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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]

Ice shelf dynamics and morphology play an important role in the stability of floating bodies of ice by driving fracturing that can lead to calving, in turn impacting the ability of the ice shelf to buttress upstream grounded ice. Following a 2016 calving event at the Nansen Ice Shelf (NIS), East Antarctica, we collected airborne and ground-based radar data to map ice thickness across the shelf. We combine these data with published satellite-derived data to examine the spatial variations in ice shelf draft, the cause and effects of ice shelf strain rates, and the possibility that a suture zone may be channelizing ocean water and altering patterns of sub-ice-shelf melt and freeze-on. We also use our datasets to assess limitations that may arise from relying on hydrostatic-balance equations applied to ice surface elevation to determine ice draft morphology. We find that the Nansen Ice Shelf has a highly variable basal morphology driven primarily by the formation of basal fractures near the onset of the ice shelf suture zone. This morphology is reflected in the ice shelf strain rates but not in the calculated hydrostatic-balance thickness, which underestimates the scale of variability at the ice shelf base. Enhanced melt rates near the ice shelf terminus and in steep regions of the channelized suture zone, along with relatively thin ice in the suture zone, appear to represent vulnerable areas in the NIS. This morphology, combined with ice dynamics, induce strain that has led to the formation of transverse fractures within the suture zone, resulting in large-scale calving events. Similar transverse fractures at other Antarctic ice shelves may also be driven by highly variable morphology, and predicting their formation and evolution could aid projections of ice shelf stability. [ABSTRACT FROM AUTHOR]

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 the foraging behavior of marine animals is crucial for assessing their ecological significance and responses to environmental changes. In the context of Antarctica, marine animals face rapid and profound environmental changes related with global warming. However, our understanding of their responses remains limited owing to the formidable challenges inherent in conducting observations, particularly during the harsh austral winter months. In this study, we investigated the influence of changes in seawater properties and light conditions on the seasonal foraging behavior of Weddell seals (Leptonychotes weddellii) in the Ross Sea, Antarctica. We affixed 35 Weddell seals with CTD tags to record their locations and dive profiles, including depth, head acceleration, temperature, and salinity. We found that seals foraged more frequently in modified shelf water and ice shelf water compared to Antarctic surface water. This preference could be connected to greater food availability. Additionally, seals also dove to greater depths and displayed increased activity in capturing prey during daylight hours. This behavior may correspond to the diel vertical migration of pelagic prey in response to varying light conditions. Our findings suggest that Weddell seals have adjusted their foraging behaviors to adapt to spatial and temporal changes in oceanographic conditions. This highlights the importance of extrinsic factors in estimating their seasonal foraging behavior. [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]

Ice melting beneath Antarctic ice shelves is caused by heat transfer through the ice-shelf–ocean boundary layer (IOBL). However, our understanding of the fluid dynamics and thermohaline physics of the IOBL flow is poor. In this study, we utilize a large-eddy simulation (LES) model to investigate ocean dynamics and the role of turbulence within the IOBL flow near the ice front. To simulate the varying turbulence intensities, we imposed different theoretical profiles of the velocity. Far-field ocean conditions for the melting at the ice-shelf base and freezing at the sea surface were derived based on in situ observations of temperature and salinity near the ice front of the Nansen Ice Shelf. In terms of overturning features near the ice front, we validated the LES simulation results by comparing them with the in situ observational data. In the comparison of the velocity profiles to shipborne lowered acoustic Doppler current profiler (LADCP) data, the LES-derived strength of the overturning cells is similar to that obtained from the observational data. Moreover, the vertical distribution of the simulated temperature and salinity, which were mainly determined by the positively buoyant meltwater and sea-ice formation, was also comparable to that of the observations. We conclude that the IOBL flow near the ice front and its contribution to the ocean dynamics can be realistically resolved using our proposed method. Based on validated 3D-LES results, we revealed that the main forces of ocean dynamics near the ice front are driven by positively buoyant meltwater, concentrated salinity at the sea surface, and outflowing momentum of the sub-ice-shelf plume. Moreover, in the strong-turbulence case, distinct features such as a higher basal melt rate (0.153 m yr -1), weak upwelling of the positively buoyant ice-shelf water, and a higher sea-ice formation were observed, suggesting a relatively high speed current within the IOBL because of highly turbulent mixing. The findings of this study will contribute toward a deeper understanding of the complex IOBL-flow physics and its impact on the ocean dynamics near the ice front. [ABSTRACT FROM AUTHOR]

Pine Island Ice Shelf (PIIS) buttresses the Pine Island Glacier, the key contributor to sea-level rise. PIIS has thinned owing to ocean-driven melting, and its calving front has retreated, leading to buttressing loss. PIIS melting depends primarily on the thermocline variability in its front. Furthermore, local ocean circulation shifts adjust heat transport within Pine Island Bay (PIB), yet oceanic processes underlying the ice front retreat remain unclear. Here, we report a PIB double-gyre that moves with the PIIS calving front and hypothesise that it controls ocean heat input towards PIIS. Glacial melt generates cyclonic and anticyclonic gyres near and off PIIS, and meltwater outflows converge into the anticyclonic gyre with a deep-convex-downward thermocline. The double-gyre migrated eastward as the calving front retreated, placing the anticyclonic gyre over a shallow seafloor ridge, reducing the ocean heat input towards PIIS. Reconfigurations of meltwater-driven gyres associated with moving ice boundaries might be crucial in modulating ocean heat delivery to glacial ice. Glacial melt can modify heat transport, and therefore ocean processes, associated with ice front retreat, as revealed by direct observations from the Pine Island Bay region of Antarctica. [ABSTRACT FROM AUTHOR]

In the 2016–2017 austral summer, the University of Texas Institute for Geophysics (UTIG) and the Korea Polar Research Institute (KOPRI) collaborated to perform a helicopter-based radar and laser altimeter survey of lower David Glacier with the goals of characterizing the subglacial water distribution that supports a system of active subglacial lakes and informing the site selection for a potential subglacial access drilling project. This survey overlaps with and expands upon an earlier survey of the Drygalski Ice Tongue and the David Glacier grounding zone from 2011 and 2012 to create a 5 km resolution survey extending 200 km upstream from the grounding zone. The surveyed region covers two active subglacial lakes and includes reflights of ICESat ground tracks that extend the surface elevation record in the region. This is one of the most extensive aerogeophysical surveys of an active lake system and provides higher-resolution boundary conditions and basal characterizations that will enable process studies of these features. This paper introduces a new helicopter-mounted ice-penetrating radar and laser altimetry system, notes a discrepancy between the original surface-elevation-derived lake outlines and locations of possible water collection based on basal geometry and hydraulic potential, and presents radar-based observations of basal conditions that are inconsistent with large collections of ponded water despite laser altimetry showing that the hypothesized active lakes are at a highstand. [ABSTRACT FROM AUTHOR]

Antarctica's Getz Ice Shelf has been rapidly thinning in recent years, producing more meltwater than any other ice shelf in the world. The influx of fresh water is known to substantially influence ocean circulation and biological productivity, but relatively little is known about the factors controlling basal melt rate or how basal melt is spatially distributed beneath the ice shelf. Also unknown is the relative importance of subglacial discharge from the grounded ice sheet in contributing to the export of fresh water from the ice shelf cavity. Here we compare the observed spatial distribution of basal melt rate to a new sub-ice-shelf bathymetry map inferred from airborne gravity surveys and to locations of subglacial discharge from the grounded ice sheet. We find that melt rates are high where bathymetric troughs provide a pathway for warm Circumpolar Deep Water to enter the ice shelf cavity and that melting is enhanced where subglacial discharge fresh water flows across the grounding line. This is the first study to address the relative importance of meltwater production of the Getz Ice Shelf from both ocean and subglacial sources. [ABSTRACT FROM AUTHOR]

Terra Nova Bay in Antarctica is a formation region for high-salinity shelf water (HSSW), which is a major source of Antarctic Bottom Water. Here, we analyze spatiotemporal salinity variability in Terra Nova Bay with implications for the local HSSW production. The salinity variations in the Drygalski Basin and eastern Terra Nova Bay near Crary Bank in the Ross Sea were investigated by analyzing hydrographic data from instrumented moorings, vessel-based profiles, and available wind and sea-ice products. Near-bed salinity in the eastern Terra Nova Bay (∼660 m) and Drygalski Basin (∼1200 m) increases each year beginning in September. Significant salinity increases (>0.04) were observed in 2016 and 2017, which is likely related to active HSSW formation. According to velocity data at identical depths, the salinity increase from September was primarily due to advection of the HSSW originating from the coastal region of the Nansen Ice Shelf. In addition, we show that HSSW can also be formed locally in the upper water column (<300 m) of the eastern Terra Nova Bay through convection supplied by brine from the surface, which is related to polynya development via winds and ice freezing. While the general consensus is that the salinity of the HSSW was decreasing from 1995 to the late 2000s in the region, the salinity has been increasing since 2016. In 2018, it returned to values comparable to those in the early 2000s. [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]