We present a new version of the Oxford Venus GCM, which using our new parameterisations produce a realistic Venus mesosphere atmospheric circulation. We present results that give hints to the formation of global super-rotation

Lee, Christopher

Lewis, Stephen R.

Mendonça, João M.

Read, Peter L.

English

Open Research Online (The Open University)

Open Research OnlineThe Open University’s repository of research publicationsand other research outputsThe new Oxford planetary unified model system forVenus (OPUS-V)Conference or Workshop ItemHow to cite:Mendonc¸a, Joa˜o M.; Read, Peter L.; Lewis, Stephen R. and Lee, Christopher (2012). The new Oxford planetaryunified model system for Venus (OPUS-V). In: Comparative Climatology of Terrestrial Planets, 25-28 Jun 2012,Boulder, Co, USA.For guidance on citations see FAQs.c© 2012 The AuthorsVersion: Version of RecordLink(s) to article on publisher’s website:http://www.lpi.usra.edu/meetings/climatology2012/pdf/8047.pdfCopyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyrightowners. For more information on Open Research Online’s data policy on reuse of materials please consult the policiespage.oro.open.ac.ukTHE NEW OXFORD PLANETARY UNIFIED MODEL SYSTEM FOR VENUS (OPUS-V). João M. Men-donça1, Peter L. Read1, Stephen R. Lewis2, and Christopher Lee3 1 Department of Physics, University of Oxford, U. K., 2 Department of Physical Sciences, The Open University, U.K., 3Ashima Research, USA  (Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, U.K. mendonca@atm.ox.ac.uk)   Introduction:  Venus models are at the stage of evolving from simpliﬁed General Circulation Models (SGCM) towards more complete and physically-based ones ([1], [2] and [3]). The process is complex and challenging due to difﬁculties in reproducing the phys-ical and dynamical conditions of the global atmosphere of Venus in a realistic numerical approach. The Venus atmospheric circulation is well known to exhibit strong super-rotation and a variety of enigmatic features which remain poorly understood. Here we present a new version of the Oxford Plane-tary Unified (Model) System for Venus (OPUS-V). This model is the expansion and improvement of an existing simplified version ([1]) which uses as basis a dynamical core from an Earth GCM called HadCM3 ([4]). New pameterisations were developed and imple-mented, being more suitable to simulate the extreme Venus climate, such as: a complex radiation scheme for solar and thermal spectral regions ([3]), a new convec-tion scheme, a realistic boundary layer and a dynamical core that takes into account the dependence of the heat capacity with temperature. Simulated Atmospheric Circulation: The model presented here produces a realistic Venus mesosphere atmospheric circulation. This result is an important improvement over earlier simplified General Circula-tion Models, and an essential tool to explore the at-mospheric circulation, which will consequently ad-vance the interpretation of the observational data. We present the zonal wind maps and the important climatic diagnostics, which help us to have a better understand-ing of the mechanisms for the formation of the atmos-pheric super-rotation. We also present results showing good agreement between the simulated global zonal winds and the ones constrained by the observations ([5]). The magnitude of the mesosphere winds at the equilibrium state, where the total angular of the atmos-phere evolve roughly constant with time, depends on the different intensities of the initial zonal wind fields. Currently, three different regimes have been obtained and are presented here. Starting with a rest atmosphere or a super-rotation obtained by the simplified version, the current model produces mesospheric zonal winds in agreement with the observations. The other two states show a global super-rotation of the atmosphere even stronger than the one observed, being one of them in the retrograde direction. To obtain these two  statistic equilibrium states, the model is started with an absolute super-rotation four times larger than the one obtained by the simplified version: in the prograde direction for a prograde super-rotation or in the retrograde direction for a retrograde super-rotation.    The model’s results suggest two main different mechanisms for the formation of the strong prograde winds, which act in two different regions of the Venus atmosphere: upper atmosphere (60-100km) and lower atmosphere (0-60 km). A consistent theory for the gen-eral super-rotation is proposed and discussed. Its im-plications are also discussed for other terrestrial atmos-pheres: Earth, Mars and Titan. Acknowledgements: J. Mendonça acknowledges financial support from FCT - Fundação para a Ciência e a Tecnologia (Portugal). Material produced using Met Office Software. References: [1] Lee, C. et al. (2007), J. Geophys. Res., 112, E4 [2] Lebonnois, S. et al. (2010), J. Ge-ophys. Res., 115, E6  [3] Mendonca, J. et al. (2011), EGU, Abstract, 13, 634 [4] Cullen, M. (1993), Mete-orol. Mag.,122, 81-94 [5] Kerzhanovich, V. (1985), Adv. Space Res., 5, 11, 59-83   8047.pdfComparative Climatology of Terrestrial Planets (2012)

The new Oxford planetary unified model system for Venus (OPUS-V)

Abstract

Similar works

Full text

Available Versions

Open Research Online (The Open University)