The links between the categorised Southern Oscillation indicators and climate and hydrologic variables in Turkey     

M. Çaǧatay Karabörk  Ercan Kahya 《水文研究》2009,23(13):1927-1936

Some previous global and regional studies have indicated teleconnection between the extreme phases of the Southern Oscillation (SO) and Turkish climate and hydrologic variables; however, they failed to suggest a strong correlation structure. In this study, categorised Southern Oscillation index (SOI) and Multivariate ENSO (El Nino Southern Oscillation) index (MEI) series were used to examine the far‐reaching effects of the SO on temperature, precipitation and streamflow patterns in Turkey. These SO indicators were categorised into five subgroups according to their empirical distributions. Correlations between the categorised SO indicators and three analysis variables were computed using the Spearman's rho from lag‐0 to lag‐4. Significance of calculated correlations was tested at the 0·01 level for station‐based analysis and at the 0·05 level for regional analysis. Temperature records demonstrated significant correlations with the categorised SOI and MEI in nearly half of the entire stations. For some categories, precipitation and streamflow were found to be correlated with the SO indicators in some stations mainly in western Turkey. Regional analyses of temperature and precipitation revealed a clear and strong correlation structure with the categorised SO indicators on a large portion of Turkey. This was not concluded by the earlier pertinent studies. Besides, this study showed that significant correlations were obtained not only for the SO extreme phases (namely, El Nino and La Nina) but also for neutral and moderate phases of the SO. Plausible explanations for the observed teleconnection are presented. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Analysis of the Marmara flood in Turkey, 7–10 September 2009: an assessment from hydrometeorological perspective     

Ali Ümran Kömüşcü  Seyfullah Çelik 《Natural Hazards》2013,66(2):781-808

Turkey often suffers from flood-related damages and causalities as a result of intense and prolonged storms that are usually convective or cyclonic in origin. The impact is more distinctive in Aegean and Mediterranean coasts of the country where quantity and distribution of rainfall is influenced by Mediterranean cyclones, especially in late autumn and early winter. The floods sometimes became very hazardous when combined with urbanization effects, especially in the densely populated coastal communities and major cities. Severe weather was marked in the early parts of September 2009 that produced record-setting rainfall amounts across the Marmara region of Turkey and led a series of flash floods which affected ?stanbul and Tekirda? provinces especially. The overall flooding was the result of successive and persistent intense rainfall episodes over a 3-day period which produced more than 250-mm rainfall over portions of the region. The floods resulted in death of 32 people and caused extensive environmental and infrastructural damage in the region. This study provides in-depth analysis of hydrometeorological conditions that led to the occurrence of flash floods in Marmara region during 7–10 September 2009 period and also discusses non-meteorological factors that exacerbated the flooding conditions. Main meteorological settings that led to intense storms were presence of cold air in the upper atmosphere, a slow-moving quasi-stationary trough, and continuous resupply of moisture to the surface low from the warm Aegean Sea. Radar images showed the development of clusters of convective cells that remained quasi-stationary over portions of the region. The 24-h rainfall amounts varied between 100 and 253 mm in most parts of the region during the flooding period with diverse spatial patterns. The southern locations received the highest amount of the rainfall as compared to stations located in northern slopes of the region. Typical effects of orography that enhance rainfall in the coastal areas, however, were not observed during the Marmara flood. Some features of the synoptic pattern observed prior and during the flooding period, supported the back door cold front concept. This is characterized with easterly to northeasterly surface flows forced by an anticyclone, advection of cold continental air over the warm Black Sea which provided anomalous moisture to trigger cyclogenesis over the Marmara region, and falling of core of the intense rainfall over the Marmara Sea. The study concluded that although the meteorological settings were favorable for the convective rainfalls, urbanization factors, such as land use changes and occupation of flood plains, played major role in aggravating the worst flood observed in the region in recent decades.  相似文献   

CCD photometric analysis of the W UMa-type binary V376 Andromeda     

C. Çiçek 《New Astronomy》2011,16(1):12-16

This study presents the absolute parameters of the contact binary system V376 And. CCD photometric observations were made at the Çanakkale Onsekiz Mart University Observatory in 2004. The instrumental magnitudes of all observed stars were converted into standard magnitudes. New BV light curves of the system were analysed using the Wilson–Devinney method supplemented with a Monte Carlo type algorithm. Since there are large asymmetries between maxima (i.e., O’Connell effect) in these light curves, two different models (one with a cool spot and one with a hot spot) were applied to the photometric data. The best fit, which was obtained with a large hot spot on the secondary component, gives V376 And as an A sub-type contact binary in poor thermal contact and a small value of the filling factor (f ≈ 0.07). Combining the solutions of our light curves and Rucinski et al. (2001)’s radial velocity curves, the following absolute parameters of the components were determined: M₁ = 2.44 ± 0.04 M_⊙, M₂ = 0.74 ± 0.03 M_⊙, R₁ = 2.60 ± 0.03 R_⊙, R₂ = 1.51 ± 0.02 R_⊙, L₁ = 40 ± 4 L_⊙ and L₂ = 5 ± 1 L_⊙. We also discuss the evolution of the system, which appears to have an age of 1.6 Gyr. The distance to V376 And was calculated as 230 ± 20 pc from this analysis, taking into account interstellar extinction.  相似文献   

Spectral Ratio Estimates for Site Effects on the Horst–Graben System in West Turkey     

Nİhal Akyol  Tevfİk Özgür Kurtulmuş  Murat Çamyildiz  Talİp Güngör 《Pure and Applied Geophysics》2013,170(12):2107-2125

Recordings of micro- and moderate-size local earthquakes have been used to quantify site effects in the central-west Turkey which contains one of the world’s best examples of a rapid intra-continental extension with its high population and industrial potential. We analyzed 436 earthquakes with local magnitudes ranging between 2.0 and 5.6 using three component digital recordings from 32 stations. Site functions were obtained using two different spectral ratio approaches (horizontal to vertical spectral ratio, HVSR, and standard spectral ratio, SSR). HVSR estimates of transverse and radial S-waves were compared with one another. Epicentral distance, magnitude and back-azimuth dependencies of site functions were also evaluated. In general, HVSR values from transverse and radial S-waves are similar within a factor of 2. The back-azimuth dependencies of transverse S-wave HVSR results are more significant than distance and magnitude dependencies. On the other hand, averaging of transverse and radial S-wave HVSR results eliminates systematic back-azimuth dependencies caused by source radiation effects. Distributions of HVSR estimates along ~N–S linear array, which traversed main grabens in the region with a station spacing of 3–4 km, reflect subsurface geological complexities in the region. The sites located near the basin edges are characterized by broader HVSR curves. Broad HVSR peaks could be attributed to the complexity of wave propagation related to significant 2D/3D velocity variations at the sediment–bedrock interface near the basin edges. The results also show that, even if the site is located on a horst, the presence of weathered zones along the surface could cause moderate frequency dependent site effects. Comparison of HVSR and SSR estimates for the stations on the graben sites showed that SSR estimates give larger values at lower frequencies which could be attributed to lateral variations in regional velocity and attenuation values caused by basin geometry and edge effects.  相似文献   

Digital Identification of Ecosystem Structure in the F?rt?na Valley of the Ka?kar Mountains in the Rize City of Turkey     

Cagasan KARACAOGLU  Selim Sualp CAGLAR 《山地科学学报》2014,11(2):421-428

Identifying the structure of protected mountain ecosystems is an important task for understanding conservation sustainability. The study area, the F？rt？na Valley, located in the Rize City on the Eastern Blacksea Coast, is one of the biological hotspots and a National Park of Turkey. In order to identify the structure of mountain ecosystems, we generated a GIS database for the main environmental parameters of the study area, including elevation, slope and aspect layers for topographic structure, 10 year mean values of Normalized Difference Vegetation Index（NDVI）, data for vegetation structure, annual mean temperature and precipitation layers for climatic structure, main soil groups for soil structure and stream flow accumulation, stream flow length and stream order layers for hydrological structure .To identify the complex relations among environmental factors in the study area a data reduction method is applied with Principal Component Analysis （PCA）. PCA is performed using data of 16 layers from Geographical Information Systems （GIS）. PCA analysis reduced 16 dimensions into 5 dimensions containing 75% of the variation in all data. It is also revealed that the topographic structure, mainly altitude, dominates the ecosystems of the F？rt？na Valley, but it should be considered that the interactions of environmental factors in an ecosystem dynamics are very complex. The ecosystem structure is determined by the environmental factors direct or indirect effects on energy regulation of an ecosystem. Therefore the relationship between topographic elements and other abiotic-biotic elements in the Fcrtcna Valley are important for environmental assessment and sustainability of a protected area, and these effects are explained in this study.  相似文献   

Monazite ages and the evolution of the Menderes Massif, western Turkey     

E. J. Catlos  Ibrahim Çemen 《International Journal of Earth Sciences》2005,94(2):204-217

The Menderes Massif experienced polyphase deformation, but distinguishing Pan-African events from Alpine tectono-metamorphic evolution, and discriminating Eocene–Oligocene shortening from recent extension remain controversial. To address this, monazite in garnet-bearing rocks from the massifs Gordes, Central, and Cine sections were dated in thin section (in situ) using the Th–Pb ion microprobe method. Cambro–Ordovician monazite inclusions in Cine and Central Menderes Massif garnets are ~450 m.y. older than matrix grains. Monazites in reaction with allanite from the Kuzey Detachment, which bounds the northern edge of the Central Menderes Massif, are 17±5 Ma and 4.5±1.0 Ma. The Pliocene result shows that dating of monazite can record the time of extension. The Kuzey Detachment might have exhumed rocks a lateral distance of ~53 km at a rapid rate of ~12 mm/year assuming the present ~20° ramp dip, Pliocene monazite crystallization at ~450°C, and a geothermal gradient of ~25°C/km. Assuming an angle of 60°, the rate decreases to ~5 mm/year, with the detachment surface at ~21 km depth in the Pliocene. Two Gordes Massif monazites show a similar allanite–monazite reaction relationship and are 29.6±1.1 Ma and 27.9±1.0 Ma, suggesting that the Cenozoic extension in the Gordes Massif, and possibly the entire Menderes Massif, might have begun in the Late Oligocene.  相似文献   

Pan-African high-pressure metamorphism in the Precambrian basement of the Menderes Massif, western Anatolia, Turkey     

O. Candan  O. Dora  R. Oberhänsli  M. Çetinkaplan  J. Partzsch  F. Warkus  S. Dürr 《International Journal of Earth Sciences》2001,89(4):793-811

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Deep and shallow structures of large pockmarks in the Turkish shelf, Eastern Black Sea   总被引：2，自引：1，他引：2  

Günay Çifçi  Derman Dondurur  Mustafa Ergün 《Geo-Marine Letters》2003,23(3-4):311-322

Circular and elongated pockmarks are present between 180- and 300-m water depths in the Eastern Black Sea shelf. The circular pockmarks have diameters of 50–120 m and the elongated pockmarks are 150–200 m wide with crater depths of 10–25 m. In deeper sediments, buried pockmarks were vertically stacked, indicating that the pockmarks developed under periodically varying overpressure conditions driven by the seismologically active North Anatolian Fault. Linear elongated pockmarks were formed by downslope tensional stretching, which caused linear weak zones together with strong seafloor currents acting as a connector of circular pockmarks.  相似文献   

Finger prints of the formation of geothermal springs on the granitoids: Beypazarı–Ankara, Turkey     

Sezen Diker  Mehmet Çelik  Yusuf Kağan Kadıoğlu 《Environmental Geology》2006,51(3):365-375

The Beypazarı granitoid in central Anatolia was emplaced during the Late Cretaceous and it is partly covered with Early Miocene–Quaternary sedimentary and volcanic units. Compression and tension regimes of the Beypazarı granitoid emplacing along the Sakarya River were evaluated considering the kinematical characteristics of discontinuities on granitoids, petrographic/geochemical works, formation of geothermal spring and irregularities in topographic structure. It was determined that the Beypazarı granitoid was witnessed with NE–SW compressional stress and NW–SE extensional stress which resulted in the formation of the Kapullu normal fault with N55–72°E, 78°SE crossing the Kapullu spring site. There are also several other probable normal faults around this fault in the Sakarya River basin. The results of the geochemical studies reveal that SiO₂, Na₂O, Al₂O_3, CaO and K₂O as a major oxide and As, Rb, Sr, Th and U as trace elements are decreased away from the Kapullu bath spring. On the other hand, the ratio of Fe₂O₃ and MgO as major oxide and Y as a trace element with the lost on ignition (LOI) are increased away from the Kapullu fault. Regard as the regional plate tectonism, there is a consistency between the direction of compression in the Beypazarı granitoid and that developed by the southwesterly movement of the Anatolian plate.  相似文献   

Hydrochemical evaluation of groundwater quality in the Çavuşçayı basin, Sungurlu-Çorum, Turkey     

Mehmet Çelik  Turgut Yıldırım 《Environmental Geology》2006,50(3):323-330

The purpose of this study is to investigate the quality and usage possibility of groundwater in the Çavuşçayı basin and suggest the best water structure for the groundwater use. Results from hydrochemical analyses reveal that groundwater is mostly affected by salty (Na⁺–Cl⁻) waters of the Incik Formation and brackish (Ca²⁺, Mg²⁺–SO ₄ ²⁻ ) waters of the Bayındır Formation. The Alibaba saltpan discharged (2 l/s) from the Incik Formation is used for salt production. In the basin, salinity risk increases with depth and along the groundwater flow direction. Therefore, shallow water and trenches opened in the alluvium aquifer at the east of the basin were determined to yield suitable water with no Na⁺ and Cl⁻ contamination. Following the heavy rainy period, waters of less salinity and conductivity are possibly used for agriculture.  相似文献