As one of the strongest convection bands in the Southern Hemisphere,the South Pacific Convergence Zone(SPCZ)substantially influences the variabilities in the atmospheric circulation and Antarctic climate.In this study...As one of the strongest convection bands in the Southern Hemisphere,the South Pacific Convergence Zone(SPCZ)substantially influences the variabilities in the atmospheric circulation and Antarctic climate.In this study,it is revealed that the intensity of the SPCZ can change the characteristics of sea ice in the West Antarctica during austral autumn,which is significantly independent of the El Niño-Southern Oscillation(ENSO).Observational and numerical results suggest that a stronger-than-usual SPCZ can generate a poleward-propagating Rossby wave train along a great circular route and induce a weakening of the Amundsen Sea Low(ASL)near West Antarctica,which may somewhat offset the teleconnections exerted by ENSO.These changes in the strength and zonal extent of ASL is noticeable and robustly lead to a tripole response of sea-ice perturbations in the Ross,Amundsen,and Weddell Seas.We find that the wind-driven dynamical processes determine the local sea-ice changes,while the influence from thermodynamic processes is trivial.This research underscores the need to consider the SPCZ variability for a comprehensive understanding of sea-ice changes in West Antarctica on interannual timescales.展开更多
利用1979—2009年的NECP资料、Hadley海温月平均资料和CMAP降水资料,采用Kao and Yu(2009)的方法定义了夏季EP型ENSO指数EPI,用合成分析的方法分析了东部型ENSO与海洋性大陆降水的关系。结果表明:EPI与MC(Maritime Continent,海洋性大陆...利用1979—2009年的NECP资料、Hadley海温月平均资料和CMAP降水资料,采用Kao and Yu(2009)的方法定义了夏季EP型ENSO指数EPI,用合成分析的方法分析了东部型ENSO与海洋性大陆降水的关系。结果表明:EPI与MC(Maritime Continent,海洋性大陆)区域降水变化间存在非常弱的负相关。造成这一弱相关的原因是EPI与MC区域降水在某些年份存在同号变化。在剔除Nio4信号后,海洋性大陆区域降水序列与EPI与存在着同号和反号两种关系。反号关系是通常所认为的,当经典的El Nio(La Nia)发生时MC区域降水出现显著地减少(增多)。此时,沿赤道的异常Walker环流建立了EP型ENSO与MC区域气候间的直接联系。而在同号关系时,菲律宾以东异常加热和SPCZ区域异常冷却引起的西北—东南走向的垂直环流圈削弱了MC区域与赤道东太平洋之间的异常Walker环流所建立的直接联系,或者说,赤道东太平洋区域SSTA与MC区域降水异常的形成是通过SPCZ区域SST的反号异常而产生间接联系的。这种机制的揭示为深刻认识ENSO影响海洋性大陆区域甚至东亚地区气候变动的联系提供了新的线索。展开更多
By using a linear and stationary atmospheric model (Luo and Jiang, 1994, Zebiak and Cane,1987) and the initial data coming from Zebiak and Cane (1987), the influence of interaction between shift of warm pool and that ...By using a linear and stationary atmospheric model (Luo and Jiang, 1994, Zebiak and Cane,1987) and the initial data coming from Zebiak and Cane (1987), the influence of interaction between shift of warm pool and that of the equatorial convergence zone (ITCZ and SPCZ ) on atmospheric surface stream field and divergence field during 82/83 ENSO is analysed by numerical experiments. The results show that SPCZ is more important than ITCZ in developing phase and mature phase of warm event. The interaction of warm POOl and SPCZ is stronger than that of warm pool and ITCZ in the two phases. SPCZ is as important as ITCZ in the initial phase and decline phase of warm event.展开更多
Extreme precipitation events pose significant challenges to water resources,ag-riculture,infrastructure,public health,ecosystems,energy production,fishing,timber production,and other rain-dependent socioeconomic secto...Extreme precipitation events pose significant challenges to water resources,ag-riculture,infrastructure,public health,ecosystems,energy production,fishing,timber production,and other rain-dependent socioeconomic sectors across Eastern Africa,threatening the environment and regional livelihoods.This study analyzes spatial and temporal trends of extreme precipitation in Eastern Africa from January 1981 to 2023,using high-resolution CHIRPS data.Key ex-treme precipitation indices,including R10mm,R75p,and SDII,were calculated to assess variations in the frequency,intensity,and contribution of extreme rainfall events.The temporal analysis reveals a statistically significant increas-ing trend in January precipitation(0.844 mm/year,p=0.0191),confirmed by Sen’s Slope(0.74 mm/year).R10mm increased by 0.036 days/year(p=0.0079),with Sen’s Slope estimating 0.04 days/year.R75p showed a rise of 0.025 days/year(p=0.0113),with Sen’s Slope at 0.02 days/year.SDII exhibited the most significant trend,increasing by 0.056 mm/day per year(p=0.0002),with Sen’s Slope at 0.06 mm/day per year.These results indicate a rise in extreme precipitation in Eastern Africa,increasing the risk of flooding and other cli-mate-related hazards.Spatial analysis shows distinct regional variations,with Southern Tanzania,Mozambique,Malawi,Zambia,Zimbabwe,and Madagas-car exhibiting statistically significant increasing trends in January precipitation and extreme precipitation indices.These regions are becoming more vulnera-ble to flooding and other climate-related hazards.Moreover,correlation anal-ysis identifies significant links between global SST anomalies and extreme pre-cipitation trends,demonstrating the influence of large-scale climate drivers.The study indicates the growing intensity and frequency of extreme precipita-tion in parts of Eastern Africa,significantly influenced by the South Pacific Convergence Zone(SPCZ).This necessitates a deeper understanding of SPCZ dynamics and their impacts on precipitation patterns to enhance climate pre-diction and develop adaptive strategies for mitigating extreme weather events.Such efforts will contribute to safeguarding water resources,agriculture,infra-structure,public health,energy production,fisheries,transportation,and live-lihoods across the region.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42375024).
文摘As one of the strongest convection bands in the Southern Hemisphere,the South Pacific Convergence Zone(SPCZ)substantially influences the variabilities in the atmospheric circulation and Antarctic climate.In this study,it is revealed that the intensity of the SPCZ can change the characteristics of sea ice in the West Antarctica during austral autumn,which is significantly independent of the El Niño-Southern Oscillation(ENSO).Observational and numerical results suggest that a stronger-than-usual SPCZ can generate a poleward-propagating Rossby wave train along a great circular route and induce a weakening of the Amundsen Sea Low(ASL)near West Antarctica,which may somewhat offset the teleconnections exerted by ENSO.These changes in the strength and zonal extent of ASL is noticeable and robustly lead to a tripole response of sea-ice perturbations in the Ross,Amundsen,and Weddell Seas.We find that the wind-driven dynamical processes determine the local sea-ice changes,while the influence from thermodynamic processes is trivial.This research underscores the need to consider the SPCZ variability for a comprehensive understanding of sea-ice changes in West Antarctica on interannual timescales.
文摘By using a linear and stationary atmospheric model (Luo and Jiang, 1994, Zebiak and Cane,1987) and the initial data coming from Zebiak and Cane (1987), the influence of interaction between shift of warm pool and that of the equatorial convergence zone (ITCZ and SPCZ ) on atmospheric surface stream field and divergence field during 82/83 ENSO is analysed by numerical experiments. The results show that SPCZ is more important than ITCZ in developing phase and mature phase of warm event. The interaction of warm POOl and SPCZ is stronger than that of warm pool and ITCZ in the two phases. SPCZ is as important as ITCZ in the initial phase and decline phase of warm event.
文摘Extreme precipitation events pose significant challenges to water resources,ag-riculture,infrastructure,public health,ecosystems,energy production,fishing,timber production,and other rain-dependent socioeconomic sectors across Eastern Africa,threatening the environment and regional livelihoods.This study analyzes spatial and temporal trends of extreme precipitation in Eastern Africa from January 1981 to 2023,using high-resolution CHIRPS data.Key ex-treme precipitation indices,including R10mm,R75p,and SDII,were calculated to assess variations in the frequency,intensity,and contribution of extreme rainfall events.The temporal analysis reveals a statistically significant increas-ing trend in January precipitation(0.844 mm/year,p=0.0191),confirmed by Sen’s Slope(0.74 mm/year).R10mm increased by 0.036 days/year(p=0.0079),with Sen’s Slope estimating 0.04 days/year.R75p showed a rise of 0.025 days/year(p=0.0113),with Sen’s Slope at 0.02 days/year.SDII exhibited the most significant trend,increasing by 0.056 mm/day per year(p=0.0002),with Sen’s Slope at 0.06 mm/day per year.These results indicate a rise in extreme precipitation in Eastern Africa,increasing the risk of flooding and other cli-mate-related hazards.Spatial analysis shows distinct regional variations,with Southern Tanzania,Mozambique,Malawi,Zambia,Zimbabwe,and Madagas-car exhibiting statistically significant increasing trends in January precipitation and extreme precipitation indices.These regions are becoming more vulnera-ble to flooding and other climate-related hazards.Moreover,correlation anal-ysis identifies significant links between global SST anomalies and extreme pre-cipitation trends,demonstrating the influence of large-scale climate drivers.The study indicates the growing intensity and frequency of extreme precipita-tion in parts of Eastern Africa,significantly influenced by the South Pacific Convergence Zone(SPCZ).This necessitates a deeper understanding of SPCZ dynamics and their impacts on precipitation patterns to enhance climate pre-diction and develop adaptive strategies for mitigating extreme weather events.Such efforts will contribute to safeguarding water resources,agriculture,infra-structure,public health,energy production,fisheries,transportation,and live-lihoods across the region.
