TROPICAL CYCLONE GENESIS EFFICIENCY:MID-LEVEL VERSUS BOTTOM VORTEX

Cloud resolving Weather Research and Forecasting(WRF)model simulations are used to investigate tropical cyclone(TC)genesis efficiency in an environment with a near bottom vortex(EBV)and an environment with a mid-level vortex(EMV).Sensitivity experiments show that the genesis timing depends greatly on initial vorticity vertical profiles.The larger the initial column integrated absolute vorticity,the greater the genesis efficiency is.Given the same column integrated absolute vorticity,a bottom vortex has higher genesis efficiency than a mid-level vortex.A common feature among these experiments is the formation of a mid-level vorticity maximum prior to TC genesis irrespective where the initial vorticity maximum locates.Both the EMV and EBV scenarios share the following development characteristics:1)a transition from non-organized cumulus-scale(~5 km)convective cells into an organized meso-vortex-scale(~50 to 100 km)system through upscale cascade processes,2)the establishment of a nearly saturated air column prior to a rapid drop of the central minimum pressure,and 3)a multiple convective-stratiform phase transition.A genesis efficiency index(GEI)is formulated that includes the following factors:initial column integrated absolute vorticity,vorticity at top of the boundary layer and vertically integrated relative humidity.The calculated GEI reflects well the simulated genesis efficiency and thus may be used to estimate how fast a tropical disturbance develops into a TC.

COMPARISON OF THE STRUCTURAL CHARACTERISTICS OF DEVELOPED VERSUS UNDEVELOPED MID-LEVEL VORTEXES

Using the NCEP 1°×1°reanalysis data,several obvious differences of the structural characteristics of developed versus undeveloped mid-level vortexes are studied.First,the central vorticity of the developed mid-level vortex increases towards higher levels while the undeveloped one decreases.The low-level convergence structure maintains well in the developed mid-level vortex whereas the undeveloped one does badly.Second,on the one hand,according to the symmetric analysis,the horizontal wind field and wind vertical section of the developed mid-level vortex are well symmetric while those of the undeveloped one are less symmetric.Meanwhile,weak wind vertical shear help the developed mid-level vortex to establish a warm core in upper-and mid-levels of the troposphere.On the other hand,according to the balance analysis,better balance between wind and pressure is shown in the mid-and lower-levels of the troposphere of the developed mid-level vortex than in those of the undeveloped vortex.Third,positive anomaly of potential vorticity is enhanced and developed in the vertical direction of the developed vortex.However,the undeveloped vortex weakens with a weak positive anomaly.

Mid-level car campaign, are you all right?

Public sources show a lot of locally-owned brands are going to roll out mid-level cars: Chery, BYD and JAC in this year, Great Wall, Lifan, Changfeng and Chang'in the next year or so.

The particularities and the research missions of the educational theories

Starting from the analysis of the theoretical drawbacks of classical pedagogy stretching from Johann Friedrich Herbart to John Dewey,this paper advocates that educational research in China in the new century should take on a theory mission that calls for the classification of the knowledge of educational theory and the definition of its theoretical formation.Instead of a single theory,the formation of the new theories should be a theoretical continuum,which consists of three parts that are not isolated but interconnected and interactive.The first one is a general theory that is conformed by abstract propositions and has a reflective function.The second is a mid-level theory that presents the requirements of the methodology,and the third one is a micro-theory that displays detailed experiences.The paper finally presents the structure of the problems of educational theory and its unique value.It then concludes that progress in educational theory implicates progress in the understanding of the conditions for education.