Recurrent Synoptic-Scale Rossby Wave Patterns and Their Effect on the Persistence of Cold and Hot Spells

Röthlisberger, Matthias; Frossard, Linda; Bosart, Lance F.; Keyser, Daniel; Martius, Olivia (2019). Recurrent Synoptic-Scale Rossby Wave Patterns and Their Effect on the Persistence of Cold and Hot Spells. Journal of Climate, 32(11), pp. 3207-3226. American Meteorological Society 10.1175/JCLI-D-18-0664.1

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The persistence of surface weather during several recent high-impact weather events has been pivotal in generating their societal impact. Here we examine Hovmöller diagrams of the 250-hPa meridional wind during several periods with particularly persistent surface weather and find a common pattern in these Hovmöller diagrams. This pattern can be characterized as a “recurrent Rossby wave pattern” (RRWP), arising from multiple transient synoptic-scale wave packets. During such RRWP periods, individual troughs and ridges forming the wave packets repeatedly amplify in the same geographical region. We discuss the synoptic evolution of two RRWP periods, in February–March 1987 and July–August 1994, and illustrate how the recurrence of the transient wave packets led to unusually long-lasting cold and hot spells, which occurred simultaneously in several regions, each separated by roughly one synoptic wavelength. Furthermore, a simple index termed R is proposed to identify RRWPs, which is based on both a time and wavenumber filter applied to conventional Hovmöller diagrams. A Weibull regression analysis then shows that large values of R are statistically significantly linked to increased durations of winter cold and summer hot spells in large areas of the Northern Hemisphere midlatitudes. Traditionally, persistent high-impact surface weather has often been linked to the occurrence of proximate atmospheric blocking. In contrast to blocking, RRWPs affect persistent surface temperature anomalies over multiple synoptic wavelengths. We therefore argue that, in addition to blocking, RRWPs should be considered as an important flow feature leading to persistent high-impact surface weather.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geography > Physical Geography > Unit Impact
08 Faculty of Science > Institute of Geography > Physical Geography

UniBE Contributor:

Röthlisberger, Matthias; Frossard, Linda and Romppainen-Martius, Olivia

Subjects:

500 Science > 550 Earth sciences & geology
900 History > 910 Geography & travel

ISSN:

0894-8755

Publisher:

American Meteorological Society

Projects:

[245] Mobiliar Lab für Naturrisiken Official URL

Language:

English

Submitter:

Hélène Christine Louise Barras

Date Deposited:

29 Jan 2020 08:04

Last Modified:

15 Jul 2021 14:12

Publisher DOI:

10.1175/JCLI-D-18-0664.1

Uncontrolled Keywords:

Blocking; Planetary waves; Rossby waves; Stationary waves; Synoptic climatology; Extreme events

BORIS DOI:

10.7892/boris.138761

URI:

https://boris.unibe.ch/id/eprint/138761

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