The Hiccup: a dynamical coupling process during the autumn transition in the Northern Hemisphere – similarities and differences to sudden stratospheric warmings

Matthias, V., Shepherd, T. G. ORCID: https://orcid.org/0000-0002-6631-9968, Hoffmann, P. and Rapp, M. (2015) The Hiccup: a dynamical coupling process during the autumn transition in the Northern Hemisphere – similarities and differences to sudden stratospheric warmings. Annales Geophysicae, 33 (2). pp. 199-206. ISSN 0992-7689 doi: 10.5194/angeo-33-199-2015

Abstract/Summary

Sudden stratospheric warmings (SSWs) are the most prominent vertical coupling process in the middle atmosphere, which occur during winter and are caused by the interaction of planetary waves (PWs) with the zonal mean flow. Vertical coupling has also been identified during the equinox transitions, and is similarly associated with PWs. We argue that there is a characteristic aspect of the autumn transition in northern high latitudes, which we call the “hiccup”, and which acts like a “mini SSW”, i.e. like a small minor warming. We study the average characteristics of the hiccup based on a superimposed epoch analysis using a nudged version of the Canadian Middle Atmosphere Model, representing 30 years of historical data. Hiccups can be identified in about half the years studied. The mesospheric zonal wind results are compared to radar observations over Andenes (69N,16E) for the years 2000–2013. A comparison of the average characteristics of hiccups and SSWs shows both similarities and differences between the two vertical coupling processes.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/39373
Identification Number/DOI	10.5194/angeo-33-199-2015
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	Copernicus Publications
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