Responses of the Atmospheric Centers of Action to the Solar Cycle in the East and West phases of the Quasi-Biennial Oscillation

The Atmospheric Centers of Action (COA) at the surface are extended regions of high and low pressures that dominate atmospheric circulations over large areas. It is useful to study the variations of the COA because they are strongly coupled to regional climates. This study presents results for the Icelandic Low and the Azores High which are strongly related to regional climates in North America, Europe and North Africa, and the Aleutian Low and the Hawaiian High which are strongly related to regional climates in East Asia and North America.

Following the procedure of Van Loon and Labitzke we classified the monthly averaged pressure, the latitude position and the longitude position of these COA for each month of the year (during 1948-2004) according to the East and West directions of the equatorial stratospheric winds, and correlated each set with the solar cycle. Significant correlations were found for each of the COA in selected months in winter, spring, summer and autumn.

The responses in the surface conditions of the COA are found to lag the stratospheric wind direction by zero to four months. Current theories of stratosphere-troposphere dynamical coupling are evaluated to identify mechanisms that might communicate stratospheric circulation anomalies to the surface in all seasons and with lags of several months.