Mixing and geometry in the North Atlantic Meridional Overturning Circulation

Abstract

Vertical motions across the ocean are central to processes, like CO2 fixation, heat removal or pollutant transport, which are essential to the Earth's climate. This work explores 3D conveyor routes associated with the Atlantic Meridional Overturning Circulation (AMOC). Our findings show the geometry of mixing structures in the upper and deep ocean layers by means of Lagrangian Coherent Structures. This tool identifies among others, zones linked to vertical transport and characterizes vertical transport time scales. We focus the study in two regions. The first one is the Flemish Cap region, a zone of interaction between the major AMOC components, where our analysis identifies a domain of deep waters that ascend very rapidly to the ocean surface. The second one is the Irminger Sea, where our analysis confirms the existence of a downwelling zone, and reveals a previously unreported upwelling connection between very deep waters and the ocean surface.

RB acknowledges support of a CSIC JAE intro fellowship. AMM and GGS acknowledge the support of a CSIC PIE project Ref. 202250E001 and from Grants PID2021-123348OB-I00 funded by MCIN/AEI/10.13039/501100011033/ and by FEDER A way to make Europe. AMM is an active member of the CSIC Interdisciplinary Thematic Platform POLARCSIC and TELEDETECT and acknowledges the support from Grant EIN2020-112235 funded by MCIN/ AEI/10.13039/501100011033/and by the European Union NextGenerationEU/ PRTR. JC also acknowledges the support of the RyC project RYC2018-025169, the Spanish Grant PID2020-114043GB-I00 and PID2021-122954NB-I00 and the “2022 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation.

Peer Reviewed

Postprint (published version)