Coastal OceAn SusTainability in Changing Climate – COAST

IORAS together with KAUST and IGE has built several model configurations for the coastal areas of the Black and Azov Seas, the Red Sea and the coast of the Arctic Seas. For all areas, regional versions of the WRF-ARM model were adapted, which allowed for accounting for high intensity of extreme hydroclimatic events. The model configuration for the Black Sea coast was adapted to the boundary conditions available from the operational analysis data (FNL) and ERA5 reanalysis. FNL (NCEP Final Analysis) data is a product of the Global Data Assimilation System (GDAS) including station measurements, buoys, satellite information, atmospheric sounding data, radar data, shipborne measurements and other sources. This information is assimilated into the spectral model of the Global Forecast System (GFS).
IGE developed a new data base of precipitation rain gauge measurements was developed for the Gulf of Lion. Altogether about 400 stations captured by the basins of the system of small rivers and the groundwater flow regions of southern France were selected after quality control.
For all regions IORAS and FURG also created databases of meteorological parameters over offshore areas using ICOADS (International Comprehensive Ocean Atmosphere Data Set) global archive for the period from 1950 to 2021. In particular, the most comprehensive data base was developed for the coastal zone of Brazil, including the La Plata basin. Of a specific interest is the analysis of wind and wave parameters available from visual observations (the only source of independent estimates of the characteristics of wind waves and swell waves) of direction, height, period. This subset makes it possible to also compute wave geometry characteristics, significant wave heights and their dominant periods.
IGE together with IORAS evaluated the performance of high-resolution regional climate models (RCM) simulations in representing the characteristics of widespread extreme precipitation events and their associated large-scale synoptic systems across different complex orographic precipitation regimes in Mediterranean regions and European-North-Atlantic sectors using the recent ERA5 ECMWF reanalysis during 1980-2010. The high-resolution quality-controlled observational precipitation datasets compiled from a higher density rain gauge stations, along with E-OBS data, have been used to validate the precipitation simulated by RCMs.
Also the analysis included the impact of the atmospheric dynamics onto local infrastructure. Exposed to mid-latitudinal cyclones from north, west, and south, the Black Sea is bounded from the East by the Caucasus Mountains that closely follow its northeastern coast and create orography effects responsible for heavy precipitation uphill and mighty rivers that accumulate rainfall over the mountain slopes to bring them to the Sea by violent streams.

‘WHITE COAST’ was focused on climate impacts and hydrological cycle changes in selected regions, comprising atmospheric processes, transports of aerosols, climate indicators, precipitation, moisture transports and air-sea interactions;
‘YELLOW COAST’ was concentrated on the land hydrology, continental discharges, matter and pollutant impacts onto the ocean state and health;
‘BLUE COAST’ was covered coastal ocean dynamics, including transports of sediments and pollutants in the coastal area using best available observational and remote sensing data as well as state of the art ocean models;
‘GREEN COAST’ was focused on the coastal ecosystem responses and will cover their dynamics under the compound impact of climate, hydrological and ocean factors, thus tracking regional biodiversity and its sustainability;
‘RED COAST’ was considered consolidated impacts of coastal ocean processes on human activity, well being, infrastructure and regional sectors of economy, including transportation, fishery, tourism and others.

We found that Kara Sea coast is strongly affected by continental runoff (about 1350 km3 annually of which 70% is from Ob and Yenisei) forming a buoyant plume extending in area to 40% of the Kara Sea. Kara Sea dynamics is determined by the interaction of Barents Sea waters, propagating through the Kara Strait with Arctic Basin waters, invading from the north near the St. Anna Trench and with freshwater runoff from Ob and Yenisei. The latter is mostly forming surface sea layer interannual variability in response to variability of river runoffs and regional winds. Black sea coastal zone is influenced by freshwater inflows from ~20 small and mid-size rivers which provide ~25% of 350 km3 annual runoff into the Black Sea (the remaining
are due to 4 major rivers Danube, Dniepr, Rioni, and Dniestr). This inflow along with flash continental discharges due to
extreme precipitation events is characterized by the strongest variability of transported terrigenic pollutants and suspended
matter into the sea affecting the alongshore area of several kilometers. Also for the Black Sea we have diagnosed the
compound mechanisms resulting in regional extreme events with inundation of the coastal areas (e.g. recent Bettina Storm in November 2023). For the tropical coastal Atlantic Ocean off South America we quantified the strong advection of suspended and dissolved matter, including pollutants by the Plata Estuary of Parana and Uruguay Rivers along with Patos-Mirim Lagoon (PML) tributary river complex. For the Red Sea we analysed the effect of potential modification of the coastal areas onto changes of the regional moisture budget and delivered the model for assign these effects.
Detailed analysis of the role of moisture advection onto Gulf of Lyon allowed for identifying different regimes of the regional
coastal zone.

One of such kind of outcomes is definitely a strong impact of sea level changes onto coastal erosion in the Raka Sea and also in the Gulf of Lyon. Also we were able to demonstrate that in the Red Sea coastal ecosystem which includes the extended coral reefs forming a unique habitat as the plankton of coral reefs interacts within an ecosystem radically different from that of the open ocean. In the Gulf of Lyon the local coastal hydrological cycle is accelerating with growing SST with alternating each other periods of excessive atmospheric moisture transports and dry regimes. We also found that South Atlantic coast basin is affected by ENSO events and this impact on a long term river discharges are increasing. During El Nino, the regional plume attains a distance of 30 to 40 km from the mouth and increases buoyancy along the coastal zone.

Project delivered better understanding of the physical processes in coastal regions under the climate changes which resulted in many high ranked scientific publications.

COAST (Coastal OceAn SusTainability in Changing Climate) project focuses on the sustainability of the coastal ocean under the impacts of
ongoing and projected climate variability and change. The project will address impacts of climate change and increased human activity on coastal
zones by integrating the natural and social domains of the coastal ocean and tracking how changes will affect the use and the infrastructure of today
and in different scenarios for the future. We will assess the impact on human communities in view of their ability to adjust to long-term change in
terms of policy-making, legislation, and business development and survival rates.
With the project motto "think globally - act regionally" COAST will consider shelf areas of the polar Kara Sea and of the Black Sea, the tropical
coastal Atlantic Ocean off South America (estuary of Parana and Uruguay Rivers) and the coastal areas of the arid Red Sea. All these regions are
characterized by medium to high human impact on marine ecosystems, different tendencies in sea level, increasing impacts of waves and surges on
coastal erosion and intensified coastal hydrological cycles. Project methodologies include data analysis, ocean circulation and wave models forced
by high resolution atmospheric model, process-oriented models for river plumes, pollutant transports and ecosystems. The further use of regional
climate models will ensure for developing improved regional projections under different climate change scenarios. Physical model results will be
incorporated into regional configurations of socio-economic model for the translation of regional physical and biochemical variables into a suite of
impact metrics.
The project will be carried out by international and multidisciplinary team of natural scientists (IORAS, FURG, IGE, and KAUST), social scientists
(GWU and IEPRAS), NGO and in-kind partners and stakeholders from different industries representing Russia, Brazil, France, Saudi Arabia and
USA. This ensures the development of society-relevant recommendations and environmentally friendly business solutions for ocean coastal areas.