ALBERT

Description: One of the societal outcomes of the UN Decade of Ocean Science for Sustainable Development (2021-2030) is a Safe Ocean. The Sub Commission for the Caribbean and Adjacent Regions of UNESCO’s Intergovernmental Commission (IOCARIBE) hosted in 2020-2022 events to facilitate the co-design of actions for the different Ocean Decade Outcomes and Capacity Development. For the Safe Ocean outcome, the project Integrating Coastal Hazard Early Warning Systems for the Tropical Americas and Caribbean (iCHEWS) was submitted. It was endorsed in June 2022 and attached to the Ocean Decade Programme Coast Predict (University of Bologna). iCHEWS prioritizes the integration of existing and new coastal hazards early warning systems and services considering four components: Risk Knowledge, Monitoring and Forecasting, Warning Dissemination and Communication, and Response Capabilities, with cross cutting governance and capacity development considerations. Hazards considered to be of highest priority were: Climate Change and its cascading impacts, including but not limited to more intense and frequent tropical cyclones and sea level rise, tsunamis, sargassum, wastewater, oil spills, and coral bleaching. Linkages to regional and international efforts (Target G of the Sendai Framework, and the United Nations Early Warning for All Initiative) and national and local priorities would be maximized and strengthened. The creation of a sustainable and responsive Governance and Management framework is under discussion. Principals of iCHEWS have begun conversations with Coast Predict. As a Demonstration Product, the definition of a regional Blue Line, defining an all-inclusive coastal inundation (storm surge, tsunami, sea level rise) has been proposed.

Description: In this work we discuss some asymptotic properties of the Gaussian kernel (GK) estimator for the correlation between two time series sampled on different time points and their relevance for the construction and interpretation of bootstrap based confidence intervals.In particular, we show that the GK estimator is asymptotically biased and converges to a weighted average of the cross-correlation function in a neighbourhood of zero. As a result, any bootstrap procedure for the construction of confidence intervals that combines the GK estimator with a standard method based on percentiles of its bootstrapped distribution(such the bias-corrected and accelerated method) asymptotically will have zero coverage even after applying recalibration. This does not imply, however, that bootstrap confidence intervals are useless. In fact, we show through an extensive simulation study, that a suitable block-bootstrap procedure can provide a useful lower bound for the absolute correlation and, in some special cases, confidence intervals with approximately the correct coverage. The ideas explored in this work apply as well to the more general problem of estimating the cross-correlation function of a bivariate time series whose components are sampled on different time points using a kernel-based estimator.

Description: A geodetic estimation of the 3D-Geostrophic Currents (GC) and Volume Transport (VT) for the Southern Ocean is provided from satellite data by combining the SSH from altimetry missions, the geoid from satellite gravity missions, and temperature and salinity profiles based on ARGO and other in-situ measurements . The estimated 3D GC is provided near full-depth in 41 layers, with a 1º spatial resolution and monthly temporal resolution, covering the 12 years period from 2004 to 2015. We analyze the obtained 3D GC over the Southern Ocean region, where the Antarctic Circumpolar Current (ACC) and its several fronts are clearly depicted, as well as other major currents such as the Agulhas current, the Malvinas current or the East Australian Current. From the 3D GC, we estimate the associated water VT and present the results for the ACC and the Drake Passage in the context of existing literature. The spatial resolution of our space data-based approach allows us to provide VT estimates for the different paths followed in the different in-situ campaigns at the Drake Passage. The results not only validate our study but also reconciles the different estimates, showing a general good agreement for the different campaigns and how the existing estimates differences depend on the epoch and exact location where the in-situ measurements were taken.

Description: The water cycle of the Baltic Sea has been estimated from Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On satellite time-variable gravity measurements, and precipitation and evaporation from ERA5 atmospheric reanalysis data for the periods 06/2002 to 06/2017, and 06/2018 to 11/2021. On average, the Baltic Sea evaporates 199 ± 3 km〈sup〉3〈/sup〉/year, which is overcompensated with 256 ± 6 km〈sup〉3〈/sup〉/year of precipitation and 476 ± 17 km〈sup〉3〈/sup〉/year of water from land. This surplus of freshwater inflow produces a salty water net outflow from the Baltic Sea of 515 ± 27 km〈sup〉3〈/sup〉/year, which increases to 668 ± 32 km〈sup〉3〈/sup〉/year when the Kattegat and Skagerrak straits are included. The Baltic net outflow reaches an annual minimum of 221 ± 79 km〈sup〉3〈/sup〉/year in September and a maximum of 814 ± 94 km〈sup〉3〈/sup〉/year in May, mainly driven by the freshwater contribution from land. At interannual scale, the annual mean of the Baltic net outflow can vary up to 470 km〈sup〉3〈/sup〉/year from year to year. This variability is not directly related to the North Atlantic Oscillation during wintertime, although the latter is well correlated with net precipitation in both continental drainage basin and Baltic Sea. Acknowledgements: AB is funded by the Algerian Ministry of Higher Education and Scientific Research. MIV, DGG and JMS are partially funded by Spanish Ministry of Science, Innovation and Universities grant number PID2021-122142OB-I00, and Generalitat Valenciana (GV) grant numbers GVATHINKINAZUL/2021/035. MIV and DGG are also funded by GV grant number PROMETEO/2021/030.

Description: It is known that an overturning circulation develops in the Mediterranean Sea, although substantially weaker and smaller than in the North Atlantic. We use monthly mean fields from a high-resolution ocean reanalysis (1/16º ×1/16º) to explore seasonal and interannual variability of Mediterranena Sea overturning circulation in both depth and water mass parameter spaces (potential density, potential temperature, salinity) from 1987 to 2018. Results show a clear single zonal clockwise transport cell in all three spaces that extends from the Strait of Gibraltar to the Levantine Basin, in which water masses tend to densify as they move eastward. This densification is mainly controlled by salinity in the Eastern Mediterranean basin (EMED), while in the Western Mediterranean (WMED) both salinity and potential temperature variations must be taken into account. In contrast, the meridional overturning transport, much more complex, is able to capture smaller-scale variations better since it responds faster to perturbations in the circulation. Seasonal variations in overturning transport are reflected in the size and strength of overturning cells in all spaces, being remarkably narrower in winter than in summer. Regarding interannual changes, we show that the zonal overturning transport in density space is significantly correlated with the North Atlantic Oscillation, the Mediterranean Oscillation Index and the Scandinavian pattern during wintertime in the WMED. In contrast, no significant correlations appear in the zonal components of EMED, although the overturning metric in density space captures well the Eastern Mediterranean Transient, that occurred during years 1992–1996.