Exploring the relationships of North Atlantic sea surface temperature anomalies at high and low latitudes with North Atlantic Oscillation variability over recent centuries from paleoclimate proxy data

Climate model- and modern observation-based studies have hypothesized a mechanistic link between decadal to multidecadal-scale high latitude Atlantic sea surface temperature (SST) anomalies, atmospheric pressure gradients in the North Atlantic sector (NAO), and Atlantic Meridional Overturning Circulation (AMOC) variability. However, modern observations of decadal to multidecadal SST anomalies display a strong signal in the tropics. It is unclear if this is because the multidecadal SST anomalies observed in the tropical Atlantic are passively responding to atmospheric noise and not mechanistically related to AMOC, or if the models are not adequately capturing the low-latitude processes that lead to coherent SST anomalies in low and high latitudes. Part of the problem is separating the coherent forced global warming signal from the internal variability. In this study, we explore existing paleoclimate proxy data that contain signals of the variability of the Earth's climate system before anthropogenic perturbations. We test the coherence of SST anomalies in the northern tropical and high latitude Atlantic and further characterize the relationships between a NAO proxy and the SST anomalies at high and low latitudes. Initial results indicate the tropical SSTs may lead both the NAO and high latitude SST on decadal scales, indicating an active role for the tropics in Atlantic multidecadal variability, but further work is needed to conform this result. This project is the product of a graduate-level issue study course in the Marine Estuarine and Environmental Science Program at the University of Maryland Center for Environmental Science. The course focused on making connections between modern and paleoclimate observations of AMOC.