scholarly journals PALAEOCLIMATIC AND PALAEOCEANOGRAPHIC EVOLUTION OF THE MEDITERRANEAN SEA OVER THE LAST 18KA

2017 ◽  
Vol 43 (2) ◽  
pp. 1064
Author(s):  
K. Thomopoulos ◽  
M. Geraga ◽  
E. Fakiris ◽  
G. Papatheodorou ◽  
G. Ferentinos

he aim of the present study is the reconstruction of the palaeoclimatic and palaeoceanographic evaluation of the Mediterranean Sea over the last 18ka based on the distribution of the planktonic foraminifera species. Planktonic foraminifera species have been proven excellent indicators of the palaeoclimatic and palaeoceanographic variability. The data set of the present study consists of the variability in the abundances of planktonic foraminifera species as has been reported and published in previous studies, after the examination of marine sediments from cores selected all over the Mediterranean Sea. The evolution in the abundance of each planktonic species is examined on a time interval spacing of 1000years suggesting implications for the palaeoclimatic and palaeoceanographic evolution of the Mediterranean Sea for the same time sampling interval (1000yrs). The most pronounced results of this study suggest that: (i) the increase in surface temperature during the warm intervals always follow a decreasing trend from eastern to western areas, (ii) the eutrophication of the Mediterranean Sea in most of the time exhibits a decreasing trend from northern to southern areas, and (iii) during the Holocene two cool spells (at around 8ka and 4ka) seems that had affected the majority of the Mediterranean region.

2020 ◽  
Author(s):  
Iuliana Vasiliev ◽  
Daniela Boehn ◽  
Darja Volkovskaja ◽  
Clemens Schmitt ◽  
Konstantina Agiadi ◽  
...  

<p>Between 5.97-5.33 Ma several kilometre-thick evaporite units were deposited in the Mediterranean Basin during the Messinian Salinity Crisis (MSC). The MSC reflects a period featured by a negative hydrological budget, with a net evaporative loss of water exceeding precipitation and riverine runoff. The contemporary changes in continental and marine circum-Mediterranean temperature are, however, poorly constrained. Here we reconstruct continental mean annual temperatures (MAT) using branched glycerol dialkyl glycerol tetraether (GDGT) biomarkers for the time period corresponding to MSC Stage 3 (5.55-5.33 Ma). Additionally, for the same time interval, we estimate sea surface temperatures (SSTs) of the Mediterranean Sea using isoprenoidal GDGTs based TEX<sub>86</sub> proxy. The excellently preserved organic biomarkers were extracted from outcrops and DSDP cores spread over a large part of the onland (Malaga, Sicily, Cyprus) and offshore (holes 124 and 134 from the Balearic abyssal plane and hole 374 from the Ionian Basin) Mediterranean Basin domain. The calculated MATs for the 5.55 to 5.33 Ma interval show values around 16 to 18 ºC for the Malaga, Sicily and Cyprus outcrops. The MAT values calculated for DSDP Leg 13 holes 124, 134 and Leg 42A hole 374 are lower, around 11 to 13 ºC.</p><p>For samples where the branched and isoprenoid tetraether (BIT) index was lower than the 0.4 we could calculate TEX<sub>86</sub> derived SSTs averaging around 27 ºC for all sampled locations. Where available (i.e. Sicily), we compared the TEX<sub>86</sub> derived SSTs with alkenone based, U<sup>k</sup><sub>37</sub> derived SST estimates from the same samples. The TEX<sub>86</sub> derived SST values are slightly higher than the U<sup>k</sup><sub>37</sub> derived SST of 20 to 28 ºC. For the Mediterranean region, values between 19 and 27 ºC of the U<sup>k</sup><sub>37</sub> derived SSTs were calculated for the interval between the 8.0 and 6.4 Ma (Tzanova et al., 2015), close to our calculations for Sicily section (20 to 28 ºC). Independent of common pitfalls that may arise in using molecular biomarkers as temperature proxies, both SST estimates independently hint towards much warmer Mediterranean Sea water during the latest phase (Stage 3) of the MSC. These elevated temperatures coincide with higher δD values measured on alkenones and long chain n-alkanes (both records indicating for more arid and/or warmer conditions than today between 5.55 and 5.33 Ma). We therefore conclude that the climate between 5.55 to 5.33 Ma was warmer than present-day conditions, recorded both in the Mediterranean Sea and the land surrounding it.</p>


2003 ◽  
Vol 21 (1) ◽  
pp. 205-220 ◽  
Author(s):  
G. Korres ◽  
A. Lascaratos

Abstract. The present study deals with the implementation of an eddy resolving model of the Levantine and Aegean basins and its one-way nesting with a coarse resolution (1/8° × 1/8°) global Mediterranean general circulation model. The modelling effort is done within the framework of the Mediterranean Forecasting System Pilot Project as an initiative towards real-time forecasting within the eastern Mediterranean region. The performed climatological runs of the nested model have shown very promising results on the ability of the model to capture correctly the complex dynamics of the area and at the same time to demonstrate the skill and robustness of the nesting technique applied. A second aim of this study is to prepare a comprehensive climatological surface boundary conditions data set for the Mediterranean Sea. This data set has been developed within the framework of the same research project and is suitable for use in ocean circulation models of the Mediterranean Sea or parts of it. The computation is based on the ECMWF 6-h atmospheric parameters for the period 1979–1993 and a calibrated set of momentum and heat flux bulk formulae resulted from previous studies for the Mediterranean region. Key words. Oceanography: general (numerical modelling); physical (general circulation; air-sea interactions)


Ocean Science ◽  
2013 ◽  
Vol 9 (2) ◽  
pp. 301-324 ◽  
Author(s):  
K. Schroeder ◽  
C. Millot ◽  
L. Bengara ◽  
S. Ben Ismail ◽  
M. Bensi ◽  
...  

Abstract. The long-term monitoring of basic hydrological parameters (temperature and salinity), collected as time series with adequate temporal resolution (i.e. with a sampling interval allowing the resolution of all important timescales) in key places of the Mediterranean Sea (straits and channels, zones of dense water formation, deep parts of the basins), constitute a priority in the context of global changes. This led CIESM (The Mediterranean Science Commission) to support, since 2002, the HYDROCHANGES programme (http//www.ciesm.org/marine/programs/hydrochanges.htm), a network of autonomous conductivity, temperature, and depth (CTD) sensors, deployed on mainly short and easily manageable subsurface moorings, within the core of a certain water mass. The HYDROCHANGES strategy is twofold and develops on different scales. To get information about long-term changes of hydrological characteristics, long time series are needed. But before these series are long enough they allow the detection of links between them at shorter timescales that may provide extremely valuable information about the functioning of the Mediterranean Sea. The aim of this paper is to present the history of the programme and the current set-up of the network (monitored sites, involved groups) as well as to provide for the first time an overview of all the time series collected under the HYDROCHANGES umbrella, discussing the results obtained thanks to the programme.


Author(s):  
Sarah Davis-Secord

Sicily is a lush and culturally rich island at the center of the Mediterranean Sea. Throughout its history, the island has been conquered and colonized by successive waves of peoples from across the Mediterranean region. In the early and central Middle Ages, the island was ruled and occupied in turn by Greek Christians, Muslims, and Latin Christians. This book investigates Sicily's place within the religious, diplomatic, military, commercial, and intellectual networks of the Mediterranean by tracing the patterns of travel, trade, and communication among Christians (Latin and Greek), Muslims, and Jews. By looking at the island across this long expanse of time and during the periods of transition from one dominant culture to another, the book uncovers the patterns that defined and redefined the broader Muslim–Christian encounter in the Middle Ages. Sicily was a nexus for cross-cultural communication not because of its geographical placement at the center of the Mediterranean but because of the specific roles the island played in a variety of travel and trade networks in the Mediterranean region.


2008 ◽  
Vol 112 (8) ◽  
pp. 3300-3313 ◽  
Author(s):  
Vittorio Barale ◽  
Jean-Michel Jaquet ◽  
Mapathé Ndiaye

2011 ◽  
Vol 8 (5) ◽  
pp. 8961-8998 ◽  
Author(s):  
Y. Cuypers ◽  
P. Bouruet-Aubertot ◽  
C. Marec ◽  
J.-L. Fuda

Abstract. One main purpose of BOUM experiment was to give evidence of the possible impact of submesoscale dynamics on biogeochemical cycles. To this aim physical as well as biogeochemical data were collected along a zonal transect through the western and eastern basins. Along this transect 3 day fixed point stations were performed within anticyclonic eddies during which microstructure measurements were collected over the first 100 m. We focus here on the characterization of turbulent mixing induced by internal wave breaking. The analysis of microstructure measurements revealed a high level of turbulence in the seasonal pycnocline and a moderate level below with energy dissipation mean values of the order of 10−6 W kg−1 and 10−8 W kg−1, respectively. Fine-scale parameterizations developed to mimic energy dissipation produced by internal wavebreaking were then tested against these direct measurements. Once validated a parameterization has been applied to infer energy dissipation and mixing over the whole data set, thus providing an overview over a latitudinal section of the Mediterranean sea. The results evidence a significant increase of dissipation at the top and base of eddies associated with strong near inertial waves. Vertical turbulent diffusivity is increased both in these regions and in the weakly stratified eddy core.


2014 ◽  
Vol 2 (4) ◽  
pp. 2813-2849
Author(s):  
I. Marchesini ◽  
F. Ardizzone ◽  
M. Alvioli ◽  
M. Rossi ◽  
F. Guzzetti

Abstract. We used landslide information for 13 study areas in Italy and morphometric information obtained from the 3 arc-second SRTM DEM to determine areas where landslide susceptibility is expected to be null or negligible in Italy, and in the landmasses surrounding the Mediterranean Sea. The morphometric information consisted in the local terrain slope computed in a square 3 × 3 cell moving window, and in the regional relative relief computed in a circular 15 × 15 cell moving window. We tested three different models to determine the non-susceptible landslide areas, including a linear model (LR), a quantile linear model (QLR), and a quantile non-linear model (QNL). We tested the performance of the three models using independent landslide information represented by the Italian Landslide Inventory (Inventario Fenomeni Franosi in Italia – IFFI). Best results were obtained using the QNL model. The corresponding zonation of non-susceptible landslide areas was intersected in a GIS with geographical census data for Italy. The result allowed determining that 57.5% of the population of Italy (in 2001) was located in areas where landslide susceptibility is expected to be null or negligible, and that the remaining 42.5% was located in areas where some landslide susceptibility is expected. We applied the QNL model to the landmasses surrounding the Mediterranean Sea, and we tested the synoptic non-susceptibility zonation using independent landslide information for three study areas in Spain. Results proved that the QNL model was capable of determining where landslide susceptibility is expected to be negligible in the Mediterranean area. We expect our results to be applicable in similar study areas, facilitating the identification of non-susceptible and susceptible landslide areas, at the synoptic scale.


Sign in / Sign up

Export Citation Format

Share Document