Solar wind dynamic pressure effect on planetary wave propagation and synoptic-scale Rossby wave breaking

Lu, Hua; Franzke, Christian; Martius, Olivia; Jarvis, Martin J.; Phillips, Tony (2013). Solar wind dynamic pressure effect on planetary wave propagation and synoptic-scale Rossby wave breaking. Journal of Geophysical Research: Atmospheres, 118(10), pp. 4476-4493. American Geophysical Union 10.1002/jgrd.50374

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We provide statistical evidence of the effect of the solar wind dynamic pressure (Psw) on the northern winter and spring circulations. We find that the vertical structure of the Northern Annular Mode (NAM), the zonal mean circulation, and Eliassen-Palm (EP)-flux anomalies show a dynamically consistent pattern of downward propagation over a period of ~45 days in response to positive Psw anomalies. When the solar irradiance is high, the signature of Psw is marked by a positive NAM anomaly descending from the stratosphere to the surface during winter. When the solar irradiance is low, the Psw signal has the opposite sign, occurs in spring, and is confined to the stratosphere. The negative Psw signal in the NAM under low solar irradiance conditions is primarily governed by enhanced vertical EP-flux divergence and a warmer polar region. The winter Psw signal under high solar irradiance conditions is associated with positive anomalies of the horizontal EP-flux divergence at 55°N–75°N and negative anomalies at 25°N–45°N, which corresponds to the positive NAM anomaly. The EP-flux divergence anomalies occur ~15 days ahead of the mean-flow changes. A significant equatorward shift of synoptic-scale Rossby wave breaking (RWB) near the tropopause is detected during January–March, corresponding to increased anticyclonic RWB and a decrease in cyclonic RWB. We suggest that the barotropic instability associated with asymmetric ozone in the upper stratosphere and the baroclinic instability associated with the polar vortex in the middle and lower stratosphere play a critical role for the winter signal and its downward propagation.

Item Type:

Journal Article (Original Article)

Division/Institute:

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

UniBE Contributor:

Romppainen-Martius, Olivia

Subjects:

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

ISSN:

2169-897X

Publisher:

American Geophysical Union

Language:

English

Submitter:

Monika Wälti-Stampfli

Date Deposited:

19 Jun 2014 08:23

Last Modified:

05 Dec 2022 14:29

Publisher DOI:

10.1002/jgrd.50374

BORIS DOI:

10.7892/boris.43225

URI:

https://boris.unibe.ch/id/eprint/43225

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