Benthic foraminifer palaeoecology of the Late Quaternary continental outer shelf of a landlocked marine basin in central Aegean Sea, Greece

Deep water mass characteristics and interannual variability in the North and Central Aegean Sea

Living and dead benthic foraminifers were studied in four samples collected at depths of 40, 60, 80, and 100 m in the Gullmarn fjord on April 2, 1992, with the purpose of charting differences in assemblage composition among the samples in relation to hydrographic and environmental factors. It is suggested that the relatively high abundance of dead foraminifers found at 40 m may be due to postmortem transportation and redeposition of the microbenthos by currents generated by the frequent water exchange of the intermediate water mass. The diversity of living foraminifers was slightly but distinctly lower in the two deeper samples probably partly as a consequence of the lower oxygen content and food supply in the deeper water mass of the fjord during the winter months. Nyberg, J. & Majoran, S., 1995: Benthic foraminifers of the intermediate and bottom water masses of the Gullmarn fjord (SW Sweden) in early April 1992. GFF, Vol. 117 (Pt. 4, December), pp. 211–214. Stockholm. ISSN 1103–5897.

Climatic forcing of eastern Mediterranean deep-water formation and benthic ecosystems during the past 22 000 years

Radiocarbon-dated benthonic foraminiferal zones in three cores provide new information on the evolution of the deep and intermediate water masses off Gaspé Peninsula. The deglacial phase in the deep Laurentian Channel began before 14 000 BP and was characterized by low-salinity (<20‰) or alternating low-salinity and saline (~35‰) water. This was followed by a cold saline phase, which ended ca. 13 500 BP, and a salinity minimum (30–33.5‰), which began ca. 12 100 BP. Between 8700 and 7900 BP, the temperature and salinity of the deep water mass increased, resulting in the modern deep water mass (temperature 4–6 °C, salinity 34.5–34.9‰) at the end of the Goldthwait Sea episode. The salinity of the deep water was apparently controlled by the meltwater flux from the ice front during the deglacial phase. After the deglacial phase the characteristics of the deep water mass were determined by the composition of offshore water entering the Laurentian Channel. Runoff from the Lake Agassiz – Great Lakes system does not appear to have mixed with the deep water of the Goldthwait Sea. The deglacial phase in Chaleur Trough, which is within the intermediate water mass, began before 12 200 BP. The temperature of the intermediate water mass has remained close to 0 °C after deglaciation; however, the salinity has increased from 25–30‰ at 12 200 BP to about 33.5‰ by 5900 BP.

Changes in Pacific Ocean circulation following the Miocene onset of permanent Antarctic ice cover

Gaseous species and aerosol size distribution and chemical composition within the boundary layer during the Etesians is investigated, based upon airborne measurements, over the Aegean Sea, from Crete to Limnos islands (29/8–8/9 2011, Aircraft_BAe146–FAAM). Three flights of a similar route covered the eastern and western parts of the Aegean Sea. Two flights were performed on the same day to study the impact of the diurnal cycle. The sorties involved horizontal tracks mainly at 150 m a.s.l. and above the aerosol layer, at 2.5 km a.s.l., and profiles up to 4.5 km near the ground stations of Crete and Limnos and the Central Aegean Sea. Marked variations were detected in the vertical structure of aerosols and thermodynamic variables between the eastern and western segments flown around the Aegean. Several discrete aerosol layers, separated by a clean slot, containing particles of different chemical composition were observed, with sulfates and organics being the dominant components. CO concentrations ranged from 80 ppb above the mixing layer, up to 140 ppb near the surface. O3 ranged between 50 and 75 ppb, with higher values observed at surface upwind of Finokalia and in the mixing layer in Central and Northern Aegean Sea.

Stable isotopic composition of Holocene benthic foraminifers from the Eastern Mediterranean Sea: Past changes in productivity and deep water oxygenation

More records on the tripletail, Lobotes surinamensis (Bloch, 1790) from the Aegean Sea

The intra-annual variation and the spatial distribution of lightning activity over Greece is studied for the 10-year period 2005–14, on a 15-day basis, using Zeus 0.5° × 0.5° data. Factor Analysis (S-mode and T-mode) is applied to the average lightning activity for each fortnight of the year and for each grid box, for the studied period. (i) For the intra-annual variation of lightning activity, 3 sub-regions are defined, presenting characteristic modes of variation: In the first one, over the mainland, a broad maximum appears during late spring–early summer; in the second, mainly over the Ionian Sea, a maximum is seen during early autumn; while in the third, mainly over the central and south Aegean Sea, two maxima are found, one in middle autumn and another in late May. (ii) For the spatial distribution of lightning activity, 4 main patterns are revealed: the ‘summer’ pattern (1/5–15/8), characterized by a maximum over the mainland; the ‘autumn’ pattern (1/9–15/10), with maxima over the north Ionian Sea and the north Aegean Sea; the ‘winter’ pattern (15/12–15/2), with maxima over the south Ionian Sea and Dodecanese Islands; and a low variance ‘transitional’ pattern (1/4–30/4 and 1/12–15/12), with maximum over the central Aegean Sea.

The seasonal and interannual variability of the local hydrography in 3 bays (Saros, Izmir, and Gokova bays) along the eastern coast of the Aegean Sea are investigated using data sets collected from 1991 to 2010. The data cover the last major deep-water formation episodes and the Eastern Mediterranean Transient (EMT) relaxation period. Aegean Sea hydrology and water mass characteristics influence the water properties of the bays. The data suggest that Saros Bay (North Aegean Sea), Izmir Bay (Central Aegean Sea), and Gokova Bay (South Aegean Sea) have different physical processes and water characteristics. They have their own dynamics independent from the Aegean Sea. At the same time, they are occasionally influenced by the Aegean Sea's physical processes. The time evolution of water properties inside the bays is investigated by analyzing the temperature, salinity, and density. The bays' data show the relaxation period of the EMT, which continued well into the early 2000s. It is known that this variability depends on the changing climate over the Mediterranean area. Our analysis reveals that the dense water formation in the Central Aegean Sea is considerably connected to the anomalous decrease in winter atmospheric temperature during the EMT period. The isopycnal levels started to increase again and reached their maximum after the EMT relaxation period in the summer of 2007 together with a salinity increase in the water column. The outcropping of isopycnals could have been a sign of a new formation of very dense water in the Aegean Sea.

<p>We present an analysis of specific water masses fluxes in the Western Mediterranean Sea issued from a twenty years (1992-2013) reanalysis (MEDRYS1V2). Water masses are identified on the base of salinity and potential density properties and computes; the fractions of each water mass involved in total flux are computed under the hypothesis assumptions of mixing lines schemes. It was first designed in order to avoid rough truncations between water masses on the T-S diagram when using fixed thermo-haline properties thresholds. The method does not use the temperature marker due to its high seasonal variability in near surface waters (0-200 m) and we consider that potential density is a better marker to discriminate deep and intermediate water masses. The algorithm discriminates successively five different water masses : the Atlantic Water (AW) incoming from the Gibraltar strait (salinity between 36,1 and 38,45 PSU), the Levantine Intermediate Waters (LIW) incoming from the Tunisia-Sicily strait (salinity between 38,45 and 39.1 PSU), the Modified Atlantic Waters (MAW) defined as near-surface waters (potential density less than 28,9 kg m-3) that are neither AW or LIW, while Western Intermediate Waters (WIW) are those remaining until the σθ = 29,10 kg m-3 threshold for Western Mediterranean Deep Waters (WMDW) is reached. Such computed fractions of each water mass, whose sum is constrained to unity, are then used to compute their water masses transports all along over twenty years of the reanalysis. The transport are assessed across computed on key transects delimiting known sub-basin entities (Ligurian Sea, Gulf of Lion, Balearic Sea...), with total transports showing balanced mass budget. The such computed total transport reveal marked differences in their seasonal to interannual variability, while the analysis of the water mass transports allows to identify those which mainly implied induced these variability. The results first show a low seasonal and no significant interannual variability at the exit of the Alboran Sea that results from the balance between the eastward AW/MAW outflow and the westward WIW and WMDW inflows. The Corsican strait, the Ligurian Sea line and Tunisia-Sardinia straits show a marked seasonal variability (0,37-0,39 Sv) mainly driven by the AW/MAW. By contrast, a strong interannual variability dominates the seasonal one (-2 to 1 Sv) between the Algerian Basin and the northern basin, correlated to the WMDW formation. The analysis of each specific water masses transport pointed out that shows this marked variability to be first driven by the intermediate and deep water masses transports. Similarly the interannual variability of the AW and MAW transports in the central part of the Western Mediterranean suggests some coupling between the deep, intermediate and surface water masses, even through the shallower Balearic Sea.</p>

Late Quaternary micropalaeontological record of a semi-enclosed marine basin, North Evoikos, central Aegean Sea

The evolution of deepwater dissolved oxygen in the northern South China Sea since 400 ka

Late quaternary benthic foraminifera and deep-water paleoceanography in the South China Sea

North–Central Aegean Sea surface and intermediate water masses and their role in triggering the Eastern Mediterranean Transient