Abstract Arctic outflow winds bring cold air from the continent to the coastline through mountain passes. Using observational data and a 2‐D model, we show that a February 2019 outflow event caused the upper 100 m in Bute Inlet, British Columbia (within the traditional territory of the Homalco Nation) to cool up to 1.9°C and gain up to 4.1 mLL−1 of oxygen. The cold, oxygenated water persisted for almost 1 year within the 1,023–1,023.5 kgm−3 isopycnal range (∼50–150 m). Atmospheric (from 1929 to 2022) and oceanographic (from 1951 to 2022) data showed a statistically significant relationship between continental air temperature at Tatlayoko Lake and temperature and oxygen in Bute Inlet. This local mechanism that counters some effects of climate change could create a biological refugium as surrounding waters warm and lose oxygen at a faster rate. The number of outflow events decreased from 1951 to 2018, and increased since.

Liquid inclusions in sea ice are variable and dependent on the myriad of physical conditions of the atmosphere–sea ice environment in which the sea ice was grown, and whether or not melting processes affected the sea ice. In that light, there exist relatively few observations and resultant quantification of the morphology and vertical distribution of brine inclusions in sea ice. Using a magnetic (3.0 T) resonance (MR) imager using constructive interference steady state gradient echo sequence, we show that it is possible to image brine channels and pockets in an 18.5 cm young sea ice core in three-dimensions in only four and a half minutes following core storage at − 20 °C. We present a three-dimensional image of a brine drainage channel feature in a young sea ice core, give the physical context for its formation by presenting the physical conditions of the atmosphere and water/sea ice prior to sea ice growth through the sampling date, and observe its physical characteristics. We illustrate that brine drainage channels may be established concurrently with ice growth, and indicate the amount and location of vertical and horizontal fluid connectivity in the young sea ice sample in the context of the environment in which it grew. Finally, we show that a vertical brine volume distribution profile can be calculated using MR image data, extending the (non-imaging) nuclear magnetic resonance work of others in this vein.

Ikaite (CaCO3 · 6H2O) is a metastable phase of calcium carbonate that normally forms in a cold environment and/or under high pressure. Recently, ikaite crystals have been found in sea ice, and it has been suggested that their precipitation may play an important role in air–sea CO2 exchange in ice-covered seas. Little is known, however, of the spatial and temporal dynamics of ikaite in sea ice. Here we present evidence for highly dynamic ikaite precipitation and dissolution in sea ice grown at an outdoor pool of the Sea-ice Environmental Research Facility (SERF) in Manitoba, Canada. During the experiment, ikaite precipitated in sea ice when temperatures were below −4 °C, creating three distinct zones of ikaite concentrations: (1) a millimeter-to-centimeter-thin surface layer containing frost flowers and brine skim with bulk ikaite concentrations of >2000 μmol kg−1, (2) an internal layer with ikaite concentrations of 200–400 μmol kg−1, and (3) a bottom layer with ikaite concentrations of <100 μmol kg−1. Snowfall events caused the sea ice to warm and ikaite crystals to dissolve. Manual removal of the snow cover allowed the sea ice to cool and brine salinities to increase, resulting in rapid ikaite precipitation. The observed ikaite concentrations were on the same order of magnitude as modeled by FREZCHEM, which further supports the notion that ikaite concentration in sea ice increases with decreasing temperature. Thus, varying snow conditions may play a key role in ikaite precipitation and dissolution in sea ice. This could have a major implication for CO2 exchange with the atmosphere and ocean that has not been accounted for previously.

Although gypsum has been predicted to precipitate in sea ice, it has never been observed. Here we provide the first report on gypsum precipitation in both experimental and natural sea ice. Crystals were identified by X-ray diffraction analysis. Based on their apparent distinguishing characteristics, the gypsum crystals were identified as being authigenic. The FREeZing CHEMistry (FREZCHEM) model results support our observations of both gypsum and ikaite precipitation at typical in situ sea ice temperatures and confirms the Gitterman pathway where gypsum is predicted to precipitate. The occurrence of authigenic gypsum in sea ice during its formation represents a new observation of precipitate formation and potential marine deposition in polar seas.

Abstract. In order to determine the morphology and distribution of liquid inclusions in young sea ice, magnetic resonance imaging of an 18 cm sea ice core was done using a Siemens 3T TIM TRIO human scanner. The sample was stored at about −20 °C until the beginning of a constructive interference steady state gradient echo sequence which lasted four and a half min. Here we present the first three-dimensional reconstruction of a brine drainage channel network in young sea ice using magnetic resonance imaging. The magnetic resonance image sequence data presented here clearly illustrate that brine drainage channels are established relatively quickly during ice formation, and indicates the amount and location of vertical and horizontal fluid permeability in young sea ice. A simple analysis of the image sequence reveals that magnetic resonance imaging is useful in describing the vertical profile of liquid fraction that compares well to volumes calculated for similar sea ice temperatures. Future work in this vein may include three-dimensional magnetic resonance scans of sea ice cores at in situ temperatures using different magnetic resonance sequences in order to improve the observation of inclusions, though this will necessitate both access to a scanner and the construction of a cooling system compatible with a magnetic resonance imager.

Introduction Conclusions References

The pH of sea ice and brine was experimentally determined during initial ice growth and melt at the Sea-ice Environmental Research Facility (SERF), an outdoor experimental sea ice facility in Winnipeg, Canada. pH measurements were performed potentiometrically and spectroscopically at near-freezing temperatures. Vertical pH profiles from bulk ice cores revealed a consistent C-shaped pattern during columnar ice growth, with highest pH values (>9) in both exterior (top and bottom) ice sections and in frost flowers, and lowest pH (~7) in interior ice sections. Brine pH typically remained below that of the source seawater pH (~8.4). The distinct differences between these ice features and the underlying seawater source demonstrate the effect of the natural freezing process and associated changes in the CO2-carbonate system on the pH of the sea ice environment. Interpreting this effect provides new insight into the conditions leading to CO2 exchange across the ocean–sea ice–atmosphere interface. A conceptual model of pH evolution in seawater, sea ice and brine, and frost flowers is proposed to explain the observed pH characteristics of seawater components during sea ice growth and melt.