Venus's major cloud feature as an equatorially trapped wave distorted by the wind

Peralta, Javier; Sánchez‐Lavega, A.; López‐Valverde, M. Á.; Luz, D.; Machado, Paula Renata Lima

doi:10.1002/2014gl062280

Cited by 38 publications

(55 citation statements)

References 26 publications

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“…A candidate of wave packet with horizontal wavelength of 139 km was apparent during 20 November 2016 at ∼43°N (see white frame and its zoom in Figure i). Gravity waves were rare on NIR images during the VEx mission with one case found within 112 days of observations (Peralta et al, , figure 2C therein), and Kelvin‐type waves like the Y feature (Kouyama et al, ; Peralta et al, ; Rossow et al, ) are also missing. Since Kelvin‐type waves require a stably stratified atmosphere, its absence in NIR imagery is consistent with the understanding that NIR images may be sensing cloud contrasts at an altitude range at which static stability is low (Piccialli, , figure 5.9 therein).…”

Section: Cloud Morphologies At 900 Nmmentioning

confidence: 99%

Morphology and Dynamics of Venus's Middle Clouds With Akatsuki/IR1

Peralta

Iwagami²,

Sánchez‐Lavega

et al. 2019

Geophysical Research Letters

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The Venusian atmosphere is covered by clouds with superrotating winds whose accelerating mechanism is still not well understood. The fastest winds, occurring at the cloud tops (∼70‐km height), have been studied for decades, thanks to their visual contrast in dayside ultraviolet images. The middle clouds (∼50–55 km) can be observed at near‐infrared wavelengths (800–950 nm), although with very low contrast. Here we present the first extensive analysis of their morphology and motions at lower latitudes along 2016 with 900‐nm images from the IR1 camera onboard Akatsuki. The middle clouds exhibit hemispherical asymmetries every 4–5 days, sharp discontinuities in elongated “hook‐like” stripes, and large contrasts (3–21%) probably associated with large changes in the optical thickness. Zonal winds obtained with IR1 images and with ground‐based observations reveal mean zonal winds peaking at the equator, while their combination with Venus Express unveils long‐term variations of 20 m/s along 10 years.

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Section: Cloud Morphologies At 900 Nmmentioning

confidence: 99%

Morphology and Dynamics of Venus's Middle Clouds With Akatsuki/IR1

Peralta

Iwagami²,

Sánchez‐Lavega

et al. 2019

Geophysical Research Letters

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“…These effects are visible in the series of images taken in individual orbits. It should be noted that in this case we see a combination of at least three processes: solar tide, mountain wave, and “Y” or “V” feature (resulting from the interaction of a Kelvin wave with the zonal flow: see, e.g., Titov et al, ; Peralta et al, ). The Y feature is characterized by strong poleward deflections of the zonal flow (Patsaeva et al, ) that make the detection of the solar tide and mountain wave above Aphrodite Terra more difficult.…”

Section: Resultsmentioning

confidence: 65%

Solar‐Related Variations of the Cloud Top Circulation Above Aphrodite Terra From VMC/Venus Express Wind Fields

et al. 2019

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Winds derived by a digital tracking technique from ultraviolet (365 nm) images captured by the Venus Monitoring Camera (VMC) onboard the Venus Express spacecraft from 2006 to 2013 were used to study the atmospheric circulation at cloud top level (70 ± 2 km). This data set allows variations of the wind speed with both latitude and longitude to be studied and establishes their correlation with surface topography as well as local time dependence. Both zonal and meridional wind components show some correlation with topography. The minimum zonal wind speed was found at noon above Ovda Regio (10°S, 93°E), the highest region of Aphrodite Terra, one of the largest highlands in the equatorial region. The area of slow zonal wind extends to at least 30°S and shifts in the direction of superrotation in the afternoon and with increasing latitude (poleward). The observed deceleration of cloud top wind was recently attributed to the interaction of the gravity (mountain) waves generated by Aphrodite Terra with the atmospheric circulation. The present study was performed for different local time over the mountainous longitudes. The deceleration pattern in the zonal wind field is mainly conserved within a few hours around noon. Systematic longitude shift is observed in the afternoon in the direction of the evening terminator. Another area of perturbation of both zonal and meridional wind components is observed in the equatorial region around LT = 13–14 hr and may be explained by the solar tide.

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“…This kind of feature is different from the above described equatorial waves. Its aspect is reminiscent of the long-lived Y or C structure observed in Venus clouds (Schubert 1983) and recently identified as a wind distorted Kelvin wave by Peralta et al (2015). We first describe the observations of the feature (Sect.…”

Section: Introductionmentioning

confidence: 88%

A large active wave trapped in Jupiter’s equator

Legarreta

Barrado-Izagirre

García-Melendo

et al. 2016

A&A

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Context. A peculiar atmospheric feature was observed in the equatorial zone (EZ) of Jupiter between September and December 2012 in ground-based and Hubble Space Telescope (HST) images. This feature consisted of two low albedo Y-shaped cloud structures (Y1 and Y2) oriented along the equator and centred on it (latitude 0.5• −1 • N). Aims. We wanted to characterize these features, and also tried to find out their properties and understand their nature. Methods. We tracked these features to obtain their velocity and analyse their cloud morphology and the interaction with their surroundings. We present numerical simulations of the phenomenon based on one-and two-layer shallow water models under a Gaussian pulse excitation. Results. Each Y feature had a characteristic zonal length of ∼15• (18 000 km) and a meridional width (distance between the northsouth extremes of the Y) of 5• (6000 km), and moved eastward with a speed of around 20−40 m s −1 relative to Jupiter's mean flow. Their lifetime was 90 and 60 days for Y1 and Y2, respectively. In November, both Y1 and Y2 exhibited outbursts of rapidly evolving bright spots emerging from the Y vertex. The Y features were not visible at wavelengths of 255 or 890 nm, which suggests that they were vertically shallow and placed in altitude between the upper equatorial hazes and the main cloud deck. Numerical simulations of the dynamics of the Jovian equatorial region generate Kelvin and Rossby waves, which are similar to those in the Matsuno-Gill model for Earth's equatorial dynamics, and reproduce the observed cloud morphology and the main properties the main properties of the Y features.

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Venus's major cloud feature as an equatorially trapped wave distorted by the wind

Cited by 38 publications

References 26 publications

Morphology and Dynamics of Venus's Middle Clouds With Akatsuki/IR1

Morphology and Dynamics of Venus's Middle Clouds With Akatsuki/IR1

Solar‐Related Variations of the Cloud Top Circulation Above Aphrodite Terra From VMC/Venus Express Wind Fields

A large active wave trapped in Jupiter’s equator

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