Decadal-scale variability in hazardous winds in northern Switzerland since end of the 19th century

The decadal-scale variability in winter hazardous winds in northern Switzerland from 1871 to present is investigated in the Twentieth Century Reanalysis (20CR). Independent wind speed measurements taken at Zurich climate station show that the interannual and decadal variability in hazardous winds in northern Switzerland is realistically represented in the 20CR. Both time series exhibit pronounced decadal-scale variability with periods between approximately 36 and 47 years. At these periodicities, the hazardous wind variability in northern Switzerland is positively correlated with the variability in the North Atlantic Oscillation, however the strength and statistical significance of their co-variability varies over time.

Sea surface temperature and sea ice variability in the subpolar North Atlantic from explosive volcanism of the late thirteenth century

In this study, we use IP and alkenone biomarker proxies to document the subdecadal variations of sea ice and sea surface temperature in the subpolar North Atlantic induced by the decadally paced explosive tropical volcanic eruptions of the second half of the thirteenth century. The short- and long-term evolutions of both variables were investigated by cross analysis with a simulation of the IPSL-CM5A LR model. Our results show short-term ocean cooling and sea ice expansion in response to each volcanic eruption. They also highlight that the long response time of the ocean leads to cumulative surface cooling and subsurface heat buildup due to sea ice capping. As volcanic forcing relaxes, the surface ocean rapidly warms, likely amplified by subsurface heat, and remains almost ice free for several decades