Malte F. Jansen

University of Chicago

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Alistair Adcroft

NOAA Geophysical Fluid Dynamics Laboratory

Raffaele Ferrari

Massachusetts Institute of Technology

Stephen M. Griffies

NOAA Geophysical Fluid Dynamics Laboratory

Ian Grooms

University of Colorado Boulder

Robert Hallberg

NOAA Geophysical Fluid Dynamics Laboratory

Nora Loose

Princeton University

Stephanie L. Olson

Purdue University West Lafayette

Hailu Kong

University of Chicago

Dorian S. Abbot

University of Chicago

Chiung‐Yin Chang

Princeton University

Cooperative Institutions

Princeton University

NOAA Geophysical Fluid Dynamics Laboratory

National Oceanic and Atmospheric Administration

University of Chicago

Massachusetts Institute of Technology

Planetary Science Institute

California Institute of Technology

Woods Hole Oceanographic Institution

NSF National Center for Atmospheric Research

New York University

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Parameterizing subgrid-scale eddy effects using energetically consistent backscatter

Ocean Modelling (2014)

Malte F. Jansen Isaac M. Held

Enstrophy

Turbulence Modeling

Large-Eddy Simulation

10.1016/j.ocemod.2014.06.002

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Citations (140)

The glacial mid‐depth radiocarbon bulge and its implications for the overturning circulation

Paleoceanography (2015)

Andrea Burke Andrew L. Stewart Jess F. Adkins Raffaele Ferrari Malte F. Jansen

Abstract Published reconstructions of radiocarbon in the Atlantic sector of the Southern Ocean indicate that there is a mid‐depth maximum in radiocarbon age during the Last Glacial Maximum (LGM). This is in contrast to the modern ocean where intense mixing between water masses results in a relatively homogenous radiocarbon profile. Ferrari et al. (2014) suggested that the extended Antarctic sea ice cover during the LGM necessitated a shallower boundary between the upper and lower branches of the meridional overturning circulation. This shoaled boundary lay above major topographic features associated with strong diapycnal mixing, isolating dense southern sourced water in the lower branch of the overturning circulation. This isolation would have allowed radiocarbon to decay and thus provides a possible explanation for the mid‐depth radiocarbon age bulge. We test this hypothesis using an idealized, 2‐D, residual‐mean dynamical model of the global overturning circulation. Concentration distributions of a decaying tracer that is advected by the simulated overturning are compared to published radiocarbon data. We find that a 600 km (~5° of latitude) increase in sea ice extent shoals the boundary between the upper and lower branches of the overturning circulation at 45°S by 600 m and shoals the depth of North Atlantic Deep Water convection at 50°N by 2500 m. This change in circulation configuration alone decreases the radiocarbon content in the mid‐depth South Atlantic at 45°S by 40‰, even without an increase in surface radiocarbon age in the source region of deep waters during the LGM.

Shoal

Last Glacial Maximum

10.1002/2015pa002778

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Citations (70)

The Turbulent Circulation of a Globally Ice-Covered Ocean

21st Conference on Atmospheric and Oceanic Fluid Dynamics and the 19th Conference on Middle Atmosphere (2017)

Malte F. Jansen

Circulation (fluid dynamics)

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The Effect of Southern Ocean Surface Buoyancy Loss on the Deep-Ocean Circulation and Stratification

Journal of Physical Oceanography (2016)

Malte F. Jansen Louis-Philippe Nadeau

Abstract The deep-ocean circulation and stratification have likely undergone major changes during past climates, which may have played an important role in the modulation of atmospheric CO 2 concentrations. The mechanisms by which the deep-ocean circulation changed, however, are still poorly understood and represent a major challenge to the understanding of past and future climates. This study highlights the importance of the integrated buoyancy loss rate around Antarctica in modulating the abyssal circulation and stratification. Theoretical arguments and idealized numerical simulations suggest that enhanced buoyancy loss around Antarctica leads to a strong increase in the abyssal stratification, consistent with proxy observations for the last glacial maximum. Enhanced buoyancy loss moreover leads to a contraction of the middepth overturning cell and thus upward shift of North Atlantic Deep Water (NADW). The abyssal overturning cell initially expands to fill the void. However, if the buoyancy loss rate further increases, the abyssal cell also contracts, leaving a “dead zone” with vanishing meridional flow at middepth.

Abyssal zone

Stratification (seeds)

Antarctic Bottom Water

Seabed

10.1175/jpo-d-16-0084.1

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Citations (65)

The Impact of Topography and Eddy Parameterization on the Simulated Southern Ocean Circulation Response to Changes in Surface Wind Stress

Journal of Physical Oceanography (2020)

Hailu Kong Malte F. Jansen

Abstract It remains uncertain how the Southern Ocean circulation responds to changes in surface wind stress, and whether coarse-resolution simulations, where mesoscale eddy fluxes are parameterized, can adequately capture the response. We address this problem using two idealized model setups mimicking the Southern Ocean: a flat-bottom channel and a channel with moderately complex topography. Under each topographic configuration and varying wind stress, we compare several coarse-resolution simulations, configured with different eddy parameterizations, against an eddy-resolving simulation. We find that 1) without topography, sensitivity of the Antarctic Circumpolar Current (ACC) to wind stress is overestimated by coarse-resolution simulations, due to an underestimate of the sensitivity of the eddy diffusivity; 2) in the presence of topography, stationary eddies dominate over transient eddies in counteracting the direct response of the ACC and overturning circulation to wind stress changes; and 3) coarse-resolution simulations with parameterized eddies capture this counteracting effect reasonably well, largely due to their ability to resolve stationary eddies. Our results highlight the importance of topography in modulating the response of the Southern Ocean circulation to changes in surface wind stress. The interaction between mesoscale eddies and stationary meanders induced by topography requires more attention in future development and testing of eddy parameterizations.

Eddy

Wind Stress

Eddy diffusion

10.1175/jpo-d-20-0142.1

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Citations (11)

On the role of tropical cyclones in ocean heat transport (Invited)

AGU Fall Meeting Abstracts (2010)

Malte F. Jansen Ramiro Ferrari

Source

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Citations (0)

Equilibration of an Atmosphere by Adiabatic Eddy Fluxes

Journal of the Atmospheric Sciences (2013)

Malte F. Jansen Raffaele Ferrari

Abstract A major question for climate studies is to quantify the role of turbulent eddy fluxes in maintaining the observed atmospheric mean state. Both the equator-to-pole temperature gradient and the static stability of the extratropical atmosphere are set by a balance between these eddy fluxes and the radiative forcing. Much attention has been paid to the adjustment of the isentropic slope, which relates the static stability and the meridional temperature gradient. It is often argued that the extratropical atmosphere always equilibrates such that isentropes leaving the surface in the subtropics reach the tropopause near the poles. However, recent work challenged this argument. This paper revisits scaling arguments for the equilibrated mean state of a dry atmosphere, which results from a balance between the radiative forcing and the along-isentropic eddy heat flux. These arguments predict weak sensitivity of the isentropic slope to changes in the radiative forcing, consistent with previous results. Large changes can, however, be achieved if other external parameters, such as the size and rotation rate of the planet, are varied. The arguments are also extended to predict both the meridional temperature gradient and the static stability independently. This allows a full characterization of the atmospheric mean state as a function of external parameters.

Extratropical cyclone

Lapse rate

Isentropic process

Tropopause

Earth's energy budget

Radiative equilibrium

10.1175/jas-d-13-013.1

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Citations (34)

The global overturning circulation and the importance of non-equilibrium effects in ECCOv4r4

Tatsu Monkman Malte F. Jansen

Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at Geophysical Research Letters. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing the latest version by default [v1]The global overturning circulation and the importance of non-equilibrium effects in ECCOv4r4AuthorsTatsuMonkmaniDMalte FriedrichJansenSee all authors Tatsu MonkmaniDCorresponding Author• Submitting AuthorThe University of ChicagoiDhttps://orcid.org/0000-0002-3834-3063view email addressThe email was not providedcopy email addressMalte Friedrich JansenUniversity of Chicagoview email addressThe email was not providedcopy email address

Preprint

Circulation (fluid dynamics)

space science

10.1002/essoar.10511132.1

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Why Are Mountaintops Cold? The Transition of Surface Lapse Rate on Dry Planets

Geophysical Research Letters (2023)

Bowen Fan Malte F. Jansen M. A. Mischna Edwin S. Kite

Abstract Understanding surface temperature is important for habitability. Recent work on Mars has found that the dependence of surface temperature on elevation (surface lapse rate) converges to zero in the limit of a thin CO 2 atmosphere. However, the mechanisms that control the surface lapse rate are still not fully understood. It remains unclear how the surface lapse rate depends on both greenhouse effect and surface pressure. Here, we use climate models to study when and why “mountaintops are cold.” We find the tropical surface lapse rate increases with the greenhouse effect and with surface pressure. The greenhouse effect dominates the surface lapse rate transition and is robust across latitudes. The pressure effect is important at low latitudes in moderately opaque ( τ ∼ 0.1) atmospheres. A simple model provides insights into the mechanisms of the transition. Our results suggest that topographic cold‐trapping may be important for the climate of arid planets.

Lapse rate

Opacity

Greenhouse effect

10.1029/2023gl106683

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Citations (3)

Global cooling linked to increased glacial carbon storage via changes in Antarctic sea ice

Nature Geoscience (2019)

Alice Marzocchi Malte F. Jansen

10.1038/s41561-019-0466-8

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Citations (62)