This data set includes CTD-O2 and LADCP data from the 46 stations occupied in Storfjorden and Storfjordrenna during the STEP cruise in July 2016 onboard R/V l'Atalante. Hydrographic data are provided in the form of Seabird ascii format (cnv), with two files per station (up and down). The data set also includes  underway S-ADCP data provided in netcdf format. Sensor metadata: CTD data were collected with a Seabird SBE 911+ probe. Dissolved oxygen data were collected with a Seabird SBE43 probe attached to the rosette. Additional data include fluorescence (Chelsea Aqua3) and transmission (WET labs C-Star).LADCP data were collected with a pair of  300 kHz Workhorse Sentinel from RD Instruments mounted on the rosette. Shipborne-ADCP data were collected with the  150 kHz Ocean Surveyor (RD Instruments)  mounted on the hull of R/V L'Atalante. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

As part of the STeP project (STorfjorden Polynya multidisciplinary study), two moorings, M1 and M2, were deployed in Storfjorden (Svalbard) on July 14, 2016 from the French R/V L’Atalante and were recovered one year later, on September 28, 2017, from the French R/V Pourquoi-Pas?. The two moorings, deployed a few hundred meters apart at 78°N and 20°E at a depth of 100m, documented the formation of dense Brine-enriched Shelf Water (BSW).  The moorings included both physical oceanography (PO) and biogeochemistry sensors. The present dataset is composed of PO data only: the 3 components of the currents, backscatter, salinity, temperature and dissolved oxygen. PO sensors on M1, spanning the whole water column, included 6 Seabird SBE37 microcat (CTD),  15 RBR solo (T), and 1 RBR duet (TD) for hydrography, while currents were monitored with a RDI WH 300kHz upward looking ADCP and 1 Nortek Aquadopp underneath. PO sensors on the shorter M2 mooring included 1 Seabird SBE63 (CTD-O2), 1 RBR solo (T) and 1 RBR duo (TD). Data have been calibrated and validated and the different steps of this processing are discussed in the technical report provided with the dataset. Two netcdf4 files are provided for M1: one for hydrography (STEP2016_M1_hydrography.nc), the other one (STEP2016_M1_current.nc)  for currents and backscatter. Only one netcdf4 files (STEP2016_M2_hydrography.nc) is provided for the shorter M2. Temperature and salinity data from SBE sensors have been interpolated on a common time grid with a 20’ time step. Likewise temperature data from RBR are provided on a 30” time grid. A merged SBE-RBR dataset has also been built for increased vertical resolution, providing temperature every 20’. ADCP data are provided on a 100’ time grid. The user is referred to the technical report provided with the dataset for further information on the different fields. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

Two ice mass balance instruments (part of IAOOS7 and IAOOS8 platforms) deployed near 83°N on the same ice floe, documented the evolution of snow and ice conditions in the Arctic Ocean north of Svalbard in Jan-Mar 2015. Frequent profiles of temperature (every 3 hours) and temperature change after 30s and 120s heating (once a day) were recorded. The ratio of the temperature changes after heating provides a proxy for thermal diffusivity. Both instruments documented flooding and snow-ice formation. Flooding was clearly detectable in the simultaneous changes in thermal diffusivity proxy, increased temperature, and heat propagation through the underlying ice. Slush then progressively transformed into snow-ice. Flooding resulted from two different processes; i) after storm-induced break-up of snow-loaded floes for IAOOS8 and ii) after loss of buoyancy due to basal ice melt for IAOOS7. The instrument on IAOOS7 documented basal sea-ice melt over warm Atlantic waters and ocean-to-ice heat flux peaked at up to 400 Wm-2 in winter. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

The mooring was deployed on 25 July 2007 from the R/V Haakon Mosby at 80.601°N, 7.119°E (depth of 745 m) in the Yermak Pass over the Yermak Plateau north of Svalbard. It comprised an upward-looking RDI 75kHz Long Ranger Acoustic Doppler Current Profiler (ADCP) at 585 m with 16 m vertical resolution and a 1hour sampling time, and an ocean profiler on a taut cable between 130 and 530 m. The mooring was recovered on 23 September 2008 by the K/V Svalbard. The dataset is composed of the raw data from the ADCP, after declination correction. A white shaded zone is visible in the data between 380 and 500 m depth throughout the time series. It corresponds to the reflection of the acoustic bins on the profiler stuck on the cable.

In the Northwest Atlantic, Pandalus borealis (northern shrimp) serve as key mid-trophic consumers and prey for higher-trophic predators, including commercially important fish species. However, the impact of changing environmental conditions on trophic interactions and lipid storage in sub-Arctic ecosystems is not well understood. We employed biochemical tracers (fatty acids and stable isotopes) to investigate the trophic ecology and stage-specific nutritional condition of P. borealis across spatial and seasonal scales. A total of 68 different fatty acids (FAs) were identified in P. borealis tissues (i.e., muscle and eggs). The relative abundances of these FAs varied among sex, tissues, seasons, and fishing areas. Results revealed that P. borealis primarily fed on diatoms and zooplankton, with opportunistic feeding on sinking phytodetritus. Lipid composition showed strong seasonality, with storage triacylglycerols being the predominant lipid class. Ovigerous females exhibited the highest lipid concentrations and essential fatty acids, emphasizing the ecological importance of eggs as high-quality lipid sources. Additionally, total lipid content in eggs increased from spring to summer, highlighting vulnerability to shifts in seasonal primary production. This study underscores the significant seasonal variability in the nutritional status of P. borealis and the need to understand lipid dynamics to assess population resilience to environmental changes. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

We defined the interfaces between the air/snow, snow/ice, and ice/ocean and calculated the ocean heat flux for two SIMBA recordings (SIMBA2015a and SIMBA_2015f) of repeated temperature profiles at 6h interval and 2cm vertical resolution, during N-ICE 2015 experiment floe1. The snow/ice interface is derived from the sharp contrast in the diffusivity proxy values between both media. The snow/ice interface does not change except for slush formation associated with flooding events. The air/snow interface is calculated using simultaneous information from the vertical gradient of the temperature and the standard deviation over 24, 48, and 72 h period. Snow accumulation of more than 10 centimeters happened at different time for the 2 SIMBA. The ice/ocean interface is estimated from temperature profiles alone since the winter sea-ice remains colder than the ocean. The ocean just below the ice is at or just above the freezing temperature (estimated from a near surface conductivity-temperature-depth (CTD) sensor see Koenig et al. [2016]). The method detects (1) the first sensor, downward of the snow/ice interface, with a temperature above the ocean freezing temperature and (2) the last sensor in the ice with a temperature below the mean ocean temperature by at least twice the ocean temperature standard deviation in that profile. The ice/ocean interface is then defined as half way between the last sensor in the ice and the first sensor in the ocean. Note it take 3-4 days for the deployment hole to refreeze. Then the ice thickness remains constant up to 20 February when floe1 breaks. Simba_2015f stops working and SIMBA_2015a features basal melt events corresponding to temperature changes in the ocean. The consistency of the 3 interfaces estimate is validated with the thermal diffusivity proxy and the vertical and temporal derivatives of temperature. The ocean heat flux is derived from the latent heat flux which is directly proportional to the change in time of the ice/ocean interface depth and the conductive heat flux in the lower portion of the ice estimated 6 cm above the ice/ocean interface. The ocean heat flux values for SIMBA_2015a and SIMBA2015f range from -50 to 350 W/m2, and -50 to 150 W/m2 respectively, while the basal melt events associated with ocean temperature increase stand out in SIMBA_2015a.   The SIMBA data are available through the Norwegian Polar Institute’s data center (https://data.npolar.no/dataset/6ed9a8ca-95b0-43be-bedf-8176bf56da80) and the method of interface detection is thoroughly described in Provost et al. (2017). Note that all time series have been smoothed with a 36-h running mean.   Provost, C., N. Sennechael, J. Miguet, P. Itkin, A. Rosel, Z. Koenig, N. Villacieros-Robineau, and M. A. Granskog (2017), Observations of flooding and snow-ice formation in a thinner Arctic sea-ice regime during the N-ICE2015 campaign: Influence of basal ice melt and storms, J. Geophys. Res. Oceans, 122, 7115–7134, doi:10.1002/2016JC012011. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

We report continuous observations in the high Arctic (north of 84°N) over the full 2013 summer season at two nearby sites with distinct initial snow depth, ice thickness and altitude with respect to the local ice topography. The two sites subject to similar atmospheric conditions that did not favor strong ice melt showed a contrasted evolution. One site, with an initial thin sea ice (1.40 m) at a low location of the floe, witnessed the formation of a spectacular 1.20 m-deep melt pond, a pond-enhanced erosion of the ice surface and a sudden pond drainage into the ocean. Then, the outpoured fresh water rapidly froze, heated the old ice from below and also acted as a temporary shield from the ocean heat flux while it was progressively ablated through dissolution. Eventually, the site almost recovered its initial ice thickness. In contrast, the other site, with an initial thicker sea ice (1.75 m) at a high location of the floe, did not support any significant melt water and underwent over 0.5 m of continuous basal ablation. The two sites witnessed formation of superimposed and interposed ice. Sea-ice survived summer melt at the two sites which entered the refreezing season with similar snow and ice thicknesses. For the first time, processes associated with the formation of a deep melt pond and subsequent false bottom evolution are continuously documented with ice mass balance instruments.  Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

A mooring, equipped with a CTD sensor (SBE37) at 350 m depth, was deployed in the Yermak Pass on the 24 September 2017 from the R/V Lance. The mooring was recovered in summer 2020 from K/V Svalbard. The present dataset provides 10-day smoothed time series of daily conservative temperature (CT, °C), absolute salinity (SA, g/kg) and pressure (db) recorded by the SBE37 sensor, from the 24 September 2017 to the 31 May 2020. The mooring was located at 80.63°N, 6.88°E. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

In April 2017, two Ice Atmosphere Arctic Ocean Observing System platforms (IAOOS 23 and IAOOS 24) were deployed near the North Pole. Over the next 8 months, they meandered southwards with the ice in the Transpolar Drift, collecting measurements in the upper 250 m of Amundsen Basin, Nansen Basin and Fram Strait. The ocean profilers are PROVOR SPI (from French manufacturer NKE), which includes a Seabird SBE41 CTD (Conductivity, Temperature, Depth) and a dissolved oxygen (DO) Aandera 4330 optode. IAOOS 23 also featured a bio-optics sensor suite and a submersible ultraviolet nitrate analyzer (SUNA, Satlantic-Seabird Inc.). The bio-optics sensor suite (called Pack Rem A) combines a three-optical-sensor instrument (ECO Triplet, WET Labs Inc.) and a multispectral radiometer (OCR-504, Satlantic Inc.). The present dataset is composed of chlorophyll-a fluorescence, backscatter, irradiances (at 412, 490 and 555 nm), photosynthetically active radiation (PAR), nitrate and colored-dissolved organic matter data from the IAOOS 23 platform, as well as composites of absolute salinity, conservative temperature and apparent oxygen utilization data from both profilers. The profilers were set to perform two upward profiles a day from 250 m starting at approximately 6 am and 6 pm. In this dataset, chlorophyll-a, PAR and irradiances were corrected with a shift to set dark values to zero. Nitrate was interpolated vertically every 5 m, and all other parameters were interpolated vertically every 0.5 m. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

The two platforms IAOOS 23 and IAOOS 24 were deployed within 600 m from each other at the North Pole from the Russia-operated Barneo ice camp on April 12, 2017. They followed a meandering trajectory, reaching as far as 30°E in the Nansen Basin, before turning back to the western Fram Strait. On both IAOOS 23 and 24, the ocean profiler was a PROVOR SPI (from French manufacturer NKE) equipped with a Seabird SBE41 CTD (Conductivity, Temperature, Depth) and a dissolved oxygen (DO) Aandera 4330 optode. For the first time, the profiler on IAOOS 23 also carried biogeochemical sensors. It featured a bio-optics sensor suite and a submersible ultraviolet nitrate analyzer (SUNA, Satlantic-Seabird Inc.). The bio-optics sensor suite (called Pack Rem A) combines a three-optical-sensor instrument (ECO Triplet, WET Labs Inc.) and a multispectral radiometer (OCR-504, Satlantic Inc.). The present dataset is composed of CTD-DO data from IAOOS 23 and 24, corrected from the thermal lag and the sensor lag, despiked and interpolated vertically every 0.5 m. It also comprises nitrate concentrations from the SUNA and CDOM fluorescence from the WETLabs ECO sensor on IAOOS 23. Other biogeochemical data will be added to this dataset. The profilers were set to perform two upward profiles a day from 250 m (IAOOS 23) and 350 m (IAOOS 24) upward starting at approximately 6 am and 6 pm. They provided a unique 8-month long dataset, gathering a total of 793 profiles of the temperature, salinity and oxygen (upper 350m) and 427 profiles of CDOM and nitrates concentrations (upper 250m).   Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.