排序方式： 共有6条查询结果，搜索用时 15 毫秒
1
1.
Stylianos Bitharis Christos Pikridas Aristeidis Fotiou Dimitrios Rossikopoulos Harald Schuh 《Marine Geodesy》2017,40(5):297-314
In this study, we show how the Global Navigation Satellite System (GNSS)-derived vertical velocities contribute to the correction of tide gauge (TG) measurements used for the sea level rise estimation in Greece. Twelve sites with records of local sea level heights are processed in order to estimate their trend. Certain error sources related to TGs, e.g. equipment changes, data noise, may lead to biased or erroneous estimations of the sea level height. Therefore, it would be preferred to follow a robust estimation technique in order to detect and reduce outlier effects. The geocentric sea level rise is estimated by taking into account the land vertical motion of co-located GNSS permanent stations at the Hellenic area. TGs measure the height of the water relative to a monitored geodetic benchmark on land. On the other hand, using GNSS-based methods the vertical land motion can be derived. By means of extended models fitted to the GNSS time-series position, obtained from seven years of continuous data analysis, periodic signals are well described. The synergy of the two co-located techniques results in the correction of TG relative sea level heights taking into account the GNSS vertical velocities and consequently obtaining the conversion to absolute (geocentric) sea level trend. 相似文献
2.
This study analyzes the flash flood event of two ungauged ephemeral streams in Olympiada region (Chalkidiki, North Greece), which occurred at the 21–22 of November 2019. Aim of the study is to reconstruct the specific flash flood event, investigate the causes of flood generation mechanisms, evaluate the performance of SCS-CN hydrological and HEC-RAS hydraulic models, investigate the relation between extreme flash floods and human intervention, using the combination of ground and aerial observations obtained from the field survey and unmanned aerial vehicles (UAVs), respectively. The results of the specific discharge ranged between 9 and 11 m3 s−1 km2, values that are typical for flash flood events in Mediterranean region. The comparison between the observed and simulated values of flood extent showed sufficiently good performance of the hydraulic model (CSI = 82%). However, the statistical analysis of the observed and simulated flood depths displayed a flood depth overestimation by the applied model, despite that the values of the used statistic indexes are acceptable (RMSE = 0.35 m, SD = 0.53, NSE = 0.56, PBIAS = 11.26%). The model overestimation of flood depth was attributed to the DEM low resolution and quality. Ground and aerial observations depicted the alluvial fan activation, the alternation of flow paths and the huge sediment transport. Human intervention in main streams, urban sprawl, wet AMC and sediment transport were among the main factors that contributed to the flash flood generation. This integrated approach revealed the necessity of the constant evaluation and validation of hydrological and hydraulic models in small ungauged Mediterranean watersheds and ephemeral streams. The use of UAVs in combination with ground observations and hydraulic simulation could significantly contribute to the enhanced understanding of flash flood mechanisms, in the direction of flood risk mitigation, improvement of the planning efficiency of flood prevent measures, flood hazard estimation, evolution of flood warning systems and floodplain geomorphology analysis. 相似文献
3.
Summer tourism is one of the most important contributors to the European GDP especially for the southern countries and is highly dependent on the climatic conditions. Changes in average climatic conditions, along with the potential subsequent changes in the physical environment, will pose stress on the favorability of the climate of European destinations for tourism and recreational activities. Here, we study the vulnerability of summer-oriented tourism due to a global temperature increase by 2 °C relative to the preindustrial era. We use a well-defined framework of exposure, sensitivity, and adaptive capacity indicators for a set of plausible climate (RCPs) and socioeconomic (SSPs) combinations. Our result shows that a 2 °C global warming will pose substantial changes to the vulnerability of the European tourism sector. Despite the general increase in exposure, the vulnerability of summer tourism is highly depended on the socioeconomic developments (SSPs). Although exposure is higher for most of the popular southern European destinations like Spain, France, South Italy, southernmost Greece, and Cyprus, they are expected to be less vulnerable than others, under specific SSPs, due to their higher capacity to adapt to a different climate. The capacity to adapt is lower for higher emission scenarios. Substantial changes are also apparent at the subnational level. Countries like France are foreseen to experience very diverse impacts and vulnerabilities within their own territories that will have consequences in terms of domestic tourism. The dynamics of these changes are expected to alter the state of the current European tourism regime. 相似文献
4.
Severe climate-induced water shortage and extremes in Crete 总被引：1，自引：0，他引：1
Ioannis K. Tsanis Aristeidis G. Koutroulis Ioannis N. Daliakopoulos Daniela Jacob 《Climatic change》2011,106(4):667-677
Climate change is expected to have a significant impact on the hydrologic cycle, creating changes in freshwater resources.
The Intergovernmental Panel on Climate Change (IPCC) predicts that, as a result, floods and prolonged droughts will take place
at increasingly frequent periods. The Mediterranean has been described as one of the main climate change “hot-spots”, with
recent simulations showing a collective picture of substantial drying and warming. This effect appears more pronounced during
warm periods, when the seasonal decrease of precipitation can exceed control climatology by 25–30%. Despite the decreasing
annual rainfall trend, an increase in the amount and intensity of wintertime rainfall is evident. However, the scientific
question on the quantitative impact of these signals to small scale coastal watersheds and Mediterranean islands has not been
answered. The state-of-the-art Ensembles dataset was employed to assess the impact of the changing climate on the water availability
of the island of Crete at basin scale. Here, the Ensembles precipitation and temperature data is used as input for a rainfall–runoff
model previous calibrated for the whole island with the principle of regionalization. Data analysis for the period 1970–2100
reveals an overall decreasing precipitation trend which, combined with a temperature rise, leads to substantial reduction
of water availability. Quantitative results of hydrological change provide the data required to improve knowledge and adaptation
policy to water shortages. 相似文献
5.
6.
Xiaoyue Cao Ran Li J.W.Nightingale Richard Massey Andrew Robertson Carlos S.Frenk Aristeidis Amvrosiadis Nicola C.Amorisco Qiuhan He Amy Etherington Shaun Cole Kai Zhu 《天文和天体物理学研究(英文版)》2022,(2):143-172
The elliptical power-law model of the mass in a galaxy is widely used in strong gravitational lensing analyses.However,the distribution of mass in real galaxies... 相似文献
1