Coherent Oscillations of Cold-season Precipitation on the Territory of the Ishim Plain and Atmospheric Circulation Indices

K. Yu. Sukovatov and N. N. Bezuglova

Analyzed are the periodical components of cold-season precipitation series on the territory of the Ishim Plain and atmospheric circulation indices AO, SCAND, and EA/WR for 1950–2010 using the wavelet coherence method. The spectra of wavelet coherence (R2) are computed for the atmospheric parameters under study, and oscillation periods and phase relations are determined. Statistically significant coherent fluctuation with the periods of 8–12 years (R2 = 0.7–0.9) were observed in the series of precipitation and of each index. Phase relations and time periods differ for different circulation indices: EA/WR in 1963–1985, SCAND in 1983–2000, and AO in 1972–1991. Coherent oscillations in the series of precipitation and AO and EA/WR indices occurred in phase and those in the series of precipitation and SCAND index, in antiphase.