Estimation of Predictive Potential of Quasi-Biennoal Oscillation (QBO) Cyclical Stratospheric Circulation in Tropical Zone for Long-Term Precipitation Forecast

for our knowledge, this represented the first Iraqi report that aimed for assessment if the worldwide signals can employ as predictor variables among long-range forecast. Hence, a simple relationship assay with QBO was applied for examining long-term precipitation over many Iraqi main cities with variable phases of QBO throughout stratospheric zonal, the Eastern and Western, winds. As well as, this study was carried out for exploring, predictably, long season of precipitation by the data concerned to QBO phases during 1951-2010; and for statistical studying of spatially relationship pattern for understanding climatic correlation of equatorially stratospheric zonal winds with the regionally precipitation during the scale of inter-annual time. Statistically, the findings showed that the highest significance (P<0.0001) precipitation rate during wet season reported in January, while the lowest in October; and the average value of precipitation rate depended relatively on passage of air masses. In summer, values of standard deviation for Western wind passes Iraq were minimal; whereas in winter, values being maximum. Regarding Eastern phase of QBO Cycle in stratospheric circulation, statistical analysis showed that there no significant differences (P≤0.0717) within the values of Aa and Bb. However, significant differences (P≤0.0364) were detected when the values of Aa compared with the values of Bb. For Western phase of QBO Cycle in stratospheric circulation, the findings revealed no significant variation (P≤0.0523) within the values of Aa and Bb; while, significant variation (P≤0.009) was seen between the values of Aa and Bb. Concerning Aa repeatability of the Eastern and Western phases, no significant differences (P≤0.712) were detected within values of both phases; but not between them (P<0.0001). For Bb repeatability, significant variation within (P≤0.0202) and between (P≤0.0003) values of both phases was detected.