In this paper,we first review the research advancements in blocking dynamics and highlight the merits and drawbacks of the previous theories of atmospheric blocking.Then,the dynamical mechanisms of atmospheric blockin...In this paper,we first review the research advancements in blocking dynamics and highlight the merits and drawbacks of the previous theories of atmospheric blocking.Then,the dynamical mechanisms of atmospheric blocking are presented based on a nonlinear multi-scale interaction(NMI)model.Previous studies suggested that the eddy deformation(e.g.,eddy straining,wave breaking,and eddy merging)might lead to the formation and maintenance of atmospheric blocking.However,the results were speculative and problematic because the previous studies,based on the time-mean eddy-mean flow interaction model,cannot identify the causal relationship between the evolution of atmospheric blocking and the eddy deformation.Based on the NMI model,we indicate that the onset,growth,maintenance,and decay of atmospheric blocking is mainly produced by the spatiotemporal evolution of pre-existing upstream synoptic-scale eddies,whereas the eddy deformation is a concomitant phenomenon of the blocking formation.The lifetime of blocking is mainly determined by the meridional background potential vorticity gradient(PVy)because a small PVyfavors weak energy dispersion and strong nonlinearity to sustain the blocking.But the zonal movement of atmospheric blocking is associated with the background westerly wind,PVy,and the blocking amplitude.Using this NMI model,a bridge from the climate change to sub-seasonal atmospheric blocking and weather extremes might be established via examining the effect of climate change on PVy.Thus,it is expected that using the NMI model to explore the dynamics of atmospheric blocking and its change is a new direction in the future.展开更多
To investigate the multiscale interaction characteristics of Landfall Typhoon Lekima(2019),this study analyzed the characteristics of the different scale vortex structure and interactions among different scales based ...To investigate the multiscale interaction characteristics of Landfall Typhoon Lekima(2019),this study analyzed the characteristics of the different scale vortex structure and interactions among different scales based on vorticity equation diagnosis.The analysis is based on the simulation results of the WRF model which has been thoroughly verified.The main results are as follows:the original vorticity dominated by the meso-αscale vorticity increases with height and then decreases,with maximum vorticity distributed at 900 hPa.The meso-βscale vorticity varies significantly with altitude,while the meso-γscale vorticityfield exhibits obvious positive vorticity below 850 hPa.The meso-αscale vorticity tendency primarily maintains negative,contributing significantly to the overall reduction in the original vorticityfield over time.The increase in mid-to-upper-level(above 550 hPa)original vorticity is mainly related to the variations in the meso-βand meso-γscale vorticityfields.The original vorticity dominated by the meso-αscale vorticity increases with height and then decreases,and the whole layer vorticity decreases over time.The meso-βscale vorticity varies significantly with altitude and time,while the meso-γscale vorticityfield consistently exhibits significant positive vorticity below 850 hPa.The vorticity equation diagnosis revealed that the primary source terms of the vorticity tendencies are the twisting and stretching terms,and the main sink terms being horizontal and vertical vorticity transport terms below 900 hPa.The source terms and sink terms exchange above 850 hPa.Scale separation results show that the primary contributions of all impact factors originate from the meso-αand meso-γscalefields(accounting for over 80%of the total),with the contribution of the meso-αscale being less than that of the meso-γscale and a notable contribution over 35.5%of the interactions between different scales.展开更多
Accurately diagnosing and assessing complicated spatial linkages at various scales has become a crucial strategy for enhancing the efficacy of urban government policies and initiatives in the modern era.There is still...Accurately diagnosing and assessing complicated spatial linkages at various scales has become a crucial strategy for enhancing the efficacy of urban government policies and initiatives in the modern era.There is still room for improvement in identifying spatial scale disparities and coupling linkages in cities,although the standard research paradigm on urban sustainability has produced numerous positive outcomes.To advance urban sustainability research from the perspective of spatial coupling,this study used cluster and cross-tabulation analyses for considering urban sustainable development patterns from the requirements of both development scale and spatial accuracy.Subsequently,the spatial unit coupling relationship between district and street scales was explored.Our findings indicated significant scale dependence in the spatial divergence between the built environment sustainability levels of streets and the economic,social,and environmental sustainability levels of districts.The implication is that significant differences exist in the built environment levels of various sustainable development type districts.The scale effect of the spatial coupling relationship influences urban planning and the transition of sustainable development.Maintaining reasonable population density and maximizing the structure and quality of social public resources supply are priorities for streets with the highest habitat sustainability that are located in low-growth type districts.Priority should be given to population deconcentration for high habitat sustainable streets located in synergistic development type districts to increase the level of public service protection.Supporting facilities should be added to medium sustainable streets in low-growth areas to increase the mix of land use,which should encourage additional production activity concentration,thereby fostering overall economic strength.Further,increasing the accessibility of local public service facilities for low and medium sustainable streets located in ecologically biased areas should be prioritized,but a green and low-carbon orientation should be maintained during building.展开更多
The flow patterns of Euro-Atlantic blocking events in winter are investigated by dividing the sector into three sub- regions： 60°-30°W （Greenland region）; 20°W-30°E [eastern Atlantic-Europe （EA...The flow patterns of Euro-Atlantic blocking events in winter are investigated by dividing the sector into three sub- regions： 60°-30°W （Greenland region）; 20°W-30°E [eastern Atlantic-Europe （EAE） region]; and 50°-90°E （Ural region）. It is shown that blocking events in winter are extremely frequent in the three sub-regions. Composite 500-mb geopotential height fields for intense and long-lived blocking events demonstrate that the blocking fields over Greenland and Ural regions exhibit southwest-northeast （SW-NE） and southeast-northwest （SE-NW） oriented dipole-type patterns, respectively, while the composite field over the EAE region exhibits an Ω-type pattern. The type of composite blocking pattern seems to be related to the position of the blocking region relative to the positive center of the climatological stationary wave （CSW） anomaly existing near 10°W. The physical cause of why there are different composite blocking types in the three sub-regions is identified using a nonlinear multiscale interaction model. It is found that when the blocking event is in almost the same position as the positive CSW anomaly, the planetary-scale field can exhibit an Ω-type pattern due to the enhanced positive CSW anomaly. Neverthe- less, a SW-NE （SE-NW） oriented dipole-type block can occur due to the reduced positive CSW anomaly as it is farther in the west （east） of the positive CSW anomaly. The total fields of blocking in the three regions may exhibit a meandering flow comprised of several isolated anticyclonic and cyclonic vortices, which resembles the Berggren-Bolin-Rossby meandering jet type.展开更多
Under global warming,extreme weather events and air pollution are becoming increasingly critical challenges.Both pose serious risks to human health,economies,and societal stability,and their complex interactions can f...Under global warming,extreme weather events and air pollution are becoming increasingly critical challenges.Both pose serious risks to human health,economies,and societal stability,and their complex interactions can further amplify these impacts.Numerical models are essential tools for studying these phenomena;however,traditional low-resolution Earth system models often fail to accurately capture the dynamics of extreme weather and air pollution.This limitation hinders our mechanistic understanding,reduces the reliability of future projections,and constrains the development of effective adaptation strategies.Dynamical downscaling—an approach that uses highresolution regional models nested within global models—offers a partial solution.However,this method inherits biases from the parent global models and often fails to adequately represent multi-scale and cross-sphere interactions involving the atmosphere,land,and oceans.These shortcomings underscore the growing need for developing and applying high-resolution Earth system models that can more comprehensively and accurately depict land-sea-atmosphere interactions,including heat and material exchanges and their spatial heterogeneity.This article explores the current challenges,recent advances,and future opportunities in understanding the interplay between extreme weather events and air pollution,with a focus on the critical role of high-resolution modeling.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42150204 and 42288101)the Chinese Academy of Sciences Strategic Priority Research Program(Grant No.XDA19070403)。
文摘In this paper,we first review the research advancements in blocking dynamics and highlight the merits and drawbacks of the previous theories of atmospheric blocking.Then,the dynamical mechanisms of atmospheric blocking are presented based on a nonlinear multi-scale interaction(NMI)model.Previous studies suggested that the eddy deformation(e.g.,eddy straining,wave breaking,and eddy merging)might lead to the formation and maintenance of atmospheric blocking.However,the results were speculative and problematic because the previous studies,based on the time-mean eddy-mean flow interaction model,cannot identify the causal relationship between the evolution of atmospheric blocking and the eddy deformation.Based on the NMI model,we indicate that the onset,growth,maintenance,and decay of atmospheric blocking is mainly produced by the spatiotemporal evolution of pre-existing upstream synoptic-scale eddies,whereas the eddy deformation is a concomitant phenomenon of the blocking formation.The lifetime of blocking is mainly determined by the meridional background potential vorticity gradient(PVy)because a small PVyfavors weak energy dispersion and strong nonlinearity to sustain the blocking.But the zonal movement of atmospheric blocking is associated with the background westerly wind,PVy,and the blocking amplitude.Using this NMI model,a bridge from the climate change to sub-seasonal atmospheric blocking and weather extremes might be established via examining the effect of climate change on PVy.Thus,it is expected that using the NMI model to explore the dynamics of atmospheric blocking and its change is a new direction in the future.
基金funded by the National Natural Science Foundation of China(grant U2142206).W。
文摘To investigate the multiscale interaction characteristics of Landfall Typhoon Lekima(2019),this study analyzed the characteristics of the different scale vortex structure and interactions among different scales based on vorticity equation diagnosis.The analysis is based on the simulation results of the WRF model which has been thoroughly verified.The main results are as follows:the original vorticity dominated by the meso-αscale vorticity increases with height and then decreases,with maximum vorticity distributed at 900 hPa.The meso-βscale vorticity varies significantly with altitude,while the meso-γscale vorticityfield exhibits obvious positive vorticity below 850 hPa.The meso-αscale vorticity tendency primarily maintains negative,contributing significantly to the overall reduction in the original vorticityfield over time.The increase in mid-to-upper-level(above 550 hPa)original vorticity is mainly related to the variations in the meso-βand meso-γscale vorticityfields.The original vorticity dominated by the meso-αscale vorticity increases with height and then decreases,and the whole layer vorticity decreases over time.The meso-βscale vorticity varies significantly with altitude and time,while the meso-γscale vorticityfield consistently exhibits significant positive vorticity below 850 hPa.The vorticity equation diagnosis revealed that the primary source terms of the vorticity tendencies are the twisting and stretching terms,and the main sink terms being horizontal and vertical vorticity transport terms below 900 hPa.The source terms and sink terms exchange above 850 hPa.Scale separation results show that the primary contributions of all impact factors originate from the meso-αand meso-γscalefields(accounting for over 80%of the total),with the contribution of the meso-αscale being less than that of the meso-γscale and a notable contribution over 35.5%of the interactions between different scales.
基金National Key R&D Program of China,No.2022YFC3800803National Natural Science Foundation of China,No.42271218。
文摘Accurately diagnosing and assessing complicated spatial linkages at various scales has become a crucial strategy for enhancing the efficacy of urban government policies and initiatives in the modern era.There is still room for improvement in identifying spatial scale disparities and coupling linkages in cities,although the standard research paradigm on urban sustainability has produced numerous positive outcomes.To advance urban sustainability research from the perspective of spatial coupling,this study used cluster and cross-tabulation analyses for considering urban sustainable development patterns from the requirements of both development scale and spatial accuracy.Subsequently,the spatial unit coupling relationship between district and street scales was explored.Our findings indicated significant scale dependence in the spatial divergence between the built environment sustainability levels of streets and the economic,social,and environmental sustainability levels of districts.The implication is that significant differences exist in the built environment levels of various sustainable development type districts.The scale effect of the spatial coupling relationship influences urban planning and the transition of sustainable development.Maintaining reasonable population density and maximizing the structure and quality of social public resources supply are priorities for streets with the highest habitat sustainability that are located in low-growth type districts.Priority should be given to population deconcentration for high habitat sustainable streets located in synergistic development type districts to increase the level of public service protection.Supporting facilities should be added to medium sustainable streets in low-growth areas to increase the mix of land use,which should encourage additional production activity concentration,thereby fostering overall economic strength.Further,increasing the accessibility of local public service facilities for low and medium sustainable streets located in ecologically biased areas should be prioritized,but a green and low-carbon orientation should be maintained during building.
基金the support from the National Science Foundation of China(Grant No.41375067) "One-Hundred Talents Plan"of the Chinese Academy of Sciences(Grant No.Y163011)
文摘The flow patterns of Euro-Atlantic blocking events in winter are investigated by dividing the sector into three sub- regions： 60°-30°W （Greenland region）; 20°W-30°E [eastern Atlantic-Europe （EAE） region]; and 50°-90°E （Ural region）. It is shown that blocking events in winter are extremely frequent in the three sub-regions. Composite 500-mb geopotential height fields for intense and long-lived blocking events demonstrate that the blocking fields over Greenland and Ural regions exhibit southwest-northeast （SW-NE） and southeast-northwest （SE-NW） oriented dipole-type patterns, respectively, while the composite field over the EAE region exhibits an Ω-type pattern. The type of composite blocking pattern seems to be related to the position of the blocking region relative to the positive center of the climatological stationary wave （CSW） anomaly existing near 10°W. The physical cause of why there are different composite blocking types in the three sub-regions is identified using a nonlinear multiscale interaction model. It is found that when the blocking event is in almost the same position as the positive CSW anomaly, the planetary-scale field can exhibit an Ω-type pattern due to the enhanced positive CSW anomaly. Neverthe- less, a SW-NE （SE-NW） oriented dipole-type block can occur due to the reduced positive CSW anomaly as it is farther in the west （east） of the positive CSW anomaly. The total fields of blocking in the three regions may exhibit a meandering flow comprised of several isolated anticyclonic and cyclonic vortices, which resembles the Berggren-Bolin-Rossby meandering jet type.
基金supported by the National Natural Science Foundation of China(Nos.42122039 and 42375189)the Science and Technology Innovation Project of Laoshan Laboratory(China)(Nos.LSKJ202300401 and LSKJ202202201)+1 种基金Hainan Provincial Joint Project of Sanya Yazhou Bay Science and Technology City(China)(No.2021JJLH0050)Deliang Chen was supported by Tsinghua University(China)(No.100008001).
文摘Under global warming,extreme weather events and air pollution are becoming increasingly critical challenges.Both pose serious risks to human health,economies,and societal stability,and their complex interactions can further amplify these impacts.Numerical models are essential tools for studying these phenomena;however,traditional low-resolution Earth system models often fail to accurately capture the dynamics of extreme weather and air pollution.This limitation hinders our mechanistic understanding,reduces the reliability of future projections,and constrains the development of effective adaptation strategies.Dynamical downscaling—an approach that uses highresolution regional models nested within global models—offers a partial solution.However,this method inherits biases from the parent global models and often fails to adequately represent multi-scale and cross-sphere interactions involving the atmosphere,land,and oceans.These shortcomings underscore the growing need for developing and applying high-resolution Earth system models that can more comprehensively and accurately depict land-sea-atmosphere interactions,including heat and material exchanges and their spatial heterogeneity.This article explores the current challenges,recent advances,and future opportunities in understanding the interplay between extreme weather events and air pollution,with a focus on the critical role of high-resolution modeling.
