Polynyas, persistent areas of open water within sea ice, are critical features of polar marine systems, facilitating ocean-atmosphere heat exchange, deep water formation, nutrient cycling, and biological productivity. However, current remote sensing approaches typically delineate polynyas using either sea ice concentration thresholds or thin sea ice thickness retrievals. While these methods have proven highly valuable, they ca...

Floating debris transport in marginal seas is controlled by a combination of geostrophic currents, wind-driven currents, wave-induced drift, and direct wind forcing, but the relative importance of these processes remains difficult to quantify without in-situ trajectory observations. This study evaluates near-surface forcing combinations for particle tracking in the East/Japan Sea using 33 GPS-tracked surface drifters deployed...

Global warming has been identified as the primary cause of the decline of surface chlorophyll a (Chl a) concentrations in the oceans. Conversely, increasing Chl a concentrations have been observed in a number of marginal seas over recent decades due to the increasing anthropogenic input of key nutrients. With the intensification of global warming, however, its impact on Chl a in coastal waters along with the superimposed effec...

The upcoming Sentinel-3 Next Generation Topography (S3NG-T) mission, designed to succeed the current Sentinel-3 (S3) mission, will operate on the same ground tracks as the current S3 constellation to maximise continuity of measurements, but with a fixed 4 h temporal lag due to satellite design constraints. This configuration prevents the implementation of a classical near-simultaneous tandem phase, traditionally used for inter...

Current and sea-level observations in the 2.4 km-long, 300 m-wide channel between Varna Lake and the Black Sea, conducted by three novel Hydromast stations with a 1 min resolution, revealed that moderate sub-hourly dynamics were occasionally interrupted by high-amplitude oscillations with a period of a few tens of minutes. The resonant excitation of the events was studied using barotropic 1D analytical and numerical methods. B...

The North Pacific Intermediate Water (NPIW) plays an important role in regulating thermohaline structure and biogeochemical distributions in the North Pacific. However, limited continuous observations have hindered our understanding of its short-term variability and structural response to mesoscale processes. Based on 1 year mooring observations from three sites (M1–M3) in the western North Pacific, this study investigates the...

At the edge of the Amazon River plume, stirring by the North Brazil Current (NBC) and its eddies creates sharp surface thermohaline gradients on horizontal scales of 𝒪 (1–100) km. This study provides a comprehensive picture of these gradients and fronts associated with the region's distinctive dynamics. Saildrone observations show that the plume amplifies density gradient variability at all scales from 1–100 km, with frontal s...

The warm Atlantic inflow across the Iceland-Faroe Ridge (IFR) is the strongest of the three branches carrying warm water to the Nordic Seas and further into the Arctic Ocean. This branch (IF-inflow) carries almost 50 % of the total Atlantic water inflow. After crossing the ridge, a large part of this water is converted to dense water that returns to the Atlantic as cold overflow, which contributes to the deep limb of the Atlan...

The Arctic Ocean is undergoing rapid change, yet many CMIP-type climate models struggle to accurately represent its circulation and water masses. A key feature of the system is the topographically controlled boundary currents that transport warm, saline Atlantic Water northward at intermediate depths into the Atlantic Water layer. An important process affecting these boundary currents is the lateral flux of heat and salt drive...

High-resolution satellite observations are essential for studying fine-scale ocean processes. Yet, present satellite sea surface salinity (SSS) products remain too coarse to resolve many fine-scale structures. We investigate denoising diffusion models as a generative framework for SSS downscaling in a controlled proof-of-concept experiment based on GLORYS reanalysis fields. A multichannel diffusion prior is trained on 1/12° SS...

On the continental slope north of Svalbard, the boundary current carrying Atlantic Water (AW) loses heat as it flows eastward. This cooling cannot be fully attributed to atmospheric heat loss or turbulent mixing. Lateral exchange, potentially linked to mesoscale activity, has previously been proposed as a contributing factor, based on limited observations of eddies. Here, we analyse a year-long dataset of hydrography and veloc...

The vast majority of studies examining the impact of freshwater from ice sheet melting on the Atlantic Meridional Overturning Circulation (AMOC) use climate models that cannot resolve mesoscale ocean processes and do not include an accurate spatio-temporal distribution of the freshwater forcing. These two factors critically affect the nature of the AMOC response. Our study partially fills that gap with a set of three hosing ex...

Global shelf seas have experienced unprecedented marine heatwaves (MHWs) in recent decades. Although MHWs have been extensively studied at the global scale, their regional variability and underlying mechanisms remain poorly understood, particularly in shelf seas influenced by multiple climate modes. Here, we examine MHW variability in the Northeastern Atlantic shelf using a correlation-based k-means clustering approach. Two di...

The Arctic Ocean is undergoing rapid change, with freshwater playing a central role in shaping stratification, vertical heat exchange, and sea-ice loss. Using long-term observations from the Nansen and Amundsen Basins Observational System (NABOS), we document a strong freshening event in the eastern Eurasian Basin between late 2015 and early 2017. During this period, salinity in the upper 175 m decreased by ∼ 0.5 psu, equivale...

The abyssal Ionian Sea is a deep region of interest for the entire ocean circulation of the Mediterranean Sea, since it plays an important role in the ventilation processes of the whole basin. Here we investigate spatial patterns of internal wave climate over the bottom of the Ionian sub-basin. To identify regional features of the internal wave field in terms of vertical shear and strain, we analyze LADCP and CTD profiles, mea...

This study characterizes seasonal hydrography and mixing processes in Almirantazgo Fjord, a sensitive ecosystem in southern Chilean Patagonia. Although estuarine and tidal forcing conventionally explain fjord dynamics, wind stress effects remain less understood in this high-latitude region. The study analyses a comprehensive six-month dataset including a moored time-series of temperature, salinity, and dissolved oxygen, cross-...

Understanding temporal variations in nearshore sea states is crucial, as they affect shoreline evolution and coastal hazard potential. Local sea state conditions are influenced by large-scale climate modes, yet the underlying mechanisms remain not fully understood. Previous studies have mainly established the climate–sea state links through correlation analyses or other statistical methods. This study investigates whether weat...

Ocean bottom pressure (pb) is critical for monitoring and understanding ocean variability, yet global observations from GRACE and GRACE Follow-On suffer from limited spatiotemporal coverage. State estimation methods allow for the dynamical interpolation of sparse data by optimally combining observations with models. Here we examine the effects of assimilating GRACE data (local pb anomalies and global mean), along with other da...

Since the 1990s, satellite observations have been providing reliable estimates of ocean surface state, including absolute dynamic topography (ADT), sea surface temperature (SST), and sea surface salinity (SSS) at sufficient space and time resolution to characterize ocean dynamics. Together with the extensive hydrographic dataset from Argo and ship-based hydrographic profiles, these measurements provide a comprehensive view of...

This study investigates the dynamics and alteration of a low-density filament driven by freshwater-induced buoyancy embedded within a tidal mixing front, focusing on its spatial and temporal evolution in the near-surface layer (0.1–10 m) of the water column. A high-resolution, multi-sensor dataset, consisting of surface drifters, a drifting sensor chain, and an autonomous surface vehicle equipped with an Acoustic Doppler Curre...

Sediment resuspension, driven by wind-wave-induced shear stress, is a key process influencing coastal water quality, biogeochemical cycles, and the transport of pollutants and organisms. The critical shear stress, τcr, is a central parameter in sediment transport models, since initiation of motion can occur when wave-induced shear stress exceeds the critical value. In this study, we implemented a high-resolution (20 m) spectra...

Satellite-derived oceanic data are frequently affected by cloud cover, resulting in spatiotemporal gaps. The Multi-DINEOF method is widely used to reconstruct multiple oceanic variables. However, Multi-DINEOF essentially remains a matrix-based DINEOF approach and does not fully leverage the correlations among multiple variables. To address this limitation, this study proposes the T-DINEOF model, aiming to improve the accuracy...

This study outlines the development and testing of a Digital Twin Ocean (DTO) framework, aimed at improving coastal ocean forecasts through the use of autonomous underwater gliders. A fleet of gliders were deployed in the western English Channel during August-September 2024 to collect measurements of temperature, salinity, chlorophyll and oxygen, aiming to track the movement of the harmful algal bloom Karenia mikimotoi. Measur...

Satellite and reanalysis data sets are analyzed to explain sea level changes in the tropical North Atlantic margin off northwest Africa. The study domain sea level was rising as far back as 1986 and a pause in sea level rise (hiatus) began around 2010 and stopped in 2019. Characteristics of sea level anomaly and its drivers during a period of rise (1996–2004) and the hiatus period (2010–2018) are analyzed and compared. Results...

Marine heatwaves (MHWs) are defined as prolonged periods of anomalously high ocean temperatures. These events can have severe impacts on marine ecosystems and, if they occur at the surface, can feed back on the atmosphere, changing inland air temperatures and precipitation. We use a comprehensive set of model, reanalysis, and observational datasets to investigate recent changes in North Sea MHWs. All datasets show a significan...