Final Results on Atmospheric Wave Characterisation on the Nightside Lower Clouds of Venus

2021 ◽  
Author(s):  
José Silva ◽  
Pedro Machado ◽  
Javier Peralta ◽  
Francisco Brasil ◽  
Sebastien Lebonnois ◽  
...  
Keyword(s):  
Infrared Imaging ◽  
Effective Means ◽  
Morphological Properties ◽  
Imaging Data ◽  
Geophysical Research ◽  
Restoring Force ◽  
Infrared Thermal Imaging ◽  
Atmospheric Waves ◽  
Support Mechanism ◽  
Lower Cloud

<p>An atmospheric internal gravity wave is a oscillatory disturbance on an atmospheric layer in which buoyancy acts as the restoring force. As such, they can only exist in a continuously stably stratified atmosphere, that is, a fluid in which the static stability is positive and horizontal variations in pressure are negligible when compared to the vertical variations (in altitude) [Gilli et al. 2020; Peralta et al. 2008]. These waves are of particular interest because they represent an effective means of energy and momentum transport across various layers of a planetary atmosphere, as these waves can form on one atmospheric region and travel through the atmosphere, sometimes over great distances, and dump their contained energy upon wave dissipation or breaking [Alexander et al. 2010]. Given these properties, study of atmospheric waves on Venus becomes important as another tool to answer some of the fundamental question surrounding its atmosphere dynamics, mainly the origin and support mechanism of the remarkable superrotation of the atmosphere.<br>We present here the final results on a study conducted on the nightside lower cloud of Venus to detect and characterise mesoscale waves. This analysis was conducted with infrared imaging data from both the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) onboard Venus Express (Vex) [Svedhem et al. 2007] and the 2-micron camera (IR2) onboard Akatsuki [Nakamura et al. 2011, Satoh et al. 2016] space missions. We covered the entire VIRTIS-M-IR archive selecting the 1.74- and 2.25-micron wavelengths as well as all available images from the IR2 camera at 2.26 microns to ensure a most comprehensive survey and through image navigation and processing we were able to characterise approximately 300 wave packets across more than 5500 images over a broad range of latitudes on Venus. From these waves we retrieved basic morphological properties such as horizontal wavelength, number of crests and the full extent of the wave. Additionally, we were able to track the evolution of waves as they moved on the atmosphere, enabling some dynamical characterisation. The panel below shows examples of atmospheric waves observed in this study. Figures A-C show VIRTIS-M-IR images while figures D-F show IR2 data. All images have been subject to contrast enhancement techniques to improve observability of waves.</p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.664bc41e16a062149941261/sdaolpUECMynit/1202CSPE&app=m&a=0&c=4d76fa87765c4d96de6f9a4578649e21&ct=x&pn=gnp.elif&d=1" alt=""></p><p>Our goal was to provide a survey on atmospheric waves in the lower cloud as complete as possible, using two different instruments which cover in detail different sections of the globe of Venus over a long-time span, expanding on other studies performed by Peralta et al. (2008), (2019). With the larger data base, we discuss the nature of these waves, possible forcing mechanisms, and their relationship with the background atmosphere. Several questions remain however, such as how much energy do these waves transport in the cloud layer and how much do they contribute to Venus’ superrotation and if there is a dominant source of excitation for these waves. Full details of these results can be found in Silva et al. (2021) and we hope that these updated results can prove useful to recent and future models of Venus atmosphere as well as atmosphere of other slow rotators in the Solar System.</p><p><br><strong>References</strong></p><ul><li>Alexander M.J. et al, Quarterly Journal of the Royal Meteorological Society, vol. 136, pp. 1103-1124, 2010;</li> <li>Gilli G. et al, Journal of Geophys. Research – Planets, ID. e05873, 2020;</li> <li>Nakamura M. et al, Earth, Planets and Space, vol. 63, pp. 443-457, 2011;</li> <li>Peralta J. et al, Journal of Geophysical Research, vol. 113, ID. E00B18, 2008;</li> <li>Peralta J. et al, Icarus, vol. 333, pp. 177-182, 2019;</li> <li>Satoh T. et al, Earth, Planets and Space, vol. 68, ID. 74, 2016;</li> <li>Silva J. et al, A&A, vol. 649, ID. A34, 2021;</li> <li>Svedhem H. et al, Planetary and Space Science, vol. 55, pp. 1636-1652, 2007;</li> </ul>

scholarly journals Winds in the Lower Cloud Level on the Nightside of Venus from VIRTIS-M (Venus Express) 1.74 μm Images

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 186
Author(s):  
Dmitry A. Gorinov ◽  
Ludmila V. Zasova ◽  
Igor V. Khatuntsev ◽  
Marina V. Patsaeva ◽  
Alexander V. Turin
Keyword(s):  
Wind Speed ◽  
Meridional Wind ◽  
Equatorial Region ◽  
Hadley Cell ◽  
Horizontal Wind ◽  
Simultaneous Increase ◽  
Volcanic Area ◽  
Infrared Thermal Imaging ◽  
Latitude Range ◽  
Lower Cloud

The horizontal wind velocity vectors at the lower cloud layer were retrieved by tracking the displacement of cloud features using the 1.74 µm images of the full Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS-M) dataset. This layer was found to be in a superrotation mode with a westward mean speed of 60–63 m s−1 in the latitude range of 0–60° S, with a 1–5 m s−1 westward deceleration across the nightside. Meridional motion is significantly weaker, at 0–2 m s−1; it is equatorward at latitudes higher than 20° S, and changes its direction to poleward in the equatorial region with a simultaneous increase of wind speed. It was assumed that higher levels of the atmosphere are traced in the equatorial region and a fragment of the poleward branch of the direct lower cloud Hadley cell is observed. The fragment of the equatorward branch reveals itself in the middle latitudes. A diurnal variation of the meridional wind speed was found, as east of 21 h local time, the direction changes from equatorward to poleward in latitudes lower than 20° S. Significant correlation with surface topography was not found, except for a slight decrease of zonal wind speed, which was connected to the volcanic area of Imdr Regio.

scholarly journals The deep Chandra survey in the SDSS J1030+0524 field

2020 ◽  
Vol 637 ◽  
pp. A52 ◽  
Author(s):  
R. Nanni ◽  
R. Gilli ◽  
C. Vignali ◽  
M. Mignoli ◽  
A. Peca ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Cumulative Number ◽  
Imaging Data ◽  
X Ray ◽  
Large Scale Structures ◽  
Multi Wavelength ◽  
Deep Fields ◽  
Initial Source

We present the X-ray source catalog for the ∼479 ks Chandra exposure of the SDSS J1030+0524 field, which is centered on a region that shows the best evidence to date of an overdensity around a z > 6 quasar, and also includes a galaxy overdensity around a Compton-thick Fanaroff-Riley type II (FRII) radio galaxy at z = 1.7. Using wavdetect for initial source detection and ACIS Extract for source photometry and significance assessment, we create preliminary catalogs of sources that are detected in the full (0.5−7.0 keV), soft (0.5−2.0 keV), and hard (2−7 keV) bands, respectively. We produce X-ray simulations that mirror our Chandra observation to filter our preliminary catalogs and achieve a completeness level of > 91% and a reliability level of ∼95% in each band. The catalogs in the three bands are then matched into a final main catalog of 256 unique sources. Among them, 244, 193, and 208 are detected in the full, soft, and hard bands, respectively. The Chandra observation covers a total area of 335 arcmin2 and reaches flux limits over the central few square arcmins of ∼3 × 10−16, 6 × 10−17, and 2 × 10−16 erg cm−2 s−1 in the full, soft, and hard bands, respectively This makes J1030 field the fifth deepest extragalactic X-ray survey to date. The field is part of the Multiwavelength Survey by Yale-Chile (MUSYC), and is also covered by optical imaging data from the Large Binocular Camera (LBC) at the Large Binocular Telescope (LBT), near-infrared imaging data from the Canada France Hawaii Telescope WIRCam (CFHT/WIRCam), and Spitzer IRAC. Thanks to its dense multi-wavelength coverage, J1030 represents a legacy field for the study of large-scale structures around distant accreting supermassive black holes. Using a likelihood ratio analysis, we associate multi-band (r, z, J, and 4.5 μm) counterparts for 252 (98.4%) of the 256 Chandra sources, with an estimated reliability of 95%. Finally, we compute the cumulative number of sources in each X-ray band, finding that they are in general agreement with the results from the Chandra Deep Fields.

scholarly journals Galaxy build-up at cosmic dawn: Insights from deep observations with Hubble, Spitzer, and ALMA

2019 ◽  
Vol 15 (S352) ◽  
pp. 12-12
Author(s):  
Pascal Oesch
Keyword(s):  
Rest Frame ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Hubble Space Telescope ◽  
Uv Light ◽  
Big Bang ◽  
Limited Information ◽  
Imaging Data ◽  
Early Galaxies ◽  
Stellar Masses

AbstractOver the last few years, great progress has been made in understanding the build-up of the first generations of galaxies based on deep optical and near-infrared imaging from the Hubble Space Telescope. However, HST only samples the rest-frame UV light of galaxies at z …4, providing only limited information on the dust obscuration and on stellar masses of these sources. Fortunately, several Spitzer/IRAC programs have complemented the extragalactic HST fields with ultra-deep imaging data, allowing for a rest-frame optical view on early galaxies. Together with first ALMA/ NOEMA (sub)mm observations on distant galaxies, we are starting to gain a more and more complete picture of galaxy star-formation and mass build-up in the early universe. In this talk, I will present an overview of our current understanding of normal star-forming galaxies at z > 3 based the combination of HST+Spitzer+ALMA/NOEMA data. In particular, I will show how HST as already pushed into JWST territory with the discovery and spectroscopic confirmation of a galaxy at z = 11.1 ± 0.1, only : 400 Myr after the Big Bang. I will also highlight some of the exciting possibilities that lie ahead with JWST to push the spectroscopic frontier to the cosmic dawn and to finally probe the physics of early galaxies.

scholarly journals An investigation of the Temperature Distribution of a Thin Steel Strip during the Quenching Step of a Hardening Process

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 675 ◽  
Author(s):  
Pouyan Pirouznia ◽  
Nils Å. I. Andersson ◽  
Anders Tilliander ◽  
Pär G. Jönsson
Keyword(s):  
Temperature Distribution ◽  
Numerical Model ◽  
Thermal Imaging ◽  
Steel Strip ◽  
Imaging Data ◽  
Infrared Thermal Imaging ◽  
Hardening Process ◽  
Real Process ◽  
Significant Temperature

The dimension quality of the strip within the hardening process is an essential parameter, which great attention needs to be paid. The flatness of the final product is influenced by the temperature distribution of the strip, specifically across the width direction. Therefore, based on physical theories, a numerical model was established. The temperature of the strip for the section before the martensitic transformation was objected in the predicted model by using a steady state approach. In addition an infrared thermal imaging camera was applied in the real process in order to validate the results and to improve the boundary conditions of the numerical model. The results revealed that the temperature of strip decreased up to 250 °C within the area between the furnace and the quenching bath. This, in turn, resulted in significant temperature difference across the width of the strip. This difference can be up to 69 °C and 41 °C according to the numerical results and thermal imaging data, respectively. Overall, this study gave a better insight into the cooling step in the hardening process. In addition, this investigation can be used to improve the hardening process as well as an input for future thermal stress investigations.

Experimental Aspects of Asynchronous Rapid-Scan Fourier Transform Infrared Imaging

2005 ◽  
Vol 59 (9) ◽  
pp. 1075-1081 ◽  
Author(s):  
Christopher M. Snively ◽  
Jochen Lauterbach
Keyword(s):  
Fourier Transform ◽  
Data Collection ◽  
Data Quality ◽  
Infrared Imaging ◽  
Fourier Transform Infrared ◽  
Data Sampling ◽  
Imaging Data ◽  
Zero Crossings ◽  
Rapid Scan ◽  
Acquisition Scheme

In the asynchronous, rapid-scan approach to Fourier transform infrared (FT-IR) imaging, data sampling is not correlated with the zero crossings of the interference fringes of the HeNe reference laser. The success of this data collection scheme depends on the reproducibility of the clock signals driving the interferometer mirror and focal plane array data collection. In previous studies, it was shown that this implementation provides for markedly faster data acquisition without sacrificing data quality, as compared with step-scan imaging. This approach to data collection introduces some unique peculiarities to the acquisition and processing of imaging data. The purpose of this paper is to address a few of these concerns in terms of their effect on final data quality. Also, the practical aspects of implementing such an acquisition scheme are described in detail.

scholarly journals Smartphone-based infrared thermal imaging for differentiating venomous snakebites from non-venomous and dry bites

2020 ◽  
Author(s):  
Paramasivam Sabitha ◽  
Chanaveerappa Bammigatti ◽  
Surendran Deepanjali ◽  
Bettadpura Shamanna Suryanarayana ◽  
Tamilarasu Kadhiravan
Keyword(s):  
Thermal Imaging ◽  
Infrared Imaging ◽  
Hot Spot ◽  
Body Part ◽  
Night Vision ◽  
Care Providers ◽  
Infrared Thermal Imaging ◽  
Thermal Images ◽  
Thermal Changes ◽  
Infrared Thermal Images

AbstractBackgroundLocal envenomation following snakebites is accompanied by thermal changes, which could be visualized using infrared imaging. We explored whether infrared thermal imaging could be used to differentiate venomous snakebites from non-venomous and dry bites.MethodsWe prospectively enrolled adult patients with a history of snakebite in the past 24 hours presenting to the emergency of a teaching hospital in southern India. A standardized clinical evaluation for symptoms and signs of envenomation including 20-minute whole-blood clotting test and prothrombin time was performed to assess envenomation status. Infrared thermal imaging was done at enrolment, 6 hours, and 24 hours using a smartphone-based device under ambient conditions. Processed infrared thermal images were independently interpreted twice by a reference rater and once by three novice raters.FindingsWe studied 89 patients; 60 (67%) of them were male. Median (IQR) time from bite to enrolment was 11 (6.5—15) hours; 21 (24%) patients were enrolled within 6 hours of snakebite. In all, 48 patients had local envenomation with/without systemic envenomation, and 35 patients were classified as non-venomous/dry bites. Envenomation status was unclear in six patients. At enrolment, area of increased temperature around the bite site (Hot spot) was evident on infrared thermal imaging in 45 of the 48 patients with envenomation, while hot spot was evident in only 6 of the 35 patients without envenomation. Presence of hot spot on baseline infrared thermal images had a sensitivity of 93.7% (95% CI 82.8% to 98.7%) and a specificity of 82.9% (66.3% to 93.4%) to differentiate envenomed patients from those without envenomation. Interrater agreement for identifying hot spots was more than substantial (Kappa statistic >0.85), and intrarater agreement was almost perfect (Kappa = 0.93). Paradoxical thermal changes were observed in 14 patients.ConclusionsPoint-of-care infrared thermal imaging could be useful in the early identification of non-venomous and dry snakebites.Author summaryMost poisonous snakebites cause swelling of the bitten body part within a few hours if venom had been injected. Usually, health care providers diagnose poisonous snakebites by doing a clinical examination and by testing for incoagulable blood. If no abnormalities are found, then the snakebite is diagnosed as a non-poisonous bite or a dry bite. Swelling of the bitten body part results from venom-induced inflammation and is accompanied by local increase in skin temperature. It is possible to capture visual images of these temperature changes by using infrared imaging, the same technology used in night vision cameras. This study found that most persons with poisonous snakebites had hot areas on infrared images while such changes were observed in only a few persons with non-poisonous or dry snakebites. This new knowledge could help doctors identify non-poisonous and dry snakebites early.

scholarly journals Stellar substructures in the periphery of the magellanic clouds with the VISTA hemisphere survey from the red clump and other tracers

2021 ◽  
Author(s):  
Dalal El Youssoufi ◽  
Maria-Rosa L Cioni ◽  
Cameron P M Bell ◽  
Richard de Grijs ◽  
Martin A T Groenewegen ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Magellanic Clouds ◽  
Imaging Data ◽  
The North ◽  
The Galaxy ◽  
History Of ◽  
Northern Side ◽  
Red Clump ◽  
Interaction History

Abstract We study the morphology of the stellar periphery of the Magellanic Clouds in search of substructure using near–infrared imaging data from the VISTA Hemisphere Survey (VHS). Based on the selection of different stellar populations using the (J − Ks, Ks) colour–magnitude diagram, we confirm the presence of substructures related to the interaction history of the Clouds and find new substructures on the eastern side of the LMC disc which may be owing to the influence of the Milky Way, and on the northern side of the SMC, which is probably associated to the ellipsoidal structure of the galaxy. We also study the luminosity function of red clump stars in the SMC and confirm the presence of a bi–modal distance distribution, in the form of a foreground population. We find that this bi–modality is still detectable in the eastern regions of the galaxy out to a 10○ distance from its centre. Additionally, a background structure is detected in the North between 7○ and 10○ from the centre which might belong to the Counter Bridge, and a foreground structure is detected in the South between 6○ and 8○ from the centre which might be linked to the Old Bridge.

Parsing out of Infrared Thermal Imaging Temperature Field Based on BP Neural Network

2013 ◽  
Vol 437 ◽  
pp. 501-504 ◽  
Author(s):  
Zhi Zhong Sun ◽  
Xiao Lei Chen
Keyword(s):  
Neural Network ◽  
Temperature Field ◽  
Bp Neural Network ◽  
Infrared Imaging ◽  
Image Data ◽  
Thermal Image ◽  
Infrared Thermal Imaging ◽  
Infrared Imager ◽  
Temperature Filed ◽  
Thermal Infrared Imager

As a kind of infrared imaging equipment, thermal infrared imager plays an important role not only for military use, but also for civil. However, data of temperature filed cannot be obtained from thermal image directly. Accordingly, digital image processing technology and BP neural network were employed to analysis thermal image. Data of the whole temperature field were restored from the thermal image for further processing.

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