Javier Peralta

Javier Peralta
Unemployed

PhD Planetary Atmospheres

About

87
Publications
18,296
Reads
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1,696
Citations
Additional affiliations
April 2015 - March 2020
Japan Aerospace Exploration Agency
Position
  • Fellow
February 2013 - December 2014
Instituto De Astrofisica De Andalucia
Position
  • PostDoc Position
February 2010 - January 2013
University of Lisbon
Position
  • Atmospheric Dynamics of Venus
Education
April 2005 - March 2009
Universidad del País Vasco / Euskal Herriko Unibertsitatea
Field of study
  • Winds, Turbulence and Waves in the Atmosphere of Venus

Publications

Publications (87)
Article
In this work we analyzed nadir observations of atmospheric infrared emissions carried out by VIRTIS, a high-resolution spectrometer onboard the European spacecraft Venus Express. We focused on the ro-vibrational band of CO2 at 4.3 µm in the dayside, whose fluorescence is originated in the Venus upper mesosphere and above. This is the first time tha...
Article
Full-text available
Context. First identified in 2016 by the Japan Aerospace eXploration Agency (JAXA) Akatsuki mission, the discontinuity or disruption is a recurrent wave observed to propagate over decades at the deeper clouds of Venus (47–56 km above the surface), while its absence at the top of the clouds (∼70 km) suggests that it dissipates at the upper clouds an...
Preprint
Full-text available
First identified in 2016 by JAXA's Akatsuki mission, the discontinuity/disruption is a recurrent wave observed to propagate during decades at the deeper clouds of Venus (47--56 km above the surface), while its absence at the clouds' top ($\sim$70 km) suggests that it dissipates at the upper clouds and contributes in the maintenance of the puzzling...
Preprint
Full-text available
Firstly identified in images from JAXA's orbiter Akatsuki, the cloud discontinuity of Venus is a planetary-scale phenomenon known to be recurrent since, at least, the 1980s. Interpreted as a new type of Kelvin wave, this disruption is associated to dramatic changes in the clouds' opacity and distribution of aerosols, and it may constitute a critica...
Article
Full-text available
Firstly identified in images from JAXA’s orbiter Akatsuki, the cloud discontinuity of Venus is a planetary-scale phenomenon known to be recurrent since, at least, the 1980s. Interpreted as a new type of Kelvin wave, this disruption is associated to dramatic changes in the clouds’ opacity and distribution of aerosols, and it may constitute a critica...
Article
Full-text available
Characterizing the wind speeds of Venus and their variability at multiple vertical levels is essential for a better understanding of the atmospheric superrotation, constraining the role of large-scale planetary waves in the maintenance of this superrotation, and in studying how the wind field affects clouds’ distribution. Here, we present cloud-tra...
Article
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We present images of Venus from the Wide‐Field Imager for Parker Solar Probe (WISPR) telescope on board the Parker Solar Probe (PSP) spacecraft, obtained during PSP's third and fourth flybys of Venus on 2020 July 11 and 2021 February 20, respectively. Thermal emission from the surface is observed on the night side, representing the shortest wavelen...
Article
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A cloud opacity contrast feature that has been called a “long-lived sharp disruption” has been seen in the atmosphere of Venus in the near-infrared using Akatsuki’s IR2 camera, most clearly at equatorial latitudes. This feature was found to have a consistent planet-circling period of 4.9 days, and subsequent searches of past imagery revealed that i...
Article
Full-text available
Although Venus is a terrestrial planet similar to Earth, its atmospheric circulation is much different and poorly characterized¹. Winds at the cloud top have been measured predominantly on the dayside. Prominent poleward drifts have been observed with dayside cloud tracking and interpreted to be caused by thermal tides and a Hadley circulation2–4;...
Preprint
Full-text available
We present the detection and characterisation of mesoscale waves on the lower clouds of Venus using images from the Visible Infrared Thermal Imaging Spectrometer onboard the European Venus Express space mission and from the 2 $\mu$m camera (IR2) instrument onboard the Japanese space mission Akatsuki. We used image navigation and processing techniqu...
Article
Full-text available
We present new results of our studies of zonal and meridional winds in both hemispheres of Venus, using ground- and space-based coordinated observations. The results obtained from telescope observations were retrieved with a Doppler velocimetry method. The wind velocities retrieved from space used an improved cloud-tracked technique based on the ph...
Cover Page
Full-text available
Review article on latest scientific discoveries on Venus.
Article
We present the detection and characterisation of mesoscale waves on the lower clouds of Venus using images from the Visible Infrared Thermal Imaging Spectrometer onboard the European Venus Express space mission and from the 2 μm camera (IR2) instrument onboard the Japanese space mission Akatsuki. We used image navigation and processing techniques b...
Preprint
Full-text available
The National Academy Committee on Astrobiology and Planetary Science (CAPS) made a recommendation to study a large/medium-class dedicated space telescope for planetary science, going beyond the Discovery-class dedicated planetary space telescope endorsed in Visions and Voyages. Such a telescope would observe targets across the entire solar system,...
Preprint
Full-text available
We advocate for a mission concept study for a space telescope dedicated to solar system science in Earth orbit. Such a study was recommended by the Committee on Astrobiology and Planetary Science (CAPS) report "Getting Ready for the Next Planetary Science Decadal Survey." The Mid-Decadal Review also recommended NASA to assess the role and value of...
Article
Full-text available
Plain Language Summary One of the biggest mysteries of Venus is its atmospheric superrotation that allows the atmosphere to rotate 60 times faster than the solid planet. Atmospheric waves are among one of the possible mechanisms thought to feed this superrotation by pushing energy to different locations of the atmosphere. In fact, the upper clouds...
Article
Full-text available
We mapped the distribution of the 365‐nm albedo of the Venus atmosphere over the years 2006–2014, using images acquired by the Venus Monitoring Camera (VMC) on board Venus Express. We selected all images with a global view of Venus to investigate how the albedo depends on longitude. Bertaux et al. (2016, https://doi.org/10.1002/2015JE004958) report...
Preprint
Full-text available
Planetary-scale waves are thought to play a role in powering the yet-unexplained atmospheric superrotation of Venus. Puzzlingly, while Kelvin, Rossby and stationary waves manifest at the upper clouds (65--70 km), no planetary-scale waves or stationary patterns have been reported in the intervening level of the lower clouds (48--55 km), although the...
Article
Full-text available
In June 2015, Cassini high-resolution images of Saturn’s limb southwards of the planet’s hexagonal wave revealed a system of at least six stacked haze layers above the upper cloud deck. Here, we characterize those haze layers and discuss their nature. Vertical thickness of layers ranged from 7 to 18 km, and they extended in altitude ∼130 km, from p...
Article
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Explaining super-rotation on Venus The solid surface of Venus rotates very slowly, once every 243 days, but its thick atmosphere circles the planet in just 4 days. This phenomenon, known as super-rotation, requires a continuous input of angular momentum, from an unknown source, to overcome friction with the surface. Horinouchi et al. mapped the pla...
Article
Full-text available
An unknown absorber near the cloud-top level of Venus generates a broad absorption feature from the ultraviolet (UV) to visible, peaking around 360 nm, and therefore plays a critical role in the solar energy absorption. We present a quantitative study of the variability of the cloud albedo at 365 nm and its impact on Venus’s solar heating rates bas...
Preprint
Full-text available
An unknown absorber near the cloud top level of Venus generates a broad absorption feature from the ultraviolet (UV) to visible, peaking around 360 nm, and therefore plays a critical role in the solar energy absorption. We present a quantitative study on the variability of the cloud albedo at 365 nm and its impact on Venus' solar heating rates base...
Preprint
Full-text available
During the years 2016 to 2018, the instruments Akatsuki/IR2 (JAXA) and IRTF/SpeX (NASA) acquired a large set of images at 1.74, 2.26 and 2.32 {\mu}m to study the nightside mid-to-lower clouds (48-60 km) of Venus. Here we summarize the rich variety of cloud morphologies apparent in these images: from frequent wave packets and billows caused by shear...
Article
Full-text available
During the years 2016 to 2018, the instruments Akatsuki/IR2 (JAXA) and IRTF/SpeX (NASA) acquired a large set of images at 1.74, 2.26 and 2.32 μm to study the nightside mid-to-lower clouds (48–60 km) of Venus. Here we summarize the rich variety of cloud morphologies apparent in these images: from frequent wave packets and billows caused by shear ins...
Article
Full-text available
Plain Language Summary The atmosphere Venus is surprisingly fast with velocities 60 times faster than the solid globe of Venus. This atmospheric phenomenon is called superrotation and its mechanisms are yet unexplained for the scientists. The Japanese space mission Akatsuki from the Japan Aerospace Exploration Agency arrived at Venus in December 20...
Article
Full-text available
Venus is covered with thick clouds. Ultraviolet (UV) images at 0.3–0.4 microns show detailed cloud features at the cloud-top level at about 70 km, which are created by an unknown UV-absorbing substance. Images acquired in this wavelength range have traditionally been used to measure winds at the cloud top. In this study, we report low-latitude wind...
Article
Full-text available
Since insertion into orbit on December 7, 2015, the Akatsuki orbiter has returned global images of Venus from its four imaging cameras at eleven discrete wavelengths from ultraviolet (283 and 365 nm) and near infrared (0.9–2.3 µm), to the thermal infrared (8–12 µm) from a near-equatorial orbit. The Venus Express and Pioneer Venus Orbiter missions h...
Article
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We present measurements of the wind speeds at the nightside lower clouds of Venus from observations by JAXA's mission Akatsuki during 2016, complemented with new wind measurements from ground-based observations acquired with TNG/NICS in 2012 and IRTF/SpeX in 2015 and 2017. Zonal and meridional components of the winds were measured from cloud tracki...
Preprint
Full-text available
We present measurements of the wind speeds at the nightside lower clouds of Venus from observations by JAXA's mission Akatsuki during 2016, complemented with new wind measurements from ground-based observations acquired with TNG/NICS in 2012 and IRTF/SpeX in 2015 and 2017. Zonal and meridional components of the winds were measured from cloud tracki...
Preprint
Full-text available
This PhD thesis consists on a study of the atmospheric dynamics of the planet Venus with data from two space missions separated in time: the Galileo mission and Venus Express. Concretely, images obtained with different wavelengths have been used to study the motions of the clouds at different vertical levels of the atmosphere, enabling to track the...
Article
Full-text available
One of the most intriguing, long-standing questions regarding Venus' atmosphere is the origin and distribution of the unknown UV-absorber, responsible for the absorption band detected at the near-UV and blue range of Venus' spectrum. In this work, we use data collected by MASCS spectrograph on board the MESSENGER mission during its second Venus fly...
Article
One of the most intriguing, long-standing questions regarding Venus' atmosphere is the origin and distribution of the unknown UV-absorber, responsible for the absorption band detected at the near-UV and blue range of Venus' spectrum. In this work, we use data collected by MASCS spectrograph on board the MESSENGER mission during its second Venus fly...
Article
The Venusian atmosphere is in a state of superrotation where prevailing westward winds move much faster than the planet’s rotation. Venus is covered with thick clouds that extend from about 45 to 70 km altitude, but thermal radiation emitted from the lower atmosphere and the surface on the planet’s nightside escapes to space at narrow spectral wind...
Article
At the cloud top level of Venus (65-70 km altitude) the atmosphere rotates 60 times faster than the underlying surface, a phenomenon known as superrotation. Whereas on Venus's dayside the cloud top motions are well determined and Venus general circulation models predict a mean zonal flow at the upper clouds similar on both day and nightside, the ni...
Article
Abstract New tables to observe the planet Venus are presented with detailed information about the main spectral regions from 100 nm to 1 mm. The information hereby is updated thanks to the Venus Express legacy and recent ground-based observations, and we hope it can constitute a helpful tool for professional and amateur observers willing to support...
Article
Full-text available
Even though many missions have explored the Venus atmospheric circulation, its instantaneous state is poorly characterized. In situ measurements vertically sampling the atmosphere exist for limited locations and dates, while remote-sensing observations provide only global averages of winds at altitudes of the clouds: 47, 60 and 70 km. We present a...
Data
Figure S1: Similar to Fig. 2c, but it demonstrates the expected error in the estimated vorticity, which is dependent on the scale of interest.
Article
We report Venus image observations around the two maximum elongations of the planet at June and October 2015. From these images we describe the global atmospheric dynamics and cloud morphology in the planet before the arrival of JAXA’s Akatsuki mission on December the 7th. The majority of the images were acquired at ultraviolet wavelengths (380-410...
Article
Full-text available
AKATSUKI is the Japanese Venus Orbiter designed to investigate the climate system of Venus. It was launched on May 21, 2010 and reached Venus on December 7, 2010. Thrust was applied by the orbital maneuver engine in an attempt to put AKATSUKI into a westward equatorial orbit around Venus with a 30 hours' orbital period. However, this operation fail...
Article
Full-text available
The discovery of almost 2000 exoplanets has revealed an unexpectedly diverse planet population. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are plane...
Article
The Venus Express mission has provided a long-term monitoring of Venus atmosphere including the morphology and motions of its upper clouds. Several works have focused on the dynamics of the upper cloud visible on the day-side in ultraviolet images sensitive to the 65-70 km altitude and in the lower cloud level (50 km height) observable in the night...
Article
The superrotation of the atmospheres of slowly rotating bodies is a longstanding problem yet unsolved in atmospheric dynamics. On Venus, the most extreme case known of superrotation, this is accompanied and influenced by a recurrent planetary-scale cloud structure, known as the Y-feature. So far, no model has simultaneously reproduced its shape, te...
Article
We present new results based on ground-based Doppler spectroscopic measurements, obtained with the ESPaDOnS spectrograph at Canada-France-Hawaii telescope (CFHT) and simultaneous observations of velocity fields, obtained from space by the VIRTIS-M instrument on board the Venus Express spacecraft. These measurements are based on high-resolution spec...
Article
Full-text available
This paper is the first of a two-part study devoted to developing tools for a systematic classification of the wide variety of atmospheric waves expected on slowly rotating planets with atmospheric superrotation. Starting from the primitive equations for a cyclostrophic regime we have deduced the analytical solution for the possible waves, simultan...
Article
Full-text available
This paper is the second of a two-part study devoted to developing tools for a systematic classification of the wide variety of atmospheric waves expected on slowly rotating planets with atmospheric superrotation. Starting from the primitive equations for a cyclostrophic regime we have deduced the analytical solution for the possible waves, simulta...
Article
High resolution images of Venus Northern hemisphere obtained with the Venus Monitoring Camera (VMC/VEx) allow studying small-scale dynamical phenomena at the cloud tops (∼62–70 km altitude) including features like wave trains. A systematic visual search of these waves was performed; more than 1500 orbits were analyzed and wave patterns were observe...
Article
Full-text available
Polar vortices are common in the atmospheres of rapidly rotating planets(1-4). On Earth and Mars, vortices are generated by surface temperature gradients and their strength is modulated by the seasonal insolation cycle(1-3). Slowly rotating Venus lacks pronounced seasonal forcing, but vortices are known to occur at both poles, in an atmosphere that...
Article
Full-text available
By examining electron density profiles from the Mars Express Radio Science Experiment MaRS, we show that the vertical structure of the dayside ionosphere of Mars is more variable and more complex than previously thought. The top of the ionosphere can be below 250 km (25\% occurrence rate) or above 650 km (1\%); the topside ionosphere can be well-de...
Article
After 6 years orbiting Venus the Venus Express mission has provided a large database of visual and infrared observations of the Venus clouds at different layers with the VMC and VIRTIS instruments. We present further measurements of cloud motions in the South hemisphere of Venus obtained from observations at different wavelengths and atmospheric al...
Conference Paper
Full-text available
The effect of the solar tides on the winds at the top of the clouds in Venus has been studied using cloud tracking technique applied to the Venus Express/VIRTIS-M images taken at wavelengths of 3.8 and 5.0 μm. Both these wavelengths probe about the same altitude on the clouds top, allowing for the first time to retrieve winds in the dayside and nig...
Conference Paper
Full-text available
polar region of Venus, using measurements from the VIRTIS instrument from the Venus Express Mission, revealed it to be in constant dynamic change, with the southern polar vortex displaced from the rotational geometry of the planet [1]. Here, we place these results in the context of measurements taken over a two year period. We examine the dynamics...
Article
The observation, characterization, and understanding of planetary atmospheres are key components of Solar System exploration. Their study requires, among other observations, the use of image data acquired from spacecrafts. The basic tasks that are generally used to work with planetary image data are: image navigation, projection, image processing,...
Conference Paper
The Venus Express (VEX) mission has been in orbit to Venus for almost four years now. The VIRTIS instrument onboard VEX observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet. Images in the ultraviolet range are used to study the upper cloud at 66 km while images in the infrared (1.74 mum)...