Large-scale ocean circulation in the Southern Hemisphere with closed and open Drake Passage – A laboratory minimal model approach

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 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.

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Extreme Wind and Wave Predictability From Operational Forecasts at the Drake Passage

Campos

D’Agostini

França

et al. 2020

Journal of Offshore Mechanics and Arctic Engineering

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The Drake Passage is an ocean area between South America and Antarctic with very extreme wind and wave climates. The quality of forecasts of surface winds and significant wave heights is analyzed in the present paper, in order to study the error and distribution of model uncertainties as a function of: forecast range, severity, location, and numerical model. The operational metocean forecasts selected are run twice a day by the Brazilian Navy and the forecast horizon analyzed is five days. A period of one year (2017) is considered for the assessment. Observations consist of four satellite missions: JASON2, JASON3, CRYOSAT, and SARAL. The atmospheric models with 10-m winds are GFS (Global Forecast System) and ICON (Icosahedral Nonhydrostatic Model). They are used as inputs to force the wave model WAVEWATCH III with a mosaic of two grids. Results show that under calm to moderate conditions, within the first two days of forecast, the wind and wave model skill is very high. However, above the 90th percentile and beyond the third forecast day, the predictability drops significantly. It highlights specific contours of forecast range versus percentiles where the wind and wave modelers should focus, in order to anticipate and to improve the predictability of extreme events at the Drake Passage.

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Large-scale ocean circulation in the Southern Hemisphere with closed and open Drake Passage – A laboratory minimal model approach

Cited by 4 publications

References 42 publications

Preface: Dynamics of ocean waves and currents

Preface: Dynamics of ocean waves and currents

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

Extreme Wind and Wave Predictability From Operational Forecasts at the Drake Passage

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