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Title |
Impact of 3-D Earth structure on W-phase CMT parameters |
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Journal |
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Year |
2020 |
Publication |
Geophysical Journal International |
Abbreviated Journal |
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Volume |
223 |
Issue |
2 |
Pages |
1432-1445 |
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133 |
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ISSN |
0956-540X |
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yes |
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Call Number |
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Serial |
7890 |
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Author |
Merieme Chadid, Chris Sneden and George Preston |
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Title |
Spectroscopic Comparison of Metal–Rich RRab Stars of theGalactic Field with Their Metal–Poor Counterparts |
Type |
Journal Article |
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Year |
2016 |
Publication |
Astrophysical journal |
Abbreviated Journal |
Astrophys. J. |
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Volume |
835 |
Issue |
2 |
Pages |
187 |
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Abstract |
We investigate atmospheric properties of 35 stable RRab stars that possess the full ranges of period, light amplitude, and metal abundance found in Galactic RR Lyrae stars. Our results are derived from several thousand echelle spectra obtained over several years with the du Pont telescope of Las Campanas Observatory. Radial velocities of metal lines and the Hα line were used to construct curves of radial velocity versus pulsation phase. From these we estimated radial velocity amplitudes for metal lines (formed near the photosphere) and Hα Doppler cores (formed at small optical depths). We also measured Hα emission fluxes when they appear during primary light rises. Spectra shifted to rest wavelengths, binned into small phase intervals, and co-added were used to perform model atmospheric and abundance analyses. The derived metallicities and those of some previous spectroscopic surveys were combined to produce a new calibration of the Layden abundance scale. We then divided our RRab sample into metal-rich (disk) and metal-poor (halo) groups at [Fe/H] = −1.0; the atmospheres of RRab families, so defined, differ with respect to (a) peak strength of Hα emission flux, (b) Hα radial velocity amplitude, (c) dynamical gravity, (d) stellar radius variation, (e) secondary acceleration during the photometric bump that precedes minimum light, and (f) duration of Hα line-doubling. We also detected Hα line-doubling during the |
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Programme |
1096 |
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Bachelor's thesis |
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0004-637X |
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yes |
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Call Number |
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Serial |
6544 |
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Author |
Michael Lockwood, Mathew J. Owens, Carl Haines, Luke Barnard, Christopher John Scott, Aude Chambodut, Kathryn A. McWilliams, Alan W. P. Thomson |
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Title |
Universal Time Variations in Space Weather |
Type |
Journal |
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Year |
2020 |
Publication |
Earth and space science open archive |
Abbreviated Journal |
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Volume |
12 |
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139 |
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Approved |
yes |
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Call Number |
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Serial |
8464 |
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Title |
High Angular Resolution Measurements of the Anisotropy of Reflectance of Sea Ice and Snow |
Type |
Journal |
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Year |
2018 |
Publication |
Earth and Space Science |
Abbreviated Journal |
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Volume |
5 |
Issue |
1 |
Pages |
30-47 |
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Keywords |
Arctic bidirectional reflectance reflectance anisotropy remote sensing snow and ice albedo spectroradiometry |
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Abstract |
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Programme |
1164 |
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ISSN |
2333-5084 |
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Approved |
yes |
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Call Number |
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Serial |
8134 |
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Title |
New modeling of the Vostok ice flow line and implication for the glaciological chronology of the Vostok ice core |
Type |
Journal Article |
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Year |
2004 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
109 |
Issue |
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Pages |
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Keywords |
glaciology; paleoclimatology; Antarctica; inverse theory; 1827 Hydrology: Glaciology; 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 3260 Mathematical Geophysics: Inverse theory; 9310 Information Related to Geographic Region: Antarctica |
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Abstract |
We have used new spaceborne (elevation) and airborne (ice thickness) data to constrain a 2D1/2 model of snow accumulation and ice flow along the Ridge B-Vostok station ice flow line (East Antarctica). We show that new evaluations of the ice flow line geometry (from the surface elevation), ice thickness (from low-frequency radar data), and basal melting and sliding change significantly the chronology of the Vostok ice core. This new Vostok dating model reconciles orbital and glaciological timescales and is in good agreement with the Dome Fuji glaciological timescale. At the same time, the new model shows significantly older ages than the previous GT4 timescale for the last glacial part, being thus in better agreement with the GRIP and GISP2 chronologies. |
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Programme |
355 |
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Publisher |
American Geophysical Union |
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Edition |
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ISSN |
0148-0227 |
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Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5618 |
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Author |
Bulat S., Alekhina I A Blot M., Petit J.R., De Angelis M., Wagenbach D. Lipenkov V.Y., |
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Title |
DNA signature of thermophilic bacteria from the aged accretion ice of Lake Vostok, Antarctica: implications for searching for life in extreme icy environments |
Type |
Journal Article |
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Year |
2004 |
Publication |
International journal of astrobiology |
Abbreviated Journal |
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Volume |
3 |
Issue |
1 |
Pages |
1-12 |
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Abstract |
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Programme |
355 |
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Approved |
yes |
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Call Number |
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Serial |
2604 |
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Author |
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Title |
Modeling the lithospheric magnetic field over France by means of revised spherical cap harmonic analysis (R-SCHA) |
Type |
Journal Article |
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Year |
2006 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
111 |
Issue |
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Pages |
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Keywords |
regional modeling; France; magnetic field; 1517 Geomagnetism and Paleomagnetism: Magnetic anomalies: modeling and interpretation; 1545 Geomagnetism and Paleomagnetism: Spatial variations: all harmonics and anomalies; 0545 Computational Geophysics: Modeling |
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Abstract |
We have recently proposed the revised spherical cap harmonic analysis (R-SCHA) modeling technique. The new mathematical functions represent faithfully the spatial variations of potential fields in a restricted area. In this paper, we tackle the inverse problem and outline the efficiency of the new basis functions with respect to real magnetic data. Processing simultaneously repeat stations, observatory, aeromagnetic, and CHAMP satellite data provides our first vector lithospheric field model over France, which extends from surface to 500 km of altitude. The magnetic field is represented with a minimum horizontal spatial representation of 40 km at the mean Earth radius. The magnetic lithospheric map consistency is confirmed with a comparison to known geological features. The model variation with altitude also suggests that the major French magnetic anomaly, the Paris basin anomaly, is produced by a deep-rooted geological structure. These results demonstrate the superiority of regional modeling over global modeling for delineating small-scale details in the lithospheric field. In view of forthcoming satellite missions, like Swarm, the revised spherical cap harmonic analysis method will help to accurately represent the lithospheric field for more detailed geological interpretations. |
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Programme |
905;139 |
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Publisher |
American Geophysical Union |
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ISSN |
0148-0227 |
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Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5617 |
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Author |
W. Lyatsky, G. V. Khanazov, S. Lyatskaya, D. Di Mauro, S. Lepidi, L. Cafarella, A. Chambodut, J.-J. Schott |
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Title |
Polar magnetic indices : a new key to correlate magnetic variations in the Earth's hemisphere |
Type |
Conference - International - Poster |
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Year |
2009 |
Publication |
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Abbreviated Journal |
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Volume |
IAGA 11th Scientific Assembly, 23-30 August 2009 |
Issue |
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Pages |
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Abstract |
We have presented here the results of a statistical study of two polar magnetic indices, computed from data from two near-pole geomagnetic observatories: Thule in the northern hemisphere and new, Concordia (Dome C) observatory near the southern geomagnetic pole in Antarctica. We found that:
The northern PMn and southern PMs polar magnetic indices show a good correlation with the solar wind/IMF parameters (the average correlation coefficient is ~ 0.87). Meanwhile, the southern PMs index shows a significantly better correlation than the northern PMn index, which demonstrates that the new Concordia observatory may play an important role in improving the Space Weather prediction.
The obtained results also show a high correlation between these two polar magnetic indices: the average correlation coefficient for this period was ~0.9 while for equinoctial months it increased up to 0.94-0.96.
Using the polar magnetic indices in two hemispheres may also significantly improve the prediction of other parameters, including the auroral electrojet AL index which shows substorm activity. Using the polar magnetic indices in two hemispheres allows us to predict the auroral electrojet AL index with a very high reliability (the correlation coefficient between predicted and actual AL indices is ~0.9, while for the equinoctial months the correlation coefficient was ~0.92).
The results of this study show an important role which is played by the magnetic disturbances in both polar ionospheres in developing the global magnetic activity, and the necessity to account for the magnetic disturbances in both ionospheres for improving the Space Weather prediction in the Geospace environment. |
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Programme |
905 |
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yes |
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Call Number |
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Serial |
5745 |
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Author |
W. Lyatsky, G. V. Khanazov, S. Lyatskaya, D. Di Mauro, S. Lepidi, L. Cafarella, A. Chambodut, J.-J. Schott |
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Title |
Polar magnetic indices : a new key to correlate magnetic variations in the Earth's hemisphere |
Type |
Conference - International - Poster |
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Year |
2009 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
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Keywords |
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Abstract |
We have presented here the results of a statistical study of two polar magnetic indices, computed from data from two near-pole geomagnetic observatories: Thule in the northern hemisphere and new, Concordia (Dome C) observatory near the southern geomagnetic pole in Antarctica. We found that:
The northern PMn and southern PMs polar magnetic indices show a good correlation with the solar wind/IMF parameters (the average correlation coefficient is ~ 0.87). Meanwhile, the southern PMs index shows a significantly better correlation than the northern PMn index, which demonstrates that the new Concordia observatory may play an important role in improving the Space Weather prediction.
The obtained results also show a high correlation between these two polar magnetic indices: the average correlation coefficient for this period was ~0.9 while for equinoctial months it increased up to 0.94-0.96.
Using the polar magnetic indices in two hemispheres may also significantly improve the prediction of other parameters, including the auroral electrojet AL index which shows substorm activity. Using the polar magnetic indices in two hemispheres allows us to predict the auroral electrojet AL index with a very high reliability (the correlation coefficient between predicted and actual AL indices is ~0.9, while for the equinoctial months the correlation coefficient was ~0.92).
The results of this study show an important role which is played by the magnetic disturbances in both polar ionospheres in developing the global magnetic activity, and the necessity to account for the magnetic disturbances in both ionospheres for improving the Space Weather prediction in the Geospace environment. |
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Programme |
139 |
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yes |
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Call Number |
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Serial |
5861 |
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Author |
Butler Rhett, Tsuboi Seiji, |
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Title |
Antipodal seismic observations of temporal and global variation at Earth's inner-outer core boundary
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Type |
Journal Article |
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Year |
2010 |
Publication |
Geophysical Research Letters |
Abbreviated Journal |
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Volume |
37 |
Issue |
11 |
Pages |
L11301- |
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Keywords |
antipode, Earth, core, 7207 Core, 7203 Body waves, 8115 Core processes, |
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Abstract |
We have found two pairs of earthquake doublets closely located antipodally on one diametral axis between Tonga-Algeria, and several other events on other axes. These doublets show significant correlation, and exhibit seismic phases traversing the Core that cannot be explained by a standard radial Earth model such as PREM. The antipodal waveform data are highly variable between axes. The observed variability of the waveforms indicates global variations in the structure above and below the Inner-Outer Core boundary region. We have found evidence for a regional low-velocity zone at the base of the Outer Core, corresponding with a decadal temporal variation (0.55 s) in seismic energy traversing the top of the Inner Core. We propose an antipodal seismic array to constrain and to provide further progress for the study of the Inner and Outer Core.
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133 |
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ISSN |
1944-8007 |
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yes |
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Call Number |
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Serial |
448 |
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| Permanent link to this record |
