Objektivna klasifikacija atmosferske cirkulacije iznad Srbije

Abstract

Vreme i klima neke oblasti odraz su na prvom mestu osobenosti opšte cirkulacije atmosfere. Promene u atmosferskoj cirkulaciji su presudne zato što su one često praćene promenama u površinskim meteorološkim promenljivama. Da bi se lakše proučavala veza između atmosferske cirkulacije i lokalnih vremenskih uslova, vrši se klasifikacija sinoptičkih sistema, tj. određuju se tipovi cirkulacije. Zato je glavni cilj ove disertacije da se na objektivan način identifikuju i opišu tipovi cirkulacije koji karakterišu vremenska stanja iznad Srbije. Proučavanje tipova cirkulacije je aktuelna tema, koja se stalno unapređuje i dopunjuje. Metod Jekinson-a i Collison-a je objektivna verzija Lamb-ove klasifikacije atmosferske cirkulacije, gde je dnevna cirkulacija okarakterisana upotrebom indeksa povezanih sa pravcem, jačinom i vrtložnošću strujanja. Ovaj metod je bio primenjen iznad Srbije za period od 1961. do 2010. Dobijeno je dvadesetšest cirkulacionih tipova: osam usmerenih tipova po pravcu − severni (N), severoistočni (NE), istočni (E), jugoistočni (SE), južni (S), jugozapadni (SW), zapadni (W) i severozapadni (NW), zatim dva vrtložna tipa zasnovana na jačini vrtložnosti − ciklonalni (C) i anticiklonalni (A) i šesnaest hibridnih tipova (osam ciklonalnih i osam anticiklonalnih za svaki pravac). Sinoptičke karakteristike dobijenih tipova su razmatrane za sve četiri sezone. Svaki cirkulacioni tip ima poseban sinoptički obrazac koji daje očekivan tip i smer strujanja iznad posmatrane oblasti. Analizirani su i trendovi i relativne učestalosti cirkulacionih tipova. Mana metoda Jekinson–a i Collison–a je što nema podataka na višim nivoima. Ovaj nedostatak je rešen u disertaciji tako što su analizirane anomalije geopotencijalne visine na 500 hPa. Utvrđeno je da je anticiklonalni (A) cirkulacioni tip najučestaliji u jesen (23,87%), zatim zimi (18,93%) i u leto (18,70%). Sledi severoistočni tip (NE) sa čestinom od 16,65% za vreme letnje sezone. A tip ima pozitivan trend za zimu i proleće i statistički značajan negativan trend za jesen i leto. C tip pokazuje značajno negativan trend samo u proleće...

One of the primary dynamic factors shaping weather and climate of an area is the atmospheric circulation. Regional or local changes in meteorological parameters in the mid-latitudes are mainly controlled by the atmospheric circulation. In order to study relationships between atmospheric circulation and local weather conditions, classification of the synoptic systems is conducted, i.e., circulation weather types (WTs) are determined. Therefore, the main goal of this thesis is to objectively determine and explain the circulation weather types over Serbia. Studying of circulation types is a current topic that is constantly improved and updated. The method of Jenkinson and Collison is an objective version of the Lamb’s classification of atmospheric circulation, in which daily circulation is characterized using a set of indices associated with the direction, strength and vorticity of the flow. This method has been applied to the atmosphere over Serbia for the time period 1961- 2010, resulting in 26 WTs: eight pure directional types - northerly (N), northeasterly (NE), easterly (E), southeasterly (SE), southerly (S), southwesterly (SW), westerly (W) and northwesterly (NW), two pure types based on the severity of the vorticity - cyclonic (C) and anticyclonic (A), and sixteen hybrid types (eight cyclonic and eight anticyclonic for each direction). Synoptic characteristics of circulation types against all four seasonal times are considered. Each of the circulation types has a distinct underlying synoptic pattern that produces the expected type and direction of flow over the study area. Trends and relative frequencies of the circulation types are analyzed. A shortcoming of this method is the lack of data on other higher levels. In thesis, this deficiency has been solved by the vertical structure of the atmosphere that was employed to analyze the anomalies of the geopotential height at the 500 hPa. It has been found that the anticyclonic type (A), is the most common type of circulation in autumn with a frequency of 23.87%, then winter (18.93%) and summer (18.70%), followed by the northeasterly type (NE) with a frequency of 16.65% during the summer season. The A type has a positive trend for winter and spring, and significant negative trend for autumn and summer. The C type shows a significantly negative trend only in spring...