Zafer ASLAN, Zehra Nevin ÇAĞLAR, D. Nail YENİÇERİ

WAVELET ANALYSES OF SOME ATMOSPHERIC PARAMETERS AT BLACK SEA REGION

1D wavelet and continuous wavelet analyses of some atmospheric parameters (annual mean, maximum and minimum air temperature, relative humidity and annual total precipitation) in Şile (Northeastern Black Sea Region of Istanbul) between 1939 and 2012 are presented in this paper. The main aim of this study is to extract temporal structure changes of a climatic oscillation of some selected atmospheric parameters. The influence of climatic oscillations based on NO and El-Nino are analyzed for monthly and annual values. Wavelet analyses allowed quantifying both the pattern of variability in the time series and non-stationary associations in general. Mean air temperature values increases associated with decreasing of high frequency (small scale) fluctuations and increasing of low frequency (large scale) fluctuations in the second term. Increasing ratio of maximum air temperatures are more than mean air temperatures. Meso and small scale fluctuations play an important role on increasing of maximum air temperatures in study area. Large scale fluctuations cause increasing trend of minimum air temperature in the second term. Relative humidity increases beginning from 1976 (industrialization) and associates with amplitudes of high frequency fluctuations (small scale evens). Large scale evens have a great importance on this variation at the study area. Annual total rainfall rate values also increase in the second period. Increasing trend of amplitude of high frequency fluctuations are accompany with rainfall increasing. In this period, large scale evens observed every 5 to 20 year periodic modes have a great influence on rainfall increasing. Maximum rainfall rate observations in 1926, 1969-70, 1982-83, 1997-98 and 2009 may be reported strong associations between rainfall and El Nino periodic bands. Warm event matched with increasing values of relative humidity and annual total rainfall rate values.

Keywords:

Climatic oscillations, wavelet, El Nino,

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