| Records |
| Author |
Houser C, Masters G, Shearer P, Laske G, |
| Title |
Shear and compressional velocity models of the mantle from cluster analysis of long-period waveforms
|
Type |
Journal Article |
| Year |
2008 |
Publication |
Geophysical Journal International |
Abbreviated Journal |
|
| Volume |
174 |
Issue |
1 |
Pages |
195-212 |
Keywords  |
Mantle processes, Body waves, Seismic tomography, |
| Abstract |
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| Programme |
133 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
Blackwell Publishing Ltd |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
1365-246X |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
2812 |
| Permanent link to this record |
| |
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| |
| Author |
Mohiuddin Anwar, Long Maureen D, Lynner Colton, |
| Title |
Mid-mantle seismic anisotropy beneath southwestern Pacific subduction systems and implications for mid-mantle deformation
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Type |
Journal Article |
| Year |
2015 |
Publication |
Physics of the Earth and Planetary Interiors |
Abbreviated Journal |
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| Volume |
245 |
Issue |
|
Pages |
1-14 |
| Keywords |
Mantle deformation, Mid-mantle, Seismic anisotropy, Shear wave splitting, Subduction zones, |
| Abstract |
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| Programme |
133 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0031-9201 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
6152 |
| Permanent link to this record |
| |
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| |
| Author |
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| Title |
Revised spherical cap harmonic analysis (R-SCHA): Validation and properties |
Type |
Journal Article |
| Year |
2006 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
111 |
Issue |
|
Pages |
|
| Keywords |
magnetism; regional modeling; Spherical Cap Harmonic Analysis; 1214 Geodesy and Gravity: Geopotential theory and determination; 1517 Geomagnetism and Paleomagnetism: Magnetic anomalies: modeling and interpretation; 1532 Geomagnetism and Paleomagnetism: Reference fields: regional, global; 1541 Geomagnetism and Paleomagnetism: Satellite magnetics: main field, crustal field, external field; 1545 Geomagnetism and Paleomagnetism: Spatial variations: all harmonics and anomalies |
| Abstract |
We recently proposed a technique able to represent the spatial variations of the magnetic field at regional scales. However, we pointed out that these preliminary developments were not suited for the complete representation of the geomagnetic field. In this paper, we propose a complete revision, the revised spherical cap harmonic analysis (R-SCHA), which introduces slight changes in order to rectify the previous shortcomings. In addition, some discussions shed a new light on the former spherical cap harmonic analysis (SCHA) and help us to demonstrate its deficiencies and approximations. We finally show that R-SCHA now fully satisfies the natural properties of potential fields. R-SCHA also yields analytical relationships with the spherical harmonics. Taking advantage of the mathematical equivalence of both representations, we explore the relevance of fundamental concepts like spectrum, minimum wavelength, or internal/external field separation. We conclude that these concepts are misleading and must be handled with care in regional modeling. A prime goal being the ability of R-SCHA to represent real data sets, we also investigate and illustrate the effect of finite series expansions. A norm for the regularization of the inverse problem is proposed as well. The conclusions drawn in this paper allow us to validate the method and to assert that the present proposal is suited for modeling and studying the lithospheric magnetic field from ground to satellite altitudes at regional scales. |
| Programme |
139;905 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0148-0227 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5626 |
| Permanent link to this record |
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| Author |
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| Title |
International Geomagnetic Reference Field: the eleventh generation
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Type |
Journal Article |
| Year |
2010 |
Publication |
Geophysical Journal International |
Abbreviated Journal |
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| Volume |
183 |
Issue |
3 |
Pages |
1216 -1230 |
| Keywords |
Magnetic field, Satellite magnetics, |
| Abstract |
SUMMARY The eleventh generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2009 by the International Association of Geomagnetism and Aeronomy Working Group V-MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field model for epoch 2010.0, and a linear predictive secular variation model for 2010.02015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity for epoch 2010.0 and their predicted rates of change for 2010.02015.0 are presented. The recent evolution of the South Atlantic Anomaly and magnetic pole positions are also examined.
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| Programme |
139;905 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
Bachelor's thesis |
| Publisher |
Blackwell Publishing Ltd |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
1365-246X |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
2683 |
| Permanent link to this record |
| |
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| |
| Author |
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| Title |
A new proposal for spherical cap harmonic modelling. |
Type |
Journal Article |
| Year |
2004 |
Publication |
Geophysical journal international |
Abbreviated Journal |
|
| Volume |
159 |
Issue |
2 |
Pages |
83-103 |
| Keywords |
magnetic field, regional modelling, spherical cap harmonic analysis |
| Abstract |
The geomagnetic field above the surface of the Earth in the current-free region may be expressed as the gradient of a scalar potential solving Laplace's equation. For regions with a fairly dense coverage of data at different altitudes, a regional model ought to offer a better spatial resolution of the regional field over the volume under study than a global field expanded in spherical harmonics (SH). The spherical cap harmonics analysis (SCHA) is an attractive regional modelling tool having close relationship with global SH. With the SCHA adopted so far, difficulties arise in upward continuation and in establishing a relationship between global and local Gauss coefficients. Such a relationship would be useful, for instance, for introducing prior constraint on an inverse problem dealing with the estimation of local Gauss coefficients based upon a local data set. In this paper, we show that these difficulties are overcome if the SCHA modelling is formulated as a boundary value (BV) problem in a cone bounded radially by the surface of the Earth and an upper surface suitable for satellite data, and bounded laterally in order to encompass a specific region of study. Although the example worked out here applies only to a limited class of fields, which verifies some special flux condition, the ideas behind this formalism are quite general and should offer a new way of processing data in a bounded region of space. |
| Programme |
139;905 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0956-540X |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
4706 |
| Permanent link to this record |
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| Author |
V. Haberle, A. Marchaudon, A. Chambodut, P.-L. Blelly |
| Title |
Direct Determination of Geomagnetic Baselines During Quiet Periods for Low- and Mid-Latitude Observatories |
Type |
Journal |
| Year |
2022 |
Publication |
Journal of Geophysical Research: Space Physics |
Abbreviated Journal |
|
| Volume |
127 |
Issue |
8 |
Pages |
e2022JA030407 |
| Keywords |
magnetic baseline magnetic observatory data quiet geomagnetic field Sq current |
| Abstract |
The geomagnetic field is composed of a variety of sources that act on a wide range of timescales and amplitudes. The separation of magnetic storm effects from quiet variations is needed to accurately quantify impacts of space weather events. The extraction of such quiet contributions within geomagnetic measurements is achieved by the determination of baselines, which, ideally, is done by a simple algorithm which captures quiet sources suitably well, while being applicable to an extensive network of magnetic observatories independent of the period of time. In this work, we apply signal filtering techniques on the horizontal components of geomagnetic field measurements from low- and mid-latitude observatories to determine baselines. The variations within the baseline are investigated for magnetically quiet periods between 1991 and 2019, focusing on long-term trends, seasonal and local time dependencies, and day-to-day variability. The analysis confirms that the contributing quiet sources include the secular variation and the solar quiet (Sq) current system. The non-negligible day-to-day variability, that is typical for Sq in low- and mid-latitudes, is embedded within the baseline. Thus, the filter approach extracts quiet magnetic field variations well. Comparisons with other baseline methods show good agreements. We conclude that the filter approach can be used to determine baselines automatically during magnetically quiet periods without the need of further apriori information and is applicable on a wide network of magnetic observatories. It marks the first step for deriving magnetic indices for (near) real-time space weather applications. |
| Programme |
139 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
2169-9402 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
8568 |
| Permanent link to this record |
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| Author |
R. Sulzbach, H. Dobslaw, M. Thomas |
| Title |
High-Resolution Numerical Modeling of Barotropic Global Ocean Tides for Satellite Gravimetry |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Geophysical Research: Oceans |
Abbreviated Journal |
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| Volume |
126 |
Issue |
5 |
Pages |
e2020JC017097 |
| Keywords |
M2-tide minor tides pole-rotation self-attraction and loading tide-generating potential topographic wavedrag |
| Abstract |
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| Programme |
688 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
2169-9291 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
8605 |
| Permanent link to this record |
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| Author |
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| Title |
Cryptic vector divergence masks vector-specific patterns of infection: an example from the marine cycle of Lyme borreliosis
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Type |
Journal Article |
| Year |
2010 |
Publication |
Evolutionary Applications |
Abbreviated Journal |
Evol Appl |
| Volume |
3 |
Issue |
4 |
Pages |
391 -401 |
| Keywords |
lyme disease bacteria, pathogen detection, seabirds, site occupancy models, transmission, |
| Abstract |
Vector organisms are implicated in the transmission of close to a third of all infectious diseases. In many cases, multiple vectors (species or populations) can participate in transmission but may contribute differently to disease ecology and evolution. The presence of cryptic vector populations can be particularly problematic as differences in infection can be difficult to evaluate and may lead to erroneous evolutionary and epidemiological inferences. Here, we combine site-occupancy modeling and molecular assays to evaluate patterns of infection in the marine cycle of Lyme borreliosis, involving colonial seabirds, the tick Ixodes uriae, and bacteria of the Borrelia burgdorferi s.l. complex. In this cycle, the tick vector consists of multiple, cryptic (phenotypically undistinguishable but genetically distinct) host races that are frequently found in sympatry. Our results show that bacterial detection varies strongly among tick races leading to vector-specific biases if raw counts are used to calculate Borrelia prevalence. These differences are largely explained by differences in infection intensity among tick races. After accounting for detection probabilities, we found that overall prevalence in this system is higher than previously suspected and that certain vector-host combinations likely contribute more than others to the local dynamics and large-scale dispersal of Borrelia spirochetes. These results highlight the importance of evaluating vector population structure and accounting for detection probability when trying to understand the evolutionary ecology of vector-borne diseases.
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| Programme |
333 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
1752-4571 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
2324 |
| Permanent link to this record |
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| |
| Author |
Lynner Colton, Long Maureen D, |
| Title |
Lowermost mantle anisotropy and deformation along the boundary of the African LLSVP
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Type |
Journal Article |
| Year |
2014 |
Publication |
Geophysical Research Letters |
Abbreviated Journal |
|
| Volume |
41 |
Issue |
10 |
Pages |
3447-3454 |
| Keywords |
lowermost mantle anisotropy, African LLSVP, discrepant SKS-SKKS splitting, 7208 Mantle, 7203 Body waves, |
| Abstract |
Shear wave splitting of SK(K)S phases is often used to examine upper mantle anisotropy. In specific cases, however, splitting of these phases may reflect anisotropy in the lowermost mantle. Here we present SKS and SKKS splitting measurements for 233 event-station pairs at 34 seismic stations that sample D″ beneath Africa. Of these, 36 pairs show significantly different splitting between the two phases, which likely reflects a contribution from lowermost mantle anisotropy. The vast majority of discrepant pairs sample the boundary of the African large low shear velocity province (LLSVP), which dominates the lower mantle structure beneath this region. In general, we observe little or no splitting of phases that have passed through the LLSVP itself and significant splitting for phases that have sampled the boundary of the LLSVP. We infer that the D″ region just outside the LLSVP boundary is strongly deformed, while its interior remains undeformed (or weakly deformed). |
| Programme |
133 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
1944-8007 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
5026 |
| Permanent link to this record |
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| Author |
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| Title |
Composition of chick meals from one of the main little auk (Alle alle) breeding colonies in Northwest Greenland
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Type |
Journal Article |
| Year |
2014 |
Publication |
Polar Biology |
Abbreviated Journal |
|
| Volume |
37 |
Issue |
7 |
Pages |
1055-1060- |
| Keywords |
Little auk, Chick diet, High arctic, Seabirds, Calanus species, |
| Abstract |
During the last decade, increasing information on little auk (Alle alle) biology, ecology and behaviour has been reported. However, only a few of these studies have focused on the breeding population in the Avanersuaq (Thule) district of Northwest Greenland, where 80 % of the global little auk population is estimated to breed. This study reports on the chick diet composition from one of the largest colonies, the Paakitsoq colony, located on the south-eastern margin of the North Water (NOW) Polynya. Results revealed the highest proportion of Calanus hyperboreus, a large lipid-rich copepod, in chick diet reported for any little auk colony. Results confirmed that the cold,
highly productive waters of the NOW Polynya are favourable foraging grounds for the little auks during the breeding season. Species diversity within and between the chick meals was low, which probably reflects a high availability of a few preferred prey species. Individual chick meals were generally low in number of prey items and total energy content compared with other published results. This may be explained by a higher feeding frequency or by the samples being collected late in the breeding period (during late chick rearing), when chicks have a reduced growth rate and may require less energy than at earlier developmental stages. |
| Programme |
388 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
Springer Berlin Heidelberg |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0722-4060 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
5313 |
| Permanent link to this record |
