Zarokanellos
Nikolaos
Zarokanellos
Nikolaos
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ArticleFactors governing the deep ventilation of the Red Sea(John Wiley & Sons, 2015-11-19) Papadopoulos, Vassilis P. ; Zhan, Peng ; Sofianos, Sarantis S. ; Raitsos, Dionysios E. ; Qurban, Mohammed ; Abualnaja, Yasser ; Bower, Amy S. ; Kontoyiannis, Harilaos ; Pavlidou, Alexandra ; Asharaf, T. T. Mohamed ; Zarokanellos, Nikolaos ; Hoteit, IbrahimA 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-bottom layer in the Red Sea is a robust feature of the thermohaline circulation. Dense water capable to reach the bottom layers of the Red Sea can be regularly produced mostly inside the Gulfs of Aqaba and Suez. Occasionally, during colder than usual winters, deep water formation may also take place over coastal areas in the northernmost end of the open Red Sea just outside the Gulfs of Aqaba and Suez. However, the origin as well as the amount of deep waters exhibit considerable interannual variability depending not only on atmospheric forcing but also on the water circulation over the northern Red Sea. Analysis of several recent winters shows that the strength of the cyclonic gyre prevailing in the northernmost part of the basin can effectively influence the sea surface temperature (SST) and intensify or moderate the winter surface cooling. Upwelling associated with periods of persistent gyre circulation lowers the SST over the northernmost part of the Red Sea and can produce colder than normal winter SST even without extreme heat loss by the sea surface. In addition, the occasional persistence of the cyclonic gyre feeds the surface layers of the northern Red Sea with nutrients, considerably increasing the phytoplankton biomass.
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ArticlePhysical mechanisms routing nutrients in the central Red Sea(John Wiley & Sons, 2017-11-22) Zarokanellos, Nikolaos ; Kürten, Benjamin Peter Helmut Franziskus ; Churchill, James H. ; Roder, Cornelia ; Voolstra, Christian R. ; Abualnaja, Yasser ; Jones, Burton H.Mesoscale eddies and boundary currents play a key role in the upper layer circulation of the Red Sea. This study assesses the physical and biochemical characteristics of an eastern boundary current (EBC) and recurrent eddies in the central Red Sea (CRS) using a combination of in situ and satellite observations. Hydrographic surveys in November 2013 (autumn) and in April 2014 (spring) in the CRS (22.15°N–24.1°N) included a total of 39 and 27 CTD stations, respectively. In addition, high-resolution hydrographic data were acquired in spring 2014 with a towed undulating vehicle (ScanFish). In situ measurements of salinity, temperature, chlorophyll fluorescence, colored dissolved organic matter (CDOM), and dissolved nitrate: phosphorous ratios reveal distinct water mass characteristics for the two periods. An EBC, observed in the upper 150 m of the water column during autumn, transported low-salinity and warm water from the south toward the CRS. Patches of the low-salinity water of southern origin tended to contain relatively high concentrations of chlorophyll and CDOM. The prominent dynamic feature observed in spring was a cyclonic/anticyclonic eddy pair. The cyclonic eddy was responsible for an upward nutrient flux into the euphotic zone. Higher chlorophyll and CDOM concentrations, and concomitant lower nitrate:phosphorous ratios indicate the influence of the EBC in the CRS at the end of the stratified summer period.
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Technical ReportCALYPSO 2019 Cruise Report: field campaign in the Mediterranean(Woods Hole Oceanographic Institution, 2020-01) Mahadevan, Amala ; D'Asaro, Eric A. ; Allen, John T. ; Almaraz García, Pablo ; Alou-Font, Eva ; Aravind, Harilal Meenambika ; Balaguer, Pau ; Caballero, Isabel ; Calafat, Noemi ; Carbornero, Andrea ; Casas, Benjamin ; Castilla, Carlos ; Centurioni, Luca R. ; Conley, Margaret ; Cristofano, Gino ; Cutolo, Eugenio ; Dever, Mathieu ; Enrique Navarro, Angélica ; Falcieri, Francesco ; Freilich, Mara ; Goodwin, Evan ; Graham, Raymond ; Guigand, Cedric ; Hodges, Benjamin A. ; Huntley, Helga ; Johnston, T. M. Shaun ; Lankhorst, Matthias ; Lermusiaux, Pierre F. J. ; Lizaran, Irene ; Mirabito, Chris ; Miralles, A. ; Mourre, Baptiste ; Navarro, Gabriel ; Ohmart, Michael ; Ouala, Said ; Ozgokmen, Tamay M. ; Pascual, Ananda ; Pou, Joan Mateu Horrach ; Poulain, Pierre Marie ; Ren, Alice ; Tarry, Daniel R. ; Rudnick, Daniel L. ; Rubio, M. ; Ruiz, Simon ; Rypina, Irina I. ; Tintore, Joaquin ; Send, Uwe ; Shcherbina, Andrey Y. ; Torner, Marc ; Salvador-Vieira, Guilherme ; Wirth, Nikolaus ; Zarokanellos, NikolaosThis cruise aimed to identify transport pathways from the surface into the interior ocean during the late winter in the Alborán sea between the Strait of Gibraltar (5°40’W) and the prime meridian. Theory and previous observations indicated that these pathways likely originated at strong fronts, such as the one that separates salty Mediterranean water and the fresher water in owing from the Atlantic. Our goal was to map such pathways and quantify their transport. Since the outcropping isopycnals at the front extend to the deepest depths during the late winter, we planned the cruise at the end of the Spring, prior to the onset of thermal stratification of the surface mixed layer.