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Impact of climate change and land cover dynamics on nitrate transport to surface waters
(Springer Science and Business Media Deutschland GmbH, 2024-03) Boyacıoğlu, Hülya; Gunecti, Mert Can; Barbaros, Filiz; Gül, Ali; Gül, Gülay Onuşluel; Öztürk, Tuğba; Kurnaz, M. Levent
The study investigated the impact of climate and land cover change on water quality. The novel contribution of the study was to investigate the individual and combined impacts of climate and land cover change on water quality with high spatial and temporal resolution in a basin in Turkey. The global circulation model MPI-ESM-MR was dynamically downscaled to 10-km resolution under the RCP8.5 emission scenario. The Soil and Water Assessment Tool (SWAT) was used to model stream flow and nitrate loads. The land cover model outputs that were produced by the Land Change Modeler (LCM) were used for these simulation studies. Results revealed that decreasing precipitation intensity driven by climate change could significantly reduce nitrate transport to surface waters. In the 2075–2100 period, nitrate-nitrogen (NO3-N) loads transported to surface water decreased by more than 75%. Furthermore, the transition predominantly from forestry to pastoral farming systems increased loads by about 6%. The study results indicated that fine-resolution land use and climate data lead to better model performance. Environmental managers can also benefit greatly from the LCM-based forecast of land use changes and the SWAT model’s attribution of changes in water quality to land use changes. Graphical abstract: (Figure presented.).
Time-dependent lateral diffusion in WO? thin films
(Elsevier B.V., 2023-10) Karakurt, İsmail; Başar, Günay; Leiderer, Paul; Parlatan, Şeyma; Arapoğlu, Nihan
We have studied the anomalous lateral diffusion process in thin tungsten trioxide films by optical means. The diffusion process seems to start at imperfections within the film a few seconds after the H+ ion intercalation begins, and progresses parallel to the surface of the film. We measured the mean square displacement of the diffusion front and used its time-dependence to calculate the instantaneous diffusion coefficient. The anomalous exponents are found to be 2.24 and 2.92 for 400 nm and 270 nm thick films, respectively. We explain the observed large diffusion coefficients and depth dependence of the expansion of the film by interfacial job-sharing diffusion of electrons and protons. Raman measurements were also carried out on virgin films, and on films after the lateral diffusion. Although the observed spectrum after the lateral diffusion is, in general, consistent with the literature for H+ intercalated films, we observe an additional strong band at 855 cm?1. This lateral diffusion process is observed to be irreversible; therefore, it has to be avoided in electrochromic switching devices based on WO3.
The emergence of projected scaled patterns of extreme temperatures over Europe
(Frontiers Media SA, 2023-06-28) Öztürk, Tuğba; Canbaz, Emine; Bilgin, Başak; Matte, Dominic; Kurnaz, Mehmet Levent; Christensen, Jens Hesselbjerg
This work investigates the scalability of extreme temperatures over the European domain with global warming levels. We have used the EURO-CORDEX ensemble of regional model simulations at 0.11° resolution for daily minimum and maximum temperatures to analyze future changes in extreme weather daily events. Scaling with the annual mean global warming modeled by the driving GCM was applied to future extreme temperature indices changes. Regional changes in each index were scaled by corresponding global warming levels obtained from GCMs. This approach asserts that regional patterns of climate change and average global temperature change are linearly related. It can provide information regarding climate change for periods or emission scenarios when no simulations exist. According to the results, the annual minimum of the lowest temperature of the day (TNn) increases more than the annual maximum of the highest temperature of the day (TXx) for Europe. The multi-model mean of the changes in scaled patterns of extreme temperatures emerges early, around 2020, even before it becomes robust. Individual scaled patterns of TNn and TXx emerge from around 2040.
Projected future changes in extreme climate indices over Central Asia using RegCM4.3.5
(MDPI, 2023-06) Öztürk, Tuğba
This work projected future extreme climate indices' changes over Central Asia (The Coordinated Regional Climate Downscaling Experiment-CORDEX Region 8). Changes were calculated for 2071-2100 relative to 1971-2000. Climate simulations were obtained by downscaling the RegCM4.3.5 to 50 km resolution under RCP4.5 and 8.5 with HadGEM2-ES and MPI-ESM-MR. The results indicate that the Central Asian domain will experience warmer and more extreme temperatures with increasing radiative forcing. The annual lowest value of minimum daily temperature was simulated to increase remarkably, up to 8 degrees, especially in high latitudes, with a more than 12 degree increase projected over Siberia. A strong growth in the percentage of warm nights and an increase in the days of warm spells for the whole region, with a decrease in cold spell duration, are anticipated. Model results show an expected reduction of up to 30% in precipitation totals over the domain, except for the increased precipitation over Siberia, the Himalayas, and Tibetan Plateau. Extreme precipitation events are projected to have an increase of 20% over the whole domain, with an 80% increase over high topographical areas.
Implications for late Quaternary Sea level changes on the Mediterranean and Black Sea Coasts - MEDBLACKS2014
(Elsevier Ltd, 2016-05-16) Erginal, Ahmet Evren; Güneç Kıyak, Nafiye
[No abstract available]
RegCM4.3.5 İklim modeli? benzeti?mleri? kullanılarak Türki?ye'ni?n gelecek hava sıcaklığı ve yağış klimatolojilerindeki deği?şi?kli?kleri?n çözümlenmesi
(Ege Üniversitesi, 2011-06-01) Öztürk, Tuğba; Türkeş, Murat; Kurnaz, Mehmet Levent
Bu 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.
RegCM4.3.5 Bölgesel i?klim modelini kullanarak Türkiye ve çevresi bölgelerin yakın gelecekteki hava sıcaklığı ve yağış klimatolojileri i?çin öngörülen değişikliklerin i?ncelenmesi
(Ege Üniversitesi, 2014-06-01) Turp, M. Tufan; Öztürk, Tuğba; Türkeş, Murat; Kurnaz, Mehmet Levent
Bu 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.
The Worldwide C3S CORDEX Grand Ensemble A Major Contribution to Assess Regional Climate Change in the IPCC AR6 Atlas
(American Meteorological Society, 2022-12) Diez-Sierra, Javier; Iturbide, Maialen; Gutierrez, Jose M.; Fernandez, Jesus; Milovac, Josipa; Cofino, Antonio S.; Cimadevilla, Ezequiel; Nikulin, Grigory; Levavasseur, Guillaume; Kjellstrom, Erik; Bulow, Katharina; Horanyi, Andras; Brookshaw, Anca; Garcia-Diez, Markel; Perez, Antonio; Bano-Medina, Jorge; Ahrens, Bodo; Alias, Antoinette; Ashfaq, Moetasim; Bukovsky, Melissa; Buonomo, Erasmo; Caluwaerts, Steven; Chou, Sin Chan; Christensen, Ole B.; Ciarlo, James M.; Coppola, Erika; Corre, Lola; Demory, Marie-Estelle; Djurdjevic, Vladimir; Evans, Jason P.; Fealy, Rowan; Feldmann, Hendrik; Jacob, Daniela; Jayanarayanan, Sanjay; Katzfey, Jack; Keuler, Klaus; Kittel, Christoph; Kurnaz, Mehmet Levent; Laprise, Rene; Lionello, Piero; McGinnis, Seth; Mercogliano, Paola; Nabat, Pierre; Öztürk, Tuğba; Panitz, Hans-Jurgen; Paquin, Dominique; Pieczka, Ildiko; Raffaele, Francesca; Remedio, Armelle Reca; Scinocca, John; Sevault, Florence; Somot, Samuel; Steger, Christian; Tangang, Fredolin; Teichmann, Claas; Termonia, Piet; Thatcher, Marcus; Torma, Csaba; van Meijgaard, Erik; Vautard, Robert; Warrach-Sagi, Kirsten; Winger, Katja; Zittis, George; Önol, Barış
The collaboration between the Coordinated Regional Climate Downscaling Experiment (CORDEX) and the Earth System Grid Federation (ESGF) provides open access to an unprecedented ensemble of regional climate model (RCM) simulations, across the 14 CORDEX continental-scale domains, with global coverage. These simulations have been used as a new line of evidence to assess regional climate projections in the latest contribution of the Working Group I (WGI) to the IPCC Sixth Assessment Report (AR6), particularly in the regional chapters and the Atlas. Here, we present the work done in the framework of the Copernicus Climate Change Service (C3S) to assemble a consistent worldwide CORDEX grand ensemble, aligned with the deadlines and activities of IPCC AR6. This work addressed the uneven and heterogeneous availability of CORDEX ESGF data by supporting publication in CORDEX domains with few archived simulations and performing quality control. It also addressed the lack of comprehensive documentation by compiling information from all contributing regional models, allowing for an informed use of data. In addition to presenting the worldwide CORDEX dataset, we assess here its consistency for precipitation and temperature by comparing climate change signals in regions with overlapping CORDEX domains, obtaining overall coincident regional climate change signals. The C3S CORDEX dataset has been used for the assessment of regional climate change in the IPCC AR6 (and for the interactive Atlas) and is available through the Copernicus Climate Data Store (CDS).
Projections of future change of climatology and extreme weather events in the Mediterranean Basin, by the HIRHAM5 regional climate model
(Marmara Üniversitesi, 2022-03-30) Öztürk, Tuğba
In this study, changes in temperature and precipitation climatology and extreme weather events over the Mediterranean Basin including Turkey were investigated using HIRHAM5 driven by global climate models such as EC-EARTH, HadGEM2-ES, and NorESM1-M for 2011-2100 compared to 1971-2000. RCP4.5 and RCP8.5 scenario outputs of global climate models were used as forcing data. Daily mean temperature and precipitation variables are used to compute extreme indices. Extreme indices were calculated for the period of 2071-2100 compared to the reference period. According to the results, the severity of temperature- and precipitation-based indices will be expected to increase throughout the century with increasing radiative forcing. Minimum of minimum temperatures will increase more pronounced over the northern Mediterranean, which is referred to as climate change hot spots, whereas the increase in a maximum of maximum temperatures is moderate over land areas. A decrease in total wet-day precipitation is expected while the number of dry days is expected to increase. Therefore, the Mediterranean Basin and Turkey will have warmer and drier conditions compared to present climate conditions.
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.
Robustness of future atmospheric circulation changes over the EURO-CORDEX domain
(Springer Science and Business Media Deutschland GmbH, 2022-09) Öztürk, Tuğba; Matte, Dominic; Christensen, Jens Hesselbjerg
European climate is associated with variability and changes in the mid-latitude atmospheric circulation. In this study, we aim to investigate potential future change in circulation over Europe by using the EURO-CORDEX regional climate projections at 0.11° grid mesh. In particular, we analyze future change in 500-hPa geopotential height (Gph), 500-hPa wind speed and mean sea level pressure (MSLP) addressing different warming levels of 1 °C, 2 °C and 3 °C, respectively. Simple scaling with the global mean temperature change is applied to the regional climate projections for monthly mean 500-hPa Gph and 500-hPa wind speed. Results from the ensemble mean of individual models show a robust increase in 500-hPa Gph and MSLP in winter over Mediterranean and Central Europe, indicating an intensification of anticyclonic circulation. This circulation change emerges robustly in most simulations within the coming decade. There are also enhanced westerlies which transport warm and moist air to the Mediterranean and Central Europe in winter and spring. It is also clear that, models showing different responses to circulation depend very much on the global climate model ensemble member in which they are nested. For all seasons, particularly autumn, the ensemble mean is much more correlated with the end of the century than most of the individual models. In general, the emergence of a scaled pattern appears rather quickly.
Spatial extent of precipitation events: when big is getting bigger
(Springer Science and Business Media Deutschland GmbH, 2022-03) Matte, Dominic; Christensen, Jens Hesselbjerg; Öztürk, Tuğba
Using a sub-selection of regional climate models at 0.11 degrees (approximate to 12 km) grid resolution from the EURO-CORDEX ensemble, we investigate how the spatial extent of areas associated with the most intensive daily precipitation events changes as a consequence of global warming. We address this by analysing three different warming levels: 1 degrees C, 2 degrees C and 3 degrees C. We find that not only does the intensity of such events increase, but their size will also change as a function of the warming: larger systems becomes more frequent and larger, while systems of lesser extent are reduced in numbers.
Global exposure of population and land-use to meteorological droughts under different Warming Levels and Shared Socioeconomic Pathways: A Coordinated Regional Climate Downscaling Experiment-based study
(John Wiley and Sons Ltd, 2021-12) Spinoni, Jonathan; Barbosa, Paulo; Bucchignani, Edoardo; Cassano, John; Cavazos, Tereza; Cescatti, Alessandro; Christensen, Jens Hesselbjerg; Christensen, Ole Bossing; Coppola, Erika; Evans, Jason; Forzieri, Giovanni; Geyer, Beate; Giorgi, Filippo; Jacob, Daniela; Katzfey, Jack; Koenigk, Torben; Laprise, Rene; Lennard, Christopher John; Kurnaz, Mehmet Levent; Li, Delei; Llopart, Marta; McCormick, Niall; Naumann, Gustavo; Nikulin, Grigory; Öztürk, Tuğba; Panitz, Hans-Jurgen; da Rocha, Rosmeri Porfirio; Solman, Silvina Alicia; Syktus, Jozef; Tangang, Fredolin; Teichmann, Claas; Vautard, Robert; Vogt, Jurgen Valentin; Winger, Katja; Zittis, George; Dosio, Alessandro
Global warming is likely to cause a progressive drought increase in some regions, but how population and natural resources will be affected is still underexplored. This study focuses on global population and land-use (forests, croplands, pastures) exposure to meteorological drought hazard in the 21st century, expressed as frequency and severity of drought events. As input, we use a large ensemble of climate simulations from the Coordinated Regional Climate Downscaling Experiment, population projections from the NASA-SEDAC dataset, and land-use projections from the Land-Use Harmonization 2 project for 1981-2100. The exposure to drought hazard is presented for five SSPs (SSP1-SSP5) at four Global Warming Levels (GWLs, from 1.5 to 4 degrees C). Results show that considering only Standardized Precipitation Index (SPI; based on precipitation), the combination SSP3-GWL4 projects the largest fraction of the global population (14%) to experience an increase in drought frequency and severity (vs. 1981-2010), with this value increasing to 60% if temperature is considered (indirectly included in the Standardized Precipitation-Evapotranspiration Index, SPEI). With SPEI, considering the highest GWL for each SSP, 8 (for SSP2, SSP4, and SSP5) and 11 (SSP3) billion people, that is, more than 90%, will be affected by at least one unprecedented drought. For SSP5 (fossil-fuelled development) at GWL 4 degrees C, approximately 2 center dot 10(6) km(2) of forests and croplands (respectively, 6 and 11%) and 1.5 center dot 10(6) km(2) of pastures (19%) will be exposed to increased drought frequency and severity according to SPI, but for SPEI, this extent will rise to 17 center dot 10(6) km(2) of forests (49%), 6 center dot 10(6) km(2) of pastures (78%), and 12 center dot 10(6) km(2) of croplands (67%), with mid-latitudes being the most affected areas. The projected likely increase of drought frequency and severity significantly increases population and land-use exposure to drought, even at low GWLs, thus extensive mitigation and adaptation efforts are needed to avoid the most severe impacts of climate change.
Projected changes in extreme temperature and precipitation indices over CORDEX-MENA domain
(MDPI AG, 2021-05) Öztürk, Tuğba; Saygılı Aracı, F. Sibel; Kurnaz, Mehmet Levent
In 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.
Business-as-usual will lead to super and ultra-extreme heatwaves in the Middle East and North Africa
(Nature Research, 2021-03-21) Zittis, George; Hadjinicolaou, Panos; Almazroui, Mansour; Bucchignani, Edoardo; Driouech, Fatima; El Rhaz, Khalid; Kurnaz, Levent; Nikulin, Grigory; Ntoumos, Athanasios; Öztürk, Tuğba
Global climate projections suggest a significant intensification of summer heat extremes in the Middle East and North Africa (MENA). To assess regional impacts, and underpin mitigation and adaptation measures, robust information is required from climate downscaling studies, which has been lacking for the region. Here, we project future hot spells by using the Heat Wave Magnitude Index and a comprehensive ensemble of regional climate projections for MENA. Our results, for a business-as-usual pathway, indicate that in the second half of this century unprecedented super- and ultra-extreme heatwave conditions will emerge. These events involve excessively high temperatures (up to 56 degrees C and higher) and will be of extended duration (several weeks), being potentially life-threatening for humans. By the end of the century, about half of the MENA population (approximately 600 million) could be exposed to annually recurring super- and ultra-extreme heatwaves. It is expected that the vast majority of the exposed population (>90%) will live in urban centers, who would need to cope with these societally disruptive weather conditions.
River, alluvial fan and landslide interactions in a tributary junction setting: Implications for tectonic controls on Quaternary fluvial landscape development (Central Anatolian Plateau northern margin, Turkey)
(Elsevier B.V., 2021-03-01) McClain, Kevin P.; Yıldırım, Cengiz; Çiner, Tahsin Attila; Sarıkaya, M. Akif; Özcan, Orkan; Görüm, Tolga; Köse, Oğuzhan; Şahin, Sefa; Güneç Kıyak, Nafiye; Öztürk, Tuğba
Along the western flank of the northern margin (Central Pontides) of the Central Anatolian Plateau, the humidity from the Black Sea is much higher than the central and eastern flanks and creates a complex relationship between surface and tectonic processes by triggering intense mass wasting activity and aggradation within narrow valleys. We identified three incised fill terrace levels and used Optically Stimulated Luminescence (OSL) dating to calculate fluvial sediment ages and cosmogenic 36Cl exposure dating to calculate limestone boulders exposure ages across the terrace surface. Stratigraphical interpretations and OSL ages of the lowest levels revealed that a fluvial fill terrace formed in the main valley at 275.6 ± 12.8 ka and was overlain by a main river-tributary junction alluvial fan that was abandoned at 39.5 ± 3.5 ka. The results collectively show the influence of climate, topography, hillslope processes, and lithology on aggradation-incision patterns of main rivers. Prolonged aggradation can prevent the channel equilibrium required to calculate rock uplift rates while also causing a new base-level and aggradation upstream. This effect can be exacerbated in uplifting mountainous regions with limited depositional areas. Bedrock incision rates based on the fluvial terrace age were between 0.15 and 0.2 mm/a since 39.5 ± 3.5 ka. However, the high aggradation within this segment of the main valley prevented incision of the channel bedrock for long periods, causing a potential underestimation of the rock uplift rate calculation. Our local period of aggradation appears to be related to increased aggradation and decreased bedrock incision rates measured 14 km upstream that were previously assumed to be the result of decreased tectonic uplift rates. This demonstrates the importance of corroborating strath terrace incision rate estimations with ages and incision rates of downstream fill terraces, if present, to check for potential interference with the tectonic signal.
Strategies for the evolution of sex
(American Institute of Physics Inc., 2001-12) Tüzel, Erkan; Sevim, Volkan; Erzan, Ayşe
The maintenance of a macroscopic sexual population is addressed. As a scenario, the mechanism of random conversion to sex, in the presence of a constant rate of mutation is examined. This scenario is very closely related to "coevolution of cell senescence and diploid sexual reproduction in unicellular organisms." In this work, a "senescence clock" ticks off a finite lifetime for each bit string. Sexual reproduction resets the senescence of clock; unless this happens after a number of generations of cloning, the offspring stop dividing and die.
Quaternary rock uplift rates and their implications for the western flank of the North Anatolian Fault restraining bend; inferences from fluvial terrace ages
(Blackwell Publishing Ltd, 2020-10-01) McClain, Kevin P.; Yıldırım, Cengiz; Ciner, Attila; Şahin, Sefa; Sarıkaya, Mehmet Akif; Özcan, Orkan; Güneç Kıyak, Nafiye; Öztürk, Tuğba
In the western flank of the North Anatolian Fault restraining bend (i.e., Central Pontides), the Filyos River incises through the uplifting Karabük Range, creating the ~1.7-km-deep Filyos River Gorge on the hanging wall of the reverse Karabük Fault. Seven fluvial strath terrace levels are preserved in this gorge. optically stimulated luminescence ages from quartz-rich sediments of five terrace levels reveal an average long-term rock uplift rate of 0.45 ± 0.02 mm yr?1 with an unsteady pattern of uplift during the last 542 ± 24 kyr. Uplift rates of 1.52 ± 0.6 and 0.74 ± 0.3 mm yr?1 occurred before 366 ± 19 kyr, followed by lower rates of ~0.1 and 0.31 mm yr?1 through present. These later uplift rates may reflect relatively slower tectonic rates since ~366 kyr, with closer similarity to regional uplift rates of ~0.3 mm yr?1 yielded from the eastern flank of the Central Pontides. The Karabük Range fluvial terraces are near the North Anatolian Fault, meaning pre- ~366 kyr uplift rates may be a glimpse of the highest Central Pontides Quaternary rock uplift rates on uplifting hanging wall blocks activated by the restraining bend. When we consider offshore seismic reflection data, the focal mechanism solution of the Bartın Earthquake, onshore structural data, and regional tectonic geomorphology, the western flank of the Central Anatolian Plateau's northern margin is propagating northward as a growing orogenic wedge with a positive flower-structure geometry.
İznik Gölü kıyılarındaki yalıtaşlarının kökeni, yaşı ve geç kuvaterner göl seviye değişimleri ile bağlantıları
Future global meteorological drought hot spots: A study based on CORDEX data
(American Meteorological Society, 2020-05-01) Spinoni, Jonathan; Barbosa, Paulo; Bucchignani, Edoardo; Kurnaz, Mehmet Levent; Öztürk, Tuğba
Two questions motivated this study: 1) Will meteorological droughts become more frequent and severe during the twenty-first century? 2) Given the projected global temperature rise, to what extent does the inclusion of temperature (in addition to precipitation) in drought indicators play a role in future meteorological droughts? To answer, we analyzed the changes in drought frequency, severity, and historically undocumented extreme droughts over 1981–2100, using the standardized precipitation index (SPI; including precipitation only) and standardized precipitation-evapotranspiration index (SPEI; indirectly including temperature), and under two representative concentration pathways (RCP4.5 and RCP8.5). As input data, we employed 103 high-resolution (0.448) simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX), based on a combination of 16 global circulation models (GCMs) and 20 regional circulation models (RCMs). This is the first study on global drought projections including RCMs based on such a large ensemble of RCMs. Based on precipitation only,;15% of the global land is likely to experience more frequent and severe droughts during 2071–2100 versus 1981–2010 for both scenarios. This increase is larger (;47% under RCP4.5,;49% under RCP8.5) when precipitation and temperature are used. Both SPI and SPEI project more frequent and severe droughts, especially under RCP8.5, over southern South America, the Mediterranean region, southern Africa, southeastern China, Japan, and southern Australia. A decrease in drought is projected for high latitudes in Northern Hemisphere and Southeast Asia. If temperature is included, drought characteristics are projected to increase over North America, Amazonia, central Europe and Asia, the Horn of Africa, India, and central Australia; if only precipitation is considered, they are found to decrease over those areas.

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