The 2015/2016 El Nio was one of the strongest El Nio events in history, and this strong event was preceded by a weak El Nio in 2014. This study systematically analyzed the dynamical processes responsible for the genes...The 2015/2016 El Nio was one of the strongest El Nio events in history, and this strong event was preceded by a weak El Nio in 2014. This study systematically analyzed the dynamical processes responsible for the genesis of these events. It was found that the weak 2014 El Nio had two warming phases, the spring-summer warming was produced by zonal advection and downwelling Kelvin waves driven by westerly wind bursts(WWBs), and the autumn-winter warming was produced by meridional advection, surface heating as well as downwelling Kelvin waves. The 2015/2016 extreme El Nio, on the other hand, was primarily a result of sustained zonal advection and downwelling Kelvin waves driven by a series of WWBs, with enhancement from the Bjerknes positive feedback. The vast difference between these two El Nio events mainly came from the different amount of WWBs in 2014 and 2015. As compared to the 1982/1983 and 1997/1998 extreme El Nio events, the 2015/2016 El Nio exhibited some distinctive characteristics in its genesis and spatial pattern. We need to include the effects of WWBs to the theoretical framework of El Nio to explain these characteristics, and to improve our understanding and prediction of El Nio.展开更多
This paper deals with the blow-up rate estimates of positive solutions for systems of heat equationswith nonlinear boundary conditions. The upper and lower bounds of blow-up rate are obtained.
The purpose of this paper is to investigate the stability and asymptotic behavior of the time-dependent solutions to a linear parabolic equation with nonlinear boundary condition in relation to their corresponding ste...The purpose of this paper is to investigate the stability and asymptotic behavior of the time-dependent solutions to a linear parabolic equation with nonlinear boundary condition in relation to their corresponding steady state solutions. Then, the above results are extended to a semilinear parabolic equation with nonlinear boundary condition by analyzing the corresponding eigenvalue problem and using the method of upper and lower solutions.展开更多
Objective:Gastrointestinal heat retention syndrome(GHRS)is associated with lung-heat syndrome and is related to recurrent respiratory infection.Upper respiratory tract infection(URTI)lung heat syndrome is common in ch...Objective:Gastrointestinal heat retention syndrome(GHRS)is associated with lung-heat syndrome and is related to recurrent respiratory infection.Upper respiratory tract infection(URTI)lung heat syndrome is common in children.The study will explore the effect of GHRS on the structure and function of gut microbiota in children with URTI lung-heat syndrome.Methods:Participants were divided into both groups using the self-developed URTI scale and the“GHRS Diagnostic Scale$Pediatric Part”:GHRS-positive children(LS group)and GHRS-negative children(L group).General information,clinical symptoms,and stool were collected.We used 16S rRNA amplicon sequencing technology to determine the gene sequence of the V3eV4 region in feces and measure the gut microbiota of the both groups at the genus level.Results:A total of 23 children were included in the both groups.There were 12 cases in the LS group and 11 cases in the L group.There was no statistical difference between the both groups in age,gender,height,weight,and body mass index.The effective sequences shared by the both groups accounted for 85.66%of the total.In the gut microbiota,there was no difference in the a diversity and the b diversity between the both groups.Compared with the L group,the LS group had a significant increase in the relative abundance of the Ruminococcus gnavus group,Prevotella-9,Staphylococcus,and Actinomyces(P<.05).The functions of the both groups of microbiota primarily concentrate on metabolism,genetic information processing,and environmental information processing.The relative abundance of signaling molecules and interactions in the LS group were higher than that in the L group(P<.05).The redundancy analysis(RDA)showed that the URTI score had the greatest impact on the distribution of microbiota.Conclusion:GHRS may affect the development of URTI lung-heat syndrome by changing the relative abundances of gut microbiota.展开更多
By using a linear baroclinic model(LBM),this study investigates the different Rossby wave train(RWT)patterns associated with the Tibetan Plateau(TP)upper-atmospheric heat source(TPUHS)that is anomalously shallower and...By using a linear baroclinic model(LBM),this study investigates the different Rossby wave train(RWT)patterns associated with the Tibetan Plateau(TP)upper-atmospheric heat source(TPUHS)that is anomalously shallower and deeper in boreal summer.Observational results indicate the different RWT patterns between the developing and decaying periods of synoptic TPUHS events,when the anomalous TPUHS develops from a relatively shallower to a deeper TP heat source.Based on the different vertical heating profiles between these two periods in observation,this study forces the LBM with prescribed TPUHS profiles to mimic a shallower and deeper summer TP heat source.The results show that the atmospheric responses to a shallower and deeper TPUHS do exhibit different RWT patterns that largely resemble those in observation.Namely,corresponding RWT pattern to a shallower TPUHS stretches from the TP to the west coast of America,while that to a deeper TPUHS extends from the TP region to Alaska.展开更多
Surface waves comprise an important aspect of the interaction between the atmosphere and the ocean, so a dynamically consistent framework for modelling atmosphere-ocean interaction must take account of surface waves, ...Surface waves comprise an important aspect of the interaction between the atmosphere and the ocean, so a dynamically consistent framework for modelling atmosphere-ocean interaction must take account of surface waves, either implicitly or explicitly. In order to calculate the effect of wind forcing on waves and currents, and vice versa, it is necessary to employ a consistent formula- tion of the energy and momentum balance within the airflow, wave field, and water column. It is very advantageous to apply sur- face-following coordinate systems, whereby the steep gradients in mean flow properties near the air-water interface in the cross-interface direction may be resolved over distances which are much smaller than the height of the waves themselves. We may account for the waves explicitly by employing a numerical spectral wave model, and applying a suitable theory of wave–mean flow interaction. If the mean flow is small compared with the wave phase speed, perturbation expansions of the hydrodynamic equations in a Lagrangian or generalized Lagrangian mean framework are useful: for stronger flows, such as for wind blowing over waves, the presence of critical levels where the mean flow velocity is equal to the wave phase speed necessitates the application of more general types of surface-following coordinate system. The interaction of the flow of air and water and associated differences in temperature and the concentration of various substances (such as gas species) gives rise to a complex boundary-layer structure at a wide range of vertical scales, from the sub-millimetre scales of gaseous diffusion, to several tens of metres for the turbulent Ekman layer. The bal- ance of momentum, heat, and mass is also affected significantly by breaking waves, which act to increase the effective area of the surface for mass transfer, and increase turbulent diffusive fluxes via the conversion of wave energy to turbulent kinetic energy.展开更多
Monthly ocean temperature from ORAS4 datasets and atmospheric data from NCEP/NCAR Reanalysis I/II were used to analyze the relationship between the intensity of the South Asian summer monsoon(SASM) and upper ocean hea...Monthly ocean temperature from ORAS4 datasets and atmospheric data from NCEP/NCAR Reanalysis I/II were used to analyze the relationship between the intensity of the South Asian summer monsoon(SASM) and upper ocean heat content(HC) in the tropical Indo-Pacific Ocean.The monsoon was differentiated into a Southwest Asian Summer Monsoon(SWASM)(2.5°–20°N,35°–70°E) and Southeast Asian Summer Monsoon(SEASM)(2.5°–20°N,70°–110°E).Results show that before the 1976/77 climate shift,the SWASM was strongly related to HC in the southern Indian Ocean and tropical Pacific Ocean.The southern Indian Ocean affected SWASM by altering the pressure gradient between southern Africa and the northern Indian Ocean and by enhancing the Somali cross-equatorial flow.The tropical Pacific impacted the SWASM through the remote forcing of ENSO.After the 1976/77 shift,there was a close relationship between equatorial central Pacific HC and the SEASM.However,before that shift,their relationship was weak.展开更多
Regardless of the slowdown in global warming during the hiatus period, sea surface temperatures(SSTs) in the southwestern Indian Ocean(SWIO) have experienced sustained decadal warming for more than two decades since t...Regardless of the slowdown in global warming during the hiatus period, sea surface temperatures(SSTs) in the southwestern Indian Ocean(SWIO) have experienced sustained decadal warming for more than two decades since the mid-1990 s. The SWIO SSTs warmed steadily during 1996–2016, causing a warming hot spot of 0.4 K decade-1 in a large region east of Madagascar. An upper-layer heat budget analysis indicated that heat advection by ocean currents was the greatest contributor to the warming of the SWIO SSTs. The existence of an anticyclonic geostrophic current along the western boundary of the SWIO tended to maintain such warming by transporting warmer water from the west into the SWIO region. In addition, net positive heat transport by ocean currents also occurred at the southern boundary of the SWIO as the climatological northward transport of cold water from the Southern Ocean weakened. This reduction in northward ocean currents at the surface was caused by local wind stress changes, leading to a southward Ekman current. Below the surface, an anticyclonic geostrophic current pattern existed around the warming center near the southeastern SWIO, which reduced the transport of cold waters from the Southern Ocean and warmed the SWIO. These processes near the two boundaries formed a self-sustaining positive feedback mechanism and favored the maintenance of sustained warming in the SWIO. More attention is needed to analyze the sustained long-lasting warming in the SWIO, as it is a unique phenomenon occurring under the background of the ongoing global warming.展开更多
At the interface between the lower atmosphere and sea surface,sea spray might significantly influence air-sea heat fluxes and subsequently,modulate upper ocean temperature during a typhoon passage. The effects of sea ...At the interface between the lower atmosphere and sea surface,sea spray might significantly influence air-sea heat fluxes and subsequently,modulate upper ocean temperature during a typhoon passage. The effects of sea spray were introduced into the parameterization of sea surface roughness in a 1-D turbulent model,to investigate the effects of sea spray on upper ocean temperature in the Kuroshio Extension area,for the cases of two real typhoons from 2006,Yagi and Soulik. Model output was compared with data from the Kuroshio Extension Observatory(KEO),and Reynolds and AMSRE satellite remote sensing sea surface temperatures. The results indicate drag coefficients that include the spray effect are closer to observations than those without,and that sea spray can enhance the heat fluxes(especially latent heat flux) considerably during a typhoon passage. Consequently,the model results with heat fluxes enhanced by sea spray simulate better the cooling process of the SST and upper-layer temperature profiles. Additionally,results from the simulation of the passage of typhoon Soulik(that passed KEO quickly),which included the sea spray effect,were better than for the simulated passage of typhoon Yagi(that crossed KEO slowly). These promising 1-D results could provide insight into the application of sea spray in general circulation models for typhoon studies.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 41690121, 41690124, 41690120, 41506025 & 41621064)the National Program on Global Change and Air-Sea Interaction (Grant Nos. GASI-IPOVAI-04 & GASI-IPOVAI-06)the Zhejiang Provincial Natural Science Foundation of China (Grant No. LQ15D060004)
文摘The 2015/2016 El Nio was one of the strongest El Nio events in history, and this strong event was preceded by a weak El Nio in 2014. This study systematically analyzed the dynamical processes responsible for the genesis of these events. It was found that the weak 2014 El Nio had two warming phases, the spring-summer warming was produced by zonal advection and downwelling Kelvin waves driven by westerly wind bursts(WWBs), and the autumn-winter warming was produced by meridional advection, surface heating as well as downwelling Kelvin waves. The 2015/2016 extreme El Nio, on the other hand, was primarily a result of sustained zonal advection and downwelling Kelvin waves driven by a series of WWBs, with enhancement from the Bjerknes positive feedback. The vast difference between these two El Nio events mainly came from the different amount of WWBs in 2014 and 2015. As compared to the 1982/1983 and 1997/1998 extreme El Nio events, the 2015/2016 El Nio exhibited some distinctive characteristics in its genesis and spatial pattern. We need to include the effects of WWBs to the theoretical framework of El Nio to explain these characteristics, and to improve our understanding and prediction of El Nio.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 19831060) and "333" Project of Jiangsu Province.
文摘This paper deals with the blow-up rate estimates of positive solutions for systems of heat equationswith nonlinear boundary conditions. The upper and lower bounds of blow-up rate are obtained.
基金The project is supported by National Natural Science Foundation of China (10071026)
文摘The purpose of this paper is to investigate the stability and asymptotic behavior of the time-dependent solutions to a linear parabolic equation with nonlinear boundary condition in relation to their corresponding steady state solutions. Then, the above results are extended to a semilinear parabolic equation with nonlinear boundary condition by analyzing the corresponding eigenvalue problem and using the method of upper and lower solutions.
基金This study was financially supported by the National Key R&D Program of China(2018YFC1704100 and 2018YFC1704101)Beijing Municipal Natural Science Foundation(7172131).
文摘Objective:Gastrointestinal heat retention syndrome(GHRS)is associated with lung-heat syndrome and is related to recurrent respiratory infection.Upper respiratory tract infection(URTI)lung heat syndrome is common in children.The study will explore the effect of GHRS on the structure and function of gut microbiota in children with URTI lung-heat syndrome.Methods:Participants were divided into both groups using the self-developed URTI scale and the“GHRS Diagnostic Scale$Pediatric Part”:GHRS-positive children(LS group)and GHRS-negative children(L group).General information,clinical symptoms,and stool were collected.We used 16S rRNA amplicon sequencing technology to determine the gene sequence of the V3eV4 region in feces and measure the gut microbiota of the both groups at the genus level.Results:A total of 23 children were included in the both groups.There were 12 cases in the LS group and 11 cases in the L group.There was no statistical difference between the both groups in age,gender,height,weight,and body mass index.The effective sequences shared by the both groups accounted for 85.66%of the total.In the gut microbiota,there was no difference in the a diversity and the b diversity between the both groups.Compared with the L group,the LS group had a significant increase in the relative abundance of the Ruminococcus gnavus group,Prevotella-9,Staphylococcus,and Actinomyces(P<.05).The functions of the both groups of microbiota primarily concentrate on metabolism,genetic information processing,and environmental information processing.The relative abundance of signaling molecules and interactions in the LS group were higher than that in the L group(P<.05).The redundancy analysis(RDA)showed that the URTI score had the greatest impact on the distribution of microbiota.Conclusion:GHRS may affect the development of URTI lung-heat syndrome by changing the relative abundances of gut microbiota.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences [grant number XDA17010105]the National Natural Science Foundation of China [grant numbers 91437105,41430533,and 41575041]the Key Research Program of Frontier Sciences [grant number QYZDY-SSW-DQC018]
文摘By using a linear baroclinic model(LBM),this study investigates the different Rossby wave train(RWT)patterns associated with the Tibetan Plateau(TP)upper-atmospheric heat source(TPUHS)that is anomalously shallower and deeper in boreal summer.Observational results indicate the different RWT patterns between the developing and decaying periods of synoptic TPUHS events,when the anomalous TPUHS develops from a relatively shallower to a deeper TP heat source.Based on the different vertical heating profiles between these two periods in observation,this study forces the LBM with prescribed TPUHS profiles to mimic a shallower and deeper summer TP heat source.The results show that the atmospheric responses to a shallower and deeper TPUHS do exhibit different RWT patterns that largely resemble those in observation.Namely,corresponding RWT pattern to a shallower TPUHS stretches from the TP to the west coast of America,while that to a deeper TPUHS extends from the TP region to Alaska.
文摘Surface waves comprise an important aspect of the interaction between the atmosphere and the ocean, so a dynamically consistent framework for modelling atmosphere-ocean interaction must take account of surface waves, either implicitly or explicitly. In order to calculate the effect of wind forcing on waves and currents, and vice versa, it is necessary to employ a consistent formula- tion of the energy and momentum balance within the airflow, wave field, and water column. It is very advantageous to apply sur- face-following coordinate systems, whereby the steep gradients in mean flow properties near the air-water interface in the cross-interface direction may be resolved over distances which are much smaller than the height of the waves themselves. We may account for the waves explicitly by employing a numerical spectral wave model, and applying a suitable theory of wave–mean flow interaction. If the mean flow is small compared with the wave phase speed, perturbation expansions of the hydrodynamic equations in a Lagrangian or generalized Lagrangian mean framework are useful: for stronger flows, such as for wind blowing over waves, the presence of critical levels where the mean flow velocity is equal to the wave phase speed necessitates the application of more general types of surface-following coordinate system. The interaction of the flow of air and water and associated differences in temperature and the concentration of various substances (such as gas species) gives rise to a complex boundary-layer structure at a wide range of vertical scales, from the sub-millimetre scales of gaseous diffusion, to several tens of metres for the turbulent Ekman layer. The bal- ance of momentum, heat, and mass is also affected significantly by breaking waves, which act to increase the effective area of the surface for mass transfer, and increase turbulent diffusive fluxes via the conversion of wave energy to turbulent kinetic energy.
基金Supported by the Key Program of National Natural Science Foundation of China(NSFC)(No.41330963)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA01010101)+1 种基金the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406401)the Fund for Innovative Research Groups of the NSFC(No.41421005)
文摘Monthly ocean temperature from ORAS4 datasets and atmospheric data from NCEP/NCAR Reanalysis I/II were used to analyze the relationship between the intensity of the South Asian summer monsoon(SASM) and upper ocean heat content(HC) in the tropical Indo-Pacific Ocean.The monsoon was differentiated into a Southwest Asian Summer Monsoon(SWASM)(2.5°–20°N,35°–70°E) and Southeast Asian Summer Monsoon(SEASM)(2.5°–20°N,70°–110°E).Results show that before the 1976/77 climate shift,the SWASM was strongly related to HC in the southern Indian Ocean and tropical Pacific Ocean.The southern Indian Ocean affected SWASM by altering the pressure gradient between southern Africa and the northern Indian Ocean and by enhancing the Somali cross-equatorial flow.The tropical Pacific impacted the SWASM through the remote forcing of ENSO.After the 1976/77 shift,there was a close relationship between equatorial central Pacific HC and the SEASM.However,before that shift,their relationship was weak.
基金the National Key Research and Development Program of China (2016YFA0600602)National Natural Science Foundation of China (41776039)。
文摘Regardless of the slowdown in global warming during the hiatus period, sea surface temperatures(SSTs) in the southwestern Indian Ocean(SWIO) have experienced sustained decadal warming for more than two decades since the mid-1990 s. The SWIO SSTs warmed steadily during 1996–2016, causing a warming hot spot of 0.4 K decade-1 in a large region east of Madagascar. An upper-layer heat budget analysis indicated that heat advection by ocean currents was the greatest contributor to the warming of the SWIO SSTs. The existence of an anticyclonic geostrophic current along the western boundary of the SWIO tended to maintain such warming by transporting warmer water from the west into the SWIO region. In addition, net positive heat transport by ocean currents also occurred at the southern boundary of the SWIO as the climatological northward transport of cold water from the Southern Ocean weakened. This reduction in northward ocean currents at the surface was caused by local wind stress changes, leading to a southward Ekman current. Below the surface, an anticyclonic geostrophic current pattern existed around the warming center near the southeastern SWIO, which reduced the transport of cold waters from the Southern Ocean and warmed the SWIO. These processes near the two boundaries formed a self-sustaining positive feedback mechanism and favored the maintenance of sustained warming in the SWIO. More attention is needed to analyze the sustained long-lasting warming in the SWIO, as it is a unique phenomenon occurring under the background of the ongoing global warming.
基金Supported by the National Basic Research Program of China(973 Program)(No.2013CB430304)the National Natural Science Foundation of China(Nos.41030854,41106005,41176003,41206178,41376015,41376013,41306006)+1 种基金the National High-Tech R&D Program of China(No.2013AA09A505)the Public Science and Technology Research Funds Projects of Ocean(No.20130531-8)
文摘At the interface between the lower atmosphere and sea surface,sea spray might significantly influence air-sea heat fluxes and subsequently,modulate upper ocean temperature during a typhoon passage. The effects of sea spray were introduced into the parameterization of sea surface roughness in a 1-D turbulent model,to investigate the effects of sea spray on upper ocean temperature in the Kuroshio Extension area,for the cases of two real typhoons from 2006,Yagi and Soulik. Model output was compared with data from the Kuroshio Extension Observatory(KEO),and Reynolds and AMSRE satellite remote sensing sea surface temperatures. The results indicate drag coefficients that include the spray effect are closer to observations than those without,and that sea spray can enhance the heat fluxes(especially latent heat flux) considerably during a typhoon passage. Consequently,the model results with heat fluxes enhanced by sea spray simulate better the cooling process of the SST and upper-layer temperature profiles. Additionally,results from the simulation of the passage of typhoon Soulik(that passed KEO quickly),which included the sea spray effect,were better than for the simulated passage of typhoon Yagi(that crossed KEO slowly). These promising 1-D results could provide insight into the application of sea spray in general circulation models for typhoon studies.
