Jupiter’s zonal winds and their variability studied with small-size telescopes

Abstract

Context. The general circulation of Jupiter's atmosphere at cloud level is dominated by a system of zonal jets that alternate in direction with latitude. The winds, measured in high-resolution images obtained by different space missions and the Hubble Space Telescope, are overall stable in their latitude location with small changes in intensity at particular jets. However, the atmosphere experiences repetitive changes in the albedo of particular belts and zones that are subject to large-scale intense disturbances that may locally influence the profile. Aims. The lack of high-resolution images has not allowed the wind system to be studied with the regularity required to assess its stability with respect to these major changes or to other types of variations (e.g., seasonality). To amend that, we present a study of the zonal wind profile of Jupiter using images acquired around the 2011 opposition by a network of observers operating small-size telescopes with apertures in the range 0.20−1 m. Methods. Using an automatic correlation technique, we demonstrate the capability to extract the mean zonal winds in observing periods close to the opposition. A broad collaboration with skilled amateur astronomers opens the possibility to regularly study shortand long-term changes in the jets of Jupiter. Results. We compare the 2011 Jovian wind profile to those previously obtained. The winds did not experience significant short-term changes over 2011 but show noteworthy variations at particular latitudes when compared with wind profiles from previous years. Most of these variations are related to major changes in the cloud morphology of the planet, in particular at 7 • N where an intense eastward jet varies around 40 ms −1 in its intensity according to the development or not of the "dark projection" features, confirming previous results.

An enduring rapidly moving storm as a guide to Saturn’s Equatorial jet’s complex structure

“…Tentatively, one can identify these features as delineating a southern jet peak, symmetric in latitude to the northern one. If so, Saturn's Equatorial jet at the lowest levels sampled has a similar shape to the Jupiter equatorial jet, that is, exhibiting a ‘double symmetric peak' relative to Equator13456. Third, the red continuum 689–750–937 nm wavelengths show a second group of lower velocities that follow the 2014 profile from Cassini ISS (blue and violet lines, Fig.…”

“…At the upper cloud level, the giant planets Jupiter and Saturn display a permanent system of alternating eastward and westward zonal jets whose intensity and width show few temporal changes since the first detailed measurements in 1979–1980 (refs 1, 2, 3, 4, 5, 6, 7, 8, 9). One exception is Saturn's broad equatorial jet that extends from planetographic latitudes ∼35° N to 35° S reaching eastward peak velocities ∼450–500 ms −1 (refs 7, 8, 9) (Fig.…”

Jupiter cloud morphology and zonal winds from ground‐based observations before and during Juno's first perijove

“…The motivations to obtain the ground‐based zonal winds were the following: Explore the possibility of small temporal changes in the zonal winds at different latitudes over 2016. A full statistical analysis of the ground‐based data from December 2015 to June 2016 and a comparison with HST zonal winds measured in January 2015 [ Simon et al , ] including a specific exploration of the NTB jet (not shown) conclude that there were no changes in the zonal winds at any latitude below the amateur noise level (10 m s −1 for the worse statistics associated to data from individual months). Validate the technique for ground‐based data which provides results that largely improve in terms of better latitudinal resolution and smaller error bars over previous analyses with similar data [ Barrado‐Izagirre et al , ]. …”

A large active wave trapped in Jupiter’s equator

“…The quality and spatial resolution on these images depend on several parameters: planet size (date of the observations relative to Jupiter's opposition), atmospheric conditions (seeing), telescope diameter, camera used and processing software, planet altitude, and astronomer's location in latitude. Assuming 35 cm diameter as a representative size of telescope used, the Airy spot diameter at the yellow wavelength is 0.4 arcsec, which for a JupiterEarth distance (∼6.26 × 10 8 km) gives a spatial resolution over Jupiter's disk of ∼1200 km/pixel; this is good enough to study Jovian atmospheric dynamics (Barrado-Izagirre et al 2013).…”