Recent trends in the recurrence of North-Atlantic Atmospheric Circulation Patterns

• Main Authors: Yiou, Pascal, Cattiaux, Julien, Ribes, Aurélien, Vautard, Robert, Vrac, Mathieu
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)
• Format: Report
• Language: English
• Published: HAL CCSD 2017
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-01616483; https://hal.archives-ouvertes.fr/hal-01616483/document; https://hal.archives-ouvertes.fr/hal-01616483/file/SLP_trends_20170803_complexity.pdf

A few types of extreme climate events in the North Atlantic region, such as heatwaves, cold spells or high cumulated precipitation, are connected to the persistence of atmospheric circulation patterns. Understanding or attributing those extreme events requires assessing long-term trends of the atmospheric circulation. This paper presents a set of diagnostics of the intra and interannual recurrence of atmospheric patterns. Those diagnostics are devised to detect trends in the stability of the circulation and the return period of atmospheric patterns. We detect significant emerging trends in the winter circulation, pointing towards a potential increased predictability. No such signal seems to emerge in the summer. We find that the winter trends in the dominating atmospheric patterns and their recurrences do not depend of the patterns themselves.