Latest results of the LMD Venus GCM
Abstract
The LMD Venus General Circulation Model (GCM), under development since 2005, models the circulation in Venus atmosphere (from the surface up to roughly 100 km), in particular the superrotation feature. The temperature structure is computed using a specific radiative transfer module based on net-exchange matrix formulation. Since the publication of the GCM details (Lebonnois et al, JGR 115, 2010, doi:10.1029/2009JE003458), some improvements were done, especially for the boundary layer scheme that affects the exchange of angular momentum between atmosphere and surface. Surprising impact of initial conditions on the steady-state zonal winds is also discussed. Passive tracers, tuned to mimic CO and OCS distributions, have also been added to the model to simulate the latitudinal distributions induced by transport. In this presentation, comparisons between our latest simulations and available observations from Venus Express (winds, temperature fields, CO and OCS distributions) are detailed: zonal and meridional wind distributions in the cloud region and above, thermal tide features in winds and temperature near the cloud-top, CO and OCS latitudinal profiles below the clouds. These comparisons help constrain the meridional circulation and its impact on trace species distributions, the chemical relaxation timescale of the same trace species as well as the thermal tides and their role in the angular momentum budget and in the superrotation mechanism. The impact on the zonal wind field of gravity waves that may be generated near the surface is currently investigated with a new parametrisation. These gravity waves have been suggested as a significant contributor in the angular momentum budget and superrotation mechanism (Hou and Farrell, J. Atmos. Sci. 44, pp.1049-1061, 1987, doi:10.1175/1520-0469(1987)044<1049:SIBCLA>2.0.CO;2). This parametrisation and its first results are presented here.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.P13F..02L
- Keywords:
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- 3337 ATMOSPHERIC PROCESSES / Global climate models;
- 5405 PLANETARY SCIENCES: SOLID SURFACE PLANETS / Atmospheres;
- 6295 PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS / Venus