Extratropical cyclones are weather phenomena with significant transfer of energy between the surface (over the ocean or on land) and the atmosphere. Recurrently, reanalysis data are used to understand the behavior of cyclonic tracks and to study extreme events, with constant updates and validations with the observational base in the Northern Hemisphere. However, studies using cyclone tracking in the Southwestern Atlantic, has proven more difficult. This disagreement seems to be in function of the structure and intensity of the forcing factors that influence both cyclogenesis and the displacement to the South Atlantic, when compared to the Northern Hemisphere. In this work, synoptic pressure charts at sea level, manually made and processed by the Brazilian Navy every 12 hours between the years 2010 and 2020, as a product resulting from a consensus among Navy meteorologists, were used to study the cyclonic pathways in the Southwestern Atlantic (METAREA V). Data obtained for all cyclones identified in the charts, based on their position and displacement, formed a database with 10737 cyclones, containing speed, dimensions, and pressure gradient. The cyclones identified have a higher radius frequency between 200/400 km and a faster-moving center shift. In addition, about 60% of cyclones associated with cold fronts have a life cycle ranging from 3 to 4 days. There is also a expressive cyclogenesis between latitudes 23ºS and 43ºS where, in austral autumn winter, increases its frequency over the ocean and close to the southern Brazilian coast. During spring, the greater cyclogenesis frequency occurs over the continent, close to Chaco area in Argentina and Uruguay. The impacts of these statistical figures on the south and southeastern Brazilian coast, mainly the continental insertion point of the cold fronts and cyclonic displacement that influence rough seas and storm surges, are discussed in this work. Keywords: EXTRATROPICAL CYCLONES, CYCLONE TRACK, SYNOPTIC CHARTS, SOUTHWESTERN ATLANTIC

Research on Atmospheric Rivers (ARs) has focused primarily on AR (thermo)dynamics and hydrological impacts over land. However, the evolution and potential role of nearshore air-sea fluxes during landfalling ARs are not well documented. Here, we examine synoptic evolutions of nearshore latent heat flux (LHF) during strong late-winter landfalling ARs (1979–2017) using 138 over-shelf buoys along the U. S. west coast. Composite evolutions show that ARs typically receive upward (absolute) LHF from the coastal ocean. LHF is small during landfall due to weak air-sea humidity gradients but is strongest (30–50 W/m^2 along the coast) 1–3 days before/after landfall. During El Niño winters, southern-coastal LHF strengthens, coincident with stronger ARs. A decomposition of LHF reveals that sea surface temperature (SST) anomalies modulated by the El Niño—Southern Oscillation dominate interannual LHF variations under ARs, suggesting a potential role for nearshore SST and LHF influencing the intensity of landfalling ARs.

Submerged aquatic vegetation in estuaries and coastal areas can alter the hydrodynamics of coastal waves by attenuating the energy of waves generated by storm surges and cyclones. Generally, wave attenuation by seagrass meadows is studied by considering a constant vegetation drag coefficient across the meadow which is an oversimplification. This study provides a better understanding of how submerged vegetation alters surface wave amplitude and velocity by developing a coupled flow-vegetation interaction model, which consists of a nonhydrostatic wave model and a numerical model for vegetation blade dynamics. The model captures wave attenuation rate and quantifies the effect of vegetation flexibility on wave attenuation. The vegetation model divides up each blade into an arbitrary number of segments that allows us to simulate strong deflection of blades under combined wave and current conditions. The two models are dynamically coupled which means that at each time step, the hydrodynamic model solves the free surface elevation and depth-varying velocity which is then used as input for the vegetation model. Then, the vegetation model calculates the effective drag coefficient of each segment of a stem in the canopy that is dependent on the forces applied over the blade and orientation of the blade. The computed vertically variable vegetation drag coefficient of each stem is then used in the hydrodynamic model for the next time step. Model results suggest that considering a rigid vegetation with simplified drag coefficient would result in larger vegetation-induced damping compared to flexible vegetation condition. The model results also confirm that there is a strong dependency between the vegetation-induced wave dissipation and vegetation parameters (e.g., canopy length and vegetation blade height).

Sea levels in the Western North Pacific (WNP) are presented with anomalous intraseasonal variations. This study examines the response of sea level in the WNP to the atmospheric Intraseasonal Oscillation modes, namely the Madden-Julian Oscillation (MJO) and the Boreal Summer Intraseasonal Oscillation (BSISO), using the 25 years (1993-2017) of satellite altimetry and barotropic model output. In winter, the MJO has significant effects on the component of sea level due to the instant wind and atmospheric pressure effects (high-frequency), showing an eastward propagation pattern in most regions, with the strongest effects in the western marginal seas. The MJO-associated pattern of dynamical (low-frequency) component of sea level propagates southward, with the significant effects mostly in the tropics. In summer, the BSISO-associated pattern of the high-frequency component of sea level moves from southwest to northeast, with the largest anomalies in the middle of WNP (20{degree sign}N-30{degree sign}N), while the strongest BSISO effects on the low-frequency component are detectable mostly in the coasts of China and east of the Philippines. The MJO and BSISO can also modulate the probability of extreme sea level events. In winter, during phases 2-5, MJO increases the chance of extreme high events in the high-frequency component of sea level by 100-200% in the western coasts and the tropics. In summer, in BSISO phases 6-7, the chance of extreme high events in the high-frequency component of sea level is enhanced by >300% in the South China Sea and east of the Philippines.

Carbon and nitrogen dynamics in the Sea of Japan (SOJ) are rapidly changing. In this study, we investigated the carbon and nitrogen isotope ratios of particulate organic matter (δ13CPOM and δ15NPOM, respectively) at depths of ≤ 100 m in the southern part of the SOJ from 2016 to 2021. δ13CPOM and δ15NPOM exhibited multimodal distributions and were classified into four classes (I–IV) according to the Gaussian mixed model. A majority of the samples were classified as class II (n = 441), with mean ± standard deviation of δ13CPOM and δ15NPOM of –23.7 ± 1.2‰ and 3.1 ± 1.2‰, respectively. Compared to class II, class I had significant low δ15NPOM (-2.1 ± 0.8‰, n = 11), class III had low δ13CPOM (-27.1 ± 1.0‰, n = 21), and class IV had high δ13CPOM (-20.7 ± 0.8‰, n = 34). All the class I samples, whose δ15NPOM showed an outlier of total data sets, were collected in winter and had comparable temperature and salinity originating in Japanese local rivers. The generalized linear model demonstrated that the temperature and chlorophyll-a concentration had positive effects on δ13CPOM, supporting the active photosynthesis and phytoplankton growth increased δ13CPOM. However, the fluctuation in δ15NPOM was attributed to the temperature and salinity rather than nitrate concentration, which suggested that the δ15N of source nitrogen for primary production is different among the water masses.  These findings suggest that multiple nitrogen sources, including nitrates from the East China Sea, Kuroshio, and Japanese local rivers, contribute to the primary production in the SOJ.

Tidal currents are known to influence basal melting of Antarctic ice shelves through two types of mechanisms: local processes taking place within the boundary current adjacent to the ice shelf-ocean interface and far-field processes influencing the properties of water masses entering the cavity. The separate effects of these processes are poorly understood, limiting our ability to parameterize tide-driven ice shelf-ocean interactions. Here we focus on the small-scale processes within the boundary current and we apply a one-dimensional plume model to a range of ice base geometries characteristic of Antarctic ice shelves to study the sensitivity of basal melt rates to different representations of tide-driven turbulent mixing. Our simulations demonstrate that the direction of the relative change in melt rate due to tides depends on the approach chosen to parameterize entrainment of ambient water into the plume, a process not yet well constrained by observations. A theoretical assessment based on an analogy with tidal bottom boundary layers suggests that tide-driven shear at the ice shelf-ocean interface enhances mixing through the pycnocline. Under this assumption our simulations predict an increase in melt and freeze rates along the base of the ice shelf when adding tides into the model. An approximation is provided to account for this response in basal melt rate parameterizations that neglect the effect of tide-induced turbulent mixing

Atmosphere-ocean interactions are thermodynamically important in the development of explosive cyclones. An explosive cyclone which emerged in the Northwestern Atlantic in January 2018 received massive heat from the Gulf Stream and developed rapidly due to enhanced atmospheric instability. Ocean surface waves affect momentum and heat air-sea exchanges, but their roles in explosive cyclone development have not been examined. This study shows that waves enhance the development of the explosive cyclone using a coupled atmosphere-ocean-wave model. The developing waves increased sensible and latent heat supply by increasing the transfer coefficient and friction under the cyclone. The increased heat supply from the sea surface strengthened the convective instability in the lower atmosphere. The air was lifted to the middle troposphere near the bent-back front by a strong updraft and enhanced precipitation near the cyclone’s center. The resulting latent heat release produced positive potential vorticity in the lower troposphere and intensified the explosive cyclone development. Waves also enhanced vertical ocean mixing, and sea surface temperature (SST) warmed north of the Gulf Stream. Overall, the most dominant effect of waves for the explosive cyclone development was to increase the supply coefficients of sensible and latent heat. Introducing ocean surface waves into the numerical simulations improved the reproducibility of explosive cyclones, indicating the importance of waves in explosive cyclone development.

The sea surface salinity (SSS) maximum of the South Indian Ocean (the SISSS-max) is a high-salinity feature centered at 30°S, 90°E, near the center of the South Indian subtropical gyre. It is located poleward of a region of strong evaporation and weak precipitation. Using several different satellite and in situ datasets, we track changes in this feature since the early 2000’s. The centroid of the SISSS-max moves seasonally north and south, furthest north in late winter and farthest south in late summer. Interannually, the SISSS-max has moved on a northeast-southwest path about 1500 km in length. The size and maximum SSS of the feature vary in tandem with this motion. It gets larger (smaller) and saltier (fresher) as it moves to the northeast (southwest) closer to (further from) the area of strongest surface freshwater flux. The area of the SISSS-max almost doubles from its smallest to largest extent. It was maximum in area in 2006, decreased steadily until it reached a minimum in 2013, and then increased again. The seasonal variability of the SISSS-max is controlled by the changes that occur on its poleward, or southern, side, whereas intereannual variability is controlled by changes on its equatorward side. The variations in the SISSS-max are a complex dance between changes in evaporation, precipitation, wind forcing, gyre-scale ocean circulation and downward Ekman pumping. Its motion correlated with SSS changes throughout the South Indian Ocean and is a sensitive indicator of changes in the basin’s subtropical circulation.

The subpolar North Atlantic is a site of significant carbon dioxide, oxygen, and heat exchange with the atmosphere. This exchange, which regulates transient climate change and prevents large-scale hypoxia throughout the North Atlantic, is thought to be mediated by vertical mixing in the ocean's surface mixed layer. Here we present observational evidence that waters deeper than the conventionally defined mixed layer are affected directly by atmospheric forcing. When northerly winds blow along the Irminger Sea's western boundary current, the Ekman response pushes denser water over lighter water and triggers slantwise convection. We estimate that this down-front wind forcing is four times stronger than air--sea heat flux buoyancy forcing and can mix waters to several times the conventionally defined mixed layer depth. Slantwise convection is not included in most large-scale ocean models, which likely limits their ability to accurately represent subpolar water mass transformations and deep ocean ventilation.

In winter 2013, a sea ice breakout in the Beaufort Sea produced extensive fracturing and contributed to record regional ice export. Rheinlænder et al. (2022) simulated this event using the neXtSIM sea ice model, reproducing a realistic progression of lead opening and ice drift following the track of an anticyclone. In their study, Rheinlænder et al. (2022) highlighted strong winds and thin ice as key factors for breakouts. We draw on observational records to provide additional context for the driving mechanisms of breakout events. We show that wind direction, rather than speed, was the primary control on patterns of lead opening and breakout timing in 2013. Records of similar events over previous decades demonstrate that breakouts are common under anticyclonic forcing, including during years when the ice was thicker. These additional events can be used to further validate models such as neXtSIM and improve predictive capabilities for future breakouts.

We analyze two preindustrial experiments from the Community Earth System Model version 2 (CESM2) to characterize the impact of sea ice physics on regional differences in coastal sea ice production around Antarctica and the resulting impact on the ocean and atmosphere. The experiment in which sea ice is a “mushy” mixture of solid ice and brine has a substantial increase in coastal sea ice frazil and snow ice production that is accompanied by decreasing congelation growth and increasing bottom melt. With mushy ice physics, the subsurface ocean is denser and saltier, there is a statistically significant increase in Antarctic Bottom Water Formation by ~0.5 Sv, but differences in ocean biogeochemistry are minimal and only in regions where the summer ice state differs. While there are no significant changes in the atmospheric circulation, using “mushy” ice physics results in decreased turbulent heat flux, atmospheric convection, and low level cloud cover.

Internal tides (ITs) in the Indonesian seas were largely investigated and hotspots of intensified mixing identified in the straits in regional models and observations. Both of them indicate strong mixing up to 10⁻⁴cm/s even close to the surface and show that tides at spring-neap cycle cool by 0.2°C the surface water at ITs’ generation sites.These findings supported the idea of strong and surfaced mixing capable of providing cold and nutrient-rich water favorable for the whole ecosystem. However, it has never been assessed through an ad-hoc study. Our aim is to provide a quantification of ITs impact on chlorophyll-a through a coupled model, whose physical part was validated against the INDOMIX data in precedent studies and the biogeochemical part is compared to in-situ samples and satellite products. In particular, explicit tides’ inclusion within the model improves the representation of chlorophyll and of the analyzed nutrients. Results from harmonic analysis of chlorophyll-a demonstrate that tidal forcing modify spring/neap tides’ variability on the regions of maximum concentration in correspondence to ITs’ génération areas and to plateau sites where barotropic tides produce large friction reaching the surface. The adoption of measured vertical diffusivities explains the biogéochemical tracers’ transformation within the Halmahera Sea and used to estimate the nutrients’ turbulent flux, with an associated increase in new production of ~25% of the total and a growth in mean chlorophyll of ~30%. Hence, we confirm the key role of ITs in shaping vertical distribution and variability of chlorophyll as well as nutrients in the maritime continent.

The dispersal of dissolved iron (DFe) from hydrothermal vents is poorly constrained. Combining field observations and a hierarchy of models, we show that the dispersal of DFe from the Trans-Atlantic-Geotraverse vent site occurs predominantly in the colloidal phase and is controlled by multiple physical processes. Enhanced mixing near the seafloor and transport through fracture zones at fine-scales interacts with the wider ocean circulation to drive predominant westward DFe dispersal away from the Mid-Atlantic ridge at the 100km scale. In contrast, diapycnal mixing predominantly drives northward DFe transport within the ridge axial valley. The observed DFe dispersal is not reproduced by the coarse resolution ocean models typically used to assess ocean iron cycling due to their omission of local topography and mixing. Unless biogeochemical models include high-resolution nested grids, they will inaccurately represent DFe dispersal from axial valley ridge systems, which make up half of the global ocean ridge crest.

This study investigates the occurrence of mixed-phase clouds (MPC) over the Southern Ocean (SO) using space- and surface-based lidar and radar observations. The occurrence of supercooled clouds is dominated by geometrically thin (< 1km) layers that are rarely MPC. We diagnose layers that are geometrically thicker than 1 km to be MPC approximately 65%, and 4% of the time from below by surface remote sensors and from above by orbiting remote sensors, respectively. We examine the discrepancy in MPC as diagnosed from the below and above. From above, we find that MPC occurrence has a gradient associated with the Antarctic Polar Front near 55°S with the rare occurrence of satellite-derived MPC south of that latitude. In contrast, surface sensors find MPC in 33% of supercooled layers. We infer that space-based lidar cannot identify the occurrence of MPC except when secondary ice-forming processes operate in convection that is sufficiently strong to loft ice crystals to cloud tops. We conclude that the CALIPSO phase statistics of MPC have a severe low bias in MPC occurrence. Based on surface-based statistics, we present a parameterization of the frequency of MPC as a function of cloud top temperature that differs substantially from that used in recent climate model simulations.

• Phytoplankton distributions and primary productivity were assessed off the northern coast of Norway in spring. Biomass and productivity were greatest off the continental shelf during the period of observations. • A satellite climatology showed that blooms usually form on the continental shelf first, and spread to deeper waters from 2-4 weeks after the shelf bloom. • The Calanus finmarchicus population had the potential for removing substantial amounts of chlorophyll each day, but phytoplankton vertical distributions were controlled by passive sinking.

Oceanographic research cruises produce abundant data, using a wide range of methods and equipment; very often through large collaborative efforts. These research endeavors span a broad array of disciplines and are critical to investigating the interplay between biological, geological, and chemical processes in the ocean systems over space and time. The advent of genomic sequencing technologies allows for the analysis of gene expression in a variety of environmental settings, to measure the distribution and significance of metabolites and lipids in organisms and the environment. Despite scientists’ best efforts to carefully curate and share their data with collaborators to advance individual studies and publications, no systematic, unifying framework currently exists to integrate ‘omics data with physical, geochemical, and biological datasets commonly used by the broader geoscience community. As a result, the moment each sample leaves the ship is often the last time each data component appears together in a unified collection. Typically, ‘omics datasets are submitted to nucleotide sequence repositories, whereas contextual environmental data are submitted and stored in specialized data-repositories, or only made available within published papers. This makes it difficult to fully reconnect in-situ data, therefore limiting their reuse in other studies. The development of resources to facilitate the aggregation, publication and reuse of biological datasets along with their physicochemical information is critical for studying marine microbes and the biogeochemical processes in the ocean that they drive. We present Planet Microbe, a cyberinfrastructure resource enabling data discovery and open data sharing for historical and on-going oceanographic sequencing efforts. Several historical oceanographic ‘omics datasets (Hawaii Ocean Time-series (HOT), Bermuda Atlantic Time-series (BATS), Global Ocean Sampling Expedition (GOS)) have been integrated into Planet Microbe along with new oceanic large-scale datasets as the Tara Expeditions and Ocean Sampling Day (OSD). In Planet Microbe, these ’omics data have been reintegrated with their in-situ environmental contextual data, including biological and physicochemical measurements, and information about sampling events, and sampling stations. Finally, cruise tracks, protocols and instrumentation are also linked to these datasets to provide the user with a comprehensive view of the metadata. Additionally, Planet Microbe integrates computational tools using National Science Foundation (NSF) funded Cyberinfrastructure (CyVerse) and provides users with free access to large-scale computing power to analyze and explore these datasets.

The Labrador Sea undergoes deep mixing in the wintertime, with mixed layer depths frequently reaching down to 2000 m. The resulting water mass that is formed - Labrador Sea Water (LSW) - has long been thought to be important for the deep Western Boundary Current (dWBC) and the upper limb of the AMOC. Direct observations of the overturning have, however, been rather limited. Limited Argo profiles and moorings in key locations offered winter measurements in a region challenged by severe weather conditions. Here we discuss observations of a winter-spring glider deployment in the Labrador Sea, but more specifically where deep convection occurs, from December 2019- to June 2020. Using the glider data, we describe the evolution of the mixed layer, changes in heat and freshwater content for surface (0-500 m) and intermediate depth (500-1000 m) layers for the central Labrador Sea convection region inside a box 200 by 100 km wide and spatial scales of T and S. We compare the observations with reanalysis data (air-sea heat fluxes and winds) and Argo profiles to better understand the variability missed by existing datasets. These observations highlight the role played by eddies in the overall variability of heat and salt in this region, something that is missed by Argo observations. They also show changes in spatial scales of T-S over the months from January to May, pointing towards the modulating effect of eddies on LSW winter formation.

Ocean gliders are a key platform that can fill the gaps between coastal and open ocean observing systems, between Argo floats, and moorings and ship-based strategies (Testor et al., 2019). One challenge for these slow-moving, primarily underwater systems, is to improve waypoint-based navigation to minimize the effects of wind and current driven dynamics. This is important in time-critical applications where there are advantages in reaching a site as quickly as possible, for example when monitoring storm systems or tracking eddies. Optimal path planning will also be important in long duration missions where battery consumption is a limiting factor of the deployment. In August 2019, a Slocum glider was deployed in the Gulf of St. Lawrence for preliminary system studies. During the deployment, a waypoint planning system was used to generate the glider waypoints list files. In this presentation, we will present the design of the path-planning system and show in-situ scientific measurements collected by the glider. The key optimized value assigned to enable path planning are minimizing current speeds and the key metric for validating the performance is the distance covered per hour. This approach has tremendous value for improving the autonomy of gliders in operational ocean monitoring applications, removing pressure from pilots managing the glider mission and improving the state-of-the-art of ocean data products.

The ocean plays a critical role in modulating climate change by sequestering CO2 from the atmosphere. Quantifying the CO2 flux across the air-sea interface requires time-dependent maps of surface ocean partial pressure of CO2 (pCO2), which can be estimated using global ocean biogeochemical models (GOBMs) and observational-based data products. GOBMs are internally consistent, mechanistic representations of the ocean circulation and carbon cycle, and have long been the standard for making spatio-temporally resolved estimates of air-sea CO2 fluxes. However, there are concerns about the fidelity of GOBM flux estimates. Observation-based products have the strength of being data-based, but the underlying data are sparse and require significant extrapolation to create global full-coverage flux estimates. The Lamont Doherty Earth Observatory-Hybrid Physics Data (LDEO-HPD) pCO2 product is a new approach to estimating the temporal evolution of surface ocean pCO2 and air-sea CO2 exchange. LDEO-HPD uses machine learning to merge high-quality observations with state-of-the-art GOBMs. We train an eXtreme Gradient Boosting (XGB) algorithm to learn a non-linear relationship between model-data mismatch and observed predictors. GOBM fields are then corrected with the predicted model-data misfit to estimate real-world pCO2 for 1982-2018. A benefit of this approach is that model-data misfit has reduced temporal skewness compared to the observed pCO2 that is the target variable for other machine-learning based reconstructions. This supports a robust reconstruction by LDEO-HPD that is in better agreement with independent observations than other estimates. LDEO-HPD global ocean uptake of CO2 is in agreement with other products and the Global Carbon Budget 2020.

The variability of streams in the atmosphere and the ocean, as shown in a number of studies, affects the change in the speed of the Earth’s rotation. However, it can cause a reverse reaction—a change in the Coriolis force; as a result of this, atmospheric and oceanic streams can have some variability. In the following work, a hypothesis is presented and considered: it suggests that a change in the volume of Atlantic water inflow into the Barents Sea is related to the change in the Earth’s rotation speed. The paper presents a methodology for determining representative values of the temperature and salinity of seawater that describe the largest possible volume of the sea, as well as a methodology for calculating the content of Atlantic, river and melt water for the period of 100 years. The change of these parameters, and the length of day values, demonstrates the presence of both linear trends and cyclical fluctuations with a period of about 80 years. As a result, it was shown that a decrease in the Earth’s rotation speed with a linear trend somewhat decreases the observed intensity of the processes of global climate change in the Arctic region (an increase in temperature and salinity). Due to the summation of positive anomalies, both a linear trend and a quasi-80-year cycle, the modern period is characterized by abnormally high values of water temperature, the growth of which has not stopped and will possibly reach its maximum between 2025 and 2030.

We investigate numerically the elastic interaction between a dipole and an axisymmetrical vortex in inviscid isochoric two-dimensional (2D), as well as in three-dimensional (3D) flows under the quasi-geostrophic (QG) approximation. The dipole is a straight moving Lamb-Chaplygin (L-C) vortex such that the absolute value of either its positive or negative amount of vorticity equals the vorticity of the axisymmetrical vortex. The results for the 2D and 3D cases show that, when the L-C dipole approaches the vortex, their respective potential flows interact, the dipole’s trajectory acquires curvature and the dipole’s vorticity poles separate. In the QG dynamics, the vortices suffer little vertical deformation, being the barotropic effects dominant. At the moment of highest interaction, the negative vorticity pole elongates, simultaneously, the positive vorticity pole evolves towards spherical geometry and the axisymmetrical vortex acquires prolate ellipsoidal geometry in the vertically stretched QG space. Once the L-C dipole moves away from the vortex, its poles close, returning the vortices to their original geometry, and the dipole continues with a straight trajectory but along a direction different from the initial one. The vortices preserve, to a large extent, their amount of vorticity and the resulting interaction may be practically qualified as an elastic interaction. The interaction is sensitive to the initial conditions and, depending on the initial position of the dipole as well as on small changes in the vorticity distribution of the axisymmetrical vortex, inelastic interactions may instead occur.

The thermodynamic growth of sea ice is a critical factor in the mass balance of Arctic sea ice, which has important implications for Arctic communities and the global climate. However, the magnitude by which snow atop Arctic sea ice limits thermodynamic ice growth is still not fully understood. Prior work has shown that the wind-driven snow redistribution could significantly modify the heat conduction through the snow cover and hence the rate of thermodynamic ice growth. However, the effects of snow redistribution on sea ice growth have not been quantified and are not well represented in climate models. We use observations from the MOSAiC expedition to show how different facets of snow redistribution can enhance or reduce heat conduction through the snow cover for the same mean snow thickness. The net effect depends on ice topography and environmental conditions. For example, snow redistribution onto young ice in April at MOSAiC reduced heat conduction by approximately 5-15%. We quantify the impact winter and springtime snow redistribution events on the heat conduction on deformed, level, and young ice. We explore the implications of these snow redistribution processes in the Community Earth System Model and discuss priorities for improving climate models.

We investigate numerically the elastic interaction between an eddy-pair and an axisymmetrical cyclonic eddy in inviscid isochoric two-dimensional (2D), as well as in three-dimensional (3D) flows under the quasi-geostrophic (QG) approximation. The eddy-pair is a straight moving Lamb-Chaplygin dipole where the absolute value of either its positive or negative amount of vorticity equals the vorticity of the axisymmetrical eddy. The results for the 2D and 3D cases show that interactions with almost no vorticity exchange or vorticity loss to the background field between ocean eddies, but changing their displacement velocity, are possible. When the eddy-pair approaches the axisymmetrical eddy, their respective potential flows interact, the eddy-pair’s trajectory acquires curvature and their vorticity poles separate. In the QG dynamics, the eddies suffer little vertical deformation, being the barotropic effects dominant. At the moment of highest interaction, the anticyclonic eddy of the pair elongates, simultaneously, the cyclonic eddy of the pair evolves towards spherical geometry, and the axisymmetrical eddy acquires prolate ellipsoidal geometry in the vertically stretched QG space. Once the eddy-pair moves away from the axisymmetrical eddy, its poles close, returning to their original geometry, and the anticyclonic and cyclonic eddy continue as an eddy-pair with a straight trajectory but along a new direction. The interaction is sensitive to the initial conditions and, depending on the initial position of the eddy-pair, as well as on small changes in the vorticity distribution of the axisymmetrical eddy, inelastic interactions may instead occur.

Seasonal Ice Zone Reconnaissance Surveys (SIZRS) is a multi-investigator program of repeated ocean, ice, and atmospheric measurements. These measurements make use of U.S. Coast Guard flights across the Beaufort-Chukchi Sea seasonal sea ice zone (SIZ), the region between maximum winter ice extent and minimum summer ice extent. The long-term goal of SIZRS is to track and understand the interplay among the ice, atmosphere, and ocean, contributing to the rapid decline in summer ice extent. The fundamental SIZRS approach is to make monthly flights, June to October, with US Coast Guard Air Station Kodiak C-130s across the Beaufort Sea SIZ along 150°W from 72°N to 76°N or ~ 1 degree of latitude north of the ice edge, whichever is farther north. We make oceanography stations every degree of latitude by dropping Aircraft eXpendable CTDs (AXCTDs) and Aircraft eXpendable Current Profilers (AXCPs) typically while traveling northbound (PI: J. Morison). On the return leg, we drop atmospheric dropsondes from 3000 meters altitude to measure atmospheric temperature, humidity, and winds (PI: A. Schweiger). We also drop UpTempO drifting buoys that report time series of ocean temperature profiles (PI: M. Steele) and various meteorology and ice-tracking buoys of the International Arctic Buoy Program (IABP, PI: I. Rigor).