A long-lived cyclone in Saturn's atmosphere: Observations and models

作者：del Rio Gaztelurrutia T^*; Legarreta J; Hueso R; Perez Hoyos S; Sanchez Lavega A

来源：Icarus, 2010, 209(2): 665-681.

DOI：10.1016/j.icarus.2010.04.002

• Saturn, Atmosphere
• Atmospheres, Dynamics

The atmospheres of the giant planets Jupiter and Saturn possess large numbers of vortices (closed circulation ovals). On the larger scale, above 2000 km, anticyclones on Jupiter and Saturn are generally long-lived coherent structures while cyclones survive a much shorter time and behave more chaotically. A long term survey of images of Saturn's atmosphere obtained by the Cassini ISS camera has revealed the presence of an unusual long-lived cyclone in Saturn's southern hemisphere persistent during at least 4 years, making this vortex the longest-lived cyclone on either Jupiter or Saturn. We present a description of its horizontal morphology and vertical cloud structure, as well as its dynamics. We also present numerical simulations of its inner structure using a non-linear general circulation model (EPIC) that reproduces the main characteristics of this cyclone. We find that in contrast to jovian large and long-lived anticyclones which have strong circulations, and despite its long life, the vortex has a weak circulation and properties very similar to those of its environment. We show that the vortex lies in a latitude of unstable flow, feeding from the mean meridional wind shear in a low dissipation ambient environment.

• 出版日期2010-10