Türkiye'yi etkileyen sinoptik sistemlerin klimotolojisi
Climatology of synoptic systems affecting Turkey
Yazar: ALİ DENİZ
Danışman: PROF. DR. FEVZİ ERDOĞMUŞ
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Meteoroloji Mühendisliği Ana Bilim Dalı
Derece: Doktora, 1997
Konu: Meteoroloji = Meteorology
Dizin: Klimatoloji = Climatology ; Sinoptik sistemler = Synoptic systems

Özet:
ÖZET Bu çalışmada 1979-92 yıllan arasındaki 14 yıllık yer ve 500 mb sinoptik kartlar sübjektif yöntemle incelenerek siklon yörüngelerinin tespiti ve analizi yapılmıştır. Türkiye'yi etkileyen siklonların yörüngeleri genel olarak 4 farklı gruba ayrılmış ve bu yörüngelerden hangilerinin Türkiye'nin hangi bölgelerini etkilediği araştırılmıştır. Farklı yörüngelere ait siklon frekansları da aylık, mevsimlik ve yıllık olarak tespit edilmiştir. Türkiye'deki atmosferik paternlerin klimatolojisini ortaya koymak için Avrupa Orta Vadeli Hava Tahmin Merkezinden (ECMWF) sağlanan ortalama deniz seviyesi basınçları ve standart basmç seviyelerine ( 850, 700, 500 ve 250 mb) ait jeopotansiyel yükseklik verileri kullanılmıştır. Böylece aylık, mevsimlik ve yıllık bazda klimatoloji ve anomali haritaları oluşturulmuştur. 250 mb jeopotansiyel yükseklik verileri kullanılarak geostrofik rüzgar hesaplamaları yapılmış ve siklon sayıları, engelleme olaylarının meydana geliş sayıları ve kalış sürelerine bağlı olarak subtropikal jetin enlemsel değişimi çoklu regresyon analizi yöntemiyle tespit edilmiştir. Böylece Türkiye için bir jet indeksi geliştirilmiştir. Siklon frekansları ve yörüngeleri, engelleme sayılan ve süreleri ile yağış ve hava kirliliği arasındaki ilişkilere bakılmışta. Aynca 500 ve 700 mb standart basmç seviyeleri için jeopotansiyel yükseklik verileri kullanılarak yıllık ve aylık bazda korelasyon haritalan elde edilmiştir. Farklı 4 yörüngeye ait istasyonların siklon sayılan ile yağış arasındaki korelasyonlar hesaplanmıştır. Son olarak 1985-93 periyodu için nüfusu 100.000'nin üzerinde olan yerleşim merkezlerindeki hava kirleticileri (SO2 ve Asılı Partiküler Madde) ile siklon yörüngeleri ve engelleme olaylan arasındaki ilişkiler araştırılmıştır.

Abstract:
SUMMARY Many Studies have been conducted about cyclone frequencies and tracks. In the literature the studies about cyclone tracks and frequencies are focused on winter and spring instead of summer and autumn. In this work, "Meteorologische Abhandlungen" published by "Frei Universitat Berlin, Institut fur Meteorologie" in Germany is used to determine cyclone tracks and frequencies. The cyclone frequencies and tracks are defined according to the source regions by analysis of daily maps of 500 mb geopotential and surface maps at 07 UTC for the period of 1979-1992 (14 years). During the conflicting conditions the upper air maps are also investigated. In general, the tracks of cyclones that have been effective on Turkey are classified in four groups..These are: 1) Trajectories of cyclones that are created over Northern Europe and pass over Black Sea coasts. 2) Trajectories of cyclones that develop over Balkan Region and affect Marmara Region and the coastline of West Black Sea region. 3) The cyclogenesis of Genoa Gulf often follows two type paths: a) The cyclones that form over Genoa Gulf and effects the Northern parts of Aegean region almost the whole of Marmara region and Western Black Sea region come over Turkey via following a trajectory over Northern Mediterranean Sea. b) The cyclones that are generated over Genoa Gulf and effects middle Aegean region inland Anatolia and East Black Sea region come over Turkey by following a trajectory over middle Mediterranean Sea. 4) Trajectories of cyclones that are created over West or Middle Mediterranean Sea, or in some cases over Genoa Gulf and by moving towards East Mediterranean Sea effects Mediterranean coastline and southeast Anatolian region of Turkey. These cyclones sometimes pass over Cyprus.If you look at annual variability of cyclones we can see that the maximum number of the cyclones (68) was detected in 1980 and 1983 and the minimum number of cyclones (46) was observed in 1989 and 1992. During these 14 years period a decreasing trend can be detected. This result of the minimum number of cyclones observed in summer and the maximum number of cyclones monitored in winter is an expected one. It is interesting to have maximum number of cyclones in December with a number of 94 although there is decreasing trend in the number of cyclones in summer and winter, no any significant trend can be detected in spring. In the case of autumn where is a slightly increasing trend. The main trajectory of cyclones that is influencing Turkey is formed in the Genoa Gulf and passes over Aegean Sea, inland Anatolia region and Eastern Black sea, i.e. the trajectory classified as 3b. The lowest number of cyclones is associated with the first trajectory. According to the annual variability of cyclone frequencies there is decreasing trend in the cyclone tracks of 1, 2, 3a and 4, but disobeying this law there is a slightly increasing trend in the number of cyclones of the track 3b. In the track 3b there is a decrease in the total number of cyclones since 1984. This condition explains the drought of the period 1989-92 over Istanbul and over its neighboring regions to a certain extends. In this study, in order to produce the atmospheric patterns of certain parameters over Turkey, again, the data of European Center Middle Weather Forecast (ECMWF) is used. The initial daily data consisting of l°xl° grid intervals is converted into 2°x2° grid data of monthly values. This transformation is carried out owing to inadequacy of the computer power. The monthly data base of ECMWF sea level pressure and the geopotential height of the standard pressure levels (850, 700, 500 and 250 mb) the period of data for the mean sea level is 1983-94 (12 years) and for the geopotential heights of standard pressure levels is 1980-94 (15 years) related investigated area that have data is located between 20 °N - 76 °N latitudes and 40 °W - 80 °E longitutes. This region includes a large area that Turkey is also located. Thus, they are 29x61=1769 grid points of 2°x2°. The frequency and residence periods of the blocking events that are persistent 5 days or more are determined by investigating the German surface and 500 mb maps in the period of 1979-94. The monthly and also the annual analysis reveal that there is an increasing trend in the numbers and the residence periods of the blocking events.?£2urcttaM«flKra'3tfS^ imhmmweii* ^?^^?İ^HMaaHM MHMHWtf For the same period there is a decreasing trend monthly and the annual time series of the cases of cyclones. This expected result confirms the result of conducted research. So, one can talk about a negative relationship between the cyclone numbers and the numbers of blocking. Some correlation is valid also for seasonal analysis. After words, the studies will be conducted can benefit from the various forms of blocking events. In order to determine the relationship between cyclone frequencies and the precipitation, the precipitation data of 84 station located of the Turkey for the period of 1979-92 (14 years) is used. These precipitation series are subjected to Swed- Eisenhart and Kruskal-Wallis homogenety tests. Inhomogeneous series are extracted from the analysis. The frequencies of the cyclones affecting Turkey are illustrated seasonally for five different tracks. The main trajectory of cyclones that is influencing Turkey is created in the Genoa Gulf and passes over Middle Aegean, inland Anatolia and Eastern Black Sea and follows the path of 3b. The minimum number of cyclone cases is observed on the first trajectory. Although there is a decreasing trend in the cyclone tracks of 1, 2, 3 a and 4, there is slightly increasing trend in the number of cyclones of the tracks 3b. Two precipitation stations are randomly selected in the influential are of each trajectory. When we compare the cyclones and the precipitation data, we can detect a positive relationship between precipitation and the frequency of the low pressure systems. We determined the correlations between precipitation amounts and cyclone frequencies for each trajectory and for winter, spring and autumn. It is possible to stayed that the most important trajectories that produce highest precipitation on Turkey are 3b and 3a, in order, and those that produce lowest amounts of precipitation are 1, 2 and 4. In summer season lower correlation values than compared with the other seasons can be detected almost for all trajectories. The main case of this is the dominance of the convective precipitation to the cyclonic and frontal precipitation. In order to predict the relationship of this cyclonic system affecting Turkey with the other systems in the research region, correlation maps for 500 and 700 mb standard pressure levels are produced. For the related standard pressure levels annual and monthly correlation maps representing seasons (January, April, July and October) in the period of 1979-94 are produced by using geopotential height data. In order to produce correlation maps a standard grid point located on 40 °N latitude and 28 °E xivlongitude over Turkey in close proximity to Istanbul was chosen. Geopotential height time series of this point and those of 1768 grid points are investigated and their correlation with each other is estimated. It is found that there is not great difference between the correlation maps of 500 and 700 mb on the monthly basis and also annual basis. In all the correlation maps the correlation coefficients above 0.90 is associated with the source regions of the cyclone tracks and their associated trajectories. The relationship between blocking event, cyclone frequencies and precipitation with the maximum active El-Nino years are determined. For this purpose the warm and the cold years of El-Nino inside the research period is selected as 1982 and 1988, respectively. It is intuitively clear that there is a negative correlation between the numbers and durations of blocking event and the number of cyclones for both warm and cold years. In the warm year (1982) high number of cyclones were found to be associated with low number of blocking events and a decrease in the average precipitation over Turkey was detected. Contrary, in the cold year (1988) low number of cyclones were found to be associated with high number and duration of blocking events and an increase in the average precipitation over Turkey was observed. Thus for this research period, a close relationship between the cyclone frequencies affect Turkey, the number and duration of blocking events and precipitation with ENSO is obvious. But in order to generalize these results, data with much longer period is necessary. In order to estimate the variation of the axis of subtropical Jetstream, ECMWF 250 hPa geopotential heights for the 1979-94 period obtained for the 1769 grid points lying on the latitudinal interval 20°-76°N and longitudinal interval 40°W-80°E is used. From the data the geostrophic wind patterns are obtained, and the referance latitude for the estimations is accepted as 40 °N. The variation of the subtropical Jetstream is estimated by using the 40 °N referance latitude and a main interval window located on 20-38 °N latitudes and 16-60 °E longitudes. To detect whether there is a structure disorder interrupting the general variability in the windowing system or not, six different windows in the main window are taken. The variability of the subtropical Jetstream in each window is investigated and it is found that the general variability is kept intact.The variation of the subtropical Jetstream latitude is analyzed by multi-variate regression involving cyclone numbers, blocking numbers and their persistence periods. The established equation showing the variability of the Jetstream axis on a monthly basis is as follows: Y = 34.477572 + 0.069357 Xx - 0.015493 X2 - 0.0582 X3 Where Xf. The number of the observed blocking cases over Turkey X2: The period of the observed blocking cases over Turkey X3: The number of the observed cyclones. The obtained above formula is calibrated by comparing it with the equation of the variation of the Jetstream axis as explained in the methodology section. Thus by putting the related variables into the equation, monthly Jetstream index can be generated. Finally in this research, the relationship between air pollutants (S02 and TSP) with cyclone frequencies, trajectories and blocking events are investigated over 59 residence centers having populations over 100.000 located on Turkey. In the air pollution studies the number of blocking events are important as well as their duration. The number of blocking events that are occuring over Europe have less influence than the duration of the blocking event as far as cyclonic passages over Turkey is considered.