AYBE- İklim ve Deniz Bilimleri Lisansüstü Programı
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Bu anabilim dalımızda fizik, meteoroloji, çevre gibi farklı disiplinlerden gelen öğrencilere çok sayıda Yüksek Lisans ve Doktora çalışmaları yaptırılmıştır.
Çalışma Konuları:
• İklim Değişikliği
• İklim Modellemesi
• Hidrolojik Modelleme
• Hava Kalitesi Modellemesi
• Model Performans Değerlendirmesi
• Atmosfer - Okyanus Etkileşimi
• Emisyon Envanteri
• Türkiye İklimi
Gözat
Yazar "Bozbura, Merih" ile AYBE- İklim ve Deniz Bilimleri Lisansüstü Programı'a göz atma
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ÖgeTürkiye'yi Etkileyen Siklon Yörüngeleri: Ncep 2 - Era-ınterım(Eurasia Institute of Earth Sciences, 2018-06-06) Bozbura, Merih ; Şen, Ömer Lütfi ; 601161005 ; Climate and Marine Sciences ; İklim ve Deniz Bilimleri Anabilim DalıCyclones are low pressure atmospheric systems that control weather conditions every day in many places of mid-latitudes. Any systematic change in the density, frequency or location of cyclones has a wide range of influence on the local climate. When they arise it takes time to evolve and become a mature cyclone and fade away after a cyclone exists. So, lifetime of a cyclone is about a week or so. As it is known from the polar front theory, this strong horizontal temperature gradient results from the cold air from the Polar cell and the warm air from Ferrel cell moving towards each other and this movement develops a transition zone. If there is a convenient environment in the upper atmosphere, the pressure begins to drop, developing a low center at the surface, so cyclogenesis starts. The cold air moves to south and starts to rotate around warm air, forming a cold front, and the warm air moves north into the cold air, developing a warm front. While the system moves to the east, the central pressure keeps reducing and the cold front approaches to the warm front. Ultimately, the cold front cuts off the connection between the warm front and surface and goes under the cooler air ahead of the warm front, thus occluded front forms. This mature system covers a large area and vigorous weather events generally occur in the occlusion stage. The huge warm sea surface of the Mediterranean Basin immensely triggers cyclogenesis and evolutions of the cyclones. These cyclones can bring rain and snow in the form of flooding, snow storms and severe thunderstorm with hail. For instance, a long-running snowstorm hit Turkey on January 22nd, 2004 and it lasted until January 25nd. There were a lot of accidents, the power outage, and one of the rope of Bosphorus Bridge was broken. Shortly, life stopped in ˙ Istanbul and nearby cities for a few days. Purpose of this thesis is to identify the trajectories of cyclones affecting Turkey from two different reanalysis data sets. Detection of cyclone is achieved by The University of Melbourne automatic cyclone tracking scheme (CTS) using 6 hourly NCEP Reanalysis 2 and ERA-Interim mean sea level pressure field respectively at 2.5 x 2.5 and 1.0 x 1.0 spatial resolution for a region between 15◦W - 60◦E and 20◦N - 60◦N for 38 years (1979 - 2016). The first step is to transform latitude and longitude data into 101 x 101 polar stereographic (PS) array via bicubic spline interpolation. Smoothing is applied to ERA-Interim pressure field, however it is not preferred for NCEP 2 data because of its low spatial resolution. The local maxima of relative cyclonic geostrophic vorticity (x) value via the Laplacian of pressure is sought through comparing each grid point with surrounding eight grid points. If there is no closed depression reasonable distance (diflt1), scanning for minimum pressure gradient begins to find an open depression in closest allowable space (diflt2). There is no need to integrate the diflt1 parameter to ERA-Interim case after smoothing. Each cyclone is followed from the first moment of its formation to its perish. This procedure involves three steps. First one is estimating the subsequent positions of the centres. Second is looking for probability of a relations between the estimated position and the current position. The subsequent positions are predicted via prediction velocity (upred). Positions were estimated using upred. Final step is choosing most probable candidate for matching. Thus, this study shows that the most of the cyclones affecting Turkey are generally westerly and they follow a southerly trajectory in winter, however their trajectory shifts northward towards summer. Cyclones affecting Turkey generally originate in Gulf of Genoa, northern Italy, and the Black Sea, but there are other regions such as the Aegean Sea, Cyprus, and Sahara. However, some changes are seen season to season. Gulf of Genoa and northern Italy regions play major role for all seasons. In winter seasons, Turkey is also affected by southern Italy, the Aegean Sea and the Black Sea cyclones other than Gulf of Genoa and northern Italy cyclones. Sahara, Cyprus, the Aegean Sea, and the Black Sea are cyclogenesis regions in spring seasons. While winter cyclones traverse, summer cyclones are more stationary. Cyclones of Cyprus and the Black Sea have high intensity in summer season. In autumn seasons, cyclones of Sahara, Cyprus, and the Black Sea become pronounced. The results of NCEP2 and ERA-Interim are generally similar, however there are several differences between them. There are approximately 31% more tracks in the result of NCEP2 than ERA-Interim. In all seasons, there are more tracks in North Africa in ERA-Interim results than NCEP2. While there is a few tracks around Syria, Iraq, and Persian Gulf in ERA-Interim results, NCEP2 results has more tracks than ERA-Interim in these regions in the spring, summer, and autumn seasons. The average central pressure of cyclones is around 1010 hPa for ERA-Interim and 1009 hPa for NCEP2. While the mean cyclone intesity is 0.68 hPa(◦lat)−2 for ERA-Interim, it is obtained to be 0.53 hPa(◦lat)−2 for NCEP2. Also, the mean radius of the cyclones is around 4.10 ◦lat for ERA-Interim and it is found to be 4.08 ◦lat for NCEP2.