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- Brohede, Samuel, 1977, et al.
(författare)
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A stratospheric NO2 climatology from Odin/OSIRIS limb-scatter measurements
- 2007
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Ingår i: Canadian Journal of Physics. - 0008-4204 .- 1208-6045. ; 85:11, s. 1253-1274
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Tidskriftsartikel (refereegranskat)abstract
- A climatology of stratospheric nitrogen dioxide (NO2), in terms of mean and standard deviation, as a function of latitude (5° bins); altitude (10–46 km in 2 km bins); local solar time (24 h); and month is constructed based on the Odin/OSIRIS limb-scattering data from 2002–2005. The measured profiles, given at specific local solar times, are scaled to all 24 h using a photochemical box model. The Odin orbit gives near global coverage around the equinoxes and hemispheric coverage elsewhere, due to lack of sunlight. The mean NO2 field at a specific local solar time involves high concentrations in the polar summer, peaking at around 25 km, with a negative equatorward gradient. Distinct high levels between 40–50° latitude at 30 km in the winter/spring hemisphere are also found, associated with the so-called {Noxon-cliff}. The diurnal cycle reveals the lowest NO2 concentrations just after sunrise and steep gradients at twilight. The 1σ standard deviation is generally quite low, around 20%, except for winter and spring high latitudes, where values are well above 50% and stretch through the entire stratosphere, a phenomenon probably related to the polar vortex. It is also found that NO2 concentrations are log-normally distributed. Comparisons to a climatology based on data from a (REPROBUS) chemical transport model for the same time period reveal relative differences below 20% in general, which is comparable to the estimated OSIRIS systematic uncertainty. Clear exceptions are the polar regions in winter/spring throughout the atmosphere and equatorial regions below 25 km, where OSIRIS is relatively higher by 40% and more. These discrepancies are most likely attributable to limitations of the model, but this has to be investigated further.
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| 4. |
- Brohede, Samuel, 1977, et al.
(författare)
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Internal consistency in the Odin stratospheric ozone products
- 2007
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Ingår i: Canadian Journal of Physics. - 0008-4204 .- 1208-6045. ; 85:11, s. 1275-1285
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Tidskriftsartikel (refereegranskat)abstract
- The two independent instruments on the Odin satellite, the Optical Spectrograph and Infrared Imaging System (OSIRIS) and the Sub-Millimetre Radiometer (SMR) produce atmospheric profiles of various atmospheric species including stratospheric ozone. Comparisons are made between OSIRIS version 3.0 and SMR version 2.1 ozone data to evaluate the consistency of the Odin ozone data sets. Results show good agreement between OSIRIS and SMR in the range 25–40 km, where systematic differences are less than 15% for all latitudes and seasons. Larger systematic differences are seen below 25 km, which can be explained by the increase of various error sources and lower signals. The random differences are between 20–30% in the middle stratosphere. Differences between Odin up-scans and down-scans or AM and PM are insignificant in the middle stratosphere. Furthermore, there is little variation from year to year, but a slight positive trend in the differences (OSIRIS minus SMR) of 0.045 ppmv/year at 30 km over validation period (2002–2006). The fact that the two fundamentally different measurement techniques, (absorption spectroscopy of scattering sunlight and emission measurements in the sub-millimetre region) agree so well, provides confidence in the robustness of both techniques.
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- Clementson, J., et al.
(författare)
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Tungsten spectroscopy at the Livermore electron beam ion trap facility
- 2011
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Ingår i: Canadian Journal of Physics. - 0008-4204. ; 89:5, s. 571-580
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Forskningsöversikt (refereegranskat)abstract
- The utilization of tungsten spectroscopy for diagnostics of magnetically confined fusion plasmas requires the radiative properties of tungsten ions to be accurately known. At the Lawrence Livermore National Laboratory, a program to gather spectroscopic data on tungsten ions has been initiated with the purpose to study spectral signatures and identify candidate fusion plasma diagnostics. In this paper, an overview of recent results from the Livermore WOLFRAM spectroscopy project is presented, which includes experimental investigations at the EBIT-I and SuperEBIT electron beam ion traps. In particular, the spectra of highly charged M-and L-shell tungsten ions have been studied. These investigations cover energy measurements of n = 2 to n = 2, 3 transitions in Ne-like W64+ through Li-like W71+ ions and soft X-ray measurements of n = 3 to n = 3, 4 transitions in M-shell ions with emphasis on the Ni-like W46+ and Si-like W60+ through Na-like W63+ ions. The measurements are complemented by atomic-structure calculations and spectral modeling using the Flexible Atomic Code (FAC).
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- FRANCIS, JT, et al.
(författare)
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STUDIES OF C 1S-]PI-ASTERISK TRIPLET-STATES OF CARBON-MONOXIDE, BENZENE, ETHYLENE, AND ACETYLENE
- 1994
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Ingår i: CANADIAN JOURNAL OF PHYSICS. - 0008-4204. ; 72:11-12, s. 879-884
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The (C 1s(-1),pi*) triplet states of carbon monoxide, benzene, ethylene, and acetylene have been studied using electron energy loss spectroscopy with low-energy (near-threshold) excitation. The singlet-triplet splitting for the (C 1s(-1), pi*) states of t
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| 7. |
- Gattinger, R. L., et al.
(författare)
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Vibrational populations of near-ultraviolet O-2 band systems in the night airglow
- 2012
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Ingår i: Canadian journal of physics (Print). - : Canadian Science Publishing. - 0008-4204 .- 1208-6045. ; 90:8, s. 741-751
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Tidskriftsartikel (refereegranskat)abstract
- Observations of the limb night airglow spectrum from 250 to 475 nm, emitted from the upper mesosphere and lower thermosphere, are compared with model spectra. Data from the Arizona GLO-1 imaging spectrograph and the OSIRIS spectrograph are combined to form the observed mean airglow spectrum; a tabulated version of this spectrum is included. Model spectra of the individual O-2 Herzberg I, II, and III, Chamberlain, and Slanger band systems are combined to simulate the observed mean spectrum. Franck-Condon relative band intensities are used to form a series of basis functions for the upper vibrational levels in each band system. These functions are fitted to the observed airglow spectrum with a least-squares method, the relative vibrational populations are derived and discussed.
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- Grevesse, N., et al.
(författare)
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The chemical composition of the sun
- 2011
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Ingår i: Canadian journal of physics (Print). - 0008-4204 .- 1208-6045. ; 89:4, s. 327-331
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Forskningsöversikt (refereegranskat)abstract
- We have very recently re-determined the abundances of nearly all the available chemical elements in the solar photosphere, from lithium to thorium (Asplund et al. Annu. Rev. Astron. Astrophys. 47, 481 (2009)). This new complete and homogeneous analysis results from a very careful selection of spectral lines of all the indicators of the abundances present in the solar photospheric spectrum, from a discussion of the atomic and molecular data, and from an analysis of these lines based on a new 3D model of the solar outer layers, taking non-LTE effects into account when possible. We present these new results, compare them with other recent solar data as well as with recent results for the solar neighborhood, and discuss some of their most important implications as well as some of the atomic data we still urgently need.
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| 9. |
- Haley, C. S., et al.
(författare)
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Status of the Odin/OSIRIS stratospheric O3 and NO2 data products
- 2007
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Ingår i: Canadian Journal of Physics. - 0008-4204 .- 1208-6045. ; 85:11, s. 1177-1194
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the status of the stratospheric ozone and nitrogen dioxide data products from the Optical Spectrograph and InfraRed Imager System (OSIRIS) instrument on the Odin satellite. The current version of the data products is 3.0, covering the period from November 2001 to the present. The O3 and NO2 retrieval methods are reviewed along with an overview of the error analyses and geophysical validation status.
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| 10. |
- Hansson, Johan
(författare)
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A simple explanation of the nonappearance of physical gluons and quarks
- 2002
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Ingår i: Canadian journal of physics (Print). - : Canadian Science Publishing. - 0008-4204 .- 1208-6045. ; 80:9, s. 1093-1097
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Tidskriftsartikel (refereegranskat)abstract
- We show that the nonappearance of gluons and quarks as physical particles is a rigorous and automatic result of the full, i.e., nonperturbative, nonabelian nature of the color interaction in quantum chromodynamics (QCD). This makes it, in general, impossible to describe the color field as a collection of elementary quanta (gluons). Neither can a quark be an elementary quantum of the quark field, as the color field of which it is the source is itself a source, making isolated noninteracting quarks, crucial for a physical particle interpretation, impossible. In geometrical language, the impossibility of quarks and gluons as physical elementary particles arises due to the fact that the color Yang-Mills space does not have a constant trivial curvature. In QCD, the particles "gluons" and "quarks" are merely artifacts of an approximation method (the perturbative expansion) and are simply absent in the exact theory. This also coincides with the empirical, experimental evidence
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