Oxford Planetary Unified Model System

Venus, Jupiter, Saturn, and Titan

In 1996, a new project was initiated to adapt the UK Meteorological Office Portable Unified Model (MetUM) for use as a limited-area GCM of the Jovian stratosphere and upper troposphere. This model has now been extended to versions for Venus, Saturn, and Titan. The core model uses the HadAM3 core of the MetUM with simple parameterisations of (1) radiation balance via Newtonian cooling, (2) velocity damping effects via Rayleigh friction, (3) Richardson number-based vertical diffusion, and (4) cloud evaporation / condensation / precipitation processes for the major cloud species on Venus (sulphuric acid) and Jupiter (ammonia / water).

Current projects:

OPUS Venus and Titan (João Mendonça)

The atmospheric circulation both on Venus and Titan exhibit strong super-rotation and a range of other enigmatic features, but both remain poorly understood. The Venus GCM is being improved to include more accurate representations of radiative transfer, cloud physics, and boundary layer processes for both Venus and Titan, whose atmospheres have many similarities. The model simulations will be compared with new observations (a) of the Venus atmosphere from ESA's Venus Express mission, and (b) of Titan from the Cassini orbiter.

OPUS Venus zonal velocityOPUS Venus meridional velocity

OPUS-V publications

Lee, C., Lewis, S.R., and Read, P.L. (2007) Superrotation in a Venus general circulation model, J. Geophys. Res., 112, E04S11.

Lee, C., Lewis, S.R., and Read, P.L. (2010) A bulk cloud parameterization in a Venus General Circulation Model, Icarus, 206, 662-668.

Mendonça, J.M., Read, P.L., Wilson, C.F., and Lewis, S.R. (2012) Zonal winds at high latitudes on Venus: An improved application of cyclostrophic balance to Venus Express observations, Icarus, 217, 629-639.

Mendonça, J.M., Read, P.L., Wilson, C.F., and Lee, C. (2015) A new, fast and flexible radiative transfer method for Venus general circulation models, Plan. Space Sci., 105, 80-93.

OPUS Jupiter and Saturn (Roland Young)

The mechanisms responsible for the formation and maintenance of the ubiquitous zonal jets on the giant planets, of which Jupiter's are the most spectacular example, are still poorly understood. Of particular interest is how energy is injected into the system at small scales. Well-established results from 2D turbulence can be used to argue that such an energy injection combined with a planetary β-effect can lead to an inverse cascade of energy to large scales resulting in planetary-scale zonal jets. Observations of moist convection on Jupiter by the Galileo spacecraft suggest that this might be the dominant process responsible.

Recent work on OPUS Jupiter (Lena Zuchowski) added the effects of moist convection to the model. We are working on extending the Jupiter model to a global domain for use on a large supercomputing cluster. We expect to be able to resolve the zonal jets on a global scale and so investigate the role of convective and turbulent processes in the formation of the large-scale features, both for Jupiter and Saturn. The Cassini spacecraft (at Jupiter and particularly at Saturn) and the New Horizons spacecraft (at Jupiter) have provided a wealth of data for comparison with these models.

Typical OPUS Jupiter southern hemisphere limited area model velocity field:

OPUS-G publications

Yamazaki, Y.H., Skeet, D.R., and Read, P.L. (2004) A new general circulation model of Jupiter's atmosphere based on the UKMO Unified Model: Three-dimensional evolution of isolated vortices and zonal jets in mid-latitudes, Plan. Space Sci., 52, 423-445.

Yamazaki, Y.H., Read, P.L., and Skeet, D.R. (2005) Hadley circulations and Kelvin wave-driven equatorial jets in the atmospheres of Jupiter and Saturn, Plan. Space Sci., 53, 508-525.

Yamazaki, Y.H. and Read, P.L. (2006) Two scenarios on the driving mechanism of the Jovian equatorial jet with secondary hydrodynamic instabilities, Adv. Space Res., 38, 2639-2644.

Zuchowski, L.C., Yamazaki, Y.H., and Read, P.L. (2009) Modeling Jupiter's cloud bands and decks: 1. Jet scale meridional circulations, Icarus, 200, 548-562.

Zuchowski, L.C., Yamazaki, Y.H., and Read, P.L. (2009) Modeling Jupiter's cloud bands and decks: 2. Distribution and motion of condensates, Icarus, 200, 563-573.

Zuchowski, L.C., Read, P.L., and Yamazaki, Y.H. (2009) A heat engine based moist convection parametrization for Jupiter, Plan. Space Sci., 57, 1525-1537.