This study assessed total hydrocarbon content and polycyclic aromatic hydrocarbon content in Grönfjord (the Greenland Sea, Svalbard). The field study was held in marine expeditions of research vessel “Barentsburg” by the North-Western Branch of the Federal State Budget Institution, Research and Production Associaton «Typhoon» in summer periods of 2012 to 2022. In the framework of the field works simultaneous measurements of hydrological and hydrochemical characteristics of the water column were done. The data was analyzed using standard procedure in purpose to gather new information about the levels of hydrocarbons    (measured as total hydrocarbon contents), polycyclic aromatic hydrocarbons. The results showed pronounced interannual variations of total hydrocarbon contents and polycyclic aromatic hydrocarbons concentrations. Supposed that local natural sources contribute to elevated polycyclic aromatic hydrocarbons and total hydrocarbon content levels both in water and in sediments,  the levels of contamination do not signify exclusively anthropogenic influence on the sea-body. At the same time, some local elevated petroleum hydrocarbons concentrations, which were detected in the surface water layer, may be a sign of existing industrial activity affecting the waters of the fjord. Continuity of tasks starting from earlier expeditions indicates that many processes in the Norwegian Sea, Greenland Sea require further research.

Ocean acidification driven by the uptake of anthropogenic CO2 represents a major threat to ocean ecosystems, yet little is known about its progression beneath the surface. Here, we reconstruct the history of ocean interior acidification (OIA) from 1800 to 2014 on the basis of observation-based estimates of the accumulation of anthropogenic carbon. Across the top 100 m and over the industrial era, the saturation state of aragonite (Ωarag) and pH = -log[H+] decreased by more than 0.6 and 0.1, respectively, with a progress of nearly 50% over the last 20 years (1994-2014). While the magnitude of the Ωarag change decreases uniformly with depth, the magnitude of the pH decrease exhibits a distinct maximum in the upper thermocline. Since 1800, the saturation horizon (Ωarag=1) shoaled by more than 200 m, approaching the euphotic zone in several regions, especially in the Southern Ocean, and exposing many organisms to corrosive conditions.

A version of This Work has been submitted to _J. Physical Oceanography_ This Work has not yet been peer-reviewed and is provided by the contributing Author(s) as a means to ensure timely dissemination of scholarly and technical Work on a noncommercial basis. Copyright and all rights therein are maintained by the Author(s) or by other copyright owners. It is understood that all persons copying this information will adhere to the terms and constraints invoked by each Author’s copyright. This Work may not be reposted without explicit permission of the copyright owner. Copyright in this Work may be transferred without further notice. ABSTRACT Deep estuaries are often separated from the open ocean by sills and constrictions. These constrictions are areas of intense mixing often dominating the total estuarine mixing. The amount and depth of the estuarine exchange depends sensitively on the mixing and the densities of the waters on the two sides of the mixing region. Thus, the density, nutrient concentration, oxygen saturation, and dissolved inorganic carbon content of the incoming estuarine flow depend on local tidal mixing processes and large scale buoyancy dynamics. We have investigated this process using a numerical model (SalishSeaCast) of the Salish Sea on the West Coast of North America, straddling the Canada/USA border. The region receives considerable freshwater dominated by the outflow of the Fraser River. The Fraser River first flows into the deep Strait of Georgia but the freshwater must traverse the strongly tidally mixed shallower passages through the Gulf/San Juan Islands before it reaches the Pacific Ocean. The model correctly reproduces the deep water flow into the Strait of Georgia as evaluated against Ocean Networks Canada (ONC) four bottom-mounted, continuously recording, conductivity-temperature instruments which capture this incoming flow. Using a four-year hindcast from the model we determine the amount, depth and position of the outflow and inflow. We show that 95% of the variance of the 4-day average baroclinic flux through the tidal mixing region can be explained by the density difference across the region and a Richardson Number based on the tidal velocities. The outgoing flux includes both surface and intermediate waters and the incoming flux includes both intermediate and deep waters. Laterally, fluxes into and out of the Strait of Georgia and across Victoria Sill show the impact of the Coriolis force and local bathymetry. INTRODUCTION A classic lock exchange experiment in a laboratory separates two different densities by a lock that is removed (_e.g._ ). As the lock is removed, the lighter water flows over the heavier and the heavier water flows under the lighter. These two gravity current flows travel quickly, on the order of the internal wave speed, quickly redistributing the density. Performing the experiment on a rotating table reduces the lateral width of the gravity currents but does not significantly change their speed . On the other hand, introducing turbulence, say in the form of a bubble region, breaks up the gravity currents and significantly increases the time for density exchange . These basic dynamics, a contrast in densities driving exchange, and turbulence reducing the rate of exchange, are expected to explain real oceanographic situations. Here we look at their application to an estuarine system with a highly constricted, very turbulent tidal mixing “hotspot”. Using the results from a well-resolved three-dimensional ocean model, we ask if the laboratory dynamics apply and what they tell us about the exchange flow for this estuary. In the oceanographic literature, the estuarine exchange problem has a long, and mostly separate history from these laboratory studies. In a real estuary, the problem is greatly complicated by the presence of tides. We cannot remove them (even from our model) as they are determining the mixing in the system. However, at any given time, the instantaneous velocity is largely determined by the tides, advecting water in and out. A traditional way to determine the net estuarine transport from observations is to assume two layers and to use Knudsen’s Relations, that is, conservation of water and salt. However, adding symmetrical mixing, as opposed to just entrainment into the upper layer, makes the system under-determined. One can use temperature and heating versus salinity to remove this ambiguity and then invert temperature and salinity profiles to determine the transport assuming a layer structure . The water advected in and the water advected out by the tides may be largely the same, and what we want to extract is the difference. From model results, one can analyze time averages, giving the tidally averaged velocities and tidally averaged salinity. However, this process neglects the strong correlations in the fluctuations. A more complete way to do this is to bin the water and salt fluxes by salinity bin and calculate TEF or total exchange flow . This method captures both the estuarine exchange flow and the transport due to the tides, and thus is a total or maximal exchange . The estuary we will consider is the large, semi-enclosed Strait of Georgia (SoG), which is connected to the Pacific Ocean through a western and a northern entrance (Figure [fig:map]). The primary flow is through the western entrance; the northern entrance is small and flux and exchange there are significantly smaller than at the west. The major source of fresh water is the Fraser River, about 60% of the total to the SoG which enters the SoG near its south end. At the south end of the SoG are the Gulf/San Juan Islands that form lateral constrictions. The water through this region is also shallower (Figure [fig:transects]). Thus, tidal flows are high, up to 4.5 m s−1, and turbulent mixing is strong (Figure [fig:transects]). Water exiting the SoG flows through this region and then into the relatively straight Juan de Fuca Strait (Figure [fig:map]), although there is a significant sill, Victoria Sill, at the eastern end of Juan de Fuca Strait (Figure [fig:transects]). Exchange through this region has been studied through observations and models . Exchange is seasonally variable with pulses of freshwater exiting Juan de Fuca Strait during the Fraser River Freshet, weak neap tides, and winds to the south in SoG . Deep water renewals similarly occur during neap tides during spring through fall . The observed dense water cascading from Boundary Pass Sill into the deep SoG has been successfully explained as a gravity current . Net fluxes have been estimated at 46 mSv out from Boundary Pass or 114 mSv in from Victoria Sill . These estimates are based on mass, salt and heat balances and are necessarily coarse in their vertical resolution and do not include lateral resolution. Using the TEF method the flux into the SoG is estimated as 83 mSv , updated to 70 mSv . These two estimates include both the estuarine component and the net tidal impact. Estimates not including the tidal impact are lower (28 mSv, ). However, all these estimates include both the flux that transitions the turbulent region and flux that is recycled within it. In particular, the flux into and out of Haro Strait is different in because much of the deep flow into Haro Strait is entrained into the surface flow and exits back out in the surface outflow to Juan de Fuca Strait. Indeed, although the exchange is maximum during neap tides, the maximum residual flow actually occurs at spring tides due to this entrained flux . This short-circuited flow is referred to as the reflux ( _e.g.,_ , ). Here we will use a Lagrangian tracking method that allows us to separate the reflux and focus on the flux that travels through the mixing region. This method does include the effect of the tides. Typically the SoG is divided into three layers: a surface layer above 50 m, an intermediate layer, and a deep layer below 200 m (e.g. , ; , ). Looking at the monthly climatology in the central SoG these depths would correspond to salinities of 30 g kg−1 (range 29.9 g kg−1 (July) to 30.4 g kg−1 (November)), for 50 m and 31.2 g kg−1 (range 31.0 g kg−1 (May) to 31.4 g kg−1 (October)) for 200 m.

Coral atoll islands, common in tropical and subtropical oceans, consist of low-lying accumulations of carbonate sediment produced by fringing coral reef systems and are of great socio-economic and ecological importance. Previous studies have predicted that many coral atoll islands will become uninhabitable before the end of this century due to sea level rise exacerbating wave-driven flooding. However, the assumption that such islands are morphologically static, and will therefore ‘drown’ as sea levels rise, has been challenged by observations and modelling that show the potential for overwashing and sediment deposition to maintain island freeboard. However, for sustainable habitation, reliable predictions of island adjustment, flooding frequency and the influence of adaptation measures are required. Here, we illustrate the effect of various adaptation measures on the morphological response of an atoll island to future sea level rise using process-based model simulations. We found that the assumption of a static island morphology leads to a significant increase in the predicted frequency of future island flooding compared to morphodynamically active islands, and demonstrate that natural morphological adjustment is a viable mechanism to increase island freeboard. Reef adaptation measures were shown to modify the inshore wave energy, influencing the equilibrium island crest height and therefore the long-term morphological response of the island, while beach restoration mainly delays the island’s response. If embraced and implemented by local communities, allowing for natural island dynamics and implementing well-designed adaptation measures could potentially extend the habitability of atoll islands well beyond current projections.

There is a lack of diversity amongst geoscience faculty. Therefore, many geoscience departments are taking steps to recruit and retain faculty from underrepresented groups. Here, we interview 19 geoscientists who identify as a member of an underrepresented race or gender who declined a tenure-track faculty job offer to investigate the factors influencing their decision. We find a range of key factors that influenced their decisions to accept or decline a position, including fit and resources, experiences during job interviews, negotiations and offers, family, geographic preferences, attention to DEI, personal identities, mentorship, hiring process, and teaching responsibilities. Despite existing recommendations for interventions to improve faculty diversity, many of the participants experienced hiring processes that did not follow these suggested best practices, suggesting that departments are not all aware of best hiring practices. Therefore, we leverage our results to provide actionable recommendations for improving the equity and effectiveness of faculty recruitment efforts. We find that institutions may doubly benefit from improving their culture: in addition to benefiting current members of the institution, it may also help with recruitment.

Estuaries are dynamic coastal features that support industry, food production, and recreation, and provide habitat for numerous animal species. Their typically low surface gradients make estuaries vulnerable to sea level rise, storms, and high river water discharge. This vulnerability combined with the large number of people who often live near estuaries has led to increasing efforts over recent decades to improve our understanding of how to minimize flooding and protect people and property. Despite these efforts, however, we still lack the tools to quantify the relationship between changes in estuarine morphology and flood risks. In particular, the interplay between bathymetric changes and water levels during storm conditions remains poorly quantified. To address this knowledge gap, we present a general enthalpy framework for modeling the evolution of estuaries that couples a low gradient subaerial topset and a subaqueous offshore region or foreset. Sediment transport in both the subaerial and subaqueous domains includes a non-linear term that relates sediment flux, local slope, and a threshold of motion. With this approach, we describe the evolution of the bathymetric profile and sediment partitioning between topset and foreset under a range of sea-level variations scenarios. We find that in some cases upstream sections of the topset can undergo erosion during periods of sea-level rise and deposition during sea-level fall, contradicting traditional stratigraphic models. These counterintuitive bathymetric changes could potentially lead to shifts in the location of maximum water levels along the estuary not accounted for by models of storm inundation.

The ICESat-2 (Ice, Cloud and Land Elevation Satellite-2) photon-counting laser altimeter technology required the design and development of very sophisticated onboard algorithms to collect, store and downlink the observations. These algorithms utilize both software and hardware solutions for meeting data volume requirements and optimizing the science achievable via ICESat-2 measurements. Careful planning and dedicated development were accomplished during the pre-launch phase of the mission in preparation for the 2018 launch. Once on-orbit all of the systems and subsystems were evaluated for performance, including the receiver algorithms, to ensure compliance with mission standards and satisfy the mission science objectives. As the mission has progressed and the instrument performance and data volumes were better understood, there have been several opportunities to enhance ICESat-2’s contributions to earth observation science initiated by NASA and the ICESat-2 science community. We highlight multiple updates to the flight receiver algorithms, the onboard software for signal processing, that have extended ICESat-2’s data capabilities and allowed for advanced science applications beyond the original mission objectives.

The end-Triassic extinction (ETE) is one of the most severe biotic crises in the Phanerozoic. This event was synchronous with volcanism of the Central Atlantic Magmatic Province (CAMP), the ultimate cause of the extinction and related environmental perturbations. However, the continental weathering response to CAMP-induced warming remains poorly constrained. Strontium isotope stratigraphy is a powerful correlation tool that can also provide insights into the changes in weathering regime but the scarcity of 87Sr/86Sr data across the Triassic-Jurassic boundary (TJB) compromised the use of this method. Here we present new high-resolution 87Sr/86Sr data from bulk carbonates in Csővár, a continuous marine section that spans 2.5 Myrs across the TJB. We document a continuing decrease in 87Sr/86Sr the from the late Rhaetian to the ETE, terminated by a 300 kyr interval of no trend and followed by a transient increase in the early Hettangian that levels off. We suggest that the first in the series of perturbations is linked to the influx of non-radiogenic Sr from the weathering of freshly erupted CAMP basalts, leading to a delay in the radiogenic continental weathering response. The subsequent rise in 87Sr/86Sr after the TJB is explained by intensified continental crustal weathering from elevated CO2 levels and reduced mantle-derived Sr flux. Using Sr flux modeling, we also find support for such multiphase, prolonged continental weathering scenario. Aggregating the new dataset with published records employing an astrochronological age model results in a highly resolved Sr isotope reference curve for an 8.5 Myr interval around the TJB.

Water temperature is an important environmental factor for the growth of eelgrass (Zostera marina) beds, which provide important nearshore ecosystem services. Here, we study water temperature dynamics in eelgrass beds off the Atlantic coast of Nova Scotia using a highresolution nearshore oceanographic model based on the Finite Volume Community Ocean Model (FVCOM). The model has been evaluated against the observed temperature at six sites for three years from 2017-2019; the evaluation indicates that the model is able to replicate the temperature variation on time scales from hours to seasonal. We also use various temperature metrics relevant to eelgrass condition, including mean seasonal values and variability, daily ranges, growing degree day, and warm events, to both validate the model and better understand the temperature regime at the study sites. Our analyses showed that eelgrass inhabit a wide range of temperature conditions that have previously been shown to influence their performance. The mean water temperature during the summer growing period differs by more than 7°C between the shallowest and the deepest sites. The rate of heat accumulation was faster at shallow sites, and they experienced ≥ 12 extreme warm events year-1. While the amplitude of the temperature variations within the high frequency band (<48 hr) was greater in shallower sites, temperature changes on meteorological time scales (48 hr to 60 days) were coherent at all sites suggesting the importance of coast-wide processes. The results of this study demonstrate that our high resolution numerical model can capture biologically relevant temperature dynamics at different time scales and over a large spatial region and yet still capture detailed temperature dynamics at specific nearshore sites. It therefore has the potential to contribute to conservation planning and prediction of eelgrass response to future climate changes.

The ice streams flowing into the Amundsen Sea, West Antarctica, are losing mass due to changes in the oceanic basal melting of their floating ice shelves. Rapid ice-shelf melting is sustained by the delivery of warm Circumpolar Deep Water to the ice-shelf cavities, which is first supplied to the continental shelf by an undercurrent that flows eastward along the shelf break. Temporal variability of this undercurrent controls ice-shelf basal melt variability. Recent work shows that on decadal timescales the undercurrent variability opposes surface wind variability. Using a regional model, we show that undercurrent variability is driven by sea-ice freshwater fluxes, particularly those north of the shelf break, which affect the cross-shelf break density gradient. This sea-ice variability is caused by tropical Pacific variability impacting atmospheric conditions over the Amundsen Sea. Ice-shelf melting also feeds back onto the undercurrent by affecting the on-shelf density, thereby influencing shelf-break density gradient anomalies.

A document by Daniel E. Amrhein. Click on the document to view its contents.

Antarctic ice shelves are losing mass at drastically different rates, primarily due to melting by relatively warm Circumpolar Deep Water (CDW). Previous studies have identified seafloor bathymetry as a key obstacle to CDW intrusions across the continental shelf and beneath ice shelves, but a generalized theory for geometrically-influenced ice melt is lacking. This study proposes such a theory based on geostrophically-constrained CDW inflow, combined with a threshold bathymetric elevation that obstructs CDW access to ice shelf grounding lines, called the Highest Unconnected isoBath (HUB). This theory captures $~90\%$ of the variance in melt rates across a suite of process-oriented ocean/ice shelf simulations with various quasi-randomized geometries. Applied to observed ice shelf geometries and offshore hydrography, the theory captures $>80\%$ of the variance in measured ice shelf melt rates. These findings provide a generalized theoretical framework for melt resulting from buoyancy-driven CDW access to geometrically complex Antarctic ice shelf cavities.

The interaction between the internal tide and the mesoscale circulation are studied from the internal tide energy budget perspective. To that end, the modal energy budget of the internal tide is diagnosed using a high resolution numerical simulation covering the North Atlantic. Compared to the topographic contribution, the advection of the internal tide by the background flow and the horizontal and vertical shear are found to be significant at global scale, while the buoyancy contribution is important locally. The advection of the internal tide by mesoscale currents is responsible for a net energy transfer from the large scale to smaller scale internal tide, without significant exchanges with the background flow. On the opposite, the shear of the mesoscale circulation and the buoyancy field are responsible for exchanges between the internal tide and the background flow. The importance of the shear increases in the northernmost part of the domain, and a partial compensation between the buoyancy and the shear contributions is found in some areas of the North Atlantic, such as in the Gulf Stream region. In addition, the temporal variability of the topographic, advection, mesoscale shear and buoyancy gradient induced energy transfers is investigated. The spring neap cycle is the dominant frequency for the topographic scattering, but other frequencies modulate this term in areas of strong mesoscale activity. Mesoscale induced energy fluxes are modulated by both the spring neap cycle and the variation in the mesoscale circulation patterns.

As oceanic moisture evaporates, it leaves a signature on sea surface salinity. Roughly 10% of the moisture that evaporates over the ocean is transported over land, allowing the salinity fields to be a predictor of terrestrial precipitation. This research is among the first in published literature to assess the role of sea surface salinity for improved predictions on low-skill summertime subseasonal timescales for terrestrial precipitation predictions. Neural networks are trained with the CESM2 Large Ensemble using North Atlantic salinity anomalies to quantify predictability of U.S. Midwest summertime heavy rainfall events at 0 to 56-day leads. Using explainable artificial intelligence, salinity anomalies in the Caribbean Sea and Gulf of Mexico are found to provide skill for subseasonal forecasts of opportunity, e.g. confident and correct predictions. Further, a moisture-tracking algorithm applied to reanalysis data demonstrates that the regions of evaporation identified by neural networks directly provide moisture that precipitates in the Midwest.

Geographical distributions and frequency content of ocean surface kinetic energy (KE) are estimated in a 1/48° high-resolution global numerical model of the ocean circulation. Eulerian (fixed-point) KE rotary frequency spectra and band-integrated energy levels (e.g., low-frequency, tidal and near-inertial) are considered as references which are compared to Lagrangian (along-flow) estimates. Eulerian and Lagrangian KE exhibit broad qualitative similarities with dominance of low-frequency motions and presence of distinct spectral peaks at semidiurnal, near-inertial, and diurnal frequencies. One notable difference is that, apart for the near-inertial band, Lagrangian spectra are systematically smoother, e.g., with wider and lower spectral peaks compared to Eulerian counterparts. Nevertheless, no significant differences are found between Lagrangian and Eulerian global KE levels provided adequate frequency bandwidths are chosen. Our findings demonstrate that Lagrangian observations of the Global Drifter Program have great potential to accurately map global KE variability at high frequencies (e.g., tidal and near-inertial). 

Two moorings deployed for 75 days in 2019 and long-term satellite altimetry data reveal a spatially complex and temporally variable internal tidal field at the SWOT Cal/Val site off central California due to the interference of multiple seasonally-variable sources. Coherent tides account for $\sim$45\% of the potential energy. The south mooring exhibits more energetic semidiurnal tides, while the north mooring displays stronger mode-1 M$_2$ with an amplitude of $\sim$5.1 mm. These findings from in situ observations align with the analysis of 27-year altimetry data. The altimetry results indicate that the complex internal tidal field is attributed to multiple sources. Mode-1 tides primarily originate from the Mendocino Ridge and the 36.5\textendash37.5$^\circ$N California continental slope, while mode-2 tides are generated by local seamounts and Monterey Bay. The generation and propagation of these tides are influenced by mesoscale eddies and seasonal stratification. Seasonality is evident for mode-1 waves from three directions. Southward components from the Mendocino Ridge consistently play a dominant role ($\sim$268 MW) yearlong. We observed the strongest eastward waves during the fall and spring seasons, generated remotely from the Hawaiian Ridge. Westward waves from the 36.5\textendash37.5$^\circ$N California continental slope are weakest during summer, while those from the Southern California Bight are weakest during spring. The highest variability of energy flux is found in the westward waves ($\pm 22\%$), while the lowest is in the southward waves ($\pm 13\%$). These findings emphasize the importance of incorporating the seasonality and spatial variability of internal tides for the SWOT internal tidal correction.

Marine forecasts are essential for safe navigation, efficient offshore operations, coastal management, and research, especially in areas with a such harsh conditions as the Arctic Ocean. They require accurate predictions of ocean currents, wind-driven waves, and other oceanic parameters. However, physics-based numerical models, while precise, are computationally demanding. Consequently, data-driven methods, which are less resource-intensive, may offer a more efficient solution for sea state forecasting. This paper presents an analysis and comparison of three data-driven models: our newly developed convLSTM-based MariNet, FourCastNet and the PhydNet, a physics-informed model for video prediction. Using metrics such as RMSE, Bias and Correlation, we demonstrate the areas where our model surpasses the performance of the prominent prediction models. Our model achieves improved accuracy in forecasting ocean dynamics compared to FourCastNet and PhyDNet. We also find that our model requires significantly less training data, computing power, and consequently provides less carbon emmisions. The results suggest that data-driven models should be further explored as a complement to physics-based models for operational marine forecasting. They have the potential to enhance prediction accuracy and efficiency, enabling more responsive and cost-effective forecasting systems.

The eastern subpolar North Atlantic upper ocean salinity undergoes decadal fluctuations. A large fresh anomaly event occurred during 2012--2016. Using the ECCO state estimate, we diagnose and compare mechanisms of this low salinity event with that of the 1990s fresh anomaly event. To avoid erroneous interpretations of physical mechanisms due to reference salinity values in the freshwater budget, we perform a salt mass content budget analysis of the eastern subpolar North Atlantic. It shows that the recent fresh anomaly occurs due to the circulation of anomalous salinity by mean currents entering the eastern subpolar basin from its western boundary via the North Atlantic Current. This is in contrast to the early 1990s, when the dominant mechanism governing the fresh anomaly was the transport of the mean salinity field by anomalous currents across the southern boundary of the subpolar North Atlantic.

The increasing movement and deformation of Arctic sea ice cover results in pronounced drag sheltering effects behind sea ice pressure ridges. This needs to be accounted for in the parameterization of the form drag of ridges, thereby posing a challenge to evaluate the ice–ocean dynamic feedback. Laboratory experiments were conducted in a water tank to explore the sheltering effect between adjacent ridges of various geometries. The form drag forces on the keel models were measured, and the particle image velocimetry (PIV) system was employed to capture the flow fields surrounding the models to explain the variations in the drag force. The key sheltering parameters were the ratio between keel spacing and keel depth L/H, flow velocity u, and keel slope angle α. The results showed that the drag force F1 on the upstream keel was close to the value of the single keel case, while the drag force F2 on the downstream keel was lower, for L/H ≤ 10 even opposite to the flow direction. Having changed from negative to positive, the sheltering coefficient Г = F1/F2 increased with increasing L/H. Г decreased remarkably with steepening α and was independent of u. To fully incorporate the effects of the L/H and α , we propose a new sheltering function fitted with the experimental results:Г =[1-1.56exp(sL/H)]*1.20α-0.08, s=0.001α-0.15. This function is compared with the previous sheltering functions and the actual ice conditions in the Arctic Ocean, pointing the way to obtain the final sheltering functions applicable to sea ice dynamics models.

The sea-ice cover in the Barents and Kara Seas (BKS) displays pronounced interannual variability. Both atmospheric and oceanic drivers have been found to influence sea-ice variability, but their relative strength and regional importance remain under debate. Here, we use the Liang-Kleeman information flow method to quantify the causal influence of oceanic and atmospheric drivers on the annual sea-ice cover in the BKS in the Community Earth System Model large ensemble and reanalysis. We find that atmospheric drivers dominate in the northern part, ocean heat transport dominates in the central and northeastern part, and local sea-surface temperature dominates in the southern part. Furthermore, the large-scale atmospheric circulation over the Nordic Seas drives ocean heat transport into the Barents Sea, which then influences sea ice. Under future sea-ice retreat, the atmospheric drivers are expected to become more important.

• Two fresh anomalies observed in the eastern subpolar North Atlantic upper ocean during 1992-2017 share similar spatial characteristics. • Salt budget analysis shows the 2012-2016 fresh anomaly in the upper 200 m occurs due to transport of anomalous salinity by mean currents. • In contrast, the fresh anomaly in the 1990s is due to anomalous circulation of the mean salinity field.

Synthetic downscaling of tropical cyclones (TCs) is critically important to estimate the long-term hazard of rare high-impact storm events. Existing downscaling approaches rely on statistical or statistical-deterministic models that are capable of generating large samples of synthetic storms with characteristics similar to observed storms. However, these models do not capture the complex two-way interactions between a storm and its environment. In addition, these approaches either necessitate a separate TC size model to simulate storm size or involve post-processing to introduce asymmetries in the simulated surface wind. In this study, we present an innovative data-driven approach for TC synthetic downscaling. Using a machine learning-based high-resolution global weather model (ML-GWM), our approach is able to simulate the full life cycle of a storm with asymmetric surface wind that accounts for the two-way interactions between the storm and its environment. This approach consists of multiple components: a data-driven model for generating synthetic TC seeds, a blending method that seamlessly integrate storm seeds into the surrounding while maintain the seed structure, and a recurrent neural network-based model for correcting the biases in maximum wind speed. Compared to observations and synthetic storms simulated using existing statistical-deterministic and statistical downscaling approaches, our method shows the ability to effectively capture many aspects of TC statistics, including track density, landfall frequency, landfall intensity, and outermost wind extent. Taking advantage of the computational efficiency of ML-GWM, our approach shows substantial potential for TC regional hazard and risk assessment.

c\cite{Beck_2021,Claudet_2020,Cunsolo_2018,Franke_2020,process,Jung_2022,Kemmis_2014} In 2021, and again in 2022, our globally scattered group of artists and scientists followed the Exquisite Corpse process for co-creating multiple threaded series of artworks inspired by extreme ocean events. In 2023 some members of our two groups convened a series of collaborative synchronous sessions to create a shared understanding of the paths we took to join this creative community and engage in this open ArtScience collaboration.Prompted by a sense of curiosity, a shared passion for the ocean and the will to collaborate, artists and scientists came together (virtually) to forge relationships around the shared intent to deepen our understanding of transdisciplinary ArtScience and how it can contribute to ocean knowledge. Discovering common ground (and creating a grounded commons) and mutual interests, we set forth on a path of curiosity into a formal Exquisite Corpse cycle. We created an array of art projects drawn from a semi-ambiguous “seed” within a semi-safe, not-always-comfortable space for experimentation and creation. Through cyclical introspection, enactment, opening, giving, and receiving, we developed our artwork series and relationships among our group. Finally, in the sharing of these series, we experienced new insights about our individual and collective perceptions of extreme ocean events, while simultaneously further deepening our relationships and appreciation for the potency of ArtScience collaborations.This poster was presented at the AGU23 Meeting in San Francisco, CA, on 13 December 2023. Conference abstract URL: https://agu.confex.com/agu/fm23/meetingapp.cgi/Paper/1266010

Surface semi-geostrophic turbulence is examined in this study. In our simulations, the strength of the ageostrophic component of the flows is controlled by the Rossby number ε, varying from 0.01 to 0.2. The flows manifest a cyclone-anticyclone asymmetry with a cyclonic preference for cold vortices and an anticyclonic preference for warm filaments. This asymmetry becomes especially pronounced in the flows with large ε, where an abundance of warm filaments is observed. Strong vertical motions concentrate in the small-scale filaments and at the periphery of the vortices. There, the lateral divergence becomes significant. A negative correlation between the divergence and the relative vorticity is identified using joint probability density functions. Slopes of the kinetic and potential energy spectra vary between -2.2 and -1.7 at intermediate scales. Analyses of spectral fluxes demonstrate an inverse kinetic energy cascade and a forward cascade of potential energy. As ε increases, the filaments become more numerous in the flows. They wrap around cyclones, weakening their interactions and subsequent mergers, thus suppressing the inverse cascade of kinetic energy. We characterize lateral dispersion in the SSG flows using the finite-scale Lyapunov exponents (FSLEs). They are used to identify Lagrangian coherent structures, such as those created by the interaction of vortices. The FSLEs are also used to investigate the regimes of dispersion at different scales. The results show a smooth transition from hyper-ballistic diffusion at small scales to normal diffusion at large scales.