In this study,based on MERRA-2 reanalysis data and a multi-algorithm integrated atmospheric river(AR)iden-tification method,the authors reveal the cross-seasonal regulation mechanism of El Niño-Southern Oscillati...In this study,based on MERRA-2 reanalysis data and a multi-algorithm integrated atmospheric river(AR)iden-tification method,the authors reveal the cross-seasonal regulation mechanism of El Niño-Southern Oscillation(ENSO)on winter-spring AR activities in East Asia.The results show that ENSO asymmetrically modulates AR ac-tivity through teleconnection and hysteresis effects,and has significant enhancement/inhibition effects on ARs in different regions.At the onset of El Niño,enhanced southwesterly flow at the western edge of the western Pacific subtropical high(WPSH)leads to enhanced AR activity in the western Pacific,and anomalous southerly winds in the Indian Ocean promote northward transport of water vapor in the Arabian Sea and Bay of Bengal.With a three-month lag,the weakening and eastward retreat of the WPSH weakens the low-latitude AR activity,but persistent southerly winds in the Bay of Bengal maintain the AR activity over Southwest China.The mid-to high-latitude AR response exhibits delayed dynamics,initially dominated by the synergistic effect of the southward deviation of the upper-air rapids and the low-level convergence(double-rapid-flow effect)and later modulated by the Pacific-North American teleconnection(PNA)-triggered East Asian ridge,which enhances the precipitation efficiency through prolonged frontal activity and enhanced cold-warm airmass convergence.Overall,El Niño promotes the development of low-and midlatitude AR activity in East Asia,while La Niña promotes(maritime continental)AR activity in the tropics.This study establishes the“ENSO teleconnection→circulation adjust-ment→East Asian AR response”chain,revealing a cross-seasonal lagged response mechanisms of East Asian AR activity,and provides a theoretical basis for winter and spring climate prediction and extreme precipitation forecasting.展开更多
Atmospheric rivers(ARs)are long,narrow,and transient filaments of strong horizontal water vapor transport that can lead to extreme precipitation.To investigate the relationship between ARs and mei-yu rainfall in China...Atmospheric rivers(ARs)are long,narrow,and transient filaments of strong horizontal water vapor transport that can lead to extreme precipitation.To investigate the relationship between ARs and mei-yu rainfall in China,the mei-yu season of 2020 in the Yangtze-Huaihe River basin is taken as an example.An adjusted AR-detection algorithm is applied on integrated water vapor transport(IVT)of the ERA5 reanalysis.The JRA-55 reanalysis and the data from Integrated Multi-satellite Retrievals for GPM(IMERG)are also utilized to study the impacts of ARs on mei-yu rainfall in 2020.The results reveal that ARs in East Asia have an average length of 5400 km,a width of 600 km,a length/width ratio of 9.3,and a northeastward orientation of 30°.ARs are modulated by the western North Pacific subtropical high.The IVT core is located at the south side of low pressure systems,moving eastward with a speed of 10°d−1.For the cross sections of ARs in the Yangtze-Huaihe River basin,75%of the total flux is concentrated below 4 km with low-level jets near AR cores.Moreover,ARs occur mainly in the mei-yu period with a frequency of 20%–60%.The intensity of AR-related precipitation is 6–12 times that of AR-unrelated precipitation,and AR-related precipitation contributes about 50%–80%to total mei-yu precipitation.As shown in this case study of summer 2020,ARs are an essential part of the mei-yu system and have great impacts on mei-yu rainfall.Thus,ARs should receive more attention in research and weather forecast practices.展开更多
Atmospheric Rivers(ARs) are narrow and elongated water vapor belts in troposphere with meridional transport across the mid-latitudes towards high-latitudes. Compared with ARs occurred over the northeastern Pacific, th...Atmospheric Rivers(ARs) are narrow and elongated water vapor belts in troposphere with meridional transport across the mid-latitudes towards high-latitudes. Compared with ARs occurred over the northeastern Pacific, the western coast of North America and Europe, the ARs over the East Asia have received less attention. In this paper, the characteristics of ARs which affected China in the area 20?–60?N, 95?–165?E in the middle summer season from 2001 to 2016 were investigated by using European Center for Medium-Range Weather Forecasts(ECMWF) ERA-Interim reanalysis data and Multi-functional Transport Satellites-1 R(MTSAT-1 R) infrared data. Totally, 134 ARs occurred during that period, and averagely 8.4 ARs occurred per year. Statistically, 101 ARs were in east-west orientation, and 33 ARs were in north-south orientation, which accounts for about 75% and 25%, respectively. Herein we report the occurrence number, duration time, intensity, length, width, ratio of length to width, and extension orientation of these ARs, which provide the basic information for those who have interest in ARs over the East Asia.展开更多
Atmospheric rivers(ARs),the long and narrow conveyors of intense moisture transport,have a non-negligible impact on hydrometeorological events over the extratropical regions.This study analyzes the climatology and int...Atmospheric rivers(ARs),the long and narrow conveyors of intense moisture transport,have a non-negligible impact on hydrometeorological events over the extratropical regions.This study analyzes the climatology and interannual variability of ARs and their quantitative association with precipitation and precipitation extremes over East Asia(EA)during 1979-2019,based on calculations of not only moisture transport but also moisture flux convergence.It is found that the ARs over EA occur frequently in spring and summer,accounting for 25%-40%of seasonal precipitation and 60%-75%of extreme precipitation over EA.Increases in AR frequency are observed over EA during post-El Ni?o summers,meanwhile the AR-related anomalous moisture convergence is found leading to the increase of extreme precipitation.Specifically,increased ARs account for 70%-90%of total precipitation anomalies and up to 90%of extreme precipitation anomalies over the middle-lower reaches of the Yangtze River,and the anomalies of moisture flux convergence are caused mainly by changes in horizontal wind convergence rather than moisture advection during the post-El Ni?o summers.展开更多
Arctic sea ice has undergone a significant decline in the Barents-Kara Sea(BKS)since the late 1990s.Previous studies have shown that the decrease in sea ice caused by increased poleward moisture transport is modulated...Arctic sea ice has undergone a significant decline in the Barents-Kara Sea(BKS)since the late 1990s.Previous studies have shown that the decrease in sea ice caused by increased poleward moisture transport is modulated by tropical sea temperature changes(mainly referring to La Niña events).The occurrence of multi-year La Niña(MYLA)events has increased significantly in recent decades,and their impact on Arctic sea ice needs to be further explored.In this study,we investigate the relationship between sea-ice variation and different atmospheric diagnostics during MYLA and other La Niña(OTLA)years.The decline in BKS sea ice during MYLA winters is significantly stronger than that during OTLA years.This is because MYLA events tend to be accompanied by a warm Arctic-cold continent pattern with a barotropic high pressure blocked over the Urals region.Consequently,more frequent northward atmospheric rivers intrude into the BKS,intensifying longwave radiation downward to the underlying surface and melting the BKS sea ice.However,in the early winter of OTLA years,a negative North Atlantic Oscillation presents in the high latitudes of the Northern Hemisphere,which obstructs the atmospheric rivers to the south of Iceland.We infer that such a different response of BKS sea-ice decline to different La Niña events is related to stratospheric processes.Considering the rapid climate changes in the past,more frequent MYLA events may account for the substantial Arctic sea-ice loss in recent decades.展开更多
Soil erosion by water poses major environmental challenges to the European viticulture sector.Biochar is recognised as a sustainable tool for combating land degradation,but few studies on the effect of biochar on soil...Soil erosion by water poses major environmental challenges to the European viticulture sector.Biochar is recognised as a sustainable tool for combating land degradation,but few studies on the effect of biochar on soil erosion have been conducted in Mediterranean vineyards with hilly terrain and heavy rainfall.This study assesses the potential of biochar to support soil conservation by enhancing sponge function,i.e.water retention and infiltration,and reducing erodibility in sloping sandy loam soil under natural rainfall conditions.An 18-month outdoor box lysimeter experiment was conducted using bare soil,including soil amended with 4%(w/w)biochar from a Portuguese vineyard.Over the monitoring period,biochar application significantly(p<0.001)reduced the runoff coefficient by an average of 45%.Biochar reduced coarse fragment erosion by 67%,fine-earth erosion by 43%,and splash erosion by 34%,all affected(p<0.05)by rainfall intensity.The erosion rate in vineyard soil was 3 times lower(p<0.001)in biocharamended soil than in the control(3.7 vs.11.1 t ha^(-1)yr^(-1)).Improved soil structure led to a 7%reduction in bulk density,an average increase of 73%in stored water,and a 28%increase in infiltration.During drier periods,the biocharamended soil stored 171–303%more water than the control soil.We recommend a minimum monitoring period of a full hydrological cycle under natural rainfall to comprehensively capture the effect of biochar on the soil sponge function.Observed seasonal trends and atmospheric river(AR)events suggest that studies using rainfall simulations without considering antecedent soil moisture and AR variations will yield skewed data on effects.From a practical standpoint,this study showed that biochar could be a sustainable soil management solution to enhancing long-term vineyard resilience and productivity in the Mediterranean.展开更多
基金supported by the National Natural Science Foundation of China[grant number 41830964]the Natural Science Foundation of Hunan Province[grant number 2023JJ40666]。
文摘In this study,based on MERRA-2 reanalysis data and a multi-algorithm integrated atmospheric river(AR)iden-tification method,the authors reveal the cross-seasonal regulation mechanism of El Niño-Southern Oscillation(ENSO)on winter-spring AR activities in East Asia.The results show that ENSO asymmetrically modulates AR ac-tivity through teleconnection and hysteresis effects,and has significant enhancement/inhibition effects on ARs in different regions.At the onset of El Niño,enhanced southwesterly flow at the western edge of the western Pacific subtropical high(WPSH)leads to enhanced AR activity in the western Pacific,and anomalous southerly winds in the Indian Ocean promote northward transport of water vapor in the Arabian Sea and Bay of Bengal.With a three-month lag,the weakening and eastward retreat of the WPSH weakens the low-latitude AR activity,but persistent southerly winds in the Bay of Bengal maintain the AR activity over Southwest China.The mid-to high-latitude AR response exhibits delayed dynamics,initially dominated by the synergistic effect of the southward deviation of the upper-air rapids and the low-level convergence(double-rapid-flow effect)and later modulated by the Pacific-North American teleconnection(PNA)-triggered East Asian ridge,which enhances the precipitation efficiency through prolonged frontal activity and enhanced cold-warm airmass convergence.Overall,El Niño promotes the development of low-and midlatitude AR activity in East Asia,while La Niña promotes(maritime continental)AR activity in the tropics.This study establishes the“ENSO teleconnection→circulation adjust-ment→East Asian AR response”chain,revealing a cross-seasonal lagged response mechanisms of East Asian AR activity,and provides a theoretical basis for winter and spring climate prediction and extreme precipitation forecasting.
基金This research was supported jointly by the National Key Research and Development Program(Grant No.2016YFA0600604)the National Natural Science Foundation of China(Grant No.4191101005 and 4181101164)the Alliance of the International Science Organizations(Grant No.ANSO-CR-KP-2020-01).
文摘Atmospheric rivers(ARs)are long,narrow,and transient filaments of strong horizontal water vapor transport that can lead to extreme precipitation.To investigate the relationship between ARs and mei-yu rainfall in China,the mei-yu season of 2020 in the Yangtze-Huaihe River basin is taken as an example.An adjusted AR-detection algorithm is applied on integrated water vapor transport(IVT)of the ERA5 reanalysis.The JRA-55 reanalysis and the data from Integrated Multi-satellite Retrievals for GPM(IMERG)are also utilized to study the impacts of ARs on mei-yu rainfall in 2020.The results reveal that ARs in East Asia have an average length of 5400 km,a width of 600 km,a length/width ratio of 9.3,and a northeastward orientation of 30°.ARs are modulated by the western North Pacific subtropical high.The IVT core is located at the south side of low pressure systems,moving eastward with a speed of 10°d−1.For the cross sections of ARs in the Yangtze-Huaihe River basin,75%of the total flux is concentrated below 4 km with low-level jets near AR cores.Moreover,ARs occur mainly in the mei-yu period with a frequency of 20%–60%.The intensity of AR-related precipitation is 6–12 times that of AR-unrelated precipitation,and AR-related precipitation contributes about 50%–80%to total mei-yu precipitation.As shown in this case study of summer 2020,ARs are an essential part of the mei-yu system and have great impacts on mei-yu rainfall.Thus,ARs should receive more attention in research and weather forecast practices.
基金supported by the National Na-tural Science Foundation of China (Nos. 41775042 and 41275049)。
文摘Atmospheric Rivers(ARs) are narrow and elongated water vapor belts in troposphere with meridional transport across the mid-latitudes towards high-latitudes. Compared with ARs occurred over the northeastern Pacific, the western coast of North America and Europe, the ARs over the East Asia have received less attention. In this paper, the characteristics of ARs which affected China in the area 20?–60?N, 95?–165?E in the middle summer season from 2001 to 2016 were investigated by using European Center for Medium-Range Weather Forecasts(ECMWF) ERA-Interim reanalysis data and Multi-functional Transport Satellites-1 R(MTSAT-1 R) infrared data. Totally, 134 ARs occurred during that period, and averagely 8.4 ARs occurred per year. Statistically, 101 ARs were in east-west orientation, and 33 ARs were in north-south orientation, which accounts for about 75% and 25%, respectively. Herein we report the occurrence number, duration time, intensity, length, width, ratio of length to width, and extension orientation of these ARs, which provide the basic information for those who have interest in ARs over the East Asia.
基金Supported by the National Key Research and Development Program of China(2018YFC1505903)National Natural Science Foundation of China(41621005)。
文摘Atmospheric rivers(ARs),the long and narrow conveyors of intense moisture transport,have a non-negligible impact on hydrometeorological events over the extratropical regions.This study analyzes the climatology and interannual variability of ARs and their quantitative association with precipitation and precipitation extremes over East Asia(EA)during 1979-2019,based on calculations of not only moisture transport but also moisture flux convergence.It is found that the ARs over EA occur frequently in spring and summer,accounting for 25%-40%of seasonal precipitation and 60%-75%of extreme precipitation over EA.Increases in AR frequency are observed over EA during post-El Ni?o summers,meanwhile the AR-related anomalous moisture convergence is found leading to the increase of extreme precipitation.Specifically,increased ARs account for 70%-90%of total precipitation anomalies and up to 90%of extreme precipitation anomalies over the middle-lower reaches of the Yangtze River,and the anomalies of moisture flux convergence are caused mainly by changes in horizontal wind convergence rather than moisture advection during the post-El Ni?o summers.
基金supported by the National Key R&D Program of China(Grant No.2022YFE0106300)the National Natural Science Foundation of China(Grant Nos.42105052 and 42106220)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2020B1515020025)the fundamental research funds for the Norges Forskningsråd(Grant No.328886).
文摘Arctic sea ice has undergone a significant decline in the Barents-Kara Sea(BKS)since the late 1990s.Previous studies have shown that the decrease in sea ice caused by increased poleward moisture transport is modulated by tropical sea temperature changes(mainly referring to La Niña events).The occurrence of multi-year La Niña(MYLA)events has increased significantly in recent decades,and their impact on Arctic sea ice needs to be further explored.In this study,we investigate the relationship between sea-ice variation and different atmospheric diagnostics during MYLA and other La Niña(OTLA)years.The decline in BKS sea ice during MYLA winters is significantly stronger than that during OTLA years.This is because MYLA events tend to be accompanied by a warm Arctic-cold continent pattern with a barotropic high pressure blocked over the Urals region.Consequently,more frequent northward atmospheric rivers intrude into the BKS,intensifying longwave radiation downward to the underlying surface and melting the BKS sea ice.However,in the early winter of OTLA years,a negative North Atlantic Oscillation presents in the high latitudes of the Northern Hemisphere,which obstructs the atmospheric rivers to the south of Iceland.We infer that such a different response of BKS sea-ice decline to different La Niña events is related to stratospheric processes.Considering the rapid climate changes in the past,more frequent MYLA events may account for the substantial Arctic sea-ice loss in recent decades.
基金support to UID Centro de Estudos do Ambiente e Mar(CESAM)+LA/P/0094/2020,through national funds.We further acknowledge FCT for the funding of projects SOILCOMBAT,TRUESOIL(https://doi.org/10.54499/PTDC/EAM-AMB/0474/2020https://doi.org/10.54499/EJPSo ils/0001/2021),and SOILSPONGE project no 16808(COMPETE2030-FEDER-00799200)as well as of authors B.Gholamahmadi(https://doi.org/10.54499/2020.04610.BD)(WATERDESERT,PhD thesis),F.Verheijen(https://doi.org/10.54499/2023.06689.CEECI ND/CP2840/CT0011),A.C.Bastos(https://doi.org/10.54499/DL57/2016/CP1482/CT0006)and C.Ferreira。
文摘Soil erosion by water poses major environmental challenges to the European viticulture sector.Biochar is recognised as a sustainable tool for combating land degradation,but few studies on the effect of biochar on soil erosion have been conducted in Mediterranean vineyards with hilly terrain and heavy rainfall.This study assesses the potential of biochar to support soil conservation by enhancing sponge function,i.e.water retention and infiltration,and reducing erodibility in sloping sandy loam soil under natural rainfall conditions.An 18-month outdoor box lysimeter experiment was conducted using bare soil,including soil amended with 4%(w/w)biochar from a Portuguese vineyard.Over the monitoring period,biochar application significantly(p<0.001)reduced the runoff coefficient by an average of 45%.Biochar reduced coarse fragment erosion by 67%,fine-earth erosion by 43%,and splash erosion by 34%,all affected(p<0.05)by rainfall intensity.The erosion rate in vineyard soil was 3 times lower(p<0.001)in biocharamended soil than in the control(3.7 vs.11.1 t ha^(-1)yr^(-1)).Improved soil structure led to a 7%reduction in bulk density,an average increase of 73%in stored water,and a 28%increase in infiltration.During drier periods,the biocharamended soil stored 171–303%more water than the control soil.We recommend a minimum monitoring period of a full hydrological cycle under natural rainfall to comprehensively capture the effect of biochar on the soil sponge function.Observed seasonal trends and atmospheric river(AR)events suggest that studies using rainfall simulations without considering antecedent soil moisture and AR variations will yield skewed data on effects.From a practical standpoint,this study showed that biochar could be a sustainable soil management solution to enhancing long-term vineyard resilience and productivity in the Mediterranean.
