Universität zu Köln

Pinto, Joaquim G., Ulbrich, Sven, Economou, Theodoros, Stephenson, David B., Karremann, Melanie K. and Shaffrey, Len C. (2016). Robustness of serial clustering of extratropical cyclones to the choice of tracking method. Tellus Ser. A-Dyn. Meteorol. Oceanol., 68. ABINGDON: TAYLOR & FRANCIS LTD. ISSN 1600-0870

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Abstract

Cyclone clusters are a frequent synoptic feature in the Euro-Atlantic area. Recent studies have shown that serial clustering of cyclones generally occurs on both flanks and downstream regions of the North Atlantic storm track, while cyclones tend to occur more regulary on the western side of the North Atlantic basin near Newfoundland. This study explores the sensitivity of serial clustering to the choice of cyclone tracking method using cyclone track data from 15 methods derived from ERA-Interim data (1979-2010). Clustering is estimated by the dispersion (ratio of variance to mean) of winter [December - February (DJF)] cyclone passages near each grid point over the Euro-Atlantic area. The mean number of cyclone counts and their variance are compared between methods, revealing considerable differences, particularly for the latter. Results show that all different tracking methods qualitatively capture similar large-scale spatial patterns of underdispersion and overdispersion over the study region. The quantitative differences can primarily be attributed to the differences in the variance of cyclone counts between the methods. Nevertheless, overdispersion is statistically significant for almost all methods over parts of the eastern North Atlantic and Western Europe, and is therefore considered as a robust feature. The influence of the North Atlantic Oscillation (NAO) on cyclone clustering displays a similar pattern for all tracking methods, with one maximum near Iceland and another between the Azores and Iberia. The differences in variance between methods are not related with different sensitivities to the NAO, which can account to over 50% of the clustering in some regions. We conclude that the general features of underdispersion and overdispersion of extratropical cyclones over the North Atlantic and Western Europe are robust to the choice of tracking method. The same is true for the influence of the NAO on cyclone dispersion.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Pinto, Joaquim G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ulbrich, Sven UNSPECIFIED UNSPECIFIED UNSPECIFIED Economou, Theodoros UNSPECIFIED UNSPECIFIED UNSPECIFIED Stephenson, David B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Karremann, Melanie K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Shaffrey, Len C. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-293501
DOI:	10.3402/tellusa.v68.32204
Journal or Publication Title:	Tellus Ser. A-Dyn. Meteorol. Oceanol.
Volume:	68
Date:	2016
Publisher:	TAYLOR & FRANCIS LTD
Place of Publication:	ABINGDON
ISSN:	1600-0870
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language OBJECTIVE IDENTIFICATION; ATLANTIC REGION; WINTER; CLIMATOLOGY; ERA-40; REANALYSIS; DISTRIBUTIONS; PERSPECTIVES; VARIABILITY; ALGORITHM Multiple languages Meteorology & Atmospheric Sciences; Oceanography Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/29350