Water isotopes in the ocean trace the freshwater exchanges between the ocean, the atmosphere, and the cryosphere and are used to investigate processes of the hydrological cycle. We illustrate offsets in seawater isotopic composition between different datasets that are larger than the expected variability that one often wants to explore. This highlights the need to share seawater isotopic composition samples dedicated to specific intercomparison of data produced in different laboratories.

We explore how a semi-enclosed bay in the Humboldt Current System responds to the passage of extratropical cyclones. Using ERA5 data and acoustic Doppler current profiler observations, we found that intense north winds associated with these cyclones drive surface water into the gulf, creating pressure gradients that alter coastal currents, and may reduce residence times. This enhances our understanding of wind-driven coastal dynamics, impacting marine ecosystems and coastal management globally.

Few observations exist in the Amundsen Sea. Consequently, studies rely on reanalysis (e.g., ERA5) to investigate how the atmosphere affects ocean variability (e.g., sea-ice formation and melt). We use data collected along ice shelves to show that cold, dry air blowing from Antarctica triggers large ocean heat loss, which is underestimated by ERA5. We then use an ocean model to show that this bias has an important impact on the ocean, with implications for sea-ice forecasts.

Recent studies have highlighted the potential vulnerability of the East Antarctic Ice Sheet to atmospheric and oceanic changes. We present new insights from observations from three oceanic moorings below Fimbulisen Ice Shelf from 2009 to 2023. We find that relatively warm water masses reach below the ice shelf both close to the surface and at depth with implications for the basal melting of Fimbulisen.

As Earth’s climate warms, cyclone intensity and rain may increase. Cyclones, like hurricanes, gain strength from warm ocean waters. Understanding how oceans react to strong winds is vital. We highlight ocean responses to pre-storm salinity. Changes in salinity affect oceans during storms: salinity rises, temperature falls, and density increases. We suggest that mixing of near-surface with deeper water may impact heat exchange between the ocean and atmosphere during and after a weather event.