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.