Mid-Holocene NAO:A PMIP2 model intercomparison

• Published in: Geophysical Research Letters
• Main Authors: Gladstone, R. M., Ross, I., Valdes, P. J., Abe-Ouchi, A., Braconnot, P., Brewer, S., Kageyama, M., Kitoh, A., Legrande, A., Marti, O., Ohgaito, R., Otto-Bliesner, B., Peltier, W. R., Vettoretti, G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2005
• Subjects: North Atlantic
• Online Access: https://research.ulapland.fi/fi/publications/3947b3dc-3fc2-47bd-8373-994b06845e60; https://doi.org/10.1029/2005GL023596; http://www.scopus.com/inward/record.url?scp=26844559985&partnerID=8YFLogxK; http://www.scopus.com/inward/citedby.url?scp=26844559985&partnerID=8YFLogxK

The mid-Holocene (6000 years before present) North Atantic Oscillation (NAO) from nine models in the Paleoclimate Modeling Intercomparison Project Phase 2 is studied, primarily through principal component analysis of winter time North Atlantic sea level pressure (SLP). Modeled mid-Holocene NAO and mean SLP show small changes compared to pre-industrial control runs, with a shift in mean state towards a more positive NAO regime for three of the models. Modeled NAO variability shows little change, with a small increase for some models in the fraction of time spent in the NAO-negative phase during the mid-Holocene. Proxy based reconstructions of the NAO indicate a more positive NAO regime compared to present day during the mid- Holocene. We hypothesise that there was a small NAO+ like shift in mean state during the mid-Holocene.