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
An ocean-atmosphere and land-air coupled numerical model system is used to study the basic properties and the monthly time variations of the summer quasi-stationary circulation systems. It is found that either at the ...An ocean-atmosphere and land-air coupled numerical model system is used to study the basic properties and the monthly time variations of the summer quasi-stationary circulation systems. It is found that either at the upper or at the lower levels of the atmosphere, the circulation patterns have a two-wave structure in the zonal direction at the mid and high latitudes of the Northern Hemisphere. Such a structure of circulation is totally matchable to that of the land-sea distribution there. It is proved, hence, that the land-sea distributive pattern is the fundamental cause for the summer quasi-stationary circulation pattern. The topography in the globe is the secondary factor for circulation systems. The circulation centres of the quasi-stationary systems are always located in certain areas due to the thermodynamic contrast between land and sea.From the time evolutions of the circulation systems it is seen that the change is larger at the beginning period of the time integration, it is because of using the zonally averaged mean fields as the initial values of the model. As long as the basic simulated pattern of circulations reaches the state similar to that of the real climatic fields resulting from the coeffects of the land-sea distribution and the topography, the circulation systems modelled will change slowly and tend to a quasi-stationary state. Therefore, the time integration does not need to last for a very long time, if the purpose of numerical modellings is to test sensitivities of some factors influencing the climate, 20 model days may be enough for sensitive experiments.展开更多
This paper aims to demonstrate some characteristics of the 20-50 day oscillations of certain circulation systems in low latitudes during the northern summer seasons.The teleconnection between the variations of the Mas...This paper aims to demonstrate some characteristics of the 20-50 day oscillations of certain circulation systems in low latitudes during the northern summer seasons.The teleconnection between the variations of the Mascarene high and the Northwest Pacific high and its physical mechanism are studied.How the Mas- carene high plays an important role in the interaction between the atmospheric circulations of both hemispheres is discussed.展开更多
The Yangtze-Huaihe River Valley(YHRV)experienced a record-breaking mei-yu season during the summer of 2020,prompting investigation into the role of regional ocean-atmosphere coupling in simulating this extreme event.T...The Yangtze-Huaihe River Valley(YHRV)experienced a record-breaking mei-yu season during the summer of 2020,prompting investigation into the role of regional ocean-atmosphere coupling in simulating this extreme event.Through comparative analysis of regional ocean-atmosphere coupled(CP)and atmosphere-only(WRF)simulations,the aim of this study was to elucidate the mechanisms underlying this phenomenon.Results indicate that CP effectively reproduced the observed sea surface temperature spatial distribution and its daily variation during the period from 25 June to 25 July 2020,and notably reduced the wet biases over the YHRV when compared to WRF simulations.This improvement in representation was manifested in the observed rainfall spatial distribution and daily variability.The wet biases simulated by WRF were associated with a stronger 200-hPa westerly jet and a more westward-positioned western North Pacific subtropical high(WNPSH)with more intense 500-hPa winds and a stronger 850-hPa circulation.However,these biases were significantly reduced in CP simulations.Mechanism analysis revealed that regional ocean-atmosphere coupling over the western Northwest Pacific influenced surface turbulent heat fluxes and atmospheric instability,thereby modulating the intensity and position of the WNPSH and associated circulation subsystems at different levels.Moreover,adjustments in land-sea thermal contrast induced by ocean-atmosphere coupling impacted YHRV precipitation by altering East Asian circulation systems.These findings highlight the significant role of regional ocean-atmosphere coupling in enhancing the simulation and understanding of extreme mei-yu events over East Asia.展开更多
Background:The benefits of exercise are well known;however,many of the underlying molecular mechanisms are not fully understood.Skeletal muscle secretes myokines,which mediate muscleorgan crosstalk.Myokines regulate s...Background:The benefits of exercise are well known;however,many of the underlying molecular mechanisms are not fully understood.Skeletal muscle secretes myokines,which mediate muscleorgan crosstalk.Myokines regulate satellite-cell proliferation and migration,inflammatory cascade,insulin secretion,angiogenesis,fatty oxidation,and cancer suppression.To date,the effects of different exercise modes(namely,aerobic and resistance exercise)on myokine response remain to be elucidated.This is crucial considering the clinical implementation of exercise to enhance general health and wellbeing and as a medical treatment.Methods:A systematic search was undertaken in PubMed,MEDLINE,CINAHL,Embase,SPORTDiscus,andWeb of Science in April 2023.Eligible studies examining the effects of a single bout of exercise on interleukin15(IL-15),irisin,secreted protein acidic and rich in cysteine(SPARC),oncostatinM(OSM),and decorin were included.A random-effects meta-analysis was also undertaken to quantify the magnitude of change.Results:Sixty-two studies were included(n=1193).Overall,exercise appeared to induce small to large increases in myokine expression,with effects observed immediately after to 60 min post-exercise,although these were mostly not statistically significant.Both aerobic and resistance exercise resulted in changes in myokine levels,without any significant difference between training modes,and with the magnitude of change differing across myokines.Myokine levels returned to baseline levels within 180 min to 24 h post-exercise.However,owing to potential sources of heterogeneity,most changes were not statistically significant,indicating that precise conclusions cannot be drawn.Conclusion:Knowledge is limited but expanding with respect to the impact of overall and specific effects of exercise on myokine expression at different time points in the systemic circulation.Further research is required to investigate the effects of different exercise modes at multiple time points on myokine response.展开更多
In addition to complications relating to the liver, patients with cirrhosis and portal hypertension develop extrahepatic functional disturbances of multiple organ systems. This can be considered a multiple organ failu...In addition to complications relating to the liver, patients with cirrhosis and portal hypertension develop extrahepatic functional disturbances of multiple organ systems. This can be considered a multiple organ failure that involves the heart, lungs, kidneys, the immune systems, and other organ systems. Progressive fibrosis of the liver and subsequent metabolic impairment leads to a systemic and splanchnic arteriolar vasodilatation. This affects both the haemodynamic and functional homeostasis of many organs and largely determines the course of the disease. With the progression of the disease, the circulation becomes hyperdynamic with cardiac, pulmonary as well as renal consequences for dysfunction and reduced survival. Infections and a changed cardiac function known as cirrhotic cardiomyopathy may be involved in further aggravation of other complications such as renal failure precipitatingthe hepatorenal syndrome.Patients with end-stage liver disease and related complications as for example the hepatopulmonary syndrome can only radically be treated by liver transplantation.As a bridge to this treatment,knowledge on the mechanisms of the pathophysiology of complications is essential for the choice of vasoactive drugs,antibiotics,drugs with specific effects on fibrogenesis and inflammation,and drugs that target specific receptors.展开更多
Mesenchymal stromal cells(MSCs) are adult multipotent stem cells residing as pericytes in various tissues and organs where they can differentiate into specialized cells to replace dying cells and damaged tissues. Thes...Mesenchymal stromal cells(MSCs) are adult multipotent stem cells residing as pericytes in various tissues and organs where they can differentiate into specialized cells to replace dying cells and damaged tissues. These cells are commonly found at injury sites and in tumors that are known to behave like "wounds that do not heal." In this article, we discuss the mechanisms of MSCs in migrating, homing, and repairing injured tissues. We also review a number of reports showing that tumor microenvironment triggers plasticity mechanisms in MSCs to induce malignant neoplastic tissue formation, maintenance, and chemoresistance, as well as tumor growth. The antitumor properties and therapeutic potential of MSCs are also discussed.展开更多
The effects of 3,4-DHAP on hypoxic pulmonary and systemic vascular responses were studied in anaesthetized dogs. The percentage change in pulmonary vascular resistance(△PVR%)and that in systemic vascular resistance(...The effects of 3,4-DHAP on hypoxic pulmonary and systemic vascular responses were studied in anaesthetized dogs. The percentage change in pulmonary vascular resistance(△PVR%)and that in systemic vascular resistance(△SVR%)induced by 5 min hypoxia decreased significantly.3,4-DHAP in doses of 1 mg/kg,3mg/kg,and 10 mg/kg i.v caused a decrease in b PVR% from the control value of 47.27±22.27% to 24.62±21.76%,18.15±18.73%,and 24.10±19.76% respectively, and a decrease in △SVR% from the control value of 12.91±7.39% to -0.34±12.7%,-2.11±12.76%,and -2.37±15.52% respectively.The results showed that 3,4-DHAP could decrease the hypoxic responses of pulmonary and systemic blood vessels.But it did not change △PVR% or △SVR% in dose of 30mg/kg,neither did it influence the heart rate,cardiac output or cerebral blood flow during hypoxia in all the doses used.展开更多
We diagnose characteristics of the quasi-balanced flow and secondary circulation（SC） of tropical storm Bilis（2006） using the potential vorticity（PV）-ω inversion method.We further analyze how secondary steering ...We diagnose characteristics of the quasi-balanced flow and secondary circulation（SC） of tropical storm Bilis（2006） using the potential vorticity（PV）-ω inversion method.We further analyze how secondary steering flows associated with mesoscale convective systems affected the track of tropical storm Bilis after it made landfall.The quasi-balanced asymmetric and axisymmetric circulation structures of tropical storm Bilis are represented well by the PV-w inversion.The magnitude of the nonlinear quasi-balanced vertical velocity is approximately 75%of the magnitude simulated using the Weather Research and Forecasting（WRF） model.The SC of Bilis（2006） contained two strong regions of ascending motion,both of which were located in the southwest quadrant of the storm.The first（150-200 km southwest of the storm center） corresponded to the eyewall region,while the second（approximately 400 km southwest of the storm center） corresponded to latent heat release associated with strong precipitation in major spiral rainbands.The SC was very weak in the northeast quadrant（the upshear direction）.Dynamical processes related to the environmental vertical wind shear produced an SC that partially offset the destructive effects of the environmental vertical wind shear（by 20%-25%）.This SC consisted of upward motion in the southwest quadrant and subsidence in the northeast quadrant,with airflow oriented from southwest to northeast at high altitudes and from northeast to southwest at lower levels.The inverted secondary zonal and meridional steering flows associated with continuous asymmetric mesoscale convective systems were about-2.14 and-0.7 m s^（-1）,respectively.These steering flows contributed substantially to the zonal（66.15%） and meridional（33.98%） motion of the storm at 0000 UTC15 July 2006.The secondary steering flow had a significant influence on changing the track of Bilis from southward to northward.The direction of the large-scale meridional steering flow（3.02 m s^（-1）） was opposite to the actual meridional motion（-2.06 m s^（-1））.展开更多
This study investigates influencing weather systems for and the effect of Tibetan Plateau （TP）’s surface heating on the heavy rainfall over southern China in June 2010, focusing on the four persistent heavy rainfal...This study investigates influencing weather systems for and the effect of Tibetan Plateau （TP）’s surface heating on the heavy rainfall over southern China in June 2010, focusing on the four persistent heavy rainfall events during 14-24 June 2010. The ma jor weather systems include the South Asian high, midlatitude trough and ridge, western Pacific subtropical high in the middle troposphere, and shear lines and eastward-moving vortices in the lower troposphere. An ensemble of convection-permitting simulations （CTL） is carried out with the WRF model for these rainfall events, which successfully reproduce the observed evolution of precipitation and weather systems. Another ensemble of simulations （SEN） with the surface albedo over the TP and its southern slope changed artificially to one, i.e., the surface does not absorb any solar heating, otherwise it is identical to CTL, is also performed. Comparison between CTL and SEN suggests that the surface sensible heating of TP in CTL significantly affects the temperature distributions over the plateau and its surroundings, and the thermal wind adjustment consequently changes atmospheric circulations and properties of the synoptic systems, leading to intensified precipitation over southern China. Specifically, at 200 hPa, anticyclonic and cyclonic anomalies form over the western and eastern plateau, respectively, which enhances the southward cold air intrusion along the eastern TP and the divergence over southern China;at 500 hPa, the ridge over the northern plateau and the trough over eastern China are strengthened, the southwesterly flows along the northwestern side of the subtropical high are intensified, and the positive vorticity propagation from the plateau to its downstream is also enhanced significantly;at 850 hPa, the low-pressure vortices strongly develop and move eastward while the southwesterly low-level jet over southern China strengthens in CTL, leading to increased water vapor convergence and upward motion over the precipitation region.展开更多
The basic theme of this work is to identify the optimal measurement locations for pres- sure and flow in the systemic circulation to detect aortic stenoses and aneurysms in early stages of a disease. For this purpose,...The basic theme of this work is to identify the optimal measurement locations for pres- sure and flow in the systemic circulation to detect aortic stenoses and aneurysms in early stages of a disease. For this purpose, a linear elastic lumped parameter model of the fluid dynamical simulator, major arterial cardiovascular simulator （MACSim）, is considered and global sensitivity analysis is applied to identify the better measurement locations for pressure and flow in the systemic circulation. The obtained results of sensitivity analysis provide insight that enable the experimentalists to optimize their experimental setups for detecting aortic stenoses and aneurysms using parameter estimation process. From the results, it is observed that the stenosis in the thoracic aorta can be identified from both pressure and flow at the location itself, nearby nodes, aorta ascendens, arcus aorta, arteria subclavia and arteria axillaris. On the other hand, the preferable measurement locations for abdominal aneurysms are locations themselves, nearby nodes and left/right leg of the body.展开更多
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Supported by National Fundamental Key Research Project:"Studies on dynamic climate and climate prediction theory".
文摘An ocean-atmosphere and land-air coupled numerical model system is used to study the basic properties and the monthly time variations of the summer quasi-stationary circulation systems. It is found that either at the upper or at the lower levels of the atmosphere, the circulation patterns have a two-wave structure in the zonal direction at the mid and high latitudes of the Northern Hemisphere. Such a structure of circulation is totally matchable to that of the land-sea distribution there. It is proved, hence, that the land-sea distributive pattern is the fundamental cause for the summer quasi-stationary circulation pattern. The topography in the globe is the secondary factor for circulation systems. The circulation centres of the quasi-stationary systems are always located in certain areas due to the thermodynamic contrast between land and sea.From the time evolutions of the circulation systems it is seen that the change is larger at the beginning period of the time integration, it is because of using the zonally averaged mean fields as the initial values of the model. As long as the basic simulated pattern of circulations reaches the state similar to that of the real climatic fields resulting from the coeffects of the land-sea distribution and the topography, the circulation systems modelled will change slowly and tend to a quasi-stationary state. Therefore, the time integration does not need to last for a very long time, if the purpose of numerical modellings is to test sensitivities of some factors influencing the climate, 20 model days may be enough for sensitive experiments.
文摘This paper aims to demonstrate some characteristics of the 20-50 day oscillations of certain circulation systems in low latitudes during the northern summer seasons.The teleconnection between the variations of the Mascarene high and the Northwest Pacific high and its physical mechanism are studied.How the Mas- carene high plays an important role in the interaction between the atmospheric circulations of both hemispheres is discussed.
基金the National Key Scientific and Technological Infrastructure project “Earth System Science Numerical Simulator Facility (EarthLab)” for its support of our studyjointly supported by the National Key Research and Development Program of China (Grant No. 2023YFF0805501)+2 种基金the Key Laboratory of Meteorological Disaster (KLME) of the Ministry of Education, and the Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD) at Nanjing University of Information Science & Technology, Nanjing, China (Grant No. KLME202204)the NSFC program (42141017)support from the China Scholarship Council.
文摘The Yangtze-Huaihe River Valley(YHRV)experienced a record-breaking mei-yu season during the summer of 2020,prompting investigation into the role of regional ocean-atmosphere coupling in simulating this extreme event.Through comparative analysis of regional ocean-atmosphere coupled(CP)and atmosphere-only(WRF)simulations,the aim of this study was to elucidate the mechanisms underlying this phenomenon.Results indicate that CP effectively reproduced the observed sea surface temperature spatial distribution and its daily variation during the period from 25 June to 25 July 2020,and notably reduced the wet biases over the YHRV when compared to WRF simulations.This improvement in representation was manifested in the observed rainfall spatial distribution and daily variability.The wet biases simulated by WRF were associated with a stronger 200-hPa westerly jet and a more westward-positioned western North Pacific subtropical high(WNPSH)with more intense 500-hPa winds and a stronger 850-hPa circulation.However,these biases were significantly reduced in CP simulations.Mechanism analysis revealed that regional ocean-atmosphere coupling over the western Northwest Pacific influenced surface turbulent heat fluxes and atmospheric instability,thereby modulating the intensity and position of the WNPSH and associated circulation subsystems at different levels.Moreover,adjustments in land-sea thermal contrast induced by ocean-atmosphere coupling impacted YHRV precipitation by altering East Asian circulation systems.These findings highlight the significant role of regional ocean-atmosphere coupling in enhancing the simulation and understanding of extreme mei-yu events over East Asia.
文摘Background:The benefits of exercise are well known;however,many of the underlying molecular mechanisms are not fully understood.Skeletal muscle secretes myokines,which mediate muscleorgan crosstalk.Myokines regulate satellite-cell proliferation and migration,inflammatory cascade,insulin secretion,angiogenesis,fatty oxidation,and cancer suppression.To date,the effects of different exercise modes(namely,aerobic and resistance exercise)on myokine response remain to be elucidated.This is crucial considering the clinical implementation of exercise to enhance general health and wellbeing and as a medical treatment.Methods:A systematic search was undertaken in PubMed,MEDLINE,CINAHL,Embase,SPORTDiscus,andWeb of Science in April 2023.Eligible studies examining the effects of a single bout of exercise on interleukin15(IL-15),irisin,secreted protein acidic and rich in cysteine(SPARC),oncostatinM(OSM),and decorin were included.A random-effects meta-analysis was also undertaken to quantify the magnitude of change.Results:Sixty-two studies were included(n=1193).Overall,exercise appeared to induce small to large increases in myokine expression,with effects observed immediately after to 60 min post-exercise,although these were mostly not statistically significant.Both aerobic and resistance exercise resulted in changes in myokine levels,without any significant difference between training modes,and with the magnitude of change differing across myokines.Myokine levels returned to baseline levels within 180 min to 24 h post-exercise.However,owing to potential sources of heterogeneity,most changes were not statistically significant,indicating that precise conclusions cannot be drawn.Conclusion:Knowledge is limited but expanding with respect to the impact of overall and specific effects of exercise on myokine expression at different time points in the systemic circulation.Further research is required to investigate the effects of different exercise modes at multiple time points on myokine response.
基金Supported by Novo Nordisk Foundation and the University of Copenhagen
文摘In addition to complications relating to the liver, patients with cirrhosis and portal hypertension develop extrahepatic functional disturbances of multiple organ systems. This can be considered a multiple organ failure that involves the heart, lungs, kidneys, the immune systems, and other organ systems. Progressive fibrosis of the liver and subsequent metabolic impairment leads to a systemic and splanchnic arteriolar vasodilatation. This affects both the haemodynamic and functional homeostasis of many organs and largely determines the course of the disease. With the progression of the disease, the circulation becomes hyperdynamic with cardiac, pulmonary as well as renal consequences for dysfunction and reduced survival. Infections and a changed cardiac function known as cirrhotic cardiomyopathy may be involved in further aggravation of other complications such as renal failure precipitatingthe hepatorenal syndrome.Patients with end-stage liver disease and related complications as for example the hepatopulmonary syndrome can only radically be treated by liver transplantation.As a bridge to this treatment,knowledge on the mechanisms of the pathophysiology of complications is essential for the choice of vasoactive drugs,antibiotics,drugs with specific effects on fibrogenesis and inflammation,and drugs that target specific receptors.
文摘Mesenchymal stromal cells(MSCs) are adult multipotent stem cells residing as pericytes in various tissues and organs where they can differentiate into specialized cells to replace dying cells and damaged tissues. These cells are commonly found at injury sites and in tumors that are known to behave like "wounds that do not heal." In this article, we discuss the mechanisms of MSCs in migrating, homing, and repairing injured tissues. We also review a number of reports showing that tumor microenvironment triggers plasticity mechanisms in MSCs to induce malignant neoplastic tissue formation, maintenance, and chemoresistance, as well as tumor growth. The antitumor properties and therapeutic potential of MSCs are also discussed.
文摘The effects of 3,4-DHAP on hypoxic pulmonary and systemic vascular responses were studied in anaesthetized dogs. The percentage change in pulmonary vascular resistance(△PVR%)and that in systemic vascular resistance(△SVR%)induced by 5 min hypoxia decreased significantly.3,4-DHAP in doses of 1 mg/kg,3mg/kg,and 10 mg/kg i.v caused a decrease in b PVR% from the control value of 47.27±22.27% to 24.62±21.76%,18.15±18.73%,and 24.10±19.76% respectively, and a decrease in △SVR% from the control value of 12.91±7.39% to -0.34±12.7%,-2.11±12.76%,and -2.37±15.52% respectively.The results showed that 3,4-DHAP could decrease the hypoxic responses of pulmonary and systemic blood vessels.But it did not change △PVR% or △SVR% in dose of 30mg/kg,neither did it influence the heart rate,cardiac output or cerebral blood flow during hypoxia in all the doses used.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2009CB421503)International Cooperating Program of Science and Technology(2010DFA24650)+1 种基金National Natural Science Foundation of China(41375098 and 41175061)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘We diagnose characteristics of the quasi-balanced flow and secondary circulation（SC） of tropical storm Bilis（2006） using the potential vorticity（PV）-ω inversion method.We further analyze how secondary steering flows associated with mesoscale convective systems affected the track of tropical storm Bilis after it made landfall.The quasi-balanced asymmetric and axisymmetric circulation structures of tropical storm Bilis are represented well by the PV-w inversion.The magnitude of the nonlinear quasi-balanced vertical velocity is approximately 75%of the magnitude simulated using the Weather Research and Forecasting（WRF） model.The SC of Bilis（2006） contained two strong regions of ascending motion,both of which were located in the southwest quadrant of the storm.The first（150-200 km southwest of the storm center） corresponded to the eyewall region,while the second（approximately 400 km southwest of the storm center） corresponded to latent heat release associated with strong precipitation in major spiral rainbands.The SC was very weak in the northeast quadrant（the upshear direction）.Dynamical processes related to the environmental vertical wind shear produced an SC that partially offset the destructive effects of the environmental vertical wind shear（by 20%-25%）.This SC consisted of upward motion in the southwest quadrant and subsidence in the northeast quadrant,with airflow oriented from southwest to northeast at high altitudes and from northeast to southwest at lower levels.The inverted secondary zonal and meridional steering flows associated with continuous asymmetric mesoscale convective systems were about-2.14 and-0.7 m s^（-1）,respectively.These steering flows contributed substantially to the zonal（66.15%） and meridional（33.98%） motion of the storm at 0000 UTC15 July 2006.The secondary steering flow had a significant influence on changing the track of Bilis from southward to northward.The direction of the large-scale meridional steering flow（3.02 m s^（-1）） was opposite to the actual meridional motion（-2.06 m s^（-1））.
基金Supported by the National(Key) Basic Research and Development(973) Program of China(2012CB417202)National Natural Science Foundation of China(41175049 and 41221064)+1 种基金Basic Research Funds of the Chinese Academy of Meteorological Sciences(2012Y001)National Science and Technology Support Program of China(2012BAC22B03)
文摘This study investigates influencing weather systems for and the effect of Tibetan Plateau （TP）’s surface heating on the heavy rainfall over southern China in June 2010, focusing on the four persistent heavy rainfall events during 14-24 June 2010. The ma jor weather systems include the South Asian high, midlatitude trough and ridge, western Pacific subtropical high in the middle troposphere, and shear lines and eastward-moving vortices in the lower troposphere. An ensemble of convection-permitting simulations （CTL） is carried out with the WRF model for these rainfall events, which successfully reproduce the observed evolution of precipitation and weather systems. Another ensemble of simulations （SEN） with the surface albedo over the TP and its southern slope changed artificially to one, i.e., the surface does not absorb any solar heating, otherwise it is identical to CTL, is also performed. Comparison between CTL and SEN suggests that the surface sensible heating of TP in CTL significantly affects the temperature distributions over the plateau and its surroundings, and the thermal wind adjustment consequently changes atmospheric circulations and properties of the synoptic systems, leading to intensified precipitation over southern China. Specifically, at 200 hPa, anticyclonic and cyclonic anomalies form over the western and eastern plateau, respectively, which enhances the southward cold air intrusion along the eastern TP and the divergence over southern China;at 500 hPa, the ridge over the northern plateau and the trough over eastern China are strengthened, the southwesterly flows along the northwestern side of the subtropical high are intensified, and the positive vorticity propagation from the plateau to its downstream is also enhanced significantly;at 850 hPa, the low-pressure vortices strongly develop and move eastward while the southwesterly low-level jet over southern China strengthens in CTL, leading to increased water vapor convergence and upward motion over the precipitation region.
文摘The basic theme of this work is to identify the optimal measurement locations for pres- sure and flow in the systemic circulation to detect aortic stenoses and aneurysms in early stages of a disease. For this purpose, a linear elastic lumped parameter model of the fluid dynamical simulator, major arterial cardiovascular simulator （MACSim）, is considered and global sensitivity analysis is applied to identify the better measurement locations for pressure and flow in the systemic circulation. The obtained results of sensitivity analysis provide insight that enable the experimentalists to optimize their experimental setups for detecting aortic stenoses and aneurysms using parameter estimation process. From the results, it is observed that the stenosis in the thoracic aorta can be identified from both pressure and flow at the location itself, nearby nodes, aorta ascendens, arcus aorta, arteria subclavia and arteria axillaris. On the other hand, the preferable measurement locations for abdominal aneurysms are locations themselves, nearby nodes and left/right leg of the body.
