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).

It is generally agreed that the resolution of a regular quadrilateral mesh is the side length of quadrilateral cells. There is less agreement on what is the resolution of triangular meshes, exacerbated by the fact that the numbers of edges or cells on triangular meshes are approximately three or two times larger than that of vertices. However, the geometrical resolution of triangular meshes, i.e. maximum wavenumbers that can be represented on such meshes, is a well defined quantity, known from solid state physics. These wavenumbers are related to a smallest common mesh cell (primitive unit cell), and the set of mesh translations that map it into itself. The wavenumbers do not depend on whether discrete degrees of freedom are placed on vertices, cells or edges. The resolution is defined by the height of triangles.

Preservation of organic carbon (OC) in marine and terrestrial deposits is enhanced by bonding with reactive iron (FeR) phases. The association of OC with FeR (OC-FeR) provides physical protection and hinders microbiological degradation. Roughly 20% of all OC stored in unconsolidated marine sediments and 40% of all OC present in Quaternary terrestrial deposits is preserved as OC-FeR, but this value varies from 10 to 80% across depositional environments. In this work, we provide a new assessment of global OC-FeR burial rates in both marine and terrestrial environments, using published estimates of the fraction of OC associated with FeR, carbon burial, and probabilistic modelling. We estimate the marine OC-FeR sink at between 31 – 70 Mt C yr-1 (mean 52 Mt C yr-1), and the terrestrial OC-FeR sink at between 171 - 946 Mt C yr-1 (mean 472 Mt C yr-1). In marine environments, continental shelves (mean 17 Mt C yr-1) and deltaic/estuarine environments (mean 11 Mg C yr-1) are the primary locations of OC-FeR burial. On land, croplands (279 Mt C yr-1) and grasslands (121 Mt C yr-1) dominate the OC-FeR burial budget. Changes in the Earth system through geological time likely alter the OC-FeR pools, particularly in marine locations. For example, periods of intense explosive volcanism may lead to increased net OC-FeR burial in marine sediments. Our work highlights the importance of OC-FeR in marine carbon burial and demonstrates how OC-FeR burial rates may be an order of magnitude greater in terrestrial environments, those potentially most sensitive to anthropogenic impacts.

Ocean circulation is dominated by turbulent geostrophic eddy fields with typical scales ranging from 10 km to 300 km. At mesoscales (> 50 km), the size of eddy structures varies regionally following the Rossby radius of deformation. The variability of the scale of smaller eddies is not well known due to the limitations in existing numerical simulations and satellite capability. But it is well established that oceanic flows (< 50km) generally exhibit strong seasonality. In this study, we present a basin-scale analysis of coherent structures down to 10\,km in the North Atlantic Ocean using two submesoscale-permitting ocean models, a NEMO-based North Atlantic simulation with a horizontal resolution of 1/60 (NATL60) and an HYCOM-based Atlantic simulation with a horizontal resolution of 1/50 (HYCOM50). We investigate the spatial and temporal variability of the scale of eddy structures with a particular focus on eddies with scales of 10 to 100\,km, and examine the impact of the seasonality of submesoscale energy on the seasonality and distribution of coherent structures in the North Atlantic. Our results show an overall good agreement between the two models in terms of surface wavenumber spectra and seasonal variability. The key findings of the paper are that (i) the mean size of ocean eddies show strong seasonality; (ii) this seasonality is associated with an increased population of submesoscale eddies (10\,–\,50\,km) in winter; and (iii) the net release of available potential energy associated with mixed layer instability is responsible for the emergence of the increased population of submesoscale eddies in wintertime.

The western tropical Pacific (WTP) exhibits large interannual sea level anomalies (SLAs), and the sea level falling in El Niño is evidently stronger than the rising in La Niña. The asymmetry is most prominent near 160°E with the response to El Niño larger by three times and becomes less obvious near the western boundary. Sensitivity experiments of a simplified ocean model suggest that the asymmetry in surface wind forcing structure between El Niño and La Niña is critical. The El Niño’s westerly wind anomaly patch locates more east than the La Niña’s easterly wind patch during the mature stage, and its upwelling effects are accumulated over a wider longitude range and cause stronger negative SLAs in the WTP. Near the western boundary, however, upwelling effects are attenuated by easterly wind anomalies during El Niño conditions. The asymmetric ocean responses to ENSO winds may participate in the asymmetry of ENSO cycle.

The traditional ocean color remote sensing usually focuses on using optical inversion models to estimate the properties of in-water components from the above-surface spectra, so we call it the spectrum-concentration (SC) scheme. Unlike the SC scheme, this study proposed a new research scheme, distribution-distribution (DD) scheme, which uses statistical inference models to estimate the possibility distribution of these in-water components, based on the possibility distribution of the observed spectra. The DD scheme has the advantages that (1) it can rapidly give the key and overview information of the interest water, instead of using the SC scheme to compute each image pixel, (2) it can assist the SC scheme to improve their models and parameters, and (3) it can provide more valuable information for better understanding and indicating the features and dynamics of aquatic environment. In this study, based on Landsat-8 images, we analyzed the spectral possibility distributions (SPD) of 688 global water and found many of them were normal, lognormal, and exponential distributions, but with diverse patterns in distribution parameters such as the mean, standard deviation, skewness and kurtosis. Furthermore, we used Monte-Carlo and Hydrolight simulations to study the theoretical and statistical connections between the possibility distributions of in-water components and SPDs. The simulation results were basically consistent with the observations on the real water. Then by using the simulation and field measured data, we proposed a bootstrap-based DD scheme and developed some simple statistical inference models to estimate the distribution parameters of yellow substance in lakes. Since DD scheme is still on its early stage, we also suggested some potential and useful topics for the future work.

One third of all coastlines worldwide consist of permafrost. Many of these permafrost coasts are presently exposed to greater environmental forcing as a consequence of climate change, such as a lengthening of the open water season, intensified storms, and higher water and air temperatures. As a result, increasing erosion rates are currently reported from various sites across the Arctic. It is crucial to synthetize these data on Arctic shoreline dynamics in order to improve our understanding on present coastal dynamics on the pan-Arctic scale. A first synthesis product was released in form of the Arctic Coastal Dynamics databse in 2012, which included data published until 2009 (Lantuit et al., 2012). Since then, numerous publications and data products were published on short and long term changes of Arctic coasts across a wide range of study sites. We made an extensive literature review of publications released within the last 10 years and updated the shoreline change data section in the Arctic Coastal Dynamics database. While in 2009 for one percent of the Arctic shoreline data on coastal dynamics was available, the addition of new data leads to a broader data coverage, which is mainly the effect of the greater availability of remotely sensed products for analyses conducted in these remote regions. Further, the additional data allow us to update the current mean rate of Arctic shoreline change.

Some of the Earth system data products such as those from NASA airborne and field investigations (a.k.a. campaigns), are highly heterogeneous and cross-disciplinary, making the data extremely challenging to manage. For example, airborne and field campaign measurements tend to be sporadic over a period of time, with large gaps. Data products generated are of various processing levels and utilized for a wide range of inter- and cross-disciplinary research and applications. Data and derived products have been historically stored in a variety of domain-specific standard (and some non-standard) formats and in various locations such as NASA Distributed Active Archive Centers (DAACs), NASA airborne science facilities, field archives, or even individual scientists’ computer hard drives. As a result, airborne and field campaign data products have often been managed and represented differently, making it onerous for data users to find, access, and utilize campaign data. Some difficulties in discovering and accessing the campaign data originate from the incomplete data product and contextual metadata that may contain details relevant to the campaign (e.g. campaign acronym and instrument deployment locations), but tend to lack other significant information needed to understand conditions surrounding the data. Such details can be burdensome to locate after the conclusion of a campaign. Utilizing consistent terminology, essential for improved discovery and reuse, is also challenging due to the variety of involved disciplines. To help address the aforementioned challenges faced by many repositories and data managers handling airborne and field data, this presentation will describe stewardship practices developed by the Airborne Data Management Group (ADMG) within the Interagency Implementation and Advanced Concepts Team (IMPACT) under the NASA’s Earth Science Data systems (ESDS) Program.

Mangrove forests with complex root systems contribute to increased coastal protection through drag effects. Previous flume studies proposed a predictive model of drag in Rhizophora mangrove forests based on quadratic drag law. However, its general applicability on mangrove forests in the field has not been tested. To fill this knowledge gap, this study quantified drag in a 17-year-old planted Rhizophora mangrove forest using a comprehensive measurement of hydrodynamics and vegetation morphology. The vegetation projected area density, a, showed an approximate exponential increase towards the bed, mainly due to root branching. This vertical variation led to enhanced vegetation drag per unit water volume relative to velocity with decreasing water depth. Alternatively, the drag per vegetation projected area solely depended on the square of velocity, indicating association with the quadratic drag law. The derived drag coefficient (CD) was 1.0 ± 0.2 for tide-driven currents, consistent with previous flume studies. By using the mean value of derived CD (1.0), it was confirmed that the quadratic drag model expresses well the field-measured drag. We also presented a method for predicting a value for a, another unknown parameter in the drag model, using an empirical Rhizophora root model, and confirmed a successful prediction of a and drag. Therefore, the drag in a Rhizophora mangrove forest can be accurately predicted only using the input parameters of the Rhizophora root model – stem diameter and tree density. This provides insights into effectively implementing the drag model in hydrodynamic models for better representation of mangroves’ coastal protection function.

Time series of shipboard observations in the southern Arafura Sea near the Tiwi Islands indicated that the water column dynamics differed between the east and west sides of the islands. On the west side, the water column, characterized by temperature, salinity, and velocity, was barotropic and tidal advection dominated. On the east side, the water column was baroclinic and internal tides were present along with tidal advection. These conditions affected the distribution of the turbidity and fluorescence in the water column. Likewise, the influence of the daily solar radiation cycle reached the bottom on the western side, but was limited to the upper layer above the thermocline on the eastern side. The fluorescence peaks also differed between the east and west sides, with the eastern side dominated by the semidiurnal tides and the western side by the daily solar cycle. Fluorescence integrated over the water column was much higher on the eastern side than the western side. Also on the eastern side, fluorescence was limited to the lower layer, while on the western side, it encompassed the entire water column at times and peaked below the warmer, higher oxygenated water generated by solar radiation and surface mixing. These dynamics have distinct implications for biological productivity and also may affect a proposed tidal power system in the region.

This study investigates trends in global tropical cyclone (TC) activity from 1990–2020, a period where observational platforms are mostly consistent. Several global TC metrics have decreased during this period, with significant decreases in hurricanes and Accumulated Cyclone Energy (ACE). Most of this decrease has been driven by significant downward trends in the western North Pacific. Globally, short-lived named storms, 24-hr intensification periods of >=50 kt day-1 and TC-related damage have increased significantly. The increase in short-lived named storms is likely due to technological improvements, while rapidly intensifying TC increases may be fueled by higher potential intensity. Damage increases are largely due to increased coastal assets. The decreasing trends in hurricane numbers and global ACE are likely due to the trend towards a more La Niña-like base state from 1990–2020, favoring TC activity in the North Atlantic and suppressing TC activity in the eastern and western North Pacific.

Eastern Boundary Currents Systems are typically studied as a whole due to their dynamical similarities, mainly because Ekman pumping is predominant at these currents, and they typically have low kinetic energy. In this study, we used the output of a high-resolution global simulation to make a dynamical comparison among the California, Canary, Peru, and Benguela currents during the winter and summer months, focusing on submesoscale motions (Ro ~ 1) in both the frequency-wavenumber and space-time domains. After we confirmed the presence of submesoscale activity and isolated it from mesoscale motions, we found that their divergence and vorticity fields follow similar seasonal patterns in the near-diurnal frequency range, despite regional differences. The results showed that heat fluxes at the ocean surface, along with weak to moderate wind stresses, significantly impact the modulation of submesoscale vorticity and divergence fields at diurnal frequencies.

Understanding and predicting sea ice dynamics and ice-ocean feedback processes requires accurate descriptions of momentum fluxes across the ice-ocean interface. In this study, we present observations from an array of moorings in the Beaufort Sea. Using a force-balance approach, we determine ice-ocean drag coefficient values over an annual cycle and a range of ice conditions. Statistics from high resolution ice draft measurements are used to calculate expected drag coefficient values from morphology-based parameterization schemes. With both approaches, drag coefficient values ranged from approximately 1-10×10^-3, with a minimum in fall and a maximum at the end of spring, consistent with previous observations. The parameterizations do a reasonable job of predicting the observed drag values if the under ice geometry is known, and reveal that keel drag is the primary contributor to the total ice-ocean drag coefficient. When translations of bulk model outputs to ice geometry are included in the parameterizations, they overpredict drag on floe edges, leading to the inverted seasonal cycle seen in prior models. Using these results to investigate the efficiency of total momentum flux across the atmosphere-ice-ocean interface suggests an inter-annual trend of increasing coupling between the atmosphere and the ocean.

The Reykjanes Ridge is a major topographic feature that lies south of Iceland in the North- Atlantic Ocean and strongly influences the Subpolar Gyre (SPG) circulation. Based on velocity and hydrographic measurements carried out along the crest of the Ridge from the Icelandic continental shelf to 50°N during the RREX cruise in June-July 2015, we derived the first direct estimates of volume and water masses transports over the Ridge. The circulation was mainly westward north of 53.35°N and eastward south of it. The westward transport was estimated at 21.9 ± 2.5 Sv (Sv = 10 6 m 3 s -1 ) and represents the SPG intensity. The westward flows followed two main pathways at 57°N near Bight Fracture Zone and at 59 – 62°N. We argue that those pathways were respectively connected to the northern branch of the North Atlantic Current and to the Sub-Arctic Front that were intersected by the southern part of the section. In addition to this horizontal circulation, mixing and bathymetry shaped the water mass distribution. Water mass transformations in the Iceland Basin lead to the formation of weakly stratified SubPolar Mode Water (SPMW). We explain why SPMW, which was the main contributor in terms of water mass to the westward flow, was denser at 57°N than at 59–62°N along the Ridge. At higher densities, both Intermediate Water, defined by a dissolved oxygen minimum, and Icelandic Slope Water contributed as much to the westward transport across the Ridge as the sum of Labrador Sea Water and Iceland-Scotland Overflow Water.

High performance liquid chromatography (HPLC) remains one of the most widely applied methods currently available for estimation of phytoplankton taxonomy from ocean samples. This method measures the concentrations of phytoplankton pigments, some of which are useful chemotaxonomic markers that can be used to diagnose the relative abundance of phytoplankton groups. Here, we use HPLC phytoplankton pigment concentrations measured on surface water samples from 38 field surveys for a total of over 3,000 distinct samples that cover every major ocean basin and represent a wide range of ecological regimes. The data compilation has been quality controlled to remove measurements below pigment detection limits and outliers from the linear regression of total chlorophyll-a concentration with total accessory pigment concentrations and only samples from labs that have participated in round-robin quality assurance experiments (e.g. NASA SeaHARRE) have been included. We assess the environmental and spatial drivers controlling the global distribution and co-variability of individual phytoplankton pigments. Preliminary results of hierarchical clustering show strong differentiation in phytoplankton pigments following known relationships between phytoplankton size class and relative pigment concentration, partitioning their contributions by micro-, nano-, and pico-phytoplankton size classes. However, the exact clusters relationships change when the data are divided by ocean basin or latitude. We also use statistical techniques, including EOFs and network-based exploration, to examine the associations between groups of pigments over a range of environmental conditions on local to global scales and diagnose the main controls on these associations.

Natural methane gas release from the seafloor is a widespread phenomenon that occurs at cold seeps along most continental margins. Since their discovery in the early 1980s, seeps have been the focus of intensive research, partly aimed to refine the global carbon budget. However, deep-sea research is challenging and expensive and, to date, few works have successfully monitored the variability of methane gas release over long time periods (> 1 yr). Long-term monitoring is necessary to study the mechanisms that control seabed gas release. The M³ project, funded by the German Ministry of Education and Research, aims to study the temporal and spatial variability of gas emissions at the Southern Hydrate Ridge (SHR) by acoustically monitoring and quantifying gas effluxes over several years. Located 850 m deep on the Cascadia accretionary prism offshore Oregon, the SHR is one of the most studied seep sites and persistent but variable gas release has been observed for more than 20 years. Since 2015, the Ocean Observatories Initiative’s (OOI) Cabled Array observatory, provides power supply and two-way communication to the SHR, making it an ideal site for continuous long-term monitoring work. In this work, we present how we will take advantage of the OOI infrastructure and deploy several instruments on the seabed for at least 1.5 year. A multi-beam “overview” sonar mounted on a rotor will identify every gas bubble stream located within 200 m from the sonar location. A scanning “quantification” sonar will be used to estimate the amount of gas that is released from discrete gas streams. A camera system and a CTD probe will help process and analyze the hydro-acoustic data. All instruments will be powered and controlled from land through the OOI infrastructure. We present the instrument design, the operation protocol, as well as the data processing steps and expected results.