The statistics of precipitation and droughts during opposite phases of the quasi-biennial oscillation of atmospheric processes and its relation to the yield in the European part of Russia

As a result of the analysis of the data from weather stations and the values of Palmer Drought Severity Index (PDSI), territorial regularities are revealed in the distribution of total ten-day precipitation, frequency of severe atmospheric droughts in May and June, and spring wheat yield in the European part of Russia depending on the phase of the quasi-biennial oscillation of equatorial stratospheric wind (QBO) in 1953–2010. It is demonstrated that the variations can be explained by differences in the statistics of synoptic cyclonic and anticyclonic vortices during different QBO phases. The spatial structure of differences in ten-day precipitation and frequency of severe droughts on the European part of Russia during opposite phases of the QBO agrees with differences in spring wheat yield. The QBO was considered in the modeling of spring wheat yield in the Rostov oblast, and this allowed improvement of prognostic values of yield by 14%. The results of the simulation of spring wheat yield with account of the quasi-biennial oscillation of stratospheric equatorial wind as a predictor with the relative spatiotemporal stability of values can be used for working out new methods for forecasting the crop yield.