1400 years of extreme precipitation patterns over the Mediterranean French Alps and possible forcing mechanisms

A 1400-year record of extreme precipitation patterns over the Mediterranean French Alps reveals distinct phases of flood frequency, with low activity during the Medieval Warm Period and increased intensity during the Little Ice Age. The study, based on sediment analysis from Lake Allos, identifies ~160 graded layers as flood deposits, corroborated by historical records. These events are linked to intense meso-scale precipitation, with no evidence of changes in erosion processes since the MWP. High-frequency oscillations in flood frequency correlate with solar activity and autumnal North Atlantic Oscillation (NAO) patterns. Additionally, flood events in Allos were out of phase with those in the Cévennes but in phase with eastern Spain, suggesting regional atmospheric circulation shifts over the northwestern Mediterranean.

Wilhelm, B., Arnaud, F., Sabatier, P., Crouzet, C., Brisset, E., Chaumillon, E., Disnar, J.-R., Guiter, F., Malet, E., Reyss, J.-L., Tachikawa, K., Bard, E., & Delannoy, J.-J. (2012). 1400 years of extreme precipitation patterns over the Mediterranean French Alps and possible forcing mechanisms. Quaternary Research, 78(1), 1–12. https://doi.org/10.1016/j.yqres.2012.03.003