A dataset of direct observations of sea ice drift and waves in ice

Variability in sea ice conditions, combined with strong couplings to the atmosphere and the ocean, lead to a broad range of complex sea ice dynamics. More in-situ measurements are needed to better identify the phenomena and mechanisms that govern sea ice growth, drift, and breakup. To this end, we have gathered a dataset of in-situ observations of sea ice drift and waves in ice. A total of 15 deployments were performed over a period of 5 years in both the Arctic and Antarctic, involving 72 instruments. These provide both GPS drift tracks, and measurements of waves in ice. The data can, in turn, be used for tuning sea ice drift models, investigating waves damping by sea ice, and helping calibrate other sea ice measurement techniques, such as satellite based observations

Warming of Atlantic Water in three west Spitsbergen fjords: recent patterns and century-long trends

We investigated the recent warming of summer Atlantic Water in relation to the century-long trends in maximum temperature in three west Spitsbergen fjords: Isfjorden, Grønfjorden and Billefjorden. On the basis of repeated along-fjord transects in late summer 2003–2019, we found that the warming has been pronounced not only in the outer but also in the inner domain of Isfjorden, where the presence of waters of Atlantic origin was registered more frequently after 2011 compared to early 2000s. Furthermore, Atlantic waters occurred more frequently in the bottom layers in the inner part of the fjord. In all the investigated fjords, the year 2014 was the warmest and saltiest during the period 2003–2019, which is consistent with previous reports for other west Spitsbergen fjords. In 2014, the mean temperature and salinity in Isfjorden and Grønfjorden exceeded 4.9 °C and 34.7 (in Billefjorden, 4.0 °C and 34.67, respectively). With the new data for 2010–19, we extended the time-series of maximum Atlantic Water temperature in Isfjorden and Grønfjorden, covering 1912–2009, reported previously by Pavlov et al. 2013. For the period 1912–2019, the average long-term trend of Atlantic Water maximum temperature is 0.25 °C/decade and 0.22 °C/decade in the outer part of Isfjorden and Grønfjorden, respectively. In the first two decades of the 21st century, the warming trend is steeper compared to the 20th century, 0.78 °C/decade in Isfjorden and 0.56 °C/decade in Grønfjorden, highlighting the strength of the ongoing ‘Atlantification’ of west Spitsbergen fjords

TransArctic-2019 expedition ice thickness and snow height direct measurements at points of hydrological stations

Direct (contact) measurements of sea ice thickness, elevation and snow height performed at points of 59 hydrological (oceanographic) stations during the TransArctic-2019 expedition (28 March - 04 May 2019) are presented. Variables include time, geographical location (lat, lon) and measurements of minimum (imin, m) and maximum (imax, m) sea ice thickness, minimum (iemin, m) and maximum (iemax, m) sea ice elevation (above sea level), minimum (smi, m) and maximum (sma, m) snow height, hummock concentration (huct, in 1/10 of area coverage) and maximum hummocks height (humh, m). Data is presented in CSV, DBF and shapefile formats. TransArctic-2019 expedition was convened by the Arctic and Antarctic Research Institute (AARI) aboard AARI research vessel "Akademik Tryoshnikov" within the area of the Arctic Basin northward of the Franz-Josef Land archipelago. Points of the stations were the helicopter landing sites chosen on sufficiently level and thick ice along the sections at a distance of 10s-100s km from the drifting ship

Physical oceanography (CTD/Rosette) during the Akademik Tryoshnikov cruise Transarktika-2019 Leg 1 in 2019, Arctic Ocean

A standard Sea-Bird Electronics SBE911+ CTD system with a temperature and conductivity sensor was used to measure temperature, conductivity, and pressure at 180 stations during the Russian-international expedition Transarktika-2019 Leg 1 in the Barents Sea in March-May 2019 aboard the research vessel Akademik Tryoshnikov. We followed the manufacturer's recommendation to calculate salinity using Seabird processing software. The salinity is reported as Practical Salinity (PSU). Data were averaged at depth ranges of 1 m. Data are provided by the Antarctic and Arctic Research Institute (AARI) and reprocessed at the Helmholtz Centre for Polar and Marine Research, Alfred Wegener Institute. The Transarktika-2019 expedition was made possible by funding from the Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet). The scientific research was also supported by RFBR grants No. 18-05-60048 and 18-05-60083

Wave dispersion and dissipation in landfast ice: Comparison of observations against models

Abstract. Observations of wave dissipation and dispersion in sea ice are a necessity for the development and validation of wave–ice interaction models. As the composition of the ice layer can be extremely complex, most models treat the ice layer as a continuum with effective, rather than independently measurable, properties. While this provides opportunities to fit the model to observations, it also obscures our understanding of the wave–ice interactive processes; in particular, it hinders our ability to identify under which environmental conditions these processes are of significance. Here, we aimed to reduce the number of free variables available by studying wave dissipation in landfast ice. That is, in continuous sea ice, such as landfast ice, the effective properties of the continuum ice layer should revert to the material properties of the ice. We present observations of wave dispersion and dissipation from a field experiment on landfast ice in the Arctic and Antarctic. Independent laboratory measurements were performed on sea ice cores from a neighboring fjord in the Arctic to estimate the ice viscosity. Results show that the dispersion of waves in landfast ice is well described by theory of a thin elastic plate, and such observations could provide an estimate of the elastic modulus of the ice. Observations of wave dissipation in landfast ice are about an order of magnitude larger than in ice floes and broken ice. Comparison of our observations against models suggests that wave dissipation is attributed to the viscous dissipation within the ice layer for short waves only, whereas turbulence generated through the interactions between the ice and waves is the most likely process for the dissipation of wave energy for long periods. The separation between short and long waves in this context is expected to be determined by the ice thickness through its influence on the lengthening of short waves. Through the comparison of the estimated wave attenuation rates with distance from the landfast ice edge, our results suggest that the attenuation of long waves is weaker in comparison to short waves, but their dependence on wave energy is stronger. Further studies are required to measure the spatial variability of wave attenuation and measure turbulence underneath the ice independently of observations of wave attenuation to confirm our interpretation of the results

Oceanic Routing of Wind-Sourced Energy Along the Arctic Continental Shelves

Data from coastal tide gauges, oceanographic moorings, and a numerical model show that Arctic storm surges force continental shelf waves (CSWs) that dynamically link the circumpolar Arctic continental shelf system. These trains of barotropic disturbances result from coastal convergences driven by cross-shelf Ekman transport. Observed propagation speeds of 600−3000 km day–1, periods of 2−6 days, wavelengths of 2000−7000 km, and elevation maxima near the coast but velocity maxima near the upper slope are all consistent with theoretical CSW characteristics. Other, more isolated events are tied to local responses to propagating storm systems. Energy and phase propagation is from west to east: ocean elevation anomalies in the Laptev Sea follow Kara Sea anomalies by one day and precede Chukchi and Beaufort Sea anomalies by 4−6 days. Some leakage and dissipation occurs. About half of the eastward-propagating energy in the Kara Sea passes Severnaya Zemlya into the Laptev Sea. About half of the eastward-propagating energy from the East Siberian Sea passes southward through Bering Strait, while one quarter is dissipated locally in the Chukchi Sea and another quarter passes eastward into the Beaufort Sea. Likewise, CSW generation in the Bering Sea can trigger elevation and current speed anomalies downstream in the Northeast Chukchi Sea of 25 cm and 20 cm s–1, respectively. Although each event is ephemeral, the large number of CSWs generated annually suggest that they represent a non-negligible source of time-averaged energy transport and bottom stress-induced dissipative mixing, particularly near the outer shelf and upper slope. Coastal water level and landfast ice breakout event forecasts should include CSW effects and associated lag times from distant upstream winds