At cloud top level, Venus’ entire atmosphere circles the planet in just about four Earth days, much faster than the solid planet does. Despite this “superrotation,” some dynamical and morphological similarities exist between the vortex organization in the atmospheres of Venus’s northern and southern hemispheres and tropical cyclones and hurricanes on Earth.

First detected by the Pioneer Venus Orbiter near the northern pole and recently by Venus Express orbiter around the southern pole, an S-shaped feature in the center of the vortices on Venus is also known to occur in Earth’s tropical cyclones. Using an idealized nonlinear and nondivergent barotropic model, Limaye et al. show that these S-shaped features are the manifestations of barotropic instability. They find that similar to the S-shapes seen in tropical cyclones, the S-shapes in Venus’s vortices are transient. Given the challenges in measuring the deep circulation of Venus’s atmosphere, the authors expect that the morphological similarities between vortices on Earth and Venus might help scientists better understand atmospheric superrotation on Venus and guide future observations.

Source: Geophysical Research Letters (GRL) paper 10.1029/2008GL036093, 2009; http://dx.doi.org/10.1029/2008GL036093