Ville Maliniemi, Timo Asikainen, Kalevi Mursula, Decadal variability in the Northern Hemisphere winter circulation: Effects of different solar and terrestrial drivers, Journal of Atmospheric and Solar-Terrestrial Physics, Volume 179, 2018, Pages 40-54, ISSN 1364-6826, https://doi.org/10.1016/j.jastp.2018.06.012.
Decadal variability in the Northern Hemisphere winter circulation : effects of different solar and terrestrial drivers
|Author:||Maliniemi, Ville1; Asikainen, Timo1; Mursula, Kalevi1|
1ReSoLVE Centre of Excellence, Space Climate Research Unit, University of Oulu
|Online Access:||PDF Full Text (PDF, 7.4 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe2018111247911
|Publish Date:|| 2018-11-12
Northern Hemisphere winter circulation is affected by both solar and terrestrial forcings. El-Niño events and volcanic eruptions have been shown to produce a negative and a positive North Atlantic Oscillation (NAO) signature, respectively. Recent studies show a positive NAO signature related to both geomagnetic activity (proxy for solar wind driven particle precipitation) and sunspot activity (proxy for solar irradiance). Here the relative role of these four different drivers on the Northern Hemisphere wintertime circulation is studied using a statistical analysis of observational and reanalysis data during 1868–2014. The phase of the Quasi-Biennial Oscillation (QBO) is used to study driver signals in different stratospheric conditions. Moreover, the effects are separated for early/mid- and late winter. Our findings suggest a stratospheric mediation of the ENSO signal to the Atlantic side, which is delayed and modulated by the QBO unlike the signal in the Pacific side. The positive NAO by volcanic activity is preferentially obtained in the westerly QBO. We also find a substantial QBO modulation for geomagnetic activity and late winter sunspot activity, which favours a stratospheric pathway and the top-down mechanisms. However, signal in the North Pacific produced by early/mid-winter sunspot activity remain rather similar in different QBO phases and supports a direct forcing from the troposphere by the bottom-up sunspot mechanism.
Journal of atmospheric and solar-terrestrial physics
|Pages:||40 - 54|
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
115 Astronomy and space science
We acknowledge the financial support by the Academy of Finland to the ReSoLVE Center of Excellence (project no. 272157) as well as to projects no. 257403 and 292712.
|Academy of Finland Grant Number:||
272157 (Academy of Finland Funding decision)
257403 (Academy of Finland Funding decision)
292712 (Academy of Finland Funding decision)
© 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).