The Climate-system Historical Forecast Project: do stratosphere-resolving models make better seasonal climate predictions in boreal winter?

• Published in: Quarterly Journal of the Royal Meteorological Society
• Main Authors: Calvo Fernández, Natalia, Iza San Juan, Maddalen, otros, .
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell 2016
• Subjects: Astrofísica; Astronomía; North Atlantic; North Atlantic oscillation
• Online Access: https://eprints.ucm.es/id/eprint/38405/; https://eprints.ucm.es/id/eprint/38405/1/calvofernandez34postprint.pdf; https://doi.org/10.1002/qj.2743

Using an international, multi-model suite of historical forecasts from the World Climate Research Programme (WCRP) Climate-system Historical Forecast Project (CHFP), we compare the seasonal prediction skill in boreal wintertime between models that resolve the stratosphere and its dynamics (high-top') and models that do not (low-top'). We evaluate hindcasts that are initialized in November, and examine the model biases in the stratosphere and how they relate to boreal wintertime (December-March) seasonal forecast skill. We are unable to detect more skill in the high-top ensemble-mean than the low-top ensemble-mean in forecasting the wintertime North Atlantic Oscillation, but model performance varies widely. Increasing the ensemble size clearly increases the skill for a given model. We then examine two major processes involving stratosphere-troposphere interactions (the El Niño/Southern Oscillation (ENSO) and the Quasi-Biennial Oscillation (QBO)) and how they relate to predictive skill on intraseasonal to seasonal time-scales, particularly over the North Atlantic and Eurasia regions. High-top models tend to have a more realistic stratospheric response to El Niño and the QBO compared to low-top models. Enhanced conditional wintertime skill over high latitudes and the North Atlantic region during winters with El Niño conditions suggests a possible role for a stratospheric pathway.