scholarly journals The Climate Impact of the Drake Passage Opening From a Fluid Dynamics Point of View: the Role of Antarctic Glaciation

2021 ◽  
Author(s):  
Miklos Vincze ◽  
Tamás Bozóki ◽  
Mátyás Herein ◽  
Ion Dan Borcia ◽  
Uwe Harlander ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Ocean Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Drake Passage ◽  
Climate Impact ◽  
Laboratory Model ◽  
Climate History ◽  
Ice Dynamics

Abstract Pronounced global cooling around the Eocene-Oligocene transition (EOT) was a pivotal event in Earth’s climate history, controversially associated with the opening of the Drake Passage. Using a physical laboratory model we revisit the fluid dynamics of this marked reorganization of ocean circulation. Here we show, seemingly contradicting paleoclimate records, that in our experiments opening the pathway yields higher values of mean water surface temperature than the "closed'" configuration. This mismatch points to the importance of the role ice albedo feedback plays in the investigated EOT-like transition, a component that is not captured in the laboratory model. Our conclusion is supported by numerical simulations performed in a global climate model (GCM) of intermediate complexity, where both "closed" and "open" configurations were explored, with and without active sea-ice dynamics. The GCM results indicate that sea surface temperatures would change in the opposite direction following an opening event in the two ice dynamics settings, and the results are therefore consistent both with the laboratory experiment (slight warming after opening) and the paleoclimatic data (pronounced cooling after opening). It follows that in the hypothetical case of an initially ice-free Antarctica the continent could have become even warmer after the opening, a scenario not indicated by paleotemperature reconstruction. These results provide circumstantial evidence supporting a particular EOT scenario in which Antarctica has already been -- at least partially -- covered with ice when the Drake Passage fully opened.

scholarly journals The climate impact of the Drake Passage opening from a fluid dynamics point of view: the role of Antarctic glaciation

2021 ◽  
Author(s):  
Matyas Herein ◽  
Miklos Vinzce ◽  
Tamas Bozoki ◽  
Ion Dan Borcia ◽  
Uwe Harlander ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Ocean Circulation ◽  
Climate Model ◽  
Global Climate Model ◽  
Drake Passage ◽  
Climate Impact ◽  
Laboratory Model ◽  
Climate History ◽  
Ice Dynamics ◽  
Albedo Feedback

<p>Pronounced global cooling around the Eocene-Oligocene transition (EOT) was a pivotal event in Earth’s climate history, controversially associated with the opening of the Drake Passage.  Using a physical laboratory model we revisit the fluid dynamics of this marked reorganization of ocean circulation. Our differentially heated rotating annulus is a widely studied experimental set-up designed to model mid-latitude circulation in the atmosphere and the ocean, as well. Here we show, seemingly contradicting paleoclimate records that in our experiments opening the pathway yields higher values of mean water surface temperature than the “closed” configuration. This mismatch points to the importance of the crucial role ice albedo feedback plays in the investigated EOT-like transition, a component that is not captured in the laboratory model. Our conclusion is supported by numerical simulations performed in a global climate model (GCM) of intermediate complexity, where both “closed” and “open” configurations were explored, with and without active ice-albedo feedback. The GCM results indicate that sea surface temperatures would change in the opposite direction following an opening event in the two ice dynamics settings, and the results are therefore consistent both with the laboratory experiment (slight warming after opening) and the paleoclimatic data (pronounced cooling after opening). It follows that in the hypothetical case of an initially ice-free Antarctica the continent could have become even warmer after the opening, a scenario not indicated by paleotemperature reconstruction. These results provide circumstantial evidence supporting a particular EOT scenario in which Antarctica had already been – at least partially – covered with ice when the Drake Passage fully opened.</p>

scholarly journals The Drake Passage opening from an experimental fluid dynamics point of view

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Miklós Vincze ◽  
Tamás Bozóki ◽  
Mátyás Herein ◽  
Ion Dan Borcia ◽  
Uwe Harlander ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Sea Ice ◽  
Ocean Circulation ◽  
Climate Model ◽  
Global Climate Model ◽  
Drake Passage ◽  
Laboratory Model ◽  
Climate History ◽  
Ice Dynamics ◽  
Sea Ice Dynamics

AbstractPronounced global cooling around the Eocene–Oligocene transition (EOT) was a pivotal event in Earth’s climate history, controversially associated with the opening of the Drake Passage. Using a physical laboratory model we revisit the fluid dynamics of this marked reorganization of ocean circulation. Here we show, seemingly contradicting paleoclimate records, that in our experiments opening the pathway yields higher values of mean water surface temperature than the “closed” configuration. This mismatch points to the importance of the role ice albedo feedback plays in the investigated EOT-like transition, a component that is not captured in the laboratory model. Our conclusion is supported by numerical simulations performed in a global climate model (GCM) of intermediate complexity, where both “closed” and “open” configurations were explored, with and without active sea ice dynamics. The GCM results indicate that sea surface temperatures would change in the opposite direction following an opening event in the two sea ice dynamics settings, and the results are therefore consistent both with the laboratory experiment (slight warming after opening) and the paleoclimatic data (pronounced cooling after opening). It follows that in the hypothetical case of an initially ice-free Antarctica the continent could have become even warmer after the opening, a scenario not indicated by paleotemperature reconstructions.

Revisiting the Krakatau 1883 Volcanic Aerosol Dispersal 

2021 ◽  
Author(s):  
Rafael Castro ◽  
Tushar Mittal ◽  
Stephen Self
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Volcanic Eruptions ◽  
Climate Impact ◽  
Volcanic Plume ◽  
Quasi Biennial Oscillation ◽  
Aerosol Cloud ◽  
Pinatubo Eruption ◽  
The Impact

<p>The 1883 Krakatau eruption is one of the most well-known historical volcanic eruptions due to its significant global climate impact as well as first recorded observations of various aerosol associated optical and physical phenomena. Although much work has been done on the former by comparison of global climate model predictions/ simulations with instrumental and proxy climate records, the latter has surprisingly not been studied in similar detail. In particular, there is a wealth of observations of vivid red sunsets, blue suns, and other similar features, that can be used to analyze the spatio-temporal dispersal of volcanic aerosols in summer to winter 1883. Thus, aerosol cloud dispersal after the Krakatau eruption can be estimated, bolstered by aerosol cloud behavior as monitored by satellite-based instrument observations after the 1991 Pinatubo eruption. This is one of a handful of large historic eruptions where this analysis can be done (using non-climate proxy methods). In this study, we model particle trajectories of the Krakatau eruption cloud using the Hysplit trajectory model and compare our results with our compiled observational dataset (principally using Verbeek 1884, the Royal Society report, and Kiessling 1884).</p><p>In particular, we explore the effect of different atmospheric states - the quasi-biennial oscillation (QBO) which impacts zonal movement of the stratospheric volcanic plume - to estimate the phase of the QBO in 1883 required for a fast-moving westward cloud. Since this alone is unable to match the observed latitudinal spread of the aerosols, we then explore the impact of an  umbrella cloud (2000 km diameter) that almost certainly formed during such a large eruption. A large umbrella cloud, spreading over ~18 degrees within the duration of the climax of the eruption (6-8 hours), can lead to much quicker latitudinal spread than a point source (vent). We will discuss the results of the combined model (umbrella cloud and correct QBO phase) with historical accounts and observations, as well as previous work on the 1991 Pinatubo eruption. We also consider the likely impacts of water on aerosol concentrations and the relevance of this process for eruptions with possible significant seawater interactions, like Krakatau. We posit that the role of umbrella clouds is an under-appreciated, but significant, process for beginning to model the climatic impacts of large volcanic eruptions.</p>

scholarly journals Organic aerosol and global climate modelling: a review

2005 ◽  
Vol 5 (4) ◽  
pp. 1053-1123 ◽  
Author(s):  
M. Kanakidou ◽  
J. H. Seinfeld ◽  
S. N. Pandis ◽  
I. Barnes ◽  
F. J. Dentener ◽  
...  
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Organic Aerosol ◽  
Climate Impact ◽  
Climate Modelling ◽  
Carbonaceous Particles ◽  
Global Climate Modelling ◽  
Removal Processes ◽  
Wet Removal

Abstract. The present paper reviews existing knowledge with regard to Organic Aerosol (OA) of importance for global climate modelling and defines critical gaps needed to reduce the involved uncertainties. All pieces required for the representation of OA in a global climate model are sketched out with special attention to Secondary Organic Aerosol (SOA): The emission estimates of primary carbonaceous particles and SOA precursor gases are summarized. The up-to-date understanding of the chemical formation and transformation of condensable organic material is outlined. Knowledge on the hygroscopicity of OA and measurements of optical properties of the organic aerosol constituents are summarized. The mechanisms of interactions of OA with clouds and dry and wet removal processes parameterisations in global models are outlined. This information is synthesized to provide a continuous analysis of the flow from the emitted material to the atmosphere up to the point of the climate impact of the produced organic aerosol. The sources of uncertainties at each step of this process are highlighted as areas that require further studies.

scholarly journals Simulation of black carbon in snow and its climate impact in the Canadian Global Climate Model

2015 ◽  
Vol 15 (13) ◽  
pp. 18839-18882 ◽  
Author(s):  
M. Namazi ◽  
K. von Salzen ◽  
J. N. S. Cole
Keyword(s):  
Black Carbon ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Surface Air Temperature ◽  
Climate Impact ◽  
Radiative Forcings ◽  
Mixing Ratios ◽  
Emission Changes ◽  
The Impact

Abstract. A new physically-based parameterization of black carbon (BC) in snow was developed and implemented in the Canadian Atmospheric Global Climate Model (CanAM4.2). Simulated BC snow mixing ratios and BC snow radiative forcings are in good agreement with measurements and results from other models. Simulations with the improved model yield considerable trends in regional BC concentrations in snow and BC snow radiative forcings during the time period from 1950–1959 to 2000–2009. Increases in radiative forcings for Asia and decreases for Europe and North America are found to be associated with changes in BC emissions. Additional sensitivity simulations were performed in order to study the impact of BC emission changes between 1950–1959 and 2000–2009 on surface albedo, snow cover fraction, and surface air temperature. Results from these simulations indicate that impacts of BC emission changes on snow albedos between these two decades are small and not significant. Overall, changes in BC concentrations in snow have much smaller impacts on the cryosphere than the net warming surface air temperatures during the second half of the 20th century.

Sea‐ice dynamics and CO2sensitivity in a global climate model

1994 ◽  
Vol 32 (2) ◽  
pp. 449-467 ◽  
Author(s):  
David Pollard ◽  
Starley L. Thompson
Keyword(s):  
Sea Ice ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Ice Dynamics ◽  
Sea Ice Dynamics

scholarly journals Simulation of black carbon in snow and its climate impact in the Canadian Global Climate Model

2015 ◽  
Vol 15 (18) ◽  
pp. 10887-10904 ◽  
Author(s):  
M. Namazi ◽  
K. von Salzen ◽  
J. N. S. Cole
Keyword(s):  
Black Carbon ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Surface Air Temperature ◽  
Climate Impact ◽  
Radiative Forcings ◽  
Mixing Ratios ◽  
Emission Changes ◽  
The Impact

Abstract. A new physically based parameterisation of black carbon (BC) in snow was developed and implemented in the Canadian Atmospheric Global Climate Model (CanAM4.2). Simulated BC snow mixing ratios and BC snow radiative forcings are in good agreement with measurements and results from other models. Simulations with the improved model yield considerable trends in regional BC concentrations in snow and BC snow radiative forcings during the time period from 1950–1959 to 2000–2009. Increases in radiative forcings for Asia and decreases for Europe and North America are found to be associated with changes in BC emissions. Additional sensitivity simulations were performed in order to study the impact of BC emission changes between 1950–1959 and 2000–2009 on surface albedo, snow cover fraction, and surface air temperature. Results from these simulations indicate that impacts of BC emission changes on snow albedos between these 2 decades are small and not significant. Overall, changes in BC concentrations in snow have much smaller impacts on the cryosphere than the net warming surface air temperatures during the second half of the 20th century.

scholarly journals Organic aerosol and global climate modelling: a review

2004 ◽  
Vol 4 (5) ◽  
pp. 5855-6024 ◽  
Author(s):  
M. Kanakidou ◽  
J. H. Seinfeld ◽  
S. N. Pandis ◽  
I. Barnes ◽  
F. J. Dentener ◽  
...  
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Organic Aerosol ◽  
Climate Impact ◽  
Climate Modelling ◽  
Carbonaceous Particles ◽  
Global Climate Modelling ◽  
Removal Processes ◽  
Wet Removal

Abstract. The present paper reviews existing knowledge with regard to Organic Aerosol (OA) of importance for global climate modelling and defines critical gaps needed to reduce the involved uncertainties. All pieces required for the representation of OA in a global climate model are sketched out with special attention to Secondary Organic Aerosol (SOA): The emission estimates of primary carbonaceous particles and SOA precursor gases are summarized. The up-to-date understanding of the chemical formation and transformation of condensable organic material is outlined. Knowledge on the hygroscopicity of OA and measurements of optical properties of the organic aerosol constituents are summarized. The mechanisms of interactions of OA with clouds and dry and wet removal processes parameterisations in global models are outlined. This information is synthesized to provide a continuous analysis of the flow from the emitted material to the atmosphere up to the point of the climate impact of the produced organic aerosol. The sources of uncertainties at each step of this process are highlighted as areas that require further studies.

scholarly journals Solar-forced shifts of the Southern Hemisphere Westerlies during the late Holocene

2010 ◽  
Vol 6 (2) ◽  
pp. 369-384 ◽  
Author(s):  
V. Varma ◽  
M. Prange ◽  
F. Lamy ◽  
U. Merkel ◽  
M. Schulz
Keyword(s):  
Solar Activity ◽  
Southern Hemisphere ◽  
Ocean Circulation ◽  
Late Holocene ◽  
Large Scale ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Latitudinal Position ◽  
Potential Factor

Abstract. The Southern Hemisphere Westerly Winds (SWW) constitute an important zonal circulation that influences large-scale precipitation patterns and ocean circulation. Variations in their intensity and latitudinal position have been suggested to exert a strong influence on the CO2 budget in the Southern Ocean, thus making them a potential factor affecting the global climate. In the present study, the possible influence of solar forcing on SWW variability during the late Holocene is addressed. It is shown that a high-resolution iron record from the Chilean continental slope (41° S), which basically reflects changes in the position of the SWW, is significantly correlated with reconstructed solar activity. In addition, solar sensitivity experiments with a comprehensive global climate model (CCSM3) are carried out to study the response of SWW to solar variability. Taken together, the proxy and model results strongly suggest that centennial-scale periods of lower (higher) solar activity caused equatorward (southward) shifts of the SWW during the past 3000 years.

scholarly journals Climate Impact of Cloud Water Inhomogeneity through Microphysical Processes in a Global Climate Model

2020 ◽  
Vol 33 (12) ◽  
pp. 5195-5212 ◽  
Author(s):  
Haruka Hotta ◽  
Kentaroh Suzuki ◽  
Daisuke Goto ◽  
Matthew Lebsock
Keyword(s):  
Enhancement Factor ◽  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Climate Impact ◽  
Cloud Water ◽  
Satellite Observations ◽  
Low Latitudes

AbstractThis study investigates how subgrid cloud water inhomogeneity within a grid spacing of a general circulation model (GCM) links to the global climate through precipitation processes. The effect of the cloud inhomogeneity on autoconversion rate is incorporated into the GCM as an enhancement factor using a prognostic cloud water probability density function (PDF), which is assumed to be a truncated skewed-triangle distribution based on the total water PDF originally implemented. The PDF assumption and the factor are evaluated against those obtained by global satellite observations and simulated by a global cloud-system-resolving model (GCRM). Results show that the factor implemented exerts latitudinal variations, with higher values at low latitudes, qualitatively consistent with satellite observations and the GCRM. The GCM thus validated for the subgrid cloud inhomogeneity is then used to investigate how the characteristics of the enhancement factor affect global climate through sensitivity experiments with and without the factor incorporated. The latitudinal variation of the factor is found to have a systematic impact that reduces the cloud water and the solar reflection at low latitudes in the manner that helps mitigate the too-reflective cloud bias common among GCMs over the tropical oceans. Due to the limitation of the factor arising from the PDF assumption, however, no significant impact is found in the warm rain formation process. Finally, it is shown that the functional form for the PDF in a GCM is crucial to properly characterize the observed cloud water inhomogeneity and its relationship with precipitation.

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