Omer Lutfi Sen

Istanbul Technical University · Eurasia Institute of Earth Sciences

In this study, we present the long‐term daily and sub‐daily station data of annual extreme rainfall (1970‐2015) and the trend analyses in rainfall regimes in Turkey. Trends in 5, 10, 15, 30 minutes, 1, 2, 6, 12, and 24 hours of extreme rainfall in seven different rainfall regimes are estimated through non‐parametric tests. The trends in return leve...

The central aim of this study is to estimate the current potential distribution of Turkey’s forests and their composition in absence of anthropogenic landcover change, and in this manner to contribute to past studies on the distribution of European forest taxa by filling an important spatial gap. For our simulations, we used high resolution climate...

Emerging drought stress on vegetation over western Eurasia is linked to varying teleconnection patterns. The North-Sea Caspian pattern (NCP) is a relatively less studied Eurasian teleconnection pattern which has a role on drought conditions and the consequence of changing conditions on vegetation. Between 1981 and 2015, we found that the Standardiz...

The Mediterranean Basin, including the Mediterranean Sea and the surrounding countries, is referred to as a hotspot in terms of climate change, primarily because of a basin-wide drying trend projected for its future. The Mediterranean Sea plays an important role in the climate of the basin through air-sea interactions, and it is, therefore, importa...

The study aims to predict the potential future forest cover for Anatolia, a peninsula situated in the Eastern Mediterranean Basin, a historic land bridge between Southeast Europe and Southwest Asia with diverse terrestrial ecosystems hosting uniquely adapted species due to topographic heterogeneity and climatic variability. To forecast the potentia...

This study investigates the predictability of the dense advection fog over Istanbul on February 19, 2014, which significantly halted international as well as local transportation. Sensitivity simulations were conducted using the Weather Research and Forecasting (WRF) model forced by the ERA-Interim reanalysis data. A hierarchical approach was adopt...

Unprecedented wildfires swept Mediterranean Europe in the summer of 2021 wreaking havoc economically and socially while clearing large swaths of forest land. Those that scorched the southern coastal highlands in Turkey came on the heels of a heat wave and at the peak of the arid season. Nearly two thirds of the Anatolian Peninsula are under the inf...

Agricultural activities have a significant impact on the hydrological cycle. With the increasing population, agriculture is performed with limited water resources. In this study, land use/cover data in Konya Closed Basin, where agriculture is intensive, were examined from an agricultural point of view. Temporal and spatial analyses of the Coordinat...

With the increase in population, industrialization, agricultural activities and urbanization are increasing. In addition to this situation, when the effect of climate change is taken into account, the land cover changes quite rapidly. In this study, the change of land cover/use over time in Konya Closed Basin (KCB), which is a semi-arid closed basi...

Drought conditions of Southeast China are associated with the sea surface temperature warm pool in the tropical Western Pacific, which is related to low-frequency hydroclimatic patterns and their teleconnections. Empirically, the moisture influx to the region is linked to the interannual and decadal teleconnections, including the Pacific Decadal Os...

Turkey, aka Asia Minor, is situated in a distinct spot, surrounded by marine basins on three sides and an inner sea, coastlines on the northern and southern parts of the country cut off from the inner plateau by high mountain ranges showcasing different micro-climatic settings. The area, a natural corridor between two continents, also harbors a hea...

Atmospheric rivers (ARs) travelling thousands of kilometers over arid North Africa could interact with the highlands of the Near East (NE), and thus affect the region's hydrometeorology and water resources. Here, we use a state‐of‐the‐art AR tracking database, and reanalysis and observational datasets to investigate the climatology (1979‐2017) and...

İstanbul’un iklimi gelecekte görece az değişecek ve değişim Akdeniz iklimine doğru evrilme şeklinde olacaktır. Bu açıdan cazibesi görece yüksek kalmaya devam edecektir. İstanbul’un su kaynakları, değişen iklime tepki olarak muhtemelen azalma eğiliminde olacaktır. İklim değişikliği yavaş gerçekleşen bir olgu olduğu için değişim yeterince iyi algılan...

A heavy hailstorm developed over Istanbul on July 27, 2017 and inflicted substantial damage on hundreds of buildings and thousands of vehicles. Weather forecast models largely failed to predict this event. In this study, we investigate the performance of the Weather Research and Forecasting (WRF) model in simulating this particular hailstorm throug...

Morphological changes, caused by the erosion and deposition processes due to water discharge and sediment flux occur, in the banks along the river channels and in the estuaries. Flow rate is one of the most important factors that can change river morphology. The geometric shapes of the meanders and the river flow parameters are crucial components i...

Modelling palaeoglaciers in mountainous terrain is challenging due to the need for detailed ice flow computations in relatively narrow and steep valleys, high‐resolution climate estimations, knowledge of pre‐ice topography, and proxy‐based palaeoclimate forcing. The Parallel Ice Sheet Model (PISM), a numerical model that approximates glacier slidin...

Change detection analysis for monitoring and modeling riverine systems requires detailed spatiotemporal surveying of river morphology dynamics. An accurate high-resolution surface model of the river channel and floodplain enables a more comprehensive view of the riverbed evolution and allows monitoring the morphodynamics of the entire river channel...

Change detection analysis for monitoring and modeling riverine systems requires detailed spatial and temporal surveying of river morphology dynamics. Accurate digital surface models are an essential part of the studies of morphodynamic modeling of rivers and river channel evolution. An accurate high-resolution surface model of the river channel and...

The Euphrates–Tigris River Basin is a large transboundary basin that covers an area of about 800,000 km2 distributed between Iraq, Turkey, Iran, Syria, Saudi Arabia and Jordan. The Basin is known by the two snow­fed rivers, the Euphrates and Tigris, which are an essential part of the Southeastern Anatolian Project in Turkey. This project aims at ge...

This study investigates the potential influence of the East Asian trough (EAT) on the eastern Mediterranean temperature variability in early spring. In connection with this, it also examines the extreme case of the year 2004 when anomalous warming of the eastern Anatolia resulted in unprecedented snowmelt runoff amounts in the Euphrates and Tigris...

We used the Parallel Ice Sheet Model (PISM), to simulate a relatively small size (~300 km 2 , 17x17 km) paleo-ice cap on Mount Dedegöl in southwestern Turkey. Modelling small paleo-ice bodies in mountainous terrain is challenging due to the need for detailed ice flow computations in relatively narrow and steep valleys, high-resolution climate estim...

Euro-Mediterranean climate variability has been associated mostly with the upstream atmospheric circulation and teleconnection patterns, the North Atlantic Oscillation and European blocking being the main ones. This study shows, for the first time, that the East Asian trough (EAT), a prominent circulation feature of the mid-troposphere in the downs...

The waters of the Euphrates and Tigris rivers have always been a vital resource in the water-food-energy nexus of the Middle East region. The currently ongoing Southeastern Anatolia Project (GAP) in Turkey aims to increase regional prosperity by optimizing the use of these waters for irrigation and hydropower. Since the beginning of the 1990s, the...

The snow-fed river basins of the Near East region are facing an urgent threat in the form of declining water resources. In this study, we analyzed several remote sensing products (optical, passive microwave, and gravimetric) and outputs of a meteorological reanalysis data set to understand the relationship between the terrestrial water storage anom...

Bu çalışmada, Batı Toroslar Dağ kuşağı üzerinde bulunan Dedegöl Dağı’ndan elde edilen kozmojenik 36Cl buzul kronolojileri ve sayısal buzul akış modeli ile elde edilen paleoiklim çıkarımları sunulmuştur. Dedegöl Dağı’ndaki (2992 m, Beyşehir Gölü’nün ~ 15 km batısı) üç buzul vadisinde, morenlerden alınan toplam 25 örnek kozmojenik 36Cl yüzey tarihlen...

Irrigation is a common practice that is performed to increase the agricultural yield all around the globe. A regional development project that uses the waters of the Euphrates and Tigris rivers to irrigate vast semi-arid lands has already caused immense land cover and land use (LCLU) changes. Here, outputs from a regional climate model (RCM) LCLU...

The East Asian trough (EAT) is the strongest stationary wave in the Northern Hemisphere mid- latitudes. In this study, we investigate how its strength affects the amplitude and location of the eastern Mediterranean trough that causes temperature variability over the eastern Mediterranean. We used daily ERA-Interim dataset whose time span is from 19...

During the Late Quaternary, glaciers were formed on the Mt. Dedegöl (SW Turkey), and the geomorphological evidences for these glaciers were be observed and dated. The area covered by glaciers can be matched with the results produced by computer based numerical glacier reconstruction. For this purpose, an open source software, named Parallel Ice She...

İTÜ Vakfı dergisinin Nisan-Haziran 2018 tarihli 80. sayısında basılan bu makale (tam kaynakça aşağıdaki gibi) o tarihe yakın zamanlarda gerçekleşen şiddetli meteorolojik olaylar ışığında küresel iklim değişikliğini anlatmaktadır. Küresel ısınmaya rağmen kışın neden şiddetli soğuklar oluşuyor? Neden yağışların şiddeti artıyor ve yüzlerce, binlerce i...

Climate plays a crucial role in the development of soils on the surface of the earth. In fact, there is a broad agreement between the distributions of soil and climate types at a global scale.

1. GİRİŞ Hükümetlerarası İklim değişikliği Paneli'nin dördüncü değerlendirme raporunda (IPCC 2007) değişik emisyon senaryoları için çalıştırılmış Küresel Sirkülasyon Model (KSM) çıktılarına göre ülkemizin de içinde bulunduğu Akdeniz Havzası'nda yirmi birinci yüzyıl sonlarına doğru sıcaklıkların artışıyla beraber yağışlarda önemli azalmaların meydan...

Dünyamız… Uzaydan çekilen resimlerde göz alıcı bir nazar boncuğu… Mavi Gezegen… Mavilik… Suya işaret… Suyu bol… Yaşama işaret… Karalar, yeşillikler, başka renkler… Canlı çeşitliliğine işaret… Üzerinde beyaz fırça izleri… Bulutlar… Havaya işaret… Harekete işaret… Bu gezegende sonsuz olan bir şey yok… Her şey sonlu… Suyu sonlu… Karası sonlu… Havası s...

Türkiye’de Kuvaterner buzul dönemlerine ait sedimanlar yüksek dağlık alanlarda yaygın bir şekilde gelişmiştir. Özellikle yüksekliği 2000-3000 m’nin üzerinde yer alan birçok bölgede Geç Pleyistosen ve kısmen de Holosen’de gelişen buzulların oluşturduğu morenler içindeki tiller ve glasiyo-flüvyal kökenli sandur çökelleri bulunmaktadır. Genellikle vad...

Anomalous temperatures over eastern Anatolia during the first week of March 2004 caused rapid snowmelt and resulted in high river discharges that are unprecedented in the region at that time of year. The primary objective of the study is to investigate the underlying surface and atmospheric mechanisms leading to this extreme event, together with a...

The Southeastern Anatolia Project (SAP) of Turkey, one of the largest regional development projects in the world, aims to irrigate the vast semi-arid plains of the upper Mesopotamia by transferring water from the Euphrates and Tigris rivers. At the current realization level of irrigation projects (about 25%), it has already caused extensive land co...

The three-dimensional non-hydrostatic mesoscale model, OMEGA (Operational Multiscale Environment model with Grid Adaptivity), is utilized to investigate the thermally driven local flows and their interaction with each other over the province of Istanbul, Turkey. Idealized case simulations are conducted in order to describe the contribution of sea–l...

This study presents the comparison of two different approaches for quantifying the spatiotemporal distribution of the evapotranspiration at the regional scale: the simulations by a regional climate model (ICTP-RegCM3), versus the estimations by a remote sensing based surface energy balance model (SEBS). The comparison was carried out in the semi-ar...

GCMs are the advanced tools essential for simulating the climate and changes in the climate system, however their performances in simulating the regional climate characteristics could be highly different from each other. Thus, it could be wise, first, to evaluate the performances of the GCMs to decide on which ones to proceed with in a dynamical do...

This paper reports the second part of a study that aims to understand the thermally driven local flows and their interaction with each other over the province of Istanbul. The first part of the research evaluates a series of sensitivity simulations involving perturbations to the landscape. The present one includes an analysis of the real case simul...

The hydrological discharge (HD) model of Max Planck Institute for Meteorology is forced by a variety of climate model datasets to investigate the future of discharge in the Euphrates-Tigris Basin. The data include daily time series of surface runoff and sub-surface runoff outputs of 2 global climate models (GCMs) (the SRES A1B scenario simulation o...

Turkey lies in a region that is highly vulnerable to climate change, and the indicators show that climate is changing in Turkey. The station observations show that temperatures are increasing throughout the country. Summer temperatures increase more than those of the other seasons. There are significant shifts in the timing of the snowfed river dis...

We used the Conversion of Land Use and its Effects (CLUE-s) model to simulate scenarios of land-cover and land-use change (LCLUC) in Montane Mainland Southeast Asia (MMSEA), a region on the cusp of change due to projected rapid intensification of agriculture and expansion of regional trade markets. Simulated changes affected approximately 10% of th...

In this study, human-induced climate change over the Eastern Mediterranean–Black Sea region has been analyzed for the twenty-first century by performing regional climate model simulations forced with large-scale fields from three different global circulation models (GCMs). Climate projections have been produced with Special Report on Emissions Scen...

This study investigates whether snowmelt runoff for the selected 15 streamflow stations located in the Euphrates, Tigris, Aras, and Çoruh basins in eastern Anatolia, Turkey, has shown a consistent hydrologic response to global climatic changes over the past several decades. It also investigates the future runoff changes in these basins. The analysi...

This report was prepared by Ömer Lütfi Şen based on the outcomes of his Mercator-IPC Fellowship project “A holistic view of climate change impact in Turkey” between September 1, 2012 and August 31, 2013. It may not be used for any other purposes, reproduced in whole or part, nor passed to any organisation or person without the specific permission i...

It is sensible to expect the climate change issue to heat up in the international agenda during the second half of 2013 as the UN's Intergovernmental Panel on Climate Change (IPCC) will start to release the fifth assessment report (AR5) on climate change late this year. The release of the AR5 and the possible preceding and alongside debates as well...

Since urban areas display nonlinear and dynamic interactions within their growth patterns, a crucial question is how complex systems can be integrated into urban planning practices in relation to urban ecosystems. Natural threats and extreme weather conditions resulting from climate change will threaten social, environmental and economic assets in...

Hydro-climatic effects of future climate change in the Euphrates-Tigris Basin are investigated using dynamically downscaled outputs of different GCM (ECHAM5, CCSM3 and HadCM3) - emissions scenario (A1FI, A2 and B1) simulations. The suite of simulations (total five) enables an analysis taking into account the A2 emission scenario simulations of thre...

The Eastern Anatolia Region has a high and quite complex terrain, with a considerable snow-pack in the cold season. It hosts the headwaters regions of important rivers. In such regions, several factors including the inadequate observational network and difficulty of maintenance of the available hydro-meteorological stations affect the quality and q...

Regional climate model simulations with RegCM3 were performed to investigate how future land-cover/land-use (LCLU) change in Montane Mainland Southeast Asia (MMSEA) could affect regional climate. Simulation land-surface parameterizations included present day and plausible 2050 land-covers, as well as two extreme deforestation simula- tions. In the...

We used the conversion of land use and its effects (CLUE-s) model to simulate scenarios of land-cover change in Montane mainland southeast Asia (MMSEA), a region in the midst of transformation due to rapid intensification of agriculture and expansion of regional trade markets. Simulated changes affected approximately 10 % of the MMSEA landscape bet...

Three-dimensional non-hydrostatic meso-scale model, OMEGA (Operational Multi-scale Environment model with Grid Adaptivity), is utilized to investigate the thermally driven local flows and their interaction with each other in Istanbul. The city of Istanbul is located between two water bodies, Black Sea in the north and Sea of Marmara in the south. T...

Hydroclimatological impacts of future climate change in the Euphrates-Tigris Basin are investigated by using dynamically downscaled outputs of different GCM (ECHAM5, CCSM3 and HadCM3) - emissions scenario (A1FI, A2 and B1) simulations. The suit of simulations (total five) allows to be analyzed as the A2 emission scenario simulations of three differ...

The outputs of three GCMs, ECHAM5, CCSM3 and HadCM3, are downscaled for the eastern Mediterranean–Black Sea region for the period 1961–1990 using a regional climate model, RegCM3, to assess the capability of these models in simulating the climatology of the region. In addition, the NCEP/NCAR Reanalysis data are also downscaled for the same period t...

The streamflow timings of the Euphrates and Tigris, two important snow-fed rivers in the Middle East, are found to be shifting to earlier days in the year. Six out of eight stations indicate statistically significant shifts between two consecutive 17-year periods (i.e. 1972–88 and 1990–2006). Among these stations, the average shift to earlier times...

Effects of the increased sea surface tempera- tures (SSTs) in the surrounding seas of the Anatolian Peninsula on the precipitation it receives are investigated through sensitivity simulations using a state-of-the-art regional climate model, RegCM3. The sensitivity simula- tions involve 2-K increases to the SSTs of the Aegean, eastern Mediterranean...

The outputs of three GCMs, ECHAM5, CCSM3 and HADCM3, are downscaled for the eastern Mediterranean-Black Sea region for the period 1961-1990 using a regional climate model, RegCM3, to assess the capability of these models in simulating the climatology of the region. In addition, the NCEP/NCAR Reanalysis data are also downscaled for the same period t...

In this study, it is aimed to demonstrate climate change impacts on hydrometeorology of the Euphrates and Tigris Basins which are the two major water sources in the Middle East. The ICTP-RegCM3 model has been used to downscale MPI's ECHAM5/MPI-OM and NCAR's CCSM for different emission scenarios in an ongoing project supported by UNDP. The simulatio...

Temperature has been traditionally used as the primary parameter in detecting the climate change signal at scales from local to global. As being point measurements, however, temperature data come with important shortcomings such as the lack of the representivity of large areas and contamination by urban heat island effect as most stations are locat...

An action was taken to release water from the dam reservoirs on the Euphrates river in response to severe precipitation and snowmelt events that took place in the Eastern Anatolia, Turkey in the early days of March 2004. In order to investigate this event, an atmosphere-hydrology modeling system was introduced by using the climate simulations done...

We investigate the potential role of haptics in augmenting the visualization of climate data. In existing approaches to climate visualization, different dimensions of climate data such as temperature, humidity, wind, precipitation, and cloud water are typically represented using different visual markers and dimensions such as color, size, intensity...

Outlier trimming and homogeneity checking/correction were performed on the monthly precipitation time series of various lengths from 267 stations in Turkey. Outlier values are usually found during dry summer months, and are concentrated mostly over the southern parts of the country, where the dry period is most pronounced, implying natural extremes...

Statistical and numerical modeling tools were used to investigate the climatic effects of urbanization in Istanbul, the largest city in Turkey. Mann–Kendall trend test was applied to minimum temperature data from stations located in urban, suburban and rural areas in Istanbul to determine the existence and significance of trends, and the approximat...

This paper describes a study that investigates the local and regional effects of vegetation restoration in northern China via regional climate model simulations, and reports implications for the sustainability of vegetation under the altered rainfall regime. Ensemble simulations with the current vegetation cover and an idealized re-greening scenari...

This paper describes a study that investigates the local and remote effects of Indochina deforestation on the east Asian summer monsoon. During the summer months, the peninsula is subject to strong monsoonal flow whose downstream rainfall is of vital importance for China, where a significant fraction of the world's population lives. It is, therefor...

East Asia is a region with complex topography, land surface conditions, coastlines, and with large contribution from mesoscale phenomena, such as the mei-yu/baiu frontal systems and tropical storms. To study the regional climate in such a region, a highly resolved regional climate model (IPRC-RegCM) has been recently developed at the International...

This paper describes a study in which, for the first time, advanced systems-engineering parameter-estimation techniques were applied to data from several field studies to estimate the preferred set of parameters for some of the most common biomes represented in an advanced Soil-Vegetation-Atmosphere Transfer (SVAT) scheme (BATS2, a recent version o...

Over the last decade, improved understanding of plant physiological processes has generated a significant change in the way stomatal functioning is described in advanced land surface schemes. New versions of two advanced and widely used land surface schemes, the Biosphere-Atmosphere Transfer Scheme (BATS) and the Simple Biosphere Model (SIB), refle...