- 1Instituto de Astrofísica e Ciências do Espaço (IA) and Physics Department, Faculty of Sciences, University of Lisbon, Campo Grande, PT1749-016 Lisbon, Portugal (dfquirino@fc.ul.pt)
- 2Instituto Dom Luiz (IDL) and Geology Department, Faculty of Sciences, University of Lisbon, Campo Grande, PT1749-016 Lisbon, Portugal
- 3School of Ocean Sciences, Bangor University Menai Bridge, LL59 5AB, UK
- 4NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, USA
- 5Theoretical Astrophysics, Department of Physics and Astronomy, Uppsala University, Uppsala, SE-75120, Sweden
- 6GSFC Sellers Exoplanet Environments Collaboration, NASA Goddard Space Flight Center, MD, USA
The modern Venus atmosphere has substantially lower water vapour abundance [1-3] and a high deuterium to hydrogen ratio (D/H) compared to Earth [3,4]. The high D/H suggests a significantly larger initial water reservoir than today. Some studies suggest an initial temperate climate, with a dayside cloud-albedo feedback supporting early and prolonged surface Habitability [5,6] and ending with a runaway greenhouse effect possibly triggered by large-scale volcanism [7]. Water vapour photodissociation and preferential loss of the lighter hydrogen would explain the observed D/H [8]. Other studies claim that warming from nightside stratospheric clouds could prevent water condensation [9].
Assuming surface water condensation from a steam atmosphere in the first place, we use a 3D General Circulation model (GCM) to simulate a hypothetical ocean on Venus (2.9 Ga). We use the 3D GCM ROCKE-3D (Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics), developed at the NASA Goddard Institute for Space Studies [10]. The simulations use a spatial resolution of 4ºx5º (latitude x longitude), a 40-layer atmosphere (top pressure: 0.1-hPa) and a 13-layer fully dynamic ocean [11] coupled to the atmosphere. For the reference simulation, we select a modern Venus topography following the NASA/Magellan archive. We simulate a 310-m global equivalent layer (GEL), covering ~60% of the surface of Venus. Ocean volume is 1.4 x 1017 m3, one order of magnitude below that of modern Earth’s Ocean [5]. We set insolation to 2001 W/m2 or 1.47 times that of modern Earth, representing conditions at 2.9 Ga. The atmospheric composition was set to be Archean Earth-like (1.013 bar N2, 400 ppm CO2, 1 ppm CH4) [6]. Other planetary parameters follow the modern values of Venus’s surface gravity, radius, obliquity, eccentricity and rotation rate (retrograde slow-rotator: -243 days) [5].
We will discuss the main physical oceanographic parameters (e.g., potential temperature, salinity, potential density) and ocean circulation. Our results suggest the presence of deep mixed layers in the polar seas and the development of a complex meridional overturning circulation, controlled in part by the landmass configuration and bathymetry. In addition, we will explore the impact of parameters such as rotation rate, insolation, and ocean thickness on ocean circulation.
References: [1] Bézard B., et al.,2011.Icarus.216:173; [2] Cottini V., et al.,2015.Planet. Space Sci.113:219; [3] Encrenaz T., et al.,2015.Planet. Space Sci.113:275; [4] Krasnopolsky V., et al.,2013.Icarus.224:57; [5] Way M.J., et al.,2016.GRL.43; [6] Way M.J. & Del Genio A.D. (2020).JGR:Planets.125; [7] Way M.J., et al.,2022.Planet. Sci. J.3:92; [8] Chaffin M.S., et al.,2024.Nature.629:307; [9] Turbet M., et al.,2021.Nature.598:276; [10] Way M.J., et al.,2017.ApJS.213:12; [11] Russell G.L., et al.,1995.Atmos-Ocean.33:683.
Acknowledgements: This work was funded by the Portuguese Fundação para a Ciência e Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) –UID/50019/2025 and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020), and research grants UIDB/04434/2020 (https://doi.org/10.54499/UIDB/04434/2020) and UIDP/04434/2020 (https://doi.org/10.54499/UIDP/04434/2020). DQ acknowledges FCT a PhD fellowship 2023.05220.BD. JCD also acknowledges FCT a CEEC Inst. 2018, CEECINST/00032/2018/CP1523/CT0002 (https://doi.org/10.54499/CEECINST/00032/2018/CP1523/CT0002).
How to cite: Quirino, D., Way, M. J., Green, J. A. M., Duarte, J. C., and Machado, P.: Ocean circulation on a temperate paleo-Venus simulated with ROCKE-3D, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-730, https://doi.org/10.5194/egusphere-egu25-730, 2025.
