The Green Edge project was designed to investigate the onset, life and fate of a phytoplankton spring bloom (PSB) in the Arctic Ocean. The lengthening of the ice-free period and the warming of seawater, amongst other factors, have induced major changes in arctic ocean biology over the last decades. Because the PSB is at the base of the Arctic Ocean food chain, it is crucial to understand how changes in the arctic environment will affect it. Green Edge was a large multidisciplinary collaborative project bringing researchers and technicians from 28 different institutions in seven countries, together aiming at understanding these changes and their impacts on the future. The fieldwork for the Green Edge project took place over two years (2015 and 2016) and was carried out from both an ice camp and a research vessel in the Baffin Bay, Canadian arctic. Here, we describe the data set obtained during the research cruise, which took place aboard the Canadian Coast Guard Ship (CCGS) Amundsen in spring 2016. 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 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.

The MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon fluxes in the Mackenzie River estuary and the Beaufort Sea. During the campaign, an extensive suite of physical, chemical and biological variables was measured across seven shelf–basin transects (south-north) to capture the meridional gradient between the estuary and the open ocean. Key variables such as temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll-a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured onboard the Canadian research icebreaker CCGS Amundsen and from a barge in shallow coastal areas or for sampling within broken ice fields. This dataset is the results of a joint effort to tidy and standardize the collected data sets that will facilitate their reuse in further studies of the changing Arctic Ocean. 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.

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.

The dataset represents data primary processing of zoobenthos samples taken in the Chaun Bay of the East Siberian Sea in October 2020 during an expedition onboard R/V "Akademik Oparin" 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 gathered ocean profiles during the first two floes of the N-ICE2015 ice camp north of Svalbard with IAOOS ocean profilers. Between January and March 2015, four ocean profilers were deployed: two below a full IAOOS platform (500 m long cable) during floe 1, two on an 800 m long instrumented line in a tent-covered testing-hole during floe1 and floe 2. The ocean profilers, from French manufacturer NKE (PROVOR SPI), carried a Seabird SBE41CP CTD (Conductivity, Temperature, Depth) with an Aanderaa 4330 optode for dissolved oxygen (DO). The profilers were set to perform two profiles a day from 500 m upward (800 m from testing hole) starting at 6 am and 6 pm. They provided the first winter data in the region with a total of 138 profiles during floe 1 (January 15- February 21) with 62, 50, and 26 profiles for IAOOS7, IAOOS8, and IAOOS 9, respectively and 16 profiles during floe 2 (February 24 - March 19- IAOOS 11 from testing hole). Following quality control, we retain all the temperature profiles and remove 1% of the salinity profiles. Finally, the accuracy is estimated to be 0.002°C in temperature, and 0.02 g/kg in salinity. Several profiles are missing or incomplete because of high drift speeds (> 0.4 m s-1) impeding the ascent of the profiler. There are no bottle DO measurements during Floe 1 to calibrate the DO data. DO accuracy is estimated comparing the deep values of DO concentration (rather stable at 500m) between the three profilers. A difference of 3 µmol L-1 is observed between IAOOS 8 and 9, and IAOOS 7. An offset of 3 µmol L-1 is then applied to the oxygen data from IAOOS7 and the accuracy of the data is estimated to be at ±3 µmol L-1. The vertical resolution of the processed CTD data is 1 dbar in the upper 400 dbars, 5 dbars from 400 to 550 dbars and 10 dbars from 550 to 850 dbars. The vertical resolution in dissolved oxygen is 2 dbars over all depths. 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.

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.

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.