Mid-Holocene NAO: A PMIP2 model intercomparison

• Published in: Geophysical Research Letters
• Main Authors: Gladstone, RM, Ross, I, Valdes, PJ, Abe-Ouchi, A, Braconnot, P, Brewer, S, Kageyama, M, Kitoh, M, Legrande, A, Marti, O, Ohgaito, R, Otto-Bliesner, B, Peltier, W, Vettoretti, G
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2005
• Subjects: North Atlantic; North Atlantic oscillation
• Online Access: https://hdl.handle.net/1983/f7387565-badc-4a7e-be0a-3f1d31b8eff4; https://research-information.bris.ac.uk/en/publications/f7387565-badc-4a7e-be0a-3f1d31b8eff4; https://doi.org/10.1029/2005GL023596

The mid-Holocene ( 6000 years before present) North Atlantic 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. The mid-Holocene ( 6000 years before present) North Atlantic 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.