BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Hannah Zanowski (University of Colorado Boulder) DTSTART:20200909T140000Z DTEND:20200909T150000Z DTSTAMP:20260404T110911Z UID:BAS-PO/1 DESCRIPTION:Title: Arctic Freshwater Storage and Export in CMIP6 Models\nby Hannah Zanowski (University of Colorado Boulder) as part of BAS Polar Oceans Semi nar\n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Margaret Lindeman (Scripps Institute of Oceanography) DTSTART:20200923T150000Z DTEND:20200923T160000Z DTSTAMP:20260404T110911Z UID:BAS-PO/2 DESCRIPTION:Title: Observing Iceberg Melt in a Greenland Fjord\nby Margaret Lindema n (Scripps Institute of Oceanography) as part of BAS Polar Oceans Seminar\ n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Rebecca Jackson (Rutgers University) DTSTART:20201007T130000Z DTEND:20201007T140000Z DTSTAMP:20260404T110911Z UID:BAS-PO/3 DESCRIPTION:Title: Melting and mixing at the submarine termini of tidewater glaciers\nby Rebecca Jackson (Rutgers University) as part of BAS Polar Oceans Sem inar\n\n\nAbstract\nAround the globe\, glaciers and ice sheets are shrinki ng and contributing to sea level rise. Ocean warming has been implicated a s a driver of glacier retreat\, with submarine melting as the presumed lin k. However\, at the termini of tidewater glaciers\, we lack observations o f submarine melting or the oceanic processes that control melt. Instead\, many studies rely on untested theory and parameterizations to estimate sub marine melt rates. These frameworks often hinge on buoyant plumes\, whose small-scale dynamics can modulate both the ocean’s impact on the glacier via submarine melting and the glacier’s impact on the ocean via buoyanc y forcing. In this talk\, I will present data collected near the terminus of LeConte Glacier\, Alaska to probe the standard theory for plume-driven melt. In the first half\, I will present surveys from autonomous kayaks th at reveal ubiquitous meltwater intrusions along the terminus and suggest a mechanism to explain melt rates that are significantly higher than standa rd theory predicts. In the second half\, the bulk fluxes of submarine melt and subglacial discharge are evaluated across a wide range of conditions in six field campaigns to test the theoretical relationship between these two sources of freshwater. Modifications to the standard melt parameteriza tions are explored\, in an effort to work towards an updated representatio n of melt in ocean-glacier models.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Mitch Bushuk (Geophysical Fluid Dynamics Laboratory) DTSTART:20201021T130000Z DTEND:20201021T140000Z DTSTAMP:20260404T110911Z UID:BAS-PO/4 DESCRIPTION:Title: Seasonal prediction and predictability of regional Antarctic sea ice \nby Mitch Bushuk (Geophysical Fluid Dynamics Laboratory) as part of B AS Polar Oceans Seminar\n\n\nAbstract\nCompared to the Arctic\, seasonal p redictions of Antarctic sea ice have received relatively little attention. In this talk\, I will use three coupled dynamical prediction systems deve loped at the Geophysical Fluid Dynamics Laboratory to assess the seasonal prediction skill and predictability of Antarctic sea ice. These systems\, based on the FLOR\, SPEAR-lo\, and SPEAR-med dynamical models\, differ in their coupled model components\, initialization techniques\, atmospheric r esolution\, and model biases. This allows for an investigation of these fa ctors in determining Antarctic sea ice prediction skill. Using suites of r etrospective initialized seasonal predictions spanning 1992-2018\, we find that each system is capable of skillfully predicting regional Antarctic s ea ice extent (SIE) with skill that generically exceeds that of a persiste nce forecast. Winter SIE is skillfully predicted up to 11 months in advanc e in the Weddell\, Amundsen and Bellingshausen\, Indian\, and West Pacific sectors\, whereas winter skill is notably lower in the Ross sector. Zonal ly advected upper ocean heat content anomalies are found to provide the cr ucial source of prediction skill for the winter sea ice edge position. The SPEAR systems are notably more skillful than FLOR for summer sea ice pred ictions\, owing to improvements in sea ice concentration and sea ice thick ness initialization. Summer Weddell SIE can be skillfully predicted up to 8 months in advance in SPEAR-med\, due to the persistence and drift of ini tialized sea ice thickness anomalies from the previous winter. Overall\, t hese results suggest a promising potential for providing operational regio nal Antarctic sea ice predictions on seasonal timescales.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Luwei Yang (University of California\, Los Angeles) DTSTART:20201104T150000Z DTEND:20201104T160000Z DTSTAMP:20260404T110911Z UID:BAS-PO/5 DESCRIPTION:Title: The impact of lee waves on the Southern Ocean circulation and its re sponse to winds\nby Luwei Yang (University of California\, Los Angeles ) as part of BAS Polar Oceans Seminar\n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Georgy Manucharyan (University of Washington) DTSTART:20201118T160000Z DTEND:20201118T170000Z DTSTAMP:20260404T110911Z UID:BAS-PO/6 DESCRIPTION:Title: SubZero: Floe-Resolving Sea Ice Model\nby Georgy Manucharyan (Un iversity of Washington) as part of BAS Polar Oceans Seminar\n\n\nAbstract\ nSea ice is commonly represented in climate models as a continuous fluid w ith prescribed rheological properties aimed to represent its motion at rel atively large scales\, O(100km). However\, at relatively small scales\, O( 10 km) and less\, sea ice consists of a collection of strongly interacting floes that undergo frequent fractures leading to large-scale motion. Here \, I will present a prototype of a new sea ice model (SubZero) that explic itly simulates the lifecycle of individual sea ice floes. Its various capa bilities will be demonstrated and physical parameterizations will be discu ssed\, including floe fractures\, welding\, creation from the open ocean\, etc. The key advantage of this model is that its evolution equations can\ , in principle\, be constrained from observations for each individual proc ess parameterization\, and hence it could present a valuable alternative t o existing rheological models\, the parameters of which do not represent e xplicitly observable quantities.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Madi Rosevear (University of Tasmania) DTSTART:20201202T100000Z DTEND:20201202T110000Z DTSTAMP:20260404T110911Z UID:BAS-PO/7 DESCRIPTION:Title: Fine-scale ocean processes in the basal melting of Antarctic ice she lves\nby Madi Rosevear (University of Tasmania) as part of BAS Polar O ceans Seminar\n\n\nAbstract\nThe Antarctic Ice Sheet\, which comprises the largest volume of ice on our planet\, is losing mass due to ocean-driven melting of its fringing ice shelves. Efforts to represent the effects of b asal melting in sea level projections are undermined by poor understanding of the turbulent ice shelf-ocean boundary layer (ISOBL)\, a meters-thick band of ocean that regulates heat and salt transfer between the ambient oc ean and the ice. Ocean-climate models cannot resolve the ISOBL and rely on parameterisations to predict melting. However\, observations suggest that common ISOBL parameterisations only perform well in cold\, energetic ocea n environments.\n\nIn this talk I will summarise some of the main findings of my PhD thesis\, which uses both observational data and turbulence-reso lving model simulations to characterise melting and ISOBL dynamics across a broad range of ocean states. The observational data comprises unique oce an and in situ basal melt rate observations from beneath the Amery Ice She lf. The modelling focuses on the ISOBL and is performed using resolved lar ge-eddy simulation. The model domain consists of a horizontal ice-ocean in terface underlain by a stratified ocean\, and is forced by a steady flow i n geostrophic balance. Using these model simulations\, I investigate the c oupled ISOBL and melting response to ocean temperature and current forcing . Depending on the relative strength of the thermal and current forcing\, I find that the ISOBL may be characterized as either “well-mixed” \, “stratified” or “double-diffusive”. I use these results to develop a novel regime diagram for the ISOBL\, which provides new insight into th e varied and nonlinear melting responses expected around Antarctica\, depe nding on the local conditions. Comparison to observed sub-ice shelf condit ions and melt rates is favorable and demonstrates the relevance of these r egimes over a broad range of realistic conditions.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/7/ END:VEVENT BEGIN:VEVENT SUMMARY:Anna Wåhlin (University of Gothenburg) DTSTART:20210113T140000Z DTEND:20210113T150000Z DTSTAMP:20260404T110911Z UID:BAS-PO/8 DESCRIPTION:Title: An AUV underneath the ‘Doomsday glacier’: Revealing pathways and modification of warm water flowing beneath Thwaites ice shelf\, West Anta rctica\nby Anna Wåhlin (University of Gothenburg) as part of BAS Pola r Oceans Seminar\n\n\nAbstract\nThe fate of the West Antarctic Ice Sheet i s the largest remaining uncertainty in predicting sea-level rise through t he next century\, and its most vulnerable and rapidly changing outlet is T hwaites Glacier. Because the seabed slope under the glacier is retrograde (downhill inland)\, ice discharge from Thwaites Glacier is potentially uns table to melting of the underside of its floating ice shelf and grounding line retreat\, both of which can be enhanced by warm ocean water circulati ng underneath the ice shelf. Here we present the results of two missions u nderneath Thwaites ice shelf performed by the AUV ‘Ran’: The very firs t direct observations of ocean temperature\, salinity\, and oxygen underne ath Thwaites ice shelf. Using the high precision environment payload suite \, observations were obtained that indicate deep water (> 800 m) underneat h the central part of the ice shelf is in connection with Pine Island Bay\ , a previously unknown westward branch of warm deep water entering the ice shelf cavity. Warm water also enters from the north in two troughs separa ted by a pinning point. Spatial gradients of salinity\, temperature and ox ygen recorded underneath the ice shelf indicate that this is an active reg ion where several water masses meet and mixes. The observations identify t he central buttressing point as a vulnerable region of change currently un der attack by warm water inflow from all sides: a scenario that may lead t o ungrounding and retreat more quickly than previously expected.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Rachael Sanders (British Antarctic Survey) DTSTART:20210127T140000Z DTEND:20210127T150000Z DTSTAMP:20260404T110911Z UID:BAS-PO/9 DESCRIPTION:by Rachael Sanders (British Antarctic Survey) as part of BAS P olar Oceans Seminar\n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/9/ END:VEVENT BEGIN:VEVENT SUMMARY:Shenjie Zhou (British Antarctic Survey) DTSTART:20210210T140000Z DTEND:20210210T150000Z DTSTAMP:20260404T110911Z UID:BAS-PO/10 DESCRIPTION:Title: Ocean’s response to the stochastic atmospheric forcing\nby Sh enjie Zhou (British Antarctic Survey) as part of BAS Polar Oceans Seminar\ n\n\nAbstract\nThe ocean is forced by the atmosphere on a range of spatial and temporal scales. In ocean and climate models the resolution of the at mospheric forcing sets a limit on the scales that are represented. For typ ical climate models this means mesoscale (< 400 km) atmospheric forcing is absent. Previous studies have demonstrated that mesoscale forcing signifi cantly affects key ocean circulation systems such as the North Atlantic Su bpolar gyre and the Atlantic Meridional Overturning Circulation (AMOC). Ho wever\, the approach of these studies has either been ad hoc or limited in resolution. Here we present ocean model simulations with and without real istic mesoscale atmospheric forcing that represents scales down to 10 km. We use a novel stochastic parameterization – based on a cellular automat on algorithm that is common in weather forecasting ensemble prediction sys tems – to represent spatially coherent weather systems over a range of s cales\, including down to the smallest resolvable by the ocean grid. The p arameterization is calibrated spatially and temporally using marine wind o bservations. The addition of mesoscale atmospheric forcing leads to cohere nt patterns of change in the sea surface temperature and mixed-layer depth . It also leads to non-negligible changes in the volume transport in the N orth Atlantic subtropical gyre (STG) and subpolar gyre (SPG) and in the AM OC. A non-systematic basin-scale circulation response to the mesoscale win d perturbation emerges – an in-phase oscillation in northward heat trans port across the gyre boundary\, partly driven by the constantly enhanced S TG\, correspoding to an oscillatory behaviour in SPG and AMOC indices with a typical time scale of 5-year\, revealing the importance of ocean dynami cs in generating non-local ocean response to the stochastic mesoscale atmo spheric forcing. Atmospheric convection-permitting regional climate simula tions predict changes in the intensity and frequency of mesoscale weather systems this century\, so representing these systems in coupled climate mo dels could bring higher fidelity in future climate projections.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/10/ END:VEVENT BEGIN:VEVENT SUMMARY:Peter Washam (Georgia Institute of Technology) DTSTART:20210224T140000Z DTEND:20210224T150000Z DTSTAMP:20260404T110911Z UID:BAS-PO/11 DESCRIPTION:Title: A synthesis of Antarctic ice-ocean boundary observations from the u nderwater vehicle Icefin\nby Peter Washam (Georgia Institute of Techno logy) as part of BAS Polar Oceans Seminar\n\n\nAbstract\nThe accumulated m ass loss from the Earth’s cryosphere currently represents the largest co ntribution to global sea level rise. A large portion of this mass loss is driven by physical processes occurring at the marine margin of the Antarc tic and Greenland ice sheets\, where the ice sheet interacts with the ocea n. However\, there are extremely limited direct observations of the ice-oc ean interface where these two physical environments meet. Here we synthesi ze three years of ice and ocean observations in Antarctica from McMurdo So und and beneath the Ross and Thwaites ice shelves\, using hydrographic and sonar data\, and video footage from the underwater vehicle Icefin. Near-i ce ocean conditions vary between these environments from below freezing to greater than two degrees above freezing\, with considerable variability i n current velocities. Ice base morphology likewise varies within and betwe en environments\, with ablating ice forming scallops\, runnels\, and terra ces with horizontal scales of meters and vertical scales of centimeters to meters. Supercooled waters in turn form marine ice platelets\, which accu mulate in both unconsolidated and rigid bulbous masses observed at meter s cales. These variations in ice basal roughness affect the turbulent transf er of heat and salt from the ocean to the ice\, and represent one of the m ost poorly constrained parameters in the equations that describe ice-ocean interactions. Our results provide direct observations of the ice-ocean bo undary in several environments\, and therefore inform on these processes t hat are critical for the future behavior of the Antarctic and Greenland ic e sheets\, as well as other peripheral ice caps that contain marine-termin ating outlet glaciers.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/11/ END:VEVENT BEGIN:VEVENT SUMMARY:Wilma Huneke (Australian National University) DTSTART:20210324T090000Z DTEND:20210324T100000Z DTSTAMP:20260404T110911Z UID:BAS-PO/13 DESCRIPTION:Title: Spatial and temporal variability of the Antarctic Slope Current in an eddying ocean-sea ice model\nby Wilma Huneke (Australian National U niversity) as part of BAS Polar Oceans Seminar\n\n\nAbstract\nThe basal me lt rate of Antarctica's ice shelves is largely controlled by heat delivere d from the Southern Ocean to the Antarctic continental shelf. The Antarcti c Slope Current (ASC) is an almost circumpolar feature that encircles Anta rctica along the continental shelf break in an anti-clockwise direction. B ecause the circulation is to first order oriented along the topographic sl ope\, it inhibits exchange of water masses between the Southern Ocean and the Antarctic continental shelf and thereby impacts cross-slope heat suppl y. Direct observations of the ASC system are sparse\, but indicate a highl y variable flow field both in time and space. Given the importance of the circulation near the shelf break for cross-shelf exchange of heat\, it is timely to further improve our knowledge of the ASC system. This study make s use of the global ocean-sea ice model ACCESS-OM2-01 with a 1/10 degree h orizontal resolution and describes the spatial and temporal variability of the velocity field. We categorise the modelled ASC into three different r egimes\, similar to previous works for the associated Antarctic Slope Fron t: (i) A surface-intensified current found predominantly in East Antarctic a\, (ii) a bottom-intensified current found downstream of the dense shelf water formation sites in the Ross\, Weddell\, and Prydz Bay Seas\, and (ii i) a reversed current found in West Antarctica where the eastward flowing Antarctic Circumpolar Current impinges onto the continental shelf break. W e show that the regional distribution of the ASC regimes aligns well with that of the frontal structures. Looking at the temporal variability\, we f ind differences in the seasonal characteristics for each regime. The surfa ce-intensified ASC exhibits the largest seasonal variability with larger v elocities in the autumn and winter months as a response to the variability in the wind field. As a final addendum\, note that both spatial and tempo ral variability is extensive within each ASC regime.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/13/ END:VEVENT BEGIN:VEVENT SUMMARY:Andrea Rochner (University of Exeter) DTSTART:20210407T130000Z DTEND:20210407T140000Z DTSTAMP:20260404T110911Z UID:BAS-PO/14 DESCRIPTION:Title: Contemporary Southern Ocean CO2 flux variability in the UKESM1 and ocean-only simulations\nby Andrea Rochner (University of Exeter) as pa rt of BAS Polar Oceans Seminar\n\n\nAbstract\nThe Southern Ocean is a stro ng contemporary sink for atmospheric CO2 due to the interaction of various drivers\, including strong winds\, biological activity\, or the overturni ng of water masses and their carbon content. A fundamental question is whe ther the Southern Ocean will continue taking up similar proportions of CO2 in the future. However\, future projections are hampered by the large unc ertainty in contemporary CO2 fluxes in Earth System Models (ESMs) and resu lt from differences in individual model set-ups and their representation o f CO2 flux drivers\, historically sparse observations\, and gaps in the un derstanding of the regional distribution and natural variability of air-se a CO2 flux.\n\n \n\nIn this talk\, I will first introduce some of the open questions and challenges for both observations and models with regard to the CO2 flux in the Southern Ocean. I then explore the CO2 flux and its dr ivers in the Southern Ocean for the fully-coupled historical UK Earth Syst em Model (UKESM1) simulation\, compared to simulations using the UKESM1’ s ocean component forced with reanalysis data. The comparison highlights s everal shortcomings in the UKESM1 simulations. Differences in the phase of the seasonal cycle of net CO2 flux appear between the simulations: while the seasonal cycle is out of phase with observations in the UKESM1\, the o cean-only simulation is in phase. This phase change is related to differen ces in the underlying physical processes\, namely upper ocean stratificati on\, winter mixed layer depth in the sub-Antarctic region\, and circulatio n\, which occur in response to the different atmospheric forcing. Disagree ments in the timing of the seasonal cycle are not uncommon for ESMs\, as a re biases in the named physical processes. The results described here may therefore be valid for a larger group of ESMs. However\, there are feature s of the CO2 flux which do not improve or even exacerbate despite improved physics representation in the ocean-only run\, such as the magnitude of t he CO2 flux or the decadal variability. The results thus illustrate the co mplexity of simulating the Southern Ocean CO2 flux\, current limitations a nd opportunities for future model developments.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/14/ END:VEVENT BEGIN:VEVENT SUMMARY:Sønke Maus (Norwegian University of Science and Technology) DTSTART:20210421T130000Z DTEND:20210421T140000Z DTSTAMP:20260404T110911Z UID:BAS-PO/15 DESCRIPTION:Title: Digital Sea Ice Physics - A novel approach for computing and parame trising sea ice properties for geophysical applications\nby Sønke Mau s (Norwegian University of Science and Technology) as part of BAS Polar Oc eans Seminar\n\n\nAbstract\nOne of the large challenges in sea ice science is how sea ice properties (e.g.\, albedo\, thermal conductivity) on small scales influence properties and processes on larger scales (e.g.\, the fl oe or ridge scale and basin-scale sea ice behaviour). To make progress one has to understand the variability in small-scale properties which can spa n several orders of magnitude (e.g. permeability). For many properties a s trong dependence on temperature and salinity has been found\, yet the deta iled physical processes leading to this variability have remained unclear: On the one hand are the bulk fractions of sea ice constituents (gas\, ice \, brine and solid salts) often insufficiently known or measured. On the o ther hand\, there is the lack in observations of 3D sea ice micro-structur e to which the physical properties are related.\n\nIn the present talk I w ill focus on the concept of "Digital Sea Ice physics" to improve our under standing of sea ice properties\, their dependence on microstructure and gr owth conditions\, and illustrate several applications to geophysical sea i ce problems. The concept is adopted from rock science where it has been es tablished as "Digital Rock Physics" (DRP) during the last decade. It is ba sed on 3D X-ray tomographic imaging and digitizing of the sea ice pore spa ce\, followed by direct numerical computation of its effective physical pr operties. In this way the relationship between effective physical properti es of sea ice and its bulk constituents (volume fractions of ice\, air\, b rine and solid salts) is determined and related to micro-scale characteris tics of the pore space\, providing an improved understanding of the proper ties' variability.\n\nI will begin the talk with an overview of sea ice pr operties and microstructure and their variability\, to illustrate related challenges and open questions in sea ice science\, identifying the need of 3D microstructure information for many topics. I will then describe the w ork flow of “Digital Sea Ice Physics” from field sampling to physical property computations\, as well as the challenges for the porous medium se a ice\, when compared to rocks and snow. I will discuss several applicatio ns to obtain sea ice properties that are relevant for sea ice and climate modelling: (i) transport properties of sea ice and recent results on sea i ce permeability and electrical conductivity\; (ii) the microstructure at t he sea ice ocean interface (with relevance for on ice-ocean heat\, salt an d momentum exchange as well as ice-ice friction) and (iii) the ice surface regime (with relevance for albedo and inter-facial processes between sea ice and snow). Digital Sea ice physics is a concept that has large future potential due to increasing computational power to handle large 3D images. The talk closes with an overview of climate-relevant sea ice properties f or which the approach opens new paths to fundamental knowledge and underst anding.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/15/ END:VEVENT BEGIN:VEVENT SUMMARY:Hartmut Hellmer (Alfred Wegener Institute) DTSTART:20210505T130000Z DTEND:20210505T140000Z DTSTAMP:20260404T110911Z UID:BAS-PO/16 DESCRIPTION:Title: From Models to Observations: A Case Study for the Filchner-Ronne Ic e Shelf\nby Hartmut Hellmer (Alfred Wegener Institute) as part of BAS Polar Oceans Seminar\n\n\nAbstract\nWarm water of open ocean origin on the continental shelf of Amundsen and Bellingshausen Seas drives the highest basal melt rates reported for Antarctic ice shelves. This has severe conse quences for ice shelf/ice sheet dynamics and the mass balance of the Antar ctic Ice Sheet. Ice shelves fringing the broad continental shelf in Weddel l and Ross Seas melt at rates orders of magnitude smaller. However\, simul ations using coupled ice–ocean models forced with the atmospheric output of the HadCM3 SRES-A1B scenario run indicate that the circulation in the southern Weddell Sea might change during the 21st century. As elaborated b y additional sensitivity studies\, certain environmental settings support the flow of Circumpolar Deep Water derivatives southward underneath the Fi lchner–Ronne Ice Shelf\, warming the cavity and intensifying basal melti ng. The results also identify a tipping point in the southern Weddell Sea: a positive melt water feedback enhances the shelf circulation and the ons hore transport of open ocean heat. Motivated by the model results\, the Al fred Wegener Institute in collaboration with the British Antarctic Survey and Norwegian Research Centre participated in two projects (FISP and FISS) focused on the investigation of the Filchner-Ronne Ice Shelf (FRIS) cavit y and the southern Weddell Sea continental shelf. Here\, I combine the res ults from data of four moorings operating beneath FRIS with the most recen t survey (PS111-2018) along the FRIS front and across the Filchner Trough\ , complemented by mooring data recovered during the PS124-2021 COSMUS crui se. It turns out that wide-ranging atmospheric teleconnections influence s ea ice and thus dense water formation in the southern Weddell Sea on inter annual time scales. The shelf process (a) controls the cavity circulation\ , (b) causes mode shifts underneath the northern Filchner Ice Shelf\, and (c) determines the strength of the density barrier at the continental shel f break\, thereby affecting the onshore flow of warmer waters. This sugges ts that keeping an eye on the large-scale atmospheric conditions in the So uthern Ocean might be one (easy) way to infer changes in the northern Filc hner Trough.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/16/ END:VEVENT BEGIN:VEVENT SUMMARY:Elizabeth Yankovsky (New York University) DTSTART:20210519T130000Z DTEND:20210519T140000Z DTSTAMP:20260404T110911Z UID:BAS-PO/17 DESCRIPTION:Title: Constraining water mass transformation and overflow dynamics on the Arctic shelves\nby Elizabeth Yankovsky (New York University) as part of BAS Polar Oceans Seminar\n\n\nAbstract\nDense gravity currents forced b y surface buoyancy loss over polar continental shelves are important contr ibutors to subsurface and abyssal ventilation throughout the World Ocean\, yet remain challenging to observe and represent accurately in models. The vast\, and rapidly evolving Arctic shelves are particularly crucial in se tting water mass structure of the entire basin and influencing its respons e to changing climatic conditions. Observations indicate that some of the strongest water mass transformation processes in the Arctic occur in the B arents and Kara Sea shelves. The combination of cooling of warm Atlantic i nflow as well as localized polynya development around Svalbard\, Franz Jos ef Land\, and Novaya Zemlya leads to development of waters with higher den sities than even the deepest layers of the Arctic. Depending on the amount of mixing and strength of the buoyancy forcing\, these dense overflows ma y also ventilate the Arctic halocline layer.\n\n \n\nIn the first part of the talk\, I will present idealized high-resolution simulations aimed at s tudying the dynamics of rotating dense overflows. I will discuss the role of mesoscale baroclinic eddies and submesoscale symmetric instability in s etting the pathways and properties of the dense waters. In the second part \, we will examine how modern state-of-the-art general circulation models presently capture shelf overflow dynamics in the Arctic. We consider: (1) whether dense shelf overflows and the vertical structure of the Arctic are well-represented by the GFDL-OM4 1/4-degree model as well as an analogous 1/8-degree version\; and (2) pathways by which overflows and water mass t ransformation over the Eurasian shelves contribute to setting the vertical structure of the interior Arctic. We also explore the changes in ventilat ion pathways that the Arctic will experience as a result of warming. In pa rticular – we see evidence for dense water formation changing from being influenced by polynyas and brine rejection as sea ice forms to being pred ominantly set by cooling of the inflowing\, highly saline Atlantic waters. \n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/17/ END:VEVENT BEGIN:VEVENT SUMMARY:Louis-Alexandre Couston (Laboratoire de Physique\, ENS de Lyon) DTSTART:20210602T130000Z DTEND:20210602T140000Z DTSTAMP:20260404T110911Z UID:BAS-PO/18 DESCRIPTION:Title: Turbulent convection in Antarctic Subglacial Lakes\nby Louis-Al exandre Couston (Laboratoire de Physique\, ENS de Lyon) as part of BAS Pol ar Oceans Seminar\n\n\nAbstract\nTrapped beneath the Antarctic ice sheet l ie over 400 subglacial lakes\, which are considered to be extreme\, isolat ed\, yet viable habitats for microbial life. The physical conditions withi n subglacial lakes are critical to evaluating how and where life may best exist. In this talk\, I will demonstrate that Earth’s geothermal flux pr ovides efficient stirring of Antarctic subglacial lake water. I will show that most lakes are in a regime of vigorous turbulent vertical convection\ , enabling suspension of spherical particulates with diameters up to 36 mi crometers. Thus\, dynamic flows support efficient mixing of nutrient- and oxygen-enriched meltwater derived from the overlying ice\, which is essent ial for biome support within the water column. I will show that a stable l ayer isolates the well-mixed bulk from the ice-water interface in lakes be neath a thin (<3.166 kilometers) ice cover\, because of the nonlinear equa tion of state of water. I will discuss how relaxing the approximations tha t the current theory relies on (flat ice-water ceiling) might change the p redictions\, as well as the implications of this work for future lake expl oration.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/18/ END:VEVENT BEGIN:VEVENT SUMMARY:Maria Fox (Schlumberger Cambridge Research) DTSTART:20210329T100000Z DTEND:20210329T110000Z DTSTAMP:20260404T110911Z UID:BAS-PO/19 DESCRIPTION:Title: Automated Strategic Mission Planning for a Future Marine Autonomous Vehicle Fleet\nby Maria Fox (Schlumberger Cambridge Research) as part of BAS Polar Oceans Seminar\n\n\nAbstract\nIn the marine research fleet o f the future\, untethered autonomous vehicles will be much more prevalent than they are today\, meeting the rapidly-growing demand for environmental data to inform policy decisions relating to climate\, sea level rise and ecosystems. This means that controllable autonomous vehicles will need to be used optimally to perform data gathering tasks\, especially in remote a nd hostile regions. To fully utilise the autonomous fleet\, there will be a need for intelligent automated decision-making to command and control it s role in long-term research campaigns. Instead of each vehicle being sepa rately tasked and piloted\, as is the case now\, an automated strategic pl anning system will coordinate the fleet to maximise the ocean area covered and optimise the quantity\, quality and type of data collected over the l ifetime of a research campaign. Strategic plans can be used to augment\, and eventually even replace\, some of the human expertise currently needed to manage the fleet.\n\nTo generate high value plans for the fleet\, a st rategic decision-making system will need to be informed by environmental s imulations and predictions based on data. It will need an understanding of the risk to the vehicles\, and how to minimise this risk without wasting opportunities. This talk will describe a plan-based approach to coordinati ng the activities of a fleet of autonomous vehicles undertaking long-term campaigns in the Southern Ocean. The talk will discuss how predictions mad e by Machine Learning can be integrated with combinatorial decision-making to generate plans that use the fleet safely and effectively.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/19/ END:VEVENT BEGIN:VEVENT SUMMARY:Paul Holland (British Antarctic Survey) DTSTART:20210630T130000Z DTEND:20210630T140000Z DTSTAMP:20260404T110911Z UID:BAS-PO/21 DESCRIPTION:Title: Melting of the Antarctic Ice Sheet: What is the role of anthropogen ic forcing?\nby Paul Holland (British Antarctic Survey) as part of BAS Polar Oceans Seminar\n\n\nAbstract\nIce loss from the Antarctic Ice Sheet is a substantial source of sea-level rise\, with a large and uncertain fu ture contribution. This melting ice is often used as an example of global warming\, with an implicit linkage to human activities. However\, the li nk to anthropogenic forcing is not clear because the ice sheet may be in a n unstable configuration\, and the region is subject to large internal cli mate variability. In this talk I will summarise the available observation s of ice\, ocean\, and atmosphere in the region\, and then present evidenc e from climate model simulations. The combined evidence suggests that the ongoing ice loss is partly caused by ice sheet instability and partly by c limate forcing. Of the forcing\, part is anthropogenic. As a result of t his combination of factors\, it is not clear how the Antarctic Ice Sheet w ill respond to future emissions scenarios.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/21/ END:VEVENT BEGIN:VEVENT SUMMARY:Mainak Mondal (New York University Abu Dhabi) DTSTART:20210714T130000Z DTEND:20210714T140000Z DTSTAMP:20260404T110911Z UID:BAS-PO/22 DESCRIPTION:Title: Turbulent melting of a glacier front using high resolution simulati ons\nby Mainak Mondal (New York University Abu Dhabi) as part of BAS P olar Oceans Seminar\n\n\nAbstract\nOver the past few years\, valuable new observations from the glacial front of Antarctica and Greenland using high -resolution turbulence profilers at the ice shelf borehole (Davis and Nich olls 2019\; Kimura et al. 2015\; Begeman et al. 2018\; Jenkins et al. 2010 ) iterated the importance of turbulent processes in controlling the meltin g and dissolution of the ice-ocean interface. Previous laboratory experime nts (McConnochie et. al.\, 2015\,17\,18) and high-resolution numerical sim ulations (Gayen et al.\, 2015\, Mondal et. al\, 2019\, Vreghdenhil et al.\ , 2020 Couston et al.\,2021) also have extensively discussed the role of t urbulence in the basal melting. My talk spans from turbulence-resolving s cales up to the full depth of a fjord. At the turbulence scale\, I investi gated how the turbulent melting/freezing at the ice-interface is affected by ice-geometry\, surface-roughness\, ambient velocity shear and external subglacial discharge using fluid-only Direct Numerical Simulations. At the large scale\, I investigated the dynamics of a subglacial discharge plume subjected to varying subglacial conduit size\, shape and distributions a s well as 3d ice-geometry using the MITgcm plume model. These insights can help to provide better estimations of the melting of the ice-face\, essen tial for more accurate projections of future sea-level rise.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/22/ END:VEVENT BEGIN:VEVENT SUMMARY:Erik Behrens (National Institute of Water and Atmospheric Research ) DTSTART:20211020T080000Z DTEND:20211020T090000Z DTSTAMP:20260404T110911Z UID:BAS-PO/23 DESCRIPTION:Title: The impact of sea-ice drift and ocean circulation on dispersal of t oothfish eggs and juveniles in the Ross Gyre and Amundsen Sea\nby Erik Behrens (National Institute of Water and Atmospheric Research) as part of BAS Polar Oceans Seminar\n\n\nAbstract\nKnowledge about the early life hi story of Antarctic toothfish (Dissostichus mawsoni) is still incomplete\, particularly on the spatial and temporal extent of spawning and the subseq uent transport of eggs\, larvae\, and juveniles from the offshore spawning areas to the continental shelf. This study uses a high-resolution hydrody namic model to investigate the impact of ocean circulation and sea-ice dri ft on the dispersal of eggs\, larvae\, and juvenile Antarctic toothfish. T he virtual eggs are released on seamounts of the Pacific-Antarctic ridge i n the Ross Gyre and advected using hydrodynamical model data. Particles ar e seeded annually over the years 2002 to 2016 and tracked for three years after their release. Recruitment success has been evaluated based on the n umber of juveniles that reached known coastal recruitment areas\, between the eastern Ross and Amundsen Seas\, within three years. Sensitivities to certain juvenile behaviours has been explored and showed that recruitment success was reduced by around 70% if juveniles drifted with sea-ice during the second winter season as this carries them into the open ocean away fr om the shelf region. Recruitment success increases during the second winte r season if juveniles are entrained in the Ross Gyre circulation or if the y actively swam towards the shelf. These modelling results suggest that th e ecological advantage of sea-ice association in the early life cycle of t oothfish diminishes as they grow\, promoting a behaviour change during the ir second winter.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/23/ END:VEVENT BEGIN:VEVENT SUMMARY:Andrew Stewart (UCLA) DTSTART:20211103T153000Z DTEND:20211103T163000Z DTSTAMP:20260404T110911Z UID:BAS-PO/24 DESCRIPTION:Title: High-frequency fluctuations in Antarctic Bottom Water transport dri ven by Southern Ocean winds\nby Andrew Stewart (UCLA) as part of BAS P olar Oceans Seminar\n\n\nAbstract\nNorthward flow of Antarctic Bottom Wate r (AABW) across the Southern Ocean comprises a key component of the global overturning circulation. Yet AABW transport remains poorly constrained by observations and state estimates\, and there is presently no means of dir ectly monitoring any component of the Southern Ocean overturning. However\ , AABW flow is dynamically linked to Southern Ocean surface circulation vi a the zonal momentum balance\, offering potential routes to indirect monit oring of the transport. Exploiting this dynamical link\, this study uses a dynamically self-consistent ocean state estimate (ECCOV4r4) to show that wind stress fluctuations drive large AABW transport fluctuations on time s cales shorter than ~2 years\, which comprise almost all of the transport v ariance. This connection occurs due to differing time scales on which topo graphic and interfacial form stresses respond to wind variability\, likely associated with differences in barotropic vs. baroclinic Rossby wave prop agation. These findings imply that AABW transport variability can largely be reconstructed from the surface wind stress alone.\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/24/ END:VEVENT BEGIN:VEVENT SUMMARY:Robbie Mallett (University College London) DTSTART:20211117T140000Z DTEND:20211117T150000Z DTSTAMP:20260404T110911Z UID:BAS-PO/25 DESCRIPTION:Title: Snow on sea ice: poorly observed\, poorly modelled\, poorly underst ood\nby Robbie Mallett (University College London) as part of BAS Pola r Oceans Seminar\n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/25/ END:VEVENT BEGIN:VEVENT SUMMARY:Gemma O'Conor (University of Washington) DTSTART:20211108T140000Z DTEND:20211108T150000Z DTSTAMP:20260404T110911Z UID:BAS-PO/26 DESCRIPTION:Title: A proxy-constrained history of 20th century atmospheric circulation in the Amundsen Sea and implications for glacier retreat\nby Gemma O' Conor (University of Washington) as part of BAS Polar Oceans Seminar\n\nAb stract: TBA\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/26/ END:VEVENT BEGIN:VEVENT SUMMARY:Chen Zhao (University of Tasmania) DTSTART:20211201T100000Z DTEND:20211201T110000Z DTSTAMP:20260404T110911Z UID:BAS-PO/27 DESCRIPTION:Title: Representation of basal melting in idealised coupled ice sheet ocea n models\nby Chen Zhao (University of Tasmania) as part of BAS Polar O ceans Seminar\n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/27/ END:VEVENT BEGIN:VEVENT SUMMARY:Oana Dragomir (National Oceanography Centre\, Southampton) DTSTART:20211215T140000Z DTEND:20211215T150000Z DTSTAMP:20260404T110911Z UID:BAS-PO/28 DESCRIPTION:Title: Variability of the Undercurrent in the Amundsen Sea inferred from s atellite altimetry\nby Oana Dragomir (National Oceanography Centre\, S outhampton) as part of BAS Polar Oceans Seminar\n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/28/ END:VEVENT BEGIN:VEVENT SUMMARY:Isabel Nias (University of Liverpool) DTSTART:20220126T140000Z DTEND:20220126T150000Z DTSTAMP:20260404T110911Z UID:BAS-PO/29 DESCRIPTION:Title: Quantifying and reducing uncertainty in projections of sea level ri se from ice sheets\nby Isabel Nias (University of Liverpool) as part o f BAS Polar Oceans Seminar\n\nAbstract: TBA\n LOCATION:https://stable.researchseminars.org/talk/BAS-PO/29/ END:VEVENT END:VCALENDAR