On the Relationship Between the Stratospheric Quasi-Biennial Oscillation and Summer Precipitation in Northern China

This paper reports that there has been a significant relationship between the quasi-biennial oscillation (QBO) in zonal wind at 50 hPa in summer and precipitation in August in northern China since the late 1970s. The correlation coefficient between them reaches up to -0.61 during 1979-2018. Associated with the easterly (westerly) phase of the QBO, there is a meridional dipole pattern of zonal wind from the stratosphere to troposphere over the Northwest Pacific in August with the easterly (westerly) anomalies in 25-50 degrees N and westerly (easterly) anomalies in 50-65 degrees N. This meridional zonal-wind dipole favors the strengthening (weakening) of the tropospheric Japan Sea high in the QBO easterly (westerly) phase, causing an increase (decrease) of the water vapor transportation from the Northwest Pacific to northern China and thus more (less) precipitation in these regions. The finding of this study has import implications for predicting the summer precipitation in northern China in the future.