scholarly journals Phosphine in Venus’ atmosphere: Detection attempts and upper limits above the cloud top assessed from the SOIR/VEx spectra

2020 ◽  
Vol 645 ◽  
pp. L4
Author(s):  
L. Trompet ◽  
S. Robert ◽  
A. Mahieux ◽  
F. Schmidt ◽  
J. Erwin ◽  
...  
Keyword(s):  
Vertical Profile ◽  
Spectral Signature ◽  
Spectral Signatures ◽  
James Clerk Maxwell ◽  
Solar Occultation ◽  
Upper Limits ◽  
Infrared Spectral ◽  
Biogenic Source ◽  
Venus Atmosphere ◽  
Atmosphere Of Venus

Context. Recent detection of phosphine (PH3) was reported from James Clerk Maxwell Telescope and Atacama Large Millimetre/submillimetre Array observations. The presence of PH3 on Venus cannot be easily explained in the Venus atmosphere and a biogenic source located at or within the clouds was proposed. Aims. We aim to verify if the infrared spectral signature of PH3 is present in the spectra of Solar Occultation at Infrared (SOIR). If it is not present, we then seek to derive the upper limits of PH3 from SOIR spectra. Methods. We analyzed the SOIR spectra containing absorption lines of PH3. We searched for the presence of PH3 lines. If we did not find any conclusive PH3 spectral signatures, we computed the upper limits of PH3. Results. We report no detection of PH3. Upper limits could be determined for all of the observations, providing strong constraints on the vertical profile of PH3 above the clouds. Conclusions. The SOIR PH3 upper limits are almost two orders of magnitude below the announced detection of 20 ppb and provide the lowest known upper limits for PH3 in the atmosphere of Venus.

An infrared spectral signature of human lymphocyte subpopulations from peripheral blood

The Analyst ◽  
2015 ◽  
Vol 140 (7) ◽  
pp. 2257-2265 ◽  
Author(s):  
N. Wald ◽  
A. Legat ◽  
C. Meyer ◽  
D. E. Speiser ◽  
E. Goormaghtigh
Keyword(s):  
T Cells ◽  
Human Lymphocyte ◽  
Peripheral Blood ◽  
Cytotoxic T Cells ◽  
Lymphocyte Subpopulations ◽  
Helper T Cells ◽  
Spectral Signature ◽  
Mid Infrared ◽  
Spectral Signatures ◽  
Infrared Spectral

Peripheral blood cytotoxic T cells (CD8+), helper T cells (CD4+) and regulatory T cells (T reg) have unique spectral signatures in the mid-infrared.

scholarly journals Spectral characteristics of spring arctic mesosphere dynamics

1998 ◽  
Vol 16 (12) ◽  
pp. 1607-1618 ◽  
Author(s):  
C. M. Hall ◽  
A. H. Manson ◽  
C. E. Meek
Keyword(s):  
Energy Dissipation ◽  
Middle Atmosphere ◽  
Spectral Characteristics ◽  
Turbulent Energy ◽  
Energy Dissipation Rate ◽  
Spectral Signature ◽  
Upper Limits ◽  
Waves And Tides ◽  
Signal Fading ◽  
Mf Radar

Abstract. The spring of 1997 has represented a stable period of operation for the joint University of Tromsø / University of Saskatchewan MF radar, being between refurbishment and upgrades. We examine the horizontal winds from the February to June inclusive and also include estimates of energy dissipation rates derived from signal fading times and presented as upper limits on the turbulent energy dissipation rate, ε. Here we address the periodicity in the dynamics of the upper mesosphere for time scales from hours to one month. Thus, we are able to examine the changes in the spectral signature of the mesospheric dynamics during the transition from winter to summer states.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; turbulence; waves and tides).

scholarly journals Mobile Application Development for Spectral Signature of Weed Species in Rice Farming

2021 ◽  
Vol 29 (4) ◽  
Author(s):  
Nor Athirah Roslin ◽  
Nik Norasma Che’Ya ◽  
Nursyazyla Sulaiman ◽  
Lutfi Amir Nor Alahyadi ◽  
Mohd Razi Ismail
Keyword(s):  
Mobile Application ◽  
Near Infrared ◽  
Spectral Signature ◽  
Weed Species ◽  
Application Development ◽  
Spectral Signatures ◽  
Weed Infestation ◽  
Access Information ◽  
Master Builder ◽  
And Control

Weed infestation happens when there is intense competition between rice and weeds for light, nutrients and water. These conditions need to be monitored and controlled to lower the growth of weeds as they affected crops production. The characteristics of weeds and rice are challenging to differentiate macroscopically. However, information can be acquired using a spectral signature graph. Hence, this study emphasises using the spectral signature of weed species and rice in a rice field. The study aims to generate a spectral signature graph of weeds in rice fields and develop a mobile application for the spectral signature of weeds. Six weeds were identified in Ladang Merdeka using Fieldspec HandHeld 2 Spectroradiometer. All the spectral signatures were stored in a spectral database using Apps Master Builder, viewed using smartphones. The results from the spectral signature graph show that the jungle rice (Echinochloa spp.) has the highest near-infrared (NIR) reflectance. In contrast, the saromacca grass (Ischaemum rugosum) shows the lowest NIR reflectance. Then, the first derivative (FD) analysis was run to visualise the separation of each species, and the 710 nm to 750 nm region shows the highest separation. It shows that the weed species can be identified using spectral signature by FD analysis with accurate separation. The mobile application was developed to provide information about the weeds and control methods to the users. Users can access information regarding weeds and take action based on the recommendations of the mobile application.

scholarly journals Solar occultation with SCIAMACHY: algorithm description and first validation

2005 ◽  
Vol 5 (1) ◽  
pp. 17-66 ◽  
Author(s):  
J. Meyer ◽  
A. Bracher ◽  
A. Rozanov ◽  
A. C. Schlesier ◽  
H. Bovensmann ◽  
...  
Keyword(s):  
Vertical Profile ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Trace Gas ◽  
Transmission Spectra ◽  
Atmospheric Transmission ◽  
Gas Concentration ◽  
Solar Occultation ◽  
First Results ◽  
The Vertical Distribution

Abstract. This presentation concentrates on solar occultation measurements with the spaceborne spectrometer SCIAMACHY in the UV-Vis wavelength range. Solar occultation measurements provide unique information about the vertical distribution of atmospheric constituents. For retrieval of vertical trace gas concentration profiles, an algorithm has been developed based on the optimal estimation method. The forward model is capable to simulate the extinction signals of different species as they occur in atmospheric transmission spectra obtained from occultation measurements. Furthermore, correction algorithms have been implemented to address shortcomings of the tangent height pre-processing and inhomogeneities of measured solar spectra. First results of O3 and NO2 vertical profile retrievals have been validated with data from ozone sondes and satellite based occultation instruments. The validation shows very promising results for SCIAMACHY O3 and NO2 values between 15 to 35 km with errors in the order of 10% and 15%, respectively.

scholarly journals Molecular cross-sections for high-resolution spectroscopy of super-Earths, warm Neptunes, and hot Jupiters

2020 ◽  
Vol 495 (1) ◽  
pp. 224-237 ◽  
Author(s):  
Siddharth Gandhi ◽  
Matteo Brogi ◽  
Sergei N Yurchenko ◽  
Jonathan Tennyson ◽  
Phillip A Coles ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Sections ◽  
Cross Correlation ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Pressure Broadening ◽  
Spectral Signatures ◽  
Hot Jupiters ◽  
Wide Range ◽  
Infrared Spectral

ABSTRACT High-resolution spectroscopy (HRS) has been used to detect a number of species in the atmospheres of hot Jupiters. Key to such detections is accurately and precisely modelled spectra for cross-correlation against the R ≳ 20 000 observations. There is a need for the latest generation of opacities which form the basis for high signal-to-noise detections using such spectra. In this study we present and make publicly available cross-sections for six molecular species, H2O, CO, HCN, CH4, NH3, and CO2 using the latest line lists most suitable for low- and high-resolution spectroscopy. We focus on the infrared (0.95–5 μm) and between 500 and 1500 K where these species have strong spectral signatures. We generate these cross-sections on a grid of pressures and temperatures typical for the photospheres of super-Earth, warm Neptunes, and hot Jupiters using the latest H2 and He pressure broadening. We highlight the most prominent infrared spectral features by modelling three representative exoplanets, GJ 1214 b, GJ 3470 b, and HD 189733 b, which encompass a wide range in temperature, mass, and radii. In addition, we verify the line lists for H2O, CO, and HCN with previous high-resolution observations of hot Jupiters. However, we are unable to detect CH4 with our new cross-sections from HRS observations of HD 102195 b. These high-accuracy opacities are critical for atmospheric detections with HRS and will be continually updated as new data become available.

scholarly journals New Asia Dust Storm Detection Method Based on the Thermal Infrared Spectral Signature

2014 ◽  
Vol 7 (1) ◽  
pp. 51-71 ◽  
Author(s):  
Hui Xu ◽  
Tianhai Cheng ◽  
Xingfa Gu ◽  
Tao Yu ◽  
Yu Wu ◽  
...  
Keyword(s):  
Dust Storm ◽  
Detection Method ◽  
Thermal Infrared ◽  
Spectral Signature ◽  
Infrared Spectral

Erratum: Upper Limits on Liquid Water in the Venus Atmosphere

1967 ◽  
Vol 150 ◽  
pp. L207 ◽  
Author(s):  
W. J. Welch ◽  
D. G. Rea
Keyword(s):  
Liquid Water ◽  
Upper Limits ◽  
Venus Atmosphere

scholarly journals Upper Limits for the Luminosity of a dM Companion in AM Herculis Objects

1980 ◽  
Vol 88 ◽  
pp. 471-472
Author(s):  
S. Tapia ◽  
G. V. Coyne
Keyword(s):  
Binary Systems ◽  
Near Infrared ◽  
Close Binary ◽  
Optical Identification ◽  
New Class ◽  
Upper Limits ◽  
Infrared Spectral ◽  
Cyclotron Emission ◽  
High Degree ◽  
The Magnetic Field

SummaryThe quest for optical identification of X-ray sources has revealed a new class of variables currently formed by AM Her, AN UMa, VV Pup, and the most recent member, 2A 0311-227 (for which a variable star designation will be available soon). These objects show many of the variations common to close binary systems where mass transfer is under way. However, they are distinguished by the high degree (10 to 35 %) of linear and circular polarization observed in the optical and near infrared spectral regions. Apparently the polarization is due to cyclotron emission of electrons located in a region where the magnetic field strength is about 108 gauss.

Synthesis of infrared spectral signatures

1990 ◽  
Vol 29 (3) ◽  
pp. 233
Author(s):  
Glenn D. Boreman ◽  
Kenneth J. Barnard
Keyword(s):  
Spectral Signatures ◽  
Infrared Spectral
Sign in / Sign up

Export Citation Format

Share Document