We examine global ocean color data and modeling outputs of nutrients using SOM analysis to identify characteristic spatial and temporal patterns of HNLC regions and their association with different climate modes. HNLC regions in polar and subpolar areas have experienced an increase in phytoplankton biomass over the last decades, particularly in the Southern Ocean. Our study finds that chlorophyll variations in HNLC regions respond to major climate variability signals.

Using tide gauge observations, we show that the acceleration of sea-level rise (SLR) along the coast of the Netherlands started in the 1960s but was masked by wind field and nodal-tide variations. This finding aligns with global SLR observations and expectations based on a physical understanding of SLR related to global warming.

The pathways of the Atlantic circulation form a complex system of currents that change meridionally due to interactions with nearby water masses. Over the last 30 years, hydrographic data have allowed us to characterize these upper, deep, and abyssal currents for the entire water column using high-resolution data, computing their mass, heat, and freshwater transports. Generally, we have found no changes among decades for each current in terms of the transport of mass or properties.

This work is focused on the impacts of climate change on a complex water flow system in the southeastern (SE) Baltic Sea, covering the Nemunas river basin and Curonian Lagoon. The results show that lagoon and sea will receive more water coming from the Nemunas. This will lead to a decreased frequency of saltwater inflow to the lagoon, and water will take less time to renew. Water temperatures in the entire lagoon and the SE Baltic Sea will increase steadily, and salinity values will decrease.

Satellite altimetry provides a unique technique for observing the sea surface height (SSH) signature of internal tides from space. The advances in mapping technique, combined with the accumulation of satellite altimetry data, make it possible to construct empirical models for minor internal tide constituents. This paper demonstrates that N₂ internal tides, the fifth largest tidal constituent, are observed using 100 satellite years of SSH data from 1993 to 2019 by a new mapping procedure.

The Weddell Gyre is key for bottom water formation. Prior studies show warming of the whole water column, except for the gyre’s heat source, Warm Deep Water (WDW). We use Argo floats to estimate a heat budget within WDW. Heat advects into the southern limb and upwards from below throughout. Turbulent diffusion removes heat through the top and transports heat from the southern limb into the interior and southwards towards Antarctica. Turbulent diffusion imports heat across the northern boundary.

Our study shows a high-resolution regional atmospheric model improves near-surface wind and air temperature simulation, resulting in improved circulation and hydrographic simulations in the Pearl River estuary. High-resolution wind forcing is critical for coastal circulation and cross-isobath transport, while high-resolution heat forcing greatly improves sea surface temperature simulation. High-resolution atmospheric forcing is essential for accurately simulating dynamic coastal ocean processes.

Wind waves and swells are major drivers of coastal environment changes and can drive coastal marine hazards such as coastal flooding. In this paper, by using numerical modeling along the European Atlantic coastline, we assess how present and future wave characteristics are impacted by sea level changes. For example, at the end of the century under the SSP5-8.5 climate change scenario, extreme significant wave heights are higher by up to +40 % due to the effect of tides and mean sea level rise.

We estimate subsurface linear and non-linear temperature trends at five coastal sites adjacent to the East Australian Current (EAC). We see accelerating trends at both 34.1 and 42.6 °S and place our results in the context of previously reported trends, highlighting that magnitudes are depth-dependent and vary across latitude. Our results indicate the important role of regional dynamics and show the necessity of subsurface data for the improved understanding of regional climate change impacts.

The transition from an arbitrary initial sea surface height to a geostrophic balance in which the velocity is steady was solved last century for constant Coriolis frequency, f(y), where y is the latitude. This study extends the theory to the realistic case in which f(y) is linear with y. We find that the variation in f(y) translates the steady geostrophic state westward as low-frequency Rossby waves that are harmonic in narrow domains and trapped near the equatorward boundary in wide ones.

This work presents a series of studies conducted by the authors on the application of the Lagrangian approach for the connectivity analysis between different ocean locations in an idealized open-ocean model. We assess how the connectivity properties of typical oceanic flows are affected by the fine-scale circulation and discuss the challenges facing ocean connectivity estimates related to the spatial resolution. Our results are important to improve the understanding of marine ecosystems.

The interaction between the Indonesian Throughflow (ITF) and regional climate phenomena indicates the high relevance for monitoring the ITF. Observations remain temporally and spatially limited; hence near-real-time monitoring is only possible with reanalyses. We assess how well ocean reanalyses depict the intensity of the ITF via comparison to observations. The results show that reanalyses agree reasonably well with in situ observations; however, some aspects require higher-resolution products.

Based on in situ observations combined with sea level anomaly (SLA) data from satellite altimetry, volume as well as heat (relative to 0 °C) transport of the Iceland–Faroe warm-water inflow towards the Arctic (IF inflow) increased from 1993 to 2021. The reprocessed SLA data released in December 2021 represent observed variations accurately. The IF inflow crosses the Iceland–Faroe Ridge in two branches, with retroflection in between. The associated coupling to overflow reduces predictability.

Data assimilation methods that couple observations with dynamical models are essential for understanding climate change. Here, climate includes all sub-elements (ocean, atmosphere, ice, etc.). A common form of combination arises from sequential estimation theory, a methodology susceptible to a variety of errors that can accumulate through time for long records. Using two simple analogs, examples of these errors are identified and discussed, along with suggestions for accommodating them.

Reducing uncertainties in coastal sea level trend estimates requires a better understanding of altimeter measurements and local sea level dynamics. Using long-term sea level time series from the Nouméa tide gauge (New Caledonia) and in situ data collected as part of the GEOCEAN-NC campaign, this study presents a method inspired from Cal/Val studies to re-analyse about 20 years of altimetry observations and re-address the question of sea level evolution in the lagoon.

New Caledonia is a hot spot of internal-tide generation due to complex bathymetry. Regional modeling quantifies the coherent internal tide and shows that most energy is converted in shallow waters and on very steep slopes. The region is a challenge for observability of balanced dynamics due to strong internal-tide sea surface height (SSH) signatures at similar wavelengths. Correcting the SSH for the coherent internal tide may increase the observability of balanced motion to < 100 km.