Séminaire
The northern North Atlantic is important globally both through its impact on the Atlantic Meridional Overturning Circulation (AMOC) and through widespread atmospheric teleconnections. The region has been shown to be potentially predictable a decade ahead with the skill of decadal predictions assessed against reanalyses of the ocean state.
Here, we show that prediction skill in this region is strongly dependent on the choice of reanalysis used for validation and describe the causes. We use fifteen state-of-the-art decadal prediction systems and two widely-used reanalysis products. These reanalyses separatelyestimate either temperature or salinity variability to be most influential in interannual density variability in the important Labrador Sea region. We show that skill in key metrics such as Labrador Sea density and the AMOC are largely independent of the detail of the prediction system. Instead, this skill is related to the similarity (or not) between the nature of interannual density variability in the underlying climate model and the chosen reanalysis.
The climate models used in these decadal predictions are also used in longer term climate projections raising further questions about the sensitivity of these projections to innate model characteristics.
Juliette.Mignot@locean-ipsl.upmc.fr