Langmuir turbulence is a complex turbulent process in the ocean upper mixed layer.The Coriolis parameter has an important effect on Langmuir turbulence through the Coriolis-Stokes force and Ekman effect,however,this e...Langmuir turbulence is a complex turbulent process in the ocean upper mixed layer.The Coriolis parameter has an important effect on Langmuir turbulence through the Coriolis-Stokes force and Ekman effect,however,this effect on Langmuir turbulence has not been systematically investigated.Here,the impact of the Coriolis parameter on Langmuir turbulence with a change of latitude(LAT)from 20°N to 80°N is studied using a non-hydrostatic large eddy simulation model under an ideal condition.The results show that the ratio of the upper mixed layer depth to Ekman depth scale(RME)RME=0.266(LAT=50°N)is a key value(latitude)for the modulation effect of the Coriolis parameter on the mean and turbulent statistics of Langmuir turbulence.It is found that the rate of change of the sea surface temperature,upper mixed layer depth,entrainment flux,crosswind velocity,downwind vertical momentum flux,and turbulent kinetic energy budget terms associated with Langmuir turbulence are more evident at RME≤0.266(LAT≤50°N)than at RME≥0.266(LAT≥50°N).However,the rate of change of the depth-averaged crosswind vertical momentum flux does not have a clear variation between RME≤0.266 and RME≥0.266.The complex changes of both Langmuir turbulence characteristics and influence of Langmuir turbulence on the upper mixed layer with latitude presented here may provide more information for further improving Langmuir turbulence parameterization.展开更多
An investigation of equatorial near-inertial wave dynamics under complete Coriolis parameters is performed in this paper.Starting from the basic model equations of oceanic motions,a Korteweg de Vries equation is deriv...An investigation of equatorial near-inertial wave dynamics under complete Coriolis parameters is performed in this paper.Starting from the basic model equations of oceanic motions,a Korteweg de Vries equation is derived to simulate the evolution of equatorial nonlinear near-inertial waves by using methods of scaling analysis and perturbation expansions under the equatorial beta plane approximation.Theoretical dynamic analysis is finished based on the obtained Korteweg de Vries equation,and the results show that the horizontal component of Coriolis parameters is of great importance to the propagation of equatorial nonlinear near-inertial solitary waves by modifying its dispersion relation and by interacting with the basic background flow.展开更多
The climatology of near-equatorial typhoons over the western-north Pacific are fully investigated using the JTWC (Joint Typhoon Warning Center) typhoon record from 1951 to 2006. The result shows that there are seaso...The climatology of near-equatorial typhoons over the western-north Pacific are fully investigated using the JTWC (Joint Typhoon Warning Center) typhoon record from 1951 to 2006. The result shows that there are seasonal and decadal variations, as well as a distinctive spatial distribution, of such events. Among them, Typhoon Vamei is an example of a near-equatorial typhoon that occurred near Singapore in December of 2001. Using the WRF (Weather and Research Forecast) model, we attempt to find out how the well known "wind surge" of this event contributes to the development of Typhoon Vamei. It is found that the strong wind surge not only helps to provide advection of positive vorticity to Vamei between 800 and 500 hPa, but also increases the convective instability of the lower troposphere, and thus helps to induce convective outbreaks and rapid intensification. Furthermore, sensitivity experiments show that terrain and the land-sea distribution have very limited effects on the formation of Typhoon Vamei in the simulation, but an adequate Coriolis parameter (f) is still needed for the development of Vamei.展开更多
Considering the effect of horizontal Coriolis parameter and the density compactness of seawater, which were often neglected in internal waves discussion, the governing equation of linear internal waves presented by ve...Considering the effect of horizontal Coriolis parameter and the density compactness of seawater, which were often neglected in internal waves discussion, the governing equation of linear internal waves presented by vertical velocity only will be proposed. Under the assumption that the Brunt- Vaeisaelae frequency is exponential, an accurate analytic solution of it is obtained. Finally, the expressions of wave functions are also given.展开更多
The sensitivity of tropical cyclone(TC) intensification to the ambient rotation effect under vertical shear is investigated. The results show that the vortices develop more rapidly with intermediate planetary vortic...The sensitivity of tropical cyclone(TC) intensification to the ambient rotation effect under vertical shear is investigated. The results show that the vortices develop more rapidly with intermediate planetary vorticity, which suggests an optimal latitude for the TC development in the presence of vertical shear. This is different from the previous studies in which no mean flow is considered. It is found that the ambient rotation has two main effects. On the one hand,the boundary layer imbalance is largely controlled by the Coriolis parameter. For TCs at lower latitudes, due to the weaker inertial instability, the boundary inflow is promptly established, which results in a stronger moisture convergence and thus greater diabatic heating in the inner core region. On the other hand, the Coriolis parameter modulates the vertical realignment of the vortex with a higher Coriolis parameter, favoring a quicker vertical realignment and thus a greater potential for TC development. The combination of these two effects results in an optimal latitude for TC intensification in the presence of a vertical shear investigated.展开更多
基金supported by the National Key Research and Development Program of China (Grant No. 2018YFC1405701)the National Natural Science Foundation of China (Grant Nos. 92158204, 41506001, 42076019, 42076026 and 41876017)the Project supported by Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (Grant No. GML2019ZD0304)
文摘Langmuir turbulence is a complex turbulent process in the ocean upper mixed layer.The Coriolis parameter has an important effect on Langmuir turbulence through the Coriolis-Stokes force and Ekman effect,however,this effect on Langmuir turbulence has not been systematically investigated.Here,the impact of the Coriolis parameter on Langmuir turbulence with a change of latitude(LAT)from 20°N to 80°N is studied using a non-hydrostatic large eddy simulation model under an ideal condition.The results show that the ratio of the upper mixed layer depth to Ekman depth scale(RME)RME=0.266(LAT=50°N)is a key value(latitude)for the modulation effect of the Coriolis parameter on the mean and turbulent statistics of Langmuir turbulence.It is found that the rate of change of the sea surface temperature,upper mixed layer depth,entrainment flux,crosswind velocity,downwind vertical momentum flux,and turbulent kinetic energy budget terms associated with Langmuir turbulence are more evident at RME≤0.266(LAT≤50°N)than at RME≥0.266(LAT≥50°N).However,the rate of change of the depth-averaged crosswind vertical momentum flux does not have a clear variation between RME≤0.266 and RME≥0.266.The complex changes of both Langmuir turbulence characteristics and influence of Langmuir turbulence on the upper mixed layer with latitude presented here may provide more information for further improving Langmuir turbulence parameterization.
基金The National Natural Science Foundation of China under contract No.11762011the Natural Science Foundation of Inner Mongolia Autonomous Region under contract No.2020BS01002+1 种基金the Research Program of Science at Universities of Inner Mongolia Autonomous Region under contract No.NJZY20003the Scientific Starting Foundation of Inner Mongolia University under contract No.21100-5185105
文摘An investigation of equatorial near-inertial wave dynamics under complete Coriolis parameters is performed in this paper.Starting from the basic model equations of oceanic motions,a Korteweg de Vries equation is derived to simulate the evolution of equatorial nonlinear near-inertial waves by using methods of scaling analysis and perturbation expansions under the equatorial beta plane approximation.Theoretical dynamic analysis is finished based on the obtained Korteweg de Vries equation,and the results show that the horizontal component of Coriolis parameters is of great importance to the propagation of equatorial nonlinear near-inertial solitary waves by modifying its dispersion relation and by interacting with the basic background flow.
基金supported by Chinese State Key program 2009CB421500the National Natural Science Foundation of China under Grant Nos.40921160380 and 40975059the Scientific Research Foundation of the Ministry of Education of China
文摘The climatology of near-equatorial typhoons over the western-north Pacific are fully investigated using the JTWC (Joint Typhoon Warning Center) typhoon record from 1951 to 2006. The result shows that there are seasonal and decadal variations, as well as a distinctive spatial distribution, of such events. Among them, Typhoon Vamei is an example of a near-equatorial typhoon that occurred near Singapore in December of 2001. Using the WRF (Weather and Research Forecast) model, we attempt to find out how the well known "wind surge" of this event contributes to the development of Typhoon Vamei. It is found that the strong wind surge not only helps to provide advection of positive vorticity to Vamei between 800 and 500 hPa, but also increases the convective instability of the lower troposphere, and thus helps to induce convective outbreaks and rapid intensification. Furthermore, sensitivity experiments show that terrain and the land-sea distribution have very limited effects on the formation of Typhoon Vamei in the simulation, but an adequate Coriolis parameter (f) is still needed for the development of Vamei.
文摘Considering the effect of horizontal Coriolis parameter and the density compactness of seawater, which were often neglected in internal waves discussion, the governing equation of linear internal waves presented by vertical velocity only will be proposed. Under the assumption that the Brunt- Vaeisaelae frequency is exponential, an accurate analytic solution of it is obtained. Finally, the expressions of wave functions are also given.
基金Supported by the National Natural Science Foundation of China(41575056,41775058,41575043,and 41375095)National(Key)Basic Research and Development(973)Program of China(2015CB452803)+2 种基金National Key Research Project(2017YFA0603802)Key University Science Research Project of Jiangsu Province(14KJA170005)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘The sensitivity of tropical cyclone(TC) intensification to the ambient rotation effect under vertical shear is investigated. The results show that the vortices develop more rapidly with intermediate planetary vorticity, which suggests an optimal latitude for the TC development in the presence of vertical shear. This is different from the previous studies in which no mean flow is considered. It is found that the ambient rotation has two main effects. On the one hand,the boundary layer imbalance is largely controlled by the Coriolis parameter. For TCs at lower latitudes, due to the weaker inertial instability, the boundary inflow is promptly established, which results in a stronger moisture convergence and thus greater diabatic heating in the inner core region. On the other hand, the Coriolis parameter modulates the vertical realignment of the vortex with a higher Coriolis parameter, favoring a quicker vertical realignment and thus a greater potential for TC development. The combination of these two effects results in an optimal latitude for TC intensification in the presence of a vertical shear investigated.