Japan Geoscience Union Meeting 2018

Presentation information

[EE] Evening Poster

A (Atmospheric and Hydrospheric Sciences) » A-OS Ocean Sciences & Ocean Environment

[A-OS10] Atlantic climate variability, and its global impacts and predictability

Sun. May 20, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Ingo Richter(JAMSTEC Japan Agency for Marine-Earth Science and Technology), Noel S Keenlyside (Geophysical Institute Bergen), Carlos R Mechoso (共同), Yoshimitsu Chikamoto(Utah State University)

[AOS10-P03] Prediction and projection with anomaly coupling

Francois Counillon1, Teferi Demissie2, Noel S Keenlyside3, *Shunya Koseki3, Thomas Toniazzo2, Yiguo Wang1, Lea Svendsen3, Ingo Bethke2 (1.Nansen Environmental and Remote Sensing Centre, 2.Uni Research Klima, 3.Geophysical Institute, University of Bergen)

Keywords:Seasonal prediction, Climate projection, Anomaly coupling

Current state-of-the-art models exhibit large climatological errors in the tropical Atlantic. Such unfavourable errors degrade the skill of climate predictions and introduce uncertainty in climate projections. Here we investigate (1) seasonal predictions and (2) climate projections with a standard and an anomaly coupled configurations of the Norwegian Climate Prediction Model (NorCPM). Correcting momentum and SST fields exchanged between oceanic and atmospheric models significantly reduces the climatological errors in the anomaly-coupled version. The mechanisms for equatorial Atlantic variability are better represented, but the variability is reduced in strength. This enhances the ability of the model to assimilate ocean observations in this region. A set of seasonal predictions with both standard and anomaly-coupled models indicates that together this leads to a significant improvement in the skill in predicting the Atlantic Niño mode.

Regarding climate projection, the standard model shows a rather uniform warming of around 2.5 degrees Celsius over the equatorial Atlantic. In contrast, the corrected model shows greater warming in the east, reaching 3 degrees Celsius in the eastern equatorial Atlantic. These changes are reflected in quite different rainfall response patterns. The standard model shows that climate change will lead to wetter conditions over central Africa and the western Atlantic, and drier conditions over eastern equatorial South America and the south equatorial Atlantic. The corrected model, in contrast, shows greater rainfall changes in the east and over central Africa, and less drying over South America. The underlying mechanisms will be discussed. This result illustrates the potential impact of mean state errors in future climate change in this region.