Bilge TUTAK, Yasemin EZBER, Mehmet ILICAK

Güney Okyanusunun Atmosfer ve Okyanus Sirkülasyonlarının Sayısal Modeller Yardımıyla İncelenmesi

Bu çalışmada amacımız, Güney Okyanusu üzerindeki rüzgar dinamiklerini ve bunun okyanus devinim sirkülasyonu üzerindeki etkisini incelemektir. Bu amaçla, atmosfer ve bileşik okyanus-deniz buzu yüksek çözünürlüklü bölgesel modelleri ayrı ayrı koşturulmuştur. 2007 ve 2013 yılları arasında eşzamanlı olarak üç benzetim gerçekleştirilmiştir. İlk benzetim, gözlemlenen deniz yüzeyi sıcaklığı ve deniz buzu konsantrasyonu tarafından zorlanan sadece atmosfer bölgesel modelidir. Model, ortalama deniz seviyesi basıncı, 2 metre hava sıcaklığı, yukarı atmosfer jetleri ve Stratosferik Polar Vortex gibi önemli atmosferik özelliklerin mevsimselliğini başarıyla yakalamıştır. Model, Antarktika'daki gözlem istasyonlarıyla uyumluluk göstermektedir. İkinci benzetim, reanaliz atmosferik veri seti ile zorlanan kontrol okyanus-deniz buzu bileşik bölgesel modeldir. Okyanus modeli, deniz yüzeyi sıcaklık gradyanını doğru şekilde yakalamayı başarmıştır. Drake Geçidi'ndeki taşınım değerleri gözlemler dahilinde yaklaşık 152 Sv'dir. Son olarak, Güney Okyanusu üzerindeki bölgesel rüzgar gerilmesinin 1,5 kat arttığı bir duyarlılık benzetimi de yapılmış ve daha güçlü Drake Geçidi taşınımı ve Deacon Hücresi sirkülasyonu gözlemlenmiştir. Bu çalışma ileride gerçekleştirilebilecek Güney Okyanusu tamamen bütünleşik atmosfer-okyanus modeli geliştirilmesi için kapasite ve kabiliyetlerin ortaya konmasını sağlamıştır.

Analysis of the Atmospheric and Oceanic Circulations of the Southern Ocean with the Help of Numerical Models

In this study, our aim is to investigate Southern Ocean wind dynamics and its impact on the ocean overturning circulation. To this end, we performed atmosphere and ocean-sea ice coupled regional high-resolution models separately. We conduct three concurrent simulations spanning between 2007 and 2013. The first simulation is atmosphere only regional model forced by observed sea surface temperature and sea ice concentration. The model successfully captures important atmospheric properties such as mean and seasonality of the sea level pressure, 2 meter air temperature, upper level jet, Stratospheric Polar vortex. The model compares well against the observation stations throughout the Antarctica. The second simulation is the control ocean-sea ice coupled regional model forced with reanalysis atmospheric dataset. In the ocean model, we capture the sea surface temperature gradient. The transport at the Drake Passage is around 152 Sv which is within the observation values. Finally, we conduct a sensitivity simulation where the zonal wind stress over the Southern Ocean is increased 1.5 times. This leads to stronger Drake Passage transport and Deacon Cell overturning circulation in the model. This study has provided to demonstrate the capacity and capabilities to develop a Southern Ocean integrated fully coupled atmosphere-ocean model that can be carried out in the future.

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