Unexploded ordnance (UXO) resulting from past military activity are present in coastal settings. Mobility of UXO, specifically in the inner surf and swash zones, constitutes a potential risk for the public. Mobility or exposure may increase under energetic events due to enhanced forcing or sediment erosion. Yet, the conditions leading to exposure, burial, or movement of UXO remain poorly understood. A large-scale laboratory wave flume (120 m x 5 m x 5 m) study at the Institut national de la recherche scientifique (INRS) in Quebec City, Canada was carried out from July 7 to September 23, 2022 to quantify surrogate UXO mobility and burial. An undistorted, scaled beach profile from Mantoloking, NJ, USA was constructed using 0.28 mm diameter sand. Eighteen stations were established at roughly 5 m intervals to collect hydrodynamic, sediment process, and morphology data and to quantify surrogate UXO behavior. Over 150 surrogates of varying bulk density were distributed throughout the flume. Waves were forced in 300-wave packets for each trial of a condition case. Cases used different wave heights, water levels, and wave periods. Preliminary results indicate berm erosion with increasing hydrodynamic energy. The dune only experienced erosion at the highest water levels. Surrogate UXO generally remained in place and buried partially or migrated offshore. Migration tendency and distance was a function of the surrogate density.

How to cite: Puleo, J. A., Idowu, T., Gangadharan, M., and Chapman, E.: Mobility and Burial of Munition Surrogates in the Inner Surf and Swash Zones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-117, https://doi.org/10.5194/egusphere-egu23-117, 2023.

How to cite: Aijaz, S., Brassington, G., Divakaran, P., Régnier, C., Drévillon, M., Maksymczuk, J., and Peterson, K. A.: Verification and Intercomparison of Global Ocean Eulerian Currents, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2350, https://doi.org/10.5194/egusphere-egu23-2350, 2023.

Ocean geochemical tracers such as radiocarbon, protactinium and thorium isotopes, and noble gases are widely used to constrain a range of physical and biogeochemical processes in both the present-day and past ocean. However their routine simulation in global ocean circulation and climate models is hindered by the computational expense of integrating them to a steady state. Here, a new approach to this long-standing ``spin-up'' problem is introduced to efficiently compute equilibrium distributions of such tracers in seasonally-forced models. Based on ``Anderson Acceleration'', a sequence acceleration technique developed in the 1960s to solve nonlinear integral equations, the new method is entirely ``black box'' and offers significant speed-up over conventional direct time integration. Moreover, it requires no preconditioning, ensures tracer conservation and is fully consistent with the numerical time-stepping scheme of the underlying model. It thus circumvents some of the drawbacks of other schemes such as matrix-free Newton Krylov that have been proposed to address this problem. An implementation specifically tailored for the batch HPC systems on which ocean and climate models are typically run is described, and the method illustrated by applying it to a variety of geochemical tracer problems. The new method, which provides speed-ups by over an order of magnitude, should make simulations of such tracers more feasible and enable their inclusion in climate change assessments such as IPCC.

How to cite: Khatiwala, S.: Fast spin-up of geochemical tracers in ocean circulation and climate models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4930, https://doi.org/10.5194/egusphere-egu23-4930, 2023.

A relatively high spatial resolution is often desirable when capturing the spatial variability of evolving wave fields. Some of these situations where a high spatial resolution is needed may be, for example, studing the shape evolution of breaking waves, or studing the directional distribution of the energy of wind-wave spectra, where computing the frequency-wavenumber spectra is critically needed. In both cases, an ideal space-time representation of the wave field is the one whose spatial and time resolutions are high enough (∆x and ∆t being very small), or to some extend, comparable in relative terms (∆x/λ ≈ ∆t/T), i.e., ∆x and ∆t representing a tiny fraction of the characteristic wavelength (λ) and period (T), respectively. In this case, the wave field in the space-time domain looks like a continuous 2D function. However, reaching such high spatial resolutions is not very common in experimental or field works. In some cases, such high resolution is not needed. In some other cases, such high resolution is not possible due to unavoidable experimental, technical and cost constraints, and that results in a limited number of available instruments. To overcome this limitation, we present a relatively simple procedure called S-interp, which is freely available at https://github.com/EMPadilla/Sinterp.
 
S-interp is to interpolate wave fields at spatial locations where no measurements are available. S-interp uses a Modified Akima cubic Hermite interpolation along points in the wave field that are in phase. The main hypothesis of S-interp is that the wave field follows a linear-like evolution along points being at the same phase. Therefore, along these points, differences between the interpolated and the actual wave fields are minimal. Some factors for these differences to rise are: (i) The spatial distribution of the instruments, (ii) the nonlinear effects that modify the wave geometry increasing its asymmetry and skewness and (iii) the interpolation method used. 

We assess the performance of S-interp by reconstructing missing areas of experimental non-breaking wave conditions, gathered in SIREN-NB data set. These are 33 non-breaking focused wave events designed using a NewWave-type spectra for peak periods ranging from 1.0 s to 1.7 s with a peak enhancement factor set to 2. The wave conditions are recorded by video cameras and the wave fields are measured by video-image detection. The experiments were conducted in the Wind-Wave-Current flume at the Hydrodynamics Lab - Imperial College London. Preliminary results suggest that S-interp seems to be more sensitive to the spacing between the instruments than to the nonlinear effects of the wave fields.

How to cite: Padilla, E. M., Cao, R., and Callaghan, A. H.: Increasing the spatial resolution of wave fields when the amount of available instruments is limited, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7078, https://doi.org/10.5194/egusphere-egu23-7078, 2023.

We have developed autonomous, Lagrangian floats that make seismo-acoustic measurements in the oceans, with mission durations of 4+ years and running (http://earthscopeoceans.org). Earthquakes generate seismic waves that traverse the solid earth, convert to acoustic waves when they hit the seafloor from below, and are recorded by the hydrophone on our “Mermaid” floats drifting at ~1500m depth.

In the long-term, we aim for dense and even global coverage of the oceans for seismology, following the model of oceanography’s Argo initiative, or of internationally federated seismometer networks on land. In order to grow the network, we are exploring synergies with oceanography and the marine environmental sciences.

We present technical developments towards the first multidisciplinary mission in 2024 in the Mediterranean, whose floats will run embedded applications in two frequency ranges: the seismic (~0.1-5 Hz) as well as the “conventional” ocean acoustics range (10 Hz to 30 kHz). It will feature detection and classification algorithms for earthquakes, rainfall, marine mammal vocalizations, and ship noise. While energy-limited, these seismological floats carry significantly larger batteries than Argo floats and allow for up to eight physical/chemical/other sensors and their analysis algorithms, whose concurrent needs are managed by a domain-specific language written for the purpose (Bonnieux 2020).

Reference: Bonnieux, S. (2020). Float for multidisciplinary monitoring of the marine environment. From business expertise to embedded codes (Doctoral dissertation, Université Côte d'Azur).

How to cite: Sigloch, K., Bonnieux, S., and Hello, Y.: Multidisciplinary, autonomous, Lagrangian floats for seismology, ocean acoustics and marine environmental science, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8362, https://doi.org/10.5194/egusphere-egu23-8362, 2023.

The spatio-temporal variability of the surface ocean CO₂ system and the air-sea CO₂ fluxes were studied in the Northeast Atlantic and the Strait of Gibraltar, including the northwest African coastal transitional region and the easternmost archipelagic waters of the Canary Islands. The surface underway high-frequency data was collected by a surface ocean observation platform (SOOP) aboard a volunteer observing ship (VOS). The variability of the CO₂ fugacity in seawater (fCO_2,sw) was strongly driven by the seasonal pattern of the sea surface temperature (SST), which increased with latitude and was lower throughout the year in the high-intense African coastal upwelling. In the Strait of Gibraltar, the changes in the depth of the Atlantic-Mediterranean Interface layer and the tidal and wind-induced upwelling influenced the surface CO₂ distribution. The variability of the CO₂ fugacity (fCO_2,sw) in this high-variable semi-enclosed area was mainly driven by temperature despite the significant influence of non-thermal processes in the southernmost part. The fCO_2,sw increased from winter to summer by 11.84 ± 0.28 µatm ºC^-1 in the Canary archipelago and by 11.71 ± 0.25 µatm ºC^-1 along the northwest African continental shelf. In the Strait of Gibraltar, the gradient was lower and showed differences between the northern and southern sections (9.02 ± 1.99 and 4.51 ± 1.66 µatm ºC-1, respectively). The annual cycle (referenced to 2019) of total inorganic carbon normalized to a constant salinity of 36.7 (NC_T) indicated that the net community production in the Northeast Atlantic represented >90% of the reduction of inorganic carbon while air-sea CO₂ exchange described <6%. The net community production processes in the Strait of Gibraltar described 93.5-95.6% of the total NC_T change, while the contribution of air-sea exchange and horizontal and vertical advection was found to be minimal (<4.6%). According to the seasonality of air-sea CO₂ fluxes, the entire region behaved as a strong CO₂ sink during the cold months and as a weak CO₂ source during the warm months. A net annual CO₂ sink behaviour was observed in the Canary basin (-0.26 mol C m^-2 yr^-1), in the northwest African coastal transitional area (-0.48 mol C m^-2 yr^-1) and in both the northern and southern section of the Strait of Gibraltar (-0.82 and -1.01 mol C m^-2 yr^-1). The calculated average air-sea CO₂ flux for the area of study in Northeast Atlantic and in the Strait of Gibraltar was, -2.65 ± 0.44 TgCO₂ yr^-1 (-0.72 ± 0.12 TgC yr^-1) and -7.12 Gg CO₂ yr^-1 (-1.94 Gg C yr^-1), respectively.

How to cite: Gonzalez-Davila, M., Curbelo-Hernández, D., Santana-Casiano, J. M., González-González, A., and González-Santana, D.: Volunteer Observing Ships in transitional oceanic regions: the Northeast African upwelling and the Strait of Gibraltar, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11734, https://doi.org/10.5194/egusphere-egu23-11734, 2023.

During the XXXVIII Italian Expedition in Antarctica, in the framework of the PNRA RESTORE (Robotic-based invESTigation and mOnitoring Ross sEa) project the PROTEUS (Portable RObotic TEchnology for Underwater Surveys) unmanned marine vehicle (UMV) was used for carrying out an integrated 3D mapping of a portion of the Tethys Bay in the Ross Sea. PROTEUS is an innovative UMV developed by the Marine Robotics research group of CNR-INM which is particularly suitable, with its reduced size and weight, modularity, reconfigurability, and open hardware and software architectures, to operate in extreme environments as the polar ones. For performing the survey seven holes were drilled in the ice pack from which it was possible to deploy the robot in the water. Thanks to the versatility of PROTEUS, it was possible to acquire a comprehensive collection of bio-geo-chemical and physical parameters of the water column (acoustic, conductivity/salinity, temperature, depth, dissolved oxygen, turbidity and chlorophyll), acoustic and video data of the ice and the seabed. All the collected data, once processed, will be made available to the scientific community by means of FAIR (Findable, Accessible, Interoperable and Reusable data) techniques following the UN Ocean Science Decade directives.

How to cite: Bruzzone, G., Aracri, S., Bibuli, M., Bruzzone, G., Caccia, M., Ferretti, R., Giacopelli, M., Ivaldi, R., Motta, C., Odetti, A., Spirandelli, E., and Zereik, E.: Multi-sensor 3D mapping of Tethys Bay (Ross Sea – Antarctica) with PROTEUS, an innovative, highly reconfigurable and versatile unmanned marine vehicle, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12041, https://doi.org/10.5194/egusphere-egu23-12041, 2023.

Interactions across an air-sea interface are fundamental features of Earth’s climate system with substantial implications for ecosystems. Diurnal variations of local exchange between atmosphere and ocean impacts both environments and rectifies into longer and larger scale through interactions with mesoscale circulation. Therefore, such local processes can influence evolution of weather patterns. At the same time, atmosphere and ocean models struggle with the realistic representation of diurnal variations across an air-sea interface. It is related to gaps in our understating of physical mechanisms behind these interactions which stems from a fact that collocated, reliable measurements within coupled atmosphere and ocean environment, spanning across an air-sea interface are rare.

Emergence of the Uncrewed Aircraft Systems (UAS) enables a new opportunity for sampling across air-sea interface. A multirotor UAS equipped with atmosphere and/or ocean measurement capability can be launch from a vessel (e.g. research vessel) and perform measurements in its vicinity, but in flow not obstructed by ship’s structure. In this presentation, observations collected over ocean tropical and subtropical Atlantic, as well as in the coastal zone will be presented. Profiles were collected in both oceanic (temperature profile, top 5m of the ocean) and atmospheric (temperature and humidity, surface to 500m). Therefore, measurements were conducted in the area not only obstructed by vessel’s sole presence but also unreachable by remote sensing techniques. Results demonstrate capability of ocean and atmosphere sensing UAS to measure coupled variability across an air-sea interface.

How to cite: Baranowski, D.: Uncrewed Aircraft Systems (UAS) for in-situ measurements across an air-sea interface, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12700, https://doi.org/10.5194/egusphere-egu23-12700, 2023.

Due to climate change, the Arctic environment has rapidly evolved in the last decades. Glaciers are melting at unprecedented rates, sea ice is forming later and melting earlier in the season, multiyear sea ice is being replaced by yearly sea ice, and the freshwater content in the ocean has increased. All this has impacts other large-scale, ocean-climate-related phenomena such as the water mass (trans)formation, ocean currents, and salinity fronts. The natural variability of the Arctic system itself has been reported to be bound to change. Apart from that, Arctic ecosystems are also expected to respond to evolving environmental conditions.

Besides the importance of these changes at a regional and global scale, long-term and continuous environmental observations are still scarce both in time and space. Hard accessibility of Arctic regions, makes observational initiatives logistically difficult, time-consuming, and costly. In addition to providing environmental information, near-real-time and long lasting observing systems are key for supporting data to local communities, mariners and also for model assimilation and verification in the context of operational forecast systems.

With the advent of new technologies, low-cost solutions for continuous and long-term coastal observations are possible. In this work, we introduce two systems. Firstly, a near-real-time observing system for sea ice and oceanographic conditions deployed in Northeast Greenland in the framework of the Greenland Integrated Observing System (GIOS.org). These systems are composed of mobile observatories powered by sun and wind allowing the near-real-time measurements of atmospheric, terrestrial and oceanographic drivers of the coastal ocean. The system measures several sea ice (e.g., sea ice thickness, images) and oceanographic (e.g., salinity, temperature, and currents) parameters. In practical terms, oceanographic sensors deployed for 2 years on underwater moorings collect data and transmit it via an inductive link to in-land containerized unities and transmit near-real-time data over satellite. Secondly, we present low-cost IoT (Internet of Things) units that enable transmission of a limited set of parameters via satellite from sensors dispersed in the landscape. For both systems, the data, once transmitted, enters a customized data processing system which allows displaying the post-processed environmental conditions in near-real-time via an open online dashboard. To conclude, this work will introduces new analysis methods and preliminary results based on real time data from the field on sea ice formation and melting and how these are directly influenced by oceanographic and atmospheric conditions.

How to cite: Boone, W., Ponsoni, L., Johnen, G., and Rysgaard, S.: New technologies and insights from a real-time monitoring system of sea ice and oceanographic conditions in Northeast Greenland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14430, https://doi.org/10.5194/egusphere-egu23-14430, 2023.

Aquatic research is often recognized as the last real adventure with dedicated scientists sailing on famous research vessels to even remotest areas like the Arctic or Antarctica taking samples with highly sophisticated scientific equipment. Such cruises or even more, scientists in submarines or ROVs are eye-catchers and get a high level of attention in the scientific, public and political community. In contrast, there is a comparatively small group of scientists which indeed physically enter the aquatic ecosystem and do science there - the group of diving scientists.  

Most surprisingly, this small group of scientists is sometimes not well recognized in science. Very often, scientific divers are assumed to take up their hobby and have mainly fun under water instead of doing serious scientific work. We - the scientific diver community - are often confronted with statements like “oh, you can be outside and can dive the whole day long, I have to stand the entire day in the lab. Your work must be like holydays”. Most of these colleagues have never been out the entire day in a bulky drysuit, spending hours and hours on a small boat while the colleague is under water doing fine tuned work in the three-dimensional space having the air to survive in tanks on the back. Often these colleagues have never spend 6 or more hours outside in a steady swell or with outside temperatures below 0°C of above 30°C and 100% humidity - without a private toilet - on a 6 m long RIB-boat.

In this talk, we present the well harmonized European standards for doing excellent science under water, the respective European and German national bodies for scientific diving, as well as the required and recommended occupational safety standards and procedures for a successful, safe and efficient scientific work under water. In contrast, we also stress some possible reasons why doing science under water as diving scientist is, most  surprisingly, much less accepted and established in science as doing aquatic science from “outside”, e.g. from a ship floating at the surface.

How to cite: Fischer, P., Brand, M., Comeau, S., Schmid, M., and Schwanitz, M.: Aquatic scientists under water - it’s much more than just fun, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15505, https://doi.org/10.5194/egusphere-egu23-15505, 2023.

NorSOOP (Norwegian Ships of Opportunity Program) is a national research infrastructure which began in 2018 and is financed by the Research Council of Norway. Its main goal is to build a network of ships of opportunity capable of providing marine and atmospheric observations that are relevant for improving our understanding of coastal and oceanic ecosystems and also covers a subset of the Global Ocean Observing System (GOOS) essential ocean variables. NorSOOP ships of opportunity are part of the European GOOS (EuroGOOS) FerryBox Task Team and have contributed to various projects focused on marine ecosystem change, carbon dioxide/ocean acidification, pollution/microplastics, and remote sensing – at the local/municipality, national, and European level (including Horizon 2020 JERICO-S3, NAUTILOS, MINKE, and EuroSea projects). The objectives of NorSOOP include: (1) upgrade existing FerryBox installations and establish new ships of opportunity in Norwegian waters and the Arctic and North Atlantic; (2) provide and support high-quality and cost-efficient basic and applied ocean and atmosphere research; (3) foster innovation and growth for maritime, environmental sensor, and aquaculture industries. This talk will provide the latest developments, installations, and results as well as updates of the past and future activities within the project.

How to cite: King, A., Jaccard, P., Frigstad, H., Harvey, T., Sørensen, K., Wehde, H., Eastwood, S., and Sagerup, K.: Norwegian Ships of Opportunity Program for marine and atmospheric research, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16706, https://doi.org/10.5194/egusphere-egu23-16706, 2023.

We deployed a propulsion system-aided Slocum G3 glider in a high current environment off the Florida shelf fitted with an Acoustic Doppler Current Profiler (ADCP), a Conductivity-Temperature-Depth (CTD) sensor, and optics channel sensors to obtain measurements of current velocities, salinity, temperature, pressure, dissolved organic matter (DOM), chlorophyll, and backscatter. We also used a Wirewalker, a wave-powered profiling platform, fitted with both an ADCP and a CTD to obtain measurements at a 120-m isobath nearby off the Florida shelf. CTD measurements, glider coordinates, and aligned temporal windows of relevant profiles were used to validate velocity comparisons between both ADCPs. Different processing procedures were also used to motion-correct velocity measurements from both devices. Glider optics channels were used to evaluate changes through time in particle distributions associated with the meandering of the currents. Wirewalker velocity measurements qualitatively coincided with the glider’s ADCP overall, albeit not perfectly quantitatively. However, this coherence was partly dependent on whether the platform’s upcasts or downcasts were compared, as well as distance from the glider. Both ADCPs’ velocity measurements show clear evidence of a southward-flowing intermittent undercurrent jet previously reported by Soloviev et al. (2017). This undercurrent’s effects are also seen through the glider’s optics channels, with influence in DOM and chlorophyll distributions. Changes in backscatter were seen to a much lesser degree and probably influenced by the diel vertical migration (DVM) of zooplankton. The volume transport by the southward flow is relatively small compared to the Florida Current’s transport. Nevertheless, the processes that maintain and account for the variability of the southward flow are important for a number of practical applications including the propagation of pollution and genetic information against the Florida Current.

How to cite: Quezada, A., Soloviev, A., Kluge, J., Morrison, G., Thompson, T., and Ettinger, B.: Coastal Circulation in a Western Boundary Current Using Gliders and a Wirewalker, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16975, https://doi.org/10.5194/egusphere-egu23-16975, 2023.