The Quasi-Biennial Oscillation(QBO)is a vital mode of stratospheric variability with significant influence on tropical and subtropical climate systems.However,its influence on precipitation variability across Eastern ...The Quasi-Biennial Oscillation(QBO)is a vital mode of stratospheric variability with significant influence on tropical and subtropical climate systems.However,its influence on precipitation variability across Eastern and Southern Africa remains insufficiently understood.This study examines the impact of the QBO on summer precipitation and associated circulation anomalies over Eastern and Southern Africa from 1979 to 2021.Using ERA5 and NOAA reanalysis datasets,we applied composite and correlation analyses to assess precipitation responses to westerly(WQBO)and easterly(EQBO)phases.Results show a dipole-like pattern,with WQBO linked to enhanced precipitation in both Eastern and Southern Africa,while EQBO is associated with reduced precipitation.Circulation analysis reveals that WQBO phases promote upper-level divergence,low-level moisture inflow,and vertical ascent,whereas EQBO phases enhance subsidence and upperlevel convergence.These findings highlight the QBO role in modulating precipitation through stratosphere-troposphere coupling and its interaction with regional circulation patterns.The quasi-periodic nature of QBO offers substantial potential for enhancing seasonal precipitation predictions when integrated with other regional circulations,such as the Botswana High and the Angola Low.展开更多
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
A solution of atrazine in a TiO_(2)suspension,an endocrine disruptor in natural water,was tentatively treated by microwave-assisted photocatalytic technique.The effects of mannitol,oxygen,humic acid,and hydrogen dioxi...A solution of atrazine in a TiO_(2)suspension,an endocrine disruptor in natural water,was tentatively treated by microwave-assisted photocatalytic technique.The effects of mannitol,oxygen,humic acid,and hydrogen dioxide on the photodegradation rate were explored.The results could be deduced as follows:the photocatalytic degradation of atrazine fits the pseudo-first-order kinetic well with k=0.0328 s–1,and·OH was identified as the dominant reactant.Photodegradation of atrazine was hindered in the presence of humic acid,and the retardation effect increased as the concentration of humic acid increased.H_(2)O_(2)displayed a significant negative influence on atrazine photocatalysis efficiency.Based on intermediates identified with gas chromatography-mass spectrometry(GC-MS)and Liquid chromatography-mass spectrometry(LC-MS/MS)techniques,the main degradation routes of atrazine are proposed.展开更多
Optical heterodyne detection using 500 MHz phase modulation was combined with the Zeeman modulation-magnetic rotation spectroscopy (ZM-MRS) to form a new spectroscopic technique, which effectively reduced the amplitud...Optical heterodyne detection using 500 MHz phase modulation was combined with the Zeeman modulation-magnetic rotation spectroscopy (ZM-MRS) to form a new spectroscopic technique, which effectively reduced the amplitude fluctuation from laser source and greatly improved the signal-to-noise ratio in the detection of transient molecules.展开更多
文摘The Quasi-Biennial Oscillation(QBO)is a vital mode of stratospheric variability with significant influence on tropical and subtropical climate systems.However,its influence on precipitation variability across Eastern and Southern Africa remains insufficiently understood.This study examines the impact of the QBO on summer precipitation and associated circulation anomalies over Eastern and Southern Africa from 1979 to 2021.Using ERA5 and NOAA reanalysis datasets,we applied composite and correlation analyses to assess precipitation responses to westerly(WQBO)and easterly(EQBO)phases.Results show a dipole-like pattern,with WQBO linked to enhanced precipitation in both Eastern and Southern Africa,while EQBO is associated with reduced precipitation.Circulation analysis reveals that WQBO phases promote upper-level divergence,low-level moisture inflow,and vertical ascent,whereas EQBO phases enhance subsidence and upperlevel convergence.These findings highlight the QBO role in modulating precipitation through stratosphere-troposphere coupling and its interaction with regional circulation patterns.The quasi-periodic nature of QBO offers substantial potential for enhancing seasonal precipitation predictions when integrated with other regional circulations,such as the Botswana High and the Angola Low.
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.
基金the National Natural Science Foundation of China(Grant No.20707009)the National Major Project of Science&Technology Ministry of China(No.2008ZX07421-003)the Jiangsu Province Social Development Foundation(Nos.BS2007026 and BS2007051).
文摘A solution of atrazine in a TiO_(2)suspension,an endocrine disruptor in natural water,was tentatively treated by microwave-assisted photocatalytic technique.The effects of mannitol,oxygen,humic acid,and hydrogen dioxide on the photodegradation rate were explored.The results could be deduced as follows:the photocatalytic degradation of atrazine fits the pseudo-first-order kinetic well with k=0.0328 s–1,and·OH was identified as the dominant reactant.Photodegradation of atrazine was hindered in the presence of humic acid,and the retardation effect increased as the concentration of humic acid increased.H_(2)O_(2)displayed a significant negative influence on atrazine photocatalysis efficiency.Based on intermediates identified with gas chromatography-mass spectrometry(GC-MS)and Liquid chromatography-mass spectrometry(LC-MS/MS)techniques,the main degradation routes of atrazine are proposed.
文摘Optical heterodyne detection using 500 MHz phase modulation was combined with the Zeeman modulation-magnetic rotation spectroscopy (ZM-MRS) to form a new spectroscopic technique, which effectively reduced the amplitude fluctuation from laser source and greatly improved the signal-to-noise ratio in the detection of transient molecules.
