The impact of oceanic heat transport on the atmospheric circulation

Knietzsch, Marc-Andre; Schröder, Alexander; Lucarini, Valerio; Lunkeit, Frank

doi:10.5194/esd-6-591-2015

Cited by 22 publications

(23 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Part of this modelled 410 N.Atlantic surface temperature underestimate may be due to a latitudinal temperature gradient being too high in the model (as also identified in previous modelling efforts of past warm climates), with heat transport to the poles being too low. Increased ocean heat transport was found to reduce the latitudinal temperature gradient and the location of Hadley and Ferrel cells in a modelling study by Knietzsch et al (2015), indicating the importance of atmospheric circulation, which in the cGENIE 2D energy-moisture balance atmosphere is simplified and invariant. The interaction between vegetation and atmosphere was found 415 to produce a warmer Miocene independent of CO2 by Knorr et al (2011).…”

Section: Climate Forcing and Co2 Levelsmentioning

confidence: 95%

Data-constrained assessment of ocean circulation changes since the middle Miocene in an Earth system model

Crichton¹,

Ridgwell²,

Lunt³

et al. 2020

Preprint

View full text Add to dashboard Cite

Abstract. Since the middle Miocene, 15 Ma (million years ago), the Earth’s climate has undergone a long-term cooling trend, characterised by a reduction in sea surface temperatures by over 6 °C, with 4 to 6 °C cooling occurring in the deep ocean. The causes of this cooling are primarily thought to be linked to changes in ocean circulation due to tectonic plate movements affecting ocean seaways, together with and a drop in atmospheric greenhouse gas forcing (and attendant ice-sheet growth and feedback). In this study we assess the potential to constrain, using marine sediment proxy data, the evolving patterns of global ocean circulation and cooling of surface climate over the last 15 million years (Ma) in an Earth system model. We do this by compiling surface and benthic ocean temperature and benthic carbon-13 data in a series of seven time-slices spaced at approximately 2.5 million year intervals. We pair this with a corresponding series of seven tectonic and surface climate boundary condition reconstructions in the cGENIE (muffin release) Earth system model. In the cGENIE model, we adjust atmospheric CO2 together with the magnitude of North Pacific to North Atlantic salinity flux adjustment in a series of 2D parameter ensembles in order to match global temperature and benthic δ13C patterns in the model to the data. We identify that a relatively high CO2 equivalent forcing of 1120 ppm is required at 15 Ma in cGENIE to reproduce proxy temperature estimates in the model, noting that this CO2 forcing is dependent on cGENIEs climate sensitivity (which is as the present day) and that it incorporates the effects of all greenhouse gases. The required CO2 forcing progressively reduces throughout the subsequent six time slices delineating the observed long-term cooling trend. In order to match the evolving patterns of the proxy data, we require fundamental change in the mode of ocean circulation at 12.5 Ma with present-day-like benthic δ13C trends established by 10 Ma. We also find a general increasing strength of Atlantic overturning despite a reduction in salinity of the surface North Atlantic over the cooling period, attributable to falling intensity of the hydrological cycle and polar cooling caused by CO2-driven global cooling.

show abstract

Section: Climate Forcing and Co2 Levelsmentioning

confidence: 95%

Data-constrained assessment of ocean circulation changes since the middle Miocene in an Earth system model

Crichton¹,

Ridgwell²,

Lunt³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Finally, the presence of larger temperature differences between high and low latitudes lead to a stronger atmospheric variability, as baroclinic conversion is more efficient and can draw from a larger reservoir of available potential energy. This is associated with a stronger Lorenz energy cycle compared to set-up A, see table 1; see a discussion of the climatic effects of modulating the meridional oceanic heat transport in the W state in [109].…”

Section: (B) Set-up B: Atmospheric-only Large-scale Energy Transport (I) the Three Competing Climate Statesmentioning

confidence: 99%

Dynamical landscape and multistability of a climate model

et al. 2021

View full text Add to dashboard Cite

We apply two independent data analysis methodologies to locate stable climate states in an intermediate complexity climate model and analyse their interplay. First, drawing from the theory of quasi-potentials, and viewing the state space as an energy landscape with valleys and mountain ridges, we infer the relative likelihood of the identified multistable climate states and investigate the most likely transition trajectories as well as the expected transition times between them. Second, harnessing techniques from data science, and specifically manifold learning, we characterize the data landscape of the simulation output to find climate states and basin boundaries within a fully agnostic and unsupervised framework. Both approaches show remarkable agreement, and reveal, apart from the well known warm and snowball earth states, a third intermediate stable state in one of the two versions of PLASIM, the climate model used in this study. The combination of our approaches allows to identify how the negative feedback of ocean heat transport and entropy production via the hydrological cycle drastically change the topography of the dynamical landscape of Earth’s climate.

show abstract

“…In addition, large-scale horizontal temperature gradients may play an important role in the global entropy budget. For instance, Knietzsch et al [2015] found decreases in frictional dissipation along with decreases in the pole-to-equator temperature gradient in GCM simulations in which the magnitude of a specified ocean heat transport was increased. In our study, moist convection is the focus, and large-scale motions and horizontal temperature gradients are not considered.…”

Section: Discussionmentioning

confidence: 99%

Scaling of the entropy budget with surface temperature in radiative‐convective equilibrium

Singh

O’Gorman

2016

J Adv Model Earth Syst

View full text Add to dashboard Cite

The entropy budget of the atmosphere is examined in simulations of radiative‐convective equilibrium with a cloud‐system resolving model over a wide range of surface temperatures from 281 to 311 K. Irreversible phase changes and the diffusion of water vapor account for more than half of the irreversible entropy production within the atmosphere, even in the coldest simulation. As the surface temperature is increased, the atmospheric radiative cooling rate increases, driving a greater entropy sink that must be matched by greater irreversible entropy production. The entropy production resulting from irreversible moist processes increases at a similar fractional rate as the entropy sink and at a lower rate than that implied by Clausius‐Clapeyron scaling. This allows the entropy production from frictional drag on hydrometeors and on the atmospheric flow to also increase with warming, in contrast to recent results for simulations with global climate models in which the work output decreases with warming. A set of approximate scaling relations is introduced for the terms in the entropy budget as the surface temperature is varied, and many of the terms are found to scale with the mean surface precipitation rate. The entropy budget provides some insight into changes in frictional dissipation in response to warming or changes in model resolution, but it is argued that frictional dissipation is not closely linked to other measures of convective vigor.

show abstract

The impact of oceanic heat transport on the atmospheric circulation

Cited by 22 publications

References 65 publications

Data-constrained assessment of ocean circulation changes since the middle Miocene in an Earth system model

Data-constrained assessment of ocean circulation changes since the middle Miocene in an Earth system model

Dynamical landscape and multistability of a climate model

Scaling of the entropy budget with surface temperature in radiative‐convective equilibrium

Contact Info

Product

Resources

About