Application of Excess Rotation Kinetic Energy in Distinguishing the Tornadic and Non-Tornadic Mesocyclones in China

Doppler radar mesocyclone algorithm is designed to detect mesocyclones with diameters from 1.8 to 9.2 km(1～5 n mi).Majority strong tornadoes occur in mesocyclone with supercell,but not all of the mesocyclones can develop into tornadoes.In this paper,the concept of the Excess Rotational Kinetic Energy(ERKE) of a mesocyclone core is introduced.Combining with mesocyclone algorithm and radial velocity products,the temporal variation features of ERKE and weighted height are analyzed in some tornadic and non-tornadic mesocyclone lifetime,and the initial ERKE value and weighted height of other cases are also calculated.The results show that the ERKE are generally larger and the weighted heights are relatively lower in tornadic mesocyclone,comparing with non-tornadic mesocyclone.Furthermore,the tornadic and non-tornadic mesocyclones in the low-and mid-troposphere layers can be distinguished by the initial ERKE value of mesocyclone with supercell storm effectively,which can be used as the quantificational identification indicator of tornadic mesocyclone.Finally,the ERKE diagram is given on the basis of the climatological mature mesocyclone in China.From the diagram,ERKE value can be quickly gained via the values of rotational speed and the mesocyclone radius.