Examining the sensitivity of Earth's climate to the removal of ozone, landmasses and enhanced ocean heat transport in the GENESIS global climate model

<p>Arctic sea ice has been retreating at fast pace in the last decades, with potential impacts on the weather and climate at mid and high latitudes, as well as the biosphere and society. Sea-ice loss is driven by anthropogenic global warming, atmospheric circulation changes, climate feedbacks, and ocean heat transport. To date, no clear consensus regarding the detailed impact of ocean heat transport on Arctic sea ice exists. Previous observational and modeling studies show that the poleward Atlantic Ocean heat transport and Arctic sea-ice area and volume are generally anti-correlated, suggesting a decrease in sea-ice area and volume with larger ocean heat transport. In turn, the changing sea ice may also affect ocean heat transport, but this effect has been much less studied. Our study explores the two-way interactions between ocean heat transport and Arctic sea ice. We use the EC-Earth global climate model, coupling the atmosphere and ocean, and perform different sensitivity experiments to gain insights into these interactions. The mechanisms by which ocean heat transport and Arctic sea ice interact are analyzed, and compared to observations. This study provides a way to better constrain model projections of Arctic sea ice, based on the relationships between ocean heat transport and Arctic sea ice.</p>

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Atmospheric Responses and Feedback to the Meridional Ocean Heat Transport in the North Pacific

Journal of Climate ◽

10.1175/jcli-d-16-0055.1 ◽

2017 ◽

Vol 30 (15) ◽

pp. 5715-5728 ◽

Cited By ~ 1

Author(s):

Hiroaki Tatebe ◽

Masao Kurogi ◽

Hiroyasu Hasumi

Keyword(s):

Heat Transport ◽

North Pacific ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Storm Track ◽

Ocean Heat Transport ◽

The North ◽

The Mean ◽

The North Pacific

Atmospheric responses and feedback to meridional ocean heat transport (OHT) have been investigated using a global climate model that is interactively connected with a high-resolution regional ocean model embedded in the western North Pacific. Compared with a global climate model without the regional model, the net heat supply into the Kuroshio–Oyashio Extension (KOE) region is increased as a result of the increase of the mean northward ocean heat transport (OHT) by the western boundary currents and mesoscale eddies. Resultant sea surface temperature (SST) rise sharpens the meridional SST gradient and reinforces the cross-frontal difference of the surface heat flux and thereby enhances lower-tropospheric baroclinicity. These changes cause northward deflection and strengthening of the wintertime storm track over the North Pacific, which leads to the Pacific–North American (PNA)-like pattern anticyclonic response of the mean westerly jet. The increase of the eddy northward atmospheric heat flux (AHF) associated with the enhanced storm-track activity is compensated by the decrease of the mean northward AHF. The changes of the atmospheric circulations reduce the mean northward OHT in the eastern North Pacific that compensates the increase of the mean northward OHT in the KOE region. The atmospheric responses, which have once been excited by the SST fronts in the KOE region, stabilize the trans–North Pacific OHT. The modeling results herein suggest that basinwide Bjerknes-like compensation works in air–sea coupled processes for the formation of the climatic mean state in the North Pacific.

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Examination of Isentropic Circulation Response to a Doubling of Carbon Dioxide Using Statistical Transformed Eulerian Mean*

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-12-0235.1 ◽

2013 ◽

Vol 70 (6) ◽

pp. 1649-1667 ◽

Cited By ~ 7

Author(s):

Yutian Wu ◽

Olivier Pauluis

Keyword(s):

Heat Transport ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Sensible Heat Flux ◽

Sensible Heat ◽

Isentropic Flow ◽

Warming World ◽

The Tropics ◽

Transformed Eulerian Mean

Abstract Responses of the atmospheric circulation to a doubling of CO2 are examined in a global climate model, focusing on the circulation on both dry and moist isentropes. The isentropic circulations are reconstructed using the statistical transformed Eulerian mean (STEM), which approximates the isentropic flow from the Eulerian-mean and second-order moments. This approach also makes it possible to decompose the changes in the circulation into changes in zonal mean and eddy statistics. It is found that, as a consequence of CO2 doubling, the dry isentropic circulation weakens across all latitudes. The weaker circulation in the tropics is a result of the reduction in mean meridional circulation while the reduction in eddy sensible heat flux largely contributes to the slowdown of the circulation in the midlatitudes. The heat transport on dry isentropes, however, increases in the tropics because of the increase in dry effective stratification whereas it decreases in the extratropics following the reduction in eddy sensible heat transport. Distinct features are found on moist isentropes. In the tropics, the circulation weakens, but without much change in heat transport. The extratropical circulation shifts poleward with an intensification (weakening) on the poleward (equatorward) flank, primarily because of the change in eddy latent heat transport. The total heat transport in the midlatitudes also shows a poleward shift but is of smaller magnitude. The differences between the dry and moist circulations reveal that in a warming world the increase in midlatitude eddy moisture transport is associated with an increase in warm moist air exported from the subtropics into the midlatitude storm tracks.

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Black Carbon Increases Frequency of Extreme ENSO Events

Journal of Climate ◽

10.1175/jcli-d-19-0549.1 ◽

2019 ◽

Vol 32 (23) ◽

pp. 8323-8333 ◽

Cited By ~ 3

Author(s):

Sijia Lou ◽

Yang Yang ◽

Hailong Wang ◽

Jian Lu ◽

Steven J. Smith ◽

...

Keyword(s):

Black Carbon ◽

Climate Models ◽

Climate Model ◽

Southern Oscillation ◽

Global Climate ◽

Global Climate Model ◽

Co2 Concentration ◽

Enso Events ◽

Aerosol Forcing ◽

Earth’S Climate

ABSTRACT El Niño–Southern Oscillation (ENSO) is the leading mode of Earth’s climate variability at interannual time scales with profound ecological and societal impacts, and it is projected to intensify in many climate models as the climate warms under the forcing of increasing CO2 concentration. Since the preindustrial era, black carbon (BC) emissions have substantially increased in the Northern Hemisphere. But how BC aerosol forcing may influence the occurrence of the extreme ENSO events has rarely been investigated. In this study, using simulations of a global climate model, we show that increases in BC emissions from both the midlatitudes and Arctic weaken latitudinal temperature gradients and northward heat transport, decrease tropical energy divergence, and increase sea surface temperature over the tropical oceans, with a surprising consequential increase in the frequency of extreme ENSO events. A corollary of this study is that reducing BC emissions might serve to mitigate the possible increasing frequency of extreme ENSO events under greenhouse warming, if the modeling result can be translated into the climate in reality.

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Emergence of the Southeast Asian islands as a driver for Neogene cooling

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2011033117 ◽

2020 ◽

Vol 117 (41) ◽

pp. 25319-25326

Author(s):

Yuem Park ◽

Pierre Maffre ◽

Yves Goddéris ◽

Francis A. Macdonald ◽

Eliel S. C. Anttila ◽

...

Keyword(s):

Northern Hemisphere ◽

Chemical Weathering ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Southeast Asian ◽

Spatially Resolved ◽

Banda Arc ◽

Earth’S Climate ◽

The Antarctic

Steep topography, a tropical climate, and mafic lithologies contribute to efficient chemical weathering and carbon sequestration in the Southeast Asian islands. Ongoing arc–continent collision between the Sunda-Banda arc system and Australia has increased the area of subaerially exposed land in the region since the mid-Miocene. Concurrently, Earth’s climate has cooled since the Miocene Climatic Optimum, leading to growth of the Antarctic ice sheet and the onset of Northern Hemisphere glaciation. We seek to evaluate the hypothesis that the emergence of the Southeast Asian islands played a significant role in driving this cooling trend through increasing global weatherability. To do so, we have compiled paleoshoreline data and incorporated them into GEOCLIM, which couples a global climate model to a silicate weathering model with spatially resolved lithology. We find that without the increase in area of the Southeast Asian islands over the Neogene, atmosphericpCO2would have been significantly higher than preindustrial values, remaining above the levels necessary for initiating Northern Hemisphere ice sheets.

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Interhemispheric effect of global geography on Earth's climate response to orbital forcing

Climate of the Past ◽

10.5194/cp-15-377-2019 ◽

2019 ◽

Vol 15 (1) ◽

pp. 377-388

Author(s):

Rajarshi Roychowdhury ◽

Robert DeConto

Keyword(s):

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Climate Response ◽

Orbital Forcing ◽

Climate Data ◽

Unequal Distribution ◽

Summer Temperatures ◽

Earth’S Climate ◽

Climate Responses

Abstract. The climate response of the Earth to orbital forcing shows a distinct hemispheric asymmetry due to the unequal distribution of land in the Northern Hemisphere versus Southern Hemisphere. This asymmetry is examined using a global climate model (GCM) for different climate responses such as mean summer temperatures and positive degree days. A land asymmetry effect (LAE) is quantified for each hemisphere and the results show how changes in obliquity and precession translate into variations in the calculated LAE. We find that the global climate response to specific past orbits is likely unique and modified by complex climate–ocean–cryosphere interactions that remain poorly known. Nonetheless, these results provide a baseline for interpreting contemporaneous proxy climate data spanning a broad range of latitudes, which may be useful in paleoclimate data–model comparisons, and individual time-continuous records exhibiting orbital cyclicity.

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Interhemispheric bias in earth's climate response to orbital forcing

10.5194/cp-2015-156 ◽

2016 ◽

Cited By ~ 1

Author(s):

R. Roychowdhury ◽

R. M. DeConto

Keyword(s):

Data Model ◽

Hemispheric Asymmetry ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Climate Response ◽

Orbital Forcing ◽

Climate Data ◽

Unequal Distribution ◽

Earth’S Climate

Abstract. The climate response to orbital forcing shows a distinct hemispheric asymmetry due to the unequal distribution of land in the Northern vs. Southern hemispheres. This asymmetry is examined using a Global Climate Model (GCM) and a Land Hemispheric Bias (LHB) is quantified for each hemisphere. The results show how changes in obliquity and precession translate into variations in the calculated LHB. We find that the global climate response to specific past orbits is likely unique and modified by complex climate-ocean-cryosphere interactions that remain poorly known and difficult to model. Nonetheless, these results provide a baseline for interpreting contemporaneous proxy climate data spanning a broad range of latitudes, which maybe especially useful in paleoclimate data-model comparisons, and individual time-continuous records exhibiting orbital cyclicity.

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Exploring Opportunities for Performance Improvement in a Global Climate Model

10.5753/wscad.2019.8660 ◽

2019 ◽

Author(s):

Rhuan Costa ◽

Celso Luiz Mendes

Keyword(s):

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Optimization Techniques ◽

Intergovernmental Panel ◽

Support Materials ◽

Performance Improvements ◽

Ongoing Work ◽

Earth’S Climate ◽

Performance Gains

The Brazilian Earth System Model (BESM) is a Global Climate Model (GCM) developed by the Brazilian National Institute for Space Research (INPE). The main purpose of a GCM is to simulate Earth’s climate in a decadal or centennial scale. The simulations usually include representations of the main elements of the Earth, such as atmosphere, ocean, ice and land. Since its first release, BESM has provided support materials for contributions to the Intergovernmental Panel on Climate Change (IPCC). This paper evaluates BESM’s performance and explores optimization possibilities, aiming to speed up the model execution. Our study started with a detailed analysis that characterized the performance of BESM executions on hundreds of processors, which served to reveal the major performance bottlenecks. Next, we worked on schemes to mitigate some of those bottlenecks. The changes made so far resulted on performance gains up to a factor of 4 in some cases, when compared to the way it was previously being executed in production. We also describe ongoing work towards additional performance improvements. Despite presenting results only for BESM, our optimization techniques are applicable to other scientific, multi-physics models as well.

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Interhemispheric Effect of Global Geography on Earth's Climate Response to Orbital Forcing

10.5194/cp-2017-68 ◽

2017 ◽

Author(s):

Rajarshi Roychowdhury ◽

Robert DeConto

Keyword(s):

Data Model ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Climate Response ◽

Orbital Forcing ◽

Climate Data ◽

Unequal Distribution ◽

The Earth ◽

Earth’S Climate

Abstract. The climate response of the Earth to orbital forcing shows a distinct hemispheric asymmetry due to the unequal distribution of land in the Northern versus Southern Hemispheres. This asymmetry is examined using a Global Climate Model (GCM) and a Land Asymmetry Effect (LAE) is quantified for each hemisphere. The results show how changes in obliquity and precession translate into variations in the calculated LAE. We find that the global climate response to specific past orbits is likely unique and modified by complex climate–ocean–cryosphere interactions that remain poorly known and difficult to model. Nonetheless, these results provide a baseline for interpreting contemporaneous proxy climate data spanning a broad range of latitudes, which maybe especially useful in paleoclimate data-model comparisons, and individual time-continuous records exhibiting orbital cyclicity.

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