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Stefan Maus - One of the best experts on this subject based on the ideXlab platform.
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emag2 a 2 arc min resolution earth Magnetic Anomaly grid compiled from satellite airborne and marine Magnetic measurements
Geochemistry Geophysics Geosystems, 2009Co-Authors: Stefan Maus, J D Fairhead, Udo Barckhausen, H A Berkenbosch, N Bournas, John Brozena, Vicki A Childers, F Dostaler, Carol A FinnAbstract:[1] A global Earth Magnetic Anomaly Grid (EMAG2) has been compiled from satellite, ship, and airborne Magnetic measurements. EMAG2 is a significant update of our previous candidate grid for the World Digital Magnetic Anomaly Map. The resolution has been improved from 3 arc min to 2 arc min, and the altitude has been reduced from 5 km to 4 km above the geoid. Additional grid and track line data have been included, both over land and the oceans. Wherever available, the original shipborne and airborne data were used instead of precompiled oceanic Magnetic grids. Interpolation between sparse track lines in the oceans was improved by directional gridding and extrapolation, based on an oceanic crustal age model. The longest wavelengths (>330 km) were replaced with the latest CHAMP satellite Magnetic field model MF6. EMAG2 is available at http://geomag.org/models/EMAG2 and for permanent archive at http://earthref.org/cgi-bin/er.cgi?s=erda.cgi?n=970.
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Earth Magnetic Anomaly Grid Released
Eos Transactions American Geophysical Union, 2009Co-Authors: Stefan MausAbstract:An Earth Magnetic Anomaly Grid (EMAG2) compiled from satellite, ship, and airborne Magnetic measurements during a 2-year international collaborative effort was released in February 2009. Magnetic Anomaly maps provide insights into the subsurface structure and composition of the Earths crust. They are widely used in the geological sciences and in resource exploration. Furthermore, the global Magnetic map is useful in science education to illustrate plate tectonics, crustal interaction with the deep mantle, and other aspects of Earth evolution. Distinct patterns and Magnetic signatures on Magnetic Anomaly maps can be attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, the formation of continental crust by accretion of terranes to cratonic areas, and large-scale volcanism.
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Magnetic Anomaly map of the world merging satellite airborne marine and ground based Magnetic data sets
Earth and Planetary Science Letters, 2007Co-Authors: Dhananjay Ravat, Kumar Hemant, E Thebault, Mioara Mandea, Stefan MausAbstract:Abstract We report here a simple but practical method to combine systematically the Magnetic surveys of disparate specifications from marine, ground, aeroMagnetic and satellite platforms that aims to be helpful in the framework of the world digital Magnetic Anomaly map project. Because the satellite coverage and data quality is more uniform than near-surface surveys, it is adopted as the base map for wavelengths larger than 400 km and up to spherical harmonic degree inclusive of 16 (∼ 2500 km). After checking that satellite models and large aeroMagnetic wavelengths are not consistent, we filter out wavelengths longer than 400 km in aeroMagnetic compilations. Existing regional grids and, when available, individual surveys, are merged to give a more uniform spatial variation of the Magnetic anomalies. The effects of merging the grids are examined by plotting profiles and difference maps of the overlapping regions. A preliminary global map is obtained after combining the Magnetic Anomaly map with the downward continued CHAMP satellite derived Magnetic Anomaly map. Forthcoming availability of new datasets, as well as improvements in the procedure, will help to produce increasingly reliable maps.
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national geophysical data center candidate for the world digital Magnetic Anomaly map
Geochemistry Geophysics Geosystems, 2007Co-Authors: Stefan Maus, T Sazonova, Kumar Hemant, J D Fairhead, Dhananjay RavatAbstract:Marine and airborne Magnetic Anomaly data have been collected for more than half a century, providing global coverage of the Earth. Furthermore, the German CHAMP satellite is providing increasingly accurate information on large-scale Magnetic anomalies. The World Digital Magnetic Anomaly Map project is an international effort to integrate all available near-surface and satellite Magnetic Anomaly data into a global map database. Teams of researchers were invited to produce candidate maps using a common pool of data sets. Here we present the National Geophysical Data Center (NGDC) candidate. To produce a homogeneous map, the near-surface data were first line-leveled and then merged by Least Squares Collocation. Long wavelengths were found to agree surprisingly well with independent satellite information. This validates our final processing step of merging the short-wavelength part of the near-surface data with long-wavelength satellite Magnetic anomalies.
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Magnetic Anomaly map of the world: merging satellite, airborne, marine and ground-based Magnetic data sets
Earth and Planetary Science Letters, 2007Co-Authors: Kumar Hemant, Dhananjay Ravat, E Thebault, Mioara Mandea, Stefan MausAbstract:We report here a simple but practical method to combine systematically the Magnetic surveys of disparate specifications from marine, ground, aeroMagnetic and satellite platforms that aims to be helpful in the framework of the world digital Magnetic Anomaly map project. Because the satellite coverage and data quality is more uniform than near-surface surveys, it is adopted as the base map for wavelengths larger than 400 km and up to spherical harmonic degree inclusive of 16 (not, vert, similar 2500 km). After checking that satellite models and large aeroMagnetic wavelengths are not consistent, we filter out wavelengths longer than 400 km in aeroMagnetic compilations. Existing regional grids and, when available, individual surveys, are merged to give a more uniform spatial variation of the Magnetic anomalies. The effects of merging the grids are examined by plotting profiles and difference maps of the overlapping regions. A preliminary global map is obtained after combining the Magnetic Anomaly map with the downward continued CHAMP satellite derived Magnetic Anomaly map. Forthcoming availability of new datasets, as well as improvements in the procedure, will help to produce increasingly reliable maps.
Kumar Hemant - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Anomaly map of the world merging satellite airborne marine and ground based Magnetic data sets
Earth and Planetary Science Letters, 2007Co-Authors: Dhananjay Ravat, Kumar Hemant, E Thebault, Mioara Mandea, Stefan MausAbstract:Abstract We report here a simple but practical method to combine systematically the Magnetic surveys of disparate specifications from marine, ground, aeroMagnetic and satellite platforms that aims to be helpful in the framework of the world digital Magnetic Anomaly map project. Because the satellite coverage and data quality is more uniform than near-surface surveys, it is adopted as the base map for wavelengths larger than 400 km and up to spherical harmonic degree inclusive of 16 (∼ 2500 km). After checking that satellite models and large aeroMagnetic wavelengths are not consistent, we filter out wavelengths longer than 400 km in aeroMagnetic compilations. Existing regional grids and, when available, individual surveys, are merged to give a more uniform spatial variation of the Magnetic anomalies. The effects of merging the grids are examined by plotting profiles and difference maps of the overlapping regions. A preliminary global map is obtained after combining the Magnetic Anomaly map with the downward continued CHAMP satellite derived Magnetic Anomaly map. Forthcoming availability of new datasets, as well as improvements in the procedure, will help to produce increasingly reliable maps.
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national geophysical data center candidate for the world digital Magnetic Anomaly map
Geochemistry Geophysics Geosystems, 2007Co-Authors: Stefan Maus, T Sazonova, Kumar Hemant, J D Fairhead, Dhananjay RavatAbstract:Marine and airborne Magnetic Anomaly data have been collected for more than half a century, providing global coverage of the Earth. Furthermore, the German CHAMP satellite is providing increasingly accurate information on large-scale Magnetic anomalies. The World Digital Magnetic Anomaly Map project is an international effort to integrate all available near-surface and satellite Magnetic Anomaly data into a global map database. Teams of researchers were invited to produce candidate maps using a common pool of data sets. Here we present the National Geophysical Data Center (NGDC) candidate. To produce a homogeneous map, the near-surface data were first line-leveled and then merged by Least Squares Collocation. Long wavelengths were found to agree surprisingly well with independent satellite information. This validates our final processing step of merging the short-wavelength part of the near-surface data with long-wavelength satellite Magnetic anomalies.
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Magnetic Anomaly map of the world: merging satellite, airborne, marine and ground-based Magnetic data sets
Earth and Planetary Science Letters, 2007Co-Authors: Kumar Hemant, Dhananjay Ravat, E Thebault, Mioara Mandea, Stefan MausAbstract:We report here a simple but practical method to combine systematically the Magnetic surveys of disparate specifications from marine, ground, aeroMagnetic and satellite platforms that aims to be helpful in the framework of the world digital Magnetic Anomaly map project. Because the satellite coverage and data quality is more uniform than near-surface surveys, it is adopted as the base map for wavelengths larger than 400 km and up to spherical harmonic degree inclusive of 16 (not, vert, similar 2500 km). After checking that satellite models and large aeroMagnetic wavelengths are not consistent, we filter out wavelengths longer than 400 km in aeroMagnetic compilations. Existing regional grids and, when available, individual surveys, are merged to give a more uniform spatial variation of the Magnetic anomalies. The effects of merging the grids are examined by plotting profiles and difference maps of the overlapping regions. A preliminary global map is obtained after combining the Magnetic Anomaly map with the downward continued CHAMP satellite derived Magnetic Anomaly map. Forthcoming availability of new datasets, as well as improvements in the procedure, will help to produce increasingly reliable maps.
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geological modeling of the new champ Magnetic Anomaly maps using a geographical information system technique
Journal of Geophysical Research, 2005Co-Authors: Kumar Hemant, Stefan MausAbstract:[1] Reliable global crustal field Anomaly maps produced from Magnetic measurements of the CHAMP satellite mission now allow for quantitative geological studies of crustal structure and composition. We have developed a GIS based forward modeling technique to model these Anomaly maps. On the basis of the geologic and tectonic maps of the world, laboratory susceptibility values of the occurring rock types, and the seismic thickness of the crust, a vertically integrated susceptibility grid is generated in the GIS system. In addition, a remanent magnetization grid is computed for the oceanic crust using a digital isochron map of the ocean floor and rotation models of the paleoplates. Combining the global VIS and remanent magnetization grids, the vertical Magnetic field Anomaly is computed at satellite altitude and compared with the corresponding CHAMP Magnetic Anomaly map. Over the oceans, induced and remanent magnetization explains well the prominent observed anomalies over the Cretaceous quiet zones. We also find a good agreement between predicted and observed anomalies over the continents. Remaining discrepancies between the predicted and observed anomalies can be used to adjust poorly known boundaries and the composition of the buried Precambrian provinces, until the recomputed anomalies fit the observed anomalies. The feasibility of this approach is demonstrated on Greenland, the West African Craton, Bangui in central Africa, and the Kolyma-Omolon Block in Siberia. We conclude that quantitative information on the lateral extent, the composition and the thickness of the lower crust within a Precambrian province can thus be inferred from the new satellite Magnetic Anomaly maps.
Dhananjay Ravat - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Anomaly map of the world merging satellite airborne marine and ground based Magnetic data sets
Earth and Planetary Science Letters, 2007Co-Authors: Dhananjay Ravat, Kumar Hemant, E Thebault, Mioara Mandea, Stefan MausAbstract:Abstract We report here a simple but practical method to combine systematically the Magnetic surveys of disparate specifications from marine, ground, aeroMagnetic and satellite platforms that aims to be helpful in the framework of the world digital Magnetic Anomaly map project. Because the satellite coverage and data quality is more uniform than near-surface surveys, it is adopted as the base map for wavelengths larger than 400 km and up to spherical harmonic degree inclusive of 16 (∼ 2500 km). After checking that satellite models and large aeroMagnetic wavelengths are not consistent, we filter out wavelengths longer than 400 km in aeroMagnetic compilations. Existing regional grids and, when available, individual surveys, are merged to give a more uniform spatial variation of the Magnetic anomalies. The effects of merging the grids are examined by plotting profiles and difference maps of the overlapping regions. A preliminary global map is obtained after combining the Magnetic Anomaly map with the downward continued CHAMP satellite derived Magnetic Anomaly map. Forthcoming availability of new datasets, as well as improvements in the procedure, will help to produce increasingly reliable maps.
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national geophysical data center candidate for the world digital Magnetic Anomaly map
Geochemistry Geophysics Geosystems, 2007Co-Authors: Stefan Maus, T Sazonova, Kumar Hemant, J D Fairhead, Dhananjay RavatAbstract:Marine and airborne Magnetic Anomaly data have been collected for more than half a century, providing global coverage of the Earth. Furthermore, the German CHAMP satellite is providing increasingly accurate information on large-scale Magnetic anomalies. The World Digital Magnetic Anomaly Map project is an international effort to integrate all available near-surface and satellite Magnetic Anomaly data into a global map database. Teams of researchers were invited to produce candidate maps using a common pool of data sets. Here we present the National Geophysical Data Center (NGDC) candidate. To produce a homogeneous map, the near-surface data were first line-leveled and then merged by Least Squares Collocation. Long wavelengths were found to agree surprisingly well with independent satellite information. This validates our final processing step of merging the short-wavelength part of the near-surface data with long-wavelength satellite Magnetic anomalies.
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Magnetic Anomaly map of the world: merging satellite, airborne, marine and ground-based Magnetic data sets
Earth and Planetary Science Letters, 2007Co-Authors: Kumar Hemant, Dhananjay Ravat, E Thebault, Mioara Mandea, Stefan MausAbstract:We report here a simple but practical method to combine systematically the Magnetic surveys of disparate specifications from marine, ground, aeroMagnetic and satellite platforms that aims to be helpful in the framework of the world digital Magnetic Anomaly map project. Because the satellite coverage and data quality is more uniform than near-surface surveys, it is adopted as the base map for wavelengths larger than 400 km and up to spherical harmonic degree inclusive of 16 (not, vert, similar 2500 km). After checking that satellite models and large aeroMagnetic wavelengths are not consistent, we filter out wavelengths longer than 400 km in aeroMagnetic compilations. Existing regional grids and, when available, individual surveys, are merged to give a more uniform spatial variation of the Magnetic anomalies. The effects of merging the grids are examined by plotting profiles and difference maps of the overlapping regions. A preliminary global map is obtained after combining the Magnetic Anomaly map with the downward continued CHAMP satellite derived Magnetic Anomaly map. Forthcoming availability of new datasets, as well as improvements in the procedure, will help to produce increasingly reliable maps.
Masaki Matsushima - One of the best experts on this subject based on the ideXlab platform.
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regional mapping of the lunar Magnetic anomalies at the surface method and its application to strong and weak Magnetic Anomaly regions
Icarus, 2014Co-Authors: Hideo Tsunakawa, Hidetoshi Shibuya, Futoshi Takahashi, Hisayoshi Shimizu, Masaki MatsushimaAbstract:Abstract We have developed a new method for regional mapping of the lunar Magnetic anomalies as the vector field at the surface using the satellite observation, that is the surface vector mapping (SVM). The SVM is based on the inverse boundary value problem with a spherical boundary surface. There are two main procedures for reducing effects of bias and noise on mapping: (1) preprocessing the data to provide first derivatives along the pass, and (2) the Bayesian statistical procedure in the inversion using Akaike’s Bayesian Information Criterion. The SVM was applied to two regions: the northwest region of the South Pole-Aitken basin as a strong Magnetic Anomaly region, and the southeast region of the lunar near side as a weak Magnetic Anomaly region. Since the results from the different datasets of the Kaguya and Lunar Prospector observations show good consistency, characteristic features of the lunar Magnetic anomalies at the surface are considered to be well estimated except for components of wavelength shorter than about 1°. From the results by the SVM, both of the regions show elongation patterns of the lunar Magnetic anomalies, suggesting lineated structures of the Magnetic Anomaly sources.
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mini magnetosphere over the reiner gamma Magnetic Anomaly region on the moon
Geophysical Research Letters, 2005Co-Authors: M Kurata, Hidetoshi Shibuya, Masaki Matsushima, Hideo Tsunakawa, Y Saito, Hisayoshi ShimizuAbstract:[1] We show presence of a mini-magnetosphere above the Reiner Gamma Magnetic Anomaly (RGA) region in the solar wind, using Lunar Prospector magnetometer (MAG) measurement data. RGA is one of the strongest Magnetic anomalies on the Moon. Two Magnetic anomalies are found from six MAG datasets at 17–40 km altitudes in the lunar wake or the geoMagnetic tail lobe and are well explained by a two-dipole model. When RGA was exposed to the solar wind plasma, two MAG datasets were obtained at 27–29 km altitudes. Although the Magnetic anomalies survived against the plasma pressure, they were heavily distorted in comparison with the Magnetic field of the two-dipole model. Flow directions and dynamic pressures of the solar wind plasma at those periods indicate that the distortions were caused by forming a mini-magnetosphere over the RGA region in the solar wind.
E Thebault - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Anomaly map of the world merging satellite airborne marine and ground based Magnetic data sets
Earth and Planetary Science Letters, 2007Co-Authors: Dhananjay Ravat, Kumar Hemant, E Thebault, Mioara Mandea, Stefan MausAbstract:Abstract We report here a simple but practical method to combine systematically the Magnetic surveys of disparate specifications from marine, ground, aeroMagnetic and satellite platforms that aims to be helpful in the framework of the world digital Magnetic Anomaly map project. Because the satellite coverage and data quality is more uniform than near-surface surveys, it is adopted as the base map for wavelengths larger than 400 km and up to spherical harmonic degree inclusive of 16 (∼ 2500 km). After checking that satellite models and large aeroMagnetic wavelengths are not consistent, we filter out wavelengths longer than 400 km in aeroMagnetic compilations. Existing regional grids and, when available, individual surveys, are merged to give a more uniform spatial variation of the Magnetic anomalies. The effects of merging the grids are examined by plotting profiles and difference maps of the overlapping regions. A preliminary global map is obtained after combining the Magnetic Anomaly map with the downward continued CHAMP satellite derived Magnetic Anomaly map. Forthcoming availability of new datasets, as well as improvements in the procedure, will help to produce increasingly reliable maps.
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Magnetic Anomaly map of the world: merging satellite, airborne, marine and ground-based Magnetic data sets
Earth and Planetary Science Letters, 2007Co-Authors: Kumar Hemant, Dhananjay Ravat, E Thebault, Mioara Mandea, Stefan MausAbstract:We report here a simple but practical method to combine systematically the Magnetic surveys of disparate specifications from marine, ground, aeroMagnetic and satellite platforms that aims to be helpful in the framework of the world digital Magnetic Anomaly map project. Because the satellite coverage and data quality is more uniform than near-surface surveys, it is adopted as the base map for wavelengths larger than 400 km and up to spherical harmonic degree inclusive of 16 (not, vert, similar 2500 km). After checking that satellite models and large aeroMagnetic wavelengths are not consistent, we filter out wavelengths longer than 400 km in aeroMagnetic compilations. Existing regional grids and, when available, individual surveys, are merged to give a more uniform spatial variation of the Magnetic anomalies. The effects of merging the grids are examined by plotting profiles and difference maps of the overlapping regions. A preliminary global map is obtained after combining the Magnetic Anomaly map with the downward continued CHAMP satellite derived Magnetic Anomaly map. Forthcoming availability of new datasets, as well as improvements in the procedure, will help to produce increasingly reliable maps.
