West African Monsoon influence on the summer Euro-Atlantic circulation

• Published in: Geophysical Research Letters
• Main Authors: Gaetani, Marco, Pohl, Benjamin, Douville, Hervé, Fontaine, Bernard
• Other Authors: Istituto di Biometeorologia Roma (IBIMET), Consiglio Nazionale delle Ricerche (CNR), Centre de Recherches de Climatologie (CRC), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: envir; geo; North Atlantic; North Atlantic oscillation
• Online Access: https://doi.org/10.1029/2011GL047150; https://hal.archives-ouvertes.fr/hal-00582619/file/2011GL047150.pdf; https://hal.archives-ouvertes.fr/hal-00582619

International audience The West African Monsoon (WAM) influence on the interannual variability of the summer atmospheric circulation over North Atlantic and Europe is investigated over the period 1971-2000. A set of sensitivity experiments performed through the Arpege-Climat atmospheric general circulation model is analyzed, using the so-called "grid-point nudging" technique, where the simulated atmospheric fields in the WAM region are relaxed towards the ERA40 reanalysis. Observations confirm that a sizable part of the Euro-Atlantic circulation variability is related to the WAM, with anomalies of reinforced convection in the Sudan-Sahel region associated with positive North Atlantic Oscillation (NAO) phases and subsidence over eastern Mediterranean. The nudged simulations highlights the role of the WAM in driving the mid-latitudes circulation. A strong monsoon is related to high-pressure anomalies over the Azores and positive NAO phases.