Sarantis Sofianos

• PhD
• National and Kapodistrian University of Athens

A Bay of Biscay model configuration is used as a test case to assess the data-based consistency of ensemble-based ocean model uncertainties of several types: [A] built-in stochastic parameterizations at regional ocean scales, [B] ocean model response to a global atmospheric model ensemble and [C] both A and B simultaneously. Ensembles of varying le...

Ocean water clarity, influenced by marine chlorophyll concentration, significantly alters the distribution of shortwave radiation in the water column. This work aims to assess the effects of varying chlorophyll on the upper‐ocean physical properties and their subsequent impact on the atmosphere, using a coupled ocean‐atmosphere regional model for t...

This study examines the impact of different turbidity products on the Aegean Sea surface physical characteristics, by performing twin-experiment simulations using a high-resolution regional ocean model. The turbidity products used include an in-situ based diffuse attenuation coefficient dataset at 490 nm (kd490, in m− 1) and a satellite derived kd4...

Ocean water turbidity, influenced by marine chlorophyll concentration, significantly alters the distribution of shortwave radiation in the water column. This work aims to assess the effects of turbidity on the upper-ocean physical properties and their subsequent impact on the atmosphere, using a coupled ocean-atmosphere regional model for the Medit...

The growing energy demand has intensified interest in marine renewable sources. This study assesses wave energy potential in the Mediterranean and Black Seas using a 15-year (2010–2024) wave hindcast with the WaveWatch III model. It examines the spatial and temporal distribution of significant wave height, wave energy period, and overall wave energ...

Accurate modelling of air-sea processes is essential for reliable forecasts of Mediterranean tropical-like cyclones (also known as “Medicanes”). Medicanes occasionally develop in the Mediterranean causing extreme weather conditions with catastrophic potential due to excessive precipitation, windstorms, and coastal flooding. In this work, we investi...

The contribution of surface and lateral forcing to the observed Arabian Gulf warming trend is studied based on the results of a high-resolution (1/100°, 60 vertical layers) MIT general circulation model (MITgcm) covering the period 1993–2021. The model validation against available observations reveals that the simulation satisfactorily reproduces t...

The weather and climate greatly affect the socioeconomic activities on multiple temporal and spatial scales. From a climate perspective, atmospheric and ocean characteristics have determined the life, evolution and prosperity of humans and other species in different areas of the world. On smaller scales, the atmospheric and sea conditions affect va...

The dynamics of fluid flows give rise to robust, persistent circulation features that underpin the flow and exert strong control over the advection of water masses, either enhancing it or supressing it, collectively known as lagrangian coherent structures. Lagrangian approaches and metrics have been shown to be better suited than eulerian ones at l...

Marine chlorophyll concentration has an impact on turbidity affecting the upper-ocean properties and regulating the air-sea fluxes. This work aims at assessing the effect of turbidity, as estimated via surface chlorophyll, on the heat content and dynamics of the Mediterranean and Black Seas. We performed twin-simulation experiments using a regional...

Research infrastructures have been established throughout Europe in order to create robust organizations that will facilitate and enhance research and innovation processes and will advance society with innovative products and services. The Hellenic Integrated Marine Observing, Forecasting and Technology System (component of HIMIOFoTS RI) has been i...

Global warming affects the aquatic ecosystems, accelerating pathogenic microorganisms’ and toxic microalgae's growth and spread in marine habitats, and in bivalve molluscs. New parasite invasions are directly linked to oceanic warming. Consumption of pathogen‐infected molluscs impacts human health at different rates, depending, inter alia, on the b...

We investigate the impact of atmospheric forcing uncertainties on the prediction of the dispersion of pollutants in the marine environment. Ensemble simulations consisting of 50 members were carried out using the ECMWF ensemble prediction system and the oil spill model MEDSLIK-II in the Aegean Sea. A deterministic control run using the unperturbed...

We investigate the impact of atmospheric forcing uncertainties on the prediction of dispersion of pollutants in the marine environment. Ensemble simulations consisted of 50 members were carried out using the ECMWF ensemble prediction system and the oil spill model MEDSLIK-II in the Aegean Sea. A deterministic control run, using the unperturbed wind...

In this article, Part 1 of a two-part series, we run and evaluate the skill of a regional physical-biogeochemical stochastic ocean model based on NEMO. The domain covers the Bay of Biscay at 1/36° resolution, as a case study for open-ocean and coastal shelf dynamics. We generate ensembles of uncertainties from assumptions related to errors in the a...

In this Part 2 article of a two-part series, observations based on satellite missions were used to evaluate the empirical consistency of model ensembles generated via stochastic modelling of ocean physics and biogeochemistry. A high-resolution Bay of Biscay configuration was used as a case study to explore the model error subspace in both the open...

Two of the major risks from an oil spill incident at sea are associated with the maritime transport and the coastal/offshore installations related to the oil and gas industry exploration and exploitation. Such risks call for preparations of the operational response to oil spill incidents, based on the lessons learned from the sinking of Exxon Valde...

The Red Sea, home to the second-longest coral reef system in the world, is a vital resource for the Kingdom of Saudi Arabia. The Red Sea provides 90% of the Kingdom's potable water by desalinization, supporting tourism, shipping, aquaculture and fishing industries, which together contribute about 10-20% of the country's GDP. All these activities, a...

The impact of tides on the Bay of Biscay dynamics is investigated by means of an ocean model twin-experiment, consisted of two simulations with and without tidal forcing. The study is based on a high-resolution (1/36∘) regional configuration of NEMO (Nucleus for European Modelling of the Ocean) performing one-year simulations. The results highlight...

Microplastics (MPs) are a contaminant of growing concern due to their widespread distribution and interactions with marine species, such as filter feeders. To investigate the MPs accumulation in wild and cultured mussels, a dynamic energy budget (DEB) model was developed and validated with the available field data of Mytilus edulis (M. edulis, wild...

The vertical distribution of the DO also presents significant variability (Fig.5). Multidecadal shifts, rather than long-term trends, are observed for the dissolved oxygen and thermohaline characteristics and are associated with known episodic dense water formation events. The latter is true, especially for the EMT period, but to a lesser extent fo...

The variability of the water mass exchange between the Arabian Gulf and the Indian Ocean is investigated using a high-resolution (1/36°) ocean model. We focus on the period from December 1996 to March 1998, having as reference in situ measurements at the Strait of Hormuz. Previous studies, based on models and observations, suggested a perpetual dee...

Formation of intermediate waters in the northern Red Sea was captured by Seagliders during the winter of 2016. The analysis is based on measurements collected by consequent deployments of Seaglider autonomous underwater vehicles along a 70 km transect, which was run repeatedly from the coast to midbasin during the period from October 2015 to May 20...

The interannual variability and the mechanisms controlling the dissolved oxygen concentration in the Mediterranean Sea were investigated through generating gridded fields of dissolved oxygen, salinity and temperature. The Data-Interpolating Variational Analysis (DIVA) software was used to produce a gridded dataset for the time period 1960–2011. Hig...

Abstract. Microplastics (MPs) are a contaminant of growing concern due to their widespread distribution and interactions with marine species, such as filter feeders. To investigate the MPs accumulation by wild and cultured mussels, a Dynamic Energy Budget (DEB) model was developed and validated with the available field data of Mytilus edulis (wild)...

The representation of ocean model errors is required in ensemble-based data assimilation methods. In this study, we assess ocean model uncertainties in a high-resolution Bay of Biscay configuration, using atmospheric ensembles and stochastic ocean simulations. The atmospheric ensemble consists of 50 members produced by the European Centre for Mediu...

The Mediterranean community represented in this paper is the result of more than 30 years of EU and nationally funded coordination, which has led to key contributions in science concepts and operational initiatives. Together with the establishment of operational services, the community has coordinated with universities, research centers, research i...

A 1-D full-life-cycle, Individual-based model (IBM), two-way coupled with a hydrodynamic/biogeochemical model, is demonstrated for anchovy and sardine in the N. Aegean Sea (Eastern Mediterranean). The model is stage-specific and includes a ‘Wisconsin’ type bioenergetics, a diel vertical migration and a population dynamics module, with the incorpora...

Recent reports of warming trends in the Red Sea raise concerns about the response of the basin's fragile ecosystem under an increasingly warming climate. Using a variety of available Sea Surface Temperature (SST) datasets, we investigate the evolution of Red Sea SST in relation to natural climate variability. Analysis of long‐term SST datasets reve...

The interannual variability of the exchange flow between the Red Sea and the Gulf of Aden through the Bab‐al‐Mandeb strait is examined based on a high‐resolution, nonhydrostatic hindcast model simulation covering a 19‐year period (1995–2013), using the MITgcm (MIT general circulation model). The model is validated against moored profiles and along‐...

We generate ocean biogeochemical model ensembles including several kinds of stochastic parameterizations. The NEMO stochastic modules are complemented by integrating a subroutine to calculate variable anisotropic spatial scales, which are of particular importance in high-resolution coastal configurations. The domain covers the Bay of Biscay at 1/36...

The present MONGOOS Science and Strategy Plan has the objective of reviewing the present status of the Mediterranean Sea Oceanographic system, analyzing the existing gaps and deficiencies, and proposing ways forward. It is the result of the contribution of the main institutions working in the area, coordinated within the framework of MONGOOS, the G...

For the first time, LISST-Deep measurements (beam attenuation coefficient, particle volume concentration, and particle size) were obtained across the Mediterranean Sea during the cruise MSM72 (Mediterranean Sea transect). An unexpected increase of particle volume concentration and particle median diameter below ~500 m was observed and was attribute...

We present a new product composed of a set of thermohaline climatic indices from 1950 to 2015 for the Mediterranean Sea such as decadal temperature and salinity anomalies, their mean values over selected depths, decadal ocean heat and salt content anomalies at selected depth layers as well as their long time series. It is produced from a new high-r...

Submarine channels several kilometres wide can be found near sills between major basins but they typically lie on the sides of the sills where dense bottom waters passing between the basins form gravity currents. In the southernmost Red Sea, in contrast, an 8 km-wide and 100-to 250-m deep channel lies on the north side of Hanish Sill, in an area wh...

We present a new product composed of a set of thermohaline climatic indices from 1950 to 2015 for the Mediterranean Sea such as decadal temperature and salinity anomalies, their mean values over selected depths, decadal ocean heat and salt content anomalies at selected depth layers as well as their long times series. It is produced from a new high-...

Oil spills in the ocean are a matter of concern due to the damaging effect they can have on coastal and offshore resources. This work presents a review of present-day modeling techniques used in the mitigation of oil spills by booms, skimmers, chemical dispersants, and other equipment and the importance of the controlling parameters of these techni...

A dynamic energy budget (DEB) model was developed to investigate the growth and reproduction of cultured bivalve species raised under different environmental conditions (varying phytoplankton carbon biomass [Phyto-C], particulate organic carbon [POC] and temperature) and tuned against field data for Mytilus galloprovincialis from the Maliakos and T...

The Central Red Sea (CRS) lies between two distinct hydrographic and atmospheric regimes. In the southern Red Sea, seasonal monsoon reversal regulates the exchange of water between the Red Sea and the Indian Ocean. In the northern Red Sea intermediate and occasionally deep water are formed during winter to sustain the basin's overturning circulatio...

The Gulf of Suez is accepted as an important location for Red Sea Deep Water formation, but the circulation and exchange with the Red Sea around the year remains elusive. A summer cruise in the area gives the opportunity to investigate features of the summertime hydrological structure and exchange with the Red Sea. An inverse estuarine circulation...

Ocean model uncertainties arise on a range of spatiotemporal scales from the formulation of forecast models themselves and erroneous surface-lateral boundary forcings. In the past two decades, successful applications of advanced ocean data assimilation methods have led to an increased interest in their estimation. This study is based on a Copernicu...

The work is based on stochastic modelling of ocean physics and biogeochemistry in the Bay of Biscay, on an identical sub-grid configuration of the IBI-MFC system in its latest CMEMS operational version V2.

Abstract: Dense water formation in the Red Sea fuels its overturning circulation that includes intermediate and deep cells. In particular, the intermediate basin-wide conveyor belt, through an inverse estuary circulation pattern, converts the fresher Indian Ocean water to the denser and much saltier Red Sea Outflow Water. The major intermediate wat...

Abstract: The thermohaline characteristics and the circulation patterns of the Red Sea present strong variability at various time scales that is related to the strong and variable atmospheric forcing and the exchange with the Indian Ocean and the gulfs located at the northern end of the basin. Sea surface temperature time-series, derived from satel...

The aim of this work is to study the response of an ocean circulation model in the Eastern Mediterranean Sea, using a new drag coefficient formula based on observations at this area. Thirty twin simulation experiments of 5-days, using two different drag coefficient parameterizations were carried out by the Aegean-Levantine Eddy Resolving Model in a...

Although progress has been achieved in describing and understanding the mean state and seasonal cycle of the Red Sea dynamics, their interannual variability is not yet well evaluated and explained. The thermohaline characteristics and the circulation patterns present strong variability at various time scales and are affected by the strong and varia...

A variety of data based on hydrographic measurements, satellite observations, reanalysis databases, and meteorological observations are used to explore the interannual variability and factors governing the deep water formation in the northern Red Sea. Historical and recent hydrographic data consistently indicate that the ventilation of the near bot...

Operational ocean forecast systems provide routine marine products to an ever-widening community of users and stakeholders. The majority of users need information about the quality and reliability of the products to exploit them fully. Hence, forecast centres have been developing improved methods for evaluating and communicating the quality of thei...

We study the performances of (a) fully two-way coupled atmosphere–ocean modeling system and (b) one-way coupled ocean model (forced by the atmospheric model hourly output), as compared to the available in situ (mooring and CTD) measurements during and after an strong Bora wind event in February 2012, which led to extreme air–sea interactions and re...

On the influence of a regional drag coefficient parameterization scheme in the forecasting skill of an ocean model in the Aegean and Levantine Seas. Kostopoulos Vassilis (1), Chrisagi Eurydice (2), Sofianos Sarantis (2), and Helmis Constantinos (1) (1) Univercity of Athens, Environmental Physics and Meteorology, Athens, Greece (vkostopoulos@phys.uo...

The Red Sea experiences strong atmospheric forcing through both wind stress and air–sea buoyancy fluxes. Direct observations and modeling experiment show a robust response that consists of a strong and complicated three-dimensional circulation pattern with intense seasonal variability, involving water masses that are locally formed in the Red Sea o...

The interannual variability of the circulation and water mass formation in the Red Sea is investigated with the use of a numerical model and the combination of satellite and in-situ observations. The response of Red Sea to the large-scale variability of atmospheric forcing is studied through a 30-years simulation experiment, using MICOM model. The...

Results from a high-resolution hindcast model experiment, supported by available observations, reveal an increasing salinity trend in the north Aegean during the Eastern Mediterranean Transient (EMT) period, largely controlled by increases in the flow rate and salinity of water masses of Levantine origin entering the domain through the Myconos-Ikar...

Based on the observed variability of the deep-water characteristics in the Eastern Mediterranean Sea, multidecadal high-resolution model simulations, at the basin scale, were carried out in order to identify the major pattern and processes of deep-water formation variability in the Aegean Sea and its influence in the adjacent basins deep circulatio...

This paper is the outcome of a workshop held in Rome in November 2011 on the occasion of the 25th anniversary of the POEM (Physical Oceanography of the Eastern Mediterranean) program. In the workshop discussions, a number of unresolved issues were identified for the physical and biogeochemical properties of the Mediterranean Sea as a whole, i.e., c...

The eastern basin of the Mediterranean is a remote area of the world ocean, the isolation of its various basins increased with distance from the Atlantic Ocean and with further constraints posed by the various straits. This chapter analyzes the deep-water characteristics independent of the changes in the upper-water column. It provides the data sou...

Recent dramatic changes of the thermohaline circulation of the Eastern Mediterranean and the observed long-term variability of the thermohaline structure of the various sub-basins (Aegean, Adriatic, Levantine, Ionian) reveal the very sensitive character of the regional thermohaline circulation pattern. We examine deep-water variability, during the...

The exchange water fluxes between the Black Sea and the North Aegean Sea through the Dardanelles Strait constitute an essential factor for the general circulation of the region. The Black Sea Water (BSW) inflow to the Aegean plays an important role in the hydrography and circulation of the basin and can affect the North Aegean deep water formation...

The importance of the Mediterranean Sea for the world ocean has long been recognized. First, the Mediterranean sea has a profound impact on the Atlantic ocean circulation and, consequently, on the global thermohaline conveyor belt. Maps of the Mediterranean salty water tongue exiting from the Gibraltar strait at intermediate depths and spreading th...

The Ionian Sea, located in the center of the Mediterranean basin, represents the crossroad between water masses originated in the Western and in the Eastern Mediterranean. The interannual variability of the circulation pattern of this basin and its role as a "water mass distributor" is studied by performing a hindcast simulation using the Princeton...

Saudi Aramco is the oil industry of the Kingdom of Saudi Arabia with several activities related to the environment. In order to optimize daily operations and minimize environmental risks a forecasting system has been employed and setup in operations. The objectives of the system include prevention and mitigation of environmental problems, as well a...

Assimilating observed ocean state variables improves the forecast skill of oceanic flow models. Many forecast centers and institutions assimilate remotely-sensed observations such as sea level anomaly, sea surface temperature, and surface currents. For further improvement, in situ data from the ocean depths are assimilated, typically temperature an...

A web-based validation platform has been developed at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) for the Near Real Time validation of the MyOcean-Mediterranean Monitoring and Forecasting Centre products (Med-MFC). A network for the collection of the in-situ observations, the nested sub-basin forecasting systems model data (provided b...

The Eastern Mediterranean deep-water variability during the last 60 years, in relation to new water mass sources, is studied and analyzed through a comprehensive and most complete data set of temperature and salinity profiles. Decadal to multi-decadal variability is present in all sub-basins (Aegean, Adriatic, Levantine, Ionian) with the Eastern Me...

The exchange between the Red Sea and the Indian Ocean on synoptic time scales (days to weeks) is investigated using moored current meter data collected in the strait of Bab el Mandeb from June 1995 to November 1996. Transport variations through the strait on these time scales can reach amplitudes of up to 0.6 Sv (1 Sv ≡ 10 6 m 3 s -1), or nearly tw...

Recent changes of the thermohaline circulation in the Eastern Mediterranean (i.e. the Eastern Mediterranean Transient) and older observations of the thermohaline structure of the Aegean-Levantine region (with events of dramatic changes of deep water characteristics) reveal the very sensitive character of the regional thermohaline circulation patter...

The simulation of the transport and fate of an oil slick, accidentally introduced in the marine environment, is the focus of this research. An oil spill dispersion forecasting system (DIAVLOS forecasting system), based on wind, wave and ocean circulation forecasting models is developed. The 3-D oil spill model, by the University of Thessaloniki, is...

The long term variability of the sea surface temperature (SST) of the Mediterranean basin and its sub‐basins for the period 1869–2006 (138 years) is investigated using the International Comprehensive Ocean—Atmosphere Data Set (I‐COADS). Analysis of the SST time‐series revealed a positive trend in both basin and sub‐basin scale. During the last cen...

Aiming at portraying the Aegean's water mass structure and identifying Dense Water Formation processes, two winter cruises were conducted in 2005-2006, across the plateaus and depressions of the Aegean Sea. The most prominent feature of the water mass distribution in the basin is a distinct "X-shape" of the Θ-S characteristics, suggesting a complic...

Twenty-four years of AVHRR-derived sea surface temperature (SST) data (1985–2008) and 35years of NOCS (V.2) in situ-based SST data (1973–2008) were used to investigate the decadal scale variability of this parameter in the Mediterranean Sea in relation to local air–sea interaction and large-scale atmospheric variability. Satellite and in situ-deriv...