSVAL and FANS research campaigns conducted in the fjords and coastal waters of West Greenland (60.2°N – 69.5°N) between March and April 2025 - SIMSVAL (32 profiles) + FANS (41 profiles). The data acquisition was carried out on board the vessel Le Commandant Charcot using high-accuracy RBR Concerto CTD (Conductivity, Temperature, Depth) loggers deployed via zodiacs. The dataset was processed using a reproducible MATLAB pipeline archived on GitHub and Zenodo: https://github.com/Barcelona-Polar-Lab/SIMSVAL_FANS_MarApr2025_postprocessing (doi: 10.5281/zenodo.20527364). Dataset described in: Umbert et al. (in preparation), Earth System Science Data. The dataset is distributed in two complementary NetCDF-4 files, both compliant with CF-1.8 and ACDD-1.3 conventions: 1) Raw Data Product: 'SIMSVAL_FANS_MarApr2025_RAW.nc' This file contains the raw, native instrument output from 73 casts. The only correction applied is the subtraction of the atmospheric pressure using synchronized shipboard FerryBox data. It includes native conductivity and surface salinity bottle samples analyzed via a Guildline Autosal 8400B salinometer. 2) Processed Data Product: 'SIMSVAL_FANS_MarApr2025_PROC.nc' This file contains scientifically procesed, analysis-ready data from 73 profiles. The processing pipeline (MATLAB architecture) includes digital A/D hold correction, high-frequency despiking, dynamic conductivity-temperature alignment (for the 16 Hz stream), low-pass boxcar filtering, automated soak phase truncation, and strict downcast velocity filtering (> 0.1 m/s) to eliminate ship-heave artifacts. Derived variables include Practical Salinity (PSS-78) and Potential Density Anomaly (TEOS-10). Automated Real-Time Quality Control (RTQC) flags have been applied using the SeaDataNet L20 vocabulary (Argo/QARTOD style). Crucially, the data is preserved at its native temporal resolution (unbinned) to retain sub-metric vertical structural features. Spatial and temporal coverage Region Western Greenland fjords Latitude 60.16°N – 69.49°N Longitude 53.85°W – 43.61°W Sea pressure ~0 – 148.9 dbar SIMSVAL period 24 March 2025 – 08 April 2025 FANS period 14 April 2025 – 28 April 2025 Total profiles 73 Files metadata Dimensions Dimension Size Description profile 73 One element per CTD profile obs 6623 Maximum number of samples per profile (NaN-padded); native resolution name 6 Maximum length of station identifiers campaign 7 Maximum length of campaign names (SIMSVAL = 7 characters) Variables Variable Units Description time seconds since 1970-01-01 UTC Profile start time, defined as the first valid sample; CF coordinate latitude degrees north Profile latitude; NaN for profiles without GPS position longitude degrees east Profile longitude; NaN for profiles without GPS position station_id — Station identifier, e.g. A_1, 3D_3, 8J_5 campaign — Campaign name: SIMSVAL (March 2025) or FANS (April 2025) sea_pressure dbar Sea pressure at native resolution (NaN-padded) depth m Depth derived from sea pressure using TEOS-10 gsw_z_from_p at mean latitude (62.68°N) sample_time seconds since 1970-01-01 UTC UTC timestamp of each native-resolution sample: 1/16 s for ICM-CSIC and 1/2 s for PONANT; NaN for padding temperature °C Seawater temperature salinity dimensionless (PSU) Derived practical salinity (TEOS-10) conductivity S m⁻¹ Electrical conductivity, converted from mS cm⁻¹ by dividing by 10 sigma_theta kg m⁻³ Potential density anomaly σθ (TEOS-10, gsw_sigma0) profile_velocity m s⁻¹ Vertical descent velocity during the downcast NOTE: Temperature, salinity, conductivity, sigma-theta and sea_pressure also include quality-control flags as variables. We also include soak variables such as soak duration, soak depth, and number of samples removed during soak filtering. In addition, atmospheric variables from FerryBox hourly means are included: atmospheric pressure, wind speed, wind direction, and relative humidity. Processing steps applied to each profile Step Operation Description 1 Data reading RSKopen + RSKreadprofiles (downcast only). Channel Temperature1 was renamed to Temperature for the 2 Hz PONANT sensor used at station C. 2 Sea pressure RSKderiveseapressure — sea pressure = raw pressure − atmospheric pressure, using hourly averaged FerryBox atmospheric pressure data and nearest-neighbour interpolation. 3 A/D correction RSKcorrecthold — correction of A/D hold artefacts, applied only to 16 Hz data and omitted for the 2 Hz PONANT sensor due to an RSKtools indexing issue. 4 Spike removal RSKdespike — 4σ threshold, 15-point window, downcast direction, action set to nan. Applied to temperature and conductivity. 5 C/T lag correction RSKcalculateCTlag (seapressurerange = [5 30]) + RSKalignchannel — conductivity/temperature lag correction, applied only to 16 Hz data. Lag limited to ±2 scans. 6 Smoothing RSKsmooth — 5-point window applied to temperature and conductivity. 7 Velocity and depth RSKderivedepth + RSKderivevelocity. 8 Soak removal RSKtrim_soak — fixed-time method, 20 s for all profiles except 1A_1 and 7H_4, where 5 s was used due to rapid descent from the start. 9 Pressure-loop removal RSKremoveloops — removes samples with descent velocity < 0.1 m s⁻¹. 10 Derived variables RSKderivesalinity for practical salinity + gsw_sigma0 from TEOS-10 for potential density anomaly σθ. 11 Quality control apply_QC_tests — seven automatic tests using SeaDataNet L20 flags. The vertical-gradient test was not applied to native-resolution data; see QC note below. Instrument Specifications ICM-CSIC Sensor: RBR Concerto3, sampling at 16 Hz (Serial Number 237957).PONANT Sensor: RBR Concerto3, sampling at 2 Hz (Serial Number 237329). Contact Data Curator: Nina Hoareau ([e-mail]) Principal Investigator: Marta Umbert ([e-mail]) Barcelona Polar Lab, Institut de Ciències del Mar (ICM-CSIC), Barcelona, Spain Acknowledgements The authors thank the captain, crew, expedition staff, and science coordinators of Le Commandant Charcot for their support during the SIMSVAL and FANS campaigns. We also acknowledge PONANT Science and the logistical teams involved in the planning and execution of both expeditions. We thank RBR Ltd. for instrument calibration support and technical assistance during data processing and quality control. This work was supported by the European Research Council (ERC) under the European Union's Horizon Europe research and innovation programme through the ERC Starting Grant FRESH-CARE (grant agreement No. 101164517, 'Unraveling FRESHwater and ocean Currents changes in the Arctic using REmote sensing'). We also acknowledge funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (Grant CEX2024-001494-S funded by AEI 10.13039/501100011033). This work is a contribution to to CSIC Conexión Polar and CSIC Thematic Interdisciplinary Platform PTI Teledetect.