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Decades long deep giant disturbance discovered on Venus

Decades long deep giant disturbance discovered on Venus

Examples of undulations behind the discontinuity on the night side on April 1

5, 2016. Credit: Javier Peralta / JAXA-Planet C-team

A planetary cloudburst has been regularly buzzing deep in the thick cloud on Venus for at least 35 years, says a study involving the Instituto de Astrofísica e Ciências do Espaço (IA).

In the cloudy skies of Venus, consisting mostly of carbon dioxide with clouds made of drops of sulfuric acid, a huge atmospheric disturbance that has not yet been seen anywhere else in the solar system has moved rapidly about 50 kilometers over the hidden surface and has gone unnoticed for at least 35 years. Its discovery is reported in a study now published in Geophysical research letters and had the grant from Pedro Machado, from the Institute of Astrophysics and Space Science (IA) and the Faculty of Sciences at the University of Lisbon (Sciences ULisboa).

This flat-width cloudburst can sometimes extend as far as 7,500 kilometers above the equator, from 30 º north to 40 south south, and occurs at the lower cloud level, at altitudes between 47.5 and 56.5 kilometers. The researchers discovered that this wall of acid clouds since at least 1983 sweeps the solid globe over five days at about 328 kilometers per hour.

The study was led by the Japanese space agency JAXA, which first saw what looked like an atmospheric wave, but of planet sizes. This was suggested from the high-detail infrared images taken from the planet’s night edge by JAXA’s Venus orbiter Akatsuki, which examined the middle and lower layers of the atmosphere.

“If this happened on Earth, this would be a frontal surface on the planet’s scale, and it’s incredible,” says Pedro Machado. “During the follow-up campaign, we went back to pictures I took in the infrared 2012 with the Galileo National Telescope (TNG) in the Canary Islands and we found exactly the same disturbance.”

IA contributed during its long research program that studied Venus’ winds, but also with follow-up observations with NASA’s infrared telescope facility (IRTF), in Hawaii, coordinated with new observations made from space with Akatsuki orbits.

Decades long deep giant disturbance discovered on Venus

Pattern of cloud disturbances in infrared images taken by the Japanese space agency-JAXA Akatsuki Venus orbiter 2016. Credit: Javier Peralta / JAXA-Planet C-team

While scientists have observed other giant cloud patterns in the atmosphere of Venus, such as the Y-wave or the 10,000-kilometer, arc-shaped stationary wave in the upper clouds, this is the first serious candidate for a planetary wave at low altitudes.

The deep area of ​​the atmosphere where this new disturbance was discovered is responsible for the lush greenhouse effect that retains heat and keeps the surface at a temperature of 465 degrees Celsius, warm enough to melt lead. Planetary waves like this can help establish a connection between the surface and the dynamics of the Venusian atmosphere as a whole, which to some extent is still a mystery.

Akatsuki reveals a giant cloud disturbance unnoticed for 35 years on Venus

A rapid disturbance dominates the deeper clouds of Venus in the equatorial region, which was observed in the left bottom composite made with infrared2.26 micrometer images on the night side of Venus acquired August 25-28, 2016 by the IR2 camera aboard JAXA’s Akatsuki shuttle. The long-term development of the disturbance from March 2016 to December 2018 is also shown as a sequence of smaller images. Credit: Planet-C Project Team, NASA, IRTF

“Since the disturbance cannot be observed in the ultraviolet images that sense the top of the clouds at an altitude of about 70 kilometers, it is important to confirm its wave character,” said Javier Peralta, who led this study. “We would finally have found a wave that transports speed and energy from the deep atmosphere and disappears before we reach the top of the clouds. It would therefore set off momentum exactly at the level where we observe the fastest winds in the so-called atmospheric super-protection. of Venus, the mechanisms of which have been a long-standing mystery. “

However, the mechanism that ignited and perpetuates the long-standing phenomenon of cycles of varying intensity is still unknown, despite computer simulations attempting to mimic it. According to scientists, this atmospheric disturbance is a new meteorological phenomenon, invisible on other planets, and it is therefore difficult to give a reliable physical interpretation.

Although it will be the focus of future research, the authors suggest that this disturbance may be the physical manifestation of a Kelvin-type atmospheric wave, which propagates and is trapped around the equator. Kelvin waves are a class of atmospheric gravitational waves that share important common features with this disorder. For example, they spread in the same direction as the super-rotating winds and without any obvious effect on the gusts, the winds that blow from the equator towards the poles.

Kelvin waves can interact with other types of atmospheric waves such as those that occur naturally as a result of the planet’s rotation, the Rossby waves. These can cause the transport of energy from the superrotation to the equator.

By reviewing images taken as far back as 1983, the researchers were able to confirm the existence of the same functions. According to Pedro Machado, it was unnoticed for so long because “we needed access to a large, growing and scattered collection of images of Venus collected in recent decades using various telescopes.”

Atmospheric tidal waves maintain Venus’ superrotation

More information:
J. Peralta et al. A long-lasting sharp disturbance on the lower clouds of Venus, Geophysical research letters (2020). DOI: 10.1029 / 2020GL087221

Provided by the Institute of Astrophysics and Space Sciences

Quote: Decades of deep giant cloud disturbance detected on Venus (2020, August 6) retrieved August 6, 2020 from https://phys.org/news/2020-08-decades-long-deep-giant-cloud-disruption.html

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