Investigation of the relations between station based maximum precipitations and large scale atmospheric parameters

Increasing air temperatures due to global warming not only affect the total amount of precipitation, but also cause changes in the intensity and frequency of extreme precipitation. In order to explain the correlation between these changes in precipitation regimes and atmospheric parameters, daily precipitation data of İzmir Bölge, Bergama, Bornova, Buca, Çeşme, Karşıyaka, Kemalpaşa, Menderes, Torbalı and Urla stations and the weather temperature, geopotential height, relative humidity and areal average precipitation parameters with regards to data obtained from NCEP / NCAR Re-Analysis between 1948 and 2018 period were assessed. Daily precipitation and atmospheric parameters of the same period were examined through Mann-Kendall trend test, and the trend structures of station-based precipitation and atmospheric parameters were compared. The trend analyses indicated the differentiation between the trends in the atmospheric parameters and station-based precipitation in the same period, and Sequential Mann-Kendall analyses were carried out to find the turning points of the increasing or decreasing trend, which has a major role in this differentiation. Within the scope of this thesis, the correlation between the daily precipitation of İzmir and its surrounding stations, and NCEP / NCAR parameters were examined through quantile regression analysis and it was found which atmospheric parameters affect the high quantile precipitation (heavy precipitation). It was observed in consequence of the analyses conducted that the temperature have been increasing in the centre of İzmir and other stations since 1960s, however the temperatures during the winter when the heaviest precipitation is observed have increased since 1975, the decrease in humidity began in the 1960s, the air-surface temperatures are dominant parameters in heavy precipitation, and that as the temperature increases, heavy precipitation increases correlatively.