Sensitivity of Stratospheric Zonal Wind to Solar Cycle Variations
Shuntai Zhou [shuntai.zhou@noaa.gov] and Alvin Miller, NOAA/NCEP/Climate Prediction Center

It has been speculated that the sun and earth's climate may be linked through stratospheric zonal wind structure, which regulates upward propagating planetary waves. To examine how effective that mechanism works, we first calculate sensitivities of stratospheric zonal wind to solar cycle and other dynamical factors using 24 years of observed data. The zonal wind used in our analysis consists of two parts: below 10 hPa we use the NCEP/NCAR Reanalysis, above 10 hPa we derive it from the CPC operational analysis of height fields. The dynamical factors considered in our multiple regression analysis include QBO, SAO, annular modes and E-P flux. Our results indicate that the zonal wind sensitivity to solar cycle variations is relatively small compared to other factors, though it is significant in the tropical upper stratosphere and in the extratropics of southern hemisphere. In addition to stratospheric zonal wind, we examine various quantities of wave propagation, such as E-P flux and refractive index, to verify if they support the speculated mechanism.