Oceanographic conductivity, temperature, and depth (CTD) data from expedition GEOEO, North of Greenland, 2024

Julia Muchowski, Christian Stranne, Johan Nilsson

Processed conductivity, temperature and depth (CTD) data collected during the GEOEO North of Greenland 2024 expedition between August and September 2024.

These CTD data include high resolution (0.2 m) vertical profiles of the water column properties in terms of salinity, temperature, dissolved oxygen, turbidity, fluorescence, and CDOM (colored dissolved organic matter) over a total of 42 casts.

MarineHydrographyGEOEO 2024 expeditionArcticIcebreaker OdenCTDConductivityTemperatureDissolved oxygenTurbidityFluorescenceArctic Ocean

Name

Version

Citation

References

Muchowski J, Stranne C, Nilsson J (2025) Oceanographic conductivity, temperature, and depth (CTD) data from expedition GEOEO, North of Greenland, 2024 — raw data. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-geoeo-2024-ctd-raw-1

Data description

This dataset is provided in three folders. Total size 4.9 MB.

profiles

Processed and quality-controlled CTD data from the downcast in csv files with data from each CTD cast. All files follow the naming convention

GE24-[station number]-ctd[cast number].*

Each file contains the following parameters:

• time NMEA time in UTC in the format yyyy-mm-dd HH:MM:SS.SSS
• lat Latitude (°N)
• lon Longitude (°E)
• pressure pressure (dbar)
• pump Pump status (on/off)
• T1, T2 In situ temperature (°C) for first/second sensor pack
• S1, S2 Practical salinity (PSU) from first/second sensor pack
• OXY1_SAT,OXY2_SAT Oxygen saturation (%) from second sensor pack
• OXY1_ML, OXY2_ML Oxygen concentration (ml/l) from second sensor pack
• FLUOR Fluorescence, WET Labs ECO-AFL/FL (mg/m³)
• TURB Turbidity, WET Labs ECO (NTU)
• CDOM Colored dissolved organic matter (ppb)
• DESC Descent rate (m/s)
• ALTIM Altimeter reading of distance above the seafloor (m)
• CNT Scan count
• T1_quality_flag, T2_quality_flag Quality flags for temperature sensors
• S1_quality_flag,S2_quality_flag Quality flags for salinity sensors
• OXY1_quality_flag, OXY2_quality_flag Quality flag for oxygen sensors

Note that there were dual temperature, conductivity, and oxygen sensor packs installed on the CTD.

Definition of quality flags:

• 0 good data
• 1 sketchy data
• 2 bad data

In some casts NMEA positioning was not available, therefore the fields lat and lon are empty in the data files.

btl_files

Text files with processed data for each water sample, created by the SBEDataProcessing software. Each file ends in _u.btl, with _u indicating that the data were collected during the upcast, and contains a header that provides metadata to the cast, the used sensors, and their calibration data. For each bottle that was sampled, the following parameters are included as average only:

• Bottle Position
• Date Time Date and time in the format mmm-dd-yyyy HH:MM:SS
• Potemp090C and Potemp190C Potential temperature (°C) derived from in situ temperatures in first and second sensor pack using the TEOS10 toolbox
• Sbeox0ML/L, Sbeox1ML/L Oxygen (ml/l) from the first and second sensor pack
• Sbeox0PS, Sbeox1PS Oxygen saturation (%) from the first and second sensor pack
• SvCM Soundvelocity (m/s)
• DepSM Depth (salt water, m) (if calculated)
• DepFM Depth (fresh water, m) (if calculated)
• Sal00, Sal11 Practical salinity (psu) from the first and second sensor pack
• Density00, Density11 Density (kg/m³) from the two temperature and salinity sensor packs
• Sigma00, Sigma11 Density with reference pressure of 0 dbar (kg/m³) from the two temperature and salinity sensor packs

The following parameters are included as average and, in addition, the standard deviation (sdev), their minimum value (min) and maximum value (max) while the bottle was fired are provided:

• Dz/dtM Descent rate (m/s)
• Latitude Latitude (°N)
• Longitude Longitude (°E)
• TimeS Elapsed seconds since the beginning of the CTD cast (s)
• T090C, T190C In situ temperature (°C) from the two sensor packs
• Sbeox0V, Sbeox1V Oxygen sensor raw data (V) from the two sensor packs
• PrDM Pressure, Digiquartz, Strain Gauge (db)
• AltM Altimeter reading of distance to seafloor (m). This value starts to be reliable when approaching the last 100m above the seafloor
• C0S/m, C1S/m Conductivity (S/m)

Processing of the data was done using Tunatools, a Python wrapper around the SBEDataProcessing software.

xmlcon_files

Used configuration files, including calibration coefficients and dates of the applied calibrations for all sensors. Three files are provided, with the file naming convention

GEOEO24_config_cal2024_FLNTURD[serial number]_[without or with]SPAR

Two configuaration files are for Photosynthetically Active Radiation (PAR) data collected with and without the corresponding surface PAR unit (SPAR), respectively. The third file is for data where the Wetlabs Environmental Characterization Optics Fluorometer and Scattering Meter (ECO FLNTURTD, measuring fluorescence and turbidity) sensor was swapped to a replacement sensor.

The configuration files can be opened in a text editor or with the SBE software DisplayConFile, which is part of the SBEDataProcessing software.

Comments

Data quality control

Data were flagged bad when: out of range, difference between the dual sensors, significant outliers — especially at the top and bottom of profiles. In addition, salinity and oxygen data were flagged bad if the pump status was off. Data were flagged as sketchy when abrupt changes occured (spikes, outliers) or unexplainable differences between the dual sensors occured. All other data are flagged as good.

All collected temperature, salinity and oxygen sensor data were quality controlled. The second oxygen sensor shows oxygen minima at the surface of several profiles which were flagged bad when obviously erroneous and sketchy in other cases that were less clear. The reason of the oxygen minima in sensor two are not known. There seem to be issues with the PAR sensor data, which seem to be constant during all casts. The reason for this is unclear as well.

Related raw data

Raw data from which this dataset is derived are made available by Muchowski et al. (2025).

The expedition

Data were collected during the GEOEO North of Greenland 2024 expedition on board the Swedish icebreaker Oden, which was organized by the Swedish Polar Research Secretariat from 5 August through 17 September, 2024.

Project

GEOEO North of Greenland 2024 Expedition

Publisher

Bolin Centre Database

License

Creative Commons Attribution 4.0 International License (CC BY 4.0)

First name

Julia

Last name or organisation

Muchowski

Email address

julia.muchowski@polar.se

Address

Swedish Polar Research Secretariat; c/o Luleå tekniska universitet

Postal code

SE-971 87

City

Luleå

Country

Sweden

GCMD science keyword

Earth science > Oceans

GCMD location

Ocean > Arctic Ocean

Dataset language

English

Begin date

2024-08-08

End date

2024-09-13

DOI

Time