Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
On the Nonlinearity of Winter Northern Hemisphere Atmospheric Variability
Stockholm University, Faculty of Science, Department of Meteorology .
Stockholm University, Faculty of Science, Department of Meteorology .ORCID iD: 0000-0003-0698-2677
2019 (English)In: Journal of the Atmospheric Sciences, ISSN 0022-4928, E-ISSN 1520-0469, Vol. 76, no 1, p. 333-356Article in journal (Refereed) Published
Abstract [en]

Nonlinearity in the Northern Hemisphere’s winter time atmospheric flow is investigated from both an intermediate complexity model of the extratropics and reanalyses. A long simulation is obtained using a three-level quasi-geostrophic model on the sphere. Kernel empirical orthogonal functions (EOFs), which help delineate complex structures, are used along with the local flow tendencies. Two fixed points are obtained, which are associated with strong bimodality in two-dimensional kernel PC space in consistency with conceptual low-order dynamics. The regimes reflect zonal and blocked flows. The analysis is then extended to ERA-40 and JRA-55 reanalyses using daily sea level pressure (SLP) and geopotential heights in the stratosphere (20-hPa) and troposphere (500-hPa). In the stratosphere, trimodality is obtained, representing disturbed, displaced and undisturbed states of the winter polar vortex. In the troposphere the probability density functions (PDFs), for both fields, within the two-dimensional (2D) kernel EOF space are strongly bimodal. The modes correspond broadly to opposite phases of the Arctic Oscillation with signature of negative North Atlantic Oscillation (NAO). Over the North Atlantic/European sector a trimodal PDF is also obtained with two strong and one weak modes. The strong modes are associated, respectively, with the north (or +NAO) and south (or –NAO) positions of the eddy-driven jet strteam. The third weak mode is interpreted as a transition path between the two positions. A climate change signal is also observed in the troposphere of the winter hemisphere, resulting in an increase (decrease) in the frequency of the polar high (low) consistent with an increase of zonal flow frequency.

Place, publisher, year, edition, pages
2019. Vol. 76, no 1, p. 333-356
Keywords [en]
Nonlinear dynamics
National Category
Meteorology and Atmospheric Sciences
Research subject
Atmospheric Sciences and Oceanography
Identifiers
URN: urn:nbn:se:su:diva-162268DOI: 10.1175/JAS-D-18-0182.1ISI: 000454864600002OAI: oai:DiVA.org:su-162268DiVA, id: diva2:1265534
Available from: 2018-11-24 Created: 2018-11-24 Last updated: 2019-02-04Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full text

Search in DiVA

By author/editor
Hannachi, AbdelIqbal, Waheed
By organisation
Department of Meteorology
In the same journal
Journal of the Atmospheric Sciences
Meteorology and Atmospheric Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 83 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf