Multi-proxy documentation of past storm events in a mid-latitude coastal environment

Résumé En

As extreme events are expected to become more frequent, the combination of different environmental approaches is essential to apprehend the evolution of their occurrences. This requires a substantial time depth with a robust record of such events. This work presents a combined approach crossing historical, dendrochronological and meteorological indicators to document storm occurrences from a primary maritime pine (Pinus pinaster) tree-ring dataset extracted at Pointe d’Arcay coastal environment (western France), covering the period 1964 to 2019. From the analyses of tree-ring patterns, we identified fourteen years during which the growth of trees was strongly disturbed by significant storm winds, including those associated with Lothar and Martin (1999), Xynthia (2010), Joachim (2012), Klaus and Quinten (2009) storm systems. The analysis of wind parameters (intensity, direction, and persistence) based on ERA5 reanalysis showed a ∼85 % fit between historical archives, dendrochronology, and meteorological data. As trees were sampled through the main tilting axis, tree rings revealed the impacts of windstorms originating from only one direction. The wind intensity appears to be an important factor to produce tree-ring eccentric growth; however, it does not explain all eccentric growth cases. Thus, we analyzed wind persistence as a potential parameter influencing dendrochronological signals recorded during years without storms. We demonstrate that dendrochronology, with the support of meteorological, historical and reanalysis wind data, accurately documents storm winds in a mid-latitude coastal environment. Tree-ring archives are effective to estimate windy phases of extratropical storms and can be used to understand past storm activity with trees older than the available meteorological records.