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.

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.

The mooring was deployed on 15 September 2017 from Norwegian Research Vessel Lance at 80.6°N and 7.26°E (depth of 730 m) in the Yermak Pass over the Yermak Plateau north of Svalbard. It comprised 3 instruments: an upward-looking RDI 75kHz, a Long Ranger Acoustic Doppler Current Profiler (ADCP) at 340 m with 16 m vertical resolution (25 bins of 16 m each) and a 2-hour sampling time; a Seabird SBE37 measuring temperature, salinity and pressure at 348 m with 10-minute sampling time; and an Aquadopp current meter at 645 m with a 2-hour sampling time. The mooring was retrieved on the 19 July 2020 by Norwegian Icebreaker K.V. Svalbard. The present dataset features: The ADCP 50-hour high pass filtered velocities and  the Aquadopp 50-hour high pass filtered velocities. 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.