A Study of the Stability of Jovian Zonal Winds from HST Images: 1995–2000

Pérez‐Hoyos

García-Melendo

et al. 2009

A&A

Aims. Despite the banded visual aspect of cloud patterns in Jupiter, high resolution images indicate that these regions are markedly turbulent. One region of particular interest is the north temperate belt (NTB) at 21 • N planetocentric latitude, where the most intense Jovian jet resides with eastward peak speeds of 160−180 m s −1 . Almost every 15 years, the NTB is known to experience an eruption or disturbance that dramatically changes its appearance, a phenomenon known as NTB disturbance (NTBD). In this work, we characterize the morphology of the disturbed cloud field in the wake of the plumes that caused the perturbation, and check for changes in the velocity or shape of the jet. Methods. The 2007 disturbance was witnessed with unprecedented resolution by the Hubble Space Telescope and by a long-term survey based on the "International Outer Planet Watch" (IOPW) network. Our analysis is based on the brightness spectral distribution to characterize both the typical spatial frequency of the perturbation and its turbulent and wavy nature. We also compare our characterization with non-linear dynamical simulations of the disturbance using the EPIC dynamical model. Finally, we obtain a renewed wind profile for the region of interest by cloud tracking. Results. We detect a change in the power spectral slope of the cloud brightness following the disturbance that is related to a change in the typical size of the observed structures. We model the initial disturbance as a Rossby wave. A comparison of the jet profile in the NTB just after the disturbance ended (June 2007) with one observed a year later (July 2008), illustrates a net change occurred in the westward jet at 16 • N with a speed change of 25 m s −1 . As implied by the power spectra analysis, the disturbance and its related Rossby wave dissipate. We propose that this dissipation produced a momentum transfer to the anticyclonic side of the NTB jet increasing the speed of the westward jet at 16 • N as also supported by numerical simulations.

Section: Introductionsupporting

confidence: 80%

Evolution of the cloud field and wind structure of Jupiter's highest speed jet during a huge disturbance

Pérez‐Hoyos

García-Melendo

et al. 2009

A&A

“…We compare the 2011 wind profile with those obtained using HST data from 1995 to 1998 (García-Melendo & Sánchez-Lavega 2001), the Cassini wind profile corresponding to late 2000 (Porco et al 2003), and the most recent one retrieved from HST 2008 observations (Asay-Davis et al 2011). Figure 9 shows these global wind profiles.…”

Section: Long-term Variationsmentioning

confidence: 99%

“…Relevant questions about the observed wind system, which is measured at the 0.5−1 bar altitude level tracking the motions of small-cloud features, are: how deep it extends (shallow or deep relative to the planetary radius) (Dowling & Ingersoll 1989;Dowling 1995;Ingersoll et al 2004;Vasavada & Showman 2005;Sánchez-Lavega et al 2008), if winds are variable or not (García-Melendo & Sánchez-Lavega 2001;Asay-Davis et al 2011;Simon-Miller et al 2007;Simon-Miller & Gierasch 2010), and if the zonal jets support cyclic variations as has been claimed ). The study of long-or short-term global wind variations is fundamental to these questions and to A&A 554, A74 (2013) determine which is the energy source behind the atmospheric circulation (solar or internal or both).…”

Section: Introductionmentioning

confidence: 99%

“…In 1995, in situ measurements by the Galileo probe (Atkinson et al 1998) and observations from the Galileo orbiter (Vasavada et al 1998) led to new precise measurements of the winds on some localized areas, but did not result in a complete wind profile. Images acquired by the Hubble Space Telescope (HST) were used to obtain several profiles on different dates from 1995 to 2000 (García-Melendo & Sánchez-Lavega 2001). The Cassini flyby of Jupiter in late 2000 provided highresolution images that were also used to study the zonal winds system (Porco et al 2003;Vasavada & Showman 2005).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Rojas

Hueso

et al. 2013

A&A

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.

“…HST images were pipeline preprocessed and calibrated and Cassini ISS ones were photometrically calibrated with CISSCAL software (Porco et al 2004). We used LAIA software (Cano, 1998; see e. g. García-Melendo and Sánchez-Lavega, 2001 for details) for HST image navigation and projection; whereas for Cassini images PLIA software was employed (Hueso et al 2008). Both use parts of the VICAR code for pixel to longitude-latitude coordinates transformation (Barrey 1984).…”

Section: [Table 1]mentioning

confidence: 99%

Brightness power spectral distribution and waves in Jupiter's upper cloud and hazes

Pérez‐Hoyos

Sánchez‐Lavega

2009

Icarus

To cite this version:N. Barrado-Izagirre, S. Pérez-Hoyos, A. Sánchez-Lavega. Brightness power spectral distribution and waves in Jupiter's upper cloud and hazes. Icarus, Elsevier, 2009, 202 (1) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. infrared and blue wavelengths, average spectral slopes are n 1 = -1.3 ± 0.4 for shorter wavenumbers (k < 80), and n 2 = -2.5 ± 0.7 for greater wavenumbers, whereas for the ultraviolet n 1 = -1.9 ± 0.4 and n 2 = -0.7 ± 0.4, possibly showing a different dynamical regime. We find a turning point in the spectra between both regimes at wavenumber k ~ 80 (corresponding to L ~ 1000 km) for all wavelengths.