Influence of synoptic weather patterns on solar irradiance variability in northern Europe

Observations have revealed strong variability of shortwave (SW) irradiance at Earth’s surface on decadal time scales, referred to as global dimming and brightening. Previous studies have attributed the dimming and brightening to changes in clouds and atmospheric aerosols. This study assesses the inf...

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Bibliographic Details
Published in:Journal of Climate
Main Authors: Parding, Kajsa, Liepert, Beate G., Hinkelman, Laura M., Ackerman, Thomas P., Dagestad, Knut-Frode, Olseth, Jan Asle
Format: Article in Journal/Newspaper
Language:English
Published: American Meteorological Society 2016
Subjects:
Atm/Ocean Structure/ Phenomena
Synoptic-scale processes
Physical Meteorology and Climatology
Climate variability
Shortwave radiation
Variability
Decadal variability
Multidecadal variability
Trends
North Atlantic
Online Access:https://hdl.handle.net/1956/15663
https://doi.org/10.1175/jcli-d-15-0476.1
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Summary:Observations have revealed strong variability of shortwave (SW) irradiance at Earth’s surface on decadal time scales, referred to as global dimming and brightening. Previous studies have attributed the dimming and brightening to changes in clouds and atmospheric aerosols. This study assesses the influence of atmospheric circulation on clouds and SW irradiance to separate the influence of ‘‘natural’’ SW variability from direct and, to some extent, indirect aerosol effects. The focus is on SW irradiance in northern Europe in summer and spring because there is little high-latitude SW irradiance during winter. As a measure of large-scale circulation the Grosswetterlagen (GWL) dataset, a daily classi- fication of synoptic weather patterns, is used. Empirical models of normalized SW irradiance are constructed based on the GWL, relating the synoptic weather patterns to the local radiative climate. In summer, a temporary SW peak in the 1970s and subsequent dimming is linked to variations in the synoptic patterns over Scandinavia, possibly related to a northward shift in the North Atlantic storm track. In spring, a decrease of anticyclonic and increase of cyclonic weather patterns over northern Europe contributes to the dimming from the 1960s to 1990. At many sites, there is also a residual SWirradiance trend not explained by the GWL model: a weak nonsignificant residual dimming from the 1950s or 1960s to around 1990, followed by a statistically significant residual brightening. It is concluded that factors other than the large-scale circulation (e.g., decreasing aerosol emissions) also play an important role in northern Europe. publishedVersion

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