Limitations of the potential predictability of meridional mass and heat transports in the North Atlantic

Abstract

AbstractThe climatological relevance of the Atlantic meridional overturning circulation (AMOC) stems from its capability to transport heat meridionally. The variability of AMOC and the meridional heat transport (MHT) are intimately linked, but not interchangeable. Here we ask to what extend AMOC's predictability may be used as a proxy for MHT's predictability. We find that the geostrophic parts of MHT and AMOC show similar potential predictability (0∘–45∘N), which originates from the potential predictability of the density field at the western boundary (above 1700 m). Maximum timescales of potential predictability are found for both MHT's and AMOC's geostrophic parts between the subpolar and the subtropical gyre, while meridionally propagating density anomalies at the western boundary limit the potential predictability north and south of the gyre boundary. The inference of MHT predictability from AMOC predictability is thus limited to the geostrophic parts of MHT and AMOC, and particularly adequate at the gyre boundary.