The Brazilian coast is characterized by different tidal regimes and distinct meteorological influences. The northern part has larger tidal amplitudes and is permanently affected by trade winds and tropical disturbance...The Brazilian coast is characterized by different tidal regimes and distinct meteorological influences. The northern part has larger tidal amplitudes and is permanently affected by trade winds and tropical disturbances; the southern portion has smaller tidal amplitudes and is frequently influenced by extratropical cyclone activity. Besides these aspects, many features regarding current structure and behavior are also present, such as the equatorial system of currents, the subtropical gyre and the corresponding western boundary currents, and the Brazil-Malvinas confluence region. Within this context, efforts were made to develop the BRAZCOAST system, capable of describing the processes that determine the oceanic circulation from large to coastal scales. A customized version of the Princeton Ocean Model(POM) was implemented in a basin-scale domain covering the whole of the tropical and southern Atlantic Ocean, with 0.5° spatial resolution, as well as three nested grids with(1/12)° resolution covering the different parts of the Brazilian shelf, in a one-way procedure. POM was modified to include tidal potential generator terms and a partially-clamped boundary condition for tidal elevations. The coarse grid captured large-scale features, while the nested grids detailed local circulations affected by bathymetry and coastal restrictions. An interesting aspect at the coarse grid level was the relevance of the Weddell Sea to the location of the tidal amphidromic systems.展开更多
In this study,a two-dimensional flow-pollutant coupled model was developed based on a quadtree grid.This model was established to allow the accurate simulation of wind-driven flow in a large-scale shallow lake with ir...In this study,a two-dimensional flow-pollutant coupled model was developed based on a quadtree grid.This model was established to allow the accurate simulation of wind-driven flow in a large-scale shallow lake with irregular natural boundaries when focusing on important smallscale localized flow features.The quadtree grid was created by domain decomposition.The governing equations were solved using the finite volume method,and the normal fluxes of mass,momentum,and pollutants across the interface between cells were computed by means of a Godunov-type Osher scheme.The model was employed to simulate wind-driven flow in a circular basin with non-uniform depth.The computed values were in agreement with analytical data.The results indicate that the quadtree grid has fine local resolution and high efficiency,and is convenient for local refinement.It is clear that the quadtree grid model is effective when applied to complex flow domains.Finally,the model was used to calculate the flow field and concentration field of Taihu Lake,demonstrating its ability to predict the flow and concentration fields in an actual water area with complex geometry.展开更多
A new semi implicit numerical model developed to investigate the wind driven circulation (with inflow and outflow) in the Bohai, Huanghai and East China Sea in winter showed that the open boundary conditions and wind ...A new semi implicit numerical model developed to investigate the wind driven circulation (with inflow and outflow) in the Bohai, Huanghai and East China Sea in winter showed that the open boundary conditions and wind forcing are important in controlling general circulation in wintertime; that open boundary conditions (such as Kuroshio, Changjiang River runoff) are primary factors controlling the East China Sea circulation; and that wind driven current is more important in the upper layer in shallow sea area (such as Bohai Sea, North Huanghai Sea, as well as coastal area) in winter. Two numerical experiments are discussed to demonstrate the circulation responding to the changes of the open boundary conditions.展开更多
Climate models are essential for understanding past,present,and future changes in atmospheric circulation,with circulation modes providing key sources of seasonal predictability and prediction uncertainties for both g...Climate models are essential for understanding past,present,and future changes in atmospheric circulation,with circulation modes providing key sources of seasonal predictability and prediction uncertainties for both global and regional climates.This study assesses the performance of models participating in phase 6 of the Coupled Model Intercomparison Project in simulating interannual variability modes of Northern Hemisphere 500-hPa geopotential height during winter and summer,distinguishing predictable(potentially predictable on seasonal or longer timescales)and unpredictable(intraseasonal and essentially unpredictable at long range)components,using reanalysis data and a variance decomposition method.Although most models effectively capture unpredictable modes in reanalysis,their ability to reproduce dominant predictable modes-specifically the Pacific-North American pattern,Arctic Oscillation,and Western Pacific Oscillation in winter,and the East Atlantic and North Atlantic Oscillations in summer-varies notably.An optimal ensemble is identified to distinguish(a)predictable-external modes,dominated by external forcing,and(b)predictable-internal modes,associated with slow internal variability,during the historical period(1950-2014)and the SSP5-8.5 scenario(2036-2100).Under increased radiative forcing,the leading winter/summer predictable-external mode exhibits a more uniform spatial distribution,remarkably larger trend and annual variance,and enhanced height-sea surface temperature(SST)covariance under SSP5-8.5 compared to historical conditions.The dominant winter/summer predictable-internal modes also exhibit increased variance and height-SST covariance under SSP5-8.5,along with localized changes in spatial configuration.Minimal changes are observed in spatial distribution or variance for dominant winter/summer unpredictable modes under SSP5-8.5.This study,from a predictive perspective,deepens our understanding of model uncertainties and projected changes in circulations.展开更多
The development of a simplified 2-D numerical model was described forwind-driven circulation in reservoir u-sing standard k-ε turbulence model to specify eddy viscositydistribution. The governing equations are transf...The development of a simplified 2-D numerical model was described forwind-driven circulation in reservoir u-sing standard k-ε turbulence model to specify eddy viscositydistribution. The governing equations are transformed and solved on variable vertical grids, whichallows refinement at the surface and bottom boundaries. The results of the model simulation for floware compared with analytical solutions for laminar and turbulent flows, experimental data in awind-flume and wind wave tank. The sensitivity analysis results show that use of large number ofdepth layers increases the accuracy for the bottom counter-current flow. Prediction of surface driftwas not very sensitive to surface grid refinement. The model was also applied to Baisha reservoirfor an assumed wind condition and showed to be able to simulate the general features of surfacedrift and return flow under variable flow depth. The model can serve as alternative means ofstudying wind-driven flow beside experiments. It also reduced the problem complexity associated with3-D circulation models while faithfully reproducing the drift and near bottom return currents.展开更多
A lattice Boltzmann (LB) model with overall second-order accuracy is applied to the 1.5-layer shallow water equation for a wind-driven double-gyre ocean circulation. By introducing the second-order integral approximat...A lattice Boltzmann (LB) model with overall second-order accuracy is applied to the 1.5-layer shallow water equation for a wind-driven double-gyre ocean circulation. By introducing the second-order integral approximation for the collision operator, the model becomes fully explicit. In this case, any iterative technique is not needed. The Coriolis force and other external forces are included in the model with second-order accuracy, which is consistent with the discretized accuracy of the LB equation. The numerical results show correct physics of the ocean circulation driven by the double-gyre wind stress with different Reynolds numbers and different spatial resolutions. An intrinsic low-frequency variability of the shallow water model is also found. The wind-driven ocean circulation exhibits subannual and interannual oscillations, which are comparable to those of models in which the conventional numerical methods are used.展开更多
The movement of global ocean circulation in the Earth’s main magnetic field generates a measurable induced magnetic field(about 2 nT at geomagnetic satellite altitudes).However,this ocean circulation-induced magnetic...The movement of global ocean circulation in the Earth’s main magnetic field generates a measurable induced magnetic field(about 2 nT at geomagnetic satellite altitudes).However,this ocean circulation-induced magnetic field has not been previously estimated or incorporated into geomagnetic field models,potentially causing leakage into the core field model.Here,we present a method to account for the circulation-induced magnetic field during geomagnetic field modeling.First,a forward model of the circulation-induced magnetic field is constructed by numerically solving electromagnetic induction equations based on a realistic ocean circulation model.Then,this forward model is subtracted from the observed data.Finally,the core and lithospheric fields,magnetospheric and Earth’s mantle-induced fields,and the ocean tide-induced magnetic field are co-estimated.Applying our method to over 20 years of MSS-1,Swarm,CryoSat-2,and CHAMP satellite magnetic data,we derive a new multisource geomagnetic field model(MGFM).We find that incorporating a forward model of the circulation-induced magnetic field marginally improves the fit to the data.Furthermore,we demonstrate that neglecting the circulation-induced magnetic field in geomagnetic field modeling results in leakage into the core field model.The highlights of the MGFM model include:(i)a good agreement with the widely used CHAOS model series;(ii)the incorporation of magnetic fields induced by both ocean tides and circulation;and(iii)the suppression of leakage of the circulation-induced magnetic field into the core field model.展开更多
Objective:To evaluate the therapeutic effect of Tianma Gouteng Decoction combined with Betahistine Mesylate in patients with posterior circulation ischemic vertigo(PCI).Methods:Eighty-two patients with PCI who visited...Objective:To evaluate the therapeutic effect of Tianma Gouteng Decoction combined with Betahistine Mesylate in patients with posterior circulation ischemic vertigo(PCI).Methods:Eighty-two patients with PCI who visited the hospital from February 2024 to February 2025 were selected as samples and randomly divided into two groups.Group A received Tianma Gouteng Decoction combined with Betahistine Mesylate,while Group B received only Betahistine Mesylate.The efficacy,syndrome scores,hemodynamics,and quality of life indicators were compared between the two groups.Results:The efficacy of PCI treatment in Group A was higher than that in Group B(P<0.05).The syndrome scores in Group A were lower than those in Group B(P<0.05).The peak systolic velocity(PSV)of the basilar artery and left and right vertebral arteries in Group A were higher than those in Group B(P<0.05).The quality of life(SF-36)score in Group A was higher than that in Group B(P<0.05).Conclusion:Tianma Gouteng Decoction combined with Betahistine Mesylate is effective and feasible in the treatment of PCI,with improved hemodynamic indicators and reduced disease scores.展开更多
Due to complex geological structures and a narrow safe mud density window,offshore fractured formations frequently encounter severe lost circulation(LC)during drilling,significantly hindering oil and gas exploration a...Due to complex geological structures and a narrow safe mud density window,offshore fractured formations frequently encounter severe lost circulation(LC)during drilling,significantly hindering oil and gas exploration and development.Predicting LC risks enables the targeted implementation of mitigation strategies,thereby reducing the frequency of such incidents.To address the limitations of existing 3D geomechanical modeling in predicting LC,such as arbitrary factor selection,subjective weight assignment,and the inability to achieve pre-drilling prediction along the entire well section,an improved prediction method is proposed.This method integrates multi-source data and incorporates three LC-related sensitivity factors:fracture characteristics,rock brittleness,and in-situ stress conditions.A quantitative risk assessment model for LC is developed by combining the subjective analytic hierarchy process with the objective entropy weight method(EWM)to assign weights.Subsequently,3D geomechanical modeling is applied to identify regional risk zones,enabling digital visualization for pre-drilling risk prediction.The developed 3D LC risk prediction model was validated using actual LC incidents from drilled wells.Results were generally consistent with field-identified LC zones,with an average relative error of 19.08%,confirming its reliability.This method provides practical guidance for mitigating potential LC risks and optimizing drilling program designs in fractured formations.展开更多
A coupled lattice Boltzmann （LB） model with second-order accuracy is applied to the reduced-gravity, shallow water, 2.5-layer model for wind-driven double-gyre ocean circulation. By introducing the secondorder integ...A coupled lattice Boltzmann （LB） model with second-order accuracy is applied to the reduced-gravity, shallow water, 2.5-layer model for wind-driven double-gyre ocean circulation. By introducing the secondorder integral approximation for the collision operator, the model becomes fully explicit. The Coriolis force and other external forces are included in the model with second-order accuracy, which is consistent with the discretization accuracy of the LB equation. The feature of the multiple equilibria solutions is found in the numerical experiments under different Reynolds numbers based on this LB scheme. With the Reynolds number increasing from 3000 to 4000, the solution of this model is destabilized from the anti-symmetric double-gyre solution to the subtropic gyre solution and then to the subpolar gyre solution. The transitions between these equilibria states are also found in some parameter ranges. The time-dependent variability of the circulation based on this LB simulation is also discussed for varying viscosity regimes. The flow of this model exhibits oscillations with different timescales varying from subannual to interannual. The corresponding statistical oscillation modes are obtained by spectral analysis. By analyzing the spatiotemporal structures of these modes, it is found that the subannual oscillation with a 9-month period originates from the barotropic Rossby basin mode, and the interarmual oscillations with periods ranging from 1.5 years to 4.6 years originate from the recirculation gyre modes, which include the barotropic and the baroclinic recirculation gyre modes.展开更多
In order to fulfill the no-slip condition at the western and eastern boundaries of the ocean basin, introduced ＂effective wind stress＂, which has much larger spatial variations towards the boundaries than in the oce...In order to fulfill the no-slip condition at the western and eastern boundaries of the ocean basin, introduced ＂effective wind stress＂, which has much larger spatial variations towards the boundaries than in the ocean interior. The effective wind stress can thus be decomposed into spatially slow-varying and fast varying components. Careful scale analysis on the classical Munk winddriven ocean circulation theory, which consists of the interior Sverdrup flow and the western boundary current but of no eastern boundary current, shows that the wind stress curl appearing in the Sverdrup equation must have negligible spatial variations. In the present model the spatially slow-varying component of the wind stress appears in the Sverdrup equation, and the spatially fastvarying component becomes the forcing term of the boundary equations. As a result, in addition to the classical Munk solution the present model has an extra term at the western boundary which （Northern Hemisphere） increases the northward transport as well as the southward return transport, and has a term at the eastern boundary corresponding to the eastern boundary current.展开更多
The adjoint approach is a variational method which is often applied to data assimilation widely in meteorology and oceanography. It is used for analyses on observing optimization for the wind-driven Sverdrup circulati...The adjoint approach is a variational method which is often applied to data assimilation widely in meteorology and oceanography. It is used for analyses on observing optimization for the wind-driven Sverdrup circulation. The adjoint system developed by Thacker and Long (1992), which is based on the GFDL Byran-Cox model, includes three components, i. e. the forward model, the adjoint model and the optimal algorithm. The GFDL Byran-Cox model was integrated for a long time driven by a batch of ideal wind stresses whose meridional component is set to null and zonal component is a sine function of latitudes in a rectangle box with six vertical levels and 2 by 2 degree horizontal resolution. The results are regarded as a “real” representative of the wind-driven Sverdrup circulation, from which the four dimensional fields are allowed to be sampled in several ways, such as sampling at the different levels or along the different vertical sections. To set the different samples, the fields of temperature, salinity and velocities function as the observational limit in the adjoint system respectively where the same initial condition is chosen for 4D VAR data assimilation. By examining the distance functions which measure the misfit between the circulation field from the control experiment of the adjoint system with a complete observation and those from data assimilation of adjoint approach in these sensitivity experiments respectively, observing optimizations for the wind-driven Sverdrup circulation will be suggested under a fixed observational cost.展开更多
During drilling operations in deep fractured tight gas reservoirs,lost circulation of working fluid frequently occurs due to the formationʼs low pressure-bearing capacity.Adding lost circulation materials(LCMs)to dril...During drilling operations in deep fractured tight gas reservoirs,lost circulation of working fluid frequently occurs due to the formationʼs low pressure-bearing capacity.Adding lost circulation materials(LCMs)to drilling fluids is the most common method for controlling lost circulation.Among these,granular LCMs are widely used,but the application frequency of flaky LCMs has been increasing annually due to their unique morphology.However,the migration and plugging behavior of flaky LCMs within fractures,and the mechanisms enhancing the pressure-bearing capacity of the plugging zone are not well understood.Therefore,this study conducted visual plugging experiments and dynamic fracture plugging experiments to evaluate the plugging mode and pressure-bearing capacity of the plugging slurry with various particle sizes and concentrations of flaky LCMs.The experimental results demonstrate that the fracture plugging process can be divided into four stages:uniform flow stage of the plugging slurry,formation and development stage of the bridging area,formation and development stage of the plugging area,and pressure-bearing stage of the plugging zone.The inclusion of flaky LCMs notably reduces the duration of stages 1 and 2,while simultaneously increasing the proportion of the plugging zone and enhancing its surface porosity.Flaky LCMs reduce the effective fracture width through“interception”and“co-bridging”modes,thus improving plugging zone formation efficiency.Appropriate particle size and concentration of flaky LCMs increase the area and length of the plugging zone.This reduces the fracture width increment caused by injection pressure and enhances frictional force between the plugging zone and fracture surface,thereby improving the pressure-bearing capacity of the plugging zone.However,excessively high concentrations of flaky LCMs result in decreased structural stability of the plugging zone,and excessively large particle sizes increase the risk of plugging outside fracture inlet.The recommended concentration of flaky LCMs in the plugging slurry is 2%–3%,with a particle size 1.2 to 1.5 times that of the bridging granular LCMs and not exceeding twice the fracture width.This study provides a theoretical foundation for selecting LCMs and designing plugging formulations for field applications.展开更多
Lost circulation of drilling fluid is an international engineering problem during drilling.Aiming at the problems of the first-time lost circulation control success rate and poor adaptability of traditional lost circu...Lost circulation of drilling fluid is an international engineering problem during drilling.Aiming at the problems of the first-time lost circulation control success rate and poor adaptability of traditional lost circulation materials,a new self-healing lost circulation material based on dynamic disulfide bonds was prepared and named CKSH.In this paper,the particle size of self-healing lost circulation material was from 0.1 to 5 mm.The structure was analyzed by modern characterization means,and the drilling fluid compatibility,self-healing performance were evaluated.The self-healing and bridging-filling-sealing mechanism of CKSH were revealed.The results showed that the healing rate of CKSH could reach100%after 12 h over 70℃.It showed good compatibility with drilling fluid,with no effect on rheology or filtration loss.It could be stably suspended in drilling fluid,and the temperature resistance reached140℃.Healing by self-healing lost circulation materials of different particle size,the pressure bearing capacity of plugging zone were over 12 MPa for fracture opening of 1–5 mm.It could play a synergistic role with traditional lost circulation materials by chemical bonding,and the repeated loss caused by physical plugging was avoided.The research results of this paper can improve the bridging plugging bearing pressure strength and the first-time lost circulation control success rate,which is of great significance for improving drilling efficiency and reducing non-productive time.展开更多
Based on questionnaire surveys and field interviews conducted with various types of agricultural production organizations across five districts and four counties in Daqing City,this study combines relevant theoretical...Based on questionnaire surveys and field interviews conducted with various types of agricultural production organizations across five districts and four counties in Daqing City,this study combines relevant theoretical frameworks to systematically examine the evolution,performance,and influencing factors of governance mechanisms within these organizations.Using both quantitative and inductive analytical methods,the paper proposes innovative designs and supporting measures for improving governance mechanisms.The findings reveal that,amid large-scale farmland circulation,the governance mechanisms of agricultural production organizations in Daqing City are evolving from traditional to modern structures.However,challenges remain in areas such as decision-making efficiency,benefit distribution,and supervision mechanisms.In response,this study proposes innovative governance designs focusing on decision-making processes,profit-sharing mechanisms,and risk prevention.Corresponding policy recommendations are also provided to support the sustainable development of agricultural modernization in China.展开更多
Background:Aortic atherosclerosis increases the risk of embolic events under extracorporeal circulation(ECC).To evaluate the hemodynamic impact of ECC on atheromatous plaques,an atherosclerosis animal model,which is a...Background:Aortic atherosclerosis increases the risk of embolic events under extracorporeal circulation(ECC).To evaluate the hemodynamic impact of ECC on atheromatous plaques,an atherosclerosis animal model,which is also eligible for ECC,is required.Methods:Twenty-nine New Zealand White rabbits received a pro-atherosclerotic diet(group diet,n=10),a pro-atherosclerotic diet and additional intraaortic balloon insufflation injury(group BI,n=9),or served as controls(n=10).After 3 or 6 months,aortic explants were analyzed by(immuno-)histology and RT-PCR.Results:Blood serum analyses revealed increased cholesterol-levels in groups diet and BI compared to controls(3 months:p=0.03 each,6 months:p<0.0001 each).Aortic inflammatory infiltration was significantly enhanced in groups diet(CD3 at 3 months:p<0.0001,6 months:p=0.02;CD68 at 3 months:p=0.01)and BI(CD3 at 3 months:p<0.0001,6 months:p=0.03;CD68 at 3 months:p=0.04,6 months:p=0.02).Increased intima hyperplasia occurred in both groups(p<0.0001 each).Macroscopic analyses after 3 and 6 months showed ubiquitous lumen-narrowing aortic plaques.Calcification of the intima and media was increased in groups diet(intima:p<0.0001 at 3 and 6 months;media at 3 months:p<0.0001,6 months:p=0.01)and BI(intima:p<0.0001 at 3 and 6 months;media at 3 months:p<0.0001,6 months:p=0.02).Extensive lipid accumulation was found in the intima in both treatment groups(p<0.0001 each).Conclusions:A rabbit model with high aortic calcific plaque burden—diet-induced with no implicit need of an additional intimal injury by an intraaortic balloon insufflation due to comparable outcome—exhibiting multiple pathophysiological aspects of human atherosclerosis has been designed and thoroughly characterized.It is suitable for use in future studies on the interaction between atherosclerotic plaques and the arterial blood flow under ECC.展开更多
Dear Editor,Dengue virus(DENV)is a positive-sense single-stranded RNA virus belonging to the Flaviviridae family,which causes dengue—a disease affecting over 400 million people annually worldwide.DENV is transmitted ...Dear Editor,Dengue virus(DENV)is a positive-sense single-stranded RNA virus belonging to the Flaviviridae family,which causes dengue—a disease affecting over 400 million people annually worldwide.DENV is transmitted through the bite of mosquitoes from the Aedes genus,primarily Aedes aegypti,and has a wide distribution in tropical and subtropical areas(de Souza et al.,2022).展开更多
The Hadley Circulation(HC),a fundamental component of global atmospheric circulation,plays an important role in the global energy balance and transport of moisture.The interaction between ENSO and the HC significantly...The Hadley Circulation(HC),a fundamental component of global atmospheric circulation,plays an important role in the global energy balance and transport of moisture.The interaction between ENSO and the HC significantly impacts tropical climate and has broad implications for global climate variability through atmospheric teleconnections.The HC is usually represented by the mass stream function.As a result,it can rarely be observed through in-situ measurement.Reanalysis datasets and CMIP models are frequently used to investigate the properties of the HC.Previous studies systematically assess the capability of these CMIP models to represent the spatial distribution and intensity of the HC anomalies associated with ENSO events.However,most of these studies investigate the HC anomaly from a global perspective.In this work,we focus on evaluating the ability of CMIP6 models to capture the three-dimensional features of ENSO-related HC anomalies in comparison to that in six reanalysis datasets.Results show a consistent westward shift of the ENSO-related HC over the tropical Central-Eastern Pacific in almost all CMIP6 models,accompanied by a weakening of the asymmetric component of the ENSO-related HC over the equatorial Pacific.The former is mainly attributed to the westward extension of the Pacific cold tongue in CMIP models,while the latter is more related to the southward shift of the ENSO-related SST and precipitation anomalies in CMIP models.One should be aware of these biases when studying the ENSO-related atmospheric circulation changes.Our study has broad implications for ENSO simulations and the predictability of ENSO-related global climate variabilities.展开更多
In 2022, South China(SC) experienced record-breaking rainfall during its first rainy season, causing severe socioeconomic losses. This study examines the large-scale circulation anomalies responsible for this extreme ...In 2022, South China(SC) experienced record-breaking rainfall during its first rainy season, causing severe socioeconomic losses. This study examines the large-scale circulation anomalies responsible for this extreme event.Analysis reveals that the lower-tropospheric cyclonic anomaly over SC plays a crucial role. This cyclonic anomaly consists of extratropical northeasterly anomalies to the north of SC and tropical southwesterly anomalies to the south. Both components were particularly intense during the 2022 first rainy season, contributing to the heavy rainfall in SC. Moreover,the lower-tropospheric cyclonic anomaly is enhanced by its counterpart in the upper troposphere, which is associated with a wave train propagating from the North Atlantic to East Asia across the mid-high latitudes of the Eurasian continent.Further analysis indicates that the extratropical wave train correlates with sea surface temperature anomalies(SSTAs) in the North Atlantic. Additionally, the SSTAs over the North Indian Ocean also play a role in enhancing the tropical southwesterlies in the lower troposphere. This study highlights the combined influence of tropical and extratropical circulation anomalies, offering a comprehensive understanding of the record-breaking rainfall.展开更多
Using long-term Whole Atmosphere Community Climate Model version 5(WACCM5)simulations initialized with the climatology around the year 2000,we studied the anomalous distribution of planetary wave and gravity wave flux...Using long-term Whole Atmosphere Community Climate Model version 5(WACCM5)simulations initialized with the climatology around the year 2000,we studied the anomalous distribution of planetary wave and gravity wave fluxes during distinct phases of the boreal stratospheric polar vortex(BSPV)and Quasi-Biennial Oscillation(QBO).The contributions of these two types of waves to Brewer-Dobson circulation(BDC)anomalies were further analyzed.The results revealed that under four distinct phases,the northern hemisphere BDC is primarily governed by planetary waves,whereas gravity waves counteract approximately half of the planetary wave influence on the BDC in the upper stratosphere.The QBO regulates the position of the anomaly center within the BDC’s descending branch in the northern hemisphere.In particular,during the westerly phase of the QBO(WQBO),the center of this anomalous descending branch is located in the upper stratosphere,whereas during the easterly phase of the QBO(EQBO),it is located in the lower stratosphere.Southern hemisphere BDC anomalies are regulated more by QBO activity:during the WQBO,it shows synchronous changes with the BDC anomaly in the northern hemisphere,whereas during the EQBO,it exhibits an antiphase relationship with the BDC anomaly in the northern hemisphere.Mesospheric circulation anomalies are predominantly driven by gravity wave activity.The circulation weakens during a weak BSPV and strengthens during a strong BSPV.Additionally,the descending branch anomaly of the northern hemisphere circulation is more pronounced during the WQBO,whereas the ascending branch anomaly of the southern hemisphere circulation is more significant during the EQBO.展开更多
基金the Brazilian agencies FAPESP (Sao Paulo State Research Agency) and CNPq (National Council for Scientific and Technological Development) for funding throughout the development of this work
文摘The Brazilian coast is characterized by different tidal regimes and distinct meteorological influences. The northern part has larger tidal amplitudes and is permanently affected by trade winds and tropical disturbances; the southern portion has smaller tidal amplitudes and is frequently influenced by extratropical cyclone activity. Besides these aspects, many features regarding current structure and behavior are also present, such as the equatorial system of currents, the subtropical gyre and the corresponding western boundary currents, and the Brazil-Malvinas confluence region. Within this context, efforts were made to develop the BRAZCOAST system, capable of describing the processes that determine the oceanic circulation from large to coastal scales. A customized version of the Princeton Ocean Model(POM) was implemented in a basin-scale domain covering the whole of the tropical and southern Atlantic Ocean, with 0.5° spatial resolution, as well as three nested grids with(1/12)° resolution covering the different parts of the Brazilian shelf, in a one-way procedure. POM was modified to include tidal potential generator terms and a partially-clamped boundary condition for tidal elevations. The coarse grid captured large-scale features, while the nested grids detailed local circulations affected by bathymetry and coastal restrictions. An interesting aspect at the coarse grid level was the relevance of the Weddell Sea to the location of the tidal amphidromic systems.
基金supported by the National Natural Science Foundation of China(Grants No.51739002 and 51479064)the World-Class Universities(Disciplines)and Characteristic Development Guidance Funds for the Central Universitiesthe Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions(Grant No.PPZY2015A051)
文摘In this study,a two-dimensional flow-pollutant coupled model was developed based on a quadtree grid.This model was established to allow the accurate simulation of wind-driven flow in a large-scale shallow lake with irregular natural boundaries when focusing on important smallscale localized flow features.The quadtree grid was created by domain decomposition.The governing equations were solved using the finite volume method,and the normal fluxes of mass,momentum,and pollutants across the interface between cells were computed by means of a Godunov-type Osher scheme.The model was employed to simulate wind-driven flow in a circular basin with non-uniform depth.The computed values were in agreement with analytical data.The results indicate that the quadtree grid has fine local resolution and high efficiency,and is convenient for local refinement.It is clear that the quadtree grid model is effective when applied to complex flow domains.Finally,the model was used to calculate the flow field and concentration field of Taihu Lake,demonstrating its ability to predict the flow and concentration fields in an actual water area with complex geometry.
文摘A new semi implicit numerical model developed to investigate the wind driven circulation (with inflow and outflow) in the Bohai, Huanghai and East China Sea in winter showed that the open boundary conditions and wind forcing are important in controlling general circulation in wintertime; that open boundary conditions (such as Kuroshio, Changjiang River runoff) are primary factors controlling the East China Sea circulation; and that wind driven current is more important in the upper layer in shallow sea area (such as Bohai Sea, North Huanghai Sea, as well as coastal area) in winter. Two numerical experiments are discussed to demonstrate the circulation responding to the changes of the open boundary conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2342210 and 42275043)the National Institute of Natural Hazards,Ministry of Emergency Management of China(Grant Nos.J2223806,ZDJ2024-25 and ZDJ2025-34)。
文摘Climate models are essential for understanding past,present,and future changes in atmospheric circulation,with circulation modes providing key sources of seasonal predictability and prediction uncertainties for both global and regional climates.This study assesses the performance of models participating in phase 6 of the Coupled Model Intercomparison Project in simulating interannual variability modes of Northern Hemisphere 500-hPa geopotential height during winter and summer,distinguishing predictable(potentially predictable on seasonal or longer timescales)and unpredictable(intraseasonal and essentially unpredictable at long range)components,using reanalysis data and a variance decomposition method.Although most models effectively capture unpredictable modes in reanalysis,their ability to reproduce dominant predictable modes-specifically the Pacific-North American pattern,Arctic Oscillation,and Western Pacific Oscillation in winter,and the East Atlantic and North Atlantic Oscillations in summer-varies notably.An optimal ensemble is identified to distinguish(a)predictable-external modes,dominated by external forcing,and(b)predictable-internal modes,associated with slow internal variability,during the historical period(1950-2014)and the SSP5-8.5 scenario(2036-2100).Under increased radiative forcing,the leading winter/summer predictable-external mode exhibits a more uniform spatial distribution,remarkably larger trend and annual variance,and enhanced height-sea surface temperature(SST)covariance under SSP5-8.5 compared to historical conditions.The dominant winter/summer predictable-internal modes also exhibit increased variance and height-SST covariance under SSP5-8.5,along with localized changes in spatial configuration.Minimal changes are observed in spatial distribution or variance for dominant winter/summer unpredictable modes under SSP5-8.5.This study,from a predictive perspective,deepens our understanding of model uncertainties and projected changes in circulations.
文摘The development of a simplified 2-D numerical model was described forwind-driven circulation in reservoir u-sing standard k-ε turbulence model to specify eddy viscositydistribution. The governing equations are transformed and solved on variable vertical grids, whichallows refinement at the surface and bottom boundaries. The results of the model simulation for floware compared with analytical solutions for laminar and turbulent flows, experimental data in awind-flume and wind wave tank. The sensitivity analysis results show that use of large number ofdepth layers increases the accuracy for the bottom counter-current flow. Prediction of surface driftwas not very sensitive to surface grid refinement. The model was also applied to Baisha reservoirfor an assumed wind condition and showed to be able to simulate the general features of surfacedrift and return flow under variable flow depth. The model can serve as alternative means ofstudying wind-driven flow beside experiments. It also reduced the problem complexity associated with3-D circulation models while faithfully reproducing the drift and near bottom return currents.
基金The work was supported by the One Hundred Talents Project of the Chinese Academy of Sciences(Grant No.KCL14014)the Impacts of Ocean-Land-Atmosphere Interactions over the East Asian Mon soon Region on the Climate in China(EAMOLA)(Grant No:ZKCX2-SW-210)the National Outstanding Youth Science Foundation of China(Grant No.40325016).
文摘A lattice Boltzmann (LB) model with overall second-order accuracy is applied to the 1.5-layer shallow water equation for a wind-driven double-gyre ocean circulation. By introducing the second-order integral approximation for the collision operator, the model becomes fully explicit. In this case, any iterative technique is not needed. The Coriolis force and other external forces are included in the model with second-order accuracy, which is consistent with the discretized accuracy of the LB equation. The numerical results show correct physics of the ocean circulation driven by the double-gyre wind stress with different Reynolds numbers and different spatial resolutions. An intrinsic low-frequency variability of the shallow water model is also found. The wind-driven ocean circulation exhibits subannual and interannual oscillations, which are comparable to those of models in which the conventional numerical methods are used.
基金supported by the National Natural Science Foundation of China(42250101,42250102)the Macao Foundation.
文摘The movement of global ocean circulation in the Earth’s main magnetic field generates a measurable induced magnetic field(about 2 nT at geomagnetic satellite altitudes).However,this ocean circulation-induced magnetic field has not been previously estimated or incorporated into geomagnetic field models,potentially causing leakage into the core field model.Here,we present a method to account for the circulation-induced magnetic field during geomagnetic field modeling.First,a forward model of the circulation-induced magnetic field is constructed by numerically solving electromagnetic induction equations based on a realistic ocean circulation model.Then,this forward model is subtracted from the observed data.Finally,the core and lithospheric fields,magnetospheric and Earth’s mantle-induced fields,and the ocean tide-induced magnetic field are co-estimated.Applying our method to over 20 years of MSS-1,Swarm,CryoSat-2,and CHAMP satellite magnetic data,we derive a new multisource geomagnetic field model(MGFM).We find that incorporating a forward model of the circulation-induced magnetic field marginally improves the fit to the data.Furthermore,we demonstrate that neglecting the circulation-induced magnetic field in geomagnetic field modeling results in leakage into the core field model.The highlights of the MGFM model include:(i)a good agreement with the widely used CHAOS model series;(ii)the incorporation of magnetic fields induced by both ocean tides and circulation;and(iii)the suppression of leakage of the circulation-induced magnetic field into the core field model.
文摘Objective:To evaluate the therapeutic effect of Tianma Gouteng Decoction combined with Betahistine Mesylate in patients with posterior circulation ischemic vertigo(PCI).Methods:Eighty-two patients with PCI who visited the hospital from February 2024 to February 2025 were selected as samples and randomly divided into two groups.Group A received Tianma Gouteng Decoction combined with Betahistine Mesylate,while Group B received only Betahistine Mesylate.The efficacy,syndrome scores,hemodynamics,and quality of life indicators were compared between the two groups.Results:The efficacy of PCI treatment in Group A was higher than that in Group B(P<0.05).The syndrome scores in Group A were lower than those in Group B(P<0.05).The peak systolic velocity(PSV)of the basilar artery and left and right vertebral arteries in Group A were higher than those in Group B(P<0.05).The quality of life(SF-36)score in Group A was higher than that in Group B(P<0.05).Conclusion:Tianma Gouteng Decoction combined with Betahistine Mesylate is effective and feasible in the treatment of PCI,with improved hemodynamic indicators and reduced disease scores.
基金supported by the National Natural Science Foundation of China(No.52074312)the CNPC Science and Technology Innovation Foundation(No.2021DQ02-0505)+1 种基金the Open Fund Project of the National Key Laboratory for the Enrichment Mechanism and Efficient Development of Shale Oil and Gas(No.36650000-24-ZC0609-0006)the Major Science and Technology Project of Karamay City(No.20232023zdzx0003).
文摘Due to complex geological structures and a narrow safe mud density window,offshore fractured formations frequently encounter severe lost circulation(LC)during drilling,significantly hindering oil and gas exploration and development.Predicting LC risks enables the targeted implementation of mitigation strategies,thereby reducing the frequency of such incidents.To address the limitations of existing 3D geomechanical modeling in predicting LC,such as arbitrary factor selection,subjective weight assignment,and the inability to achieve pre-drilling prediction along the entire well section,an improved prediction method is proposed.This method integrates multi-source data and incorporates three LC-related sensitivity factors:fracture characteristics,rock brittleness,and in-situ stress conditions.A quantitative risk assessment model for LC is developed by combining the subjective analytic hierarchy process with the objective entropy weight method(EWM)to assign weights.Subsequently,3D geomechanical modeling is applied to identify regional risk zones,enabling digital visualization for pre-drilling risk prediction.The developed 3D LC risk prediction model was validated using actual LC incidents from drilled wells.Results were generally consistent with field-identified LC zones,with an average relative error of 19.08%,confirming its reliability.This method provides practical guidance for mitigating potential LC risks and optimizing drilling program designs in fractured formations.
基金The work is supported by the ＂100 Talent project＂ of Chinese Academy of Sciences （Grant No. KCL14014） the National 0utstanding Youth Science Foundation of China （Grant No. 40325016）.
文摘A coupled lattice Boltzmann （LB） model with second-order accuracy is applied to the reduced-gravity, shallow water, 2.5-layer model for wind-driven double-gyre ocean circulation. By introducing the secondorder integral approximation for the collision operator, the model becomes fully explicit. The Coriolis force and other external forces are included in the model with second-order accuracy, which is consistent with the discretization accuracy of the LB equation. The feature of the multiple equilibria solutions is found in the numerical experiments under different Reynolds numbers based on this LB scheme. With the Reynolds number increasing from 3000 to 4000, the solution of this model is destabilized from the anti-symmetric double-gyre solution to the subtropic gyre solution and then to the subpolar gyre solution. The transitions between these equilibria states are also found in some parameter ranges. The time-dependent variability of the circulation based on this LB simulation is also discussed for varying viscosity regimes. The flow of this model exhibits oscillations with different timescales varying from subannual to interannual. The corresponding statistical oscillation modes are obtained by spectral analysis. By analyzing the spatiotemporal structures of these modes, it is found that the subannual oscillation with a 9-month period originates from the barotropic Rossby basin mode, and the interarmual oscillations with periods ranging from 1.5 years to 4.6 years originate from the recirculation gyre modes, which include the barotropic and the baroclinic recirculation gyre modes.
基金The National Natural Science Foundation of China under contract No.40576020
文摘In order to fulfill the no-slip condition at the western and eastern boundaries of the ocean basin, introduced ＂effective wind stress＂, which has much larger spatial variations towards the boundaries than in the ocean interior. The effective wind stress can thus be decomposed into spatially slow-varying and fast varying components. Careful scale analysis on the classical Munk winddriven ocean circulation theory, which consists of the interior Sverdrup flow and the western boundary current but of no eastern boundary current, shows that the wind stress curl appearing in the Sverdrup equation must have negligible spatial variations. In the present model the spatially slow-varying component of the wind stress appears in the Sverdrup equation, and the spatially fastvarying component becomes the forcing term of the boundary equations. As a result, in addition to the classical Munk solution the present model has an extra term at the western boundary which （Northern Hemisphere） increases the northward transport as well as the southward return transport, and has a term at the eastern boundary corresponding to the eastern boundary current.
文摘The adjoint approach is a variational method which is often applied to data assimilation widely in meteorology and oceanography. It is used for analyses on observing optimization for the wind-driven Sverdrup circulation. The adjoint system developed by Thacker and Long (1992), which is based on the GFDL Byran-Cox model, includes three components, i. e. the forward model, the adjoint model and the optimal algorithm. The GFDL Byran-Cox model was integrated for a long time driven by a batch of ideal wind stresses whose meridional component is set to null and zonal component is a sine function of latitudes in a rectangle box with six vertical levels and 2 by 2 degree horizontal resolution. The results are regarded as a “real” representative of the wind-driven Sverdrup circulation, from which the four dimensional fields are allowed to be sampled in several ways, such as sampling at the different levels or along the different vertical sections. To set the different samples, the fields of temperature, salinity and velocities function as the observational limit in the adjoint system respectively where the same initial condition is chosen for 4D VAR data assimilation. By examining the distance functions which measure the misfit between the circulation field from the control experiment of the adjoint system with a complete observation and those from data assimilation of adjoint approach in these sensitivity experiments respectively, observing optimizations for the wind-driven Sverdrup circulation will be suggested under a fixed observational cost.
基金support from the National Natural Science Foundation of China(Grant No.52274009).
文摘During drilling operations in deep fractured tight gas reservoirs,lost circulation of working fluid frequently occurs due to the formationʼs low pressure-bearing capacity.Adding lost circulation materials(LCMs)to drilling fluids is the most common method for controlling lost circulation.Among these,granular LCMs are widely used,but the application frequency of flaky LCMs has been increasing annually due to their unique morphology.However,the migration and plugging behavior of flaky LCMs within fractures,and the mechanisms enhancing the pressure-bearing capacity of the plugging zone are not well understood.Therefore,this study conducted visual plugging experiments and dynamic fracture plugging experiments to evaluate the plugging mode and pressure-bearing capacity of the plugging slurry with various particle sizes and concentrations of flaky LCMs.The experimental results demonstrate that the fracture plugging process can be divided into four stages:uniform flow stage of the plugging slurry,formation and development stage of the bridging area,formation and development stage of the plugging area,and pressure-bearing stage of the plugging zone.The inclusion of flaky LCMs notably reduces the duration of stages 1 and 2,while simultaneously increasing the proportion of the plugging zone and enhancing its surface porosity.Flaky LCMs reduce the effective fracture width through“interception”and“co-bridging”modes,thus improving plugging zone formation efficiency.Appropriate particle size and concentration of flaky LCMs increase the area and length of the plugging zone.This reduces the fracture width increment caused by injection pressure and enhances frictional force between the plugging zone and fracture surface,thereby improving the pressure-bearing capacity of the plugging zone.However,excessively high concentrations of flaky LCMs result in decreased structural stability of the plugging zone,and excessively large particle sizes increase the risk of plugging outside fracture inlet.The recommended concentration of flaky LCMs in the plugging slurry is 2%–3%,with a particle size 1.2 to 1.5 times that of the bridging granular LCMs and not exceeding twice the fracture width.This study provides a theoretical foundation for selecting LCMs and designing plugging formulations for field applications.
基金supported by National Natural Science Foundation of China(52304006,52274032,and 51774062)the General Project of the Chongqing Natural Science Foundation(CSTB2022NSCQ-MSX1554 and CSTB2022NSCQ-MSX0349)Shaanxi Province Key Laboratory of Environmental Pollution Control and Reservoir Protection Technology of Oilfields and Engineering Research Center of Oil and Gas Field Chemistry,Universities of Shaanxi Province(XSYU-CCCE-2402).
文摘Lost circulation of drilling fluid is an international engineering problem during drilling.Aiming at the problems of the first-time lost circulation control success rate and poor adaptability of traditional lost circulation materials,a new self-healing lost circulation material based on dynamic disulfide bonds was prepared and named CKSH.In this paper,the particle size of self-healing lost circulation material was from 0.1 to 5 mm.The structure was analyzed by modern characterization means,and the drilling fluid compatibility,self-healing performance were evaluated.The self-healing and bridging-filling-sealing mechanism of CKSH were revealed.The results showed that the healing rate of CKSH could reach100%after 12 h over 70℃.It showed good compatibility with drilling fluid,with no effect on rheology or filtration loss.It could be stably suspended in drilling fluid,and the temperature resistance reached140℃.Healing by self-healing lost circulation materials of different particle size,the pressure bearing capacity of plugging zone were over 12 MPa for fracture opening of 1–5 mm.It could play a synergistic role with traditional lost circulation materials by chemical bonding,and the repeated loss caused by physical plugging was avoided.The research results of this paper can improve the bridging plugging bearing pressure strength and the first-time lost circulation control success rate,which is of great significance for improving drilling efficiency and reducing non-productive time.
基金Supported by Daqing City Philosophy and Social Sciences Planning Research Project(DSGB 2025011)the Heilongjiang Province Education Science Planning Key Project(GJB1320229).
文摘Based on questionnaire surveys and field interviews conducted with various types of agricultural production organizations across five districts and four counties in Daqing City,this study combines relevant theoretical frameworks to systematically examine the evolution,performance,and influencing factors of governance mechanisms within these organizations.Using both quantitative and inductive analytical methods,the paper proposes innovative designs and supporting measures for improving governance mechanisms.The findings reveal that,amid large-scale farmland circulation,the governance mechanisms of agricultural production organizations in Daqing City are evolving from traditional to modern structures.However,challenges remain in areas such as decision-making efficiency,benefit distribution,and supervision mechanisms.In response,this study proposes innovative governance designs focusing on decision-making processes,profit-sharing mechanisms,and risk prevention.Corresponding policy recommendations are also provided to support the sustainable development of agricultural modernization in China.
基金German Heart Foundation/German Foundation of Heart Research。
文摘Background:Aortic atherosclerosis increases the risk of embolic events under extracorporeal circulation(ECC).To evaluate the hemodynamic impact of ECC on atheromatous plaques,an atherosclerosis animal model,which is also eligible for ECC,is required.Methods:Twenty-nine New Zealand White rabbits received a pro-atherosclerotic diet(group diet,n=10),a pro-atherosclerotic diet and additional intraaortic balloon insufflation injury(group BI,n=9),or served as controls(n=10).After 3 or 6 months,aortic explants were analyzed by(immuno-)histology and RT-PCR.Results:Blood serum analyses revealed increased cholesterol-levels in groups diet and BI compared to controls(3 months:p=0.03 each,6 months:p<0.0001 each).Aortic inflammatory infiltration was significantly enhanced in groups diet(CD3 at 3 months:p<0.0001,6 months:p=0.02;CD68 at 3 months:p=0.01)and BI(CD3 at 3 months:p<0.0001,6 months:p=0.03;CD68 at 3 months:p=0.04,6 months:p=0.02).Increased intima hyperplasia occurred in both groups(p<0.0001 each).Macroscopic analyses after 3 and 6 months showed ubiquitous lumen-narrowing aortic plaques.Calcification of the intima and media was increased in groups diet(intima:p<0.0001 at 3 and 6 months;media at 3 months:p<0.0001,6 months:p=0.01)and BI(intima:p<0.0001 at 3 and 6 months;media at 3 months:p<0.0001,6 months:p=0.02).Extensive lipid accumulation was found in the intima in both treatment groups(p<0.0001 each).Conclusions:A rabbit model with high aortic calcific plaque burden—diet-induced with no implicit need of an additional intimal injury by an intraaortic balloon insufflation due to comparable outcome—exhibiting multiple pathophysiological aspects of human atherosclerosis has been designed and thoroughly characterized.It is suitable for use in future studies on the interaction between atherosclerotic plaques and the arterial blood flow under ECC.
文摘Dear Editor,Dengue virus(DENV)is a positive-sense single-stranded RNA virus belonging to the Flaviviridae family,which causes dengue—a disease affecting over 400 million people annually worldwide.DENV is transmitted through the bite of mosquitoes from the Aedes genus,primarily Aedes aegypti,and has a wide distribution in tropical and subtropical areas(de Souza et al.,2022).
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.42325605)the National Natural Science Foundation of China(Grant No.42176243)the National Natural Science Foundation of China(Grant No.42222501)。
文摘The Hadley Circulation(HC),a fundamental component of global atmospheric circulation,plays an important role in the global energy balance and transport of moisture.The interaction between ENSO and the HC significantly impacts tropical climate and has broad implications for global climate variability through atmospheric teleconnections.The HC is usually represented by the mass stream function.As a result,it can rarely be observed through in-situ measurement.Reanalysis datasets and CMIP models are frequently used to investigate the properties of the HC.Previous studies systematically assess the capability of these CMIP models to represent the spatial distribution and intensity of the HC anomalies associated with ENSO events.However,most of these studies investigate the HC anomaly from a global perspective.In this work,we focus on evaluating the ability of CMIP6 models to capture the three-dimensional features of ENSO-related HC anomalies in comparison to that in six reanalysis datasets.Results show a consistent westward shift of the ENSO-related HC over the tropical Central-Eastern Pacific in almost all CMIP6 models,accompanied by a weakening of the asymmetric component of the ENSO-related HC over the equatorial Pacific.The former is mainly attributed to the westward extension of the Pacific cold tongue in CMIP models,while the latter is more related to the southward shift of the ENSO-related SST and precipitation anomalies in CMIP models.One should be aware of these biases when studying the ENSO-related atmospheric circulation changes.Our study has broad implications for ENSO simulations and the predictability of ENSO-related global climate variabilities.
基金Guangdong Major Project of Basic and Applied Basic Research (2020B0301030004)National Natural Science Foundation of China (42275041)Hainan Province Science and Technology Special Fund (SOLZSKY2025006)。
文摘In 2022, South China(SC) experienced record-breaking rainfall during its first rainy season, causing severe socioeconomic losses. This study examines the large-scale circulation anomalies responsible for this extreme event.Analysis reveals that the lower-tropospheric cyclonic anomaly over SC plays a crucial role. This cyclonic anomaly consists of extratropical northeasterly anomalies to the north of SC and tropical southwesterly anomalies to the south. Both components were particularly intense during the 2022 first rainy season, contributing to the heavy rainfall in SC. Moreover,the lower-tropospheric cyclonic anomaly is enhanced by its counterpart in the upper troposphere, which is associated with a wave train propagating from the North Atlantic to East Asia across the mid-high latitudes of the Eurasian continent.Further analysis indicates that the extratropical wave train correlates with sea surface temperature anomalies(SSTAs) in the North Atlantic. Additionally, the SSTAs over the North Indian Ocean also play a role in enhancing the tropical southwesterlies in the lower troposphere. This study highlights the combined influence of tropical and extratropical circulation anomalies, offering a comprehensive understanding of the record-breaking rainfall.
基金supported by the National Natural Science Foundation of China(Grant Nos.U244221042475072 and 42361144843).
文摘Using long-term Whole Atmosphere Community Climate Model version 5(WACCM5)simulations initialized with the climatology around the year 2000,we studied the anomalous distribution of planetary wave and gravity wave fluxes during distinct phases of the boreal stratospheric polar vortex(BSPV)and Quasi-Biennial Oscillation(QBO).The contributions of these two types of waves to Brewer-Dobson circulation(BDC)anomalies were further analyzed.The results revealed that under four distinct phases,the northern hemisphere BDC is primarily governed by planetary waves,whereas gravity waves counteract approximately half of the planetary wave influence on the BDC in the upper stratosphere.The QBO regulates the position of the anomaly center within the BDC’s descending branch in the northern hemisphere.In particular,during the westerly phase of the QBO(WQBO),the center of this anomalous descending branch is located in the upper stratosphere,whereas during the easterly phase of the QBO(EQBO),it is located in the lower stratosphere.Southern hemisphere BDC anomalies are regulated more by QBO activity:during the WQBO,it shows synchronous changes with the BDC anomaly in the northern hemisphere,whereas during the EQBO,it exhibits an antiphase relationship with the BDC anomaly in the northern hemisphere.Mesospheric circulation anomalies are predominantly driven by gravity wave activity.The circulation weakens during a weak BSPV and strengthens during a strong BSPV.Additionally,the descending branch anomaly of the northern hemisphere circulation is more pronounced during the WQBO,whereas the ascending branch anomaly of the southern hemisphere circulation is more significant during the EQBO.
