The present study compares the Atlantic Meridional Overturning Circulation(AMOC)in the North Atlantic from two simulations by an oceanic general circulation model with 1°×1°and 0.1°×0.1°r...The present study compares the Atlantic Meridional Overturning Circulation(AMOC)in the North Atlantic from two simulations by an oceanic general circulation model with 1°×1°and 0.1°×0.1°resolution,respectively,which explores the sensitivity of AMOC to the resolution.The ocean model is the latest version of the LASG/IAP Climate System Model(LICOM3),and it is forced with atmospheric data from phase 2 of the Ocean Model Intercomparison Project(OMIP2).Comprehensive comparison between the two simulations indicates that the simulated AMOC is highly sensitive to the spatial resolution.The high-resolution model(LICOM-H)simulates a deeper mixed-layer depth(MLD),due to increased surface salinity,than that in the low-resolution model(LICOML)in the Labrador Sea,and it also has stronger AMOC strength(the maximum climatic mean AMOC from 1958 to 2018 is 23.4 Sv for LICOM-H and 21.2 Sv for LICOM-L)and larger variability of AMOC index(2.3 Sv for LICOM-H and 1.7 Sv for LICOM-L).These differences can mainly be attributed to two main dynamic processes that benefit from high resolution.Firstly,LICOM-H can simulate much stronger boundary currents(~0.6 m s^(-1))than LICOM-L(0.3 m s^(-1))in the upper ocean,which leads to saltier and warmer seawater being transported to the Labrador Sea,where it enhances deep convection.Secondly,in LICOM-H,the stronger variability of AMOC is related to the higher sensitivity of the MLD and transformation to the prescribed atmospheric forcing in the Labrador Sea.展开更多
Based on the plate tectonics theory,the sedimentary environment of paleotectonics along the passive continental margins on both sides of the South Atlantic Ocean was reconstructed using the paleomagnetic,regional geol...Based on the plate tectonics theory,the sedimentary environment of paleotectonics along the passive continental margins on both sides of the South Atlantic Ocean was reconstructed using the paleomagnetic,regional geological,and seismic data,and the intrinsic relationships of hydrocarbon distribution in the passive continental margin basins and the differential hydrocarbon accumulation patterns were analyzed.Results show that basins on both sides of the South Atlantic experienced two major extensional phases—rift and depression—and four evolutionary stages:the Early Cretaceous Berriasian-Barremian intracontinental rift stage,the Early Cretaceous Aptian-Albian intercontinental rift to initial drift transition stage,the Late Cretaceous-Paleogene drift-related marine transgressive depression stage,and the Neogene-Quaternary drift-related marine regressive depression stage.According to basin architecture and superposition style,the passive-margin basins are classified into two principal types:rift-continental marginal depression composite and continental marginal depression-dominated.The basins in the study area were further divided into six types based on the development degree of salt tectonics and the type of dominant sand bodies,i.e.salt-free rift-continental marginal gravity-flow composite type,salt-free rift-continental marginal delta composite type,salt-bearing rift-continental marginal gravity flow composite type,delta-dominated salt-bearing rift-continental marginal delta composite type,gravity-flow-dominated continental marginal depression type,and delta-dominated continental marginal depression type.The salt-free rift-continental marginal gravity flow and delta composite basins are mainly distributed in the southern segment.The salt-bearing rift-continental marginal gravity flow and delta composite basins are mainly distributed in the central segment.The gravity-flow-dominated continental marginal depression basins are mainy distributed in the northern segment.The delta-dominated passive-margin depression basins are distributed in three segments from north to south.In different types of basins,distinctive depositional systems and source-reservoir-caprock assemblages were formed in each upper/lower structure layer.The superimposition and evolution of multi-phase prototype basins result in the orderly hydrocarbon accumulation vertically and laterally,which are“segmented along-strike,zoned across-strike,and layered vertically”.展开更多
The Equatorial Atlantic Ocean,a region crucial to understanding Earth’s tectonic processes and advancing the theory of plate tectonics,remains the focus of extensive research aimed at unraveling its evolution.However...The Equatorial Atlantic Ocean,a region crucial to understanding Earth’s tectonic processes and advancing the theory of plate tectonics,remains the focus of extensive research aimed at unraveling its evolution.However,its complex structural setting and contentious formation timeline have posed significant challenges.Through a comprehensive review of contemporary scientific litera-ture,we have identified three distinct phases for its evolution:pre-breakup,syn-breakup,and post-breakup,providing more detailed in-sights into the tectonic evolution of the Equatorial Atlantic.Prior to 110 Myr,the African and South American Plates underwent stretching predominantly from North to South,with the emergence of the Parana plume.This condition has led to the formation of nu-merous fracture zones and a triple junction.During the syn-breakup phase,spanning from 110 Myr to 90 Myr,the central region of the Equatorial Atlantic fully opened up,establishing a connection between the northern and southern waterways.However,the develop-ment of multiple ridge segments separated by numerous fracture zones in the central Equatorial Atlantic exhibited considerable com-plexity.The underlying causes for these complex structural formations remain elusive.Following the Chicxulub meteorite impact around 66 Myr and the emergence of the Sierra Leone hotspot,a pair of oceanic plateau‘twins’and a series of seamount chains were formed as a result of mantle plume tails.Consequently,the timeline of the Equatorial Atlantic’s tectonic evolution has gradually be-come clearer.However,due to the extensive timescale and the multitude of events involved in its formation,disputes about the precise-timing of various events still remain.The evolution of the Equatorial Atlantic has witnessed numerous ridge propagations,hotspot formations,and meteorite impacts,highlighting the need for further investigation into their interactions.The absence of identified magnetic isochrons in the Equatorial region emphasizes the urgency of additional exploration and analysis of its geological and geo-physical data.展开更多
Atlantic salmon(Salmo salar)represents the primary species in aquaculture.The gut microbiota plays a crucial role in nutrient processing and protection against pathogenic bacteria.Nonetheless,the composition and funct...Atlantic salmon(Salmo salar)represents the primary species in aquaculture.The gut microbiota plays a crucial role in nutrient processing and protection against pathogenic bacteria.Nonetheless,the composition and functionality of the gut microbiota in Salmo salar at different growth stages remain largely unexplored.This study investigated the alterations within the gut microbial communities and their associated metabolites across different growth stages of Salmo salar,specifically when the body weights were 1.0 kg(S1 group),2.0 kg(S2 group),4.0 kg(S3 group),and 6.0 kg(S4 group),using microbiome sequencing and liquid chromatographymass spectrometry(LC-MS)technology.Results indicated significant changes in the gut microbiota and metabolite profiles concurrent with fish growth.Notably,the abundance of Firmicutes decreased,and Proteobacteria increased,resulting in a decreased Firmicutes/Bacteroidetes(F/B)ratio.Concurrently,the abundance of potential pathogenic bacteria such as Stenotrophomonas,Vibrio,Aeromonas,Staphylococcaceae,Enterobacteriaceae,Enterococcaceae,and Haemophilus increased,whereas beneficial bacteria like Lactobacillus and Bacilli decreased.The gut microbiota in the S1 group exhibited an increase in the abundance of beneficial bacteria.Conversely,in the S2,S3,and S4 groups,the prevalence of pathogenic bacteria increased.Metabolic profiling revealed significant upregulation of arachidonic acid(ARA)and taurine in the S2 and S3 groups,while citric acid,riboflavin,and pantothenic acid notably increased in the S4 group.Particularly,several amino acids such as threonine,lysine,and serine in the gut microbiota metabolites were significantly reduced in the S2,S3,and S4 groups,correlating positively with the respective essential amino acid concentrations in muscle tissue.The S1 group exhibited a more active gut microbiota associated with amino acid metabolism,resulting in higher muscle amino acid content.This study identified gut microbiota and its metabolic products at different growth stages of Salmo salar,providing a scientific basis for proactive intervention of gut microbiota and improve the quality of aquatic products.展开更多
Although hunting in the north-eastern Atlantic forest of Brazil began more than 500 years ago, no study to date has evaluated its impacts on the region’s mammalian fauna. For one year we carried out diurnal and noctu...Although hunting in the north-eastern Atlantic forest of Brazil began more than 500 years ago, no study to date has evaluated its impacts on the region’s mammalian fauna. For one year we carried out diurnal and nocturnal surveys using the Line Transect method in seven forest fragments varying from 7.32 ha to 469.76 ha, within a 4000 ha forest island archipelago, in Pernambuco State, Atlantic forest of northeastern Brazil. We calculated species density, population size, biomass and synergetic biomass, and recorded direct and indirect human impacts along the study transects. We recorded 44 mammalian species, of which 45.5% (n = 20) went extinct through hunting. The smallest forest fragment had the lowest richness, diversity, population size, and total biomass. It also had no synergetic biomass. The largest fragment had the highest richness, total density, and population size. There was a statistically significant relationship between fragment area and number of gunshots heard and suspended hunting platforms found;between population size and gunshots heard, suspended hunting platforms, free-roaming and feral dogs, and between total density and free-roaming and feral dogs. After more than 500 years of colonization hunting is still devastating, with larger fragments being linked to more hunters. Higher mammal abundances attracted more free-roaming and feral dogs, which have adapted to hunt wildlife on their own. Unless we protect every single forest fragment and create sustainable landscapes, we will not be able to save this hotspot’s hotspot.展开更多
On December 12,2020,I cast off with Argo,my trusty boat,for a solo voyage across the Atlantic.As we departed San Sebastian at dawn,the exhaustion from preparation already had me longing for sleep,which was a strange d...On December 12,2020,I cast off with Argo,my trusty boat,for a solo voyage across the Atlantic.As we departed San Sebastian at dawn,the exhaustion from preparation already had me longing for sleep,which was a strange desire on the very first day of what was to be a 70⁃day expedition.展开更多
The Pacific Meridional Mode(PMM)and the Atlantic Meridional Mode(AMM)are key modes of interannual sea surface temperature(SST)variability in the Pacific and Atlantic Oceans,respectively.Analysis of CMIP6 model outputs...The Pacific Meridional Mode(PMM)and the Atlantic Meridional Mode(AMM)are key modes of interannual sea surface temperature(SST)variability in the Pacific and Atlantic Oceans,respectively.Analysis of CMIP6 model outputs reveals a robust intensification of the PMM under global warming,whereas the AMM exhibits no consensus among models.These different responses are attributed to mid-to-high latitude atmospheric forcing and subtropical feedback mechanisms.Changes in the upper-level westerly jet drive distinct atmospheric variability over the North Pacific and Atlantic,amplifying sea-level pressure variations associated with the PMM but weakening those linked to the AMM.The SST response to atmospheric forcing shows an increase in the Pacific and a decrease in the Atlantic,both of which are significantly positively correlated with the respective changes in each mode.The enhanced wind-evaporation-SST(WES)feedback,primarily driven by rising background SSTs,positively impacts the intensification of both modes.In the subtropical Pacific,the PMM is further strengthened by an increasing latent heat flux response.The enhancement of the PMM is principally connected to intensified atmospheric forcing and strengthened subtropical feedback.Although the WES feedback is enhanced to some extent,wind anomalies that oppose the climatological state reduce latent heat flux.Combined with the weakening of atmospheric forcing over the Atlantic,this phenomenon contributes to the uncertainty in the AMM's response to global warming.展开更多
Southwest China(SWC)is one of the major grain-producing areas in China,and the surface air temperature(SAT)during autumn has a substantial influence on grain production and planting.It is therefore important to unders...Southwest China(SWC)is one of the major grain-producing areas in China,and the surface air temperature(SAT)during autumn has a substantial influence on grain production and planting.It is therefore important to understand temporal changes in the SAT over SWC(SWC-SAT).Our analysis of observational and reanalysis datasets shows that the autumn SWC-SAT exhibits significant multidecadal variability.A significantly strong positive correlation also exists between the autumn SWC-SAT and the Atlantic multidecadal oscillation(AMO)time series(correlation coefficient of 0.85).These results suggest that the AMO is a remote driver of multidecadal variability in the autumn SWC-SAT.Further analyses show that the North Atlantic sea surface temperature anomalies(SSTA)associated with the AMO modulate the multidecadal variability of the autumn SWC-SAT through triggering the Africa-Asia multidecadal teleconnection(AAMT)pattern.Specifically,the AAMT corresponds to geopotential height anomalies over SWC,which adjust the local thickness of the air column and thereby induce multidecadal variability of the autumn SWC-SAT.This potential mechanism,derived from observational and reanalysis datasets,was verified by using a linear barotropic model and the Community Atmosphere Model version 4.Our results from combining observations and numerical modeling simulations indicate that the North Atlantic SSTA may act as a key pacemaker for the multidecadal SAT variability over SWC.展开更多
Compound extreme climate events involving multiple meteorological elements usually have a more severe impact on the environment and human health than single-element extreme events.However,the current definition of mul...Compound extreme climate events involving multiple meteorological elements usually have a more severe impact on the environment and human health than single-element extreme events.However,the current definition of multi-element compound extreme events is proposed from meteorological and statistical perspectives,without integrating health data,making the conclusions less practical for guiding health risk prevention.This study identified the threshold for hot–dry compound extreme events with high mortality risks(HMHDs)in China,using daily mortality data and temperature–humidity data from 278 districts or counties,and explored the interdecadal change and driving mechanisms of HMHD frequency in China from 1979 to 2021.The results show a significant increase in annual HMHD frequency in China after 2000,mainly occurring in summer(June,July,August).The northwestern to western regions of China(Xinjiang,Inner Mongolia,Gansu),and from the southwestern to the areas south of the Yangtze River(Sichuan,Hubei,Hunan,Jiangxi,Fujian,Guizhou,Yunnan),experience an increase of>10 days.The authors find that the interdecadal abrupt change in HMHD frequency can be attributed to the shift of the Atlantic Multidecadal Oscillation from a negative to a positive phase by affecting the Silk Road teleconnection.展开更多
Since the publication of The Black Atlantic:Modernity and Double Consciousness(1993),the concept of the“Black Atlantic”has become a key paradigm in diaspora studies and cultural criticism.The“Black Atlantic”challe...Since the publication of The Black Atlantic:Modernity and Double Consciousness(1993),the concept of the“Black Atlantic”has become a key paradigm in diaspora studies and cultural criticism.The“Black Atlantic”challenges the historical dominance of Western-centered Atlantic history by situating slavery,forced migration,and diasporic intellectual production as central components of modernity itself.This essay re-examines the meaning of the“Black Atlantic”by situating it against Eurocentric Atlantic history,exploring its philosophical dialogue with modernity,interrogating its relationship with Marxism,and reassessing its significance in the context of globalization.In doing so,it seeks to clarify both the transformative power and the limitations of Gilroy’s paradigm while also suggesting directions for future scholarship that reconnect the“Black Atlantic”to Africa,Marxism,and anti-capitalist critique.展开更多
This study investigated the fluctuations in the relationship between the Silk Road Pattern(SRP)and the boreal summer North Atlantic Oscillation(SNAO).The results indicated that the SRP–SNAO relationship was relativel...This study investigated the fluctuations in the relationship between the Silk Road Pattern(SRP)and the boreal summer North Atlantic Oscillation(SNAO).The results indicated that the SRP–SNAO relationship was relatively weak during 1958–2022,which was primarily due to fluctuations,particularly the reversal in their relationship since the late 1990s.Using wavelet coherence analysis,the authors identified a strong SRP–SNAO linkage on a 4–8-yr timescale,in particular during the mid-1970s to the early/mid-1990s.This strong linkage is mainly attributable to the intensification and eastward movement of the southern part of the SNAO around the mid/late 1970s,which favored the strong connection between the SNAO and the SRP.Additionally,the interdecadal changes of the atmospheric circulations over the North Atlantic and Eurasia around the mid/late 1970s that resembled the circulation anomalies related to the strong SRP–SNAO linkage,may also have provided a favorable background for the strong connection between the two teleconnections.These findings on the fluctuations in the SRP–SNAO linkage may offer important implications for understanding the impact of the SNAO on the SRP and the variability of the SRP.展开更多
This study examined the impact of the preceding boreal summer(June–August) North Atlantic Oscillation(NAO) on early autumn(September) rainfall over Central China(RCC). The results show that a significant positive cor...This study examined the impact of the preceding boreal summer(June–August) North Atlantic Oscillation(NAO) on early autumn(September) rainfall over Central China(RCC). The results show that a significant positive correlation exists between the preceding summer NAO and the early autumn RCC on the interannual timescale. In order to understand the physical mechanism between them, the role of ocean was investigated. It was found that the strong summer NAO can induce a tripole sea surface temperature anomaly(SSTA) in the North Atlantic; this SSTA pattern can persist until early autumn. The diagnostic analysis showed that the tripole SSTA pattern excites a downstream Atlantic-Eurasian(AEA) teleconnection, which contributes to an increase in RCC. The circulation anomalies related to SSTA caused by the weak NAO are opposite, so the RCC is less than normal. The results imply that the preceding summer NAO may be regarded as a forecast factor for the early autumn RCC.展开更多
In this study,physical mechanism of the impacts of the tropical Atlantic sea surface temperature(SST)on decadal change of the summer North Atlantic Oscillation(SNAO)was explored using an atmospheric general circulatio...In this study,physical mechanism of the impacts of the tropical Atlantic sea surface temperature(SST)on decadal change of the summer North Atlantic Oscillation(SNAO)was explored using an atmospheric general circulation model(AGCM)developed at the International Centre for Theoretical Physics(ICTP).The simulation results indicate that the decadal warming of the SST over the tropical Atlantic after the late 1970s could have significantly enhanced the convection over the region.This enhanced convection would have strengthened the local meridional circulation over the Eastern Atlantic-North Africa-Western Europe region,exciting a meridional teleconnection.This teleconnection might have brought the signal of the tropical Atlantic SST to the Extratropics,consequently activating the variability of the eastern part of the SNAO southern center,which led to an eastward shift of the SNAO southern center around the late 1970s.Such physical processes are highly consistent with the previous observations.展开更多
Effects of extratropical solar penetration on the North Atlantic Ocean circulation and climate are investigated using a coupled ocean-atmosphere model.In this model,solar penetration generates basinwide cooling and wa...Effects of extratropical solar penetration on the North Atlantic Ocean circulation and climate are investigated using a coupled ocean-atmosphere model.In this model,solar penetration generates basinwide cooling and warming in summer and winter,respectively.Associated with SST changes,annual mean surface wind stress is intensified in both the subtropical and subpolar North Atlantic,which leads to acceleration of both subtropical and subpolar gyres.Owing to warming in the subtropics and significant saltiness in the subpolar region,potential density decreases(increases) in the subtropical(subpolar)North Atlantic.The north-south meridional density gradient is thereby enlarged,accelerating the Atlantic meridional overturning circulation(AMOC).In addition,solar penetration reduces stratification in the upper ocean and favors stronger vertical convection,which also contributes to acceleration of the AMOC.展开更多
Early studies suggested that the Aleutian–Icelandic low seesaw(AIS) features multidecadal variation. In this study, the multidecadal modulation of the AIS and associated surface climate by the Atlantic Multidecadal O...Early studies suggested that the Aleutian–Icelandic low seesaw(AIS) features multidecadal variation. In this study, the multidecadal modulation of the AIS and associated surface climate by the Atlantic Multidecadal Oscillation(AMO) during late winter(February–March) is explored with observational data. It is shown that, in the cold phase of the AMO(AMO|-),a clear AIS is established, while this is not the case in the warm phase of the AMO(AMO|+). The surface climate over Eurasia is significantly influenced by the AMO’s modulation of the Aleutian low(AL). For example, the weak AL in AMO|-displays warmer surface temperatures over the entire Far East and along the Russian Arctic coast and into Northern Europe,but only over the Russian Far East in AMO|+. Similarly, precipitation decreases over central Europe with the weak AL in AMO|-, but decreases over northern Europe and increases over southern Europe in AMO|+.The mechanism underlying the influence of AMO|-on the AIS can be described as follows: AMO|-weakens the upward component of the Eliassen–Palm flux along the polar waveguide by reducing atmospheric blocking occurrence over the Euro–Atlantic sector, and hence drives an enhanced stratospheric polar vortex. With the intensified polar night jet, the wave trains originating over the central North Pacific can propagate horizontally through North America and extend into the North Atlantic, favoring an eastward-extended Pacific–North America–Atlantic pattern, and resulting in a significant AIS at the surface during late winter.展开更多
Based on reanalysis data from 1979 to 2016,this study focuses on the sea surface temperature(SST)anomaly of the tropical North Atlantic(TNA)in El Nino decaying years.The TNA SST exhibits a clear warm trend during this...Based on reanalysis data from 1979 to 2016,this study focuses on the sea surface temperature(SST)anomaly of the tropical North Atlantic(TNA)in El Nino decaying years.The TNA SST exhibits a clear warm trend during this period.The composite result for 10 El Nino events shows that the TNA SST anomaly reaches its maximum in spring after the peak of an El Nino event and persists until summer.In general,the anomaly is associated with three factors-namely,El Nino,the North Atlantic Oscillation(NAO),and a long-term trend,leading to an increase in local SST up to 0.4℃,0.3℃,and 0.35℃,respectively.A comparison between 1983 and 2005 indicates that the TNA SST in spring is affected by El Niño,as well as the local SST in the preceding winter,which may involve a long-term trend signal.In addition,the lead-lag correlation shows that the NAO leads the TNA SST by 2-3 months.By comparing two years with an opposite phase of the NAO in winter(i.e.,1992 and 2010),the authors further demonstrate that the NAO is another important factor in regulating the TNA SST anomaly.A negative phase of the NAO in winter will reinforce the El Nino forcing substantially,and vise versa.In other words,the TNA SST anomaly in the decaying years is more evident if the NAO is negative with El Nino.Therefore,the combined effects of El Nino and the NAO must be considered in order to fully understand the TNA SST variability along with a long-term trend.展开更多
A strong （weak） East Asian summer monsoon （EASM） is usually concurrent with the tripole pattern of North Atlantic SST anomalies on the interannual timescale during summer, which has positive （negative） SST anoma...A strong （weak） East Asian summer monsoon （EASM） is usually concurrent with the tripole pattern of North Atlantic SST anomalies on the interannual timescale during summer, which has positive （negative） SST anomalies in the northwestern North Atlantic and negative （positive） SST anomalies in the subpolar and tropical ocean. The mechanisms responsible for this linkage are diagnosed in the present study. It is shown that a barotropie wave-train pattern occurring over the Atlantic-Eurasia region likely acts as a link between the EASM and the SST tripole during summer. This wave-train pattern is concurrent with geopotential height anomalies over the Ural Mountains, which has a substantial effect on the EASM. Diagnosis based on observations and linear dynamical model results reveals that the mechanism for maintaining the wave-train pattern involves both the anomalous diabatic heating and synoptic eddy-vorticity forcing. Since the North Atlantic SST tripole is closely coupled with the North Atlantic Oscillation （NAO）, the relationships between these two factors and the EASM are also examined. It is found that the connection of the EASM with the summer SST tripole is sensitive to the meridional location of the tripole, which is characterized by large seasonal variations due to the north-south movement of the activity centers of the NAO. The SST tripole that has a strong relationship with the EASM appears to be closely coupled with the NAO in the previous spring rather than in the simultaneous summer.展开更多
The Atlantic Multidecadal Oscillation （AMO）, the multidecadal variation of North Atlantic sea surface temperature （SST）, exhibits an oscillation with a period of 65-80 years and an amplitude of 0.4℃. Observationa...The Atlantic Multidecadal Oscillation （AMO）, the multidecadal variation of North Atlantic sea surface temperature （SST）, exhibits an oscillation with a period of 65-80 years and an amplitude of 0.4℃. Observational composite analyses reveal that the warm phase AMO is linked to warmer winters in East China, with enhanced precipitation in the north of this region and reduced precipitation in the south, on multidecadal time scales. The pattern is reversed during the cold phase AMO. Whether the AMO acts as a forcing of the multidecadal winter climate of East China is explored by investigating the atmospheric response to warm AMO SST anomalies in a large ensemble of atmospheric general circulation model （AGCM） experiments. The results from three AGCMs are consistent and suggest that the AMO warmth favors warmer winters in East China. This influence is realized through inducing negative surface air pressure anomalies in the hemispheric-wide domain extending from the midlatitude North Atlantic to midlatitude Eurasia. These negative surface anomalies favor the weakening of the Mongolian Cold High, and thus induce a weaker East Asian Winter Monsoon.展开更多
A new North Atlantic Oscillation (NAO) index, the NAOI, is defined as the differences of normalized sea level pressures regionally zonal-averaged over a broad range of longitudes 80°W-30°E. A comprehensive c...A new North Atlantic Oscillation (NAO) index, the NAOI, is defined as the differences of normalized sea level pressures regionally zonal-averaged over a broad range of longitudes 80°W-30°E. A comprehensive comparison of six NAO indices indicates that the new NAOI provides a more faithful representation of the spatial-temporal variability associated with the NAO on all timescales. A very high signal-to-noise ratio for the NAOI exists for all seasons, and the life cycle represented by the NAOI describes well the seasonal migration for action centers of the NAO. The NAOI captures a larger fraction of the variance of sea level pressure over the North Atlantic sector (20°-90°N, 80°W-30°E), on average 10% more than any other NAO index. There are quite different relationships between the NAOI and surface air temperature during winter and summer. A novel feature, however, is that the NAOI is significantly negative correlated with surface air temperature over the North Atlantic Ocean between 10°-25°N and 70°-30°W, whether in winter or summer. From 1873, the NAOI exhibits strong interannual and decadal variability. Its interannual variability of the twelve calendar months is obviously phase-locked with the seasonal cycle. Moreover, the annual NAOI exhibits a clearer decadal variability in amplitude than the winter NAOI. An upward trend is found in the annual NAOI between the 1870s and 1910s, while the other winter NAO indices fail to show this tendency. The annual NAOI exhibits a strongly positive epoch of 50 years between 1896 and 1950. After 1950, the variability of the annual NAOI is very similar to that of the winter NAO indices.展开更多
基金supported by the National Natural Science Foundation of China [grant number 92358302]。
文摘The present study compares the Atlantic Meridional Overturning Circulation(AMOC)in the North Atlantic from two simulations by an oceanic general circulation model with 1°×1°and 0.1°×0.1°resolution,respectively,which explores the sensitivity of AMOC to the resolution.The ocean model is the latest version of the LASG/IAP Climate System Model(LICOM3),and it is forced with atmospheric data from phase 2 of the Ocean Model Intercomparison Project(OMIP2).Comprehensive comparison between the two simulations indicates that the simulated AMOC is highly sensitive to the spatial resolution.The high-resolution model(LICOM-H)simulates a deeper mixed-layer depth(MLD),due to increased surface salinity,than that in the low-resolution model(LICOML)in the Labrador Sea,and it also has stronger AMOC strength(the maximum climatic mean AMOC from 1958 to 2018 is 23.4 Sv for LICOM-H and 21.2 Sv for LICOM-L)and larger variability of AMOC index(2.3 Sv for LICOM-H and 1.7 Sv for LICOM-L).These differences can mainly be attributed to two main dynamic processes that benefit from high resolution.Firstly,LICOM-H can simulate much stronger boundary currents(~0.6 m s^(-1))than LICOM-L(0.3 m s^(-1))in the upper ocean,which leads to saltier and warmer seawater being transported to the Labrador Sea,where it enhances deep convection.Secondly,in LICOM-H,the stronger variability of AMOC is related to the higher sensitivity of the MLD and transformation to the prescribed atmospheric forcing in the Labrador Sea.
基金Supported by the China National Science and Technology Major Project(2025ZD400801)CNPC Science and Technology Major Project(2023ZZ07-01)。
文摘Based on the plate tectonics theory,the sedimentary environment of paleotectonics along the passive continental margins on both sides of the South Atlantic Ocean was reconstructed using the paleomagnetic,regional geological,and seismic data,and the intrinsic relationships of hydrocarbon distribution in the passive continental margin basins and the differential hydrocarbon accumulation patterns were analyzed.Results show that basins on both sides of the South Atlantic experienced two major extensional phases—rift and depression—and four evolutionary stages:the Early Cretaceous Berriasian-Barremian intracontinental rift stage,the Early Cretaceous Aptian-Albian intercontinental rift to initial drift transition stage,the Late Cretaceous-Paleogene drift-related marine transgressive depression stage,and the Neogene-Quaternary drift-related marine regressive depression stage.According to basin architecture and superposition style,the passive-margin basins are classified into two principal types:rift-continental marginal depression composite and continental marginal depression-dominated.The basins in the study area were further divided into six types based on the development degree of salt tectonics and the type of dominant sand bodies,i.e.salt-free rift-continental marginal gravity-flow composite type,salt-free rift-continental marginal delta composite type,salt-bearing rift-continental marginal gravity flow composite type,delta-dominated salt-bearing rift-continental marginal delta composite type,gravity-flow-dominated continental marginal depression type,and delta-dominated continental marginal depression type.The salt-free rift-continental marginal gravity flow and delta composite basins are mainly distributed in the southern segment.The salt-bearing rift-continental marginal gravity flow and delta composite basins are mainly distributed in the central segment.The gravity-flow-dominated continental marginal depression basins are mainy distributed in the northern segment.The delta-dominated passive-margin depression basins are distributed in three segments from north to south.In different types of basins,distinctive depositional systems and source-reservoir-caprock assemblages were formed in each upper/lower structure layer.The superimposition and evolution of multi-phase prototype basins result in the orderly hydrocarbon accumulation vertically and laterally,which are“segmented along-strike,zoned across-strike,and layered vertically”.
基金supported by the National Natural Science Foundation of China(Nos.42376071,42006056)the Special Fund of South China Sea Institute of Oceanol-ogy of the Chinese Academy of Sciences(No.SCSIO 2024QY02)the Chinese Academy of Sciences Pro-ject(No.Y4SL021).
文摘The Equatorial Atlantic Ocean,a region crucial to understanding Earth’s tectonic processes and advancing the theory of plate tectonics,remains the focus of extensive research aimed at unraveling its evolution.However,its complex structural setting and contentious formation timeline have posed significant challenges.Through a comprehensive review of contemporary scientific litera-ture,we have identified three distinct phases for its evolution:pre-breakup,syn-breakup,and post-breakup,providing more detailed in-sights into the tectonic evolution of the Equatorial Atlantic.Prior to 110 Myr,the African and South American Plates underwent stretching predominantly from North to South,with the emergence of the Parana plume.This condition has led to the formation of nu-merous fracture zones and a triple junction.During the syn-breakup phase,spanning from 110 Myr to 90 Myr,the central region of the Equatorial Atlantic fully opened up,establishing a connection between the northern and southern waterways.However,the develop-ment of multiple ridge segments separated by numerous fracture zones in the central Equatorial Atlantic exhibited considerable com-plexity.The underlying causes for these complex structural formations remain elusive.Following the Chicxulub meteorite impact around 66 Myr and the emergence of the Sierra Leone hotspot,a pair of oceanic plateau‘twins’and a series of seamount chains were formed as a result of mantle plume tails.Consequently,the timeline of the Equatorial Atlantic’s tectonic evolution has gradually be-come clearer.However,due to the extensive timescale and the multitude of events involved in its formation,disputes about the precise-timing of various events still remain.The evolution of the Equatorial Atlantic has witnessed numerous ridge propagations,hotspot formations,and meteorite impacts,highlighting the need for further investigation into their interactions.The absence of identified magnetic isochrons in the Equatorial region emphasizes the urgency of additional exploration and analysis of its geological and geo-physical data.
基金supported by the Key R&D Program of Shandong Province(No.2021LZGC027)the Shandong Provincial Natural Science Foundation(No.ZR202102250235)+1 种基金the Major Agricultural Application Technology Innovation Projects in Shandong Province(No.SD2019YY 006)the‘First Class Fishery Discipline’Program in Shandong Province,China。
文摘Atlantic salmon(Salmo salar)represents the primary species in aquaculture.The gut microbiota plays a crucial role in nutrient processing and protection against pathogenic bacteria.Nonetheless,the composition and functionality of the gut microbiota in Salmo salar at different growth stages remain largely unexplored.This study investigated the alterations within the gut microbial communities and their associated metabolites across different growth stages of Salmo salar,specifically when the body weights were 1.0 kg(S1 group),2.0 kg(S2 group),4.0 kg(S3 group),and 6.0 kg(S4 group),using microbiome sequencing and liquid chromatographymass spectrometry(LC-MS)technology.Results indicated significant changes in the gut microbiota and metabolite profiles concurrent with fish growth.Notably,the abundance of Firmicutes decreased,and Proteobacteria increased,resulting in a decreased Firmicutes/Bacteroidetes(F/B)ratio.Concurrently,the abundance of potential pathogenic bacteria such as Stenotrophomonas,Vibrio,Aeromonas,Staphylococcaceae,Enterobacteriaceae,Enterococcaceae,and Haemophilus increased,whereas beneficial bacteria like Lactobacillus and Bacilli decreased.The gut microbiota in the S1 group exhibited an increase in the abundance of beneficial bacteria.Conversely,in the S2,S3,and S4 groups,the prevalence of pathogenic bacteria increased.Metabolic profiling revealed significant upregulation of arachidonic acid(ARA)and taurine in the S2 and S3 groups,while citric acid,riboflavin,and pantothenic acid notably increased in the S4 group.Particularly,several amino acids such as threonine,lysine,and serine in the gut microbiota metabolites were significantly reduced in the S2,S3,and S4 groups,correlating positively with the respective essential amino acid concentrations in muscle tissue.The S1 group exhibited a more active gut microbiota associated with amino acid metabolism,resulting in higher muscle amino acid content.This study identified gut microbiota and its metabolic products at different growth stages of Salmo salar,providing a scientific basis for proactive intervention of gut microbiota and improve the quality of aquatic products.
文摘Although hunting in the north-eastern Atlantic forest of Brazil began more than 500 years ago, no study to date has evaluated its impacts on the region’s mammalian fauna. For one year we carried out diurnal and nocturnal surveys using the Line Transect method in seven forest fragments varying from 7.32 ha to 469.76 ha, within a 4000 ha forest island archipelago, in Pernambuco State, Atlantic forest of northeastern Brazil. We calculated species density, population size, biomass and synergetic biomass, and recorded direct and indirect human impacts along the study transects. We recorded 44 mammalian species, of which 45.5% (n = 20) went extinct through hunting. The smallest forest fragment had the lowest richness, diversity, population size, and total biomass. It also had no synergetic biomass. The largest fragment had the highest richness, total density, and population size. There was a statistically significant relationship between fragment area and number of gunshots heard and suspended hunting platforms found;between population size and gunshots heard, suspended hunting platforms, free-roaming and feral dogs, and between total density and free-roaming and feral dogs. After more than 500 years of colonization hunting is still devastating, with larger fragments being linked to more hunters. Higher mammal abundances attracted more free-roaming and feral dogs, which have adapted to hunt wildlife on their own. Unless we protect every single forest fragment and create sustainable landscapes, we will not be able to save this hotspot’s hotspot.
文摘On December 12,2020,I cast off with Argo,my trusty boat,for a solo voyage across the Atlantic.As we departed San Sebastian at dawn,the exhaustion from preparation already had me longing for sleep,which was a strange desire on the very first day of what was to be a 70⁃day expedition.
基金the National Natural Science Foundation of China(Nos.42230405,41975092)the National Key R&D Program of China(No.2023YFF0805100)+1 种基金the Shandong Natural Science Foundation Project(No.ZR2019ZD12)the Taishan Scholars Project of Shandong Province(No.tsqn202306095)。
文摘The Pacific Meridional Mode(PMM)and the Atlantic Meridional Mode(AMM)are key modes of interannual sea surface temperature(SST)variability in the Pacific and Atlantic Oceans,respectively.Analysis of CMIP6 model outputs reveals a robust intensification of the PMM under global warming,whereas the AMM exhibits no consensus among models.These different responses are attributed to mid-to-high latitude atmospheric forcing and subtropical feedback mechanisms.Changes in the upper-level westerly jet drive distinct atmospheric variability over the North Pacific and Atlantic,amplifying sea-level pressure variations associated with the PMM but weakening those linked to the AMM.The SST response to atmospheric forcing shows an increase in the Pacific and a decrease in the Atlantic,both of which are significantly positively correlated with the respective changes in each mode.The enhanced wind-evaporation-SST(WES)feedback,primarily driven by rising background SSTs,positively impacts the intensification of both modes.In the subtropical Pacific,the PMM is further strengthened by an increasing latent heat flux response.The enhancement of the PMM is principally connected to intensified atmospheric forcing and strengthened subtropical feedback.Although the WES feedback is enhanced to some extent,wind anomalies that oppose the climatological state reduce latent heat flux.Combined with the weakening of atmospheric forcing over the Atlantic,this phenomenon contributes to the uncertainty in the AMM's response to global warming.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2442210,42175042,and 42275059)the Natural Science Foundation of Sichuan Province(Grant No.2024NSFTD0017)+1 种基金the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0103)the Natural Science Foundation of Chongqing(Grant No.cstc2021jcyj-msxmX0698).
文摘Southwest China(SWC)is one of the major grain-producing areas in China,and the surface air temperature(SAT)during autumn has a substantial influence on grain production and planting.It is therefore important to understand temporal changes in the SAT over SWC(SWC-SAT).Our analysis of observational and reanalysis datasets shows that the autumn SWC-SAT exhibits significant multidecadal variability.A significantly strong positive correlation also exists between the autumn SWC-SAT and the Atlantic multidecadal oscillation(AMO)time series(correlation coefficient of 0.85).These results suggest that the AMO is a remote driver of multidecadal variability in the autumn SWC-SAT.Further analyses show that the North Atlantic sea surface temperature anomalies(SSTA)associated with the AMO modulate the multidecadal variability of the autumn SWC-SAT through triggering the Africa-Asia multidecadal teleconnection(AAMT)pattern.Specifically,the AAMT corresponds to geopotential height anomalies over SWC,which adjust the local thickness of the air column and thereby induce multidecadal variability of the autumn SWC-SAT.This potential mechanism,derived from observational and reanalysis datasets,was verified by using a linear barotropic model and the Community Atmosphere Model version 4.Our results from combining observations and numerical modeling simulations indicate that the North Atlantic SSTA may act as a key pacemaker for the multidecadal SAT variability over SWC.
基金funded by the National Natural Science Foundation of China[grant number U2442202]the National Key Research and Development Program of China[grant number 2018YFA0606200]+1 种基金the Guangdong Major Project of Basic and Applied Basic Research[grant number 2020B0301030004]the Science and Technology Project of the Tibet Autonomous Region[grant number XZ202402ZD0006-06]。
文摘Compound extreme climate events involving multiple meteorological elements usually have a more severe impact on the environment and human health than single-element extreme events.However,the current definition of multi-element compound extreme events is proposed from meteorological and statistical perspectives,without integrating health data,making the conclusions less practical for guiding health risk prevention.This study identified the threshold for hot–dry compound extreme events with high mortality risks(HMHDs)in China,using daily mortality data and temperature–humidity data from 278 districts or counties,and explored the interdecadal change and driving mechanisms of HMHD frequency in China from 1979 to 2021.The results show a significant increase in annual HMHD frequency in China after 2000,mainly occurring in summer(June,July,August).The northwestern to western regions of China(Xinjiang,Inner Mongolia,Gansu),and from the southwestern to the areas south of the Yangtze River(Sichuan,Hubei,Hunan,Jiangxi,Fujian,Guizhou,Yunnan),experience an increase of>10 days.The authors find that the interdecadal abrupt change in HMHD frequency can be attributed to the shift of the Atlantic Multidecadal Oscillation from a negative to a positive phase by affecting the Silk Road teleconnection.
文摘Since the publication of The Black Atlantic:Modernity and Double Consciousness(1993),the concept of the“Black Atlantic”has become a key paradigm in diaspora studies and cultural criticism.The“Black Atlantic”challenges the historical dominance of Western-centered Atlantic history by situating slavery,forced migration,and diasporic intellectual production as central components of modernity itself.This essay re-examines the meaning of the“Black Atlantic”by situating it against Eurocentric Atlantic history,exploring its philosophical dialogue with modernity,interrogating its relationship with Marxism,and reassessing its significance in the context of globalization.In doing so,it seeks to clarify both the transformative power and the limitations of Gilroy’s paradigm while also suggesting directions for future scholarship that reconnect the“Black Atlantic”to Africa,Marxism,and anti-capitalist critique.
基金jointly supported by the National Natural Science Foundation of China[grant numbers 41605058 and 41831175]the Joint Open Project of the Key Laboratory of Meteorological Disaster,the Ministry of Education,the Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,NUIST[grant number KLME202104]。
文摘This study investigated the fluctuations in the relationship between the Silk Road Pattern(SRP)and the boreal summer North Atlantic Oscillation(SNAO).The results indicated that the SRP–SNAO relationship was relatively weak during 1958–2022,which was primarily due to fluctuations,particularly the reversal in their relationship since the late 1990s.Using wavelet coherence analysis,the authors identified a strong SRP–SNAO linkage on a 4–8-yr timescale,in particular during the mid-1970s to the early/mid-1990s.This strong linkage is mainly attributable to the intensification and eastward movement of the southern part of the SNAO around the mid/late 1970s,which favored the strong connection between the SNAO and the SRP.Additionally,the interdecadal changes of the atmospheric circulations over the North Atlantic and Eurasia around the mid/late 1970s that resembled the circulation anomalies related to the strong SRP–SNAO linkage,may also have provided a favorable background for the strong connection between the two teleconnections.These findings on the fluctuations in the SRP–SNAO linkage may offer important implications for understanding the impact of the SNAO on the SRP and the variability of the SRP.
基金supported jointly by the National Basic Research Program of China(973 program,Grant No.2013CB340203)the National Natural Science Foundation of China(NSFC)(Grant Nos.41290255 and 41205046)
文摘This study examined the impact of the preceding boreal summer(June–August) North Atlantic Oscillation(NAO) on early autumn(September) rainfall over Central China(RCC). The results show that a significant positive correlation exists between the preceding summer NAO and the early autumn RCC on the interannual timescale. In order to understand the physical mechanism between them, the role of ocean was investigated. It was found that the strong summer NAO can induce a tripole sea surface temperature anomaly(SSTA) in the North Atlantic; this SSTA pattern can persist until early autumn. The diagnostic analysis showed that the tripole SSTA pattern excites a downstream Atlantic-Eurasian(AEA) teleconnection, which contributes to an increase in RCC. The circulation anomalies related to SSTA caused by the weak NAO are opposite, so the RCC is less than normal. The results imply that the preceding summer NAO may be regarded as a forecast factor for the early autumn RCC.
基金supported by the National Basic Research Program of China(Grant No.2012CB955401)the National Natural Science Foundation of China(Grant No.40905041)
文摘In this study,physical mechanism of the impacts of the tropical Atlantic sea surface temperature(SST)on decadal change of the summer North Atlantic Oscillation(SNAO)was explored using an atmospheric general circulation model(AGCM)developed at the International Centre for Theoretical Physics(ICTP).The simulation results indicate that the decadal warming of the SST over the tropical Atlantic after the late 1970s could have significantly enhanced the convection over the region.This enhanced convection would have strengthened the local meridional circulation over the Eastern Atlantic-North Africa-Western Europe region,exciting a meridional teleconnection.This teleconnection might have brought the signal of the tropical Atlantic SST to the Extratropics,consequently activating the variability of the eastern part of the SNAO southern center,which led to an eastward shift of the SNAO southern center around the late 1970s.Such physical processes are highly consistent with the previous observations.
基金Supported by the Key Project of National Natural Science Foundation of China(No.41130859)the Innovation Team Project(No.40921004)
文摘Effects of extratropical solar penetration on the North Atlantic Ocean circulation and climate are investigated using a coupled ocean-atmosphere model.In this model,solar penetration generates basinwide cooling and warming in summer and winter,respectively.Associated with SST changes,annual mean surface wind stress is intensified in both the subtropical and subpolar North Atlantic,which leads to acceleration of both subtropical and subpolar gyres.Owing to warming in the subtropics and significant saltiness in the subpolar region,potential density decreases(increases) in the subtropical(subpolar)North Atlantic.The north-south meridional density gradient is thereby enlarged,accelerating the Atlantic meridional overturning circulation(AMOC).In addition,solar penetration reduces stratification in the upper ocean and favors stronger vertical convection,which also contributes to acceleration of the AMOC.
基金supported by the Research Council of Norway(Grant Nos.EPOCASA#229774/E10 and SNOWGLACE#244166)the National Natural Science Foundation of China(Grant No.41605059)the Young Talent Support Plan launched by the China Association for Science and Technology(Grant No.2016QNRC001)
文摘Early studies suggested that the Aleutian–Icelandic low seesaw(AIS) features multidecadal variation. In this study, the multidecadal modulation of the AIS and associated surface climate by the Atlantic Multidecadal Oscillation(AMO) during late winter(February–March) is explored with observational data. It is shown that, in the cold phase of the AMO(AMO|-),a clear AIS is established, while this is not the case in the warm phase of the AMO(AMO|+). The surface climate over Eurasia is significantly influenced by the AMO’s modulation of the Aleutian low(AL). For example, the weak AL in AMO|-displays warmer surface temperatures over the entire Far East and along the Russian Arctic coast and into Northern Europe,but only over the Russian Far East in AMO|+. Similarly, precipitation decreases over central Europe with the weak AL in AMO|-, but decreases over northern Europe and increases over southern Europe in AMO|+.The mechanism underlying the influence of AMO|-on the AIS can be described as follows: AMO|-weakens the upward component of the Eliassen–Palm flux along the polar waveguide by reducing atmospheric blocking occurrence over the Euro–Atlantic sector, and hence drives an enhanced stratospheric polar vortex. With the intensified polar night jet, the wave trains originating over the central North Pacific can propagate horizontally through North America and extend into the North Atlantic, favoring an eastward-extended Pacific–North America–Atlantic pattern, and resulting in a significant AIS at the surface during late winter.
基金supported by the National Natural Science Founda-tion of China[grant numbers 41630530 and 41861144015]the National Key Scientific and Technological Infrastructure project“Earth System Science Numerical Simulator Facility”.
文摘Based on reanalysis data from 1979 to 2016,this study focuses on the sea surface temperature(SST)anomaly of the tropical North Atlantic(TNA)in El Nino decaying years.The TNA SST exhibits a clear warm trend during this period.The composite result for 10 El Nino events shows that the TNA SST anomaly reaches its maximum in spring after the peak of an El Nino event and persists until summer.In general,the anomaly is associated with three factors-namely,El Nino,the North Atlantic Oscillation(NAO),and a long-term trend,leading to an increase in local SST up to 0.4℃,0.3℃,and 0.35℃,respectively.A comparison between 1983 and 2005 indicates that the TNA SST in spring is affected by El Niño,as well as the local SST in the preceding winter,which may involve a long-term trend signal.In addition,the lead-lag correlation shows that the NAO leads the TNA SST by 2-3 months.By comparing two years with an opposite phase of the NAO in winter(i.e.,1992 and 2010),the authors further demonstrate that the NAO is another important factor in regulating the TNA SST anomaly.A negative phase of the NAO in winter will reinforce the El Nino forcing substantially,and vise versa.In other words,the TNA SST anomaly in the decaying years is more evident if the NAO is negative with El Nino.Therefore,the combined effects of El Nino and the NAO must be considered in order to fully understand the TNA SST variability along with a long-term trend.
基金jointly supported by the National Basic Research Program of China (Grant Nos. 2010CB950404, 2013CB430203, 2010CB950501 and 2012CB955901)the National Natural Science Foundation of China (Grant No. 41205058)+1 种基金the China Postdoctoral Science Foundation (Grant No. 2012M510634)the National Science and Technology Support Program of China (Grant No. 2009BAC51B05)
文摘A strong （weak） East Asian summer monsoon （EASM） is usually concurrent with the tripole pattern of North Atlantic SST anomalies on the interannual timescale during summer, which has positive （negative） SST anomalies in the northwestern North Atlantic and negative （positive） SST anomalies in the subpolar and tropical ocean. The mechanisms responsible for this linkage are diagnosed in the present study. It is shown that a barotropie wave-train pattern occurring over the Atlantic-Eurasia region likely acts as a link between the EASM and the SST tripole during summer. This wave-train pattern is concurrent with geopotential height anomalies over the Ural Mountains, which has a substantial effect on the EASM. Diagnosis based on observations and linear dynamical model results reveals that the mechanism for maintaining the wave-train pattern involves both the anomalous diabatic heating and synoptic eddy-vorticity forcing. Since the North Atlantic SST tripole is closely coupled with the North Atlantic Oscillation （NAO）, the relationships between these two factors and the EASM are also examined. It is found that the connection of the EASM with the summer SST tripole is sensitive to the meridional location of the tripole, which is characterized by large seasonal variations due to the north-south movement of the activity centers of the NAO. The SST tripole that has a strong relationship with the EASM appears to be closely coupled with the NAO in the previous spring rather than in the simultaneous summer.
文摘The Atlantic Multidecadal Oscillation （AMO）, the multidecadal variation of North Atlantic sea surface temperature （SST）, exhibits an oscillation with a period of 65-80 years and an amplitude of 0.4℃. Observational composite analyses reveal that the warm phase AMO is linked to warmer winters in East China, with enhanced precipitation in the north of this region and reduced precipitation in the south, on multidecadal time scales. The pattern is reversed during the cold phase AMO. Whether the AMO acts as a forcing of the multidecadal winter climate of East China is explored by investigating the atmospheric response to warm AMO SST anomalies in a large ensemble of atmospheric general circulation model （AGCM） experiments. The results from three AGCMs are consistent and suggest that the AMO warmth favors warmer winters in East China. This influence is realized through inducing negative surface air pressure anomalies in the hemispheric-wide domain extending from the midlatitude North Atlantic to midlatitude Eurasia. These negative surface anomalies favor the weakening of the Mongolian Cold High, and thus induce a weaker East Asian Winter Monsoon.
基金supported jointly by the NOAA Arctic Research,CAS Project ZKCX2-SW-210the National Natural Science Foundation of China(Grant No.40275025)
文摘A new North Atlantic Oscillation (NAO) index, the NAOI, is defined as the differences of normalized sea level pressures regionally zonal-averaged over a broad range of longitudes 80°W-30°E. A comprehensive comparison of six NAO indices indicates that the new NAOI provides a more faithful representation of the spatial-temporal variability associated with the NAO on all timescales. A very high signal-to-noise ratio for the NAOI exists for all seasons, and the life cycle represented by the NAOI describes well the seasonal migration for action centers of the NAO. The NAOI captures a larger fraction of the variance of sea level pressure over the North Atlantic sector (20°-90°N, 80°W-30°E), on average 10% more than any other NAO index. There are quite different relationships between the NAOI and surface air temperature during winter and summer. A novel feature, however, is that the NAOI is significantly negative correlated with surface air temperature over the North Atlantic Ocean between 10°-25°N and 70°-30°W, whether in winter or summer. From 1873, the NAOI exhibits strong interannual and decadal variability. Its interannual variability of the twelve calendar months is obviously phase-locked with the seasonal cycle. Moreover, the annual NAOI exhibits a clearer decadal variability in amplitude than the winter NAOI. An upward trend is found in the annual NAOI between the 1870s and 1910s, while the other winter NAO indices fail to show this tendency. The annual NAOI exhibits a strongly positive epoch of 50 years between 1896 and 1950. After 1950, the variability of the annual NAOI is very similar to that of the winter NAO indices.
