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Yayın Akdağ Kütlesi’nde (Batı Toroslar) Pleistosen buzullaşmalarının jeomorfolojik özellikleri ve optik uyarmalı lüminesans (OSL) ile yaşlandırılması(Türk Coğrafya Kurumu, 2017) Bayrakdar, Cihan; Güneç Kıyak, Nafiye; Turoğlu, Hüseyin; Öztürk, Tuğba; Canel, TimurBatı Torosların en yüksek ikinci zirvesine (Uyluk T. 3014 m) sahip olan Akdağ, batıda Eşen Ovası (60 m) doğuda Elmalı Ovası (1100 m) arasında yer alan ve 2700 m üzerinde birçok zirve barındıran, çevresine göre oldukça yüksek bir kütle görünümündedir. Akdağ Kütlesi'nde Kuvaterner'de meydana gelen buzul şekillerini incelemek ve OSL ile tarihlendirmek çalışmanın temel amacıdır. Bu çalışmada coğrafi bilgi sistemleri ve morfometrik analizler, OSL tarihlendirme yöntemi ve sedimantolojik analizlerden faydalanılmıştır. Akdağ Kütlesi'nin jeomorfolojik gelişiminde birden fazla etken ve sürecin rolü olmuştur. Bu süreçlerin başında karst, buzul, tektonik ve flüviyal gelmektedir. Akdağ Kütlesi'nde etkili olan Pleistosen buzullaşmaları, büyük ölçüde karstik yapıya uyumlu gelişmiş ve 2500 m ve üzerindeki paleo-karstik depresyonlarda kalın plato buzulları oluşmuştur. Akdağ Kütlesi'nde üçü büyük, beş buzul vadisi tespit edilmiştir. Bu buzul vadileri gelişmiş sirklerle başlayıp 2500 m seviyelerinde paleokarstik depresyonlara uyumlu olarak düşük eğimli, geniştabanlı ve büyük ölçüde taban ve yanal morenleri ile kaplı iken 2500 m seviyelerinden sonra vadiler daralıp klasik tekne vadi formu alıp 2000 m seviyelerinde cephe morenleri ile sonlanırlar. Akdağ Kütlesi'nde morenlerden alınan örneklere ait OSL tarihlendirmelerinde 17-21 bin yaşları çıkmıştır ki bu da son buzul dönemi MIS 2 ye denk gelmektedir.Yayın Quaternary uplift of the northern margin of the Central Anatolian Plateau: New OSL dates of fluvial and delta-terrace deposits of the Kizilirmak River, Black Sea coast, Turkey(Pergamon-Elsevier Science Ltd, 2018-12-01) Berndt, Christopher; Yıldırım, Cengiz; Çiner, Tahsin Attila; Strecker, Manfred R.; Ertunç, Gülgün; Sarıkaya, Mehmet Akif; Özcan, Orkan; Öztürk, Tuğba; Güneç Kıyak, NafiyeWe analysed the interplay between coastal uplift, sea level change in the Black Sea, and incision of the Kizilirmak River in northern Turkey. These processes have created multiple co-genetic fluvial and marine terrace sequences that serve as excellent strain markers to assess the ongoing evolution of the Pontide orogenic wedge and the growth of the northern margin of the Central Anatolian Plateau. We used high-resolution topographic data, OSL ages, and published information on past sea levels to analyse the spatiotemporal evolution of these terraces; we derived a regional uplift model for the northward advancing orogenic wedge that supports the notion of laterally variable uplift rates along the flanks of the Pontides. The best-fit uplift model defines a constant long-term uplift rate of 0.28 +/- 0.07 m/ka for the last 545 ka. This model explains the evolution of the terrace sequence in light of active tectonic processes and superposed cycles of climate-controlled sea-level change. Our new data reveal regional uplift characteristics that are comparable to the inner sectors of the Central Pontides; accordingly, the rate of uplift diminishes with increasing distance from the main strand of the restraining bend of the North Anatolian Fault Zone (NAFZ). This spatial relationship between the regional impact of the restraining bend of the NAFZ and uplift of the Pontide wedge thus suggests a strong link between the activity of the NAFZ, deformation and uplift in the Pontide orogenic wedge, and the sustained lateral growth of the Central Anatolian Plateau flank.Yayın RegCM4.3.5 Bölgesel iklim modelini kullanarak Türkiye ve çevresi bölgelerin yakın gelecekteki hava sıcaklığı ve yağış klimatolojileri için öngörülen değişikliklerin incelenmesi(Ege Üniversitesi, 2014-06-01) Turp, Mustafa Tufan; Öztürk, Tuğba; Türkeş, Murat; Kurnaz, Mehmet LeventBu çalışmada 1970 – 2000 referans dönemi iklimine göre 2020 – 2050 dönemi için Türkiye’nin ortalama hava sıcaklığı ve yağış klimatolojilerinde öngörülen değişiklikler, bölgesel iklim modeli benzetimleri kullanılarak araştırıldı. Yakın gelecekteki iklim koşullarında öngörülen değişimleri incelemek için Uluslararası Teorik Fizik Merkezi’ne ait olan RegCM4.3.5 isimli bölgesel iklim modeli üç farklı küresel modelden yararlanılarak koşuldu. Max Planck Meteoroloji Enstitüsü’ne ait MPI-ESM-MR, Met Office Hadley Merkezi’ne ait HadGEM2 ve Amerikan Ulusal Okyanus ve Atmosfer Dairesi Jeofiziksel Akışkanlar Dinamiği Laboratuvarı’na ait GFDL-ESM2M modelleri Türkiye ve çevresi için dinamik olarak 50 km’ye alt ölçeklendirildi. Öngörüler, Hükümetlerarası İklim Değişikliği Paneli’nin (IPCC) RCP4.5 ve RCP8.5 salım senaryolarına göre gerçekleştirildi. Model sonuçlarına göre, Türkiye’de ortalama hava sıcaklıklarında 1970 – 2000 dönemine göre 2020 – 2050 döneminde 0.5 °C ile 4 °C arasında değişen artışlar olacaktır. Bu artış, sıcak mevsimlerde soğuk mevsimlere göre daha fazla olacaktır. Türkiye’nin yağış klimatolojisinde ise, bölgesel iklim modeli sonuçlarına göre, özellikle ülkenin Akdeniz ikliminin egemen olduğu batı ve güney bölgelerinde ve tüm mevsimlerde, yaklaşık 0.4 mm/gün ile 1.2 mm/gün arasında değişen belirgin yağış azalışlarının oluşması beklenir.Yayın Cement fabrics and optical luminescence ages of beachrock, North Cyprus: Implications for Holocene sea-level changes(Elsevier Ltd., 2016-05-16) Öztürk, Muhammed Zeynel; Erginal, Ahmet Evren; Güneç Kıyak, Nafiye; Öztürk, TuğbaCaCO3-cemented beachrocks are widely found along the northern coast of Cyprus. In this study, we aim to discuss the cementation history of beachrocks at ten particular sites within the context of Holocene sea-level changes. Cement fabrics, petrographic and geochemical characteristics, and optically-stimulated luminescence ages of buried quartz grains were studied. The seaward-inclined (~5-10°) parallel-stratified beds are composed mostly of sandstone alternating with conglomerate. Ooids, benthic and planktic foraminifera, bioclasts of red algae, echinoid spines and gastropods make up a significant proportion of the cemented beds. With CaCO3 content ranging between 37% and 65%, poorly-sorted grains are bonded by four distinct cements: circumgranular micritic coatings, sparry calcite infillings, pore fills, and meniscus bridges. This consecutive nature of cementation is typical of a marine phreatic and meteoric vadose environment when the sea level was lower than present but had a tendency to increase during middle to late Holocene. OSL ages ranging from 5.4 ka to 0.38 ka indicate that the deposition and ensuing cementation of the quartz grains occurred during two main stages; younger beds dated between 2.3 ka and 0.38 ka and older beds from 2.3 ka to 5.4 ka. A period devoid of beachrock formation was attested between 3.5 ka and 2.3 ka.Yayın RegCM4.3.5 İklim modeli benzetimleri kullanılarak Türkiye'nin gelecek hava sıcaklığı ve yağış klimatolojilerindeki değişikliklerin çözümlenmesi(Ege Üniversitesi, 2011-06-01) Öztürk, Tuğba; Türkeş, Murat; Kurnaz, Mehmet LeventBu çalışmada 1970-2000 dönemi günümüz iklimine göre 2070-2100 dönemi için Türkiye’nin ortalama hava sıcaklığı ve yağış klimatolojilerindeki değişikler, bölgesel iklim modeli simülasyonları (benzetim) kullanılarak öngörüldü. Günümüz ve gelecek iklim koşullarının model kestirimlerinin yapılması için, International Centre for Theoretical Physics (ICTP) bölgesel iklim modeli RegCM4.3.5 kullanıldı. Met Office Hadley Merkezi’nin HadGEM2 küresel iklim modeli, Türkiye ve çevresi için alt ölçeklendirme yöntemi ile çalışıldı. Gelecekte Türkiye’nin iklim değişkenlerinde oluşacak değişimleri incelemek için, küresel iklim modelinin RCP4.5 ve RCP8.5 salım senaryoları çıktıları kullanıldı. Model çıktılarına göre, Türkiye’de ortalama hava sıcaklıklarında 3 °C ile 7 °C arasında değişen artışlar olacaktır. Sıcaklık artışı, sıcak mevsimlerde soğuk mevsimlere göre daha fazla olacaktır. Bölgesel iklim modeli sonuçlarına göre, Türkiye’nin yağış klimatolojisinde ise, –0.8 mm/gün ile 1.2 mm/gün arasında değişen değişimler beklenmektedir.Yayın Aeolian imprints of multiple Mediterranean invasions of the Black Sea during Pleistocene(Elsevier B.V., 2022-03-04) Erginal, Ahmet Evren; Güneç Kıyak, Nafiye; Makaroğlu, Özlem; Bozcu, Mustafa; Öztürk, Muhammed Zeynel; Selim, Haluk Hamit; Nowacyzk, Norbert R.; Kaya, Nurcan; Öztürk, Tuğba; Karabıyıkoğlu, Mustafa; Polymeris, Georgios S.Climate changes determined the repeated connections between the Black Sea, Caspian Sea and Mediterranean Sea. The landlocked anoxic Black Sea basin was exposed to several transgressions throughout Quaternary by the Mediterranean Sea through the Straits of Istanbul (Bosphorus) and by the Caspian Sea through the Manych-Kerch spillway. Sedimentological records of these connections are limited mostly to the marine terrace deposits of Marine Isotope Stage (MIS) 5e while the pre-MIS 5e period remains uncertain due to a lack of robust facies and chronological data from deep-sea sedimentary sequences. Here we discuss the imprints of multiple Mediterranean transgressions during Middle Pleistocene in the Black Sea based on facies analysis and the optical age of coastal carbonate aeolianites. Contrary to today's hydro-climate of the Black Sea, the aeolianites bear witness to the transformation of the Black Sea into a warm inland sea during successive Mediterranean invasions. Prior to the onset of aeolian deposition, paleosols were formed on the Eocene-aged hardened sandy silts, suggesting strongly washed soil. This is evidenced by no calcium carbonate and a high Rb/Sr ratio, with quartz amounting to of 99.8%. According to our OSL ages, carbonates deposited on the shelf plain under higher temperature and increased evaporation conditions in MIS 15 and the later interglacial phases were transported to the coastal sand dunes during the transitional phases of MIS 15–14, MIS 13–12, MIS 11–10 and MIS 9–8. We suggest that the carbonate-rich and ooid-containing aeolianites were repeatedly formed in the multiple Mediterranean transgression stages, beginning with an increasingly severe dry phase following the Brunhes-Matuyama magnetic reversal.Yayın Projected changes in temperature and precipitation climatology of Central Asia CORDEX Region 8 by using RegCM4.3.5(Elsevier Ltd, 2017-01-01) Öztürk, Tuğba; Turp, Mustafa Tufan; Türkeş, Murat; Kurnaz, Mehmet LeventThis work investigated projected future changes in seasonal mean air temperature (°C) and precipitation (mm/day) climatology for the three periods of 2011–2040, 2041–2070, and 2071–2100, with respect to the control period of 1971–2000 for the Central Asia domain via regional climate model simulations. In order to investigate the projected changes in near future climate conditions, the Regional Climate Model, RegCM4.3.5 of the International Centre for Theoretical Physics (ICTP) was driven by two different CMIP5 global climate models. The HadGEM2-ES global climate model of the Met Office Hadley Centre and the MPI-ESM-MR global climate model of the Max Planck Institute for Meteorology were downscaled to 50 km for the Coordinated Regional Climate Downscaling Experiment (CORDEX) Region 8. We investigated the seasonal time-scale performance of RegCM4.3.5 in reproducing observed climatology over the domain of the Central Asia by using two different global climate model outputs. For the future climatology of the domain, the regional model projects relatively high warming in the warm season with a decrease in precipitation in almost all parts of the domain. A warming trend is notable, especially for the northern part of the domain during the cold season. The results of our study show that surface air temperatures in the region will increase between 3 °C and about 7 °C on average, according to the emission scenarios for the period of 2071–2100 with respect to past period of 1971–2000. Therefore, the projected warming and decrease in precipitation might adversely affect the ecological and socio-economic systems of this region, which is already a mostly arid and semi-arid environment.Yayın Projections of climate change in the Mediterranean Basin by using downscaled global climate model outputs(Wiley-Blackwell, 2015-11-30) Öztürk, Tuğba; Ceber, Zeynep Pelin; Türkeş, Murat; Kurnaz, Mehmet LeventThe Mediterranean Basin is one of the regions that shall be affected most by the impacts of the future climate changes on hydrology and water resources. In this study, projected future changes in mean air temperature and precipitation climatology and inter-annual variability over the Mediterranean region were studied. For performing this aim, the future changes in annual and seasonal averages for the future period of 2070-2100 with respect to the period from 1970 to 2000 were investigated. Global climate model outputs of the World Climate Research Program's Coupled Model Intercomparison Project Phase 3 multi-model dataset were used in this work. Intergovernmental Panel on Climate Change SRES A2, A1B and B1 emission scenarios' outputs were used in future climate model projections. Future surface mean air temperatures of the larger Mediterranean basin increase mostly in summer and least in winter, and precipitation amounts decrease in all seasons at almost all parts of the basin. Future climate signals for air temperature and total precipitation values are much larger than the inter-model standard deviation. Inter-annual temperature variability increases evidently in summer season and decreases in the northern part of the domain in the winter season, while precipitation variability increases in almost all parts of domain. Probability distribution functions are found to be shifted and flattened for future period compared to the reference period. This indicates that the occurrence of frequency and intensity of high temperatures and heavy precipitation events will likely increase in the future period.Yayın Future projections of temperature and precipitation climatology for CORDEX-MENA domain using RegCM4.4(Elsevier Science Inc, 2018-07-01) Öztürk, Tuğba; Turp, Mustafa Tufan; Türkeş, Murat; Kurnaz, Mehmet LeventIn this study, we investigate changes in seasonal temperature and precipitation climatology of CORDEX Middle East and North Africa (MENA) region for three periods of 2010-2040, 2040-2070 and 2070-2100 with respect to the control period of 1970-2000 by using regional climate model simulations. Projections of future climate conditions are modeled by forcing Regional Climate Model, RegCM4.4 of the International Centre for Theoretical Physics (ICTP) with two different CMIP5 global climate models. HadGEM2-ES global climate model of the Met Office Hadley Centre and MPI-ESM-MR global climate model of the Max Planck Institute for Meteorology were used to generate 50 km resolution data for the Coordinated Regional Climate Downscaling Experiment (CORDEX) Region 13. We test the seasonal time-scale performance of RegCM4.4 in simulating the observed climatology over domain of the MENA by using the output of two different global climate models. The projection results show relatively high increase of average temperatures from 3 degrees C up to 9 degrees C over the domain for far future (2070-2100). A strong decrease in precipitation is projected in almost all parts of the domain according to the output of the regional model forced by scenario outputs of two global models. Therefore, warmer and drier than present climate conditions are projected to occur more intensely over the CORDEX-MENA domain.Yayın Projected changes in extreme temperature and precipitation indices over CORDEX-MENA domain(MDPI AG, 2021-05) Öztürk, Tuğba; Saygılı Aracı, Fatma Sibel; Kurnaz, Mehmet LeventIn this study, projected changes in climate extreme indices defined by the Expert Team on Climate Change Detection and Indices were investigated over Middle East and North Africa. Changes in the daily maximum and minimum temperature-and precipitation-based extreme indices were analyzed for the end of the 21st century compared to the reference period 1971–2000 using regional climate model simulations. Regional climate model, RegCM4.4 was used to downscale two different global climate model outputs to 50 km resolution under RCP4.5 and RCP8.5 scenarios. Results generally indicate an intensification of temperature-and precipitation-based extreme indices with increasing radiative forcing. In particular, an increase in annual minimum of daily minimum temperatures is more pronounced over the northern part of Mediterranean Basin and tropics. High increase in warm nights and warm spell duration all over the region with a pronounced increase in tropics are projected for the period of 2071–2100 together with decrease or no change in cold extremes. According to the results, a decrease in total wet-day precipitation and increase in dry spells are expected for the end of the century.
