Objective Identification of Cyclones and Their Circulation Intensity, and Climatology

Abstract

An updated procedure for objective identification and tracking of surface cyclones from gridded analyses is described. Prior smoothing of the raw data with a constant radius spatial filter is used to remove distortions related to the particular grid configuration used and to consistently admit a known scale of disturbance over the domain. Pitfalls of using central pressure or vorticity to infer cyclone intensity are illustrated, and a procedure for obtaining a more realistic areal measure of circulation is described. An automated selection procedure for storms having specific properties is outlined. Case selection is by computer search of a database of cyclone tracks, obtained from an application of the cyclone finding and tracking procedure to an extended series of gridded mean sea level pressure analyses.