scholarly journals Solar 5-minute Oscillations at 2.23 μm

1994 ◽  
Vol 154 ◽  
pp. 271-276
Author(s):  
Torben Leifsen
Keyword(s):  
Time Series ◽  
Fourier Transform ◽  
Near Infrared ◽  
Broad Band ◽  
Solar Observatory ◽  
Fourier Transform Spectrometer ◽  
Large Intensity ◽  
National Solar Observatory ◽  
Long Run ◽  
The Fourier Transform

Large amplitude solar 5-min intensity oscillations have recently been detected at 2.23 μm using broad band (650 Å FWHM) photometry (Leifsen and Maltby, 1990). Large intensity amplitudes in a broad range in the near infrared was unexpected, and several questions concerning the source of the high amplitudes were raised. In an attempt to study the nature of these oscillations, time series of spectra have been obtained with the Fourier Transform Spectrometer (FTS) of the McMath telescope at National Solar Observatory at Kitt Peak. We present preliminary results from a 10 day long run in May 1991 in support for the suggestion that the results may be useful in both helio- and asteroseismological investigations.

The infrared spectrum of CS

1984 ◽  
Vol 62 (12) ◽  
pp. 1414-1419 ◽  
Author(s):  
R. J. Winkel Jr. ◽  
Sumner P. Davis ◽  
Rubén Pecyner ◽  
James W. Brault
Keyword(s):  
Fourier Transform ◽  
Infrared Emission ◽  
Solar Observatory ◽  
Band Head ◽  
The Other ◽  
Fourier Transform Spectrometer ◽  
National Solar Observatory ◽  
Carbon Monosulfide ◽  
Vibration Rotation ◽  
The Fourier Transform

The infrared emission spectrum of carbon monosulfide was observed as a sequence of vibration–rotation bands in the X1Σ+ state, with strong heads of the Δν = 2 sequence degraded to the red. Eight bands of 12C32S were identified, and bands corresponding to the isotope 12C34S were also observed. The most prominent band head, that of the (2–0) band, is at 2585 cm−1, with the other heads spaced approximately 26 cm−1 to smaller wavenumbers. Our data, taken with the Fourier transform spectrometer at the National Solar Observatory (Kitt Peak) include the first reported laboratory observations of the band heads and as many as 200 lines in each band. These observations allowed the calculation of vibrational and rotational constants to higher order than previously reported.

Lambda doubling in the infrared spectrum of SH

1984 ◽  
Vol 62 (12) ◽  
pp. 1420-1425 ◽  
Author(s):  
R. J. Winkel Jr. ◽  
Sumner P. Davis
Keyword(s):  
Fourier Transform ◽  
Infrared Spectrum ◽  
Ground State ◽  
Solar Observatory ◽  
Fourier Transform Spectrometer ◽  
Multiplet Splitting ◽  
National Solar Observatory ◽  
Vibration Rotation ◽  
The Fourier Transform ◽  
First Time

The (1–0), (2–1), and (3–2) infrared vibration–rotation bands of the X2Π ground state of sulfur monohydride were observed in emission from a furnace. Multiplet splitting produces two subbands, each of which exhibits lambda splitting. The band heads were observed for the first time, 285 lines were measured, and a calculation of lambda-doubling parameters was made. The spectrum was recorded using the Fourier transform spectrometer at the National Solar Observatory (Kitt Peak).

scholarly journals Solar observation with the Fourier transform spectrometer I : Preliminary results of the visible and near-infrared solar spectrum

2021 ◽  
Vol 21 (10) ◽  
pp. 267
Author(s):  
Xian-Yong Bai ◽  
Zhi-Yong Zhang ◽  
Zhi-Wei Feng ◽  
Yuan-Yong Deng ◽  
Xing-Ming Bao ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Spectral Resolution ◽  
Near Infrared ◽  
Solar Spectrum ◽  
High Spectral Resolution ◽  
Inversion Method ◽  
Fourier Transform Spectrometer ◽  
Solar Observation ◽  
The Fourier Transform ◽  
Sun Light

Abstract The Fourier transform spectrometer (FTS) is a core instrument for solar observation with high spectral resolution, especially in the infrared. The Infrared System for the Accurate Measurement of Solar Magnetic Field (AIMS), working at 10–13 μm, will use an FTS to observe the solar spectrum. The Bruker IFS-125HR, which meets the spectral resolution requirement of AIMS but simply equips with a point source detector, is employed to carry out preliminary experiment for AIMS. A sun-light feeding experimental system is further developed. Several experiments are taken with them during 2018 and 2019 to observe the solar spectrum in the visible and near infrared wavelength, respectively. We also proposed an inversion method to retrieve the solar spectrum from the observed interferogram and compared it with the standard solar spectrum atlas. Although there is a wavelength limitation due to the present sun-light feeding system, the results in the wavelength band from 0.45–1.0 μm and 1.0–2.2 μm show a good consistency with the solar spectrum atlas, indicating the validity of our observing configuration, the data analysis method and the potential to work in longer wavelength. The work provided valuable experience for the AIMS not only for the operation of an FTS but also for the development of its scientific data processing software.

Identification of Natural Bamboo Fibers and Flax Fibers

2013 ◽  
Vol 821-822 ◽  
pp. 153-157 ◽  
Author(s):  
Wei Dong Li ◽  
Xin Hou Wang ◽  
Li Hua Peng
Keyword(s):  
Cluster Analysis ◽  
Fourier Transform ◽  
Near Infrared ◽  
Hierarchical Cluster ◽  
High Accuracy ◽  
Flax Fibers ◽  
First Derivative ◽  
Near Infrared Spectra ◽  
Bamboo Fibers ◽  
The Fourier Transform

In this paper, the method based on the testing of the Fourier transform near infrared (NIR) spectra is proposed to identify natural bamboo fibers and flax fibers. The discrimination models between natural bamboo fibers and flax fibers are established by means of Ward’s algorithm and Hierarchical Cluster Analysis after the first derivative and vector normalization pretreatment. The verification results indicated that these two kinds of fibers could be classified into two separated groups for the identification and the near infrared spectra model is high accuracy.

Testing for nonlinearity in time series without the Fourier transform

2005 ◽  
Vol 72 (5) ◽  
Author(s):  
Tomomichi Nakamura ◽  
Xiaodong Luo ◽  
Michael Small
Keyword(s):  
Time Series ◽  
Fourier Transform ◽  
The Fourier Transform

Balloon-borne GLORIA hyperspectral Limb and Nadir imager in the LWIR

2021 ◽  
Author(s):  
Erik Kretschmer ◽  
Felix Friedl-Vallon ◽  
Thomas Gulde ◽  
Michael Höpfner ◽  
Sören Johansson ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Optical System ◽  
Late Summer ◽  
High Spectral Resolution ◽  
Fourier Transform Spectrometer ◽  
System Improvement ◽  
The Fourier Transform ◽  
Temperature Retrieval ◽  
Long Wave Infrared ◽  
Better Than

<p>The GLORIA-B (Gimballed Limb Observer for Radiance Imaging of the Atmosphere - Balloon) instrument is an adaptation of the very successful GLORIA-AB imaging Fourier transform spectrometer (iFTS) flown on the research aircrafts HALO and M55 Geophysica. The high spectral resolution in the LWIR (Long Wave Infrared) allows for the retrieval of temperature and of a broad range of atmospheric trace gases, with the goal to retrieve O<sub>3</sub>, H<sub>2</sub>O, HNO<sub>3</sub>, C<sub>2</sub>H<sub>6</sub>, C<sub>2</sub>H<sub>2</sub>, HCOOH, CCl<sub>4</sub>, PAN, ClONO<sub>2</sub>, CFC-11, CFC-12, SF<sub>6</sub>, OCS, NH<sub>3</sub>, HCN, BrONO<sub>2</sub>, HO<sub>2</sub>NO<sub>2</sub>, N<sub>2</sub>O<sub>5</sub> and NO<sub>2</sub>. The radiometric sensitivity of the Balloon instrument is further increased in comparison with the GLORIA-AB instrument by having two detector channels on the same focal plane array, while keeping the same concept of a cooled optical system. This system improvement was achieved with minimal adaptation of the existing optical system.</p><p>The high spatial and temporal resolution of the instrument is ensured by the imaging capability of the Fourier transform spectrometer while stabilizing the line-of-sight in elevation with the instrument and in azimuth with the balloon gondola. In a single measurement lasting 13 seconds, the atmosphere can be sounded from mid-troposphere up to flight altitude, typically 30 km, with a vertical resolution always better than 1 km for most retrieved species; a spatial resolution up to 0.3 km can be achieved in favourable conditions. Temperature retrieval precision between 0.1 and 0.2 K is expected. A spectral sampling up to 0.0625 cm<sup>-1</sup> can be achieved.</p><p>The first flight of GLORIA-B shall take place during the late-summer polar jet turn-around at Kiruna/ESRANGE. This flight is organised in the frame of the HEMERA project and was scheduled for summer 2020, but was ultimately postponed to summer 2021. Beyond qualification of the first balloon-borne iFTS, the scientific goals of the flight are, among others, the quantification of the stratospheric bromine budget and its diurnal evolution by measuring vertical profiles of BrONO<sub>2 </sub>in combination with BrO observations by the DOAS instrument of University Heidelberg on the same platform.</p>

Near-infrared broadband cavity-enhanced sensor system for methane detection using a wavelet-denoising assisted Fourier-transform spectrometer

The Analyst ◽  
2018 ◽  
Vol 143 (19) ◽  
pp. 4699-4706 ◽  
Author(s):  
Kaiyuan Zheng ◽  
Chuantao Zheng ◽  
Zidi Liu ◽  
Qixin He ◽  
Qiaoling Du ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Spectral Range ◽  
Near Infrared ◽  
Wavelet Denoising ◽  
Visible Spectral Range ◽  
Sensor System ◽  
Trace Gas ◽  
Fourier Transform Spectrometer ◽  
Methane Detection

The majority of broadband cavity-enhanced systems are used to detect trace gas species in the visible spectral range.

scholarly journals Retrieval of atmospheric CH<sub>4</sub> vertical information from ground-based FTS near-infrared spectra

2019 ◽  
Vol 12 (11) ◽  
pp. 6125-6141 ◽  
Author(s):  
Minqiang Zhou ◽  
Bavo Langerock ◽  
Mahesh Kumar Sha ◽  
Nicolas Kumps ◽  
Christian Hermans ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Mole Fraction ◽  
Atmospheric Chemistry ◽  
Near Infrared ◽  
Satellite Observations ◽  
Total Carbon ◽  
Fourier Transform Spectrometer ◽  
Aircraft Measurements ◽  
Retrieval Software ◽  
Total Column

Abstract. The Total Carbon Column Observing Network (TCCON) column-averaged dry air mole fraction of CH4 (XCH4) measurements have been widely used to validate satellite observations and to estimate model simulations. The GGG2014 code is the standard TCCON retrieval software used in performing a profile scaling retrieval. In order to obtain several vertical pieces of information in addition to the total column, in this study, the SFIT4 retrieval code is applied to retrieve the CH4 mole fraction vertical profile from the Fourier transform spectrometer (FTS) spectrum at six sites (Ny-Ålesund, Sodankylä, Bialystok, Bremen, Orléans and St Denis) during the time period of 2016–2017. The retrieval strategy of the CH4 profile retrieval from ground-based FTS near-infrared (NIR) spectra using the SFIT4 code (SFIT4NIR) is investigated. The degree of freedom for signal (DOFS) of the SFIT4NIR retrieval is about 2.4, with two distinct pieces of information in the troposphere and in the stratosphere. The averaging kernel and error budget of the SFIT4NIR retrieval are presented. The data accuracy and precision of the SFIT4NIR retrievals, including the total column and two partial columns (in the troposphere and stratosphere), are estimated by TCCON standard retrievals, ground-based in situ measurements, Atmospheric Chemistry Experiment – Fourier Transform Spectrometer (ACE-FTS) satellite observations, TCCON proxy data and AirCore and aircraft measurements. By comparison against TCCON standard retrievals, it is found that the retrieval uncertainty of SFIT4NIR XCH4 is similar to that of TCCON standard retrievals with systematic uncertainty within 0.35 % and random uncertainty of about 0.5 %. The tropospheric and stratospheric XCH4 from SFIT4NIR retrievals are assessed by comparison with AirCore and aircraft measurements, and there is a 1.0 ± 0.3 % overestimation in the SFIT4NIR tropospheric XCH4 and a 4.0 ± 2.0 % underestimation in the SFIT4NIR stratospheric XCH4, which are within the systematic uncertainties of SFIT4NIR-retrieved partial columns in the troposphere and stratosphere respectively.

scholarly journals A high-resolution near-infrared extraterrestrial solar spectrum derived from ground-based Fourier transform spectrometer measurements

2013 ◽  
Vol 118 (11) ◽  
pp. 5319-5331 ◽  
Author(s):  
Kaah P. Menang ◽  
Marc D. Coleman ◽  
Tom D. Gardiner ◽  
Igor V. Ptashnik ◽  
Keith P. Shine
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Near Infrared ◽  
Solar Spectrum ◽  
Fourier Transform Spectrometer ◽  
Extraterrestrial Solar Spectrum
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