Universität zu Köln

Ludwig, Patrick ORCID: 0000-0003-3655-7890, Pinto, Joaquim G., Hoepp, Simona A., Fink, Andreas H. ORCID: 0000-0002-5840-2120 and Gray, Suzanne L. (2015). Secondary Cyclogenesis along an Occluded Front Leading to Damaging Wind Gusts: Windstorm Kyrill, January 2007. Mon. Weather Rev., 143 (4). S. 1417 - 1438. BOSTON: AMER METEOROLOGICAL SOC. ISSN 1520-0493

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Abstract

Windstorm Kyrill affected large parts of Europe in January 2007 and caused widespread havoc and loss of life. In this study the formation of a secondary cyclone, Kyrill II, along the occluded front of the mature cyclone Kyrill and the occurrence of severe wind gusts as Kyrill II passed over Germany are investigated with the help of high-resolution regional climate model simulations. Kyrill underwent an explosive cyclogenesis south of Greenland as the storm crossed poleward of an intense upper-level jet stream. Later in its life cycle secondary cyclogenesis occurred just west of the British Isles. The formation of Kyrill II along the occluded front was associated (i) with frontolytic strain and (ii) with strong diabatic heating in combination with a developing upper-level shortwave trough. Sensitivity studies with reduced latent heat release feature a similar development but a weaker secondary cyclone, revealing the importance of diabatic processes during the formation of Kyrill II. Kyrill II moved farther toward Europe and its development was favored by a split jet structure aloft, which maintained the cyclone's exceptionally deep core pressure (below 965 hPa) for at least 36 h. The occurrence of hurricane-force winds related to the strong cold front over north and central Germany is analyzed using convection-permitting simulations. The lower troposphere exhibits conditional instability, a turbulent flow, and evaporative cooling. Simulation at high spatiotemporal resolution suggests that the downward mixing of high momentum (the wind speed at 875 hPa widely exceeded 45ms(-1)) accounts for widespread severe surface wind gusts, which is in agreement with observed widespread losses.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Ludwig, Patrick UNSPECIFIED orcid.org/0000-0003-3655-7890 UNSPECIFIED Pinto, Joaquim G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoepp, Simona A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fink, Andreas H. UNSPECIFIED orcid.org/0000-0002-5840-2120 UNSPECIFIED Gray, Suzanne L. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-404324
DOI:	10.1175/MWR-D-14-00304.1
Journal or Publication Title:	Mon. Weather Rev.
Volume:	143
Number:	4
Page Range:	S. 1417 - 1438
Date:	2015
Publisher:	AMER METEOROLOGICAL SOC
Place of Publication:	BOSTON
ISSN:	1520-0493
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MOIST DEFORMATION FRONTOGENESIS; NUMERICAL WEATHER PREDICTION; REGIONAL CLIMATE MODEL; NORTH-ATLANTIC; LIFE-CYCLE; WAVE STABILITY; VORTICITY; CYCLONES; PARAMETERIZATION; PERSPECTIVE Multiple languages Meteorology & Atmospheric Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/40432