Karakteristike egipatskih vodenih masa tijekom hladnih i toplih zima (original) (raw)
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Hydrographic Variations in the deep and shallow areas of the Egyptian Mediterranean Coast
Proceedings of the IUGG XXIV, 2007
Water temperature, salinity and conductivity profiles were obtained at each location during the mobilization, service visits and final recovery from February, 1999 to January, 2000. A Seabird 19 CTD recorder was used to obtain data at regular intervals throughout the water column from 1m below the surface to the seabed. The instrument was set up to take readings at a rate of 2 samples every second. CTD data were recorded on both the downward and the upward casts. At locations C02, C05, C06, C07, C06, C09 and C12: CTD profiles at these shallow water locations showed the water column to be well mixed, with temperature, salinity and density being constant throughout depth. The calculated salinity at each of the service visits fluctuated around 39 with a slight increase in salinity in the months of October 1999 through to December 1999. Only at C7, the shallowest measurement location (7m), was a lower salinity value of 37.5 recorded. At locations C01, C03, C04, C10, C11, M01 and H01: CTD profiles taken at the deeper water moorings indicate a seasonal variation to the water column structure. During the months of February to April 1999, the temperature, salinity and density were fairly uniform throughout the water column, although an increase in density and a decrease in temperature were observed at most of the deeper water locations. During the June 1999 service visit, a variation in temperature and salinity at a depth of approximately 30 m was apparent for most of the locations. By August 1999, a strong thermocline at most of the above locations had started to appear in the profiles at a depth of approximately 30 m, with a variation in temperature of 10 C above and below the thermocline.
Atlantic water Temperature and salinity Trend Mediterranean
2011
The paper investigates the changes in the characteristics of Atlantic Water (AW) flowing eastwards along the Egyptian coast in the southeastern Mediterranean during the period 1959-2008. Vertically, only one water mass could be observed in winter in the upper 200 m layer, whereas in summer, there were three distinct water masses. The subsurface water mass, of Atlantic origin, occupying the 50-150 m layer and characterized by low salinities from < 38.60 to 38.80 PSU, moves throughout the study area from west to east and spreads over a range of density between 27.5 and 28.5 σ t. Temperature and salinity have indicated increasing trends for both temperature and salinity during the last 25 years (1983-2008), reaching 0.85 • C decade −1 and 0.073 PSU dec −1 , respectively, for the Mediterranean surface waters. For the Atlantic water, the trends were 0.28 • C dec −1 for temperature and 0.014 PSU dec −1 for salinity.
Characteristics of the Egyptian Mediterranean water masses during the cold and warm winters
Acta Adriatica, 2007
Two winter sets of hydrographic data representing warm and cold winters for 1989 and 1990 respectively were used to study the characteristics of Egyptian Mediterranean water masses. The classification was based on the variations of air and surface water temperatures. Four water masses were observed during winter; (i) the surface water mass of temperature 17
Water mass properties and dynamic conditions of the Eastern Mediterranean in June 2007
2012
Five locations in the Eastern Mediterranean, situated in the Ionian Sea, Cretan passage and Levantine basin, were characterized for their physical and biogeochemical properties on the basis of the data collected during an oceanographic cruise in June 2007. Basinwide, subbasin and mesoscale surface dynamic features are described in terms of absolute dynamic topography of the sea surface, sea surface temperature and chlorophyll-a distribution. Additional information along the ship's track was acquired via the vessel-mounted thermosalinograph and the Acoustic Doppler Current Profiler, providing data on temperature, salinity and marine current. The latter helped identify the depth penetration (<300 m) of some dynamic structures revealed by satellite imagery. The principal water mass characteristics of the Eastern Mediterranean are described in terms of thermohaline properties and inorganic nutrient concentrations. Mixing of the principal water masses at each location was estimated by means of optimum multiparameter analysis. The June 2007 thermohaline properties are compared with those from previous studies that have described the evolution of the Eastern Mediterranean Transient from the early 1990s through the early 2000s. The processes of horizontal and vertical mixing that tend to decrease temperature and salinity of the deep waters with respect to the maximum reached during or some time after the Eastern Mediterranean Transient seem still to persist in 2007.
Long-term Variations in the Salinity off the Egyptian Mediterranean Coast
Blue Economy, 2023
The variability in seawater salinity, an indicator of the global hydrological cycle, is crucial in basin-scale circulation and many dynamic processes from basin to global scale. Salinity is significant for marine science because fluctuations in salinity can affect physical processes such as climate change, ocean current variations, and water mass formation. From a biological perspective, variations in salinity may pose a threat to marine animals and disrupt their normal functioning. In this study, the long-term variability of salinity in the photic zone (0e200 m) of the Egyptian Mediterranean Sea is examined using an extended data set from 1950 to 2021. On a monthly basis, the western sector of the Egyptian Mediterranean coast usually has lower salinity than its eastern sector. Seasonally, the maximum surface salinity was observed in autumn, while spring was the season with the lowest surface salinity variations. Positive trends in the salinity anomaly variations were found in the upper water layer (0e50 m) and then trends changed to negative patterns along the depths of 100, 150, and 200 m. Therefore, the depth of 50 m is said to divide the surface and subsurface waters with opposite trends. Future research should be undertaken based on our qualitative analysis to foresee and model the progression of salinity in the region.
Estimation of Salinity Profiles in the Southeastern Mediterranean off the Egyptian Coast
Journal of the Faculty of Marine Science (Jeddah), 2011
The main objective of the present study is the estimation of salinity profiles in the upper 500 m from measurements of temperature profiles and surface salinity in the southeastern Mediterranean off the Egyptian coast. 291 Temperature and salinity profiles were selected for this study, taken from expeditions carried out by Egypt and different countries during the period 1963-1990. Six methods were used for estimating salinity profiles in the present study. The results obtained from the climatological salinity-profile data were slightly better than the methods which were obtained by using the traditional mean salinity method. Estimated salinity profiles are able to characterize barrier layers, and regions formed by a halocline within the thermal mixed layer.
Man-Induced Salinity and Temperature Increases in Western Mediterranean Deep Water
Journal of Geophysical Research, 1992
The historical data base is used to study property changes in both the Western Mediterranean Deep Water (WMDW) and the Levantine Intermediate Water (LIW). Changes in WMDW prop- erties during the past century have been described previously, although on a more limited data base. We are not aware of any previous study of changes in LIW properties. In the extensive data base we used, increases appear in both WMDW temperature and salinity, from 1909 to the present, which substantiate previously reported observations. In addition, we find that the density of WMDW seems to have increased as well, which disagrees with previous suggestions that it has remained constant. We observe that the WMDW temperature increase displays a distinct acceler- ation starting about 1955 and that a similar, although less conspicuous, acceleration occurs in the WMDW salinity increase. From our study of historical data on LIW properties, the LIW salinity also appears to have increased since 1909. We argue that t...
Behaviour of Temperature Variations in Subsurface Layers in the South-Eastern Mediterranean Sea
ATHENS JOURNAL OF SCIENCES, 2020
The present work is a qualitative research, which aims at drawing the general behaviour of variations in the subsurface seawater temperatures within three distinctive subsurface layers in the south-eastern Mediterranean region. The work is based on hydrographic data collected over 65 years (1948–2012). The investigated layers are the subsurface, the intermediate and the deep water layers. The general trend of the mean annual temperature anomaly (MATA) was examined using the linear and quadratic regressions. Results revealed that the MATA over the water column in the south-eastern Mediterranean has the same trend, regardless of the place (layer) of investigation. Linearly, all MATA have increasing trends with different rates, with the exception of the 75 m level, which has a decreasing trend following that previously concluded for the surface water in the region. Also, the quadratic approach reflects the same trend of MATA over the water column, with different years of minimum occurr...
Scientia Marina, 2007
Time series measurements at a mooring site on the deep slope of the NW Mediterranean from October 2003 to July 2005 revealed the sequence of effects of the anomalously dry, markedly cold, and very windy winter of 2005 in deep water thermohaline properties. At the end of January, a dense water mass that was warmer and saltier than usual reached the deep slope mooring site. Almost simultaneously, the start of deep dense shelf water cascading episodes was observed in the Gulf of Lions' submarine canyons. 30 days later, colder, fresher and even denser waters reached the mooring, with a 5-day delay from an intensification of the Gulf of Lions' cascading. The signature of these waters was detected for 35 days, and by late spring 2005 a new stable water mass situation was reached, with higher thermohaline values than those that characterised the deep layer from RESUMEN: SECUENCIA DE CAMBIOS HIDROGRÁFICOS EN EL AGUA PROFUNDA DEL MEDITERRÁNEO NOROCCIDENTAL DURANTE EL EXCEPCIONAL INVIERNO DE 2005. -Una serie temporal de datos registrados en un anclaje en la parte profunda del talud continental del Mediterráneo noroccidental desde octubre de 2003 a julio de 2005 muestra la secuencia de los efectos del invierno de 2005, anómalamente seco, destacadamente frío y muy ventoso. A finales de enero una masa de agua densa, más caliente y salada de lo habitual, llegó al anclaje del talud profundo. Casi simultáneamente se observó en los cañones del Golfo de León el inicio de episodios de hundimiento profundo de agua densa de plataforma en forma de cascada. Al cabo de 30 días, 5 días después de intensificarse el hundimiento en cascada en el Golfo de León , aguas más frías, menos saladas, y todavía más densas, alcanzaron el anclaje y permanecieron allí durante 35 días. A finales de la primavera de 2005 se alcanzó un nuevo estado estacionario con valores de temperatura y salinidad más elevados que los característicos de la capa profunda desde octubre de 2003 hasta enero de 2005.