A diagnostic study of an apparent instant occlusion” cyclogenesis event during ERICA

Abstract

Abstract The phenomenon commonly known to operational mereorologists as an “instant occlusion” is a signature in satellite imagery that indicates cyclogenesis. The process consists of the merging of a cloud mass associated with an Arctic vortex with a pre‐existing baroclinic zone resulting in a system that resembles a fully occluded system. Although the process may be familiar to operational meteorologists, the details of the structure and life cycle are not well understood. Although some work has been conducted on instant occlusions, most of the studies have involved cases in the eastern Atlantic and eastern Pacific. No such feature has ever been studied in Canada. A well documented instant occlusion case (which also happened to be a rapid deepener) occurred during the ERICA field experiment. Observations indicate that the merging process resulted in increased baroclinicity in the system as well as an interesting frontal structure. The influence of local topographic features of the eastern seaboard was i...