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Takvor H. Soukissian Aristides M. Prospathopoulos Chrysoula Diamanti 《Journal of Atmospheric & Ocean Science》2002,8(2):163-189
In this paper, a statistical analysis on wind and wave buoy measurements and wind and wave model forecasts obtained during a two-year period (1999-2001) is presented with reference to four characteristic near-shore sites of the Aegean Sea. The measurements are a main product of the "POSEIDON" system aiming at the monitoring and forecasting of the state of the Greek seas, operated by the National Centre for Marine Research (NCMR). Although the two-year period is rather short for a thorough analysis of the local wind and wave climate, yet the obtained results, presented herein for the first time, reveal some interesting features of the corresponding wave and wind characteristics. Comparisons between the measurements and the forecast results are also performed at the locations under consideration. It is found that (i) wind speeds obtained from the POSEIDON weather forecasting system are, in general, in agreement with the measurements, except for high wind speeds which are systematically underestimated, (ii) the WAM model can successfully follow the monthly and over year trend of the evolution of wind and wave characteristics, but face significant problems for efficient sea-state forecasting. Finally, the overall pattern of the wind/wave climate for the entire Aegean Sea as obtained from the models is presented by means of the spatial distribution of the mean annual wind and sea-state intensity. 相似文献
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Lake Koronia, a Ramsar site, is shallow, polymictic, hypertrophic and until recently was aerially the fourth largest lake in Greece. Although exceeding 5 m in the past, lake depth has declined progressively from 3.8 m in 1980 to < 1 m in 1997, reducing surface area and water volume by 50% and 80%, respectively. Specific conductivityincreased from 1300 μS cm−1 in 1977 to >6000 μS cm−1 in 1991. Increased phosphate concentrations from the late 1970's (8–45 μg L−1) to the late 1990's (100–1000 μg L−1) document that the previously eutrophic system with a limited littoral zone switched to hypertrophy dominated by massive cyanobacteria blooms. Oxygen saturation of the water column increased progressively from about 80% in 1983 to full saturation about 1993, after which it decreased progressively to only 20% saturation in 1997. In spite of cyanobacteria dominance, community metabolism of the lake switched from progressively increasing autotrophy to rapidly advancing heterotrophy associated with progressive water-level reduction leading to fish extirpation in the lake. 相似文献
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Simulation of seismic response in a city-like environment 总被引：1，自引：0，他引：1
Jean-Philippe Groby Chrysoula Tsogka Armand Wirgin 《Soil Dynamics and Earthquake Engineering》2005,25(7-10):487-504
We study the seismic response of idealized 2D cities, constituted by non-equally spaced, non-equally sized homogenized blocks anchored in a soft layer overlying a hard half space. The blocks and soft layer are occupied by dissipative media. To simulate such response, we use an approximation of the viscoelastic modulus by a low-order rational function of frequency and incorporate this approximation into a first-order-in-time scheme. Our results display spatially variable, strong, long-duration responses inside the blocks and on the ground, which qualitatively match the responses observed in some earthquake-prone cities of Mexico, France, the USA, etc. 相似文献
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We study the seismic response of an idealized 2D ‘city’, constituted by ten non equally-spaced, non equally-sized, homogenized blocks (i.e. buildings or groups of buildings) anchored in a soft soil layer overlying a hard halfspace. Our results display strong response inside the blocks and on the ground which qualitatively match the responses observed in some earthquake-prone cities. 相似文献
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Chrysoula Christia Eva Papastergiadou George Papatheodorou Maria Geraga Emmanouil Papadakis 《Environmental Earth Sciences》2014,71(8):3543-3558
Temporal and spatial variations of environmental and water quality parameters and their relations with macrobenthic flora were investigated in an eastern Mediterranean lagoon. Kaiafas is a mesohaline lagoon, which is influenced by point and diffused sources from the adjacent agricultural land and the nearby city. Water samples were analyzed for physicochemical parameters, microbial load and primary production, on a seasonal and spatial scale, while heavy metal concentrations were measured into two different sediment cores. An overall analysis of seasonal dynamics of water parameters and Chl-a based on trophic index TSI pointed out the lagoon as eutrophic. According to water quality parameters the lagoon was separated into two parts. The southern sector of the lagoon which was more affected by human activities showed higher nutrients, Chl-a, heavy metals and total Coliforms concentrations. Sediment texture and distribution of macrophytes were detected through the acoustic side scan sonar method, which proved to be a promising tool for defining and monitoring vegetation coverage of shallow lagoons. A number of distinct echo types and three different sediment types were revealed on the basis of the backscatter level and the variability of low and high backscatter areas. Furthermore, the extension and the coverage of Potamogeton pectinatus and Chara hispida f. corfuensis were successively depicted by combining the data of SSS and ground truthing samples. Meadows of P. pectinatus were established to the lagoon limits where high turbidity and silty substrate occurred, while C. hispida f. corfuensis was limited in deep and high transparent waters with sandy substrate. 相似文献
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Eleni Terzi Chrysoula Anatolaki Constantini Samara Roxani Tsitouridou 《Journal of Atmospheric Chemistry》2008,59(3):171-186
Ambient suspended particles (TSP) were collected from January to June 2001 at seven sampling sites in western Macedonia, Greece,
where four thermal power stations are located. TSP samples were chemically characterized for minerals (Fe, Al, Mg, Ca, K,
Ti and Si), trace elements (P, Cd, Cr, Cu, Mn, Pb, V, Zn, Te, Co, Ni, Se, Sr, As, and Sb), water-soluble ions , carbonaceous compounds (OC/EC) and polycyclic aromatic hydrocarbons (PAHs). These classes of compounds were consequently
compared with PM mass concentrations of TSP in order to perform mass closure. PM chemical compositions exhibited differences
at the seven sites. Minerals were found to be more abundant at four sites, electrolytes dominated the composition at two of
the sites while carbonaceous material was most abundant only at one site. The fraction unaccounted for ranged between 22 and
34%. Spatial variations of atmospheric concentrations showed significantly higher levels of minerals, some trace metals and
TC at the site that was closest to the power plants. At the same site ions exhibited high correlations with minerals and the
majority of trace elements. 相似文献
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