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dc.contributor.authorGuttu, Sigmund
dc.contributor.authorOrsolini, Yvan
dc.contributor.authorStordal, Frode
dc.contributor.authorOtterå, Odd Helge
dc.contributor.authorOmrani, Nour-Eddine
dc.contributor.authorTartaglione, Nazario
dc.contributor.authorVerronen, Pekka T.
dc.contributor.authorRodger, Craig J.
dc.contributor.authorClilverd, Mark A.
dc.description.abstractObservational studies suggest that part of the North Atlantic Oscillation (NAO) variability may be attributed to the spectral ultra-violet (UV) irradiance variations associated to the 11-year solar cycle. The observed maximum surface pressure response in the North Atlantic occurs 2–4 years after solar maximum, and some model studies have identified that atmosphere–ocean feedbacks explain the multi-year lag. Alternatively, medium-to-high energy electron (MEE) precipitation, which peaks in the declining phase of the solar cycle, has been suggested as a potential cause of this lag. We use a coupled (ocean–atmosphere) climate prediction model and a state-of-the-art MEE forcing to explore the respective roles of irradiance and MEE precipitation on the NAO variability. Three decadal ensemble experiments were conducted over solar cycle 23 in an idealized setting. We found a weak ensemble-mean positive NAO response to the irradiance. The simulated signal-to-noise ratio remained very small, indicating the predominance of internal NAO variability. The lack of multi-annual lag in the NAO response was likely due to lagged solar signals imprinted in temperatures below the oceanic mixed-layer re-emerging equatorward of the oceanic frontal zones, which anchor ocean–atmosphere feedbacks. While there is a clear, yet weak, signature from UV irradiance in the atmosphere and upper ocean over the North Atlantic, enhanced MEE precipitation on the other hand does not lead to any systematic changes in the stratospheric circulation, despite its marked chemical signatures.en_US
dc.rightsNavngivelse 4.0 Internasjonal*
dc.titleImpacts of UV Irradiance and Medium-Energy Electron Precipitation on the North Atlantic Oscillation during the 11-Year Solar Cycleen_US
dc.typeJournal articleen_US
dc.typePeer revieweden_US
dc.rights.holderCopyright 2021 by the authorsen_US
dc.relation.projectNILU - Norsk institutt for luftforskning: 116104en_US
dc.relation.projectNorges forskningsråd: 255276en_US
dc.identifier.citationAtmosphere. 2021, 12 (8), 1029.en_US

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