Euro-African MAGSAT anomaly-tectonic observations

Science.gov (United States)

Hinze, W. J.; Olivier, R.; Vonfrese, R. R. B.

1985-01-01

Preliminary satellite (MAGSAT) scalar magnetic anomaly data are compiled and differentially reduced to radial polarization by equivalent point source inversion for comparison with tectonic data of Africa, Europe and adjacent marine areas. A number of associations are evident to constrain analyses of the tectonic features and history of the region. The Precambrian shields of Africa and Europe exhibit varied magnetic signatures. All shields are not magnetic highs and, in fact, the Baltic shield is a marked minimum. The reduced-to-the-pole magnetic map shows a marked tendency for northeasterly striking anomalies in the eastern Atlantic and adjacent Africa, which is coincident to the track of several hot spots for the past 100 million years. However, there is little consistency in the sign of the magnetic anomalies and the track of the hot spots. Comparison of the radially polarized anomalies of Africa and Europe with other reduced-to-the-pole magnetic satellite anomaly maps of the Western Hemisphere support the reconstruction of the continents prior to the origin of the present-day Atlantic Ocean in the Mesozoic Era.

Revisiting the South Atlantic Anomaly after 3 years of Swarm satellite mission

Science.gov (United States)

Pavón-Carrasco, F. Javier; Campuzano, Saioa A.; De Santis, Angelo

2017-04-01

Covering part of Southern America and the South Atlantic Ocean, the South Atlantic Anomaly (SAA) is nowadays one of the most important and largest features of the geomagnetic field at the Earth's surface. It is characterized by lower intensity values than expected for those geomagnetic latitudes. Thanks to the global geomagnetic models, the spatial and temporal geometry of the Earth's magnetic field can be defined at the core-mantle boundary, showing the origin of the SAA as a reversal polarity patch that is growing with a pronounced rate of -2.54ṡ105 nT per century and with western drift. Since the Swarm satellite mission of the European Space Agency was launched at the end of 2013, the three twin satellites are picking up the most accurate values of the geomagnetic field up to now. In this work, we use the satellite magnetic data from Swarm mission along with the observatory ground data of surrounding areas to evaluate the spatial and temporal evolution of the SAA during the Swarm-life.

Investigation of source location determination from Magsat magnetic anomalies: The Euler method approach

Science.gov (United States)

Ravat, Dhananjay

1996-01-01

The applicability of the Euler method of source location determination was investigated on several model situations pertinent to satellite-data scale situations as well as Magsat data of Europe. Our investigations enabled us to understand the end-member cases for which the Euler method will work with the present satellite magnetic data and also the cases for which the assumptions implicit in the Euler method will not be met by the present satellite magnetic data. These results have been presented in one invited lecture at the Indo-US workshop on Geomagnetism in Studies of the Earth's Interior in August 1994 in Pune, India, and at one presentation at the 21st General Assembly of the IUGG in July 1995 in Boulder, CO. A new method, called Anomaly Attenuation Rate (AAR) Method (based on the Euler method), was developed during this study. This method is scale-independent and is appropriate to locate centroids of semi-compact three dimensional sources of gravity and magnetic anomalies. The method was presented during 1996 Spring AGU meeting and a manuscript describing this method is being prepared for its submission to a high-ranking journal. The grant has resulted in 3 papers and presentations at national and international meetings and one manuscript of a paper (to be submitted shortly to a reputable journal).

Magnetic anomalies in the Cosmonauts Sea, off East Antarctica

Science.gov (United States)

Nogi, Y.; Hanyu, T.; Fujii, M.

2017-12-01

Identification of magnetic anomaly lineations and fracture zone trends in the Southern Indian Ocean, are vital to understanding the breakup of Gondwana. However, the magnetic spreading anomalies and fracture zones are not clear in the Southern Indian Ocean. Magnetic anomaly lineations in the Cosmonauts Sea, off East Antarctica, are key to elucidation of separation between Sri Lanka/India and Antarctica. No obvious magnetic anomaly lineations are observed from a Japanese/German aerogeophysical survey in the Cosmonauts Sea, and this area is considered to be created by seafloor spreading during the Cretaceous Normal Superchron. Vector magnetic anomaly measurements have been conducted on board the Icebreaker Shirase mainly to understand the process of Gondwana fragmentation in the Indian Ocean. Magnetic boundary strikes are derived from vector magnetic anomalies obtained in the Cosmonauts Sea. NE-SW trending magnetic boundary strikes are mainly observed along the several NW-SE oriented observation lines with magnetic anomaly amplitudes of about 200 nT. These NE-SW trending magnetic boundary strikes possibly indicate M-series magnetic anomalies that can not be detected from the aerogeophysical survey with nearly N-S observation lines. We will discuss the magnetic spreading anomalies and breakup process between Sri Lanka/India and Antarctica in the Cosmonauts Sea.

Towards improved knowledge of geology and global thermal regime from Swarm satellites magnetic gradient observations

DEFF Research Database (Denmark)

Ravat, Dhananjay; Olsen, Nils; Sabaka, Terence

Gradients of magnetic field have higher spatial resolution than the fields themselves and are helpful in improving the resolution of downward continued satellite magnetic anomaly maps (Kotsiaros et al., 2015, Geophys. J. Int.; Sabaka et al., 2015, Geophys. J. Int.). Higher spatial resolution and ...

Inversion of Magnetic Measurements of the CHAMP Satellite Over the Pannonian Basin

Science.gov (United States)

Kis, K. I.; Taylor, P. T.; Wittmann, G.; Toronyi, B.; Puszta, S.

2011-01-01

The Pannonian Basin is a deep intra-continental basin that formed as part of the Alpine orogeny. In order to study the nature of the crustal basement we used the long-wavelength magnetic anomalies acquired by the CHAMP satellite. The anomalies were distributed in a spherical shell, some 107,927 data recorded between January 1 and December 31 of 2008. They covered the Pannonian Basin and its vicinity. These anomaly data were interpolated into a spherical grid of 0.5 x 0.5, at the elevation of 324 km by the Gaussian weight function. The vertical gradient of these total magnetic anomalies was also computed and mapped to the surface of a sphere at 324 km elevation. The former spherical anomaly data at 425 km altitude were downward continued to 324 km. To interpret these data at the elevation of 324 km we used an inversion method. A polygonal prism forward model was used for the inversion. The minimum problem was solved numerically by the Simplex and Simulated annealing methods; a L2 norm in the case of Gaussian distribution parameters and a L1 norm was used in the case of Laplace distribution parameters. We INTERPRET THAT the magnetic anomaly WAS produced by several sources and the effect of the sable magnetization of the exsolution of hemo-ilmenite minerals in the upper crustal metamorphic rocks.

Magsat - A new satellite to survey the earth's magnetic field

Science.gov (United States)

Mobley, F. F.; Eckard, L. D.; Fountain, G. H.; Ousley, G. W.

1980-01-01

The Magsat satellite was launched on Oct. 30, 1979 into a sun-synchronous dawn-dusk orbit, of 97 deg inclination, 350 km perigee, and 550 km apogee. It contains a precision vector magnetometer and a cesium-vapor scalar magnetometer at the end of a 6-m long graphite epoxy scissors boom. The magnetometers are accurate to 2 nanotesla. A pair of star cameras are used to define the body orientation to 10 arc sec rms. An 'attitude transfer system' measures the orientation of the magnetometer sensors relative to the star cameras to approximately 5 arc sec rms. The satellite position is determined to 70 meters rms by Doppler tracking. The overall objective is to determine each component of the earth's vector magnetic field to an accuracy of 6 nanotesla rms. The Magsat satellite gathers a complete picture of the earth's magnetic field every 12 hours. The vector components are sampled 16 times per second with a resolution of 0.5 nanotesla. The data will be used by the U.S. Geological Survey to prepare 1980 world magnetic field charts and to detect large-scale magnetic anomalies in the earth's crust for use in planning resource exploration strategy.

Retrieving Temperature Anomaly in the Global Subsurface and Deeper Ocean From Satellite Observations

Science.gov (United States)

Su, Hua; Li, Wene; Yan, Xiao-Hai

2018-01-01

Retrieving the subsurface and deeper ocean (SDO) dynamic parameters from satellite observations is crucial for effectively understanding ocean interior anomalies and dynamic processes, but it is challenging to accurately estimate the subsurface thermal structure over the global scale from sea surface parameters. This study proposes a new approach based on Random Forest (RF) machine learning to retrieve subsurface temperature anomaly (STA) in the global ocean from multisource satellite observations including sea surface height anomaly (SSHA), sea surface temperature anomaly (SSTA), sea surface salinity anomaly (SSSA), and sea surface wind anomaly (SSWA) via in situ Argo data for RF training and testing. RF machine-learning approach can accurately retrieve the STA in the global ocean from satellite observations of sea surface parameters (SSHA, SSTA, SSSA, SSWA). The Argo STA data were used to validate the accuracy and reliability of the results from the RF model. The results indicated that SSHA, SSTA, SSSA, and SSWA together are useful parameters for detecting SDO thermal information and obtaining accurate STA estimations. The proposed method also outperformed support vector regression (SVR) in global STA estimation. It will be a useful technique for studying SDO thermal variability and its role in global climate system from global-scale satellite observations.

Global magnetic anomaly and aurora of Neptune

International Nuclear Information System (INIS)

Cheng, A.F.

1990-01-01

The large offset and tilt of Neptune's dipole magnetic field combine to create a global magnetic anomaly, analogous to but much more important than Earth's South Atlantic Anomaly. Energetic particle precipitation loss within the Neptune anomaly creates atmospheric drift shadows within which particle fluxes are greatly reduced. The energetic particle dropout observed by Voyager near closest approach occurred near the predicted times when Voyager passed within the atmospheric drift shadow. Extremely soft, structured bursts of ions and electrons within the drift shadow may result from plasma wave-induced pitch angle scattering of trapped particles confined near the magnetic equator. The dropout does not necessarily imply that Voyager passed through an Earth-like discrete auroral zone, as earlier reported. The ion and electron fluxes observed within the dropout period correspond to particles that must precipitate to Neptune's atmosphere within the anomaly region. This anomaly precipitation can account for a major portion of the ultraviolet emissions previously identified as Neptune aurora

Derivation and Error Analysis of the Earth Magnetic Anomaly Grid at 2 arc min Resolution Version 3 (EMAG2v3)

Science.gov (United States)

Meyer, B.; Chulliat, A.; Saltus, R.

2017-12-01

The Earth Magnetic Anomaly Grid at 2 arc min resolution version 3, EMAG2v3, combines marine and airborne trackline observations, satellite data, and magnetic observatory data to map the location, intensity, and extent of lithospheric magnetic anomalies. EMAG2v3 includes over 50 million new data points added to NCEI's Geophysical Database System (GEODAS) in recent years. The new grid relies only on observed data, and does not utilize a priori geologic structure or ocean-age information. Comparing this grid to other global magnetic anomaly compilations (e.g., EMAG2 and WDMAM), we can see that the inclusion of a priori ocean-age patterns forces an artificial linear pattern to the grid; the data-only approach allows for greater complexity in representing the evolution along oceanic spreading ridges and continental margins. EMAG2v3 also makes use of the satellite-derived lithospheric field model MF7 in order to accurately represent anomalies with wavelengths greater than 300 km and to create smooth grid merging boundaries. The heterogeneous distribution of errors in the observations used in compiling the EMAG2v3 was explored, and is reported in the final distributed grid. This grid is delivered at both 4 km continuous altitude above WGS84, as well as at sea level for all oceanic and coastal regions.

A Qualitative Interpretation of Residual Magnetic Anomaly using ...

African Journals Online (AJOL)

A Qualitative Interpretation of Residual Magnetic Anomaly using Ground ... The magnetic data was collected using a G816 proton precision magnetometer. ... Analysis of residual anomaly graph reveals the existence of some structural features ...

Satellite Anomalies: Benefits of a Centralized Anomaly Database and Methods for Securely Sharing Information Among Satellite Operators

Science.gov (United States)

2014-01-01

is more or less prone to anomalies. The Atrium Space Insurance Corporation (ASIC) at Lloyd’s of London Insurance Market insures approximately 190...Oceanic and Atmospheric Administration, National Geophysical Data Center, 1993. As of December 6, 2012: http://www.ngdc.noaa.gov/ stp /satellite...National Geophysical Data Center, Online Publications, undated a. As of November 1, 2013: http://www.ngdc.noaa.gov/ stp /solar/onlinepubl.html ———, Space

Discriminating satellite IR anomalies associated with the MS 7.1 Yushu earthquake in China

Science.gov (United States)

Qin, Kai; Wu, Lixin; Zheng, Shuo; Ma, Weiyu

2018-03-01

In the process of exploring pre-earthquake thermal anomalies using satellite infrared data, Blackett et al. (2011) found that the previously reported anomalies before the 2001 Mw 7.7 Gujarat earthquake, in India, were related to positive biases caused by data gaps due to cloud cover and mosaicing of neighboring orbits of MODIS satellite data. They supposed that such effects could also be responsible for other cases. We noted a strip-shaped TIR anomaly on March 17th, 2010, 28 days before the Ms. 7.1 Yushu earthquake (Qin et al., 2011). Here we again investigate multi-year infrared satellite data in different bands to discriminate whether the anomaly is associated with the earthquake, or is only bias caused by the data gaps. From the water vapor images, we find lots of clouds that have TIR anomalies. However, on the cloudiness background, there is an obvious strip-shaped gap matching the tectonic faults almost perfectly. In particular, the animation loops of hourly water vapor images show that the cloud kept moving from west to east, while they never covered the strip-shaped gap. We consider that the cloud with this special spatial pattern should have implied the abnormal signals associated with the seismogenic process. Based on current physical models, the satellite IR anomalies both on TIR and water vapor bands can qualitatively be explained using synthetic mechanisms.

Earth's lithospheric magnetic field determined to spherical harmonic degree 90 from CHAMP satellite measurements

DEFF Research Database (Denmark)

Maus, S.; Rother, M.; Hemant, K.

2006-01-01

of the lithospheric field down to an altitude of about 50 km at lower latitudes, with reduced accuracy in the polar regions. Crustal features come out significantly sharper than in previous models. In particular, bands of magnetic anomalies along subduction zones become visible by satellite for the first time....

Magnetic Satellite Missions and Data

DEFF Research Database (Denmark)

Olsen, Nils; Kotsiaros, Stavros

2011-01-01

Although the first satellite observations of the Earth’s magnetic field were already taken more than 50 years ago, continuous geomagnetic measurements from space are only available since 1999. The unprecedented time-space coverage of this recent data set opened revolutionary new possibilities...... for exploring the Earth’s magnetic field from space. In this chapter we discuss characteristics of satellites measuring the geomagnetic field and report on past, present and upcoming magnetic satellite missions. We conclude with some basics about space magnetic gradiometry as a possible path for future...... exploration of Earth’s magnetic field with satellites....

Deep and shallow structures in the Arctic region imaged by satellite magnetic and gravity data

Science.gov (United States)

Gaina, Carmen; Panet, Isabelle; Shephard, Grace

2016-07-01

The last decade has seen an increase in geoscientific data collection, which, together with available and older classified data made publicly available, is contributing to increasing our knowledge about Earth's structure and evolution. Despite this development, there are many gaps in data coverage in remote, hard-to-access regions. Satellite data have the advantage of acquiring measurements steadily and covering the entire globe. From a tectonics point of view, the specific heights of various satellites allow for the identification of moderate to large tectonic features, and can shed light on Earth's lower crust and lithosphere structure. In this contribution I discuss the use of magnetic and gravity models based on satellite data in deciphering the tectonic structure of remote areas. The present day Circum-Arctic region comprises a variety of tectonic settings: from active seafloor spreading in the North Atlantic and Eurasian Basin, and subduction in the North Pacific, to long-lived stable continental platforms in North America and Asia. A series of rifted margins, abandoned rifted areas and presumably extinct oceanic basins fringe these regions. Moreover, rifting- and seafloor spreading-related processes formed many continental splinters and terranes that were transported and docked at higher latitudes. Volcanic provinces of different ages have also been identified, from the Permian-Triassic Siberian traps at ca. 251 Ma to the (presumably) Cretaceous HALIP and smaller Cenozoic provinces in northern Greenland and the Barents Sea. We inspect global lithospheric magnetic data in order to identify the signature of the main volcanic provinces in the High Arctic. One of the most striking features in the Arctic domain is the strong magnetic anomaly close to the North Pole that correlates with a large, igneous oceanic plateau called the Alpha Mendeleev Ridge. The intensity and extent of the magnetic anomalies recorded by aircraft or satellites point towards a very thick

Magnetic anomalies in Central Bengal fan

Digital Repository Service at National Institute of Oceanography (India)

Rao, T.C.S.; Lakshminarayana, S.; Sarma, K.V.L.N.S.

Total magnetic field anomalies recorded over the Central Bengal Fan are analysed and the depths to the magnetic basement are computed using the analytical signal and the Werner deconvolution methods. To the west and east of 85 degrees E...

Anomaly Monitoring Method for Key Components of Satellite

Directory of Open Access Journals (Sweden)

Jian Peng

2014-01-01

Full Text Available This paper presented a fault diagnosis method for key components of satellite, called Anomaly Monitoring Method (AMM, which is made up of state estimation based on Multivariate State Estimation Techniques (MSET and anomaly detection based on Sequential Probability Ratio Test (SPRT. On the basis of analysis failure of lithium-ion batteries (LIBs, we divided the failure of LIBs into internal failure, external failure, and thermal runaway and selected electrolyte resistance (Re and the charge transfer resistance (Rct as the key parameters of state estimation. Then, through the actual in-orbit telemetry data of the key parameters of LIBs, we obtained the actual residual value (RX and healthy residual value (RL of LIBs based on the state estimation of MSET, and then, through the residual values (RX and RL of LIBs, we detected the anomaly states based on the anomaly detection of SPRT. Lastly, we conducted an example of AMM for LIBs, and, according to the results of AMM, we validated the feasibility and effectiveness of AMM by comparing it with the results of threshold detective method (TDM.

Spacecraft anomalies on the CRRES satellite correlated with the environment and insulator samples

International Nuclear Information System (INIS)

Violet, M.D.; Frederickson, A.R.

1993-01-01

The CRRES satellite has been extensively surveyed for the occurrence of onboard anomalies. CRRES system and instrument responses which were not programmed or commanded are classified as anomalies. The history of anomalies is correlated with the history of plasmas, high energy particles, and electromagnetic fields as measured on CRRES. The anomalies for each instrument on CRRES are compared with those from other instruments. The 674 anomalies, as a group, correlate well with high levels of high energy electron flux and poorly with every other environmental parameter

Magnetic anomalies in SmMn2Ge2

International Nuclear Information System (INIS)

Mallik, R.; Sampathkumaran, E.V.; Paulose, P.L.

1997-01-01

The results of electrical resistance (ρ), magnetoresistance (Δρ/ρ) and magnetization (M) measurements are reported for polycrystalline SmMn 2 Ge 2 . Sharp variations in ρ at 108 and 142 K attributable to well-known magnetic transitions from Mn sublattice are noted. Sign of the ρ across these transitions exhibits anomalies. Δρ/ρ data indicate the existence of a hitherto unrecognized magnetic anomaly near 30 K, presumably of ferrimagnetic type as revealed by isothermal M data at low temperatures. (orig.)

Magnetic resonance in prenatal diagnosis of thoracic anomalies

International Nuclear Information System (INIS)

Pietrani, M.; Elias, D.; Wojakowski, A.; Fataljaef, V.; Carcano, M.; Otano, L.

2007-01-01

The objective of this article is to communicate the experience in the evaluation of fetal anomalies thoracic by means of magnetic resonance. Between January, 2001 - March, 2007 16 fetus were evaluated by means of magnetic resonance with echographic diagnosis of thoracic anomalies. An equipment of 1.5 TESLA was used. The thoracic anatomy was valued in general. At the presence of discovering pulmonary mass, their size, volume and intensity of sign were determined. The echographic and magnetic resonance findings were checked against the perinatal results [es

SEISMIC DISCRIMINATION OF THERMAL AND MAGNETIC ANOMALIES IN SUNSPOT UMBRAE

International Nuclear Information System (INIS)

Lindsey, C.; Cally, P. S.; Rempel, M.

2010-01-01

Efforts to model sunspots based on helioseismic signatures need to discriminate between the effects of (1) a strong magnetic field that introduces time-irreversible, vantage-dependent phase shifts, apparently connected to fast- and slow-mode coupling and wave absorption and (2) a thermal anomaly that includes cool gas extending an indefinite depth beneath the photosphere. Helioseismic observations of sunspots show travel times considerably reduced with respect to equivalent quiet-Sun signatures. Simulations by Moradi and Cally of waves skipping across sunspots with photospheric magnetic fields of order 3 kG show travel times that respond strongly to the magnetic field and relatively weakly to the thermal anomaly by itself. We note that waves propagating vertically in a vertical magnetic field are relatively insensitive to the magnetic field, while remaining highly responsive to the attendant thermal anomaly. Travel-time measurements for waves with large skip distances into the centers of axially symmetric sunspots are therefore a crucial resource for discrimination of the thermal anomaly beneath sunspot umbrae from the magnetic anomaly. One-dimensional models of sunspot umbrae based on compressible-radiative-magnetic-convective simulations such as by Rempel et al. can be fashioned to fit observed helioseismic travel-time spectra in the centers of sunspot umbrae. These models are based on cooling of the upper 2-4 Mm of the umbral subphotosphere with no significant anomaly beneath 4.5 Mm. The travel-time reductions characteristic of these models are primarily a consequence of a Wilson depression resulting from a strong downward buoyancy of the cooled umbral medium.

Marine magnetic anomalies off Ratnagiri, Western continental shelf of India

Digital Repository Service at National Institute of Oceanography (India)

Rao, D.G.

of magnetic anomalies. Two-dimensional model and spectral studies of these anomalies were carried out, and subsurface models of the geology in the area have been derived from anomalies at a number of places. The results suggest that the anomalies occur over a...

Particle precipitation events in the South Atlantic Magnetic Anomaly (SAMA) and geomagnetic field

International Nuclear Information System (INIS)

Sanchez Bettucci, L.; Caraballo, R.; Da Silva Barbosa, C.

2003-01-01

Particle precipitation events in the South Atlantic Magnetic Anomaly (SAMA) have been correlated with impulses in the H component of the geomagnetic field. Sudden changes in the H component of the geomagnetic field can produce high intensity peaks in geomagnetic induced currents (GIC) at the Earth’s surface. The effects related to electron precipitation on the upper and middle atmosphere are still not well understood, especially in the area of the SAMA. This study focuses on the Halloween magnetic storm (29-31 October 2003) and two of the largest magnetic storms occurred in 2011. Data from POES and DMSP satellites have been contrasted with the Vassoura s magnetic observatory records and the GIC in a H V transformer neutral at Itumbiara substation (central Brazilian area) to look for possible correlations between d H, the GIC and the precipitation flux of ultrarelativistic electrons. The observations suggest some overlap between episodes of intense precipitation of electrons in the inner radiation belt and impulsive changes in these variables

THEMIS satellite observations of hot flow anomalies at Earth's bow shock

Directory of Open Access Journals (Sweden)

C. Chu

2017-03-01

Full Text Available Hot flow anomalies (HFAs at Earth's bow shock were identified in Time History of Events and Macroscale Interactions During Substorms (THEMIS satellite data from 2007 to 2009. The events were classified as young or mature and also as regular or spontaneous hot flow anomalies (SHFAs. The dataset has 17 young SHFAs, 49 mature SHFAs, 15 young HFAs, and 55 mature HFAs. They span a wide range of magnetic local times (MLTs from approximately 7 to 16.5 MLT. The largest ratio of solar wind to HFA core density occurred near dusk and at larger distances from the bow shock. In this study, HFAs and SHFAs were observed up to 6.3 RE and 6.1 RE (Earth radii, respectively, upstream from the model bow shock. HFA–SHFA occurrence decreases with distance upstream from the bow shock. HFAs of the highest event core ion temperatures were not seen at the flanks. The ratio of HFA ion temperature increase to HFA electron temperature increase is highest around 12 MLT and slightly duskward. For SHFAs, (Tihfa∕Tisw/(Tehfa∕Tesw generally increased with distance from the bow shock. Both mature and young HFAs are more prevalent when there is an approximately radial interplanetary magnetic field. HFAs occur most preferentially for solar wind speeds from 550 to 600 km s−1. The correlation coefficient between the HFA increase in thermal energy density from solar wind values and the decrease in kinetic energy density from solar wind values is 0.62. SHFAs and HFAs do not show major differences in this study.

Lunar magnetic anomalies detected by the Apollo substatellite magnetometers

Science.gov (United States)

Hood, L.L.; Coleman, P.J.; Russell, C.T.; Wilhelms, D.E.

1979-01-01

Properties of lunar crustal magnetization thus far deduced from Apollo subsatellite magnetometer data are reviewed using two of the most accurate presently available magnetic anomaly maps - one covering a portion of the lunar near side and the other a part of the far side. The largest single anomaly found within the region of coverage on the near-side map correlates exactly with a conspicuous, light-colored marking in western Oceanus Procellarum called Reiner Gamma. This feature is interpreted as an unusual deposit of ejecta from secondary craters of the large nearby primary impact crater Cavalerius. An age for Cavalerius (and, by implication, for Reiner Gamma) of 3.2 ?? 0.2 ?? 109 y is estimated. The main (30 ?? 60 km) Reiner Gamma deposit is nearly uniformly magnetized in a single direction, with a minimum mean magnetization intensity of ???7 ?? 10-2 G cm3/g (assuming a density of 3 g/cm3), or about 700 times the stable magnetization component of the most magnetic returned samples. Additional medium-amplitude anomalies exist over the Fra Mauro Formation (Imbrium basin ejecta emplaced ???3.9 ?? 109 y ago) where it has not been flooded by mare basalt flows, but are nearly absent over the maria and over the craters Copernicus, Kepler, and Reiner and their encircling ejecta mantles. The mean altitude of the far-side anomaly gap is much higher than that of the near-side map and the surface geology is more complex, so individual anomaly sources have not yet been identified. However, it is clear that a concentration of especially strong sources exists in the vicinity of the craters Van de Graaff and Aitken. Numerical modeling of the associated fields reveals that the source locations do not correspond with the larger primary impact craters of the region and, by analogy with Reiner Gamma, may be less conspicuous secondary crater ejecta deposits. The reason for a special concentration of strong sources in the Van de Graaff-Aitken region is unknown, but may be indirectly

Combined analysis of magnetic and gravity anomalies using normalized source strength (NSS)

Science.gov (United States)

Li, L.; Wu, Y.

2017-12-01

Gravity field and magnetic field belong to potential fields which lead inherent multi-solution. Combined analysis of magnetic and gravity anomalies based on Poisson's relation is used to determinate homology gravity and magnetic anomalies and decrease the ambiguity. The traditional combined analysis uses the linear regression of the reduction to pole (RTP) magnetic anomaly to the first order vertical derivative of the gravity anomaly, and provides the quantitative or semi-quantitative interpretation by calculating the correlation coefficient, slope and intercept. In the calculation process, due to the effect of remanent magnetization, the RTP anomaly still contains the effect of oblique magnetization. In this case the homology gravity and magnetic anomalies display irrelevant results in the linear regression calculation. The normalized source strength (NSS) can be transformed from the magnetic tensor matrix, which is insensitive to the remanence. Here we present a new combined analysis using NSS. Based on the Poisson's relation, the gravity tensor matrix can be transformed into the pseudomagnetic tensor matrix of the direction of geomagnetic field magnetization under the homologous condition. The NSS of pseudomagnetic tensor matrix and original magnetic tensor matrix are calculated and linear regression analysis is carried out. The calculated correlation coefficient, slope and intercept indicate the homology level, Poisson's ratio and the distribution of remanent respectively. We test the approach using synthetic model under complex magnetization, the results show that it can still distinguish the same source under the condition of strong remanence, and establish the Poisson's ratio. Finally, this approach is applied in China. The results demonstrated that our approach is feasible.

Marine magnetic anomalies in the northeastern Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Bhattacharya, G.C.; Chaubey, A; Murty, G.P.S.; Rao, D.G.; Scherbakov, V.S.; Lygin, V.A; Philipenko, A; Bogomyagkov, A

Based on the analysis of some additional magnetic profiles, an updated correlation and identification of the sea-floor spreading type magnetic lineations in the northeastern Arabian Sea is presented. The anomaly 24 A-B sequence, characteris...

Size-dependent avoidance of a strong magnetic anomaly in Caribbean spiny lobsters.

Science.gov (United States)

Ernst, David A; Lohmann, Kenneth J

2018-03-01

On a global scale, the geomagnetic field varies predictably across the Earth's surface, providing animals that migrate long distances with a reliable source of directional and positional information that can be used to guide their movements. In some locations, however, magnetic minerals in the Earth's crust generate an additional field that enhances or diminishes the overall field, resulting in unusually steep gradients of field intensity within a limited area. How animals respond to such magnetic anomalies is unclear. The Caribbean spiny lobster, Panulirus argus , is a benthic marine invertebrate that possesses a magnetic sense and is likely to encounter magnetic anomalies during migratory movements and homing. As a first step toward investigating whether such anomalies affect the behavior of lobsters, a two-choice preference experiment was conducted in which lobsters were allowed to select one of two artificial dens, one beneath a neodymium magnet and the other beneath a non-magnetic weight of similar size and mass (control). Significantly more lobsters selected the control den, demonstrating avoidance of the magnetic anomaly. In addition, lobster size was found to be a significant predictor of den choice: lobsters that selected the anomaly den were significantly smaller as a group than those that chose the control den. Taken together, these findings provide additional evidence for magnetoreception in spiny lobsters, raise the possibility of an ontogenetic shift in how lobsters respond to magnetic fields, and suggest that magnetic anomalies might influence lobster movement in the natural environment. © 2018. Published by The Company of Biologists Ltd.

On the magnetic anomaly at Easter Island during the 2010 Chile tsunami

Directory of Open Access Journals (Sweden)

Benlong Wang

2015-08-01

Full Text Available A magnetic anomaly was recorded at Easter Island on 27 February 2010 during the Chile tsunami event. The physics of the magnetic anomaly is analyzed using kinematic dynamo theory. Using a single wave model, the space and time behavior of the magnetic field is given. By joint analysis of the magnetic observations, tide gauge data and numerical results of the global tsunami propagation, we show the close resemblance between the predicted spatial and temporal magnetic distributions and the field data, indicating the magnetic anomaly at Easter Island was actually induced by the motion of seawater under tsunami waves. Similarity between the field magnetic data at Easter Island during 2010 Chile tsunami and sea surface level is verified with realistic tsunami propagating model.

Airborne detection of magnetic anomalies associated with soils on the Oak Ridge Reservation, Tennessee

International Nuclear Information System (INIS)

Doll, W.E.; Beard, L.P.; Helm, J.M.

1995-01-01

Reconnaissance airborne geophysical data acquired over the 35,000-acre Oak Ridge Reservation (ORR), TN, show several magnetic anomalies over undisturbed areas mapped as Copper Ridge Dolomite (CRD). The anomalies of interest are most apparent in magnetic gradient maps where they exceed 0.06 nT/m and in some cases exceed 0.5 nT/m. Anomalies as large as 25nT are seen on maps. Some of the anomalies correlate with known or suspected karst, or with apparent conductivity anomalies calculated from electromagnetic data acquired contemporaneously with the magnetic data. Some of the anomalies have a strong correlation with topographic lows or closed depressions. Surface magnetic data have been acquired over some of these sites and have confirmed the existence of the anomalies. Ground inspections in the vicinity of several of the anomalies has not led to any discoveries of manmade surface materials of sufficient size to generate the observed anomalies. One would expect an anomaly of approximately 1 nT for a pickup truck from 200 ft altitude. Typical residual magnetic anomalies have magnitudes of 5--10 nT, and some are as large as 25nT. The absence of roads or other indications of culture (past or present) near the anomalies and the modeling of anomalies in data acquired with surface instruments indicate that man-made metallic objects are unlikely to be responsible for the anomaly. The authors show that observed anomalies in the CRD can reasonably be associated with thickening of the soil layer. The occurrence of the anomalies in areas where evidences of karstification are seen would follow because sediment deposition would occur in topographic lows. Linear groups of anomalies on the maps may be associated with fracture zones which were eroded more than adjacent rocks and were subsequently covered with a thicker blanket of sediment. This study indicates that airborne magnetic data may be of use in other sites where fracture zones or buried collapse structures are of interest

Magnetic anomalies in SmMn{sub 2}Ge{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Mallik, R; Sampathkumaran, E V; Paulose, P L [Tata Inst. of Fundamental Res., Mumbai (India). Solid State Phys. Group

1997-02-01

The results of electrical resistance ({rho}), magnetoresistance ({Delta}{rho}/{rho}) and magnetization (M) measurements are reported for polycrystalline SmMn{sub 2}Ge{sub 2}. Sharp variations in {rho} at 108 and 142 K attributable to well-known magnetic transitions from Mn sublattice are noted. Sign of the {rho} across these transitions exhibits anomalies. {Delta}{rho}/{rho} data indicate the existence of a hitherto unrecognized magnetic anomaly near 30 K, presumably of ferrimagnetic type as revealed by isothermal M data at low temperatures. (orig.). 5 refs.

Basement configuration of KG offshore basin from magnetic anomalies

Digital Repository Service at National Institute of Oceanography (India)

Subrahmanyam, V.; Swamy, K.V.; Raj, N.

to Dept. of Science & Technology, New Delhi for granting the Junior Research Fel- lowship through Inspire Programme. This is NIO (CSIR) contribution no. 7132. References Aftalion M, Bowes D R, Dash B and Dempster T J 1988 Late proterozoic charnockites... anomaly map in figure 1. Keywords. Marine magnetic anomalies; offshore K–G basin; magnetic basement; extension of EGMB geology; continent– oceanic boundary. J. Earth Syst. Sci. 125, No. 3, April 2016, pp. 663–668 c© Indian Academy of Sciences 663 664 V...

Tactile sensor of hardness recognition based on magnetic anomaly detection

Science.gov (United States)

Xue, Lingyun; Zhang, Dongfang; Chen, Qingguang; Rao, Huanle; Xu, Ping

2018-03-01

Hardness, as one kind of tactile sensing, plays an important role in the field of intelligent robot application such as gripping, agricultural harvesting, prosthetic hand and so on. Recently, with the rapid development of magnetic field sensing technology with high performance, a number of magnetic sensors have been developed for intelligent application. The tunnel Magnetoresistance(TMR) based on magnetoresistance principal works as the sensitive element to detect the magnetic field and it has proven its excellent ability of weak magnetic detection. In the paper, a new method based on magnetic anomaly detection was proposed to detect the hardness in the tactile way. The sensor is composed of elastic body, ferrous probe, TMR element, permanent magnet. When the elastic body embedded with ferrous probe touches the object under the certain size of force, deformation of elastic body will produce. Correspondingly, the ferrous probe will be forced to displace and the background magnetic field will be distorted. The distorted magnetic field was detected by TMR elements and the output signal at different time can be sampled. The slope of magnetic signal with the sampling time is different for object with different hardness. The result indicated that the magnetic anomaly sensor can recognize the hardness rapidly within 150ms after the tactile moment. The hardness sensor based on magnetic anomaly detection principal proposed in the paper has the advantages of simple structure, low cost, rapid response and it has shown great application potential in the field of intelligent robot.

Shaded relief magnetic anomaly map of Italy and surrounding marine areas

International Nuclear Information System (INIS)

Chiappini, M.; Meloni, A.; Boschi, E.; Faggioni, O.; Beverini, N.; Carmisciano, C.; Marson, I.

2000-01-01

Magnetic observations made onshore the Italian Peninsula, and across the adjacent seas, have been compiled in a new digital database that provides the first complete regional scale view of the crustal scale magnetic anomalies of the regional at sea level. The offshore data were acquired between 1965-1972 by the Osservatorio Geofisico Sperimentale (OGS) while the ground measurements were performed within the framework of the Progetto Finalizzato Geodinamica of the Calling's Nazionale delle Ricerche (PFG-CNR) between 1977 and 1981. The new shaded relief magnetic anomaly map of total intensity of the Earth's magnetic field for Italy and the surrounding seas has been produced at sea level, for the geomagnetic epoch 1979.0. The most remarkable result of this new map, with respect to the previous compilations and to the aero magnetic map of Italy, is an unprecedented view of the magnetic signature of the major tectonic elements in their regional setting. There is good correlation between known structural geology and the magnetic anomalies, and now that the longer wavelength signatures have been corrected, deeper interpretations are possible

Crustal Magnetic Field Anomalies and Global Tectonics

Science.gov (United States)

Storetvedt, Karsten

2014-05-01

A wide variety of evidence suggests that the ruling isochron (geomagnetic polarity versus age) hypothesis of marine magnetic lineations has no merit - undermining therefore one of the central tenets of plate tectonics. Instead, variable induction by the ambient geomagnetic field is likely to be the principal agent for mega-scale crustal magnetic features - in both oceanic and continental settings. This revitalizes the fault-controlled susceptibility-contrast model of marine magnetic lineations, originally proposed in the late 1960s. Thus, the marine magnetic 'striping' may be ascribed to tectonic shearing and related, but variable, disintegration of the original iron-oxide mineralogy, having developed primarily along one of the two pan-global sets of orthogonal fractures and faults. In this way, fault zones (having the more advanced mineral alteration) would be characterized by relatively low susceptibility, while more moderately affected crustal sections (located between principal fault zones) would be likely to have less altered oxide mineralogy and therefore higher magnetic susceptibility. On this basis, induction by the present geomagnetic field is likely to produce oscillating magnetic field anomalies with axis along the principal shear grain. The modus operandi of the alternative magneto-tectonic interpretation is inertia-driven wrenching of the global Alpine age palaeo-lithosphere - triggered by changes in Earth's rotation. Increasing sub-crustal loss to the upper mantle during the Upper Mesozoic had left the ensuing Alpine Earth in a tectonically unstable state. Thus, sub-crustal eclogitization and associated gravity-driven delamination to the upper mantle led to a certain degree of planetary acceleration which in turn gave rise to latitude-dependent, westward inertial wrenching of the global palaeo-lithosphere. During this process, 1) the thin and mechanically fragile oceanic crust were deformed into a new type of broad fold belts, and 2) the continents

Shaded relief magnetic anomaly map of Italy and surrounding marine areas

Directory of Open Access Journals (Sweden)

C. Carmisciano

2000-06-01

Full Text Available Magnetic observations made onshore the Italian Peninsula, and across the adjacent seas, have been compiled in a new digital database that provides the first complete regional scale view of the crustal scale magnetic anomalies of the region at sea level. The offshore data were acquired between 1965-1972 by the Osservatorio Geofisico Sperimentale (OGS while the ground measurements were performed within the framework of the Progetto Finalizzato Geodinamica of the Consiglio Nazionale delle Ricerche (PFG-CNR between 1977 and 1981. The new shaded relief magnetic anomaly map of total intensity of the Earth's magnetic field for Italy and the surrounding seas has been produced at sea level, for the geomagnetic epoch 1979.0. The most remarkable result of this new map, with respect to the previous compilations and to the aeromagnetic map of Italy, is an unprecedented view of the magnetic signature of the major tectonic elements in their regional setting. There is good correlation between known structural geology and the magnetic anomalies, and now that the longer wavelength signatures have been corrected, deeper interpretations are possible.

Statistical averaging of marine magnetic anomalies and the aging of oceanic crust.

Science.gov (United States)

Blakely, R.J.

1983-01-01

Visual comparison of Mesozoic and Cenozoic magnetic anomalies in the North Pacific suggests that older anomalies contain less short-wavelength information than younger anomalies in this area. To test this observation, magnetic profiles from the North Pacific are examined from crust of three ages: 0-2.1, 29.3-33.1, and 64.9-70.3Ma. For each time period, at least nine profiles were analyzed by 1) calculating the power density spectrum of each profile, 2) averaging the spectra together, and 3) computing a 'recording filter' for each time period by assuming a hypothetical seafloor model. The model assumes that the top of the source is acoustic basement, the source thickness is 0.5km, and the time scale of geomagnetic reversals is according to Ness et al. (1980). The calculated power density spectra of the three recording filters are complex in shape but show an increase of attenuation of short-wavelength information as the crust ages. These results are interpreted using a multilayer model for marine magnetic anomalies in which the upper layer, corresponding to pillow basalt of seismic layer 2A, acts as a source of noise to the magnetic anomalies. As the ocean crust ages, this noisy contribution by the pillow basalts becomes less significant to the anomalies. Consequently, magnetic sources below layer 2A must be faithful recorders of geomagnetic reversals.-AuthorPacific power density spectrum

Small Satellite Passive Magnetic Attitude Control

Science.gov (United States)

Gerhardt, David T.

Passive Magnetic Attitude Control (PMAC) is capable of aligning a satellite within 5 degrees of the local magnetic field at low resource cost, making it ideal for a small satellite. However, simulation attempts to date have not been able to predict the attitude dynamics at a level sufficient for mission design. Also, some satellites have suffered from degraded performance due to an incomplete understanding of PMAC system design. This dissertation alleviates these issues by discussing the design, inputs, and validation of PMAC systems for small satellites. Design rules for a PMAC system are defined using the Colorado Student Space Weather Experiment (CSSWE) CubeSat as an example. A Multiplicative Extended Kalman Filter (MEKF) is defined for the attitude determination of a PMAC satellite without a rate gyro. After on-orbit calibration of the off-the-shelf magnetometer and photodiodes and an on-orbit fit to the satellite magnetic moment, the MEKF regularly achieves a three sigma attitude uncertainty of 4 degrees or less. CSSWE is found to settle to the magnetic field in seven days, verifying its attitude design requirement. A Helmholtz cage is constructed and used to characterize the CSSWE bar magnet and hysteresis rods both individually and in the flight configuration. Fitted parameters which govern the magnetic material behavior are used as input to a PMAC dynamics simulation. All components of this simulation are described and defined. Simulation-based dynamics analysis shows that certain initial conditions result in abnormally decreased settling times; these cases may be identified by their dynamic response. The simulation output is compared to the MEKF output; the true dynamics are well modeled and the predicted settling time is found to possess a 20 percent error, a significant improvement over prior simulation.

Magnetic resonance imaging of pediatric soft-tissue vascular anomalies

International Nuclear Information System (INIS)

Navarro, Oscar M.

2016-01-01

Magnetic resonance (MR) imaging can be used in the management of pediatric soft-tissue vascular anomalies for diagnosing and assessing extent of lesions and for evaluating response to therapy. MR imaging studies often involve a combination of T1- and T2-weighted images in addition to MR angiography and fat-suppressed post-contrast sequences. The MR imaging features of these vascular anomalies when combined with clinical findings can aid in diagnosis. In cases of complex vascular malformations and syndromes associated with vascular anomalies, MR imaging can be used to evaluate accompanying soft-tissue and bone anomalies. This article reviews the MR imaging protocols and appearances of the most common pediatric soft-tissue vascular anomalies. (orig.)

Orbital studies of lunar magnetism

Science.gov (United States)

Mcleod, M. G.; Coleman, P. J., Jr.

1982-01-01

Limitations of present lunar magnetic maps are considered. Optimal processing of satellite derived magnetic anomaly data is also considered. Studies of coastal and core geomagnetism are discussed. Lunar remanent and induced lunar magnetization are included.

Lithologic boundaries from gravity and magnetic anomalies over Proterozoic Dalma volcanics

Science.gov (United States)

Yadav, Pramod Kumar; Adhikari, P. K.; Srivastava, Shalivahan; Maurya, Ved P.; Tripathi, Anurag; Singh, Shailendra; Singh, Roshan K.; Bage, Ashish K.

2018-03-01

Dalma volcanics (DVs) has intruded the older Singhbhum Group of Metapelites. Despite DVs being rich in mineralisation, its boundaries are not clearly demarcated. Gravity and magnetic surveys have been attempted for mapping the boundaries in DVs. These surveys were made in the northern fringe of the DVs over an area of ˜ 0.70 km2 along 13 parallel lines at 50 m spacing. The data was acquired at ˜ 25 m spacing. The surveys were taken for determination of lithological boundaries, depths and nature of causative source using Euler depth solutions and radially averaged power spectrum (RAPS). Residual anomaly maps of gravity and magnetic intensity show the same trend as that of Bouguer gravity anomaly and total magnetic intensity anomaly map indicating towards shallow sources. The magnetic map in general follows the same pattern as that of gravity anomaly maps. The map shows coincident high gravity and magnetic anomalies. These anomalies together with resistivity signatures confirm that the northern fringe of DVs hosts volcanogenic massive sulphide settings. The Euler depth solution delineated the lateral boundaries and nature of the source. It seems that the source is of spherical nature lying within a depth range of 25-40 m. The obtained lithological (vertical) units from RAPS are between Lower DVs, Upper DVs and Singhbhum Group Metapelites at depths of ˜ 15, ˜ 25 and ˜ 40 m, respectively. The metallogeny is associated with the Upper DVs and the corresponding delineated lithological (vertical) unit is indicative of the top of the ore body. Good agreement is observed with the geological succession from the drilling data and resistivity data. The findings suggest that the northern fringe of DVs could be a preferred target for drilling.

Magnetic anomaly depth and structural index estimation using different height analytic signals data

Science.gov (United States)

Zhou, Shuai; Huang, Danian; Su, Chao

2016-09-01

This paper proposes a new semi-automatic inversion method for magnetic anomaly data interpretation that uses the combination of analytic signals of the anomaly at different heights to determine the depth and the structural index N of the sources. The new method utilizes analytic signals of the original anomaly at different height to effectively suppress the noise contained in the anomaly. Compared with the other high-order derivative calculation methods based on analytic signals, our method only computes first-order derivatives of the anomaly, which can be used to obtain more stable and accurate results. Tests on synthetic noise-free and noise-corrupted magnetic data indicate that the new method can estimate the depth and N efficiently. The technique is applied to a real measured magnetic anomaly in Southern Illinois caused by a known dike, and the result is in agreement with the drilling information and inversion results within acceptable calculation error.

Time series analysis of infrared satellite data for detecting thermal anomalies: a hybrid approach

Science.gov (United States)

Koeppen, W. C.; Pilger, E.; Wright, R.

2011-07-01

We developed and tested an automated algorithm that analyzes thermal infrared satellite time series data to detect and quantify the excess energy radiated from thermal anomalies such as active volcanoes. Our algorithm enhances the previously developed MODVOLC approach, a simple point operation, by adding a more complex time series component based on the methods of the Robust Satellite Techniques (RST) algorithm. Using test sites at Anatahan and Kīlauea volcanoes, the hybrid time series approach detected ~15% more thermal anomalies than MODVOLC with very few, if any, known false detections. We also tested gas flares in the Cantarell oil field in the Gulf of Mexico as an end-member scenario representing very persistent thermal anomalies. At Cantarell, the hybrid algorithm showed only a slight improvement, but it did identify flares that were undetected by MODVOLC. We estimate that at least 80 MODIS images for each calendar month are required to create good reference images necessary for the time series analysis of the hybrid algorithm. The improved performance of the new algorithm over MODVOLC will result in the detection of low temperature thermal anomalies that will be useful in improving our ability to document Earth's volcanic eruptions, as well as detecting low temperature thermal precursors to larger eruptions.

Correlation analysis between the occurrence of ionospheric scintillation at the magnetic equator and at the southern peak of the Equatorial Ionization Anomaly

Science.gov (United States)

de Lima, G. R. T.; Stephany, S.; de Paula, E. R.; Batista, I. S.; Abdu, M. A.; Rezende, L. F. C.; Aquino, M. G. S.; Dutra, A. P. S.

2014-06-01

Ionospheric scintillation refers to amplitude and phase fluctuations in radio signals due to electron density irregularities associated to structures named ionospheric plasma bubbles. The phenomenon is more pronounced around the magnetic equator where, after sunset, plasma bubbles of varying sizes and density depletions are generated by plasma instability mechanisms. The bubble depletions are aligned along Earth's magnetic field lines, and they develop vertically upward over the magnetic equator so that their extremities extend in latitude to north and south of the dip equator. Over Brazil, developing bubbles can extend to the southern peak of the Equatorial Ionization Anomaly, where high levels of ionospheric scintillation are common. Scintillation may seriously affect satellite navigation systems, such as the Global Navigation Satellite Systems. However, its effects may be mitigated by using a predictive model derived from a collection of extended databases on scintillation and its associated variables. This work proposes the use of a classification and regression decision tree to perform a study on the correlation between the occurrence of scintillation at the magnetic equator and that at the southern peak of the equatorial anomaly. Due to limited size of the original database, a novel resampling heuristic was applied to generate new training instances from the original ones in order to improve the accuracy of the decision tree. The correlation analysis presented in this work may serve as a starting point for the eventual development of a predictive model suitable for operational use.

Basement configuration of KG offshore basin from magnetic anomalies

Indian Academy of Sciences (India)

of charnockites of neighbouring EGMB and onshore K–G basin areas indicates that EGMB geology. (charnockites ... Marine magnetic anomalies; offshore K–G basin; magnetic basement; extension of EGMB geology; continent– oceanic boundary. ..... of India; J. Australian Petroleum Exploration Association. 14 29–41.

Linear magnetic anomalies and tectonic development of the middle Okinawa Trough

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

-By analyzing the magnetic anomalies, the linear magnetic anomalies in the middle Okinawa Trough are identified. It means that the crust along the spreading axis is broken, and new oceanic crust is formed. Geophysical data have revealed that a model of three extensive episodes occurs in the Okinawa Trough, which can be named as "doming episode" from the Middle to Late Miocene (Phase I), the episode from the Pliocence to Early Pleistocene (Phase Ⅱ ), and the recent "spreading episode" (Phase Ⅲ ). The magnetic anomalies in the middle Okinawa Trough are very similar to those found in the middle Red Sea, indicating that the Okinawa Trough is developing towards the "Red Sea stage". Similar to the Red Sea, there are a "main trough" and a "axial trough" in the Okinawa Trough.

Ionospheric midlatitude electric current density inferred from multiple magnetic satellites

DEFF Research Database (Denmark)

Shore, R. M.; Whaler, K. A.; Macmillan, S.

2013-01-01

A method for inferring zonal electric current density in the mid-to-low latitude F region ionosphere is presented. We describe a method of using near-simultaneous overflights of the Ørsted and CHAMP satellites to define a closed circuit for an application of Ampère's integral law to magnetic data...... for estimates of main and crustal magnetic fields. Current density in the range ±0.1 μA/m2 is resolved, with the distribution of electric current largely matching known features such as the Appleton anomaly. The currents appear unmodulated at times of either high-negative Dst or high F10.7, which has...... implications for any future efforts to model their effects. We resolve persistent current intensifications between geomagnetic latitudes of 30 and 50° in the postmidnight, predawn sector, a region typically thought to be relatively free of electric currents. The cause of these unexpected intensifications...

Least-squares Minimization Approaches to Interpret Total Magnetic Anomalies Due to Spheres

Science.gov (United States)

Abdelrahman, E. M.; El-Araby, T. M.; Soliman, K. S.; Essa, K. S.; Abo-Ezz, E. R.

2007-05-01

We have developed three different least-squares approaches to determine successively: the depth, magnetic angle, and amplitude coefficient of a buried sphere from a total magnetic anomaly. By defining the anomaly value at the origin and the nearest zero-anomaly distance from the origin on the profile, the problem of depth determination is transformed into the problem of finding a solution of a nonlinear equation of the form f(z)=0. Knowing the depth and applying the least-squares method, the magnetic angle and amplitude coefficient are determined using two simple linear equations. In this way, the depth, magnetic angle, and amplitude coefficient are determined individually from all observed total magnetic data. The method is applied to synthetic examples with and without random errors and tested on a field example from Senegal, West Africa. In all cases, the depth solutions are in good agreement with the actual ones.

Role of magnetic resonance urography in pediatric renal fusion anomalies

International Nuclear Information System (INIS)

Chan, Sherwin S.; Ntoulia, Aikaterini; Khrichenko, Dmitry; Back, Susan J.; Darge, Kassa; Tasian, Gregory E.; Dillman, Jonathan R.

2017-01-01

Renal fusion is on a spectrum of congenital abnormalities that occur due to disruption of the migration process of the embryonic kidneys from the pelvis to the retroperitoneal renal fossae. Clinically, renal fusion anomalies are often found incidentally and associated with increased risk for complications, such as urinary tract obstruction, infection and urolithiasis. These anomalies are most commonly imaged using ultrasound for anatomical definition and less frequently using renal scintigraphy to quantify differential renal function and assess urinary tract drainage. Functional magnetic resonance urography (fMRU) is an advanced imaging technique that combines the excellent soft-tissue contrast of conventional magnetic resonance (MR) images with the quantitative assessment based on contrast medium uptake and excretion kinetics to provide information on renal function and drainage. fMRU has been shown to be clinically useful in evaluating a number of urological conditions. A highly sensitive and radiation-free imaging modality, fMRU can provide detailed morphological and functional information that can facilitate conservative and/or surgical management of children with renal fusion anomalies. This paper reviews the embryological basis of the different types of renal fusion anomalies, their imaging appearances at fMRU, complications associated with fusion anomalies, and the important role of fMRU in diagnosing and managing children with these anomalies. (orig.)

Role of magnetic resonance urography in pediatric renal fusion anomalies

Energy Technology Data Exchange (ETDEWEB)

Chan, Sherwin S. [Children' s Mercy Hospital, Department of Radiology, Kansas City, MO (United States); Ntoulia, Aikaterini; Khrichenko, Dmitry [The Children' s Hospital of Philadelphia, Division of Body Imaging, Department of Radiology, Philadelphia, PA (United States); Back, Susan J.; Darge, Kassa [The Children' s Hospital of Philadelphia, Division of Body Imaging, Department of Radiology, Philadelphia, PA (United States); University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA (United States); Tasian, Gregory E. [University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA (United States); The Children' s Hospital of Philadelphia, Division of Urology, Department of Surgery, Philadelphia, PA (United States); Dillman, Jonathan R. [Cincinnati Children' s Hospital Medical Center, Division of Thoracoabdominal Imaging, Department of Radiology, Cincinnati, OH (United States)

2017-12-15

Renal fusion is on a spectrum of congenital abnormalities that occur due to disruption of the migration process of the embryonic kidneys from the pelvis to the retroperitoneal renal fossae. Clinically, renal fusion anomalies are often found incidentally and associated with increased risk for complications, such as urinary tract obstruction, infection and urolithiasis. These anomalies are most commonly imaged using ultrasound for anatomical definition and less frequently using renal scintigraphy to quantify differential renal function and assess urinary tract drainage. Functional magnetic resonance urography (fMRU) is an advanced imaging technique that combines the excellent soft-tissue contrast of conventional magnetic resonance (MR) images with the quantitative assessment based on contrast medium uptake and excretion kinetics to provide information on renal function and drainage. fMRU has been shown to be clinically useful in evaluating a number of urological conditions. A highly sensitive and radiation-free imaging modality, fMRU can provide detailed morphological and functional information that can facilitate conservative and/or surgical management of children with renal fusion anomalies. This paper reviews the embryological basis of the different types of renal fusion anomalies, their imaging appearances at fMRU, complications associated with fusion anomalies, and the important role of fMRU in diagnosing and managing children with these anomalies. (orig.)

Space weather and space anomalies

Directory of Open Access Journals (Sweden)

L. I. Dorman

2005-11-01

Full Text Available A large database of anomalies, registered by 220 satellites in different orbits over the period 1971-1994 has been compiled. For the first time, data from 49 Russian Kosmos satellites have been included in a statistical analysis. The database also contains a large set of daily and hourly space weather parameters. A series of statistical analyses made it possible to quantify, for different satellite orbits, space weather conditions on the days characterized by anomaly occurrences. In particular, very intense fluxes (>1000 pfu at energy >10 MeV of solar protons are linked to anomalies registered by satellites in high-altitude (>15000 km, near-polar (inclination >55° orbits typical for navigation satellites, such as those used in the GPS network, NAVSTAR, etc. (the rate of anomalies increases by a factor ~20, and to a much smaller extent to anomalies in geostationary orbits, (they increase by a factor ~4. Direct and indirect connections between anomaly occurrence and geomagnetic perturbations are also discussed.

Multi-satellite observations of magnetic fields in space plasmas

International Nuclear Information System (INIS)

Potemra, T.A.; Zanetti, L.J.; Bythrow, P.F.; Erlandson, R.E.

1987-01-01

The most common method of detecting electric currents in space has been by virtue of the magnetic perturbations they produce. A satellite can pass through a field-aligned ''Birkeland'' current and measure the in-situ magnetic perturbations. Satellite-borne magnetic field experiments may also be used to observe characteristics of resonant oscillations of the Earth's magnetic field at ULF frequencies. Examples of such measurements with magnetic field experiments on the Viking, AMPTE/CCE, and DMSP-F7 satellites will be presented. The Viking satellite, launched in February, 1986, is Sweden's first satellite and is in a polar orbit with 3.1 R/sub e/ apogee. AMPTE/CCE was launched in August, 1984, with satellites from West Germany and the United Kingdom, for the purpose of creating artificial comets in space. It is in an equatorial orbit with a 8.8 R/sub e/ apogee. The Defense Meteorological Satellite Program (DMSP)-F7 satellite was launched in October, 1983 into an 800 km circular sun-synchronous orbit in the 0830-2030 magnetic local time plane. Viking and AMPTE/CCE observed harmonic ULF pulsations when they were near the same flux tube, but separated by about 10 R/sub e/. These unique observations are used to investigate the characteristics and sources of multiple field line resonances of Alfven waves. On another occasion, Viking and DMSP-F7 observed similar magnetic perturbations at widely separated locations. The authors interpret these perturbations as due to a complicated system of large-scale stable Birkeland currents in the morning sector. This multi-satellite data set is in the early stages of exploration, but already confirms the usefulness of coordinated multi-position observations of magnetic fields in space

Gravity and magnetic anomaly modeling and correlation using the SPHERE program and Magsat data

Science.gov (United States)

Braile, L. W.; Hinze, W. J. (Principal Investigator); Vonfrese, R. R. B.

1980-01-01

The spherical Earth inversion, modeling, and contouring software were tested and modified for processing data in the Southern Hemisphere. Preliminary geologic/tectonic maps and selected cross sections for South and Central America and the Caribbean region are being compiled and as well as gravity and magnetic models for the major geological features of the area. A preliminary gravity model of the Andeas Beniff Zone was constructed so that the density columns east and west of the subducted plates are in approximate isostatic equilibrium. The magnetic anomaly for the corresponding magnetic model of the zone is being computed with the SPHERE program. A test tape containing global magnetic measurements was converted to a tape compatible with Purdue's CDC system. NOO data were screened for periods of high diurnal activity and reduced to anomaly form using the IGS-75 model. Magnetic intensity anomaly profiles were plotted on the conterminous U.S. map using the track lines as the anomaly base level. The transcontinental magnetic high seen in POGO and MAGSAT data is also represented in the NOO data.

Understanding the Tectonic Features in the South China Sea By Analyzing Magnetic Anomalies

Science.gov (United States)

Guo, L.; Meng, X.; Shi, L.; Yao, C.

2011-12-01

The South China Sea (SCS) is surrounded by the Eurasia, Pacific and India-Australia plates. It formed during Late Oligocene-Early Miocene, and is one of the largest marginal seas in the Western Pacific. The collision of Indian subcontinent and Eurasian plate in the northwest, back-arc spreading in the centre and subduction beneath the Philippine plate along Manila trench in the east and along Palawan trough in the south had produced the complex tectonic features in the SCS that we can see today. In the past few decades, a variety of geophysical methods were conducted to study geological tectonics and evolution of the SCS. Here, we analyzed the magnetic data of this area using new data enhancement techniques to understand the regional tectonic features. We assembled the magnetic anomalies data with a resolution of two arc-minute from the World Digital Magnetic Anomaly Map, and then gridded the data on a regular grid. Then we used the method of reduction to the pole at low latitude with varying magnetic inclinations to stably reduce the magnetic anomalies. Then we used the preferential continuation method based on Wiener filtering and Green's equivalence principle to separate the reduced-to-pole (RTP) magnetic anomalies, and subsequently analyze the regional and residual anomalies. We also calculated the directional horizontal derivatives and the tilt-angle derivative of the data to derive clearer geological structures with more details. Then we calculated the depth of the magnetic basement surface in the area by 3D interface inversion. From the results of the preliminary processing, we analyzed the main faults, geological structures, magma distribution and tectonic features in the SCS. In the future, the integrated interpretation of the RTP magnetic anomalies, Bouguer gravity anomalies and other geophysical methods will be performed for better understanding the deep structure , the tectonic features and evolution of the South China Sea. Acknowledgment: We

Influence of space radiation on satellite magnetics

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, M K [Vikram Sarabhai Space Centre, Trivandrum (India)

1978-12-01

The magnetic circuits and devices used in space-borne systems such as satellites are naturally exposed to space environments having among others, hazardous radiations. Such radiations, in turn, may be of solar, cosmic or nuclear origin depending upon the altitude as well as the propulsion/power systems involving mini atomic reactors when utilised. The influence of such radiations on the magnetic components of the satellite have been analysed revealing the critical hazards in the latter circuits system. Remedial measures by appropriate shielding, etc. necessary for maintaining optimum performance of the satellite have been discussed.

High magnetic susceptibility granodiorite as a source of surface magnetic anomalies in the King George Island, Antarctica

Science.gov (United States)

Kon, S.; Nakamura, N.; Funaki, M.; Sakanaka, S.

2012-12-01

Change in plate motion produces convergence of the two oceanic lithospheres and the formation of volcanic island arcs above the subducted older and thicker plate. The association of calc-alkaline diorites to tonalites and granodiorites (ACG) is typical plutonic rocks of the volcanic arcs. In the many island arcs that surround the Pacific Ocean, ACG generally forms shallow level plutons and is closely associated with volcanic rocks. The Japan Arc setting had occurred the emplacement of the highly magnetic granitoid along the fore-arc basin before back-arc spreading at middle Miocene, showing a linear positive magnetic anomaly. Similar magnetic anomalies have also been exhibited along the Circum-Pacific Belt. Along East Antarctica, it is well known that the South Shetland Islands have been formed by back-arc spreading related to the subduction along the South Shetland trench during the late Cretaceous and middle Miocene. Moreover, geology in the South Shetland Islands consists of lava flows with subordinate pyroclastic deposits, intrusive dykes-sills, granitic plutons, displaying a typical subduction-related calc-alkaline volcanic association. However, there is little report on the presence of fore-arc granitoid. Here we report the distribution and structure of the granitic plutons around Marian Cove in the King George Island, South Shetland, East Antarctica by surface geological survey and magnetic anisotropic studies. Then we compare the distribution of granitic plutons with surface magnetic anomalies through our ship-borne and foot-borne magnetic surveys. The granitic plutons are distributed only shallow around the Marian cove in the King George Island, and the plutons had been intruded in the Sejong formation with pyroclastic deposits and basaltic/rhyoritic lavas, suggesting the post back-arc spreading. We sampled 8 plutons, 12 basaltic lavas and 6 andestic dykes, all located within four kilometer radius from the Korean Antarctic research station (King Sejong

Characterization of CHAMP magnetic data anomalies: magnetic contamination and measurement timing

International Nuclear Information System (INIS)

Yin, Fan; Cai, Hongtao; Lühr, Hermann; Rauberg, Jan; Michaelis, Ingo

2013-01-01

The CHAMP (CHAllenging Minisatellite Payload) mission ended after more than ten years in space on 19 September 2010. For achieving a high measurement accuracy of the magnetometers on CHAMP, detailed analyses of spacecraft magnetic characteristics in orbit are required. A decade of continuous magnetometer and housekeeping data are a good basis for evaluating some of the effects of variable spacecraft magnetic fields on the ambient field determination. It was found that some perturbations of FGM (FluxGate vector Magnetometer) or OVM (OVerhauser scalar Magnetometer) measurements are caused by stray fields induced by the power system, the ASC (advanced stellar compass) instrument or magneto-torquer currents. The magnetic effect of solar currents on FGM measurements varies with the local time of the orbit and amounts to 0.2 nT. In cases when one head of the ASC instrument was blinded by the sun, sometimes transient drops in instrument current strength occur, which were accompanied by magnetic disturbance signals (∼0.3 nT) in FGM measurements. The magnetic residual contamination of OVM data by the torquer currents was of order 0.1 nT but still detectable. An improved torquer correction matrix is derived which eliminates this effect. In-flight scalar calibration parameters revealed some of the effects of timing anomalies. Time lags between FGM and OVM readings are misinterpreted by the scalar calibration as variations of the angles between some of the sensor axes. The resulting amplitudes of the anomalies presented here lie in the range of some 0.1 nT, but they are systematic in nature. (paper)

Satellite measurements of the earth's crustal magnetic field

Science.gov (United States)

Schnetzler, C. C.

1989-01-01

The literature associated with the Magsat mission has evaluated the capabilities and limitations of satellite measurements of the earth's crustal magnetic field, and demonstrated that there exists a 300-3000 km magnetic field, related to major features in the earth's crust, which is primarily caused by induction. Due to its scale and sensitivity, satellite data have been useful in the development of models for such large crustal features as subduction zones, submarine platforms, continental accretion boundaries, and rifts. Attention is presently given to the lack of agreement between laboratory and satellite estimates of lower crustal magnetization.

Magnetic resonance imaging of head and neck vascular anomalies ...

African Journals Online (AJOL)

Magnetic resonance imaging of head and neck vascular anomalies: pearls and pitfalls. Shaimaa Abdelsattar Mohammad, Amr Abdelhamid Abou Zeid, Ahmed M. Fawzi, Mohamed M. Dahab, Iman A. Ragab, Osama El-Naggar ...

The last frontier? High-resolution, near-bottom measurements of the Hawaiian Jurassic magnetic anomaly sequence

Science.gov (United States)

Tivey, M.; Tominaga, M.; Sager, W. W.

2012-12-01

The Jurassic sequence of marine magnetic anomalies i.e. older than M29 remain the last part of the marine magnetic anomaly sequence of the geomagnetic polarity timescale (GPTS) that can be gleaned from the ocean crustal record. While Jurassic crust is present in several areas of the world's ocean basins, the oldest and arguably best preserved sequence is in the western Pacific where three lineations sets (Japanese, Hawaiian and Phoenix) converge on the oldest remaining ocean crust on the planet (i.e. crust that has not been subducted). The magnetic anomalies in these 3 lineation sets are marked by low amplitude, relatively indistinct anomalies (tiny wiggles) that collectively have been called the Jurassic quiet Zone (JQZ). Over the past 20 years we have been working on resolving the character and origin of these anomalies with various technologies to improve our resolution of this period. Following an aeromagnetic survey that revealed the possible presence of lineated anomalies older than M29 in the Japanese lineations, we conducted a deeptow magnetometer survey of the Japanese sequence in 1992. In 2002/03 we extended and confirmed this deeptow record with a deeptowed sidescan and magnetometer survey of the Japanese lineation sequence by tying in ODP Hole 801C and extending the anomaly sequence between M29 and M44. These surveys reveal remarkably fast reversals that are lineated and decrease in intensity back in time until M38, prior to which the sequence becomes somewhat confused (the LAZ or low amplitude zone) before recovering in both amplitude and lineated character around Hole 801C (M42). These results are partially supported by recently reported terrestrial magnetostratigraphy records that show the existence of reversals back to M38. A Jurassic GPTS was constructed from this Japanese anomaly sequence, but the overall global significance of the reversal sequence and systematic field intensity changes require confirmation from crustal records created at

Advances in analysis of pre-earthquake thermal anomalies by analyzing IR satellite data

Science.gov (United States)

Ouzounov, D.; Bryant, N.; Filizzola, C.; Pergola, N.; Taylor, P.; Tramutoli, V.

Presented work addresses the possible relationship between tectonic stress, electro-chemical and thermodynamic processes in the atmosphere and increasing infrared (IR) flux as part of a larger family of electromagnetic (EM) phenomena related to earthquake activity. Thermal infra-red (TIR) surveys performed by polar orbiting (NOAA/AVHRR, MODIS) and geosynchronous weather satellites (GOES, METEOSAT) seems to indicate the appearance (from days to weeks before the event) of "anomalous" space-time TIR transients associated with the place (epicentral area, linear structures and fault systems) and the time of occurrence of a number of major earthquakes with M>5 and focal depths no deeper than 50km. As Earth emitted in 8-14 microns range the TIR signal measured from satellite strongly vary depending on meteorological conditions and other factors (space-time changes in atmospheric transmittance, time/season, solar and satellite zenithal angles and etc) independent from seismic activity, a preliminary definition of "anomalous TIR signal" should be given. To provide reliable discrimination of thermal anomalous area from the natural events (seasonal changes, local morphology) new robust approach (RAT) has been recently proposed (and successfully applied in the field of the monitoring of the major environmental risks) that permits to give a statistically based definition of thermal info-red (TIR) anomaly and reduce of false events detection. New techniques also were specifically developed to assure the precise co-registration of all satellite scenes and permit accurate time-series analysis of satellite observations. As final results we present examples of most recent 2000/2004 worldwide strong earthquakes and the techniques used to capture the tracks of thermal emission mid-IR anomalies and methodology for practical future use of such phenomena in the early warning systems.

Apparatus and method for detecting a magnetic anomaly contiguous to remote location by SQUID gradiometer and magnetometer systems

Science.gov (United States)

Overton, W.C. Jr.; Steyert, W.A. Jr.

1981-05-22

A superconducting quantum interference device (SQUID) magnetic detection apparatus detects magnetic fields, signals, and anomalies at remote locations. Two remotely rotatable SQUID gradiometers may be housed in a cryogenic environment to search for and locate unambiguously magnetic anomalies. The SQUID magnetic detection apparatus can be used to determine the azimuth of a hydrofracture by first flooding the hydrofracture with a ferrofluid to create an artificial magnetic anomaly therein.

General expression for spectrum of magnetic anomaly due to long tabular body and its characteristics

Digital Repository Service at National Institute of Oceanography (India)

Mishra, D.C.; Murthy, K.S.R.; Rao, T.C.S.

A general expression for spectrum of magnetic anomalies-vertical, horizontal and total intensity - due to a long tabular body is derived which is used to estimate the body parameters. The analysis is extended to a marine magnetic anomaly recorded...

The relation between anomalous magnetic moment and axial anomaly

International Nuclear Information System (INIS)

Teryaev, O.V.

1990-12-01

The conservation of total angular momentum of spinor particle leads to a simple relation between the famous Schwinger and Adler coefficients determining axial anomaly and anomalous magnetic moment, respectively. (author). 8 refs, 1 fig

Lithologic boundaries from gravity and magnetic anomalies over ...

Indian Academy of Sciences (India)

67

The data was acquired at ~25 m spacing. The surveys were taken for determination of lithological boundaries, depths and nature of causative source using Euler depth solutions and radially averaged power spectrum (RAPS). Residual anomaly maps of gravity and magnetic. Manuscript. Click here to view linked References.

Structural modeling of the Vichada impact structure from interpreted ground gravity and magnetic anomalies

International Nuclear Information System (INIS)

Hernandez, Orlando; Khurama, Sait; Alexander, Gretta C

2011-01-01

A prominent positive free-air gravity anomaly mapped over a roughly 50-km diameter basin is consistent with a mascon centered on (4 degrades 30 minutes N, 69 degrades 15 minutes W) in the Vichada Department, Colombia, South America. Ground follow up gravity and magnetic anomalies were modeled confirming the regional free air gravity anomalies. These potential field anomalies infer a hidden complex impact basin structure filled with tertiary sedimentary rocks and recent quaternary deposits. Negative Bouguer anomalies of 8 mgals to 15 mgals amplitude are associated with a concentric sedimentary basin with a varying thickness from 100 m to 500 m in the outer rings to 700 m to 1000 m at the center of the impact crater basin. Strong positive magnetic anomalies of 100 nt to 300 nt amplitude infer the presence of a local Precambrian crystalline basement that was affected by intensive faulting producing tectonic blocks dipping to the center of the structure, showing a typical domino structure of impact craters such as that of Sudbury, Ontario, Canada. Basic to intermediate mineralized veins and dikes with contrasting density and magnetic susceptibility properties could be emplaced along these faulting zones, as inferred from local gravity and magnetic highs. The geologic mapping of the area is limited by the flat topography and absence of outcrops/ geomorphologic units. Nevertheless, local normal faults along the inner ring together with radially sparse irregular blocks over flat terrains can be associated with terraced rims or collapse of the inner crater structure and eject blanket, respectively. A detailed airborne electromagnetic survey is recommended to confirm the gravity and magnetic anomalies together with a seismic program to evaluate the economic implications for energy and mineral exploration of the Vichada impact structure.

Magnetic anomalies of offshore Krishna–Godavari basin, eastern continental margin of India

Digital Repository Service at National Institute of Oceanography (India)

Swamy, K.V.; Murthy, I.V.R.; Krishna, K.S.; Murthy, K.S.R.; Subrahmanyam, A.S.; Rao, M.M.M.

with the volcanic material. Inversion of the magnetic and gravity anomalies was also carried out to establish the similarity of anomalies of the two geological features (structural high on the margin and the 85 degrees E Ridge) and their interpretations. In both...

Influence of calculation error of total field anomaly in strongly magnetic environments

Science.gov (United States)

Yuan, Xiaoyu; Yao, Changli; Zheng, Yuanman; Li, Zelin

2016-04-01

An assumption made in many magnetic interpretation techniques is that ΔTact (total field anomaly - the measurement given by total field magnetometers, after we remove the main geomagnetic field, T0) can be approximated mathematically by ΔTpro (the projection of anomalous field vector in the direction of the earth's normal field). In order to meet the demand for high-precision processing of magnetic prospecting, the approximate error E between ΔTact and ΔTpro is studied in this research. Generally speaking, the error E is extremely small when anomalies not greater than about 0.2T0. However, the errorE may be large in highly magnetic environments. This leads to significant effects on subsequent quantitative inference. Therefore, we investigate the error E through numerical experiments of high-susceptibility bodies. A systematic error analysis was made by using a 2-D elliptic cylinder model. Error analysis show that the magnitude of ΔTact is usually larger than that of ΔTpro. This imply that a theoretical anomaly computed without accounting for the error E overestimate the anomaly associated with the body. It is demonstrated through numerical experiments that the error E is obvious and should not be ignored. It is also shown that the curves of ΔTpro and the error E had a certain symmetry when the directions of magnetization and geomagnetic field changed. To be more specific, the Emax (the maximum of the error E) appeared above the center of the magnetic body when the magnetic parameters are determined. Some other characteristics about the error Eare discovered. For instance, the curve of Emax with respect to the latitude was symmetrical on both sides of magnetic equator, and the extremum of the Emax can always be found in the mid-latitudes, and so on. It is also demonstrated that the error Ehas great influence on magnetic processing transformation and inversion results. It is conclude that when the bodies have highly magnetic susceptibilities, the error E can

Amplitude inversion of the 2D analytic signal of magnetic anomalies through the differential evolution algorithm

Science.gov (United States)

Ekinci, Yunus Levent; Özyalın, Şenol; Sındırgı, Petek; Balkaya, Çağlayan; Göktürkler, Gökhan

2017-12-01

In this work, analytic signal amplitude (ASA) inversion of total field magnetic anomalies has been achieved by differential evolution (DE) which is a population-based evolutionary metaheuristic algorithm. Using an elitist strategy, the applicability and effectiveness of the proposed inversion algorithm have been evaluated through the anomalies due to both hypothetical model bodies and real isolated geological structures. Some parameter tuning studies relying mainly on choosing the optimum control parameters of the algorithm have also been performed to enhance the performance of the proposed metaheuristic. Since ASAs of magnetic anomalies are independent of both ambient field direction and the direction of magnetization of the causative sources in a two-dimensional (2D) case, inversions of synthetic noise-free and noisy single model anomalies have produced satisfactory solutions showing the practical applicability of the algorithm. Moreover, hypothetical studies using multiple model bodies have clearly showed that the DE algorithm is able to cope with complicated anomalies and some interferences from neighbouring sources. The proposed algorithm has then been used to invert small- (120 m) and large-scale (40 km) magnetic profile anomalies of an iron deposit (Kesikköprü-Bala, Turkey) and a deep-seated magnetized structure (Sea of Marmara, Turkey), respectively to determine depths, geometries and exact origins of the source bodies. Inversion studies have yielded geologically reasonable solutions which are also in good accordance with the results of normalized full gradient and Euler deconvolution techniques. Thus, we propose the use of DE not only for the amplitude inversion of 2D analytical signals of magnetic profile anomalies having induced or remanent magnetization effects but also the low-dimensional data inversions in geophysics. A part of this paper was presented as an abstract at the 2nd International Conference on Civil and Environmental Engineering, 8

Static and dynamical anomalies caused by chiral soliton lattice in molecular-based chiral magnets

International Nuclear Information System (INIS)

Kishine, Jun-ichiro; Inoue, Katsuya; Kikuchi, Koichi

2007-01-01

Interplay of crystallographic chirality and magnetic chirality has been of great interest in both chemist's and physicist's viewpoints. Crystals belonging to chiral space groups are eligible to stabilize macroscopic chiral magnetic order. This class of magnetic order is described by the chiral XY model, where the transverse magnetic field perpendicular to the chiral axis causes the chiral soliton lattice (CSL) formation. As a clear evidence of the chiral magnetic order, the temperature dependence of the transverse magnetization exhibits sharp cusp just below the mean field ferrimagnetic transition temperature, indicating the formation of the CSL. In addition to the static anomaly, we expect the CSL formation also causes dynamical anomalies such as induction of the spin supercurrent

Magnetic anomaly patterns over crustal blocks of the King Edward VII Peninsula, Marie Byrd Land, West Antarctica

Directory of Open Access Journals (Sweden)

M. Spano

2000-06-01

Full Text Available Within the framework of the GITARA II project an aeromagnetic survey was performed during the GANOVEXVII expedition (1992/1993 over the King Edward VII Peninsula in northwestern Marie Byrd Land (West Antarctica. This region which may represent the eastern flank of the Ross Sea rift system had previously been explored only at reconnaissance level. New total field and upward continued (10 km magnetic anomaly maps are produced and interpreted here to map and discuss the crustal structure of the Edward VII Peninsula. Tworound-shaped, high-amplitude magnetic anomalies are recognised over the Alexandra Mountains block. The anomalies are difficult to interpret since susceptibility data indicate the prevalence of non-magnetic rocks at the surface. A possible interpretation is that the anomalies are due to Cretaceous mafic intrusives distinct from weakly magnetic Byrd Coast Granite of the adjacent Rockefeller Mountains block. Alternatively the anomalies could be related to buried pluton-sized Devonian Ford Granodiorite intruded by dikes. If Cretaceous in age, the former intrusives revealed from the magnetics could also be responsible for contact metamorphism of the adjacent Alexandra Mountains migmatites. Lower amplitude circular anomalies over the Central Plateau and Prestrud Inlet are likely to be caused by unexposed Devonian Ford Granodiorite which crops out in the Ford Ranges. Elongated high-frequency anomalies of the Sulzberger Bay are similar to those recognised over seismically constrained Cenozoic rift-related volcanics of the Ross Sea. A broad magnetic low over the Sulzberger Ice Shelf may be indicative of a fault bounded graben-like basin with sedimentary infill. Overall recognition of magnetic anomaly patterns and trends reveals segmentation of the Edward VII Peninsula and of the adjacent marine areas in distinct crustal blocks. Faults may separate these blocks and they are interpreted to reflect multiple Cretaceous and maybe Cenozoic crustal

First high-resolution near-seafloor survey of magnetic anomalies of the South China Sea

Science.gov (United States)

Lin, J.; Xu, X.; Li, C.; Sun, Z.; Zhu, J.; Zhou, Z.; Qiu, N.

2013-12-01

We successfully conducted the first high-resolution near-seafloor magnetic survey of the Central, Southwest, and Northern Central Basins of the South China Sea (SCS) during two cruises on board Chinese R/V HaiYangLiuHao in October-November 2012 and March-April 2013, respectively. Measurements of magnetic field were made along four long survey lines, including (1) a NW-SE across-isochron profile transecting the Southwest Basin and covering all ages of the oceanic crust (Line CD); (2) a N-S across-isochron profile transecting the Central Basin (Line AB); and (3) two sub-parallel NE-SW across-isochron profiles transecting the Northern Central Basin of the SCS (Lines D and E). A three-axis magnetometer was mounted on a deep-tow vehicle, flying within 0.6 km above the seafloor. The position of the tow vehicle was provided by an ultra-short baseline navigation system along Lines D and E, while was estimated using shipboard GPS along Lines AB and CD. To investigate crustal magnetization, we first removed the International Geomagnetic Reference Field (IGRF) of 2010 from the measured magnetic data, and then downward continued the resultant magnetic field data to a horizontal plane at a water depth of 4.5 km to correct for variation due to the fishing depth of the deep-tow vehicle. Finally, we calculated magnetic anomalies at various water depths after reduction-to-the-pole corrections. We also constructed polarity reversal block (PRB) models of crustal magnetization by matching peaks and troughs of the observed magnetic field anomaly. Our analysis yielded the following results: (1) The near-bottom magnetic anomaly showed peak-to-trough amplitudes of more than 2,500 nT, which are several times of the anomaly amplitudes at the sea surface, illustrating that deep-tow measurements acquired much higher spatial resolutions. (2) The deep-tow data revealed several distinctive magnetic anomalies with wavelengths of 5-15 km and amplitudes of several hundred nT. These short

Mapping the earth's magnetic and gravity fields from space Current status and future prospects

Science.gov (United States)

Settle, M.; Taranik, J. V.

1983-01-01

The principal magnetic fields encountered by earth orbiting spacecraft include the main (core) field, external fields produced by electrical currents within the ionosphere and magnetosphere, and the crustal (anomaly) field generated by variations in the magnetization of the outermost portions of the earth. The first orbital field measurements which proved to be of use for global studies of crustal magnetization were obtained by a series of three satellites launched and operated from 1965 to 1971. Each of the satellites, known as a Polar Orbiting Geophysical Observatory (POGO), carried a rubidium vapor magnetometer. Attention is also given to Magsat launched in 1979, the scalar anomaly field derived from the Magsat measurements, satellite tracking studies in connection with gravity field surveys, radar altimetry, the belt of positive free air gravity anomalies situated along the edge of the Pacific Ocean basin, future technological capabilities, and information concerning data availability.

Magnetic anomalies across Bastar craton and Pranhita–Godavari ...

Indian Academy of Sciences (India)

Such intrusions can be explained considering the collision of the Bastar and Dharwar cratons by the ... that there was no imprint of magnetization of a later date, it is concluded that the Indian plate was located in the .... swarms, that occur in this craton. Thus the .... b, c and d, needed to explain the anomalies along with the ...

Measurement of the terrestrial magnetic field and its anomalies

International Nuclear Information System (INIS)

Duret, D.

1994-01-01

After a presentation of the terrestrial magnetic field and its various anomalies, the different types of magnetometers commonly used are reviewed with their characteristics and performances: scalar magnetometers (free precession and continuous polarization proton magnetometers, dynamic polarization proton magnetometers, optical pumping magnetometers, electronic resonance scalar magnetometers (without pumping)); vectorial magnetometers (flux gate magnetometers, induction magnetometers, suspended magnet magnetometers, superconducting magnetometers, integrated magnetometers, resonance directional magnetometers). The magnetometry market and applications are discussed. 20 figs., 9 tabs., 72 refs

A comparative study of spherical and flat-Earth geopotential modeling at satellite elevations

Science.gov (United States)

Parrott, M. H.; Hinze, W. J.; Braile, L. W.; Vonfrese, R. R. B.

1985-01-01

Flat-Earth modeling is a desirable alternative to the complex spherical-Earth modeling process. These methods were compared using 2 1/2 dimensional flat-earth and spherical modeling to compute gravity and scalar magnetic anomalies along profiles perpendicular to the strike of variably dimensioned rectangular prisms at altitudes of 150, 300, and 450 km. Comparison was achieved with percent error computations (spherical-flat/spherical) at critical anomaly points. At the peak gravity anomaly value, errors are less than + or - 5% for all prisms. At 1/2 and 1/10 of the peak, errors are generally less than 10% and 40% respectively, increasing to these values with longer and wider prisms at higher altitudes. For magnetics, the errors at critical anomaly points are less than -10% for all prisms, attaining these magnitudes with longer and wider prisms at higher altitudes. In general, in both gravity and magnetic modeling, errors increase greatly for prisms wider than 500 km, although gravity modeling is more sensitive than magnetic modeling to spherical-Earth effects. Preliminary modeling of both satellite gravity and magnetic anomalies using flat-Earth assumptions is justified considering the errors caused by uncertainties in isolating anomalies.

Multi precursors analysis associated with the powerful Ecuador (MW = 7.8) earthquake of 16 April 2016 using Swarm satellites data in conjunction with other multi-platform satellite and ground data

Science.gov (United States)

Akhoondzadeh, Mehdi; De Santis, Angelo; Marchetti, Dedalo; Piscini, Alessandro; Cianchini, Gianfranco

2018-01-01

After DEMETER satellite mission (2004-2010), the launch of the Swarm satellites (Alpha (A), Bravo (B) and Charlie (C)) has created a new opportunity in the study of earthquake ionospheric precursors. Nowadays, there is no doubt that multi precursors analysis is a necessary phase to better understand the LAIC (Lithosphere Atmosphere Ionosphere Coupling) mechanism before large earthquakes. In this study, using absolute scalar magnetometer, vector field magnetometer and electric field instrument on board Swarm satellites, GPS (Global Positioning System) measurements, MODIS-Aqua satellite and ECMWF (European Centre for Medium-Range Weather Forecasts) data, the variations of the electron density and temperature, magnetic field, TEC (Total Electron Content), LST (Land Surface Temperature), AOD (Aerosol Optical Depth) and SKT (SKin Temperature) have been surveyed to find the potential seismic anomalies around the strong Ecuador (Mw = 7.8) earthquake of 16 April 2016. The four solar and geomagnetic indices: F10.7, Dst, Kp and ap were investigated to distinguish whether the preliminary detected anomalies might be associated with the solar-geomagnetic activities instead of the seismo-ionospheric anomalies. The Swarm satellites (A, B and C) data analysis indicate the anomalies in time series of electron density variations on 7, 11 and 12 days before the event; the unusual variations in time series of electron temperature on 8 days preceding the earthquake; the analysis of the magnetic field scalar and vectors data show the considerable anomalies 52, 48, 23, 16, 11, 9 and 7 days before the main shock. A striking anomaly is detected in TEC variations on 1 day before earthquake at 9:00 UTC. The analysis of MODIS-Aqua night-time images shows that LST increase unusually on 11 days prior to main shock. In addition, the AOD variations obtained from MODIS measurements reach the maximum value on 10 days before the earthquake. The SKT around epicentral region presents anomalous higher

Delineation of structural lineaments from marine magnetic anomalies off Lawson's Bay (Visakhapatnam), East Coast of India

Digital Repository Service at National Institute of Oceanography (India)

Murthy, K.S.R.; Rao, T.C.S.; Rao, M.M.M.

Marine magnetic surveys have recorded total field anomalies that correspond to structural lineaments extending from the coast into the sea. The significant anomalies recorded in this area are along wavelength high amplitude negative anomaly...

Crustal structure of the Churchill-Superior boundary zone between 80 and 98 deg W longitude from Magsat anomaly maps and stacked passes

Science.gov (United States)

Hall, D. H.; Millar, T. W.; Noble, I. A.

1985-01-01

A modeling technique using spherical shell elements and equivalent dipole sources has been applied to Magsat signatures at the Churchill-Superior boundary in Manitoba, Ontario, and Ungava. A large satellite magnetic anomaly (12 nT amplitude) on POGO and Magsat maps near the Churchill-Superior boundary was found to be related to the Richmond Gulf aulacogen. The averaged crustal magnetization in the source region is 5.2 A/m. Stacking of the magnetic traces from Magsat passes reveals a magnetic signature (10 nT amplitude) at the Churchill-Superior boundary in an area studied between 80 deg W and 98 deg W. Modeling suggests a steplike thickening of the crust on the Churchill side of the boundary in a layer with a magnetization of 5 A/m. Signatures on aeromagnetic maps are also found in the source areas for both of these satellite anomalies.

A least-squares minimization approach for model parameters estimate by using a new magnetic anomaly formula

Science.gov (United States)

Abo-Ezz, E. R.; Essa, K. S.

2016-04-01

A new linear least-squares approach is proposed to interpret magnetic anomalies of the buried structures by using a new magnetic anomaly formula. This approach depends on solving different sets of algebraic linear equations in order to invert the depth ( z), amplitude coefficient ( K), and magnetization angle ( θ) of buried structures using magnetic data. The utility and validity of the new proposed approach has been demonstrated through various reliable synthetic data sets with and without noise. In addition, the method has been applied to field data sets from USA and India. The best-fitted anomaly has been delineated by estimating the root-mean squared (rms). Judging satisfaction of this approach is done by comparing the obtained results with other available geological or geophysical information.

Structural Anomalies and Multiferroic Behavior in Magnetically Frustrated TbMn2O5

NARCIS (Netherlands)

Chapon, L.C.; Blake, G.R.; Gutmann, M.J.; Park, S.; Hur, N.; Radaelli, P.G.; Cheong, S-W.

2004-01-01

We have studied the magnetostructural phase diagram of multiferroic TbMn2O5 as a function of temperature and magnetic field by neutron diffraction. Dielectric and magnetic anomalies are found to be associated with steps in the magnetic propagation vector, including a rare example of a

Anomaly detection using magnetic flux leakage technology

Energy Technology Data Exchange (ETDEWEB)

Rempel, Raymond G. [BJ Pipeline Inspection Services, Alberta (Canada)

2005-07-01

There are many aspects to properly assessing the integrity of a pipeline. In-line-Inspection (ILI) tools, in particular those that employ the advanced use of Magnetic Flux Leakage (MFL) technology, provide a valuable means of achieving required up-to-date knowledge of a pipeline. More prevalent use of High Resolution MFL In-Line-Inspection tools is growing the knowledge base that leads to more reliable and accurate identification of anomalies in a pipeline, thus, minimizing the need for expensive verification excavations. Accurate assessment of pipeline anomalies can improve the decision making process within an Integrity Management Program and excavation programs can then focus on required repairs instead of calibration or exploratory digs. Utilizing the information from an MFL ILI inspection is not only cost effective but, as well, can also prove to be an extremely valuable building block of a Pipeline Integrity Management Program. (author)

ADMAP-2: The second generation Antarctic crustal magnetic anomaly map.

Science.gov (United States)

Ferraccioli, F.; Golynsky, A.; Golynsky, D.; Young, D. A.; Eagles, G.; Damaske, D.; Finn, C.; Aitken, A.; von Frese, R. R. B.; Ghidella, M. E.; Kim, H. R.; Hong, J.

2017-12-01

ADMAP-2 is the second generation crustal magnetic anomaly compilation for the Antarctic region south of 60°S. It was produced from more than 3.5 million line-km of near-surface terrestrial, airborne and marine magnetic observations collected since the International Geophysical Year 1957/58 through 2013. The data were edited, IGRF corrected, profile levelled and gridded at a 1.5-km interval on a polar stereographic projection using the minimum curvature technique. Given the ubiquitous polar cover of snow, ice and sea water, the magnetic anomaly compilation offers important constraints on the global tectonic processes and crustal properties of the Antarctic. It also links widely separated areas of outcrop to help unify disparate geologic studies, and provides insights on the lithospheric transition between Antarctica and adjacent oceans, as well as the geodynamic evolution of the Antarctic lithosphere in the assembly and break-up of the Gondwana, Rodinia, and Columbia supercontinents and key piercing points for reconstructing linkages between the protocontinents. The magnetic data together with ice-probing radar and gravity information greatly facilitate understanding the evolution of fundamental large-scale geological processes such as continental rifting, intraplate mountain building, subduction and terrane accretion processes, and intraplate basin formation.

Delineation of structural lineaments from marine magnetic anomalies off Jonnalakonda, East Coast of India

Digital Repository Service at National Institute of Oceanography (India)

Sarma, K.V.L.N.S.; Rao, T.C.S.; Rao, D.G.

to charnockitic bodies occurring at shallow depth around 0.37 to 0.4 km and (2) the high frequency and amplitude anomalies near to the coast are trending north west-south east direction. The well developed magnetic anomaly is interpreted following automated Werner...

Observing Crustal Magnetic Anomalies in Remote Ocean Regions: Filling in the Gaps

Science.gov (United States)

Claus, B.; Kinsey, J. C.; Tominaga, M.; Tivey, M.

2016-12-01

The use of long duration ocean observing platforms is necessary for filling in broad gaps in the observational record of magnetic anomaly measurements in the ocean basins -- observations that are necessary for understanding a variety of geophysical processes. Such an instrument would need to gather 1000s of kilometers of magnetic data untended, requiring in-situ calibration methods and minimization of energy usage. In this work an autonomous underwater glider (AUG) has been equipped with a low power flux-gate magnetic sensor. Sensor integration was tested locally in shallow water followed by deep water trials to verify the calibration procedure in June of 2016. During this cruise a 160 kilometer magnetic tow was also collected across the East Coast Shelf Anomaly to the South-East of Cape Cod. Following these tests, the AUG was deployed such that it followed the trajectory of the towed magnetic survey to provide a baseline comparison against a known methodology. For these deployments an in-situ calibration procedure was used whereby the vehicle was commanded to perform descending and ascending spirals with its actuators at various discrete locations. When combined with a temperature model for the sensor the calibrated measurements were found to be in agreement with the towed data to within several 10's of nT. These comparative measurements demonstrate the utility of using directed long duration autonomous ocean observing platforms to gather medium wavelength crustal magnetic anomaly features. This ability is especially desirable for collecting measurements in remote ocean basins, such as the Southern Ocean, where presently only a few ship tracks exist and are likely to never be sampled by conventional research vessels surveys.

Seafloor spreading magnetic anomalies in the southeastern Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Chaubey, A.K.; Bhattacharya, G.C; Rao, D.G.

. A new geomagnetic polarity time scale for the Late Cretaceous and Cenozoic. J. Geophys. Res., 97: 13,917-13,951. Cande, S.C., La Brecque, J.L., Larson, R.L., Pitman, W.C., Golovchenko, X. and Haxby, W.F., 1989. Magnetic linea- tions of the world....O., Herron, E.M., Pitman, W.C. and Le Pichon, X., 1968. Marine magnetic anomalies, geomagnetic field reversals, and motions of the ocean floor and continents. J. Geophys. Res., 73: 2119-2136. McKenzie, D.P. and Sclater, J.G., 1971. The evolution...

Gravity and magnetic anomalies of the Cyprus arc and tectonic implications

Science.gov (United States)

Ergün, M.; Okay, S.; Sari, C.; Oral, E. Z.

2003-04-01

In present day, eastern Mediterranean is controlled by the collision of the African and Eurasian plates and displacements of Arabian, Anatolian and Aegean micro-plates. The boundary between African and Eurasian plates is delineated by the Hellenic arc and Pliny-Strabo trench in the west and the Cyprus arc and a diffuse fault system of the Eastern Anatolian Fault zone in the east. The available gravity and magnetic data from the easternmost Mediterranean allow to subdivide this basin into three provinces: the northeastern Mediterranean north of the Cyprus Arc; the Levant Basin south of the Cyprus Arc and east of the line that roughly continues the Suez rift trend toward the Gulf of Antalya, between Cyprus and Anaximander Mountains; and the Mediterranean Ridge, Herodotus Basin west of this line. High anomalies observed in Cyprus and the sea region at the south is prominent in the gravity data. The Bouguer gravity anomaly reaches its maximum values over Cyprus, where it is most probably caused by high dense Troodos ophiolites. The uplifted oceanic crust causes high Bouguer anomaly also seen in the vicinity of Eratosthenes Seamount. Another result obtained from gravity data is that the crust under Herodotos and Rhodes basins is somehow oceanic and Anaximander, Eratosthenes and Cyprus are continental fragments. There are no linear magnetic anomalies in the Mediterranean. But there are magnetic anomalies over the Eratosthenes seamount and as well as from Cyprus to the Antalya basin due to the ophiolitic bodies. In Cyprus, the last compressional deformations were defined near the Miocene/Pliocene boundary. The extensional deformation associated with the Antalya basin appears to be separated by a zone of the Florence rise and Anaximander Mountains affected by differential tectonic movements. Eratosthenes Seamount is a positive crustal feature in the process of collision with Cyprus along an active margin; there is clearly a potential tectonic relationship to the onland

Automatic program for the interpretation of two-dimensional gravity and magnetic anomalies

International Nuclear Information System (INIS)

Wagini, A.

1985-01-01

This automatic inversion program for the interpretation of two-dimensional gravity and magnetic anomalies has been developed mainly in support of the US Geological Survey's effort to characterize potential radioactive-waste storage sites at the Nevada Test Site, Nevada. Determining subsurface shapes and extensions of geologic bodies necessitates extensive modeling of magnetic and gravity data. Geologic models for the source of magnetic or gravity anomalies are often developed by trial and error: an approximation is made to establish an initial model, the anomaly due to the model is calculated and compared with the observed anomaly, and the model is iteratively modified to improve the agreement between calculated and observed anomalies. The method presented is not a least-squares method like other methods developed during the last few years, but minimizes the sum of the squares of the residuals by varying only one variable (coordinate) at a time. Varying one variable at a time allows one to use all available information in the model calculation, which can essentially reduce the computation time. The objective of this program is to find the shape of geologic bodies when the physical parameters are known. Except for the outermost corners, only the z-coordinate of each corner-point is varied. The variation of only one variable at a time has the advantage that a large number of bodies and corner-points (in this program up to 50 bodies, each with up to 50 corner-points) can be used for the model calculation without solving a large matrix. This can be important, especially for smaller computers. The program is written in ANSI Standard FORTRAN 77 and is interactive; thus it requires little knowledge of the computer system and its editing facilities. 5 refs

Detection of a weak meddy-like anomaly from high-resolution satellite SST maps

Directory of Open Access Journals (Sweden)

Mikhail Emelianov

2012-09-01

Full Text Available Despite the considerable impact of meddies on climate through the long-distance transport of properties, a consistent observation of meddy generation and propagation in the ocean is rather elusive. Meddies propagate at about 1000 m below the ocean surface, so satellite sensors are not able to detect them directly and finding them in the open ocean is more fortuitous than intentional. However, a consistent census of meddies and their paths is required in order to gain knowledge about their role in transporting properties such as heat and salt. In this paper we propose a new methodology for processing high-resolution sea surface temperature maps in order to detect meddy-like anomalies in the open ocean on a near-real-time basis. We present an example of detection, involving an atypical meddy-like anomaly that was confirmed as such by in situ measurements.

Measurement of the terrestrial magnetic field and its anomalies; Mesures du champ magnetique terrestre et de ses anomalies

Energy Technology Data Exchange (ETDEWEB)

Duret, D.

1994-12-31

After a presentation of the terrestrial magnetic field and its various anomalies, the different types of magnetometers commonly used are reviewed with their characteristics and performances: scalar magnetometers (free precession and continuous polarization proton magnetometers, dynamic polarization proton magnetometers, optical pumping magnetometers, electronic resonance scalar magnetometers (without pumping)); vectorial magnetometers (flux gate magnetometers, induction magnetometers, suspended magnet magnetometers, superconducting magnetometers, integrated magnetometers, resonance directional magnetometers). The magnetometry market and applications are discussed. 20 figs., 9 tabs., 72 refs.

Magnetic investigation and 2½ D gravity profile modelling across the Beattie magnetic anomaly in the southeastern Karoo Basin, South Africa

Science.gov (United States)

Baiyegunhi, Christopher; Gwavava, Oswald

2017-03-01

The southeastern Karoo Basin is considered to be one of the most prospective areas for shale gas exploration in South Africa. An interesting magnetic anomaly, the Beattie magnetic anomaly (BMA), and geologic intrusions are seen on the magnetic map. To date, the source of the BMA and interconnectivity of the igneous intrusions are not well understood. In this study, we investigate the interconnectivity of the igneous intrusions and possible location of the source of the BMA using gravity and magnetic methods. The gravity model results showed that igneous intrusions are interconnected at depth, which probably pose threat by increasing the risk of fracking the Karoo for shale gas exploration. The magnetic results revealed that the BMA becomes stronger with depth. The average depths to the top of the shallow and deep magnetic sources were estimated to be approximately 0.6 and 15 km, respectively.

Optimization of Archeological Anomalies using GIS method for Magnetic and Resistivity Study at Sungai Batu, Lembah Bujang, Kedah (Malaysia)

Science.gov (United States)

Yusoh, R.; Saad, R.; Saidin, M.; Anda, S. T.; Muhammad, S. B.; Ashraf, M. I. M.; Hazreek, Z. A. M.

2018-04-01

Magnetic and resistivity method has become a reliable option in archeological exploration. The use of both method has become popular these day. However, both method gives different type of sensing in detecting anomalies and direct interpret from the anomalies will result large coverage area for excavation. Therefore, to overcome this issue, both anomalies can be extracted using ArcGIS software to reduce excavated coverage area. The case study located at Sungai Batu, Lembah Bujang near SB2ZZ lot expected buried clay brick monument which will be a perfect case to apply this technique. Magnetic and resistivity method was implemented at the study area where the anomalies coverage area for magnetic and resistivity is 531.5 m2 and 636 m2 respectively which total area of both anomalies was 764 m2. By applying combine technique, the anomalies area reduce to 403.7 m2 which reduce the suspected anomalies by 47.16 %. The unsuspected clay brick monument area was increase from 15.86% to 55.54% which improve the cost and labor work for excavation.

Evidence of Urban Precipitation Anomalies from Satellite and Ground-Based Measurements

Science.gov (United States)

Shepherd, J. Marshall; Manyin, M.; Negri, Andrew

2004-01-01

Urbanization is one of the extreme cases of land use change. Most of world's population has moved to urban areas. Although currently only 1.2% of the land is considered urban, the spatial coverage and density of cities are expected to rapidly increase in the near future. It is estimated that by the year 2025, 60% of the world's population will live in cities. Human activity in urban environments also alters weather and climate processes. However, our understanding of urbanization on the total Earth-weather-climate system is incomplete. Recent literature continues to provide evidence that anomalies in precipitation exist over and downwind of major cities. Current and future research efforts are actively seeking to verify these literature findings and understand potential cause-effect relationships. The novelty of this study is that it utilizes rainfall data from multiple satellite data sources (e.g. TRMM precipitation radar, TRMM-geosynchronous-rain gauge merged product, and SSM/I) and ground-based measurements to identify spatial anomalies and temporal trends in precipitation for cities around the world. Early results will be presented and placed within the context of weather prediction, climate assessment, and societal applications.

The Study of the Electron Enhancements during Garuda-1 Satellite anomaly

Science.gov (United States)

Neflia, Neflia

Garuda-1 Satellite is one of Indonesian geostationary satellite. On April 5, 2005 Garuda-1 experienced power loss. According to space weather condition, This anomaly could be caused by the enhancement of electron during the day of anomaly and geomagnetic activity. The electron enhancement during quite solar activity have been associated with solar wind speed and IMF. For this study I will use solar wind speed, IMF , AE, Kp, Dst and Plasma Flow Pressure. The result of this study show that before the electron fluxes exceed 1000 pfu on April 5 at 13 UT, solar wind plasma speed exceed 500 km/s from April 4 at 16 UT until April 6 at 21 UT, with maximum speed, 646 km/s, occur on April 5 at 9 UT. AE index also increase from April 4 at 16 UT until April 6 at 09 UT, with maximum AE, 1024 nT, occur on April 5 at 18 and 21 UT. From April 4 at 14 UT until April 5 at 7 UT, Bz index directed southward, with minimum Bz, -8.8 nT, occur at April 5 at 1 UT. Kp index also increase from April 4 at 16 UT until April 6 at 09 UT, with maximum Kp, 7, occur on April 5 at 0-3 UT. Dst decrease from April 4 at 21 UT until April 6 at 09 UT, with minimum Dst occur on April 5 at 5-6 UT. The plasma flow pressure increase from April4 at 18 UT until April 5 at 3 UT, with maximum pressure, 6.9 nPa, occur on April 4 at 21 UT. This result indicate that plasma condition was disturbed which started with geomagnetic subtorm in the Auroral region before electron flux increase.

Paleomagnetic determinations on Lanzarote from magnetic and gravity anomalies: Implications for the early history of the Canary Islands

Science.gov (United States)

Blanco-Montenegro, I.; Montesinos, F. G.; GarcíA, A.; Vieira, R.; VillalaíN, J. J.

2005-12-01

The Bouguer and aeromagnetic anomaly maps of Lanzarote show a gravity high and a dipolar magnetic anomaly over the central part of the island, indicating one isolated source. Assuming that the structure responsible for both anomalies is the same, a methodology has been designed to estimate the total magnetization vector of the source, which is interpreted as a large intrusive body (mafic core) positioned as a result of magma rising to the surface during the early stages of growth of Lanzarote. Considering its geometry to be known from a previous three-dimensional (3-D) gravity model, the approach proposed in this paper is based on the delineation of magnetic contacts through analysis of the horizontal gradient of the reduced-to-the-pole anomaly map, comparison between the gravity and the pseudogravity anomalies, and 3-D forward magnetic modeling. The total magnetization vector obtained by this method is defined by a module of 4.5 A m-1 and a direction D = -20° and I = 30°. Comparing the paleomagnetic pole, obtained from this direction, with the apparent polar wander path of Africa for the last 160 Myr, it is concluded that the main component of the total magnetization vector is probably a primary natural remanent magnetization (NRM) which could have been acquired between 60 and 100 Ma. This result suggests that the emplacement of magmas at shallow depths linked to the beginning of volcanism in Lanzarote took place during the Upper Cretaceous, thus providing the first evidence of a timeline for the early formative stages of this volcanic island.

South Atlantic Anomaly evolution by means of Swarm data

Science.gov (United States)

Pavon-Carrasco, F. Javier; Qamili, Enkelejda; De Santis, Angelo

2015-04-01

The study of the South Atlantic Anomaly (SAA) is an important challenge nowadays not only for the geomagnetic and paleomagnetic community, but also for other areas focused on the Earth Observation. This large magnetic anomaly is characterized by values of geomagnetic field intensity around 30% lower than expected for those latitudes and covers a large area in the South Atlantic Ocean between Southwest Brazil and South Africa. This great depression of the geomagnetic field strength at the Earth's surface has an internal deep origin: it is caused by a prominent patch of reversed polarity flux in the outer core. Since the Earth's magnetic field has an important protective role for the all geosphere because it deflects a large part of the solar radiation that would otherwise reach the Earth's surface, a large increase of the SAA could have dramatic consequences for human health and technologies. In the last three decades, an almost constant monitoring of the SAA has been carried out using satellite data showing a clear picture of the behaviour and evolution of the SAA, which area is growing alarmingly during the most recent years at the Earth's surface and at the core mantle boundary. In this context, the ESA Swarm mission (constituted by a constellation of three satellites in near-polar low orbits at two different altitudes) is providing detailed measurements of the intensity and directional elements of the geomagnetic field with high-precision and resolution never reached in the former space missions. This work aims to analyse in detail in space and time the SAA from the Earth's surface up to the satellite altitude. In order to carry out this study, comprehensive geomagnetic models at regional and global scale will be performed using the dataset provided by the Swarm satellites and all the available ground data. This kind of study is crucial to understand the evolution of the Earth's magnetic field in this area, and to possibly predict its future behaviour.

Satellite traces, range spread-F occurrence, and gravity wave propagation at the southern anomaly crest

Energy Technology Data Exchange (ETDEWEB)

Cabrera, M.A. [Universidad Tecnologica Nacional, Tucuman (Argentina). CIASUR, Facultad Regional Tucuman; Universidad Nacional de Tucuman (Argentina). Lab. de Ionosfera; Pezzopane, M.; Zuccheretti, E. [Istituto Nazionale di Geofisica e Vulcanologia, Rome (Italy); Ezquer, R.G. [Universidad Tecnologica Nacional, Tucuman (Argentina). CIASUR, Facultad Regional Tucuman; Universidad Nacional de Tucuman (Argentina). Lab. de Ionosfera; Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires (Argentina)

2010-07-01

Range spread-F (RSF) and occurrence of ''satellite'' traces prior to RSF onset were studied at the southern peak of the ionospheric equatorial anomaly (EA). Ionograms recorded in September 2007 at the new ionospheric station of Tucuman, Argentina (26.9 S, 294.6 E, dip latitude 15.5 S), by the Advanced Ionospheric Sounder (AIS) developed at the Istituto Nazionale di Geofisica e Vulcanologia (INGV), were considered. Satellite traces (STs) are confirmed to be a necessary precursor to the appearance of an RSF trace on the ionograms. Moreover, an analysis of isoheight contours of electron density seems to suggest a relationship between RSF occurrence and gravity wave (GW) propagation. (orig.)

Satellite Tidal Magnetic Signals Constrain Oceanic Lithosphere-Asthenosphere Boundary Earth Tomography with Tidal Magnetic Signals

Science.gov (United States)

Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.; Sabaka, Terence J.; Chandrasekharan, Manoj; Olsen, Niles

2016-01-01

The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation of secondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; however, there are no reports that these signals have been used to infer subsurface structure. Here we use satellite-detected tidal magnetic fields to image the global electrical structure of the oceanic lithosphere and upper mantle down to a depth of about 250 km. The model derived from more than 12 years of satellite data reveals an Approximately 72 km thick upper resistive layer followed by a sharp increase in electrical conductivity likely associated with the lithosphere-asthenosphere boundary, which separates colder rigid oceanic plates from the ductile and hotter asthenosphere.

Magnetic and magnetoelastic anomalies of an Er.sub.2./sub.Co.sub.17./sub. single crystal in high magnetic fields

Czech Academy of Sciences Publication Activity Database

Andreev, Alexander V.; Skourski, Y.; Kuz'min, M.D.; Yasin, S.; Zherlitsyn, S.; Daou, R.; Wosnitza, J.; Iwasa, A.; Kondo, A.; Matsuo, A.; Kindo, K.

2011-01-01

Roč. 83, č. 18 (2011), "184422-1"-"184422-9" ISSN 1098-0121 R&D Projects: GA ČR GA202/09/0339 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic and magnetoelastic anomalies * high magnetic fields * anisotropy constants Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

MODVOLC2: A Hybrid Time Series Analysis for Detecting Thermal Anomalies Applied to Thermal Infrared Satellite Data

Science.gov (United States)

Koeppen, W. C.; Wright, R.; Pilger, E.

2009-12-01

We developed and tested a new, automated algorithm, MODVOLC2, which analyzes thermal infrared satellite time series data to detect and quantify the excess energy radiated from thermal anomalies such as active volcanoes, fires, and gas flares. MODVOLC2 combines two previously developed algorithms, a simple point operation algorithm (MODVOLC) and a more complex time series analysis (Robust AVHRR Techniques, or RAT) to overcome the limitations of using each approach alone. MODVOLC2 has four main steps: (1) it uses the original MODVOLC algorithm to process the satellite data on a pixel-by-pixel basis and remove thermal outliers, (2) it uses the remaining data to calculate reference and variability images for each calendar month, (3) it compares the original satellite data and any newly acquired data to the reference images normalized by their variability, and it detects pixels that fall outside the envelope of normal thermal behavior, (4) it adds any pixels detected by MODVOLC to those detected in the time series analysis. Using test sites at Anatahan and Kilauea volcanoes, we show that MODVOLC2 was able to detect ~15% more thermal anomalies than using MODVOLC alone, with very few, if any, known false detections. Using gas flares from the Cantarell oil field in the Gulf of Mexico, we show that MODVOLC2 provided results that were unattainable using a time series-only approach. Some thermal anomalies (e.g., Cantarell oil field flares) are so persistent that an additional, semi-automated 12-µm correction must be applied in order to correctly estimate both the number of anomalies and the total excess radiance being emitted by them. Although all available data should be included to make the best possible reference and variability images necessary for the MODVOLC2, we estimate that at least 80 images per calendar month are required to generate relatively good statistics from which to run MODVOLC2, a condition now globally met by a decade of MODIS observations. We also found

Development of references of anomalies detection on P91 material using Self-Magnetic Leakage Field (SMLF) technique

Science.gov (United States)

Husin, Shuib; Afiq Pauzi, Ahmad; Yunus, Salmi Mohd; Ghafar, Mohd Hafiz Abdul; Adilin Sekari, Saiful

2017-10-01

This technical paper demonstrates the successful of the application of self-magnetic leakage field (SMLF) technique in detecting anomalies in weldment of a thick P91 materials joint (1 inch thickness). Boiler components such as boiler tubes, stub boiler at penthouse and energy piping such as hot reheat pipe (HRP) and H-balance energy piping to turbine are made of P91 material. P91 is ferromagnetic material, therefore the technique of self-magnetic leakage field (SMLF) is applicable for P91 in detecting anomalies within material (internal defects). The technique is categorized under non-destructive technique (NDT). It is the second passive method after acoustic emission (AE), at which the information on structures radiation (magnetic field and energy waves) is used. The measured magnetic leakage field of a product or component is a magnetic leakage field occurring on the component’s surface in the zone of dislocation stable slipbands under the influence of operational (in-service) or residual stresses or in zones of maximum inhomogeneity of metal structure in new products or components. Inter-granular and trans-granular cracks, inclusion, void, cavity and corrosion are considered types of inhomogeneity and discontinuity in material where obviously the output of magnetic leakage field will be shown when using this technique. The technique does not required surface preparation for the component to be inspected. This technique is contact-type inspection, which means the sensor has to touch or in-contact to the component’s surface during inspection. The results of application of SMLF technique on the developed P91 reference blocks have demonstrated that the technique is practical to be used for anomaly inspection and detection as well as identification of anomalies’ location. The evaluation of this passive self-magnetic leakage field (SMLF) technique has been verified by other conventional non-destructive tests (NDTs) on the reference blocks where simulated

Rock magnetic characterization of faulted sediments with associated magnetic anomalies in the Albuquerque Basin, Rio Grande rift, New Mexico

Science.gov (United States)

Hudson, M.R.; Grauch, V.J.S.; Minor, S.A.

2008-01-01

Variations in rock magnetic properties are responsible for the many linear, short-wavelength, low-amplitude magnetic anomalies that are spatially associated with faults that cut Neogene basin sediments in the Rio Grande rift, including the San Ysidro normal fault, which is well exposed in the northern part of the Albuquerque Basin. Magnetic-susceptibility measurements from 310 sites distributed through a 1200-m-thick composite section of rift-filling sediments of the Santa Fe Group and prerift Eocene and Cretaceous sedimentary rocks document large variations of magnetic properties juxtaposed by the San Ysidro fault. Mean volume magnetic susceptibilities generally increase upsection through eight map units: from 1.7 to 2.2E-4 in the prerift Eocene and Cretaceous rocks to 9.9E-4-1.2E-3 in three members of the Miocene Zia Formation of the Santa Fe Group to 1.5E-3-3.5E-3 in three members of the Miocene-Pleistocene Arroyo Ojito Formation of the Santa Fe Group. Rock magnetic measurements and petrography indicate that the amount of detrital magnetite and its variable oxidation to maghemite and hematite within the Santa Fe Group sediments are the predominant controls of their magnetic property variations. Magnetic susceptibility increases progressively with sediment grain size within the members of the Arroyo Ojito Formation (deposited in fluvial environments) but within members of the Zia Formation (deposited in mostly eolian environments) reaches highest values in fine to medium sands. Partial oxidation of detrital magnetite is spatially associated with calcite cementation in the Santa Fe Group. Both oxidation and cementation probably reflect past flow of groundwater through permeable zones. Magnetic models for geologic cross sections that incorporate mean magnetic susceptibilities for the different stratigraphic units mimic the aeromagnetic profiles across the San Ysidro fault and demonstrate that the stratigraphic level of dominant magnetic contrast changes with

Low temperature anomaly of light stimulated magnetization and heat capacity of the 1D diluted magnetic semiconductors

Science.gov (United States)

Geffe, Chernet Amente

2018-03-01

This article reports magnetization and specific heat capacity anomalies in one dimensional diluted magnetic semiconductors observed at very low temperatures. Based on quantum field theory double time temperature dependent Green function technique is employed to evaluate magnon dispersion and the time correlation function. It is understood that magnon-photon coupling and magnetic impurity concentration controls both, such that near absolute temperature magnetization is nearly zero and abruptly increase to saturation level with decreasing magnon-photon coupling strength. We also found out dropping of magnetic specific heat capacity as a result of increase in magnetic impurity concentration x, perhaps because of inter-band disorder that would suppress the enhancement of density of spin waves.

Low temperature anomaly of light stimulated magnetization and heat capacity of the 1D diluted magnetic semiconductors

Directory of Open Access Journals (Sweden)

Chernet Amente Geffe

2018-03-01

Full Text Available This article reports magnetization and specific heat capacity anomalies in one dimensional diluted magnetic semiconductors observed at very low temperatures. Based on quantum field theory double time temperature dependent Green function technique is employed to evaluate magnon dispersion and the time correlation function. It is understood that magnon-photon coupling and magnetic impurity concentration controls both, such that near absolute temperature magnetization is nearly zero and abruptly increase to saturation level with decreasing magnon-photon coupling strength. We also found out dropping of magnetic specific heat capacity as a result of increase in magnetic impurity concentration x, perhaps because of inter-band disorder that would suppress the enhancement of density of spin waves.

Analysis of vector magnetic anomalies over the Bayonnaise Knoll caldera obtained from a deep-sea magnetic exploration by AUV

Science.gov (United States)

Sayanagi, K.; Isezaki, N.; Matsuo, J.; Harada, M.; Kasaya, T.

2011-12-01

Geophysical surveys near the seafloor are very effective methods in order to investigate fine structures of the oceanic crust. Such surveys have increased in researches and developments of the seafloor, and will be more and more necessary in the future. For example, seabed resources like hydrothermal deposits have recently focused attention behind the international situation for natural resources like a competition of resources development. In order to estimate accurate abundance of those resources, the above detailed investigations should be needed because of low resolution of geophysical surveys on the sea and low efficiency of exploratory drilling. From such a viewpoint, we have been developing a measurement system for magnetic explorations using an AUV and a deep-tow system. The magnetic exploration system consists of two 3-axis flux-gate magnetometers, one/two Overhauser magnetometer(s), an optical fiber gyro, a main unit (control, communication, recording), and an onboard unit. These devices except for the onboard unit are installed in pressure cases (depth limit: 6000m). Thus this system can measure three components and total intensity of the geomagnetic field in the deep sea. In 2009, the first test of the magnetic exploration system was carried out in the Kumano Basin using AUV Urashima and towing vehicle Yokosuka Deep-Tow during the R/V Yokosuka YK09-09 cruise. In this test, we sank a small magnetic target to the seafloor, and examined how the system worked. As a result, we successfully detected magnetic anomaly of the target to confirm the expected performance of that in the sea. In 2010, the magnetic exploration system was further tested in the Bayonnaise Knoll area both using a titanium towing frame during the R/V Bosei-maru cruise and using AUV Urashima during the R/V Yokosuka YK10-17 cruise. The purpose of these tests was to evaluate the performance of the system in an actual hydrothermal deposit area for practical applications of that. The

Magnetization of the oceanic crust: TRM or CRM?

Science.gov (United States)

Raymond, C. A.; Labrecque, J. L.

1987-01-01

A model was proposed in which chemical remanent magnetization (CRM) acquired within the first 20 Ma of crustal evolution may account for 80% of the bulk natural remanent magnetization (NRM) of older basalts. The CRM of the crust is acquired as the original thermoremanent magnetization (TRM) is lost through low temperature alteration. The CRM intensity and direction are controlled by the post-emplacement polarity history. This model explains several independent observations concerning the magnetization of the oceanic crust. The model accounts for amplitude and skewness discrepancies observed in both the intermediate wavelength satellite field and the short wavelength sea surface magnetic anomaly pattern. It also explains the decay of magnetization away from the spreading axis, and the enhanced magnetization of the Cretaceous Quiet Zones while predicting other systematic variations with age in the bulk magnetization of the oceanic crust. The model also explains discrepancies in the anomaly skewness parameter observed for anomalies of Cretaceous age. Further studies indicate varying rates of TRM decay in very young crust which depicts the advance of low temperature alteration through the magnetized layer.

Magnetic field experiment on the SUNSAT satellite

Science.gov (United States)

Kotzé, P. B.; Langenhoven, B.; Risbo, T.

2002-03-01

On Tuesday 23 February 1999, at 10:29 UTC, SUNSAT was launched into an 857×655 km, 96.47° polar orbit on a Boeing-Delta II rocket from Vandenberg Air Force Base in California, USA. Both SUNSAT and Ørsted were NASA-sponsored secondary payloads accompanying the USA Air Force Argos satellite. In the process it became South Africa's (and Africa's) first satellite in space. Although sponsored by several private industrial organisations, it is essentially a student project with more than 96 graduate students in the Department of Electronic and Electrical Engineering at the University of Stellenbosch providing the majority of SUNSAT's engineering development and operation since 1992. This paper reports on the magnetic field experiment on board the Sunsat satellite, consisting of two fluxgate magnetometers, called Orimag and Scimag, both built and calibrated by the Hermanus Magnetic Observatory. Orimag is mainly used for orientation control purposes on SUNSAT, while Scimag, mounted on a boom of 2.2 m is designed to perform geomagnetic field observations, employing standard navigation fluxgate technology.

IceBridge Scintrex CS-3 Cesium Magnetometer L1B Geolocated Magnetic Anomalies, Version 1

Data.gov (United States)

National Aeronautics and Space Administration — The NASA IceBridge Scintrex CS-3 Cesium Magnetometer L1B Geolocated Magnetic Anomalies (IMCS31B) data set contains magnetic field readings taken over Greenland using...

Magnetic dipole moment estimation and compensation for an accurate attitude control in nano-satellite missions

Science.gov (United States)

Inamori, Takaya; Sako, Nobutada; Nakasuka, Shinichi

2011-06-01

Nano-satellites provide space access to broader range of satellite developers and attract interests as an application of the space developments. These days several new nano-satellite missions are proposed with sophisticated objectives such as remote-sensing and observation of astronomical objects. In these advanced missions, some nano-satellites must meet strict attitude requirements for obtaining scientific data or images. For LEO nano-satellite, a magnetic attitude disturbance dominates over other environmental disturbances as a result of small moment of inertia, and this effect should be cancelled for a precise attitude control. This research focuses on how to cancel the magnetic disturbance in orbit. This paper presents a unique method to estimate and compensate the residual magnetic moment, which interacts with the geomagnetic field and causes the magnetic disturbance. An extended Kalman filter is used to estimate the magnetic disturbance. For more practical considerations of the magnetic disturbance compensation, this method has been examined in the PRISM (Pico-satellite for Remote-sensing and Innovative Space Missions). This method will be also used for a nano-astrometry satellite mission. This paper concludes that use of the magnetic disturbance estimation and compensation are useful for nano-satellites missions which require a high accurate attitude control.

Characteristics of equatorial ionization anomaly (EIA) in relation to transionospheric satellite links around the northern crest in the Indian longitude sector

Science.gov (United States)

Das, A.; Paul, K. S.; Halder, S.; Basu, K.; Paul, A.

2014-02-01

The poleward gradient of the equatorial ionization anomaly (EIA) introduces more intense propagation effects on transionospheric satellite links in comparison to the equatorward gradient. Characterization of the poleward gradient was performed during March-April, August-October 2011 and March-April 2012 using GPS total electron content (TEC) recorded from a chain of stations located more or less along the same meridian (88.5° E) at Calcutta, Baharampore, Farakka and Siliguri. The poleward gradients calculated on magnetically quiet days at elevation in excess of 50° at 14:00, 15:00 and 16:00 LT were found to have a strong correlation with GPS S4 observed from Calcutta during post-sunset-to-midnight hours. A threshold value of poleward TEC gradient is calculated above which there is a probability of scintillation at Calcutta with S4 ≥ 0.4.

Characteristics of equatorial ionization anomaly (EIA in relation to transionospheric satellite links around the northern crest in the Indian longitude sector

Directory of Open Access Journals (Sweden)

A. Das

2014-02-01

Full Text Available The poleward gradient of the equatorial ionization anomaly (EIA introduces more intense propagation effects on transionospheric satellite links in comparison to the equatorward gradient. Characterization of the poleward gradient was performed during March–April, August–October 2011 and March–April 2012 using GPS total electron content (TEC recorded from a chain of stations located more or less along the same meridian (88.5° E at Calcutta, Baharampore, Farakka and Siliguri. The poleward gradients calculated on magnetically quiet days at elevation in excess of 50° at 14:00, 15:00 and 16:00 LT were found to have a strong correlation with GPS S4 observed from Calcutta during post-sunset-to-midnight hours. A threshold value of poleward TEC gradient is calculated above which there is a probability of scintillation at Calcutta with S4 ≥ 0.4.

Satellite-borne study of seismic phenomena by low frequency magnetic field observations

Science.gov (United States)

Schwingenschuh, Konrad; Magnes, Werner; Xuhui, Shen; Wang, Jindong; Pollinger, Andreas; Hagen, Christian; Prattes, Gustav; Eichelberger, Hans-Ulrich; Wolbang, Daniel; Boudjada, Mohammed Y.; Besser, Bruno P.; Rozhnoi, Alexander A.; Zhang, Tielong

2015-04-01

A combined scalar-vector magnetic field experiment will be flown on the upcoming CSES mission (China Seismo-Electromagnetic Satellite). Magnetic field data from DC to 30 Hz will be measured with an accuracy of about 10 pT. A fluxgate instrument will provide the 3 magnetic field components and a new type of an optically pumped magnetometer [see Pollinger, 2010] will measure the magnitude of the ambient magnetic field. The satellite will operate in a Sun synchronous polar orbit at an altitude of about 500 km and with an inclination of 97°. We present a model of magnetic field fluctuations in the upper ionosphere based on previous satellite observations and on a model of the lithospheric-atmospheric-ionospheric coupling. Pollinger et al., CDSM-a new scalar magnetometer, EGU General Assembly 2010

PSO (Particle Swarm Optimization) for Interpretation of Magnetic Anomalies Caused by Simple Geometrical Structures

Science.gov (United States)

Essa, Khalid S.; Elhussein, Mahmoud

2018-04-01

A new efficient approach to estimate parameters that controlled the source dimensions from magnetic anomaly profile data in light of PSO algorithm (particle swarm optimization) has been presented. The PSO algorithm has been connected in interpreting the magnetic anomaly profiles data onto a new formula for isolated sources embedded in the subsurface. The model parameters deciphered here are the depth of the body, the amplitude coefficient, the angle of effective magnetization, the shape factor and the horizontal coordinates of the source. The model parameters evaluated by the present technique, generally the depth of the covered structures were observed to be in astounding concurrence with the real parameters. The root mean square (RMS) error is considered as a criterion in estimating the misfit between the observed and computed anomalies. Inversion of noise-free synthetic data, noisy synthetic data which contains different levels of random noise (5, 10, 15 and 20%) as well as multiple structures and in additional two real-field data from USA and Egypt exhibits the viability of the approach. Thus, the final results of the different parameters are matched with those given in the published literature and from geologic results.

Adaptive cancellation of geomagnetic background noise for magnetic anomaly detection using coherence

International Nuclear Information System (INIS)

Liu, Dunge; Xu, Xin; Huang, Chao; Zhu, Wanhua; Liu, Xiaojun; Fang, Guangyou; Yu, Gang

2015-01-01

Magnetic anomaly detection (MAD) is an effective method for the detection of ferromagnetic targets against background magnetic fields. Currently, the performance of MAD systems is mainly limited by the background geomagnetic noise. Several techniques have been developed to detect target signatures, such as the synchronous reference subtraction (SRS) method. In this paper, we propose an adaptive coherent noise suppression (ACNS) method. The proposed method is capable of evaluating and detecting weak anomaly signals buried in background geomagnetic noise. Tests with real-world recorded magnetic signals show that the ACNS method can excellently remove the background geomagnetic noise by about 21 dB or more in high background geomagnetic field environments. Additionally, as a general form of the SRS method, the ACNS method offers appreciable advantages over the existing algorithms. Compared to the SRS method, the ACNS algorithm can eliminate the false target signals and represents a noise suppressing capability improvement of 6.4 dB. The positive outcomes in terms of intelligibility make this method a potential candidate for application in MAD systems. (paper)

First stage of INTRAMAP: INtegrated Transantarctic Mountains and Ross Sea Area Magnetic Anomaly Project

Directory of Open Access Journals (Sweden)

D. Damaske

1999-06-01

Full Text Available INTRAMAP (INtegrated Transantarctic Mountains and Ross Sea Area Magnetic Anomaly Project is an international effort to merge the magnetic data acquired throughout the "Ross Sea Antarctic Sector" (south of 60°S between 135°-255°E including the Transantarctic Mountains (TAM, the Ross Sea, Marie Byrd Land, and the Pacific coast, and also to begin the compilation efforts for new data over the Wilkes Basin. This project is a component of the continental scale Antarctic Digital Magnetic Anomaly Project (ADMAP. The first stage of INTRAMAP addresses the analysis and merging of GITARA (1991-1994 and GANOVEX (1984 aeromagnetic surveys together with ground magnetic data (1984-1989. The combined data sets cover an area of approximately 30 km2 over Victoria Land and adjacent Ross Sea. Map and profile gridding were implemented to integrate the data sets. These approaches are studied for improving existing strategies to adopt for the whole magnetic compilation effort. The final microlevelled grid that we produce is a new tool for regional interpretation of the main tectonic and geologic features of this sector of Antarctica.

Hot Flow Anomaly formation by magnetic deflection

International Nuclear Information System (INIS)

Onsager, T.G.; Thomsen, M.F.; Winske, D.

1990-01-01

Hot Flow Anomalies (HFAs) are localized plasma structures observed in the solar wind and magnetosheath near the Earth's quasi-parallel bow shock. The authors present 1-D hybrid computer simulations illustrating a formation mechanism for HFAs in which the single, hot, ion population results from a spatial separation of two counterstreaming ion beams. The higher-density, cooler regions are dominated by the background (solar wind) ions, and the lower-density, hotter, internal regions are dominated by the beam ions. The spatial separation of the beam and background is caused by the deflection of the ions in large amplitude magnetic fields which are generated by ion/ion streaming instabilities

Satellite tidal magnetic signals constrain oceanic lithosphere-asthenosphere boundary

DEFF Research Database (Denmark)

Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.

2016-01-01

The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation ofsecondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; howeve...

Martian meteorites and Martian magnetic anomalies: a new perspective from NWA 7034 (Invited)

Science.gov (United States)

Gattacceca, J.; Rochette, P.; Scozelli, R. B.; Munayco, P.; Agee, C. B.; Quesnel, Y.; Cournede, C.; Geissman, J. W.

2013-12-01

The magnetic anomalies observed above the Martian Noachian crust [1] require strong crustal remanent magnetization in the 15-60 A/m range over a thickness of 20-50 km [2,3]. The Martian rocks available for study in the form of meteorites do contain magnetic minerals (magnetite and/or pyrrhotite) but in too small amount to account for such strong remanent magnetizations [4]. Even though this contradiction was easily explained by the fact that Martian meteorites (mostly nakhlites and shergottites) are not representative of the Noachian Martian crust, we were left with no satisfactory candidate lithology to account for the Martian magnetic anomalies. The discovery in the Sahara of a new type of Martian meteorite (NWA 7034 [5] and subsequent paired stones which are hydrothermalized volcanic breccia) shed a new light on this question as it contains a much larger amount of ferromagnetic minerals than any other Martian meteorite. We present here a study of the magnetic properties of NWA 7034, together with a review of the magnetic properties of thirty other Martian meteorites. Magnetic measurements (including high and low temperature behavior and Mössbauer spectroscopy) show that NWA 7034 contains about 15 wt.% of magnetite with various degrees of substitution and maghemitization up to pure maghemite, in the pseudo-single domain size range. Pyrrhotite, a common mineral in other Martian meteorites is not detected. Although it is superparamagnetic and cannot carry remanent magnetization, nanophase goethite is present in significant amounts confirming that NWA 7034 is the most oxidized Martian meteorite studied so far, as already indicated by the presence of maghemite (this study) and pyrite [5]. These magnetic properties show that a kilometric layer of a lithology similar to NWA 7034 magnetized in a dynamo field would be enough to account for the strongest Martian magnetic anomalies. Although the petrogenesis of NWA 7034 is still debated, as the brecciation could be either

Marine magnetic anomalies off the southwest coast of India and their analysis

Digital Repository Service at National Institute of Oceanography (India)

Rao, D.G.; Bhattacharya, G.C.

Total magnetic intensity and bathymetric surveys were carried out in the offshore area of Ratnagiri on the western continental shelf of India and an isomagnetic anomalies map at a contour interval of 50 nT was prepared which reveals N-S trends...

MAGSAT anomaly map and continental drift

Science.gov (United States)

Lemouel, J. L. (Principal Investigator); Galdeano, A.; Ducruix, J.

1981-01-01

Anomaly maps of high quality are needed to display unambiguously the so called long wave length anomalies. The anomalies were analyzed in terms of continental drift and the nature of their sources is discussed. The map presented confirms the thinness of the oceanic magnetized layer. Continental magnetic anomalies are characterized by elongated structures generally of east-west trend. Paleomagnetic reconstruction shows that the anomalies found in India, Australia, and Antarctic exhibit a fair consistency with the African anomalies. It is also shown that anomalies are locked under the continents and have a fixed geometry.

New Magnetic Anomaly Map of the East Asia with Some Preliminary Tectonic Interpretations

Directory of Open Access Journals (Sweden)

Wen-Bin Doo

2015-01-01

Full Text Available Magnetic data provides basic information for geological and geophysical interpretation. In this study we compile recently collected (57 cruises survey and old (published and open access magnetic data. This compilation includes land, marine and aeromagnetic data acquired in the East Asia region. The newly acquired magnetic data are mainly concentrated mainly in the South China Sea (SCS (especially in the northern continental shelf, the northwestern part of the West Philippine Basin (WPB, and the East China Sea. The updated magnetic dataset is gridded with a spacing of one arc-minute. The new magnetic map provides new insights into the tectonic setting of East Asia. Analysis of the compiled data reveals several regional anomaly patterns: (1 the NE-SW trending high positive magnetic anomaly zone extending from southwest Taiwan to the area about 114.5°E114.5°E and 22°N22°N is pronounced; but it is less continuous southwest of the Penghu islands. In addition, the orientation of this high linear magnetic zone changes slightly in 118.5°E,118.5°E, 22.5°N22.5°N from N60°EN60°E - N50°E.N50°E. (2 Between the Gagua Ridge (GR and the Luzon-Okinawa Fracture Zone (LOFZ the marine magnetic stripes of the WPB exhibit a NW-SE orientation. This suggests that the seafloor spreading could be related to the first stage of the WPB east of the LOFZ. (3 The Urdaneta and Amami plateaus are associated with high magnetization zones. These high magnetization zones extend northwestward and are subducting beneath the Ryukyu Trench.

Highly macroscopically degenerated single-point ground states as source of specific heat capacity anomalies in magnetic frustrated systems

Science.gov (United States)

Jurčišinová, E.; Jurčišin, M.

2018-04-01

Anomalies of the specific heat capacity are investigated in the framework of the exactly solvable antiferromagnetic spin- 1 / 2 Ising model in the external magnetic field on the geometrically frustrated tetrahedron recursive lattice. It is shown that the Schottky-type anomaly in the behavior of the specific heat capacity is related to the existence of unique highly macroscopically degenerated single-point ground states which are formed on the borders between neighboring plateau-like ground states. It is also shown that the very existence of these single-point ground states with large residual entropies predicts the appearance of another anomaly in the behavior of the specific heat capacity for low temperatures, namely, the field-induced double-peak structure, which exists, and should be observed experimentally, along with the Schottky-type anomaly in various frustrated magnetic system.

Airborne gamma-ray and magnetic anomaly signatures of serpentinite in relation to soil geochemistry, northern California

Science.gov (United States)

McCafferty, A.E.; Van Gosen, B. S.

2009-01-01

Serpentinized ultramafic rocks and associated soils in northern California are characterized by high concentrations of Cr and Ni, low levels of radioelements (K, Th, and U) and high amounts of ferrimagnetic minerals (primarily magnetite). Geophysical attributes over ultramafic rocks, which include airborne gamma-ray and magnetic anomaly data, are quantified and provide indirect measurements on the relative abundance of radioelements and magnetic minerals, respectively. Attributes are defined through a statistical modeling approach and the results are portrayed as probabilities in chart and map form. Two predictive models are presented, including one derived from the aeromagnetic anomaly data and one from a combination of the airborne K, Th and U gamma-ray data. Both models distinguish preferential values within the aerogeophysical data that coincide with mapped and potentially unmapped ultramafic rocks. The magnetic predictive model shows positive probabilities associated with magnetic anomaly highs and, to a lesser degree, anomaly lows, which accurately locate many known ultramafic outcrops, but more interestingly, locate potentially unmapped ultramafic rocks, possible extensions of ultramafic bodies that dip into the shallow subsurface, as well as prospective buried ultramafic rocks. The airborne radiometric model shows positive probabilities in association with anomalously low gamma radiation measurements over ultramafic rock, which is similar to that produced by gabbro, metavolcanic rock, and water bodies. All of these features share the characteristic of being depleted in K, Th and U. Gabbro is the only rock type in the study area that shares similar magnetic properties with the ultramafic rock. The aerogeophysical model results are compared to the distribution of ultramafic outcrops and to Cr, Ni, K, Th and U concentrations and magnetic susceptibility measurements from soil samples. Analysis of the soil data indicates high positive correlation between

New methods for processing and interpreting marine magnetic anomalies: Application to structure, oil and gas exploration, Kuril forearc, Barents and Caspian seas

Directory of Open Access Journals (Sweden)

A.M. Gorodnitskiy

2013-01-01

In the southern and central parts of Barents Sea, tectonic blocks with widths of 30–100 km, and upper and lower boundaries of magnetic layers ranging from depths of 10 to 5 km and 18 to 30 km are calculated. Models of the magnetic layer underlying the Mezen Basin in an inland part of the White Sea–Barents Sea paleorift indicate depths to the lower boundary of the layer of 12–30 km. Weak local magnetic anomalies of 2–5 nT in the northern and central Caspian Sea were identified using the new methods, and drilling confirms that the anomalies are related to concentrations of hydrocarbon. Two layers causing magnetic anomalies are identified in the northern Caspian Sea from magnetic anomaly spectra. The upper layer lies immediately beneath the sea bottom and the lower layer occurs at depths between 30–40 m and 150–200 m.

Compensation of an attitude disturbance torque caused by magnetic substances in LEO satellites

Science.gov (United States)

Inamori, Takaya; Wang, Jihe; Saisutjarit, Phongsatorn; Ohsaki, Hiroyuki

This research considers an attitude disturbance torque caused by ferromagnetic substances in a LEO satellite. In most LEO satellite missions, a gravity gradient torque, solar pressure torque, aerodynamic torque, and magnetic dipole moment torque are considered for their attitude control systems, however, the effect of the ferromagnetic substances causing a disturbance torque in the geomagnetic field is not considered in previous satellite missions. The ferromagnetic substances such as iron cores of MTQs and a magnetic hysteresis damper for a passive attitude control system are used in various small satellites. These substances cause a disturbance torque which is almost the same magnitude of the dipole magnetic disturbance and the dominant disturbance in the worst cases. This research proposes a method to estimate and compensate for the effect of the ferromagnetic substances using an extended Kalman filter. From simulation results, the research concludes that the proposed method is useful and attractive for precise attitude control for LEO satellite missions.

Effects of edge magnetism on the Kohn anomalies of zigzag graphene nanoribbons

International Nuclear Information System (INIS)

Culchac, F J; Capaz, Rodrigo B

2016-01-01

The effects of edge magnetism on the Kohn anomaly (KA) of the G-band phonons of zigzag graphene nanoribbons (ZGNRs) are studied using a combination of the tight-binding and mean-field Hubbard models. We show that the opening of an energy gap, induced by magnetic ordering, significantly changes the KA effects, particularly for narrow ribbons in which the gap is larger than the phonon energy. Therefore, the G-band phonon frequency and lifetime are altered for a magnetically-ordered edge state with respect to an unpolarized edge state. The effects of temperature, ZGNR width, doping and transverse electric fields are systematically investigated. We propose using this effect to probe the magnetic order of edge states in graphene nanoribbons using Raman spectroscopy. (paper)

Incipient-signature identification of mechanical anomalies in a ship-borne satellite antenna system using an ensemble multiwavelet

International Nuclear Information System (INIS)

He, Shuilong; Zi, Yanyang; Chen, Jinglong; Chen, Binqiang; He, Zhengjia; Zhao, Chenlu; Yuan, Jing

2014-01-01

The instrumented tracking and telemetry ship with a ship-borne satellite antenna (SSA) is the critical device to ensure high quality of space exploration work. To effectively detect mechanical anomalies that can lead to unexpected downtime of the SSA, an ensemble multiwavelet (EM) is presented for identifying the anomaly related incipient-signatures within the measured dynamic signals. Rather than using a predetermined basis as in a conventional multiwavelet, an EM optimizes the matching basis which satisfactorily adapts to the anomaly related incipient-signatures. The construction technique of an EM is based on the conjunction of a two-scale similarity transform (TST) and lifting scheme (LS). For the technique above, the TST improves the regularity by increasing the approximation order of multiscaling functions, while subsequently the LS enhances the smoothness and localizability via utilizing the vanishing moment of multiwavelet functions. Moreover, combining the Hilbert transform with EM decomposition, we identify the incipient-signatures induced by the mechanical anomalies from the measured dynamic signals. A numerical simulation and two successful applications of diagnosis cases (a planetary gearbox and a roller bearing) demonstrate that the proposed technique is capable of dealing with the challenging incipient-signature identification task even though spectral complexity, as well as the strong amplitude/frequency modulation effect, is present in the dynamic signals. (paper)

RECURRENT SOLAR JETS INDUCED BY A SATELLITE SPOT AND MOVING MAGNETIC FEATURES

Energy Technology Data Exchange (ETDEWEB)

Chen, Jie; Su, Jiangtao; Yin, Zhiqiang; Priya, T. G.; Zhang, Hongqi; Xu, Haiqing; Yu, Sijie [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Liu, Jihong, E-mail: chenjie@bao.ac.cn [Shi Jiazhuang University, Shi Jiazhuang, 050035 (China)

2015-12-10

Recurrent and homologous jets were observed to the west edge of active region NOAA 11513 at the boundary of a coronal hole. We find two kinds of cancellations between opposite polarity magnetic fluxes, inducing the generation of recurrent jets. First, a satellite spot continuously collides with a pre-existing opposite polarity magnetic field and causes recurrent solar jets. Second, moving magnetic features, which emerge near the sunspot penumbra, pass through the ambient plasma and eventually collide with the opposite polarity magnetic field. Among these recurrent jets, a blowout jet that occurred around 21:10 UT is investigated. The rotation of the pre-existing magnetic field and the shear motion of the satellite spot accumulate magnetic energy, which creates the possibility for the jet to experience blowout right from the standard.

Extracting Ocean-Generated Tidal Magnetic Signals from Swarm Data Through Satellite Gradiometry

Science.gov (United States)

Sabaka, Terence J.; Tyler, Robert H.; Olsen, Nils

2016-01-01

Ocean-generated magnetic field models of the Principal Lunar, M2, and the Larger Lunar elliptic, N2, semidiurnal tidal constituents were estimated through a "Comprehensive Inversion" of the first 20.5 months of magnetic measurements from European Space Agency's (ESA) Swarm satellite constellation mission. While the constellation provides important north-south along-track gradiometry information, it is the unique low-spacecraft pair that allows for east-west cross-track gradiometry. This latter type is crucial in delivering an M2 estimate of similar quality with that derived from over 10 years of CHAMP satellite data but over a shorter interval, at higher altitude, and during more magnetically disturbed conditions. Recovered N2 contains nonoceanic signal but is highly correlated with theoretical models in regions of maximum oceanic amplitude. Thus, satellite magnetic gradiometry may eventually enable the monitoring of ocean electrodynamic properties at temporal resolutions of 1 to 2 years, which may have important implications for the inference of ocean temperature and salinity.

Neural networks based three-axis satellite attitude control using only magnetic torquers

International Nuclear Information System (INIS)

Sivaprakash, N.; Shanmugam, J.; Natarajan, P.

2005-01-01

Full text: Magnetic control is a favorable way to stabilize small satellites. Often, the hardware is simple and lightweight, and does not degrade or change mass over time. However, a magnetic control system does have some disadvantages and limitations. The control, which is in the form of magnetic moment, can only be applied perpendicular to the local magnetic field. In addition, there is uncertainty in the Earth magnetic field models due to the complicated dynamic nature of the field. Also, the magnetic hardware and the spacecraft can interact, causing both to behave in undesirable ways. To overcome these limitations some intelligence is incorporated in the controller. In this paper, control laws are developed to stabilize spacecraft on Three axes. The motivation for this project is ANUSAT, which is a micro-satellite under development at Anna University in collaboration with ISRO. This control could be carried out solely with satellite's magnetometer measurements and its position in orbit. The magnetic dipole moment for control is: M = K p (B o - B r ) + K d (dB o /dt - dB r /dt) Where B o is the measured magnetic field, B r is the reference magnetic field, and K p and K d are the control position and rate gains respectively. The value of the controller gains are selected by the Intelligent Neural Network System in the feedback path. Control laws are numerically tested to show that the magnetic control system works within resolution limits

The Geopotential Research Mission - Mapping the near earth gravity and magnetic fields

Science.gov (United States)

Taylor, P. T.; Keating, T.; Smith, D. E.; Langel, R. A.; Schnetzler, C. C.; Kahn, W. D.

1983-01-01

The Geopotential Research Mission (GRM), NASA's low-level satellite system designed to measure the gravity and magnetic fields of the earth, and its objectives are described. The GRM will consist of two, Shuttle launched, satellite systems (300 km apart) that will operate simultaneously at a 160 km circular-polar orbit for six months. Current mission goals include mapping the global geoid to 10 cm, measuring gravity-field anomalies to 2 mgal with a spatial resolution of 100 km, detecting crustal magnetic anomalies of 100 km wavelength with 1 nT accuracy, measuring the vectors components to + or - 5 arc sec and 5 nT, and computing the main dipole or core field to 5 nT with a 2 nT/year secular variation detection. Resource analysis and exploration geology are additional applications considered.

An alternative 3D inversion method for magnetic anomalies with depth resolution

Directory of Open Access Journals (Sweden)

M. Chiappini

2006-06-01

Full Text Available This paper presents a new method to invert magnetic anomaly data in a variety of non-complex contexts when a priori information about the sources is not available. The region containing magnetic sources is discretized into a set of homogeneously magnetized rectangular prisms, polarized along a common direction. The magnetization distribution is calculated by solving an underdetermined linear system, and is accomplished through the simultaneous minimization of the norm of the solution and the misfit between the observed and the calculated field. Our algorithm makes use of a dipolar approximation to compute the magnetic field of the rectangular blocks. We show how this approximation, in conjunction with other correction factors, presents numerous advantages in terms of computing speed and depth resolution, and does not affect significantly the success of the inversion. The algorithm is tested on both synthetic and real magnetic datasets.

From silk to satellite: Half a century of ocean colour anomalies in the Northeast Atlantic

KAUST Repository

Raitsos, Dionysios E.

2014-04-23

Changes in phytoplankton dynamics influence marine biogeochemical cycles, climate processes, and food webs, with substantial social and economic consequences. Large-scale estimation of phytoplankton biomass was possible via ocean colour measurements from two remote sensing satellites - the Coastal Zone Colour Scanner (CZCS, 1979-1986) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS, 1998-2010). Due to the large gap between the two satellite eras and differences in sensor characteristics, comparison of the absolute values retrieved from the two instruments remains challenging. Using a unique in situ ocean colour dataset that spans more than half a century, the two satellite-derived chlorophyll-a (Chl-a) eras are linked to assess concurrent changes in phytoplankton variability and bloom timing over the Northeast Atlantic Ocean and North Sea. Results from this unique re-analysis reflect a clear increasing pattern of Chl-a, a merging of the two seasonal phytoplankton blooms producing a longer growing season and higher seasonal biomass, since the mid-1980s. The broader climate plays a key role in Chl-a variability as the ocean colour anomalies parallel the oscillations of the Northern Hemisphere Temperature (NHT) since 1948. © 2013 John Wiley & Sons Ltd.

From silk to satellite: Half a century of ocean colour anomalies in the Northeast Atlantic

KAUST Repository

Raitsos, Dionysios E.; Pradhan, Yaswant; Lavender, Sam; Hoteit, Ibrahim; McQuatters-Gollop, Abigail L.; Reid, Philip Chris; Richardson, Anthony J.

2014-01-01

Changes in phytoplankton dynamics influence marine biogeochemical cycles, climate processes, and food webs, with substantial social and economic consequences. Large-scale estimation of phytoplankton biomass was possible via ocean colour measurements from two remote sensing satellites - the Coastal Zone Colour Scanner (CZCS, 1979-1986) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS, 1998-2010). Due to the large gap between the two satellite eras and differences in sensor characteristics, comparison of the absolute values retrieved from the two instruments remains challenging. Using a unique in situ ocean colour dataset that spans more than half a century, the two satellite-derived chlorophyll-a (Chl-a) eras are linked to assess concurrent changes in phytoplankton variability and bloom timing over the Northeast Atlantic Ocean and North Sea. Results from this unique re-analysis reflect a clear increasing pattern of Chl-a, a merging of the two seasonal phytoplankton blooms producing a longer growing season and higher seasonal biomass, since the mid-1980s. The broader climate plays a key role in Chl-a variability as the ocean colour anomalies parallel the oscillations of the Northern Hemisphere Temperature (NHT) since 1948. © 2013 John Wiley & Sons Ltd.

Sliding Mode Attitude Control for Magnetic Actuated Satellite

DEFF Research Database (Denmark)

Wisniewski, Rafal

1998-01-01

control torques can only be generated perpendicular to the local geomagnetic field vector. This has been a serious obstacle for using magnetorquer based control for three-axis attitude control. This paper deals with three-axis stabilization of a low earth orbit satellite. The problem of controlling...... the spacecraft attitude using only magnetic torquing is realized in the form of the sliding mode control. A three dimensional sliding manifold is proposed, and it is shown that the satellite motion on the sliding manifold is asymptotically stable...

Structural model Soapaga failure from spectral correlation and magnetic gravity anomalies in the eastern cordillera, Colombia

International Nuclear Information System (INIS)

Rodriguez Diana Marcela; Hernandez Orlando; Kammer Andreas

2009-01-01

The aim of this research is to apply spectral correlation, local favorability indexes and Poisson's theorem as numerical methods for data processing and interpretation of potential field data associated with structural features; these techniques are applied to theoretical and real gravity and magnetic data of the Soapaga fault, located in the Boyaca Department, in the eastern Andean Mountains. Theoretical data of the Soapaga fault was obtained by forward modeling of geological and structural sections. Real data of the Soapaga fault included compiled gravity data and acquired magnetic data along four profiles oriented perpendicular to the fault. As a result, the geometry of the fault and its structural characteristics were obtained by interactive forward and inverse modeling. This methodology allows highlighting anomaly trends associated with density and magnetic susceptibility contrast that occur along the Soapaga fault zone. Additionally, this work provides a quantitative approach to establish the relationship between gravity and magnetic anomalies, supported by a rigorous mathematical methodology rather than isolated data interpretation to better understand the gravity and magnetic signatures of outcropping and hidden structural features.

Regional magnetic anomalies, crustal strength, and the location of the northern Cordilleran fold-and-thrust belt

Science.gov (United States)

Saltus, R.W.; Hudson, T.L.

2007-01-01

The northern Cordilleran fold-and-thrust belt in Canada and Alaska is at the boundary between the broad continental margin mobile belt and the stable North American craton. The fold-and-thrust belt is marked by several significant changes in geometry: cratonward extensions in the central Yukon Territory and northeastern Alaska are separated by marginward re-entrants. These geometric features of the Cordilleran mobile belt are controlled by relations between lithospheric strength and compressional tectonic forces developed along the continental margin. Regional magnetic anomalies indicate deep thermal and compositional characteristics that contribute to variations in crustal strength. Our detailed analysis of one such anomaly, the North Slope deep magnetic high, helps to explain the geometry of the fold-and-thrust front in northern Alaska. This large magnetic anomaly is inferred to reflect voluminous mafic magmatism in an old (Devonian?) extensional domain. The presence of massive amounts of malic material in the lower crust implies geochemical depletion of the underlying upper mantle, which serves to strengthen the lithosphere against thermal erosion by upper mantle convection. We infer that deep-source magnetic highs are an important indicator of strong lower crust and upper mantle. This stronger lithosphere forms buttresses that play an important role in the structural development of the northern Cordilleran fold-and-thrust belt. ?? 2007 The Geological Society of America.

The specific features of gold ore provinces of the south of Siberia in a magnetic field at ground height and heights of flight of satellite Champ.

Science.gov (United States)

Litvinova, Tamara; Petrova, Alevtina

2010-05-01

The specific features of gold ore provinces of the south of Siberia in a magnetic field at ground height and heights of flight of satellite Champ. T.Litvinova -All-Russian Geological Research Institute (VSEGEI) A. Petrova - St. Petersburg, SPbF IZMIRAN, Russian Academy of Sciences, St. Petersburg For allocation of specific features known gold ore objects (Olimpiadninskoje, Suchoi Log, etc.) is executed the morphological analysis of the magnetic field received on materials of aeromagnetic data and satellite measurements at heights of 100 and 400 km. On the ground data on a map of magnetic anomalies of Russia of scale 1:2 500000 of 50 km on the extended structures crossing known gold ore deposits and promising ore units have been constructed geomagnetic and densitys sections up to depth. On geomagnetic and densitys sections to known large gold ore to deposits are dated deep synvertical the permeable zones described by a synlenticular -layered structure. Extended horizons of not magnetic formations are located on depths about 10, 12, 15-18, 30 and 40 km. On deep densitys sections reference sites ¬ the Suchoi Log, Olimpiadninskoje and Vodorazdelnoje ¬ is characterized by zones of inversion of density. Areas of the loosened breeds are dated to synvertical to deep zones of hydrothermal and fluid study of breeds inside which the loosened lenses in intervals of depths from 2 up to 5 km are formed, 8-13 km, 18-20 and 25-30 km of 35-40 km within the limits of the bottom bark. The analysis of a magnetic field has shown, that gold mineralization in researched region is dated for zones of long-living regional explosive infringements, to permeable terrigenous to thicknesses of depressions, to adjournment depression structures in units of crossing of tectonofluid zones of diagonal orientation. Terrigenous adjournment depression structures are shown on a geomagnetic section as the powerful deflections filled with low-magnetic thicknesses. These deflections are dated to

Expanding the spectrum of human ganglionic eminence region anomalies on fetal magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Righini, Andrea; Parazzini, Cecilia; Izzo, Giana [Children' s Hospital ' ' V. Buzzi' ' , Department of Radiology and Neuroradiology, Milan (Italy); Cesaretti, Claudia [Children' s Hospital ' ' V. Buzzi' ' , Department of Radiology and Neuroradiology, Milan (Italy); Ospedale Maggiore Policlinico, Medical Genetics Unit, Fondazione I.R.C.C.S. Ca' Granda, Milan (Italy); Conte, Giorgio [Children' s Hospital ' ' V. Buzzi' ' , Department of Radiology and Neuroradiology, Milan (Italy); University of Milan, Department of Health Sciences, Milan (Italy); Frassoni, Carolina; Inverardi, Francesca [Fondazione I.R.C.C.S. Istituto Neurologico ' ' C. Besta' ' , Clinical Epileptology and Experimental Neurophysiology Unit, Milan (Italy); Bulfamante, Gaetano; Avagliano, Laura [San Paolo Hospital, Division of Human Pathology, Milan (Italy); Rustico, Mariangela [Children' s Hospital ' ' V. Buzzi' ' , Department of Obstetrics and Gynaecology, Prenatal Diagnosis, Milan (Italy)

2016-03-15

Ganglionic eminence (GE) is a transient fetal brain structure that harvests a significant amount of precursors of cortical GABA-ergic interneurons. Prenatal magnetic resonance (MR) imaging features of GE anomalies (i.e., cavitations) have already been reported associated with severe micro-lissencephaly. The purpose of this report was to illustrate the MR imaging features of GE anomalies in conditions other than severe micro-lissencephalies. Among all the fetuses submitted to prenatal MR imaging at our center from 2005 to 2014, we collected eight cases with GE anomalies and only limited associated brain anomalies. The median gestational age at the time of MR imaging was 21 weeks ranging from 19 to 29 weeks. Two senior pediatric neuroradiologists categorized the anomalies of the GE region in two groups: group one showing cavitation in the GE region and group two showing enlarged GE region. For each fetal case, associated cranial anomalies were also reported. Five out of the eight cases were included in group one and three in group two. Besides the GE region abnormality, all eight cases had additional intracranial anomalies, such as mild partial callosal agenesis, vermian hypoplasia and rotation, cerebellar hypoplasia, ventriculomegaly, enlarged subarachnoid spaces, molar tooth malformation. Ultrasound generally detected most of the associated intracranial anomalies, prompting the MR investigation; on the contrary in none of the cases, GE anomalies had been detected by ultrasound. Our observation expands the spectrum of human GE anomalies, demonstrating that these may take place also without associated severe micro-lissencephalies. (orig.)

Expanding the spectrum of human ganglionic eminence region anomalies on fetal magnetic resonance imaging

International Nuclear Information System (INIS)

Righini, Andrea; Parazzini, Cecilia; Izzo, Giana; Cesaretti, Claudia; Conte, Giorgio; Frassoni, Carolina; Inverardi, Francesca; Bulfamante, Gaetano; Avagliano, Laura; Rustico, Mariangela

2016-01-01

Ganglionic eminence (GE) is a transient fetal brain structure that harvests a significant amount of precursors of cortical GABA-ergic interneurons. Prenatal magnetic resonance (MR) imaging features of GE anomalies (i.e., cavitations) have already been reported associated with severe micro-lissencephaly. The purpose of this report was to illustrate the MR imaging features of GE anomalies in conditions other than severe micro-lissencephalies. Among all the fetuses submitted to prenatal MR imaging at our center from 2005 to 2014, we collected eight cases with GE anomalies and only limited associated brain anomalies. The median gestational age at the time of MR imaging was 21 weeks ranging from 19 to 29 weeks. Two senior pediatric neuroradiologists categorized the anomalies of the GE region in two groups: group one showing cavitation in the GE region and group two showing enlarged GE region. For each fetal case, associated cranial anomalies were also reported. Five out of the eight cases were included in group one and three in group two. Besides the GE region abnormality, all eight cases had additional intracranial anomalies, such as mild partial callosal agenesis, vermian hypoplasia and rotation, cerebellar hypoplasia, ventriculomegaly, enlarged subarachnoid spaces, molar tooth malformation. Ultrasound generally detected most of the associated intracranial anomalies, prompting the MR investigation; on the contrary in none of the cases, GE anomalies had been detected by ultrasound. Our observation expands the spectrum of human GE anomalies, demonstrating that these may take place also without associated severe micro-lissencephalies. (orig.)

Using Low Resolution Satellite Imagery for Yield Prediction and Yield Anomaly Detection

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Oscar Rojas

2013-04-01

Full Text Available Low resolution satellite imagery has been extensively used for crop monitoring and yield forecasting for over 30 years and plays an important role in a growing number of operational systems. The combination of their high temporal frequency with their extended geographical coverage generally associated with low costs per area unit makes these images a convenient choice at both national and regional scales. Several qualitative and quantitative approaches can be clearly distinguished, going from the use of low resolution satellite imagery as the main predictor of final crop yield to complex crop growth models where remote sensing-derived indicators play different roles, depending on the nature of the model and on the availability of data measured on the ground. Vegetation performance anomaly detection with low resolution images continues to be a fundamental component of early warning and drought monitoring systems at the regional scale. For applications at more detailed scales, the limitations created by the mixed nature of low resolution pixels are being progressively reduced by the higher resolution offered by new sensors, while the continuity of existing systems remains crucial for ensuring the availability of long time series as needed by the majority of the yield prediction methods used today.

A lithospheric magnetic field model derived from the Swarm satellite magnetic field measurements

Science.gov (United States)

Hulot, G.; Thebault, E.; Vigneron, P.

2015-12-01

The Swarm constellation of satellites was launched in November 2013 and has since then delivered high quality scalar and vector magnetic field measurements. A consortium of several research institutions was selected by the European Space Agency (ESA) to provide a number of scientific products which will be made available to the scientific community. Within this framework, specific tools were tailor-made to better extract the magnetic signal emanating from Earth's the lithospheric. These tools rely on the scalar gradient measured by the lower pair of Swarm satellites and rely on a regional modeling scheme that is more sensitive to small spatial scales and weak signals than the standard spherical harmonic modeling. In this presentation, we report on various activities related to data analysis and processing. We assess the efficiency of this dedicated chain for modeling the lithospheric magnetic field using more than one year of measurements, and finally discuss refinements that are continuously implemented in order to further improve the robustness and the spatial resolution of the lithospheric field model.

Near-Curie magnetic anomaly at the Ni/C interface observed by Electron Holography

DEFF Research Database (Denmark)

Ferrari, Loris; Matteucci, Giorgio; Schofield, Marvin A

2010-01-01

We analyze with electron holography carried out in a transmission electron microscope the near-Curie behavior of magnetism at the edge of a Nickel thin film coated with Carbon. In-situ experiments with finely controlled variations of the sample temperature reveal an anomaly in the ferromagnetic...

Magnetic anomalies across the transitional crust of the passive conjugate margins of the North Atlantic: Iberian Abyssal Plain/Northern Newfoundland Basin

Science.gov (United States)

Srivastava, S.; Sibuet, J.; Manatschal, G.

2005-12-01

The magma starved Iberia Abyssal Plain (IAP) margin off Iberia is probably one of the most studied non-volcanic continental margin in the world. Numerous multi-channel seismic cruises, detailed refraction surveys, and ODP drilling (Legs 149 and 173) have been carried out across it. Yet serious disagreement exists about the nature and mode of emplacement of the transitional crust which lies between true continental and true oceanic crusts in this region. One group regards this crust to be excessively thinned continental crust through which mantle was exhumed while the other group regards it to be oceanic crust, a mixture of basalt and mantle material, formed during ultraslow seafloor spreading. However, neither the drilling, which was carried out only on the basement highs and recovered serpentinized peridotites together with some gabbroic material, nor the detailed refraction measurements have been of much help in solving this dispute because the velocity values in this region neither correspond to true volcanic materials nor to true continental rocks. Similarly the magnetic anomalies in this region have been also interpreted differently by the two groups. One group negates the existence of any seafloor spreading type anomalies over the transition zone. On the other hand, examination of surface and deep-tow magnetic data from conjugate sections of the margins across this part of the North Atlantic shows a good correlation between them. The prime reason for such differences in the interpretation of magnetic data lies in the low amplitude of the surface magnetic anomalies forming the M sequence anomalies in this region compared to those of similar age present in the Central Atlantic. We demonstrate here that the symmetrical magnetic anomalies identified within the transitional zones between Iberia and North America, and across passive margins in general where separation between plates has been very slow, are caused by the serpentinization of the exhumed mantle rocks

Magnetic study of the low temperature anomalies in the underdoped PrBCO compound

Science.gov (United States)

Lahoubi, Mahieddine

2018-05-01

The low temperature anomalous magnetic properties of a non-superconducting PrBCO6+x compound in an underdoped oxygen state of concentration (x = 0.44) are characterized by paraprocess magnetic susceptibility χH(T) measurements carried out as a function of temperature T under different values of a DC magnetic field H up to 110 kOe. The derivatives dχH(T)/dT curves reveal a significant reduction with increasing H in the Néel temperature TN = 9 K of the Pr antiferromagnetic (AFM) ordering for which the transition subsists at 100 kOe. The small anomaly at T2 = 6-7 K is confirmed at 20 kOe and the previous spin reorientation attributed to this transition temperature seems to be suppressed above 60 kOe. The well defined anomaly in the vicinity of the low-critical point Tcr = 4-5 K which occurs simultaneously, is still present when the strength of H is increased up to 100 kOe. Weak field induced phase transitions are observed between T2 and TN at a low transition-field (Ht<11 kOe) in the differential magnetic susceptibility dMT(H)/dH as a function of H deduced from the isothermal magnetizations MT(H) with H up to 21 kOe, whereas a weak ferromagnetic behavior of the Pr sublattice appears below Tcr. The magnetic field effects give rise to more evidence for the Pr-Cu(2) coupling with 'exchange-frustrated AFM' interactions and ascertain the main role of the Pr sublattice whereas the Cu(2) sublattice seems to be less efficient.

The utility of ultrasound and magnetic resonance imaging versus surgery for the characterization of müllerian anomalies in the pediatric and adolescent population.

Science.gov (United States)

Santos, X M; Krishnamurthy, R; Bercaw-Pratt, J L; Dietrich, J E

2012-06-01

To evaluate the utility of transabdominal ultrasound and magnetic resonance imaging in the evaluation of American Society for Reproductive Medicine (†)(ASRM)-classified müllerian anomalies compared to surgical findings in the pediatric and adolescent population. Retrospective chart review. Tertiary academic center. Thirty-eight patients with müllerian anomalies seen in our pediatric and adolescent gynecology clinic were identified both on the basis of ICD-9 codes and having magnetic resonance imaging at Texas Children's Hospital between 2004 and 2009. None. Correlation among transabdominal ultrasound and magnetic resonance imaging findings with surgical findings. Mean age was 12.2 (± 4.1) years. Twenty-eight patients underwent magnetic resonance imaging and required surgical intervention, and 88.5% demonstrated correlative consistency with surgical findings. Twenty-two patients underwent ultrasound, magnetic resonance imaging, and surgery, which revealed consistency among ultrasound and surgical findings (59.1%) and consistency among magnetic resonance imaging and surgical findings (90.9%). In ASRM diagnoses evaluated by magnetic resonance imaging, surgical findings correlated in 92% (Pearson 0.89). Overall, 55.2% of patients had a renal malformation. Magnetic resonance imaging is the gold standard imaging modality for müllerian anomalies and is an effective technique for noninvasive evaluation and accurate classification of the type of anomaly in the pediatric and adolescent population. Magnetic resonance imaging should be considered as an adjunct to transabdominal ultrasound to evaluate müllerian anomalies. Copyright © 2012 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

Observation of high energy electrons and protons in the South Atlantic geomagnetic anomaly by Ohzora Satellite

International Nuclear Information System (INIS)

Nagata, K.; Murakami, H.; Nakamoto, A.; Hasebe, N.; Kikuche, J.; Doke, T.

1988-01-01

Observed results of the high energy electrons (0.19 - 3.2 MeV) and protons (0.58 - 35 MeV) of the South Atlantic Geomagnetic Anomaly are presented. Two silicon Δ E-E telescopes on the ohzora satellite (EXOS-C, 1984-15A) were used to observe the high energy particle and the maximum intensity of electrons and protons. The powers of energy spectra above 1 MeV have different values from energy region below 1 MeV. The electron and proton intensities are greatest at pitch angle maximized at 90 0 . (author) [pt

Marine magnetic anomalies over the Direction bank, off Bombay western continental shelf of India

Digital Repository Service at National Institute of Oceanography (India)

SubbaRaju, L.V.; Subrahmanyam, V.

Total magnetic intensity data were collected over the Direction Bank, off Bombay on the western continental shelf of India and the isomagnetic anomaly map prepared at a contour interval of 25nT show NNW-SSE trend resemble those of the Dharwarians...

The relationship of thermospheric density anomaly with electron temperature, small-scale FAC, and ion up-flow in the cusp region, as observed by CHAMP and DMSP satellites

Directory of Open Access Journals (Sweden)

G. N. Kervalishvili

2013-03-01

Full Text Available We present in a statistical study a comparison of thermospheric mass density enhancements (ρrel with electron temperature (Te, small-scale field-aligned currents (SSFACs, and vertical ion velocity (Vz at high latitudes around noon magnetic local time (MLT. Satellite data from CHAMP (CHAllenging Minisatellite Payload and DMSP (Defense Meteorological Satellite Program sampling the Northern Hemisphere during the years 2002–2005 are used. In a first step we investigate the distribution of the measured quantities in a magnetic latitude (MLat versus MLT frame. All considered variables exhibit prominent peak amplitudes in the cusp region. A superposed epoch analysis was performed to examine causal relationship between the quantities. The occurrence of a thermospheric relative mass density anomaly, ρrel >1.2, in the cusp region is defining an event. The location of the density peak is taken as a reference latitude (Δ MLat = 0°. Interestingly, all the considered quantities, SSFACs, Te, and Vz are co-located with the density anomaly. The amplitudes of the peaks exhibit different characters of seasonal variation. The average relative density enhancement of the more prominent density peaks considered in this study amounts to 1.33 during all seasons. As expected, SSFACs are largest in summer with average amplitudes equal to 2.56 μA m−2, decaying to 2.00 μA m−2 in winter. The event related enhancements of Te and Vz are both largest in winter (Δ Te =730 K, Vz =136 m s−1 and smallest in summer (Δ Te = 377 K, Vz = 57 m s−1. Based on the similarity of the seasonal behaviour we suggest a close relationship between these two quantities. A correlation analysis supports a linear relation with a high coefficient greater than or equal to 0.93, irrespective of season. Our preferred explanation is that dayside reconnection fuels Joule heating of the thermosphere causing air upwelling and at the same time heating of the electron gas that pulls up ions

Touchless attitude correction for satellite with constant magnetic moment

Science.gov (United States)

Ao, Hou-jun; Yang, Le-ping; Zhu, Yan-wei; Zhang, Yuan-wen; Huang, Huan

2017-09-01

Rescue of satellite with attitude fault is of great value. Satellite with improper injection attitude may lose contact with ground as the antenna points to the wrong direction, or encounter energy problems as solar arrays are not facing the sun. Improper uploaded command may set the attitude out of control, exemplified by Japanese Hitomi spacecraft. In engineering practice, traditional physical contact approaches have been applied, yet with a potential risk of collision and a lack of versatility since the mechanical systems are mission-specific. This paper puts forward a touchless attitude correction approach, in which three satellites are considered, one having constant dipole and two having magnetic coils to control attitude of the first. Particular correction configurations are designed and analyzed to maintain the target's orbit during the attitude correction process. A reference coordinate system is introduced to simplify the control process and avoid the singular value problem of Euler angles. Based on the spherical triangle basic relations, the accurate varying geomagnetic field is considered in the attitude dynamic mode. Sliding mode control method is utilized to design the correction law. Finally, numerical simulation is conducted to verify the theoretical derivation. It can be safely concluded that the no-contact attitude correction approach for the satellite with uniaxial constant magnetic moment is feasible and potentially applicable to on-orbit operations.

Congenital varitans and anomalies of the pancreas and pancreatic duct: Imaging by magnetic resonance cholangiopancreaticography and multidetector computed tomography

Energy Technology Data Exchange (ETDEWEB)

Tuerkvatan, Aysel; Yener, Ouzlem [Dept. of Radiology, Tuerkiye Yueksek Ihtisas Hospital, Ankara (Turkmenistan); Erden, Aysel [Dept. of Radiology, Ankara University School of Medicine, Antalya (Turkmenistan); Tuerkoglu, Mehmet Akif [Dept. of General Surgery, Antalya University School of Medicine, Antalya (Turkmenistan)

2013-12-15

Though congenital anomalies of the pancreas and pancreatic duct are relatively uncommon and they are often discovered as an incidental finding in asymptomatic patients, some of these anomalies may lead to various clinical symptoms such as recurrent abdominal pain, nausea and vomiting. Recognition of these anomalies is important because these anomalies may be a surgically correctable cause of recurrent pancreatitis or the cause of gastric outlet obstruction. An awareness of these anomalies may help in surgical planning and prevent inadvertent ductal injury. The purpose of this article is to review normal pancreatic embryology, the appearance of ductal anatomic variants and developmental anomalies of the pancreas, with emphasis on magnetic resonance cholangiopancreaticography and multidetector computed tomography.

Registration of ELF waves in rocket-satellite experiment with plasma injection

Science.gov (United States)

Korobeinikov, V. G.; Oraevskii, V. N.; Ruzhin, Iu. Ia.; Sobolev, Ia. P.; Skomarovskii, V. S.; Chmyrev, V. M.; Namazov, C. A.; Pokhunkov, A. A.; Nesmeianov, V. I.

1992-12-01

Two rocket KOMBI-SAMA experiments with plasma injection at height 100-240 km were performed in August 1987 in the region of Brazilian magnetic anomaly (L = 1.25). The launching time of the rocket was determined so that plasma injection was at the time when COSMOS 1809 satellite passed as close as possible to magnetic tube of injection. Caesium plasma jet was produced during not less than 300 s by an electric plasma generator separated from the payload. When the satellite passed the geomagnetic tube intersecting the injection region an enhancement of ELF emission at 140 Hz, 450 Hz by a factor of 2 was registered on board the satellite. An enhancement of energetic particle flux by a factor of 4-5 was registered on board the rocket. Observed ELF emission below 100 Hz is interpreted as the generation of oblique electromagnetic ion-cyclotron waves due to drift plasma instability at the front of the plasma jet.

The role of magnetic resonance imaging in prenatal diagnosis of fetal anomalies.

Science.gov (United States)

Bekker, M N; van Vugt, J M

2001-06-01

Magnetic resonance imaging (MR) has become a useful adjuvant in evaluating fetal structural anomalies when ultrasound (US) is equivocal. It has a significant promise in confirming a US suspected abnormality and providing new information that was previously not available. The first studies on prenatal MR were hindered by fetal motion and long acquisition times. This degraded imaging and, therefore, maternal or fetal sedation was needed. Since fast and ultrafast MR with scan times of <1 s have become available, the amount of motion artifacts is decreased and sedation is no longer needed.MR has proved to be especially beneficial in detecting CNS anomalies. Agenesis of the corpus callosum, migration abnormalities and abnormalities of the posterior fossa are better seen on MR. Masses in the fetal neck and thorax can be identified on MR, as some abdominal anomalies. However, the fetal skeletal is difficult to visualize with MR. In the future, it is most likely that real time MR will become clinically available which would improve MR imaging even more.

Gravitational Anomaly and Transport Phenomena

International Nuclear Information System (INIS)

Landsteiner, Karl; Megias, Eugenio; Pena-Benitez, Francisco

2011-01-01

Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid.

Aeromagnetic anomalies over faulted strata

Science.gov (United States)

Grauch, V.J.S.; Hudson, Mark R.

2011-01-01

High-resolution aeromagnetic surveys are now an industry standard and they commonly detect anomalies that are attributed to faults within sedimentary basins. However, detailed studies identifying geologic sources of magnetic anomalies in sedimentary environments are rare in the literature. Opportunities to study these sources have come from well-exposed sedimentary basins of the Rio Grande rift in New Mexico and Colorado. High-resolution aeromagnetic data from these areas reveal numerous, curvilinear, low-amplitude (2–15 nT at 100-m terrain clearance) anomalies that consistently correspond to intrasedimentary normal faults (Figure 1). Detailed geophysical and rock-property studies provide evidence for the magnetic sources at several exposures of these faults in the central Rio Grande rift (summarized in Grauch and Hudson, 2007, and Hudson et al., 2008). A key result is that the aeromagnetic anomalies arise from the juxtaposition of magnetically differing strata at the faults as opposed to chemical processes acting at the fault zone. The studies also provide (1) guidelines for understanding and estimating the geophysical parameters controlling aeromagnetic anomalies at faulted strata (Grauch and Hudson), and (2) observations on key geologic factors that are favorable for developing similar sedimentary sources of aeromagnetic anomalies elsewhere (Hudson et al.).

Detection Range of Airborne Magnetometers in Magnetic Anomaly Detection

Directory of Open Access Journals (Sweden)

Chengjing Li

2015-11-01

Full Text Available Airborne magnetometers are utilized for the small-range search, precise positioning, and identification of the ferromagnetic properties of underwater targets. As an important performance parameter of sensors, the detection range of airborne magnetometers is commonly set as a fixed value in references regardless of the influences of environment noise, target magnetic properties, and platform features in a classical model to detect airborne magnetic anomalies. As a consequence, deviation in detection ability analysis is observed. In this study, a novel detection range model is proposed on the basis of classic detection range models of airborne magnetometers. In this model, probability distribution is applied, and the magnetic properties of targets and the environment noise properties of a moving submarine are considered. The detection range model is also constructed by considering the distribution of the moving submarine during detection. A cell-averaging greatest-of-constant false alarm rate test method is also used to calculate the detection range of the model at a desired false alarm rate. The detection range model is then used to establish typical submarine search probabilistic models. Results show that the model can be used to evaluate not only the effects of ambient magnetic noise but also the moving and geomagnetic features of the target and airborne detection platform. The model can also be utilized to display the actual operating range of sensor systems.

The long-term effects of space weather on satellite operations

Directory of Open Access Journals (Sweden)

D. T. Welling

2010-06-01

Full Text Available Integrated lifetime radiation damage may cause spacecraft to become more susceptible to operational anomalies by changing material characteristics of electronic components. This study demonstrates and quantifies the impact of these effects by examining the National Oceanic and Atmospheric Administration (NOAA National Geophysical Data Center (NGDC satellite anomaly database. Energetic particle data from the Geostationary Operational Environmental Satellites (GOES is used to construct the total lifetime particle exposure a satellite has received at the epoch of an anomaly. These values are compared to the satellite's chronological age and the average exposure per year (calculated over two solar cycles. The results show that many anomalies occur on satellites that have received a total lifetime high-energy particle exposure that is disproportionate to their age. In particular, 10.8% of all events occurred on satellites that received over two times more 20 to 40 MeV proton lifetime particle exposure than predicted using an average annual mean. This number inflates to 35.2% for 40 to 80 MeV protons and 33.7% for ≥2 MeV electrons. Overall, 73.5% of all anomalies occurred on a spacecraft that had experienced greater than two times the expected particle exposure for one of the eight particle populations used in this study. Simplistically, this means that the long term radiation background exposure matters, and that if the background radiation is elevated during the satellite's lifetime, the satellite is likely to experience more anomalies than satellites that have not been exposed to the elevated environment.

Modeling of the Foca-Uzunada magnetic anomaly and thermal structure in the gulf of Izmir, western Turkey

Science.gov (United States)

Aydemir, Attila; Bilim, Funda; Cifci, Gunay; Okay, Seda

2018-05-01

The Gulf of Izmir (GoI) is one of the largest gulfs in the Aegean Sea, Turkey. There is a large magnetic anomaly extending in the NE-SW direction between Foca and Uzunada (Uzun Island) in the gulf. Previously, Curie Point Depth (CPD), geothermal gradient, heat-flow and radiogenic heat production maps of the onshore part of the Aegean region were constructed from the aeromagnetic data. In this study, the same maps except radiogenic heat production map are presented for the offshore part and the largest magnetic anomaly in the northern part of the gulf is focused, particularly. As a result, the thermal structure of GoI is clearly defined and according to the results of this study, CPD values were found from 7 km in the NE of Foca to 10 km through the south of the gulf. The geothermal gradient values vary between 50 and 80 °C/km. Maximum heat flow values around the anomaly are calculated as 200 and 215 mW/m2 according to the thermal conductivity coefficients of 2.5 W m-1 K-1 and 2.7 W m-1 K-1, respectively. Although the anomaly is located in the Izmir Gulf; CPD, geothermic gradient, heat flow anomalies are shifted through the north of Foca and Aliaga towns in the Candarli Bay. This prominent anomaly in the Gulf of Izmir is associated with the magmatics that were encountered at 969 m in the Foca-1 well although it was drilled about 2 km away from the outermost closed contour of the magnetic anomaly. The anomaly is also modeled three dimensionally (3D) in this study. In the model map, the top of the causative body is completely located in the outer part of the gulf, and is very shallow at about 0.5 km while its bottom is inclined through the west of Cigli and Menemen. From this viewpoint, it is possible to suggest that the causative body is inclined through the Foca Peninsula. However, its closed contours are in the NE direction, through the Candarli Bay. Top depth of the causative body is also calculated from the basement horizon on the seismic sections crossing this

Cosmic rays and other space weather effects influenced on satellite operation, technologies, biosphere and people health

Science.gov (United States)

Lev, Dorman

2016-07-01

Satellite anomalies (or malfunctions), including total distortion of electronics and loose of some satellites cost for Insurance Companies billions dollars per year. During especially active periods the probability of big satellite anomalies and their loosing increased very much. Now, when a great number of civil and military satellites are continuously worked for our practice life, the problem of satellite anomalies became very important. Many years ago about half of satellite anomalies were caused by technical reasons (for example, for Russian satellites Kosmos), but with time with increasing of production quality, this part became smaller and smaller. The other part, which now is dominated, caused by different space weather effects (energetic particles of CR and generated/trapped in the magnetosphere, and so on). We consider only satellite anomalies not caused by technical reasons: the total number of such anomalies about 6000 events, and separately for high and low altitude orbit satellites (5000 and about 800 events, correspondingly for high and low altitude satellites). No relation was found between low and high altitude satellite anomalies. Daily numbers of satellite anomalies, averaged by a superposed epoch method around sudden storm commencements and solar proton event onsets for high (>1500 km) and low (railway operation (possible, through induction currents), catastrophes in long-distance electric power lines and transformators, and in other ground technologies.

Edge detection of magnetic anomalies using analytic signal of tilt angle (ASTA)

Science.gov (United States)

Alamdar, K.; Ansari, A. H.; Ghorbani, A.

2009-04-01

Magnetic is a commonly used geophysical technique to identify and image potential subsurface targets. Interpretation of magnetic anomalies is a complex process due to the superposition of multiple magnetic sources, presence of geologic and cultural noise and acquisition and positioning error. Both the vertical and horizontal derivatives of potential field data are useful; horizontal derivative, enhance edges whereas vertical derivative narrow the width of anomaly and so locate source bodies more accurately. We can combine vertical and horizontal derivative of magnetic field to achieve analytic signal which is independent to body magnetization direction and maximum value of this lies over edges of body directly. Tilt angle filter is phased-base filter and is defined as angle between vertical derivative and total horizontal derivative. Tilt angle value differ from +90 degree to -90 degree and its zero value lies over body edge. One of disadvantage of this filter is when encountering with deep sources the detected edge is blurred. For overcome this problem many authors introduced new filters such as total horizontal derivative of tilt angle or vertical derivative of tilt angle which Because of using high-order derivative in these filters results may be too noisy. If we combine analytic signal and tilt angle, a new filter termed (ASTA) is produced which its maximum value lies directly over body edge and is easer than tilt angle to delineate body edge and no complicity of tilt angle. In this work new filter has been demonstrated on magnetic data from an area in Sar- Cheshme region in Iran. This area is located in 55 degree longitude and 32 degree latitude and is a copper potential region. The main formation in this area is Andesith and Trachyandezite. Magnetic surveying was employed to separate the boundaries of Andezite and Trachyandezite from adjacent area. In this regard a variety of filters such as analytic signal, tilt angle and ASTA filter have been applied which

Automatic detection of multiple UXO-like targets using magnetic anomaly inversion and self-adaptive fuzzy c-means clustering

Science.gov (United States)

Yin, Gang; Zhang, Yingtang; Fan, Hongbo; Ren, Guoquan; Li, Zhining

2017-12-01

We have developed a method for automatically detecting UXO-like targets based on magnetic anomaly inversion and self-adaptive fuzzy c-means clustering. Magnetic anomaly inversion methods are used to estimate the initial locations of multiple UXO-like sources. Although these initial locations have some errors with respect to the real positions, they form dense clouds around the actual positions of the magnetic sources. Then we use the self-adaptive fuzzy c-means clustering algorithm to cluster these initial locations. The estimated number of cluster centroids represents the number of targets and the cluster centroids are regarded as the locations of magnetic targets. Effectiveness of the method has been demonstrated using synthetic datasets. Computational results show that the proposed method can be applied to the case of several UXO-like targets that are randomly scattered within in a confined, shallow subsurface, volume. A field test was carried out to test the validity of the proposed method and the experimental results show that the prearranged magnets can be detected unambiguously and located precisely.

Comparison of the Northeast Arctic cod year class strength (at the age of 3+) with the SST anomalies in main spawning ground (the Norwegian Shelf Waters) by results of analysis satellite monitoring data during last years.

Science.gov (United States)

Vanyushin, George

2015-04-01

Continuous long-term database (1998-2014) on the sea surface temperature (SST) comprising results of regional satellite monitoring (the Norwegian and the Barents seas) is used to resolve several applied problems. Authors have analyzed indirect influence the SST (the NOAA satellite data) on modern cod total stock biomass (abundance of the Northeast Arctic cod at age 3+). In this study, we went on the consideration of the relationship between the SST anomalies for March-April in the main spawning ground of the cod off the Lofoten islands in the Norwegian Shelf Waters and forecasting assessment of future cod generation success and its future abundance of 3 year old. Mean monthly SST and SST anomalies are computed for the selected area on the basis of the weekly SST maps which made by using the NOAA satellites data for the period 1998-2014. Comparison of the SST anomalies in the main spawning ground with abundance of the cod year class at age 3+ shows that survival of the cod generations was inhibited on the whole as negative (below -0,1C) well as positive SST anomalies (above +1,3C) during March and April. Finally, the results indicate that poor and low middle generations of cod at age 3+ (2002, 2004, 2010) occurred in years with negative or extremely high positive the SST anomalies in the spawning area. The SST anomalies in years which were close to normal significances provide conditions for appearance middle or strong generations of cod (2001-2003, 2005-2009, 2011-2013). So, the SST and SST anomalies (by the NOAA satellite data) characterize of increase in input of warm Atlantic waters which form numerous eddies along the main stream thus creating favorable conditions for spawning and development of the cod larvae and fry and provide them with food stock, finally direct influence on forming total stock biomass of cod and helping its population forecast. Key words: satellite monitoring of SST, the Northeast Arctic cod, spawning ground, forecast of the cod year class

Magnetic anomalies across the southern Central Indian Ridge: evidence for a new transform fault

Digital Repository Service at National Institute of Oceanography (India)

Chaubey, A.K.; Krishna, K.S.; SubbaRaju, L.V.; Rao, D.G.

, Vol. 37. No. 4. pp. MT-~a56, 1990. 0198-.0149/90 $3.(gl + 0.00 Pnnled in Great Britain. (~ 1990 Pergartma Ptes6 pie Magnetic anomalies across the southern Central Indian Ridge: evidence for a new transform fault A. K. CHAUBEY,* K. S. KRISHNA,* L. V... to the ridge are identified as sea-floor spreading lineations 2.2A,3.3A and 4. A half spreading rate of 2.2 cm y- t is estimated for the last I0 Ma. The ridge jump between the anomalies 2-2A (approx. 2.5 Ma) and a new left lateral transform fault offsetting...

Patterns of congenital bony spinal deformity and associated neural anomalies on X-ray and magnetic resonance imaging

OpenAIRE

Trenga, Anthony P.; Singla, Anuj; Feger, Mark A.; Abel, Mark F.

2016-01-01

Purpose Congenital malformations of the bony vertebral column are often accompanied by spinal cord anomalies; these observations have been reinforced with the use of magnetic resonance imaging (MRI). We hypothesized that the incidence of cord anomalies will increase as the number and complexity of bony vertebral abnormalities increases. Methods All patients aged ?13 years (n?=?75) presenting to the pediatric spine clinic from 2003?2013 with congenital bony spinal deformity and both radiograph...

Analysis of the Nuevo Leon magnetic anomaly and its possible relation to the Cerro Prieto magmatic-hydrothermal system

Energy Technology Data Exchange (ETDEWEB)

Goldstein, N.E.; Wilt, M.J.; Corrigan, D.J.

1982-10-01

The broad dipolar magnetic anomaly whose positive peak is centered near Ejido Nuevo Leon, some 5 km east of the Cerro Prieto I Power Plant, has long been suspected to have a genetic relationship to the thermal source of the Cerro Prieto geothermal system. This suspicion was reinforced after several deep geothermal wells, drilled to depths of 3 to 3.5 km over the anomaly, intersected an apparent dike-sill complex consisting mainly of diabase but with minor rhyodacite. A detailed fit of the observed magnetic field to a computer model indicates that the source may be approximated by a tabular block 4 by 6 km in area, 3.7 km in depth, 2.3 km thick, and dipping slightly to the north. Mafic dike chips from one well, NL-1, were analyzed by means of electron microprobe analyses which showed tham to contain a titanomagnetite that is paramagnetic at in-situ temperature conditions. As the dike mineralogy does not account for the magnetic anomaly, the magnetic source is believed to be a deeper, magnetite-rich assemblage of peridotite-gabbro plutons. the suite of igneous rocks was probably passively emplaced at a shallow depth in response to crustal extension and thinning brought on by strike-slip faulting. The bottom of the magnetic source body, at an estimated depth of 6 km, is presumed to be at or near that of the Curie isotherm (575/sup 0/C) for magnetite, the principal ferromagnetic mineral in peridotitic-gabbroic rocks. The geological model derived from the magnetic study is generally supported by other geophysical data. In particular, earthquake data suggest dike injection is occurring at depths of 6 to 11 km in an area beneath the magnetic source. Thus, it is possible that heat for the geothermal field is being maintained by continuing crustal extension and magmatic activity.

Investigating the polar electrojet using Swarm satellite magnetic data

DEFF Research Database (Denmark)

Aakjær, Cecilie Drost; Olsen, Nils; Finlay, Chris

The aim of this study is to investigate the magnetic perturbations caused by the polar electrojets, which are described by means of a model consisting of a series of infinite line currents placed at the height of the ionosphere along QD latitudes. The method is applied to Swarm magnetic scalar...... of the polar electrojets as well as their temporal evolution. In addition, applying the method to data taken by the Swarm satellites Alpha and Beta allows investigating longitudinal differences of the electrojets....

Multi-instrument observations of midlatitude summer nighttime anomaly from satellite and ground

Science.gov (United States)

Yamamoto, Mamoru; Thampi, Smitha V.; Liu, Huixin; Lin, Charles

"Midlatitude Summer Nighttime Anomaly (MSNA)" is a phenomenon that the nighttime elec-tron densities exceed the daytime values on almost all days in summer over latitudes of 33-34N of more. We recently found the MSNA over the northeast Asian region from multi-instrument observations. The observations include the tomography analysis based on the chain of digital beacon receivers at Shionomisaki (33.45N, 135.8E), Shigaraki (34.85N, 136.1E), and Fukui (36.06N,136E), the ionosonde network over Japan (especially data from Wakkanai (45.4N, 141.7E)), ground-based GPS TEC observations using the GEONET. Also from satellites, CHAMP in situ electron density measurements, and Formosat3/COSMIC (F3/C) occultation measurements are useful to confirm the presence of MSNA over this region. In the presen-tation we show detailed features of the MSNA based on these multi-instrument, and discuss importance of the neutral atmosphere as a driver of the phenomenon.

An orbit determination algorithm for small satellites based on the magnitude of the earth magnetic field

Science.gov (United States)

Zagorski, P.; Gallina, A.; Rachucki, J.; Moczala, B.; Zietek, S.; Uhl, T.

2018-06-01

Autonomous attitude determination systems based on simple measurements of vector quantities such as magnetic field and the Sun direction are commonly used in very small satellites. However, those systems always require knowledge of the satellite position. This information can be either propagated from orbital elements periodically uplinked from the ground station or measured onboard by dedicated global positioning system (GPS) receiver. The former solution sacrifices satellite autonomy while the latter requires additional sensors which may represent a significant part of mass, volume, and power budget in case of pico- or nanosatellites. Hence, it is thought that a system for onboard satellite position determination without resorting to GPS receivers would be useful. In this paper, a novel algorithm for determining the satellite orbit semimajor-axis is presented. The methods exploit only the magnitude of the Earth magnetic field recorded onboard by magnetometers. This represents the first step toward an extended algorithm that can determine all orbital elements of the satellite. The method is validated by numerical analysis and real magnetic field measurements.

Congenital inferior vena cava anomalies: a review of findings at multidetector computed tomography and magnetic resonance imaging

Directory of Open Access Journals (Sweden)

Catherine Yang

2013-07-01

Full Text Available Inferior vena cava anomalies are rare, occurring in up to 8.7% of the population, as left renal vein anomalies are considered. The inferior vena cava develops from the sixth to the eighth gestational weeks, originating from three paired embryonic veins, namely the subcardinal, supracardinal and postcardinal veins. This complex ontogenesis of the inferior vena cava, with multiple anastomoses between the pairs of embryonic veins, leads to a number of anatomic variations in the venous return from the abdomen and lower limbs. Some of such variations have significant clinical and surgical implications related to other cardiovascular anomalies and in some cases associated with venous thrombosis of lower limbs, particularly in young adults. The authors reviewed images of ten patients with inferior vena cava anomalies, three of them with deep venous thrombosis. The authors highlight the major findings of inferior vena cava anomalies at multidetector computed tomography and magnetic resonance imaging, correlating them the embryonic development and demonstrating the main alternative pathways for venous drainage. The knowledge on the inferior vena cava anomalies is critical in the assessment of abdominal images to avoid misdiagnosis and to indicate the possibility of associated anomalies, besides clinical and surgical implications.

Congenital inferior vena cava anomalies: a review of findings at multidetector computed tomography and magnetic resonance imaging

International Nuclear Information System (INIS)

Yang, Catherine; Trad, Clovis Simao; Trad, Henrique Simao

2013-01-01

Inferior vena cava anomalies are rare, occurring in up to 8.7% of the population, as left renal vein anomalies are considered. The inferior vena cava develops from the sixth to the eighth gestational weeks, originating from three paired embryonic veins, namely the subcardinal, supracardinal and postcardinal veins. This complex ontogenesis of the inferior vena cava, with multiple anastomoses between the pairs of embryonic veins, leads to a number of anatomic variations in the venous return from the abdomen and lower limbs. Some of such variations have significant clinical and surgical implications related to other cardiovascular anomalies and in some cases associated with venous thrombosis of lower limbs, particularly in young adults. The authors reviewed images of ten patients with inferior vena cava anomalies, three of them with deep venous thrombosis. The authors highlight the major findings of inferior vena cava anomalies at multidetector computed tomography and magnetic resonance imaging, correlating them the embryonic development and demonstrating the main alternative pathways for venous drainage. The knowledge on the inferior vena cava anomalies is critical in the assessment of abdominal images to avoid misdiagnosis and to indicate the possibility of associated anomalies, besides clinical and surgical implications. (author)

Congenital inferior vena cava anomalies: a review of findings at multidetector computed tomography and magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Yang, Catherine; Trad, Clovis Simao [Central de Diagnostico Ribeirao Preto (CEDIRP), SP (Brazil); Trad, Henrique Simao, E-mail: hstrad@terra.com.br [Central de Diagnostico Ribeirao Preto (CEDIRP), SP (Brazil); Universidade de Sao Paulo (HC-FMRPUSP), Ribeirao Preto, SP (Brazil). Fac. de Medicina. Hospital das Clinicas; Mendonca, Silvana Machado [Clinica de Diagnostico por Imagem (CDPI), Rio de Janeiro, RJ (Brazil)

2013-06-15

Inferior vena cava anomalies are rare, occurring in up to 8.7% of the population, as left renal vein anomalies are considered. The inferior vena cava develops from the sixth to the eighth gestational weeks, originating from three paired embryonic veins, namely the subcardinal, supracardinal and postcardinal veins. This complex ontogenesis of the inferior vena cava, with multiple anastomoses between the pairs of embryonic veins, leads to a number of anatomic variations in the venous return from the abdomen and lower limbs. Some of such variations have significant clinical and surgical implications related to other cardiovascular anomalies and in some cases associated with venous thrombosis of lower limbs, particularly in young adults. The authors reviewed images of ten patients with inferior vena cava anomalies, three of them with deep venous thrombosis. The authors highlight the major findings of inferior vena cava anomalies at multidetector computed tomography and magnetic resonance imaging, correlating them the embryonic development and demonstrating the main alternative pathways for venous drainage. The knowledge on the inferior vena cava anomalies is critical in the assessment of abdominal images to avoid misdiagnosis and to indicate the possibility of associated anomalies, besides clinical and surgical implications. (author)

New constraints on the age and style of continental breakup in the South Atlantic from magnetic anomaly data

Science.gov (United States)

Collier, Jenny S.; McDermott, Carl; Warner, George; Gyori, Noemi; Schnabel, Michael; McDermott, Ken; Horn, Brian W.

2017-11-01

We present new constraints on the opening of the South Atlantic Ocean from a joint interpretation of marine magnetic anomaly grids and forward modelling of conjugate profiles. We use 45,000 km of recently collected commercial ship track data combined with 561,000 km of publically available data. The new data cover the critical ocean-continental transition zones and allow us to identify and downgrade some poorly navigated older ship tracks relied upon in earlier compilations. Within the final grids the mean cross-over error is 14 nT computed from 8,227 ship track intersections. The forward modelling used uniformly magnetised bodies whose shapes were constrained from coincident deep-seismic reflection data. We find the oldest magnetic anomalies to date from M10r (134.2 Ma, late Valanginian) north of the Falkland-Agulhas Fracture Zone and M3 (129.3 Ma, Barremian) south of the Rio Grande Fracture Zone. Hence, assuming the GPTS used is correct, continental breakup was contemporaneous with the Parana and Etendeka continental flood basalts. Many of the landward linear anomalies overlap seismically mapped Seaward Dipping Reflectors (SDRs). We interpret this to mean that a significant portion of the SDRs overlay crust formed by subaerial seafloor spreading. Here crustal accretion is envisaged to be similar to that at mid-ocean ridges, but sheet lava flows (that later form the SDRs) rather than pillow basalts form the extrusive component. Segmentation of the linear anomalies generated implies that this stage of continental breakup is organised and parallels the seafloor spreading centre that follows. Our results call into question the common assumption that at volcanic continental margins the first linear magnetic anomalies represent the start of conventional (submarine) oceanic crustal generation.

Analysis of magnetic anomalies in relation to Placer deposits and basement configuration off Mirya bay, Central West coast of India

Digital Repository Service at National Institute of Oceanography (India)

Ramana, M.V.

The offshore ilmenite placers off Konkan, central west coast of India, have been surveyed by echosounding, shallow seismic profiling, magnetics, and seabed sampling. The magnetic data show two different types of anomalies: (1) N-S trending high...

Dating of the 85 degrees E Ridge (northeastern Indian Ocean) using marine magnetic anomalies

Digital Repository Service at National Institute of Oceanography (India)

Michael, L.; Krishna, K.S.

underneath the eastern Con- rad Rise on the Antarctic plate. Subsequent geophysical RESEARCH ARTICLES CURRENT SCIENCE, VOL. 100, NO. 9, 10 MAY 2011 1315 studies 5,8 opined that short-lived volcanic activity had ini- tiated the 85°E Ridge in Mahanadi.... Satellite-derived free-air gravity anomaly map of the north- eastern Indian Ocean 24 . Curved strip line indicates continuity of the 85°E Ridge from the Mahanadi Basin to ANS. Few bathymetry con- tours derived from ETOPO5 data are shown in the map. N...

Particle precipitation and atmospheric X-and gamma-rays in the South Atlantic magnetic anomaly by balloon experiments

International Nuclear Information System (INIS)

Costa, J.M. da.

1981-06-01

Studies concerning particle precipitation and atmospheric X-and low energy gamma-rays in the South Atlantic magnetic anomaly by balloons experiments that have been made at INPE since 1968 are reported. (Author) [pt

Magnetic resonance imaging of Muellerian duct anomalies in children

International Nuclear Information System (INIS)

Li, Yi; Phelps, Andrew; Zapala, Matthew A.; MacKenzie, John D.; MacKenzie, Tippi C.; Courtier, Jesse

2016-01-01

Muellerian duct anomalies encompass a wide variety of disorders resulting from abnormalities in the embryological development of the Muellerian ducts. In the prepubertal pediatric population, Muellerian duct anomalies are often incidental findings on studies obtained for other reasons. The onset of menses can prompt more clinical symptoms. Proper characterization of Muellerian duct anomalies is important because these anomalies can affect the development of gynecological disorders as well as fertility. Muellerian duct anomalies also carry a high association with other congenital anomalies, particularly renal abnormalities. MRI is widely considered the best modality for assessing Muellerian duct anomalies; it provides multiplanar capability, clear anatomical detail and tissue characterization without ionizing radiation. MRI allows for careful description of Muellerian duct anomalies, often leading to classification into the most widely accepted classification system for Muellerian duct anomalies. This system, developed by the American Society of Reproductive Medicine, includes seven subtypes: uterine agenesis/hypoplasia, unicornuate, didelphys, bicornuate, septate, arcuate, and diethylstilbestrol (DES) drug-related uterus. In cases of complex anomalies that defy classification, MRI allows detailed depiction of all components of the anatomical abnormality, allowing for proper management and surgical planning. (orig.)

Inversion satellites of isolated Perl vortex in thin film of magnetic superconductor

CERN Document Server

Lomtev, A I

2001-01-01

The electrodynamics equation is derived for the magnetic field of the Perl isolated vortex, moving by the arbitrary law in the ultrafine magnetic conductor and true for every type of the magnetic ordering in the magnetic subsystem. The magnetic structure of the Perl isolated oscillating vortex in the magnetic conductor fine film is studied. It is shown that the oscillations process and the magnetic subsystem essentially renorm the vortex field as compared to the Perl decision. The new events of the inversion satellite (the inversion forerunners in the front of the vortex and the inversion traces behind it) are forecasted, which may be actually observed in the magnetic optical experiments

Contrasting Nature of Magnetic Anomalies over Thin Sections Made out of Barrandien’s Basaltic Rocks Points to their Origin

Czech Academy of Sciences Publication Activity Database

Kletetschka, Günther; Pruner, Petr; Schnabl, Petr; Šifnerová, Kristýna

-, special issue (2012), s. 69-70 ISSN 1335-2806. [Castle meeting New Trends in Geomagnetism : Paleo, rock and environmental magnetism/13./. 17.06.2012-23.06.2012, Zvolen] R&D Projects: GA ČR GAP210/10/2351 Institutional support: RVO:67985831 Keywords : magnetic anomalies * thin sections * volcanic rocks Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://gauss.savba.sk/GPIweb/conferences/Castle2012/abstrCastle.pdf

The lithospheric structure beneath Ireland and surrounding areas from integrated geophysical-petrological modelling of magnetic and other geophysical data

Science.gov (United States)

Baykiev, E.; Guerri, M.; Fullea, J.

2017-12-01

The availability of unprecedented resolution aeromagnetic data in Ireland (Tellus project, http://www.tellus.ie/) in conjunction with new satellite magnetic data (e.g., ESÁs Swarm mission) has opened the possibility of detailed modelling of the Irish subsurface magnetic structure. A detailed knowledge of the magnetic characteristics (susceptibility, magnetite content) of the crust is relevant for a number of purposes, including geological mapping and mineral and geothermal energy prospection. In this work we model the magnetic structure of Ireland and surrounding areas using primarily aeromagnetic and satellite observations but also other geophysical data sets. To this aim we use a geophysical-petrological modelling tool (LitMod) in which key properties of rocks (i.e., density, electrical conductivity and seismic velocities) that can be inferred from geophysical data (gravity, seismic, EM) are self consistently determined based on the thermochemical conditions (using the software Perple_X). In contrast to the mantle, where thermodynamic equilibrium is prevalent, in the crust metastable conditions are dominant, i.e. rock properties may not be representative of the current, in situ, temperature and pressure conditions. Instead, the rock properties inferred from geophysical data may be reflecting the mineralogy stable at rock formation conditions. In addition, temperature plays a major role in the distribution of the long wavelength crustal magnetic anomalies. Magnetite retains its magnetic properties below its Curie temperature (585 ºC) and the depth of Curie's isotherm provides an estimate of the thickness of the magnetic crust. Hence, a precise knowledge of the crustal geotherm is required to consistently model crustal magnetic anomalies. In this work LitMod has been modified to account for metastable crustal lithology, to predict susceptibility in the areas below Curie's temperature, and to compute magnetic anomalies based on a magnetic tesseroid approach. The

Viking satellite program - preliminary results from the APL Magnetic Field Experiment

International Nuclear Information System (INIS)

Potemra, T.A.; Zanetti, L.J.; Erlandson, R.E.; Gustafsson, G.; Acuna, M.H.; NASA, Goddard Space Flight Center, Greenbelt, MD)

1986-01-01

Sweden's Viking satellite, launched in February 1986, has been conducting plasma process observations in the earth magnetosphere and auroral regions; the U.S.-supplied APL Magnetic Field Experiment aboard Viking is used to determine field-aligned Birkeland current characteristics in previously unsampled regions of near-earth space. The Magnetic Field Experiment has an equivalent spatial resolution of 12 m in the auroral ionosphere when making measurements near apogee. The purposes of Viking's other instruments and their relationship to the Magnetic Field Experiment are discussed

Satellite drag effects due to uplifted oxygen neutrals during super magnetic storms

Science.gov (United States)

Lakhina, Gurbax S.; Tsurutani, Bruce T.

2017-12-01

During intense magnetic storms, prompt penetration electric fields (PPEFs) through E × B forces near the magnetic equator uplift the dayside ionosphere. This effect has been called the dayside super-fountain effect. Ion-neutral drag forces between the upward moving O+ (oxygen ions) and oxygen neutrals will elevate the oxygen atoms to higher altitudes. This paper gives a linear calculation indicating how serious the effect may be during an 1859-type (Carrington) superstorm. It is concluded that the oxygen neutral densities produced at low-Earth-orbiting (LEO) satellite altitudes may be sufficiently high to present severe satellite drag. It is estimated that with a prompt penetrating electric field of ˜ 20 mV m-1 turned on for 20 min, the O atoms and O+ ions are uplifted to 850 km where they produce about 40-times-greater satellite drag per unit mass than normal. Stronger electric fields will presumably lead to greater uplifted mass.

Magnetic anomalies of steel drums: a review of the literature and research results of the INGV

Directory of Open Access Journals (Sweden)

Marco Marchetti

2013-04-01

Full Text Available The detection and evaluation of the status of disposal sites that contain hazardous waste materials is becoming an increasingly important element in environmental investigations. Close cooperation between the Istituto Nazionale di Geofisica e Vulcanologia (INGV; National Institute of Volcanology and Geophysics in Rome and the Italian environmental police has resulted in numerous underground investigations of different buried materials. Among the geophysical investigation tools, magnetometry is the most effective, rapid and precise of all of the geophysical methods for localizing buried steel drums. Analysis of magnetic map anomalies can provide a variety of information about buried materials, including extension, distribution and depth, with processing of the acquired magnetic data. This information is also very useful in case of excavations that are aimed at the recovery of hazardous waste. This study determines the most relevant analyses reported in the literature, with modeling of magnetometric methods for environmental applications both theoretically and experimentally. Some studies and research results achieved by the INGV in relation to magnetic anomalies produced by buried steel drums are also reported, as found in field operations and as achieved from test sites.

The enigma of lunar magnetism

Science.gov (United States)

Hood, L. L.

1981-01-01

Current understandings of the nature and probable origin of lunar magnetism are surveyed. Results of examinations of returned lunar samples are discussed which reveal the main carrier of the observed natural remanent magnetization to be iron, occasionally alloyed with nickel and cobalt, but do not distinguish between thermoremanent and shock remanent origins, and surface magnetometer data is presented, which indicates small-scale magnetic fields with a wide range of field intensities implying localized, near-surface sources. A detailed examination is presented of orbital magnetometer and charged particle data concerning the geologic nature and origin of magnetic anomaly sources and the directional properties of the magnetization, which exhibit a random distribution except for a depletion in the north-south direction. A lunar magnetization survey with global coverage provided by a polar orbiting satellite is suggested as a means of placing stronger constraints on the origin of lunar crustal magnetization.

A new segmentation strategy for processing magnetic anomaly detection data of shallow depth ferromagnetic pipeline

Science.gov (United States)

Feng, Shuo; Liu, Dejun; Cheng, Xing; Fang, Huafeng; Li, Caifang

2017-04-01

Magnetic anomalies produced by underground ferromagnetic pipelines because of the polarization of earth's magnetic field are used to obtain the information on the location, buried depth and other parameters of pipelines. In order to achieve a fast inversion and interpretation of measured data, it is necessary to develop a fast and stable forward method. Magnetic dipole reconstruction (MDR), as a kind of integration numerical method, is well suited for simulating a thin pipeline anomaly. In MDR the pipeline model must be cut into small magnetic dipoles through different segmentation methods. The segmentation method has an impact on the stability and speed of forward calculation. Rapid and accurate simulation of deep-buried pipelines has been achieved by exciting segmentation method. However, in practical measurement, the depth of underground pipe is uncertain. When it comes to the shallow-buried pipeline, the present segmentation may generate significant errors. This paper aims at solving this problem in three stages. First, the cause of inaccuracy is analyzed by simulation experiment. Secondly, new variable interval section segmentation is proposed based on the existing segmentation. It can help MDR method to obtain simulation results in a fast way under the premise of ensuring the accuracy of different depth models. Finally, the measured data is inversed based on new segmentation method. The result proves that the inversion based on the new segmentation can achieve fast and accurate inversion of depth parameters of underground pipes without being limited by pipeline depth.

What can we learn about Mars from satellite magnetic field measurements?

Science.gov (United States)

Morschhauser, A.; Mittelholz, A.; Thomas, P.; Vervelidou, F.; Grott, M.; Johnson, C.; Lesur, V.; Lillis, R. J.

2017-12-01

The Mars orbiters MGS and MAVEN provide vector magnetic field data for Mars at a variety of altitudes, locations, and local times. In spite of the abundance of data, there are many open questions concerning the crustal magnetic field of Mars. In this contribution, we present our efforts to estimate the shutdown time of the Martian core dynamo and to estimate Martian paleopole locations, using magnetic field satellite data and models derived from these data [1]. Models are primarily based on MGS data, and we shortly present our recent advances to include MAVEN data. There exists some controversy concerning the timing of the Martian core dynamo shutdown [e.g., 2-5]. We address this question by studying the so-called visible magnetization [6-7] of impact craters larger than 400 km in diameter, and conclude that the dynamo ceased to operate in the Noachian period [8]. Further, paleopole locations have been used to constrain the dynamics of the Martian core dynamo [e.g. 4-5, 9]. However, such estimates are limited by the inherent non-uniqueness of inferring magnetization from magnetic field measurements. Here, we discuss how estimated paleopoles are influenced by this non-uniqueness and the limited signal-to-noise ratio of satellite measurements [6]. Furthermore, we discuss how paleopole locations may still be obtained from satellite magnetic field measurements. In this context, we present some new paleopole estimates for Mars including estimates of uncertainties. References: [1] A. Morschhauser et al. (2014), JGR, doi: 10.1002/2013JE004555 [2] R.J. Lillis et al. (2015), JGR, doi: 10.1002/2014je004774 [3] L.L. Hood et al. (2010), Icarus, doi: 10.1016/j.icarus.2010.01.009 [4] C. Milbury et al. (2012), JGR, doi: 10.1029/2012JE004099 [5] B. Langlais and M. Purucker (2007), PSS, 10.1016/j.pss.2006.03.008 [6] F. Vervelidou et al., On the accuracy of paleopole estimations from magnetic field measurements, GJI, under revision 2017 [7] D. Gubbins et al. (2011), GJI, doi: 10

Can We Probe the Conductivity of the Lithosphere and Upper Mantle Using Satellite Tidal Magnetic Signals?

Science.gov (United States)

Schnepf, N. R.; Kuvshinov, A.; Sabaka, T.

2015-01-01

A few studies convincingly demonstrated that the magnetic fields induced by the lunar semidiurnal (M2) ocean flow can be identified in satellite observations. This result encourages using M2 satellite magnetic data to constrain subsurface electrical conductivity in oceanic regions. Traditional satellite-based induction studies using signals of magnetospheric origin are mostly sensitive to conducting structures because of the inductive coupling between primary and induced sources. In contrast, galvanic coupling from the oceanic tidal signal allows for studying less conductive, shallower structures. We perform global 3-D electromagnetic numerical simulations to investigate the sensitivity of M2 signals to conductivity distributions at different depths. The results of our sensitivity analysis suggest it will be promising to use M2 oceanic signals detected at satellite altitude for probing lithospheric and upper mantle conductivity. Our simulations also suggest that M2 seafloor electric and magnetic field data may provide complementary details to better constrain lithospheric conductivity.

Long wavelength magnetic anomalies over continental rifts in cratonic region

Science.gov (United States)

Friedman, S. A.; Persaud, P.; Ferre, E. C.; Martín-Hernández, F.; Feinberg, J. M.

2017-12-01

New collections of unaltered mantle xenoliths shed light on potential upper mantle contributions to long wavelength magnetic anomalies (LWMA) in continental rifts in cratonic / shield areas. The new material originates from the East African Rift (Tanzania), the Rio Grande Rift (U.S.A.), the Rhine Rift (Germany), and the West Antarctic Rift (Antarctica). The xenoliths sample the uppermost ( 0.2 or Fe geotherms (>60ºC/km) that are characteristic of rifted regions preclude any contribution to LWMA at depths >10 km. Hence, only upper basalts and hypovolcanic mafic sills would constitute potential magnetic sources. In contrast, the margins of these rifted regions consist of refractory cratonic domains, often characterized by oxidized sublithospheric mantle that host significant concentrations of primary magnetite. The higher NRMs of these peridotites (up to 15 A/m, Qn > 2.5) combined with much lower geotherms (as low as 15ºC/km) allows for a 5 to 10 km layer of uppermost mantle to potentially contribute to LWMA. Assuming that Qn values in rift margins are also gradient across the rift would primarily reflect thermal equilibration over time.

Patterns of congenital bony spinal deformity and associated neural anomalies on X-ray and magnetic resonance imaging.

Science.gov (United States)

Trenga, Anthony P; Singla, Anuj; Feger, Mark A; Abel, Mark F

2016-08-01

Congenital malformations of the bony vertebral column are often accompanied by spinal cord anomalies; these observations have been reinforced with the use of magnetic resonance imaging (MRI). We hypothesized that the incidence of cord anomalies will increase as the number and complexity of bony vertebral abnormalities increases. All patients aged ≤13 years (n = 75) presenting to the pediatric spine clinic from 2003-2013 with congenital bony spinal deformity and both radiographs and MRI were analyzed retrospectively for bone and neural pathology. Chi-squared analysis was used to compare groups for categorical dependent variables. Independent t tests were used for continuous dependent variables. Significance was set at p formation had a higher incidence of cord anomalies (73 %) than failures of formation (50 %) or segmentation (45 %) alone (p = 0.065). Deformities in the sacrococcygeal area had the highest rate of spinal cord anomalies (13 of 15 patients, 87 %). In 35 cases (47 %), MRI revealed additional bony anomalies that were not seen on the radiographs. As the number of bony malformations increased, we found a higher incidence of cord anomalies. Clinicians should have increased suspicion of spinal cord pathology in the presence of mixed failures of segmentation and formation.

An Equivalent Source Method for Modelling the Lithospheric Magnetic Field Using Satellite and Airborne Magnetic Data

DEFF Research Database (Denmark)

Kother, Livia Kathleen; Hammer, Magnus Danel; Finlay, Chris

. Advantages of the equivalent source method include its local nature and the ease of transforming to spherical harmonics when needed. The method can also be applied in local, high resolution, investigations of the lithospheric magnetic field, for example where suitable aeromagnetic data is available......We present a technique for modelling the lithospheric magnetic field based on estimation of equivalent potential field sources. As a first demonstration we present an application to magnetic field measurements made by the CHAMP satellite during the period 2009-2010. Three component vector field...... for the remaining lithospheric magnetic field consists of magnetic point sources (monopoles) arranged in an icosahedron grid with an increasing grid resolution towards the airborne survey area. The corresponding source values are estimated using an iteratively reweighted least squares algorithm that includes model...

Energy detection based on undecimated discrete wavelet transform and its application in magnetic anomaly detection.

Directory of Open Access Journals (Sweden)

Xinhua Nie

Full Text Available Magnetic anomaly detection (MAD is a passive approach for detection of a ferromagnetic target, and its performance is often limited by external noises. In consideration of one major noise source is the fractal noise (or called 1/f noise with a power spectral density of 1/fa (0magnetic anomaly detection and UDWT are introduced in brief, while a possible detection system based on giant magneto-impedance (GMI magnetic sensor is also given out. Then our proposed energy detection based on UDWT is described in detail, and the probabilities of false alarm and detection for given the detection threshold in theory are presented. It is noticeable that no a priori assumptions regarding the ferromagnetic target or the magnetic noise probability are necessary for our method, and different from the discrete wavelet transform (DWT, the UDWT is shift invariant. Finally, some simulations are performed and the results show that the detection performance of our proposed detector is better than that of the conventional energy detector even utilized in the Gaussian white noise, especially when the spectral parameter α is less than 1.0. In addition, a real-world experiment was done to demonstrate the advantages of the proposed method.

Satellite drag effects due to uplifted oxygen neutrals during super magnetic storms

Directory of Open Access Journals (Sweden)

G. S. Lakhina

2017-12-01

Full Text Available During intense magnetic storms, prompt penetration electric fields (PPEFs through E  ×  B forces near the magnetic equator uplift the dayside ionosphere. This effect has been called the dayside super-fountain effect. Ion-neutral drag forces between the upward moving O+ (oxygen ions and oxygen neutrals will elevate the oxygen atoms to higher altitudes. This paper gives a linear calculation indicating how serious the effect may be during an 1859-type (Carrington superstorm. It is concluded that the oxygen neutral densities produced at low-Earth-orbiting (LEO satellite altitudes may be sufficiently high to present severe satellite drag. It is estimated that with a prompt penetrating electric field of ∼ 20 mV m−1 turned on for 20 min, the O atoms and O+ ions are uplifted to 850 km where they produce about 40-times-greater satellite drag per unit mass than normal. Stronger electric fields will presumably lead to greater uplifted mass.

Satellite Geomagnetism

DEFF Research Database (Denmark)

Olsen, Nils; Stolle, Claudia

2012-01-01

Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade....... The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite constellation Swarm will ensure continuity of such measurement and provide enhanced possibilities to improve our...... ability to characterize and understand the many sources that contribute to Earth’s magnetic field. In this review, we summarize investigations of Earth’s interior and environment that have been possible through the analysis of high-precision magnetic field observations taken by LEO satellites....

MAGSAT anomaly field inversion and interpretation for the US

Science.gov (United States)

Mayhew, M. A. (Principal Investigator)

1982-01-01

Long wavelength anomalies in the total magnetic field measured by MAGSAT over the United States and adjacent areas are inverted to an equivalent layer crustal magnetization distribution. The model is based on an equal area dipole grid at the Earth's surface. Model resolution, defined as the closest dipole spacing giving a solution having physical significance, is about 220 km for MAGSAT data in the elevation range 300-500 km. The magnetization contours correlate well with large scale tectonic provinces. A higher resolution (200 km) model based on relatively noise free synthetic "pseudodata" is also presented. Magnetic anomaly component data measured by MAGSAT is compared with synthetic anomaly component fields arising from an equivalent source dipole array at the Earth's surface generated from total field anomaly data alone. An excellent inverse correlation between apparent magnetization and heat flow in the western U.S. is demonstrated. A regional heat flow map which is presented and compared with published maps, predicts high heat flow in Nebraska and the Dakotas, suggesting the presence of a "blind" geothermal area of regional extent.

Mapping magnetized geologic structures from space: The effect of orbital and body parameters

Science.gov (United States)

Schnetzler, C. C.; Taylor, P. T.; Langel, R. A.

1984-01-01

When comparing previous satellite magnetometer missions (such as MAGSAT) with proposed new programs (for example, Geopotential Research Mission, GRM) it is important to quantify the difference in scientific information obtained. The ability to resolve separate magnetic blocks (simulating geological units) is used as a parameter for evaluating the expected geologic information from each mission. The effect of satellite orbital altitude on the ability to resolve two magnetic blocks with varying separations is evaluated and quantified. A systematic, nonlinear, relationship exists between resolution and distance between magnetic blocks as a function of orbital altitude. The proposed GRM would provide an order-of-magnitude greater anomaly resolution than the earlier MAGSAT mission for widely separated bodies. The resolution achieved at any particular altitude varies depending on the location of the bodies and orientation.

Extracting Ocean-Generated Tidal Magnetic Signals from Swarm Data through Satellite Gradiometry

DEFF Research Database (Denmark)

Sabaka, Terence J.; Tyler, Robert H.; Olsen, Nils

2016-01-01

Ocean-generated magnetic field models of the Principal Lunar, M2, and the Larger Lunar elliptic, N2, semi-diurnal tidal constituents were estimated through a “Comprehensive Inversion" of the first 20.5 months of magnetic measurements from ESA's Swarm satellite constellation mission. While...

The Astromag superconducting magnet facility configured for a free-flying satellite

Science.gov (United States)

Green, M. A.; Smoot, G. F.

1992-01-01

The magnet parameters of a free-flying version of Astromag and the parameters of the space cryogenic system for the magnet are presented. Consideration is given to the free-flyer version of the Astromag magnet. The diameter of the magnet, its cryostat, the satellite and the two instruments is limited by the 4.27-m shroud diameter of the Atlas IIa. The magnet coil must use a stable reliable superconductor which can carry the full magnet current at 4.2 K at a peak induction in the coil of 7.5 T. The magnet must operate in the persistent mode. The changes in the overall design and operating requirements for the free-flying-design Astromag suggest that the coils, the cryogenic system, and the charging system can be simplified without a loss of required magnet function. Attention is given to switches, trim coils, and plumbing in the low field region between the coils; the magnet charging system and the quench protection system; and cooled helium supply to the magnet gas-cooled electrical leads.

Plasma instabilities in the ionosphere at the crest of anomaly region

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Shivalika, E-mail: shivalikasarkar@gmail.com [Department of Education in Science and Mathematics, Regional Institute of Education, Bhopal – 462013 (India); Tiwari, Sunita, E-mail: suni-tiwari@yahoo.co.in [LNCT, Kalchuri Nagar, Raisen Road, Bhopal (India); Gwal, A. K., E-mail: ashok.gwal@gmail.com [Department of Physics, Barkatullah University, Bhopal-462026 (India)

2015-07-31

Comparison of the in situ density fluctuations measured by the DEMETER satellite with ground based GPS receiver measurements at the equatorial anomaly station Bhopal [geographic coordinates (23.2°N, 77.6°E); geomagnetic coordinates (14.29° N, 151.12°E)] for the low solar activity year, 2005, are presented in this paper. The Langmuir Probe experiment and Plasma Analyzer onboard DEMETER measure the electron and ion densities respectively. It is interesting to note that in situ density fluctuations observed on magnetic flux tubes that pass over Bhopal can be used as indicator of ionospheric scintillations at that site. Many cases of density fluctuations and associated scintillations have been observed during descending low solar activity period.

High magnetic field magnetoresistance anomalies in the charge density wave state of the quasi-two dimensional bronze KMo6O{17}

Science.gov (United States)

Guyot, H.; Dumas, J.; Marcus, J.; Schlenker, C.; Vignolles, D.

2005-12-01

We report high magnetic field magnetoresistance measurements performed in pulsed fields up to 55 T on the quasi-two dimensional charge density wave conductor KMo{6}O{17}. Magnetoresistance curves show several anomalies below 28 T. First order transitions to smaller gap states take place at low temperature above 30 T. A phase diagram T(B) has been obtained. The angular dependence of the anomalies is reported.

Modeling and Inversion of Magnetic Anomalies Caused by Sediment–Basement Interface Using Three-Dimensional Cauchy-Type Integrals

DEFF Research Database (Denmark)

Cai, Hongzhu; Zhdanov, Michael

2014-01-01

This letter introduces a new method for the modeling and inversion of magnetic anomalies caused by crystalline basements. The method is based on the 3-D Cauchy-type integral representation of the magnetic field. Traditional methods use volume integrals over the domains occupied by anomalous...... is particularly significant in solving problems of the modeling and inversion of magnetic data for the depth to the basement. In this letter, a novel method is proposed, which only requires discretizing the magnetic contrast surface for modeling and inversion. We demonstrate the method using several synthetic...... susceptibility and on the prismatic representation of the volumes with an anomalous susceptibility distribution. Such discretization is computationally expensive, particularly in 3-D cases. The technique of Cauchy-type integrals makes it possible to represent the magnetic field as surface integrals, which...

Geophysical Surveying of Shallow Magnetic Anomalies Using the iPhone Magnetometer

Science.gov (United States)

Opdyke, P.; Dudley, C.; Louie, J. N.

2012-12-01

This investigation examined whether the 3-axis Hall-effect magnetometer in the Apple iPhone 3GS can function as an effective shallow magnetic survey instrument. The xSensor Pro app from Crossbow Systems allows recoding of all three sensor components along with the GPS location, at a frequency of 1.0, 4.0, 16.0, and 32.0 Hz. If the iPhone proves successful in collecting useful magnetic data, then geophysicists and especially educators would have a new tool for high-density geophysical mapping. No-contract iPhones that can connect with WiFi can be obtained for about $400, allowing deployment of large numbers of instruments. iPhones with the xSensor Pro app surveyed in parallel with an Overhauser GEM system magnetometer (1 nT sensitivity) to test this idea. Anderson Bay, located on the Pyramid Lake Paiute Reservation, provided a rural survey location free from cultural interference. xSensor Pro, logged each component's intensity and the GPS location at a frequency of four measurements per second. Two Overhauser units functioned as a base unit and a roving unit. The roving unit collected total field at set points located with a handheld GPS. Comparing the total field computed from the iPhone components against that collected by the Overhauser establishes the level of anomalies that the iPhone can detect. iPhone total-field measurements commonly vary by 200 nT from point to point, so a spatial-temporal average over 25 seconds produces a smoothed signal for comparison. Preliminary analysis of the iPhone results show that the data do not accurately correlate to the total field collected by the Overhauser for any anomaly of less than 200 nT.

Geothermal Heat Flux Underneath Ice Sheets Estimated From Magnetic Satellite Data

DEFF Research Database (Denmark)

Fox Maule, Cathrine; Purucker, M.E.; Olsen, Nils

The geothermal heat flux is an important factor in the dynamics of ice sheets, and it is one of the important parameters in the thermal budgets of subglacial lakes. We have used satellite magnetic data to estimate the geothermal heat flux underneath the ice sheets in Antarctica and Greenland...

The location and nature of the Telemzan High Ghadames basin boundary in southern Tunisia based on gravity and magnetic anomalies

Science.gov (United States)

Gabtni, H.; Jallouli, C.; Mickus, K. L.; Zouari, H.; Turki, M. M.

2006-03-01

Gravity and magnetic data were analyzed to add constraints on the location and nature of the Telemzan-Ghadames boundary (TGB) and structure of the Ghadames basin in southern Tunisia. TGB is the boundary between the thick sedimentary cover of the intracratonic Ghadames basin to the south and the thin sedimentary cover of the Saharan platform to the north. The upward continuation of the Bouguer gravity anomalies showed that the TGB is a regional geophysical feature that may have controlled the amount of sediment being deposited both north and south of the boundary and the tectonic environment in the region since Paleozoic time. To emphasize the shorter wavelength gravity and magnetic anomalies, a series of gray scale images of the directional horizontal gradients were constructed that determined a series of previously unknown east-west-trending gravity and magnetic anomalies south of 31.6°N that correspond to lineaments seen on a Landsat 7 image and the location of the TGB. Also, an edge-enhancement analysis illustrated the same linear gravity anomalies and showed the subbasins and uplifts within the Ghadames basin had source depths of between 0.5 and 3.4 km. A north-south trending gravity model showed that the TGB is a relatively gradual feature (possibly basement stepped down by relatively low-displacement faulting) controlling the subsidence of the main Ghadames basin and confirms the edge-enhancement analysis that subbasin S3 and uplift U1 are the main structural features within the Ghadames basin. The knowledge of basement architecture of the Ghadames basin is important for future petroleum exploration within this intracratonic basin.

3D inversion and modeling of magnetic and gravimetric data characterizing the geophysical anomaly source in Pratinha I in the southeast of Brazil

Science.gov (United States)

Louro, Vinicius Hector Abud; Mantovani, Marta Silvia Maria

2012-05-01

The Alto do Paranaíba Igneous Province (APIP) is known for its great mineral exploratory interest in phosphates, niobium, titanium, and diamonds, among others. In the years of 2005 and 2006, the Economic Development Company of Minas Gerais (CODEMIG — http://www.comig.com.br/) performed an airborne magnetic survey over the portion of this igneous province which belongs to Minas Gerais state, denominated Area 7. This survey revealed at the coordinates (19°45'S, 46°10'W) a tripolar anomaly here referred as Pratinha I. This anomaly does not present evidences of outcropping or topographic remodeling. So, boreholes or studies over its sources make the geophysical methods the best and less expensive solution for studying the body in its subsurface. Besides, two gravimetric ground surveys were performed in 2009 and 2010, confirming the existence of a density contrast over the region of the magnetic anomaly. Therefore, through the magnetometry and gravimetry processing, 3D modeling and inversions, it was possible to estimate the geometry, density and magnetic susceptibility, which when analyzed with the regional geology, enabled the proposition of an igneous intrusion of probable alkaline or kamafugitic composition to justify the gravimetric and magnetic response in the region.

Glimpses of East Antarctica: Aeromagnetic and satellite magnetic view from the central Transantarctic Mountains of East Antarctica

Science.gov (United States)

Finn, Carol A.; Goodge, John W.

2010-01-01

Aeromagnetic and satellite magnetic data provide glimpses of the crustal architecture within the Ross Sea sector of the enigmatic, ice-covered East Antarctic shield critical for understanding both global tectonic and climate history. In the central Transantarctic Mountains (CTAM), exposures of Precambrian basement, coupled with new high-resolution magnetic data, other recent aeromagnetic transects, and satellite magnetic and seismic tomography data, show that the shield in this region comprises an Archean craton modified both by Proterozoic magmatism and early Paleozoic orogenic basement reactivation. CTAM basement structures linked to the Ross Orogeny are imaged 50–100 km farther west than previously mapped, bounded by inboard upper crustal Proterozoic granites of the Nimrod igneous province. Magnetic contrasts between craton and rift margin sediments define the Neoproterozoic rift margin, likely reactivated during Ross orogenesis and Jurassic extension. Interpretation of satellite magnetic and aeromagnetic patterns suggests that the Neoproterozoic rift margin of East Antarctica is offset by transfer zones to form a stepwise series of salients tracing from the CTAM northward through the western margin of the Wilkes Subglacial Basin to the coast at Terre Adélie. Thinned Precambrian crust inferred to lie east of the rift margin cannot be imaged magnetically because of modification by Neoproterozoic and younger tectonic events.

A model of Earth’s magnetic field derived from 2 years of Swarm satellite constellation data

DEFF Research Database (Denmark)

Olsen, Nils; Finlay, Chris; Kotsiaros, Stavros

2016-01-01

More than 2 years of magnetic field data taken by the three-satellite constellation mission Swarm are used to derive a model of Earth’s magnetic field and its time variation. This model is called SIFMplus. In addition to the magnetic field observations provided by each of the three Swarm satellites...... the North–South gradient. The SIFMplus model provides a description of the static lithospheric field that is very similar to models determined from CHAMP data, up to at least spherical harmonic degree n=75. Also the core field part of SIFMplus, with a quadratic time dependence for n≤6 and a linear time...... with the model of the core, lithospheric and large-scale magnetospheric fields, a magnetic potential that depends on quasi-dipole latitude and magnetic local time....

6d, Coulomb branch anomaly matching

Science.gov (United States)

Intriligator, Kenneth

2014-10-01

6d QFTs are constrained by the analog of 't Hooft anomaly matching: all anomalies for global symmetries and metric backgrounds are constants of RG flows, and for all vacua in moduli spaces. We discuss an anomaly matching mechanism for 6d theories on their Coulomb branch. It is a global symmetry analog of Green-Schwarz-West-Sagnotti anomaly cancellation, and requires the apparent anomaly mismatch to be a perfect square, . Then Δ I 8 is cancelled by making X 4 an electric/magnetic source for the tensor multiplet, so background gauge field instantons yield charged strings. This requires the coefficients in X 4 to be integrally quantized. We illustrate this for theories. We also consider the SCFTs from N small E8 instantons, verifying that the recent result for its anomaly polynomial fits with the anomaly matching mechanism.

Magnetic-field fluctuations from 0 to 26 Hz observed from a polar-orbiting satellite

International Nuclear Information System (INIS)

Erlandson, R.E.; Zanetti, L.J.; Potemra, T.A.

1989-01-01

The polar orbit of the Viking satellite provides a unique opportunity to obtain observations of magnetic fluctuations at mid-altitudes on the dayside of the magnetosphere and in the polar-cusp region. One type of magnetic-field fluctuation, observed in the dayside magnetosphere, was Pc 1 waves. Pc 1 waves are in the electromagnetic ion-cyclotron mode and are generated by anisotropies in energetic ion distributions. The waves are thought to be generated near the equator and to propagate large distances along magnetic-field lines. Most observations of Pc 1 waves have been obtained near the equator using geosynchronous satellites and on the surface of the earth. The Viking observations provide an opportunity to observe Pc 1 waves at mid-latitudes above the ionosphere and to determine the spectral structure and polarization of the waves. ULF/ELF broadband noise represents a second type of magnetic fluctuation acquired by Viking. This type of magnetic fluctuation was observed at high latitudes near the polar cusp and may be useful in the identification of polar-cusp boundaries. Thirdly, electromagnetic ion-cyclotron waves have also been observed in the polar-cusp region. These waves occur only during an unusually high level of magnetic activity and appear to be generated locally

Magnetically-driven oceans on Jovian satellites

Science.gov (United States)

Gissinger, C.; Petitdemange, L.

2017-12-01

During the last decade, data from Galileo space missions have added strong support for the existence of subsurface liquid oceans on several moons of Jupiter. For instance, it is now commonly accepted that an electrically conducting fluid beneath the icy crust of Europa's surface may explain the variations of the induced field measured near the satellite. These observations have raised many questions regarding the size and the salinity of such subsurface ocean, or how and why the water remains liquid. In addition, the hydrodynamics of such oceans is mostly unknown. These questions are of primary importance since Europa is often considered as a good candidate for the presence of life beyond the Earth. Here, we present the first numerical modeling of the rapidly-rotating magnetohydrodynamic (MHD) flow generated in Europa's interior: due to Jupiter's rotation with respect to Europa, we show that the Lorentz force induced by the time-varying Jovian magnetic field is able to generate an oceanic flow of a few km/h. Our results are understood in the framework of a simple theoretical model and we obtain a scaling law for the prediction of the mean oceanic velocity and the total heating generated inside the ocean of Europa. Finally, by comparing our simulations to Galileo observations, we make predictions on both the thickness and the electrical conductivity of the ocean of different Jovian's satellites.

Magnetic Anomalies over the Mid-Atlantic Ridge near 27{degrees}N.

Science.gov (United States)

Phillips, J D

1967-08-25

Ten magnetic profiles across the mid-Atlantic ridge near 27 degrees N show trends that are parallel to the ridge axis and symmetrical about the ridge axis. The configuration of magnetic bodies that could account for the pattern supports the Vine and Matthews hypothesis for the origin of magnetic anomalies over oceanic ridges. A polarity-reversal time scale inferred from models for sea-floor spreading in the Pacific-Antarctic ridge and radiometrically dated reversals of the geomagnetic field indicates a spreading rate of 1.25 centimeters per year during the last 6 million years and a rate of 1.65 centimeters per year between 6 and 10 million years ago. A similar analysis of more limited data over the mid-Atlantic ridge near 22 degrees N also indicates a change in the spreading rate. Here a rate of 1.4 centimeters per year appears to have been in effect during the last 5 million years; between 5 and 9 million years ago, an increased rate of 1.7 centimeters per year is indicated. The time of occurrence and relative magnitude of these changes in the spreading rate, about 5 to 6 million years ago and 18 to 27 percent, respectively, accords with the spreading rate change implied for the Juan de Fuca ridge in the northeast Pacific.

Toward Continuous GPS Carrier-Phase Time Transfer: Eliminating the Time Discontinuity at an Anomaly.

Science.gov (United States)

Yao, Jian; Levine, Judah; Weiss, Marc

2015-01-01

The wide application of Global Positioning System (GPS) carrier-phase (CP) time transfer is limited by the problem of boundary discontinuity (BD). The discontinuity has two categories. One is "day boundary discontinuity," which has been studied extensively and can be solved by multiple methods [1-8]. The other category of discontinuity, called "anomaly boundary discontinuity (anomaly-BD)," comes from a GPS data anomaly. The anomaly can be a data gap (i.e., missing data), a GPS measurement error (i.e., bad data), or a cycle slip. Initial study of the anomaly-BD shows that we can fix the discontinuity if the anomaly lasts no more than 20 min, using the polynomial curve-fitting strategy to repair the anomaly [9]. However, sometimes, the data anomaly lasts longer than 20 min. Thus, a better curve-fitting strategy is in need. Besides, a cycle slip, as another type of data anomaly, can occur and lead to an anomaly-BD. To solve these problems, this paper proposes a new strategy, i.e., the satellite-clock-aided curve fitting strategy with the function of cycle slip detection. Basically, this new strategy applies the satellite clock correction to the GPS data. After that, we do the polynomial curve fitting for the code and phase data, as before. Our study shows that the phase-data residual is only ~3 mm for all GPS satellites. The new strategy also detects and finds the number of cycle slips by searching the minimum curve-fitting residual. Extensive examples show that this new strategy enables us to repair up to a 40-min GPS data anomaly, regardless of whether the anomaly is due to a data gap, a cycle slip, or a combination of the two. We also find that interference of the GPS signal, known as "jamming", can possibly lead to a time-transfer error, and that this new strategy can compensate for jamming outages. Thus, the new strategy can eliminate the impact of jamming on time transfer. As a whole, we greatly improve the robustness of the GPS CP time transfer.

Jitter reduction of a reaction wheel by management of angular momentum using magnetic torquers in nano- and micro-satellites

Science.gov (United States)

Inamori, Takaya; Wang, Jihe; Saisutjarit, Phongsatorn; Nakasuka, Shinichi

2013-07-01

Nowadays, nano- and micro-satellites, which are smaller than conventional large satellites, provide access to space to many satellite developers, and they are attracting interest as an application of space development because development is possible over shorter time period at a lower cost. In most of these nano- and micro-satellite missions, the satellites generally must meet strict attitude requirements for obtaining scientific data under strict constraints of power consumption, space, and weight. In many satellite missions, the jitter of a reaction wheel degrades the performance of the mission detectors and attitude sensors; therefore, jitter should be controlled or isolated to reduce its effect on sensor devices. In conventional standard-sized satellites, tip-tilt mirrors (TTMs) and isolators are used for controlling or isolating the vibrations from reaction wheels; however, it is difficult to use these devices for nano- and micro-satellite missions under the strict power, space, and mass constraints. In this research, the jitter of reaction wheels is reduced by using accurate sensors, small reaction wheels, and slow rotation frequency reaction wheel instead of TTMs and isolators. The objective of a reaction wheel in many satellite missions is the management of the satellite's angular momentum, which increases because of attitude disturbances. If the magnitude of the disturbance is reduced in orbit or on the ground, the magnitude of the angular momentum that the reaction wheels gain from attitude disturbances in orbit becomes smaller; therefore, satellites can stabilize their attitude using only smaller reaction wheels or slow rotation speed, which cause relatively smaller vibration. In nano- and micro-satellite missions, the dominant attitude disturbance is a magnetic torque, which can be cancelled by using magnetic actuators. With the magnetic compensation, the satellite reduces the angular momentum that the reaction wheels gain, and therefore, satellites do

Experimental study of linear magnetic dichroism in photoionization satellite transitions of atomic rubidium

International Nuclear Information System (INIS)

Jaenkaelae, K.; Alagia, M.; Feyer, V.; Richter, R.; Prince, K. C.

2011-01-01

Laser orientation in the initial state has been used to study the properties of satellite transitions in inner-shell photoionization of rubidium atoms. The linear magnetic dichroism in the angular distribution (LMDAD) has been utilized to probe the continuum waves of orbital angular momentum conserving monopole, and angular momentum changing conjugate satellites, accompanying the 4p ionization of atomic Rb. We show experimentally that LMDAD of both types of satellite transitions is nonzero and that LMDAD of monopole satellites, measured as a function of photon energy, mimics the LMDAD of direct photoionization, whereas the LMDAD of conjugate transitions deviates drastically from that trend. The results indicate that conjugate transitions cannot be described theoretically without explicit inclusion of electron-electron interaction. The present data can thus be used as a very precise test of current models for photoionization.

Research on Modeling of the Agile Satellite Using a Single Gimbal Magnetically Suspended CMG and the Disturbance Feedforward Compensation for Rotors

Science.gov (United States)

Cui, Peiling; Yan, Ning

2012-01-01

The magnetically suspended Control Moment Gyroscope (CMG) has the advantages of long-life, micro-vibration and being non-lubricating, and is the ideal actuator for agile maneuver satellite attitude control. However, the stability of the rotor in magnetic bearing and the precision of the output torque of a magnetically suspended CMG are affected by the rapid maneuvers of satellites. In this paper, a dynamic model of the agile satellite including a magnetically suspended single gimbal control moment gyroscope is built and the equivalent disturbance torque effected on the rotor is obtained. The feedforward compensation control method is used to depress the disturbance on the rotor. Simulation results are given to show that the rotor displacement is obviously reduced. PMID:23235442

Research on Modeling of the Agile Satellite Using a Single Gimbal Magnetically Suspended CMG and the Disturbance Feedforward Compensation for Rotors

Directory of Open Access Journals (Sweden)

Ning Yan

2012-12-01

Full Text Available The magnetically suspended Control Moment Gyroscope (CMG has the advantages of long-life, micro-vibration and being non-lubricating, and is the ideal actuator for agile maneuver satellite attitude control. However, the stability of the rotor in magnetic bearing and the precision of the output torque of a magnetically suspended CMG are affected by the rapid maneuvers of satellites. In this paper, a dynamic model of the agile satellite including a magnetically suspended single gimbal control moment gyroscope is built and the equivalent disturbance torque effected on the rotor is obtained. The feedforward compensation control method is used to depress the disturbance on the rotor. Simulation results are given to show that the rotor displacement is obviously reduced.

Modelling of charged satellite motion in Earth's gravitational and magnetic fields

Science.gov (United States)

Abd El-Bar, S. E.; Abd El-Salam, F. A.

2018-05-01

In this work Lagrange's planetary equations for a charged satellite subjected to the Earth's gravitational and magnetic force fields are solved. The Earth's gravity, and magnetic and electric force components are obtained and expressed in terms of orbital elements. The variational equations of orbit with the considered model in Keplerian elements are derived. The solution of the problem in a fully analytical way is obtained. The temporal rate of changes of the orbital elements of the spacecraft are integrated via Lagrange's planetary equations and integrals of the normalized Keplerian motion obtained by Ahmed (Astron. J. 107(5):1900, 1994).

Magnetization anomaly of Nb3Al strands and instability of Nb3Al Rutherford cables

International Nuclear Information System (INIS)

Yamada, Ryuji; Kikuchi, Akihiro; Wake, Masayoshi

2006-01-01

Using a Cu stabilized Nb 3 Al strand with Nb matrix, a 30 meter long Nb 3 Al Rutherford cable was made by a collaboration of Fermilab and NIMS. Recently the strand and cable were tested. In both cases instability was observed at around 1.5 Tesla. The magnetization of this Nb 3 Al strand was measured first using a balanced coil magnetometer at 4.2 K. Strands showed an anomalously large magnetization behavior around at 1.6 T, which is much higher than the usual B c2 ∼ 0.5 Tesla (4.2 K) of Nb matrix. This result is compared with the magnetization data of short strand samples using a SQUID magnetometer, in which a flux-jump signal was observed at 0.5 Tesla, but not at higher field. As a possible explanation for this magnetization anomaly, the interfilament coupling through the thin Nb films in the strands is suggested. The instability problem observed in low field tests of the Nb 3 Al Rutherford cables is attributed to this effect

Global Monitoring RSEM System for Crop Production by Incorporating Satellite-based Photosynthesis Rates and Anomaly Data of Sea Surface Temperature

Science.gov (United States)

Kaneko, D.; Sakuma, H.

2014-12-01

The first author has been developing RSEM crop-monitoring system using satellite-based assessment of photosynthesis, incorporating meteorological conditions. Crop production comprises of several stages and plural mechanisms based on leaf photosynthesis, surface energy balance, and the maturing of grains after fixation of CO2, along with water exchange through soil vegetation-atmosphere transfer. Grain production in prime countries appears to be randomly perturbed regionally and globally. Weather for crop plants reflects turbulent phenomena of convective and advection flows in atmosphere and surface boundary layer. It has been difficult for scientists to simulate and forecast weather correctly for sufficiently long terms to crop harvesting. However, severely poor harvests related to continental events must originate from a consistent mechanism of abnormal energetic flow in the atmosphere through both land and oceans. It should be remembered that oceans have more than 100 times of energy storage compared to atmosphere and ocean currents represent gigantic energy flows, strongly affecting climate. Anomalies of Sea Surface Temperature (SST), globally known as El Niño, Indian Ocean dipole, and Atlantic Niño etc., affect the seasonal climate on a continental scale. The authors aim to combine monitoring and seasonal forecasting, considering such mechanisms through land-ocean biosphere transfer. The present system produces assessments for all continents, specifically monitoring agricultural fields of main crops. Historical regions of poor and good harvests are compared with distributions of SST anomalies, which are provided by NASA GSFC. Those comparisons fairly suggest that the Worst harvest in 1993 and the Best in 1994 relate to the offshore distribution of low temperature anomalies and high gaps in ocean surface temperatures. However, high-temperature anomalies supported good harvests because of sufficient solar radiation for photosynthesis, and poor harvests because

Interpretation of CHAMP Magnetic Anomaly Data over the Pannonian Basin Region Using Lower Altitude Horizontal Gradient Data

Science.gov (United States)

Taylor, P. T.; Kis, K. I.; Wittmann, G.

2013-01-01

The ESA SWARM mission will have three earth orbiting magnetometer bearing satellites one in a high orbit and two side-by-side in lower orbits. These latter satellites will record a horizontal magnetic gradient. In order to determine how we can use these gradient measurements for interpretation of large geologic units we used ten years of CHAMP data to compute a horizontal gradient map over a section of southeastern Europe with our goal to interpret these data over the Pannonian Basin of Hungary.

Thermal infrared anomalies of several strong earthquakes.

Science.gov (United States)

Wei, Congxin; Zhang, Yuansheng; Guo, Xiao; Hui, Shaoxing; Qin, Manzhong; Zhang, Ying

2013-01-01

In the history of earthquake thermal infrared research, it is undeniable that before and after strong earthquakes there are significant thermal infrared anomalies which have been interpreted as preseismic precursor in earthquake prediction and forecasting. In this paper, we studied the characteristics of thermal radiation observed before and after the 8 great earthquakes with magnitude up to Ms7.0 by using the satellite infrared remote sensing information. We used new types of data and method to extract the useful anomaly information. Based on the analyses of 8 earthquakes, we got the results as follows. (1) There are significant thermal radiation anomalies before and after earthquakes for all cases. The overall performance of anomalies includes two main stages: expanding first and narrowing later. We easily extracted and identified such seismic anomalies by method of "time-frequency relative power spectrum." (2) There exist evident and different characteristic periods and magnitudes of thermal abnormal radiation for each case. (3) Thermal radiation anomalies are closely related to the geological structure. (4) Thermal radiation has obvious characteristics in abnormal duration, range, and morphology. In summary, we should be sure that earthquake thermal infrared anomalies as useful earthquake precursor can be used in earthquake prediction and forecasting.

Modelling the Earth's Main Magnetic Field by the spinning Astrid-2 satellite

DEFF Research Database (Denmark)

Merayo, Jose Maria Garcia; Jørgensen, Peter Siegbjørn; Risbo, T.

1999-01-01

and therefore the mapping of the Earth's magnetic field may be possible. The spinning of the spacecraft about a certain axis makes the stabilisation in space possible. This fact and the well distributed data over the globe makes the magnetic data well suited for the estimation of the magnetic field model......The Swedish micro-satellite Astrid-2 was successfully launched into a near polar orbit last December 98. Despite the fact that its primary mission was the research of Auroral phenomena, the magnetic instrumentation has been designed to accomplish high resolution vector field magnetic measurements...... at the spacecraft altitude (circa 1000km). Several methods for field modelling are presented in this paper with the assumption that the direction of the spin axis is nearly constant. In any case the orientation of the magnetometer is to bedetermined simultaneously with the instrument calibration and main field...

Detecting ecosystem performance anomalies for land management in the upper colorado river basin using satellite observations, climate data, and ecosystem models

Science.gov (United States)

Gu, Yingxin; Wylie, B.K.

2010-01-01

This study identifies areas with ecosystem performance anomalies (EPA) within the Upper Colorado River Basin (UCRB) during 2005-2007 using satellite observations, climate data, and ecosystem models. The final EPA maps with 250-m spatial resolution were categorized as normal performance, underperformance, and overperformance (observed performance relative to weather-based predictions) at the 90% level of confidence. The EPA maps were validated using "percentage of bare soil" ground observations. The validation results at locations with comparable site potential showed that regions identified as persistently underperforming (overperforming) tended to have a higher (lower) percentage of bare soil, suggesting that our preliminary EPA maps are reliable and agree with ground-based observations. The 3-year (2005-2007) persistent EPA map from this study provides the first quantitative evaluation of ecosystem performance anomalies within the UCRB and will help the Bureau of Land Management (BLM) identify potentially degraded lands. Results from this study can be used as a prototype by BLM and other land managers for making optimal land management decisions. ?? 2010 by the authors.

Obtaining Magnetic Properties of Meteorites Using Magnetic Scanner

Science.gov (United States)

Kletetschka, G.; Nabelek, L.; Mazanec, M.; Simon, K.; Hruba, J.

2015-12-01

Magnetic images of Murchison meteorite's and Chelyabinsk meteorite's thin section have been obtained from magnetic scanning system from Youngwood Science and Engineering (YSE) capable of resolving magnetic anomalies down to 10-3 mT range from about 0.3 mm distance between the probe and meteorite surface (resolution about 0.15 mm). Anomalies were produced repeatedly, each time after application of magnetic field pulse of varying amplitude and constant, normal or reversed, direction. This process resulted in both magnetizing and demagnetizing of the meteorite thin section, while keeping the magnetization vector in the plane of the thin section. Analysis of the magnetic data allows determination of coercivity of remanence (Bcr) for the magnetic sources in situ. Value of Bcr is critical for calculating magnetic forces applicable during missions to asteroids where gravity is compromised. Bcr was estimated by two methods. First method measured varying dipole magnetic field strength produced by each anomaly in the direction of magnetic pulses. Second method measured deflections of the dipole direction from the direction of magnetic pulses (Nabelek et al., 2015). Nabelek, L., Mazanec, M., Kdyr, S., and Kletetschka, G., 2015, Magnetic, in situ, mineral characterization of Chelyabinsk meteorite thin section: Meteoritics & Planetary Science.

Long periods (1 -10 mHz) geomagnetic pulsations variation with solar cycle in South Atlantic Magnetic Anomaly

Science.gov (United States)

Rigon Silva, Willian; Schuch, Nelson Jorge; Guimarães Dutra, Severino Luiz; Babulal Trivedi, Nalin; Claudir da Silva, Andirlei; Souza Savian, Fernando; Ronan Coelho Stekel, Tardelli; de Siqueira, Josemar; Espindola Antunes, Cassio

The occurrence and intensity of the geomagnetic pulsations Pc-5 (2-7 mHz) and its relationship with the solar cycle in the South Atlantic Magnetic Anomaly -SAMA is presented. The study of geomagnetic pulsations is important to help the understanding of the physical processes that occurs in the magnetosphere region and help to predict geomagnetic storms. The fluxgate mag-netometers H, D and Z, three axis geomagnetic field data from the Southern Space Observatory -SSO/CRS/INPE -MCT, São Martinho da Serra (29.42° S, 53.87° W, 480m a.s.l.), RS, Brasil, a were analyzed and correlated with the solar wind parameters (speed, density and temperature) from the ACE and SOHO satellites. A digital filtering to enhance the 2-7 mHz geomagnetic pulsations was used. Five quiet days and five perturbed days in the solar minimum and in the solar maximum were selected for this analysis. The days were chosen based on the IAGA definition and on the Bartels Musical Diagrams (Kp index) for 2001 (solar maximum) and 2008 (solar minimum). The biggest Pc-5 amplitude averages differences between the H-component is 78,35 nT for the perturbed days and 1,60nT for the quiet days during the solar maximum. For perturbed days the average amplitude during the solar minimum is 8,32 nT, confirming a direct solar cycle influence in the geomagnetic pulsations intensity for long periods.

Seafloor spreading anomalies and crustal ages of the Clarion-Clipperton Zone

OpenAIRE

Udo Barckhausen; Meike Bagge; Douglas S. Wilson

2013-01-01

The Clarion-Clipperton Zone (CCZ) of the central Pacific is one of the few regions in the world’s oceans that are still lacking full coverage of reliable identifications of seafloor spreading anomalies. This is mainly due to the geometry of the magnetic lineations’ strike direction sub-parallel to the Earth’s magnetic field vector near the equator resulting in low amplitude magnetic anomalies, and the remoteness of the region which has hindered systematic surveying in the past. Following rece...

PENENTUAN POSISI SUMBER PROSPEK PANAS BUMI BERDASARKAN DATA ANOMALI MAGNETDI DAERAH AKESAHU, PULAU TIDORE, MALUKU UTARA

Directory of Open Access Journals (Sweden)

Rohima Wahyu Ningrum

2015-04-01

Full Text Available Penelitian geofisika dengan menggunakan metode magnetik yaitu dengan alat Magnetometer Fluxgate. Luas daerah penyelidikan ± 1 km x 1 km, dibatasi oleh koordinat geografis antara 127° 27’ 42” s/d 127° 27’ 43” BT dan 0° 43’ 17” s/d 0° 43’ 19” LU . Penelitian ini bertujuan untuk mengetahui posisi sumber prospek panas bumi di daerah Akesahu, Pulau Tidore berdasarkan data anomali medan magnet. Data medan magnet total yang terukur adalah medan utama, medan luar dan medan anomali. Untuk menghilangkan efek-efek anomali dari medan magnet luar dan anomali medan magnet utama dilakukan perhitungan koreksi variasi harian, koreksi drift (kesalahan alat, koreksi penyesuaian, koreksi IGRF, dan pemisahan anomali residual dan regional. Hasil penelitian menunjukkan bahwa, daerah Akesahu, Pulau Tidore memiliki potensi panas bumi yang masih cukup besar yang ditandai dengan adanya manifestasi panas bumi berupa mata air panas. Anomali medan magnet daerah Akesahu ditunjukkan dengan adanya anomali yang rendah (0.90 sampai dengan -2163.09 nT yang memanjang arah utara-selatan di bagian Timur Pulau Tidore. Disamping itu di sekitar mata air panas Akesahu secara geologis didukung dengan adanya empat buah sesar normal. Ini sebagai sistem pengontrol panas bumi yang lainnya di Pulau Tidore.

Inference of Altimeter Accuracy on Along-track Gravity Anomaly Recovery

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LI Yang

2015-04-01

Full Text Available A correlation model between along-track gravity anomaly accuracy, spatial resolution and altimeter accuracy is proposed. This new model is based on along-track gravity anomaly recovery and resolution estimation. Firstly, an error propagation formula of along-track gravity anomaly is derived from the principle of satellite altimetry. Then the mathematics between the SNR (signal to noise ratio and cross spectral coherence is deduced. The analytical correlation between altimeter accuracy and spatial resolution is finally obtained from the results above. Numerical simulation results show that along-track gravity anomaly accuracy is proportional to altimeter accuracy, while spatial resolution has a power relation with altimeter accuracy. e.g., with altimeter accuracy improving m times, gravity anomaly accuracy improves m times while spatial resolution improves m0.4644 times. This model is verified by real-world data.

On-line Flagging of Anomalies and Adaptive Sequential Hypothesis Testing for Fine-feature Characterization of Geosynchronous Satellites

Science.gov (United States)

Chaudhary, A.; Payne, T.; Kinateder, K.; Dao, P.; Beecher, E.; Boone, D.; Elliott, B.

The objective of on-line flagging in this paper is to perform interactive assessment of geosynchronous satellites anomalies such as cross-tagging of a satellites in a cluster, solar panel offset change, etc. This assessment will utilize a Bayesian belief propagation procedure and will include automated update of baseline signature data for the satellite, while accounting for the seasonal changes. Its purpose is to enable an ongoing, automated assessment of satellite behavior through its life cycle using the photometry data collected during the synoptic search performed by a ground or space-based sensor as a part of its metrics mission. The change in the satellite features will be reported along with the probabilities of Type I and Type II errors. The objective of adaptive sequential hypothesis testing in this paper is to define future sensor tasking for the purpose of characterization of fine features of the satellite. The tasking will be designed in order to maximize new information with the least number of photometry data points to be collected during the synoptic search by a ground or space-based sensor. Its calculation is based on the utilization of information entropy techniques. The tasking is defined by considering a sequence of hypotheses in regard to the fine features of the satellite. The optimal observation conditions are then ordered in order to maximize new information about a chosen fine feature. The combined objective of on-line flagging and adaptive sequential hypothesis testing is to progressively discover new information about the features of a geosynchronous satellites by leveraging the regular but sparse cadence of data collection during the synoptic search performed by a ground or space-based sensor. Automated Algorithm to Detect Changes in Geostationary Satellite's Configuration and Cross-Tagging Phan Dao, Air Force Research Laboratory/RVB By characterizing geostationary satellites based on photometry and color photometry, analysts can

Comparison of satellite-derived LAI and precipitation anomalies over Brazil with a thermal infrared-based Evaporative Stress Index for 2003-2013

Science.gov (United States)

Anderson, Martha C.; Zolin, Cornelio A.; Hain, Christopher R.; Semmens, Kathryn; Tugrul Yilmaz, M.; Gao, Feng

2015-07-01

Shortwave vegetation index (VI) and leaf area index (LAI) remote sensing products yield inconsistent depictions of biophysical response to drought and pluvial events that have occurred in Brazil over the past decade. Conflicting reports of severity of drought impacts on vegetation health and functioning have been attributed to cloud and aerosol contamination of shortwave reflectance composites, particularly over the rainforested regions of the Amazon basin which are subject to prolonged periods of cloud cover and episodes of intense biomass burning. This study compares timeseries of satellite-derived maps of LAI from the Moderate Resolution Imaging Spectroradiometer (MODIS) and precipitation from the Tropical Rainfall Mapping Mission (TRMM) with a diagnostic Evaporative Stress Index (ESI) retrieved using thermal infrared remote sensing over South America for the period 2003-2013. This period includes several severe droughts and floods that occurred both over the Amazon and over unforested savanna and agricultural areas in Brazil. Cross-correlations between absolute values and standardized anomalies in monthly LAI and precipitation composites as well as the actual-to-reference evapotranspiration (ET) ratio used in the ESI were computed for representative forested and agricultural regions. The correlation analyses reveal strong apparent anticorrelation between MODIS LAI and TRMM precipitation anomalies over the Amazon, but better coupling over regions vegetated with shorter grass and crop canopies. The ESI was more consistently correlated with precipitation patterns over both landcover types. Temporal comparisons between ESI and TRMM anomalies suggest longer moisture buffering timescales in the deeper rooted rainforest systems. Diagnostic thermal-based retrievals of ET and ET anomalies, such as used in the ESI, provide independent information on the impacts of extreme hydrologic events on vegetation health in comparison with VI and precipitation-based drought

Electromagnetic particle-in-cell simulations of the solar wind interaction with lunar magnetic anomalies.

Science.gov (United States)

Deca, J; Divin, A; Lapenta, G; Lembège, B; Markidis, S; Horányi, M

2014-04-18

We present the first three-dimensional fully kinetic and electromagnetic simulations of the solar wind interaction with lunar crustal magnetic anomalies (LMAs). Using the implicit particle-in-cell code iPic3D, we confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface forming a mini-magnetosphere, as suggested by spacecraft observations and theory. In contrast to earlier magnetohydrodynamics and hybrid simulations, the fully kinetic nature of iPic3D allows us to investigate the space charge effects and in particular the electron dynamics dominating the near-surface lunar plasma environment. We describe for the first time the interaction of a dipole model centered just below the lunar surface under plasma conditions such that only the electron population is magnetized. The fully kinetic treatment identifies electromagnetic modes that alter the magnetic field at scales determined by the electron physics. Driven by strong pressure anisotropies, the mini-magnetosphere is unstable over time, leading to only temporal shielding of the surface underneath. Future human exploration as well as lunar science in general therefore hinges on a better understanding of LMAs.

Lattice anomalies and magnetic excitations of the spin web compound Cu3TeO6

International Nuclear Information System (INIS)

Choi, K Y; Lemmens, P; Choi, E S; Berger, H

2008-01-01

We report on the magnetic susceptibility and Raman scattering measurements of the S = 1/2 three-dimensional (3D) spin web compound Cu 3 TeO 6 . The magnetic susceptibility shows an antiferromagnetic ordering at T N ∼61 K and a deviation from the Curie-Weiss law around 150 K. Raman spectra show the emergence of a new mode at 132 cm -1 for temperatures below T*∼50 K (∼0.8 T N ). At the same temperature, phonon anomalies in intensity and frequency show up. This gives evidence of pronounced magneto-elastic effects. In addition, we observe a two-magnon Raman spectrum around 214 cm -1 . Compared to typical 3D spin systems, its robust temperature dependence suggests that a frustrated spin topology with a reduced spin coordination number also enhances spin-phonon couplings.

Measurement X radiation > 30 KeV in the Brazilian magnetic anomaly with omnidirectional detectors

International Nuclear Information System (INIS)

Pinto Junior, O.; Gonzalez-Alarcon, W.D.; Gonzalez, A.L.C. de; Martin, I.M.; Dutra, S.L.G.; Pinto, I.R.C.A.; Pereira, A.E.C.; Senador, R.

1982-07-01

Atmospheric X-Rays measurements, with energies > 30 KeV, were performed at Sao Jose dos Campos-Brazil (23 0 S, 46 0 W Geographic) on April 14 and December 19, 1981, using omnidirectional NaI (Tl) scintillation counters on board stratospheric balloons. The main purpose of these measurements is to study the dynamics of precipitating electrons at the Brazilian Magnetic Anomaly. Studies on similar measurements during the previous decade seemed to show the existence of approximately 100 KeV precipitating electrons, possibly related to a coulomb scattering with the atmosophere. The studies on the recent measurements try not only to confirm such indications, but also to show further features of the dynamics of precipitating electrons, mainly during magnetically active time intervals. During such intervals, more energetic electrons (up to approximately 1000 KeV) also seem to precipitate, probably due to resonant wave-particle interactions at the low latitude inner magnetosphere. The collected data during the recent measurements seem to indicate the existence of such interactions. (Author) [pt

Magnetospheric Multiscale Satellites Observations of Parallel Electric Fields Associated with Magnetic Reconnection

Science.gov (United States)

Ergun, R. E.; Goodrich, K. A.; Wilder, F. D.; Holmes, J. C.; Stawarz, J. E.; Eriksson, S.; Sturner, A. P.; Malaspina, D. M.; Usanova, M. E.; Torbert, R. B.; Lindqvist, P.-A.; Khotyaintsev, Y.; Burch, J. L.; Strangeway, R. J.; Russell, C. T.; Pollock, C. J.; Giles, B. L.; Hesse, M.; Chen, L. J.; Lapenta, G.; Goldman, M. V.; Newman, D. L.; Schwartz, S. J.; Eastwood, J. P.; Phan, T. D.; Mozer, F. S.; Drake, J.; Shay, M. A.; Cassak, P. A.; Nakamura, R.; Marklund, G.

2016-06-01

We report observations from the Magnetospheric Multiscale satellites of parallel electric fields (E∥ ) associated with magnetic reconnection in the subsolar region of the Earth's magnetopause. E∥ events near the electron diffusion region have amplitudes on the order of 100 mV /m , which are significantly larger than those predicted for an antiparallel reconnection electric field. This Letter addresses specific types of E∥ events, which appear as large-amplitude, near unipolar spikes that are associated with tangled, reconnected magnetic fields. These E∥ events are primarily in or near a current layer near the separatrix and are interpreted to be double layers that may be responsible for secondary reconnection in tangled magnetic fields or flux ropes. These results are telling of the three-dimensional nature of magnetopause reconnection and indicate that magnetopause reconnection may be often patchy and/or drive turbulence along the separatrix that results in flux ropes and/or tangled magnetic fields.

Splenic Anomalies of Shape, Size, and Location: Pictorial Essay

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Adalet Elcin Yildiz

2013-01-01

Full Text Available Spleen can have a wide range of anomalies including its shape, location, number, and size. Although most of these anomalies are congenital, there are also acquired types. Congenital anomalies affecting the shape of spleen are lobulations, notches, and clefts; the fusion and location anomalies of spleen are accessory spleen, splenopancreatic fusion, and wandering spleen; polysplenia can be associated with a syndrome. Splenosis and small spleen are acquired anomalies which are caused by trauma and sickle cell disease, respectively. These anomalies can be detected easily by using different imaging modalities including ultrasonography, computed tomography, magnetic resonance imaging, and also Tc-99m scintigraphy. In this pictorial essay, we review the imaging findings of these anomalies which can cause diagnostic pitfalls and be interpreted as pathologic processes.

Robust satellite techniques for remote sensing of seismically active areas

Energy Technology Data Exchange (ETDEWEB)

Tramutoli, V; Di Bello, G [Potenza Univ., Potenza (Italy). Dipt. di Ingegneria e Fisica dell' Ambiente; Pergola, N; Piscitelli, S [Consiglio Nazionale delle Ricerche, Istituto di Metodologie Avanzate di Analisi Ambientale, Potenza (Italy)

2001-04-01

Several satellite techniques have been recently proposed to remotely map seismically active zones and to monitor geophysical phenomena possibly associated with earthquakes. Even if questionable in terms of their effective applicability, all these techniques highlight as the major problem, still to be overcome, the high number of natural factors (independent of any seismic activity) whose variable contributions to the investigated signal can be so high as to completely mask (or simulate) the space-time anomaly possibly associated to the seismic event under study. A robust approach (RAT) has recently been proposed (and successfully applied in the field of the monitoring of the major environmental risks) which, better than other methods, seems suitable for recognising space-time anomalies in the satellite observation field also in the presence of highly variable contributions from atmospheric (transmittance), surface (emissivity and morphology) and observational (time/season, but also solar and satellite zenithal angles) conditions. This work presents the first preliminary results, based on several years of NOA A/AVHRR observations, regarding its extension to satellite monitoring of thermal anomalies possibly associated to seismically active areas of Southern Italy. The main merits of this approach are its robustness against the possibility of false events detection (specially important for this kind of applications) as well as its intrinsic exportability not only to different geographic areas but also to different satellite instrumental packages.

Robust satellite techniques for remote sensing of seismically active areas

Directory of Open Access Journals (Sweden)

S. Piscitelli

2001-06-01

Full Text Available Several satellite techniques have been recently proposed to remotely map seismically active zones and to monitor geophysical phenomena possibly associated with earthquakes. Even if questionable in terms of their effective applicability, all these techniques highlight as the major problem, still to be overcome, the high number of natural factors (independent of any seismic activity whose variable contributions to the investigated signal can be so high as to completely mask (or simulate the space-time anomaly possibly associated to the seismic event under study. A robust approach (RAT has recently been proposed (and successfully applied in the field of the monitoring of the major environmental risks which, better than other methods, seems suitable for recognising space-time anomalies in the satellite observational field also in the presence of highly variable contributions from atmospheric (transmittance, surface (emissivity and morphology and observational (time/season, but also solar and satellite zenithal angles conditions.This work presents the first preliminary results, based on several years of NOAA/AVHRR observations, regarding its extension to satellite monitoring of thermal anomalies possibly associated to seismically active areas of Southern Italy. The main merits of this approach are its robustness against the possibility of false events detection (specially important for this kind of applications as well as its intrinsic exportability not only to different geographic areas but also to different satellite instrumental packages.

Remote sensing revealed drainage anomalies and related tectonics of South India

Science.gov (United States)

Ramasamy, SM.; Kumanan, C. J.; Selvakumar, R.; Saravanavel, J.

2011-03-01

Drainages have characteristic pattern and life histories with youthful stage in hilly areas, mature stage in plains and old stage in the coastal zones. The deviations from their normal life histories, especially aberrations in their flow pattern in the form of various drainage anomalies have been inferred to be the indications of dominantly the Eustatic and Isostatic changes. This, especially after the advent of Earth Observing Satellites, has attracted the geoscientists from all over the world, for studying such drainage anomalies. In this connection, a study has been undertaken in parts of South India falling south of 14° south latitude to comprehensively map some drainage anomalies like deflected drainages, eyed drainages and compressed meanders and to evolve the tectonic scenario therefrom. The mapping of such mega drainage anomalies and the related lineaments/faults from the satellite digital data and the integration of such lineaments/faults with the overall lineament map of South India showed that the study area is marked by active N-S block faults and NE-SW sinistral and NW-SE dextral strike slip faults. Such an architecture of active tectonic grains indicates that the northerly directed compressive force which has originally drifted the Indian plate towards northerly is still active and deforming the Indian plate.

Multiple-Satellite Observation of Magnetic Dip Event During the Substorm on 10 October 2013

Science.gov (United States)

He, Zhaoguo; Chen, Lunjin; Zhu, Hui; Xia, Zhiyang; Reeves, G. D.; Xiong, Ying; Xie, Lun; Cao, Yong

2017-09-01

We present a multiple-satellite observation of the magnetic dip event during the substorm on 10 October 2013. The observation illustrates the temporal and spatial evolution of the magnetic dip and gives a compelling evidence that ring current ions induce the magnetic dip by enhanced plasma beta. The dip moves with the energetic ions in a comparable drift velocity and affects the dynamics of relativistic electrons in the radiation belt. In addition, the magnetic dip provides a favorable condition for the electromagnetic ion cyclotron (EMIC) wave generation based on the linear theory analysis. The calculated proton diffusion coefficients show that the observed EMIC wave can lead to the pitch angle scattering losses of the ring current ions, which in turn partially relax the magnetic dip in the observations. This study enriches our understanding of magnetic dip evolution and demonstrates the important role of the magnetic dip for the coupling of radiation belt and ring current.

Analysis of pre-earthquake ionospheric anomalies before the global M = 7.0+ earthquakes in 2010

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W. F. Peng

2012-03-01

Full Text Available The pre-earthquake ionospheric anomalies that occurred before the global M = 7.0+ earthquakes in 2010 are investigated using the total electron content (TEC from the global ionosphere map (GIM. We analyze the possible causes of the ionospheric anomalies based on the space environment and magnetic field status. Results show that some anomalies are related to the earthquakes. By analyzing the time of occurrence, duration, and spatial distribution of these ionospheric anomalies, a number of new conclusions are drawn, as follows: earthquake-related ionospheric anomalies are not bound to appear; both positive and negative anomalies are likely to occur; and the earthquake-related ionospheric anomalies discussed in the current study occurred 0–2 days before the associated earthquakes and in the afternoon to sunset (i.e. between 12:00 and 20:00 local time. Pre-earthquake ionospheric anomalies occur mainly in areas near the epicenter. However, the maximum affected area in the ionosphere does not coincide with the vertical projection of the epicenter of the subsequent earthquake. The directions deviating from the epicenters do not follow a fixed rule. The corresponding ionospheric effects can also be observed in the magnetically conjugated region. However, the probability of the anomalies appearance and extent of the anomalies in the magnetically conjugated region are smaller than the anomalies near the epicenter. Deep-focus earthquakes may also exhibit very significant pre-earthquake ionospheric anomalies.

World Digital Magnetic Anomaly Map version 2 (WDMAM v.2) - released for research and education

Science.gov (United States)

CHOI-Dyment, Y.; Lesur, V.; Dyment, J.; Hamoudi, M.; Thebault, E.; Catalan, M.

2015-12-01

The World Digital Magnetic Anomaly Map is an international initiative carried out under the auspices of the International Association of Geomagnetism and Aeronomy (IAGA) and the Commission for the Geological Map of the World (CGMW). A first version of the map has been published and distributed eight years ago (WDMAM v1; Korhonen et al., 2007). We have produced a candidate which has been accepted as the second version of this map (WDMAM v2) at the International Union of Geophysics and Geodesy in Prag, in June 2015. On land, we adopted an alternative approach avoiding any unnecessary processing on existing aeromagnetic compilations. When available, we used the original aeromagnetic data. As a result the final compilation remains an acceptable representation of the national and international data grids. Over oceanic areas the marine data have been extended. In areas of insufficient data coverage, a model has been computed based on a modified digital grid of the oceanic lithosphere age, considering plate motions in the determination of magnetization vector directions. This model has been further adjusted to the available data, resulting in a better representation of the anomalies. The final grid will be periodically upgraded. Version 2.0 has been released and is available at wdmam.org to support both research and education projects. Colleagues willing to contribute data for future releases (and become a co-author of the map) should contact any of the authors or Jerome Dyment (chair of the WDMAM Task Force) at jdy@ipgp.fr .

Coordinated airborne and satellite measurements of equatorial plasma depletions

International Nuclear Information System (INIS)

Weber, E.J.; Brinton, H.C.; Buchau, J.; Moore, J.G.

1982-01-01

A series of experiments was conducted in December 1979 to investigate the structure of plasma depletions in the low latitude, nightime ionosphere. The measurements included all sky imaging photometer (ASIP), ionosonde and amplitude scintillation observations from the AFGL Airborne Ionospheric Observatory (AIO), and in situ ion density measurements from the Atmosphere Explorer (AE-E) Bennett Ion Mass Spectrometer (BIMS). The AIO performed two flights along the Ascension Island (-18 0 MLAT) magnetic meridian: one in the southern hemisphere and one near the Ascension conjugate point in the northern hemisphere. During these flights, measurements from the AE-E satellite at 434 km altitude are compared with simultaneous remote ionospheric measurements from the AIO. Density biteouts of approximately one order of magnitude in the dominant ion O + , were mapped to lower altitudes along magnetic field lines for comparison with 6300-A and 7774-A O I airglow depletions. Because of the different airglow production mechanisms (dissociative recombination of O +2 for 6300 A and radiative recombination of O + for 7774 A) the 6300-A depletions reflect plasma depletions near the bottomside of the F layer, while those at 7774 A are located near the peak of the layer. The O + biteouts map directly into the 7774-A airglow depletions in the same hemisphere and also when traced into the opposite hemisphere, which indicates magnetic flux tube alignment over north-south distances of approx.2220 km. The 6300-A (bottomside) depletions are wider in longitude than the 7774-A (F-peak) depletions near the equatorward edge of the Appleton anomaly. This difference in topside and bottomside structure is used to infer large-scale structure near the anomaly and to relate this to structure, commonly observed near the magnetic equator by the ALTAIR radar

TEST BED FOR THE SIMULATION OF MAGNETIC FIELD MEASUREMENTS OF LOW EARTH ORBIT SATELLITES

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Alberto Gallina

2018-03-01

Full Text Available The paper presents a test bed designed to simulate magnetic environment experienced by a spacecraft on low Earth orbit. It consists of a spherical air bearing located inside a Helmholtz cage. The spherical air bearing is used for simulating microgravity conditions of orbiting bodies while the Helmholtz cage generates a controllable magnetic field resembling the one surrounding a satellite during its motion. Dedicated computer software is used to initially calculate the magnetic field on an established orbit. The magnetic field data is then translated into current values and transmitted to programmable power supplies energizing the cage. The magnetic field within the cage is finally measured by a test article mounted on the air bearing. The paper provides a description of the test bed and the test article design. An experimental test proves the good performance of the entire system.

Situs anomalies on prenatal MRI

International Nuclear Information System (INIS)

Nemec, Stefan F.; Brugger, Peter C.; Nemec, Ursula; Bettelheim, Dieter; Kasprian, Gregor; Amann, Gabriele; Rimoin, David L.; Graham, John M.; Prayer, Daniela

2012-01-01

Objective: Situs anomalies refer to an abnormal organ arrangement, which may be associated with severe errors of development. Due regard being given to prenatal magnetic resonance imaging (MRI) as an adjunct to ultrasonography (US), this study sought to demonstrate the in utero visualization of situs anomalies on MRI, compared to US. Materials and methods: This retrospective study included 12 fetuses with situs anomalies depicted on fetal MRI using prenatal US as a comparison modality. With an MRI standard protocol, the whole fetus was assessed for anomalies, with regard to the position and morphology of the following structures: heart; venous drainage and aorta; stomach and intestines; liver and gallbladder; and the presence and number of spleens. Results: Situs inversus totalis was found in 3/12 fetuses; situs inversus with levocardia in 1/12 fetuses; situs inversus abdominis in 2/12 fetuses; situs ambiguous with polysplenia in 3/12 fetuses, and with asplenia in 2/12 fetuses; and isolated dextrocardia in 1/12 fetuses. Congenital heart defects (CHDs), vascular anomalies, and intestinal malrotations were the most frequent associated malformations. In 5/12 cases, the US and MRI diagnoses were concordant. Compared to US, in 7/12 cases, additional MRI findings specified the situs anomaly, but CHDs were only partially visualized in six cases. Conclusions: Our initial MRI results demonstrate the visualization of situs anomalies and associated malformations in utero, which may provide important information for perinatal management. Using a standard protocol, MRI may identify additional findings, compared to US, which confirm and specify the situs anomaly, but, with limited MRI visualization of fetal CHDs.

The electrical conductivity of the upper mantle and lithosphere from satellite magnetic signal due to ocean tidal flow

Science.gov (United States)

Schnepf, N. R.; Kuvshinov, A. V.; Grayver, A.; Sabaka, T. J.; Olsen, N.

2015-12-01

Global electromagnetic (EM) studies provide information on mantle electrical conductivity with the ultimate aim of understanding the composition, structure, and dynamics of Earth's interior. There is great much interest in mapping the global conductivity of the lithosphere and upper mantle (i.e., depths of 10-400 km) because recent laboratory experiments demonstrate that the electrical conductivity of minerals in these regions are greatly affected by small amounts of water or by partial melt. For decades, studies of lithospheric/mantle conductivity were based on interpretation of magnetic data from a global network of observatories. The recent expansion in magnetic data from low-Earth orbiting satellite missions (Ørsted, CHAMP, SAC-C, and Swarm) has led to a rising interest in probing Earth from space. The largest benefit of using satellite data is much improved spatial coverage. Additionally, and in contrast to ground-based data, satellite data are overall uniform and very high quality. Probing the conductivity of the lithosphere and upper mantle requires EM variations with periods of a few hours. This is a challenging period range for global EM studies since the ionospheric (Sq) source dominates these periods and has a much more complex spatial structure compared to the magnetospheric ring current. Moreover, satellite-based EM induction studies in principle cannot use Sq data since the satellites fly above the Sq source causing the signals to be seen by the satellite as a purely internal source, thus precluding the separation of satellite Sq signals into internal and external parts. Lastly, magnetospheric and ionospheric sources interact inductively with Earth's conducting interior. Fortunately, there exists an alternative EM source in the Sq period range: electric currents generated by oceanic tides. Tides instead interact galvanically with the lithosphere (i.e. by direct coupling of the source currents in the ocean with the underlying substrate), enabling

Daily observations of the development of the ionospheric equatorial anomaly by means of differential Doppler shift method

International Nuclear Information System (INIS)

Huang, Y.N.; Cheng, K.; Chen, S.W.

1987-01-01

The differential Doppler frequency shifts observed by receiving coherent radio signals at frequencies of 150 and 400 MHz transmitted from the polar orbiting satellites of U.S. Navy Navigation Satellite System have been used to deduce the latitudinal variations of the ionospheric total electron content (TEC) near the ionospheric equatorial anomaly crest region. All latitudinal variations of TEC thus obtained for each passage of an NNSS satellite are used to construct daily contour plots of TEC in a latitude versus local time coordinates. It has been shown that these contour plot of TEC can be used to investigate the behavior of TEC around equatorial anomaly crest region. Some results are presented and discussed. 18 references

MATLAB-based algorithm to estimate depths of isolated thin dike-like sources using higher-order horizontal derivatives of magnetic anomalies.

Science.gov (United States)

Ekinci, Yunus Levent

2016-01-01

This paper presents an easy-to-use open source computer algorithm (code) for estimating the depths of isolated single thin dike-like source bodies by using numerical second-, third-, and fourth-order horizontal derivatives computed from observed magnetic anomalies. The approach does not require a priori information and uses some filters of successive graticule spacings. The computed higher-order horizontal derivative datasets are used to solve nonlinear equations for depth determination. The solutions are independent from the magnetization and ambient field directions. The practical usability of the developed code, designed in MATLAB R2012b (MathWorks Inc.), was successfully examined using some synthetic simulations with and without noise. The algorithm was then used to estimate the depths of some ore bodies buried in different regions (USA, Sweden, and Canada). Real data tests clearly indicated that the obtained depths are in good agreement with those of previous studies and drilling information. Additionally, a state-of-the-art inversion scheme based on particle swarm optimization produced comparable results to those of the higher-order horizontal derivative analyses in both synthetic and real anomaly cases. Accordingly, the proposed code is verified to be useful in interpreting isolated single thin dike-like magnetized bodies and may be an alternative processing technique. The open source code can be easily modified and adapted to suit the benefits of other researchers.

The influence of regional surface soil moisture anomalies on forest fires in Siberia observed from satellites

Energy Technology Data Exchange (ETDEWEB)

Bartsch, A [Institute of Photogrammetry and Remote Sensing, Vienna University of Technology, 1040 Vienna (Austria); Balzter, H [Department of Geography, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); George, C, E-mail: ab@ipf.tuwien.ac.a [Earth Observation, Centre for Ecology and Hydrology, Crowmarsh Gifford, Wallingford OX10 8BB (United Kingdom)

2009-10-15

Forest fires are frequent in the Siberian taiga and are predicted to increase in frequency as a result of increased fire risk under drought conditions, and prolonged fire seasons caused by climate change. There is, however, some uncertainty as to the extent to which drought influences forest fire frequency at a regional scale. Here, we present an analysis of satellite derived soil moisture anomaly data from ERS-1/2 (ERS: Earth Resources Satellite) scatterometer data and burned area maps from MODIS/AVHRR/ATSR (Moderate Resolution Imaging Spectroradiometer/Advanced Very High Resolution Radiometer/Along-Track Scanning Radiometer) over Central Siberia for the years 1992-2000. The purpose of this study is to investigate the relationship of remotely sensed soil moisture deviations from the long-term mean and fire within the boreal biome on a sub-continental scale. Results show that wet surface soil moisture conditions limit the extent of burned area. They can prevent the outbreak of fires but the magnitude of a negative (dry) deviation does not determine the maximum size of fire affected areas. It is known from the literature, however, that an ignition is more likely to occur under low surface wetness conditions, such as those that we observed during July and August in both permafrost and non-permafrost regions. Although the burned area under drier conditions in July is lowest over non-permafrost, the actual number of fires is as high as over continuous permafrost. Approximately 80% of all events occurred under such conditions during that month. The fire size was below 50 km{sup 2} under moist conditions. Larger burned areas have in general not been detected when the surface wetness deviation exceeded +5%.

The influence of regional surface soil moisture anomalies on forest fires in Siberia observed from satellites

International Nuclear Information System (INIS)

Bartsch, A; Balzter, H; George, C

2009-01-01

Forest fires are frequent in the Siberian taiga and are predicted to increase in frequency as a result of increased fire risk under drought conditions, and prolonged fire seasons caused by climate change. There is, however, some uncertainty as to the extent to which drought influences forest fire frequency at a regional scale. Here, we present an analysis of satellite derived soil moisture anomaly data from ERS-1/2 (ERS: Earth Resources Satellite) scatterometer data and burned area maps from MODIS/AVHRR/ATSR (Moderate Resolution Imaging Spectroradiometer/Advanced Very High Resolution Radiometer/Along-Track Scanning Radiometer) over Central Siberia for the years 1992-2000. The purpose of this study is to investigate the relationship of remotely sensed soil moisture deviations from the long-term mean and fire within the boreal biome on a sub-continental scale. Results show that wet surface soil moisture conditions limit the extent of burned area. They can prevent the outbreak of fires but the magnitude of a negative (dry) deviation does not determine the maximum size of fire affected areas. It is known from the literature, however, that an ignition is more likely to occur under low surface wetness conditions, such as those that we observed during July and August in both permafrost and non-permafrost regions. Although the burned area under drier conditions in July is lowest over non-permafrost, the actual number of fires is as high as over continuous permafrost. Approximately 80% of all events occurred under such conditions during that month. The fire size was below 50 km 2 under moist conditions. Larger burned areas have in general not been detected when the surface wetness deviation exceeded +5%.

Small discussion of electromagnetic wave anomalies preceding earthquakes

Energy Technology Data Exchange (ETDEWEB)

1980-01-01

Six brief pieces on various aspects of electromagnetic wave anomalies are presented. They cover: earthquake electromagnetic emanations; the use of magnetic induction information for earthquake forecasting; electromagnetic pulse emissions as pre-earthquake indicators; the use of magnetic sensors to determine medium-wavelength field strength for earthquake prediction purposes; magnetic deviation indicators inside reinforced-concrete buildings; and a discussion of the general physical principles involved.

Correlation between the Palaeozoic structures from West Iberian and Grand Banks margins using inversion of magnetic anomalies

Science.gov (United States)

Silva, Elsa A.; Miranda, J. M.; Luis, J. F.; Galdeano, A.

2000-05-01

The Ibero-Armorican Arc (IAA) is a huge geological structure of Pre-Cambrian origin, tightened during hercynian times and deeply affected by the opening of the Atlantic Ocean and the Bay of Biscay. Its remnants now lie in Iberia, north-western France and the Canadian Grand Banks margins. The qualitative correlation between these three blocks has been attempted by several authors (e.g. Lefort, J.P., 1980. Un 'Fit' structural de l'Atlantique Nord: arguments geologiques pour correler les marqueurs geophysiques reconnus sur les deux marges. Mar. Geol. 37, 355-369; Lefort, J.P., 1983. A new geophysical criterion to correlate the Acadian and Hercynian orogenies of Western Europe and Eastern America. Mem. Geol. Soc. Am. 158, 3-18; Galdeano, A., Miranda, J.M., Matte, P., Mouge, P., Rossignol, C., 1990. Aeromagnetic data: A tool for studying the Variscan arc of Western Europe and its correlation with transatlantic structures. Tectonophysics 177, 293-305) using magnetic anomalies, mainly because they seem to preserve the hercynian zonation, in spite of the strong thermal and mechanical processes that took place during rifting and ocean spreading. In this paper, we present a new contribution to the study of the IAA structure based on the processing of a compilation of magnetic data from Iberia and Grand Banks margins. To interpret the magnetic signature, a Fourier-domain-based inversion technique was applied, considering a layer with a constant thickness of 10 km, and taking into account only the induced field. The digital terrain model was derived from ETOPO5 (ETOPO5, 1986. Relief map of the earth's surface. EOS 67, 121) and TerrainBase (TerrainBase, 1995. In: Row III, L.W., Hastings, D.A., Dunbar, P.K. (Eds.), Worldwide Digital Terrain Data, Documentation Manual, CD-ROM Release 1.0. GEODAS-NGDC Key to Geophysical Records. Documentation N. 30, April) databases. The pseudo-susceptibility distribution obtained was repositioned for the 156.5 Ma epoch, using the Srivastava and

Tethered Satellite System Contingency Investigation Board

Science.gov (United States)

1992-11-01

The Tethered Satellite System (TSS-1) was launched aboard the Space Shuttle Atlantis (STS-46) on July 31, 1992. During the attempted on-orbit operations, the Tethered Satellite System failed to deploy successfully beyond 256 meters. The satellite was retrieved successfully and was returned on August 6, 1992. The National Aeronautics and Space Administration (NASA) Associate Administrator for Space Flight formed the Tethered Satellite System (TSS-1) Contingency Investigation Board on August 12, 1992. The TSS-1 Contingency Investigation Board was asked to review the anomalies which occurred, to determine the probable cause, and to recommend corrective measures to prevent recurrence. The board was supported by the TSS Systems Working group as identified in MSFC-TSS-11-90, 'Tethered Satellite System (TSS) Contingency Plan'. The board identified five anomalies for investigation: initial failure to retract the U2 umbilical; initial failure to flyaway; unplanned tether deployment stop at 179 meters; unplanned tether deployment stop at 256 meters; and failure to move tether in either direction at 224 meters. Initial observations of the returned flight hardware revealed evidence of mechanical interference by a bolt with the level wind mechanism travel as well as a helical shaped wrap of tether which indicated that the tether had been unwound from the reel beyond the travel by the level wind mechanism. Examination of the detailed mission events from flight data and mission logs related to the initial failure to flyaway and the failure to move in either direction at 224 meters, together with known preflight concerns regarding slack tether, focused the assessment of these anomalies on the upper tether control mechanism. After the second meeting, the board requested the working group to complete and validate a detailed integrated mission sequence to focus the fault tree analysis on a stuck U2 umbilical, level wind mechanical interference, and slack tether in upper tether

MR imaging of paediatric uterovaginal anomalies

International Nuclear Information System (INIS)

Lang, I.M.; Babyn, P.; Oliver, G.D.

1999-01-01

Background. Transabdominal ultrasound (US) has not proved completely reliable in Muellerian duct anomalies. One study has shown it useful in obstructed uterovaginal anomalies. We are unaware of a study that has used endovaginal ultrasound in children to investigate uterovaginal anomalies. Magnetic resonance imaging (MRI) is now gaining wide acceptance in imaging congenital abnormalities of the genital tract. Objective. To identify the problems and potential pitfalls of using MRI to evaluate the female genital tract in paediatric patients. Materials and methods. A retrospective review of the MRI scans of 19 patients, aged 3 months to 19 years (mean 14 years), with uterovaginal anomalies. Results. The uterovaginal anomalies were categorised into three groups: (1) congenital absence of the Muellerian ducts, or the Mayer-Rokitansky-Kuster-Hauser syndrome (n = 7), (2) disorders of vertical fusion (n = 2) and (3) disorders of lateral fusion (n = 10). Conclusions. MRI is a reliable method for evaluating paediatric uterovaginal anomalies, but should be analysed in conjunction with other imaging modalities (US and genitography). Previous surgery makes interpretation more difficult and, if possible, MRI should be carried out prior to any surgery. An accurate MRI examination can be extremely helpful prior to surgery and it is important for the radiologist to have knowledge of how these complex anomalies are managed and what pitfalls to avoid. (orig.)

Recent Aeromagnetic Anomaly views of the Antarctic continent

Science.gov (United States)

Ferraccioli, F.

2012-04-01

Antarctica is a keystone within the Gondwana and Rodinia supercontinents. However, despite intense geological research along the coastal fringes of Antarctica, the interior of the continent remains one of the most poorly understood regions on Earth. Aeromagnetic investigations are a useful tool to help disclose the structure and the evolution of continents from the Precambrian to the Cenozoic and Antarctica is no exception. Here I review a variety of aeromagnetic studies in East and West Antarctica performed since the completion of the first generation ADMAP -Antarctic Digital Magnetic Anomaly Project- in 2001. In western Dronning Maud, in East Antarctica, aeromagnetic data help delineate the extent of the Jurassic Jutulstraumen subglacial rift that is flanked by remnants of a Grenvillian-age (ca 1.1. Ga) igneous province and magmatic arc. Different magnetic signatures appear to characterize the Coats Land block but reconnaissance surveys are insufficient to fully delineate the extent and significance of the Coats Land block, a possible tectonic tracer of Laurentia within Rodinia (Loewy et al., 2011). Further in the interior of East Antarctica, a mosaic of distinct and hitherto largely unknown Precambrian provinces has recently been revealed by combining aeromagnetic and satellite magnetic data with models of crustal thickness constrained by gravity modeling and seismology (Ferraccioli et al., 2011, Nature). A major collisional suture may lie between the Archean Ruker Province and an inferred Proterozoic Gamburtsev Province but the age of final assembly of central East Antarctica remains uncertain and controversial. I favour a Grenville-age collisional event (linked to Rodinia assembly) or possibly older Paleoproteroic collision, followed by intraplate reactivation, as opposed to Neoproterozoic or Early Cambrian collision linked to East-West Gondwana assembly (Boger, 2011). New aerogeophysical surveys over Prince Elizabeth and Queen Mary Land could test this

Highly regenerable carbon-Fe{sub 3}O{sub 4} core–satellite nanospheres as oxygen reduction electrocatalyst and magnetic adsorbent

Energy Technology Data Exchange (ETDEWEB)

Zhou, Wenqiang [Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, and Institute for Advanced Study, Tongji University, Shanghai 201804 (China); School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Liu, Minmin; Cai, Chao [Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, and Institute for Advanced Study, Tongji University, Shanghai 201804 (China); Zhou, Haijun, E-mail: zhouhaijun@just.edu.cn [School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Liu, Rui, E-mail: ruiliu@tongji.edu.cn [Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, and Institute for Advanced Study, Tongji University, Shanghai 201804 (China)

2017-02-15

We present the synthesis and multifunctional utilization of core-satellite carbon-Fe{sub 3}O{sub 4} nanoparticles to serve as the enabling platform for a range of applications including oxygen reduction reaction (ORR) and magnetic adsorbent. Starting from polydopamine (PDA) nanoparticles and Fe(NO{sub 3}){sub 3}, carbon-Fe{sub 3}O{sub 4} core–satellite nanospheres are synthesized through successive steps of impregnation, ammoniation and carbonization. The synergistic combination of Fe{sub 3}O{sub 4} and N-doped carbon endows the nanocomposite with high electrochemical activity in ORR and mainly four electrons transferred in reaction process. Furthermore, carbon-Fe{sub 3}O{sub 4} nanoparticles used as magnetic adsorbent exhibit the efficient removal of Rhodamine B from an aqueous solution. The recovery and reuse of the adsorbent is demonstrated 5 times without any detectible loss in activity. - Graphical abstract: Starting from polydopamine (PDA) nanoparticles and Fe(NO{sub 3}){sub 3}, carbon-Fe{sub 3}O{sub 4} core–satellite nanospheres are synthesized through successive steps of impregnation, ammoniation and carbonization. The nanocomposites serve as the enabling platform for a range of applications including oxygen reduction reaction (ORR) and magnetic adsorbent. - Highlights: • Carbon-Fe{sub 3}O{sub 4} core–satellite nanospheres are synthesized through successive steps of impregnation, ammoniation and carbonization. • Polydopamine and Fe(NO{sub 3}){sub 3} are precursors for N-doped carbon source and Fe{sub 3}O{sub 4} nanoparticles, respectively. • The nanocomposites exhibit high electrochemical activity in ORR. • The nanocomposites effectively adsorb organic dyes with magnetic recovery and good recycle property.

The magnetic field in the pile-up region at Mars, and its variation with the solar wind

DEFF Research Database (Denmark)

Vennerstrøm, Susanne; Olsen, Nils; Purucker, M.

2003-01-01

[1] The magnetic measurements from the Mars Global Surveyor satellite are used to study the magnetic field on the Martian dayside, and its variation with the solar wind. Because of the lack of solar wind measurements near Mars, solar wind measurements near Earth during a period centered on a Mars......-Earth conjunction are used. Concurrent variations at Mars and Earth related to the interplanetary sector-structure and dynamic pressure variations are demonstrated. The study is confined to the northern hemisphere of Mars in regions where the crustal anomalies are weak. Here we find a close association between...

Spacecraft on-orbit deployment anomalies - What can be done?

Science.gov (United States)

Freeman, Michael T.

1993-04-01

Modern communications satellites rely heavily upon deployable appendage (i.e. solar arrays, communications antennas, etc.) to perform vital functions that enable the spacecraft to effectively conduct mission objectives. Communications and telemetry antennas provide the radiofrequency link between the spacecraft and the earth ground station, permitting data to be transmitted and received from the satellite. Solar arrays serve as the principle source of electrical energy to the satellite, and recharge internal batteries during operation. However, since satellites cannot carry backup systems, if a solar array fails to deploy, the mission is lost. This article examines the subject of on-orbit anomalies related to the deployment of spacecraft appendage, and possible causes of such failures. Topics discussed shall include mechanical launch loading, on-orbit thermal and solar concerns, reliability of spacecraft pyrotechnics, and practical limitations of ground-based deployment testing. Of particular significance, the article will feature an in-depth look at the lessons learned from the successful recovery of the Telesat Canada Anik-E2 satellite in 1991.

Robust satellite techniques for monitoring volcanic eruptions

Energy Technology Data Exchange (ETDEWEB)

Pergola, N.; Pietrapertosa, C. [Consiglio Nazionale delle Ricerche, Istituto di Metodologie Avanzate, Tito Scalo, PZ (Italy); Lacava, T.; Tramutoli, V. [Potenza Universita' della Basilicata, Potenza (Italy). Dipt. di Ingegneria e Fisica dell' Ambiente

2001-04-01

Through this paper the robust approach to monitoring volcanic aerosols by satellite is applied to an extended set of events affecting Stromboli and Etna volcanoes to assess its performance in automated detection of eruptive clouds and in monitoring pre-eruptive emission activities. Using only NOAA/AVHRR data at hand (without any specific atmospheric model or ancillary ground-based measurements) the proposed method automatically discriminates meteorological from eruptive volcanic clouds and, in several cases, identified pre-eruptive anomalies in the emission rates not identified by traditional methods. The main merit of this approach is its effectiveness in recognising field anomalies also in the presence of a highly variable surface background as well as its intrinsic exportability not only on different geographic areas but also on different satellite instrumental packages. In particular, the possibility to extend the proposed method to the incoming new MSG/SEVIRI satellite package (which is going to fly next year) with its improved spectral (specific bands for SO{sub 2}) and temporal (up to 15 min) resolutions has been evaluated representing the natural continuation of this work.

The Wallula fault and tectonic framework of south-central Washington, as interpreted from magnetic and gravity anomalies

Science.gov (United States)

Blakely, Richard J.; Sherrod, Brian; Weaver, Craig S.; Wells, Ray; Rohay, Alan C.

2014-01-01

The Yakima fold and thrust belt (YFTB) in central Washington has accommodated regional, mostly north-directed, deformation of the Cascadia backarc since prior to emplacement of Miocene flood basalt of the Columbia River Basalt Group (CRBG). The YFTB consists of two structural domains. Northern folds of the YFTB strike eastward and terminate at the western margin of a 20-mGal negative gravity anomaly, the Pasco gravity low, straddling the North American continental margin. Southern folds of the YFTB strike southeastward, form part of the Olympic–Wallowa lineament (OWL), and pass south of the Pasco gravity low as the Wallula fault zone. An upper crustal model based on gravity and magnetic anomalies suggests that the Pasco gravity low is caused in part by an 8-km-deep Tertiary basin, the Pasco sub-basin, abutting the continental margin and concealed beneath CRBG. The Pasco sub-basin is crossed by north-northwest-striking magnetic anomalies caused by dikes of the 8.5 Ma Ice Harbor Member of the CRBG. At their northern end, dikes connect with the eastern terminus of the Saddle Mountains thrust of the YFTB. At their southern end, dikes are disrupted by the Wallula fault zone. The episode of NE–SW extension that promoted Ice Harbor dike injection apparently involved strike-slip displacement on the Saddle Mountains and Wallula faults. The amount of lateral shear on the OWL impacts the level of seismic hazard in the Cascadia region. Ice Harbor dikes, as mapped with aeromagnetic data, are dextrally offset by the Wallula fault zone a total of 6.9 km. Assuming that dike offsets are tectonic in origin, the Wallula fault zone has experienced an average dextral shear of 0.8 mm/y since dike emplacement 8.5 Ma, consistent with right-lateral stream offsets observed at other locations along the OWL. Southeastward, the Wallula fault transfers strain to the north-striking Hite fault, the possible location of the M 5.7 Milton-Freewater earthquake in 1936.

Global equivalent magnetization of the oceanic lithosphere

Science.gov (United States)

Dyment, J.; Choi, Y.; Hamoudi, M.; Lesur, V.; Thebault, E.

2015-11-01

As a by-product of the construction of a new World Digital Magnetic Anomaly Map over oceanic areas, we use an original approach based on the global forward modeling of seafloor spreading magnetic anomalies and their comparison to the available marine magnetic data to derive the first map of the equivalent magnetization over the World's ocean. This map reveals consistent patterns related to the age of the oceanic lithosphere, the spreading rate at which it was formed, and the presence of mantle thermal anomalies which affects seafloor spreading and the resulting lithosphere. As for the age, the equivalent magnetization decreases significantly during the first 10-15 Myr after its formation, probably due to the alteration of crustal magnetic minerals under pervasive hydrothermal alteration, then increases regularly between 20 and 70 Ma, reflecting variations in the field strength or source effects such as the acquisition of a secondary magnetization. As for the spreading rate, the equivalent magnetization is twice as strong in areas formed at fast rate than in those formed at slow rate, with a threshold at ∼40 km/Myr, in agreement with an independent global analysis of the amplitude of Anomaly 25. This result, combined with those from the study of the anomalous skewness of marine magnetic anomalies, allows building a unified model for the magnetic structure of normal oceanic lithosphere as a function of spreading rate. Finally, specific areas affected by thermal mantle anomalies at the time of their formation exhibit peculiar equivalent magnetization signatures, such as the cold Australian-Antarctic Discordance, marked by a lower magnetization, and several hotspots, marked by a high magnetization.

Gravity Anomalies and Estimated Topography Derived from Satellite Altimetry

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In many areas of the global ocean, the depth of the seafloor is not well known because survey lines by ships are hundreds of kilometers apart. Satellites carrying...

3-Axis magnetic control: flight results of the TANGO satellite in the PRISMA mission

Science.gov (United States)

Chasset, C.; Noteborn, R.; Bodin, P.; Larsson, R.; Jakobsson, B.

2013-09-01

PRISMA implements guidance, navigation and control strategies for advanced formation flying and rendezvous experiments. The project is funded by the Swedish National Space Board and run by OHB-Sweden in close cooperation with DLR, CNES and the Danish Technical University. The PRISMA test bed consists of a fully manoeuvrable MANGO satellite as well as a 3-axis controlled TANGO satellite without any Δ V capability. PRISMA was launched on the 15th of June 2010 on board DNEPR. The TANGO spacecraft is the reference satellite for the experiments performed by MANGO, either with a "cooperative" or "non-cooperative" behaviour. Small, light and low-cost were the keywords for the TANGO design. The attitude determination is based on Sun sensors and magnetometers, and the active attitude control uses magnetic torque rods only. In order to perform the attitude manoeuvres required to fulfil the mission objectives, using any additional gravity gradient boom to passively stabilize the spacecraft was not allowed. After a two-month commissioning phase, TANGO separated from MANGO on the 11th of August 2010. All operational modes have been successfully tested, and the pointing performance in flight is in accordance with expectations. The robust Sun Acquisition mode reduced the initial tip-off rate and placed TANGO into a safe attitude in MANGO. At the same time, it points its solar panel towards the Sun, and all payload equipments can be switched on without any restriction. This paper gives an overview of the TANGO Attitude Control System design. It then presents the flight results in the different operating modes. Finally, it highlights the key elements at the origin of the successful 3-axis magnetic control strategy on the TANGO satellite.

Probing the earth's gravity field by means of satellite-to-satellite tracking

Science.gov (United States)

Vonbun, F. O.

1977-01-01

Two satellite-to-satellite tracking (sst) tests are described in detail: (1) the ATS-6/Geos-3 and (2) the ATS-6/Apollo-Soyuz experiment. The main purpose of these two experiments was to track via ATS-6 the Geos-3, as well as the Apollo-Soyuz and to use these tracking data to determine both of the orbits at the same time, each of the orbits alone, and to test the two sst links to study local gravity anomalies. A second purpose was to test communications, command and data transmission from the ground via ATS-6 to these spacecraft and back again to the ground.

Magnetism and the interior of the moon

Science.gov (United States)

Dyal, P.; Parkin, C. W.; Daily, W. D.

1974-01-01

During the time period 1961-1972, 11 magnetometers were sent to the moon. The primary purpose of this paper is to review the results of lunar magnetometer data analysis, with emphasis on the lunar interior. Magnetic fields have been measured on the lunar surface at the Apollo 12, 14, 15, and 16 landing sites. The remanent field values at these sites are 38, 103 (maximum), 3, and 327 gammas (maximum), respectively. Simultaneous magnetic field and solar plasma pressure measurements show that the Apollo 12 and 16 remanent fields are compressed during times of high plasma dynamic pressure. Apollo 15 and 16 subsatellite magnetometers have mapped in detail the field above portions of the lunar surface and have placed an upper limit on the global permanent dipole moment. Satellite and surface measurements show strong evidence that the lunar crust is magnetized over much of the lunar globe. Magnetic fields are stronger in highland regions than in mare regions and stronger on the lunar far side than on the near side. The largest magnetic anomaly measured to date is between the craters Van de Graaff and Aitken on the lunar far side.

Lithospheric thickness jumps at the S-Atlantic continental margins from satellite gravity data and modelled isostatic anomalies

Science.gov (United States)

Shahraki, Meysam; Schmeling, Harro; Haas, Peter

2018-01-01

Isostatic equilibrium is a good approximation for passive continental margins. In these regions, geoid anomalies are proportional to the local dipole moment of density-depth distributions, which can be used to constrain the amount of oceanic to continental lithospheric thickening (lithospheric jumps). We consider a five- or three-layer 1D model for the oceanic and continental lithosphere, respectively, composed of water, a sediment layer (both for the oceanic case), the crust, the mantle lithosphere and the asthenosphere. The mantle lithosphere is defined by a mantle density, which is a function of temperature and composition, due to melt depletion. In addition, a depth-dependent sediment density associated with compaction and ocean floor variation is adopted. We analyzed satellite derived geoid data and, after filtering, extracted typical averaged profiles across the Western and Eastern passive margins of the South Atlantic. They show geoid jumps of 8.1 m and 7.0 m for the Argentinian and African sides, respectively. Together with topography data and an averaged crustal density at the conjugate margins these jumps are interpreted as isostatic geoid anomalies and yield best-fitting crustal and lithospheric thicknesses. In a grid search approach five parameters are systematically varied, namely the thicknesses of the sediment layer, the oceanic and continental crusts and the oceanic and the continental mantle lithosphere. The set of successful models reveals a clear asymmetry between the South Africa and Argentine lithospheres by 15 km. Preferred models predict a sediment layer at the Argentine margin of 3-6 km and at the South Africa margin of 1-2.5 km. Moreover, we derived a linear relationship between, oceanic lithosphere, sediment thickness and lithospheric jumps at the South Atlantic margins. It suggests that the continental lithospheres on the western and eastern South Atlantic are thicker by 45-70 and 60-80 km than the oceanic lithospheres, respectively.

Evidence for cosmic ray modulation in temperature records from the South Atlantic Magnetic Anomaly region

Energy Technology Data Exchange (ETDEWEB)

Frigo, E. [Sao Paulo Univ. (Brazil). Dept. de Geofisica; Federal do Pampa Univ., Cacapava do Sul (Brazil); Pacca, I.G. [Sao Paulo Univ. (Brazil). Dept. de Geofisica; Pereira-Filho, A.J. [Sao Paulo Univ. (Brazil). Dept. de Ciencias Atmosfericas; Rampelloto, P.H. [Federal do Pampa Univ., Sao Gabriel (Brazil); Rigozo, N.R. [Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos (Brazil). Div. de Geofisica Espacial

2013-11-01

Possible direct or indirect climatic effects related to solar variability and El Nino-Southern Oscillation (ENSO) were investigated in the southern Brazil region by means of the annual mean temperatures from four weather stations 2 degrees of latitude apart over the South Atlantic Magnetic Anomaly (SAMA) region. Four maximum temperature peaks are evident at all stations in 1940, 1958, 1977 and 2002. A spectral analysis indicates the occurrence of periodicities between 2 and 7 yr, most likely associated with ENSO, and periodicities of approximately 11 and 22 yr, normally associated with solar variability. Cross-wavelet analysis indicated that the signal associated with the 22 yr solar magnetic cycle was more persistent in the last decades, while the 11 yr sunspot cycle and ENSO periodicities were intermittent. Phase-angle analysis revealed that temperature variations and the 22 yr solar cycle were in anti-phase near the SAMA center. Results show an indirect indication of possible relationships between the variability of galactic cosmic rays and climate change on a regional scale.

Workflow with pitfalls to derive a regional airborne magnetic compilation

Science.gov (United States)

Brönner, Marco; Baykiev, Eldar; Ebbing, Jörg

2017-04-01

Today, large scale magnetic maps are usually a patchwork of different airborne surveys from different size, different resolution and different years. Airborne magnetic acquisition is a fast and economic method to map and gain geological and tectonic information for large areas, onshore and offshore. Depending on the aim of a survey, acquisition parameters like altitude and profile distance are usually adjusted to match the purpose of investigation. The subsequent data processing commonly follows a standardized workflow comprising core-field subtraction and line leveling to yield a coherent crustal field magnetic grid for a survey area. The resulting data makes it possible to correlate with geological and tectonic features in the subsurface, which is of importance for e.g. oil and mineral exploration. Crustal scale magnetic interpretation and modeling demand regional compilation of magnetic data and the merger of adjacent magnetic surveys. These studies not only focus on shallower sources, reflected by short to intermediate magnetic wavelength anomalies, but also have a particular interest in the long wavelength deriving from deep seated sources. However, whilst the workflow to produce such a merger is supported by quite a few powerful routines, the resulting compilation contains several pitfalls and limitations, which were discussed before, but still are very little recognized. The maximum wavelength that can be resolved of each individual survey is directly related to the survey size and consequently a merger will contribute erroneous long-wavelength components in the magnetic data compilation. To minimize this problem and to homogenous the longer wavelengths, a first order approach is the combination of airborne and satellite magnetic data commonly combined with the compilation from airborne data, which is sufficient only under particular preconditions. A more advanced approach considers the gap in frequencies between airborne and satellite data, which motivated

BEARS: a multi-mission anomaly response system

Science.gov (United States)

Roberts, Bryce A.

2009-05-01

The Mission Operations Group at UC Berkeley's Space Sciences Laboratory operates a highly automated ground station and presently a fleet of seven satellites, each with its own associated command and control console. However, the requirement for prompt anomaly detection and resolution is shared commonly between the ground segment and all spacecraft. The efficient, low-cost operation and "lights-out" staffing of the Mission Operations Group requires that controllers and engineers be notified of spacecraft and ground system problems around the clock. The Berkeley Emergency Anomaly and Response System (BEARS) is an in-house developed web- and paging-based software system that meets this need. BEARS was developed as a replacement for an existing emergency reporting software system that was too closedsource, platform-specific, expensive, and antiquated to expand or maintain. To avoid these limitations, the new system design leverages cross-platform, open-source software products such as MySQL, PHP, and Qt. Anomaly notifications and responses make use of the two-way paging capabilities of modern smart phones.

On verifying magnetic dipole moment of a magnetic torquer by experiments

Science.gov (United States)

Kuyyakanont, Aekjira; Kuntanapreeda, Suwat; Fuengwarodsakul, Nisai H.

2018-01-01

Magnetic torquers are used for the attitude control of small satellites, such as CubeSats with Low Earth Orbit (LEO). During the design of magnetic torquers, it is necessary to confirm if its magnetic dipole moment is enough to control the satellite attitude. The magnetic dipole moment can affect the detumbling time and the satellite rotation time. In addition, it is also necessary to understand how to design the magnetic torquer for operation in a CubeSat under the space environment at LEO. This paper reports an investigation of the magnetic dipole moment and the magnetic field generated by a circular air-coil magnetic torquer using experimental measurements. The experiment testbed was built on an air-bearing under a magnetic field generated by a Helmholtz coil. This paper also describes the procedure to determine and verify the magnetic dipole moment value of the designed circular air-core magnetic torquer. The experimental results are compared with the design calculations. According to the comparison results, the designed magnetic torquer reaches the required magnetic dipole moment. This designed magnetic torquer will be applied to the attitude control systems of a 1U CubeSat satellite in the project “KNACKSAT.”

Thermal emission before earthquakes by analyzing satellite infra-red data

Science.gov (United States)

Ouzounov, D.; Taylor, P.; Bryant, N.; Pulinets, S.; Freund, F.

2004-05-01

Satellite thermal imaging data indicate long-lived thermal anomaly fields associated with large linear structures and fault systems in the Earth's crust but also with short-lived anomalies prior to major earthquakes. Positive anomalous land surface temperature excursions of the order of 3-4oC have been observed from NOAA/AVHRR, GOES/METEOSAT and EOS Terra/Aqua satellites prior to some major earthquake around the world. The rapid time-dependent evolution of the "thermal anomaly" suggests that is changing mid-IR emissivity from the earth. These short-lived "thermal anomalies", however, are very transient therefore there origin has yet to be determined. Their areal extent and temporal evolution may be dependent on geology, tectonic, focal mechanism, meteorological conditions and other factors.This work addresses the relationship between tectonic stress, electro-chemical and thermodynamic processes in the atmosphere and increasing mid-IR flux as part of a larger family of electromagnetic (EM) phenomena related to seismic activity.We still need to understand better the link between seismo-mechanical processes in the crust, on the surface, and at the earth-atmospheric interface that trigger thermal anomalies. This work serves as an introduction to our effort to find an answer to this question. We will present examples from the strong earthquakes that have occurred in the Americas during 2003/2004 and the techniques used to record the thermal emission mid-IR anomalies, geomagnetic and ionospheric variations that appear to associated with impending earthquake activity.

Magnetic resonance angiography of cerebral developmental venous anomalies: its role in differential diagnosis

International Nuclear Information System (INIS)

Ostertun, B.; Solymosi, L.

1993-01-01

CT, MRI and contrast angiography of 20 patients with 21 developmental venous anomalies (DVAs), so-called venous angiomas, were compared with magnetic resonance angiography employing a two-dimensional time-of-flight technique (2D-MRA). MRA was diagnostic in 17 DVAs, when both the primary 2D slices and the maximum-intensity-protection images were read. Contrast angiography still provides the best visualization of both DVA components: dilated medullary veins and transcerebral draining vein; however, it is an invasive procedure and delivers no information about brain parenchyma. We regard MRI as necessary in cases with a suspected DVA because of the high rate of association with cavernomas: 33% in this study. Acute neurological symptoms were caused by haemorrhage from an associated cavernoma and not from the DVA in 4 such cases. Thus MRA combined with MRI obviates angiography in most cases and offers a noninvasive diagnostic strategy adequate for DVAs. (orig.)

Statistical study of phase relationships between magnetic and plasma thermal pressures in the near-earth magnetosphere using the THEMIS satellites

Science.gov (United States)

Nishi, K.; Kazuo, S.

2017-12-01

The auroral finger-like structures appear in the equatorward part of the auroral oval in the diffuse auroral region, and contribute to the auroral fragmentation into patches during substorm recovery phase. In our previous presentations, we reported the first conjugate observation of auroral finger-like structures using the THEMIS GBO cameras and the THEMIS satellites, which was located at a radial distance of 9 Re in the dawnside plasma sheet. In this conjugate event, we found anti-phase fluctuation of plasma pressure and magnetic pressure with a time scale of 5-20 min in the plasma sheet. This observational fact is consistent with the idea that the finger-like structures are caused by a pressure-driven instability in the balance of plasma and magnetic pressures in the magnetosphere. Then we also searched simultaneous observation events of auroral finger-like structures with the RBSP satellites which have an apogee of 5.8 Re in the inner magnetosphere. Contrary to the first result, the observed variation of plasma and magnetic pressures do not show systematic phase relationship. In order to investigate these phase relationships between plasma and magnetic pressures in the magnetosphere, we statistically analyzed these pressure data using the THEMIS-E satellite for one year in 2011. In the preliminary analysis of pressure variation spectra, we found that out of phase relationship between magnetic and plasma pressures occupied 40 % of the entire period of study. In the presentation, we will discuss these results in the context of relationships between the pressure fluctuations and the magnetospheric instabilities that can cause auroral finger-like structures.

Lithologic boundaries from gravity and magnetic anomalies over ...

Indian Academy of Sciences (India)

Pramod Kumar Yadav

2018-03-02

Mar 2, 2018 ... nature of causative source using Euler depth solutions and radially averaged power spectrum (RAPS). Residual anomaly maps of gravity and ... the lateral boundaries and nature of the source. It seems that the source is of ..... Goldfarb R J and Richards J P,. The Economic Geology Publishing Company, pp.

Coronary artery anomalies. Diagnosis and classification based on cardiac CT and MRI (CMR) - from ALCAPA to anomalies of termination

International Nuclear Information System (INIS)

Heermann, Philipp; Heindel, Walter; Schuelke, Christoph

2017-01-01

Coronary artery anomalies encompass a clinically and anatomically variable spectrum including physiological variants and pathophysiologically relevant anomalies. The majority of the variants has no hemodynamic relevance and is often detected accidentally. The recognition of the rare and relevant anomalies that cause either relevant shunt volumes leading to myocardial ischemia or ventricular tachyarrhythmias with the risk of sudden cardiac death is of major importance. This review is based on a literature search in PubMed conducted using the key words ''coronary artery'' and/or ''anomaly'' and/or ''anomalous origin'' and/or ''myocardial bridging'' and/or ''coronary artery fistula'' and/or ''Bland-White-Garland'' and/or ''ALCAPA''. Coronary artery anomalies can be anatomically subdivided into anomalies of origin, course and termination. The method of choice for anatomical imaging is ECG-triggered or gated multislice CT (MSCT) that provides high spatial resolution and the capability of multiplanar reconstructions. It facilitates the delineation of the precise course of all three coronary arteries and thus allows for correct classification in the anatomical classification system of coronary artery anomalies. The strengths of cardiac magnetic resonance imaging (CMR) are the evaluation of cardiac morphology, myocardial tissue properties and myocardial function. Basic methods are the analysis of myocardial contraction and perfusion with and without pharmacologic stress. Furthermore, potential shunt volumes could be quantified by phase contrast imaging or volumetry.

Distribution of the Crustal Magnetic Field in Sichuan-Yunnan Region, Southwest China

Directory of Open Access Journals (Sweden)

Chunhua Bai

2014-01-01

Full Text Available Based on the new and higher degree geomagnetic model NGDC-720-V3, we have investigated the spatial distribution, the altitude decay characteristics of the crustal magnetic anomaly, the contributions from different wavelength bands to the anomaly, and the relationship among the anomaly, the geological structure, and the geophysical field in Sichuan-Yunnan region of China. It is noted that the most outstanding feature in this area is the strong positive magnetic anomaly in Sichuan Basin, a geologically stable block. Contrasting with this feature, a strong negative anomaly can be seen nearby in Longmen Mountain block, an active block. This contradiction implies a possible relationship between the magnetic field and the geological activity. Completely different feature in magnetic field distribution is seen in the central Yunnan block, another active region, where positive and negative anomalies distribute alternatively, showing a complex magnetic anomaly map. Some fault belts, such as the Longmen Mountain fault, Lijiang-Xiaojinhe fault, and the Red River fault, are the transitional zones of strong and weak or negative and positive anomalies. The corresponding relationship between the magnetic anomaly and the geophysical fields was confirmed.

Worldwide complete spherical Bouguer and isostatic anomaly maps

Science.gov (United States)

Bonvalot, S.; Balmino, G.; Briais, A.; Peyrefitte, A.; Vales, N.; Biancale, R.; Gabalda, G.; Reinquin, F.

2011-12-01

et al., 2008), which represents the best up-to-date global gravity model (including surface gravity measurements from land, marine and airborne surveys as well as gravity and altimetry satellite measurements). The surface gravity anomaly (free air) is computed at the Earth's surface in the context of Molodensky theory and includes corrections from the mass of the atmosphere. The way gravity anomalies are computed on a worldwide basis slightly differs from the classical usage, but meets modern concerns which tend to take the real Earth into account. The resulting anomaly maps and grids will be distributed for scientific and education purposes by the Commission for the Geological Map of the World (CGMW) with support of UNESCO and other institutions. Upgraded versions might be done as soon as new global gravity model is available (including satellite GOCE and new surface measurements: ground, airborne). Visit / contact BGI (http://bgi.omp.obs-mip.fr) and CCMW (http://ccgm.free.fr) for more information.

Preliminary Analyses of Beidou Signal-In Anomaly Since 2013

Science.gov (United States)

Wu, Y.; Ren, J.; Liu, W.

2016-06-01

As BeiDou navigation system has been operational since December 2012. There is an increasing desire to use multiple constellation to improve positioning performance. The signal-in-space (SIS) anomaly caused by the ground control and the space vehicle is one of the major threats to affect the integrity. For a young Global Navigation Satellite System, knowledge about SIS anomalies in history is very important for not only assessing the SIS integrity performance of a constellation but also providing the assumption for ARAIM (Advanced Receiver Autonomous Integrity Monitoring). In this paper, the broadcast ephemerides and the precise ones are pre-processed for avoiding the false anomaly identification. The SIS errors over the period of Mar. 2013-Feb. 2016 are computed by comparing the broadcast ephemerides with the precise ones. The time offsets between GPST (GPS time) and BDT (BeiDou time) are estimated and removed by an improved estimation algorithm. SIS worst-UREs are computed and a RMS criteria are investigated to identify the SIS anomalies. The results show that the probability of BeiDou SIS anomalies is in 10-3 level in last three years. Even though BeiDou SIS integrity performance currently cannot match the GPS integrity performances, the result indicates that BeiDou has a tendency to improve its integrity performance.

An Unsupervised Anomalous Event Detection and Interactive Analysis Framework for Large-scale Satellite Data

Science.gov (United States)

LIU, Q.; Lv, Q.; Klucik, R.; Chen, C.; Gallaher, D. W.; Grant, G.; Shang, L.

2016-12-01

Due to the high volume and complexity of satellite data, computer-aided tools for fast quality assessments and scientific discovery are indispensable for scientists in the era of Big Data. In this work, we have developed a framework for automated anomalous event detection in massive satellite data. The framework consists of a clustering-based anomaly detection algorithm and a cloud-based tool for interactive analysis of detected anomalies. The algorithm is unsupervised and requires no prior knowledge of the data (e.g., expected normal pattern or known anomalies). As such, it works for diverse data sets, and performs well even in the presence of missing and noisy data. The cloud-based tool provides an intuitive mapping interface that allows users to interactively analyze anomalies using multiple features. As a whole, our framework can (1) identify outliers in a spatio-temporal context, (2) recognize and distinguish meaningful anomalous events from individual outliers, (3) rank those events based on "interestingness" (e.g., rareness or total number of outliers) defined by users, and (4) enable interactively query, exploration, and analysis of those anomalous events. In this presentation, we will demonstrate the effectiveness and efficiency of our framework in the application of detecting data quality issues and unusual natural events using two satellite datasets. The techniques and tools developed in this project are applicable for a diverse set of satellite data and will be made publicly available for scientists in early 2017.

MR imaging features of the congenital uterine anomalies

International Nuclear Information System (INIS)

Hamcan, S.; Akgun, V.; Battal, B.; Kocaoglu, M.

2012-01-01

Full text: Introduction: Congenital uterine anomalies are common and usually asymptomatic. The agenesis, malfusion or deficient resorption of the Mullerian canals during embryogenesis may lead to these anomalies. Although ultrasonography (US) is the first step imaging technique in assessment of the uterine pathologies, it can be insufficient in differentiation of them. Magnetic resonance (MR) imaging is an adequate imaging technique in depicting pelvic anatomy and different types of uterine anomalies. Objectives and tasks: In this article, we aimed to present imaging features of the uterine anomalies. Material and methods: Pelvic MR scans of the cases who were referred to our radiology department for suspicious uterine anomaly were evaluated retrospectively. Results: We determined uniconuate uterus (type II), uterus didelphys (type III), bicornuate uterus (type IV), uterine septum (type V) and arcuate uterus (type VI) anomalies according to ASRM (American Society of Reproductive Medicine) classification. Conclusion: In cases with such pathologies leading to obstruction, dysmenorrhea or palpable pelvic mass in the puberty are the main clinical presentations. In cases without obstruction, infertility or multiple abortions can be encountered in reproductive ages. The identification of the subtype of the uterine anomalies is important for the preoperative planning of the management. MR that has multiplanar imaging capability and high soft tissue resolution is a non-invasive and the most important imaging modality for the detection and classification of the uterine anomalies

Small-scale features in the Earth's magnetic field observed by Magsat.

Science.gov (United States)

Cain, J.C.; Schmitz, D.R.; Muth, L.

1984-01-01

A spherical harmonic expansion to degree and order 29 is derived using a selected magnetically quiet sample of Magsat data. Global maps representing the contribution due to terms of the expansion above n = 13 at 400 km altitude are compared with previously published residual anomaly maps and shown to be similar, even in polar regions. An expansion with such a high degree and order displays all but the sharpest features seen by the satellite and gives a more consistent picture of the high-order field structure at a constant altitude than do component maps derived independently. -Authors

Geophysical anomalies associated with uranium mineralization from Beldih mine, South Purulia Shear Zone, India

International Nuclear Information System (INIS)

Mandal, Animesh; Biswas, Arkoprovo; Mittal, Saurabh; Mohanty, William K.; Sharma, Shashi Prakash; Sengupta, Debashish; Sen, Joydip; Bhatt, A.K.

2013-01-01

Beldih mine at the central part of the South Purulia Shear Zone (SPSZ) has been reported with low grade uranium-bearing formation within quartz-magnetite-apatite host in kaolinized formation. Therefore, the present integrated geophysical study with gravity, magnetic, radiometric, very low frequency electromagnetic (VLF) and gradient resistivity profiling methods around the known mineralized zones aimed at identifying the exact geophysical signatures and lateral extent of these uranium mineralization bands. The closely spaced gravity-magnetic contours over the low to high anomaly transition zones of Bouguer, reduced-to-pole magnetic, and trend surface separated residual gravity-magnetic anomaly maps indicate the possibility of high altered zone(s) along NW-SE direction at the central part of the study area. High current density plots of VLF method and the low resistive zones in gradient resistivity study depict the coincidence with low gravity, moderately high magnetic and low resistivity anomalies at the same locations. Moderate high radioactive zones have also been observed over these locations. This also suggests the existence of radioactive mineralization over this region. Along profile P2, drilled borehole data revealed the presence of uranium mineralization at a depth of ∼100 m. The vertical projection of this mineralization band also identified as low gravity, low resistivity and high magnetic anomaly zone. Thus, the application of integrated geophysical techniques supported by geological information successfully recognized the nature of geophysical signatures associated with the uranium mineralization of this region. This enhances the scope of further integrated geophysical investigations in the unexplored regions of SPSZ. (author)

Distribution of female genital tract anomalies in two classifications.

Science.gov (United States)

Heinonen, Pentti K

2016-11-01

This study assessed the distribution of Müllerian duct anomalies in two verified classifications of female genital tract malformations, and the presence of associated renal defects. 621 women with confirmed female genital tract anomalies were retrospectively grouped under the European (ESHRE/ESGE) and the American (AFS) classification. The diagnosis of uterine malformation was based on findings in hysterosalpingography, two-dimensional ultrasonography, endoscopies, laparotomy, cesarean section and magnetic resonance imaging in 97.3% of cases. Renal status was determined in 378 patients, including 5 with normal uterus and vagina. The European classification covered all 621 women studied. Uterine anomalies without cervical or vaginal anomaly were found in 302 (48.6%) patients. Uterine anomaly was associated with vaginal anomaly in 45.2%, and vaginal anomaly alone was found in 26 (4.2%) cases. Septate uterus was the most common (49.1%) of all genital tract anomalies, followed by bicorporeal uteri (18.2%). The American classification covered 590 (95%) out of the 621 women with genital tract anomalies. The American system did not take into account vaginal anomalies in 170 (34.7%) and cervical anomalies in 174 (35.5%) out of 490 cases with uterine malformations. Renal abnormalities were found in 71 (18.8%) out of 378 women, unilateral renal agenesis being the most common defect (12.2%), also found in 4 women without Müllerian duct anomaly. The European classification sufficiently covered uterine and vaginal abnormalities. The distribution of the main uterine anomalies was equal in both classifications. The American system missed cervical and vaginal anomalies associated with uterine anomalies. Evaluation of renal system is recommended for all patients with genital tract anomalies. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Magnetic activity at Mars - Mars Surface Magnetic Observatory

DEFF Research Database (Denmark)

Vennerstrøm, Susanne; Menvielle, M.; Merayo, José M.G.

2012-01-01

, and use this to provide an estimate of the expected magnetic disturbances at the Martian surface. Far from crustal anomaly regions the expected magnetic disturbances originating from currents associated with the induced magnetosphere are very weak at the day-side, but most likely larger on the night...... around medium intensity radial anomalies in the equatorial region appear to derive from local current loops or vortices around cusp-like radial fields, acting to partly cancel the crustal field. The radial perturbation is further found to depend on upstream solar wind dynamic pressure. We define...

Observation of cosmic-ray particles with artificial satellites in Japan

International Nuclear Information System (INIS)

Nagata, Katsuaki

1981-01-01

The present status are described on the cosmic-ray observation with artificial satellites in Japan. In 1978, an electrostatic analyzer was loaded on the satellite EXOS-A to measure low energy electrons. The spectra taken on April 27, 1978, showed that the electron flux decreased exponentially with the increasing electron energy. A space environment monitor (SEM) was loaded on a geostationary meteorological satellite (GMS) in 1977. The SEM consists of 5 Si detectors, with which particle identification can be made, and protons with the energy of 500 MeV and alpha particles with the energy of 370 MeV were observed. The time variation of particle flux was large in the low energy part and small in the high energy part. In 1984, the satellite EXOS-C will be launched. The purposes of this project are general observation of the middle atmosphere composition and the study of the anomaly of the ionosphere above the Brazilian Anomaly. Measurement of low energy particles will be done with an electrostatic analyzer, and that of high energy particles with a telescope with Si detectors. Other projects designed in Japan are OPEN-J and EXOS-D. (Kato, T.)

Interstellar depletion anomalies and ionization potentials

International Nuclear Information System (INIS)

Tabak, R.G.

1979-01-01

Satellite observations indicate that (1) most elements are depleted from the gas phase when compared to cosmic abundances, (2) some elements are several orders of magnitude more depleted than others, and (3) these depletions vary from cloud to cloud. Since the most likely possibility is that the 'missing' atoms are locked into grains, depletions occur either by accretion onto core particles in interstellar clouds or earlier, during the period of primary grain formation. If the latter mechanism is dominant, then the most important depletion parameter is the condensation temperature of the elements and their various compounds. However, this alone is not sufficient to explain all the observed anomalies. It is shown that electrostatic effects - under a wide variety of conditions- can enormously enhance the capture cross-section of the grain. It is suggested that this mechanism can also account for such anomalies as the apparent 'overabundance' of the alkali metals in the gas phase. (orig.)

Analysis of Anomaly in Land Surface Temperature Using MODIS Products

Science.gov (United States)

Yorozu, K.; Kodama, T.; Kim, S.; Tachikawa, Y.; Shiiba, M.

2011-12-01

Atmosphere-land surface interaction plays a dominant role on the hydrologic cycle. Atmospheric phenomena cause variation of land surface state and land surface state can affect on atmosphereic conditions. Widely-known article related in atmospheric-land interaction was published by Koster et al. in 2004. The context of this article is that seasonal anomaly in soil moisture or soil surface temperature can affect summer precipitation generation and other atmospheric processes especially in middle North America, Sahel and south Asia. From not only above example but other previous research works, it is assumed that anomaly of surface state has a key factor. To investigate atmospheric-land surface interaction, it is necessary to analyze anomaly field in land surface state. In this study, soil surface temperature should be focused because it can be globally and continuously observed by satellite launched sensor. To land surface temperature product, MOD11C1 and MYD11C1 products which are kinds of MODIS products are applied. Both of them have 0.05 degree spatial resolution and daily temporal resolution. The difference of them is launched satellite, MOD11C1 is Terra and MYD11C1 is Aqua. MOD11C1 covers the latter of 2000 to present and MYD11C1 covers the early 2002 to present. There are unrealistic values on provided products even if daily product was already calibrated or corrected. For pre-analyzing, daily data is aggregated into 8-days data to remove irregular values for stable analysis. It was found that there are spatial and temporal distribution of 10-years average and standard deviation for each 8-days term. In order to point out extreme anomaly in land surface temperature, standard score for each 8-days term is applied. From the analysis of standard score, it is found there are large anomaly in land surface temperature around north China plain in early April 2005 and around Bangladesh in early May 2009.

Feasibility of a Constellation of Miniature Satellites for Performing Measurements of the Magnetic Field of the Earth

DEFF Research Database (Denmark)

Thomsen, Michael; Merayo, José M.G.; Brauer, Peter

2008-01-01

This paper studies the requirements for a small constellation of satellites to perform measurements of the magnetic field of the Earth and a payload and boom design for such a mission is discussed. After studying communication, power and mass requirements it is found that it is feasible to develop...

Study of hyperfine anomaly in 9,11Be isotopes

International Nuclear Information System (INIS)

Parfenova, Y.; Leclercq-Willain

2005-01-01

The study of the hyperfine anomaly of neutron rich nuclei, in particular, neutron halo nuclei, can give a very specific and unique way to measure their neutron distribution and confirm a halo structure. The hyperfine structure anomaly in Be + ions is calculated with a realistic electronic wave function, obtained as a solution of the Dirac equation. In the calculations, the Coulomb potential modified by the charge distribution of the clustered nucleus and three electrons in the configuration 1s 2 2s is used. The nuclear wave function for the 11 Be nucleus is obtained in the core + nucleon model, and that for the 9 Be nucleus is calculated in the three-cluster (α+α + n) model. The aim of this study is to test whether the hyperfine structure anomaly reflects an extended spatial structure of '1 1 Be. The results of the calculations are listed. ε BW is the hyperfine anomaly in the Bohr-Weisskopf effect and δ is the charge structure correction, μ is the calculated magnetic moment, and μ exp is the experimental value of the magnetic moment, Q and Q exp are the calculated and measured values of the quadrupole moment. The results for 9 Be are obtained with two different three-body wave functions (WF1 and WF2) showing the sensitivity of the calculations to the input parameters. The value of ε BW is sensitive to the weights of the states in the nuclear ground state wave function. The total hyperfine anomaly value εε BW +δ in 11 Be differs from that in 9 Be by 25%. This gives a measure of the accuracy of the hyperfine anomaly measurements needed to study the neutron distribution in the Be isotopes. (authors)

Adler-Bell-Jackiw anomaly and fermion-number breaking in the presence of a magnetic monopole

International Nuclear Information System (INIS)

Rubakov, V.A.

1982-01-01

In (V - A) theories, fermion number is broken in the presence of the 't Hooft-Polyakov magnetic monopole through the Adler-Bell-Jackiw anomaly. An exactly solvable zeroth-order approximation for evaluating Green functions of zero-angular-momentum fermions in the presence of a monopole is developed in the case of an SU(2) model with massless left-handed fermions. Within this approximation the density of the fermion-number breaking condensate is calculated. This density is found to be O(1), i.e. to be independent of the coupling constant and of the vacuum expectation value of the Higgs field. The corrections to the approximation are estimated. It is argued that the above effect can give rise to the strong baryon-number breaking in monopole-fermion interactions in SU(5) grand unified theory. (orig.)

Congenital anomalies of the spine and spinal cord

International Nuclear Information System (INIS)

Altman, N.R.; McLone, D.G.; Naidich, T.P.; Zimmerman, R.A.; Raybaud, C.A.

1991-01-01

In the spine, the most common congenital lesions presenting to medical attention are the diverse forms of spinal dysraphism and the diverse forms of caudal spinal anomalies. Most commonly, these conditions are discovered at birth or in early childhood. Less commonly, they first present to medical attention in adulthood. Widespread use of magnetic resonance imaging (MRI) is expected to reduce the incidence of delayed diagnosis of the dysraphisms and the other spinal malformations. This paper addresses the most common forms of dysraphism and the most common caudal spinal anomalies. It provides an overview of embryology for orientation and then groups the anomalies in terms of the specific derangements of embryology that are believed to give rise to the anomalies. It is hoped that this approach will provide greater understanding of these lesions and better long-term retention of information about them. A conceptual framework of embryology and pathogenesis may eliminate the need for rote memorization; certainly it is a more satisfying approach intellectually

Magnetic Fields of the Earth and Mars a Comparison and Discussion

Science.gov (United States)

Taylor, Patrick T.

2004-01-01

In several aspects the magnetic fields of the Earth and Mars are similar but also different. In the past both bodies had planetary magnetic fields but while they Earth's field remains today the Martian ceased to operate, at some unknown time in the past, leaving this planet without a main or core field. This fact resulted in the interaction between the solar and interplanetary magnetic fields with the surfaces of these planets being very different. In addition, Mars has large crustal magnetic anomalies, nearly ten times larger than those on the Earth. Since crustal magnetic anomalies are the product of the thickness of the layer of magnetization, both the magnetizing material and the thickness of the layer of this material must be very different on Mars than Earth. Furthermore, the martian anomalies can only be produced by remanent or fossil magnetization, in contrast with the Earth where both induced and remanent magnetization are producing these anomalies. Crustal magnetic anomalies on the Earth are mainly produced by single-domain, irontitanium oxides, in the form of magnetite being the most common on Mars the main magnetic mineral(s) are unknown. The thickness of the martian magnetized layer in comparison with the Earth remains a major area for research. Determining the paleopole position for the Earth has been done by some of the earliest paleomagnetic researchers. Since we do not have oriented martian rock samples determining the paleopoles for Mars has been done by fitting a magnetization vector to individual magnetic anomalies. Several groups have worked on this problem with somewhat differing results.

Magnetization strucrure of thermal vent on island arc from vector magnetic anomlies using AUV

Science.gov (United States)

Isezaki, N.; Matsuo, J.; Sayanagi, K.

2012-04-01

The geomagnetic anomaly measured by a scalar magnetometer,such as a proton precession magnetometer cannot be defined its direction, then it does not satisfy the Laplace's equation. Therefore physical formula describing the relation between magnetic field and magnetization cannot be established.Because the difference between results obtained from scalar data and from vector data is very significant, we must use vector magnetic field data for magnetization analyses to get the more reliable and exact solutions. The development program of fundamental tools for exploration of deep seabed resources started with the financial support of the Ministry of Education, Culture, Sports, Science & Technology (MEXT) in 2008 and will end in 2012. In this project, we are developing magnetic exploration tools for seabed resources using AUV (Autonomous Underwater Vehicle) and other deep-towed vehicles to measure not the scalar magnetic field but the vector magnetic field in order to estimate magnetization structure below the sea-floor exactly and precisely. We conducted AUV magnetic survey in 2010 at the thermal area called Hakurei deposit in the Bayonnaise submarine caldera at the southern end of Izu island arc, about 400km south of Tokyo. We analyzed the observed vector magnetic fields to get the vector magnetic anomaly Fields using the method of Isezaki(1984). We inverted these vector magnetic anomaly fields to magnetization structure. CONCLUSIONS 1.The scalar magnetic field TIA (Total Intensity Anomaly) has no physical formula describing the relation between M (Magnetization) and TIA because TIA does not satisfy the Laplace's equation. Then it is impossible to estimate M from TIA. 2.Anlyses of M using TIA have been done so far under assumption TIA=PTA (Projected Total Anomay on MF (Main Geomagnetic Field)), however, which caused the analysis error due to ɛT= TIA - PTA . 3.We succeeded to measure the vector magnetic anomaly fields using AUV despite the severe magnetic noises

Geothermal Anomaly Mapping Using Landsat ETM+ Data in Ilan Plain, Northeastern Taiwan

Science.gov (United States)

Chan, Hai-Po; Chang, Chung-Pai; Dao, Phuong D.

2018-01-01

Geothermal energy is an increasingly important component of green energy in the globe. A prerequisite for geothermal energy development is to acquire the local and regional geothermal prospects. Existing geophysical methods of estimating the geothermal potential are usually limited to the scope of prospecting because of the operation cost and site reachability in the field. Thus, explorations in a large-scale area such as the surface temperature and the thermal anomaly primarily rely on satellite thermal infrared imagery. This study aims to apply and integrate thermal infrared (TIR) remote sensing technology with existing geophysical methods for the geothermal exploration in Taiwan. Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) imagery is used to retrieve the land surface temperature (LST) in Ilan plain. Accuracy assessment of satellite-derived LST is conducted by comparing with the air temperature data from 11 permanent meteorological stations. The correlation coefficient of linear regression between air temperature and LST retrieval is 0.76. The MODIS LST product is used for the cross validation of Landsat derived LSTs. Furthermore, Landsat ETM+ multi-temporal brightness temperature imagery for the verification of the LST anomaly results were performed. LST Results indicate that thermal anomaly areas appear correlating with the development of faulted structure. Selected geothermal anomaly areas are validated in detail by field investigation of hot springs and geothermal drillings. It implies that occurrences of hot springs and geothermal drillings are in good spatial agreement with anomaly areas. In addition, the significant low-resistivity zones observed in the resistivity sections are echoed with the LST profiles when compared with in the Chingshui geothermal field. Despite limited to detecting the surficial and the shallow buried geothermal resources, this work suggests that TIR remote sensing is a valuable tool by providing an effective way of mapping

Satellite gravity anomalies and crustal features of the Central Indian Ocean Basin

Digital Repository Service at National Institute of Oceanography (India)

Rao, D.G.; Krishna, K.S.; Neprochnov, Y.P.; Grinko, B.N.

-air anomalies due to volcanic constructs that trend in arcuate shape from north to south parallel to 82.5 degrees E are noted as southern continuity of the 85 degrees E Ridge, which terminates at the Afanasy Nikitin seamount. Change in rheology of the crustal...

Modelling and inversion of local magnetic anomalies

International Nuclear Information System (INIS)

Quesnel, Y; Langlais, B; Sotin, C; Galdéano, A

2008-01-01

We present a method—named as MILMA for modelling and inversion of local magnetic anomalies—that combines forward and inverse modelling of aeromagnetic data to characterize both magnetization properties and location of unconstrained local sources. Parameters of simple-shape magnetized bodies (cylinder, prism or sphere) are first adjusted by trial and error to predict the signal. Their parameters provide a priori information for inversion of the measurements. Here, a generalized nonlinear approach with a least-squares criterion is adopted to seek the best parameters of the sphere (dipole). This inversion step allows the model to be more objectively adjusted to fit the magnetic signal. The validity of the MILMA method is demonstrated through synthetic and real cases using aeromagnetic measurements. Tests with synthetic data reveal accurate results in terms of depth source, whatever be the number of sources. The MILMA method is then used with real measurements to constrain the properties of the magnetized units of the Champtoceaux complex (France). The resulting parameters correlate with the crustal structure and properties revealed by other geological and geophysical surveys in the same area. The MILMA method can therefore be used to investigate the properties of poorly constrained lithospheric magnetized sources

S.E. Mitchell Vascular Anomalies Flow Chart (SEMVAFC): A visual pathway combining clinical and imaging findings for classification of soft-tissue vascular anomalies

International Nuclear Information System (INIS)

Tekes, A.; Koshy, J.; Kalayci, T.O.; Puttgen, K.; Cohen, B.; Redett, R.; Mitchell, S.E.

2014-01-01

Classification of vascular anomalies (VAs) is challenging due to overlapping clinical symptoms, confusing terminology in the literature and unfamiliarity with this complex entity. It is important to recognize that VAs include two distinct entities, vascular tumours (VTs) and vascular malformations (VaMs). In this article, we describe SE Mitchell Vascular Anomalies Flow Chart (SEMVAFC), which arises from a multidisciplinary approach that incorporates clinical symptoms, physical examination and magnetic resonance imaging (MRI) findings to establish International Society for the Study of Vascular Anomalies (ISSVA)-based classification of the VAs. SEMVAFC provides a clear visual pathway for physicians to accurately diagnose Vas, which is important as treatment, management, and prognosis differ between VTs and VaMs

Arcs électriques sur panneaux solaires de satellite

OpenAIRE

Amorim, Emmanuel

2002-01-01

Tout au long de leur durée de vie, les satellites sont en interaction constante avec l'environnement spatial. En orbite géostationnaire, les surfaces des satellites sont par exemple chargées par les particules de la magnétosphère, en particulier par les électrons. Récemment, des pertes de puissance ont été constatées sur certains satellites situés en orbite géostationnaire. Ces anomalies ont été corrélées avec des périodes d'environnement chargeant et s'expliqueraient par une décharge électro...

Gravity anomalies without geomagnetic disturbances interfere with pigeon homing--a GPS tracking study.

Science.gov (United States)

Blaser, Nicole; Guskov, Sergei I; Entin, Vladimir A; Wolfer, David P; Kanevskyi, Valeryi A; Lipp, Hans-Peter

2014-11-15

The gravity vector theory postulates that birds determine their position to set a home course by comparing the memorized gravity vector at the home loft with the local gravity vector at the release site, and that they should adjust their flight course to the gravity anomalies encountered. As gravity anomalies are often intermingled with geomagnetic anomalies, we released experienced pigeons from the center of a strong circular gravity anomaly (25 km diameter) not associated with magnetic anomalies and from a geophysical control site, equidistant from the home loft (91 km). After crossing the border zone of the anomaly--expected to be most critical for pigeon navigation--they dispersed significantly more than control birds, except for those having met a gravity anomaly en route. These data increase the credibility of the gravity vector hypothesis. © 2014. Published by The Company of Biologists Ltd.

Evaluation of DNA bending models in their capacity to predict electrophoretic migration anomalies of satellite DNA sequences.

Science.gov (United States)

Matyášek, Roman; Fulneček, Jaroslav; Kovařík, Aleš

2013-09-01

DNA containing a sequence that generates a local curvature exhibits a pronounced retardation in electrophoretic mobility. Various theoretical models have been proposed to explain relationship between DNA structural features and migration anomaly. Here, we studied the capacity of 15 static wedge-bending models to predict electrophoretic behavior of 69 satellite monomers derived from four divergent families. All monomers exhibited retarded mobility in PAGE corresponding to retardation factors ranging 1.02-1.54. The curvature varied both within and across the groups and correlated with the number, position, and lengths of A-tracts. Two dinucleotide models provided strong correlation between gel mobility and curvature prediction; two trinucleotide models were satisfactory while remaining dinucleotide models provided intermediate results with reliable prediction for subsets of sequences only. In some cases, similarly shaped molecules exhibited relatively large differences in mobility and vice versa. Generally less accurate predictions were obtained in groups containing less homogeneous sequences possessing distinct structural features. In conclusion, relatively universal theoretical models were identified suitable for the analysis of natural sequences known to harbor relatively moderate curvature. These models could be potentially applied to genome wide studies. However, in silico predictions should be viewed in context of experimental measurement of intrinsic DNA curvature. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deep structure of the Tristan-Gough plume revealed by geoid anomalies

Science.gov (United States)

Maia, M.; Flamme, J.; Cadio, C.; Lalancette, M. F.; Metivier, L.; Pajot-Métivier, G.; Diament, M.

2017-12-01

The origin of the hotspot Tristan da Cunha located at the southwestern end of Walvis Ridge in the Atlantic Ocean is still a controversial topic. We especially question on the nature of the involved geodynamical processes and on their origin depth. The latest results based on local seismic and magnetic data (Schlömer et al., 2016; Baba et al., 2016; Geissler et al., 2016) suggest the existence of a plume coming from the mid-mantle in the southwest of the archipelago. Here we give a regional view of mantle dynamics patterns in the area by using the high-quality satellite geoid data. To extract the mantle signature, we estimate the crustal and lithospheric signals of the ocean basin and South American and African continents, which contribute to mid- and long-wavelengths in the total geoid. We pay particular attention to the modeling of continental margins and their effects on the residual geoid signal. In addition, we explore a large density values set derived from petrological and geochemical studies in the calculation of the lithospheric geoid model. After subtracting the lithospheric signature to the EGM2008 geoid, we apply a multi-scale analysis, which unfolds the different components of the geoid residual signal. The analysis underlines a set of positive anomalies at 200-400 km in the study area, notably in north and west of Tristan de Cunha, and a positive anomaly at 700-1100 km scale in the southwest of the archipelago. These patterns do not change by using different lithospheric geoid models, which allow us to evaluate the reliability of the residual geoid anomalies. These results indicate the existence of small-scale density anomalies in the upper mantle and a larger scale density anomaly in the mid-mantle. Our study suggests that a large dome toped by plume clusters could be a good candidate to explain the volcanism of Tristan da Cunha.Schlömer et al., 2016 Hunting for the Tristan mantle plume..., EPSL, http://dx.doi.org/10.1016/j.epsl.2016.12.028Baba et

The spatial structure of magnetospheric plasma disturbance estimated by using magnetic data obtained by SWARM satellites.

Science.gov (United States)

Yokoyama, Y.; Iyemori, T.; Aoyama, T.

2017-12-01

Field-aligned currents with various spatial scales flow into and out from high-latitude ionosphere. The magnetic fluctuations observed by LEO satellites along their orbits having period longer than a few seconds can be regarded as the manifestations of spatial structure of field aligned currents.This has been confirmed by using the initial orbital characteristics of 3 SWARM-satellites. From spectral analysis, we evaluated the spectral indices of these magnetic fluctuations and investigated their dependence on regions, such as magnetic latitude and MLT and so on. We found that the spectral indices take quite different values between the regions lower than the equatorward boundary of the auroral oval (around 63 degrees' in magnetic latitude) and the regions higher than that. On the other hands, we could not find the clear MLT dependence. In general, the FACs are believed to be generated in the magnetiospheric plasma sheet and boundary layer, and they flow along the field lines conserving their currents.The theory of FAC generation [e.g., Hasegawa and Sato ,1978] indicates that the FACs are strongly connected with magnetospheric plasma disturbances. Although the spectral indices above are these of spatial structures of the FACs over the ionosphere, by using the theoretical equation of FAC generation, we evaluate the spectral indices of magnetospheric plasma disturbance in FAC's generation regions. Furthermore, by projecting the area of fluctuations on the equatorial plane of magnetosphere (i.e. plasma sheet), we can estimate the spatial structure of magnetospheric plasma disturbance. In this presentation, we focus on the characteristics of disturbance in midnight region and discuss the relations to the substorm.

MR imaging of anorectal malformations and associated anomalies

International Nuclear Information System (INIS)

Nievelstein, R.A.J.; Valk, J.; Vos, A.

1998-01-01

Congenital anorectal malformations are found in many forms, and are frequently associated with other anomalies, especially of the spinal cord, spine, and urogenital system. Decisions concerning initial management of children with anorectal malformations can be made only after accurate determination of (a) the level and type of malformation, (b) the type of fistula, (c) the developmental state of the sphincter muscle complex, and (d) the presence of associated anomalies. Magnetic resonance imaging has proven to be the only modality to answer all these crucial questions, and has contributed to a better insight in the morphology and pathogenesis of such complex congenital malformations. (orig.)

Prospects of application of survey satellite image for meteorology

Science.gov (United States)

Kapochkina, A. B.; Kapochkin, B. B.; Kucherenko, N. V.

The maximal interest is represented with the information from geostationary satellites. These satellites repeat shootings the chosen territories, allowing to study dynamics of images. Most interesting shootings in IR a range. Studying of survey image is applied to studying linear elements of clouds (LEC). It is established, that "LEC " arise only above breaks of an earth's crust. In research results of the complex analysis of the satellite data, hydrometeorological supervision, seismicity, supervision over deformations of a surface of the Earth are used. It is established that before formation "LEC " in a ground layer arise anomalies of temperature and humidity. The situation above Europe 16 May, 2001 is considered. "LEC " in Europe block carry of air weights from the west to the east. Synoptic conditions above the Great Britain July, 7-10, 2000 is considered. Moving "LEC" trace distribution of deformation waves to an earth's crust. Satellite shootings Europe before earthquake in Greece 14.08.2003 are considered. These days ground supervision were conducted and the data of the geostationary satellite were analyzed. During moving "LEC " occur failures (destruction houses & of gas mains), earthquake. The situation above Iberian peninsula 12-16.11.2001 is considered. "LEC" arose before flooding in Europe. The situation before flooding in Germany June, 6-8, 2002 and flooding on the river Kuban June, 16-23, 2002 is considered. In case of occurrence of tectonic compression of an earth's crust there are "LEC ", tracer intensive movements of air upwards and downwards above negative and positive anomalies of the form of a terrestrial surface, accordingly. Such meteorological situations are dangerous to flights of aircraft, the fast gravitational anomalies influencing into orbits of movement of satellites trace. The situation above equatorial Atlantic 26.03.2003 years is considered. At tectonic compression of continental scale overcast covers the whole continents for more

Volcanomagnetic anomalies: a review and the computation of the piezomagnetic field expected at Vulcano (Aeolian Islands, Italy

Directory of Open Access Journals (Sweden)

F. Ferricci

1994-06-01

Full Text Available he volcanic area of Vulcano experienced major unrest, which brought the fumarolic field temperatures from slightly less than 300 °C to ca. 700 °C between 1988-1993. The structure underlying the crater, investigated by drillings and by different geophysical techniques, is relatively well-known. This led us to attempt modelling the magnetic anomaly which could be generated by sudden pressure variations in the magma chamber at shallow depth. The rocks embedding the intrusive rock penetrated by drill-holes to a depth of ca. 2000 m are characterized by high susceptibility, which points to the possibility of obtaining significant magnetic anomalies with acceptably weak pressure pulses. The model for straightforward computing of the anomalous field was drawn accounting for (1 the inferred geometry of the Curie isotherrn, (2 presence of a spherical magma reservoir, 2 km wide and centred at a depth of 3.5 km, overlain by (3 a 0.5 km wide and 1.5 km high cylinder simulating the intrusion first revealed by drillings. The model elements (2 and (3 behave as a single source zone and are assumed to lie beyond the Curie point, the contribution to the piezomagnetic effect being provided by the surrounding medium. Under such conditions, a 10 MPa pressure pulse applied within the sourcezone provides a 4 nT piezomagnetic anomaly, compatible with the amplitude of the anomalies observed at those volcanoes of the world where magnetic surveillance is routinely carried out. The analytical method used for computation of the magnetic field generated by mechanical stress is extensively discussed, and the contribution of piezomagnetism to rapid variations of the magnetic field is compared to other types of magnetic anomalies likely to occur at active volcanoes.

Probing the earth's gravity field using Satellite-to-Satellite Tracking (SST)

Science.gov (United States)

Vonbun, F. O.

1976-01-01

Satellite-to-Satellite (SST) tests, namely: (a) the ATS-6/GEOS-3 and (b) the ATS-6/Apollo-Soyuz experiment and some of the results obtained are described. The main purpose of these two experiments was first to track via ATS-6 the GEOS-3 as well as the Apollo-Soyuz and to use these tracking data to determine (a) both orbits, that is, ATS-6, GEOS-3 and/or the Apollo-Soyuz orbits at the same time; (b) each of these orbits alone; and (c) test the ATS-6/GEOS-3 and/or Apollo-Soyuz SST link to study local gravity anomalies; and, second, to test communications, command, and data transmission from the ground via ATS-6 to these spacecraft and back again to the ground. The Apollo-Soyuz Geodynamics Experiment is discussed in some detail.

Study of X-rays at the atmosphere of the South Atlantic Magnetic Anomaly

International Nuclear Information System (INIS)

Pinto Junior, O.

1985-06-01

A study of X-rays at the atmosphere of the South Atlantic Magnetic Anomaly is presented in this work, in which an analysis of all existing balloon measurements carried out at this region has been done. It is concluded that the X-ray flux due to electron precipitation depends strongly on geomagnetic activity, reaching at Sao Jose dos Campos a maximum doward flux of 10 -2 photons/cm 2 .sec.KeV for 4g/cm 2 and for the energy range of 30-150KeV. The related flux of precipitating electrons was computed by Monte Carlo method with values of about 500 electrons/cm 2 .sec and energy espectra of the type e -T/200 . This electron flux is shown to represent the main ionization flux for the atmosphere at about 60 Km height. Furthermore, the atmospheric and diffuse components were determined at balloon altitudes (approximately 5g/cm 2 ) of Sao Jose dos campos (λ m = 11 0 S) to be of the same order. (author) [pt

Thermal Radiation Anomalies Associated with Major Earthquakes

Science.gov (United States)

Ouzounov, Dimitar; Pulinets, Sergey; Kafatos, Menas C.; Taylor, Patrick

2017-01-01

Recent developments of remote sensing methods for Earth satellite data analysis contribute to our understanding of earthquake related thermal anomalies. It was realized that the thermal heat fluxes over areas of earthquake preparation is a result of air ionization by radon (and other gases) and consequent water vapor condensation on newly formed ions. Latent heat (LH) is released as a result of this process and leads to the formation of local thermal radiation anomalies (TRA) known as OLR (outgoing Longwave radiation, Ouzounov et al, 2007). We compare the LH energy, obtained by integrating surface latent heat flux (SLHF) over the area and time with released energies associated with these events. Extended studies of the TRA using the data from the most recent major earthquakes allowed establishing the main morphological features. It was also established that the TRA are the part of more complex chain of the short-term pre-earthquake generation, which is explained within the framework of a lithosphere-atmosphere coupling processes.

Magnetic mineral exploration using ground magnetic survey data of ...

African Journals Online (AJOL)

The field data were quantitatively interpreted and the results gave values for the total component measurements of the ground magnetic anomaly that varied ... from the Earth surface fall in the interval of 1.28m to 13.57m, which indicates the magnetic source body suspected to be magnetic mineral, are near surface features.

Relation of decorrelated transionospheric GPS signal fluctuations from two stations in the northern anomaly crest region with equatorial ionospheric dynamics

Science.gov (United States)

Paul, K. S.; Paul, A.

2017-05-01

The ionosphere around the northern crest of the equatorial ionization anomaly (EIA) and beyond exhibits rapid temporal as well as spatial development of ionization density irregularities during postsunset hours. A GPS campaign was conducted during September 2012 and April 2013 from the Institute of Radio Physics and Electronics, Calcutta (22.58°N, 88.38°E geographic; magnetic dip: 32°N), and North Bengal University (NBU), Siliguri (26.72°N, 88.39°E geographic, magnetic dip: 39.49°N) in India in order to assess and quantify differences, if any, in the nature of carrier to noise ratio (C/N0) fluctuations observed on the same satellite link around the same time interval from these stations. Significant decorrelation of the received signals was found when tracking the same satellite vehicle (SV) link from these stations during periods of scintillations. Low values of correlation coefficient of C/N0 at L1 frequency recorded on the same SV link at these two stations were found to correspond with high irregularity characteristic velocities. North-south spatial displacement rates of the impact of ionospheric irregularities were calculated based on coordinated GPS observations which followed an increasing trend with irregularity characteristic velocities measured at VHF. Values of characteristic velocities in excess of 36 m/s were also found to result in large receiver position deviations 3.5-4.0 m during periods of scintillations. Information related to time lag associated with occurrence of scintillations on the same SV link observed from two stations could be useful for improving performance of transionospheric satellite-based position determination techniques.

Dynamics of magnetic nano-particle assembly

International Nuclear Information System (INIS)

Kondratyev, V N

2010-01-01

Ferromagnetically coupled nano-particle assembly is analyzed accounting for inter- and intra- particle electronic structures within the randomly jumping interacting moments model including quantum fluctuations due to the discrete levels and disorder. At the magnetic jump anomalies caused by quantization the magnetic state equation and phase diagram are found to indicate an existence of spinodal regions and critical points. Arrays of magnetized nano-particles with multiple magnetic response anomalies are predicted to display some specific features. In a case of weak coupling such arrays exhibit the well-separated instability regions surrounding the anomaly positions. With increasing coupling we observe further structure modification, plausibly, of bifurcation type. At strong coupling the dynamical instability region become wide while the stable regime arises as a narrow islands at small disorders. It is shown that exploring correlations of magnetic noise amplitudes represents convenient analytical tool for quantitative definition, description and study of supermagnetism, as well as self-organized criticality.

Response of Gravity, Magnetic, and Geoelectrical Resistivity Methods on Ngeni Southern Blitar Mineralization Zone

Science.gov (United States)

Sunaryo

2018-03-01

The research with entitle response of gravity, magnetic, and geoelectrical resistivity methods on Ngeni Southern Blitar mineralization zone has been done. This study aims to find the response of several geophysical methods of gravity, magnetic, and geoelectrical resistivity in an integrated manner. Gravity data acquisition was acquired 224 data which covers the whole region of Blitar district by using Gravity Meter La Coste & Romberg Model “G”, and magnetic data acquisition were acquired 195 data which covers the southern Blitar district only by using Proton Precession Magnetometer G-856. Meanwhile geoelectrical resistivity data only done in Ngeni village which is the location of phyropilite mining with the composition content of Fe, Si, Ca, S, Cu, and Mn by using ABEM Terrameter SAS 300C. Gravity data processing was performed to obtain the Bouguer anomaly value, which included unit conversion, tidal correction, drift correction, correction of tie point, base station correction, free air correction, and Bouguer correction. Magnetic data processing has been done by some corrections i.e daily, drift, and IGRF(International Geomagnetic Refference Field) to obtain the total magnetic anomaly. From gravity data processing has been obtained the simple Bouguer anomaly value in range from -10mGal until 115mGal. From this data processing has been obtained the total magnetic anomaly value in range from -650nT until 800nT. Meanwhile from geoelectrical resistivity 3.03Ωm until 11249.91 Ωm. There is a correlation between gravity anomaly, magnetic anomaly, and geoelectrical resistivity anomaly that are associated with deep anomaly, middle anomaly, and shallow anomaly.

Lithospheric stretching and the long wavelength free-air gravity anomaly of the Eastern Continental margin of India and the 85 degree E Ridge, Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Rajesh, S.; Majumdar, T.J.; Krishna, K.S.

Or as envisaged, was it originated from the Crozet hotspot We address these issues by using satellite altimeter-derived gravity anomaly and its analytical upward continuation anomalies with forward modeling of ship-borne data. Results on analytical continuation...

True Polar Wander and Hotspot Fixity: A Paleomagnetic Investigation of the Skewness of Magnetic Anomaly 12r (32 Ma B.P.) on the Pacific Plate

Science.gov (United States)

Gordon, R. G.; Horner-Johnson, B. C.

2010-12-01

Prior studies have shown that Pacific hotspots and Indo-Atlantic hotspots have moved in approximate unison relative to the spin axis since 65 Ma B.P. [Morgan, 1981; Gordon and Cape, 1981; Gordon, 1982] and since 56 Ma B.P. [Petronotis et al., 1994], which is most simply interpreted as true polar wander. In contrast, Pacific hotspots and Indo-Atlantic hotspots give conflicting results for 72 Ma B.P. and for 81 Ma B.P., which may indicate motion between Pacific hotspots and Indo-Atlantic hotspots [Tarduno and Cottrell, 1997; Petronotis et al., 1999; Tarduno et al., 2003]. Thus it is important to estimate Pacific plate apparent polar wander (APW) for more time intervals. From such estimates the APW of Pacific hotspots can be inferred and compared with that of Indo-Atlantic hotspots [e.g., Besse and Courtillot 2002]. Here we present a study of the skewness of anomaly 12r between the Galapagos and Clipperton and between the Clipperton and Clarion fracture zones. We chose this region for several reasons: First, numerical experiments, like those conducted by Acton and Gordon [1991], indicate that magnetic profiles between the Galapagos and Clarion fracture zones should contain the most information about the Pacific plate paleomagnetic pole for chron C12r (32 Ma B.P.). Second, in these two spreading rate corridors, spreading half rates range from 72 to 86 mm/a and therefore have negligible anomalous skewness, given that they exceed ≈50 mm/a [Roest et al., 1992; Dyment et al. 1994]. Third, vector aeromagnetic profiles are available for analysis. One of the challenges to interpreting magnetic anomalies in low latitudes where the anomalies strike nearly north-south is the very low amplitude of the signal relative to the noise, the latter of which can be especially intense near the present magnetic equator due to the amplification of diurnal variation by the equatorial electrojet. Previously we showed that vector aeromagnetic profiles record low-latitude Pacific plate

High-frequency parameters of magnetic films showing magnetization dispersion

International Nuclear Information System (INIS)

Sidorenkov, V.V.; Zimin, A.B.; Kornev, Yu.V.

1988-01-01

Magnetization dispersion leads to skewed resonance curves shifted towards higher magnetizing fields, together with considerable reduction in the resonant absorption, while the FMR line width is considerably increased. These effects increase considerably with frequency, in contrast to films showing magnetic-anisotropy dispersion, where they decrease. It is concluded that there may be anomalies in the frequency dependence of the resonance parameters for polycrystalline magnetic films

Ebstein’s Anomaly, Left Ventricular Noncompaction, and Sudden Cardiac Death

Directory of Open Access Journals (Sweden)

Michael McGee

2015-01-01

Full Text Available Ebstein’s anomaly is a congenital disorder characterized by apical displacement of the septal leaflet of the tricuspid valve. Ebstein’s anomaly may be seen in association with other cardiac conditions, including patent foramen ovale, atrial septal defect, and left ventricular noncompaction (LVNC. LVNC is characterized by increased trabeculation within the left ventricular apex. Echocardiography is often used to diagnose LVNC; however, magnetic resonance (MR imaging offers superior characterization of the myocardium. We report a case of sudden cardiac death in a patient with Ebstein’s anomaly with unrecognized LVNC noted on post mortem examination with screening documenting the presence of LVNC in one of the patient’s twin sons.

A review on remotely sensed land surface temperature anomaly as an earthquake precursor

Science.gov (United States)

Bhardwaj, Anshuman; Singh, Shaktiman; Sam, Lydia; Joshi, P. K.; Bhardwaj, Akanksha; Martín-Torres, F. Javier; Kumar, Rajesh

2017-12-01

The low predictability of earthquakes and the high uncertainty associated with their forecasts make earthquakes one of the worst natural calamities, capable of causing instant loss of life and property. Here, we discuss the studies reporting the observed anomalies in the satellite-derived Land Surface Temperature (LST) before an earthquake. We compile the conclusions of these studies and evaluate the use of remotely sensed LST anomalies as precursors of earthquakes. The arrival times and the amplitudes of the anomalies vary widely, thus making it difficult to consider them as universal markers to issue earthquake warnings. Based on the randomness in the observations of these precursors, we support employing a global-scale monitoring system to detect statistically robust anomalous geophysical signals prior to earthquakes before considering them as definite precursors.

Optomagnetic Detection of MicroRNA Based on Duplex-Specific Nuclease-Assisted Target Recycling and Multilayer Core-Satellite Magnetic Superstructures

DEFF Research Database (Denmark)

Tian, Bo; Ma, Jing; Qiu, Zhen

2017-01-01

-efficiency, and potential for bioresponsive multiplexing. Herein, we demonstrate a sensitive and rapid miRNA detection method based on optomagnetic read-out, duplex-specific nuclease (DSN)-assisted target recycling, and the use of multilayer core-satellite magnetic superstructures. Triggered by the presence of target mi...

The effects of sea surface temperature anomalies on oceanic coral reef systems in the southwestern tropical Atlantic

Science.gov (United States)

Ferreira, B. P.; Costa, M. B. S. F.; Coxey, M. S.; Gaspar, A. L. B.; Veleda, D.; Araujo, M.

2013-06-01

In 2010, high sea surface temperatures that were recorded in several parts of the world and caused coral bleaching and coral mortality were also recorded in the southwest Atlantic Ocean, between latitudes 0°S and 8°S. This paper reports on coral bleaching and diseases in Rocas Atoll and Fernando de Noronha archipelago and examines their relationship with sea surface temperature (SST) anomalies recorded by PIRATA buoys located at 8°S30°W, 0°S35°W, and 0°S23°W. Adjusted satellite data were used to derive SST climatological means at buoy sites and to derive anomalies at reef sites. The whole region was affected by the elevated temperature anomaly that persisted through 2010, reaching 1.67 °C above average at reef sites and 1.83 °C above average at buoys sites. A significant positive relationship was found between the percentage of coral bleaching that was observed on reef formations and the corresponding HotSpot SST anomaly recorded by both satellite and buoys. These results indicate that the warming observed in the ocean waters was followed by a warming at the reefs. The percentage of bleached corals persisting after the subsidence of the thermal stress, and disease prevalence increased through 2010, after two periods of thermal stress. The in situ temperature anomaly observed during the 2009-2010 El Niño event was equivalent to the anomaly observed during the 1997-1998 El Niño event, explaining similar bleaching intensity. Continued monitoring efforts are necessary to further assess the relationship between bleaching severity and PIRATA SST anomalies and improve the use of this new dataset in future regional bleaching predictions.

About the Las Acacias, Trelew and Vassouras Magnetic Observatories Monitoring the South Atlantic Magnetic Anomaly Region Response to an Interplanetary Coronal Mass Ejection

Science.gov (United States)

Gianibelli, J. C.; Quaglino, N. M.

2007-05-01

The South Atlantic Magnetic Anomaly (SAMA) Region presents evolutive characteristics very important as were observed by a variety of satelital sensors. Important Magnetic Observatories with digital record monitor the effects of the Sun-Earth interaction, such as San Juan de Puerto Rico (SJG), Kourou (KOU), Vassouras (VSS), Las Acacias (LAS), Trelew (TRW), Vernadsky (AIA), Hermanus (HER) and Huancayo (HUA). In the present work we present the features registered during the geomagnetic storm in January 21, 2005, produced by a geoeffective Coronal Mass Ejection (CME) whose Interplanetary Coronal Mass Ejection (ICME) was detected by the instrumental onboard the Advanced Composition Explorer (ACE) Sonde. We analize how the Magnetic Total Intensity records at VSS, TRW and LAS Observatories shows the effect of the entering particles to ionospherical dephts producing a field enhancement following the first Interplanetary Shock (IP) arrival of the ICME. This process manifest in the digital record as an increment over the magnetospheric Ring Current field effect and superinpossed effects over the Antarctic Auroral Electrojet. The analysis and comparison of the records demonstrate that the Ring Current effects are important in SJG and KOU but not in VSS, LAS and TRW observatories, concluding that SAMA region shows a enhancement of the ionospherical currents oposed to those generated at magnetospheric heighs. Moreover in TRW, 5 hours after the ICME shock arrival, shows the effect of the Antarctic Auroral Electrojet counteracting to fields generated by the Ring Current.

Cascade of Quantum Transitions and Magnetocaloric Anomalies in an Open Nanowire

Science.gov (United States)

Val'kov, V. V.; Mitskan, V. A.; Shustin, M. S.

2017-12-01

A sequence of magnetocaloric anomalies occurring with the change in a magnetic field H is predicted for an open nanowire with the Rashba spin-orbit coupling and the induced superconducting pairing potential. The nature of such anomalies is due to the cascade of quantum transitions related to the successive changes in the fermion parity of the nanowire ground state with the growth of the magnetic field. It is shown that the critical H c values fall within the parameter range corresponding to the nontrivial values of the Z 2 topological invariant of the corresponding 1D band Hamiltonian characteristic of the D symmetry class. It is demonstrated that such features in the behavior of the open nanowire are retained even in the presence of Coulomb interactions.

LUMINOUS SATELLITES OF EARLY-TYPE GALAXIES. I. SPATIAL DISTRIBUTION

International Nuclear Information System (INIS)

Nierenberg, A. M.; Auger, M. W.; Treu, T.; Marshall, P. J.; Fassnacht, C. D.

2011-01-01

We study the spatial distribution of faint satellites of intermediate redshift (0.1 s = 1.7 +0.9 -0.8 ) that is comparable to the number of Milky Way satellites with similar host-satellite contrast. The average projected radial profile of the satellite distribution is isothermal (γ p = -1.0 +0.3 -0.4 ), which is consistent with the observed central mass density profile of massive early-type galaxies. Furthermore, the satellite distribution is highly anisotropic (isotropy is ruled out at a >99.99% confidence level). Defining φ to be the offset between the major axis of the satellite spatial distribution and the major axis of the host light profile, we find a maximum posterior probability of φ = 0 and |φ| less than 42 0 at the 68% confidence level. The alignment of the satellite distribution with the light of the host is consistent with simulations, assuming that light traces mass for the host galaxy as observed for lens galaxies. The anisotropy of the satellite population enhances its ability to produce the flux ratio anomalies observed in gravitationally lensed quasars.

Measurements of additional X-ray flux in South Atlantic magnetic anomaly region

International Nuclear Information System (INIS)

Martin, I.M.

1968-01-01

The purpose of this study is the calculation of the additional X-ray flux (20 - 150 KeV), produced by electron precipitation in the South Atlantic anomaly region. The kind of detector and the technique employed in the observations of this flux, utilizing stratospheric balloons as a means of transport of the payload across the anomaly region, are described. The results of two balloon launchins in Sao Jose dos Campos in July 1968, with the expected flux, are compared. (author) [pt

Identification of shallow geothermal anomalies in the Timanfaya National Park (Lanzarote, Canary Islands) through combined geophysical prospecting techniques

Science.gov (United States)

Gómez-Ortiz, David; Blanco-Montenegro, Isabel; Martín-Crespo, Tomás; Arnoso, José; Solla, Mercedes; Montesinos, Fuensanta G.; Vélez, Emilio; Calvo-Rathert, Manuel; Sánchez, Nieves; Lorenzo, Henrique; Soler, Vicente

2017-04-01

The Timanfaya National Park is a volcanic area in the southwest of Lanzarote Island (Canary Archipelago, Spain) resulting from the 1730-1736 eruption period. Several active geothermal anomalies have been identified from 1970's. Their location is important to prevent hazards in this restricted touristic area of the park. Presently, only some regional geophysical studies based on gravity, magnetic and seismic data have been undertaken to model the crustal structure of Lanzarote Island. This work presents a new study about the geothermal anomalies in the Timanfaya National Park by the analysis and joint interpretation of electrical resistivity tomography (ERT), magnetic anomalies and electromagnetic induction data (EMI). All analyzed data have been obtained over areas which had not been surveyed before. The studied geothermal field is located at the Islote de Hilario visitor's centre. One 50m-long GPR profile was carried out in May 2012 along the location of a known geothermal anomaly developed over pyroclastic deposits. The two main characteristics are: a) no continuous subhorizontal reflections are displayed up to 12 m depth and, b) the intensity of the reflections varies laterally in good agreement with the location of the geothermal anomalies (the higher the ground temperature, the greater the intensity of the GPR signal). Thus, an outline of the subsurface area with higher temperatures can be observed, indicating that the heat source is deeper at the beginning of the profile and extends laterally and progressively shallower towards the end. Temporal variation of the shallow temperature distribution was also investigated by repeating the same GPR profile in April 2015. Although both profiles look quite similar, subtle variations of the GPR signal intensity suggest a certain temporal variation of the ground temperature. In November 2012 a land magnetic survey was carried out in Timanfaya. In the Islote de Hilario area, total field magnetic data were acquired with

Causal relationships between solar proton events and single event upsets for communication satellites

Science.gov (United States)

Lohmeyer, W. Q.; Cahoy, K.; Liu, Shiyang

In this work, we analyze a historical archive of single event upsets (SEUs) maintained by Inmarsat, one of the world's leading providers of global mobile satellite communications services. Inmarsat has operated its geostationary communication satellites and collected extensive satellite anomaly and telemetry data since 1990. Over the course of the past twenty years, the satellites have experienced more than 226 single event upsets (SEUs), a catch-all term for anomalies that occur in a satellite's electronics such as bit-flips, trips in power supplies, and memory changes in attitude control systems. While SEUs are seemingly random and difficult to predict, we correlate their occurrences to space weather phenomena, and specifically show correlations between SEUs and solar proton events (SPEs). SPEs are highly energetic protons that originate from solar coronal mass ejections (CMEs). It is thought that when these particles impact geostationary (GEO) satellites they can cause SEUs as well as solar array degradation. We calculate the associated statistical correlations that each SEU occurs within one day, one week, two weeks, and one month of 10 MeV SPEs between 10 - 10,000 particle flux units (pfu). However, we find that SPEs are most prevalent at solar maximum and that the SEUs on Inmarsat's satellites occur out of phase with the solar maximum. Ultimately, this suggests that SPEs are not the primary cause of the Inmarsat SEUs. A better understanding of the causal relationship between SPEs and SEUs will help the satellite communications industry develop component and operational space weather mitigation techniques as well as help the space weather community to refine radiation models.

An equivalent layer magnetization model for Australia based on Magsat data

Science.gov (United States)

Mayhew, M. A.; Johnson, B. D.

1987-01-01

An equivalent layer magnetization model for Australia and adjacent oceanic areas is presented. The model is obtained by linear inversion of Magsat anomaly data measured in the altitude range 325-550 km. The anomaly data set has been isolated from the raw data set by use of models of the core field and very long wavelength external fields, and is internally consistent. Certain major structural features of the Australian continent are geographically associated with magnetization anomalies. A first-order difference is seen between the Tasman Zone and the Precambrian cratonic areas: magnetization anomalies are much more subdued in the former, possibly reflecting a shallowing of the Curie isotherm within the crust. A profile of the vertical integral of magnetization is presented for a crustal section extending from the Gawler Block to the southeast coast. It is shown that the magnetization variations are probably due partly, but not wholly, to depth to Curie isotherm variations; gross magnetization variations among at least three distinct crustal units must be involved.

The Response of Equatorial Ionization Anomaly in 120°E to the Geomagnetic Storm of 18 August 2003 at Different Altitudes From Multiple Satellite Observations

Science.gov (United States)

Luo, Weihua; Zhu, Zhengping; Xiong, Chao; Chang, Shanshan

2017-12-01

In this paper, the variations of equatorial ionization anomaly (EIA) in 120°E region during the 17-20 August 2003 storm are investigated from measurements of satellites at different altitudes from Challenging Minisatellite Payload (CHAMP), Gravity Recovery and Climate Experiment (GRACE), scientific satellite of the Republic of China (ROCSAT-1), and Defense Meteorological Satellite Program missions. The results showed that (1) at CHAMP and GRACE altitudes, the EIA was inhibited before the storm sudden commencement (SSC) and also during the storm recovery phase, but it was enhanced significantly during the storm main phase of the storm. (2) The variations of EIA strength and interhemispheric density asymmetry of the two crests were similar at CHAMP and GRACE altitudes, while the location asymmetry of the two crests was different at CHAMP and GRACE altitudes. (3) The irregularities and long-duration scintillation were recorded before the SSC of the storm, when the EIA was inhibited. The irregularities at different altitudes and short-duration scintillation were observed during the main phase of the storm, when the EIA was enhanced significantly. (4) The EIA enhancement can be attributed to the enhanced electric field due to prompt penetration interplanetary electric fields and the storm time neutral wind, while the suppression of EIA on 17 August can be attributed to the absence of the equatorward neutral wind, which varied with the altitudes. The EIA inhibition during the recovery phase may be caused mainly by the neutral wind. Our results suggest that the neutral wind is the crucial factor causing the variations in EIA and the occurrence of scintillation.

Application of isostatic gravity anomaly in the Yellow Sea area

Science.gov (United States)

Hao, Z.; Qin, J.; Huang, W.; Wu, X.

2017-12-01

In order to study the deep crustal structure of the Yellow Sea area, we used the Airy-Heiskanen model to calculate the isostatic gravity anomaly of this area. Based on the Bouguer gravity anomaly and water depth data of this area, we chose the calculating parameters as standard crustal thickness 30 km, crust-mantle density difference 0.6g/cm3and grid spacing 0.1°×0.1°. This study reveals that there are six faults and four isostatic negative anomalies in the study area. The isostatic anomalies in much of Yellow Sea areas give priority to those with positive anomalies. The isostatic anomalies in North Yellow Sea are higher than South Yellow Sea with Jiashan-Xiangshui fault as the boundary. In the north of the study area, isostatic anomalies are characterized by large areas of positive anomaly. The change is relatively slow, and the trends give priority to the trend NE or NEE. In the middle of the north Yellow Sea basin, there is a local negative anomaly, arranged as a string of beads in NE to discontinuous distribution. Negative anomaly range is small, basically corresponds to the region's former Cenozoic sedimentary basin position. To the south of Jiashan-Xiangshui fault and west of Yellow Sea eastern margin fault, including most of the south Yellow Sea and Jiangsu province, the isostatic anomalies are lower. And the positive and negative anomalies are alternative distribution, and negative anomaly trap in extensive development. The trends give priority to NE, NEE, both to the NW. On the basis of the characteristics of isostatic gravity anomalies, it is concluded that the Yellow Sea belongs to continental crustal isostatic area whose isostatic anomalies is smooth and slow. ReferencesHeiskanen, W. A., F. A. V. Meinesz, and S. A. Korff (1958), The Earth and Its Gravity Field, McGraw-Hill, New York. Meng, X. J., X. H. Zhang, and J. Y. Yang (2014), Geophysical survey in eastern China seas and the characteristics of gravity and magnetic fields, Marine Geoglogy

Magnetic study of the Furnas caldera (Azores

Directory of Open Access Journals (Sweden)

J. M. Torta

1997-06-01

Full Text Available A local ground magnetic study of the Furnas caldera (S. Miguel Island, Azores has provided new insight into the magnetic structure of this volcano. Analysis of the data comprised removal of the IGRF, reduction to the pole, pseudogravity integration and upward continuation. Also, a spectral method was applied to estimate the depth to the magnetic sources, as well as a 2.5D forward modelling technique. Magnetic properties obtained at the laboratory for some representative sample rocks were considered in the modelling process. The most relevant features are the existence of an important negative anomaly inside the caldera and of an intense positive anomaly to the south of the coast. The former points out a decrease in the magnetization of the caldera filling materials with respect to the surrounding rocks, which could be explained as the result of post-eruption processes such as hydrothermal alteration. This is expected as Furnas has an active hydrothermal system probably related with a magmatic reservoir at high temperature. The positive anomaly suggests the existence of a strongly-magnetized body beneath the south coast.

High energy electron and proton observations in the South Atlantic geomagnetic anomaly

International Nuclear Information System (INIS)

Nakamura, Y.; Takahashi, H.; Nagata, K.; Kohno, T.; Murakami, H.

1988-01-01

The method developed by researchers of cooperation agreement between Japan and Brazil, to observe high energy particles in the South Atlantic Geomagnetic Anomaly, is described. The energy spectra and pitch angle distributions of electrons and protons, using silicon detectors of good energy resolution and two spectrometers with different geometrical factors, on board of the OHZORA satellite, were determined. (M.C.K.) [pt

A new model of Earth's radial conductivity structure derived from over 10 yr of satellite and observatory magnetic data

DEFF Research Database (Denmark)

Püthe, Christoph; Kuvshinov, Alexey; Khan, Amir

2015-01-01

We present a newmodel of the radial (1-D) conductivity structure of Earth's mantle. This model is derived frommore than 10 yr of magnetic measurements from the satellites ørsted, CHAMP, SAC-C and the Swarm trio as well as the global network of geomagnetic observatories. After removal of core...

Detecting robust signals of interannual variability of gross primary productivity in Asia from multiple terrestrial carbon cycle models and long-term satellite-based vegetation data

Science.gov (United States)

Ichii, K.; Kondo, M.; Ueyama, M.; Kato, T.; Ito, A.; Sasai, T.; Sato, H.; Kobayashi, H.; Saigusa, N.

2014-12-01

Long term record of satellite-based terrestrial vegetation are important to evaluate terrestrial carbon cycle models. In this study, we demonstrate how multiple satellite observation can be used for evaluating past changes in gross primary productivity (GPP) and detecting robust anomalies in terrestrial carbon cycle in Asia through our model-data synthesis analysis, Asia-MIP. We focused on the two different temporal coverages: long-term (30 years; 1982-2011) and decadal (10 years; 2001-2011; data intensive period) scales. We used a NOAA/AVHRR NDVI record for long-term analysis and multiple satellite data and products (e.g. Terra-MODIS, SPOT-VEGETATION) as historical satellite data, and multiple terrestrial carbon cycle models (e.g. BEAMS, Biome-BGC, ORCHIDEE, SEIB-DGVM, and VISIT). As a results of long-term (30 years) trend analysis, satellite-based time-series data showed that approximately 40% of the area has experienced a significant increase in the NDVI, while only a few areas have experienced a significant decreasing trend over the last 30 years. The increases in the NDVI were dominant in the sub-continental regions of Siberia, East Asia, and India. Simulations using the terrestrial biosphere models also showed significant increases in GPP, similar to the results for the NDVI, in boreal and temperate regions. A modeled sensitivity analysis showed that the increases in GPP are explained by increased temperature and precipitation in Siberia. Precipitation, solar radiation, CO2fertilization and land cover changes are important factors in the tropical regions. However, the relative contributions of each factor to GPP changes are different among the models. Year-to-year variations of terrestrial GPP were overall consistently captured by the satellite data and terrestrial carbon cycle models if the anomalies are large (e.g. 2003 summer GPP anomalies in East Asia and 2002 spring GPP anomalies in mid to high latitudes). The behind mechanisms can be consistently

Planetary Magnetism

International Nuclear Information System (INIS)

Russell, C.T.

1980-01-01

Planetary spacecraft have now probed the magnetic fields of all the terrestrial planets, the moon, Jupiter, and Saturn. These measurements reveal that dynamos are active in at least four of the planets, Mercury, the earth, Jupiter, and Saturn but that Venus and Mars appear to have at most only very weak planetary magnetic fields. The moon may have once possessed an internal dynamo, for the surface rocks are magnetized. The large satellites of the outer solar system are candidates for dynamo action in addition to the large planets themselves. Of these satellites the one most likely to generate its own internal magnetic field is Io

Electric propulsion reliability: Statistical analysis of on-orbit anomalies and comparative analysis of electric versus chemical propulsion failure rates

Science.gov (United States)

Saleh, Joseph Homer; Geng, Fan; Ku, Michelle; Walker, Mitchell L. R.

2017-10-01

With a few hundred spacecraft launched to date with electric propulsion (EP), it is possible to conduct an epidemiological study of EP's on orbit reliability. The first objective of the present work was to undertake such a study and analyze EP's track record of on orbit anomalies and failures by different covariates. The second objective was to provide a comparative analysis of EP's failure rates with those of chemical propulsion. Satellite operators, manufacturers, and insurers will make reliability- and risk-informed decisions regarding the adoption and promotion of EP on board spacecraft. This work provides evidence-based support for such decisions. After a thorough data collection, 162 EP-equipped satellites launched between January 1997 and December 2015 were included in our dataset for analysis. Several statistical analyses were conducted, at the aggregate level and then with the data stratified by severity of the anomaly, by orbit type, and by EP technology. Mean Time To Anomaly (MTTA) and the distribution of the time to (minor/major) anomaly were investigated, as well as anomaly rates. The important findings in this work include the following: (1) Post-2005, EP's reliability has outperformed that of chemical propulsion; (2) Hall thrusters have robustly outperformed chemical propulsion, and they maintain a small but shrinking reliability advantage over gridded ion engines. Other results were also provided, for example the differentials in MTTA of minor and major anomalies for gridded ion engines and Hall thrusters. It was shown that: (3) Hall thrusters exhibit minor anomalies very early on orbit, which might be indicative of infant anomalies, and thus would benefit from better ground testing and acceptance procedures; (4) Strong evidence exists that EP anomalies (onset and likelihood) and orbit type are dependent, a dependence likely mediated by either the space environment or differences in thrusters duty cycles; (5) Gridded ion thrusters exhibit both

MAPS OF IMPACT ZONES OF REGION OF THE KURSK MAGNETIC ANOMALY FOR THE ECOLOGICAL ATLAS OF RUSSIA

Directory of Open Access Journals (Sweden)

O. I. Markova

2016-01-01

Full Text Available Maps of several impact zones of the Russian Federation are included in the Ecological Atlas of Russia. These zones are characterized by the high degree of the development of the mining industry and respectively by high level of the anthropogenic impact on the environment. One of these regions is the region of the Kursk Magnetic Anomaly (КМА, where the extractive industry is most developed in separate areas of Kursk and Belgorod regions. During a long time the iron ore is mined here both open and closed methods. The general map of the Kursk Magnetic Anomaly lets to see in complex all iron ore regions and deposits and to reveal most environmentally dangerous of them as well as to evaluate the significance of deposits. Large-scale maps let to consider diverse anthropogenic changes of the environment caused by the extractive industry as well as by related industries. In regions of the intensive development of the mining industry with great areas included in the process of the industrial production and the storage of wastes take place the movement of huge masses of ground, the destruction and the degradation of the vegetation cover, the destruction of the traditional structure of settlements and the disappearance of most settlements. In example of areas of impact zones processes of the disappearance of rural settlements, of the urban sprawl and of displacement of the agriculture by the extractive industry can be seen firsthand. A registration of the development of this process is very important in the planning of the development of territories, all the more so the region of the Kursk Magnetic Anomaly has fertile chernozem soils which are not very abundant in the territory of the Russian Federation. Mining complexes are surrounded by a range of related companies serving the production and livelihoods of the population. These companies also have an impact on the environment, sometimes significantly changing it. Serious changes

Enhanced Magnetic Model 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Enhanced Magnetic Model (EMM) extends to degree and order 720, resolving magnetic anomalies down to 56 km wavelength. The higher resolution of the EMM results in...

Enhanced Magnetic Model 2010

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Enhanced Magnetic Model (EMM) extends to degree and order 720, resolving magnetic anomalies down to 56 km wavelength. The higher resolution of the EMM results in...

Magnetization of lower oceanic crust and upper mantle

Science.gov (United States)

Kikawa, E.

2004-05-01

The location of the magnetized rocks of the oceanic crust that are responsible for sea-floor spreading magnetic anomalies has been a long-standing problem in geophysics. The recognition of these anomalies was a key stone in the development of the theory of plate tectonics. Our present concept of oceanic crustal magnetization is much more complex than the original, uniformly magnetized model of Vine-Matthews-Morley Hypothesis. Magnetic inversion studies indicated that the upper oceanic extrusive layer (Layer 2A of 0.5km thick) was the only magnetic layer and that it was not necessary to postulate any contribution from deeper parts of oceanic crust. Direct measurements of the magnetic properties of the rocks recovered from the sea floor, however, have shown that the magnetization of Layer 2A, together with the observations that this layer could record geomagnetic field reversals within a vertical section, is insufficient to give the required size of observed magnetic anomalies and that some contribution from lower intrusive rocks is necessary. Magnetization of oceanic intrusive rocks were observed to be reasonably high enough to contribute to sea-floor spreading magnetic anomalies, but were considered somewhat equivocal until late 1980Os, in part because studies had been conducted on unoriented dredged and ophiolite samples and on intermittent DSDP/ODP cores. Since ODP Leg 118 that cored and recovered continuous 500m of oceanic intrusive layer at Site 735B, Southwest Indian Ridge with an extremely high recovery of 87 percent, there have been several ODP Legs (legs 147, 153, 176, 179 and 209) that were devoted to drilling gabbroic rocks and peridotites. In terms of the magnetization intensities, all of the results obtained from these ODP Legs were supportive of the model that a significant contribution must come from gabbros and peridotites and the source of the lineated magnetic anomalies must reside in most of the oceanic crust as well as crust-mantle boundary

The Advanced Stellar Compass onboard the Oersted satellite

DEFF Research Database (Denmark)

Jørgensen, John Leif; Eisenman, Allan R.; Liebe, Carl Christian

1997-01-01

In 1997 the first Danish satellite will be launched. The primarily scientific objective of the satellite is to map the magnetic field of the Earth. The attitude of the satellite is determined by an advanced stellar compass (star tracker). An advanced stellar compass consists of a CCD camera...

Magnetic susceptibility measurements in Yellowstone National Park, USA; Beikoku Yellowstone kokuritsu koen ni okeru genchi jikaritsu sokutei

Energy Technology Data Exchange (ETDEWEB)

Okuma, S [Geological Survey of Japan, Tsukuba (Japan)

1997-05-27

For the purpose of interpreting data of the aeromagnetic anomalies in Yellowstone National Park in the U.S.A., in-situ magnetization intensity measurements have been carried out in 1994 and 1995 on geological outcrops of rocks in that area. Comparisons and discussions were given on the measurement results, and existing rock magnetic data and aeromagnetic anomaly data available for the area. Outside the Yellowstone caldera, part of granitic gneisses among the Precambrian granitic gneisses and crystalline schists distributed to the north has an abnormally high magnetization intensity of 1 {times} 10 {sup -2} SI. This could be a powerful anomaly source for the high magnetic anomaly in this area. Paleogene volcanic rocks distributed widely in the eastern part of the park also have magnetization intensity as high as 1 {times} 10 {sup -2} SI or higher, which are also thought a powerful anomaly source in this area. Part of Pleistocene basalts which are exposed partially in the western part of the park has also very high magnetization intensity at 1 {times} 10 {sup -2} SI or higher. This suggests correlation with the magnetic anomaly in the east-west direction distributed in this area. Quaternary rhyolites are more magnetic than Quaternary welded tuffs, which should give greater effects to the magnetic anomaly. 10 refs., 5 figs.

3D PIC SIMULATIONS OF COLLISIONLESS SHOCKS AT LUNAR MAGNETIC ANOMALIES AND THEIR ROLE IN FORMING LUNAR SWIRLS

Energy Technology Data Exchange (ETDEWEB)

Bamford, R. A.; Kellett, B. J. [RAL Space, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX (United Kingdom); Alves, E. P.; Cruz, F.; Silva, L. O [GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon (Portugal); Fonseca, R. A. [DCTI/ISCTE—Instituto Universitário de Lisboa, 1649-026 Lisbon (Portugal); Trines, R. M. G. M. [Central Laser Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX (United Kingdom); Halekas, J. S. [Department of Physics and Astronomy, 414 Van Allen Hall, University of Iowa, Iowa City, IA 52242 (United States); Kramer, G. [The Lunar and Planetary Institute, USRA, 3600 Bay Area Blvd, Houston, TX 77058 (United States); Harnett, E. [Department of Earth and Space Science, University of Washington, Seattle, WA 98195-1310 (United States); Cairns, R. A. [University of St Andrews, North Haugh, St. Andrews, Fife, KY16 9SS (United Kingdom); Bingham, R., E-mail: Ruth.Bamford@stfc.ac.uk [SUPA, University of Strathclyde, Glasgow, Scotland, 4G 0NG (United Kingdom)

2016-10-20

Investigation of the lunar crustal magnetic anomalies offers a comprehensive long-term data set of observations of small-scale magnetic fields and their interaction with the solar wind. In this paper a review of the observations of lunar mini-magnetospheres is compared quantifiably with theoretical kinetic-scale plasma physics and 3D particle-in-cell simulations. The aim of this paper is to provide a complete picture of all the aspects of the phenomena and to show how the observations from all the different and international missions interrelate. The analysis shows that the simulations are consistent with the formation of miniature (smaller than the ion Larmor orbit) collisionless shocks and miniature magnetospheric cavities, which has not been demonstrated previously. The simulations reproduce the finesse and form of the differential proton patterns that are believed to be responsible for the creation of both the “lunar swirls” and “dark lanes.” Using a mature plasma physics code like OSIRIS allows us, for the first time, to make a side-by-side comparison between model and space observations. This is shown for all of the key plasma parameters observed to date by spacecraft, including the spectral imaging data of the lunar swirls. The analysis of miniature magnetic structures offers insight into multi-scale mechanisms and kinetic-scale aspects of planetary magnetospheres.

Magnetic structure of volcanic neck; Kazangankei no jiki kozo

Energy Technology Data Exchange (ETDEWEB)

Makino, M; Okuma, S; Morijiri, R; Nakatsuka, T [Geological Survey of Japan, Tsukuba (Japan)

1997-05-27

This paper describes the summary and result of magnetic exploration on the Kabutoyama volcano in the city of Nishinomiya, Hyogo Prefecture, Japan. It also states the interpretation and discussion on magnetic anomaly in the volcanic conduit of the mountain by using a three-dimensional magnetic structure model. Terrain surface magnetic exploration for the Kabutoyama volcano was performed by using six traverse lines each in different azimuths with the triangulation point at the summit as the basic point and by using a proton magnetometer. The exploration results of the six traverse lines around the Kabutoyama volcano may be generalized as follows: magnetic anomaly in the vicinity of the summit is moderate with little change, but it increases to 500 nT to 2,500 nT in the vicinity of the distances of 150 m to 200 m; a peak is formed with a width of a few tens of meters; and the magnetic anomaly showed a trend of rapidly decreasing at outer sides of the peak. The results of the magnetic exploration and the magnetization intensity measurement leads to a belief that such a magnetic anomalous band of an annular form would exist corresponding to the boundary or its vicinity of andesite and granite, and the Rokko granite having magnetization intensity as small as can be neglected would be distributed at outer sides of the boundary. The result of the three-dimensional magnetic structure model calculation, which assumes the internal structure of the magnetic structure to be non-uniformly magnetized, reproduced the magnetic anomaly patterns well as compared with the observation results. 1 ref., 5 figs.

3-D electromagnetic induction studies using the Swarm constellation: Mapping conductivity anomalies in the Earth's mantle

DEFF Research Database (Denmark)

Kuvshinov, A.; Sabaka, T.; Olsen, Nils

2006-01-01

the geometry of the mantle heterogeneities used in the forward approach. numerical experiments have been undertaken using various satellite combinations, sampling periods of the resulting time series, and numbers of internal coefficients. The possibility of the approach to map anomalies in the mantle using...

Ionospheric quasi-static electric field anomalies during seismic activity in August–September 1981

Directory of Open Access Journals (Sweden)

M. Gousheva

2009-01-01

Full Text Available The paper proposes new results, analyses and information for the plate tectonic situation in the processing of INTERCOSMOS-BULGARIA-1300 satellite data about anomalies of the quasi-static electric field in the upper ionosphere over activated earthquake source regions at different latitudes. The earthquake catalogue is made on the basis of information from the United State Geological Survey (USGS website. The disturbances in ionospheric quasi-static electric fields are recorded by IESP-1 instrument aboard the INTERCOSMOS-BULGARIA-1300 satellite and they are compared with significant seismic events from the period 14 August–20 September 1981 in magnetically very quiet, quiet and medium quiet days. The main tectonic characteristics of the seismically activated territories are also taken in account. The main goal of the above research work is to enlarge the research of possible connections between anomalous vertical electric field penetrations into the ionosphere and the earthquake manifestations, also to propose tectonic arguments for the observed phenomena. The studies are represented in four main blocks: (i previous studies of similar problems, (ii selection of satellite, seismic and plate tectonic data, (iii data processing with new specialized software and observations of the quasi-static electric field and (iiii summary, comparison of new with previous results in our studies and conclusion. We establish the high informativity of the vertical component Ez of the quasi-static electric field in the upper ionosphere according observations by INTERCOSMOS-BULGARIA-1300 that are placed above considerably activated earthquake sources. This component shows an increase of about 2–10 mV/m above sources, situated on mobile structures of the plates. The paper discusses the observed effects. It is represented also a statistical study of ionospheric effects 5–15 days before and 5–15 days after the earthquakes with magnitude M 4.8–7.9.

Gravitational anomalies

Energy Technology Data Exchange (ETDEWEB)

Leutwyler, H; Mallik, S

1986-12-01

The effective action for fermions moving in external gravitational and gauge fields is analyzed in terms of the corresponding external field propagator. The central object in our approach is the covariant energy-momentum tensor which is extracted from the regular part of the propagator at short distances. It is shown that the Lorentz anomaly, the conformal anomaly and the gauge anomaly can be expressed in terms of the local polynomials which determine the singular part of the propagator. (There are no coordinate anomalies). Except for the conformal anomaly, for which we give explicit representations only in dless than or equal to4, we consider an arbitrary number of dimensions.

Specific heat and magnetization of RMn2(H,D)2

International Nuclear Information System (INIS)

Tarnawski, Z.; Kolwicz-Chodak, L.; Figiel, H.; Kim-Ngan, N.-T.H.; Havela, L.; Miliyanchuk, K.; Sechovsky, V.; Santava, E.; Sebek, J.

2007-01-01

The effect of hydrogen absorption on magnetic and thermodynamic properties of hydrides compounds RMn 2 (H,D) 2 (R = Y, Nd, Tb, Ho, and Er) have been investigated by performing specific heat and magnetization measurements in the temperature range of 2-320 K and in magnetic fields up to 9 T. The phase transition to the antiferromagnetic order accompanying a crystal structure transformation have been revealed by complicated-structure anomalies in specific heat and weak anomalies in magnetization

Satellite monitoring temperature conditions spawning area of the Northeast Arctic cod in the Norwegian Sea and assessment its abundance

Science.gov (United States)

Vanyushin, George; Bulatova, Tatiana; Klochkov, Dmitriy; Troshkov, Anatoliy; Kruzhalov, Michail

2013-04-01

In this study, the attempt to consider the relationship between sea surface anomalies of temperature (SST anomalies °C) in spawning area of the Norwegian Arctic cod off the Lofoten islands in coastal zone of the Norwegian Sea and modern cod total stock biomass including forecasting assessment of future cod generation success. Continuous long-term database of the sea surface temperature (SST) was created on the NOAA satellites data. Mean monthly SST and SST anomalies are computed for the selected area on the basis of the weekly SST maps for the period of 1998-2012. These maps were plotted with the satellite SST data, as well as information of vessels, byoies and coastal stations. All data were classified by spawning seasons (March-April) and years. The results indicate that poor and low middle generations of cod (2001, 2006, 2007) occurred in years with negative or extremely high positive anomalies in the spawning area. The SST anomalies in years which were close to normal or some more normal significances provide conditions for appearance strong or very strong generations of cod (1998, 2000, 2002, 2004, 2005, 2006, 2008, 2009). Temperature conditions in concrete years influence on different indexes of cod directly. So, the mean temperature in spawning seasons in years 1999-2005 was ≈5,0°C and SST anomaly - +0,35°C, by the way average year significances indexes of cod were: total stock biomass - 1425,0 th.t., total spawning biomass - 460,0 th.t., recruitment (age 3+) - 535,0 mln. units and landings - 530,0 th.t. In spawning seasons 2006-2012 years the average data were following: mean SST ≈6,0°C, SST anomaly - +1,29°C, total stock biomass - 2185,0 th.t., total spawning biomass - 1211,0 th.t., recruitment (age 3+) - 821,0 mln. units and landings - 600,0 th.t. The SST and SST anomalies (the NOAA satellite data) characterize increase of decrease in input of warm Atlantic waters which form numerous eddies along the flows of the main warm currents thus creating

Effect of Ionosphere on Geostationary Communication Satellite Signals

Science.gov (United States)

Erdem, Esra; Arikan, Feza; Gulgonul, Senol

2016-07-01

Geostationary orbit (GEO) communications satellites allow radio, television, and telephone transmissions to be sent live anywhere in the world. They are extremely important in daily life and also for military applications. Since, satellite communication is an expensive technology addressing crowd of people, it is critical to improve the performance of this technology. GEO satellites are at 35,786 kilometres from Earth's surface situated directly over the equator. A satellite in a geostationary orbit (GEO) appears to stand still in the sky, in a fixed position with respect to an observer on the earth, because the satellite's orbital period is the same as the rotation rate of the Earth. The advantage of this orbit is that ground antennas can be fixed to point towards to satellite without their having to track the satellite's motion. Radio frequency ranges used in satellite communications are C, X, Ku, Ka and even EHG and V-band. Satellite signals are disturbed by atmospheric effects on the path between the satellite and the receiver antenna. These effects are mostly rain, cloud and gaseous attenuation. It is expected that ionosphere has a minor effect on the satellite signals when the ionosphere is quiet. But there are anomalies and perturbations on the structure of ionosphere with respect to geomagnetic field and solar activity and these conditions may cause further affects on the satellite signals. In this study IONOLAB-RAY algorithm is adopted to examine the effect of ionosphere on satellite signals. IONOLAB-RAY is developed to calculate propagation path and characteristics of high frequency signals. The algorithm does not have any frequency limitation and models the plasmasphere up to 20,200 km altitude, so that propagation between a GEO satellite and antenna on Earth can be simulated. The algorithm models inhomogeneous, anisotropic and time dependent structure of the ionosphere with a 3-D spherical grid geometry and calculates physical parameters of the

Magnetic, in situ, mineral characterization of Chelyabinsk meteorite thin section

Science.gov (United States)

Nabelek, Ladislav; Mazanec, Martin; Kdyr, Simon; Kletetschka, Gunther

2015-06-01

Magnetic images of Chelyabinsk meteorite's (fragment F1 removed from Chebarkul lake) thin section have been unraveled by a magnetic scanning system from Youngwood Science and Engineering (YSE) capable of resolving magnetic anomalies down to 10-3 mT range from about 0.3 mm distance between the probe and meteorite surface (resolution about 0.15 mm). Anomalies were produced repeatedly, each time after application of magnetic field pulse of varying amplitude and constant, normal or reversed, direction. This process resulted in both magnetizing and demagnetizing of the meteorite thin section, while keeping the magnetization vector in the plane of the thin section. Analysis of the magnetic data allows determination of coercivity of remanence (Bcr) for the magnetic sources in situ. Value of Bcr is critical for calculating magnetic forces applicable during missions to asteroids where gravity is compromised. Bcr was estimated by two methods. First method measured varying dipole magnetic field strength produced by each anomaly in the direction of magnetic pulses. Second method measured deflections of the dipole direction from the direction of magnetic pulses. Bcr of magnetic sources in Chelyabinsk meteorite ranges between 4 and 7 mT. These magnetic sources enter their saturation states when applying 40 mT external magnetic field pulse.

Holonomy anomalies

International Nuclear Information System (INIS)

Bagger, J.; Nemeschansky, D.; Yankielowicz, S.

1985-05-01

A new type of anomaly is discussed that afflicts certain non-linear sigma models with fermions. This anomaly is similar to the ordinary gauge and gravitational anomalies since it reflects a topological obstruction to the reparametrization invariance of the quantum effective action. Nonlinear sigma models are constructed based on homogeneous spaces G/H. Anomalies arising when the fermions are chiral are shown to be cancelled sometimes by Chern-Simons terms. Nonlinear sigma models are considered based on general Riemannian manifolds. 9 refs

Global correlation imaging of magnetic total field gradients

International Nuclear Information System (INIS)

Guo, Lianghui; Meng, Xiaohong; Shi, Lei

2012-01-01

Firstly we introduce the correlation imaging approach for the x-, y- and z-gradients of a magnetic total field anomaly for deriving the distribution of equivalent magnetic sources of the subsurface. In this approach, the subsurface space is divided into a regular grid, and then a correlation coefficient function is computed at each grid node, based on the cross-correlation between the x-gradient (or y-gradient or z-gradient) of the observed magnetic total field anomaly and the x-gradient (or y-gradient or z-gradient) of the theoretical magnetic total field anomaly due to a magnetic dipole. The resultant correlation coefficient is used to describe the probability of a magnetic dipole occurring at the node. We then define a global correlation coefficient function for comprehensively delineating the probability of an occurrence of a magnetic dipole, which takes, at each node, the maximum positive value of the corresponding correlation coefficient function of the three gradients. We finally test the approach both on synthetic data and real data from a metallic deposit area in the middle-lower reaches of the Yangtze River, China. (paper)

Extraction of remanent magnetization from magnetization vector inversions of airborne full tensor magnetic gradiometry data

Science.gov (United States)

Queitsch, M.; Schiffler, M.; Stolz, R.; Meyer, M.; Kukowski, N.

2017-12-01

Measurements of the Earth's magnetic field are one of the most used methods in geophysical exploration. The ambiguity of the method, especially during modeling and inversion of magnetic field data sets, is one of its biggest challenges. Additional directional information, e.g. gathered by gradiometer systems based on Superconducting Quantum Interference Devices (SQUIDs), will positively influence the inversion results and will thus lead to better subsurface magnetization models. This is especially beneficial, regarding the shape and direction of magnetized structures, especially when a significant remanent magnetization of the underlying sources is present. The possibility to separate induced and remanent contributions to the total magnetization may in future also open up advanced ways for geological interpretation of the data, e.g. a first estimation of diagenesis processes. In this study we present the results of airborne full tensor magnetic gradiometry (FTMG) surveys conducted over a dolerite intrusion in central Germany and the results of two magnetization vector inversions (MVI) of the FTMG and a conventional total field anomaly data set. A separation of the two main contributions of the acquired total magnetization will be compared with information of the rock magnetization measured on orientated rock samples. The FTMG inversion results show a much better agreement in direction and strength of both total and remanent magnetization compared to the inversion using only total field anomaly data. To enhance the separation process, the application of additional geophysical methods, i.e. frequency domain electromagnetics (FDEM), in order to gather spatial information of subsurface rock susceptibility will also be discussed. In this approach, we try to extract not only information on subsurface conductivity but also the induced magnetization. Using the total magnetization from the FTMG data and the induced magnetization from the FDEM data, the full separation of

Anomalies

International Nuclear Information System (INIS)

Bardeen, W.A.

1985-08-01

Anomalies have a diverse impact on many aspects of physical phenomena. The role of anomalies in determining physical structure from the amplitude for π 0 decay to the foundations of superstring theory will be reviewed. 36 refs

INSPIRE Project (IoNospheric Sounding for Pre-seismic anomalies Identification REsearch): Main Results and Future Prospects

Science.gov (United States)

Pulinets, S. A.; Andrzej, K.; Hernandez-Pajares, M.; Cherniak, I.; Zakharenkova, I.; Rothkaehl, H.; Davidenko, D.

2017-12-01

The INSPIRE project is dedicated to the study of physical processes and their effects in ionosphere which could be determined as earthquake precursors together with detailed description of the methodology of ionospheric pre-seismic anomalies definition. It was initiated by ESA and carried out by international consortium. The physical mechanisms of the ionospheric pre-seismic anomalies generation from ground to the ionosphere altitudes were formulated within framework of the Lithosphere-Atmosphere-Ionosphere-Magnetosphere Coupling (LAIMC) model (Pulinets et al., 2015). The general algorithm for the identification of the ionospheric precursors was formalized which also takes into account the external Space Weather factors able to generate the false alarms. Importance of the special stable pattern called the "precursor mask" was highlighted which is based on self-similarity of pre-seismic ionospheric variations. The role of expert decision in pre-seismic anomalies interpretation for generation of seismic warning is important as well. The algorithm performance of the LAIMC seismo-ionospheric effect detection module has been demonstrated using the L'Aquila 2009 earthquake as a case study. The results of INSPIRE project have demonstrated that the ionospheric anomalies registered before the strong earthquakes could be used as reliable precursors. The detailed classification of the pre-seismic anomalies was presented in different regions of the ionosphere and signatures of the pre-seismic anomalies as detected by ground and satellite based instruments were described what clarified methodology of the precursor's identification from ionospheric multi-instrumental measurements. Configuration for the dedicated multi-observation experiment and satellite payload was proposed for the future implementation of the INSPIRE project results. In this regard the multi-instrument set can be divided by two groups: space equipment and ground-based support, which could be used for real

The electrical conductivity of the Earth's upper mantle as estimated from satellite measured magnetic field variations. Ph.D. Thesis

Science.gov (United States)

Didwall, E. M.

1981-01-01

Low latitude magnetic field variations (magnetic storms) caused by large fluctuations in the equatorial ring current were derived from magnetic field magnitude data obtained by OGO 2, 4, and 6 satellites over an almost 5 year period. Analysis procedures consisted of (1) separating the disturbance field into internal and external parts relative to the surface of the Earth; (2) estimating the response function which related to the internally generated magnetic field variations to the external variations due to the ring current; and (3) interpreting the estimated response function using theoretical response functions for known conductivity profiles. Special consideration is given to possible ocean effects. A temperature profile is proposed using conductivity temperature data for single crystal olivine. The resulting temperature profile is reasonable for depths below 150-200 km, but is too high for shallower depths. Apparently, conductivity is not controlled solely by olivine at shallow depths.

Magnetic field observations on the Akebono (KXOS-D) satellite

International Nuclear Information System (INIS)

Fukunishi, H.; Fujii, R.; Kokubum, S.

1990-01-01

The Akebono (EXOS-D) satellite carries triaxial fluxgate and search coil magnetometers with sensors mounted on 5-and 3m masts, respectively. The fluxgate magnetometer has four automatically switchable ranges from ±1024 to ±65536 nT (full scale), and resolutions commensurate with a 16-bit A/D converter in each range (0.031 to 2 nT). The rate of sampling is 32 vectors per second. The triaxial search coil magnetometer has a frequency response up to 800 Hz. Signals in the frequency range higher than 100 Hz are used for VLF plasma wave experiments, while signals less than 100 Hz are used for magnetic field experiments. Both magnetometers have been operating consinuously since the 3- and 5-m masts were extended on March 7 and 8, 1989, respectively. Intense small-scale field-aligned currents embedded in the large-scale field-aligned current system were always observed at 1-2 Re altitudes in all local time regions. The region 0 currents which flow in the poleward region adjacent to the region 1 currents were also frequently observed. The search coil magnetometers measured ion cyclotron waves at 1-2 Re altitudes near the equator. (N.K.)

Application of ASTER SWIR bands in mapping anomaly pixels for Antarctic geological mapping

International Nuclear Information System (INIS)

Beiranvand Pour, Amin; Hashim, Mazlan; Park, Yongcheol

2017-01-01

Independent component analysis (ICA) was applied to shortwave infrared (SWIR) bands of ASTER satellite data for detailed mapping of alteration mineral zones in the context of polar environments, where little prior information is available. The Oscar II coast area north-eastern Graham Land, Antarctic Peninsula (AP) was selected to conduct a remote sensing satellite-based mapping approach to detect alteration mineral assemblages. Anomaly pixels in the ICA image maps related to spectral features of Al-O-H, Fe, Mg-O-H and CO3 groups were detected using SWIR datasets of ASTER. ICA method provided image maps of alteration mineral assemblages and discriminate lithological units with little available geological data for poorly mapped regions and/or without prior geological information for unmapped regions in northern and southern sectors of Oscar II coast area, Graham Land. The results of this investigation demonstrated the applicability of ASTER spectral data for lithological and alteration mineral mapping in poorly exposed lithologies and inaccessible regions, particularly using the image processing algorithm that are capable to detect anomaly pixels targets in the remotely sensed images, where no prior information is available. (paper)

Anomaly-free models for flavour anomalies

Science.gov (United States)

Ellis, John; Fairbairn, Malcolm; Tunney, Patrick

2018-03-01

We explore the constraints imposed by the cancellation of triangle anomalies on models in which the flavour anomalies reported by LHCb and other experiments are due to an extra U(1)^' gauge boson Z^' . We assume universal and rational U(1)^' charges for the first two generations of left-handed quarks and of right-handed up-type quarks but allow different charges for their third-generation counterparts. If the right-handed charges vanish, cancellation of the triangle anomalies requires all the quark U(1)^' charges to vanish, if there are either no exotic fermions or there is only one Standard Model singlet dark matter (DM) fermion. There are non-trivial anomaly-free models with more than one such `dark' fermion, or with a single DM fermion if right-handed up-type quarks have non-zero U(1)^' charges. In some of the latter models the U(1)^' couplings of the first- and second-generation quarks all vanish, weakening the LHC Z^' constraint, and in some other models the DM particle has purely axial couplings, weakening the direct DM scattering constraint. We also consider models in which anomalies are cancelled via extra vector-like leptons, showing how the prospective LHC Z^' constraint may be weakened because the Z^' → μ ^+ μ ^- branching ratio is suppressed relative to other decay modes.

Kohn Anomaly and Phase Stability in Group VB Transition Metals

Directory of Open Access Journals (Sweden)

Alexander Landa

2018-03-01

Full Text Available In the periodic table, only a few pure metals exhibit lattice or magnetic instabilities associated with Fermi surface nesting, the classical examples being α-U and Cr. Whereas α-U displays a strong Kohn anomaly in the phonon spectrum that ultimately leads to the formation of charge density waves (CDWs, Cr is known for its nesting-induced spin density waves (SDWs. Recently, it has become clear that a pronounced Kohn anomaly and the corresponding softening in the elastic constants is also the key factor that controls structural transformations and mechanical properties in compressed group VB metals—materials with relatively high superconducting critical temperatures. This article reviews the current understanding of the structural and mechanical behavior of these metals under pressure with an introduction to the concept of the Kohn anomaly and how it is related to the important concept of Peierls instability. We review both experimental and theoretical results showing different manifestations of the Kohn anomaly in the transverse acoustic phonon mode TA (ξ00 in V, Nb, and Ta. Specifically, in V the anomaly triggers a structural transition to a rhombohedral phase, whereas in Nb and Ta it leads to an anomalous reduction in yield strength.

Chapter 4: Regional magnetic domains of the Circum-Arctic: A framework for geodynamic interpretation

Science.gov (United States)

Saltus, R.W.; Miller, E.L.; Gaina, C.; Brown, P.J.

2011-01-01

We identify and discuss 57 magnetic anomaly pattern domains spanning the Circum-Arctic. The domains are based on analysis of a new Circum-Arctic data compilation. The magnetic anomaly patterns can be broadly related to general geodynamic classification of the crust into stable, deformed (magnetic and nonmagnetic), deep magnetic high, oceanic and large igneous province domains. We compare the magnetic domains with topography/bathymetry, regional geology, regional free air gravity anomalies and estimates of the relative magnetic 'thickness' of the crust. Most of the domains and their geodynamic classification assignments are consistent with their topographic/bathymetric and geological expression. A few of the domains are potentially controversial. For example, the extent of the Iceland Faroe large igneous province as identified by magnetic anomalies may disagree with other definitions for this feature. Also the lack of definitive magnetic expression of oceanic crust in Baffin Bay, the Norwegian-Greenland Sea and the Amerasian Basin is at odds with some previous interpretations. The magnetic domains and their boundaries provide clues for tectonic models and boundaries within this poorly understood portion of the globe. ?? 2011 The Geological Society of London.

Subsurface Structure Determination of Geotermal Area in Siogung-ogung Samosir District by Using Magnetic Method

Science.gov (United States)

Tampubolon, Togi; Hutahaean, Juniar; Siregar, Suryani N. J.

2018-03-01

Underwater research often uses geomagnets. It is one of the geophysical methods for measuring magnetic field variations. This research was done to identify how the subsurface rock structure is and determine kinds of rock based on its susceptibility value in Siogung-ogung geothermal area, Pangururan, Samosir District. The tool measurement of total magnetic field called Proton Precission Magnetometer, positioning using Global Position System, and north axis determination using geological compass. Data collection was done randomly with total 51 measuring points obtained. Data analysis started with International geomagnetics Reference Field correction to obtain the total magnetic field anomaly. Then, the data analysis of total magnetic anomaly was done by using surfer program 12. To get a magnetic anomaly cross section used Magdc For Windows program. Magnetic measurement results indicated that the variation of magnetic field strength in each point with the lowest magnetic intensity value of 41785.67 nano tesla. The highest magnetic intensity value is 43140, 33. From the results of qualitative interpretation, the magnetic anomaly value is at -200.92 to 1154.45 whereas the quantitative interpretive results of model show the existence of degradation and andesitic rocks, with the value of susceptibility

High-resolution residual geoid and gravity anomaly data of the northern Indian Ocean - An input to geological understanding

Digital Repository Service at National Institute of Oceanography (India)

Sreejith, K.M.; Rajesh, S.; Majumdar, T.J.; Rao, G.S.; Radhakrishna, M.; Krishna, K.S.; Rajawat, A.S.

') geoid anomaly map of the northern Indian Ocean generated from the altimeter data obtained from Geodetic Missions of GEOSAT and ERS-1 along with ERS-2, TOPEX/POSIDEON and JASON satellites is presented. The geoid map of the Indian Ocean is dominated by a...

First and second trimester screening for fetal structural anomalies.

Science.gov (United States)

Edwards, Lindsay; Hui, Lisa

2018-04-01

Fetal structural anomalies are found in up to 3% of all pregnancies and ultrasound-based screening has been an integral part of routine prenatal care for decades. The prenatal detection of fetal anomalies allows for optimal perinatal management, providing expectant parents with opportunities for additional imaging, genetic testing, and the provision of information regarding prognosis and management options. Approximately one-half of all major structural anomalies can now be detected in the first trimester, including acrania/anencephaly, abdominal wall defects, holoprosencephaly and cystic hygromata. Due to the ongoing development of some organ systems however, some anomalies will not be evident until later in the pregnancy. To this extent, the second trimester anatomy is recommended by professional societies as the standard investigation for the detection of fetal structural anomalies. The reported detection rates of structural anomalies vary according to the organ system being examined, and are also dependent upon factors such as the equipment settings and sonographer experience. Technological advances over the past two decades continue to support the role of ultrasound as the primary imaging modality in pregnancy, and the safety of ultrasound for the developing fetus is well established. With increasing capabilities and experience, detailed examination of the central nervous system and cardiovascular system is possible, with dedicated examinations such as the fetal neurosonogram and the fetal echocardiogram now widely performed in tertiary centers. Magnetic resonance imaging (MRI) is well recognized for its role in the assessment of fetal brain anomalies; other potential indications for fetal MRI include lung volume measurement (in cases of congenital diaphragmatic hernia), and pre-surgical planning prior to fetal spina bifida repair. When a major structural abnormality is detected prenatally, genetic testing with chromosomal microarray is recommended over

Chiral battery, scaling laws and magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Anand, Sampurn; Bhatt, Jitesh R.; Pandey, Arun Kumar, E-mail: sampurn@prl.res.in, E-mail: jeet@prl.res.in, E-mail: arunp@prl.res.in [Physical Research Laboratory, Ahmedabad, 380009 (India)

2017-07-01

We study the generation and evolution of magnetic field in the presence of chiral imbalance and gravitational anomaly which gives an additional contribution to the vortical current. The contribution due to gravitational anomaly is proportional to T {sup 2} which can generate seed magnetic field irrespective of plasma being chirally charged or neutral. We estimate the order of magnitude of the magnetic field to be 10{sup 30} G at T ∼ 10{sup 9} GeV, with a typical length scale of the order of 10{sup −18} cm, which is much smaller than the Hubble radius at that temperature (10{sup −8} cm). Moreover, such a system possess scaling symmetry. We show that the T {sup 2} term in the vorticity current along with scaling symmetry leads to more power transfer from lower to higher length scale as compared to only chiral anomaly without scaling symmetry.

Impending ionospheric anomaly preceding the Iquique Mw8.2 earthquake in Chile on 2014 April 1

Science.gov (United States)

Guo, Jinyun; Li, Wang; Yu, Hongjuan; Liu, Zhimin; Zhao, Chunmei; Kong, Qiaoli

2015-12-01

To investigate the coupling relationship between great earthquake and ionosphere, the GPS-derived total electron contents (TECs) by the Center for Orbit Determination in Europe and the foF2 data from the Space Weather Prediction Center were used to analyse the impending ionospheric anomalies before the Iquique Mw8.2 earthquake in Chile on 2014 April 1. Eliminating effects of the solar and geomagnetic activities on ionosphere by the sliding interquartile range with the 27-day window, the TEC analysis results represent that there were negative anomalies occurred on 15th day prior to the earthquake, and positive anomalies appeared in 5th day before the earthquake. The foF2 analysis results of ionosonde stations Jicamarca, Concepcion and Ramey show that the foF2 increased by 40, 50 and 45 per cent, respectively, on 5th day before the earthquake. The TEC anomalous distribution indicates that there was a widely TEC decrement over the epicentre with the duration of 6 hr on 15th day before the earthquake. On 5th day before the earthquake, the TEC over the epicentre increased with the amplitude of 15 TECu, and the duration exceeded 6 hr. The anomalies occurred on the side away from the equator. All TEC anomalies in these days were within the bounds of equatorial anomaly zone where should be the focal area to monitor ionospheric anomaly before strong earthquakes. The relationship between ionospheric anomalies and geomagnetic activity was detected by the cross wavelet analysis, which implied that the foF2 was not affected by the magnetic activities on 15th day and 5th day prior to the earthquake, but the TECs were partially affected by anomalous magnetic activity during some periods of 5th day prior to the earthquake.

Pattern-based approach to fetal congenital cardiovascular anomalies using the transverse aortic arch view on prenatal cardiac MRI

Energy Technology Data Exchange (ETDEWEB)

Dong, Su-Zhen; Zhu, Ming [Shanghai Jiaotong University School of Medicine, Department of Radiology, Shanghai Children' s Medical Center, Shanghai (China)

2015-05-01

Fetal echocardiography is the imaging modality of choice for prenatal diagnosis of congenital cardiovascular anomalies. However, echocardiography has limitations. Fetal cardiac magnetic resonance imaging (MRI) has the potential to complement US in detecting congenital cardiovascular anomalies. This article draws on our experience; it describes the transverse aortic arch view on fetal cardiac MRI and important clues on an abnormal transverse view at the level of the aortic arch to the diagnosis of fetal congenital cardiovascular anomalies. (orig.)

Pattern-based approach to fetal congenital cardiovascular anomalies using the transverse aortic arch view on prenatal cardiac MRI

International Nuclear Information System (INIS)

Dong, Su-Zhen; Zhu, Ming

2015-01-01

Fetal echocardiography is the imaging modality of choice for prenatal diagnosis of congenital cardiovascular anomalies. However, echocardiography has limitations. Fetal cardiac magnetic resonance imaging (MRI) has the potential to complement US in detecting congenital cardiovascular anomalies. This article draws on our experience; it describes the transverse aortic arch view on fetal cardiac MRI and important clues on an abnormal transverse view at the level of the aortic arch to the diagnosis of fetal congenital cardiovascular anomalies. (orig.)

Nature of the Jurassic Magnetic Quiet Zone revealed by the sea-surface, mid-water, and near-source magnetic sensor data in the western Pacific.

Science.gov (United States)

Tominaga, M.; Tivey, M.; Sager, W. W.

2015-12-01

The nature of the Jurassic Quiet Zone (JQZ) has been a long-standing debate in understanding Earth's geomagnetic field history and behavior. We present a coherent and likely globally significant marine magnetic reversal record for the JQZ by constructing a correlation of new and previously acquired magnetic anomaly profiles in the western Pacific. We obtained a high-resolution marine magnetic anomaly record using sea surface, mid-water (3-km level deep-towed), and near-bottom (Autonomous Underwater Vehicle (AUV)) profiles that targeted a spreading corridor in the Hawaiian lineation in 2011 (TN272 on R/V Thompson) and 2014 (SKQ2014S2 on R/V Sikuliaq). To extract crustal magnetic signals, the sea surface and mid-water magnetic data were corrected for ship-to-sensor offset, the diurnal effect, and the present-day ambient geomagnetic field. Mid-water data were upward continued to a constant 3 km level plane and to the sea surface. Near-bottom data were calibrated to remove the induced magnetic field by AUV Sentry, then corrected for IGRF and diurnal variations. We used these near-source data as an anchor for correlations with the sea surface and mid-water level data because of the AUV's superb inertial navigation and hydrodynamically stable, quiet platform environment. Our sea surface anomaly correlation with the previously established Japanese lineation sequence shows (i) an excellent correlation of anomaly shapes from M29 to M42; (ii) a remarkable similarity in anomaly amplitude envelope, which decreases back in time from M19 to M38, with a minimum at M41, then increases back in time from M42; and (iii) refined locations of pre-M25 lineations in the Hawaiian lineation set. Moreover, short-wavelength anomalies from the mid-water and near-bottom profiles show a strong similarity in the M37/M38 polarity attributes found both in the magnetostratigraphic and marine magnetic records, implying that rapid magnetic reversals were occurring at that time. The average reversal

Satellite Remote Sensing in Seismology. A Review

Directory of Open Access Journals (Sweden)

Andrew A. Tronin

2009-12-01

Full Text Available A wide range of satellite methods is applied now in seismology. The first applications of satellite data for earthquake exploration were initiated in the ‘70s, when active faults were mapped on satellite images. It was a pure and simple extrapolation of airphoto geological interpretation methods into space. The modern embodiment of this method is alignment analysis. Time series of alignments on the Earth's surface are investigated before and after the earthquake. A further application of satellite data in seismology is related with geophysical methods. Electromagnetic methods have about the same long history of application for seismology. Stable statistical estimations of ionosphere-lithosphere relation were obtained based on satellite ionozonds. The most successful current project "DEMETER" shows impressive results. Satellite thermal infra-red data were applied for earthquake research in the next step. Numerous results have confirmed previous observations of thermal anomalies on the Earth's surface prior to earthquakes. A modern trend is the application of the outgoing long-wave radiation for earthquake research. In ‘80s a new technology—satellite radar interferometry—opened a new page. Spectacular pictures of co-seismic deformations were presented. Current researches are moving in the direction of pre-earthquake deformation detection. GPS technology is also widely used in seismology both for ionosphere sounding and for ground movement detection. Satellite gravimetry has demonstrated its first very impressive results on the example of the catastrophic Indonesian earthquake in 2004. Relatively new applications of remote sensing for seismology as atmospheric sounding, gas observations, and cloud analysis are considered as possible candidates for applications.

Modeling and control of a gravity gradient stabilised satellite

Directory of Open Access Journals (Sweden)

Aage Skullestad

1999-01-01

Full Text Available This paper describes attitude control, i.e., 3-axes stabilisation and pointing, of a proposed Norwegian small gravity gradient stabilized satellite to be launched into low earth orbit. Generally, a gravity gradient stabilised system has limited stability and pointing capabilities, and wheels and/or magnetic coils are added in order to improve the attitude control. The best attitude accuracy is achieved using wheels, which can give accuracies down to less than one degree, but wheels increase the complexity and cost of the satellite. Magnetic coils allow cheaper satellites, and are an attractive solution to small, inexpensive satellites in low earth orbits and may provide an attitude control accuracy of a few degrees. Scientific measurements often require accurate attitude control in one or two axes only. Combining wheel and coil control may, in these cases, provide the best solutions. The simulation results are based on a linearised mathematical model of the satellite.

Identifying Pre-Seismic TIR Anomalies: A Long Term (2004-2015) Of RST Analysis Over Turkish Area

Science.gov (United States)

Perrone, A.; Tramutoli, V.; Corrado, A.; Filizzola, C.; Genzano, N.; Lisi, M.; Paciello, R.; Pergola, N.

2017-12-01

Since eighties, fluctuations of Earth's thermally emitted radiation, measured by satellite sensors operating in the thermal infrared (TIR) spectral range (i.e. 10-12 µm), have been associated with the complex process of preparation of earthquakes. Several theories have been proposed to explain their origin and their space-time evolution. In this paper, the Earth's emitted radiation in the Thermal Infra-Red spectral region is considered for its possible correlation with M≥4 earthquakes occurred in Turkey in between 2004 and 2015. Robust Satellite Technique (RST) and RETIRA (Robust Estimator of TIR Anomalies) index were used to preliminarily define, and then to identify, Significant Sequences of TIR Anomalies (SSTAs) in the period 1 April 2004- 31 October 2015 (12 years) of daily TIR images acquired by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board the Meteosat Second Generation (MSG) satellite. The performed analysis shows that more than 67% of all identified SSTAs occur in the pre-fixed space-time window around the occurrence time and location of earthquakes (M≥4), with a false positive rate smaller than 33%. Moreover, Molchan error diagram analysis gave a clear indication of non-casualty of such a correlation, in comparison with the random guess function. Notwithstanding the huge amount of missed events due to frequent space/time data gaps produced by the presence of clouds over the scene the achieved results, and particularly the low rate of false positives registered on a so long testing period, seems sufficient (at least) to qualify TIR anomalies (identified by RST approach and RETIRA index) among the parameters to be considered in the framework of a multi-parametric approach to time-Dependent Assessment of Seismic Hazard (t-DASH).

New gravity anomaly map of Taiwan and its surrounding regions with some tectonic interpretations

Science.gov (United States)

Doo, Wen-Bin; Lo, Chung-Liang; Hsu, Shu-Kun; Tsai, Ching-Hui; Huang, Yin-Sheng; Wang, Hsueh-Fen; Chiu, Shye-Donq; Ma, Yu-Fang; Liang, Chin-Wei

2018-04-01

In this study, we compiled recently collected (from 2005 to 2015) and previously reported (published and open access) gravity data, including land, shipborne and satellite-derived data, for Taiwan and its surrounding regions. Based on the cross-over error analysis, all data were adjusted; and, new Free-air gravity anomalies were obtained, shedding light on the tectonics of the region. To obtain the Bouguer gravity anomalies, the densities of land terrain and marine sediments were assumed to be 2.53 and 1.80 g/cm3, respectively. The updated gravity dataset was gridded with a spacing of one arc-minute. Several previously unnoticed gravity features are revealed by the new maps and can be used in a broad range of applications: (1) An isolated gravity high is located between the Shoushan and the Kaoping Canyon off southwest Taiwan. (2) Along the Luzon Arc, both Free-air and Bouguer gravity anomaly maps reveal a significant gravity discontinuity feature at the latitude of 21°20‧N. (3) In the southwestern Okinawa Trough, the NE-SW trending cross-back-arc volcanic trail (CBVT) marks the low-high gravity anomaly (both Free-air and Bouguer) boundary.

Minimization of nanosatellite low frequency magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Belyayev, S. M., E-mail: belyayev@isr.lviv.ua [Lviv Centre of Institute for Space Research, Lviv 79060 (Ukraine); Royal Institute of Technology, Stockholm 11428 (Sweden); Dudkin, F. L. [Lviv Centre of Institute for Space Research, Lviv 79060 (Ukraine)

2016-03-15

Small weight and dimensions of the micro- and nanosatellites constrain researchers to place electromagnetic sensors on short booms or on the satellite body. Therefore the electromagnetic cleanliness of such satellites becomes a central question. This paper describes the theoretical base and practical techniques for determining the parameters of DC and very low frequency magnetic interference sources. One of such sources is satellite magnetization, the reduction of which improves the accuracy and stability of the attitude control system. We present design solutions for magnetically clean spacecraft, testing equipment, and technology for magnetic moment measurements, which are more convenient, efficient, and accurate than the conventional ones.

Lunar magnetism

Science.gov (United States)

Hood, L. L.; Sonett, C. P.; Srnka, L. J.

1984-01-01

Aspects of lunar paleomagnetic and electromagnetic sounding results which appear inconsistent with the hypothesis that an ancient core dynamo was the dominant source of the observed crustal magnetism are discussed. Evidence is summarized involving a correlation between observed magnetic anomalies and ejecta blankets from impact events which indicates the possible importance of local mechanisms involving meteoroid impact processes in generating strong magnetic fields at the lunar surface. A reply is given to the latter argument which also presents recent evidence of a lunar iron core.

Experimental evidence for lamellar magnetism in hemo-ilmenite by polarized neutron scattering

DEFF Research Database (Denmark)

Brok, Erik; Sales, Morten; Lefmann, Kim

2014-01-01

Large local anomalies in the Earth's magnetic field have been observed in Norway, Sweden, and Canada. These anomalies have been attributed to the unusual magnetic properties of naturally occurring hemo-ilmenite, consisting of a paramagnetic ilmenite host (alpha-Fe2O3-bearing FeTiO3) with exsoluti...

Magnetic prospecting in Kaibuki-yama ancient tomb; Kaibukiyama kofun ni okeru zenjiryoku sokutei

Energy Technology Data Exchange (ETDEWEB)

Nishitani, T [Akita University, Akita (Japan). Mining College

1996-10-01

Kaibuki-yama ancient tomb located in Kumeda, Kishiwada City, Osaka has a square shape in the front and an orbicular shape in the rear, which was considered to be made in the 4th century. This ancient tomb has a total length about 135 m, a diameter of orbicular shape in the rear about 82 m, and a height about 9 m, which is a symbolical existence of the Kumeda ancient tombs. Stone chamber and stone casket made of Sanbagawa crystalline schist or rhyolitic-andesitic tuff are expected in this tomb. Magnetic prospecting in this study is accompanied with this survey. A differential type proton magnetometer was used for the measurements, which were conducted using meshes with 1 m edges. A pair of distinct positive and negative magnetic anomalies were observed in the center of orbicular shape in the rear. This coincides with a location of main body buried, which is archaeologically estimated. The magnetic anomaly might be caused by the article buried in the tomb, such as ironware, based on the measurement of magnetic intensity. From the calculated values of magnetic anomaly using a model, the buried article with magnetic anomaly was considered to have a size with length of 1 m, width of 0.1 m, and height of 0.2m. The negative magnetic anomaly could not be explained only by this. It is necessary to consider the other reasons. 8 refs., 8 figs.

Electrical resistivity, heat capacity and magnetic susceptibility anomalies in Ce{sub 1-x}La{sub x}Ir{sub 2}Ge{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Mallik, R; Sampathkumaran, E V; Paulose, P L [Tata Inst. of Fundamental Research, Bombay (India)

1997-02-01

The results of electrical resistivity {rho} (1.4-300 K), heat capacity C and magnetic susceptibility {chi} measurements on the alloys, Ce{sub 1-x}La{sub x}Ir{sub 2}Ge{sub 2}, are reported. The results establish that CeIr{sub 2}Ge{sub 2} is one of the rare Ce compounds with a Kondo coherence temperature as large as 80 K in the trivalent limit of Ce. Apparently, {rho} exhibits non-Fermi liquid behaviour in the low-temperature {rho} data, though there is no corresponding anomaly in the C data. There is a low-temperature tail in {chi} which appears to be intrinsic. (orig.).

Induction studies with satellite data

DEFF Research Database (Denmark)

Olsen, Nils

1999-01-01

The natural variations of the Earth's magnetic field of periods spanning from milliseconds to decades can be used to infer the conductivity-depth profile of the Earth's interior. Satellites provide a good spatial coverage of magnetic measurements, and forthcoming missions will probably allow...... for observations lasting several years, which helps to reduce the statistical error of the estimated response functions. Two methods are used to study the electrical conductivity of the Earth's mantle in the period range from hours to months. In the first, known as the potential method, a spherical harmonic...... days, this difference probably is not caused purely by differences in mantle conductivity (for which one would expect less difference for the longer periods). Further studies with data from recently launched and future satellites are needed....

Detecting geothermal anomalies and evaluating LST geothermal component by combining thermal remote sensing time series and land surface model data

NARCIS (Netherlands)

Romaguera, M.; Vaughan, R. G.; Ettema, J.; Izquierdo-Verdiguier, E.; Hecker, C. A.; van der Meer, F. D.

This paper explores for the first time the possibilities to use two land surface temperature (LST) time series of different origins (geostationary Meteosat Second Generation satellite data and Noah land surface modelling, LSM), to detect geothermal anomalies and extract the geothermal component of

Detecting geothermal anomalies and evaluating LST geothermal component by combining thermal remote sensing time series and land surface model data

NARCIS (Netherlands)

Romaguera, M.; Vaughan, R. G.; Ettema, J.; Izquierdo-Verdiguier, E.; Hecker, C. A.; van der Meer, F. D.

2017-01-01

This paper explores for the first time the possibilities to use two land surface temperature (LST) time series of different origins (geostationary Meteosat Second Generation satellite data and Noah land surface modelling, LSM), to detect geothermal anomalies and extract the geothermal component of

Global gravitational anomalies

International Nuclear Information System (INIS)

Witten, E.

1985-01-01

A general formula for global gauge and gravitational anomalies is derived. It is used to show that the anomaly free supergravity and superstring theories in ten dimensions are all free of global anomalies that might have ruined their consistency. However, it is shown that global anomalies lead to some restrictions on allowed compactifications of these theories. For example, in the case of O(32) superstring theory, it is shown that a global anomaly related to π 7 (O(32)) leads to a Dirac-like quantization condition for the field strength of the antisymmetric tensor field. Related to global anomalies is the question of the number of fermion zero modes in an instanton field. It is argued that the relevant gravitational instantons are exotic spheres. It is shown that the number of fermion zero modes in an instanton field is always even in ten dimensional supergravity. (orig.)

Aeromagnetic anomaly images of Vulcano and Southern Lipari Islands (Aeolian Archipelago, Italy

Directory of Open Access Journals (Sweden)

M. Chiappini

2004-06-01

Full Text Available Newly acquired high-resolution, low-altitude aeromagnetic data over Vulcano Island and Southwestern Lipari in the Southern Tyrrhenian Sea resolve the major volcanic features in the area associated with the past and present activity. The magnetic character changes in amplitude and frequency from south-east to north-west. The Primordial Vulcano, the Lentia Complex, the Piano Caldera units, the Fossa Caldera deposits, and the currently active La Fossa cone and Vulcanello represent the main volcanic phases on Vulcano Island. They show a distinct magnetic anomaly pattern, whereas prior to this survey, no magnetic signatures of these features were found.