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:20260422T225718Z UID:BAS-PO/1 DESCRIPTION:Title: A rctic Freshwater Storage and Export in CMIP6 Models\nby Hannah Zanowsk i (University of Colorado Boulder) as part of BAS Polar Oceans Seminar\n\n Abstract: TBA\n LOCATION:https://researchseminars.org/talk/BAS-PO/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Margaret Lindeman (Scripps Institute of Oceanography) DTSTART:20200923T150000Z DTEND:20200923T160000Z DTSTAMP:20260422T225718Z UID:BAS-PO/2 DESCRIPTION:Title: O bserving Iceberg Melt in a Greenland Fjord\nby Margaret Lindeman (Scri pps Institute of Oceanography) as part of BAS Polar Oceans Seminar\n\nAbst ract: TBA\n LOCATION:https://researchseminars.org/talk/BAS-PO/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Rebecca Jackson (Rutgers University) DTSTART:20201007T130000Z DTEND:20201007T140000Z DTSTAMP:20260422T225718Z UID:BAS-PO/3 DESCRIPTION:Title: M elting and mixing at the submarine termini of tidewater glaciers\nby R ebecca Jackson (Rutgers University) as part of BAS Polar Oceans Seminar\n\ n\nAbstract\nAround the globe\, glaciers and ice sheets are shrinking and contributing to sea level rise. Ocean warming has been implicated as a dri ver of glacier retreat\, with submarine melting as the presumed link. Howe ver\, at the termini of tidewater glaciers\, we lack observations of subma rine melting or the oceanic processes that control melt. Instead\, many st udies rely on untested theory and parameterizations to estimate submarine melt rates. These frameworks often hinge on buoyant plumes\, whose small-s cale dynamics can modulate both the ocean’s impact on the glacier via su bmarine melting and the glacier’s impact on the ocean via buoyancy forci ng. In this talk\, I will present data collected near the terminus of LeCo nte Glacier\, Alaska to probe the standard theory for plume-driven melt. I n the first half\, I will present surveys from autonomous kayaks that reve al ubiquitous meltwater intrusions along the terminus and suggest a mechan ism to explain melt rates that are significantly higher than standard theo ry predicts. In the second half\, the bulk fluxes of submarine melt and su bglacial discharge are evaluated across a wide range of conditions in six field campaigns to test the theoretical relationship between these two sou rces of freshwater. Modifications to the standard melt parameterizations a re explored\, in an effort to work towards an updated representation of me lt in ocean-glacier models.\n LOCATION:https://researchseminars.org/talk/BAS-PO/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Mitch Bushuk (Geophysical Fluid Dynamics Laboratory) DTSTART:20201021T130000Z DTEND:20201021T140000Z DTSTAMP:20260422T225718Z UID:BAS-PO/4 DESCRIPTION:Title: S easonal prediction and predictability of regional Antarctic sea ice\nb y Mitch Bushuk (Geophysical Fluid Dynamics Laboratory) as part of BAS Pola r Oceans Seminar\n\n\nAbstract\nCompared to the Arctic\, seasonal predicti ons of Antarctic sea ice have received relatively little attention. In thi s talk\, I will use three coupled dynamical prediction systems developed a t the Geophysical Fluid Dynamics Laboratory to assess the seasonal predict ion skill and predictability of Antarctic sea ice. These systems\, based o n the FLOR\, SPEAR-lo\, and SPEAR-med dynamical models\, differ in their c oupled model components\, initialization techniques\, atmospheric resoluti on\, and model biases. This allows for an investigation of these factors i n determining Antarctic sea ice prediction skill. Using suites of retrospe ctive initialized seasonal predictions spanning 1992-2018\, we find that e ach system is capable of skillfully predicting regional Antarctic sea ice extent (SIE) with skill that generically exceeds that of a persistence for ecast. Winter SIE is skillfully predicted up to 11 months in advance in th e Weddell\, Amundsen and Bellingshausen\, Indian\, and West Pacific sector s\, whereas winter skill is notably lower in the Ross sector. Zonally adve cted upper ocean heat content anomalies are found to provide the crucial s ource of prediction skill for the winter sea ice edge position. The SPEAR systems are notably more skillful than FLOR for summer sea ice predictions \, owing to improvements in sea ice concentration and sea ice thickness in itialization. Summer Weddell SIE can be skillfully predicted up to 8 month s in advance in SPEAR-med\, due to the persistence and drift of initialize d sea ice thickness anomalies from the previous winter. Overall\, these re sults suggest a promising potential for providing operational regional Ant arctic sea ice predictions on seasonal timescales.\n LOCATION:https://researchseminars.org/talk/BAS-PO/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Luwei Yang (University of California\, Los Angeles) DTSTART:20201104T150000Z DTEND:20201104T160000Z DTSTAMP:20260422T225718Z UID:BAS-PO/5 DESCRIPTION:Title: T he impact of lee waves on the Southern Ocean circulation and its response to winds\nby Luwei Yang (University of California\, Los Angeles) as pa rt of BAS Polar Oceans Seminar\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/BAS-PO/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Georgy Manucharyan (University of Washington) DTSTART:20201118T160000Z DTEND:20201118T170000Z DTSTAMP:20260422T225718Z UID:BAS-PO/6 DESCRIPTION:Title: S ubZero: Floe-Resolving Sea Ice Model\nby Georgy Manucharyan (Universit y of Washington) as part of BAS Polar Oceans Seminar\n\n\nAbstract\nSea ic e is commonly represented in climate models as a continuous fluid with pre scribed rheological properties aimed to represent its motion at relatively 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 wi ll present a prototype of a new sea ice model (SubZero) that explicitly si mulates the lifecycle of individual sea ice floes. Its various capabilitie s will be demonstrated and physical parameterizations will be discussed\, including floe fractures\, welding\, creation from the open ocean\, etc. T he key advantage of this model is that its evolution equations can\, in pr inciple\, be constrained from observations for each individual process par ameterization\, and hence it could present a valuable alternative to exist ing rheological models\, the parameters of which do not represent explicit ly observable quantities.\n LOCATION:https://researchseminars.org/talk/BAS-PO/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Madi Rosevear (University of Tasmania) DTSTART:20201202T100000Z DTEND:20201202T110000Z DTSTAMP:20260422T225718Z UID:BAS-PO/7 DESCRIPTION:Title: F ine-scale ocean processes in the basal melting of Antarctic ice shelves\nby Madi Rosevear (University of Tasmania) as part of BAS Polar Oceans S eminar\n\n\nAbstract\nThe Antarctic Ice Sheet\, which comprises the larges t 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 basal me lting 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 ocean and the ice. Ocean-climate models cannot resolve the ISOBL and rely on parame terisations to predict melting. However\, observations suggest that common ISOBL parameterisations only perform well in cold\, energetic ocean envir onments.\n\nIn this talk I will summarise some of the main findings of my PhD thesis\, which uses both observational data and turbulence-resolving m odel simulations to characterise melting and ISOBL dynamics across a broad range of ocean states. The observational data comprises unique ocean and in situ basal melt rate observations from beneath the Amery Ice Shelf. The modelling focuses on the ISOBL and is performed using resolved large-eddy simulation. The model domain consists of a horizontal ice-ocean interface underlain by a stratified ocean\, and is forced by a steady flow in geost rophic balance. Using these model simulations\, I investigate the coupled ISOBL and melting response to ocean temperature and current forcing. Depen ding on the relative strength of the thermal and current forcing\, I find that the ISOBL may be characterized as either “well-mixed” \, “strat ified” or “double-diffusive”. I use these results to develop a novel regime diagram for the ISOBL\, which provides new insight into the varied and nonlinear melting responses expected around Antarctica\, depending on the local conditions. Comparison to observed sub-ice shelf conditions and melt rates is favorable and demonstrates the relevance of these regimes o ver a broad range of realistic conditions.\n LOCATION:https://researchseminars.org/talk/BAS-PO/7/ END:VEVENT BEGIN:VEVENT SUMMARY:Anna Wåhlin (University of Gothenburg) DTSTART:20210113T140000Z DTEND:20210113T150000Z DTSTAMP:20260422T225718Z UID:BAS-PO/8 DESCRIPTION:Title: A n AUV underneath the ‘Doomsday glacier’: Revealing pathways and modifi cation of warm water flowing beneath Thwaites ice shelf\, West Antarctica< /a>\nby Anna Wåhlin (University of Gothenburg) as part of BAS Polar Ocean s Seminar\n\n\nAbstract\nThe fate of the West Antarctic Ice Sheet is the l argest remaining uncertainty in predicting sea-level rise through the next century\, and its most vulnerable and rapidly changing outlet is Thwaites Glacier. Because the seabed slope under the glacier is retrograde (downhi ll inland)\, ice discharge from Thwaites Glacier is potentially unstable t o melting of the underside of its floating ice shelf and grounding line re treat\, both of which can be enhanced by warm ocean water circulating unde rneath the ice shelf. Here we present the results of two missions undernea th Thwaites ice shelf performed by the AUV ‘Ran’: The very first direc t observations of ocean temperature\, salinity\, and oxygen underneath Thw aites ice shelf. Using the high precision environment payload suite\, obse rvations were obtained that indicate deep water (> 800 m) underneath the c entral part of the ice shelf is in connection with Pine Island Bay\, a pre viously unknown westward branch of warm deep water entering the ice shelf cavity. Warm water also enters from the north in two troughs separated by a pinning point. Spatial gradients of salinity\, temperature and oxygen re corded underneath the ice shelf indicate that this is an active region whe re several water masses meet and mixes. The observations identify the cent ral buttressing point as a vulnerable region of change currently under att ack by warm water inflow from all sides: a scenario that may lead to ungro unding and retreat more quickly than previously expected.\n LOCATION:https://researchseminars.org/talk/BAS-PO/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Rachael Sanders (British Antarctic Survey) DTSTART:20210127T140000Z DTEND:20210127T150000Z DTSTAMP:20260422T225718Z 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://researchseminars.org/talk/BAS-PO/9/ END:VEVENT BEGIN:VEVENT SUMMARY:Shenjie Zhou (British Antarctic Survey) DTSTART:20210210T140000Z DTEND:20210210T150000Z DTSTAMP:20260422T225718Z UID:BAS-PO/10 DESCRIPTION:Title: Ocean’s response to the stochastic atmospheric forcing\nby Shenjie Z hou (British Antarctic Survey) as part of BAS Polar Oceans Seminar\n\n\nAb stract\nThe ocean is forced by the atmosphere on a range of spatial and te mporal scales. In ocean and climate models the resolution of the atmospher ic forcing sets a limit on the scales that are represented. For typical cl imate models this means mesoscale (< 400 km) atmospheric forcing is absent . Previous studies have demonstrated that mesoscale forcing significantly affects key ocean circulation systems such as the North Atlantic Subpolar gyre and the Atlantic Meridional Overturning Circulation (AMOC). However\, the approach of these studies has either been ad hoc or limited in resolu tion. Here we present ocean model simulations with and without realistic m esoscale atmospheric forcing that represents scales down to 10 km. We use a novel stochastic parameterization – based on a cellular automaton algo rithm that is common in weather forecasting ensemble prediction systems – to represent spatially coherent weather systems over a range of scales \, including down to the smallest resolvable by the ocean grid. The parame terization is calibrated spatially and temporally using marine wind observ ations. The addition of mesoscale atmospheric forcing leads to coherent pa tterns of change in the sea surface temperature and mixed-layer depth. It also leads to non-negligible changes in the volume transport in the North Atlantic subtropical gyre (STG) and subpolar gyre (SPG) and in the AMOC. A non-systematic basin-scale circulation response to the mesoscale wind per turbation emerges – an in-phase oscillation in northward heat transport across the gyre boundary\, partly driven by the constantly enhanced STG\, correspoding to an oscillatory behaviour in SPG and AMOC indices with a ty pical time scale of 5-year\, revealing the importance of ocean dynamics in generating non-local ocean response to the stochastic mesoscale atmospher ic forcing. Atmospheric convection-permitting regional climate simulations predict changes in the intensity and frequency of mesoscale weather syste ms this century\, so representing these systems in coupled climate models could bring higher fidelity in future climate projections.\n LOCATION:https://researchseminars.org/talk/BAS-PO/10/ END:VEVENT BEGIN:VEVENT SUMMARY:Peter Washam (Georgia Institute of Technology) DTSTART:20210224T140000Z DTEND:20210224T150000Z DTSTAMP:20260422T225718Z UID:BAS-PO/11 DESCRIPTION:Title: A synthesis of Antarctic ice-ocean boundary observations from the underwat er vehicle Icefin\nby Peter Washam (Georgia Institute of Technology) a s part of BAS Polar Oceans Seminar\n\n\nAbstract\nThe accumulated mass los s from the Earth’s cryosphere currently represents the largest contribut ion to global sea level rise. A large portion of this mass loss is driven by physical processes occurring at the marine margin of the Antarctic and Greenland ice sheets\, where the ice sheet interacts with the ocean. Howe ver\, there are extremely limited direct observations of the ice-ocean int erface where these two physical environments meet. Here we synthesize thre e years of ice and ocean observations in Antarctica from McMurdo Sound and beneath the Ross and Thwaites ice shelves\, using hydrographic and sonar data\, and video footage from the underwater vehicle Icefin. Near-ice ocea n conditions vary between these environments from below freezing to greate r than two degrees above freezing\, with considerable variability in curre nt velocities. Ice base morphology likewise varies within and between envi ronments\, with ablating ice forming scallops\, runnels\, and terraces wit h horizontal scales of meters and vertical scales of centimeters to meters . Supercooled waters in turn form marine ice platelets\, which accumulate in both unconsolidated and rigid bulbous masses observed at meter scales. These variations in ice basal roughness affect the turbulent transfer of h eat and salt from the ocean to the ice\, and represent one of the most poo rly constrained parameters in the equations that describe ice-ocean intera ctions. Our results provide direct observations of the ice-ocean boundary in several environments\, and therefore inform on these processes that are critical for the future behavior of the Antarctic and Greenland ice sheet s\, as well as other peripheral ice caps that contain marine-terminating o utlet glaciers.\n LOCATION:https://researchseminars.org/talk/BAS-PO/11/ END:VEVENT BEGIN:VEVENT SUMMARY:Wilma Huneke (Australian National University) DTSTART:20210324T090000Z DTEND:20210324T100000Z DTSTAMP:20260422T225718Z UID:BAS-PO/13 DESCRIPTION:Title: Spatial and temporal variability of the Antarctic Slope Current in an eddy ing ocean-sea ice model\nby Wilma Huneke (Australian National Universi ty) as part of BAS Polar Oceans Seminar\n\n\nAbstract\nThe basal melt rate of Antarctica's ice shelves is largely controlled by heat delivered from the Southern Ocean to the Antarctic continental shelf. The Antarctic Slope Current (ASC) is an almost circumpolar feature that encircles Antarctica along the continental shelf break in an anti-clockwise direction. Because the circulation is to first order oriented along the topographic slope\, i t inhibits exchange of water masses between the Southern Ocean and the Ant arctic continental shelf and thereby impacts cross-slope heat supply. Dire ct observations of the ASC system are sparse\, but indicate a highly varia ble flow field both in time and space. Given the importance of the circula tion near the shelf break for cross-shelf exchange of heat\, it is timely to further improve our knowledge of the ASC system. This study makes use o f the global ocean-sea ice model ACCESS-OM2-01 with a 1/10 degree horizont al resolution and describes the spatial and temporal variability of the ve locity field. We categorise the modelled ASC into three different regimes\ , similar to previous works for the associated Antarctic Slope Front: (i) A surface-intensified current found predominantly in East Antarctica\, (ii ) a bottom-intensified current found downstream of the dense shelf water f ormation sites in the Ross\, Weddell\, and Prydz Bay Seas\, and (iii) a re versed current found in West Antarctica where the eastward flowing Antarct ic Circumpolar Current impinges onto the continental shelf break. We show that the regional distribution of the ASC regimes aligns well with that of the frontal structures. Looking at the temporal variability\, we find dif ferences in the seasonal characteristics for each regime. The surface-inte nsified ASC exhibits the largest seasonal variability with larger velociti es 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 temporal var iability is extensive within each ASC regime.\n LOCATION:https://researchseminars.org/talk/BAS-PO/13/ END:VEVENT BEGIN:VEVENT SUMMARY:Andrea Rochner (University of Exeter) DTSTART:20210407T130000Z DTEND:20210407T140000Z DTSTAMP:20260422T225718Z UID:BAS-PO/14 DESCRIPTION:Title: Contemporary Southern Ocean CO2 flux variability in the UKESM1 and ocean-o nly simulations\nby Andrea Rochner (University of Exeter) as part of B AS Polar Oceans Seminar\n\n\nAbstract\nThe Southern Ocean is a strong cont emporary sink for atmospheric CO2 due to the interaction of various driver s\, including strong winds\, biological activity\, or the overturning of w ater masses and their carbon content. A fundamental question is whether th e Southern Ocean will continue taking up similar proportions of CO2 in the future. However\, future projections are hampered by the large uncertaint y in contemporary CO2 fluxes in Earth System Models (ESMs) and result from differences in individual model set-ups and their representation of CO2 f lux drivers\, historically sparse observations\, and gaps in the understan ding of the regional distribution and natural variability of air-sea CO2 f lux.\n\n \n\nIn this talk\, I will first introduce some of the open questi ons 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 drivers i n the Southern Ocean for the fully-coupled historical UK Earth System Mode l (UKESM1) simulation\, compared to simulations using the UKESM1’s ocean component forced with reanalysis data. The comparison highlights several shortcomings in the UKESM1 simulations. Differences in the phase of the se asonal cycle of net CO2 flux appear between the simulations: while the sea sonal cycle is out of phase with observations in the UKESM1\, the ocean-on ly simulation is in phase. This phase change is related to differences in the underlying physical processes\, namely upper ocean stratification\, wi nter mixed layer depth in the sub-Antarctic region\, and circulation\, whi ch occur in response to the different atmospheric forcing. Disagreements i n the timing of the seasonal cycle are not uncommon for ESMs\, as are bias es in the named physical processes. The results described here may therefo re be valid for a larger group of ESMs. However\, there are features of th e CO2 flux which do not improve or even exacerbate despite improved physic s representation in the ocean-only run\, such as the magnitude of the CO2 flux or the decadal variability. The results thus illustrate the complexit y of simulating the Southern Ocean CO2 flux\, current limitations and oppo rtunities for future model developments.\n LOCATION:https://researchseminars.org/talk/BAS-PO/14/ END:VEVENT BEGIN:VEVENT SUMMARY:Sønke Maus (Norwegian University of Science and Technology) DTSTART:20210421T130000Z DTEND:20210421T140000Z DTSTAMP:20260422T225718Z UID:BAS-PO/15 DESCRIPTION:Title: Digital Sea Ice Physics - A novel approach for computing and parametrising sea ice properties for geophysical applications\nby Sønke Maus (Norw egian University of Science and Technology) as part of BAS Polar Oceans Se minar\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 floe or r idge scale and basin-scale sea ice behaviour). To make progress one has to understand the variability in small-scale properties which can span sever al orders of magnitude (e.g. permeability). For many properties a strong d ependence on temperature and salinity has been found\, yet the detailed ph ysical processes leading to this variability have remained unclear: On the one hand are the bulk fractions of sea ice constituents (gas\, ice\, brin e and solid salts) often insufficiently known or measured. On the other ha nd\, there is the lack in observations of 3D sea ice micro-structure to wh ich the physical properties are related.\n\nIn the present talk I will foc us on the concept of "Digital Sea Ice physics" to improve our understandin g of sea ice properties\, their dependence on microstructure and growth co nditions\, and illustrate several applications to geophysical sea ice prob lems. The concept is adopted from rock science where it has been establish ed as "Digital Rock Physics" (DRP) during the last decade. It is based on 3D X-ray tomographic imaging and digitizing of the sea ice pore space\, fo llowed by direct numerical computation of its effective physical propertie s. In this way the relationship between effective physical properties of s ea ice and its bulk constituents (volume fractions of ice\, air\, brine an d solid salts) is determined and related to micro-scale characteristics of the pore space\, providing an improved understanding of the properties' v ariability.\n\nI will begin the talk with an overview of sea ice propertie s and microstructure and their variability\, to illustrate related challen ges and open questions in sea ice science\, identifying the need of 3D mic rostructure information for many topics. I will then describe the work flo w of “Digital Sea Ice Physics” from field sampling to physical propert y computations\, as well as the challenges for the porous medium sea ice\, when compared to rocks and snow. I will discuss several applications to o btain sea ice properties that are relevant for sea ice and climate modelli ng: (i) transport properties of sea ice and recent results on sea ice perm eability and electrical conductivity\; (ii) the microstructure at the sea ice ocean interface (with relevance for on ice-ocean heat\, salt and momen tum 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 potenti al due to increasing computational power to handle large 3D images. The ta lk closes with an overview of climate-relevant sea ice properties for whic h the approach opens new paths to fundamental knowledge and understanding. \n LOCATION:https://researchseminars.org/talk/BAS-PO/15/ END:VEVENT BEGIN:VEVENT SUMMARY:Hartmut Hellmer (Alfred Wegener Institute) DTSTART:20210505T130000Z DTEND:20210505T140000Z DTSTAMP:20260422T225718Z UID:BAS-PO/16 DESCRIPTION:Title: From Models to Observations: A Case Study for the Filchner-Ronne Ice Shelf \nby Hartmut Hellmer (Alfred Wegener Institute) as part of BAS Polar O ceans Seminar\n\n\nAbstract\nWarm water of open ocean origin on the contin ental shelf of Amundsen and Bellingshausen Seas drives the highest basal m elt rates reported for Antarctic ice shelves. This has severe consequences for ice shelf/ice sheet dynamics and the mass balance of the Antarctic Ic e Sheet. Ice shelves fringing the broad continental shelf in Weddell and R oss Seas melt at rates orders of magnitude smaller. However\, simulations using coupled ice–ocean models forced with the atmospheric output of the HadCM3 SRES-A1B scenario run indicate that the circulation in the souther n Weddell Sea might change during the 21st century. As elaborated by addit ional sensitivity studies\, certain environmental settings support the flo w of Circumpolar Deep Water derivatives southward underneath the Filchner –Ronne Ice Shelf\, warming the cavity and intensifying basal melting. Th e results also identify a tipping point in the southern Weddell Sea: a pos itive melt water feedback enhances the shelf circulation and the onshore t ransport of open ocean heat. Motivated by the model results\, the Alfred W egener Institute in collaboration with the British Antarctic Survey and No rwegian Research Centre participated in two projects (FISP and FISS) focus ed on the investigation of the Filchner-Ronne Ice Shelf (FRIS) cavity and the southern Weddell Sea continental shelf. Here\, I combine the results f rom data of four moorings operating beneath FRIS with the most recent surv ey (PS111-2018) along the FRIS front and across the Filchner Trough\, comp lemented by mooring data recovered during the PS124-2021 COSMUS cruise. It turns out that wide-ranging atmospheric teleconnections influence sea ice and thus dense water formation in the southern Weddell Sea on interannual time scales. The shelf process (a) controls the cavity circulation\, (b) causes mode shifts underneath the northern Filchner Ice Shelf\, and (c) de termines the strength of the density barrier at the continental shelf brea k\, thereby affecting the onshore flow of warmer waters. This suggests tha t keeping an eye on the large-scale atmospheric conditions in the Southern Ocean might be one (easy) way to infer changes in the northern Filchner T rough.\n LOCATION:https://researchseminars.org/talk/BAS-PO/16/ END:VEVENT BEGIN:VEVENT SUMMARY:Elizabeth Yankovsky (New York University) DTSTART:20210519T130000Z DTEND:20210519T140000Z DTSTAMP:20260422T225718Z 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 by surfa ce buoyancy loss over polar continental shelves are important contributors to subsurface and abyssal ventilation throughout the World Ocean\, yet re main challenging to observe and represent accurately in models. The vast\, and rapidly evolving Arctic shelves are particularly crucial in setting w ater mass structure of the entire basin and influencing its response to ch anging climatic conditions. Observations indicate that some of the stronge st water mass transformation processes in the Arctic occur in the Barents and Kara Sea shelves. The combination of cooling of warm Atlantic inflow a s well as localized polynya development around Svalbard\, Franz Josef Land \, and Novaya Zemlya leads to development of waters with higher densities than even the deepest layers of the Arctic. Depending on the amount of mix ing and strength of the buoyancy forcing\, these dense overflows may also ventilate the Arctic halocline layer.\n\n \n\nIn the first part of the tal k\, I will present idealized high-resolution simulations aimed at studying the dynamics of rotating dense overflows. I will discuss the role of meso scale baroclinic eddies and submesoscale symmetric instability in setting the pathways and properties of the dense waters. In the second part\, we w ill examine how modern state-of-the-art general circulation models present ly capture shelf overflow dynamics in the Arctic. We consider: (1) whether dense shelf overflows and the vertical structure of the Arctic are well-r epresented by the GFDL-OM4 1/4-degree model as well as an analogous 1/8-de gree version\; and (2) pathways by which overflows and water mass transfor mation over the Eurasian shelves contribute to setting the vertical struct ure of the interior Arctic. We also explore the changes in ventilation pat hways that the Arctic will experience as a result of warming. In particula r – we see evidence for dense water formation changing from being influe nced by polynyas and brine rejection as sea ice forms to being predominant ly set by cooling of the inflowing\, highly saline Atlantic waters.\n LOCATION:https://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:20260422T225718Z UID:BAS-PO/18 DESCRIPTION:Title: Turbulent convection in Antarctic Subglacial Lakes\nby Louis-Alexandre Couston (Laboratoire de Physique\, ENS de Lyon) as part of BAS Polar Ocea ns Seminar\n\n\nAbstract\nTrapped beneath the Antarctic ice sheet lie over 400 subglacial lakes\, which are considered to be extreme\, isolated\, ye t viable habitats for microbial life. The physical conditions within subgl acial lakes are critical to evaluating how and where life may best exist. In this talk\, I will demonstrate that Earth’s geothermal flux provides efficient stirring of Antarctic subglacial lake water. I will show that mo st lakes are in a regime of vigorous turbulent vertical convection\, enabl ing suspension of spherical particulates with diameters up to 36 micromete rs. Thus\, dynamic flows support efficient mixing of nutrient- and oxygen- enriched meltwater derived from the overlying ice\, which is essential for biome support within the water column. I will show that a stable layer is olates the well-mixed bulk from the ice-water interface in lakes beneath a thin (<3.166 kilometers) ice cover\, because of the nonlinear equation of state of water. I will discuss how relaxing the approximations that the c urrent theory relies on (flat ice-water ceiling) might change the predicti ons\, as well as the implications of this work for future lake exploration .\n LOCATION:https://researchseminars.org/talk/BAS-PO/18/ END:VEVENT BEGIN:VEVENT SUMMARY:Maria Fox (Schlumberger Cambridge Research) DTSTART:20210329T100000Z DTEND:20210329T110000Z DTSTAMP:20260422T225718Z UID:BAS-PO/19 DESCRIPTION:Title: Automated Strategic Mission Planning for a Future Marine Autonomous Vehicl e Fleet\nby Maria Fox (Schlumberger Cambridge Research) as part of BAS Polar Oceans Seminar\n\n\nAbstract\nIn the marine research fleet of the f uture\, untethered autonomous vehicles will be much more prevalent than th ey are today\, meeting the rapidly-growing demand for environmental data t o inform policy decisions relating to climate\, sea level rise and ecosyst ems. This means that controllable autonomous vehicles will need to be used optimally to perform data gathering tasks\, especially in remote and host ile regions. To fully utilise the autonomous fleet\, there will be a need for intelligent automated decision-making to command and control its role in long-term research campaigns. Instead of each vehicle being separately tasked and piloted\, as is the case now\, an automated strategic planning system will coordinate the fleet to maximise the ocean area covered and op timise the quantity\, quality and type of data collected over the lifetime of a research campaign. Strategic plans can be used to augment\, and eve ntually even replace\, some of the human expertise currently needed to man age the fleet.\n\nTo generate high value plans for the fleet\, a strategic decision-making system will need to be informed by environmental simulati ons and predictions based on data. It will need an understanding of the ri sk to the vehicles\, and how to minimise this risk without wasting opportu nities. This talk will describe a plan-based approach to coordinating the activities of a fleet of autonomous vehicles undertaking long-term campaig ns in the Southern Ocean. The talk will discuss how predictions made by Ma chine Learning can be integrated with combinatorial decision-making to gen erate plans that use the fleet safely and effectively.\n LOCATION:https://researchseminars.org/talk/BAS-PO/19/ END:VEVENT BEGIN:VEVENT SUMMARY:Paul Holland (British Antarctic Survey) DTSTART:20210630T130000Z DTEND:20210630T140000Z DTSTAMP:20260422T225718Z UID:BAS-PO/21 DESCRIPTION:Title: Melting of the Antarctic Ice Sheet: What is the role of anthropogenic forc ing?\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 s ubstantial source of sea-level rise\, with a large and uncertain future co ntribution. This melting ice is often used as an example of global warmin g\, with an implicit linkage to human activities. However\, the link to a nthropogenic forcing is not clear because the ice sheet may be in an unsta ble configuration\, and the region is subject to large internal climate va riability. In this talk I will summarise the available observations of ic e\, ocean\, and atmosphere in the region\, and then present evidence from climate model simulations. The combined evidence suggests that the ongoing ice loss is partly caused by ice sheet instability and partly by climate forcing. Of the forcing\, part is anthropogenic. As a result of this com bination of factors\, it is not clear how the Antarctic Ice Sheet will res pond to future emissions scenarios.\n LOCATION:https://researchseminars.org/talk/BAS-PO/21/ END:VEVENT BEGIN:VEVENT SUMMARY:Mainak Mondal (New York University Abu Dhabi) DTSTART:20210714T130000Z DTEND:20210714T140000Z DTSTAMP:20260422T225718Z UID:BAS-PO/22 DESCRIPTION:Title: Turbulent melting of a glacier front using high resolution simulations \nby Mainak Mondal (New York University Abu Dhabi) as part of BAS Polar Oc eans Seminar\n\n\nAbstract\nOver the past few years\, valuable new observa tions from the glacial front of Antarctica and Greenland using high-resolu tion turbulence profilers at the ice shelf borehole (Davis and Nicholls 20 19\; Kimura et al. 2015\; Begeman et al. 2018\; Jenkins et al. 2010) itera ted the importance of turbulent processes in controlling the melting and d issolution of the ice-ocean interface. Previous laboratory experiments (Mc Connochie et. al.\, 2015\,17\,18) and high-resolution numerical simulation s (Gayen et al.\, 2015\, Mondal et. al\, 2019\, Vreghdenhil et al.\, 2020 Couston et al.\,2021) also have extensively discussed the role of turbulen ce in the basal melting. My talk spans from turbulence-resolving scales u p to the full depth of a fjord. At the turbulence scale\, I investigated h ow the turbulent melting/freezing at the ice-interface is affected by ice- geometry\, surface-roughness\, ambient velocity shear and external subglac ial discharge using fluid-only Direct Numerical Simulations. At the large scale\, I investigated the dynamics of a subglacial discharge plume subjec ted to varying subglacial conduit size\, shape and distributions as well as 3d ice-geometry using the MITgcm plume model. These insights can help t o provide better estimations of the melting of the ice-face\, essential fo r more accurate projections of future sea-level rise.\n LOCATION:https://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:20260422T225718Z UID:BAS-PO/23 DESCRIPTION:Title: The impact of sea-ice drift and ocean circulation on dispersal of toothfis h eggs and juveniles in the Ross Gyre and Amundsen Sea\nby Erik Behren s (National Institute of Water and Atmospheric Research) as part of BAS Po lar Oceans Seminar\n\n\nAbstract\nKnowledge about the early life history o f Antarctic toothfish (Dissostichus mawsoni) is still incomplete\, particu larly on the spatial and temporal extent of spawning and the subsequent tr ansport of eggs\, larvae\, and juveniles from the offshore spawning areas to the continental shelf. This study uses a high-resolution hydrodynamic m odel to investigate the impact of ocean circulation and sea-ice drift on t he dispersal of eggs\, larvae\, and juvenile Antarctic toothfish. The virt ual eggs are released on seamounts of the Pacific-Antarctic ridge in the R oss Gyre and advected using hydrodynamical model data. Particles are seede d annually over the years 2002 to 2016 and tracked for three years after t heir release. Recruitment success has been evaluated based on the number o f juveniles that reached known coastal recruitment areas\, between the eas tern 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 se cond winter season as this carries them into the open ocean away from the shelf region. Recruitment success increases during the second winter seaso n if juveniles are entrained in the Ross Gyre circulation or if they activ ely swam towards the shelf. These modelling results suggest that the ecolo gical advantage of sea-ice association in the early life cycle of toothfis h diminishes as they grow\, promoting a behaviour change during their seco nd winter.\n LOCATION:https://researchseminars.org/talk/BAS-PO/23/ END:VEVENT BEGIN:VEVENT SUMMARY:Andrew Stewart (UCLA) DTSTART:20211103T153000Z DTEND:20211103T163000Z DTSTAMP:20260422T225718Z UID:BAS-PO/24 DESCRIPTION:Title: High-frequency fluctuations in Antarctic Bottom Water transport driven by Southern Ocean winds\nby Andrew Stewart (UCLA) as part of BAS Polar Oc eans Seminar\n\n\nAbstract\nNorthward flow of Antarctic Bottom Water (AABW ) across the Southern Ocean comprises a key component of the global overtu rning circulation. Yet AABW transport remains poorly constrained by observ ations and state estimates\, and there is presently no means of directly m onitoring any component of the Southern Ocean overturning. However\, AABW flow is dynamically linked to Southern Ocean surface circulation via the z onal momentum balance\, offering potential routes to indirect monitoring o f the transport. Exploiting this dynamical link\, this study uses a dynami cally self-consistent ocean state estimate (ECCOV4r4) to show that wind st ress fluctuations drive large AABW transport fluctuations on time scales s horter than ~2 years\, which comprise almost all of the transport variance . This connection occurs due to differing time scales on which topographic and interfacial form stresses respond to wind variability\, likely associ ated with differences in barotropic vs. baroclinic Rossby wave propagation . These findings imply that AABW transport variability can largely be reco nstructed from the surface wind stress alone.\n LOCATION:https://researchseminars.org/talk/BAS-PO/24/ END:VEVENT BEGIN:VEVENT SUMMARY:Robbie Mallett (University College London) DTSTART:20211117T140000Z DTEND:20211117T150000Z DTSTAMP:20260422T225718Z UID:BAS-PO/25 DESCRIPTION:Title: Snow on sea ice: poorly observed\, poorly modelled\, poorly understood \nby Robbie Mallett (University College London) as part of BAS Polar Ocean s Seminar\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/BAS-PO/25/ END:VEVENT BEGIN:VEVENT SUMMARY:Gemma O'Conor (University of Washington) DTSTART:20211108T140000Z DTEND:20211108T150000Z DTSTAMP:20260422T225718Z 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\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/BAS-PO/26/ END:VEVENT BEGIN:VEVENT SUMMARY:Chen Zhao (University of Tasmania) DTSTART:20211201T100000Z DTEND:20211201T110000Z DTSTAMP:20260422T225718Z UID:BAS-PO/27 DESCRIPTION:Title: Representation of basal melting in idealised coupled ice sheet ocean model s\nby Chen Zhao (University of Tasmania) as part of BAS Polar Oceans S eminar\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/BAS-PO/27/ END:VEVENT BEGIN:VEVENT SUMMARY:Oana Dragomir (National Oceanography Centre\, Southampton) DTSTART:20211215T140000Z DTEND:20211215T150000Z DTSTAMP:20260422T225718Z UID:BAS-PO/28 DESCRIPTION:Title: Variability of the Undercurrent in the Amundsen Sea inferred from satellit e altimetry\nby Oana Dragomir (National Oceanography Centre\, Southamp ton) as part of BAS Polar Oceans Seminar\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/BAS-PO/28/ END:VEVENT BEGIN:VEVENT SUMMARY:Isabel Nias (University of Liverpool) DTSTART:20220126T140000Z DTEND:20220126T150000Z DTSTAMP:20260422T225718Z UID:BAS-PO/29 DESCRIPTION:Title: Quantifying and reducing uncertainty in projections of sea level rise from ice sheets\nby Isabel Nias (University of Liverpool) as part of BAS P olar Oceans Seminar\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/BAS-PO/29/ END:VEVENT END:VCALENDAR