The North Atlantic Re-emergence Phenomenon in a Coupled Large-ensemble Climate Model

The North Atlantic re-emergence phenomenon is an intermittent event in which winter sea surface temperature (SST) anomalies subduct under the seasonal thermocline and re-emerge the following winter when the mixed layer deepens. This means that the ocean acts as a `memory' for North Atlantic winter climate on interannual scales. Previous studies of the North Atlantic re-emergence phenomenon are limited by short observational records, forced-ocean models, or poor resolution. The CANARI Large Ensemble (65 years x 40 members of the UK Met Office Climate Model (HadGEM3) at N216 atmosphere and 1/4 degree ocean resolution) provides an opportunity to robustly analyse these events and their mechanisms. We have tested existing mechanistic theories, and are answering other pertinent questions, such as; does stratospheric preconditioning occur and can we harness predictability from it? Are there multi-year impacts and cascading effects? Can we quantify the relationship between Atlantic meridional overturning circulation (AMOC) and re-emergence?