Search

A three-day workshop was held in Gwangmyeong, South Korea, to discuss recent advances in sea ice modeling. Researchers from South Korea, China, Australia, Canada, Belgium, France, Italy, and Norway attended the workshop. The workshop focused on four themes: emerging model technologies, the role of artificial intelligence (AI) in sea ice applications, model/observation integration, and future research needs and opportunities. The use of AI techniques in sea ice research and forecasting was highlighted, including applications such as forecasting sea ice concentration and thickness, correcting biases in atmospheric boundary conditions, and detecting landfast sea ice. The workshop also emphasized the need for collaboration across geographies and highlighted the research bubbles that exist in different regions. The workshop provided a valuable forum for collaboration and knowledge sharing, and a follow-up workshop is planned for fall 2025. [Extracted from the article]

High Salinity Shelf Water (HSSW) formed in the Ross Sea of Antarctica is a precursor to Antarctic Bottom Water (AABW), a water mass that constitutes the bottom limb of the global overturning circulation. HSSW production rates are poorly constrained, as in-situ observations are scarce. Here, we present high-vertical-and-temporal-resolution salinity time series collected in austral winter 2017 from a mooring in Terra Nova Bay (TNB), one of two major sites of HSSW production in the Ross Sea. We calculate an annual-average HSSW production rate of ~0.4 Sv (106m3s−1), which we use to ground truth additional estimates across 2012–2021 made from parametrized net surface heat fluxes. We find sub-seasonal and interannual variability on the order of 0.1 S v , with a strong dependence on variability in open-water area that suggests a sensitivity of TNB HSSW production rates to changes in the local wind regime and offshore sea ice pack. Antarctic Bottom Water ventilates the deep ocean, but studies of its source regions are limited due to scarce observations. Miller et al. leverage mooring data to quantify the production rate of a key constituent water mass produced in the Ross Sea. [ABSTRACT FROM AUTHOR]

Understanding ice shelf water (ISW) structure is crucial for studying the basal melting of ice shelves. In this study, we performed large‐eddy simulation experiments to assess ISW structure and basal melt patterns under different current velocity scenarios observed in the Larsen C ice shelf, Antarctica. The LES results revealed that the thickness of ISW is primarily determined by the meridional velocity (perpendicular to the grounding line), while the zonal velocity influences the potential temperature and salinity of ISW. We found that a key parameter determining the basal melt rate was northward meltwater advection which originates from variances in meltwater generation. This advection, in turn, leads to the tilted isopycnals and the potential for thermohaline interleaving in a diffusive convection regime. The different slopes of isopycnals induce distinct heat fluxes, resulting in different basal melt rates far from and near the grounding line (∼0.44 and 1.59 m yr−1, respectively). Plain Language Summary: The loss of ice mass from the Antarctic ice sheet is accelerating, posing a threat to human lives through global sea level rise. Understanding ice shelf water (ISW), which refers to seawater below freezing temperature, is crucial as it directly or indirectly influences basal ice melting. However, direct observations are extremely challenging, leaving this understanding unclear. To tackle this issue, we utilized a numerical model to gain insight into the fundamental characteristics of ISW. We demonstrated that the direction and magnitude of ocean currents beneath the ice shelf play a significant role in determining the thickness and properties of ISW. Moreover, the key factor in basal melting was the northward movement of meltwater from intense ice melting regions near the grounding line. This movement determined the spatial distribution of ocean temperature and salinity. The horizontal gradient of ocean temperature and salinity induces mixing and horizontal intrusion. Interestingly, these mixing and intrusion phenomena occur in opposite directions, resulting in a wiggling pattern in the velocity profile. The main findings of our study will contribute to the formulation of a parameterization for basal melting, which can be incorporated into large‐scale ocean models or ice sheet dynamics models. Key Points: Direction and magnitude of ocean currents beneath an Larsen C ice shelf affect the ice shelf water thickness and propertiesNorthward meltwater advection causes 0.052°C difference of thermal drivings with different melt rates far from and near the grounding lineOcean heat intrusion to ice shelf base is induced by Ekman dynamics and thermohaline interleaving by tilted isopycnals [ABSTRACT FROM AUTHOR]

West Antarctica exhibits a pronounced sea ice variability in interannual timescale, and 20%–30% of the total variance can be explained by the El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) during austral spring. The sea ice variation is primarily linked with anomalous atmospheric circulation in the Amundsen‐Bellingshausen Sea (ABS) that modulates poleward atmospheric temperature advection and radiative forcing. With a co‐varying relationship between ENSO and IOD, isolating their remote impacts on Antarctica has been limited in observations. An idealized experiment using the atmospheric model with a dry dynamical core suggests that the anticyclonic circulation anomaly in the ABS is primarily contributed by the ENSO in the Pacific Ocean, while the contribution of the IOD in the Indian Ocean is only one‐third large. This study implies that atmospheric teleconnection through the southern Pacific Ocean is crucial for understanding the West Antarctic sea ice concentration variability. Plain Language Summary: Antarctic sea ice, which affects the Earth's climate system, has gained considerable attention in recent years. Previous studies have shown that the El Nino‐Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) in the tropics affect the sea ice variation in West Antarctica through atmospheric teleconnections at interannual timescale. Unfortunately, due to the high positive correlation between these two climate modes, it is unclear how each phenomenon contributes to the West Antarctic sea ice variation. Therefore, this study investigates the underlying mechanisms related to the sea ice changes caused by ENSO and IOD during austral spring and quantifies the effect of each phenomenon on the West Antarctic sea ice through an idealized model experiment. It is found that the ENSO and the IOD account for 20%–30% of sea ice variance during austral spring, which is primarily contributed by the dynamic and thermodynamic mechanisms associated with atmospheric circulation in the Amundsen‐Bellingshausen Sea (ABS). In addition, we confirm through the model experiments that the effect of ENSO in the Pacific Ocean on the atmospheric circulation patterns of ABS is about three times stronger than that of IOD in the Indian Ocean. Key Points: El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) account for 20%–30% of the variability in total sea ice concentration in austral springThe tropical variability affects circulation anomalies in the Amundsen‐Bellingshausen Sea, leading to sea ice variations in West AntarcticaAn idealized atmospheric model experiment suggests the ENSO effect on the West Antarctic circulation is much stronger than the IOD [ABSTRACT FROM AUTHOR]

Supra- and sub-glacial meltwater drainage becomes widespread in Antarctica, but its contribution to regional water masses has not been thoroughly quantified. For a better understanding of physical-chemical fractionations, we employ water isotopes (δ18O, δD) as practical tracers for hydrological researches. During the Antarctic summer expeditions (2014/15, 2015/16, 2016/17, and 2017/18) conducted by Korea Polar Research Institute, we sampled seawater performed with CTD casts in the Terra Nova Bay, Western Ross Sea. Picarro L2301-i CRDS is used for water isotope analysis, and preliminary results represent that sampled glacial meltwater contains both terrestrial meltwater and fresh water from ice shelf basal melting. The relationship of δ18O and δD shows the slope value around less than 7 (P1: δD=6.74×δ18O-0.02), however, the glacial meltwater shows the value around 8 (P1:δD=7.69×δ18 O+0.41). Water isotope differentiated presenting various values relative to given salinity. The various values of water isotopes imply other differentiation factors like evaporation and sea ice formation occurred. [ABSTRACT FROM AUTHOR]

We describe the first year-long hydrographic mooring timeseries from a location just to the south of the Drygalski Ice Tongue – the ice margin that forms the southern boundary of the Terra Nova Bay Polynya in the western Ross Sea. The region is where any northward flowing component of the Victoria Land Coastal Current encounters the ice tongue and supports an occasional polynya. The hydrographic mooring was deployed nearby Geikie Inlet from February 2017 through to March 2018, and was coupled with several contemporaneous oceanographic moorings to the north of the Drygalski Ice Tongue. This provides data with which to examine the water column dynamics in the context of local circulation and interaction with the ice tongue. The Terra Nova Bay region is subject to strong katabatic winds, however the polynya to the south of the Drygalski Ice Tongue operates at different times through the annual cycle when compared to the Terra Nova Bay Polynya to the north, as the sea ice in the south-side region is far more constrained in its motion yet, temperature and salinity are broadly consistent north and south of the ice tongue. Sub-surface Ice Shelf Water is observed south of the ice tongue. Transients in near-bed temperature and salinity are observed on both sides of the ice tongue, albeit with the northside leading by ∼8–9 days. Notably, the temperature transient precedes that of salinity by around 40 days. This suggests that, at this near-coastal position, the circulation beneath the ice tongue is primarily southward. [ABSTRACT FROM AUTHOR]

The Drygalski Ice Tongue is one of the largest ice tongues in Antarctica, extending 140 km into the Ross Sea. The ice tongue prevents the break up of sea ice within the Ross Sea and may also impact polynya formation within Terra Nova Bay to the North. We use a combination of remote sensing techniques and numerical modelling to examine the stability of the ice tongue.In 2005, iceberg B15-A collided with the tongue terminus, breaking off a large section of ice. In 2006, iceberg C-16 collided with the terminus, resulting in a total loss of 11 km in length from both calving events. These events have been captured in Landsat 7, MODIS, and ENVISAT ASAR imagery and provide an opportunity to examine pre- and post-calving properties of the ice tongue to determine how the tongue reacts after large mass loss. We use Landsat GoLIVE products from 2014 to 2017 to calculate ice strain, which we compare with the location of basal channels identified from aerial ice penetrating radar surveys and inversion of surface DEMs. We also apply feature tracking to four large crevasses using Landsat imagery from 1988 to 2017 to determine velocity along the tongue and rate of change of the frontal position. Water flux rates and subglacial channel location over the grounding line are determined by applying the Glacier Drainage System (GlaDS) model to the David Glacier catchment, which feeds into Drygalski Ice Tongue. Preliminary results suggest that there is a relationship between calving events, ice tongue velocity, and formation of new crevasses. These crevasses in turn control the location of future calving. There is also a relationship between basal channel location and ice surface strain rates, which may impact the transverse propagation distance of the marginal crevasses. [ABSTRACT FROM AUTHOR]