An in-depth mechanism in zonal activation of CO_(2)and H2molecular over dual-active sites has not been revealed yet.Here,Ni-Co-MgO was rationally constructed to elucidate the CO_(2)methanation mechanism.The abundant s...An in-depth mechanism in zonal activation of CO_(2)and H2molecular over dual-active sites has not been revealed yet.Here,Ni-Co-MgO was rationally constructed to elucidate the CO_(2)methanation mechanism.The abundant surface nickel and cobalt components as active sites led to strong Ni-Co interaction with charge transfer from nickel to cobalt.Notably,electron-enriched Coδ-species participated in efficient chemisorption and activation of CO_(2)to generate monodentate carbonate.Simultaneously,plentiful available Ni0sites facilitated H2dissociation,thus CO_(2)and H2were smoothly activated at zones of Coδ-species and Ni0,respectively.Detailed in situ DRIFTS,quasi situ XPS,TPSR,and DFT calculations substantiated a new formate evolution mechanism via monodentate carbonate instead of traditional bidentate carbonate based on synergistic catalysis of Coδ-species and Ni0.The zonal activation of CO_(2)and H2by tuning electron behaviors of double-center catalysts can boost heterogeneous catalytic hydrogenation performance.展开更多
El Nino-Southern Oscillation(ENSO),the leading mode of global interannual variability,usually intensifies the Hadley Circulation(HC),and meanwhile constrains its meridional extension,leading to an equatorward movement...El Nino-Southern Oscillation(ENSO),the leading mode of global interannual variability,usually intensifies the Hadley Circulation(HC),and meanwhile constrains its meridional extension,leading to an equatorward movement of the jet system.Previous studies have investigated the response of HC to ENSO events using different reanalysis datasets and evaluated their capability in capturing the main features of ENSO-associated HC anomalies.However,these studies mainly focused on the global HC,represented by a zonal-mean mass stream function(MSF).Comparatively fewer studies have evaluated HC responses from a regional perspective,partly due to the prerequisite of the Stokes MSF,which prevents us from integrating a regional HC.In this study,we adopt a recently developed technique to construct the three-dimensional structure of HC and evaluate the capability of eight state-of-the-art reanalyses in reproducing the regional HC response to ENSO events.Results show that all eight reanalyses reproduce the spatial structure of HC responses well,with an intensified HC around the central-eastern Pacific but weakened circulations around the Indo-Pacific warm pool and tropical Atlantic.The spatial correlation coefficient of the three-dimensional HC anomalies among the different datasets is always larger than 0.93.However,these datasets may not capture the amplitudes of the HC responses well.This uncertainty is especially large for ENSO-associated equatorially asymmetric HC anomalies,with the maximum amplitude in Climate Forecast System Reanalysis(CFSR)being about 2.7 times the minimum value in the Twentieth Century Reanalysis(20CR).One should be careful when using reanalysis data to evaluate the intensity of ENSO-associated HC anomalies.展开更多
Lost circulation is a common downhole problem of drilling in geothermal and high-temperature,high-pressure(HTHP)formations.Lost circulation material(LCM)is a regular preventive and remedial measure for lost circulatio...Lost circulation is a common downhole problem of drilling in geothermal and high-temperature,high-pressure(HTHP)formations.Lost circulation material(LCM)is a regular preventive and remedial measure for lost circulation.However,conventional LCMs seem ineffective in high-temperature formations.This may be due to the changes in the mechanical properties of LCMs and their sealing performance under high-temperature conditions.To understand how high temperature affects the fracture sealing performance of LCMs,we developed a coupled computational fluid dynamics-discrete element method(CFD-DEM)model to simulate the behavior of granular LCMs in fractures.We summarized the literature on the effects of high temperature on the mechanical properties of LCMs and the rheological properties of drilling fluid.We conducted sensitivity analyses to investigate how changing LCM slurry properties affected the fracture sealing efficiency at increasing temperatures.The results show that high temperature reduces the size,strength,and friction coefficient of LCMs as well as the drilling fluid viscosity.Smaller,softer,and less frictional LCM particles have lower bridging probability and slower bridging initiation.Smaller particles tend to form dual-particle bridges rather than single-particle bridges.These result in a deeper,tighter,but unstable sealing zone.Reduced drilling fluid viscosity leads to faster and shallower sealing zones.展开更多
Objective:Patients with ductal-dependent pulmonary circulation require alternative bloodflow to provide and maintain adequate oxygenation.Modified Blalock-Taussig Shunt(MBTS)has been the standard for providing such a re...Objective:Patients with ductal-dependent pulmonary circulation require alternative bloodflow to provide and maintain adequate oxygenation.Modified Blalock-Taussig Shunt(MBTS)has been the standard for providing such a result.Currently,less invasive methods such as Arterial Duct(AD)stenting have been performed as alter-natives.This study aims to compare the outcome of AD stenting and MBTS.Method:Systematic research was performed in online databases using the PRISMA protocol.The outcomes measured were 30-day mortality,com-plication,unplanned intervention,oxygen saturation,duration of hospital,and ICU length of stay.Any compara-tive study provided with full text is included.The outcome of each study was analyzed using a trandom effects model with relative risk and mean difference as the effect size.Bias risk assessment was conducted using the New-castle-Ottawa Scale.All analyses were performed using Review Manager 5.4.1.Result:A total of 11 studies with 3154 samples included in this study.There is no significant difference in 30-day mortality between the two groups(p-value=0.10).However,there is significantly less complication(RR 0.53[0.35,0.82];p-value=0.004)and unplanned intervention(RR 0.59[0.38,0.92];p-value=0.02)in the AD stent group.Comparison of the Nakata index showed no significant difference(p-value=0.88).Post-operative oxygen saturation was measured signifi-cantly higher in the AD stenting(MD 1.80[0.85,2.74];p-value=0.0002).However,AD stent group shows sig-nificantly lower long-term oxygen saturation(MD-8.43[-14.38,-2.48];p-value=0.005).Both hospital and ICU length of stay was significantly shorter in the AD stent group(MD-8.30[-11.13,-5.48];p-value<0.00001;MD-5.09[-7.79,-2.38];p-value=0.0002).Conclusion:AD stenting provides comparable outcomes relative to MBTS as it provides less complication and unplanned intervention and higher post-procedural O2 saturation.However,MBTS proved its superiority in maintaining higher long-term oxygen saturation and still became the preferred option to manage complex cases where stenting is either challenging or unsuccessful.展开更多
BACKGROUND:Unsustained return of spontaneous circulation(ROSC)is a critical barrier to survival in cardiac arrest patients.This study examined whether end-tidal carbon dioxide(ETCO_(2))and pulse oximetry photoplethysm...BACKGROUND:Unsustained return of spontaneous circulation(ROSC)is a critical barrier to survival in cardiac arrest patients.This study examined whether end-tidal carbon dioxide(ETCO_(2))and pulse oximetry photoplethysmogram(POP)parameters can be used to identify unsustained ROSC.METHODS:We conducted a multicenter observational prospective cohort study of consecutive patients with cardiac arrest from 2013 to 2014.Patients’general information,ETCO_(2),and POP parameters were collected and statistically analyzed.RESULTS:The included 105 ROSC episodes(from 80 cardiac arrest patients)comprised 51 sustained ROSC episodes and 54 unsustained ROSC episodes.The 24-hour survival rate was significantly higher in the sustained ROSC group than in the unsustained ROSC group(29.2%vs.9.4%,P<0.05).The logistic regression analysis showed that the difference between after and before ROSC in ETCO_(2)(ΔETCO_(2))and the difference between after and before ROCS in area under the curve of POP(ΔAUCp)were independently associated with sustained ROSC(odds ratio[OR]=0.931,95%confi dence interval[95%CI]0.881-0.984,P=0.011 and OR=0.998,95%CI 0.997-0.999,P<0.001).The area under the receiver operating characteristic curve ofΔETCO_(2),ΔAUCp,and the combination of both to predict unsustained ROSC were 0.752(95%CI 0.660-0.844),0.883(95%CI 0.818-0.948),and 0.902(95%CI 0.842-0.962),respectively.CONCLUSION:Patients with unsustained ROSC have a poor prognosis.The combination ofΔETCO_(2) andΔAUCp showed signifi cant predictive value for unsustained ROSC.展开更多
Aim: To explore the application effect of external diaphragm pacemaker combined with active respiratory circulation technology in pulmonary rehabilitation of perioperative lung cancer patients. Methods: A total of 98 ...Aim: To explore the application effect of external diaphragm pacemaker combined with active respiratory circulation technology in pulmonary rehabilitation of perioperative lung cancer patients. Methods: A total of 98 lung cancer patients admitted to our hospital from April 2020 to November 2021 were selected as the observation objects, and then divided into a control group and an observation group using the random number table method, with 49 cases in each group. The control group received routine admission guidance and active respiratory circulation training, while the observation group was supplemented with external diaphragm pacemaker on the basis of the control group. The intervention effect was evaluated by blood gas indicators, pulmonary function indicators, diaphragm function indicators, sputum comfort degree, and activity tolerance indicators before and after intervention. Results: Before intervention, there were no significant differences in blood gas analysis indicators, pulmonary function indicators, diaphragm function indicators, sputum comfort degree, and activity tolerance indicators between the two groups (P > 0.05). After intervention, the improvement degree of the above indicators in the observation group was higher than that in the control group (P < 0.05). Conclusions: The application of external diaphragm pacemaker combined with active respiratory circulation technology in pulmonary rehabilitation of perioperative lung cancer patients is significant, which can effectively improve the pulmonary function, blood gas function, and diaphragm function of lung cancer patients after surgery, and improve the activities of daily living and quality of life of patients.展开更多
Atlantic meridional overturning circulation(AMOC)plays an important role in transporting heat meridionally in the Earth’s climate system and is also a key metrical tool to verify oceanic general circulation models.Tw...Atlantic meridional overturning circulation(AMOC)plays an important role in transporting heat meridionally in the Earth’s climate system and is also a key metrical tool to verify oceanic general circulation models.Two OMIP(Ocean Model Intercomparison Project phase 1 and 2)simulations with LICOM3(version 3 of the LASG/IAP Climate System Ocean Model)developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG),Institute of Atmospheric Physics(IAP),are compared in this study.Both simulations well reproduce the fundamental characteristics of the AMOC,but the OMIP1 simulation shows a significantly stronger AMOC than the OMIP2 simulation.Because the LICOM3 configurations are identical between these two experiments,any differences between them must be attributed to the surface forcing data.Further analysis suggests that sea surface salinity(SSS)differences should be mainly responsible for the enhanced AMOC in the OMIP1 simulation,but sea surface temperature(SST)also play an unignorable role in modulating AMOC.In the North Atlantic,where deep convection occurs,the SSS in OMIP1 is more saline than that in OMIP1.We find that in the major region of deep convection,the change of SSS has more significant effect on density than the change of SST.As a result,the SSS was more saline than that in OMIP2,leading to stronger deep convection and subsequently intensify the AMOC.We conduct a series of numerical experiments with LICOM3,and the results confirmed that the changes in SSS have more significant effect on the strength of AMOC than the changes in SST.展开更多
This is an erratum to an already published paper named“Establishment of a prediction model for prehospital return of spontaneous circulation in out-ofhospital patients with cardiac arrest”.We found errors in the aff...This is an erratum to an already published paper named“Establishment of a prediction model for prehospital return of spontaneous circulation in out-ofhospital patients with cardiac arrest”.We found errors in the affiliated institution of the authors.We apologize for our unintentional mistake.Please note,these changes do not affect our results.展开更多
Based on ERA5 reanalysis data,the present study analyzed the thermal energy development mechanism and kinetic energy conversion characteristics of two extreme rainstorm processes in relation to the shallow southwest v...Based on ERA5 reanalysis data,the present study analyzed the thermal energy development mechanism and kinetic energy conversion characteristics of two extreme rainstorm processes in relation to the shallow southwest vortex in the warm-sector during a“rain-generated vortex”process and the deep southwest vortex in a“vortex-generated rain”process.The findings were as follows:(1)During the extreme rainstorm on August 11,2020(hereinafter referred to as the“8·11”process),intense surface heating and a high-energy unstable environment were observed.The mesoscale convergence system triggered convection to produce heavy rainfall,and the release of latent condensation heat generated by the rainfall promoted the formation of a southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy preceded the increase(decrease)in vorticity.By contrast,the extreme rainstorm on August 16,2020(hereinafter referred to as the“8·16”process)involved the generation of southwest vortex in a low-energy and highhumidity environment.The dynamic uplift of the southwest vortex triggered rainfall,and the release of condensation latent heat from rainfall further strengthened the development of the southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy exhibited a delayed progression compared to the increase(decrease)in vorticity.(2)The heating effect around the southwest vortex region was non-uniform,and the heating intensity varied in different stages.In the“8·11”process,the heating effect was the strongest in the initial stage,but weakened during the vortex's development.On the contrary,the heating effect was initially weak in the“8·16”process,and intensified during the development stage.(3)The available potential energy of the“8·11”process significantly increased in kinetic energy converted from rotational and divergent winds through baroclinic action,and the divergent wind energy continued to convert into rotational wind energy.By contrast,the“8·16”process involved the conversion of rotational wind energy into divergent wind energy,which in turn converted kinetic energy back into available potential energy,thereby impeding the further development and maintenance of the southwest vortex.展开更多
This study investigates the relationship between circulation patterns and austral summer temperature anomalies in southern Africa. The results show that the formation of continental lows tends to increase the thicknes...This study investigates the relationship between circulation patterns and austral summer temperature anomalies in southern Africa. The results show that the formation of continental lows tends to increase the thickness of the lower atmosphere. Further, the distinct variabilities of high and low pressure under the circulation types, influence air mass advection from the adjacent oceans, as well as atmospheric stability over land. Stronger anticyclonic circulation at the western branch of the Mascarene high-pressure system enhances the low-level cold air advection by southeast winds,decreases the thickness, and lowers the temperature over a majority of the land in southern Africa. Conversely, a weaker Mascarene High, coupled with enhanced cyclonic activity in the southwest Indian Ocean increases low-level warm air advection and increases temperature anomalies over vast regions in southern Africa. The ridging of a closed South Atlantic anticyclone at the southern coast of southern Africa results in colder temperatures near the tip of southern Africa due to enhanced low-level cold air advection by southeast winds. However, when the ridge is weak and westerly winds dominate the southern coast of southern Africa, these areas experience temperature increases. The northward track of the Southern Hemisphere mid-latitude cyclone, which can be linked to the negative Southern Annular Mode, reduces the temperature in the southwestern part of southern Africa. Also, during the analysis period, El Ni?o was associated with temperature increases over the central parts of southern Africa;while the positive Indian Ocean dipole was linked to a temperature increase over the northeastern, northwestern, and southwestern parts of southern Africa.展开更多
Huaihe River Basin(HRB) is located in China’s north-south climatic transition zone,which is very sensitive to global climate change.Based on the daily maximum temperature,minimum temperature,and precipitation data of...Huaihe River Basin(HRB) is located in China’s north-south climatic transition zone,which is very sensitive to global climate change.Based on the daily maximum temperature,minimum temperature,and precipitation data of 40 meteorological stations and nine monthly large-scale ocean-atmospheric circulation indices data during 1959–2019,we present an assessment of the spatial and temporal variations of extreme temperature and precipitation events in the HRB using nine extreme climate indices,and analyze the teleconnection relationship between extreme climate indices and large-scale ocean-atmospheric circulation indices.The results show that warm extreme indices show a significant(P < 0.05) increasing trend,while cold extreme indices(except for cold spell duration) and diurnal temperature range(DTR) show a significant decreasing trend.Furthermore,all extreme temperature indices show significant mutations during 1959-2019.Spatially,a stronger warming trend occurs in eastern HRB than western HRB,while maximum 5-d precipitation(Rx5day) and rainstorm days(R25) show an increasing trend in the southern,central,and northwestern regions of HRB.Arctic oscillation(AO),Atlantic multidecadal oscillation(AMO),and East Atlantic/Western Russia(EA/WR) have a stronger correlation with extreme climate indices compared to other circulation indices.AO and AMO(EA/WR) exhibit a significant(P < 0.05) negative(positive)correlation with frost days and diurnal temperature range.Extreme warm events are strongly correlated with the variability of AMO and EA/WR in most parts of HRB,while extreme cold events are closely related to the variability of AO and AMO in eastern HRB.In contrast,AMO,AO,and EA/WR show limited impacts on extreme precipitation events in most parts of HRB.展开更多
The Atlantic Meridional Overturning Circulation(AMOC)is a crucial component of the Earth’s climate system due to its fundamental role in heat distribution,carbon and oxygen transport,and the weather.Other climate com...The Atlantic Meridional Overturning Circulation(AMOC)is a crucial component of the Earth’s climate system due to its fundamental role in heat distribution,carbon and oxygen transport,and the weather.Other climate components,such as the atmosphere and sea ice,influence the AMOC.Evaluating the physical mechanisms of those interactions is paramount to increasing knowledge about AMOC’s functioning.In this study,the authors used outputs from the Community Earth System Model version 2 and observational data to investigate changes in theAMOC and the associated physical processes.Two DECK experiments were evaluated:piControl and 1pctCO_(2),with an annual increase of 1%of atmospheric CO_(2).The analysis revealed a significant decrease in the AMOC,associated with changes in mixed layer depth and buoyancy in high latitudes of the North Atlantic,resulting in the shutdown of deep convection and potentially affecting the formation of North Atlantic Deep Water and Antarctic Bottom Water.A vital aspect observed in this study is the association between increased runoff and reduced water evaporation,giving rise to a positive feedback process.Consequently,the rates of freshwater spreading have intensified during this period,which could lead to an accelerated disruption of the AMOC beyond the projections of existing models.展开更多
The long-term relationship between the tree-ring-reconstructed annual precipitation in northeastern Mongolia (PRM) and the Northern Hemisphere Zonal Circulation (NHZC), defined as the normalized zonal mean sea-lev...The long-term relationship between the tree-ring-reconstructed annual precipitation in northeastern Mongolia (PRM) and the Northern Hemisphere Zonal Circulation (NHZC), defined as the normalized zonal mean sea-level pressure at 60°N in May-June-July, is examined in this study. A significant correlation coefficient (0.31) was found between the NHZC indices and PRM based on the dataset for the period of 1872-1995. The mechanisms responsible for the relationship are discussed through analyses of the atmospheric general circulation variability associated with NHZC. It follows that NHZC-related atmospheric circulation variability provides an anomalous southeast flow from the ocean to Northeast Mongolia (northwest flow from Northeast Mongolia to the ocean) in the middle and low troposphere in positive (negative) phase of NHZC, resulting in more (less) water vapor transport to the target region and more (less) precipitation in Northeast Mongolia.展开更多
Zonal overturning circulation (ZOC) and its associated zonal heat flux (ZHF) are important components of the oceanic circulation and climate system, although these conceptions have not received adequate attentions...Zonal overturning circulation (ZOC) and its associated zonal heat flux (ZHF) are important components of the oceanic circulation and climate system, although these conceptions have not received adequate attentions. Heaving induced by inter-annual and decadal wind stress perturbations can give rise to anomalous ZOC and ZHF. Based on a simple reduced gravity model, the anomalous ZOC and ZHF induced by idealized heaving modes in the world oceans are studied. For example, in a Pacific-like model basin intensified equatorial easterly on decadal time scales can lead to a negative ZOC with a non-negligible magnitude (-0.3×10^6 m^3/s) and a considerable westward ZHF with an amplitude of -11.2 TW. Thus, anomalous ZOC and ZHF may consist of a major part of climate signals on decadal time scales and thus play an important role in the oceanic circulation and climate change.展开更多
This paper examines the dominant submonthly variability of zonally symmetrical atmospheric circula- tion in the Northern Hemisphere (NH) winter within the context of the Northern Annular Mode (NAM), with particula...This paper examines the dominant submonthly variability of zonally symmetrical atmospheric circula- tion in the Northern Hemisphere (NH) winter within the context of the Northern Annular Mode (NAM), with particular emphasis on interactive stratosphere-troposphere processes. The submonthly variability is identified and measured using a daily NAM index, which concentrates primarily on zonally symmetrical circulation. A schematic lifecycle of submonthly variability is developed that reveals a two-way coupling pro- cess between the stratosphere and troposphere in the NH polar region. Specifically, anomalous tropospheric zonal winds in the Atlantic and Pacific sectors of the Arctic propagate upwards to the low stratosphere, disturbing the polar vortex, and resulting in an anomalous stratospheric geopotential height (HGT) that subsequently propagates down into the troposphere and changes the sign of the surface circulations. From the standpoint of planetary-scale wave activities, a feedback loop is also evident when the anoma- lous planetary-scale waves (with wavenumbers 2 and 3) propagate upwards, which disturbs the anomalous zonally symmetrical flow in the low stratosphere, and induces the anomalous HGT to move poleward in the low stratosphere, and then propagates down into the troposphere. This increases the energy of waves at wavenumbers 2 and 3 in the low troposphere in middle latitudes by enhancing the land-sea contrast of the anomalous HGT field. Thus, this study supports the viewpoint that the downward propagation of stratospheric NAM signals may not originate in the stratosphere.展开更多
A discussion of the mass transport of the Hadley circulation is presented, with regard to its longitudinal structure. Data from the NCEP/NCAR reanalysis data set for the period 1948-2005 is examined, focusing on the s...A discussion of the mass transport of the Hadley circulation is presented, with regard to its longitudinal structure. Data from the NCEP/NCAR reanalysis data set for the period 1948-2005 is examined, focusing on the solsticial seasons of June-August and December-February. Quantitative estimates have been extracted from the data to observe connections between the zonal mean of the upper tropospheric north/south mass transports and their relationship to the driving factor of tropical precipitation (implying latent heat release) and subsidence in the subtropical high pressure belts. The longitudinal structure of this flow is then examined with regard to these three main variables. The poleward upper tropospheric transport has four (JJA) or three (DJF) main branches, which link regions of major precipitation with corresponding regions of large subsidence, and one (June, July, August) or two (December, January, February) reverse branches. This structure has remained stable over the past sixty years. Although the total upper tropospheric transport in each season is less than the total sinking transport in the target subtropical high pressure belt, this does not apply to the individual branches, the balance being made up by the upper tropospheric reverse transports. An analysis of correlations between all of these various components shows, however, that the complete picture is more complex, with some precipitation regions being linked to subsidence regions outside their own branch.展开更多
This study reveals a significant positive connection between autumn non-tropical-cyclone heavy rainfall on Hainan Island and the intensity of Eastern Pacific(EP)El Ni?o events.That is,the amount of rainfall in super E...This study reveals a significant positive connection between autumn non-tropical-cyclone heavy rainfall on Hainan Island and the intensity of Eastern Pacific(EP)El Ni?o events.That is,the amount of rainfall in super EP El Ni?o years is more than that in normal EP El Ni?o years.Comparing EP El Ni?o years of different intensities,the cooler sea surface temperature in the northwestern Pacific during super EP El Ni?o years stimulates a negative surface latent heat flux(LHF)anomaly and abnormal anticyclonic circulation at 850 hPa.Under these conditions,an abnormal zonal vertical circulation develops in the northern South China Sea once a positive LHF anomaly and abnormal cyclonic circulation(ACC)at 850hPa occur in the Beibu Gulf.The abnormal zonal vertical circulation further strengthens the ascending motion over Hainan Island,as the critical factor that leads to excessive rainfall.Further analysis shows that the positive LHF anomaly,which can be attributed to the increased latent heat transfer which resulted from the increased surface wind speed,is an important trigger for the ACC.However,the ACC is also the supplier of favorable moisture conditions because it intensifies vapor convergence over Hainan Island and meridionally transports moisture from the South China Sea to northeastern Hainan Island,thereby generating heavy rainfall.This paper emphasizes that the impact of El Ni?o events,especially super El Ni?o events,on rainfall over Hainan Island cannot be ignored,even if the traditional view is that frequent rainfall occurs mainly in La Ni?a years.展开更多
The abrupt changes of zonal circulation in the Tibetan Plateau(TP) region and their likely causes are derived from National Centers for Environmental Prediction and the National Center for Atmospheric Research reanaly...The abrupt changes of zonal circulation in the Tibetan Plateau(TP) region and their likely causes are derived from National Centers for Environmental Prediction and the National Center for Atmospheric Research reanalysis data.The zonal circulation over the TP abruptly changed in summer(31st pentad) and winter(59th pentad).The switch from summer to winter circulation is characterized by a sudden northward shift of the westerlies and the zero-velocity curve and disappearance of the westerly jet.The winter-summer switch is characterized by the reverse pattern.Therefore,the circulation conversion between summer and winter can be judged from the position of the zero-velocity curve.Curves located north of 20 °N indicate summer circulation over the TP and vice versa.The abrupt change of zonal circulation is mainly caused by the thermodynamic effect of the TP.In June,this effect causes a huge monsoon circulation cell extending from the TP to low latitudes.Consequently,the westerlies jump to the north as easterlies develop.This process,which is enhanced by the strong northerly in Coriolis,establishes the summer circulation.In October,the Hadley cell recurs as the thermal effects of the TP diminish,the westerlies rush southward,and the winter circulation is established.展开更多
To infer the internal equilibrium structure of a gaseous planet, especially the equation of state(EOS) and size of its inner core,requires accurate determination of lower-order zonal gravitational coefficients. Modeli...To infer the internal equilibrium structure of a gaseous planet, especially the equation of state(EOS) and size of its inner core,requires accurate determination of lower-order zonal gravitational coefficients. Modeling of the gravitational signature associated with deep zonal circulation depends critically upon reliable subtraction of the dynamical components from totally derived gravitational coefficients. In the era of the Juno mission and the Grand Finale phase of the Cassini mission, it is timely and necessary to revisit and examine the so-called ‘Thermal Wind Equation(TWE)’, which has been extensively utilized to diagnose the dynamical parts of the gravitational fields measured by the two spacecrafts. TWE treats as negligible a few terms in the full equation of balance. However, the self-gravitational anomaly of the distorted fluid, unlike oblateness effects of solid-body rotation, is not a priori minor and thus should not be neglected in the name of approximation. Another equation, the ‘Thermal Gravitational Wind Equation(TGWE)’, includes this important additional term;we compare it with the TWE and show that physically the TGWE models a fundamentally different balance from the TWE and delivers numerical results considerably different from models based on the TWE. We conclude that the TWE balance cannot be relied upon to produce realistic convection models. Only after the TGWE balance is obtained can the relative importance of terms be assessed.The calculations we report here are based on two types of zonal circulations that are produced by realistically possible convections inside planets, instead of being constructed or assumed.展开更多
基金funded by the Science and Technology Project of Southwest United Graduate School of Yunnan Province(No.202302AQ370002)the National Natural Science Foundation of China(No.22206066)。
文摘An in-depth mechanism in zonal activation of CO_(2)and H2molecular over dual-active sites has not been revealed yet.Here,Ni-Co-MgO was rationally constructed to elucidate the CO_(2)methanation mechanism.The abundant surface nickel and cobalt components as active sites led to strong Ni-Co interaction with charge transfer from nickel to cobalt.Notably,electron-enriched Coδ-species participated in efficient chemisorption and activation of CO_(2)to generate monodentate carbonate.Simultaneously,plentiful available Ni0sites facilitated H2dissociation,thus CO_(2)and H2were smoothly activated at zones of Coδ-species and Ni0,respectively.Detailed in situ DRIFTS,quasi situ XPS,TPSR,and DFT calculations substantiated a new formate evolution mechanism via monodentate carbonate instead of traditional bidentate carbonate based on synergistic catalysis of Coδ-species and Ni0.The zonal activation of CO_(2)and H2by tuning electron behaviors of double-center catalysts can boost heterogeneous catalytic hydrogenation performance.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0605703)the National Natural Science Foundation of China(Grant Nos.42176243,41976193 and 41676190)supported by National Natural Science Foundation of China(Grant No.41975079)。
文摘El Nino-Southern Oscillation(ENSO),the leading mode of global interannual variability,usually intensifies the Hadley Circulation(HC),and meanwhile constrains its meridional extension,leading to an equatorward movement of the jet system.Previous studies have investigated the response of HC to ENSO events using different reanalysis datasets and evaluated their capability in capturing the main features of ENSO-associated HC anomalies.However,these studies mainly focused on the global HC,represented by a zonal-mean mass stream function(MSF).Comparatively fewer studies have evaluated HC responses from a regional perspective,partly due to the prerequisite of the Stokes MSF,which prevents us from integrating a regional HC.In this study,we adopt a recently developed technique to construct the three-dimensional structure of HC and evaluate the capability of eight state-of-the-art reanalyses in reproducing the regional HC response to ENSO events.Results show that all eight reanalyses reproduce the spatial structure of HC responses well,with an intensified HC around the central-eastern Pacific but weakened circulations around the Indo-Pacific warm pool and tropical Atlantic.The spatial correlation coefficient of the three-dimensional HC anomalies among the different datasets is always larger than 0.93.However,these datasets may not capture the amplitudes of the HC responses well.This uncertainty is especially large for ENSO-associated equatorially asymmetric HC anomalies,with the maximum amplitude in Climate Forecast System Reanalysis(CFSR)being about 2.7 times the minimum value in the Twentieth Century Reanalysis(20CR).One should be careful when using reanalysis data to evaluate the intensity of ENSO-associated HC anomalies.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(Grant No.52274009)China Postdoctoral Science Foundation(Grant No.2022M723501)Science and Technology Planning Project of Sichuan Province(Grant No.2021YJ0359).
文摘Lost circulation is a common downhole problem of drilling in geothermal and high-temperature,high-pressure(HTHP)formations.Lost circulation material(LCM)is a regular preventive and remedial measure for lost circulation.However,conventional LCMs seem ineffective in high-temperature formations.This may be due to the changes in the mechanical properties of LCMs and their sealing performance under high-temperature conditions.To understand how high temperature affects the fracture sealing performance of LCMs,we developed a coupled computational fluid dynamics-discrete element method(CFD-DEM)model to simulate the behavior of granular LCMs in fractures.We summarized the literature on the effects of high temperature on the mechanical properties of LCMs and the rheological properties of drilling fluid.We conducted sensitivity analyses to investigate how changing LCM slurry properties affected the fracture sealing efficiency at increasing temperatures.The results show that high temperature reduces the size,strength,and friction coefficient of LCMs as well as the drilling fluid viscosity.Smaller,softer,and less frictional LCM particles have lower bridging probability and slower bridging initiation.Smaller particles tend to form dual-particle bridges rather than single-particle bridges.These result in a deeper,tighter,but unstable sealing zone.Reduced drilling fluid viscosity leads to faster and shallower sealing zones.
文摘Objective:Patients with ductal-dependent pulmonary circulation require alternative bloodflow to provide and maintain adequate oxygenation.Modified Blalock-Taussig Shunt(MBTS)has been the standard for providing such a result.Currently,less invasive methods such as Arterial Duct(AD)stenting have been performed as alter-natives.This study aims to compare the outcome of AD stenting and MBTS.Method:Systematic research was performed in online databases using the PRISMA protocol.The outcomes measured were 30-day mortality,com-plication,unplanned intervention,oxygen saturation,duration of hospital,and ICU length of stay.Any compara-tive study provided with full text is included.The outcome of each study was analyzed using a trandom effects model with relative risk and mean difference as the effect size.Bias risk assessment was conducted using the New-castle-Ottawa Scale.All analyses were performed using Review Manager 5.4.1.Result:A total of 11 studies with 3154 samples included in this study.There is no significant difference in 30-day mortality between the two groups(p-value=0.10).However,there is significantly less complication(RR 0.53[0.35,0.82];p-value=0.004)and unplanned intervention(RR 0.59[0.38,0.92];p-value=0.02)in the AD stent group.Comparison of the Nakata index showed no significant difference(p-value=0.88).Post-operative oxygen saturation was measured signifi-cantly higher in the AD stenting(MD 1.80[0.85,2.74];p-value=0.0002).However,AD stent group shows sig-nificantly lower long-term oxygen saturation(MD-8.43[-14.38,-2.48];p-value=0.005).Both hospital and ICU length of stay was significantly shorter in the AD stent group(MD-8.30[-11.13,-5.48];p-value<0.00001;MD-5.09[-7.79,-2.38];p-value=0.0002).Conclusion:AD stenting provides comparable outcomes relative to MBTS as it provides less complication and unplanned intervention and higher post-procedural O2 saturation.However,MBTS proved its superiority in maintaining higher long-term oxygen saturation and still became the preferred option to manage complex cases where stenting is either challenging or unsuccessful.
基金supported by National Natural Science Foundation of China General Program (82172179)Mathematics Tianyuan Fund (12126604)Central High-level Hospital Clinical Research Project (2022-PUMCH-B-110)
文摘BACKGROUND:Unsustained return of spontaneous circulation(ROSC)is a critical barrier to survival in cardiac arrest patients.This study examined whether end-tidal carbon dioxide(ETCO_(2))and pulse oximetry photoplethysmogram(POP)parameters can be used to identify unsustained ROSC.METHODS:We conducted a multicenter observational prospective cohort study of consecutive patients with cardiac arrest from 2013 to 2014.Patients’general information,ETCO_(2),and POP parameters were collected and statistically analyzed.RESULTS:The included 105 ROSC episodes(from 80 cardiac arrest patients)comprised 51 sustained ROSC episodes and 54 unsustained ROSC episodes.The 24-hour survival rate was significantly higher in the sustained ROSC group than in the unsustained ROSC group(29.2%vs.9.4%,P<0.05).The logistic regression analysis showed that the difference between after and before ROSC in ETCO_(2)(ΔETCO_(2))and the difference between after and before ROCS in area under the curve of POP(ΔAUCp)were independently associated with sustained ROSC(odds ratio[OR]=0.931,95%confi dence interval[95%CI]0.881-0.984,P=0.011 and OR=0.998,95%CI 0.997-0.999,P<0.001).The area under the receiver operating characteristic curve ofΔETCO_(2),ΔAUCp,and the combination of both to predict unsustained ROSC were 0.752(95%CI 0.660-0.844),0.883(95%CI 0.818-0.948),and 0.902(95%CI 0.842-0.962),respectively.CONCLUSION:Patients with unsustained ROSC have a poor prognosis.The combination ofΔETCO_(2) andΔAUCp showed signifi cant predictive value for unsustained ROSC.
文摘Aim: To explore the application effect of external diaphragm pacemaker combined with active respiratory circulation technology in pulmonary rehabilitation of perioperative lung cancer patients. Methods: A total of 98 lung cancer patients admitted to our hospital from April 2020 to November 2021 were selected as the observation objects, and then divided into a control group and an observation group using the random number table method, with 49 cases in each group. The control group received routine admission guidance and active respiratory circulation training, while the observation group was supplemented with external diaphragm pacemaker on the basis of the control group. The intervention effect was evaluated by blood gas indicators, pulmonary function indicators, diaphragm function indicators, sputum comfort degree, and activity tolerance indicators before and after intervention. Results: Before intervention, there were no significant differences in blood gas analysis indicators, pulmonary function indicators, diaphragm function indicators, sputum comfort degree, and activity tolerance indicators between the two groups (P > 0.05). After intervention, the improvement degree of the above indicators in the observation group was higher than that in the control group (P < 0.05). Conclusions: The application of external diaphragm pacemaker combined with active respiratory circulation technology in pulmonary rehabilitation of perioperative lung cancer patients is significant, which can effectively improve the pulmonary function, blood gas function, and diaphragm function of lung cancer patients after surgery, and improve the activities of daily living and quality of life of patients.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA19060102)the National Natural Science Foundation of China(Nos.91958201,42130608)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB42000000)。
文摘Atlantic meridional overturning circulation(AMOC)plays an important role in transporting heat meridionally in the Earth’s climate system and is also a key metrical tool to verify oceanic general circulation models.Two OMIP(Ocean Model Intercomparison Project phase 1 and 2)simulations with LICOM3(version 3 of the LASG/IAP Climate System Ocean Model)developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG),Institute of Atmospheric Physics(IAP),are compared in this study.Both simulations well reproduce the fundamental characteristics of the AMOC,but the OMIP1 simulation shows a significantly stronger AMOC than the OMIP2 simulation.Because the LICOM3 configurations are identical between these two experiments,any differences between them must be attributed to the surface forcing data.Further analysis suggests that sea surface salinity(SSS)differences should be mainly responsible for the enhanced AMOC in the OMIP1 simulation,but sea surface temperature(SST)also play an unignorable role in modulating AMOC.In the North Atlantic,where deep convection occurs,the SSS in OMIP1 is more saline than that in OMIP1.We find that in the major region of deep convection,the change of SSS has more significant effect on density than the change of SST.As a result,the SSS was more saline than that in OMIP2,leading to stronger deep convection and subsequently intensify the AMOC.We conduct a series of numerical experiments with LICOM3,and the results confirmed that the changes in SSS have more significant effect on the strength of AMOC than the changes in SST.
文摘This is an erratum to an already published paper named“Establishment of a prediction model for prehospital return of spontaneous circulation in out-ofhospital patients with cardiac arrest”.We found errors in the affiliated institution of the authors.We apologize for our unintentional mistake.Please note,these changes do not affect our results.
基金Key Project of Joint Meteorological Fund of the National Natural Science Foundation of China (U2242202)Key Project of the National Natural Science Foundation of China (42030611)+1 种基金Innovative Development Special Project of China Meteorological Administration (CXFZ2023J016)Innovation Team Fund of Sichuan Provincial Meteorological Service (SCQXCX7D-202201)。
文摘Based on ERA5 reanalysis data,the present study analyzed the thermal energy development mechanism and kinetic energy conversion characteristics of two extreme rainstorm processes in relation to the shallow southwest vortex in the warm-sector during a“rain-generated vortex”process and the deep southwest vortex in a“vortex-generated rain”process.The findings were as follows:(1)During the extreme rainstorm on August 11,2020(hereinafter referred to as the“8·11”process),intense surface heating and a high-energy unstable environment were observed.The mesoscale convergence system triggered convection to produce heavy rainfall,and the release of latent condensation heat generated by the rainfall promoted the formation of a southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy preceded the increase(decrease)in vorticity.By contrast,the extreme rainstorm on August 16,2020(hereinafter referred to as the“8·16”process)involved the generation of southwest vortex in a low-energy and highhumidity environment.The dynamic uplift of the southwest vortex triggered rainfall,and the release of condensation latent heat from rainfall further strengthened the development of the southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy exhibited a delayed progression compared to the increase(decrease)in vorticity.(2)The heating effect around the southwest vortex region was non-uniform,and the heating intensity varied in different stages.In the“8·11”process,the heating effect was the strongest in the initial stage,but weakened during the vortex's development.On the contrary,the heating effect was initially weak in the“8·16”process,and intensified during the development stage.(3)The available potential energy of the“8·11”process significantly increased in kinetic energy converted from rotational and divergent winds through baroclinic action,and the divergent wind energy continued to convert into rotational wind energy.By contrast,the“8·16”process involved the conversion of rotational wind energy into divergent wind energy,which in turn converted kinetic energy back into available potential energy,thereby impeding the further development and maintenance of the southwest vortex.
文摘This study investigates the relationship between circulation patterns and austral summer temperature anomalies in southern Africa. The results show that the formation of continental lows tends to increase the thickness of the lower atmosphere. Further, the distinct variabilities of high and low pressure under the circulation types, influence air mass advection from the adjacent oceans, as well as atmospheric stability over land. Stronger anticyclonic circulation at the western branch of the Mascarene high-pressure system enhances the low-level cold air advection by southeast winds,decreases the thickness, and lowers the temperature over a majority of the land in southern Africa. Conversely, a weaker Mascarene High, coupled with enhanced cyclonic activity in the southwest Indian Ocean increases low-level warm air advection and increases temperature anomalies over vast regions in southern Africa. The ridging of a closed South Atlantic anticyclone at the southern coast of southern Africa results in colder temperatures near the tip of southern Africa due to enhanced low-level cold air advection by southeast winds. However, when the ridge is weak and westerly winds dominate the southern coast of southern Africa, these areas experience temperature increases. The northward track of the Southern Hemisphere mid-latitude cyclone, which can be linked to the negative Southern Annular Mode, reduces the temperature in the southwestern part of southern Africa. Also, during the analysis period, El Ni?o was associated with temperature increases over the central parts of southern Africa;while the positive Indian Ocean dipole was linked to a temperature increase over the northeastern, northwestern, and southwestern parts of southern Africa.
基金Under the auspices of National Natural Science Foundation of China(No.52279016,51909106,51879108,42002247,41471160)Natural Science Foundation of Guangdong Province,China(No.2020A1515011038,2020A1515111054)+1 种基金Special Fund for Science and Technology Development in 2016 of Department of Science and Technology of Guangdong Province,China(No.2016A020223007)the Project of Jinan Science and Technology Bureau(No.2021GXRC070)。
文摘Huaihe River Basin(HRB) is located in China’s north-south climatic transition zone,which is very sensitive to global climate change.Based on the daily maximum temperature,minimum temperature,and precipitation data of 40 meteorological stations and nine monthly large-scale ocean-atmospheric circulation indices data during 1959–2019,we present an assessment of the spatial and temporal variations of extreme temperature and precipitation events in the HRB using nine extreme climate indices,and analyze the teleconnection relationship between extreme climate indices and large-scale ocean-atmospheric circulation indices.The results show that warm extreme indices show a significant(P < 0.05) increasing trend,while cold extreme indices(except for cold spell duration) and diurnal temperature range(DTR) show a significant decreasing trend.Furthermore,all extreme temperature indices show significant mutations during 1959-2019.Spatially,a stronger warming trend occurs in eastern HRB than western HRB,while maximum 5-d precipitation(Rx5day) and rainstorm days(R25) show an increasing trend in the southern,central,and northwestern regions of HRB.Arctic oscillation(AO),Atlantic multidecadal oscillation(AMO),and East Atlantic/Western Russia(EA/WR) have a stronger correlation with extreme climate indices compared to other circulation indices.AO and AMO(EA/WR) exhibit a significant(P < 0.05) negative(positive)correlation with frost days and diurnal temperature range.Extreme warm events are strongly correlated with the variability of AMO and EA/WR in most parts of HRB,while extreme cold events are closely related to the variability of AO and AMO in eastern HRB.In contrast,AMO,AO,and EA/WR show limited impacts on extreme precipitation events in most parts of HRB.
基金This work was possible through the financing of PEC-20480 Project between Royal Dutch Shell(Shell)and the Laboratório de Métodos Computacionais em Engenharia(LAMCE)and through the doctoral fellowship funding by CNPq for Elisa Passos Case number 141819/2016-2the postdoctoral fellowship funding by FAPERJ E 10/2020-Edital Inteligência Artificial Case Number E-26/203.327/2022-Enrollment No.Scholarship 2015.08297.7 for Lívia Sancho.
文摘The Atlantic Meridional Overturning Circulation(AMOC)is a crucial component of the Earth’s climate system due to its fundamental role in heat distribution,carbon and oxygen transport,and the weather.Other climate components,such as the atmosphere and sea ice,influence the AMOC.Evaluating the physical mechanisms of those interactions is paramount to increasing knowledge about AMOC’s functioning.In this study,the authors used outputs from the Community Earth System Model version 2 and observational data to investigate changes in theAMOC and the associated physical processes.Two DECK experiments were evaluated:piControl and 1pctCO_(2),with an annual increase of 1%of atmospheric CO_(2).The analysis revealed a significant decrease in the AMOC,associated with changes in mixed layer depth and buoyancy in high latitudes of the North Atlantic,resulting in the shutdown of deep convection and potentially affecting the formation of North Atlantic Deep Water and Antarctic Bottom Water.A vital aspect observed in this study is the association between increased runoff and reduced water evaporation,giving rise to a positive feedback process.Consequently,the rates of freshwater spreading have intensified during this period,which could lead to an accelerated disruption of the AMOC beyond the projections of existing models.
基金supported by the National Natural Science Foundation of China[grant number 42025502]the Guangdong Major Project of Basic and Applied Basic Research[grant number 2020B0301030004].
基金supported by the Chinese Academy of Sciences key program under Grant KZCX3-SW-221the National Natural Science Foundation of China under Grant Nos.40620130113 and 40475037.
文摘The long-term relationship between the tree-ring-reconstructed annual precipitation in northeastern Mongolia (PRM) and the Northern Hemisphere Zonal Circulation (NHZC), defined as the normalized zonal mean sea-level pressure at 60°N in May-June-July, is examined in this study. A significant correlation coefficient (0.31) was found between the NHZC indices and PRM based on the dataset for the period of 1872-1995. The mechanisms responsible for the relationship are discussed through analyses of the atmospheric general circulation variability associated with NHZC. It follows that NHZC-related atmospheric circulation variability provides an anomalous southeast flow from the ocean to Northeast Mongolia (northwest flow from Northeast Mongolia to the ocean) in the middle and low troposphere in positive (negative) phase of NHZC, resulting in more (less) water vapor transport to the target region and more (less) precipitation in Northeast Mongolia.
基金The CAS/SAFEA International Partnership Program for Creative Research Teams of Chinese Academy of Sciencesthe National Natural Science Foundation of China under contract Nos 41422601,41376024 and 41376025
文摘Zonal overturning circulation (ZOC) and its associated zonal heat flux (ZHF) are important components of the oceanic circulation and climate system, although these conceptions have not received adequate attentions. Heaving induced by inter-annual and decadal wind stress perturbations can give rise to anomalous ZOC and ZHF. Based on a simple reduced gravity model, the anomalous ZOC and ZHF induced by idealized heaving modes in the world oceans are studied. For example, in a Pacific-like model basin intensified equatorial easterly on decadal time scales can lead to a negative ZOC with a non-negligible magnitude (-0.3×10^6 m^3/s) and a considerable westward ZHF with an amplitude of -11.2 TW. Thus, anomalous ZOC and ZHF may consist of a major part of climate signals on decadal time scales and thus play an important role in the oceanic circulation and climate change.
基金jointly supported by the R&D Special Fund for Public Welfare Industry(meteorology)of China(Grant No.GYHY201306031)the National Natural Science Foundation of China(Grant No.40905040)the National Science Foundation of United States(Grant No.1107509)
文摘This paper examines the dominant submonthly variability of zonally symmetrical atmospheric circula- tion in the Northern Hemisphere (NH) winter within the context of the Northern Annular Mode (NAM), with particular emphasis on interactive stratosphere-troposphere processes. The submonthly variability is identified and measured using a daily NAM index, which concentrates primarily on zonally symmetrical circulation. A schematic lifecycle of submonthly variability is developed that reveals a two-way coupling pro- cess between the stratosphere and troposphere in the NH polar region. Specifically, anomalous tropospheric zonal winds in the Atlantic and Pacific sectors of the Arctic propagate upwards to the low stratosphere, disturbing the polar vortex, and resulting in an anomalous stratospheric geopotential height (HGT) that subsequently propagates down into the troposphere and changes the sign of the surface circulations. From the standpoint of planetary-scale wave activities, a feedback loop is also evident when the anoma- lous planetary-scale waves (with wavenumbers 2 and 3) propagate upwards, which disturbs the anomalous zonally symmetrical flow in the low stratosphere, and induces the anomalous HGT to move poleward in the low stratosphere, and then propagates down into the troposphere. This increases the energy of waves at wavenumbers 2 and 3 in the low troposphere in middle latitudes by enhancing the land-sea contrast of the anomalous HGT field. Thus, this study supports the viewpoint that the downward propagation of stratospheric NAM signals may not originate in the stratosphere.
文摘A discussion of the mass transport of the Hadley circulation is presented, with regard to its longitudinal structure. Data from the NCEP/NCAR reanalysis data set for the period 1948-2005 is examined, focusing on the solsticial seasons of June-August and December-February. Quantitative estimates have been extracted from the data to observe connections between the zonal mean of the upper tropospheric north/south mass transports and their relationship to the driving factor of tropical precipitation (implying latent heat release) and subsidence in the subtropical high pressure belts. The longitudinal structure of this flow is then examined with regard to these three main variables. The poleward upper tropospheric transport has four (JJA) or three (DJF) main branches, which link regions of major precipitation with corresponding regions of large subsidence, and one (June, July, August) or two (December, January, February) reverse branches. This structure has remained stable over the past sixty years. Although the total upper tropospheric transport in each season is less than the total sinking transport in the target subtropical high pressure belt, this does not apply to the individual branches, the balance being made up by the upper tropospheric reverse transports. An analysis of correlations between all of these various components shows, however, that the complete picture is more complex, with some precipitation regions being linked to subsidence regions outside their own branch.
基金supported by the National Natural Science Foundation of China(Grant No.41975008)Key Laboratory of South China Sea Meteorological Disaster Prevention and Mitigation of Hainan Province(Grant No.SCSF201906)。
文摘This study reveals a significant positive connection between autumn non-tropical-cyclone heavy rainfall on Hainan Island and the intensity of Eastern Pacific(EP)El Ni?o events.That is,the amount of rainfall in super EP El Ni?o years is more than that in normal EP El Ni?o years.Comparing EP El Ni?o years of different intensities,the cooler sea surface temperature in the northwestern Pacific during super EP El Ni?o years stimulates a negative surface latent heat flux(LHF)anomaly and abnormal anticyclonic circulation at 850 hPa.Under these conditions,an abnormal zonal vertical circulation develops in the northern South China Sea once a positive LHF anomaly and abnormal cyclonic circulation(ACC)at 850hPa occur in the Beibu Gulf.The abnormal zonal vertical circulation further strengthens the ascending motion over Hainan Island,as the critical factor that leads to excessive rainfall.Further analysis shows that the positive LHF anomaly,which can be attributed to the increased latent heat transfer which resulted from the increased surface wind speed,is an important trigger for the ACC.However,the ACC is also the supplier of favorable moisture conditions because it intensifies vapor convergence over Hainan Island and meridionally transports moisture from the South China Sea to northeastern Hainan Island,thereby generating heavy rainfall.This paper emphasizes that the impact of El Ni?o events,especially super El Ni?o events,on rainfall over Hainan Island cannot be ignored,even if the traditional view is that frequent rainfall occurs mainly in La Ni?a years.
基金National Natural Science Foundation of China(91537214,41275079,41305077,41405069)
文摘The abrupt changes of zonal circulation in the Tibetan Plateau(TP) region and their likely causes are derived from National Centers for Environmental Prediction and the National Center for Atmospheric Research reanalysis data.The zonal circulation over the TP abruptly changed in summer(31st pentad) and winter(59th pentad).The switch from summer to winter circulation is characterized by a sudden northward shift of the westerlies and the zero-velocity curve and disappearance of the westerly jet.The winter-summer switch is characterized by the reverse pattern.Therefore,the circulation conversion between summer and winter can be judged from the position of the zero-velocity curve.Curves located north of 20 °N indicate summer circulation over the TP and vice versa.The abrupt change of zonal circulation is mainly caused by the thermodynamic effect of the TP.In June,this effect causes a huge monsoon circulation cell extending from the TP to low latitudes.Consequently,the westerlies jump to the north as easterlies develop.This process,which is enhanced by the strong northerly in Coriolis,establishes the summer circulation.In October,the Hadley cell recurs as the thermal effects of the TP diminish,the westerlies rush southward,and the winter circulation is established.
基金supported by the Chinese Youth 1000 Talents Program and the Open Project of the State Key Laboratory of Planetary Sciences, Macao University of Science and Technologysupported by the Science and Technology Facilities Council grant ST/R000891/1by the Macao Science and Technology Development Fund grants (007/2016/A1 and 001/2016/AFJ)
文摘To infer the internal equilibrium structure of a gaseous planet, especially the equation of state(EOS) and size of its inner core,requires accurate determination of lower-order zonal gravitational coefficients. Modeling of the gravitational signature associated with deep zonal circulation depends critically upon reliable subtraction of the dynamical components from totally derived gravitational coefficients. In the era of the Juno mission and the Grand Finale phase of the Cassini mission, it is timely and necessary to revisit and examine the so-called ‘Thermal Wind Equation(TWE)’, which has been extensively utilized to diagnose the dynamical parts of the gravitational fields measured by the two spacecrafts. TWE treats as negligible a few terms in the full equation of balance. However, the self-gravitational anomaly of the distorted fluid, unlike oblateness effects of solid-body rotation, is not a priori minor and thus should not be neglected in the name of approximation. Another equation, the ‘Thermal Gravitational Wind Equation(TGWE)’, includes this important additional term;we compare it with the TWE and show that physically the TGWE models a fundamentally different balance from the TWE and delivers numerical results considerably different from models based on the TWE. We conclude that the TWE balance cannot be relied upon to produce realistic convection models. Only after the TGWE balance is obtained can the relative importance of terms be assessed.The calculations we report here are based on two types of zonal circulations that are produced by realistically possible convections inside planets, instead of being constructed or assumed.