Orta atmosferik ozon, sıcaklık ve potansiyel vortisiti ilişkisinin incelenmesi
Investigation of the relationship of middle atmospheric ozone, temperature and potential vorticty
Yazar: EBRU KAPLAN
Danışman: DR. ÖĞR. ÜYESİ DENİZ DEMİRHAN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Meteoroloji Mühendisliği Ana Bilim Dalı / Atmosfer Bilimleri Bilim Dalı
Derece: Yüksek Lisans, 2021
Konu: Meteoroloji = Meteorology

Özet:
Ozon, hem troposferde hem de stratosferde bulunan renksiz ve kokusuz bir gazdır.. Troposferik ozon toplam ozonun yaklaşık %10'unu stratosferik ozon ise atmosferdeki ozonun %90'ını oluşturmaktadır. Ozon konsantrasyonunun en fazla olduğu yükseklik 20 km ile 25 km arasıdır. Ozonun çoğu aşağı stratosferde bulunduğundan bu bölge atmosferde toplam ozonu temsil edebilmektedir.  Stratosferik ozon, güneşten gelen ve canlılar için zararlı olan ultraviyole radyasyonu (UV-B ve UV-C) absorbladığı için oldukça önemlidir. Bundan dolayı stratosferdeki ozonda meydana gelen azalma canlılar için tehdit oluşturmaktadır. Ozon üretiminin büyük bir kısmı tropikal stratosferde 20 km ile 50 km arasında meydana gelmektedir. Güneş radyasyonu ile reaksiyona giren Oksijen molekülleri (O2), parçalanarak Oksijen atomlarını (O) oluşturur ve bu O, diğer O2 molekülleri ile reaksiyona girerek ozonu (O3) oluşturmaktadır. Güneş radyasyonu ozon oluşumundaki temel bileşen olmasına rağmen ozonun büyük bir çoğunluğu yukarı enlemlerde bulunur. Bu durum, tropik enlemlerden orta enlemlere ve kutup enlemlerine doğru hareket eden atmosferik dolaşımdan kaynaklanır. Bu dolaşım Brewer Dobson sirkülasyonu olarak adlandırılır. Brewer Dobson sirkülasyonu üç bölümden oluşur. Birincisi troposferden stratosfere doğru olan tropiklerdeki harekettir. İkincisi stratosferden kutuplara doğru olan taşınımdır. Üçüncüsü ise orta ve polar enlemlerde meydana gelen inici harekettir. Orta enlemlerde alçalan bu hava tekrar troposfere taşınırken kutup enlemlerinde aşağı doğru hareket eden  hava ise alt stratosfere taşınır. Güney Yarım Küreye göre Kuzey Yarım Kürede Brewer Dobson sirkülasyonu daha güçlü olmaktadır. Bunun sebebi ise Güney Yarım Kürenin çoğunlukla okyanuslara kaplı olması fakat Kuzey Yarım Kürede sirkülasyonu etkileyecek dağların ve karaların bulunmasıdır.
Yapılan çalışmalarda, potansiyel vortisiti ile ozon  karışm oranı arasıda bir ilişki olduğu gösterilmiştir. Ozon miktarı ile potansiyel vortisiti arasında pozitif  bir korelasyon bulunmaktadır. Aynı zamanda ozon değişiminin olduğu bölgeyi belirlemek için de potansiyel vortisiti kullanılmaktadır.
Stratosferdeki ozonda meydana gelen değişimler ile ilgili yapılan çalışmalarda bu değişimin sadece kimyasal süreçlerle yönetilmediği, dinamik ve termal etkilerin de oldukça önemli olduğu bilinmektedir. Bundan dolayı ozondaki değişimler incelenirken sıcaklık ve potansiyel vortisitide meydana gelen değişimlerin de incelenmesi ve ortak bir sonuca varılması oldukça önemlidir.
Bu çalışmada 1979-2019 yılları arasında, 10 hPa, 30 hPa ve 100 hPa seviyelerindeki aylık ortalama ozon karışma oranı, sıcaklık ve potansiyel vortisi için ERA-5 verileri kullanılmıştır. Çalışmanın amacı ozon karışma oranı, sıcaklık ve potansiyel vortisiti arasındaki ilişkinin incelenmesidir. 5°N-95°N enlemleri ile 0°-360° boylamları arasında kalan alan için 10 hPa, 30 hPa ve 100 hPa seviyesindeki sıcaklık ve ozon karışma oranı haritaları çizdirilmiştir. Burada sıcaklık ve ozon karışma oranı arasındaki ilişki incelendiğinde en belirgin değişimlerin 55°N- 65°N enlemleri arasında olduğu görülmüştür. 55°N-65°N enlemleri arasında kalan bölge altı alana bölünerek daha detaylı bir inceleme yapmak amaçlanmıştır. Bu altı alan hem 10 hPa hem 30 hPa hem de 100 hPa seviyesi için oluşturulmuştur. Bu alanlar 55°-65° Kuzey enlemleri ile 120°-180° Batı boylamları arası, 55°-65° Kuzey enlemleri ile 60°-120° Batı boylamları arası, 55°-65° Kuzey enlemleri ile 0°-60° Batı boylamları arası, 55°-65° Kuzey enlemleri ile 0°-60° Doğu boylamları arası, 55°-65° Kuzey enlemleri ile 60°-120° Doğu boylamları arası ve 55°-65° Kuzey enlemleri ile 120°-180° Doğu boylamları arası şeklindedir. Bu alanlar için 10 hPa, 30 hPa ve100 hPa seviyesindeki ozon karışma oranı, sıcaklık ve potansiyel vortisitinin ortalamadan sapmalarının yıllara göre değişimini gösteren grafikler oluşturulmuştur. 
Bunlara ek olarak ozon ile sıcaklık ve ozon ile potansiyel vortisiti arasındaki ilişkiyi incelemek için Durbin Watson regresyon analizi yapılmıştır. Bu analizi yapabilmek için en küçük kareler yöntemi kullanılmıştır. Bu analiz 10 hPa, 30 hPa ve 100 hPa seviyeleri için ayrı ayrı uygulanarak grafikler elde edilmiştir. Bu şekilde ozon ile sıcaklık ve ozon ile potansiyel vortisiti arasındaki korelasyonu incelemek amaçlanmıştır.

Abstract:
Ozone is found in both the troposphere and the stratosphere. Tropospheric ozone accounts for about 10% of total ozone. Stratospheric ozone, on the other hand, constitutes approximately 90% of ozone in the atmosphere. The greatest ozone concentration is between 20 km and 25 km in the stratosphere. Since most of ozone is found in the lower stratosphere, ozone in the lower stratosphere represents a large-scale ozone distribution. Stratospheric ozone is very important because it absorbs ultraviolet radiation (UV-B and UV-C) from the sun, which is harmful to living things. Therefore, the decrease in ozone in the stratosphere poses a threat to living beings. 
The majority of ozone production occurs between 20 km and 50 km in the tropical stratosphere. With the sun, O2 molecules are broken down to form O atoms, and these O atoms interact with other O2 molecules to form ozone (O3). But the vast majority of ozone is found in the upper latitudes. This situation is caused by atmospheric circulation moving from tropical latitudes to mid latitudes and polar latitudes. This circulation is called the Brewer Dobson circulation. Brewer Dobson circulation consists of three branches. The first branch is the movement in the tropics from the troposphere to the stratosphere. The second is the transport from the stratosphere to the poles. The third branch is the descending motion that occurs in middle and polar latitudes. While this air descending in middle latitudes, it is carried back to the troposphere, the air descending in polar latitudes is carried to the lower stratosphere. Brewer Dobson circulation is stronger in the Northern Hemisphere than in the Southern Hemisphere. The reason for this is that the Southern Hemisphere is mostly covered by oceans, but there are mountains and lands in the Northern Hemisphere that affect circulation.
Studies have shown that there is a relationship between potential vorticity and ozone mixing ratio. There is a positive correlation between the amount of ozone and its potential vorticity. At the same time, potential vorticity is used to determine the region of ozone exchange.
In studies conducted on the changes in the amount of ozone in the stratosphere, it has been suggested that this change is not only managed by chemical processes, but also dynamic and thermal effects. Therefore, when examining the changes in ozone, it is very important to examine the changes in temperature and potential vorticity and to reach a common conclusion.
In this study, ERA-5 data were used for the monthly average ozone mixing ratio, temperature and potential vortex at 10 hPa, 30 hPa and 100 hPa levels between 1979 and 2019. The aim of the study is to examine the relationship between ozone mixing rate, temperature and potential vorticity. Temperature and ozone mixing ratio maps at 10 hPa and 100 hPa levels were drawn for between 5°N-95°N latitudes and 0° -360° longitudes. When the relationship between temperature and ozone mixing ratio is examined here, it is seen that the most significant changes are between 55°N and 65°N latitudes.  It was aimed to make a more detailed investigation by dividing the region between 55°N-65°N latitudes into six areas. These six fields were established for both the 10 hPa and 100 hPa level. These areas are between 55°-65° north latitudes and 120°-180° west longitudes, 55°-65° north latitudes and 60°-120° west longitudes, 55°-65° north latitudes and 0°-60° west longitudes 55°-65° north latitudes 0°-60° east longitudes, 55° -65° north latitudes 60° -120° east longitudes and 55°-65° north latitudes 120°-180° east longitudes. For these areas, graphs were created showing the deviations of ozone mixing ratio, temperature and potential vorticity from the average at both 10 hPa and 100 hPa levels by years
In addition, Durbin Watson regression analysis was performed to examine the relationship between ozone and temperature, and ozone and potential vorticity. Least squares method was used to make this analysis. The m and b values were found using the least squares method. In this way, estimated temperature data were obtained primarily by using ozone data. Then, the estimated temperature values were subtracted from the temperature values and error calculation was made. The obtained errors were squared and collected. At the same time, each error was subtracted from the previous one, squared and summed. Finally, the Durbin Watson Regression number was obtained by dividing the sum of squares of the errors by the sum of squares of the differences. The same procedures have been done for ozone and potential vorticity. The results obtained should be between 0 and 4. If it is between 0 and 2, it means there is a positive autocorrelation. A value between 2 and 4 indicates negative autocorrelation. The fact that it is 2 means that there is no relationship between them. Graphs were obtained by applying this analysis separately for 10 hPa, 30 hPa and 100 hPa levels. In this way, it is aimed to examine the correlation between ozone and temperature and ozone and potential vorticity.
As a result of the examination of the ozone mixing ratio map drawn for 10 hPa, 30hPa and 100 hPa levels, it is seen that the ozone mixing ratio starts to decrease with April and increase with November in upper latitudes. Near the Equator, the highest values are observed in July and August, and it is observed that the ozone mixing rate has started to decrease as of October. The increase in the rate of ozone mixing in the upper latitudes in October is associated with the strengthening of the Brewer Dobson Circulation with the decrease in temperatures. As the Brewer Dobson circulation gets stronger, ozone transport occurs from the equator to the upper latitudes and upper levels. As of April, the rate of ozone mixing in the upper latitudes decreases, which is due to the decrease in the Brewer Dobson circulation and the lowest ozone transport from the equator to the upper latitudes.
When the temperatures of 10 hPa, 30hPa and 100 hPa are examined, the cooling in the upper latitudes in October is clearly seen. In addition, while the lowest temperatures are observed around Gronland and the Arctic Ocean during the winter months, it is observed that the temperatures are higher in the Pacific Ocean coasts of Alaska and Russia. The reason for the formation of this area is that the intense jet streams formed during the winter months carry the air in the troposphere to the stratosphere. Jet streams are very effective on the Pacific, especially in the Northern Hemisphere, and carry the troposphere air to the stratosphere during the winter months, where warming occurs. It is seen that the highest temperatures in the upper latitudes are in June and July.
As a result of Durbin Watson regression analysis between 55°N - 65°N  latitudes and 10 hPa level ozone and temperature, it is seen that there is a negative autocorrelation between ozone and temperature between 120°W - 180°W longitudes, but the value obtained is very close to 2. It also means that there is almost no relationship between ozone and temperature. When the other longitude intervals are examined, the values obtained indicate that there is a positive autocorrelation between ozone and temperature.
When Durbin Watson regression analysis is performed for ozone and temperature at latitudes 55°N - 65°N and 30 hPa, it is seen that there is almost no relationship between ozone and temperature between 120° - 180°W longitudes. It was concluded that there is a positive autocorrelation between temperature and ozone: for the areas formed by 60° - 120° and 0° - 60°W longitudes and 120° - 180° E longitudes with 55° - 65° N latitudes. The value obtained for 0° - 60° and 60° - 120° E longitudes is over 2. This situation indicates a negative autocorrelation between ozone and temperature. 
When a regional Durbin Watson regression analysis is performed between temperature and ozone at 100 hPa level and latitudes 55°N - 65°N, the Durbin Watson regression value between 60°E - 120°E longitudes is less than 2 indicates that there is a positive autocorrelation between ozone and temperature in this region. . It is seen that Durbin Watson regression values calculated for all other regions are above 2. This indicates that there is a negative autocorrelation between ozone and temperature in other regions.
As a result of Durbin Watson regression analysis performed for ozone and potential vorticity at latitudes 55°N - 65°N and 10 hPa levels, it was seen that the regression value was less than 2 in the areas between 60°W - 120°W and 60°E - 120°E longitudes. . This means that there is a positive autocorrelation between ozone and potential vorticity. In other areas, regression values are greater than 2. In these areas, there is a negative correlation between ozone and potential voticity. 
Durbin Watson regression values obtained between 1979-2019 to examine the relationship between 30 hPa level ozone and potential vorticity show that there is almost no relationship between ozone and potential vorticity in areas formed by longitudes 120 ° -180 ° and 60° - 120° west. In the analysis performed for the areas formed by 0° - 60° west longitudes, 0° - 60° and 120° - 180° east longitudes 55° - 65° north latitude, it is seen that there is a positive autocorrelation between ozone and potential voticity. As a result of the analysis performed for 60° - 120° east longitudes, it is seen that there is a negative autocorrelation between ozone and potential vorticity.
As a result of Durbin Watson regression analysis performed for ozone and potential vorticity at 55°N - 65°N latitudes and 100 hPa level, it was seen that the regression value was over 2 in the area between 120°E - 180°E longitudes. This indicates that there is a negative autocorrelation between ozone and potential vorticity. Durbin Watson regression values are less than 2 in all other areas. This shows that there is a positive autocorrelation between ozone and its potential vorticity.