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
In recent years, extreme high temperature events occurred more frequently in Northern Africa (NA) posing significant impacts on ecological systems and socioeconomic development. However, the physical origin of these e...In recent years, extreme high temperature events occurred more frequently in Northern Africa (NA) posing significant impacts on ecological systems and socioeconomic development. However, the physical origin of these extreme high temperatures remains unexplored. To address this issue, Empirical Orthogonal Function (EOF) analysis technics is employed to investigate the key physical factors influencing the spatial patterns of extreme high temperature days (EHDs) over NA. Three major modes of EHDs (EOF1, EOF2 and EOF3) accounting for 43%, 11% and 8% of the total variance were identified in this study. EOF1 features uniform distribution associated with positive geopotential heights and anticyclonic flows, while EOF2 is characterized by a meridional dipole pattern. Using reanalysis datasets, these modes are further linked to ocean – land – atmosphere interactions to reveal underlying physical mechanism. EOF1 is influenced by tropical and subtropical positive SSTA associated by mid tropospheric heights which triggers heat wave transport and subsidence. This mode is also influenced by weakening of west African monsoon system which suppresses moisture transport towards NA. EOF2 is influenced by combination of tropical Indian ocean and western Pacific wave trains leading subsidence over NA. EOF3 captures more the transient or regional scale influences on EHDs due to it weak association with large-scale teleconnections. Generally, this study classifies the factors influencing summer patterns of EHDs over NA as 1) tropical and subtropical SST warming, 2) decaying of Monsoon circulation, and 3) Strengthened upper-level subsidence. Gaining an understanding of these processes is essential for improving climate prediction and setting strategies for early warning and mitigation of the impacts from extreme heat events.展开更多
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.
文摘In recent years, extreme high temperature events occurred more frequently in Northern Africa (NA) posing significant impacts on ecological systems and socioeconomic development. However, the physical origin of these extreme high temperatures remains unexplored. To address this issue, Empirical Orthogonal Function (EOF) analysis technics is employed to investigate the key physical factors influencing the spatial patterns of extreme high temperature days (EHDs) over NA. Three major modes of EHDs (EOF1, EOF2 and EOF3) accounting for 43%, 11% and 8% of the total variance were identified in this study. EOF1 features uniform distribution associated with positive geopotential heights and anticyclonic flows, while EOF2 is characterized by a meridional dipole pattern. Using reanalysis datasets, these modes are further linked to ocean – land – atmosphere interactions to reveal underlying physical mechanism. EOF1 is influenced by tropical and subtropical positive SSTA associated by mid tropospheric heights which triggers heat wave transport and subsidence. This mode is also influenced by weakening of west African monsoon system which suppresses moisture transport towards NA. EOF2 is influenced by combination of tropical Indian ocean and western Pacific wave trains leading subsidence over NA. EOF3 captures more the transient or regional scale influences on EHDs due to it weak association with large-scale teleconnections. Generally, this study classifies the factors influencing summer patterns of EHDs over NA as 1) tropical and subtropical SST warming, 2) decaying of Monsoon circulation, and 3) Strengthened upper-level subsidence. Gaining an understanding of these processes is essential for improving climate prediction and setting strategies for early warning and mitigation of the impacts from extreme heat events.
