Under the assumption of an effective point source model,this paper introduces a conception of equivalent phase velocity to describle the average propagation processes and dispersion properties of seismic waves from se...Under the assumption of an effective point source model,this paper introduces a conception of equivalent phase velocity to describle the average propagation processes and dispersion properties of seismic waves from seismic source to the site,then illuminates the relation between the phase properties of seismic motion and equivalent phase velocity and obtains a simple formula of estimating the equivalent phase velocity through the use of the phase difference spectrum of seismic motion.After the parts of strong seismic records in the western American and the SMART-1 array are used to identify the method presented by this paper in reason,the statistical relations of equivalent phase velocity are given in the above two regions.The results of the paper have demonstrated that the phase spectrum of seismic motion has its inner law as same as the amplitude spectrum does.展开更多
A dominant role played by energy dispersion in the explosive development of extratropical marine cyclones over the Northwest Pacific has been revealed based on both the eddy energy equations and the energy flux vector...A dominant role played by energy dispersion in the explosive development of extratropical marine cyclones over the Northwest Pacific has been revealed based on both the eddy energy equations and the energy flux vectors of nonlinear wave packet.At the initial and explosive time. the eddy energy from neighboring upstream systems beyond the radius of Rossby deformation is dispersed into the eddy energy center associated with the cyclone via ageostrophic geopotential fluxes,and results in the rapid increase of eddy kinetic energy and the occurrence of explosive cyclogenesis.When the cyclone begins to decay,its corresponding eddy energy is exported downstream and hence triggers the growth of new perturbation downstream.Through generalizing the energy flux vectors of quasigeostrophic wave packets to the nonlinear forms and making use of the relationship between the energy flux vectors and the total eddy energy,the approximation expressions of the total group velocity and relative group velocity are derived,and then they are used to compute an explosive case.The normalized ageostrophic geopotential fluxes by dividing the volume integral of ageostrophic geopotential fluxes by the integral of the total eddy energy determine the relative group velocity at which the eddy energy is spreading out,and they can be used to evaluate the position of next new disturbance.The nonlinear advective fluxes influence primarily the phase speed and translation of the cyclones.The results in this paper facilitate to expanding the mechanism research on explosive cyclones and have great significance for predicting the explosive intensification and downstream disturbance growth.展开更多
文摘Under the assumption of an effective point source model,this paper introduces a conception of equivalent phase velocity to describle the average propagation processes and dispersion properties of seismic waves from seismic source to the site,then illuminates the relation between the phase properties of seismic motion and equivalent phase velocity and obtains a simple formula of estimating the equivalent phase velocity through the use of the phase difference spectrum of seismic motion.After the parts of strong seismic records in the western American and the SMART-1 array are used to identify the method presented by this paper in reason,the statistical relations of equivalent phase velocity are given in the above two regions.The results of the paper have demonstrated that the phase spectrum of seismic motion has its inner law as same as the amplitude spectrum does.
文摘A dominant role played by energy dispersion in the explosive development of extratropical marine cyclones over the Northwest Pacific has been revealed based on both the eddy energy equations and the energy flux vectors of nonlinear wave packet.At the initial and explosive time. the eddy energy from neighboring upstream systems beyond the radius of Rossby deformation is dispersed into the eddy energy center associated with the cyclone via ageostrophic geopotential fluxes,and results in the rapid increase of eddy kinetic energy and the occurrence of explosive cyclogenesis.When the cyclone begins to decay,its corresponding eddy energy is exported downstream and hence triggers the growth of new perturbation downstream.Through generalizing the energy flux vectors of quasigeostrophic wave packets to the nonlinear forms and making use of the relationship between the energy flux vectors and the total eddy energy,the approximation expressions of the total group velocity and relative group velocity are derived,and then they are used to compute an explosive case.The normalized ageostrophic geopotential fluxes by dividing the volume integral of ageostrophic geopotential fluxes by the integral of the total eddy energy determine the relative group velocity at which the eddy energy is spreading out,and they can be used to evaluate the position of next new disturbance.The nonlinear advective fluxes influence primarily the phase speed and translation of the cyclones.The results in this paper facilitate to expanding the mechanism research on explosive cyclones and have great significance for predicting the explosive intensification and downstream disturbance growth.
