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
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
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
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
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
Subseasonal-to-seasonal(S2S)forecasting for East Asian atmospheric circulation poses significant challenges for conventional numerical weather prediction(NWP)models.Recently,deep learning(DL)models have demonstrated s...Subseasonal-to-seasonal(S2S)forecasting for East Asian atmospheric circulation poses significant challenges for conventional numerical weather prediction(NWP)models.Recently,deep learning(DL)models have demonstrated significant potential in further enhancing S2S forecasts beyond the capabilities of NWP models.However,most current DLbased S2S forecasting models largely overlook the role of global predictors from multiple spheres,such as ocean,land,and atmosphere domains,that are crucial for effective S2S forecasting.In this study,we introduce EAAC-S2S,a tailored DL model for S2S forecasting of East Asian atmospheric circulation.EAAC-S2S employs the cross-attention mechanism to couple atmospheric circulations over East Asia with representative multi-sphere(i.e.,atmosphere,land,and ocean)variables,providing pentad-averaged circulation forecasts up to 12 pentads ahead throughout all seasons.Experimental results demonstrate,on the S2S time scale,that EAAC-S2S consistently outperforms the European Centre for MediumRange Weather Forecasts(ECMWF)Ensemble Prediction System by decreasing the root-mean-square error(RMSE)by3.8%and increasing the anomaly correlation coefficient(ACC)by 8.6%,averaged across all 17 predictands.Our system also shows good skill for examples of heatwaves and the South China Sea Subtropical High Intensity Index(SCSSHII).Moreover,quantitative interpretability analysis including multi-sphere attribution and attention visualization are conducted for the first time in a DL S2S model,where the traced predictability aligns well with prior meteorological knowledge.We hope that our results have the potential to advance research in data-driven S2S forecasting.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
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
Aiming at the global design issue of transpiration cooling thermal protection system,a self-driven circulation loop is proposed as the internal coolant flow passage for the transpiration cooling structure to achieve a...Aiming at the global design issue of transpiration cooling thermal protection system,a self-driven circulation loop is proposed as the internal coolant flow passage for the transpiration cooling structure to achieve adaptive cooling.To enhance the universality of this internal cooling pipe design and facilitate its application,numerical studies are conducted on this systemwith four commonly used cooling mediums as coolant.Firstly,the accuracy of the numerical method is verified through an established experimental platform.Then,transient numerical simulations are performed on the flow states of different cooling mediums in the new self-circulation system.Based on the numerical result,the flow,phase change,and heat transfer characteristics of different cooling mediums are analyzed.Differences in fluid velocity and latent heat of phase change result in significant variation in heat exchange capacity among different coolingmediums,with the maximumdifference reaching up to 3 times.Besides,faster circulation speed leads to greater heat transfer capacity,with a maximum of 7600 W/m^(2).Consequently,the operating mechanism and cooling laws of the natural circulation system is further investigated,providing a reference for the practical application of this system.展开更多
The Twain-Hu Basin(THB),located in Central China,serves as a key juncture where the northerly“polluted”airflows of the East Asian winter monsoon meet the southerly warm and humid airflows.Using the T-PCA(T-mode Prin...The Twain-Hu Basin(THB),located in Central China,serves as a key juncture where the northerly“polluted”airflows of the East Asian winter monsoon meet the southerly warm and humid airflows.Using the T-PCA(T-mode Principal Component Analysis)objective synoptic pattern classification,Flexible Particle-Weather Research and Forecasting(FLEXPARTWRF)model,and Random Forest model,we investigate the influences of synoptic circulations on regional transport,local accumulation,and chemical transformation of PM_(2.5)during heavy air pollution over the THB in January of 2015-2022.The results show that the transport-type synoptic pattern accounts for 65.16%of heavy PM_(2.5)pollution,indicating that regional transport of PM_(2.5)dominates the THB’s heavy air pollution.The PM_(2.5)/CO ratio is higher in the transport-type pattern and positively correlated with PM_(2.5)concentrations,reflecting a higher efficiency of chemical transformation to secondary PM_(2.5)in transport-type pollution compared with the accumulation-type pollution.Transport-type heavy PM_(2.5)pollution is predominantly influenced by upstream anomalous northerly and easterly airflows at the bottom of the high-pressure system,converging with the southern wind in the receptor area over the THB.Accumulation-type heavy pollution exhibits weak wind anomalies in central and eastern China under the control of a uniform pressure field.Furthermore,thermally-induced vertical circulations with sinking airflows in the middle and lower troposphere suppress the vertical air pollutant dispersions.The relative contributions of atmospheric factors for transport-type PM_(2.5)heavy pollution events are 38.0%for dynamical driver,26.8%for thermal driver,and 35.1%for chemical transformation,while in accumulation-type,the contribution rates are 33.9%,36.3%,and 29.7%,respectively.This study elucidates the influences of synoptic patterns on regional transport,local accumulation,and chemical transformation of PM_(2.5)for heavy air pollution,with implications for understanding changes of air quality in the receptor region of regional transport.展开更多
Tropospheric ozone pollution has been worsened over most regions of China,adversely affecting human health and ecosystems.The long-term ozone concentration depends largely upon atmospheric circulations.Here,we conduct...Tropospheric ozone pollution has been worsened over most regions of China,adversely affecting human health and ecosystems.The long-term ozone concentration depends largely upon atmospheric circulations.Here,we conducted meteorological adjustment to quantitatively assess the influences of meteorological factors on the ozone evolution in China's seven city clusters during thewarm season(April to October)from 2013 to 2020.Our analysis indicated that northern and eastern regions experienced ozone increases driven by emission changes.Southern regions,particularly the Pearl River Delta(PRD),exhibited ozone rise primarily due to meteorological conditions despite emission changes.In the Sichuan Basin(SCB)and Central Yangtze River Plain(CYP),where ozone levels decreased,meteorological conditions played a significant role in suppressing the ascent of ozone.Empirical orthogonal functions(EOF)analyses suggested that the spatiotemporal trend ofmeteorologyassociated ozone was strongly correlated with the variation of East Asian Trough(EAT),South Asian High(SAH)and the western Pacific subtropical high(WPSH).The top three EOF patterns explained 33.4%,21.8%,and 16.0%of the total variance inmeteorology-associated ozone.Absolute principal component scores-multiple linear regression(APCS-MLR)analyse quantitatively identified that enhanced EAT and SAH with a northward location of WPSH were favourable to surface ozone formation in central and eastern regions,but unfavourable to ozone formation in edge regions such as SCB.展开更多
The impacts of the Luzon Strait transport on shallow meridional overturning circulation(SMOC)in the South China Sea(SCS)have been pointed out by previous studies,but the issue whether the Luzon Strait transport domina...The impacts of the Luzon Strait transport on shallow meridional overturning circulation(SMOC)in the South China Sea(SCS)have been pointed out by previous studies,but the issue whether the Luzon Strait transport dominates the SMOC formation still remains open.The Helmholtz decomposition is applied based on the ocean general circulation model for the earth simulator products to address this issue.Results show that the motion caused by the Luzon Strait transport is characterized as an obvious southward flow between 13°N and 20°N.After this motion being removed,the clockwise winter SMOC and the anticlockwise summer SMOC can still exist significantly.The SMOC existence and its seasonal variation are also reproduced in the numerical simulation with the Luzon Strait closed.Both results of the Helmholtz decomposition and numerical experiment suggest that the SMOC formation and its seasonal variation are not dominated by the Luzon Strait transport.The SCS monsoon is the primary driving factor for the SMOC,which is related to the physical processes within the SCS.展开更多
The discrepancy in the trends of the global zonal mean(GZM)intensity of the Hadley circulation(HCI)between reanalysis data and model simulations has been a problem for understanding the changes in HCI and the influenc...The discrepancy in the trends of the global zonal mean(GZM)intensity of the Hadley circulation(HCI)between reanalysis data and model simulations has been a problem for understanding the changes in HCI and the influence of external forcings.To understand the reason for this discrepancy,this study investigates the trends of intensity of regional HCI of the Northern Hemisphere over the eastern Pacific(EPA),western Pacific(WPA),Atlantic(ATL),Africa(AFR),the Indian Ocean(IDO),and residual area(RA),based on six reanalysis datasets and 13 CMIP6 models.In reanalysis data,the trends in regional HCI over EPA and ATL(WPA and AFR)contribute to(partially offset)the increasing trend in GZM HCI,while the trends in regional HCI over IDO are different in different reanalysis data.The CMIP6 models skillfully reproduce the trends in regional HCI over EPA,ATL,WPA,and AFR,but simulate notable decreasing trends in regional HCI over IDO,which is a key reason for the opposite trends in GZM HCI between reanalysis data and models.The discrepancy in IDO can be attributed to differences in the simulation of diabatic heating and zonal friction between reanalysis data and models.Optimal fingerprint analysis indicates that anthropogenic(ANT)and non-greenhouse gas(NOGHG)forcings are the dominant drivers of the HCI trends in the EPA and ATL regions.In the WPA(AFR)region,NOGHG(ANT)forcing serves as the primary driver.The findings contribute to improving the representation of regional HCI trends in models and improving the attribution of external forcings.展开更多
Lost circulation of drilling fluid is one of the most common and costly problems in drilling operations.This highlights the importance of wellbore strengthening treatment sthat can utilize lost circulation materials(L...Lost circulation of drilling fluid is one of the most common and costly problems in drilling operations.This highlights the importance of wellbore strengthening treatment sthat can utilize lost circulation materials(LCMs)to seal fractures associated with the wellbore.In this work,a numerical model accounting for the deformation of surrounding rock,fluid flow in the fracture,fracture propagation,and the transport of LCMs is presented to investigate the wellbore strengthening,from the fracture initiation to the fracture arrest,due to plugs formed by LCMs.The equations governing the rock deformation and fluid flow are solved by the dual boundary element method and the finite volume method,respectively.The transport of LCMs is solved based on an empirical constitutive model in suspension flow,and several characteristic quantities are derived by dimensional analysis.It is found that two dimensionless parameters,dimensionless toughness and normalized initial particle concentration,control the migration of LCM particles.The numerical results show that the dimensionless toughness influences the entrance and bridging of LCMs while the initial concentration controls the location of the particle bridging.When the initial concentration is larger than 0.8,the particle bridging tends to occur near the fracture entry.Conversely,when the initial concentration is less than 0.8,the particle bridging occurs near the fracture tip.This work provides an effective tool to predict the LCM transport and plugging in the wellbore strengthening process.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(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.
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.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.
基金supported in part by the Meteorological Joint Funds of the National Natural Science Foundation of China(Grant No.U2142211)by the National Key Research and Development Program of China(Grant No.2020YFA0608002)+4 种基金by the National Natural Science Foundation of China(Grant Nos.42075141 and 42341202)by the China National Postdoctoral Program for Innovative Talents(Grant No.BX20230071)by the National Natural Science Foundation of China for Youth(Grant No.42205191)by the Shanghai Municipal Science and Technology Major Project(Grant No.2021SHZDZX0100)the Fundamental Research Funds for the Central Universities。
文摘Subseasonal-to-seasonal(S2S)forecasting for East Asian atmospheric circulation poses significant challenges for conventional numerical weather prediction(NWP)models.Recently,deep learning(DL)models have demonstrated significant potential in further enhancing S2S forecasts beyond the capabilities of NWP models.However,most current DLbased S2S forecasting models largely overlook the role of global predictors from multiple spheres,such as ocean,land,and atmosphere domains,that are crucial for effective S2S forecasting.In this study,we introduce EAAC-S2S,a tailored DL model for S2S forecasting of East Asian atmospheric circulation.EAAC-S2S employs the cross-attention mechanism to couple atmospheric circulations over East Asia with representative multi-sphere(i.e.,atmosphere,land,and ocean)variables,providing pentad-averaged circulation forecasts up to 12 pentads ahead throughout all seasons.Experimental results demonstrate,on the S2S time scale,that EAAC-S2S consistently outperforms the European Centre for MediumRange Weather Forecasts(ECMWF)Ensemble Prediction System by decreasing the root-mean-square error(RMSE)by3.8%and increasing the anomaly correlation coefficient(ACC)by 8.6%,averaged across all 17 predictands.Our system also shows good skill for examples of heatwaves and the South China Sea Subtropical High Intensity Index(SCSSHII).Moreover,quantitative interpretability analysis including multi-sphere attribution and attention visualization are conducted for the first time in a DL S2S model,where the traced predictability aligns well with prior meteorological knowledge.We hope that our results have the potential to advance research in data-driven S2S forecasting.
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.
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funded by Fei He,National Natural Science Foundation of China(contract no.52376154)Anhui Provincial Natural Science Foundation(contract no.2308085J21).
文摘Aiming at the global design issue of transpiration cooling thermal protection system,a self-driven circulation loop is proposed as the internal coolant flow passage for the transpiration cooling structure to achieve adaptive cooling.To enhance the universality of this internal cooling pipe design and facilitate its application,numerical studies are conducted on this systemwith four commonly used cooling mediums as coolant.Firstly,the accuracy of the numerical method is verified through an established experimental platform.Then,transient numerical simulations are performed on the flow states of different cooling mediums in the new self-circulation system.Based on the numerical result,the flow,phase change,and heat transfer characteristics of different cooling mediums are analyzed.Differences in fluid velocity and latent heat of phase change result in significant variation in heat exchange capacity among different coolingmediums,with the maximumdifference reaching up to 3 times.Besides,faster circulation speed leads to greater heat transfer capacity,with a maximum of 7600 W/m^(2).Consequently,the operating mechanism and cooling laws of the natural circulation system is further investigated,providing a reference for the practical application of this system.
基金supported by the National Natural Science Foundation of China(Nos.42075186 and 41830965).
文摘The Twain-Hu Basin(THB),located in Central China,serves as a key juncture where the northerly“polluted”airflows of the East Asian winter monsoon meet the southerly warm and humid airflows.Using the T-PCA(T-mode Principal Component Analysis)objective synoptic pattern classification,Flexible Particle-Weather Research and Forecasting(FLEXPARTWRF)model,and Random Forest model,we investigate the influences of synoptic circulations on regional transport,local accumulation,and chemical transformation of PM_(2.5)during heavy air pollution over the THB in January of 2015-2022.The results show that the transport-type synoptic pattern accounts for 65.16%of heavy PM_(2.5)pollution,indicating that regional transport of PM_(2.5)dominates the THB’s heavy air pollution.The PM_(2.5)/CO ratio is higher in the transport-type pattern and positively correlated with PM_(2.5)concentrations,reflecting a higher efficiency of chemical transformation to secondary PM_(2.5)in transport-type pollution compared with the accumulation-type pollution.Transport-type heavy PM_(2.5)pollution is predominantly influenced by upstream anomalous northerly and easterly airflows at the bottom of the high-pressure system,converging with the southern wind in the receptor area over the THB.Accumulation-type heavy pollution exhibits weak wind anomalies in central and eastern China under the control of a uniform pressure field.Furthermore,thermally-induced vertical circulations with sinking airflows in the middle and lower troposphere suppress the vertical air pollutant dispersions.The relative contributions of atmospheric factors for transport-type PM_(2.5)heavy pollution events are 38.0%for dynamical driver,26.8%for thermal driver,and 35.1%for chemical transformation,while in accumulation-type,the contribution rates are 33.9%,36.3%,and 29.7%,respectively.This study elucidates the influences of synoptic patterns on regional transport,local accumulation,and chemical transformation of PM_(2.5)for heavy air pollution,with implications for understanding changes of air quality in the receptor region of regional transport.
基金supported by the National Natural Science Foundation of China(No.42377095)the Open Research Fund Program of Plateau Atmosphere and Environment Key Laboratory of Sichuan Province(No.PAEKL-2024-K01)Xianyang Key Research and Development Program(No.L2022ZDYFSF040).
文摘Tropospheric ozone pollution has been worsened over most regions of China,adversely affecting human health and ecosystems.The long-term ozone concentration depends largely upon atmospheric circulations.Here,we conducted meteorological adjustment to quantitatively assess the influences of meteorological factors on the ozone evolution in China's seven city clusters during thewarm season(April to October)from 2013 to 2020.Our analysis indicated that northern and eastern regions experienced ozone increases driven by emission changes.Southern regions,particularly the Pearl River Delta(PRD),exhibited ozone rise primarily due to meteorological conditions despite emission changes.In the Sichuan Basin(SCB)and Central Yangtze River Plain(CYP),where ozone levels decreased,meteorological conditions played a significant role in suppressing the ascent of ozone.Empirical orthogonal functions(EOF)analyses suggested that the spatiotemporal trend ofmeteorologyassociated ozone was strongly correlated with the variation of East Asian Trough(EAT),South Asian High(SAH)and the western Pacific subtropical high(WPSH).The top three EOF patterns explained 33.4%,21.8%,and 16.0%of the total variance inmeteorology-associated ozone.Absolute principal component scores-multiple linear regression(APCS-MLR)analyse quantitatively identified that enhanced EAT and SAH with a northward location of WPSH were favourable to surface ozone formation in central and eastern regions,but unfavourable to ozone formation in edge regions such as SCB.
基金The National Natural Science Foundation of China under contract No.42076003.
文摘The impacts of the Luzon Strait transport on shallow meridional overturning circulation(SMOC)in the South China Sea(SCS)have been pointed out by previous studies,but the issue whether the Luzon Strait transport dominates the SMOC formation still remains open.The Helmholtz decomposition is applied based on the ocean general circulation model for the earth simulator products to address this issue.Results show that the motion caused by the Luzon Strait transport is characterized as an obvious southward flow between 13°N and 20°N.After this motion being removed,the clockwise winter SMOC and the anticlockwise summer SMOC can still exist significantly.The SMOC existence and its seasonal variation are also reproduced in the numerical simulation with the Luzon Strait closed.Both results of the Helmholtz decomposition and numerical experiment suggest that the SMOC formation and its seasonal variation are not dominated by the Luzon Strait transport.The SCS monsoon is the primary driving factor for the SMOC,which is related to the physical processes within the SCS.
基金the National Key Research and Development Program of China[grant number 2022YFF0801704].
文摘The discrepancy in the trends of the global zonal mean(GZM)intensity of the Hadley circulation(HCI)between reanalysis data and model simulations has been a problem for understanding the changes in HCI and the influence of external forcings.To understand the reason for this discrepancy,this study investigates the trends of intensity of regional HCI of the Northern Hemisphere over the eastern Pacific(EPA),western Pacific(WPA),Atlantic(ATL),Africa(AFR),the Indian Ocean(IDO),and residual area(RA),based on six reanalysis datasets and 13 CMIP6 models.In reanalysis data,the trends in regional HCI over EPA and ATL(WPA and AFR)contribute to(partially offset)the increasing trend in GZM HCI,while the trends in regional HCI over IDO are different in different reanalysis data.The CMIP6 models skillfully reproduce the trends in regional HCI over EPA,ATL,WPA,and AFR,but simulate notable decreasing trends in regional HCI over IDO,which is a key reason for the opposite trends in GZM HCI between reanalysis data and models.The discrepancy in IDO can be attributed to differences in the simulation of diabatic heating and zonal friction between reanalysis data and models.Optimal fingerprint analysis indicates that anthropogenic(ANT)and non-greenhouse gas(NOGHG)forcings are the dominant drivers of the HCI trends in the EPA and ATL regions.In the WPA(AFR)region,NOGHG(ANT)forcing serves as the primary driver.The findings contribute to improving the representation of regional HCI trends in models and improving the attribution of external forcings.
基金support of the National Natural Science Foundation of China(Grant No.52371279)the Program for International Exchange and Cooperation in Education by the Ministry of Education of the People's Republic of China(Grant No.57220500123).
文摘Lost circulation of drilling fluid is one of the most common and costly problems in drilling operations.This highlights the importance of wellbore strengthening treatment sthat can utilize lost circulation materials(LCMs)to seal fractures associated with the wellbore.In this work,a numerical model accounting for the deformation of surrounding rock,fluid flow in the fracture,fracture propagation,and the transport of LCMs is presented to investigate the wellbore strengthening,from the fracture initiation to the fracture arrest,due to plugs formed by LCMs.The equations governing the rock deformation and fluid flow are solved by the dual boundary element method and the finite volume method,respectively.The transport of LCMs is solved based on an empirical constitutive model in suspension flow,and several characteristic quantities are derived by dimensional analysis.It is found that two dimensionless parameters,dimensionless toughness and normalized initial particle concentration,control the migration of LCM particles.The numerical results show that the dimensionless toughness influences the entrance and bridging of LCMs while the initial concentration controls the location of the particle bridging.When the initial concentration is larger than 0.8,the particle bridging tends to occur near the fracture entry.Conversely,when the initial concentration is less than 0.8,the particle bridging occurs near the fracture tip.This work provides an effective tool to predict the LCM transport and plugging in the wellbore strengthening process.
