BAA Jupiter Section PUBLICATIONS

Papers published in professional journals

Rogers JH, Mettig H-J, and Peach D (2006). Renewed acceleration of the 24°N jet on Jupiter. Icarus 184, 452-459.

For subscribers, the article is available online via the following link:

http://dx.doi.org/10.1016/j.icarus.2006.05.007

PDF here: Rogers JH, Mettig H-J, and Peach D (2006). Renewed acceleration of the 24°N jet on Jupiter. Icarus (in press).

Summary:

Jupiter's eastward jet at 24°N, which formerly had the fastest winds on the planet, has maintained a less extreme speed of ~135 m/s since 1991, carrying a series of long-lived vortices at 125 m/s. In 2002-2003, as the albedo of the adjacent North Temperate Belt increased, the tracks of the vortices accelerated slightly, and they had disappeared by 2005. In 2005, small tracers had a mean speed of 146.4 (+/- 0.9) m/s, significantly faster than the previous mean speed of the jet, suggesting that the jet peak itself has accelerated at cloud-top level, and that the jet is beginning to return to the super-fast state. These changes may resemble the even greater transformations occurring in the equatorial jet of Saturn.

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Rogers JH, Mettig H-J, Cidadão A, Sherrod PC, and Peach D (2006). Merging circulations on Jupiter: observed differences between cyclonic and anticyclonic mergers. Icarus 185, 244-257.

PDF here: Rogers JH, Mettig H-J, Cidadão A, Sherrod PC, and Peach D (2006). Merging circulations on Jupiter: observed differences between cyclonic and anticyclonic mergers. Icarus (in press).

Summary:

The dynamics of mergers of large circulations in Jupiter's atmosphere may permit different models of the atmosphere to be tested. We report well-resolved observations of such events at visible wavelengths: three anticyclonic and three cyclonic events. A merger of anticyclonic white ovals in the South South Temperate domain (2002 March) is compared with the previously reported merger of ovals BE and FA in the South Temperate domain (2000 March). In each case, the two similar-sized ovals converged rapidly once they were separated by less than the sum of their diameters; they orbited around each other anticyclonically during the merger; the merged oval initially had the same rapid drift as the western parent; and, in an unexpected similarity, a cyclonic oval emerged westward from the point of merger. Evidence suggests that a merger of smaller ovals in the North North Temperate domain (2002 February) had similar dynamics. In contrast, mergers of cyclonic ovals in the North Equatorial Belt ('barges': 2001 November, 2005 May) proceeded in a different manner. The two parent barges showed no consistent acceleration towards each other as they converged; on contact there was no obvious sign of mutual circulation, and the low-albedo regions had almost passed each other before they finally merged; and the resulting barge had a drift rate intermediate between the two parents, and a length that was greater than either parent. Again, a third such event involving a smaller barge (2002 December) showed many of the same characteristics. These observations define different dynamical behaviour during anticyclonic and cyclonic mergers.

For subscribers, the article is available online via the following link:
http://dx.doi.org/10.1016/j.icarus.2006.05.022

Fletcher L.N, Orton G.S, Rogers J.H, Simon-Miller AA, de Pater I, Wong M.H, Mousis O, Irwin PGJ, Jacquesson M, Yanamandra-Fisher PA (2011). ‘Jovian Temperature and Cloud Variability during the 2009-2010 Fade of the South Equatorial Belt.’

Summary:

Mid-infrared 7–20-microns imaging of Jupiter from ESO’s Very Large Telescope (VLT/VISIR) demonstrate that the increased albedo of Jupiter’s South Equatorial Belt (SEB) during the ‘fade’ (whitening) event of 2009–2010 was correlated with changes to atmospheric temperature and aerosol opacity. The opacity of the tropospheric condensation cloud deck at pressures less than 800 mbar increased by 80% between May 2008 and July 2010, making the SEB (7–17ºS) as opaque in the thermal infrared as the adjacent equatorial zone. After the cessation of discrete convective activity within the SEB in May 2009, a cool band of high aerosol opacity (the SEB zone at 11–15̊ºS) was observed separating the cloud-free northern and southern SEB components. The cooling of the SEBZ (with peak-to-peak contrasts of 1.0 ± 0.5 K), as well as the increased aerosol opacity at 4.8 and 8.6 microns, preceded the visible whitening of the belt by several months. A chain of five warm, cloud-free ‘brown barges’ (subsiding airmasses) were observed regularly in the SEB between June 2009 and June 2010, by which time they too had been obscured by the enhanced aerosol opacity of the SEB, although the underlying warm circulation was still present in July 2010. Upper tropospheric temperatures (150–300 mbar) remained largely unchanged during the fade, but the cool SEBZ formation was detected at deeper levels (p > 300 mbar) within the convectively-unstable region of the troposphere. The SEBZ formation caused the meridional temperature gradient of the SEB to decrease between 2008 and 2010, reducing the vertical thermal windshear on the zonal jets bounding the SEB. The southern SEB had fully faded by July 2010 and was characterised by short-wave undulations at 19–20ºS. The northern SEB persisted as a narrow grey lane of cloud-free conditions throughout the fade process. The cool temperatures and enhanced aerosol opacity of the SEBZ after July 2009 are consistent with an upward flux of volatiles (e.g., ammonia-laden air) and enhanced condensation, obscuring the blue-absorbing chromophore and whitening the SEB by April 2010. These changes occurred within cloud decks in the convective troposphere, and not in the radiatively-controlled upper troposphere. NH3 ice coatings on aerosols at p < 800 mbar are plausible sources of the suppressed 4.8 and 8.6-microns emission, although differences in the spatial distribution of opacity at these two wavelengths suggest that enhanced attenuation by a deeper cloud (p > 800 mbar) also occurred during the fade. Revival of the dark SEB coloration in the coming months will ultimately require sublimation of these ices by subsidence and warming of volatile-depleted air.

Simon-Miller AA, Rogers JH, Gierasch PJ, Choi D, Allison MD, Adamoli G, Mettig H-J (2012). ‘Longitudinal variation and waves in Jupiter’s south equatorial wind jet.’

Summary:

A detailed study of the chevron-shaped dark spots on the strong southern equatorial wind jet near 7.5° S planetographic latitude shows variations in velocity with longitude and time. The presence of the large anticyclonic South Equatorial Disturbance (SED) has a profound effect on the chevron velocity, causing slower velocities to its east and increasing with distance from the disturbance. The chevrons move with velocities near the maximum wind jet velocity of ~140 m/s, as deduced by the history of velocities at this latitude and the magnitude of the symmetric wind jet near 7° N latitude. Their repetitive nature is consistent with a gravity-inertia wave (n = 75 to 100) with phase speed up to 25 m/s, relative to the local flow, but the identity of this wave mode is not well constrained. However, for the first time, high spatial resolution movies from Cassini images show that the chevrons oscillate in latitude with a 6.7 +/- 0.7-day period. This oscillating motion has a wavelength of ~20° and a speed of 101 +/- 3 m/s, following a pattern similar to that seen in the Rossby wave plumes of the North Equatorial Zone, and possibly reinforced by it. All dates show chevron latitude variability, but it is unclear if this larger wave is present during other epochs, as there are no other suitable time series movies that fully delineate it. In the presence of multiple wave modes, the difference in dominant cloud appearance between 7° N and 7.5° S is likely due to the presence of the Great Red Spot, either through changes in stratification and stability or by acting as a wave boundary.

The Supplementary Online Figures, which include most of the amateur contributions, are here:

Link to online figures

This comprises the fourth in our series of papers on the South Equatorial Disturbance. We are also posting three reports on our results, which were largely included in this paper, but these reports give more details and use our standard conventions for orientation. They are:

The life of the South Equatorial Disturbance, 1999-2010.

John Rogers

Link to file: SED 1999-2010 Final overview

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The SEBn jet and SED in 2008

Gianluigi Adamoli & John Rogers

Link to file: The SEBn jet and SED in 2008 .

(This important report summarises the whole history of the SED, with charts.)

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The SEBn in 2010: The dual motion of the chevrons in the rapid jetstream

Gianluigi Adamoli & John Rogers

Link to file: The SEBn in 2010: The dual motion of the chevrons in the rapid jetstream

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Mousis O et 31 al., ‘Instrumental Methods for Professional and Amateur Collaborations in Planetary Astronomy’ Exp.Astron., (2014) DOI
10.1007/s10686-014-9379-0

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Simon AA, Wong MH, Rogers JH, Orton GS, de Pater I, Asay-Davis X, Carlson RW & Marcus PS. ‘Dramatic Change In Jupiter’s Great Red Spot From Spacecraft

Observations.’ Astrophysical Journal Letters, 797:L31-L34 (2014 Dec.20) DOI:10.1088/2041-8205/797/2/L31

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