Sidney Uluslararası Havalimanı'nın (AMO) gök gürültülü fırtınalarının araştırılması
Analysis of thunderstorms at Sydney İnternational Airport (AMO)
Yazar: KÜBRA TURGUT
Danışman: DOÇ. DR. EMRAH TUNCAY ÖZDEMİR
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / İklim Bilimi ve Meteoroloji Mühendisliği Ana Bilim Dalı / Atmosfer Bilimleri Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: Meteoroloji = Meteorology

Özet:
Avustralya'nın Sidney Şehri'nde gök gürültülü fırtınalar Avustralya'da can ve mal güvenliği açısından ciddi bir tehdit oluşturmaktadır. Sidney Bölgesi için kaydedilen şiddetli fırtına raporlarından oluşan çok sayıda geniş bir veritabanı oluşturulduğu görülmüştür.  Birçok ülkede olduğu gibi Avustralya'nın Sidney şehrinde de meydana gelen gök gürültülü hava hadiseleri, günlük yaşamda meydana getirdiği önemli aksamalar, ekonomik zararlar, havacılık hizmetlerinde sebep olduğu birçok gecikme, erteleme ve uçuş iptalleri sebebiyle her yıl çok sayıda maddi ve manevi zarar yaşanmaktadır.  Sonuç olarak söylenilebilir ki gök gürültülü hava hadiselerinin meteorolojik açıdan incelenmesi bazı hükümet organları, sigorta şirketleri, havacılık hizmetleri, acil servis hizmetleri için de olumsuz hava koşullarına karşı alınabilecek önlemler ve maddi kayıpların önüne geçilebilmesi için alınabilecek kararlarda çok değerli bir kaynak görevi göreceğine kuşku yoktur. 
Bu çalışmada, 2005-2023 periyodu için gözlemlenen gök gürültülü fırtına hadiselerinin kullanıldığı veriler yardımıyla gök gürültülü hadiselerinin yaşandığı gün sayıları, süreleri belirlenerek trend eğilimleri oluşturuldu ve analiz edildi. Ele alınan gök gürültülü hadiseler hafif, orta ve şiddetli olmak üzere şiddetlerine göre gruplandırılmıştır. Orta şiddetli gök gürültülü fırtına hadiselerinin, orta ve hafif şiddetli hadiselerden daha çok meydana geldiği görülmüştür. Bu çalışmada Avustralya Meteoroloji Bürosu' nun Yeni Güney Galler (NSW) Bölge Ofisi'ne bağlı Sidney Havalimanı (AMO) tarafından düzenlenen METAR ve SPECI rasatları kullanılmıştır. Gözlemlenmiş fırtına gün sayılarının zaman serilerinde ve ortalama sürelerinde azalan bir trend eğilimi tespit edilmiştir. Mann-Kendall ve Sen'in Eğim Trendi yöntemi çalışmaları %5 anlamlılık düzeyinde gerçekleştirilmiştir. 
Bununla birlikte, her geçen gün dikkatleri üzerine daha da çeken iklim değişikliği konusuna ışık tutmayı hedefleyen, meteorolojik olayların tabiatını da göz önünde bulundurularak, değişikliklerin insan kaynaklı iklim değişikliğine ne kadar doğru atfedilebileceğini gösteren önemli çalışmalar vardır. Bu çalışmalara benzer şekilde, iklim değişikliği fenomeninin fırtına olayları ve iklim parametrelerine olan ilişkisini inceleyebilmek için günlük maksimum ve minimum sıcaklık (1946-2023), yağış (1954-2023) verileri de kullanılarak zaman serisi analizleri yapılmış ve sonuçlar ayrıntılı olarak incelenmiştir. Aylık analizlerde yağış ortalamalarının aydan aya ve zaman serileri boyunca farklılıklar gösterdiği gözlenmiştir. Sonuçlarda, minimum sıcaklıklarda yükselişe işaret eden bir durumun varlığı gözlemlendi. Kaydedilen gök gürültülü hadiseli gün sayılarından elde edilmiş zaman serilerinde azalış trendleri gözlenmiş fakat toplam TS hadisesi sayılarında bir trend varlığı gözlemlenmemiştir.

Abstract:
Thunderstorms occurring in Sydney, Australia, as in many parts of the world, pose a serious threat to the life and property safety of the local people and cause many material and moral damages. It has been observed that a large database consisting of severe storm reports recorded for the Sydney Region has been created. As in many countries, thunderstorms occurring in Sydney, Australia, cause significant disruptions in daily life, economic losses, and many delays, postponements and flight cancellations in aviation services, which cause a large number of material and moral losses every year. As a result, it can be said that the meteorological examination of thunderstorms will undoubtedly serve as a very valuable resource for some government bodies, insurance companies, aviation services and emergency services in taking precautions against adverse weather conditions and in making decisions to prevent material losses. 
Sydney International Airport (AMO) is one of the longest continuously operated commercial airports in the world, and is the busiest airport in Australia, where more than three hundred thousand flight activities are coordinated, making it increasingly important for Sydney's growing population. Due to all these features, Sydney Airport was chosen as the study area. Considering the consequences of severe weather events, adverse weather conditions are linked to the dangers they create in the aviation sector, and considering the importance of the region in terms of socio-economic aspects, researchers believe that a study on this subject can be a resource that institutions can benefit from in order to make airports and flight operations more prepared within the scope of civil aviation security measures, to strengthen the regional infrastructure against extreme weather events, and to plan awareness and education activities so that the society can be more prepared against extreme weather events.
In this study, the number of days and durations of thunderstorms were determined with the help of data used for the period 2005-2023, and trend trends were created and analyzed. The thunderstorms examined were grouped according to their severity as light, moderate and severe. It has been observed that moderate thunderstorm events occur more frequently than moderate and light events. METAR and SPECI observations organized by the Sydney Airport (AMO) affiliated with the New South Wales (NSW) Regional Office of the Australian Bureau of Meteorology were used in this study. A decreasing trend trend was detected in the time series and average durations of the observed storm days. Mann-Kendall and Sen's Slope Trend method studies were carried out at a significance level of 5%.
 However, there are crucial studies that aim to shed light on the issue of climate change, which attracts more and more attention every day, and show how accurately the changes can be attributed to human-induced climate change, considering the nature of meteorological events. Similar to this kind of studies, time series analyses were implemented using both daily maximum and minimum temperature values between (1946-2023) time period and precipitation (1954-2023) data in order to examine the relationship between the climate change phenomenon and storm events and climate parameters, and the results were examined in detail. In monthly analyses, it was observed that precipitation averages varied from month to month and throughout the time series. In the results, a situation indicating an increase in minimum temperatures was observed. It can be said that a decreasing trend was observed in the time series obtained from the recorded number of thunderstorm days, while no trend was observed when the time series of the total number of TS events was examined.
For the examined Sydney airport temperature values between 1946-2023, the lowest minimum temperatures were seen in July and August, while the highest minimum temperatures were seen in January and February. An increase in minimum temperature averages was observed over the years. It should not be ignored at this point that, contrary to what is experienced in the Northern Hemisphere, winter is experienced in Australia in June, July and August, and similarly, summer is experienced in Australia in December, January and February.
When looking at the daily minimum temperature averages for many years, it was seen that the temperatures varied between 11,9°C and 15,3°C. The highest daily minimum temperature average was determined as 15.3 °C in 2016. The lowest minimum temperature average was calculated as 11,9 °C in 1960.
When looking at the daily maximum temperature averages for many years, it was seen that the temperatures varied between 21,2 °C and 24,5°C. The highest temperature average was determined as 24,5 °C in 2019. The lowest maximum temperature average was calculated as 21,2 °C in 1949.
For the examined Sydney Airport rainfall data values for the years 1954-2023, the minimum rainfall in the total rainfall time series was observed in September, which is the spring month, and the maximum total rainfall was measured in March. The highest rainfall value in the total rainfall time series was measured as 2276 mm in 2022, and it is noteworthy that this value is considerably higher than other years. The distribution and total numbers of all TS, VCTS, -TSRA, -TSGRRA, TSRA, TS, TSGRRA, +TSRA, +TSGRRA events observed between 2005-2023 are presented in order. In the TS Series graphs created by classifying according to their severity, it was seen that moderate events were more numerous than light and severe events. The number of days with all observed thunderstorm events was determined, classified according to their types, and storm events that occurred by year and month were shown in tables and graphs. When comparing all months within the given period, when the number of days in which any TS event occurred was examined, it was seen that the highest number of days with events was December and the total number of days with events in all December months was 119 days. Again, when all months were examined separately between 2005 and 2023, the highest number of days with events belonged to December 2014 and the total number of days was 14 days. The highest weather event was seen in 2007 and the number of days with events was 64. The least number of days with TS events was calculated as 23 days in July. When comparing between years, the lowest number of days with events in the examined time period were in 2011 and 2019. A total of 28 days of thunderstorm weather events were encountered in 2011 and 26 days in 2019. The average number of days with storm events was calculated for the twelve months of the year. The highest average is December and the lowest average is July.
The average duration of storm events for twelve months of the year was calculated. The highest average duration is February, and the lowest average duration is July.
The Mann-Kendall and Sen's Slope method was applied to the number of days with annual TS events by performing trend analysis. As a result of the trend analysis applied to the annual number of days with TS events and average TS times, a decreasing trend was observed. When the changes in TS events were examined on a yearly basis, no trend was detected.
In this study, looking back from the year 2023, which is the year the thesis was written, the important meteorological events that occurred in the study area in the last ten years were examined. During this period, the thunderstorm and storm event that occurred on October 14, 2014, which was seen in Sydney and made its effect felt in a wide area, attracted attention and the weather analysis was examined in detail. It was considered important because it caused disruptions in daily life, economic damages, and various grievances for the local people due to the weather event that occurred and it was desired to be examined from a meteorological perspective. In the warning issued on Tuesday, October 14, 2014, at 23:04, when the incident occurred, people were warned to move their cars to a safe area, stay away from fallen power lines, stay away from stream banks and rainwater drains, not walk in flood waters, avoid using vehicles such as cars and bicycles as much as possible, and keep children and pets at home, among other vital warnings. Due to the severe event, high wind speeds and high rainfall amounts were recorded for different parts of the city. This event, which was examined as a case study, seriously affected the flight operations in the region and caused many flights to be canceled. The extreme rainfalls and maximum wind gust values exceeding 115 km/h that occurred with the storm negatively affected life. When we examined the 9-year maximum wind gust values of the airport in Sydney, it was recorded that the highest gust value, 57 knots, was measured at Sydney Airport. Watamolla recorded winds of 161 km/h (87 knots) at 21:00. Kurnell recorded winds of 115 km/h (62 knots) at 20:52. Sydney International Airport (AMO) recorded winds of 98 km/h (53 knots) at 21:17. San Souci recorded 59 mm of rain in an hour between 20:00 and 21:00, and Strathfield areas recorded 50 mm of rain in an hour between 21:00 and 22:00.
The most striking results of the analyses are the increase in minimum temperature averages over time, the differences in the amount of rainfall at Sydney Airport (AMO) in the category of the region with uniform precipitation throughout the time series, the fact that moderate thunderstorms occurred more than light and severe thunderstorms, and the decreasing trend in the number of days and durations of TS events over time. These differences observed from year to year in the Sydney Airport (AMO) climate data analyses should not be ignored due to the fact that the temperature, rainfall differences observed in Australia or the changes observed in storm events are under the influence of many climate factors in the region. To explain more clearly, the fact that the region is under the influence of many systems such as tropical cyclones, cut-off, frontal systems, blocking effect, and east coast low effect, in addition to El Nino and La Nina periods, causes serious effects on the thunderstorms, temperatures, destructive winds, excessive rainfall, and floods. As a result, all these effects have a critical effect on the thunderstorms that occur, which directly affect the flight operations of Sydney Airport (AMO) and the lives of the population of the city of Sydney. Therefore, the trend analyses and other analyses conducted in this study, although not a direct reference, will provide an important perspective and ideas to those concerned.