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Research project Oceanic and Atmospheric Overturning Circulation

By studying the oceanic and atmospheric overturning circulation it is possible to for example track the heat, salt and moisture exchanges between the low and high latitudes.

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Theme

Contact person at SU

Kristofer Döös

Professor of Climate modeling

Department of Meteorology

08-16 17 34

073-913 16 51

doos@misu.su.se

Overview

Project period

01-01-2020 - 31-12-2024

Responsible

Department of Meteorology

Participants

Bolin Centre for Climate Research

Research subjects

Oceanography

Status

Ongoing

Funding

Swedish Research Council

Research groups

The North Atlantic and Arctic Oceans

In the North Atlantic, a mighty current system conveys, via the Gulf Stream and North Atlantic Current, warm surface waters to northerly subpolar areas where deep water is formed. This current system, which is an important link in the global ocean circulation connecting the Atlantic and Pacific Oceans, also carries warm Atlantic water into the Arctic Ocean.

Ocean and clouds. Photo: Johan Nilsson/MISU/Stockholm University

FIG. 1. The global air-mass overturning stream function for the atmosphere (top panel) and global water-mass overturning stream function for the ocean (bottom panel) simulated by an Earth System model. Arrows indicate the mass transport direction. All transports are in Sv (109kg/s). Image: K.Döös/MISU/Stockholm University

FIG. 2a. Conventional longitude-latitude map. Atmospheric water trajectories started at the sea surface at evaporation points and ended at the surface at precipitation points. Note that these are water trajectories not air trajectories simulated by TRACMASS with a new water mass conservation method. Image: K.Döös/MISU/Stockholm University

FIG. 2b. Trajectories in the temperature-humidity space, an alternative way to describe the overturning. Atmospheric water trajectories started at the sea surface at evaporation points and ended at the surface at precipitation points. Note that these are water trajectories not air trajectories simulated by TRACMASS with a new water mass conservation method. Image: K.Döös/MISU/Stockholm University

Figure 1 shows how this is viewed by cells, which transport water and air in the coupled ocean-atmosphere system simulated with the Earth system model EC-Earth.

An alternative way to study the overturning circulation is with Lagrangian trajectories, which makes it possible to follow a given water or air mass from a given region to another. For this we have developed the trajectory model TRACMASS (www.tracmass.org) for both air masses and water masses.

In Figure 2a and 2b we have followed water in the atmosphere from evaporation regions in the Tropical Pacific to the precipitation points.

Project description

Project title: Inter-ocean exchange of freshwater and heat through both the ocean and the atmosphere in a warmer climate.

Funded by: Swedish Research Council
Funding period: 2020-2024
Project ID: 2019-03574

Project members

Project managers

Kristofer Döös

Professor of Climate modeling

Department of Meteorology

08-16 17 34

073-913 16 51

doos@misu.su.se

Members

Aitor Aldama Campino

PhD

Formerly at the Department of Meteorology, Stockholm University

Dipanjan Dey

PhD

Formerly at the Department of Meteorology, Stockholm University

Joakim Kjellsson

PhD

Formerly at the Department of Meteorology, Stockholm University

Johan Nilsson

Professor of Meteorology

Department of Meteorology

08-16 17 36

nilsson@misu.su.se

Jonas Nycander

Professor of Physical oceanography

Department of Meteorology

08-16 43 36

jonas@misu.su.se

Sara Berglund

PhD

Formerly at the Department of Meteorology, Stockholm University

Verena Nadine Jung

PhD-student

Department of Meteorology

08-16 44 25

verena.jung@misu.su.se