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Vassilis P. Papadopoulos, Aristides Bartzokas, Themistoklis Chronis, Dimitris Georgopoulos, and George Ferentinos

Abstract

The authors examine the impact of low-frequency atmospheric forcings on the air–sea heat fluxes over the Aegean Sea. The correlation between the air–sea heat flux components and three established [North Atlantic Oscillation (NAO), east Atlantic–western Russian pattern (EAWR), and North Sea–Caspian pattern (NCP)] and two testing climatic indices of potential effect over the eastern Mediterranean Sea region underlines significant discrepancies between the radiative (shortwave and longwave radiation) and the turbulent (sensible and latent heat) components. The NAO index affects the air–sea heat fluxes over the Aegean Sea region much less than the two innovative indices, the “Mediterranean index” and the “Eastern Europe index,” which play more effective roles. Moreover, the influence of the sea level atmospheric pressure (SLP) variability over an extended area (Europe and North Africa) on surface fluxes regime is investigated. The SLP anomalies are corroborated as a prominent regulating factor of the air–sea heat fluxes over the Aegean Sea region, especially during the cold season of the year. The analysis of the extreme values in the heat exchange anomalies for the period 1958–2001 highlights the role of SLP field on determining the air–sea heat fluxes regime, mainly during winter, when, occasionally, large amounts of heat loss from the sea surface trigger the mechanism of intermediate- and deep-water formation. It is suggested that wind regime and turbulent components are the modulators of the net air–sea heat flux anomalies throughout the year.

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Yasser Abualnaja, Vassilis P. Papadopoulos, Simon A. Josey, Ibrahim Hoteit, Harilaos Kontoyiannis, and Dionysios E. Raitsos

Abstract

The impacts of various climate modes on the Red Sea surface heat exchange are investigated using the MERRA reanalysis and the OAFlux satellite reanalysis datasets. Seasonality in the atmospheric forcing is also explored. Mode impacts peak during boreal winter [December–February (DJF)] with average anomalies of 12–18 W m−2 to be found in the northern Red Sea. The North Atlantic Oscillation (NAO), the east Atlantic–west Russia (EAWR) pattern, and the Indian monsoon index (IMI) exhibit the strongest influence on the air–sea heat exchange during the winter. In this season, the largest negative anomalies of about −30 W m−2 are associated with the EAWR pattern over the central part of the Red Sea. In other seasons, mode-related anomalies are considerably lower, especially during spring when the mode impacts are negligible. The mode impacts are strongest over the northern half of the Red Sea during winter and autumn. In summer, the southern half of the basin is strongly influenced by the multivariate ENSO index (MEI). The winter mode–related anomalies are determined mostly by the latent heat flux component, while in summer the shortwave flux is also important. The influence of the modes on the Red Sea is found to be generally weaker than on the neighboring Mediterranean basin.

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Vassilis P. Papadopoulos, Simon A. Josey, Aristides Bartzokas, Samuel Somot, Simon Ruiz, and Paraskevi Drakopoulou

Abstract

Atmospheric circulation patterns that are conducive to extreme ocean heat loss are investigated at four sites of special interest in the Mediterranean Sea. The Gulf of Lions, the South Adriatic Sea, the Cretan Sea, and the Levantine Sea are areas where anomalously high winter heat loss may lead to deep- or intermediate-water formation. At each of the above sites, the atmospheric circulation during such events is derived by averaging the sea level pressure (SLP) fields during the lower decile of the wintertime series of the net heat exchange. A relatively simple SLP pattern dominated by an anticyclone over northwestern Europe with a weaker cyclone to the southeast is found to be associated with strong heat loss in the selected sites with minor variations in pattern structure depending on the site. The SLP composite pattern reflects the combined effect of different atmospheric modes of variability and the authors consider the impacts on heat loss of a number of these modes (North Atlantic Oscillation, east Atlantic pattern, east Atlantic–west Russia pattern, and Scandinavian pattern), together with the North Sea–Caspian pattern and the Mediterranean index. The extremes in heat loss are strongly connected with the intensity and the positions of the poles of these patterns that modulate, through the necessary SLP gradient and associated northerlies, the transfer of cold and dry air over the areas of dense-water formation. Analysis of air–sea temperature difference, specific humidity, and evaporation anomalies indicates that the extremes of the net heat fluxes are primarily due to the latent and sensible heat flux components.

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Vassilis P. Papadopoulos, Yasser Abualnaja, Simon A. Josey, Amy Bower, Dionysios E. Raitsos, Harilaos Kontoyiannis, and Ibrahim Hoteit

Abstract

The influence of the atmospheric circulation on the winter air–sea heat fluxes over the northern Red Sea is investigated during the period 1985–2011. The analysis based on daily heat flux values reveals that most of the net surface heat exchange variability depends on the behavior of the turbulent components of the surface flux (the sum of the latent and sensible heat). The large-scale composite sea level pressure (SLP) maps corresponding to turbulent flux minima and maxima show distinct atmospheric circulation patterns associated with each case. In general, extreme heat loss (with turbulent flux lower than −400 W m−2) over the northern Red Sea is observed when anticyclonic conditions prevail over an area extending from the Mediterranean Sea to eastern Asia along with a recession of the equatorial African lows system. Subcenters of high pressure associated with this pattern generate the required steep SLP gradient that enhances the wind magnitude and transfers cold and dry air masses from higher latitudes. Conversely, turbulent flux maxima (heat loss minimization with values from −100 to −50 W m−2) are associated with prevailing low pressures over the eastern Mediterranean and an extended equatorial African low that reaches the southern part of the Red Sea. In this case, a smooth SLP field over the northern Red Sea results in weak winds over the area that in turn reduce the surface heat loss. At the same time, southerlies blowing along the main axis of the Red Sea transfer warm and humid air northward, favoring heat flux maxima.

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Ibrahim Hoteit, Yasser Abualnaja, Shehzad Afzal, Boujemaa Ait-El-Fquih, Triantaphyllos Akylas, Charls Antony, Clint Dawson, Khaled Asfahani, Robert J. Brewin, Luigi Cavaleri, Ivana Cerovecki, Bruce Cornuelle, Srinivas Desamsetti, Raju Attada, Hari Dasari, Jose Sanchez-Garrido, Lily Genevier, Mohamad El Gharamti, John A. Gittings, Elamurugu Gokul, Ganesh Gopalakrishnan, Daquan Guo, Bilel Hadri, Markus Hadwiger, Mohammed Abed Hammoud, Myrl Hendershott, Mohamad Hittawe, Ashok Karumuri, Omar Knio, Armin Köhl, Samuel Kortas, George Krokos, Ravi Kunchala, Leila Issa, Issam Lakkis, Sabique Langodan, Pierre Lermusiaux, Thang Luong, Jingyi Ma, Olivier Le Maitre, Matthew Mazloff, Samah El Mohtar, Vassilis P. Papadopoulos, Trevor Platt, Larry Pratt, Naila Raboudi, Marie-Fanny Racault, Dionysios E. Raitsos, Shanas Razak, Sivareddy Sanikommu, Shubha Sathyendranath, Sarantis Sofianos, Aneesh Subramanian, Rui Sun, Edriss Titi, Habib Toye, George Triantafyllou, Kostas Tsiaras, Panagiotis Vasou, Yesubabu Viswanadhapalli, Yixin Wang, Fengchao Yao, Peng Zhan, and George Zodiatis

Abstract

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, and those elsewhere in the Red Sea region, critically depend on oceanic and atmospheric conditions. At a time of mega-development projects along the Red Sea coast, and global warming, authorities are working on optimizing the harnessing of environmental resources, including renewable energy and rainwater harvesting. All these require high-resolution weather and climate information. Toward this end, we have undertaken a multipronged research and development activity in which we are developing an integrated data-driven regional coupled modeling system. The telescopically nested components include 5-km- to 600-m-resolution atmospheric models to address weather and climate challenges, 4-km- to 50-m-resolution ocean models with regional and coastal configurations to simulate and predict the general and mesoscale circulation, 4-km- to 100-m-resolution ecosystem models to simulate the biogeochemistry, and 1-km- to 50-m-resolution wave models. In addition, a complementary probabilistic transport modeling system predicts dispersion of contaminant plumes, oil spill, and marine ecosystem connectivity. Advanced ensemble data assimilation capabilities have also been implemented for accurate forecasting. Resulting achievements include significant advancement in our understanding of the regional circulation and its connection to the global climate, development, and validation of long-term Red Sea regional atmospheric–oceanic–wave reanalyses and forecasting capacities. These products are being extensively used by academia, government, and industry in various weather and marine studies and operations, environmental policies, renewable energy applications, impact assessment, flood forecasting, and more.

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