Deep currents construct a circulation that spans the whole global ocean. They play an active role in the Earth’s climate system, for example, during glaciations, and they moderate anthropogenic climate change. Deep currents influence climate by sequestering and transporting heat, salt, and carbon around the planet. Yet compared to surface currents, which can be observed from space, they remain mysterious. This talk will discuss aspects of the deep circulation in the North Atlantic and Arctic Oceans, particularly the Denmark Strait Overflow between Greenland and Iceland. This deep current is part of the Atlantic Meridional Overturning Circulation (AMOC), which is implicated in past climate fluctuations and future climate change. Modern coupled climate models used for climate projections fail to capture some essential processes controlling the Denmark Strait Overflow. The overflow involves mixing during intense events that last O(1–10) hours. The mixing transforms the deep water properties, which are then maintained by the deep flow for O(10–100) years across planetary distances. This wide separation of scales poses serious challenges to observing or modeling deep currents. Yet modern ultra-high-resolution regional ocean circulation models are increasingly realistic and revealing of these flows.
Arranged date for the seminar talk: Aug 15, 2022 at 14:15 PM. Venue: Bjerknes lecture room 4020, Jahnebakken 5
Tom Haine is a Professor in the department of Earth & Planetary Sciences at Johns Hopkins University. His training is in physics and oceanography. He studies and teaches ocean circulation and dynamics, and the ocean’s role in Earth’s climate. Particular interests are the North Atlantic and Arctic Oceans, and their rotating-stratified fluid dynamics, which are exquisite. His approaches are computational and theoretical, although he collaborates with observational oceanographers and has participated in twelve research expeditions. In 2019 he co-authored (with Barry Klinger) a graduate level textbook, entitled Ocean Circulation in Three Dimensions (Cambridge University Press).