The Quasi-Biennial Oscillation(QBO)is a dominant mode of interannual variability in the tropical stratosphere,known to influence global weather and climate patterns through stratosphere-troposphere coupling.While its ...The Quasi-Biennial Oscillation(QBO)is a dominant mode of interannual variability in the tropical stratosphere,known to influence global weather and climate patterns through stratosphere-troposphere coupling.While its impacts on the Northern Hemisphere are well-documented,its role in the Southern Hemisphere subtropical climate remains less explored.This study investigates the relationship between the QBO and September surface air temperature(SAT)over Southern Africa during the early austral spring from 1979 to 2021.We find that the QBO’s easterly phase(EQBO)at 50 hPa is associated with a significant dipole pattern in SAT,characterized by warming over southeastern Africa and cooling along the southwestern coastal area.Analysis reveals that this temperature pattern is driven by a coherent teleconnection pathway:the EQBO forces a quasi-barotropic geopotential height anomaly,which modulates vertical velocity,leading to enhanced convection and increased cloud cover over the cooling region and suppressed convection over the warming area.Outgoing Longwave Radiation data confirm this dipole in convective activity.A latitudinal-vertical cross-section demonstrates the descent of QBOrelated wind anomalies into the subtropical troposphere,outlining the direct stratospheric pathway for this distant influence.Our results identify the QBO as a key stratospheric precursor for early spring temperature variability in Southern Africa,with important implications for improving regional seasonal forecasting.展开更多
基金ECMWF-ERA5 and NOAA for making their data available.
文摘The Quasi-Biennial Oscillation(QBO)is a dominant mode of interannual variability in the tropical stratosphere,known to influence global weather and climate patterns through stratosphere-troposphere coupling.While its impacts on the Northern Hemisphere are well-documented,its role in the Southern Hemisphere subtropical climate remains less explored.This study investigates the relationship between the QBO and September surface air temperature(SAT)over Southern Africa during the early austral spring from 1979 to 2021.We find that the QBO’s easterly phase(EQBO)at 50 hPa is associated with a significant dipole pattern in SAT,characterized by warming over southeastern Africa and cooling along the southwestern coastal area.Analysis reveals that this temperature pattern is driven by a coherent teleconnection pathway:the EQBO forces a quasi-barotropic geopotential height anomaly,which modulates vertical velocity,leading to enhanced convection and increased cloud cover over the cooling region and suppressed convection over the warming area.Outgoing Longwave Radiation data confirm this dipole in convective activity.A latitudinal-vertical cross-section demonstrates the descent of QBOrelated wind anomalies into the subtropical troposphere,outlining the direct stratospheric pathway for this distant influence.Our results identify the QBO as a key stratospheric precursor for early spring temperature variability in Southern Africa,with important implications for improving regional seasonal forecasting.
