The equatorial jet stream in Saturn's atmosphere is one of the most interesting global wind systems in Solar System planets. The jet is home to an eastward intense wind of 450 ms-1 that encompasses a broad region of the equatorial atmosphere with a complex three-dimensional structure mixed with time variability. The variability of the jet has been studied since early wind measurements from Voyager data obtained in 1980 and 1981 together with more recent data from Cassini (years 2004-2015). However, up to now this variability has been clouded by the intriguing three-dimensional structure of the jet and lack of knowledge of the precise vertical cloud structure. The equatorial region is also affected by seasonal insolation cycles and ring shadow effects and is home to the development of half of the known giant planetary-scale storms that have developed in it. In this paper we present recent data from Cassini, Hubble Space Telescope and ground-based observations from 2014 and 2015 addresing the temporal changes in the wind and the vertical cloud structure revealing the true magnitude of the velocity changes and disentangling the effects of time variation in the jet speeds and the vertical cloud structure of the equatorial atmosphere.Reference: An enduring rapidly moving storm as a guide to Saturn's Equatorial jet's complex structure. A. Sánchez-Lavega, E. García-Melendo, S. Pérez-Hoyos, R. Hueso, M. H. Wong, A. Simon, J. F. Sanz-Requena, A. Antuñano, N. Barrado-Izagirre, I. Garate-Lopez, J. F. Rojas, T. del Río-Gaztelurrutia, J. M. Gómez-Forrellad, I. de Pater, L. Li & T. Barry.
Jupiter was the target of intensive observation, starting in February 2007,
from a battery of ground-based telescopes and the Hubble Space Telescope (HST).
They were obtained as an observational support for the New Horizons spacecraft to Pluto
that fly-byed Jupiter in February. On 25 March, an intense disturbance developed in Jupiter's
strongest jet at the North Temperate Belt, two bright plumes appearing at the peak of the jet
and developed a disturbance that covered the whole belt in about 40 days.
This type of event is rare and the last ones were seen in 1990 and 1975.
The onset of the disturbance was captured by the HST, and the development of the plumes
was followed in unprecedented detail. The plumes (bright white spots in the small infrared
image on the cover) towered 30 km above the surrounding clouds.
The nature of the power source for the jets that dominate the atmospheres of Jupiter and Saturn
is a controversial matter, complicated by the interplay of local and planet-wide meteorological factors.
The new observations are consistent with a wind extending deep into the atmosphere, well below the level
reached by solar radiation. In the large cover image, turbulence caused by the plumes can be seen in the
band that is home to the jet.
From Sánchez-Lavega, A., G. Orton, S., R. Hueso, E. García-Melendo, S. Pérez-Hoyos, A. Simon-Miller, J. F. Rojas, J. M. Gómez et al., Nature (2008), 451, 437-440.
Results from the Venus Express mission have been published in the Nature review on 29 november 2007.
We participate in two of these papers based on observations with the VIRTIS instrument.
See our press release here (Spanish only).
We have published a new letter in Nature modelling the characteristics of methane storms in Titan.
Methane storms in Saturn's moon Titan, R. Hueso and A. Sánchez-Lavega, Nature, Vol. 442, July 27, 428-431 (2006).
See our press release here
The winds in Saturn are known to be the strongest in the whole Solar System.
Hubble Space Telescope observations between 1996 and 2002 have revealed an unexpected and dramatic
slowdown in Saturn's strong equatorial winds since the Voyager encounters of 1980/81. Rather than
being deeply rooted, driven by internal heat, these winds now seem to be affected by shallow surface phenomena
and are liable to seasonal variations. Away from the equator the zonal jets have remained stable. On the cover,
a time series of HST images from years 1996 to 2000.
From Sánchez-Lavega, A., Pérez-Hoyos, S., Rojas, J. F., Hueso, R. and French, R. G. 2003, Nature Vol.423, 623-626.