Meteor Beliefs Project: ``Year of Meteors''

Science.gov (United States)

McBeath, Alastair; Drobnock, George J.; Gheorghe, Andrei Dorian

2011-10-01

We present a discussion linking ideas from a modern music album by Laura Veirs back to a turbulent time in American history 150 years ago, which inspired poet Walt Whitman to compose his poem "Year of Meteors", and the meteor beliefs of the period around 1859-1860, when collection of facts was giving way to analyses and theoretical explanations in meteor science.

Dust Acoustic Mode Manifestations in Earth's Dusty Ionosphere

International Nuclear Information System (INIS)

Kopnin, S.I.; Popel, S.I.

2005-01-01

Dust acoustic mode manifestations in the dusty ionosphere are studied. The reason for an appearance of the low-frequency radio noises associated with such meteor fluxes as Perseids, Orionids, Leonids, and Gemenids is determined

Meteor observation by the Kyoto meteor radar

International Nuclear Information System (INIS)

Kato, S.; Tsuda, T.

1987-01-01

The Kyoto Meteor Radar is a monostatic coherent pulsed Doppler radar operating on the frequency of 31.57 MH. The system is computer controlled and uses radio interferometry for echo height determination. The antenna, an improvement, can be directed either to the north or the east. The system has been continuously collecting data on winds at meteor heights by radar observation. The meteor echo rate was also measured, the echo rate distribution with height and the daily variation in height integrated echo rate are discussed. Investigations of atmospheric tides are being pursued by cooperative observations. A novel approach to the study of gravity waves was attempted using the meteor radar which is able to detect the horizontal propagation of the waves by observing the changing phase through the region illuminated by the radar

Meteor Beliefs Project: Meteors in the Maori astronomical traditions of New Zealand

Science.gov (United States)

Britton, Tui R.; Hamacher, Duane W.

2014-02-01

We review the literature for perceptions of meteors in the Maori culture of Aotearoa or New Zealand. We examine representations of meteors in religion, story, and ceremony. We find that meteors are sometimes personified as gods or children, or are seen as omens of death and destruction. The stories we found highlight the broad perception of meteors found throughout the Maori culture, and note that some early scholars conflated the terms comet and meteor.

Meteor Beliefs Project: Meteoric references in Ovid's Metamorphoses

Science.gov (United States)

Gheorghe, A. D.; McBeath, A.

2003-10-01

Three sections of Ovid's Metamorphoses are examined, providing further information on meteoric beliefs in ancient Roman times. These include meteoric imagery among the portents associated with the death of Julius Caesar, which we mentioned previously from the works of William Shakespeare (McBeath and Gheorghe, 2003b).

MSFC Stream Model Preliminary Results: Modeling the 1998-2002 Leonid Encounters and the 1993,1994, and 2004 Perseid Encounters

Science.gov (United States)

Moser, D. E.; Cooke, W. J.

2004-01-01

The cometary meteoroid ejection models of Jones (1996) and Crifo (1997) were used to simulate ejection from comets 55P/Tempel-Tuttle during the last 12 revolutions, and the 1862, 1737, and 161 0 apparitions of 1 OSP/Swift-Tuttle. Using cometary ephemerides generated by the JPL HORIZONS Solar System Data and Ephemeris Computation Service, ejection was simulated in 1 hour time steps while the comet was within 2.5 AU of the Sun. Also simulated was ejection occurring at the hour of perihelion passage. An RK4 variable step integrator was then used to integrate meteoroid position and velocity forward in time, accounting for the effects of radiation pressure, Poynting-Robertson drag, and the gravitational forces of the planets, which were computed using JPL's DE406 planetary ephemerides. An impact parameter is computed for each particle approaching the Earth, and the results are compared to observations of the 1998-2002 Leonid showers, and the 1993-1 994 Perseids. A prediction for Earth's encounter with the Perseid stream in 2004 is also presented.

Mesospheric temperature estimation from meteor decay times of weak and strong meteor trails

Science.gov (United States)

Kim, Jeong-Han; Kim, Yong Ha; Jee, Geonhwa; Lee, Changsup

2012-11-01

Neutral temperatures near the mesopause region were estimated from the decay times of the meteor echoes observed by a VHF meteor radar during a period covering 2007 to 2009 at King Sejong Station (62.22°S, 58.78°W), Antarctica. While some previous studies have used all meteor echoes to determine the slope from a height profile of log inverse decay times for temperature estimation, we have divided meteor echoes into weak and strong groups of underdense meteor trails, depending on the strength of estimated relative electron line densities within meteor trails. We found that the slopes from the strong group are inappropriate for temperature estimation because the decay times of strong meteors are considerably scattered, whereas the slopes from the weak group clearly define the variation of decay times with height. We thus utilize the slopes only from the weak group in the altitude region between 86 km and 96 km to estimate mesospheric temperatures. The meteor estimated temperatures show a typical seasonal variation near the mesopause region and the monthly mean temperatures are in good agreement with SABER temperatures within a mean difference of 4.8 K throughout the year. The meteor temperatures, representing typically the region around the altitude of 91 km, are lower on average by 2.1 K than simultaneously measured SATI OH(6-2) rotational temperatures during winter (March-October).

The KUT meteor radar: An educational low cost meteor observation system by radio forward scattering

Science.gov (United States)

Madkour, W.; Yamamoto, M.

2016-01-01

The Kochi University of Technology (KUT) meteor radar is an educational low cost observation system built at Kochi, Japan by successive graduate students since 2004. The system takes advantage of the continuous VHF- band beacon signal emitted from Fukui National College of Technology (FNCT) for scientific usage all over Japan by receiving the forward scattered signals. The system uses the classical forward scattering setup similar to the setup described by the international meteor organization (IMO), gradually developed from the most basic single antenna setup to the multi-site meteor path determination setup. The primary objective is to automate the observation of the meteor parameters continuously to provide amounts of data sufficient for statistical analysis. The developed software system automates the observation of the astronomical meteor parameters such as meteor direction, velocity and trajectory. Also, automated counting of meteor echoes and their durations are used to observe mesospheric ozone concentration by analyzing the duration distribution of different meteor showers. The meteor parameters observed and the methodology used for each are briefly summarized.

New meteor showers – yes or not?

Science.gov (United States)

Koukal, Jakub

2018-01-01

The development of meteor astronomy associated with the development of CCD technology is reflected in a huge increase in databases of meteor orbits. It has never been possible before in the history of meteor astronomy to examine properties of meteors or meteor showers. Existing methods for detecting new meteor showers seem to be inadequate in these circumstances. The spontaneous discovery of new meteor showers leads to ambiguous specifications of new meteor showers. There is a duplication of already discovered meteor showers and a division of existing meteor showers based on their own criteria. The analysis in this article considers some new meteor showers in the IAU MDC database.

Meteor researches at KHNURE

Science.gov (United States)

Kolomiyets, Svitlana V.; Voloshchuk, Yuri I.; Kashcheyev, Boris L.; Slipchenko, Nikolay I.

2005-01-01

The Scientific Educational Center of Radioengineering of the Kharkiv National University of Radioelectronics (KHNURE: ) is one of the oldest radar meteor centers which was founded by B. L. Kashcheyev in 1958. The first automatic meteor radar system in Ukraine “MARS” is connected with our University. There are long-term observational series of meteor rates and orbital data in the Center. Fields of the KHNURE researches are: a structure of meteor showers a determination of meteoroid orbits an influx of cosmic rubbish in the Earth atmosphere search of parental bodies of meteoroids a statistic analysis of measurement results of radiometeors an estimation of errors of meteor radar measurements a search for real hyperbolic orbits and interstellar meteoroids. KHNURE disposes a unique electronic orbital catalogue. This catalogue contains the primary information velocities radiants and orbits of nearly 250000 radiometeoroids with masses from 0.001 to 0.000001 g. The “MARS” registered these data during observations of 1972 1978. From these data 5160 meteor streams are singled out. New classification of streams is made in view of their structure. The study of meteor stream orbits from the KHNURE data bank allow to predict orbits of a big number of undiscovered “dangerous” NEOs.

Medium-Scale Traveling Ionospheric Disturbances (MSTIDs) resulting from Chelyabinsk Meteor Blast

Science.gov (United States)

Sheeks, B. J.; Warren, N.; Coster, A. J.

2013-12-01

A global network of GPS receivers continuously make line-of-sight (LOS) measurements of the total electron content (TEC) of the ionosphere. This TEC measurement data can be analyzed to 'persistently monitor' natural and man-made activity in the atmosphere (such as volcanic eruptions, earthquakes, rocket launches, etc) which propagate into the ionosphere to produce TIDs (Traveling Ionospheric Disturbances). As an example we have analyzed in detail the TIDs resulting from the 15 Feb 2013 Chelyabinsk meteor blast as observed by the Artu GPS receiver site in Arti, Russia close to the event. Seven of the GPS satellite measurements with LOS pierce points within 1000 km of the blast show disturbances. Four of these clearly show VTEC oscillations with ~12 minute periods. The other three show much weaker responses, but their LOS pierce points are far from the blast and their aspects between the geomagnetic field & blast propagation vector are unfavorable (near broadside). By fitting all seven measurements we estimate a propagation speed of ~380 m/s for these medium-scale TIDs. As future 'persistent surveillance' efforts we intend to investigate the observability of man-made activities such as static rocket engine firings in TEC measurements. Analysis of MSTIDs resulting from the Chelyabinsk meteor blast

Determination of the Meteor Limiting Magnitude

Science.gov (United States)

Kingery, A.; Blaauw, R.; Cooke, W. J.

2016-01-01

The limiting meteor magnitude of a meteor camera system will depend on the camera hardware and software, sky conditions, and the location of the meteor radiant. Some of these factors are constants for a given meteor camera system, but many change between meteor shower or sporadic source and on both long and short timescales. Since the limiting meteor magnitude ultimately gets used to calculate the limiting meteor mass for a given data set, it is important to have an understanding of these factors and to monitor how they change throughout the night, as a 0.5 magnitude uncertainty in limiting magnitude translates to a uncertainty in limiting mass by a factor of two.

Meteor showers an annotated catalog

CERN Document Server

Kronk, Gary W

2014-01-01

Meteor showers are among the most spectacular celestial events that may be observed by the naked eye, and have been the object of fascination throughout human history. In “Meteor Showers: An Annotated Catalog,” the interested observer can access detailed research on over 100 annual and periodic meteor streams in order to capitalize on these majestic spectacles. Each meteor shower entry includes details of their discovery, important observations and orbits, and gives a full picture of duration, location in the sky, and expected hourly rates. Armed with a fuller understanding, the amateur observer can better view and appreciate the shower of their choice. The original book, published in 1988, has been updated with over 25 years of research in this new and improved edition. Almost every meteor shower study is expanded, with some original minor showers being dropped while new ones are added. The book also includes breakthroughs in the study of meteor showers, such as accurate predictions of outbursts as well ...

METEOR v1.0 - A usage example; METEOR v1.0 - Un ejemplo de uso

Energy Technology Data Exchange (ETDEWEB)

Palomo, E.

1994-07-01

This script describes a detailed example of the use of the software package METEOR for statistical analysis of meteorological data series. A real spanish meteorological data set is chosen to show the capabilities of METEOR. Output files and resultant plots provided of their interpretations are compiled in three appendixes. The original version of METEOR have been developed by Ph. D.Elena Palomo, CIEMAT-IER, GIASE. It is built by linking programs and routines written in FORTRAN 77 and it adds the graphical capabilities of GNUPLOT. The shape of this toolbox was designed following the criteria of modularity, flexibility and agility criteria. All the input, output and analysis options are structured in three main menus: i) the first is aimed to evaluate the quality of the data set; ii) the second is aimed for pre-processing of the data; and iii) the third is aimed towards the statistical analyses and for creating the graphical outputs. Actually the information about METEOR is constituted by three documents written is spanish: 1) METEOR v1.0: User's guide; 2) METEOR v1.0: A usage example; 3) METEOR v1 .0: Design and structure of the software package. (Author)

Solar influence on meteor rates and atmospheric density variations at meteor heights

International Nuclear Information System (INIS)

Ellyett, C.

1977-01-01

A full analysis of radar-determined meteor rates from New Zealand, involving 3,085,574 meteors recorded over a total of 3 1/2 years, and 12,391,976 meteors recorded by the National Research Council of Canada in 8 1/2 years confirms an inverse relationship between meteor rates and solar activity as measured by sunspot numbers. The relationship, significant at the 1% level, appears in the Canadian annual average when the abnormal 1963 increase is removed, in monthly and 1/3-monthly results for the total Canadian period, and in monthly intervals for 1 year of the New Zealand data. This proven relationship of meteor rates with the solar cycle calls for a significant density gradient change over the solar cycle in the 70- to-120-km height range. Although some definite negative results have been reported, no unambiguous positive results are yet available supporting such a density gradient change. It is possible that density variations due to annual, semiannual, diurnal, and latitudinal changes obscure any 11-year density gradient change occurring at these heights. It is uncertain whether the 1963 increase represents density gradient changes in the meteor ablation region regularly brought about 1-2 years before each sunspot minimum or is a special event due to volcanic dust. The following additional facts have emerged from the present analysis. (1) Within a 1-year period the seasonal rate change of astronomical origin overrides any density gradient change in controlling the meteor rates in one of the two hemispheres. (2) The earth's daily rotation alters rates in phase with probable diurnal density gradient changes. (3) An effect due to D region absorption has been observed in the Canadian data

Meteors, comets, and millennialism.

Science.gov (United States)

McBeath, A.

1999-12-01

An overview of meteoric and cometary activity between circa 250 BC and circa 1600 AD is discussed with especial regard to the inclusion of meteoric imagery in Christian religious texts. Evidence is presented to suggest meteorite images played a leading role in the creation of millennial fears among adherents of the early medieval Church in Europe, which fears still persist into modern times, but which may have their origins in Mesopotamia circa 2200 BC. An extended discussion of meteoric imagery in Christian writings is also presented.

Meteors Without Borders: a global campaign

Science.gov (United States)

Heenatigala, T.

2012-01-01

"Meteors Without Borders" is a global project, organized by Astronomers Without Borders and launched during the Global Astronomy Month in 2010 for the Lyrid meteor shower. The project focused on encouraging amateur astronomy groups to hold public outreach events for major meteor showers, conduct meteor-related classroom activities, photography, poetry and art work. It also uses social-media platforms to connect groups around the world to share their observations and photography, live during the events. At the International Meteor Conference 2011, the progress of the project was presented along with an extended invitation for collaborations for further improvements of the project.

METEOR v1.0 - User's Guide; METEOR v1.0 - Guia de Usuarios

Energy Technology Data Exchange (ETDEWEB)

Palomo, E.

1994-07-01

This script is a User's Guide for the software package METEOR for statistical analysis of meteorological data series. The original version of METEOR have been developed by Ph.D. Elena Palomo, CIEMAT-IER, GIMASE. It is built by linking programs and routines written in FORTRAN 77 and it adds the graphical capabilities of GNUPLOT. The shape of this toolbox was designed following the criteria of modularity, flexibility and agility criteria. All the input, output and analysis options are structured in three main menus: i) the first is aimed to evaluate the quality of the data set; ii) the second is aimed for pre-processing of the data; and iii) the third is aimed towards the statistical analyses and for creating the graphical outputs. Actually the information about METEOR is constituted by three documents written in spanish: 1) METEOR v1.0: User's guide; 2) METEOR v1.0: A usage example; 3) METEOR v1.0: Design and structure of the software package. (Author)

Elemental Abundances in Leonid and Perseid Meteoroids

Czech Academy of Sciences Publication Activity Database

Borovička, Jiří

2005-01-01

Roč. 95, 1-4 (2005), s. 245-253 ISSN 0167-9295. [Meteoroids 2004. London, Ontario, 16.08.2004-20.08.2004] R&D Projects: GA ČR GA205/02/0982 Institutional research plan: CEZ:AV0Z1003909 Keywords : meteors * meteoroids * spectroscopy Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.975, year: 2005

Interferometric Meteor Head Echo Observations using the Southern Argentina Agile Meteor Radar (SAAMER)

Science.gov (United States)

Janches, D.; Hocking, W.; Pifko, S.; Hormaechea, J. L.; Fritts, D. C.; Brunini, C; Michell, R.; Samara, M.

2013-01-01

A radar meteor echo is the radar scattering signature from the free-electrons in a plasma trail generated by entry of extraterrestrial particles into the atmosphere. Three categories of scattering mechanisms exist: specular, nonspecular trails, and head-echoes. Generally, there are two types of radars utilized to detect meteors. Traditional VHF meteor radars (often called all-sky1radars) primarily detect the specular reflection of meteor trails traveling perpendicular to the line of sight of the scattering trail, while High Power and Large Aperture (HPLA) radars efficiently detect meteor head-echoes and, in some cases, non-specular trails. The fact that head-echo measurements can be performed only with HPLA radars limits these studies in several ways. HPLA radars are very sensitive instruments constraining the studies to the lower masses, and these observations cannot be performed continuously because they take place at national observatories with limited allocated observing time. These drawbacks can be addressed by developing head echo observing techniques with modified all-sky meteor radars. In addition, the fact that the simultaneous detection of all different scattering mechanisms can be made with the same instrument, rather than requiring assorted different classes of radars, can help clarify observed differences between the different methodologies. In this study, we demonstrate that such concurrent observations are now possible, enabled by the enhanced design of the Southern Argentina Agile Meteor Radar (SAAMER) deployed at the Estacion Astronomica Rio Grande (EARG) in Tierra del Fuego, Argentina. The results presented here are derived from observations performed over a period of 12 days in August 2011, and include meteoroid dynamical parameter distributions, radiants and estimated masses. Overall, the SAAMER's head echo detections appear to be produced by larger particles than those which have been studied thus far using this technique.

International cooperation and amateur meteor work

Science.gov (United States)

Roggemans, P.

Today, the existing framework for international cooperation among amateur meteor workers offers numerous advantages. However, this is a rather recent situation. Meteor astronomy, although popular among amateurs, was the very last topic within astronomy to benefit from a truly international approach. Anyone attempting long term studies of, for instance, meteor stream structures will be confronted with the systematic lack of usable observations due to the absence of any standards in observing, recording and reporting, any archiving or publishing policy. Visual meteor observations represent the overall majority of amateur efforts, while photographic and radio observing were developed only in recent decades as technological specialties of rather few meteor observing teams.

Super Dual Auroral Radar Network observations of fluctuations in the spectral distribution of near range meteor echoes in the upper mesosphere and lower thermosphere

Directory of Open Access Journals (Sweden)

N. F. Arnold

2001-04-01

Full Text Available The Doppler shifts of meteor echoes measured by the SuperDARN HF radar network have been used in several studies to observe neutral winds in the upper mesosphere and lower thermosphere region. In the absence of accurate height information for individual meteors, it has been necessary to assume a statistical mean meteor layer where the variations in altitude were not correlated to changes in the horizontal winds. Observations of spectral width distribution variations made by the radars allow an independent determination of the systematic error in the height. We have investigated the dependence of this distribution on a number of factors including the radar geometry, diurnal and seasonal cycles, variations in solar UV irradiance and geomagnetic activity. Changes in the altitude of the mean meteor layer observed at different radar ranges provide us with some insight into the structure of the upper mesosphere and the lower thermosphere within which the meteors are being ablated. An examination of the spectral widths, as measured by the CUT-LASS Finland radar, in the days preceding and following a Storm Sudden Commencement in April 1997, illustrates how the spectral properties of the observed region can be affected. The variations in the widths were consistent with model calculations of the changes to the temperature profile over this interval. Further refinements in the determination of the spectral width are outlined for future experiments.Key words. Meterology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; instruments and techniques

Super Dual Auroral Radar Network observations of fluctuations in the spectral distribution of near range meteor echoes in the upper mesosphere and lower thermosphere

Directory of Open Access Journals (Sweden)

N. F. Arnold

Full Text Available The Doppler shifts of meteor echoes measured by the SuperDARN HF radar network have been used in several studies to observe neutral winds in the upper mesosphere and lower thermosphere region. In the absence of accurate height information for individual meteors, it has been necessary to assume a statistical mean meteor layer where the variations in altitude were not correlated to changes in the horizontal winds. Observations of spectral width distribution variations made by the radars allow an independent determination of the systematic error in the height. We have investigated the dependence of this distribution on a number of factors including the radar geometry, diurnal and seasonal cycles, variations in solar UV irradiance and geomagnetic activity. Changes in the altitude of the mean meteor layer observed at different radar ranges provide us with some insight into the structure of the upper mesosphere and the lower thermosphere within which the meteors are being ablated. An examination of the spectral widths, as measured by the CUT-LASS Finland radar, in the days preceding and following a Storm Sudden Commencement in April 1997, illustrates how the spectral properties of the observed region can be affected. The variations in the widths were consistent with model calculations of the changes to the temperature profile over this interval. Further refinements in the determination of the spectral width are outlined for future experiments.

Key words. Meterology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; instruments and techniques

The Composition of the Y2K Meteor

Science.gov (United States)

Coulson, S. G.

During the Leonid meteor shower of November 1999 a very bright meteor train, subsequently called the Y2K meteor, was observed. Analysis of the trajectory of the meteor suggests that it was composed of two distinct materials. The bulk of the meteor was composed of a comet-like material, while a much smaller fraction was of a denser carbonaceous material. A simple model is used to analytically determine the mass of the meteor fragments.

METEOR v1.0 - User's Guide

International Nuclear Information System (INIS)

Palomo, E.

1994-01-01

This script is a User's Guide for the software package METEOR for statistical analysis of meteorological data series. The original version of METEOR have been developed by Ph.D. Elena Palomo, CIEMAT-IER, GIMASE. It is built by linking programs and routines written in FORTRAN 77 and it adds the graphical capabilities of GNUPLOT. The shape of this toolbox was designed following the criteria of modularity, flexibility and agility criteria. All the input, output and analysis options are structured in three main menus: i) the first is aimed to evaluate the quality of the data set; ii) the second is aimed for pre-processing of the data; and iii) the third is aimed towards the statistical analyses and for creating the graphical outputs. Actually the information about METEOR is constituted by three documents written in spanish: 1) METEOR v1.0: User's guide; 2) METEOR v1.0: A usage example; 3) METEOR v1.0: Design and structure of the software package. (Author)

Global variation of meteor trail plasma turbulence

Directory of Open Access Journals (Sweden)

L. P. Dyrud

2011-12-01

Full Text Available We present the first global simulations on the occurrence of meteor trail plasma irregularities. These results seek to answer the following questions: when a meteoroid disintegrates in the atmosphere, will the resulting trail become plasma turbulent? What are the factors influencing the development of turbulence? and how do these trails vary on a global scale? Understanding meteor trail plasma turbulence is important because turbulent meteor trails are visible as non-specular trails to coherent radars. Turbulence also influences the evolution of specular radar meteor trails; this fact is important for the inference of mesospheric temperatures from the trail diffusion rates, and their usage for meteor burst communication. We provide evidence of the significant effect that neutral atmospheric winds and ionospheric plasma density have on the variability of meteor trail evolution and on the observation of non-specular meteor trails. We demonstrate that trails are far less likely to become and remain turbulent in daylight, explaining several observational trends for non-specular and specular meteor trails.

Geomagnetism 4

CERN Document Server

Jacobs, John A

2013-01-01

Geomagnetism, Volume 4 focuses on the processes, methodologies, technologies, and approaches involved in geomagnetism, including electric fields, solar wind plasma, pulsations, and gravity waves.The selection first offers information on solar wind, magnetosphere, and the magnetopause of the Earth. Discussions focus on magnetopause structure and transfer processes, magnetosphere electric fields, geomagnetically trapped radiation, microstructure of the solar wind plasma, and hydro magnetic fluctuations and discontinuities. The text then examines geomagnetic tail, neutral upper atmosphere, and ge

Meteors in Australian Aboriginal Dreamings

Science.gov (United States)

Hamacher, Duane W.; Norris, Ray P.

2010-06-01

We present a comprehensive analysis of Australian Aboriginal accounts of meteors. The data used were taken from anthropological and ethnographic literature describing oral traditions, ceremonies, and Dreamings of 97 Aboriginal groups representing all states of modern Australia. This revealed common themes in the way meteors were viewed between Aboriginal groups, focusing on supernatural events, death, omens, and war. The presence of such themes around Australia was probably due to the unpredictable nature of meteors in an otherwise well-ordered cosmos.

METEOR v1.0 - A usage example

International Nuclear Information System (INIS)

Palomo, E.

1994-01-01

This script describes a detailed example of the use of the software package METEOR for statistical analysis of meteorological data series. A real spanish meteorological data set is chosen to show the capabilities of METEOR. Output files and resultant plots provided of their interpretations are compiled in three appendixes. The original version of METEOR have been developed by Ph. D.Elena Palomo, CIEMAT-IER, GIASE. It is built by linking programs and routines written in FORTRAN 77 and it adds the graphical capabilities of GNUPLOT. The shape of this toolbox was designed following the criteria of modularity, flexibility and agility criteria. All the input, output and analysis options are structured in three main menus: i) the first is aimed to evaluate the quality of the data set; ii) the second is aimed for pre-processing of the data; and iii) the third is aimed towards the statistical analyses and for creating the graphical outputs. Actually the information about METEOR is constituted by three documents written is spanish: 1) METEOR v1.0: User's guide; 2) METEOR v1.0: A usage example; 3) METEOR v1 .0: Design and structure of the software package. (Author)

METEOR v1.0 - Design and structure of the software package; METEOR v1.0 - Estructura y modulos informaticos

Energy Technology Data Exchange (ETDEWEB)

Palomo, E.

1994-07-01

This script describes the structure and the separated modules of the software package METEOR for the statistical analysis of meteorological data series. It contains a systematic description of the subroutines of METEOR and, also, of the required shape for input and output files. The original version of METEOR have been developed by Ph.D. Elena Palomo, CIEMAT-IER, GIMASE. It is built by linking programs and routines written in FORTRAN 77 and it adds thc graphical capabilities of GNUPLOT. The shape of this toolbox was designed following the criteria of modularity, flexibility and agility criteria. All the input, output and analysis options are structured in three main menus: i) the first is aimed to evaluate the quality of the data set; ii) the second is aimed for pre-processing of the data; and iii) the third is aimed towards the statistical analyses and for creating the graphical outputs. Actually the information about METEOR is constituted by three documents written in spanish: 1) METEOR v1.0: User's guide; 2) METEOR v1.0: A usage example; 3) METEOR v 1.0: Design and structure of the software package. (Author)

New radio meteor detecting and logging software

Science.gov (United States)

Kaufmann, Wolfgang

2017-08-01

A new piece of software ``Meteor Logger'' for the radio observation of meteors is described. It analyses an incoming audio stream in the frequency domain to detect a radio meteor signal on the basis of its signature, instead of applying an amplitude threshold. For that reason the distribution of the three frequencies with the highest spectral power are considered over the time (3f method). An auto notch algorithm is developed to prevent the radio meteor signal detection from being jammed by a present interference line. The results of an exemplary logging session are discussed.

Seasonal Variation in Meteor Decay Time Profiles Measured by a Meteor Radar at King Sejong Station (62°S, 58°W), Antarctica

Science.gov (United States)

Kim, Y.; Kim, J.; Lee, C.; Jee, G.

2008-12-01

A VHF meteor radar at King Sejong Station (62°S, 58°W), Antarctica has been detecting echoes from more than 20,000 meteors per day since March 2007. Meteor echoes are decayed typically within seconds as meteor trail plasma spread away or are neutralized. Assuming that diffusion is the only process for decay of meteor echo signals, the atmospheric temperatures and pressures have been inferred from the measured meteor decay times at the peak meteor altitudes around 90 km. In this study, we analyze altitude profiles of meteor decay times in each month, which clearly show a maximum at 80 ~ 85 km. The maximum appears at higher altitude during austral summer than winter. The fast decay of meteor signals below the maximum cannot be explained by atmospheric diffusion which decreases with increasing atmospheric densities. We find that the measured meteor decay time profiles can be fitted with a loss rate profile, in addition to diffusion, with a peak altitude of 55 ~ 73 km and a peak rate of 4 ~ 15 sec- 1. The additional loss of meteor plasma may be due to electron absorption by icy particles in the mesosphere, but the estimated peak altitudes are much lower than the layers of NLC or PME. The estimated peak loss rates seem to be too large to be accounted by absorption by icy or dust particles. We will discuss other processes to explain the fast meteor times and their variation over season.

Problems in the design of multifunction meteor-radar networks

Science.gov (United States)

Nechitailenko, V. A.; Voloshchuk, Iu. I.

The design of meteor-radar networks is examined in connection with the need to conduct experiments on a mass scale in meteor geophysics and astronomy. Attention is given to network architecture features and procedures of communication-path selection in the organization of information transfer, with allowance for the features of the meteor communication link. The meteor link is considered as the main means to ensure traffic in the meteor-radar network.

Goals, technique and equipment of meteor study in Russia

Science.gov (United States)

Kartashova, A.; Bagrov, A. V.; Bolgova, G. T.; Kruchkov, S. V.; Leonov, V. A.; Mazurov, V. A.

2013-09-01

Institute of Astronomy RAS is one of the science institutes in the Russian Federation providing systematic optical meteor observations and supervises several meteor groups in our country. The main tasks of our investigations are dedicated to study meteoroid nature as well as meteoroid streams and meteoroid population in the Solar System. In the XXI century we in Russia carry out the reconstruction of our meteor astronomy due to possibilities of new meteor observation equipment (more powerful than were used before as visual and photographic methods) had made possible to select more interesting goals. First of our task is investigation of meteoroid streams crossing the Earth's orbit, and character of meteoroid distributions along of them. The multi stations meteor monitoring from located in the both hemispheres of the Earth can help in this study. According to the analysis of the evolution of meteor orbits, the compact and long lived meteoroid streams consist mainly from large particles. The observation equipment (cheap TV-cameras) with low limiting magnitude we use for gathering observational data. On the other hand, the observations of weak meteors are needed for new meteor shower indication (or confirmation of known meteor shower). The more effective way to do it is comparison of individual meteor orbits parameters (then calculation of radiants of meteor showers). The observations of space debris (as the meteors with low velocity - less 11.2 km/s) can be taking up within this task. The combination of high sensitive TV-cameras WATEC and super-fast lenses COMPUTAR are widely used for meteor TV-monitoring. The TVsystems for round-year meteor observations are fixed and are permanently oriented to the zenith area (the patrol camera - PatrolCa). The mobile TV-cameras (MobileCa) are used for double station observations (if it is possible) and located not far from main cameras PatrolCa (20-30 km). The mobile TVcameras observe 90% of main PatrolCa cameras FOV at altitudes

MSFC Stream Model Preliminary Results: Modeling Recent Leonid and Perseid Encounters

Science.gov (United States)

Cooke, William J.; Moser, Danielle E.

2004-01-01

The cometary meteoroid ejection model of Jones and Brown (1996b) was used to simulate ejection from comets 55P/Tempel-Tuttle during the last 12 revolutions, and the last 9 apparitions of 109P/Swift-Tuttle. Using cometary ephemerides generated by the Jet Propulsion Laboratory s (JPL) HORIZONS Solar System Data and Ephemeris Computation Service, two independent ejection schemes were simulated. In the first case, ejection was simulated in 1 hour time steps along the comet s orbit while it was within 2.5 AU of the Sun. In the second case, ejection was simulated to occur at the hour the comet reached perihelion. A 4th order variable step-size Runge-Kutta integrator was then used to integrate meteoroid position and velocity forward in time, accounting for the effects of radiation pressure, Poynting-Robertson drag, and the gravitational forces of the planets, which were computed using JPL s DE406 planetary ephemerides. An impact parameter was computed for each particle approaching the Earth to create a flux profile, and the results compared to observations of the 1998 and 1999 Leonid showers, and the 1993 and 2004 Perseids.

Meteoric 10Be in soil profiles - A global meta-analysis

Science.gov (United States)

Graly, Joseph A.; Bierman, Paul R.; Reusser, Lucas J.; Pavich, Milan J.

2010-01-01

In order to assess current understanding of meteoric 10Be dynamics and distribution in terrestrial soils, we assembled a database of all published meteoric 10Be soil depth profiles, including 104 profiles from 27 studies in globally diverse locations, collectively containing 679 individual measurements. This allows for the systematic comparison of meteoric 10Be concentration to other soil characteristics and the comparison of profile depth distributions between geologic settings. Percent clay, 9Be, and dithionite-citrate extracted Al positively correlate to meteoric 10Be in more than half of the soils where they were measured, but the lack of significant correlation in other soils suggests that no one soil factor controls meteoric 10Be distribution with depth. Dithionite-citrate extracted Fe and cation exchange capacity are only weakly correlated to meteoric 10Be. Percent organic carbon and pH are not significantly related to meteoric 10Be concentration when all data are complied.The compilation shows that meteoric 10Be concentration is seldom uniform with depth in a soil profile. In young or rapidly eroding soils, maximum meteoric 10Be concentrations are typically found in the uppermost 20 cm. In older, more slowly eroding soils, the highest meteoric 10Be concentrations are found at depth, usually between 50 and 200 cm. We find that the highest measured meteoric 10Be concentration in a soil profile is an important metric, as both the value and the depth of the maximum meteoric 10Be concentration correlate with the total measured meteoric 10Be inventory of the soil profile.In order to refine the use of meteoric 10Be as an estimator of soil erosion rate, we compare near-surface meteoric 10Be concentrations to total meteoric 10Be soil inventories. These trends are used to calibrate models of meteoric 10Be loss by soil erosion. Erosion rates calculated using this method vary based on the assumed depth and timing of erosional events and on the reference data selected.

A spectral analysis of ablating meteors

Science.gov (United States)

Bloxam, K.; Campbell-Brown, M.

2017-09-01

Meteor ablation features in the spectral lines occurring at 394, 436, 520, and 589 nm were observed using a four-camera spectral system between September and December 2015. In conjunction with this multi-camera system the Canadian Automated Meteor Observatory was used to observe the orbital parameters and fragmentation of these meteors. In total, 95 light curves with complete data in the 520 and 589 nm filters were analyzed; some also had partial or complete data in the 394 nm filter, but no usable data was collected with the 436 nm filter. Of the 95 events, 70 exhibited some degree of differential ablation, and in all except 3 of these 70 events the 589 nm filter started or ended sooner compared with the 520 nm filter, indicating early ablation at the 589 nm wavelength. In the majority of cases the meteor showed evidence of fragmentation regardless of the type of ablation (differential or uniform). A surprising result was the lack of correlation found concerning the KB parameter, linked to meteoroid strength, and differential ablation. In addition, 22 shower-associated meteors were observed; Geminids showed mainly slight differential ablation, while Taurids were more likely to ablate uniformly.

Photoacoustic Sounds from Meteors.

Energy Technology Data Exchange (ETDEWEB)

Spalding, Richard E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tencer, John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sweatt, William C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hogan, Roy E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Boslough, Mark B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Spurny, Pavel [Academy of Sciences of the Czech Republic (ASCR), Prague (Czech Republic)

2015-03-01

High-speed photometric observations of meteor fireballs have shown that they often produce high-amplitude light oscillations with frequency components in the kHz range, and in some cases exhibit strong millisecond flares. We built a light source with similar characteristics and illuminated various materials in the laboratory, generating audible sounds. Models suggest that light oscillations and pulses can radiatively heat dielectric materials, which in turn conductively heats the surrounding air on millisecond timescales. The sound waves can be heard if the illuminated material is sufficiently close to the observer’s ears. The mechanism described herein may explain many reports of meteors that appear to be audible while they are concurrently visible in the sky and too far away for sound to have propagated to the observer. This photoacoustic (PA) explanation provides an alternative to electrophonic (EP) sounds hypothesized to arise from electromagnetic coupling of plasma oscillation in the meteor wake to natural antennas in the vicinity of an observer.

Mesospheric Na Variability and Dependence on Geomagnetic and Solar Activity over Arecibo

Science.gov (United States)

Jain, K.; Raizada, S.; Brum, C. G. M.

2017-12-01

The Sodium (Na) resonance lidars located at the Arecibo Observatory offer an excellent opportunity to study the mesosphere/lower thermosphere(MLT) region. Different metals like Fe, Mg, Na, K, Ca and their ions are deposited in the 80 - 120 km altitude range due to the ablation of meteors caused by frictional heating during their entry into the Earth's atmosphere. We present an investigation of the neutral mesospheric Na atom layers over Arecibo. Data on the Na concentrations was collected using a resonance lidar tuned to the of Na wavelength at 589 nm. This wavelength is achieved with a dye-laser pumped by the second harmonic (532 nm) generated from a state-of-the-art commercial Nd:YAG laser. The backscattered signal is received on a 0.8 m (diameter) Cassegrain telescope. The study is based on this data acquired from 1998-2017 and its relation to variations in geomagnetic and solar conditions. We also investigate seasonal and long term trends in the data. The nightly-averaged altitude profiles were modeled as Gaussian curves. From this modeled data we obtain parameters such as the peak, abundance, centroid and width of the main Na layer. Preliminary results show that the Na abundance is more sensitive to changes in geomagnetic and solar variations as compared to the width and centroid height. The seasonal variation exhibits higher peak densities during the local summer and has a secondary maximum during the winter [as shown in the attached figure]. Our analysis demonstrates a decrease in the peak and the abundance of Na atoms with the increase of solar and geomagnetic activity.

Meteors, meteorites and cosmic dust

International Nuclear Information System (INIS)

Lebedinets, V.N.

1987-01-01

The problem of meteorite origin and meteorite composition is discussed. Nowadays, most scientists suppose that the giant Oort cloud consisting of ice comet nuclei is the sourse of the meteor matter. A principle unity of the matter of meteorites falling to the Earth and cosmic dust is noted as well as that of meteorite bodies evaporating in the atmosphere and bearing meteors and bodies

The California All-sky Meteor Surveillance (CAMS) System

Science.gov (United States)

Gural, P. S.

2011-01-01

A unique next generation multi-camera, multi-site video meteor system is being developed and deployed in California to provide high accuracy orbits of simultaneously captured meteors. Included herein is a description of the goals, concept of operations, hardware, and software development progress. An appendix contains a meteor camera performance trade study made for video systems circa 2010.

IAU Meteor Data Center-the shower database: A status report

Science.gov (United States)

Jopek, Tadeusz Jan; Kaňuchová, Zuzana

2017-09-01

Currently, the meteor shower part of Meteor Data Center database includes: 112 established showers, 563 in the working list, among them 36 have the pro tempore status. The list of shower complexes contains 25 groups, 3 have established status and 1 has the pro tempore status. In the past three years, new meteor showers submitted to the MDC database were detected amongst the meteors observed by CAMS stations (Cameras for Allsky Meteor Surveillance), those included in the EDMOND (European viDeo MeteOr Network Database), those collected by the Japanese SonotaCo Network, recorded in the IMO (International Meteor Organization) database, observed by the Croatian Meteor Network and on the Southern Hemisphere by the SAAMER radar. At the XXIX General Assembly of the IAU in Honolulu, Hawaii in 2015, the names of 18 showers were officially accepted and moved to the list of established ones. Also, one shower already officially named (3/SIA the Southern iota Aquariids) was moved back to the working list of meteor showers. At the XXIX GA IAU the basic shower nomenclature rule was modified, the new formulation predicates ;The general rule is that a meteor shower (and a meteoroid stream) should be named after the constellation that contains the nearest star to the radiant point, using the possessive Latin form;. Over the last three years the MDC database was supplemented with the earlier published original data on meteor showers, which permitted verification of the correctness of the MDC data and extension of bibliographic information. Slowly but surely new database software options are implemented, and software bugs are corrected.

Meteor head echoes - observations and models

Directory of Open Access Journals (Sweden)

A. Pellinen-Wannberg

2005-01-01

Full Text Available Meteor head echoes - instantaneous echoes moving with the velocities of the meteors - have been recorded since 1947. Despite many attempts, this phenomenon did not receive a comprehensive theory for over 4 decades. The High Power and Large Aperture (HPLA features, combined with present signal processing and data storage capabilities of incoherent scatter radars, may give an explanation for the old riddle. The meteoroid passage through the radar beam can be followed with simultaneous spatial-time resolution of about 100m-ms class. The current views of the meteor head echo process will be presented and discussed. These will be related to various EISCAT observations, such as dual-frequency target sizes, altitude distributions and vector velocities.

Processing method and results of meteor shower radar observations

International Nuclear Information System (INIS)

Belkovich, O.I.; Suleimanov, N.I.; Tokhtasjev, V.S.

1987-01-01

Studies of meteor showers permit the solving of some principal problems of meteor astronomy: to obtain the structure of a stream in cross section and along its orbits; to retrace the evolution of particle orbits of the stream taking into account gravitational and nongravitational forces and to discover the orbital elements of its parent body; to find out the total mass of solid particles ejected from the parent body taking into account physical and chemical evolution of meteor bodies; and to use meteor streams as natural probes for investigation of the average characteristics of the meteor complex in the solar system. A simple and effective method of determining the flux density and mass exponent parameter was worked out. This method and its results are discussed

Detection of the Phoenicids meteor shower in 2014

Science.gov (United States)

Sato, Mikiya; Watanabe, Jun-ichi; Tsuchiya, Chie; Moorhead, Althea V.; Moser, Danielle E.; Brown, Peter G.; Cooke, William J.

2017-09-01

An appearance of the Phoenicids meteor shower was predicted in 2014 by using a dust trail simulation of an outburst of 1956. We detected Phoenicids meteors on December 2 through multiple observation methods. The NASA All Sky Fireball Network and the Southern Ontario Meteor Network detected five meteors of Phoenicids via video observation. The Canadian Meteor Orbit Radar (CMOR) found fourteen candidate meteors, eight of which were confirmed as Phoenicids. The observed radiant point is consistent with that of our model predictions. In addition to the above observations, a visual observation was carried out by the Japanese team near the Observatorio del Roque de los Muchachos (ORM) of Instituto de Astrofisica de Canarias (IAC) in La Palma Island. The obtained zenithal hourly rate (ZHR) was 16.4±4.9. The maximum ZHR was roughly estimated to be between 20 and 30, which indicates that the cometary activity of parent object 289P/Blanpain in the early 20th century was only about one fifth or one eighth as high as its activity in the late 18th and early 19th century. Accordingly, it seems to be the case that 289P/Blanpain is gradually transforming from a comet to a dormant object.

Radar meteors range distribution model. I. Theory

Czech Academy of Sciences Publication Activity Database

Pecinová, Drahomíra; Pecina, Petr

2007-01-01

Roč. 37, č. 2 (2007), s. 83-106 ISSN 1335-1842 R&D Projects: GA ČR GA205/03/1405 Institutional research plan: CEZ:AV0Z10030501 Keywords : physics of meteors * radar meteors * range distribution Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

Geomagnetic field of earth

International Nuclear Information System (INIS)

Delipetrev, Marjan; Delipetrev, Blagoj; Panovska, Sanja

2008-01-01

In this paper is introduced the theory of geomagnetic field of the Earth. A homogenous and isotropic sphere is taken for a model of Earth with a bar magnet at its center as a magnetic potential. The understanding of the real origin of geomagnetic field produced from differential rotation of inner core with respect to the outer core of Earth is here presented. Special attention is given to the latest observed data of the established net of geomagnetic repeat stations in the Republic of Macedonia. Finally, the maps of elements of geomagnetic field and the equation for calculation of normal magnetic field of Earth are provided. (Author)

``Hiss, clicks and pops'' - The enigmatic sounds of meteors

Science.gov (United States)

Finnegan, J. A.

2015-04-01

The improbability of sounds heard simultaneously with meteors allows the phenomenon to remain on the margins of scientific interest and research. This is unjustified, since these audibly perceived electric field effects indicate complex, inconsistent and still unresolved electric-magnetic coupling and charge dynamics; interacting between the meteor; the ionosphere and mesosphere; stratosphere; troposphere and the surface of the earth. This paper reviews meteor acoustic effects, presents illustrating reports and hypotheses and includes a summary of similar and additional phenomena observed during the 2013 February 15 asteroid fragment disintegration above the Russian district of Chelyabinsk. An augmenting theory involving near ground, non uniform electric field production of Ozone, as a stimulated geo-physical phenomenon to explain some hissing `meteor sounds' is suggested in section 2.2. Unlike previous theories, electric-magnetic field fluctuation rates are not required to occur in the audio frequency range for this process to acoustically emit hissing and intermittent impulsive sounds; removing the requirements of direct conversion, passive human transduction or excited, localised acoustic `emitters'. Links to the Armagh Observatory All-sky meteor cameras, electrophonic meteor research and full construction plans for an extremely low frequency (ELF) receiver are also included.

Meteor activity from 2001XQ on 2-3 December 2016?

Science.gov (United States)

Roggemans, Paul

2016-04-01

The minor shower 66 Draconid (541 SDD) which was discovered by the Croatian Meteor Network has a mean orbit based on 43 meteors, similar to the orbit of 2001 XD. The asteroid 2001 XD has an orbit typical for Jupiter family comets and therefore may be a dormant comet. The shower activity ranges from November 23 until December 21. All meteor observers are encouraged to pay attention to any possible meteors from this source, although no outburst or any anything spectacular has to be expected.

Crowdsourcing, the great meteor storm of 1833, and the founding of meteor science.

Science.gov (United States)

Littmann, Mark; Suomela, Todd

2014-06-01

Yale science professor Denison Olmsted used crowdsourcing to gather observations from across the United States of the unexpected deluge of meteors on 13 November 1833--more than 72,000/h. He used these observations (and newspaper accounts and correspondence from scientists) to make a commendably accurate interpretation of the meteor storm, overturning 2100 years of erroneous teachings about shooting stars and establishing meteor science as a new branch of astronomy. Olmsted's success was substantially based on his use of newspapers and their practice of news pooling to solicit observations from throughout the country by lay and expert observers professionally unaffiliated with Yale College and him. In today's parlance, Olmsted was a remarkably successful early practitioner of scientific crowdsourcing, also known as citizen science. He may have been the first to use mass media for crowdsourcing in science. He pioneered many of the citizen-science crowdsourcing practices that are still in use today: an open call for citizen participation, a clearly defined task, a large geographical distribution for gathering data and a rapid response to opportunistic events. Olmsted's achievement is not just that he used crowdsourcing in 1833 but that crowdsourcing helped him to advance science significantly. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comet P/Machholtz and the Quadrantid meteor stream

International Nuclear Information System (INIS)

Mcintosh, B.A.

1990-01-01

Attention is drawn to the suggestive similarities between the calculated perturbation behavior of Comet P/Machholtz 1986 VIII, on the one hand, and on the other those of the Quadrantid, Delta Aquarid, and Arietid meteor streams. There appears to be adequate evidence for the formation by the Comets P/Machholtz and 1491-I, together with the three meteor streams, of a related complex controlled by Jupiter's gravitational perturbations; there is no comparably compelling information, however, bearing on the questions of parent-offspring or sibling relationships among these comets and meteor streams. 13 refs

Linear feature detection algorithm for astronomical surveys - II. Defocusing effects on meteor tracks

Science.gov (United States)

Bektešević, Dino; Vinković, Dejan; Rasmussen, Andrew; Ivezić, Željko

2018-03-01

Given the current limited knowledge of meteor plasma micro-physics and its interaction with the surrounding atmosphere and ionosphere, meteors are a highly interesting observational target for high-resolution wide-field astronomical surveys. Such surveys are capable of resolving the physical size of meteor plasma heads, but they produce large volumes of images that need to be automatically inspected for possible existence of long linear features produced by meteors. Here, we show how big aperture sky survey telescopes detect meteors as defocused tracks with a central brightness depression. We derive an analytic expression for a defocused point source meteor track and use it to calculate brightness profiles of meteors modelled as uniform brightness discs. We apply our modelling to meteor images as seen by the Sloan Digital Sky Survey and Large Synoptic Survey Telescope telescopes. The expression is validated by Monte Carlo ray-tracing simulations of photons travelling through the atmosphere and the Large Synoptic Survey Telescope telescope optics. We show that estimates of the meteor distance and size can be extracted from the measured full width at half-maximum and the strength of the central dip in the observed brightness profile. However, this extraction becomes difficult when the defocused meteor track is distorted by the atmospheric seeing or contaminated by a long-lasting glowing meteor trail. The full width at half-maximum of satellite tracks is distinctly narrower than meteor values, which enables removal of a possible confusion between satellites and meteors.

A test of the comet hypothesis of the Tunguska Meteor Fall - Nature of the meteor 'thermal' explosion paradox

Science.gov (United States)

Liu, V. C.

1978-01-01

The hypothesis that a comet was responsible for the Tunguska Meteor Fall is rejected because the hypothesis does not seem to account for the intense terminal spherical shock. A porous meteoroid model is proposed, and an analysis indicates that an entity of this type might produce an aerodynamic heat flux large enough to account for the terminal meteor explosion. It is suggested that the presence of olivine and of highly irregular macrostructure in meteors might indicate the presence of some porosity. For a highly porous meteoroid, it is postulated that during entry into the atmosphere the aerodynamic heat transfer at its external or pore walls would become so intensified as to cause either complete ablation with popping or a solid-liquid-vapor phase transition accompanied by an explosion.

Geomagnetic Principal Magnetic Storms

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The abbreviations used for observatory names are as follows: GEOMAGNETIC OBSERVATORIES Code Station Geomagnetic Latitude ABG Alibag AMS Martin de Vivie. These data...

Geomagnetic Observations for Main Field Studies

DEFF Research Database (Denmark)

Matzka, Jürgen; Chulliat, A.; Mandea, M.

2010-01-01

Direct measurements of the geomagnetic field have been made for more than 400 years, beginning with individual determinations of the angle between geographic and magnetic North. This was followed by the start of continuous time series of full vector measurements at geomagnetic observatories...... and the beginning of geomagnetic repeat stations surveys in the 19th century. In the second half of the 20th century, true global coverage with geomagnetic field measurements was accomplished by magnetometer payloads on low-Earth-orbiting satellites. This article describes the procedures and instruments...... for magnetic field measurements on ground and in space and covers geomagnetic observatories, repeat stations, automatic observatories, satellites and historic observations. Special emphasis is laid on the global network of geomagnetic observatories....

Radar meteors range distribution model. IV. Ionization coefficient

Czech Academy of Sciences Publication Activity Database

Pecinová, Drahomíra; Pecina, Petr

2008-01-01

Roč. 38, č. 1 (2008), s. 12-20 ISSN 1335-1842 R&D Projects: GA ČR GA205/03/1405 Institutional research plan: CEZ:AV0Z10030501 Keywords : physics of meteors * radar meteors * range distribution Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

Detection and Characterisation of Meteors as a Big Data Citizen Science project

Science.gov (United States)

Gritsevich, M.

2017-12-01

Out of a total around 50,000 meteorites currently known to science, the atmospheric passage was recorded instrumentally in only 30 cases with the potential to derive their atmospheric trajectories and pre-impact heliocentric orbits. Similarly, while the observations of meteors, add thousands of new entries per month to existing databases, it is extremely rare they lead to meteorite recovery. Meteor studies thus represent an excellent example of the Big Data citizen science project, where progress in the field largely depends on the prompt identification and characterisation of meteor events as well as on extensive and valuable contributions by amateur observers. Over the last couple of decades technological advancements in observational techniques have yielded drastic improvements in the quality, quantity and diversity of meteor data, while even more ambitious instruments are about to become operational. This empowers meteor science to boost its experimental and theoretical horizons and seek more advanced scientific goals. We review some of the developments that push meteor science into the Big Data era that requires more complex methodological approaches through interdisciplinary collaborations with other branches of physics and computer science. We argue that meteor science should become an integral part of large surveys in astronomy, aeronomy and space physics, and tackle the complexity of micro-physics of meteor plasma and its interaction with the atmosphere. The recent increased interest in meteor science triggered by the Chelyabinsk fireball helps in building the case for technologically and logistically more ambitious meteor projects. This requires developing new methodological approaches in meteor research, with Big Data science and close collaboration between citizen science, geoscience and astronomy as critical elements. We discuss possibilities for improvements and promote an opportunity for collaboration in meteor science within the currently

A Numerical Model to Assess Soil Fluxes from Meteoric 10Be Data

Science.gov (United States)

Campforts, B.; Govers, G.; Vanacker, V.; Vanderborght, J.; Smolders, E.; Baken, S.

2015-12-01

Meteoric 10Be may be mobile in the soil system. The latter hampers a direct translation of meteoric 10Be inventories into spatial variations in erosion and deposition rates. Here, we present a spatially explicit 2D model that allows us to simulate the behaviour of meteoric 10Be in the soil system. The Be2D model is then used to analyse the potential impact of human-accelerated soil fluxes on meteoric 10Be inventories. The model consists of two parts. A first component deals with advective and diffusive mobility of meteoric 10Be within the soil profile including particle migration, chemical leaching and bioturbation, whereas a second component describes lateral soil (and meteoric 10Be) fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering and lateral soil fluxes from creep, water and tillage erosion. Model simulations show that meteoric 10Be inventories can indeed be related to erosion and deposition, across a wide range of geomorphological and pedological settings. However, quantification of the effects of vertical mobility is essential for a correct interpretation of the observed spatial patterns in 10Be data. Moreover, our simulations suggest that meteoric 10Be can be used as a tracer to unravel human impact on soil fluxes when soils have a high retention capacity for meteoric meteoric 10Be. Application of the Be2D model to existing data sets shows that model parameters can reliably be constrained, resulting in a good agreement between simulated and observed meteoric 10Be concentrations and inventories. This confirms the suitability of the Be2D model as a robust tool to underpin quantitative interpretations of spatial variability in meteoric 10Be data for eroding landscapes.

Study about geomagnetic variations from data recorded at Surlari Geomagnetic Observatory

Science.gov (United States)

Asimopolos, Laurentiu; Asimopolos, Natalia-Silvia; Sandulescu, Agata Monica; Niculici, Eugen

2013-04-01

This paper presents statistical and spectral analysis of data from Surlari Geomagnetic Observatory that contributing to study of geomagnetic variations. Thus were highlighted, for long series of records over several solar cycles, periodicities of 22 years and 11 years. Following the same procedures for medium recording series (multi-annual) have highlighted annual, seasonal and monthly periodicities. For shorter data series, we highlighted diurnal, semidiurnal, 8 hours and even lower periodicities. For very short series with a high sample rate and for few magnetotellurics records, we highlight different types of pulsations (Pc2 - Pc5 and Pi 2). Geomagnetic signals are the convolution product of the atomic stationary signals mono-frequential of different amplitudes associated to phenomena with a very broad band of periodicities and nondeterministic signals associated with geomagnetic disturbances and non-periodic phenomena. Among analysis processes used for discrete series of geomagnetic data with different lengths and sampling rates, can conclude the following: Moving average works as a low pass filter in frequency or high pass in time. By eliminating high frequency components (depending on mobile window size used) can be studied preferential periodicities greater than a given value. Signal linearization (using least squares) provides information on linear trend of the entire series analyzed. Thus, for the very long data series (several decades) we extracted the secular variation slope for each geomagnetic component, separately. The numeric derivative of signal versus time proved to be a very reliable indicator for geomagnetic disturbed periods. Thus, the derivative value may be increased by several orders of magnitude during periods of agitation in comparisons to calm periods. The correlation factor shows significant increases when between two time series a causal relationship exists. Variation of the correlation factor, calculated for a mobile window containing k

Mesospheric sodium over Gadanki during Geminid meteor shower 2007

Science.gov (United States)

Lokanadham, B.; Rakesh Chandra, N.; Bhaskara Rao, S. Vijaya; Raghunath, K.; Yellaiah, G.

Resonance LIDAR system at Gadanki has been used for observing the mesospheric sodium during the night of 12-13 Dec 2007 when the peak activity of Geminid meteor shower occurred. Geminid meteor shower is observed along with the co-located MST radar in the altitude range 80-110 km. Sodium density profiles have been obtained with a vertical resolution of 300 m and a temporal resolution of 120 s with sodium resonance scattering LIDAR system. The sodium layers were found to exist in the altitude range 90-100 km. The enhanced Geminid meteor rates were recorded with the co-located MST radar in the same altitude range. The sodium concentration in the atmospheric altitude of ~93 km is estimated to be 2000 per cc where the meteoric concentration of Geminid is maximum and reduced to around 800 on the non activity of Geminid. These observations showed that the sodium levels in the E-region are found to be increasing during meteor shower nights at least by a factor of two.

Meteor Beliefs Project: some meteoric imagery in the works of William Shakespeare

Science.gov (United States)

McBeath, A.; Gheorghe, A. D.

2003-08-01

Passages from three of William Shakespeare's plays are presented, illustrating some of the beliefs in meteors in 16th-17th century England. They also reflect earlier beliefs and information which it is known Shakespeare drew on in constructing his works.

Advances in Meteoroid and Meteor Science

CERN Document Server

Trigo-Rodríguez, J. M; Llorca, J; Janches, D

2008-01-01

This volume is a compilation of articles that summarize the most recent results in meteor, meteoroid and related fields presented at the Meteoroids 2007 conference held at the impressive CosmoCaixa Science Museum in Barcelona, Spain. The conference took place between the 11th and the 15th of June and was organized by the Institute of Space Sciences (Consejo Superior de Investigaciones Científicas, CSIC) and the Institut d'Estudis Espacials de Catalunya (IEEC). Researchers in meteor science and supporting fields representing more than 20 countries participated at this international conference. The papers contained in this volume underwent the rigorous refereeing process, and they are good examples of the continuous progress being made in this research field. Technological advances in meteor and metoroid detection, the ever-increasing sophistication of computer modeling, and the proliferation of autonomous monitoring stations continue to create new niches for exciting research on meteoroids and their parent bo...

Geomagnetic field, global pattern

OpenAIRE

Macmillan, Susan

2011-01-01

The geomagnetic field is generated in the fluid outer core region of the Earth by electrical currents flowing in the slowly moving molten iron. In addition to sources in the Earth’s core, the geomagnetic field observable on the Earth’s surface has sources in the crust and in the ionosphere and magnetosphere. The signal from the core dominates, accounting for over 95% of the field at the Earth’s surface. The geomagnetic field varies on a range of scales, both temporal and spatial; the...

METEOR v1.0 - Design and structure of the software package

International Nuclear Information System (INIS)

Palomo, E.

1994-01-01

This script describes the structure and the separated modules of the software package METEOR for the statistical analysis of meteorological data series. It contains a systematic description of the subroutines of METEOR and, also, of the required shape for input and output files. The original version of METEOR have been developed by Ph.D. Elena Palomo, CIEMAT-IER, GIMASE. It is built by linking programs and routines written in FORTRAN 77 and it adds thc graphical capabilities of GNUPLOT. The shape of this toolbox was designed following the criteria of modularity, flexibility and agility criteria. All the input, output and analysis options are structured in three main menus: i) the first is aimed to evaluate the quality of the data set; ii) the second is aimed for pre-processing of the data; and iii) the third is aimed towards the statistical analyses and for creating the graphical outputs. Actually the information about METEOR is constituted by three documents written in spanish: 1) METEOR v1.0: User's guide; 2) METEOR v1.0: A usage example; 3) METEOR v 1.0: Design and structure of the software package. (Author)

The effect of recombination and attachment on meteor radar diffusion coefficient profiles

Science.gov (United States)

Lee, C. S.; Younger, J. P.; Reid, I. M.; Kim, Y. H.; Kim, J.-H.

2013-04-01

Estimates of the ambipolar diffusion coefficient producedusing meteor radar echo decay times display an increasing trend below 80-85 km, which is inconsistent with a diffusion-only theory of the evolution of meteor trails. Data from the 33 MHz meteor radar at King Sejong Station, Antarctica, have been compared with observations from the Aura Earth Observing System Microwave Limb Sounder satellite instrument. It has been found that the height at which the diffusion coefficient gradient reverses follows the height of a constant neutral atmospheric density surface. Numerical simulations of meteor trail diffusion including dissociative recombination with atmospheric ions and three-body attachment of free electrons to neutral molecules indicate that three-body attachment is responsible for the distortion of meteor radar diffusion coefficient profiles at heights below 90 km, including the gradient reversal below 80-85 km. Further investigation has revealed that meteor trails with low initial electron line density produce decay times more consistent with a diffusion-only model of meteor trail evolution.

Physics-Based Modeling of Meteor Entry and Breakup

Science.gov (United States)

Prabhu, Dinesh K.; Agrawal, Parul; Allen, Gary A., Jr.; Bauschlicher, Charles W., Jr.; Brandis, Aaron M.; Chen, Yih-Kang; Jaffe, Richard L.; Palmer, Grant E.; Saunders, David A.; Stern, Eric C.;

The EISCAT meteor code

Directory of Open Access Journals (Sweden)

G. Wannberg

2008-08-01

Full Text Available The EISCAT UHF system has the unique capability to determine meteor vector velocities from the head echo Doppler shifts measured at the three sites. Since even meteors spending a very short time in the common volume produce analysable events, the technique lends itself ideally to mapping the orbits of meteors arriving from arbitrary directions over most of the upper hemisphere.

A radar mode optimised for this application was developed in 2001/2002. A specially selected low-sidelobe 32-bit pseudo-random binary sequence is used to binary phase shift key (BPSK the transmitted carrier. The baud-length is 2.4 μs and the receiver bandwidth is 1.6 MHz to accommodate both the resulting modulation bandwidth and the target Doppler shift. Sampling is at 0.6 μs, corresponding to 90-m range resolution. Target range and Doppler velocity are extracted from the raw data in a multi-step matched-filter procedure. For strong (SNR>5 events the Doppler velocity standard deviation is 100–150 m/s. The effective range resolution is about 30 m, allowing very accurate time-of-flight velocity estimates. On average, Doppler and time-of-flight (TOF velocities agree to within about one part in 10³. Two or more targets simultaneously present in the beam can be resolved down to a range separation <300 m as long as their Doppler shifts differ by more than a few km/s.

The EISCAT meteor code

Directory of Open Access Journals (Sweden)

G. Wannberg

2008-08-01

Full Text Available The EISCAT UHF system has the unique capability to determine meteor vector velocities from the head echo Doppler shifts measured at the three sites. Since even meteors spending a very short time in the common volume produce analysable events, the technique lends itself ideally to mapping the orbits of meteors arriving from arbitrary directions over most of the upper hemisphere. A radar mode optimised for this application was developed in 2001/2002. A specially selected low-sidelobe 32-bit pseudo-random binary sequence is used to binary phase shift key (BPSK the transmitted carrier. The baud-length is 2.4 μs and the receiver bandwidth is 1.6 MHz to accommodate both the resulting modulation bandwidth and the target Doppler shift. Sampling is at 0.6 μs, corresponding to 90-m range resolution. Target range and Doppler velocity are extracted from the raw data in a multi-step matched-filter procedure. For strong (SNR>5 events the Doppler velocity standard deviation is 100–150 m/s. The effective range resolution is about 30 m, allowing very accurate time-of-flight velocity estimates. On average, Doppler and time-of-flight (TOF velocities agree to within about one part in 103. Two or more targets simultaneously present in the beam can be resolved down to a range separation <300 m as long as their Doppler shifts differ by more than a few km/s.

Geomagnetic storms

International Nuclear Information System (INIS)

McNamara, A.G.

1980-01-01

Disturbances due to geomagnetic storms can affect the functioning of communications satellites and of power lines and other long conductors. Two general classes of geomagnetic activity can be distinguished: ionospheric current flow (the auroral electrojet), and magnetospheric compression. Super magnetic storms, such as the one of August 1972, can occur at any time and average about 17 occurrences per century. Electrical transmission systems can be made more tolerant of such events at a price, but the most effective way to minimize damage is by better operator training coupled with effective early warning systems. (LL)

CONTENUTO DI URANIO E TORIO NELLE METEORITI

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M. SANTANGELO

1955-06-01

Full Text Available Molti ricercatori in questi ultimi anni si sono interessati al problema
della composizione delle meteoriti; dai risultati sperimentali si
è cercato trarre elementi circa la genesi di questi materiali, questione
ancora aperta, ed avere informazioni sui processi chimici e termodinamici
cui le meteoriti furono soggette prima della loro caduta sulla
terra.
Uno degli aspetti del problema è quello dell'abbondanza percentuale
degli elementi chimici e della loro composizione isotopica nella
materia meteorica dei diversi tipi : ciò perché esso è connesso con
quello piii generale dell'origine e distribuzione degli elementi nel cosmo
e nella terra, nonché con quello dell'età delle meteoriti (l .
In un recente lavoro Urey e collaboratori (-, esaminando un gran
numero di analisi chimiche effettuate su questi materiali, sono pervenuti
alla formulazione di alcuni criteri di classificazione in base alla
percentuale dei componenti più abbondanti ed alla presenza o meno
di disomogeneità strutturali nella massa fondamentale. Fra gli elementi
meno abbondanti presentano particolare interesse quelli delle due famiglie
radioattive naturali Torio e Uranio; le loro concentrazioni sono
state determinate per alcune meteoriti siliciche (stonv ineteorites e
per qualcuna ferrica (iron meteorites

On polar daily geomagnetic variation

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Paola De Michelis

2015-11-01

Full Text Available The aim of this work is to investigate the nature of the daily magnetic field perturbations produced by ionospheric and magnetospheric currents at high latitudes. We analyse the hourly means of the X and Y geomagnetic field components recorded by a meridian chain of permanent geomagnetic observatories in the polar region of the Northern Hemisphere during a period of four years (1995-1998 around the solar minimum. We apply a mathematical method, known as natural orthogonal component (NOC, which is capable of characterizing the dominant modes of the geomagnetic field daily variability through a set of empirical orthogonal functions (EOFs. Using the first two modes we reconstruct a two-dimensional equivalent current representation of the ionospheric electric currents, which contribute substantially to the geomagnetic daily variations. The obtained current structures resemble the equivalent current patterns of DP2 and DP1. We characterize these currents by studying their evolution with the geomagnetic activity level and by analysing their dependence on the interplanetary magnetic field. The obtained results support the idea of a coexistence of two main processes during all analysed period although one of them, the directly driven process, represents the dominant component of the geomagnetic daily variation.

American Meteor Society Fireball reporting system and mobile application

Science.gov (United States)

Hankey, M.

2014-07-01

The American Meteor Society (AMS) founded in 1911 pioneered the visual study of meteors and has collected data relating to meteor observations and bright fireballs for over 100 years. In December 2010, the online fireball reporting system was upgraded to an interactive application that utilizes Google Maps and other programmatic methods to pinpoint the observer's location, azimuth and elevation values with a high degree of precision. The AMS has collected 10s of 1000s of witness reports relating to 100s of events each year since the new application was released. Three dimensional triangulation methods that average the data collected from witnesses have been developed that can determine the start and end points of the meteor with an accuracy of web application. Users can file a new report directly on the phone or update the values submitted through a web report. After web users complete their fireball report online, they are prompted to download the app and update their observation with the more precise data provided by the sensors in the mobile device. The mobile app also provides an accurate means for the witness to report the elapsed time of the fireball. To log this value, the user drags the device across the sky where they saw the fireball. This process is designed to require no button click or user interaction to start and stop the time recording. A count down initiates the process and once the user's phone crosses the plane of azimuth for the end point of the fireball the velocity timer automatically stops. Users are asked to log the recording three times in an effort to minimize error. The three values are then averaged into a final score. Once enough witnesses have filed reports, elapsed time data collected from the mobile phone can be used to determine the velocity of the fireball. With the velocity, trajectory solution and RA/DEC the AMS can plot orbital estimates for significant fireball events reported to the society. Our hope is that overtime this

All-sky Meteor Orbit System AMOS and preliminary analysis of three unusual meteor showers

Czech Academy of Sciences Publication Activity Database

Tóth, J.; Kornoš, L.; Zigo, P.; Gajdoš, Š.; Kalmančok, D.; Világi, J.; Šimon, J.; Vereš, P.; Šilha, J.; Buček, M.; Galád, Adrián; Rusňák, P.; Hrábek, P.; Ďuriš, F.; Rudawska, R.

2015-01-01

Roč. 118, December (2015), s. 102-106 ISSN 0032-0633 Institutional support: RVO:67985815 Keywords : meteor * meteorite * meteoroid streams Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.942, year: 2015

Character of meteoric leaks in the salt mines of south Louisiana, U.S.A.

Science.gov (United States)

Kumar, Madhurendu B.

1983-10-01

The brine leaks of salt mines of south Louisiana are of two genetic categories: meteoric and non-meteoric (connate/formation water type), as established essentially on the basis of oxygen- and hydrogen-isotope analyses. This paper highlights the hydrochemical aspects of those mine leaks and develops simple non-isotopic criteria to differentiate the meteoric leaks from the non-meteoric. The meteoric leaks of the salt mines generally occur down to a depth level of 214 m (700 ft.) (below mean sea level) below which the leaks are mostly non-meteoric. The meteoric brine is essentially Na1bCl in type, reflecting the mineralogy of almost pure halite (with ˜ 1-2% anhydrite) of the Gulf (of Mexico) Coast dome salt. The meteoric leaks are distinctly different from the non-meteoric leaks on the log-log plots of chloride concentrations vs. those of Ca 2+, Mg 2+, K +, Sr + and Br -, in all of which the meteoric brines are conspicuously low. This study is potentially useful in the development of a mine or crypt in salt dome(s) under consideration for possible nuclear-waste isolation in the Gulf Coast region.

Improving Photometric Calibration of Meteor Video Camera Systems

Science.gov (United States)

Ehlert, Steven; Kingery, Aaron; Suggs, Robert

2017-01-01

We present the results of new calibration tests performed by the NASA Meteoroid Environment Office (MEO) designed to help quantify and minimize systematic uncertainties in meteor photometry from video camera observations. These systematic uncertainties can be categorized by two main sources: an imperfect understanding of the linearity correction for the MEO's Watec 902H2 Ultimate video cameras and uncertainties in meteor magnitudes arising from transformations between the Watec camera's Sony EX-View HAD bandpass and the bandpasses used to determine reference star magnitudes. To address the first point, we have measured the linearity response of the MEO's standard meteor video cameras using two independent laboratory tests on eight cameras. Our empirically determined linearity correction is critical for performing accurate photometry at low camera intensity levels. With regards to the second point, we have calculated synthetic magnitudes in the EX bandpass for reference stars. These synthetic magnitudes enable direct calculations of the meteor's photometric flux within the camera bandpass without requiring any assumptions of its spectral energy distribution. Systematic uncertainties in the synthetic magnitudes of individual reference stars are estimated at approx. 0.20 mag, and are limited by the available spectral information in the reference catalogs. These two improvements allow for zero-points accurate to 0.05 - 0.10 mag in both filtered and unfiltered camera observations with no evidence for lingering systematics. These improvements are essential to accurately measuring photometric masses of individual meteors and source mass indexes.

Modern Meteor Science An Interdisciplinary View

CERN Document Server

Hawkes, Robert; Brown, Peter

2005-01-01

This volume represents a blend of leading edge research and authoritative reviews in meteor science. It provides a comprehensive view of meteoroid research including the dynamics, sources and distribution of these bodies, and their chemistry and physical processes in the interplanetary medium and the Earth’s atmosphere. Techniques for investigation of meteor phenomena in the book include conventional and large aperture radar systems, spacecraft detection, optical systems, spectral measurements, and laboratory based interplanetary dust particle studies. The book will be of interest to researchers and students in astronomy, astrophysics, cosmochemistry, space engineering and space science. Cover photograph was taken by Masayuki Toda.

Geomagnetic Field During a Reversal

Science.gov (United States)

Heirtzler, J. R.

2003-01-01

It has frequently been suggested that only the geomagnetic dipole, rather than higher order poles, reverse during a geomagnetic field reversal. Under this assumption the geomagnetic field strength has been calculated for the surface of the Earth for various steps of the reversal process. Even without an eminent a reversal of the field, extrapolation of the present secular change (although problematic) shows that the field strength may become zero in some geographic areas within a few hundred years.

VLF Wave Properties During Geomagnetic Storms

Science.gov (United States)

Blancarte, J.; Artemyev, A.; Mozer, F.; Agapitov, O. V.

2017-12-01

Whistler-mode chorus is important for the global dynamics of the inner magnetosphere electron population due to its ability to scatter and accelerate electrons of a wide energy range in the outer radiation belt. The parameters of these VLF emissions change dynamically during geomagnetic storms. Presented is an analysis of four years of Van Allen probe data, utilizing electric and magnetic field in the VLF range focused on the dynamics of chorus wave properties during the enhancement of geomagnetic activity. It is found that VLF emissions respond to geomagnetic storms in more complicated ways than just by affecting the waves' amplitude growth or depletion. Oblique wave amplitudes grow together with parallel waves during periods of intermediate geomagnetic activity, while the occurrence rate of oblique waves decreases during larger geomagnetic storms.

The geomagnetic cutoff rigidities at high latitudes for different solar wind and geomagnetic conditions

International Nuclear Information System (INIS)

Chu, W.; Univ. of Chinese Academy of Sciences, Beijing; Qin, G.

2016-01-01

Studying the access of the cosmic rays (CRs) into the magnetosphere is important to understand the coupling between the magnetosphere and the solar wind. In this paper we numerically studied CRs' magnetospheric access with vertical geomagnetic cutoff rigidities using the method proposed by Smart and Shea (1999). By the study of CRs' vertical geomagnetic cutoff rigidities at high latitudes we obtain the CRs' window (CRW) whose boundary is determined when the vertical geomagnetic cutoff rigidities drop to a value lower than a threshold value. Furthermore, we studied the area of CRWs and found out they are sensitive to different parameters, such as the z component of interplanetary magnetic field (IMF), the solar wind dynamic pressure, AE index, and Dst index. It was found that both the AE index and Dst index have a strong correlation with the area of CRWs during strong geomagnetic storms. However, during the medium storms, only AE index has a strong correlation with the area of CRWs, while Dst index has a much weaker correlation with the area of CRWs. This result on the CRW can be used for forecasting the variation of the cosmic rays during the geomagnetic storms.

Geomagnetic effects caused by rocket exhaust jets

Directory of Open Access Journals (Sweden)

Lipko Yu.V.

2016-09-01

Full Text Available In the space experiment Radar–Progress, we have made 33 series of measurements of geomagnetic variations during ignitions of engines of Progress cargo spacecraft in low Earth orbit. We used magneto-measuring complexes, installed at observatories of the Institute of Solar-Terrestrial Physics of Siberian Branch of the Russian Academy of Sciences, and magnetotelluric equipment of a mobile complex. We assumed that engine running can cause geomagnetic disturbances in field tubes crossed by the spacecraft. When analyzing experimental data, we took into account the following space weather factors: solar wind parameters, total daily mid-latitude geomagnetic activity index Kр, geomagnetic auroral electrojet index AE, global geomagnetic activity. The empirical data we obtained indicate that 18 of the 33 series showed geomagnetic variations with various periods.

September epsilon Perseid cluster as a result of orbital fragmentation

Czech Academy of Sciences Publication Activity Database

Koten, Pavel; Čapek, David; Spurný, Pavel; Vaubaillon, J.; Popek, Martin; Shrbený, Lukáš

2017-01-01

Roč. 600, April (2017), A74/1-A74/5 E-ISSN 1432-0746 R&D Projects: GA ČR GA14-25251S; GA ČR(CZ) GA16-00761S; GA MŠk(CZ) 7AMB16FR025; GA ČR(CZ) GA14-31899S Institutional support: RVO:67985815 ; RVO:68378289 Keywords : meteorites * meteors * meteoroids Subject RIV: BN - Astronomy , Celestial Mechanics, Astrophysics; BN - Astronomy , Celestial Mechanics, Astrophysics (UFA-U) OBOR OECD: Astronomy (including astrophysics,space science); Astronomy (including astrophysics,space science) (UFA-U) Impact factor: 5.014, year: 2016

Solar wind and geomagnetism: toward a standard classification of geomagnetic activity from 1868 to 2009

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J. L. Zerbo

2012-02-01

Full Text Available We examined solar activity with a large series of geomagnetic data from 1868 to 2009. We have revisited the geomagnetic activity classification scheme of Legrand and Simon (1989 and improve their scheme by lowering the minimum Aa index value for shock and recurrent activity from 40 to 20 nT. This improved scheme allows us to clearly classify about 80% of the geomagnetic activity in this time period instead of only 60% for the previous Legrand and Simon classification.

Plasma distributions in meteor head echoes and implications for radar cross section interpretation

Science.gov (United States)

Marshall, Robert A.; Brown, Peter; Close, Sigrid

2017-09-01

The derivation of meteoroid masses from radar measurements requires conversion of the measured radar cross section (RCS) to meteoroid mass. Typically, this conversion passes first through an estimate of the meteor plasma density derived from the RCS. However, the conversion from RCS to meteor plasma density requires assumptions on the radial electron density distribution. We use simultaneous triple-frequency measurements of the RCS for 63 large meteor head echoes to derive estimates of the meteor plasma size and density using five different possible radial electron density distributions. By fitting these distributions to the observed meteor RCS values and estimating the goodness-of-fit, we determine that the best fit to the data is a 1 /r2 plasma distribution, i.e. the electron density decays as 1 /r2 from the center of the meteor plasma. Next, we use the derived plasma distributions to estimate the electron line density q for each meteor using each of the five distributions. We show that depending on the choice of distribution, the line density can vary by a factor of three or more. We thus argue that a best estimate for the radial plasma distribution in a meteor head echo is necessary in order to have any confidence in derived meteoroid masses.

Meteor Beliefs Project: Meteoric imagery associated with the death of John Brown in 1859

Science.gov (United States)

Drobnock, G. J.; McBeath, A.; Gheorghe, A. D.

2009-12-01

An examination is made of metaphorical meteor imagery used in conjunction with the death of American anti-slavery activist John Brown, who was executed in December 1859. Such imagery continues to be used in this regard into the 21st century.

Statistical analysis of geomagnetic field variations during solar eclipses

Science.gov (United States)

Kim, Jung-Hee; Chang, Heon-Young

2018-04-01

We investigate the geomagnetic field variations recorded by INTERMAGNET geomagnetic observatories, which are observed while the Moon's umbra or penumbra passed over them during a solar eclipse event. Though it is generally considered that the geomagnetic field can be modulated during solar eclipses, the effect of the solar eclipse on the observed geomagnetic field has proved subtle to be detected. Instead of exploring the geomagnetic field as a case study, we analyze 207 geomagnetic manifestations acquired by 100 geomagnetic observatories during 39 solar eclipses occurring from 1991 to 2016. As a result of examining a pattern of the geomagnetic field variation on average, we confirm that the effect can be seen over an interval of 180 min centered at the time of maximum eclipse on a site of a geomagnetic observatory. That is, demonstrate an increase in the Y component of the geomagnetic field and decreases in the X component and the total strength of the geomagnetic field. We also find that the effect can be overwhelmed, depending more sensitively on the level of daily geomagnetic events than on the level of solar activity and/or the phase of solar cycle. We have demonstrated it by dividing the whole data set into subsets based on parameters of the geomagnetic field, solar activity, and solar eclipses. It is suggested, therefore, that an evidence of the solar eclipse effect can be revealed even at the solar maximum, as long as the day of the solar eclipse is magnetically quiet.

Limits on radio emission from meteors using the MWA

Science.gov (United States)

Zhang, Xiang; Hancock, Paul; Devillepoix, Hadrien A. R.; Wayth, Randall B.; Beardsley, A.; Crosse, B.; Emrich, D.; Franzen, T. M. O.; Gaensler, B. M.; Horsley, L.; Johnston-Hollitt, M.; Kaplan, D. L.; Kenney, D.; Morales, M. F.; Pallot, D.; Steele, K.; Tingay, S. J.; Trott, C. M.; Walker, M.; Williams, A.; Wu, C.; Ji, Jianghui; Ma, Yuehua

2018-04-01

Recently, low frequency, broadband radio emission has been observed accompanying bright meteors by the Long Wavelength Array (LWA). The broadband spectra between 20 and 60 MHz were captured for several events, while the spectral index (dependence of flux density on frequency, with Sν∝να) was estimated to be -4 ± 1 during the peak of meteor afterglows. Here we present a survey of meteor emission and other transient events using the Murchison Widefield Array (MWA) at 72-103 MHz. In our 322-hour survey, down to a 5σ detection threshold of 3.5 Jy/beam, no transient candidates were identified as intrinsic emission from meteors. We derived an upper limit of -3.7 (95% confidence limit) on the spectral index in our frequency range. We also report detections of other transient events, like reflected FM broadcast signals from small satellites, conclusively demonstrating the ability of the MWA to detect and track space debris on scales as small as 0.1 m in low Earth orbits.

Meteoric Impact and Ion Density Calculation in the Nighttime ...

Indian Academy of Sciences (India)

Bhavin

2013-11-08

Nov 8, 2013 ... Pandya, B. M., and S. A. Haider (2012), Meteor impact perturbation in the lower ionosphere of Mars: MGS observations,. Planet. Space Sci., 63, 105-109, doi: 10.1016/j.pss.2011.09.013. Page 6. Pandya, B. M., and S. A. Haider (2012), Meteor impact perturbation in the lower ionosphere of Mars: MGS ...

Reconstructing the orbit of the Chelyabinsk meteor using satellite observations

DEFF Research Database (Denmark)

Proud, Simon Richard

2013-01-01

The large number of objects in a range of orbits around the Sun means that some will inevitably intersect the Earth, becoming a meteor. These objects are commonly comet fragments or asteroids. To determine the type of a particular meteor requires knowledge of its trajectory and orbital path...... that is typically estimated by using ground-based observations such as images or radar measurements. A lack of data can, however, make this difficult and create large uncertainties in the reconstructed orbit. Here I show a new method for estimating a meteor's trajectory, and hence allowing computation of the orbit...

Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch

Directory of Open Access Journals (Sweden)

Mario Brkić

2013-12-01

Full Text Available After more than half a century, scientific book Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch describes the recent geomagnetic field on Croatian territory. A review of research in the past decade as well as the original solutions makes the book a document of contribution to geodesy and geomagnetism in Croatia.The book’s introduction gives an overview of two centuries of history and the strategic, security, economic and scientific significance of knowing the geomagnetic field on the Croatian territory. All the activities related to the updating of the geomagnetic information, which took place in the last decade, signified a big step toward the countries where geomagnetic survey is a mature scientific and technical discipline, and a scientific contribution to understanding of the nature of the Earth's magnetism.The declination, inclination and total intensity maps (along with the normal annual changes for the epoch 2009.5 are given in the Appendix. The book Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch (ISBN 978-953-293-521-9 is published by the State Geodetic Administration of the Republic of Croatia. Beside editor in chief, M. Brkić, the authors are: E. Vujić, D. Šugar, E. Jungwirth, D. Markovinović, M. Rezo, M. Pavasović, O. Bjelotomić, M. Šljivarić, M. Varga and V. Poslončec-Petrić. The book contains 48 pages and 3 maps, and is published in 200 copies. CIP record is available in digital catalogue of the National and University Library in Zagreb under number 861937.

The First Year of Croatian Meteor Network

Science.gov (United States)

Andreic, Zeljko; Segon, Damir

2010-08-01

The idea and a short history of Croatian Meteor Network (CMN) is described. Based on use of cheap surveillance cameras, standard PC-TV cards and old PCs, the Network allows schools, amateur societies and individuals to participate in photographic meteor patrol program. The network has a strong educational component and many cameras are located at or around teaching facilities. Data obtained by these cameras are collected and processed by the scientific team of the network. Currently 14 cameras are operable, covering a large part of the croatian sky, data gathering is fully functional, and data reduction software is in testing phase.

Development of the mesospheric Na layer at 69° N during the Geminids meteor shower 2010

Directory of Open Access Journals (Sweden)

T. Dunker

2013-01-01

Full Text Available The ECOMA sounding rocket campaign in 2010 was performed to investigate the charge state and number density of meteoric smoke particles during the Geminids meteor shower in December 2010. The ALOMAR Na lidar contributed to the campaign with measurements of sodium number density, temperature and line-of-sight wind between 80 and 110 km altitude over Andøya in northern Norway. This paper investigates a possible connection between the Geminids meteor shower and the mesospheric sodium layer. We compare with data from a meteor radar and from a rocket-borne in situ particle instrument on three days. Our main result is that the sodium column density is smaller during the Geminids meteor shower than the winter average at the same latitude. Moreover, during two of the three years considered, the sodium column density decreased steadily during these three weeks of the year. Both the observed decrease of Na column density by 30% and of meteoric smoke particle column density correlate well with a corresponding decrease of sporadic meteor echoes. We found no correlation between Geminids meteor flux rates and sodium column density, nor between sporadic meteors and Na column density (R = 0.25. In general, we found the Na column density to be at very low values for winter, between 1.8 and 2.6 × 1013 m−2. We detected two meteor trails containing sodium, on 13 December 2010 at 87.1 km and on 19 December 2010 at 84 km. From these meteor trails, we estimate a global meteoric Na flux of 121 kg d−1 and a global total meteoric influx of 20.2 t d−1.

The Egyptian geomagnetic reference field to the Epoch, 2010.0

Directory of Open Access Journals (Sweden)

H.A. Deebes

2017-06-01

The geomagnetic anomaly maps, the normal geomagnetic field maps with their corresponding secular variation maps, the normal geomagnetic field equations of the geomagnetic elements (EGRF and their corresponding secular variations equations, are outlined. The anomalous sites, as discovered from the anomaly maps are, only, mentioned. In addition, a correlation between the International Geomagnetic Reference Field (IGRF 2010.0 and the Egyptian Geomagnetic Reference Field (EGRF 2010 is indicated.

The Geomagnetic Field During a Reversal

Science.gov (United States)

Heirtzler, James R.

2003-01-01

By modifying the IGRF it is possible to learn what may happen to the geomagnetic field during a geomagnetic reversal. If the entire IGRF reverses then the declination and inclination only reverse when the field strength is zero. If only the dipole component of the IGRF reverses a large geomagnetic field remains when the dipole component is zero and he direction of the field at the end of the reversal is not exactly reversed from the directions at the beginning of the reversal.

Daily variation characteristics at polar geomagnetic observatories

Science.gov (United States)

Lepidi, S.; Cafarella, L.; Pietrolungo, M.; Di Mauro, D.

2011-08-01

This paper is based on the statistical analysis of the diurnal variation as observed at six polar geomagnetic observatories, three in the Northern and three in the Southern hemisphere. Data are for 2006, a year of low geomagnetic activity. We compared the Italian observatory Mario Zucchelli Station (TNB; corrected geomagnetic latitude: 80.0°S), the French-Italian observatory Dome C (DMC; 88.9°S), the French observatory Dumont D'Urville (DRV; 80.4°S) and the three Canadian observatories, Resolute Bay (RES; 83.0°N), Cambridge Bay (CBB; 77.0°N) and Alert (ALE, 87.2°N). The aim of this work was to highlight analogies and differences in daily variation as observed at the different observatories during low geomagnetic activity year, also considering Interplanetary Magnetic Field conditions and geomagnetic indices.

A Global Atmospheric Model of Meteoric Iron

Science.gov (United States)

Feng, Wuhu; Marsh, Daniel R.; Chipperfield, Martyn P.; Janches, Diego; Hoffner, Josef; Yi, Fan; Plane, John M. C.

2013-01-01

The first global model of meteoric iron in the atmosphere (WACCM-Fe) has been developed by combining three components: the Whole Atmosphere Community Climate Model (WACCM), a description of the neutral and ion-molecule chemistry of iron in the mesosphere and lower thermosphere (MLT), and a treatment of the injection of meteoric constituents into the atmosphere. The iron chemistry treats seven neutral and four ionized iron containing species with 30 neutral and ion-molecule reactions. The meteoric input function (MIF), which describes the injection of Fe as a function of height, latitude, and day, is precalculated from an astronomical model coupled to a chemical meteoric ablation model (CABMOD). This newly developed WACCM-Fe model has been evaluated against a number of available ground-based lidar observations and performs well in simulating the mesospheric atomic Fe layer. The model reproduces the strong positive correlation of temperature and Fe density around the Fe layer peak and the large anticorrelation around 100 km. The diurnal tide has a significant effect in the middle of the layer, and the model also captures well the observed seasonal variations. However, the model overestimates the peak Fe+ concentration compared with the limited rocket-borne mass spectrometer data available, although good agreement on the ion layer underside can be obtained by adjusting the rate coefficients for dissociative recombination of Fe-molecular ions with electrons. Sensitivity experiments with the same chemistry in a 1-D model are used to highlight significant remaining uncertainties in reaction rate coefficients, and to explore the dependence of the total Fe abundance on the MIF and rate of vertical transport.

Catalogue of representative meteor spectra

Czech Academy of Sciences Publication Activity Database

Vojáček, Vlastimil; Borovička, Jiří; Koten, Pavel; Spurný, Pavel; Štork, Rostislav

2015-01-01

Roč. 580, August (2015), A67/1-A67/31 ISSN 0004-6361 R&D Projects: GA ČR(CZ) GAP209/11/1382 Institutional support: RVO:67985815 Keywords : meteorites * meteors * meteoroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

Automatic Video System for Continues Monitoring of the Meteor Activity

Czech Academy of Sciences Publication Activity Database

Koten, Pavel; Fliegel, K.; Vítek, S.; Páta, P.

2011-01-01

Roč. 108, č. 1 (2011), s. 69-76 ISSN 0167-9295 R&D Projects: GA ČR GA205/09/1302 Grant - others:GA ČR(CZ) GAP102/10/1320 Institutional research plan: CEZ:AV0Z10030501 Keywords : meteor * meteor showers * instrumentation Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.667, year: 2011

Meteor detection on ST (MST) radars

International Nuclear Information System (INIS)

Avery, S.K.

1987-01-01

The ability to detect radar echoes from backscatter due to turbulent irregularities of the radio refractive index in the clear atmosphere has lead to an increasing number of established mesosphere - stratosphere - troposphere (MST or ST) radars. Humidity and temperature variations are responsible for the echo in the troposphere and stratosphere and turbulence acting on electron density gradients provides the echo in the mesosphere. The MST radar and its smaller version, the ST radar, are pulsed Doppler radars operating in the VHF - UHF frequency range. These echoes can be used to determine upper atmosphere winds at little extra cost to the ST radar configuration. In addition, the meteor echoes can supplement mesospheric data from an MST radar. The detection techniques required on the ST radar for delineating meteor echo returns are described

French Meteor Network for High Precision Orbits of Meteoroids

Science.gov (United States)

Atreya, P.; Vaubaillon, J.; Colas, F.; Bouley, S.; Gaillard, B.; Sauli, I.; Kwon, M. K.

2011-01-01

There is a lack of precise meteoroids orbit from video observations as most of the meteor stations use off-the-shelf CCD cameras. Few meteoroids orbit with precise semi-major axis are available using film photographic method. Precise orbits are necessary to compute the dust flux in the Earth s vicinity, and to estimate the ejection time of the meteoroids accurately by comparing them with the theoretical evolution model. We investigate the use of large CCD sensors to observe multi-station meteors and to compute precise orbit of these meteoroids. An ideal spatial and temporal resolution to get an accuracy to those similar of photographic plates are discussed. Various problems faced due to the use of large CCD, such as increasing the spatial and the temporal resolution at the same time and computational problems in finding the meteor position are illustrated.

An Automatic Video Meteor Observation Using UFO Capture at the Showa Station

Science.gov (United States)

Fujiwara, Y.; Nakamura, T.; Ejiri, M.; Suzuki, H.

2012-05-01

The goal of our study is to clarify meteor activities in the southern hemi-sphere by continuous optical observations with video cameras with automatic meteor detection and recording at Syowa station, Antarctica.

On the scaling features of high-latitude geomagnetic field fluctuations during a large geomagnetic storm

Science.gov (United States)

De Michelis, Paola; Federica Marcucci, Maria; Consolini, Giuseppe

2015-04-01

Recently we have investigated the spatial distribution of the scaling features of short-time scale magnetic field fluctuations using measurements from several ground-based geomagnetic observatories distributed in the northern hemisphere. We have found that the scaling features of fluctuations of the horizontal magnetic field component at time scales below 100 minutes are correlated with the geomagnetic activity level and with changes in the currents flowing in the ionosphere. Here, we present a detailed analysis of the dynamical changes of the magnetic field scaling features as a function of the geomagnetic activity level during the well-known large geomagnetic storm occurred on July, 15, 2000 (the Bastille event). The observed dynamical changes are discussed in relationship with the changes of the overall ionospheric polar convection and potential structure as reconstructed using SuperDARN data. This work is supported by the Italian National Program for Antarctic Research (PNRA) - Research Project 2013/AC3.08 and by the European Community's Seventh Framework Programme ([FP7/2007-2013]) under Grant no. 313038/STORM and

What do we mean by accuracy in geomagnetic measurements?

Science.gov (United States)

Green, A.W.

1990-01-01

High accuracy is what distinguishes measurements made at the world's magnetic observatories from other types of geomagnetic measurements. High accuracy in determining the absolute values of the components of the Earth's magnetic field is essential to studying geomagnetic secular variation and processes at the core mantle boundary, as well as some magnetospheric processes. In some applications of geomagnetic data, precision (or resolution) of measurements may also be important. In addition to accuracy and resolution in the amplitude domain, it is necessary to consider these same quantities in the frequency and space domains. New developments in geomagnetic instruments and communications make real-time, high accuracy, global geomagnetic observatory data sets a real possibility. There is a growing realization in the scientific community of the unique relevance of geomagnetic observatory data to the principal contemporary problems in solid Earth and space physics. Together, these factors provide the promise of a 'renaissance' of the world's geomagnetic observatory system. ?? 1990.

Geomagnetic Reversals during the Phanerozoic.

Science.gov (United States)

McElhinny, M W

1971-04-09

An antalysis of worldwide paleomagnetic measurements suggests a periodicity of 350 x 10(6) years in the polarity of the geomagnetic field. During the Mesozoic it is predominantly normal, whereas during the Upper Paleozoic it is predominantly reversed. Although geomagnetic reversals occur at different rates throughout the Phanerozoic, there appeaars to be no clear correlation between biological evolutionary rates and reversal frequency.

Meteoric 10Be as a tool to investigate human induced soil fluxes: a conceptual model

Science.gov (United States)

Campforts, Benjamin; Govers, Gerard; Vanacker, Veerle; De Vente, Joris; Boix-Fayos, Carolina; Minella, Jean; Baken, Stijn; Smolders, Erik

2014-05-01

The use of meteoric 10Be as a tool to understand long term landscape behavior is becoming increasingly popular. Due its high residence time, meteoric 10Be allows in principle to investigate in situ erosion rates over time scales exceeding the period studied with classical approaches such as 137Cs. The use of meteoric 10Be strongly contributes to the traditional interpretation of sedimentary archives which cannot be unequivocally coupled to sediment production and could provide biased information over longer time scales (Sadler, 1981). So far, meteoric 10Be has successfully been used in geochemical fingerprinting of sediments, to date soil profiles, to assess soil residence times and to quantify downslope soil fluxes using accumulated 10Be inventories along a hill slope. However, less attention is given to the potential use of the tracer to directly asses human induced changes in soil fluxes through deforestation, cultivation and reforestation. A good understanding of the processes governing the distribution of meteoric 10Be both within the soil profile and at landscape scale is essential before meteoric 10Be can be successfully applied to assess human impact. We developed a spatially explicit 2D-model (Be2D) in order to gain insight in meteoric 10Be movement along a hillslope that is subject to human disturbance. Be2D integrates both horizontal soil fluxes and vertical meteoric 10Be movement throughout the soil prolife. Horizontal soil fluxes are predicted using (i) well studied geomorphical laws for natural erosion and soil formation as well as (ii) human accelerated water and tillage erosion. Vertical movement of meteoric 10Be throughout the soil profile is implemented by inserting depth dependent retardation calculated using experimentally determined partition coefficients (Kd). The model was applied to different environments such as (i) the Belgian loess belt, characterized by aeolian deposits enriched in inherited meteoric 10Be, (ii) highly degraded and stony

CAMS newly detected meteor showers and the sporadic background

Science.gov (United States)

Jenniskens, P.; Nénon, Q.; Gural, P. S.; Albers, J.; Haberman, B.; Johnson, B.; Morales, R.; Grigsby, B. J.; Samuels, D.; Johannink, C.

2016-03-01

The Cameras for Allsky Meteor Surveillance (CAMS) video-based meteoroid orbit survey adds 60 newly identified showers to the IAU Working List of Meteor Showers (numbers 427, 445-446, 506-507, and part of 643-750). 28 of these are also detected in the independent SonotaCo survey. In total, 230 meteor showers and shower components are identified in CAMS data, 177 of which are detected in at least two independent surveys. From the power-law size frequency distribution of detected showers, we extrapolate that 36% of all CAMS-observed meteors originated from ∼700 showers above the N = 1 per 110,000 shower limit. 71% of mass falling to Earth from streams arrives on Jupiter-family type orbits. The transient Geminids account for another 15%. All meteoroids not assigned to streams form a sporadic background with highest detected numbers from the apex source, but with 98% of mass falling in from the antihelion source. Even at large ∼7-mm sizes, a Poynting-Robertson drag evolved population is detected, which implies that the Grün et al. collisional lifetimes at these sizes are underestimated by about a factor of 10. While these large grains survive collisions, many fade on a 104-y timescale, possibly because they disintegrate into smaller particles by processes other than collisions, leaving a more resilient population to evolve.

Unusual Radar Echo from the Wake of Meteor Fireball in Nearly

Directory of Open Access Journals (Sweden)

Young-Sook Lee

2018-06-01

Full Text Available The summer polar lower thermosphere (90–100 km has an interesting connection to meteors, adjacent to the mesopause region attaining the lowest temperature in summer. Meteors supply condensation nuclei for charged ice particles causing polar mesospheric summer echoes (PMSE. We report the observation of meteor trail with nearly horizontal transit at high speed (20–50 km/s, and at last with re-enhanced echo power followed by diffusive echoes. Changes in phase difference between radar receivers aligned in meridional and zonal directions are used to determine variations in horizontal displacements and speeds with respect to time by taking advantage of radar interferometric analysis. The actual transit of echo target is observed along the straight pathway vertically and horizontally extended as much as a distance of at least 24 km and at most 29 km. The meteor trail initially has a signature similar to ‘head echoes’, with travel speeds from 20 – 50 km/s. It subsequently transforms into a different type of echo target including specular echo and then finally the power reenhanced. The reenhancement of echo power is followed by fume-like diffusive echoes, indicating sudden release of plasma as like explosive process probably involved. We discuss a possible role of meteor-triggered secondary plasma trail, such as fireball embedded with electrical discharge that continuously varies the power and transit speed.

Seismic characterization of the Chelyabinsk meteor's terminal explosion

Science.gov (United States)

González, Álvaro; Heimann, Sebastian; Wang, Rongjiang; Cesca, Simone; Dahm, Torsten

2014-05-01

On February 15th, 2013, an exceptionally large meteor in the region of Chelyabinsk, Russia, produced a powerful shock wave which caused unprecedented damage to people and property, the strongest atmospheric infrasound signal ever recorded, and remarkable ground motion. Here we describe and model the resulting Rayleigh waves, recorded at broadband seismic stations at distances from ~230 to ~4,100 km. Our full-waveform modeling uses a seismogram simulation code specifically tailored to consider wave propagation in the atmosphere and solid Earth, and the coupling at the interface between them. An isotropic point-like airburst reproduces very well the available seismic observations, without requiring a more complex explanation, such as a moving source. The measured seismic shaking was generated by direct coupling of the atmospheric shock wave to the ground, and then it propagated outwards faster than the atmospheric shock wave itself, at up to 3.9 km/s. The best-fitting airburst location (61.22° E, 54.88° N) is SW of Chelyabinsk city, exactly at the terminal part of the meteor's trajectory, just after it experienced a dramatic flare, with apparent brightness larger than the Sun's. We estimated the meteor's ground path from published trajectory data, eyewitness observations, and detailed satellite imagery of the exact location where a major meteorite fragment landed, in the frozen Lake Chebarkul (60.32074° E, 54.95966° N). Fixing the source origin time allowed us calculating that the explosion took place in the stratosphere, at an altitude of 22.5 ± 1.5 km. This value is lower than the reported altitude of peak brightness (about 29.5 km), but more consistent with the observations of shock wave travel times. Such results highlight the importance of terminal energy release down to lower altitude. We analyzed a surveillance video recorded inside a factory (61.347° E, 54.902° N) at Korkino, a locality close to the airburst. It shows a time delay of 87.5 seconds

Estimation of Mesospheric Densities at Low Latitudes Using the Kunming Meteor Radar Together With SABER Temperatures

Science.gov (United States)

Yi, Wen; Xue, Xianghui; Reid, Iain M.; Younger, Joel P.; Chen, Jinsong; Chen, Tingdi; Li, Na

2018-04-01

Neutral mesospheric densities at a low latitude have been derived during April 2011 to December 2014 using data from the Kunming meteor radar in China (25.6°N, 103.8°E). The daily mean density at 90 km was estimated using the ambipolar diffusion coefficients from the meteor radar and temperatures from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. The seasonal variations of the meteor radar-derived density are consistent with the density from the Mass Spectrometer and Incoherent Scatter (MSIS) model, show a dominant annual variation, with a maximum during winter, and a minimum during summer. A simple linear model was used to separate the effects of atmospheric density and the meteor velocity on the meteor radar peak detection height. We find that a 1 km/s difference in the vertical meteor velocity yields a change of approximately 0.42 km in peak height. The strong correlation between the meteor radar density and the velocity-corrected peak height indicates that the meteor radar density estimates accurately reflect changes in neutral atmospheric density and that meteor peak detection heights, when adjusted for meteoroid velocity, can serve as a convenient tool for measuring density variations around the mesopause. A comparison of the ambipolar diffusion coefficient and peak height observed simultaneously by two co-located meteor radars indicates that the relative errors of the daily mean ambipolar diffusion coefficient and peak height should be less than 5% and 6%, respectively, and that the absolute error of the peak height is less than 0.2 km.

International Geomagnetic Reference Field

DEFF Research Database (Denmark)

Finlay, Chris; Maus, S.; Beggan, C. D.

2010-01-01

The eleventh generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2009 by the International Association of Geomagnetism and Aeronomy Working Group V‐MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field...... model for epoch 2010.0, and a linear predictive secular variation model for 2010.0–2015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity...

Isotopic meteoric line for Colombia

International Nuclear Information System (INIS)

Rodriguez N, Cesar O

2004-01-01

Isotope analyses from representative rainfall samples taken from different areas in Colombia were processed to yield the meteoric line. Stable isotope composition in precipitation reflects the effects of temperature, altitude and of the continental site, being affected by different sources of atmospheric humidity over the Colombian territory. There is a seasonal variation in isotopic composition of precipitation with grater σ deviation during the rainy season and lower values in the dry season. In coastal areas the variation is smaller and is more pronounced than at continental stations. Correlation between altitude and isotope content led to equations, which indicate, on a regional level, a change in isotopic composition with altitude, of about 0.5 σ units per 200 m, for O 18 and 4 σ units per 200 m for H 2 . Such equations may be used to identify the original altitude of precipitation water, in hydrological surface and groundwater studies. Meteoric line and the concepts derived from the resulting equations presented in this paper may be applied to the interpretation of isotope analysis in future hydrological studies, particularly in areas without available data

Asteroids, Comets, Meteors 2014

Science.gov (United States)

Muinonen, K.; Penttilä, A.; Granvik, M.; Virkki, A.; Fedorets, G.; Wilkman, O.; Kohout, T.

2014-08-01

Asteroids, Comets, Meteors focuses on the research of small Solar System bodies. Small bodies are the key to understanding the formation and evolution of the Solar System, carrying signals from pre-solar times. Understanding the evolution of the Solar System helps unveil the evolution of extrasolar planetary systems. Societally, small bodies will be important future resources of minerals. The near-Earth population of small bodies continues to pose an impact hazard, whether it be small pieces of falling meteorites or larger asteroids or cometary nuclei capable of causing global environmental effects. The conference series entitled ''Asteroids, Comets, Meteors'' constitutes the leading international series in the field of small Solar System bodies. The first three conferences took place in Uppsala, Sweden in 1983, 1985, and 1989. The conference is now returning to Nordic countries after a quarter of a century. After the Uppsala conferences, the conference has taken place in Flagstaff, Arizona, U.S.A. in 1991, Belgirate, Italy in 1993, Paris, France in 1996, Ithaca, New York, U.S.A. in 1999, in Berlin, Germany in 2002, in Rio de Janeiro, Brazil in 2005, in Baltimore, Maryland, U.S.A. in 2008, and in Niigata, Japan in 2012. ACM in Helsinki, Finland in 2014 will be the 12th conference in the series.

Geomagnetic Storm Impact On GPS Code Positioning

Science.gov (United States)

Uray, Fırat; Varlık, Abdullah; Kalaycı, İbrahim; Öǧütcü, Sermet

2017-04-01

This paper deals with the geomagnetic storm impact on GPS code processing with using GIPSY/OASIS research software. 12 IGS stations in mid-latitude were chosen to conduct the experiment. These IGS stations were classified as non-cross correlation receiver reporting P1 and P2 (NONCC-P1P2), non-cross correlation receiver reporting C1 and P2 (NONCC-C1P2) and cross-correlation (CC-C1P2) receiver. In order to keep the code processing consistency between the classified receivers, only P2 code observations from the GPS satellites were processed. Four extreme geomagnetic storms October 2003, day of the year (DOY), 29, 30 Halloween Storm, November 2003, DOY 20, November 2004, DOY 08 and four geomagnetic quiet days in 2005 (DOY 92, 98, 99, 100) were chosen for this study. 24-hour rinex data of the IGS stations were processed epoch-by-epoch basis. In this way, receiver clock and Earth Centered Earth Fixed (ECEF) Cartesian Coordinates were solved for a per-epoch basis for each day. IGS combined broadcast ephemeris file (brdc) were used to partly compensate the ionospheric effect on the P2 code observations. There is no tropospheric model was used for the processing. Jet Propulsion Laboratory Application Technology Satellites (JPL ATS) computed coordinates of the stations were taken as true coordinates. The differences of the computed ECEF coordinates and assumed true coordinates were resolved to topocentric coordinates (north, east, up). Root mean square (RMS) errors for each component were calculated for each day. The results show that two-dimensional and vertical accuracy decreases significantly during the geomagnetic storm days comparing with the geomagnetic quiet days. It is observed that vertical accuracy is much more affected than the horizontal accuracy by geomagnetic storm. Up to 50 meters error in vertical component has been observed in geomagnetic storm day. It is also observed that performance of Klobuchar ionospheric correction parameters during geomagnetic storm

The Egyptian geomagnetic reference field to the Epoch, 2010.0

Science.gov (United States)

Deebes, H. A.; Abd Elaal, E. M.; Arafa, T.; Lethy, A.; El Emam, A.; Ghamry, E.; Odah, H.

2017-06-01

The present work is a compilation of two tasks within the frame of the project ;Geomagnetic Survey & Detailed Geomagnetic Measurements within the Egyptian Territory; funded by the ;Science and Technology Development Fund agency (STDF);. The National Research Institute of Astronomy and Geophysics (NRIAG), has conducted a new extensive land geomagnetic survey that covers the whole Egyptian territory. The field measurements have been done at 3212 points along all the asphalted roads, defined tracks, and ill-defined tracks in Egypt; with total length of 11,586 km. In the present work, the measurements cover for the first time new areas as: the southern eastern borders of Egypt including Halayeb and Shlatin, the Quattara depresion in the western desert, and the new roads between Farafra and Baharia oasis. Also marine geomagnetic survey have been applied for the first time in Naser lake. Misallat and Abu-Simble geomagnetic observatories have been used to reduce the field data to the Epoch 2010. During the field measurements, whenever possible, the old stations occupied by the previous observers have been re-occupied to determine the secular variations at these points. The geomagnetic anomaly maps, the normal geomagnetic field maps with their corresponding secular variation maps, the normal geomagnetic field equations of the geomagnetic elements (EGRF) and their corresponding secular variations equations, are outlined. The anomalous sites, as discovered from the anomaly maps are, only, mentioned. In addition, a correlation between the International Geomagnetic Reference Field (IGRF) 2010.0 and the Egyptian Geomagnetic Reference Field (EGRF) 2010 is indicated.

Optical observations of enhanced activity of the 2005 Draconid meteor shower

Czech Academy of Sciences Publication Activity Database

Koten, Pavel; Borovička, Jiří; Spurný, Pavel; Štork, Rostislav

2007-01-01

Roč. 466, č. 2 (2007), s. 729-735 ISSN 0004-6361 R&D Projects: GA AV ČR KJB300030502; GA ČR GA205/05/0543 Institutional research plan: CEZ:AV0Z10030501 Keywords : meteors * meteor shower s * Draconids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.259, year: 2007

Bright Perseid fireball with exceptional beginning height of 170 km observed by different techniques

Czech Academy of Sciences Publication Activity Database

Spurný, Pavel; Shrbený, Lukáš; Borovička, Jiří; Koten, Pavel; Vojáček, Vlastimil; Štork, Rostislav

2014-01-01

Roč. 563, March (2014), A64/1-A64/6 ISSN 0004-6361 R&D Projects: GA ČR GPP209/11/P651; GA ČR GA205/09/1302; GA ČR(CZ) GAP209/11/1382 Institutional support: RVO:67985815 Keywords : meteorites * meteors * meteoroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

Results of the first continuous meteor head echo survey at polar latitudes

Science.gov (United States)

Schult, Carsten; Stober, Gunter; Janches, Diego; Chau, Jorge L.

2017-11-01

We present the first quasi continuous meteor head echo measurements obtained during a period of over two years using the Middle Atmosphere ALOMAR Radar System (MAARSY). The measurements yield information on the altitude, trajectory, vector velocity, radar cross section, deceleration and dynamical mass of every single event. The large statistical amount of nearly one million meteor head detections provide an excellent overview of the elevation, altitude, velocity and daily count rate distributions during different times of the year at polar latitudes. Only 40% of the meteors were detected within the full width half maximum of the specific sporadic meteor sources. Our observation of the sporadic meteors are compared to the observations with other radar systems and a meteor input function (MIF). The best way to compare different radar systems is by comparing the radar cross section (RCS), which is the main detection criterion for each system. In this study we aim to compare our observations with a MIF, which provides information only about the meteoroid mass. Thus, we are using a statistical approach for the elevation and velocity dependent visibility and a specific mass selection. The predicted absolute count rates from the MIF are in a good agreement with the observation when it is assumed that the radar system is only sensitive to meteoroids with masses higher than one microgram. The analysis of the dynamic masses seems to be consistent with this assumption since the count rate of events with smaller masses are low and decrease even more by using events with relatively small errors.

Mantle superplumes induce geomagnetic superchrons

Directory of Open Access Journals (Sweden)

Peter eOlson

2015-07-01

Full Text Available We use polarity reversal systematics from numerical dynamos to quantify the hypothesis that the modulation of geomagnetic reversal frequency, including geomagnetic superchrons, results from changes in core heat flux related to growth and collapse of lower mantle superplumes. We parameterize the reversal frequency sensitivity from numerical dynamos in terms of average core heat flux normalized by the difference between the present-day core heat flux and the core heat flux at geomagnetic superchron onset. A low-order polynomial fit to the 0-300 Ma Geomagnetic Polarity Time Scale (GPTS reveals that a decrease in core heat flux relative to present-day of approximately 30% can account for the Cretaceous Normal Polarity and Kiaman Reverse Polarity Superchrons, whereas the hyper-reversing periods in the Jurassic require a core heat flux equal to or higher than present-day. Possible links between GPTS transitions, large igneous provinces (LIPs, and the two lower mantle superplumes are explored. Lower mantle superplume growth and collapse induce GPTS transitions by increasing and decreasing core heat flux, respectively. Age clusters of major LIPs postdate transitions from hyper-reversing to superchron geodynamo states by 30-60 Myr, suggesting that superchron onset may be contemporaneous with LIP-forming instabilities produced during collapses of lower mantle superplumes.

Double station observation of Draconid meteor outburst from two moving aircraft

Czech Academy of Sciences Publication Activity Database

Koten, Pavel; Vaubaillon, J.; Margonis, A.; Toth, J.; Ďuriš, F.; McAulliffe, J.; Oberst, J.

2015-01-01

Roč. 118, December (2015), s. 112-119 ISSN 0032-0633 R&D Projects: GA ČR GA14-25251S; GA ČR(CZ) GAP209/11/1382; GA MŠk 7AMB13FR006 Institutional support: RVO:67985815 Keywords : meteors * meteor showers * Draconids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.942, year: 2015

METEOR: An Enterprise Health Informatics Environment to Support Evidence-Based Medicine.

Science.gov (United States)

Puppala, Mamta; He, Tiancheng; Chen, Shenyi; Ogunti, Richard; Yu, Xiaohui; Li, Fuhai; Jackson, Robert; Wong, Stephen T C

2015-12-01

The aim of this paper is to propose the design and implementation of next-generation enterprise analytics platform developed at the Houston Methodist Hospital (HMH) system to meet the market and regulatory needs of the healthcare industry. For this goal, we developed an integrated clinical informatics environment, i.e., Methodist environment for translational enhancement and outcomes research (METEOR). The framework of METEOR consists of two components: the enterprise data warehouse (EDW) and a software intelligence and analytics (SIA) layer for enabling a wide range of clinical decision support systems that can be used directly by outcomes researchers and clinical investigators to facilitate data access for the purposes of hypothesis testing, cohort identification, data mining, risk prediction, and clinical research training. Data and usability analysis were performed on METEOR components as a preliminary evaluation, which successfully demonstrated that METEOR addresses significant niches in the clinical informatics area, and provides a powerful means for data integration and efficient access in supporting clinical and translational research. METEOR EDW and informatics applications improved outcomes, enabled coordinated care, and support health analytics and clinical research at HMH. The twin pressures of cost containment in the healthcare market and new federal regulations and policies have led to the prioritization of the meaningful use of electronic health records in the United States. EDW and SIA layers on top of EDW are becoming an essential strategic tool to healthcare institutions and integrated delivery networks in order to support evidence-based medicine at the enterprise level.

Meteor Shower Forecast Improvements from a Survey of All-Sky Network Observations

Science.gov (United States)

Moorhead, Althea V.; Sugar, Glenn; Brown, Peter G.; Cooke, William J.

2015-01-01

Meteoroid impacts are capable of damaging spacecraft and potentially ending missions. In order to help spacecraft programs mitigate these risks, NASA's Meteoroid Environment Office (MEO) monitors and predicts meteoroid activity. Temporal variations in near-Earth space are described by the MEO's annual meteor shower forecast, which is based on both past shower activity and model predictions. The MEO and the University of Western Ontario operate sister networks of all-sky meteor cameras. These networks have been in operation for more than 7 years and have computed more than 20,000 meteor orbits. Using these data, we conduct a survey of meteor shower activity in the "fireball" size regime using DBSCAN. For each shower detected in our survey, we compute the date of peak activity and characterize the growth and decay of the shower's activity before and after the peak. These parameters are then incorporated into the annual forecast for an improved treatment of annual activity.

The extra-atmospheric masses of small meteoric fireballs from the Prairie and the Canadian camera networks.

Science.gov (United States)

Popelenskaya, N.

2007-08-01

Existing methods of definition of extra-atmospheric masses of small meteoric bodies according to supervision of their movement in an atmosphere contain the certain arbitrariness. Vigorous attempts to overcome a divergence of results of calculations on the basis of various approaches often lead to physically incorrect conclusions. The output consists in patient accumulation of estimations and calculations for gradual elimination uncertainties. The equations of meteoric physics include two dimensionless parameters - factor ablation ? and factor of braking ?. In work are cited the data processing supervision of small meteors Prairie and Canadian networks, by a finding of values of parameters ? and ? with use of a method of the least squares. Also values of heights blackout a meteor which turn out from conditions of full destruction or final braking with use of the received values of ? and ? are considered. In prevailing number of supervision for considered meteors braking is insignificant. Results of calculations of height of blackout meteors confirm suitability of the approximations used in work for the description of movement of small meteors. In work results of calculation of extra-atmospheric masses with use of factor of braking for meteoric bodies of the spherical form with density of an ice and a stone are presented. On the basis of the received results discrepancy of photometric masses to values of masses of the input, received on observable braking proves to be true. In most cases received magnitude of masses essentially less photometric masses. Processing of supervision of small meteors Prairie and Canadian camera networks has shown, that the so-called photometric mass mismatches values of mass of the input, defined on observable braking. Acceptance of photometric value as the mass defining braking of a body, leads to obviously underestimated values of density of substance meteoric body. The further researches on specification of interpretation of supervision

Origin of meteor swarms of the Arietid and Geminid types

International Nuclear Information System (INIS)

Lebedinets, V.N.

1985-01-01

The author proposes a physical mechanism for the formation of meteor swarms on orbits of small size and very small perihelion distance, similar to the orbits of Arietid and Geminid meteor swarms, which are rarely encountered among the larger bodies of the solar system, and he justifies the mechanism mathematically. He shows that comets can transfer to such orbits from orbits of large size during evaporation of their ice nuclei under the action of reactive drag

Meteor reporting made easy- The Fireballs in the Sky smartphone app

Science.gov (United States)

Sansom, E.; Ridgewell, J.; Bland, P.; Paxman, J.

2016-01-01

Using smartphone technology, the award-winning 'Fireballs in the Sky' app provides a new approach to public meteor reporting. Using the internal GPS and sensors of a smartphone, a user can record the start and end position of a meteor sighting with a background star field as reference. Animations are used to visualize the duration and characteristics of the meteor. The intuitive application can be used in situ, providing a more accurate eye witness account than after-the-fact reports (although reports may also be made through a website interface). Since its launch in 2013, the app has received over 2000 submissions, including 73 events which were reported by multiple users. The app database is linked to the Desert Fireball Network in Australia (DFN), meaning app reports can be confirmed by DFN observatories. Supporting features include an integrated meteor shower tool that provides updates on active showers, their visibility based on moon phase, as well as a tool to point the user toward the radiant. The locations of reports are also now shown on a live map on the Fireballs in the Sky webpage.

Comparison with Russian analyses of meteor impact

Energy Technology Data Exchange (ETDEWEB)

Canavan, G.H.

1997-06-01

The inversion model for meteor impacts is used to discuss Russian analyses and compare principal results. For common input parameters, the models produce consistent estimates of impactor parameters. Directions for future research are discussed and prioritized.

Radar observations of meteor trails, and their interpretation using Fresnel holography: a new tool in meteor science

Directory of Open Access Journals (Sweden)

W. G. Elford

2004-01-01

Full Text Available A Fresnel transform technique has been developed at Adelaide to analyse radar meteor echoes detected in the transverse mode. The genesis for this technique was the study of the structure of the scattering ionization immediately behind the head of the trail, in order to deduce the degree of fragmentation of the ablating meteoroid. The technique has been remarkably successful in not only giving insight into the fragmentation of meteoroids, but also revealing other significant features of the trails including diffusion, lateral motion of the trail during formation due to wind drift, and phase of the scattered signal in the vicinity of the head of the trail. A serendipitous outcome of the analysis is the measurement of the speed and deceleration of the meteoroid producing the trail to a precision far exceeding that available from any other method applied to transverse scatter data. Examples of the outcomes of the technique applied to meteor echoes obtained with a 54MHz narrow beam radar are presented.

Magnetotactic bacteria at the geomagnetic equator

International Nuclear Information System (INIS)

Frankel, R.B.; Blakemore, R.P.; Araujo, F.F.T. de; Esquivel, D.M.S.; Danon, J.

1981-01-01

Magnetotatic bacteria are observed in freshwater and marine sediments of Fortaleza, Brazil, situated close to the geomagnetic equator. Both South-seeking and North-seeking bacteria are present in roughly equal numbers in the same samples. This observation is consistent with the hypothesis that the vertical component of the geomagnetic field selects the predominant polarity type among magnetotactic bacteria in natural environments. (Author) [pt

PMN-Portuguese Meteor Network and OLA-Observatório do Lago Alqueva agreement

Science.gov (United States)

Saraiva, C.

2018-01-01

The PMN-Portuguese Meteor Network has two new video meteor detecting systems at OLA- Observartório do Lago Alqueva, situated at the South East Portuguese territory with a pristine night sky and more than 290 clear nights each year.

The national geomagnetic initiative

Science.gov (United States)

1993-01-01

The Earth's magnetic field, through its variability over a spectrum of spatial and temporal scales, contains fundamental information on the solid Earth and geospace environment (the latter comprising the atmosphere, ionosphere, and magnetosphere). Integrated studies of the geomagnetic field have the potential to address a wide range of important processes in the deep mantle and core, asthenosphere, lithosphere, oceans, and the solar-terrestrial environment. These studies have direct applications to important societal problems, including resource assessment and exploration, natural hazard mitigation, safe navigation, and the maintenance and survivability of communications and power systems on the ground and in space. Studies of the Earth's magnetic field are supported by a variety of federal and state agencies as well as by private industry. Both basic and applied research is presently supported by several federal agencies, including the National Science Foundation (NSF), U.S. Geological Survey (USGS), U.S. Department of Energy (DOE), National Oceanic and Atmospheric Administration (NOAA), National Aeronautics and Space Administration (NASA), and U.S. Department of Defense (DOD) (through the Navy, Air Force, and Defense Mapping Agency). Although each agency has a unique, well-defined mission in geomagnetic studies, many areas of interest overlap. For example, NASA, the Navy, and USGS collaborate closely in the development of main field reference models. NASA, NSF, and the Air Force collaborate in space physics. These interagency linkages need to be strengthened. Over the past decade, new opportunities for fundamental advances in geomagnetic research have emerged as a result of three factors: well-posed, first-order scientific questions; increased interrelation of research activities dealing with geomagnetic phenomena; and recent developments in technology. These new opportunities can be exploited through a national geomagnetic initiative to define objectives and

Geomagnetic aa Indices

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The geomagnetic aa indices are the continuation of the series beginning in the year 1868. A full description of these indices is given in the International...

Be2D: A model to understand the distribution of meteoric 10Be in soilscapes

Science.gov (United States)

Campforts, Benjamin; Vanacker, Veerle; Vanderborght, Jan; Govers, Gerard

2016-04-01

Cosmogenic nuclides have revolutionised our understanding of earth surface process rates. They have become one of the standard tools to quantify soil production by weathering, soil redistribution and erosion. Especially Beryllium-10 has gained much attention due to its long half-live and propensity to be relatively conservative in the landscape. The latter makes 10Be an excellent tool to assess denudation rates over the last 1000 to 100 × 103 years, bridging the anthropogenic and geological time scale. Nevertheless, the mobility of meteoric 10Be in soil systems makes translation of meteoric 10Be inventories into erosion and deposition rates difficult. Here we present a coupled soil hillslope model, Be2D, that is applied to synthetic and real topography to address the following three research questions. (i) What is the influence of vertical meteoric Be10 mobility, caused by chemical mobility, clay translocation and bioturbation, on its lateral redistribution over the soilscape, (ii) How does vertical mobility influence erosion rates and soil residence times inferred from meteoric 10Be inventories and (iii) To what extent can a tracer with a half-life of 1.36 Myr be used to distinguish between natural and human-disturbed soil redistribution rates? The model architecture of Be2D is designed to answer these research questions. Be2D is a dynamic model including physical processes such as soil formation, physical weathering, clay migration, bioturbation, creep, overland flow and tillage erosion. Pathways of meteoric 10Be mobility are simulated using a two step approach which is updated each timestep. First, advective and diffusive mobility of meteoric 10Be is simulated within the soil profile and second, lateral redistribution because of lateral soil fluxes is calculated. The performance and functionality of the model is demonstrated through a number of synthetic and real model runs using existing datasets of meteoric 10Be from case-studies in southeastern US. Brute

An Initial Meteoroid Stream Survey in the Southern Hemisphere Using the Southern Argentina Agile Meteor Radar (SAAMER)

Science.gov (United States)

Janches, D.; Hormaechea, J. L.; Brunini, C.; Hocking, W.; Fritts, D. C.

2013-01-01

We present in this manuscript a 4 year survey of meteor shower radiants utilizing the Southern Argentina Agile Meteor Radar (SAAMER). SAAMER, which operates at the southern most region of South America, is a new generation SKiYMET system designed with significant differences from typical meteor radars including high transmitted power and an 8-antenna transmitting array enabling large detected rates at low zenith angles. We applied the statistical methodology developed by Jones and Jones (Jones, J., Jones, W. [2006]. Month. Not. R. Astron. Soc. 367, 1050-1056) to the data collected each day and compiled the results into 1 composite representative year at 1 resolution in Solar Longitude. We then search for enhancements in the activity which last for at least 3 days and evolve temporally as is expected from a meteor shower. Using this methodology, we have identified in our data 32 shower radiants, two of which were not part of the IAU commission 22 meteor shower working list. Recently, SAAMER's capabilities were enhanced by adding two remote stations to receive meteor forward scatter signals from meteor trails and thus enable the determination of meteoroid orbital parameters. SAAMER started recording orbits in January 2012 and future surveys will focus on the search for unknown meteor streams, in particular in the southern ecliptic sky.

Dynamical Model for the Zodiacal Cloud and Sporadic Meteors

Science.gov (United States)

Nesvorný, David; Janches, Diego; Vokrouhlický, David; Pokorný, Petr; Bottke, William F.; Jenniskens, Peter

2011-12-01

The solar system is dusty, and would become dustier over time as asteroids collide and comets disintegrate, except that small debris particles in interplanetary space do not last long. They can be ejected from the solar system by Jupiter, thermally destroyed near the Sun, or physically disrupted by collisions. Also, some are swept by the Earth (and other planets), producing meteors. Here we develop a dynamical model for the solar system meteoroids and use it to explain meteor radar observations. We find that the Jupiter Family Comets (JFCs) are the main source of the prominent concentrations of meteors arriving at the Earth from the helion and antihelion directions. To match the radiant and orbit distributions, as measured by the Canadian Meteor Orbit Radar (CMOR) and Advanced Meteor Orbit Radar (AMOR), our model implies that comets, and JFCs in particular, must frequently disintegrate when reaching orbits with low perihelion distance. Also, the collisional lifetimes of millimeter particles may be longer (gsim 105 yr at 1 AU) than postulated in the standard collisional models (~104 yr at 1 AU), perhaps because these chondrule-sized meteoroids are stronger than thought before. Using observations of the Infrared Astronomical Satellite to calibrate the model, we find that the total cross section and mass of small meteoroids in the inner solar system are (1.7-3.5) × 1011 km2 and ~4 × 1019 g, respectively, in a good agreement with previous studies. The mass input required to keep the zodiacal cloud in a steady state is estimated to be ~104-105 kg s-1. The input is up to ~10 times larger than found previously, mainly because particles released closer to the Sun have shorter collisional lifetimes and need to be supplied at a faster rate. The total mass accreted by the Earth in particles between diameters D = 5 μm and 1 cm is found to be ~15,000 tons yr-1 (factor of two uncertainty), which is a large share of the accretion flux measured by the Long Term Duration

Effect of geomagnetic storms on VHF scintillations observed at low latitude

Science.gov (United States)

Singh, S. B.; Patel, Kalpana; Singh, A. K.

2018-06-01

A geomagnetic storm affects the dynamics and composition of the ionosphere and also offers an excellent opportunity to study the plasma dynamics. In the present study, we have used the VHF scintillations data recorded at low latitude Indian station Varanasi (Geomag. latitude = 14^{°}55^' }N, long. = 154^{°}E) which is radiated at 250 MHz from geostationary satellite UFO-02 during the period 2011-2012 to investigate the effects of geomagnetic storms on VHF scintillation. Various geomagnetic and solar indices such as Dst index, Kp index, IMF Bz and solar wind velocity (Vx) are used to describe the geomagnetic field variation observed during geomagnetic storm periods. These indices are very helpful to find out the proper investigation and possible interrelation between geomagnetic storms and observed VHF scintillation. The pre-midnight scintillation is sometimes observed when the main phase of geomagnetic storm corresponds to the pre-midnight period. It is observed that for geomagnetic storms for which the recovery phase starts post-midnight, the probability of occurrence of irregularities is enhanced during this time and extends to early morning hours.

Recent Activities Of The World Data Centre For Geomagnetism (Edinburgh)

OpenAIRE

Reay, Sarah; Humphries, Tom; Macmillan, Susan; Flower, Simon; Stevenson, Peter; Clarke, Ellen

2015-01-01

For almost 50 years the World Data Centre for Geomagnetism (Edinburgh) has been a custodian of geomagnetic data. In particular, over recent years the scope of the data holdings has been increased, quality control measures introduced and better interfaces to make the data more accessible to users are being developed. The WDC hold geomagnetic time-series data from around 280 observatories worldwide at a number of time resolutions along with various magnetic survey, model, and geomagnetic ac...

Radar meteors range distribution model. II. Shower flux density and mass distribution index

Czech Academy of Sciences Publication Activity Database

Pecinová, Drahomíra; Pecina, Petr

2007-01-01

Roč. 37, č. 2 (2007), s. 107-124 ISSN 1335-1842 R&D Projects: GA ČR GA205/03/1405 Institutional research plan: CEZ:AV0Z10030501 Keywords : physics of meteors * radar meteors * range distribution Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

Radar meteors range distribution model. III. Ablation, shape-density and self-similarity parameters

Czech Academy of Sciences Publication Activity Database

Pecinová, Drahomíra; Pecina, Petr

2007-01-01

Roč. 37, č. 3 (2007), s. 147-160 ISSN 1335-1842 R&D Projects: GA ČR GA205/03/1405 Institutional research plan: CEZ:AV0Z10030501 Keywords : physics of meteors * radar meteors * range distribution Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

An impending geomagnetic transition? Hints from the past

OpenAIRE

Laj, Carlo; Kissel, Catherine

2015-01-01

The rapid decrease of the geomagnetic field intensity in the last centuries has led to speculations that an attempt to a reversal or an excursion might be under way. Here we investigate this hypothesis by examining past records of geomagnetic field intensity obtained from sedimentary cores and from the study of cosmogenic nuclides. The selected records describe geomagnetic changes with an unprecedented temporal resolution between 20 and 75 kyr B.P. We find that some aspects of the present-day...

Effects of geomagnetic activity on the mesospheric electric fields

Directory of Open Access Journals (Sweden)

A. M. Zadorozhny

1998-12-01

Full Text Available The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes Kp and ∑Kp. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (Kp=8+. A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.Keywords. Atmospheric composition and structure (aerosols and particles · Ionosphere (electric fields and currents · Meteorology and atmospheric dynamics (atmospheric electricity

Automated detection of geomagnetic storms with heightened risk of GIC

Science.gov (United States)

Bailey, Rachel L.; Leonhardt, Roman

2016-06-01

Automated detection of geomagnetic storms is of growing importance to operators of technical infrastructure (e.g., power grids, satellites), which is susceptible to damage caused by the consequences of geomagnetic storms. In this study, we compare three methods for automated geomagnetic storm detection: a method analyzing the first derivative of the geomagnetic variations, another looking at the Akaike information criterion, and a third using multi-resolution analysis of the maximal overlap discrete wavelet transform of the variations. These detection methods are used in combination with an algorithm for the detection of coronal mass ejection shock fronts in ACE solar wind data prior to the storm arrival on Earth as an additional constraint for possible storm detection. The maximal overlap discrete wavelet transform is found to be the most accurate of the detection methods. The final storm detection software, implementing analysis of both satellite solar wind and geomagnetic ground data, detects 14 of 15 more powerful geomagnetic storms over a period of 2 years.

A Global Model of Meteoric Sodium

Science.gov (United States)

Marsh, Daniel R.; Janches, Diego; Feng, Wuhu; Plane, John M. C.

2013-01-01

A global model of sodium in the mesosphere and lower thermosphere has been developed within the framework of the National Center for Atmospheric Research's Whole Atmosphere Community Climate Model (WACCM). The standard fully interactive WACCM chemistry module has been augmented with a chemistry scheme that includes nine neutral and ionized sodium species. Meteoric ablation provides the source of sodium in the model and is represented as a combination of a meteoroid input function (MIF) and a parameterized ablation model. The MIF provides the seasonally and latitudinally varying meteoric flux which is modeled taking into consideration the astronomical origins of sporadic meteors and considers variations in particle entry angle, velocity, mass, and the differential ablation of the chemical constituents. WACCM simulations show large variations in the sodium constituents over time scales from days to months. Seasonality of sodium constituents is strongly affected by variations in the MIF and transport via the mean meridional wind. In particular, the summer to winter hemisphere flow leads to the highest sodium species concentrations and loss rates occurring over the winter pole. In the Northern Hemisphere, this winter maximum can be dramatically affected by stratospheric sudden warmings. Simulations of the January 2009 major warming event show that it caused a short-term decrease in the sodium column over the polar cap that was followed by a factor of 3 increase in the following weeks. Overall, the modeled distribution of atomic sodium in WACCM agrees well with both ground-based and satellite observations. Given the strong sensitivity of the sodium layer to dynamical motions, reproducing its variability provides a stringent test of global models and should help to constrain key atmospheric variables in this poorly sampled region of the atmosphere.

Association between meteor showers and asteroids using multivariate criteria

Science.gov (United States)

Dumitru, B. A.; Birlan, M.; Popescu, M.; Nedelcu, D. A.

2017-10-01

Context. Meteoroid streams are fragments of matter produced by comets or asteroids which intersects the orbit of Earth. Meteor showers are produced when Earth intersects these streams of matter. The discoveries of active asteroids and extinct comets open a new view of the relation between these objects as possible parent bodies at the origin of meteor showers. Aims: The aim of this work is to identify the asteroids that can produce or re-populate meteoroid streams by determining the similarity of their orbits and orbital evolution over 10 000 yr. Methods: The identification was carried out by evaluating several well known D-criteria metrics, the orbits being taken from the IAU Meteor Data Center database and from IAU Minor Planet Center. Finally, we analyzed the physical properties and the orbital stability (in the Lyapunov time sense) of the candidates as well as their possible relationship with meteorites. Results: 206 near-Earth asteroids (NEAs) were associated as possible parent bodies with 28 meteor showers, according to at least two of the criterion used. 50 of them satisfied all the criteria. Notable finds are: binary asteroid 2000UG11 associated with Andromedids (AND), while the tumbling asteroid (4179)Toutatis could be associated with October Capricornids (OCC). Other possible good candidates are 2004TG10, 2008EY5, 2010CF55, 2010TU149 and 2014OY1. These objects have low albedo, therefore can be primitive objects. Asteroid 2007LW19 which is a fast rotator and most probably has monolithic structure and so its physical characteristic does not support the association found based on the dynamical criteria.

Simulating the mobility of meteoric 10Be in the landscape through a coupled soil-hillslope model (Be2D)

Science.gov (United States)

Campforts, Benjamin; Vanacker, Veerle; Vanderborght, Jan; Baken, Stijn; Smolders, Erik; Govers, Gerard

2016-04-01

Meteoric 10Be allows for the quantification of vertical and lateral soil fluxes over long time scales (103-105 yr). However, the mobility of meteoric 10Be in the soil system makes a translation of meteoric 10Be inventories into erosion and deposition rates complex. Here, we present a spatially explicit 2D model simulating the behaviour of meteoric 10Be on a hillslope. The model consists of two parts. The first component deals with advective and diffusive mobility of meteoric 10Be within the soil profile, and the second component describes lateral soil and meteoric 10Be fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering as well as downslope fluxes of soil due to creep, water and tillage erosion. Synthetic model simulations show that meteoric 10Be inventories can be related to erosion and deposition across a wide range of geomorphological and pedological settings. Our results also show that meteoric 10Be can be used as a tracer to detect human impact on soil fluxes for soils with a high affinity for meteoric 10Be. However, the quantification of vertical mobility is essential for a correct interpretation of the observed variations in meteoric 10Be profiles and inventories. Application of the Be2D model to natural conditions using data sets from the Southern Piedmont (Bacon et al., 2012) and Appalachian Mountains (Jungers et al., 2009; West et al., 2013) allows to reliably constrain parameter values. Good agreement between simulated and observed meteoric 10Be concentrations and inventories is obtained with realistic parameter values. Furthermore, our results provide detailed insights into the processes redistributing meteoric 10Be at the soil-hillslope scale.

Assessing soil fluxes using meteoric 10Be: development and application of the Be2D model

Science.gov (United States)

Campforts, Benjamin; Govers, Gerard; Vanacker, Veerle; Baken, Stijn; Smolders, Erik; Vanderborght, Jan

2015-04-01

Meteoric 10Be is a promising and increasingly popular tool to better understand soil fluxes at different timescales. Unlike other, more classical, methods such as the study of sedimentary archives it enables a direct coupling between eroding and deposition sites. However, meteoric 10Be can be mobilized within the soil. Therefore, spatial variations in meteoric 10Be inventories cannot directly be translated into spatial variations in erosion and sedimentation rates: a correct interpretation of measured 10Be inventories requires that both lateral and vertical movement of meteoric 10Be are accounted for. Here, we present a spatially explicit 2D model that allows to simulate the behaviour of meteoric 10Be in the soil system over timescales of up to 1 million year and use the model to investigate the impact of accelerated erosion on meteoric 10Be inventories. The model consists of two parts. A first component deals with advective and diffusive mobility within the soil profile, whereas a second component describes lateral soil (and meteoric 10Be) fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering and lateral soil fluxes. Different types of erosion such as creep, water and tillage erosion are supported. Model runs show that natural soil fluxes can be well reconstructed based on meteoric 10Be inventories, and this for a wide range of geomorphological and pedological conditions. However, extracting signals of human impact and distinguishing them from natural soil fluxes is only feasible when the soil has a rather high retention capacity so that meteoric 10Be is retained in the top soil layer. Application of the Be2D model to an existing data set in the Appalachian Mountains [West et al.,2013] using realistic parameter values for the soil retention capacity as well as for vertical advection resulted in a good agreement between simulated and observed 10Be inventories. This confirms the robustness of the model. We

Toward a possible next geomagnetic transition?

OpenAIRE

A. De Santis; E. Qamili; L. Wu

2013-01-01

The geomagnetic field is subject to possible reversals or excursions of polarity during its temporal evolution. Considering that: (a) the typical average time between one reversal and the next (the so-called chron) is around 300 000 yr, (b) the last reversal occurred around 780 000 yr ago, (c) more excursions (rapid changes of polarity) can occur within the same chron and (d) the geomagnetic field dipole is currently decreasing, a possible imminent geomagne...

Kinematic reversal schemes for the geomagnetic dipole.

Science.gov (United States)

Levy, E. H.

1972-01-01

Fluctuations in the distribution of cyclonic convective cells, in the earth's core, can reverse the sign of the geomagnetic field. Two kinematic reversal schemes are discussed. In the first scheme, a field maintained by cyclones concentrated at low latitude is reversed by a burst of cyclones at high latitude. Conversely, in the second scheme, a field maintained predominantly by cyclones in high latitudes is reversed by a fluctuation consisting of a burst of cyclonic convection at low latitude. The precise fluid motions which produce the geomagnetic field are not known. However, it appears that, whatever the details are, a fluctuation in the distribution of cyclonic cells over latitude can cause a geomagnetic reversal.

Mesospheric temperatures estimated from the meteor radar observations at Mohe, China

Science.gov (United States)

Liu, Libo; Liu, Huixin; Chen, Yiding; Le, Huijun

2017-04-01

In this work, we report the estimation of mesospheric temperatures at 90 km height from the observations of the VHF all-sky meteor radar operated at Mohe (53.5 °N, 122.3° E), China, since August 2011. The kinetic temperature profiles retrieved from the observations of Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) onboard the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) satellite are processed to provide the temperature (TSABER) and temperature gradient (dT/dh) at 90 km height. Based on the SABER temperature profile data an empirical dT/dh model is developed for the Mohe latitude. First, we derive the temperatures from the meteor decay times (Tmeteor) and the Mohe dT/dh model gives prior information of temperature gradients. Secondly, the full-width of half maximum (FWHM) of the meteor height profiles is calculated and further used to deduce the temperatures (TFWHM) based on the strong linear relationship between FWHM and TSABER. The temperatures at 90 km deduced from the decay times (Tmeteor) and from the meteor height distributions (TFWHM) at Mohe are validated/calibrated with TSABER. The temperatures present a considerable annual variation, being maximum in winter and minimum in summer. Harmonic analyses reveal that the temperatures have an annual variation consistent with TSABER. Our work suggests that the FWHM has a good performance in routine estimation of the temperatures. It should be pointed out that the slope of FWHM and TSABER is 10.1 at Mohe, which is different from that of 15.71 at King Sejong (62.2° S, 58.8° E) station. Acknowledgments The TIMED/SABER kinetic temperature (version 2.0) data are provided by the SABER team through http://saber.gats-inc.com/. The temperatures from the NRLMSISE-00 model are calculated using Aerospace Blockset toolbox of MATLAB (2016a). This research was supported by National Natural Science Foundation of China (41231065, 41321003). We acknowledge the use of meteor radar

Effects of geomagnetic activity on the mesospheric electric fields

Directory of Open Access Journals (Sweden)

A. M. Zadorozhny

Full Text Available The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes K_p and ∑K_p. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (K_p=8+. A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.

Keywords. Atmospheric composition and structure (aerosols and particles · Ionosphere (electric fields and currents · Meteorology and atmospheric dynamics (atmospheric electricity

DYNAMICAL MODEL FOR THE ZODIACAL CLOUD AND SPORADIC METEORS

Energy Technology Data Exchange (ETDEWEB)

Nesvorny, David; Vokrouhlicky, David; Pokorny, Petr; Bottke, William F. [Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302 (United States); Janches, Diego [Space Weather Laboratory, Code 674, GSFC/NASA, Greenbelt, MD 20771 (United States); Jenniskens, Peter [Carl Sagan Center, SETI Institute, 515 N. Whisman Road, Mountain View, CA 94043 (United States)

2011-12-20

The solar system is dusty, and would become dustier over time as asteroids collide and comets disintegrate, except that small debris particles in interplanetary space do not last long. They can be ejected from the solar system by Jupiter, thermally destroyed near the Sun, or physically disrupted by collisions. Also, some are swept by the Earth (and other planets), producing meteors. Here we develop a dynamical model for the solar system meteoroids and use it to explain meteor radar observations. We find that the Jupiter Family Comets (JFCs) are the main source of the prominent concentrations of meteors arriving at the Earth from the helion and antihelion directions. To match the radiant and orbit distributions, as measured by the Canadian Meteor Orbit Radar (CMOR) and Advanced Meteor Orbit Radar (AMOR), our model implies that comets, and JFCs in particular, must frequently disintegrate when reaching orbits with low perihelion distance. Also, the collisional lifetimes of millimeter particles may be longer ({approx}> 10{sup 5} yr at 1 AU) than postulated in the standard collisional models ({approx}10{sup 4} yr at 1 AU), perhaps because these chondrule-sized meteoroids are stronger than thought before. Using observations of the Infrared Astronomical Satellite to calibrate the model, we find that the total cross section and mass of small meteoroids in the inner solar system are (1.7-3.5) Multiplication-Sign 10{sup 11} km{sup 2} and {approx}4 Multiplication-Sign 10{sup 19} g, respectively, in a good agreement with previous studies. The mass input required to keep the zodiacal cloud in a steady state is estimated to be {approx}10{sup 4}-10{sup 5} kg s{sup -1}. The input is up to {approx}10 times larger than found previously, mainly because particles released closer to the Sun have shorter collisional lifetimes and need to be supplied at a faster rate. The total mass accreted by the Earth in particles between diameters D = 5 {mu}m and 1 cm is found to be {approx}15

DYNAMICAL MODEL FOR THE ZODIACAL CLOUD AND SPORADIC METEORS

International Nuclear Information System (INIS)

Nesvorný, David; Vokrouhlický, David; Pokorný, Petr; Bottke, William F.; Janches, Diego; Jenniskens, Peter

2011-01-01

The solar system is dusty, and would become dustier over time as asteroids collide and comets disintegrate, except that small debris particles in interplanetary space do not last long. They can be ejected from the solar system by Jupiter, thermally destroyed near the Sun, or physically disrupted by collisions. Also, some are swept by the Earth (and other planets), producing meteors. Here we develop a dynamical model for the solar system meteoroids and use it to explain meteor radar observations. We find that the Jupiter Family Comets (JFCs) are the main source of the prominent concentrations of meteors arriving at the Earth from the helion and antihelion directions. To match the radiant and orbit distributions, as measured by the Canadian Meteor Orbit Radar (CMOR) and Advanced Meteor Orbit Radar (AMOR), our model implies that comets, and JFCs in particular, must frequently disintegrate when reaching orbits with low perihelion distance. Also, the collisional lifetimes of millimeter particles may be longer (∼> 10 5 yr at 1 AU) than postulated in the standard collisional models (∼10 4 yr at 1 AU), perhaps because these chondrule-sized meteoroids are stronger than thought before. Using observations of the Infrared Astronomical Satellite to calibrate the model, we find that the total cross section and mass of small meteoroids in the inner solar system are (1.7-3.5) × 10 11 km 2 and ∼4 × 10 19 g, respectively, in a good agreement with previous studies. The mass input required to keep the zodiacal cloud in a steady state is estimated to be ∼10 4 -10 5 kg s –1 . The input is up to ∼10 times larger than found previously, mainly because particles released closer to the Sun have shorter collisional lifetimes and need to be supplied at a faster rate. The total mass accreted by the Earth in particles between diameters D = 5 μm and 1 cm is found to be ∼15,000 tons yr –1 (factor of two uncertainty), which is a large share of the accretion flux measured by the

Observations on Stratospheric-Mesospheric-Thermospheric temperatures using Indian MST radar and co-located LIDAR during Leonid Meteor Shower (LMS

Directory of Open Access Journals (Sweden)

R. Selvamurugan

2002-11-01

Full Text Available The temporal and height statistics of the occurrence of meteor trails during the Leonid meteor shower revealed the capability of the Indian MST radar to record large numbers of meteor trails. The distribution of radio meteor trails due to a Leonid meteor shower in space and time provided a unique opportunity to construct the height profiles of lower thermospheric temperatures and winds, with good time and height resolution. There was a four-fold increase in the meteor trails observed during the LMS compared to a typical non-shower day. The temperatures were found to be in excellent continuity with the temperature profiles below the radio meteor region derived from the co-located Nd-Yag LIDAR and the maximum height of the temperature profile was extended from the LIDAR to ~110 km. There are, how-ever, some significant differences between the observed profiles and the CIRA-86 model profiles. The first results on the meteor statistics and neutral temperature are presented and discussed below.  Key words. Atmospheric composition and structure (pres-sure, density, and temperature History of geophysics (at-mospheric sciences Meteorology and atmospheric dynamics (middle atmosphere dynamics

Meteor localization via statistical analysis of spatially temporal fluctuations in image sequences

Science.gov (United States)

Kukal, Jaromír.; Klimt, Martin; Šihlík, Jan; Fliegel, Karel

2015-09-01

Meteor detection is one of the most important procedures in astronomical imaging. Meteor path in Earth's atmosphere is traditionally reconstructed from double station video observation system generating 2D image sequences. However, the atmospheric turbulence and other factors cause spatially-temporal fluctuations of image background, which makes the localization of meteor path more difficult. Our approach is based on nonlinear preprocessing of image intensity using Box-Cox and logarithmic transform as its particular case. The transformed image sequences are then differentiated along discrete coordinates to obtain statistical description of sky background fluctuations, which can be modeled by multivariate normal distribution. After verification and hypothesis testing, we use the statistical model for outlier detection. Meanwhile the isolated outlier points are ignored, the compact cluster of outliers indicates the presence of meteoroids after ignition.

About Catalogue of Orbit and Atmospheric Trajectory of 4500 Radio Meteors Brighter +5m

Science.gov (United States)

Narziev, M.; Tshebotaryov, P.

2017-09-01

Published by this time the majority of catalogues of a radiant, speeds and elements of orbits of meteors, basically, are based on a interpretation of the given radio observations by diffraction-time a method. However the given method is applicable for processing of 15-25 % of observed meteors that leads to loss of the most part of an observed material. Besides, the error of measurement of an antiaircraft corner of a radiant σZr with increase in a corner to 60°÷70 ° will be increased in 2-3 times, and at the further increase in a corner the error grows even faster, so measurements lose meaning. In 1968-1970 in action period of the Soviet equatorial meteor expedition to Somalia, simultaneously and radio observations of meteors in HisAO from four points have been resulted. For interpretation of the radar data the bearing-time method radio method developed and applied for the first time in Tajikistan is used. This approximately twice increases number of the measured radiant and speeds. What's more, the error of measurement of an antiaircraft corner does not depend on antiaircraft distance of a radiant. The velocity of meteor is determined by the bearing-time method, and by the diffraction picture. In the catalogue along with a radiant, speeds and elements of orbits, for the first time the height, value of linear electronic density, radio magnitude and masses of each of 4500 radio meteors registered since December 1968 till May, 1969 are resulted.

Instrument for the detection of meteors in the infrared

Science.gov (United States)

Svedhem, H.; Koschny, D.; Ter Haar, J.

2014-07-01

The flux of interplanetary particles in the size range 2 mm to 20 m is poorly constrained due to insufficient data --- the larger bodies may be observed remotely by ground-based or space-based telescopes and the smaller particles are measured by in-situ impact detectors in space or by meteor cameras from ground. An infrared video rate imager in Earth orbit would enable a systematic characterization for an extended period, day and night, of the flux in this range by monitoring the bright meteor/fireball generated during atmospheric entry. Due to the low flux of meteoroids in this range a very large detector is required. With this method a large portion of the Earth atmosphere is in fact used as a huge detector. Such an instrument has never flown in Earth orbit. The only sensors of a similar kind fly on US defense satellites for monitoring launches of ballistic missiles. The data from these sensors, however, is largely inaccessible to scientists. The knowledge on emission of light by meteors/bolides at infrared wavelengths is very limited while it can be suspected that the continuum emission from meteors/bolides have stronger emission at infrared wavelengths than in the visible due to the likely low temperatures of these events. At the same time line emission is dominating over the continuum in the visible so it is not clear how this will compare with the continuum in the infrared. We have developed a bread-board version of an IR video rate camera, the SPOSH-IR. The instrument is based on an earlier technology development, SPOSH --- Smart Panoramic Optical Sensor Head, for operation in the visible range, but with the sensor replaced by a cooled IR detector and new infrared optics. The earlier work has proven the concept of the instrument and of automatic detection of meteors/bolides in the visible wavelength range. The new hardware has been built by Jena-Optronik, Jena, Germany and has been tested during several meteor showers in the Netherlands and at ESA's OGS

Statistical Study of False Alarms of Geomagnetic Storms

DEFF Research Database (Denmark)

Leer, Kristoffer; Vennerstrøm, Susanne; Veronig, A.

. A subset of these halo CMEs did not cause a geomagnetic storm the following four days and have therefore been considered as false alarms. The properties of these events are investigated and discussed here. Their statistics are compared to the geo-effective CMEs. The ability to identify potential false......Coronal Mass Ejections (CMEs) are known to cause geomagnetic storms on Earth. However, not all CMEs will trigger geomagnetic storms, even if they are heading towards the Earth. In this study, front side halo CMEs with speed larger than 500 km/s have been identified from the SOHO LASCO catalogue...

The Innisfree meteorite: Dynamical history of the orbit - Possible family of meteor bodies

Science.gov (United States)

Galibina, I. V.; Terent'eva, A. K.

1987-09-01

Evolution of the Innisfree meteorite orbit caused by secular perturbations is studied over the time interval of 500000 yrs (from the current epoch backwards). Calculations are made by the Gauss-Halphen-Gorjatschew method taking into account perturbations from the four outer planets - Jupiter, Saturn, Uranus and Neptune. In the above mentioned time interval the meteorite orbit has undergone no essential transformations. The Innisfree orbit intersected in 91 cases the Earth orbit and in 94 - the Mars orbit. A system of small and large meteor bodies (producing ordinary meteors and fireballs) which may be genetically related to the Innisfree meteorite has been found, i.e. there probably exists an Innisfree family of meteor bodies.

Coronal mass ejections and large geomagnetic storms

International Nuclear Information System (INIS)

Gosling, J.T.; Bame, S.J.; McComas, D.J.; Phillips, J.L.

1990-01-01

Previous work indicates that coronal mass ejection (CME) events in the solar wind at 1 AU can be identified by the presence of a flux of counterstreaming solar wind halo electrons (above about 80 eV). Using this technique to identify CMEs in 1 AU plasma data, the authors find that most large geomagnetic storms during the interval surrounding the last solar maximum (Aug. 1978-Oct. 1982) were associated with Earth-passage of interplanetary disturbances in which the Earth encountered both a shock and the CME driving the shock. However, only about one CME in six encountered by Earth was effective in causing a large geomagnetic storm. Slow CMEs which did not interact strongly with the ambient solar wind ahead were particularly ineffective in a geomagnetic sense

Some aspects of geomagnetically conjugate phenomena

Energy Technology Data Exchange (ETDEWEB)

Rycroft, M.J.

1987-12-01

Both charged particles and waves convey information about the thermosphere, ionosphere and magnetosphere from the Northern to the Southern Hemisphere and vice versa, along geomagnetic flux tubes.The interhemispheric travel time of electrons or ions, being dependent upon L-value , pitch angle and energy (which may lie between less than or equal to 1 eV and greater than or equal to 1 MeV) may be many hours, ranging down to less than or equal to 1 s. However, the one-hop propagation time for magnetohydrodynamic or whistler mode waves generally lies between 10/sup 2/s and 1 s. Such times, therefore, give the time scales of transient phenomena that are geomagnetically conjugate and of changes in steady-state plasma processes occurring in geomagnetically conjugate regions. Contrasting examples are presented of conjugate physical phenomena, obtained using satellite, rocket, aircraft and ground-based observations; the latter capitalise upon the rather rare disposition of land - rather than ocean - at each end of a geophysically interesting flux tube. Particular attention is paid to the interactions between whistler mode waves and energetic electrons. Geomagnetic, radio, optical and plasma observations, taken together with model computations, provide a wealth of knowledge on conjugate phenomena and their dependence on conditions in the solar wind, substorms, L-value, etc... Finally, some suggestions are made for future lines of research.

International Geomagnetic Reference Field: the 12th generation

DEFF Research Database (Denmark)

Thébault, Erwan; Finlay, Chris; Beggan, Ciarán D.

2015-01-01

The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch ...

Geomagnetic Field Variation during Winter Storm at Localized ...

Indian Academy of Sciences (India)

that transports plasma and magnetic flux which create the geomagnetic field variation. Key words. Dst—vertical component of interplanetary magnetic field and geomagnetic field components. 1. Introduction. The magnetic field is one of the important properties of the earth. The main magnetic field originates from ...

An orbital meteoroid stream survey using the Southern Argentina Agile MEteor Radar (SAAMER) based on a wavelet approach

Science.gov (United States)

Pokorný, P.; Janches, D.; Brown, P. G.; Hormaechea, J. L.

2017-07-01

Over a million individually measured meteoroid orbits were collected with the Southern Argentina Agile MEteor Radar (SAAMER) between 2012-2015. This provides a robust statistical database to perform an initial orbital survey of meteor showers in the Southern Hemisphere via the application of a 3D wavelet transform. The method results in a composite year from all 4 years of data, enabling us to obtain an undisturbed year of meteor activity with more than one thousand meteors per day. Our automated meteor shower search methodology identified 58 showers. Of these showers, 24 were associated with previously reported showers from the IAU catalogue while 34 showers are new and not listed in the catalogue. Our searching method combined with our large data sample provides unprecedented accuracy in measuring meteor shower activity and description of shower characteristics in the Southern Hemisphere. Using simple modeling and clustering methods we also propose potential parent bodies for the newly discovered showers.

A Probabilistic Assessment of the Next Geomagnetic Reversal

Science.gov (United States)

Buffett, Bruce; Davis, William

2018-02-01

Deterministic forecasts for the next geomagnetic reversal are not feasible due to large uncertainties in the present-day state of the Earth's core. A more practical approach relies on probabilistic assessments using paleomagnetic observations to characterize the amplitude of fluctuations in the geomagnetic dipole. We use paleomagnetic observations for the past 2 Myr to construct a stochastic model for the axial dipole field and apply well-established methods to evaluate the probability of the next geomagnetic reversal as a function of time. For a present-day axial dipole moment of 7.6 × 1022 A m2, the probability of the dipole entering a reversed state is less than 2% after 20 kyr. This probability rises to 11% after 50 kyr. An imminent geomagnetic reversal is not supported by paleomagnetic observations. The current rate of decline in the dipole moment is unusual but within the natural variability predicted by the stochastic model.

An Impending geomagnetic transition? Hints from the past.

Directory of Open Access Journals (Sweden)

Carlo eLAJ

2015-10-01

Full Text Available The rapid decrease of the geomagnetic field intensity in the last centuries has led to speculations that an attempt to a reversal or an excursion might be under way. Here we investigate this hypothesis by examining past records of geomagnetic field intensity obtained from sedimentary cores and from the study of cosmogenic nuclides. The selected records describe geomagnetic changes with an unprecedented temporal resolution between 20 and 75 kyr B.P. We find that some aspects of the present-day geomagnetic field have some similarities with those documented for the Laschamp excursion 41 kyr ago. Under the assumption that the dynamo processes for an eventual future reversal or excursion would be similar to those of the Laschamp excursion, we tentatively suggest that, whilst irreversible processes that will drive the geodynamo into a polarity change may have already started, a reversal or an excursion should not be expected before 500 to 1000 years.

Developing Dynamic Single Page Web Applications Using Meteor : Comparing JavaScript Frameworks: Blaze and React

OpenAIRE

Yetayeh, Asabeneh

2017-01-01

This paper studies Meteor which is a JavaScript full-stack framework to develop interactive single page web applications. Meteor allows building web applications entirely in JavaScript. Meteor uses Blaze, React or AngularJS as a view layer and Node.js and MongoDB as a back-end. The main purpose of this study is to compare the performance of Blaze and React. A multi-user Blaze and React web applications with similar HTML and CSS were developed. Both applications were deployed on Heroku’s w...

Influence of geomagnetic activity and atmospheric pressure in hypertensive adults

Science.gov (United States)

Azcárate, T.; Mendoza, B.

2017-09-01

We performed a study of the systolic and diastolic arterial blood pressure behavior under natural variables such as the atmospheric pressure and the horizontal geomagnetic field component. We worked with a group of eight adult hypertensive volunteers, four men and four women, with ages between 18 and 27 years in Mexico City during a geomagnetic storm in 2014. The data was divided by gender, age, and day/night cycle. We studied the time series using three methods: correlations, bivariate analysis, and superposed epoch (within a window of 2 days around the day of occurrence of a geomagnetic storm) analysis, between the systolic and diastolic blood pressure and the natural variables. The correlation analysis indicated a correlation between the systolic and diastolic blood pressure and the atmospheric pressure and the horizontal geomagnetic field component, being the largest during the night. Furthermore, the correlation and bivariate analyses showed that the largest correlations are between the systolic and diastolic blood pressure and the horizontal geomagnetic field component. Finally, the superposed epoch analysis showed that the largest number of significant changes in the blood pressure under the influence of geomagnetic field occurred in the systolic blood pressure for men.

Influence of geomagnetic activity and atmospheric pressure in hypertensive adults.

Science.gov (United States)

Azcárate, T; Mendoza, B

2017-09-01

We performed a study of the systolic and diastolic arterial blood pressure behavior under natural variables such as the atmospheric pressure and the horizontal geomagnetic field component. We worked with a group of eight adult hypertensive volunteers, four men and four women, with ages between 18 and 27 years in Mexico City during a geomagnetic storm in 2014. The data was divided by gender, age, and day/night cycle. We studied the time series using three methods: correlations, bivariate analysis, and superposed epoch (within a window of 2 days around the day of occurrence of a geomagnetic storm) analysis, between the systolic and diastolic blood pressure and the natural variables. The correlation analysis indicated a correlation between the systolic and diastolic blood pressure and the atmospheric pressure and the horizontal geomagnetic field component, being the largest during the night. Furthermore, the correlation and bivariate analyses showed that the largest correlations are between the systolic and diastolic blood pressure and the horizontal geomagnetic field component. Finally, the superposed epoch analysis showed that the largest number of significant changes in the blood pressure under the influence of geomagnetic field occurred in the systolic blood pressure for men.

Geometric effects of ICMEs on geomagnetic storms

Science.gov (United States)

Cho, KyungSuk; Lee, Jae-Ok

2017-04-01

It has been known that the geomagnetic storm is occurred by the interaction between the Interplanetary Coronal Mass Ejection (ICME) and the Earth's magnetosphere; especially, the southward Bz component of ICME is thought as the main trigger. In this study, we investigate the relationship between Dst index and solar wind conditions; which are the southward Bz, electric field (VBz), and time integral of electric field as well as ICME parameters derived from toroidal fitting model in order to find what is main factor to the geomagnetic storm. We also inspect locations of Earth in ICMEs to understand the geometric effects of the Interplanetary Flux Ropes (IFRs) on the geomagnetic storms. Among 59 CDAW ICME lists, we select 30 IFR events that are available by the toroidal fitting model and classify them into two sub-groups: geomagnetic storms associated with the Magnetic Clouds (MCs) and the compression regions ahead of the MCs (sheath). The main results are as follows: (1) The time integral of electric field has a higher correlation coefficient (cc) with Dst index than the other parameters: cc=0.85 for 25 MC events and cc=0.99 for 5 sheath events. (2) The sheath associated intense storms (Dst ≤-100nT) having usually occur at flank regions of ICMEs while the MC associated intense storms occur regardless of the locations of the Earth in ICMEs. The strength of a geomagnetic storm strongly depends on electric field of IFR and durations of the IFR passages through the Earth.

A comprehensive analysis of the geomagnetic storms occurred dur

Directory of Open Access Journals (Sweden)

Essam Ghamry

2016-06-01

Full Text Available The Geomagnetic storms are considered as one of the major natural hazards. Egyptian geomagnetic observatories observed multiple geomagnetic storms during 18 February to 2 March 2014. During this period, four interplanetary shocks successively hit the Earth’s magnetosphere, leading to four geomagnetic storms. The storm onsets occurred on 18, 20, 23 and 27 February. A non-substorm Pi2 pulsation was observed on 26 February. This Pi2 pulsation was detected in Egyptian observatories (Misallat and Abu Simbel, Kakioka station in Japan and Carson City station in US with nearly identical waveforms. Van Allen Probe missions observed non-compressional Pc4 pulsations on the recovery phase of the third storm. This Pc4 event is may be likely attributed to the decay of the ring current in the recovery phase.

Characteristic features of the geomagnetic field of the Earth

International Nuclear Information System (INIS)

Petrova, G.N.

1978-01-01

The laws of the earth magnetism permitting to make a model of the earth magnetic field are popularly investigated. The modern methods of investigations used in the development of geomagnetism and determining the quantity and direction of the earth magnetic field from the moment of rock formation are described. Considered are the characteristic peculiarities of geomagnetic field: the inclination of the magnetic axis to the rotational axis of the Earth, the western drift of the geomagnetic field, the magnetic field asymmetry, its pole exchange and secular variations. The sources of the continuous magnetic field are investigated. The theory of hydromagnatic dinamo operating in the earth core is described. According to the invariance of the geomagnetic field characteristics it is possible to assume that the core has not significantly evolved for milliard years

Research on Stealthy Headphone Detector Based on Geomagnetic Sensor

Directory of Open Access Journals (Sweden)

Liu Ya

2016-01-01

Full Text Available A kind of stealth headphone detector based on geomagnetic sensor has been developed to deal with the stealth headphones which are small, extremely stealthy and hard to detect. The U.S. PNI geomagnetic sensor is chosen to obtain magnetic field considering the strong magnetic performance of stealth headphones. The earth’s magnetic field at the geomagnetic sensor is eliminated by difference between two geomagnetic sensors, and then weak variations of magnetic field is detected. STM8S103K2 is chosen as the central controlling chip, which is connected to LED, buzzer and LCD 1602. As shown by the experimental results, the probe is not liable to damage by the magnetic field and the developed device has high sensitivity, low False Positive Rate (FAR and satisfactory reliability.

Biological effects of geomagnetic storms

International Nuclear Information System (INIS)

Chibisov, S.M.; Breus, T.K.; Levitin, A.E.; Drogova, G.M.; AN SSSR, Moscow; AN SSSR, Moscow

1995-01-01

Six physiological parameters of cardio-vascular system of rabbits and ultrastructure of cardiomyocytes were investigated during two planetary geomagnetic storms. At the initial and main phase of the storm the normal circadian structure in each cardiovascular parameter was lost. The disynchronozis was growing together with the storm and abrupt drop of cardia activity was observed during the main phase of storm. The main phase of storm followed by the destruction and degradation of cardiomyocytes. Parameters of cardia activity became substantially synchronized and characterized by circadian rhythm structure while the amplitude of deviations was still significant at the recovery stage of geomagnetic storm. 3 refs.; 7 figs

Fluxgate Magnetometer Array for Geomagnetic Abnormal Phenomena Tracking

Directory of Open Access Journals (Sweden)

Xiaomei Wang

2011-06-01

Full Text Available The objective of this project is to develop a flexible observation mode for a geomagnetic abnormal phenomena tracking system. The instrument, based on ring core fluxgate magnetometer technology, improves the field environment performance. Using wireless technology provides on-the-spot mobile networking for the observational data, with efficient access to the earthquake precursor observation network. It provides a powerful detection method for earthquake short-term prediction through installation of a low-noise fluxgate magnetometer array, intensely observing the phenomenon of geomagnetic disturbances and abnormal low-frequency electromagnetic signals in different latitudes, then carrying out observational data processing and exploring the relationship between earthquake activity and geomagnetic field changes.

Geomagnetic Storm Sudden Commencements

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Storm Sudden Commencements (ssc) 1868 to present: STORM1 and STORM2 Lists: (Some text here is taken from the International Association of Geomagnetism and Aeronomy...

Improvements in geomagnetic observatory data quality

DEFF Research Database (Denmark)

Reda, Jan; Fouassier, Danielle; Isac, Anca

2011-01-01

between observatories and the establishment of observatory networks has harmonized standards and practices across the world; improving the quality of the data product available to the user. Nonetheless, operating a highquality geomagnetic observatory is non-trivial. This article gives a record...... of the current state of observatory instrumentation and methods, citing some of the general problems in the complex operation of geomagnetic observatories. It further gives an overview of recent improvements of observatory data quality based on presentation during 11th IAGA Assembly at Sopron and INTERMAGNET...

The Contribution of a Geophysical Data Service: The International Service of Geomagnetic Indices

Directory of Open Access Journals (Sweden)

M Menvielle

2013-01-01

Full Text Available Geomagnetic indices are basic data in Solar-Terrestrial physics and in operational Space Weather activities. The International Service of Geomagnetic Indices (ISGI is in charge of the derivation and dissemination of the geomagnetic indices that are acknowledged by the International Association of Geomagnetism and Aeronomy (IAGA, an IUGG association. Institutes that are not part of ISGI started early in the Internet age to circulate on-line preliminary values of geomagnetic indices. In the absence of quality stamping, this resulted in a very confusing situation. The ISGI label was found to be the simplest and the safest way to insure quality stamping of circulated geomagnetic indices.

Building single-page web apps with meteor

CERN Document Server

Vogelsteller, Fabian

2015-01-01

If you are a web developer with basic knowledge of JavaScript and want to take on Web 2.0, build real-time applications, or simply want to write a complete application using only JavaScript and HTML/CSS, this is the book for you.This book is based on Meteor 1.0.

Intermittency and multifractional Brownian character of geomagnetic time series

Directory of Open Access Journals (Sweden)

G. Consolini

2013-07-01

Full Text Available The Earth's magnetosphere exhibits a complex behavior in response to the solar wind conditions. This behavior, which is described in terms of mutifractional Brownian motions, could be the consequence of the occurrence of dynamical phase transitions. On the other hand, it has been shown that the dynamics of the geomagnetic signals is also characterized by intermittency at the smallest temporal scales. Here, we focus on the existence of a possible relationship in the geomagnetic time series between the multifractional Brownian motion character and the occurrence of intermittency. In detail, we investigate the multifractional nature of two long time series of the horizontal intensity of the Earth's magnetic field as measured at L'Aquila Geomagnetic Observatory during two years (2001 and 2008, which correspond to different conditions of solar activity. We propose a possible double origin of the intermittent character of the small-scale magnetic field fluctuations, which is related to both the multifractional nature of the geomagnetic field and the intermittent character of the disturbance level. Our results suggest a more complex nature of the geomagnetic response to solar wind changes than previously thought.

How the geomagnetic field vector reverses polarity

Science.gov (United States)

Prevot, M.; Mankinen, E.A.; Gromme, C.S.; Coe, R.S.

1985-01-01

A highly detailed record of both the direction and intensity of the Earth's magnetic field as it reverses has been obtained from a Miocene volcanic sequence. The transitional field is low in intensity and is typically non-axisymmetric. Geomagnetic impulses corresponding to astonishingly high rates of change of the field sometimes occur, suggesting that liquid velocity within the Earth's core increases during geomagnetic reversals. ?? 1985 Nature Publishing Group.

Shannon information of the geomagnetic field for the past 7000 years

Directory of Open Access Journals (Sweden)

A. De Santis

2010-02-01

Full Text Available The present behaviour of the geomagnetic field as expressed by the International Geomagnetic Reference Field (IGRF deserves special attention when compared with that shown over the past few thousands of years by two paleomagnetic/archeomagnetic models, CALS3K and CALS7K. The application of the Information theory in terms of Shannon Information and K-entropy to these models shows characteristics of an instable geomagnetic field. Although the result is mitigated when we correct the CALS7K model for its typical spectral damping, the present geomagnetic field as represented by IGRF is still rather distinct, at least for the past 4000 years, a result that is further confirmed by the CALS3K model. This is consistent with a significant global critical state started at around 1750, and still present, characterised by significant decays of the geomagnetic dipole, energy and Shannon information and high K-entropy. The details of how these characteristics may develop are not clear, since the present state could move toward an excursion or a geomagnetic polarity reversal, but we cannot exclude the possibility that the "critical" behaviour will become again more "normal", stopping the apparent trend of the recent geomagnetic field decay.

Analysis of Geomagnetic Field Variations during Total Solar Eclipses Using INTERMAGNET Data

Science.gov (United States)

KIM, J. H.; Chang, H. Y.

2017-12-01

We investigate variations of the geomagnetic field observed by INTERMAGNET geomagnetic observatories over which the totality path passed during a solar eclipse. We compare results acquired by 6 geomagnetic observatories during the 4 total solar eclipses (11 August 1999, 1 August 2008, 11 July 2010, and 20 March 2015) in terms of geomagnetic and solar ecliptic parameters. These total solar eclipses are the only total solar eclipse during which the umbra of the moon swept an INTERMAGNET geomagnetic observatory and simultaneously variations of the geomagnetic field are recorded. We have confirmed previous studies that increase BY and decreases of BX, BZ and F are conspicuous. Interestingly, we have noted that variations of geomagnetic field components observed during the total solar eclipse at Isla de Pascua Mataveri (Easter Island) in Chile (IPM) in the southern hemisphere show distinct decrease of BY and increases of BX and BZ on the contrary. We have found, however, that variations of BX, BY, BZ and F observed at Hornsund in Norway (HRN) seem to be dominated by other geomagnetic occurrence. In addition, we have attempted to obtain any signatures of influence on the temporal behavior of the variation in the geomagnetic field signal during the solar eclipse by employing the wavelet analysis technique. Finally, we conclude by pointing out that despite apparent success a more sophisticate and reliable algorithm is required before implementing to make quantitative comparisons.

Geomagnetic Indices Bulletin (GIB)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Geomagnetic Indices Bulletin is a one page sheet containing the magnetic indices Kp, Ap, Cp, An, As, Am and the provisional aa indices. The bulletin is published...

Long-term trends of foE and geomagnetic activity variations

Directory of Open Access Journals (Sweden)

A. V. Mikhailov

2003-03-01

Full Text Available A relationship between foE trends and geomagnetic activity long-term variations has been revealed for the first time. By analogy with earlier obtained results on the foF2 trends it is possible to speak about the geomagnetic control of the foE long-term trends as well. Periods of increasing geomagnetic activity correspond to negative foE trends, while these trends are positive for the decreasing phase of geomagnetic activity. This "natural" relationship breaks down around 1970 (on some stations later when pronounced positive foE trends have appeared on most of the stations considered. The dependence of foE trends on geomagnetic activity can be related with nitric oxide variations at the E-layer heights. The positive foE trends that appeared after the "break down" effect may also be explained by the [NO] decrease which is not related to geomagnetic activity variations. But negative trends or irregular foE variations on some stations for the same time period require some different mechanism. Chemical pollution of the lower thermosphere due to the anthropogenic activity may be responsible for such abnormal foE behavior after the end of the 1960s.Key words. Ionosphere (ionosphere-atmosphere interactions; ionospheric disturbances

Spectroscopic Observations of the 2011 Draconids Meteor Shower

Czech Academy of Sciences Publication Activity Database

Rudawska, R.; Zender, J.; Jenniskens, P.; Vaubaillon, J.; Koten, Pavel; Margonis, A.; Toth, J.; McAuliffe, J.; Koschny, D.

2014-01-01

Roč. 112, 1-4 (2014), s. 45-57 ISSN 0167-9295 R&D Projects: GA ČR GA205/09/1302 Institutional support: RVO:67985815 Keywords : meteorites * meteors * meteoroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.667, year: 2014

Geomagnetic field evolution during the Laschamp excursion

Science.gov (United States)

Leonhardt, Roman; Fabian, Karl; Winklhofer, Michael; Ferk, Annika; Laj, Carlo; Kissel, Catherine

2009-02-01

Since the last geomagnetic reversal, 780,000 years ago, the Earth's magnetic field repeatedly dropped dramatically in intensity. This has often been associated with large variations in local field direction, but without a persistent global polarity flip. The structure and dynamics of geomagnetic excursions, and especially the difference between excursions and polarity reversals, have remained elusive so far. For the best documented excursion, the Laschamp event at 41,000 years BP, we have reconstructed the evolution of the global field morphology by using a Bayesian inversion of several high-resolution palaeomagnetic records. We have obtained an excursion scenario in which inverse magnetic flux patches at the core-mantle boundary emerge near the equator and then move poleward. Contrary to the situation during the last reversal (Leonhardt, R., Fabian, K., 2007. Paleomagnetic reconstruction of the global geomagnetic field evolution during the Matuyama/Brunhes transition: Iterative Bayesian inversion and independent verification. Earth Planet. Sci. Lett. 253, 172-195), these flux patches do not cross the hydrodynamic boundary of the inner-core tangent cylinder. While the last geomagnetic reversal began with a substantial increase in the strength of the non-dipolar field components, prior to the Laschamp excursion, both dipolar and non-dipolar field decay at the same rate. This result suggests that the nature of an upcoming geomagnetic field instability can be predicted several hundred years in advance. Even though during the Laschamp excursion the dipolar field at the Earth's surface was dominant, the reconstructed dynamic non-dipolar components lead to considerable deviations among predicted records at different locations. The inverse model also explains why at some locations no directional change during the Laschamp excursion is observed.

The determination of parameters of the upper atmosphere by the radio-meteor measurements

Science.gov (United States)

Shamukov, Damir; Fahrutdinova, Antonina; Nugmanov, Ildus

Study of the parameters of the upper atmosphere on the basis of amplitude-time characteristics of meteor ionization. Together with various methods meteor observations (optical, photographic, visual, spectral, television), the most effective modern method of studying meteors means is radar. The development of modern radar technology allows us to apply this tool to monitor meteors. This method allows to determine the parameters of temperature and atmospheric pressure. Actual issue is the development of methods of determining the coefficient of ambipolar diffusion, pressure, density and temperature of the atmosphere in the meteor zone. Graph of amplitude-time characteristic has the exponential form. This fact allows to determine the coefficient of ambipolar diffusion. New algorithm for estimation of the ambipolar diffusion coefficient based on a set of statistical methods and techniques of digital signal processing. There are decomposition of data on singular values and Prony's method. This method of modeling the sample data as a linear combination of exponential. Prony’s method approximates the amplitude-time characteristics of using a deterministic exponential model. Input data is amplitude-time characteristics of the meteor trail x[1]…x[N]. The method allows to estimate x[n] p-membered exponential model: begin{center} x[n]=Sigma2A_{k}exp[a _{k}(n-1)]Cos[2Pif_{k}(n-1)T+Fi_{k}] (1) end{center} 1<=n<=N, T - time range in seconds, A_{k} and a_{k} - amplitude and damping coefficient, f_{k} and Fi_{k} - frequency and initial phase. The equation describing the decay of radio signal: begin{center} A=A_{0}exp(-16Pi^{2}$D_{a}t/λ (2) ). (2) lambdaλ - radar wavelength. The output of the algorithm - the ambipolar diffusion coefficient values D_{a}. begin{center} T=0.5lnD-T_{0}+mg/2kT_{0} (3) Last equation allows to obtain temperature values using the coefficient of ambipolar diffusion depends on the height.

Definitions of terms in meteor astronomy

Science.gov (United States)

Koschny, Detlef; Borovicka, Jiri

2017-10-01

Over the last year, the IAU commission F1 (Meteors, Meteorites and Interplanetary Dust) has discussed and agreed a new definition of terminology related to our field of interest. It is available online at this link: https://www.iau.org/static/science/scientific_bodies/commissions/f1/meteordefinitions_approved.pdf. For your convenience it is reproduced here. Please keep these definitions in mind in any future communications about our topic.

Re-Evaluation of Geomagnetic Field Observation Data at Syowa Station, Antarctica

Directory of Open Access Journals (Sweden)

K Takahashi

2013-05-01

Full Text Available The Japanese Antarctic Research Expedition has conducted geomagnetic observations at Syowa Station, Antarctica, since 1966. Geomagnetic variation data measured with a fluxgate magnetometer are not absolute but are relative to a baseline and show drift. To enhance the importance of the geomagnetic data at Syowa Station, therefore, it is necessary to correct the continuous variation data by using absolute baseline values acquired by a magnetic theodolite and proton magnetometer. However, the database of baseline values contains outliers. We detected outliers in the database and then converted the geomagnetic variation data to absolute values by using the reliable baseline values.

Latitude dependence of long-term geomagnetic activity and its solar wind drivers

Energy Technology Data Exchange (ETDEWEB)

Myllys, M. [Helsinki Univ. (Finland). Dept. of Physics; Partamies, N. [Finnish Meteorological Institute, Helsinki (Finland); University Centre in Svalbard, Longyearbyen (Norway). Dept. of Arctic Geophysics; Juusola, L. [Finnish Meteorological Institute, Helsinki (Finland)

2015-09-01

To validate the usage of global indices in studies of geomagnetic activity, we have examined the latitude dependence of geomagnetic variations in Fennoscandia and Svalbard from 1994 to 2010. Daily standard deviation (SD) values of the horizontal magnetic field have been used as a measure of the ground magnetic disturbance level.We found that the timing of the geomagnetic minimum depends on the latitude region: corresponding to the minimum of sunspot cycle 22 (in 1996), the geomagnetic minimum occurred between the geomagnetic latitudes 57-61 in 1996 and at the latitudes 64-67 in 1997, which are the average auroral oval latitudes. During sunspot cycle 23, all latitude regions experienced the minimum in 2009, a year after the sunspot minimum. These timing differences are due to the latitude dependence of the 10 s daily SD on the different solar wind drivers. In the latitude region of 64-67 , the impact of the high-speed solar wind streams (HSSs) on the geomagnetic activity is the most pronounced compared to the other latitude groups, while in the latitude region of 57-61 , the importance of the coronal mass ejections (CMEs) dominates. The geomagnetic activity maxima during ascending solar cycle phases are typically caused by CME activity and occur especially in the oval and sub-auroral regions. The strongest geomagnetic activity occurs during the descending solar cycle phases due to a mixture of CME and HSS activity. Closer to the solar minimum, less severe geomagnetic activity is driven by HSSs and mainly visible in the poleward part of the auroral region. According to our study, however, the timing of the geomagnetic activity minima (and maxima) in different latitude bands is different, due to the relative importance of different solar wind drivers at different latitudes.

Latitude dependence of long-term geomagnetic activity and its solar wind drivers

International Nuclear Information System (INIS)

Myllys, M.

2015-01-01

To validate the usage of global indices in studies of geomagnetic activity, we have examined the latitude dependence of geomagnetic variations in Fennoscandia and Svalbard from 1994 to 2010. Daily standard deviation (SD) values of the horizontal magnetic field have been used as a measure of the ground magnetic disturbance level.We found that the timing of the geomagnetic minimum depends on the latitude region: corresponding to the minimum of sunspot cycle 22 (in 1996), the geomagnetic minimum occurred between the geomagnetic latitudes 57-61 in 1996 and at the latitudes 64-67 in 1997, which are the average auroral oval latitudes. During sunspot cycle 23, all latitude regions experienced the minimum in 2009, a year after the sunspot minimum. These timing differences are due to the latitude dependence of the 10 s daily SD on the different solar wind drivers. In the latitude region of 64-67 , the impact of the high-speed solar wind streams (HSSs) on the geomagnetic activity is the most pronounced compared to the other latitude groups, while in the latitude region of 57-61 , the importance of the coronal mass ejections (CMEs) dominates. The geomagnetic activity maxima during ascending solar cycle phases are typically caused by CME activity and occur especially in the oval and sub-auroral regions. The strongest geomagnetic activity occurs during the descending solar cycle phases due to a mixture of CME and HSS activity. Closer to the solar minimum, less severe geomagnetic activity is driven by HSSs and mainly visible in the poleward part of the auroral region. According to our study, however, the timing of the geomagnetic activity minima (and maxima) in different latitude bands is different, due to the relative importance of different solar wind drivers at different latitudes.

MU head echo observations of the 2010 Geminids: radiant, orbit, and meteor flux observing biases

Directory of Open Access Journals (Sweden)

J. Kero

2013-03-01

Full Text Available We report Geminid meteor head echo observations with the high-power large-aperture (HPLA Shigaraki middle and upper atmosphere (MU radar in Japan (34.85° N, 136.10° E. The MU radar observation campaign was conducted from 13 December 2010, 08:00 UTC to 15 December, 20:00 UTC and resulted in 48 h of radar data. A total of ~ 270 Geminids were observed among ~ 8800 meteor head echoes with precisely determined orbits. The Geminid head echo activity is consistent with an earlier peak than the visual Geminid activity determined by the International Meteor Organization (IMO. The observed flux of Geminids is a factor of ~ 3 lower than the previously reported flux of the 2009 Orionids measured with an identical MU~radar setup. We use the observed flux ratio to discuss the relation between the head echo mass–velocity selection effect, the mass distribution indices of meteor showers and the mass threshold of the MU radar.

Variations in the geomagnetic and gravitational background associated with two strong earthquakes of the May 2012 sequence in the Po Valley Plain (Italy).

Science.gov (United States)

Straser, Valentino

2013-04-01

, extension, intensity, etc..) compatible with: the classification by IAGA (International Association of Geomagnetism and Aeronomy) of geomagnetic pulsations; emissions of an anthropic type; known natural emissions (Whistler, Chorus, lightning, electrophonic meteoric sounds, plasma, etc..). For this reason, since Radio anomalies are not related to known phenomena they were considered in this study as candidate seismic precursors. Most of the radio anomalies are observed below 32Hz and, generally, between 0.1 and 20Hz and occur in association with an intense increase in the geomagnetic background that precedes the occurrence of a seismic event.

Uncertainty Quantification in Geomagnetic Field Modeling

Science.gov (United States)

Chulliat, A.; Nair, M. C.; Alken, P.; Meyer, B.; Saltus, R.; Woods, A.

2017-12-01

Geomagnetic field models are mathematical descriptions of the various sources of the Earth's magnetic field, and are generally obtained by solving an inverse problem. They are widely used in research to separate and characterize field sources, but also in many practical applications such as aircraft and ship navigation, smartphone orientation, satellite attitude control, and directional drilling. In recent years, more sophisticated models have been developed, thanks to the continuous availability of high quality satellite data and to progress in modeling techniques. Uncertainty quantification has become an integral part of model development, both to assess the progress made and to address specific users' needs. Here we report on recent advances made by our group in quantifying the uncertainty of geomagnetic field models. We first focus on NOAA's World Magnetic Model (WMM) and the International Geomagnetic Reference Field (IGRF), two reference models of the main (core) magnetic field produced every five years. We describe the methods used in quantifying the model commission error as well as the omission error attributed to various un-modeled sources such as magnetized rocks in the crust and electric current systems in the atmosphere and near-Earth environment. A simple error model was derived from this analysis, to facilitate usage in practical applications. We next report on improvements brought by combining a main field model with a high resolution crustal field model and a time-varying, real-time external field model, like in NOAA's High Definition Geomagnetic Model (HDGM). The obtained uncertainties are used by the directional drilling industry to mitigate health, safety and environment risks.

Geomagnetic fluctuations during a polarity transition

Science.gov (United States)

Audunsson, Haraldur; Levi, Shaul

1997-01-01

The extensive Roza Member of the Columbia River Basalt Group (Washington State) has intermediate paleomagnetic directions, bracketed by underlying normal and overlying reverse polarity flows. A consistent paleomagnetic direction was measured at 11 widely distributed outcrops; the average direction has a declination of 189° and an inclination of -5°, with greater variation in the inclination [Rietman, 1966]. In this study the Roza Member was sampled in two Pasco Basin drillcores, where it is a single cooling unit and its thickness exceeds 50 m. Excellent core recovery allowed uniform and dense sampling of the drillcores. During its protracted cooling, the Roza flow in the drillcores recorded part of a 15.5 Ma geomagnetic polarity transition. The inclination has symmetric, quasicyclic intraflow variation, while the declination is nearly constant, consistent with the results from the outcrops. Thermal models of the cooling flow provide the timing for remanence acquisition. The inclination is inferred to have progressed from 0° to -15° and back to -3°over a period of 15 to 60 years, at rates of 1.6° to 0.5°/yr. Because the geomagnetic intensity was probably weak during the transition, these apparently high rates of change are not significantly different from present-day secular variation. These results agree with the hypothesis that normal secular variation persists through geomagnetic transitions. The Iow-amplitude quasicyclical fluctuations of the field over tens of years, recorded by Roza, suggest that the geomagnetic field reverses in discrete steps, and that more than 15-60 years were required to complete this reversal.

Geomagnetic Observatory Database February 2004

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) maintains an active database of worldwide geomagnetic observatory...

Changes of 2H and 18O enrichment of meteoric water and Pleistocene glaciation

International Nuclear Information System (INIS)

Harmon, R.S.; Schwarcz, H.P.

1981-01-01

Isotopic data on fluid inclusions and host speleothems are presented which support the hypothesis that the deltaD-delta 18 O relationship for modern meteoric waters may have changed during the Pleistocene glacial periods in response to increased ocean surface air humidity. Palaeotemperatures for five areas of east-central North America and Bermuda, calculated assuming the present deltaDdelta 18 O meteoric water relationship for fluid inclusion waters, are observed to be too low during late Pleistocene glacial periods (in some instances falling below O 0 C) while interglacial palaeotemperatures are largely equivalent to those in the areas at present. As speleothem deposition cannot occur at subzero temperatures, a possible solution to this dilemma is a shift in the intercept of the meteoric water relationship. (U.K.)

Geomagnetic matching navigation algorithm based on robust estimation

Science.gov (United States)

Xie, Weinan; Huang, Liping; Qu, Zhenshen; Wang, Zhenhuan

2017-08-01

The outliers in the geomagnetic survey data seriously affect the precision of the geomagnetic matching navigation and badly disrupt its reliability. A novel algorithm which can eliminate the outliers influence is investigated in this paper. First, the weight function is designed and its principle of the robust estimation is introduced. By combining the relation equation between the matching trajectory and the reference trajectory with the Taylor series expansion for geomagnetic information, a mathematical expression of the longitude, latitude and heading errors is acquired. The robust target function is obtained by the weight function and the mathematical expression. Then the geomagnetic matching problem is converted to the solutions of nonlinear equations. Finally, Newton iteration is applied to implement the novel algorithm. Simulation results show that the matching error of the novel algorithm is decreased to 7.75% compared to the conventional mean square difference (MSD) algorithm, and is decreased to 18.39% to the conventional iterative contour matching algorithm when the outlier is 40nT. Meanwhile, the position error of the novel algorithm is 0.017° while the other two algorithms fail to match when the outlier is 400nT.

Geomagnetic observations on Tristan da Cunha, South Atlantic Ocean

DEFF Research Database (Denmark)

Matzka, J.; Olsen, Nils; Maule, C. F.

2009-01-01

Few geomagnetic ground observations exist of the Earth's strongest core field anomaly, the South Atlantic Anomaly (SAA). The geomagnetic repeat station on the island Tristan da Cunha, located half-way between South Africa and South America at 37 degrees 05' S, 12 degrees 18' W, is therefore of cr...

Expected Increase of Activity of Eta Aquariids Meteor Shower

Science.gov (United States)

Kulikova, N. V.; Chepurova, V. M.

2018-04-01

Analysis of the results of modeling disintegration of Comet 1P/Halley after its flare in 1991 has allowed us to predict an increase of the activity of the associated Eta Aquariids meteor shower in April-May 2018.

Mid-latitude Geomagnetic Field Analysis Using BOH Magnetometer: Preliminary Results

Directory of Open Access Journals (Sweden)

Junga Hwang

2011-09-01

Full Text Available Korea Astronomy and Space Science Institute researchers have installed and operated magnetometers at Mt. Bohyun Observatory to measure the Earth's magnetic field variations in South Korea. We, in 2007, installed a fluxgate magnetometer (RFP-523C to measure H, D, and Z components of the geomagnetic field. In addition, in 2009, we installed a Overhauser proton sensor to measure the absolute total magnetic field F and a three-axis magneto-impedance sensor for spectrum analysis. Currently three types of magnetometer data have been accumulated. In this paper, we provide the preliminary and the first statistical analysis using the BOH magnetometer installed at Mt. Bohyun Observatory. By superposed analysis, we find that daily variations of H, D, and Z shows similar tendency, that is, about 30 minutes before the meridian (11:28 a minimum appears and the time after about 3 hours and 30 minutes (15:28 a maximum appears. Also, a quiet interval start time (19:06 is near the sunset time, and a quiet interval end time (06:40 is near the sunrise time. From the sunset to the sunrise, the value of H has a nearly constant interval, that is, the sun affects the changes in H values. Seasonal variations show similar dependences to the sun. Local time variations show that noon region has the biggest variations and midnight region has the smallest variations. We compare the correlations between geomagnetic variations and activity indices as we expect the geomagnetic variation would contain the effects of geomagnetic activity variations. As a result, the correlation coefficient between H and Dst is the highest (r = 0.947, and other AL, AE, AU index and showed a high correlation. Therefore, the effects of geomagnetic storms and geomagnetic substorms might contribute to the geomagnetic changes significantly.

Improving geomagnetic observatory data in the South Atlantic Anomaly

Science.gov (United States)

Matzka, Jürgen; Morschhauser, Achim; Brando Soares, Gabriel; Pinheiro, Katia

2016-04-01

The Swarm mission clearly proofs the benefit of coordinated geomagnetic measurements from a well-tailored constellation in order to recover as good as possible the contributions of the various geomagnetic field sources. A similar truth applies to geomagnetic observatories. Their scientific value can be maximised by properly arranging the position of individual observatories with respect to the geometry of the external current systems in the ionosphere and magnetosphere, with respect to regions of particular interest for secular variation, and with respect to regions of anomalous electric conductivity in the ground. Here, we report on our plans and recent efforts to upgrade geomagnetic observatories and to recover unpublished data from geomagnetic observatories at low latitudes in the South Atlantic Anomaly. In particular, we target the magnetic equator with the equatorial electrojet and low latitudes to characterise the Sq- and ring current. The observatory network that we present allows also to study the longitudinal structure of these external current systems. The South Atlantic Anomaly region is very interesting due to its secular variation. We will show newly recovered data and comparisons with existing data sets. On the technical side, we introduce low-power data loggers. In addition, we use mobile phone data transfer, which is rapidly evolving in the region and allows timely data access and quality control at remote sites that previously were not connected to the internet.

Meteor head echo polarization at 930 MHz studied with the EISCAT UHF HPLA radar

Directory of Open Access Journals (Sweden)

G. Wannberg

2011-06-01

Full Text Available The polarization characteristics of 930-MHz meteor head echoes have been studied for the first time, using data obtained in a series of radar measurements carried out with the tristatic EISCAT UHF high power, large aperture (HPLA radar system in October 2009. An analysis of 44 tri-static head echo events shows that the polarization of the echo signal recorded by the Kiruna receiver often fluctuates strongly on time scales of tens of microseconds, illustrating that the scattering process is essentially stochastic. On longer timescales (> milliseconds, more than 90 % of the recorded events show an average polarization signature that is independent of meteor direction of arrival and echo strength and equal to that of an incoherent-scatter return from underdense plasma filling the tristatic observation volume. This shows that the head echo plasma targets scatter isotropically, which in turn implies that they are much smaller than the 33-cm wavelength and close to spherically symmetric, in very good agreement with results from a previous EISCAT UHF study of the head echo RCS/meteor angle-of-incidence relationship. Significant polarization is present in only three events with unique target trajectories. These all show a larger effective target cross section transverse to the trajectory than parallel to it. We propose that the observed polarization may be a signature of a transverse charge separation plasma resonance in the region immediately behind the meteor head, similar to the resonance effects previously discussed in connection with meteor trail echoes by Herlofson, Billam and Browne, Jones and Jones and others.

Telescopic and meteor observation of `Oumuamua, the first known interstellar asteroid

Science.gov (United States)

Ye, Quan-Zhi

2018-04-01

1I/2017 U1 ('Oumuamua), a recently discovered asteroid in a hyperbolic orbit, is the first macroscopic object of extrasolar origin identified in the solar system. I will present imaging and spectroscopic observations of 'Oumuamua as well as a search of meteor activity potentially linked to this object using the Canadian Meteor Orbit Radar. We find that 'Oumuamua exhibits a moderate spectral gradient of 10%+-6% per 100 nm, a value lower than that of outer solar system bodies, indicative of a formation and/or previous residence in a warmer environment. Imaging observation and spectral line analysis show no evidence that 'Oumuamua is presently active. Negative meteor observation is as expected, since ejection driven by sublimation of commonly known cometary species such as CO requires an extreme ejection speed of ~40 m/s at ~100 au in order to reach the Earth. No obvious candidate stars are proposed as the point of origin for 'Oumuamua. Given a mean free path of ~109 ly in the solar neighborhood, 'Oumuamua has likely spent a very long time in interstellar space before encountering the solar system.

Geomagnetic Navigation of Autonomous Underwater Vehicle Based on Multi-objective Evolutionary Algorithm.

Science.gov (United States)

Li, Hong; Liu, Mingyong; Zhang, Feihu

2017-01-01

This paper presents a multi-objective evolutionary algorithm of bio-inspired geomagnetic navigation for Autonomous Underwater Vehicle (AUV). Inspired by the biological navigation behavior, the solution was proposed without using a priori information, simply by magnetotaxis searching. However, the existence of the geomagnetic anomalies has significant influence on the geomagnetic navigation system, which often disrupts the distribution of the geomagnetic field. An extreme value region may easily appear in abnormal regions, which makes AUV lost in the navigation phase. This paper proposes an improved bio-inspired algorithm with behavior constraints, for sake of making AUV escape from the abnormal region. First, the navigation problem is considered as the optimization problem. Second, the environmental monitoring operator is introduced, to determine whether the algorithm falls into the geomagnetic anomaly region. Then, the behavior constraint operator is employed to get out of the abnormal region. Finally, the termination condition is triggered. Compared to the state-of- the-art, the proposed approach effectively overcomes the disturbance of the geomagnetic abnormal. The simulation result demonstrates the reliability and feasibility of the proposed approach in complex environments.

Insights into Meteoric 10Be Dynamics and Climate Stability along the Hawaiian Kohala Climosequence

Science.gov (United States)

Dixon, J. L.; Chadwick, O.

2017-12-01

We measure meteoric 10Be in soils across a well-studied climate gradient spanning Kohala, Hawaii to provide new understanding of the isotope behavior in soils and constraints on nuclide delivery rates to Earth's surface. Annual rainfall across the Kohala climogradient varies from 16 - 300 cm, with Hawaiian soils reflecting evolution over the past 150 ka, the nominal age of the volcanic parent material. We analyzed a sequence of nine soil profiles for meteoric 10Be and compared with previously measured data on soil chemistry and dust fluxes. In the Kohala system, soil inventories of 10Be span 40-300 x 109 atom/cm2 and generally increase linearly with rainfall, consistent with precipitation-driven fluxes and the high retention of 10Be in clay-rich soil horizons. However, nuclide inventories dramatically decrease for soils at rainfall >140 cm/y. The observed decrease corresponds with other strong changes in weathering intensity across the climate gradient, associated with previously studied and recognized pedogenic thresholds. These thresholds represent abrupt transitions in soil chemistry related to increased throughflow of soil solutions, decreases in base saturation and pH, and the destruction of phyllosilicates and replacement with amorphous oxyhydroxides. Meteoric-derived ages, based on 10Be-flux estimates and measured inventories are uniform for dry soils ( 60ka), but far less than the known substrate age (150ka), indicating that actual delivery rates are lower than predicted from current models in this region. Despite the offset in predicted and substrate ages, the consistency in pattern suggests that the rainfall gradient over the 150 thousand years of soil development has not deviated significantly from its present structure. Furthermore, based on clear 10Be losses in soils with high moisture availability, our results indicate meteoric 10Be may not be a robust tracer of soil age and movement in systems with high rainfall and weathering intensity and low soil

Global Ultra-Low-Frequency Geomagnetic Pulsations Associated with the March 24, 1991 Geomagnetic Storm

Directory of Open Access Journals (Sweden)

Nan-Wei Chen Jann-Yenq Liu

2008-01-01

Full Text Available On 24 March 1991, global ultra-low-frequency (ULF pulsations (1.1 - 3.3 mHz observed in the magnetosphere as well as on the ground were studied via analyzing magnetic field data obtained from a global network, comprising ground-based observatories and geosynchronous satellites. In the magnetosphere, the compressional and transverse components of the magnetic fields recorded at two satellites, GOES 6 and GOES 7, showed dominant fluctuations when they were in the vicinity of the noon sector, whereas the transverse fluctuations became dominant when they were at the dawn side. Similarly, on the ground, the H and D components had major fluctuations along with an increase in amplitude from low to high geomagnetic latitudes. In addition, the amplitude of the ULF pulsation was enhanced at the dawn and dusk sides. The geomagnetic pulsations propagated anti-sunward and were of counterclockwise and clockwise elliptical polarizations at the dawn and dusk sides respectively. The counterclockwise elliptical polarization reversed to a clockwise elliptical polarization at geomagnetic local noon and linear polarization was observed during the reversal. It appears that the analysis of the global network data not only provided us with a study of the characteristics of the waves in the magnetosphere and on the ground but also provided us with correlations between the geosynchronous and ground observations, which should be essential to the determination of possible mechanisms of this storm-related wave event.

Ice ages and geomagnetic reversals

Science.gov (United States)

Wu, Patrick

1992-01-01

There have been speculations on the relationship between climatic cooling and polarity reversals of the earth's magnetic field during the Pleistocene. Two of the common criticisms on this relationship have been the reality of these short duration geomagnetic events and the accuracy of their dates. Champion et al. (1988) have reviewed recent progress in this area. They identified a total of 10 short-duration polarity events in the last 1 Ma and 6 of these events have been found in volcanic rocks, which also have K-Ar dates. Supposing that the speculated relationship between climatic cooling and geomagnetic reversals actually exist, two mechanisms that assume climatic cooling causes short period magnetic reversals will be investigated. These two methods are core-mantle boundary topography and transfer of the rotational energy to the core.

Recent investigation at INPE in magnetospheric physics and geomagnetism

International Nuclear Information System (INIS)

Gonzales, W.D.; Trivedi, N.B.

1984-01-01

During recent years the following research activities related to the earth's magnetosphere have been intensified: a) studies on electric field and energy transfer from the solar wind to the magnetosphere; b) studies on high latitude magnetospheric electric fields and on their penetration into the plasmasphere; c) measurements of atmospheric-large scale-electric fields, related to the low latitude magnetospheric-ionospheric coupling and to the local atmospheric electrodynamics, using detectors on board stratospheric balloons; and d) measurements of atmospheric X-rays, related to the process of energetic particle precipitation at the South Atlantic Magnetic Anomaly, using detectors also on board stratospheric balloons. Similarly, the following research activities related to geomagnetism are being pursued: a) studies on the variability of the geomagnetic field and on the dynamics of the equatorial electrojet from local geomagnetic field measurements; b) studies on terrestrial electromagnetic induction through local measurements of the geo-electromagnetic field; and c) studies on the influence of geomagnetic activity on particle precipitation at the South Atlantic Magnetic Anomaly. (Author) [pt

Can the tardigrade Hypsibius dujardini survive in the absence of the geomagnetic field?

Directory of Open Access Journals (Sweden)

Weronika Erdmann

Full Text Available Earth's geomagnetic field has undergone critical changes in the past. Studies on the influence of the magnetic field on Earth's organisms are crucial for the understanding of evolution of life on Earth and astrobiological considerations. Numerous studies conducted both on plants and animals confirmed the significant influence of the geomagnetic field on the metabolism of living organisms. Water bears (Tardigrada, which are a mong the most resistant animals due to their cryptobiotic abilities, show significant resistance to a number of environmental stressors, but the influence of the geomagnetic field on their fitness has not been addressed before. In our studies, we used eutardigrade Hypsibius dujardini to analyse whether isolation from the geomagnetic field had an effect on mortality. We found that Hypsibius dujardini specimens demonstrated relatively high mortality during anhydrobiosis, also in control groups exposed to the normal geomagnetic field. Moreover, similar mortality was observed in anhydrobiotic specimens isolated from the geomagnetic field. However, a significant difference was noted between tardigrade survival and the moment of their isolation from the geomagnetic field. In particular, tardigrade mortality substantially increased in absence of a magnetic field during the process of entering anhydrobiosis and returning to active life. Our results suggest that these processes rely on complex metabolic processes that are critically influenced by the geomagnetic field.

Surface electric fields and geomagnetically induced currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm

OpenAIRE

Thomson, Alan W.P.; McKay, Allan J.; Clarke, Ellen; Reay, Sarah J.

2005-01-01

A surface electric field model is used to estimate the UK surface E field during the 30 October 2003 severe geomagnetic storm. This model is coupled with a power grid model to determine the flow of geomagnetically induced currents (GIC) through the Scottish part of the UK grid. Model data are compared with GIC measurements at four sites in the power network. During this storm, measured and modeled GIC levels exceeded 40 A, and the surface electric field reached 5 V/km at sites in ...

Seasonal temperature variation around the mesopause inferred from a VHF meteor radar at King Sejong Station (62S, 59W), Antarctica

Science.gov (United States)

Kim, Yongha; Kim, Jeong-Han; Lee, Changsup; Jee, Gun-Hwa

A VHF meteor radar, installed at King Sejong Station in March, 2007, has been detecting echoes from more than 20,000 meteors per day. Meteor echoes are decayed typically within seconds as meteors spread away by atmospheric diffusion. The diffusion coefficients can thus be obtained from decay times of meteor echo signals, providing with information on the atmospheric temperatures and pressures at meteor altitudes from 70 to 100 km. In this study, we present altitude profiles of 15-min averaged diffusion coefficients in each month, which clearly show a minimum at 80 - 85 km. The minimum appears at higher altitude during austral summer than winter, and seems to be near the lower level of two temperature minimum structure around the mesopause seen by TIMED/SABER data at high latitudes. The higher mesopause level (95-100 km) of the SABER data does not appear in our diffusion profiles probably because it is too close the limit of meaningful diffusion coefficients that can be derived from meteor decay detection. In order to understand temperature variation around the mesopause more directly, we will discuss various methods to extract temperature profiles from the diffusion profiles. We will also present monthly averaged OH and O2 airglow temperatures observed at the same site, and compare them with those derived from the meteor radar observation.

Properties of Pliocene sedimentary geomagnetic reversal records from the Mediterranean

NARCIS (Netherlands)

Linssen, J.H.

1991-01-01

In the history of the Earth the dipolar geomagnetic field has frequently reversed polarity. Though this property was already known early this century (Brunhes, 1906), nowadays the characteristics and the origin of polarity transitions are still largely unknown. The geomagnetic field and its

''Meteor'' radio/television satellites for study of earth's natural resources

Energy Technology Data Exchange (ETDEWEB)

Selivanov, A S; Tuchin, Yu M

1981-01-01

Two types of wide sweep multi-zonal scanning devices are included in the Meteor units, including radio-transmitting, and memory units. Data is transmitted within the wave range assigned to meteorologic earth satellites.

A Probabilistic Assessment of the Next Geomagnetic Reversal

OpenAIRE

Buffett, B; Davis, W

2018-01-01

©2018. American Geophysical Union. All Rights Reserved. Deterministic forecasts for the next geomagnetic reversal are not feasible due to large uncertainties in the present-day state of the Earth's core. A more practical approach relies on probabilistic assessments using paleomagnetic observations to characterize the amplitude of fluctuations in the geomagnetic dipole. We use paleomagnetic observations for the past 2 Myr to construct a stochastic model for the axial dipole field and apply wel...

Quasi-biennial oscillations in the geomagnetic field: Their global characteristics and origin

DEFF Research Database (Denmark)

Ou, Jiaming; Du, Aimin; Finlay, Chris

2017-01-01

Quasi-biennial oscillations (QBOs), with periods in the range 1–3 years, have been persistently observed in the geomagnetic field. They provide unique information on the mechanisms by which magnetospheric and ionospheric current systems are modulated on interannual timescales and are also of cruc...... primarily originates from the current systems due to the solar wind-magnetosphere-ionosphere coupling process....... postmidnight sectors, and the results from spherical harmonic analysis, verify that the majority of geomagnetic QBO is of external origin. We furthermore find a very high correlation between the geomagnetic QBO and the QBOs in solar wind speed and solar wind dynamic pressure. This suggests the geomagnetic QBO......Quasi-biennial oscillations (QBOs), with periods in the range 1–3 years, have been persistently observed in the geomagnetic field. They provide unique information on the mechanisms by which magnetospheric and ionospheric current systems are modulated on interannual timescales and are also...

A new regard about Surlari National Geomagnetic Observatory

Science.gov (United States)

Asimopolos, Laurentiu; Asimopolos, Natalia-Silvia; Pestina, Agata-Monica

2010-05-01

Geomagnetic field study in Romanian stations has started with irregular measurements in late XIXth century. In 1943, the foundation of Surlari National Geomagnetic Observatory (SNGO) marks the beginning of a new era in the systematic study of geomagnetic field by a continuous registration of its variations and by carrying out standard absolute measurements in a fundamental station. The location of the observatory meets the highest exigencies, being situated in physical-geological conditions of a uniform local field, at a reasonably long distance from human activities. Its laboratories observe strict conditions of non-magnetism, ensuring the possibility of absolute standard measurements (national magnetic standards) for all the units in the country, civil or military, which are endowed with equipment based on geomagnetic metrology. These basic conditions have allowed the observatory to become by developing its initial preoccupations a centre of complex geomagnetic research, constantly involved in national and international issues, promoting new themes in our country and bringing significant contributions. During the last two decades, infrastructure and equipment used in monitoring geomagnetic field at European and planetary level have experienced a remarkable development. New registering techniques have allowed a complete to automate of data acquisition, and sampling step and their precision increased by two classes of size. Systems of transmitting these data in real time to world collecting centres have resulted in the possibility of approaching globalize studies, suitable for following some phenomena at planetary scale. At the same time, a significant development in the procedures of processing primary data has been registered, based on standardized programmes. The new stage of this fundamental research, largely applicable in various fields, is also marked by the simultaneous observation of space-time distribution of terrestrial electromagnetic field by means of

Shannon information of the geomagnetic field for the past 7000 years

OpenAIRE

De Santis, A.; Qamili, E.

2010-01-01

The present behaviour of the geomagnetic field as expressed by the International Geomagnetic Reference Field (IGRF) deserves special attention when compared with that shown over the past few thousands of years by two paleomagnetic/archeomagnetic models, CALS3K and CALS7K. The application of the Information theory in terms of Shannon Information and K-entropy to these models shows characteristics of an instable geomagnetic field. Although the result is mitigated when we correct the CALS7K mode...

Meteors, space aliens, and other exotic encounters

Science.gov (United States)

Tom. Hofacker

1998-01-01

Exotics have had a big impact on our environment. If you do not think so, just look at how many people believe that humans would not exist on this planet were it not for exotics. This belief centers on two main theories: (1) that humans could not have evolved were it not for a huge meteor from outer space striking the earth resulting in extinction of the dinasours, the...

Data Reduction and Control Software for Meteor Observing Stations Based on CCD Video Systems

Science.gov (United States)

Madiedo, J. M.; Trigo-Rodriguez, J. M.; Lyytinen, E.

2011-01-01

The SPanish Meteor Network (SPMN) is performing a continuous monitoring of meteor activity over Spain and neighbouring countries. The huge amount of data obtained by the 25 video observing stations that this network is currently operating made it necessary to develop new software packages to accomplish some tasks, such as data reduction and remote operation of autonomous systems based on high-sensitivity CCD video devices. The main characteristics of this software are described here.

Quasi-two-year cycle in indices of geomagnetic and solar activity

International Nuclear Information System (INIS)

Nuzhdina, M.A.

1986-01-01

The spectral, amplitude and phase analysis of monthly standardized anomalies in the indices of planetary geomagnetic disturbance and Wolf numbers for the 100-year period and 18-year time ranges are carried out. There is a weak correlation between the monthly anomalies of fluctuations of the Wolf numbers and planetary indices of geomagnetic distubance manifesting quasi-two-year cyclic recurrence. There is the quasi-two-year cycle of 26 months average duration in the indices of geomagnetic disturbance and Wolf numbers. The quasi-two-year cycle is a rather wide band with the oscillation periods of 21 to 29 months having different amplitudes and phases. The quasi-two-year cycle in geomagnetism and the Wolf numbers is unstable: for 100 years of observations its components change in amplitude and phase

Linkage between the Biosphere and Geomagnetic field: Knowns and Unknowns

Science.gov (United States)

Pan, Y.; Zhu, R.

2017-12-01

The geomagnetic field extends from Earth's interior into space, and protects our planets habitability by shielding the planet from solar winds and cosmic rays. Recently, single zircon paleomagnetic study provides evidence of the field to ages as old as 4.2 Ga. Many great questions remain, including whether the emergence of life on Earth was a consequence of the field's protection, how organisms utilize the field, and if field variations (polarity reversal, excursion and secular variation) impact the evolution of the biosphere. In the past decade, great efforts have been made to probe these very complex and great challenging questions through the inter-disciplinary subject of biogeomagnetism. Numerous birds, fish, sea turtles, bats and many other organisms utilize the geomagnetic field during orientation and long-distance navigation. We recently found that bats, the second most abundant order of mammals, can use the direction of magnetic field with a weak strength comparable to polarity transitions/excursions, which is indicative of advanced magnetoreception developed in bats co-evolving with the geomagnetic field since the Eocene. Magnetotactic bacteria swim along the geomagnetic field lines by synthesizing intracellular nano-sized and chain-arranged magnetic minerals (magnetosomes). Recent field surveys in China, Europe, America and Australia have shown that these microbes are ubiquitous in aqueous habitats. Both their biogeography distribution and magnetotactic swimming speed are field intensity dependent. On the other hand, it is increasingly accepted that the geomagnetic field influences life through several indirect pathways. For example, it has been discovered that solar wind erosion enhanced the atmospheric oxygen escape during periods of weak magnetic field and global mean ionospheric electron density profiles can be affected by geomagnetic field strength variation. In addition, depletion of the ozone layer during a weak magnetic field could result in

Domino model for geomagnetic field reversals.

Science.gov (United States)

Mori, N; Schmitt, D; Wicht, J; Ferriz-Mas, A; Mouri, H; Nakamichi, A; Morikawa, M

2013-01-01

We solve the equations of motion of a one-dimensional planar Heisenberg (or Vaks-Larkin) model consisting of a system of interacting macrospins aligned along a ring. Each spin has unit length and is described by its angle with respect to the rotational axis. The orientation of the spins can vary in time due to spin-spin interaction and random forcing. We statistically describe the behavior of the sum of all spins for different parameters. The term "domino model" in the title refers to the interaction among the spins. We compare the model results with geomagnetic field reversals and dynamo simulations and find strikingly similar behavior. The aggregate of all spins keeps the same direction for a long time and, once in a while, begins flipping to change the orientation by almost 180 degrees (mimicking a geomagnetic reversal) or to move back to the original direction (mimicking an excursion). Most of the time the spins are aligned or antialigned and deviate only slightly with respect to the rotational axis (mimicking the secular variation of the geomagnetic pole with respect to the geographic pole). Reversals are fast compared to the times in between and they occur at random times, both in the model and in the case of the Earth's magnetic field.

Anomalous changes of vertical geomagnetic field in Kamchatka

Directory of Open Access Journals (Sweden)

Moroz Yuriy

2016-01-01

Full Text Available Secular variations of the vertical geomagnetic field at Paratunka (Kamchatka, Kakioka (Honshu, Mamambetsu (Hokkaido and Patrony (Irkutsk are considered from 1968 to 2014. Comparative analysis of secular variations showed that from 1968 to 2001, similar variations with the intensity of first hundreds on nT are obvious at four observatories. For the following period from 2001 to 2014, the secular variation at Paratunka observatory differs from other observatories. This disagreement of the secular geomagnetic variation at Paratunka observatory is timed to the increase of seismicity at the depth of 400-700 km in South Kamchatka region. It is suggested that in the result of increase of the seismicity in the region of transition from the upper to lower mantle, physical and chemical processes became more active. That caused formation of a large geo-electrical inhomogeneity which affected the behavior of the vertical component of geomagnetic field.

Geomagnetic secular variation at the African observatories

International Nuclear Information System (INIS)

Haile, T.

2002-10-01

Geomagnetic data from ten observatories in the African continent with time series data length of more than three decades have been analysed. All-day annual mean values of the D, H and Z components were used to study secular variations in the African region. The residuals in D, H and Z components obtained after removing polynomial fits have been examined in relation to the sunspot cycle. The occurrence of the 1969-1970 worldwide geomagnetic impulse in each observatory is studied. It is found that the secular variation in the field can be represented for most of the observatories with polynomials of second or third degree. Departures from these trends are observed over the Southern African region where strong local magnetic anomalies have been observed. The residuals in the geomagnetic field components have been shown to exhibit parallelism with the periods corresponding to double solar cycle for some of the stations. A clear latitudinal distribution in the geomagnetic component that exhibits the 1969-70 jerk is shown. The jerk appears in the plots of the first differences in H for the southern most observatories of Hermanus, Hartebeesthoek, and Tsuemb, while the Z plots show the jerk for near equatorial and equatorial stations of Antananarivo, Luanda Belas, Bangui and Addis Ababa. There is some indication for this jerk in the first difference plots of D for the northern stations of M'Bour and Tamanrasset. The plots of D rather strongly suggest the presence of a jerk around 1980 at most of the stations. (author)

Quasi-biennial oscillations in the geomagnetic field: Their global characteristics and origin

DEFF Research Database (Denmark)

Ou, Jiaming; Du, Aimin; Finlay, Chris

2017-01-01

of second-order derivatives of the geomagnetic X, Y, and Z components reveals salient QBO signals at periods of 1.3, 1.7, 2.2, 2.9, and 5.0 years, with the most prominent peak at 2.2 years. The signature of geomagnetic QBO is generally stronger in the X and Z components and with larger amplitudes...... on geomagnetically disturbed days. The amplitude of the QBO in the X component decreases from the equator to the poles, then shows a local maximum at subauroral and auroral zones. The QBO in the Z component enhances from low latitudes toward the polar regions. At high latitudes (poleward of 50°) the geomagnetic QBO...... exhibits stronger amplitudes during LT 00:00–06:00, depending strongly on the geomagnetic activity level, while at low latitudes the main effect is in the afternoon sector. These results indicate that the QBOs at low-to-middle latitudes and at high latitudes are influenced by different magnetospheric...

The geomagnetic field - An explanation for the microturbulence in coaxial gun plasmas

Science.gov (United States)

Mather, J. W.; Ahluwalia, H. S.

1988-01-01

The complexity introduced by the geomagnetic field in several regions of a coaxial gun plasma device is described. It is shown that the annihilation of the swept-up geomagnetic flux, trapped within the highly compressed turbulent plasma, provides an explanation for varied performance and experimental results. The results indicate that the device should be aligned along the direction of the local geomagnetic field or enclosed in a mu-metal shield.

DYNAMICS OF DUST PARTICLES RELEASED FROM OORT CLOUD COMETS AND THEIR CONTRIBUTION TO RADAR METEORS

International Nuclear Information System (INIS)

Nesvorný, David; Vokrouhlický, David; Pokorný, Petr; Janches, Diego

2011-01-01

The Oort Cloud Comets (OCCs), exemplified by the Great Comet of 1997 (Hale-Bopp), are occasional visitors from the heatless periphery of the solar system. Previous works hypothesized that a great majority of OCCs must physically disrupt after one or two passages through the inner solar system, where strong thermal gradients can cause phase transitions or volatile pressure buildup. Here we study the fate of small debris particles produced by OCC disruptions to determine whether the imprints of a hypothetical population of OCC meteoroids can be found in the existing meteor radar data. We find that OCC particles with diameters D ∼ 1 mm have a very low Earth-impact probability. The intermediate particle sizes, D ∼ 100 μm, represent a sweet spot. About 1% of these particles orbitally evolve by Poynting-Robertson drag to reach orbits with semimajor axis a ∼ 1 AU. They are expected to produce meteors with radiants near the apex of Earth's orbital motion. We find that the model distributions of their impact speeds and orbits provide a good match to radar observations of apex meteors, except for the eccentricity distribution, which is more skewed toward e ∼ 1 in our model. Finally, we propose an explanation for the long-standing problem in meteor science related to the relative strength of apex and helion/antihelion sources. As we show in detail, the observed trend, with the apex meteors being more prominent in observations of highly sensitive radars, can be related to orbital dynamics of particles released on the long-period orbits.

Coronal mass ejections and disturbances in solar wind plasma parameters in relation with geomagnetic storms

International Nuclear Information System (INIS)

Verma, P L; Singh, Puspraj; Singh, Preetam

2014-01-01

Coronal Mass Ejections (CMEs) are the drastic solar events in which huge amount of solar plasma materials are ejected into the heliosphere from the sun and are mainly responsible to generate large disturbances in solar wind plasma parameters and geomagnetic storms in geomagnetic field. We have studied geomagnetic storms, (Dst ≤-75 nT) observed during the period of 1997-2007 with Coronal Mass Ejections and disturbances in solar wind plasma parameters (solar wind temperature, velocity, density and interplanetary magnetic field) .We have inferred that most of the geomagnetic storms are associated with halo and partial halo Coronal Mass Ejections (CMEs).The association rate of halo and partial halo coronal mass ejections are found 72.37 % and 27.63 % respectively. Further we have concluded that geomagnetic storms are closely associated with the disturbances in solar wind plasma parameters. We have determined positive co-relation between magnitudes of geomagnetic storms and magnitude of jump in solar wind plasma temperature, jump in solar wind plasma density, jump in solar wind plasma velocity and jump in average interplanetary magnetic field with co-relation co-efficient 0 .35 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma temperature, 0.19 between magnitude of geomagnetic storms and magnitude of jump in solar wind density, 0.34 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma velocity, 0.66 between magnitude of geomagnetic storms and magnitude of jump in average interplanetary magnetic field respectively. We have concluded that geomagnetic storms are mainly caused by Coronal Mass Ejections and disturbances in solar wind plasma parameters that they generate.

An analysis of the physical, chemical, optical, and historical impacts of the 1908 Tunguska meteor fall

Science.gov (United States)

Turco, R. P.; Toon, O. B.; Park, C.; Whitten, R. C.; Pollack, J. B.; Noerdlinger, P.

1982-01-01

An analysis is presented of the physical characteristics and photochemical aftereffects of the 1908 Tunguska explosive cometary meteor, whose physical manifestations are consistent with a five million ton object's entry into the earth's atmosphere at 40 km/sec. Aerodynamic calculations indicate that the shock waves emanating from the falling meteor could have generated up to 30 million tons of nitric oxide in the stratosphere and mesosphere. A fully interactive one-dimensional chemical-kinetics model of atmospheric trace constituents is used to estimate the photochemical consequences of such a large NO injection. The 35-45% hemispherical ozone depletion predicted by the model is in keeping with the 30 + or - 15% ozone variation reported for the first year after the Tunguska fall. Attention is also given to the optical anomalies which followed the event for indications of NO(x)-O(x) chemiluminescent emissions, NO2 solar absorption, and meteoric dust turbidity, along with possible climate changes due to the nearly one million tons of pulverized dust deposited in the mesosphere and stratosphere by the meteor.

On the influence of neutral turbulence on ambipolar diffusivities deduced from meteor trail expansion

Directory of Open Access Journals (Sweden)

C. M. Hall

2002-11-01

Full Text Available By measuring fading times of radar echoes from underdense meteor trails, it is possible to deduce the ambipolar diffusivities of the ions responsible for these radar echoes. It could be anticipated that these diffusivities increase monotonically with height akin to neutral viscosity. In practice, this is not always the case. Here, we investigate the capability of neutral turbulence to affect the meteor trail diffusion rate.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; turbulence

Transitional geomagnetic impulse hypothesis: Geomagnetic fact or rock-magnetic artifact?

Science.gov (United States)

Camps, Pierre; Coe, Robert S.; PréVot, Michel

1999-08-01

A striking feature of the Steens Mountain (Oregon) geomagnetic polarity reversal is the two (maybe three) extremely rapid field directional changes (6 degrees per day) proposed to account for unusual behavior in direction of remanent magnetization in a single lava flow. Each of these very fast field changes, or impulses, is associated with a large directional gap (some 90°) in the record. In order to check the spatial reproducibility of the paleomagnetic signal over distances up to several kilometers, we have carried out a paleomagnetic investigation of two new sections (B and F) in the Steens summit region which cover the second and the third directional gap. The main result is the description of two new directions, which are located between the pre second and post second impulse directions. These findings weigh against the hypothesis that the geomagnetic field cause the unusual intraflow fluctuations, which now appears to be more ad hoc as an explanation of the paleomagnetic data. However, the alternative baking hypothesis remains also ad hoc since we have to assume variable rock magnetic properties that we have not yet been able to detect within the flows at the original section Steens A and D 1.5 km to the north. In addition, new results for 22 transitional and normal lava flows in section B are presented that correlate well with earlier results from section A.

Collecting Comet Samples by ER-2 Aircraft: Cosmic Dust Collection During the Draconid Meteor Shower in October 2012

Science.gov (United States)

Bastien, Ron; Burkett, P. J.; Rodriquez, M.; Frank, D.; Gonzalez, C.; Robinson, G.-A.; Zolensky, M.; Brown, P.; Campbell-Brown, M.; Broce, S.;

International Geomagnetic Reference Field: the 12th generation

OpenAIRE

Thébault , Erwan; Finlay , Christopher ,; Beggan , Ciarán ,; Alken , Patrick; Aubert , Julien ,; Barrois , Olivier; Bertrand , François; Bondar , Tatiana; Boness , Axel; Brocco , Laura; Canet , Elisabeth ,; Chambodut , Aude; Chulliat , Arnaud ,; Coïsson , Pierdavide ,; Civet , François

2015-01-01

International audience; The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch 2010.0, a main field model for epoch 2015.0, and a linear annual predictive secular variation model for 2015.0-2020.0. Here, we present the equations defining the IGRF model, p...

Geomagnetic field models for satellite angular motion studies

Science.gov (United States)

Ovchinnikov, M. Yu.; Penkov, V. I.; Roldugin, D. S.; Pichuzhkina, A. V.

2018-03-01

Four geomagnetic field models are discussed: IGRF, inclined, direct and simplified dipoles. Geomagnetic induction vector expressions are provided in different reference frames. Induction vector behavior is compared for different models. Models applicability for the analysis of satellite motion is studied from theoretical and engineering perspectives. Relevant satellite dynamics analysis cases using analytical and numerical techniques are provided. These cases demonstrate the benefit of a certain model for a specific dynamics study. Recommendations for models usage are summarized in the end.

The Geomagnetic Control Concept of The Ionospheric Long- Term Trends

Science.gov (United States)

Mikhailov, A. V.

The geomagnetic control concept has been developed to explain long-term trends of the electron concentration in the F2 and E ionospheric regions. Periods with negative and positive foF2, hmF2 and foE trends correspond to the periods of increasing or decreasing geomagnetic activity with the turning points around the end of 1950s, 1960s, and 1980s where trends change their signs. Strong latitudinal and diurnal variations revealed for the foF2 and hmF2 trends can be explained by neutral composition, temperature and thermospheric wind changes. Particle precipitation is important in the auroral zone. The newly proposed concept proceeds from a natural origin of the F2-layer trends rather than an artificial one related to the greenhouse effect. Using the proposed method a very long-term foF2 and foE trends related with general increase of geomagnetic activity in the 20th century has been revealed for the first time. The firstly revealed relationship of the foE trends with geomagnetic activity is due to nitric oxide variations at the E-region heights. This "natural" relationship of the foE trends with geomagnetic activity breaks down around 1970 on many stations presumably due to chemical polution of the upper atmosphere. The increasing rate of rocket and satellite launchings in the late 1960s is considered as a reason.

New forecasting methods of the intensity and time development of geomagnetic and ionospheric storms

International Nuclear Information System (INIS)

Akasofu, S.I.

1981-01-01

The main phase of a geomagnetic storm develops differently from one storm to another. A description is given of the solar wind quantity which controls directly the development of the main phase of geomagnetic storms. The parameters involved include the solar wind speed, the magnetic field intensity, and the polar angle of the solar wind magnetic field projected onto the dawn-dusk plane. A redefinition of geomagnetic storm and auroral activity is given. It is pointed out that geomagnetic disturbances are caused by the magnetic fields of electric currents which are generated by the solar wind-magnetosphere dynamo. Attention is given to approaches for forecasting the occurrence and intensity of geomagnetic storms and ionospheric disturbances

Operations of the World Data Centre for Geomagnetism, Edinburgh

Directory of Open Access Journals (Sweden)

S J Reay

2013-01-01

Full Text Available The British Geological Survey has operated a World Data Centre for Geomagnetism since 1966. Geomagnetic time-series data from around 280 observatories worldwide at a number of time resolutions are held along with various magnetic survey, model, and activity index data. The operation of this data centre provides a valuable resource for the geomagnetic research community. The operation of the WDC and details of the range of data held are presented. The quality control procedures that are applied to incoming data are described as is the work to collaborate with other data centres to distribute and improve the overall consistency of data held worldwide. The development of standards for metadata associated with datasets is demonstrated, and current efforts to digitally preserve the BGS analogue holdings of magnetograms and observatory yearbooks are described.

Advancements in Chinese Geomagnetism and Aeronomy during the Last Thirty Years,

Science.gov (United States)

1981-02-09

movements of charged particles in geomagnetic fields and neutral line magnetic fields and they vigorously initiated simulated tests. References (120-121... telluric prospecting and related probems; (6) Magnetic prospecting and interpretation of data; (7) Some research on geomagnetic instruments; (8

Atmospheric trajectories and light curves of shower meteors

Czech Academy of Sciences Publication Activity Database

Koten, Pavel; Borovička, Jiří; Spurný, Pavel; Betlem, H.; Evans, S.

2004-01-01

Roč. 428, č. 2 (2004), s. 683-690 ISSN 0004-6361 R&D Projects: GA ČR GP205/02/P038; GA ČR GA205/02/0982; GA ČR GA205/03/1404 Institutional research plan: CEZ:AV0Z1003909 Keywords : meteors * meteoroids * general-comets Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.694, year: 2004

On the influence of neutral turbulence on ambipolar diffusivities deduced from meteor trail expansion

Directory of Open Access Journals (Sweden)

C. M. Hall

Full Text Available By measuring fading times of radar echoes from underdense meteor trails, it is possible to deduce the ambipolar diffusivities of the ions responsible for these radar echoes. It could be anticipated that these diffusivities increase monotonically with height akin to neutral viscosity. In practice, this is not always the case. Here, we investigate the capability of neutral turbulence to affect the meteor trail diffusion rate.

Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; turbulence

Seasonal variation of meteor decay times observed at King Sejong Station (62.22°S, 58.78°W), Antarctica

Science.gov (United States)

Kim, Jeong-Han; Kim, Yong Ha; Lee, Chang-Sup; Jee, Geonhwa

2010-07-01

We analyzed meteor decay times measured by a VHF radar at King Sejong Station by classifying strong and weak meteors according to their estimated electron line densities. The height profiles of monthly averaged decay times show a peak whose altitude varies with season at altitudes of 80-85 km. The higher peak during summer is consistent with colder temperatures that cause faster chemical reactions of electron removal. By adopting temperature dependent empirical recombination rates from rocket experiments and meteor electron densities of 2×105-2×106 cm-3 in a decay time model, we are able to account for decreasing decay times below the peak for all seasons without invoking meteor electron removal by hypothetical icy particles.

Climatic influence in NRM and 10 Be-derived geomagnetic paleointensity data

NARCIS (Netherlands)

1999-01-01

One can determine geomagnetic paleointensities from natural remanent magnetizations (NRM) and by inverting production rates of cosmogenic isotopes such as 10 Be and 14 C. Recently, two independently derived 200-kyr stacks [Y. Guyodo, J.-P. Valet, Relative variations in geomagnetic intensity from

Geomagnetic storm under laboratory conditions: randomized experiment

Science.gov (United States)

Gurfinkel, Yu I.; Vasin, A. L.; Pishchalnikov, R. Yu; Sarimov, R. M.; Sasonko, M. L.; Matveeva, T. A.

2017-10-01

The influence of the previously recorded geomagnetic storm (GS) on human cardiovascular system and microcirculation has been studied under laboratory conditions. Healthy volunteers in lying position were exposed under two artificially created conditions: quiet (Q) and storm (S). The Q regime playbacks a noise-free magnetic field (MF) which is closed to the natural geomagnetic conditions on Moscow's latitude. The S regime playbacks the initially recorded 6-h geomagnetic storm which is repeated four times sequentially. The cardiovascular response to the GS impact was assessed by measuring capillary blood velocity (CBV) and blood pressure (BP) and by the analysis of the 24-h ECG recording. A storm-to-quiet ratio for the cardio intervals (CI) and the heart rate variability (HRV) was introduced in order to reveal the average over group significant differences of HRV. An individual sensitivity to the GS was estimated using the autocorrelation function analysis of the high-frequency (HF) part of the CI spectrum. The autocorrelation analysis allowed for detection a group of subjects of study which autocorrelation functions (ACF) react differently in the Q and S regimes of exposure.

Geomagnetic storm under laboratory conditions: randomized experiment.

Science.gov (United States)

Gurfinkel, Yu I; Vasin, A L; Pishchalnikov, R Yu; Sarimov, R M; Sasonko, M L; Matveeva, T A

2018-04-01

The influence of the previously recorded geomagnetic storm (GS) on human cardiovascular system and microcirculation has been studied under laboratory conditions. Healthy volunteers in lying position were exposed under two artificially created conditions: quiet (Q) and storm (S). The Q regime playbacks a noise-free magnetic field (MF) which is closed to the natural geomagnetic conditions on Moscow's latitude. The S regime playbacks the initially recorded 6-h geomagnetic storm which is repeated four times sequentially. The cardiovascular response to the GS impact was assessed by measuring capillary blood velocity (CBV) and blood pressure (BP) and by the analysis of the 24-h ECG recording. A storm-to-quiet ratio for the cardio intervals (CI) and the heart rate variability (HRV) was introduced in order to reveal the average over group significant differences of HRV. An individual sensitivity to the GS was estimated using the autocorrelation function analysis of the high-frequency (HF) part of the CI spectrum. The autocorrelation analysis allowed for detection a group of subjects of study which autocorrelation functions (ACF) react differently in the Q and S regimes of exposure.

Fast directional changes in the geomagnetic field recovered from archaeomagnetism of ancient Israel

Science.gov (United States)

Shaar, R.; Hassul, E.; Raphael, K.; Ebert, Y.; Marco, S.; Nowaczyk, N. R.; Ben-Yosef, E.; Agnon, A.

2017-12-01

Recent archaeomagnetic intensity data from the Levant revealed short-term sub-centennial changes in the geomagnetic field such as `archaeomagnetic jerks' and `geomagnetic spikes'. To fully understand the nature of these fast variations a complementary high-precision time-series of geomagnetic field direction is required. To this end we investigated 35 heat impacted archaeological objects from Israel, including cooking ovens, furnaces, and burnt walls. We combine the new dataset with previously unpublished data and construct the first archaeomagnetic compilation of Israel which, at the moment, consists of a total of 57 directions. Screening out poor quality data leaves 30 acceptable archaeomagnetic directions, 25 of which spanning the period between 1700 BCE to 400 BCE. The most striking result of this dataset is a large directional anomaly with deviation of 20°-25° from geocentric axial dipole direction during the 9th century BCE. This anomaly in field direction is contemporaneous with the Levantine Iron Age Anomaly (LIAA) - a local geomagnetic anomaly over the Levant that was characterized by a high averaged geomagnetic field (nearly twice of today's field) and short decadal-scale geomagnetic spikes.

Meteoric ions in the corona and solar wind

International Nuclear Information System (INIS)

Lemaire, J.

1990-01-01

The total mass of refractory material of interplanetary origin penetrating and evaporated in the meltosphere surrounding the sun has been inferred from observations of meteoroids and fireballs falling in earth's atmosphere. The amount of iron atoms deposited this way in the solar corona is of the order of 3000 t/s or larger. The measured flux of outflowing solar wind iron ions is equal to 2200 t/s. The close agreement of both fluxes is evidence that a significant fraction of iron ions observed in the solar wind and in the corona must be of meteoric origin. A similar accord is also obtained for silicon ions. The mean velocity of meteoroid ions formed in the solar corona is equal to the free-fall velocity: i.e., independent of their atomic mass as the thermal speed of heavy ion measured in low-density solar wind streams at 1 AU. Furthermore, the heavy ions of meteoric origin escape out of the corona with a larger bulk velocity than the protons which are mainly of solar origin. These differences of heavy ion and proton bulk velocities are also observed in the solar wind. 52 refs

Relationship between human physiological parameters and geomagnetic variations of solar origin

Science.gov (United States)

Dimitrova, S.

Results presented concern influence of increased geomagnetic activity on some human physiological parameters. The blood pressure and heart rate of 86 volunteers were measured on working days in autumn 2001 (01/10 09/11) and in spring 2002 (08/04 28/05). These periods were chosen because of maximal expected geomagnetic activity. Altogether 2799 recordings were obtained and analysed. Questionnaire information about subjective psycho-physiological complaints was also gathered. MANOVA was employed to check the significance of the influence of three factors on the physiological parameters under consideration. The factors were the following: (1) planetary geomagnetic activity level estimated by Ap-index and divided into five levels; (2) gender males and females; (3) blood pressure degree persons in the group examined were divided into hypotensive, normotensive and hypertensive. Post hoc analysis was performed to elicit the significance of differences in the factors’ levels. The average arterial blood pressure of the group was found to increase significantly with the increase of geomagnetic activity level. The average increment of systolic and diastolic blood pressure of the group examined reached 9%. This effect was present irrespectively of gender. Results obtained suppose that hypertensive persons have the highest sensitivity and the hypotensive persons have the lowest sensitivity of the arterial blood pressure to increase of geomagnetic activity. The results did not show significant changes in the heart rate. The percentage of the persons who reported subjective psycho-physiological complaints was also found to increase significantly with the geomagnetic activity increase and the highest sensitivity was revealed for the hypertensive females.

AI techniques in geomagnetic storm forecasting

Science.gov (United States)

Lundstedt, Henrik

This review deals with how geomagnetic storms can be predicted with the use of Artificial Intelligence (AI) techniques. Today many different Al techniques have been developed, such as symbolic systems (expert and fuzzy systems) and connectionism systems (neural networks). Even integrations of AI techniques exist, so called Intelligent Hybrid Systems (IHS). These systems are capable of learning the mathematical functions underlying the operation of non-linear dynamic systems and also to explain the knowledge they have learned. Very few such powerful systems exist at present. Two such examples are the Magnetospheric Specification Forecast Model of Rice University and the Lund Space Weather Model of Lund University. Various attempts to predict geomagnetic storms on long to short-term are reviewed in this article. Predictions of a month to days ahead most often use solar data as input. The first SOHO data are now available. Due to the high temporal and spatial resolution new solar physics have been revealed. These SOHO data might lead to a breakthrough in these predictions. Predictions hours ahead and shorter rely on real-time solar wind data. WIND gives us real-time data for only part of the day. However, with the launch of the ACE spacecraft in 1997, real-time data during 24 hours will be available. That might lead to the second breakthrough for predictions of geomagnetic storms.

Computation of geomagnetic elements for Nigeria for the year 2000 ...

African Journals Online (AJOL)

The Earth's magnetic field may be considered to be the sum of two parts, the main geomagnetic field which originates from the earth's fluid core, and the anomaly field that has its sources in the earth crust. The analysis of the geomagnetic field residual or anomaly, obtained from the difference between these two sources are ...

A simple statistical model for geomagnetic reversals

Science.gov (United States)

Constable, Catherine

1990-01-01

The diversity of paleomagnetic records of geomagnetic reversals now available indicate that the field configuration during transitions cannot be adequately described by simple zonal or standing field models. A new model described here is based on statistical properties inferred from the present field and is capable of simulating field transitions like those observed. Some insight is obtained into what one can hope to learn from paleomagnetic records. In particular, it is crucial that the effects of smoothing in the remanence acquisition process be separated from true geomagnetic field behavior. This might enable us to determine the time constants associated with the dominant field configuration during a reversal.

The response of European Daphnia magna Straus and Australian Daphnia carinata King to changes in geomagnetic field.

Science.gov (United States)

Krylov, Viacheslav V; Bolotovskaya, Irina V; Osipova, Elena A

2013-03-01

This study investigates the effects of lifelong exposure to reversed geomagnetic and zero geomagnetic fields (the latter means absence of geomagnetic field) on the life history of Daphnia carinata King from Australia and Daphnia magna Straus from Europe. Considerable deviation in the geomagnetic field from the usual strength, leads to a decrease in daphnia size and life span. Reduced brood sizes and increased body length of neonates are observed in D. magna exposed to unusual magnetic background. The most apparent effects are induced by zero geomagnetic field in both species of Daphnia. A delay in the first reproduction in zero geomagnetic field is observed only in D. magna. No adaptive maternal effects to reversed geomagnetic field are found in a line of D. magna maintained in these magnetic conditions for eight generations. Integrally, the responses of D. magna to unusual geomagnetic conditions are more extensive than that in D. carinata. We suggest that the mechanism of the effects of geomagnetic field reversal on Daphnia may be related to differences in the pattern of distribution of the particles that have a magnetic moment, or to moving charged organic molecules owing to a change in combined outcome and orientation of the geomagnetic field and Earth's gravitational field. The possibility of modulation of self-oscillating processes with changes in geomagnetic field is also discussed.

Long-Term Seafloor Electromagnetic Observation in the Northwest Pacific May Detect the Vector Geomagnetic Secular Variation

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H Toh

2010-03-01

Full Text Available Sea Floor ElectroMagnetic Stations (SFEMSs are now operating at two deep seafloor sites called the 'WPB' and the 'NWP' in the West Philippine Basin and the Northwest Pacific Basin, respectively. One of the main objectives of the SFEMSs is to detect the geomagnetic secular variations on the deep seafloor where long-term geomagnetic observations have not so far been achieved. SFEMSs can measure the absolute geomagnetic total force as well as the geomagnetic vector field with precise attitude monitoring systems. The vector geomagnetic time-series that was observed for more than 5 years revealed that the westward drift of the equatorial dipole dominates in the geomagnetic secular variation at the NWP.

New insights on geomagnetic storms from observations and modeling

Energy Technology Data Exchange (ETDEWEB)

Jordanova, Vania K [Los Alamos National Laboratory

2009-01-01

Understanding the response at Earth of the Sun's varying energy output and forecasting geomagnetic activity is of central interest to space science, since intense geomagnetic storms may cause severe damages on technological systems and affect communications. Episodes of southward (Bzgeomagnetic conditions are associated either with coronal mass ejections (CMEs) and possess long and continuous negative IMF Bz excursions, or with high speed solar wind streams (HSS) whose geoeffectiveness is due to IMF Bz profiles fluctuating about zero with various amplitudes and duration. We show examples of ring current simulations during two geomagnetic storms representative of each interplanetary condition with our kinetic ring current atmosphere interactions model (RAM), and investigate the mechanisms responsible for trapping particles and for causing their loss. We find that periods of increased magnetospheric convection coinciding with enhancements of plasma sheet density are needed for strong ring current buildup. During the HSS-driven storm the convection potential is highly variable and causes small sporadic injections into the ring current. The long period of enhanced convection during the CME-driven storm causes a continuous ring current injection penetrating to lower L shells and stronger ring current buildup.

Mesospheric Temperatures and Winds measured by a VHF Meteor Radar at King Sejong Station (62.2S, 58.8W), Antarctica

Science.gov (United States)

Kim, Yongha; Kim, Jeong-Han; Jee, Geonwha; Lee, Chang-Sup

2010-05-01

A VHF radar at King Sejong Station, Antarctica has been measuring meteor echoes since March 2007. Temperatures near the mesopause are derived from meteor decay times with an improved method of selecting meteor echo samples, and compared with airglow temperatures simultaneously observed by a spectral airglow temperature imager (SATI). The temperatures derived from meteor decay times are mostly consistent with the rotational temperatures of SATI OH(6-2) and O2(0-1) emissions from March through October. During southern summer when SATI cannot be operated due to brief night time, the meteor radar observation shows cold mesospheric temperatures, significantly lower than the CIRA86 model. The meteor radar observation also provides wind field information between 80 and 100 km of altitude. The measured meridional winds seem to follow the summer pole to winter pole circulation, and thus are correlated with the measured seasonal temperature change. However, the correlation between meridional winds and temperatures is not found in day by day base, as a previous study reported. Tidal characteristics of both zonal and meridional winds will also be compared with those of other Antarctic stations.

The Meteor and Fireball Network of the Sociedad Malagueña de Astronomía

Science.gov (United States)

Aznar, J. C.; Castellón, A.; Gálvez, F.; Martínez, E.; Troughton, B.; Núñez, J. M.; Villalba, F.

2016-12-01

One of the most active fields in which has been dedicated the Málaga Astronomical Society (SMA) is the meteors and meteor showers. Since 2006 the SMA refers parts of visual observations and photographic detections from El Pinillo station (Torremolinos, Spain). In 2013 it was decided to give an extra boost to get a camera network that allowed the calculation of the atmospheric trajectory of a meteoroid and, where possible, obtaining the orbital elements.

Paleointensity Behavior and Intervals Between Geomagnetic Reversals in the Last 167 Ma

Science.gov (United States)

Kurazhkovskii, A. Yu.; Kurazhkovskaya, N. A.; Klain, B. I.

2018-01-01

The results of comparative analysis of the behavior of paleointensity and polarity (intervals between reversals) of the geomagnetic field for the last 167 Ma are presented. Similarities and differences in the behavior of these characteristics of the geomagnetic field are discussed. It is shown that bursts of paleointensity and long intervals between reversals occurred at high mean values of paleointensity in the Cretaceous and Paleogene. However, there are differences between the paleointensity behavior and the reversal regime: (1) the characteristic times of paleointensity variations are less than the characteristic times of the frequency of geomagnetic reversals, (2) the achievement of maximum values of paleointensity at the Cretaceous-Paleogene boundary and the termination of paleointensity bursts after the boundary of 45-40 Ma are not marked by explicit features in the geomagnetic polarity behavior.

Geomagnetic response of interplanetary coronal mass ejections in the Earth's magnetosphere

Science.gov (United States)

Badruddin; Mustajab, F.; Derouich, M.

2018-05-01

A coronal mass ejections (CME) is the huge mass of plasma with embedded magnetic field ejected abruptly from the Sun. These CMEs propagate into interplanetary space with different speed. Some of them hit the Earth's magnetosphere and create many types of disturbances; one of them is the disturbance in the geomagnetic field. Individual geomagnetic disturbances differ not only in their magnitudes, but the nature of disturbance is also different. It is, therefore, desirable to understand these differences not only to understand the physics of geomagnetic disturbances but also to understand the properties of solar/interplanetary structures producing these disturbances of different magnitude and nature. In this work, we use the spacecraft measurements of CMEs with distinct magnetic properties propagating in the interplanetary space and generating disturbances of different levels and nature. We utilize their distinct plasma and field properties to search for the interplanetary parameter(s) playing important role in influencing the geomagnetic response of different coronal mass ejections.

The challenge associated with the robust computation of meteor velocities from video and photographic records

Science.gov (United States)

Egal, A.; Gural, P. S.; Vaubaillon, J.; Colas, F.; Thuillot, W.

2017-09-01

The CABERNET project was designed to push the limits for obtaining accurate measurements of meteoroids orbits from photographic and video meteor camera recordings. The discrepancy between the measured and theoretic orbits of these objects heavily depends on the semi-major axis determination, and thus on the reliability of the pre-atmospheric velocity computation. With a spatial resolution of 0.01° per pixel and a temporal resolution of up to 10 ms, CABERNET should be able to provide accurate measurements of velocities and trajectories of meteors. To achieve this, it is necessary to improve the precision of the data reduction processes, and especially the determination of the meteor's velocity. In this work, most of the steps of the velocity computation are thoroughly investigated in order to reduce the uncertainties and error contributions at each stage of the reduction process. The accuracy of the measurement of meteor centroids is established and results in a precision of 0.09 pixels for CABERNET, which corresponds to 3.24‧‧. Several methods to compute the velocity were investigated based on the trajectory determination algorithms described in Ceplecha (1987) and Borovicka (1990), as well as the multi-parameter fitting (MPF) method proposed by Gural (2012). In the case of the MPF, many optimization methods were implemented in order to find the most efficient and robust technique to solve the minimization problem. The entire data reduction process is assessed using simulated meteors, with different geometrical configurations and deceleration behaviors. It is shown that the multi-parameter fitting method proposed by Gural(2012)is the most accurate method to compute the pre-atmospheric velocity in all circumstances. Many techniques that assume constant velocity at the beginning of the path as derived from the trajectory determination using Ceplecha (1987) or Borovicka (1990) can lead to large errors for decelerating meteors. The MPF technique also allows one to

Geomagnetic activity associated with Earth passage of interplanetary shock disturbances and coronal mass ejections

International Nuclear Information System (INIS)

Gosling, J.T.; McComas, D.J.; Phillips, J.L.; Bame, S.J.

1991-01-01

Previous work indicates that virtually all transient shock wave disturbances in the solar wind are driven by fast coronal mass ejection events (CMEs). Using a recently appreciated capability for distinguishing CMEs in solar wind data in the form of counterstreaming solar wind electron events, this paper explores the overall effectiveness of shock wave disturbances and CMEs in general in stimulating geomagnetic activity. The study is confined to the interval from mid-August 1978 through mid-October 1982, spanning the last solar activity maximum, when ISEE 3 was in orbit about the L1 Lagrange point 220 R e upstream from Earth. The authors find that all but one of the 37 largest geomagnetic storms in that era were associated with Earth passage of CMEs and/or shock disturbances, with the large majority of these storms being associated with interplanetary events where Earth encountered both a shock and the CME driving the shock (shock/CME events). Although CMEs and/or shock disturbances were increasingly the cause of geomagnetic activity as the level of geomagnetic activity increased, many smaller geomagnetic disturbances were unrelated to these events. Further, approximately half of all CMEs and half of all shock disturbances encountered by Earth did not produce any substantial geomagnetic activity as measured by the planetary geomagnetic index Kp. The geomagnetic effectiveness of Earth directed CMEs and shock wave disturbances was directly related to the flow speed, the magnetic field magnitude, and the strength of the southward (GSM) field component associated with the events. The initial speed of a CME close to the Sun appears to be the most crucial factor in determining if an earthward directed event will be effective in exciting a large geomagnetic disturbance

Solar cycle effect on geomagnetic storms caused by interplanetary magnetic clouds

Directory of Open Access Journals (Sweden)

C.-C. Wu

2006-12-01

Full Text Available We investigated geomagnetic activity which was induced by interplanetary magnetic clouds during the past four solar cycles, 1965–1998. We have found that the intensity of such geomagnetic storms is more severe in solar maximum than in solar minimum. In addition, we affirm that the average solar wind speed of magnetic clouds is faster in solar maximum than in solar minimum. In this study, we find that solar activity level plays a major role on the intensity of geomagnetic storms. In particular, some new statistical results are found and listed as follows. (1 The intensity of a geomagnetic storm in a solar active period is stronger than in a solar quiet period. (2 The magnitude of negative Bz_min is larger in a solar active period than in a quiet period. (3 Solar wind speed in an active period is faster than in a quiet period. (4 VBs_max in an active period is much larger than in a quiet period. (5 Solar wind parameters, Bz_min, V_max and VBs_max are correlated well with geomagnetic storm intensity, D_stmin during a solar active period. (6 Solar wind parameters, Bz_min, and VBs_max are not correlated well (very poorly for V_max with geomagnetic storm intensity during a solar quiet period. (7 The speed of the solar wind plays a key role in the correlation of solar wind parameters vs. the intensity of a geomagnetic storm. (8 More severe storms with D_stmin≤−100 nT caused by MCs occurred in the solar active period than in the solar quiet period.

Meteor Observational Data Visualisation in the Equatorial Coordinate System Using Information Technology

Science.gov (United States)

Golovashchenko, V. A.; Kolomiyets, S. V.

As a result of dynamic evolution of IT industry and astronomical research in the XXI century, which have resulted in obtaining large and complex data sets known as Big Data (e.g. data from the European Space Agency missions, such as GAIA mission, etc.), as well as due to rapid development of computer technologies, astronomy and computer science have become closely linked to each other. In the XXI century, Information technology has become an essential part of understanding the world around. This paper presents a solution to the problem of meteor data representation in the second equatorial coordinate (RA-Dec) system using Information Technology. Such a visualisation solution is needed to analyse the results of experiments based on the radar observations conducted in 1972-1978 (stage 1 - the data obtained in 1972 comprise 10,247 meteor orbits), which have been accumulated and stored in the Meteor Database of the Kharkiv National University of Radio Electronics (KNURE). A sample set of data with their characteristics and details about their delivery has been presented by (Kashcheyev & Tkachuk, 1980). An electronic calculator application was developed by employing the model of data visualisation in the form of celestial hemispheres using the object-oriented programming language C#.

Relation of geomagnetic pulsations to parmeters of mid-latitude lower ionosphere

International Nuclear Information System (INIS)

Dorokhov, V.L.; Kostrov, L.S.; Martynenko, S.I.; Piven', L.A.; Pushin, V.F.; Shemet, A.S.

1989-01-01

Results of experimental investigation of the effect of geomagnetic pulsations on parameters of medium-latitude lower ionosphere with the use of methods of partial reflections and Doppler probing at short waves are presented. The relation between changes in geomagnetic field and intensity of partially reflected radiosignals is detected

Geomagnetically induced pipe-to-soil voltages in the Czech oil pipelines during October-November 2003

Directory of Open Access Journals (Sweden)

P. Hejda

2005-11-01

Full Text Available Whereas geomagnetically induced currents are a source of problems for technological systems mainly at high geomagnetic latitudes, strong geomagnetic disturbances can have quite strong effects even at mid-latitudes. This paper deals with the analysis of the pipe-to-soil (P/S voltage measured in oil pipelines in the Czech Republic during the Halloween magnetic storms in 2003. It is shown that the simplest - plane wave and uniform Earth-model of the electric field corresponds well to the measured P/S voltage. Although the largest amplitudes of the geomagnetic field were reached on the onset of the geomagnetic storm, large voltages were also induced in the main and recovery phases due to Pc5 oscillations.

Statistical analysis of geomagnetic field variations during the partial solar eclipse on 2011 January 4 in Turkey

International Nuclear Information System (INIS)

Ateş, Abdullah; Levent Ekinci, Yunus; Buyuksarac, Aydin; Aydemir, Attila; Demirci, Alper

2015-01-01

Some geophysical parameters, such as those related to gravitation and the geomagnetic field, could change during solar eclipses. In order to observe geomagnetic fluctuations, geomagnetic measurements were carried out in a limited time frame during the partial solar eclipse that occurred on 2011 January 4 and was observed in Canakkale and Ankara, Turkey. Additionally, records of the geomagnetic field spanning 24 hours, obtained from another observatory (in Iznik, Turkey), were also analyzed to check for any peculiar variations. In the data processing stage, a polynomial fit, following the application of a running average routine, was applied to the geomagnetic field data sets. Geomagnetic field data sets indicated there was a characteristic decrease at the beginning of the solar eclipse and this decrease can be well-correlated with previous geomagnetic field measurements that were taken during the total solar eclipse that was observed in Turkey on 2006 March 29. The behavior of the geomagnetic field is also consistent with previous observations in the literature. As a result of these analyses, it can be suggested that eclipses can cause a shielding effect on the geomagnetic field of the Earth. (paper)

Geomagnetic Observatory Data for Real-Time Applications

Science.gov (United States)

Love, J. J.; Finn, C. A.; Rigler, E. J.; Kelbert, A.; Bedrosian, P.

2015-12-01

The global network of magnetic observatories represents a unique collective asset for the scientific community. Historically, magnetic observatories have supported global magnetic-field mapping projects and fundamental research of the Earth's interior and surrounding space environment. More recently, real-time data streams from magnetic observatories have become an important contributor to multi-sensor, operational monitoring of evolving space weather conditions, especially during magnetic storms. In this context, the U.S. Geological Survey (1) provides real-time observatory data to allied space weather monitoring projects, including those of NOAA, the U.S. Air Force, NASA, several international agencies, and private industry, (2) collaborates with Schlumberger to provide real-time geomagnetic data needed for directional drilling for oil and gas in Alaska, (3) develops products for real-time evaluation of hazards for the electric-power grid industry that are associated with the storm-time induction of geoelectric fields in the Earth's conducting lithosphere. In order to implement strategic priorities established by the USGS Natural Hazards Mission Area and the National Science and Technology Council, and with a focus on developing new real-time products, the USGS is (1) leveraging data management protocols already developed by the USGS Earthquake Program, (2) developing algorithms for mapping geomagnetic activity, a collaboration with NASA and NOAA, (3) supporting magnetotelluric surveys and developing Earth conductivity models, a collaboration with Oregon State University and the NSF's EarthScope Program, (4) studying the use of geomagnetic activity maps and Earth conductivity models for real-time estimation of geoelectric fields, (5) initiating geoelectric monitoring at several observatories, (6) validating real-time estimation algorithms against historical geomagnetic and geoelectric data. The success of these long-term projects is subject to funding constraints

Zonal wind observations during a geomagnetic storm

Science.gov (United States)

Miller, N. J.; Spencer, N. W.

1986-01-01

In situ measurements taken by the Wind and Temperature Spectrometer (WATS) onboard the Dynamics Explorer 2 spacecraft during a geomagnetic storm display zonal wind velocities that are reduced in the corotational direction as the storm intensifies. The data were taken within the altitudes 275 to 475 km in the dusk local time sector equatorward of the auroral region. Characteristic variations in the value of the Dst index of horizontal geomagnetic field strength are used to monitor the storm evolution. The detected global rise in atmospheric gas temperature indicates the development of thermospheric heating. Concurrent with that heating, reductions in corotational wind velocities were measured equatorward of the auroral region. Just after the sudden commencement, while thermospheric heating is intense in both hemispheres, eastward wind velocities in the northern hemisphere show reductions ranging from 500 m/s over high latitudes to 30 m/s over the geomagnetic equator. After 10 hours storm time, while northern thermospheric heating is diminishing, wind velocity reductions, distinct from those initially observed, begin to develop over southern latitudes. In the latter case, velocity reductions range from 300 m/s over the highest southern latitudes to 150 m/s over the geomagnetic equator and extend into the Northern Hemisphere. The observations highlight the interhemispheric asymmetry in the development of storm effects detected as enhanced gas temperatures and reduced eastward wind velocities. Zonal wind reductions over high latitudes can be attributed to the storm induced equatorward spread of westward polar cap plasma convection and the resulting plasma-neutral collisions. However, those collisions are less significant over low latitudes; so zonal wind reductions over low latitudes must be attributed to an equatorward extension of a thermospheric circulation pattern disrupted by high latitude collisions between neutrals transported via eastward winds and ions

Effects of geomagnetic storms in the lower ionosphere, middle atmosphere and troposphere.

Science.gov (United States)

Lastovicka, J.

1996-05-01

Geomagnetic storm effects at heights of about 0-100 km are briefly (not comprehensively) reviewed, with emphasis being paid to middle latitudes, particularly to Europe. Effects of galactic cosmic rays, solar particle events, relativistic and highly relativistic electrons, and IMF sector boundary crossings are briefly mentioned as well. Geomagnetic storms disturb the lower ionosphere heavily at high latitudes and very significantly also at middle latitudes. The effect is almost simultaneous at high latitudes, while an after-effect dominates at middle latitudes. The lower thermosphere is disturbed significantly. In the mesosphere and stratosphere, the effects become weaker and eventually non-detectable. There is an effect in total ozone but only under special conditions. Surprisingly enough, correlations with geomagnetic storms seem to reappear in the troposphere, particularly in the Northern Hemisphere. Atmospheric electricity is affected by geomagnetic storms, as well. We essentially understand the effects of geomagnetic storms in the lower ionosphere, but there is a lack of mechanisms to explain correlations found deeper in the atmosphere, particularly in the troposphere. There seem to be two different groups of effects with possibly different mechanisms - those observed in the lower ionosphere, lower thermosphere and mesosphere, and those observed in the troposphere.

Geomagnetic activity forcing of the Northern Annular Mode via the stratosphere

Directory of Open Access Journals (Sweden)

D. R. Palamara

2004-03-01

Full Text Available We consider various aspects of the link between solar-modulated geomagnetic activity and the Northern Annular Mode (NAM. Our results indicate that the geomagnetic forcing of atmospheric circulation in the Northern Hemisphere is temporally and seasonally restricted, modulated by the Quasi-Biennial Oscillation (QBO, and reliant on stratosphere-troposphere coupling. When the data are restricted to January values after 1965, for years in which the January QBO is eastwards, the correlation coefficient between the geomagnetic AA index and the NAM is 0.85. These results can account for many of the enigmatic features of Northern Hemisphere circulation.

Key words. Meterology and atmospheric dynamics (general circulation, climatology

Geomagnetic activity forcing of the Northern Annular Mode via the stratosphere

Directory of Open Access Journals (Sweden)

D. R. Palamara

2004-03-01

Full Text Available We consider various aspects of the link between solar-modulated geomagnetic activity and the Northern Annular Mode (NAM. Our results indicate that the geomagnetic forcing of atmospheric circulation in the Northern Hemisphere is temporally and seasonally restricted, modulated by the Quasi-Biennial Oscillation (QBO, and reliant on stratosphere-troposphere coupling. When the data are restricted to January values after 1965, for years in which the January QBO is eastwards, the correlation coefficient between the geomagnetic AA index and the NAM is 0.85. These results can account for many of the enigmatic features of Northern Hemisphere circulation. Key words. Meterology and atmospheric dynamics (general circulation, climatology

Solar wind velocity and geomagnetic moment variations

International Nuclear Information System (INIS)

Kalinin, Yu.D.; Rozanova, T.S.

1982-01-01

The mean year values of the solar wind velocity have been calculated from the mean-year values of a geomagnetic activity index am according to the Svalgard equation of regression for the pe-- riod from 1930 to 1960. For the same years the values of the geomagnetic moment M and separately of its ''inner'' (causes of which'' are inside the Earth) and ''external'' (causes of which are outside the Earth) parts have been calculated from the mean year data of 12 magnetic observatories. The proof of the presence of the 11-year variation in the moment M has been obtained. It is concluded that the 11-year variations in M result from the variations of the solar wind velocity

Spectral, Photometric, and Dynamic Analysis of Eight Draconid Meteors

Czech Academy of Sciences Publication Activity Database

Borovička, Jiří; Koten, Pavel; Shrbený, Lukáš; Štork, Rostislav; Hornoch, Kamil

2014-01-01

Roč. 113, 1-4 (2014), s. 15-31 ISSN 0167-9295 R&D Projects: GA ČR(CZ) GAP209/11/1382; GA ČR GPP209/11/P651; GA ČR GA205/09/1302 Institutional support: RVO:67985815 Keywords : meteors * meteoroids * Draconids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.667, year: 2014

The 2011 Draconids: The First European Airborne Meteor Observation Campaign

Czech Academy of Sciences Publication Activity Database

Vaubaillon, J.; Koten, Pavel; Margonis, A.; Toth, J.; Rudawska, R.; Gritsevich, M.; Zender, J.; McAuliffe, J.; Pautet, D.; Jenniskens, P.; Koschny, D.; Colas, F.; Bouley, S.; Maquet, L.; Leroy, A.; Lecacheux, J.; Borovička, Jiří; Watanabe, J.; Oberst, J.

2015-01-01

Roč. 114, 3-4 (2015), s. 137-157 ISSN 0167-9295 R&D Projects: GA ČR GA14-25251S Institutional support: RVO:67985815 Keywords : meteors * Draconids * 21P/Giacobini-Zinner Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.659, year: 2015

Long-Term Continuous Double Station Observation of Faint Meteor Showers

Czech Academy of Sciences Publication Activity Database

Vítek, S.; Páta, P.; Koten, Pavel; Fliegel, K.

2016-01-01

Roč. 16, č. 9 (2016), 1493/1-1493/10 ISSN 1424-8220 R&D Projects: GA ČR GA14-25251S Institutional support: RVO:67985815 Keywords : faint meteor shower * meteoroid * CCD camera Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.677, year: 2016

Modeling geomagnetic induced currents in Australian power networks

Science.gov (United States)

Marshall, R. A.; Kelly, A.; Van Der Walt, T.; Honecker, A.; Ong, C.; Mikkelsen, D.; Spierings, A.; Ivanovich, G.; Yoshikawa, A.

2017-07-01

Geomagnetic induced currents (GICs) have been considered an issue for high-latitude power networks for some decades. More recently, GICs have been observed and studied in power networks located in lower latitude regions. This paper presents the results of a model aimed at predicting and understanding the impact of geomagnetic storms on power networks in Australia, with particular focus on the Queensland and Tasmanian networks. The model incorporates a "geoelectric field" determined using a plane wave magnetic field incident on a uniform conducting Earth, and the network model developed by Lehtinen and Pirjola (1985). Model results for two intense geomagnetic storms of solar cycle 24 are compared with transformer neutral monitors at three locations within the Queensland network and one location within the Tasmanian network. The model is then used to assess the impacts of the superintense geomagnetic storm of 29-31 October 2003 on the flow of GICs within these networks. The model results show good correlation with the observations with coefficients ranging from 0.73 to 0.96 across the observing sites. For Queensland, modeled GIC magnitudes during the superstorm of 29-31 October 2003 exceed 40 A with the larger GICs occurring in the south-east section of the network. Modeled GICs in Tasmania for the same storm do not exceed 30 A. The larger distance spans and general east-west alignment of the southern section of the Queensland network, in conjunction with some relatively low branch resistance values, result in larger modeled GICs despite Queensland being a lower latitude network than Tasmania.

Statistical Relationship between Sawtooth Oscillations and Geomagnetic Storms

Directory of Open Access Journals (Sweden)

Jae-Hun Kim

2008-06-01

Full Text Available We have investigated a statistical relationship between sawtooth oscillations and geomagnetic storms during 2000-2004. First of all we selected a total of 154 geomagnetic storms based on the Dst index, and distinguished between different drivers such as Coronal Mass Ejection (CME and Co-rotating Interaction Region (CIR. Also, we identified a total of 48 sawtooth oscillation events based on geosynchronous energetic particle data for the same 2000-2004 period. We found that out of the 154 storms identified, 47 storms indicated the presence of sawtooth oscillations. Also, all but one sawtooth event identified occurred during a geomagnetic storm interval. It was also found that sawtooth oscillation events occur more frequently for storms driven by CME (˜62% than for storms driven by CIR (˜30%. In addition, sawtooth oscillations occurred mainly (˜82% in the main phase of storms for CME-driven storms while they occurred mostly (˜78% during the storm recovery phase for CIR-driven storms. Next we have examined the average characteristics of the Bz component of IMF, and solar wind speed, which were the main components for driving geomagnetic storm. We found that for most of the sawtooth events, the IMF Bz corresponds to --15 to 0 nT and the solar wind speed was in the range of 400˜700 km/s. We found that there was a weak tendency that the number of teeth for a given sawtooth event interval was proportional to the southward IMF Bz magnitude.

The geomagnetic observatory on Tristan da Cunha: Setup, operation and experiences

DEFF Research Database (Denmark)

Matzka, Jürgen; Husøy, Bjørn-Ove; Berarducci, Alan

2011-01-01

The island Tristan da Cunha is located in the South Atlantic Anomaly, and until recently the area has been one of the largest gaps in the global geomagnetic observatory network. As part of the Danish project SAADAN we set up a geomagnetic observatory on the island. Here we report on how we establ...

Meteor Beliefs Project: Shakespeare revisited and the Elizabethan stage's `blazing star'

Science.gov (United States)

Gheorghe, Andrei Dorian; McBeath, Alastair

2007-06-01

Some fresh Shakespearean citations of meteors, further to those given previously in the Project, are presented, along with a discussion of the Elizabethan stage's use of the `blazing star', with especial reference to the great comet of 1577.

Propagation of low frequency geomagnetic field fluctuations in Antarctica: comparison between two polar cap stations

Directory of Open Access Journals (Sweden)

L. Santarelli

2007-11-01

Full Text Available We conduct a statistical analysis of the coherence and phase difference of low frequency geomagnetic fluctuations between two Antarctic stations, Mario Zucchelli Station (geographic coordinates: 74.7° S, 164.1° E; corrected geomagnetic coordinates: 80.0° S, 307.7° E and Scott Base (geographic coordinates: 77.8° S 166.8° E; corrected geomagnetic coordinates: 80.0° S 326.5° E, both located in the polar cap. Due to the relative position of the stations, whose displacement is essentially along a geomagnetic parallel, the phase difference analysis allows to determine the direction of azimuthal propagation of geomagnetic fluctuations. The results show that coherent fluctuations are essentially detectable around local geomagnetic midnight and, in a minor extent, around noon; moreover, the phase difference reverses in the night time hours, indicating a propagation direction away from midnight, and also around local geomagnetic noon, indicating a propagation direction away from the subsolar point. The nigh time phase reversal is more clear for southward interplanetary magnetic field conditions, suggesting a relation with substorm activity. The introduction, in this analysis, of the Interplanetary Magnetic Field conditions, gave interesting results, indicating a relation with substorm activity during nighttime hours. We also conducted a study of three individual pulsation events in order to find a correspondence with the statistical behaviour. In particular, a peculiar event, characterized by quiet magnetospheric and northward interplanetary magnetic field conditions, shows a clear example of waves propagating away from the local geomagnetic noon; two more events, occurring during southward interplanetary magnetic field conditions, in one case even during a moderate storm, show waves propagating away from the local geomagnetic midnight.

Long-Term Geomagnetically Induced Current Observations From New Zealand: Peak Current Estimates for Extreme Geomagnetic Storms

Science.gov (United States)

Rodger, Craig J.; Mac Manus, Daniel H.; Dalzell, Michael; Thomson, Alan W. P.; Clarke, Ellen; Petersen, Tanja; Clilverd, Mark A.; Divett, Tim

2017-11-01

Geomagnetically induced current (GIC) observations made in New Zealand over 14 years show induction effects associated with a rapidly varying horizontal magnetic field (dBH/dt) during geomagnetic storms. This study analyzes the GIC observations in order to estimate the impact of extreme storms as a hazard to the power system in New Zealand. Analysis is undertaken of GIC in transformer number six in Islington, Christchurch (ISL M6), which had the highest observed currents during the 6 November 2001 storm. Using previously published values of 3,000 nT/min as a representation of an extreme storm with 100 year return period, induced currents of 455 A were estimated for Islington (with the 95% confidence interval range being 155-605 A). For 200 year return periods using 5,000 nT/min, current estimates reach 755 A (confidence interval range 155-910 A). GIC measurements from the much shorter data set collected at transformer number 4 in Halfway Bush, Dunedin, (HWB T4), found induced currents to be consistently a factor of 3 higher than at Islington, suggesting equivalent extreme storm effects of 460-1,815 A (100 year return) and 460-2,720 A (200 year return). An estimate was undertaken of likely failure levels for single-phase transformers, such as HWB T4 when it failed during the 6 November 2001 geomagnetic storm, identifying that induced currents of 100 A can put such transformer types at risk of damage. Detailed modeling of the New Zealand power system is therefore required to put this regional analysis into a global context.

Turbulent Diffusion of the Geomagnetic Field and Dynamo Theories

OpenAIRE

Filippi, Enrico

2016-01-01

The thesis deals with the Dynamo Theories of the Earth’s Magnetic Field and mainly deepens the turbulence phenomena in the fluid Earth’s core. Indeed, we think that these phenomena are very important to understand the recent decay of the geomagnetic field. The thesis concerns also the dynamics of the outer core and some very rapid changes of the geomagnetic field observed in the Earth’s surface and some aspects regarding the (likely) isotropic turbulence in the Magnetohydrodynamics. These top...

Evaluation of candidate geomagnetic field models for IGRF-12

OpenAIRE

Erwan Thébault; Christopher C. Finlay; Patrick Alken; Ciaran D. Beggan; Elisabeth Canet; Arnaud Chulliat; Benoit Langlais; V. Lesur; Frank J. Lowes; Chandrasekharan Manoj; Martin Rother; Reyko Schachtschneider

2015-01-01

Background: The 12th revision of the International Geomagnetic Reference Field (IGRF) was issued in December 2014 by the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group V-MOD (http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html). This revision comprises new spherical harmonic main field models for epochs 2010.0 (DGRF-2010) and 2015.0 (IGRF-2015) and predictive linear secular variation for the interval 2015.0-2020.0 (SV-2010-2015). Findings: The models were deri...

Activity of the Leonid meteor shower on 2009 November 17

Czech Academy of Sciences Publication Activity Database

Koten, Pavel; Borovička, Jiří; Kokhirova, G.I.

2011-01-01

Roč. 528, April (2011), A94/1-A94/4 ISSN 0004-6361 R&D Projects: GA ČR GA205/09/1302 Institutional research plan: CEZ:AV0Z10030501 Keywords : meteorites * meteors * meteoroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.587, year: 2011

Long-term biases in geomagnetic K and aa indices

Science.gov (United States)

Love, J.J.

2011-01-01

Analysis is made of the geomagnetic-activity aa index and its source K-index data from groups of ground-based observatories in Britain, and Australia, 1868.0-2009.0, solar cycles 11-23. The K data show persistent biases, especially for high (low) K-activity levels at British (Australian) observatories. From examination of multiple subsets of the K data we infer that the biases are not predominantly the result of changes in observatory location, localized induced magnetotelluric currents, changes in magnetometer technology, or the modernization of K-value estimation methods. Instead, the biases appear to be artifacts of the latitude-dependent scaling used to assign K values to particular local levels of geomagnetic activity. The biases are not effectively removed by weighting factors used to estimate aa. We show that long-term averages of the aa index, such as annual averages, are dominated by medium-level geomagnetic activity levels having K values of 3 and 4. ?? 2011 Author(s).

Long-term biases in geomagnetic K and aa indices

Directory of Open Access Journals (Sweden)

J. J. Love

2011-08-01

Full Text Available Analysis is made of the geomagnetic-activity aa index and its source K-index data from groups of ground-based observatories in Britain, and Australia, 1868.0–2009.0, solar cycles 11–23. The K data show persistent biases, especially for high (low K-activity levels at British (Australian observatories. From examination of multiple subsets of the K data we infer that the biases are not predominantly the result of changes in observatory location, localized induced magnetotelluric currents, changes in magnetometer technology, or the modernization of K-value estimation methods. Instead, the biases appear to be artifacts of the latitude-dependent scaling used to assign K values to particular local levels of geomagnetic activity. The biases are not effectively removed by weighting factors used to estimate aa. We show that long-term averages of the aa index, such as annual averages, are dominated by medium-level geomagnetic activity levels having K values of 3 and 4.

Geomagnetic storm forecasting service StormFocus: 5 years online

Science.gov (United States)

Podladchikova, Tatiana; Petrukovich, Anatoly; Yermolaev, Yuri

2018-04-01

Forecasting geomagnetic storms is highly important for many space weather applications. In this study, we review performance of the geomagnetic storm forecasting service StormFocus during 2011-2016. The service was implemented in 2011 at SpaceWeather.Ru and predicts the expected strength of geomagnetic storms as measured by Dst index several hours ahead. The forecast is based on L1 solar wind and IMF measurements and is updated every hour. The solar maximum of cycle 24 is weak, so most of the statistics are on rather moderate storms. We verify quality of selection criteria, as well as reliability of real-time input data in comparison with the final values, available in archives. In real-time operation 87% of storms were correctly predicted while the reanalysis running on final OMNI data predicts successfully 97% of storms. Thus the main reasons for prediction errors are discrepancies between real-time and final data (Dst, solar wind and IMF) due to processing errors, specifics of datasets.

Stochastic forecasting of the geomagnetic field from the COV-OBS.x1 geomagnetic field model, and candidate models for IGRF-12

DEFF Research Database (Denmark)

Gillet, Nicolas; Barrois, Olivier; Finlay, Chris

2015-01-01

the ‘observations’ uncertainties in data assimilation schemes for the study of the outer core dynamics.We also present and illustrate a stochastic algorithm designed to forecast the geomagnetic field. The radial field at the outer core surface is advected by core motions governed by an auto-regressive process...... filter algorithm. We show that the envelope of forecasts includes the observed secular variation of the geomagnetic field over 5-year intervals, even in the case of rapid changes. In a purpose of testing hypotheses about the core dynamics, this prototype method could be implemented to build the ‘state...

Geomagnetic activity and the global temperature

Czech Academy of Sciences Publication Activity Database

Bucha, Václav

2009-01-01

Roč. 53, č. 4 (2009), s. 571-573 ISSN 0039-3169 Institutional research plan: CEZ:AV0Z30120515 Keywords : global warming * Southern Oscillation * geomagnetic storms Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.000, year: 2009

Geomagnetic radioflash unfold (GRUF)

International Nuclear Information System (INIS)

Malik, J.S.

1975-08-01

A method of inverting the geomagnetic component of the radioflash signal from a nuclear explosion to obtain the gamma-ray time history was proposed by E. D. Dracott of the Atomic Weapons Research Establishment. A simplified development of an elaboration by B. R. Suydam has been programmed for small calculators in a form suitable for interim field analysis of such data. The development of the program is contained in the report

Sub-ionospheric VLF signal anomaly due to geomagnetic storms: a statistical study

Directory of Open Access Journals (Sweden)

K. Tatsuta

2015-11-01

Full Text Available We investigate quantitatively the effect of geomagnetic storms on the sub-ionospheric VLF/LF (Very Low Frequency/Low Frequency propagations for different latitudes based on 2-year nighttime data from Japanese VLF/LF observation network. Three statistical parameters such as average signal amplitude, variability of the signal amplitude, and nighttime fluctuation were calculated daily for 2 years for 16–21 independent VLF/LF transmitter–receiver propagation paths consisting of three transmitters and seven receiving stations. These propagation paths are suitable to simultaneously study high-latitude, low-mid-latitude and mid-latitude D/E-region ionospheric properties. We found that these three statistical parameters indicate significant anomalies exceeding at least 2 times of their standard deviation from the mean value during the geomagnetic storm time period in the high-latitude paths with an occurrence rate of anomaly between 40 and 50 % presumably due to the auroral energetic electron precipitation. The mid-latitude and low-mid-latitude paths have a smaller influence from the geomagnetic activity because of a lower occurrence rate of anomalies even during the geomagnetically active time period (from 20 to 30 %. The anomalies except geomagnetic storm periods may be caused by atmospheric and/or lithospheric origins. The statistical occurrence rates of ionospheric anomalies for different latitudinal paths during geomagnetic storm and non-storm time periods are basic and important information not only to identify the space weather effects toward the lower ionosphere depending on the latitudes but also to separate various external physical causes of lower ionospheric disturbances.

An analytical theory of a scattering of radio waves on meteoric ionization - II. Solution of the integro-differential equation in case of backscatter

Science.gov (United States)

Pecina, P.

2016-12-01

The integro-differential equation for the polarization vector P inside the meteor trail, representing the analytical solution of the set of Maxwell equations, is solved for the case of backscattering of radio waves on meteoric ionization. The transversal and longitudinal dimensions of a typical meteor trail are small in comparison to the distances to both transmitter and receiver and so the phase factor appearing in the kernel of the integral equation is large and rapidly changing. This allows us to use the method of stationary phase to obtain an approximate solution of the integral equation for the scattered field and for the corresponding generalized radar equation. The final solution is obtained by expanding it into the complete set of Bessel functions, which results in solving a system of linear algebraic equations for the coefficients of the expansion. The time behaviour of the meteor echoes is then obtained using the generalized radar equation. Examples are given for values of the electron density spanning a range from underdense meteor echoes to overdense meteor echoes. We show that the time behaviour of overdense meteor echoes using this method is very different from the one obtained using purely numerical solutions of the Maxwell equations. Our results are in much better agreement with the observations performed e.g. by the Ondřejov radar.

The beginning heights and light curves of high-altitude meteors

Czech Academy of Sciences Publication Activity Database

Koten, Pavel; Spurný, Pavel; Borovička, Jiří; Evans, S.; Elliott, A.; Betlem, H.; Štork, Rostislav; Jobse, K.

2006-01-01

Roč. 41, č. 9 (2006), s. 1305-1320 ISSN 1086-9379 R&D Projects: GA ČR GP205/02/P038 Institutional research plan: CEZ:AV0Z10030501 Keywords : bright Leonid meteors * atmospheric trajectories Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.524, year: 2006

Propagation of low frequency geomagnetic field fluctuations in Antarctica: comparison between two polar cap stations

Directory of Open Access Journals (Sweden)

L. Santarelli

2007-11-01

Full Text Available We conduct a statistical analysis of the coherence and phase difference of low frequency geomagnetic fluctuations between two Antarctic stations, Mario Zucchelli Station (geographic coordinates: 74.7° S, 164.1° E; corrected geomagnetic coordinates: 80.0° S, 307.7° E and Scott Base (geographic coordinates: 77.8° S 166.8° E; corrected geomagnetic coordinates: 80.0° S 326.5° E, both located in the polar cap. Due to the relative position of the stations, whose displacement is essentially along a geomagnetic parallel, the phase difference analysis allows to determine the direction of azimuthal propagation of geomagnetic fluctuations. The results show that coherent fluctuations are essentially detectable around local geomagnetic midnight and, in a minor extent, around noon; moreover, the phase difference reverses in the night time hours, indicating a propagation direction away from midnight, and also around local geomagnetic noon, indicating a propagation direction away from the subsolar point. The nigh time phase reversal is more clear for southward interplanetary magnetic field conditions, suggesting a relation with substorm activity.

The introduction, in this analysis, of the Interplanetary Magnetic Field conditions, gave interesting results, indicating a relation with substorm activity during nighttime hours.

We also conducted a study of three individual pulsation events in order to find a correspondence with the statistical behaviour. In particular, a peculiar event, characterized by quiet magnetospheric and northward interplanetary magnetic field conditions, shows a clear example of waves propagating away from the local geomagnetic noon; two more events, occurring during southward interplanetary magnetic field conditions, in one case even during a moderate storm, show waves propagating away from the local geomagnetic midnight.

The METEOR/TRANSURANUS fuel performance code

International Nuclear Information System (INIS)

Struzik, C.; Guerin, Y.

1996-01-01

The first calculations for the FUMEX exercise were performed using version 1.1 of the METEOR/TRANSURANUS code. Since then, important improvements have been implemented on several models. In its present state, the code describes fuel rod behaviour in standard PWR conditions. Its validity extends to UO 2 and MOX fuels clad in Zircaloy-4. Power transient calculations for UO 2 and Gd doped fuel calculations are possible, but further developments are in progress, and the applications will be fully qualified in version 2.0. A considerable effort is made to replace semi-empirical models with models that have a sounder physical basis. (authors). 14 refs

Geomagnetic activity effects on plasma sheet energy conversion

Directory of Open Access Journals (Sweden)

M. Hamrin

2010-10-01

Full Text Available In this article we use three years (2001, 2002, and 2004 of Cluster plasma sheet data to investigate what happens to localized energy conversion regions (ECRs in the plasma sheet during times of high magnetospheric activity. By examining variations in the power density, E·J, where E is the electric field and J is the current density obtained by Cluster, we have studied the influence on Concentrated Load Regions (CLRs and Concentrated Generator Regions (CGRs from variations in the geomagnetic disturbance level as expressed by the Kp, the AE, and the Dst indices. We find that the ECR occurrence frequency increases during higher magnetospheric activities, and that the ECRs become stronger. This is true both for CLRs and for CGRs, and the localized energy conversion therefore concerns energy conversion in both directions between the particles and the fields in the plasma sheet. A higher geomagnetic activity hence increases the general level of energy conversion in the plasma sheet. Moreover, we have shown that CLRs live longer during magnetically disturbed times, hence converting more electromagnetic energy. The CGR lifetime, on the other hand, seems to be unaffected by the geomagnetic activity level. The evidence for increased energy conversion during geomagnetically disturbed times is most clear for Kp and for AE, but there are also some indications that energy conversion increases during large negative Dst. This is consistent with the plasma sheet magnetically mapping to the auroral zone, and therefore being more tightly coupled to auroral activities and variations in the AE and Kp indices, than to variations in the ring current region as described by the Dst index.

The geomagnetic field - An explanation for the microturbulence in coaxial gun plasmas

International Nuclear Information System (INIS)

Mather, J.W.; Ahluwalia, H.S.

1988-01-01

The authors describe the complexity introduced by the geomagnetic field in several regions of a coaxial gun plasma device. It is shown that the annihilation of the swept-up geomagnetic flux, trapped within the highly compressed turbulent plasma, provides an explanation for varied performance and experimental results

Circulation of the polar thermosphere during geomagnetically quiet and active times as observed by Dynamics Explorer 2

International Nuclear Information System (INIS)

McCormac, F.G.; Killeen, T.L.; Thayer, J.P.; Hernandez, G.; Tschan, C.R.; Ponthieu, J.J.; Spencer, N.W.

1987-01-01

Neutral wind measurements obtained by instruments on board the Dynamics Explorer 2 (DE 2) spacecraft have been used to study the effects of geomagnetic activity on the circulation of the high-latitude neutral thermosphere for solar maximum conditions during the periods of November 1981 through January 1982 and November 1982 through January 1983. The data have been sorted and ordered according to the two geophysical indices Kp and (auroral electrojet) AE. Simple expressions have been derived which describe (1) the maximum antisunward wind speed in the geomagnetic polar cap, (2) the maximum sunward wind speeds in the dawn and dusk sectors of the auroral oval, and (3) the latitudinal extent of the polar cap antisunward neutral wind as functions of Kp and AE. The results show a positive correlation between the geomagnetic indices and the three characteristic features of the neutral circulation described above. Averaged vector wind fields in geomagnetic coordinates for Kp ≤ 2 and Kp ≥ 4 in both northern and southern hemispheres for the 6 months have been derived from the data. In doing this, a first-order invariance of the neutral wind circulation in geomagnetic coordinates as a function of universal time (UT) was assumed. The results show a two-cell circulation pattern in the northern winter hemisphere for both quiet and active geomagnetic periods. The cell sizes increase with increasing geomagnetic activity. The dusk cell is always dominant. The southern summer hemisphere averages show only the dusk circulation cell for both quiet and active geomagnetic periods. The cell sizes increase with increasing geomagnetic activity. The dusk cell is always dominant. The southern summer hemisphere averages show only the dusk circulation cell for both quiet and active geomagnetic periods. A diminution of this cell occurs for reduced levels of geomagnetic activity

Effect of geomagnetic storms on the daytime low-latitude thermospheric wave dynamics

Science.gov (United States)

Karan, Deepak K.; Pallamraju, Duggirala

2018-05-01

The equatorial- and low-latitude thermospheric dynamics is affected by both equatorial electrodynamics and neutral wave dynamics, the relative variation of which is dependent on the prevalent background conditions, which in turn has a seasonal dependence. Depending on the ambient thermospheric conditions, varying effects of the geomagnetic disturbances on the equatorial- and low-latitude thermosphere are observed. To investigate the effect of these disturbances on the equatorial- and low-latitude neutral wave dynamics, daytime airglow emission intensities at OI 557.7 nm, OI 630.0 nm, and OI 777.4 nm are used. These emissions from over a large field-of-view (FOV∼1000) have been obtained using a high resolution slit spectrograph, MISE (Multiwavelength Imaging Spectrograph using Echelle grating), from a low-latitude location, Hyderabad (17.50N, 78.40E; 8.90N MLAT), in India. Variations of the dayglow emission intensities are investigated during three geomagnetic disturbance events that occurred in different seasons. It is seen that the neutral dayglow emission intensities at all the three wavelengths showed different type of variations with the disturbance storm time (Dst) index in different seasons. Even though the dayglow emission intensities over low-latitude regions are sensitive to the variation in the equatorial electric fields, during periods of geomagnetic disturbances, especially in solstices, these are dependent on thermospheric O/N2 values. This shows the dominance of neutral dynamics over electrodynamics in the low-latitude upper atmosphere during geomagnetic disturbances. Further, spectral analyses have been carried out to obtain the zonal scale sizes in the gravity wave regime and their diurnal distributions are compared for geomagnetic quiet and disturbed days. Broadly, the zonal scales seem to be breaking into various scale sizes on days of geomagnetic disturbances when compared to those on quiet days. This contrast in the diurnal distribution of the

Properties of Pliocene sedimentary geomagnetic reversal records from the Mediterranean

OpenAIRE

Linssen, J.H.

1991-01-01

In the history of the Earth the dipolar geomagnetic field has frequently reversed polarity. Though this property was already known early this century (Brunhes, 1906), nowadays the characteristics and the origin of polarity transitions are still largely unknown. The geomagnetic field and its variations are recorded in rocks as a natural remanent magnetization (NRM) during the formation of these rocks. The study of the NRM in sedimentary reversal records is the subject of this dissertation.

Simultaneous optical and meteor head echo measurements using the Middle Atmosphere Alomar Radar System (MAARSY): Data collection and preliminary analysis

Science.gov (United States)

Brown, P.; Stober, G.; Schult, C.; Krzeminski, Z.; Cooke, W.; Chau, J. L.

2017-07-01

The initial results of a two year simultaneous optical-radar meteor campaign are described. Analysis of 105 double-station optical meteors having plane of sky intersection angles greater than 5° and trail lengths in excess of 2 km also detected by the Middle Atmosphere Alomar Radar System (MAARSY) as head echoes was performed. These events show a median deviation in radiants between radar and optical determinations of 1.5°, with 1/3 of events having radiant agreement to less than one degree. MAARSY tends to record average speeds roughly 0.5 km/s and 1.3 km higher than optical records, in part due to the higher sensitivity of MAARSY as compared to the optical instruments. More than 98% of all head echoes are not detected with the optical system. Using this non-detection ratio and the known limiting sensitivity of the cameras, we estimate that the limiting meteoroid detection mass of MAARSY is in the 10-9-10-10 kg (astronomical limiting meteor magnitudes of +11 to +12) appropriate to speeds from 30 to 60 km/s. There is a clear trend of higher peak RCS for brighter meteors between 35 and -30 dBsm. For meteors with similar magnitudes, the MAARSY head echo radar cross-section is larger at higher speeds. Brighter meteors at fixed heights and similar speeds have consistently, on average, larger RCS values, in accordance with established scattering theory. However, our data show RCS ∝ v/2, much weaker than the normally assumed RCS ∝ v3, a consequence of our requiring head echoes to also be detectable optically. Most events show a smooth variation of RCS with height broadly following the light production behavior. A significant minority of meteors show large variations in RCS relative to the optical light curve over common height intervals, reflecting fragmentation or possibly differential ablation. No optically detected meteor occurring in the main radar beam and at times when the radar was collecting head echo data went unrecorded by MAARSY. Thus there does not

Characterization and demonstration results of a SQUID magnetometer system developed for geomagnetic field measurements

Science.gov (United States)

Kawai, J.; Miyamoto, M.; Kawabata, M.; Nosé, M.; Haruta, Y.; Uehara, G.

2017-08-01

We characterized a low temperature superconducting quantum interference device (SQUID) magnetometer system developed for high-sensitivity geomagnetic field measurement, and demonstrated the detection of weak geomagnetic signals. The SQUID magnetometer system is comprised of three-axis SQUID magnetometers housed in a glass fiber reinforced plastic cryostat, readout electronics with flux locked loop (FLL), a 24-bit data logger with a global positioning system and batteries. The system noise was approximately 0.2 pT √Hz- 1/2 in the 1-50 Hz frequency range. This performance was determined by including the thermal noise and the shielding effect of the copper shield, which covered the SQUID magnetometers to eliminate high-frequency interference. The temperature drift of the system was ˜0.8 pT °C- 1 in an FLL operation. The system operated for a month using 33 l liquid helium. Using this system, we performed the measurements of geomagnetic field in the open-air, far away from the city. The system could detect weak geomagnetic signals such as the Schumann resonance with sixth harmonics, and the ionospheric Alfvén resonance appearing at night, for the north-south and east-west components of the geomagnetic field. We confirm that the system was capable of high-sensitivity measurement of the weak geomagnetic activities.

Early diagenesis driven by widespread meteoric infiltration of a Central European carbonate ramp: A reinterpretation of the Upper Muschelkalk

Science.gov (United States)

Adams, Arthur; Diamond, Larryn W.

2017-12-01

Meteoric diagenesis of carbonate ramps is often difficult to interpret and can commonly be confused with other coinciding diagenetic processes. The Middle Triassic Upper Muschelkalk of Switzerland provides an insightful case in which the effects of several overprinting diagenetic environments, including matrix dolomitization, can be clearly unravelled. Previous studies suggested that diagenesis took place in connate marine waters, with later meteoric waters being invoked to explain recrystallization of dolomite. In this study, diagenetic analyses (C-O stable isotope ratios, thin-section point counting, cathodoluminescence and UV-fluorescence microscopy) of calcitic bioclastic samples have revealed that early diagenesis (pre-stylolitization) and the accompanying porosity evolution did not occur exclusively in the presence of marine fluids. Five sequential stages of diagenesis have been identified: marine, shallow burial, mixing-zone, meteoric and dolomitization. Marine diagenesis induced precipitation of bladed and inclusion-rich syntaxial cements that fluoresce strongly under UV-light. Both cements account for a mean 7.5 vol% reduction in the porosity of bioclastic beds. Shallow burial diagenesis likely induced mouldic porosity and associated fluorescent dog-tooth cementation. Based on light oxygen isotope and elevated strontium isotope ratios, matrix aragonite-calcite neomorphism is interpreted to have occurred in a mixture of marine and meteoric fluids. The combination of shallow burial and mixing-zone processes reduced porosity on average by 4.8 vol%. Evidence for subsequent meteoric diagenesis is found in abundant dog-tooth and blocky calcite cements that have mean δ18OVPDB of - 9.36‰ and no signs of recrystallization. These meteoric cements reduced porosity by a further 13.4 vol%. Percolation of meteoric water through the ramp was driven by hydraulic gradients on an adjacent basement high, which was exposed by a cycle of early Ladinian regressions

Evaluation of candidate geomagnetic field models for IGRF-12

DEFF Research Database (Denmark)

Thébault, Erwan; Finlay, Chris; Alken, Patrick

2015-01-01

Background: The 12th revision of the International Geomagnetic Reference Field (IGRF) was issued in December 2014 by the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group V-MOD (http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html). This revision comprises new spherical...... by the British Geological Survey (UK), DTU Space (Denmark), ISTerre (France), IZMIRAN (Russia), NOAA/NGDC (USA), GFZ Potsdam (Germany), NASA/GSFC (USA), IPGP (France), LPG Nantes (France), and ETH Zurich (Switzerland). Each candidate model was carefully evaluated and compared to all other models and a mean model...

Analysis of Total Electron Content and Electron Density Profile during Different Geomagnetic Storms

Science.gov (United States)

Chapagain, N. P.; Rana, B.; Adhikari, B.

2017-12-01

Total Electron content (TEC) and electron density are the key parameters in the mitigation of ionospheric effects on radio communication system. Detail study of the TEC and electron density variations has been carried out during geomagnetic storms, with longitude and latitude, for four different locations: (13˚N -17˚N, 88˚E -98˚E), (30˚N-50˚N, 120˚W -95˚W), (29˚S-26˚S, 167˚W-163˚W,) and (60˚S-45˚S, 120˚W-105˚W) using the Gravity Recovery and Climate Experiment (GRACE) satellite observations. In order to find the geomagnetic activity, the solar wind parameters such as north-south component of inter planetary magnetic field (Bz), plasma drift velocity (Vsw), flow pressure (nPa), AE, Dst and Kp indices were obtained from Operating Mission as Nodes on the Internet (OMNI) web system. The data for geomagnetic indices have been correlated with the TEC and electron density for four different events of geomagnetic storms on 6 April 2008, 27 March 2008, 4 September 2008, and 11 October 2008. The result illustrates that the observed TEC and electron density profile significantly vary with longitudes and latitudes. This study illustrates that the values of TEC and the vertical electron density profile are influenced by the solar wind parameters associated with solar activities. The peak values of electron density and TEC increase as the geomagnetic storms become stronger. Similarly, the electron density profile varies with altitudes, which peaks around the altitude range of about 250- 350 km, depending on the strength of geomagnetic storms. The results clearly show that the peak electron density shifted to higher altitude (from about 250 km to 350 km) as the geomagnetic disturbances becomes stronger.

Long-term rise in geomagnetic activity - A close connection between quiet days and storms

DEFF Research Database (Denmark)

Vennerstrøm, Susanne

2000-01-01

Geomagnetic quiet days and magnetic storms are naturally believed to be due to very different solar wind conditions. In this study we however demonstrate that the long-term variation of geomagnetic quiet and disturbed days are surprisingly similar. By the use of daily averages of the geomagnetic.......7. The results indicate that the longterm,increase is due to an increase in the background solar wind parameters, rather than in the number of solar wind disturbances....

Knut Lundmark, meteors and an early Swedish crowdsourcing experiment.

Science.gov (United States)

Kärnfelt, Johan

2014-10-01

Mid twentieth century meteor astronomy demanded the long-term compilation of observations made by numerous individuals over an extensive geographical area. Such a massive undertaking obviously required the participation of more than just professional astronomers, who often sought to expand their ranks through the use of amateurs that had a basic grasp of astronomy as well as the night sky, and were thus capable of generating first-rate astronomical reports. When, in the 1920s, renowned Swedish astronomer Knut Lundmark turned his attention to meteor astronomy, he was unable to rely even upon this solution. In contrast to many other countries at the time, Sweden lacked an organized amateur astronomy and thus contained only a handful of competent amateurs. Given this situation, Lundmark had to develop ways of engaging the general public in assisting his efforts. To his advantage, he was already a well-established public figure who had published numerous popular science articles and held talks from time to time on the radio. During the 1930s, this prominence greatly facilitated his launching of a crowdsourcing initiative for the gathering of meteor observations. This paper consists of a detailed discussion concerning the means by which Lundmark's initiative disseminated astronomical knowledge to the general public and encouraged a response that might directly contribute to the advancement of science. More precisely, the article explores the manner in which he approached the Swedish public, the degree to which that public responded and the extent to which his efforts were successful. The primary aim of this exercise is to show that the apparently recent Internet phenomenon of 'crowdsourcing', especially as it relates to scientific research, actually has a pre-Internet history that is worth studying. Apart from the fact that this history is interesting in its own right, knowing it can provide us with a fresh vantage point from which to better comprehend and appreciate

The Southern Argentina Agile Meteor Radar Orbital System (SAAMER-OS): An Initial Sporadic Meteoroid Orbital Survey in the Southern Sky

Science.gov (United States)

Janches, D.; Close, S.; Hormaechea, J. L.; Swarnalingam, N.; Murphy, A.; O'Connor, D.; Vandepeer, B.; Fuller, B.; Fritts, D. C.; Brunini, C.

2015-01-01

We present an initial survey in the southern sky of the sporadic meteoroid orbital environment obtained with the Southern Argentina Agile MEteor Radar (SAAMER) Orbital System (OS), in which over three-quarters of a million orbits of dust particles were determined from 2012 January through 2015 April. SAAMER-OS is located at the southernmost tip of Argentina and is currently the only operational radar with orbit determination capability providing continuous observations of the southern hemisphere. Distributions of the observed meteoroid speed, radiant, and heliocentric orbital parameters are presented, as well as those corrected by the observational biases associated with the SAAMER-OS operating parameters. The results are compared with those reported by three previous surveys performed with the Harvard Radio Meteor Project, the Advanced Meteor Orbit Radar, and the Canadian Meteor Orbit Radar, and they are in agreement with these previous studies. Weighted distributions for meteoroids above the thresholds for meteor trail electron line density, meteoroid mass, and meteoroid kinetic energy are also considered. Finally, the minimum line density and kinetic energy weighting factors are found to be very suitable for meteoroid applications. The outcomes of this work show that, given SAAMERs location, the system is ideal for providing crucial data to continuously study the South Toroidal and South Apex sporadic meteoroid apparent sources.

Geographical localisation of the geomagnetic secular variation

DEFF Research Database (Denmark)

Aubert, Julien; Finlay, Chris; Olsen, Nils

2013-01-01

the model and geomagnetic data previously processed in the same way. Our results suggest that conservation of angular momentum and heterogeneous thermochemical boundary control in the coupled inner core / outer core / mantle system are central to understanding how Earth’s magnetic field currently evolves......., westward moving, magnetic flux patches at the core surface. Despite its successes in explaining the main morphological properties of Earth’s magnetic field, self-consistent numerical modelling of the geodynamo has so far failed to reproduce this field variation pattern. Furthermore its magnetohydrodynamic...... control from either, or both, the inner-core boundary and the core-mantle boundary. In addition to presenting an Earth-like magnetic field morphology, these new numerical models also reproduce the morphology and localization of geomagnetic secular variation. In our models, the conservation of the angular...

Mathematical Properties Relevant to Geomagnetic Field Modeling

DEFF Research Database (Denmark)

Sabaka, Terence J.; Hulot, Gauthier; Olsen, Nils

2010-01-01

be directly measured. In this chapter, the mathematical foundation of global (as opposed to regional) geomagnetic field modeling is reviewed, and the spatial modeling of the field in spherical coordinates is focussed. Time can be dealt with as an independent variable and is not explicitly considered......Geomagnetic field modeling consists in converting large numbers of magnetic observations into a linear combination of elementary mathematical functions that best describes those observations.The set of numerical coefficients defining this linear combination is then what one refers.......The relevant elementary mathematical functions are introduced, their properties are reviewed, and how they can be used to describe the magnetic field in a source-free (such as the Earth’s neutral atmosphere) or source-dense (such as the ionosphere) environment is explained. Completeness and uniqueness...

Mathematical Properties Relevant to Geomagnetic Field Modeling

DEFF Research Database (Denmark)

Sabaka, Terence J.; Hulot, Gauthier; Olsen, Nils

2014-01-01

be directly measured. In this chapter, the mathematical foundation of global (as opposed to regional) geomagnetic field modeling is reviewed, and the spatial modeling of the field in spherical coordinates is focused. Time can be dealt with as an independent variable and is not explicitly considered......Geomagnetic field modeling consists in converting large numbers of magnetic observations into a linear combination of elementary mathematical functions that best describes those observations. The set of numerical coefficients defining this linear combination is then what one refers....... The relevant elementary mathematical functions are introduced, their properties are reviewed, and how they can be used to describe the magnetic field in a source-free (such as the Earth’s neutral atmosphere) or source-dense (such as the ionosphere) environment is explained. Completeness and uniqueness...

Geomagnetic storms in the Antarctic F-region

International Nuclear Information System (INIS)

Wrenn, G.L.; Rodger, A.S.; Rishbeth, H.

1987-01-01

New analysis procedures are used to show that the main phase mid-latitude storm effects conform to consistent patterns in local time when suitable selection rules are applied, with averaging over several years. Changes in the maximum plasma frequency, foF2, with respect to estimated quiet-time values, are analysed in terms of asub(p)(t), a new geomagnetic index derived to take account of integrated disturbance. Reduction of foF2 is greatest during the early morning hours, in summer, at higher geomagnetic latitudes, near solar minimum and through the more active periods. The various dependencies are quantitatively determined for the first time by creating an average 'steady state' disturbance, rather than following specific storm events. This approach permits tests of competing theories using available modelling programs. (author)

Midlatitude cooling caused by geomagnetic field minimum during polarity reversal.

Science.gov (United States)

Kitaba, Ikuko; Hyodo, Masayuki; Katoh, Shigehiro; Dettman, David L; Sato, Hiroshi

2013-01-22

The climatic effects of cloud formation induced by galactic cosmic rays (CRs) has recently become a topic of much discussion. The CR-cloud connection suggests that variations in geomagnetic field intensity could change climate through modulation of CR flux. This hypothesis, however, is not well-tested using robust geological evidence. Here we present paleoclimate and paleoenvironment records of five interglacial periods that include two geomagnetic polarity reversals. Marine oxygen isotope stages 19 and 31 contain both anomalous cooling intervals during the sea-level highstands and the Matuyama-Brunhes and Lower Jaramillo reversals, respectively. This contrasts strongly with the typical interglacial climate that has the temperature maximum at the sea-level peak. The cooling occurred when the field intensity dropped to 40% increase in CR flux. The climate warmed rapidly when field intensity recovered. We suggest that geomagnetic field intensity can influence global climate through the modulation of CR flux.

Geomagnetic storms, super-storms, and their impacts on GPS-based navigation systems

Science.gov (United States)

Astafyeva, E.; Yasyukevich, Yu.; Maksikov, A.; Zhivetiev, I.

2014-07-01

Using data of GPS receivers located worldwide, we analyze the quality of GPS performance during four geomagnetic storms of different intensity: two super-storms and two intense storms. We show that during super-storms the density of GPS Losses-of-Lock (LoL) increases up to 0.25% at L1 frequency and up to 3% at L2 frequency, and up to 0.15% (at L1) and 1% (at L2) during less intense storms. Also, depending on the intensity of the storm time ionospheric disturbances, the total number of total electron content (TEC) slips can exceed from 4 to 40 times the quiet time level. Both GPS LoL and TEC slips occur during abrupt changes of SYM-H index of geomagnetic activity, i.e., during the main phase of geomagnetic storms and during development of ionospheric storms. The main contribution in the total number of GPS LoL was found to be done by GPS sites located at low and high latitudes, whereas the area of numerous TEC slips seemed to mostly correspond to the boundary of the auroral oval, i.e., region with intensive ionospheric irregularities. Our global maps of TEC slips show where the regions with intense irregularities of electron density occur during geomagnetic storms and will let us in future predict appearance of GPS errors for geomagnetically disturbed conditions.

Statistical Properties of Geomagnetic Activity Indices and Solar Wind Parameters

Directory of Open Access Journals (Sweden)

Jung-Hee Kim

2014-06-01

Full Text Available As the prediction of geomagnetic storms is becoming an important and practical problem, conditions in the Earth’s magnetosphere have been studied rigorously in terms of those in the interplanetary space. Another approach to space weather forecast is to deal with it as a probabilistic geomagnetic storm forecasting problem. In this study, we carry out detailed statistical analysis of solar wind parameters and geomagnetic indices examining the dependence of the distribution on the solar cycle and annual variations. Our main findings are as follows: (1 The distribution of parameters obtained via the superimposed epoch method follows the Gaussian distribution. (2 When solar activity is at its maximum the mean value of the distribution is shifted to the direction indicating the intense environment. Furthermore, the width of the distribution becomes wider at its maximum than at its minimum so that more extreme case can be expected. (3 The distribution of some certain heliospheric parameters is less sensitive to the phase of the solar cycle and annual variations. (4 The distribution of the eastward component of the interplanetary electric field BV and the solar wind driving function BV2, however, appears to be all dependent on the solar maximum/minimum, the descending/ascending phases of the solar cycle and the equinoxes/solstices. (5 The distribution of the AE index and the Dst index shares statistical features closely with BV and BV2 compared with other heliospheric parameters. In this sense, BV and BV2 are more robust proxies of the geomagnetic storm. We conclude by pointing out that our results allow us to step forward in providing the occurrence probability of geomagnetic storms for space weather and physical modeling.

Geomagnetism solid Earth and upper atmosphere perspectives

CERN Document Server

Basavaiah, Nathani

2011-01-01

This volume elaborates several important aspects of solid Earth geomagnetism. It covers all the basics of the subject, including biomagnetism and instrumentation, and offers a number of practical applications with carefully selected examples and illustrations.

Plasmaspheric noise radiation during geomagnetic storms

International Nuclear Information System (INIS)

Larkina, V.I.; Likhter, Ya.I.

1981-01-01

Variations of plasmospheric background radiations during geomagnetic storms of different intensity are investigated. Used are results of ELF and VLF radiation measurements as well as electron fluxes of energies Esub(e)>40 keV carried out by Intercosmos 3 and Intercosmos 5 satellites. Dependences of radiation amplitude variations at 1.6 and 25 kHz frequencies on L shell for various geomagnetic activity in the day-time as well as data on variations of quasicaptured electron fluxes at Esub(e)>40 keV, are given. It is shown that experimental data agree with the existing theories of plasmospheric noise excitation. It is concluded that the plasmospheric noise excitation area Lsub(max) is always in the region of gap between radiation belts and inner slope of external radiation belt during magnetic storms. During magnetic storms Lsub(max) area moves simultaneously with the area, where particle flux of the external radiation belt is the most intensive [ru

Simulation of the cosmic ray Moon shadow in the geomagnetic field

International Nuclear Information System (INIS)

Di Sciascio, Giuseppe; Iuppa, Roberto

2011-01-01

An accurate Monte Carlo simulation of the deficit of primary cosmic rays in the direction of the Moon has been developed to interpret the observations reported in the TeV energy region until now. Primary particles are propagated through the geomagnetic field in the Earth-Moon system. The algorithm is described and the contributions of the detector resolution and of the geomagnetic field are disentangled.

Space Weather Monitoring for ISS Geomagnetic Storm Studies

Science.gov (United States)

Minow, Joseph I.; Parker, Linda Neergaard

2013-01-01

The International Space Station (ISS) space environments community utilizes near real time space weather data to support a variety of ISS engineering and science activities. The team has operated the Floating Potential Measurement Unit (FPMU) suite of plasma instruments (two Langmuir probes, a floating potential probe, and a plasma impedance probe) on ISS since 2006 to obtain in-situ measurements of plasma density and temperature along the ISS orbit and variations in ISS frame potential due to electrostatic current collection from the plasma environment (spacecraft charging) and inductive (vxB) effects from the vehicle motion across the Earth s magnetic field. An ongoing effort is to use FPMU for measuring the ionospheric response to geomagnetic storms at ISS altitudes and investigate auroral charging of the vehicle as it passes through regions of precipitating auroral electrons. This work is challenged by restrictions on FPMU operations that limit observation time to less than about a third of a year. As a result, FPMU campaigns ranging in length from a few days to a few weeks are typically scheduled weeks in advance for ISS engineering and payload science activities. In order to capture geomagnetic storm data under these terms, we monitor near real time space weather data from NASA, NOAA, and ESA sources to determine solar wind disturbance arrival times at Earth likely to be geoeffective (including coronal mass ejections and high speed streams associated with coronal holes) and activate the FPMU ahead of the storm onset. Using this technique we have successfully captured FPMU data during a number of geomagnetic storm periods including periods with ISS auroral charging. This presentation will describe the strategies and challenges in capturing FPMU data during geomagnetic storms, the near real time space weather resources utilized for monitoring the space weather environment, and provide examples of auroral charging data obtained during storm operations.

Fourteen years of geomagnetic daily variation at Mario Zucchelli Station (Antarctica

Directory of Open Access Journals (Sweden)

A. Meloni

2007-06-01

Full Text Available During the 1986-87 austral summer a geomagnetic observatory was installed at the Italian Antarctic Base Mario Zucchelli Station. In the first three years continuous time variation monitoring and absolute measurements of the geomagnetic field were carried out only during summer expeditions. Starting 1991 an automatic acquisition system, operating through all the year, was put in operation. We present here some peculiarities of the daily variation as observed for fourteen years (1987-2000. The availability of a long series of data has allowed the definition of seasonal, as well as solar cycle effects, on short time variations as observed at a cusp-cap observatory. In particular, contrary to mid latitude behaviour, a clear dependence of the daily variation amplitude on the global geomagnetic K index was well defined.

Initial results from SKiYMET meteor radar at Thumba (8.5°N, 77°E): 2. Gravity wave observations in the MLT region

Science.gov (United States)

Kumar, Karanam Kishore; Antonita, T. Maria; Shelbi, S. T.

2007-12-01

In the present communication, allSKy interferometric METeor (SKiYMET) radar observations of gravity wave activity in the mesosphere lower thermosphere (MLT) region over Thumba (8.5°N, 77°E) are presented. The present meteor radar system provides hourly zonal and meridional winds in the MLT region, which can be readily used for studying the tides, planetary waves, gravity waves of periods 2-6 hours, and other long period oscillations in this region. However, these hourly winds are not sufficient for studying short period gravity waves having periods less than an hour, which demand high temporal resolution measurements. Even though the winds are estimated on an hourly basis, information such as zenith angle, azimuth angle, and radial velocity of each detected meteor are archived. Using these details of the meteor, an algorithm is developed to obtain the 15-min temporal resolution wind data. The output of the algorithm is compared with hourly wind data, and it showed a good agreement during the high meteor shower periods. Most of the times high meteor counts are observed during late night and early morning hours (local) over this latitude. Continuous wind measurements during the high meteor shower periods are used for studying the gravity wave activity in the MLT region. As the wave activity is intermittent and nonstationary, wavelet analysis has been used for delineating the wave features. The results showed the upward propagating intermittent gravity waves with periods 1-2 and 4-5 hours. The new aspect of the present communication is the usage of meteor radar for gravity wave studies for the first time over this latitude and studying their seasonal variability.

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)

Modelling the motion of meteors in the Earth's atmosphere

International Nuclear Information System (INIS)

Rodrigues, Hilário

2013-01-01

This work discusses the motion of meteors in the Earth's atmosphere. The equations of motion of the projectile are presented and a simplified numerical approach to solve them is discussed. An algorithm for solving the equations of motion is constructed, and implemented in a very simple way using Excel software. The paper is intended as an example of the application of Newton's laws of motion at undergraduate level. (paper)

Volcano Popocatepetl, Mexico: ULF geomagnetic anomalies observed at Tlamacas station during March–July, 2005

Directory of Open Access Journals (Sweden)

A. Kotsarenko

2007-01-01

Full Text Available In this paper the first results of ULF (Ultra Low Frequency geomagnetic anomalies observed at Tlamacas station (Long. 261.37, Lat. 19.07 located at 4 km near the volcano Popocatepetl (active volcano, Long. 261.37, Lat. 19.02 for the period March–July, 2005 and their analysis are presented. The geomagnetic data were collected with a 3-axial fluxgate magnetometer designed at UCLA (University of California, Los Angeles, 1 Hz sampling rate frequency, GPS. Our analysis reveals some anomalies which are suspected to be generated by local volcanic origin: the EM background in the vicinity of the volcano is significantly noisier than in other reference stations; the sporadic strong noise-like geomagnetic activity observed in the H-component; locally generated geomagnetic pulsations (without preferred polarization are detected only at Tlamacas station.

F layer positive response to a geomagnetic storm - June 1972

International Nuclear Information System (INIS)

Miller, N.J.; Grebowsky, J.M.; Mayr, H.G.; Harris, I.; Tulunay, Y.K.

1979-01-01

A circulation model of neutral thermosphere-ionosphere coupling is used to interpret in situ spacecraft measurements taken during a topside mid-latitude ionospheric storm. The data are measurements of electron density taken along the circular polar orbit of Ariel 4 at 550 km during the geomagnetically disturbed period June 17--18, 1972. We infer that collisional momentum transfer from the disturbed neutral thermosphere to the ionosphere was the dominant midday process generating the positive F layer storm phase in the summer hemisphere. In the winter hemisphere the positive storm phase drifted poleward in apparent response to magnetospheric E x B drifts. A summer F layer positive phase developed at the sudden commencement and again during the geomagnetic main phase; a winter F layer positive phase developed only during the geomagnetic main phase. The observed seasonal differences in both the onsets and the magnitudes of the positive phases are attributed to the interhemispheric asymmetry in thermospheric dynamics

Total electron content responses to HILDCAAs and geomagnetic storms over South America

Science.gov (United States)

Mara de Siqueira Negreti, Patricia; Rodrigues de Paula, Eurico; Nicoli Candido, Claudia Maria

2017-12-01

Total electron content (TEC) is extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. This subject is of greatest importance for space weather applications. Under disturbed conditions the two main sources of electric fields, which are responsible for changes in the plasma drifts and for current perturbations, are the short-lived prompt penetration electric fields (PPEFs) and the longer-lasting ionospheric disturbance dynamo (DD) electric fields. Both mechanisms modulate the TEC around the globe and the equatorial ionization anomaly (EIA) at low latitudes. In this work we computed vertical absolute TEC over the low latitude of South America. The analysis was performed considering HILDCAA (high-intensity, long-duration, continuous auroral electrojet (AE) activity) events and geomagnetic storms. The characteristics of storm-time TEC and HILDCAA-associated TEC will be presented and discussed. For both case studies presented in this work (March and August 2013) the HILDCAA event follows a geomagnetic storm, and then a global scenario of geomagnetic disturbances will be discussed. Solar wind parameters, geomagnetic indices, O / N2 ratios retrieved by GUVI instrument onboard the TIMED satellite and TEC observations will be analyzed and discussed. Data from the RBMC/IBGE (Brazil) and IGS GNSS networks were used to calculate TEC over South America. We show that a HILDCAA event may generate larger TEC differences compared to the TEC observed during the main phase of the precedent geomagnetic storm; thus, a HILDCAA event may be more effective for ionospheric response in comparison to moderate geomagnetic storms, considering the seasonal conditions. During the August HILDCAA event, TEC enhancements from ˜ 25 to 80 % (compared to quiet time) were observed. These enhancements are much higher than the quiet-time variability observed in the ionosphere. We show that ionosphere is quite sensitive to solar wind forcing and

Morphology in the total electron content under geomagnetic disturbed conditions: results from global ionosphere maps

Directory of Open Access Journals (Sweden)

Zhao Biqiang

2007-07-01

Full Text Available Using 8-year global ionosphere maps (GIMs of TEC products from the Jet Propulsion Laboratory (JPL, we make a statistical study on the morphology of the global ionospheric behaviors with respect to the geomagnetic disturbances. Results show that the behaviors of TEC during geomagnetic storm present clear seasonal and local time variations under geomagnetic control in a similar way as those of NmF2 (Field and Rishbeth, 1997. A negative phase of TEC occurs with high probability in the summer hemisphere and most prominent near the geomagnetic poles, while a positive phase is obvious in the winter hemisphere and in the far pole region. A negative storm effect toward lower latitudes tends to occur from post-midnight to the morning sector and recedes to high latitude in the afternoon. A positive storm effect is separated by geomagnetic latitudes and magnetic local time. Furthermore, ionospheric responses at different local time sectors with respect to the storm commencement shows very different developing processes corresponding to the evolution of the geomagnetic storm. A daytime positive storm effect is shown to be more prominent in the American region than those in the Asian and European regions, which may suggest a longitudinal effect of the ionospheric storm.

Morphology in the total electron content under geomagnetic disturbed conditions: results from global ionosphere maps

Directory of Open Access Journals (Sweden)

Z. Biqiang

2007-07-01

Full Text Available Using 8-year global ionosphere maps (GIMs of TEC products from the Jet Propulsion Laboratory (JPL, we make a statistical study on the morphology of the global ionospheric behaviors with respect to the geomagnetic disturbances. Results show that the behaviors of TEC during geomagnetic storm present clear seasonal and local time variations under geomagnetic control in a similar way as those of NmF2 (Field and Rishbeth, 1997. A negative phase of TEC occurs with high probability in the summer hemisphere and most prominent near the geomagnetic poles, while a positive phase is obvious in the winter hemisphere and in the far pole region. A negative storm effect toward lower latitudes tends to occur from post-midnight to the morning sector and recedes to high latitude in the afternoon. A positive storm effect is separated by geomagnetic latitudes and magnetic local time. Furthermore, ionospheric responses at different local time sectors with respect to the storm commencement shows very different developing processes corresponding to the evolution of the geomagnetic storm. A daytime positive storm effect is shown to be more prominent in the American region than those in the Asian and European regions, which may suggest a longitudinal effect of the ionospheric storm.

THE SOUTHERN ARGENTINA AGILE METEOR RADAR ORBITAL SYSTEM (SAAMER-OS): AN INITIAL SPORADIC METEOROID ORBITAL SURVEY IN THE SOUTHERN SKY

Energy Technology Data Exchange (ETDEWEB)

Janches, D.; Swarnalingam, N. [Space Weather Laboratory, Mail Code 674, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Close, S. [Space Environment and Satellite Systems Laboratory, Department of Aeronautics and Astronautics, Stanford University, Palo Alto, CA (United States); Hormaechea, J. L. [Estacion Astronomica Rio Grande, Rio Grande, Tierra del Fuego (Argentina); Murphy, A.; O’Connor, D.; Vandepeer, B.; Fuller, B. [Genesis Software Pty Ltd, Adelaide (Australia); Fritts, D. C. [GATS Inc., Boulder CO (United States); Brunini, C., E-mail: diego.janches@nasa.gov, E-mail: nimalan.swarnalingam@nasa.gov, E-mail: sigridc@stanford.edu, E-mail: jlhormaechea@untdf.edu.ar, E-mail: amurphy@gsoft.com.au, E-mail: doconnor@gsoft.com.au, E-mail: bvandepe@gsoft.com.au, E-mail: bfuller@gsoft.com.au, E-mail: dave@gats-inc.com, E-mail: claudiobrunini@yahoo.com [Departmento de Astronomia y Geofísica, Universidad Nacional de La Plata, La Plata (Argentina)

2015-08-10

We present an initial survey in the southern sky of the sporadic meteoroid orbital environment obtained with the Southern Argentina Agile MEteor Radar (SAAMER) Orbital System (OS), in which over three-quarters of a million orbits of dust particles were determined from 2012 January through 2015 April. SAAMER-OS is located at the southernmost tip of Argentina and is currently the only operational radar with orbit determination capability providing continuous observations of the southern hemisphere. Distributions of the observed meteoroid speed, radiant, and heliocentric orbital parameters are presented, as well as those corrected by the observational biases associated with the SAAMER-OS operating parameters. The results are compared with those reported by three previous surveys performed with the Harvard Radio Meteor Project, the Advanced Meteor Orbit Radar, and the Canadian Meteor Orbit Radar, and they are in agreement with these previous studies. Weighted distributions for meteoroids above the thresholds for meteor trail electron line density, meteoroid mass, and meteoroid kinetic energy are also considered. Finally, the minimum line density and kinetic energy weighting factors are found to be very suitable for meteroid applications. The outcomes of this work show that, given SAAMER’s location, the system is ideal for providing crucial data to continuously study the South Toroidal and South Apex sporadic meteoroid apparent sources.

Geomagnetic activity and the North Atlantic Oscillation

Czech Academy of Sciences Publication Activity Database

Bucha, Václav

2014-01-01

Roč. 58, č. 3 (2014), s. 461-472 ISSN 0039-3169 Institutional support: RVO:67985530 Keywords : geomagnetic activity * solar wind * polar vortex intensification * downward winds Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.806, year: 2014

Spatial distribution of errors associated with multistatic meteor radar

Science.gov (United States)

Hocking, W. K.

2018-06-01

With the recent increase in numbers of small and versatile low-power meteor radars, the opportunity exists to benefit from simultaneous application of multiple systems spaced by only a few hundred km and less. Transmissions from one site can be recorded at adjacent receiving sites using various degrees of forward scatter, potentially allowing atmospheric conditions in the mesopause regions between stations to be diagnosed. This can allow a better spatial overview of the atmospheric conditions at any time. Such studies have been carried out using a small version of such so-called multistatic meteor radars, e.g. Chau et al. (Radio Sci 52:811-828, 2017, https://doi.org/10.1002/2016rs006225 ). These authors were able to also make measurements of vorticity and divergence. However, measurement uncertainties arise which need to be considered in any application of such techniques. Some errors are so severe that they prohibit useful application of the technique in certain locations, particularly for zones at the midpoints of the radars sites. In this paper, software is developed to allow these errors to be determined, and examples of typical errors involved are discussed. The software should be of value to others who wish to optimize their own MMR systems.

Time variations in geomagnetic intensity

Science.gov (United States)

Valet, Jean-Pierre

2003-03-01

After many years spent by paleomagnetists studying the directional behavior of the Earth's magnetic field at all possible timescales, detailed measurements of field intensity are now needed to document the variations of the entire vector and to analyze the time evolution of the field components. A significant step has been achieved by combining intensity records derived from archeological materials and from lava flows in order to extract the global field changes over the past 12 kyr. A second significant step was due to the emergence of coherent records of relative paleointensity using the remanent magnetization of sediments to retrace the evolution of the dipole field. A third step was the juxtaposition of these signals with those derived from cosmogenic isotopes. Contemporaneous with the acquisition of records, new techniques have been developed to constrain the geomagnetic origin of the signals. Much activity has also been devoted to improving the quality of determinations of absolute paleointensity from volcanic rocks with new materials, proper selection of samples, and investigations of complex changes in magnetization during laboratory experiments. Altogether these developments brought us from a situation where the field changes were restricted to the past 40 kyr to the emergence of a coherent picture of the changes in the geomagnetic dipole moment for at least the past 1 Myr. On longer timescales the field variability and its average behavior is relatively well documented for the past 400 Myr. Section 3 gives a summary of most methods and techniques that are presently used to track the field intensity changes in the past. In each case, current limits and potential promises are discussed. The section 4 describes the field variations measured so far over various timescales covered by the archeomagnetic and the paleomagnetic records. Preference has always been given to composite records and databases in order to extract and discuss major and global geomagnetic

IMF sector behavior estimated from geomagnetic data at South Pole

International Nuclear Information System (INIS)

Matsushita, S.; Xu, W.h.

1981-01-01

IMF sector behavior which has previously been estimated from the geomagnetic data at Godhavn is confirmed by study of the data at South Pole for 1959--1970 with the same estimation technique, taking the difference between northern and southern hemispheres into consideration. A method to improve (about 18%) the agreement between assigned and actual sector structures by study of the data at the two stations is suggested. Geomagnetic disturbance effects on sector estimation are discussed, and reversed sector effects in winter are given special emphasis

A study of geomagnetic field variations along the 80° S geomagnetic parallel

Directory of Open Access Journals (Sweden)

S. Lepidi

2017-01-01

Full Text Available The availability of measurements of the geomagnetic field variations in Antarctica at three sites along the 80° S geomagnetic parallel, separated by approximately 1 h in magnetic local time, allows us to study the longitudinal dependence of the observed variations. In particular, using 1 min data from Mario Zucchelli Station, Scott Base and Talos Dome, a temporary installation during 2007–2008 Antarctic campaign, we investigated the diurnal variation and the low-frequency fluctuations (approximately in the Pc5 range, ∼ 1–7 mHz. We found that the daily variation is clearly ordered by local time, suggesting a predominant effect of the polar extension of midlatitude ionospheric currents. On the other hand, the pulsation power is dependent on magnetic local time maximizing around magnetic local noon, when the stations are closer to the polar cusp, while the highest coherence between pairs of stations is observed in the magnetic local nighttime sector. The wave propagation direction observed during selected events, one around local magnetic noon and the other around local magnetic midnight, is consistent with a solar-wind-driven source in the daytime and with substorm-associated processes in the nighttime.

Feasibility of artificial geomagnetic field generation by a superconducting ring network

International Nuclear Information System (INIS)

Motojima, Osamu; Yanagi, Nagato

2008-05-01

The geomagnetic field shields the Earth from a large proportion of incoming radiation, and has thus played a key role in sustaining life on Earth. Paleomagnetic measurements have shown that the geomagnetic field undergoes many reversals of polarity. Continuous observations of the field intensity have revealed a weakening of approximately 10% over the last 150 years. If we assume that this trend indicates the onset of polarity reversal, the geomagnetic field, particularly the dipole component, may weaken sufficiently over the next thousand years to expose the atmosphere and nearby space to significantly increased levels of cosmic and solar radiation. This may have a serious impact on vital infrastructure such as satellites, air traffic, and electricity networks, as well as on global climate changes, indicating that measures should better be taken in an attempt to support the limited protection provided by the remaining higher-order multipole fields and atmosphere. Here we show that a series of planet-encircling superconducting rings can provide an artificial geomagnetic field equivalent to 10% of the present-day field necessary to prevent adverse effects. A feasible system consists of 12 latitudinal high-temperature superconducting rings, each carrying 6.4 MA current with a modest 1 GW of power requirement. (author)

Current sheet particle acceleration - theory and observations for the geomagnetic tail

International Nuclear Information System (INIS)

Speiser, T.W.

1984-01-01

It has been found that the current sheet in the geomagnetic tail is a source of plasma and energetic particles for the magnetospheric ring current and radiation belts. It is also a seat for instabilities and magnetospheric substorms. Theoretical studies related to the geomagnetic tail are discussed, taking into account Dungey's (1953) original ideas concerning neutral point acceleration, and studies of particle motion in current sheets conducted by many authors. A description of observations concerning the geomagnetic tail is also provided, taking into account plasma sheet populations, and the plasma sheet boundary layer. Some remaining problems are partly related to the location and the behavior of the distant source, the nature of the relative (time-dependent) ionospheric versus solar wind contributions, and the role of the solar wind in the initiation of distant or near-earth neutral lines. 56 references

Theory of geomagnetic effects of cosmic rays: its past and presence

Energy Technology Data Exchange (ETDEWEB)

Gall, R [Universidad Nacional Autonoma de Mexico, Mexico City. Inst. de Geofisica

1981-03-01

The interest expressed by Lemaitre and Vallarta in the nature of universal corpuscular radiation, remnant of the exploded primogenitive atom, culminated in 1932, in the development of their theory of the geomagnetic effects of cosmic rays, a tool since its publication, basic to cosmic radiation research and to the advancement of cosmic ray astronomy. Between 1940 and 1960 challenging experimental data from proliferating cosmic radiation stations and of direct detection techniques provided geomagnetic field models for greater theoretical precision. The discoveries since the advent of the space age of the Earth's cavity and geomagnetic tail, and of the nonrelativistic solar cosmic rays have resulted in a new branch of the theory dealing with magnetosphere effects in the propagation of low energy cosmic radiations. The theory's importance and application to cosmic bodies other than the Earth is discussed.

Mechanism of the relations between the changes of the geomagnetic field, solar corpuscular radiation, atmospheric circulation, and climate

International Nuclear Information System (INIS)

Bucha, Vaclav

1980-01-01

The correlations between geomagnetic, climatic, and meteorological phenomena were investigated with the object of demonstrating the function of the geomagnetic pole and changes of its position in controlling the climate and weather. A tentative model has been proposed to enable one to understand the causes of the generation of glacial and interglacial periods, as well as the causes which effect changes of climate (Bucha, 1976a). The analyses of various types of geomagnetic and atmospheric manifestations have disclosed certain associations. The coincidence in the occurrence of increased spectral densities with regard to geomagnetic activity and the variations of atmospheric pressure over the geomagnetic pole shows the relation between their periodicities. The results imply that the changes in the intensity of corpuscular radiation, indicated by geomagnetic activity, affect the temperature and pressure patterns over the geomagnetic pole and polar region significantly, so that a pronounced modification of the general circulation may take place, as shown schematically (Bucha, 1976b). As a result of investigating the relations between the variations of geomagnetic activity and meteorological factors a mechanism of solar-terrestrial relationships and a model of the changes of atmospheric circulation in the Northern Hemisphere are proposed; this provides a probable explanation of the causes of the fluctuation of the climate, of dry and cold periods and of differing vegetation conditions in various years in dependence on the intensity of geomagnetic activity (Bucha, 1976b, 1977a). (author)

Coronal mass ejections, interplanetary shocks in relation with forbush decreases associated with intense geomagnetic storms

International Nuclear Information System (INIS)

Verma, P L; Patel, Nand Kumar; Prajapati, Mateswari

2014-01-01

Coronal mass ejections (CMEs} are the most energetic solar events in which large amount of solar plasma materials are ejected from the sun into heliosphere, causing major disturbances in solar wind plasma, Interplanetary shocks, Forbush decrease(Fds) in cosmic ray intensity and geomagnetic storms. We have studied Forbush decreases associated with intense geomagnetic storms observed at Oulu super neutron monitor, during the period of May 1998-Dec 2006 with coronal mass ejections (CMEs), X-ray solar flares and interplanetary shocks. We have found that all the (100%) Forbush decreases associated with intense geomagnetic storms are associated with halo and partial halo coronal mass ejections (CMEs). The association rate between halo and partial halo coronal mass ejections are found 96.00%and 04.00% respectively. Most of the Forbush decreases associated with intense geomagnetic storms (96.29%) are associated with X-ray solar flares of different categories . The association rates for X-Class, M-Class, and C- Class X -ray solar flares are found 34.62%, 50.00% and 15.38% respectively .Further we have concluded that majority of the Forbush decrease associated with intense geomagnetic storms are related to interplanetary shocks (92.30 %) and the related shocks are forward shocks. We have found positive co-relation with co-relation co-efficient .7025 between magnitudes of Forbush decreases associated with intense geomagnetic storms and speed of associated coronal mass ejections. Positive co-relation with co-relation co-efficient 0.48 has also been found between magnitudes of intense geomagnetic storms and speed of associated coronal mass ejections.

Proceedings of the XIIIth IAGA Workshop on Geomagnetic Observatory Instruments, Data Acquisition, and Processing

Science.gov (United States)

Love, Jeffrey J.

2009-01-01

The thirteenth biennial International Association of Geomagnetism and Aeronomy (IAGA) Workshop on Geomagnetic Observatory Instruments, Data Acquisition and Processing was held in the United States for the first time on June 9-18, 2008. Hosted by the U.S. Geological Survey's (USGS) Geomagnetism Program, the workshop's measurement session was held at the Boulder Observatory and the scientific session was held on the campus of the Colorado School of Mines in Golden, Colorado. More than 100 participants came from 36 countries and 6 continents. Preparation for the workshop began when the USGS Geomagnetism Program agreed, at the close of the twelfth workshop in Belsk Poland in 2006, to host the next workshop. Working under the leadership of Alan Berarducci, who served as the chairman of the local organizing committee, and Tim White, who served as co-chairman, preparations began in 2007. The Boulder Observatory was extensively renovated and additional observation piers were installed. Meeting space on the Colorado School of Mines campus was arranged, and considerable planning was devoted to managing the many large and small issues that accompany an international meeting. Without the devoted efforts of both Alan and Tim, other Geomagnetism Program staff, and our partners at the Colorado School of Mines, the workshop simply would not have occurred. We express our thanks to Jill McCarthy, the USGS Central Region Geologic Hazards Team Chief Scientist; Carol A. Finn, the Group Leader of the USGS Geomagnetism Program; the USGS International Office; and Melody Francisco of the Office of Special Programs and Continuing Education of the Colorado School of Mines. We also thank the student employees that the Geomagnetism Program has had over the years and leading up to the time of the workshop. For preparation of the proceedings, thanks go to Eddie and Tim. And, finally, we thank our sponsors, the USGS, IAGA, and the Colorado School of Mines.

Study of the mid-latitude ionospheric response to geomagnetic storms in the European region

Science.gov (United States)

Berényi, Kitti Alexandra; Barta, Veronika; Kis, Arpad

2016-07-01

Geomagnetic storms affect the ionospheric regions of the terrestrial upper atmosphere through different physical and atmospheric processes. The phenomena that can be regarded as a result of these processes, generally is named as "ionospheric storm". The processes depend on altitude, segment of the day, the geomagnetic latitude and longitude, strength of solar activity and the type of the geomagnetic storm. We examine the data of ground-based radio wave ionosphere sounding measurements of European ionospheric stations (mainly the data of Nagycenk Geophysical Observatory) in order to determine how and to what extent a geomagnetic disturbance of a certain strength affects the mid-latitude ionospheric regions in winter and in summer. For our analysis we used disturbed time periods between November 2012 and June 2015. Our results show significant changing of the ionospheric F2 layer parameters on strongly disturbed days compared to quiet ones. We show that the critical frequencies (foF2) increase compared to their quiet day value when the ionospheric storm was positive. On the other hand, the critical frequencies become lower, when the storm was negative. In our analysis we determined the magnitude of these changes on the chosen days. For a more complete analysis we compare also the evolution of the F2 layer parameters of the European ionosonde stations on a North-South geographic longitude during a full storm duration. The results present the evolution of an ionospheric storm over a geographic meridian. Furthermore, we compared the two type of geomagnetic storms, namely the CME caused geomagnetic storm - the so-called Sudden impulse (Si) storms- and the HSS (High Speed Solar Wind Streams) caused geomagnetic storms -the so-called Gradual storms (Gs)- impact on the ionospheric F2-layer (foF2 parameter). The results show a significant difference between the effect of Si and of the Gs storms on the ionospheric F2-layer.

Characteristics of ejecta and alluvial deposits at Meteor Crater, Arizona and Odessa Craters, Texas: Results from ground penetrating radar

Science.gov (United States)

Grant, J. A.; Schultz, P. H.

1991-01-01

Previous ground penetrating radar (GRP) studies around 50,000 year old Meteor Crater revealed the potential for rapid, inexpensive, and non-destructive sub-surface investigations for deep reflectors (generally greater than 10 m). New GRP results are summarized focusing the shallow sub-surfaces (1-2 m) around Meteor Crater and the main crater at Odessa. The following subject areas are covered: (1) the thickness, distribution, and nature of the contact between surrounding alluvial deposits and distal ejecta; and (2) stratigraphic relationships between both the ejecta and alluvium derived from both pre and post crater drainages. These results support previous conclusions indicating limited vertical lowering (less than 1 m) of the distal ejecta at Meteor Crater and allow initial assessment of the gradational state if the Odessa craters.

Variations in the geomagnetic dipole moment during the Holocene and the past 50 kyr

Science.gov (United States)

Knudsen, Mads Faurschou; Riisager, Peter; Donadini, Fabio; Snowball, Ian; Muscheler, Raimund; Korhonen, Kimmo; Pesonen, Lauri J.

2008-07-01

All absolute paleointensity data published in peer-reviewed journals were recently compiled in the GEOMAGIA50 database. Based on the information in GEOMAGIA50, we reconstruct variations in the geomagnetic dipole moment over the past 50 kyr, with a focus on the Holocene period. A running-window approach is used to determine the axial dipole moment that provides the optimal least-squares fit to the paleointensity data, whereas associated error estimates are constrained using a bootstrap procedure. We subsequently compare the reconstruction from this study with previous reconstructions of the geomagnetic dipole moment, including those based on cosmogenic radionuclides ( 10Be and 14C). This comparison generally lends support to the axial dipole moments obtained in this study. Our reconstruction shows that the evolution of the dipole moment was highly dynamic, and the recently observed rates of change (5% per century) do not appear unique. We observe no apparent link between the occurrence of archeomagnetic jerks and changes in the geomagnetic dipole moment, suggesting that archeomagnetic jerks most likely represent drastic changes in the orientation of the geomagnetic dipole axis or periods characterized by large secular variation of the non-dipole field. This study also shows that the Holocene geomagnetic dipole moment was high compared to that of the preceding ˜ 40 kyr, and that ˜ 4 · 10 22 Am 2 appears to represent a critical threshold below which geomagnetic excursions and reversals occur.

The Distribution of Geomagnetic Field Components on the Southern Part of the Korean Peninsula for Epoch 2010.0

Directory of Open Access Journals (Sweden)

Mutaek Lim

2011-05-01

Full Text Available NGII(National Geography Information Institute of Korea consigned KIGAM(Korea Institute of Geoscience & Mineral Resources to do absolute geomagnetic measurements on 32 geomagnetic repeat stations evenly distributed on the southern part of Korean Peninsula in the year 2010 and to produce geomagnetic field components' distribution maps for the year 2010.0. The result of the processing of the measured data, i. e., the geomagnetic field components' distribution, shows a near similarity with that calculated from IGRF-11 although the latter was processed without any real geomagnetic data measured on the Korean Peninsula as an input. This implies that we installed the repeat stations on sites with good geomagnetic conditions and that our result in accordance with the IGRF represents well the regional distribution trend, i. e., it is dominated by relatively long wavelength components.

Local time and cutoff rigidity dependences of storm time increase associated with geomagnetic storms

International Nuclear Information System (INIS)

Kudo, S.; Wada, M.; Tanskanen, P.; Kodama, M.

1987-01-01

The cosmic ray increases due to considerable depressions of cosmic ray cutoff rigidity during large geomagnetic storms are investigated. Data from a worldwide network of cosmic ray neutron monitors are analyzed for 17 geomagnetic storms which occurred in the quiet phase of the solar activity cycle during 1966-1978. As expected from the longitudinal asymmetry of the low-altitude geomagnetic field during large geomagnetic storms, a significant local time dependence of the increment in the cosmic ray during large geomagnetic storms, a significant local time dependence of the increment in the cosmic ray intensity is obtained. It is shown that the maximum phases of the local time dependence occur at around 1800 LT and that the amplitudes of the local time dependence are consistent with presently available theoretical estimates. The dependence of the increment on the cutoff rigidity is obtained for both the local time dependent part and the local time independent part of the storm time increase. The local time independent part, excluding the randomizing local time dependent part, shows a clear-cut dependence on cutoff rigidity which is consistent with theoretical estimates

Paleomagnetic evidence for the persistence or recurrence of the South Atlantic geomagnetic Anomaly

Science.gov (United States)

Shah, Jay; Koppers, Anthony A. P.; Leitner, Marko; Leonhardt, Roman; Muxworthy, Adrian R.; Heunemann, Christoph; Bachtadse, Valerian; Ashley, Jack A. D.; Matzka, Jürgen

2017-04-01

The South Atlantic geomagnetic Anomaly (SAA) is known as a region of the geomagnetic field that is approximately 25 μT in intensity, compared to an expected value of ˜43 μT. Geomagnetic field models do not find evidence for the SAA being a persistent feature of the geomagnetic field, however these models are constructed from paleomagnetic data that is sparse in the southern hemisphere. We present a full-vector paleomagnetic study of 40Ar/39Ar dated Late Pleistocene lavas from Tristan da Cunha in the South Atlantic Ocean (Shah et al., 2016; EPSL). Paleointensity estimations using the Thellier method of eight lava flows yield an average paleointensity of the Tristan da Cunha lavas as 18 ± 6 μT and an average virtual axial dipole moment (VADM) of 3.1 ± 1.2 × 1022 Am2. Comparing the VADM of the lava flows against the PADM2M, PINT and SINT-800 databases indicates that the lava flows represent four distinct periods of anomalously weak intensity in the South Atlantic between 43 and 90 ka ago, constrained by newly obtained 40Ar/39Ar ages. This anomalously weak intensity in the Late Pleistocene is similar to the present-day SAA and SAA-like anomalous behavior found in the recent archeomagnetic study by Tarduno et al. (2015; Nat. Commun.). Our dataset provides evidence for the persistence or recurrence of geomagnetic main field anomalies in the South Atlantic, and potentially indicates such anomalies are the geomagnetic field manifestation of the long-existing core-mantle boundary heterogeneity seismically identified as the African Large Low Velocity Shear Province (LLSVP).

Radiative heat exchange of a meteor body in the approximation of radiant heat conduction

International Nuclear Information System (INIS)

Pilyugin, N.N.; Chernova, T.A.

1986-01-01

The problem of the thermal and dynamic destruction of large meteor bodies moving in planetary atmospheres is fundamental for the clarification of optical observations and anomalous phenomena in the atmosphere, the determination of the physicochemical properties of meteoroids, and the explanation of the fall of remnants of large meteorites. Therefore, it is important to calculate the coefficient of radiant heat exchange (which is the determining factor under these conditions) for large meteor bodies as they move with hypersonic velocities in an atmosphere. The solution of this problem enables one to find the ablation of a meteorite during its aerodynamic heating and to determine the initial conditions for the solution of problems of the breakup of large bodies and their subsequent motion and ablation. Hypersonic flow of an inviscid gas stream over an axisymmetric blunt body is analyzed with allowance for radiative transfer in a thick-thin approximation. The gas-dynamic problem of the flow of an optically thick gas over a large body is solved by the method of asymptotic joined expansions, using a hypersonic approximation and local self-similarity. An equation is obtained for the coefficient of radiant heat exchange and the peculiarities of such heat exchange for meteor bodies of large size are noted

Surface electric fields for North America during historical geomagnetic storms

Science.gov (United States)

Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.

2013-01-01

To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

Low-altitude trapped protons at the geomagnetic equator

Science.gov (United States)

Guzik, T. G.; Miah, M. A.; Mitchell, J. M.; Wefel, J. P.

1989-01-01

Geomagnetically trapped protons in the 0.6- to 9-MeV energy range were measured at latitudes near the geomagnetic equator by the Phoenix 1 experiment on board the S81-1 mission from May to November 1982. The protons show a distribution in latitude along the line of minimum magnetic field strength with a full width at half maximum of about 10 deg but with no appreciable longitudinal variation. Between 170 and 290 Km the peak proton flux shows a fifth-power altitude dependence, in contrast to previous measurements at higher altitudes, possibly demonstrating source attenuation. The efficiency of the telescope is calculated as a function of particle pitch angle and used to investigate the time dependence (1969-1982) of the intensity.

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....

Meteor Crater (Barringer Meteorite Crater), Arizona: Summary of Impact Conditions

Science.gov (United States)

Roddy, D. J.; Shoemaker, E. M.

1995-09-01

Meteor Crater in northern Arizona represents the most abundant type of impact feature in our Solar System, i.e., the simple bowl-shaped crater. Excellent exposures and preservation of this large crater and its ejecta blanket have made it a critical data set in both terrestrial and planetary cratering research. Recognition of the value of the crater was initiated in the early 1900's by Daniel Moreau Barringer, whose 27 years of exploration championed its impact origin [1]. In 1960, Shoemaker presented information that conclusively demonstrated that Meteor Crater was formed by hypervelocity impact [2]. This led the U.S. Geological Survey to use the crater extensively in the 1960-70's as a prime training site for the Apollo astronauts. Today, Meteor Crater continues to serve as an important research site for the international science community, as well as an educational site for over 300,000 visitors per year. Since the late 1950's, studies of this crater have presented an increasingly clearer view of this impact and its effects and have provided an improved view of impact cratering in general. To expand on this data set, we are preparing an upgraded summary on the Meteor Crater event following the format in [3], including information and interpretations on: 1) Inferred origin and age of the impacting body, 2) Inferred ablation and deceleration history in Earth's atmosphere, 3) Estimated speed, trajectory, angle of impact, and bow shock conditions, 4) Estimated coherence, density, size, and mass of impacting body, 5) Composition of impacting body (Canyon Diablo meteorite), 6) Estimated kinetic energy coupled to target rocks and atmosphere, 7) Terrain conditions at time of impact and age of impact, 8) Estimated impact dynamics, such as pressures in air, meteorite, and rocks, 9) Inferred and estimated material partitioning into vapor, melt, and fragments, 10) Crater and near-field ejecta parameters, 11) Rock unit distributions in ejecta blanket, 12) Estimated far

Special issue “International Geomagnetic Reference Field—the twelfth generation”

DEFF Research Database (Denmark)

Thébault, E.; Finlay, C. C.; Toh, H.

2015-01-01

This special issue of Earth, Planets and Space, synthesizes the efforts made during the construction of the twelfth generation of the International Geomagnetic Reference Field (IGRF-12) that was released online in December 2014 (http://www.ngdc.noaa.gov/IAGA/vmod/ igrf.html). The IGRF-12 is a ser......This special issue of Earth, Planets and Space, synthesizes the efforts made during the construction of the twelfth generation of the International Geomagnetic Reference Field (IGRF-12) that was released online in December 2014 (http://www.ngdc.noaa.gov/IAGA/vmod/ igrf.html). The IGRF-12...

Westward ionospheric currents over the dip equator during geomagnetic disturbances

International Nuclear Information System (INIS)

Rastogi, R.G.

1975-01-01

During geomagnetic disturbed periods, the q type of sporadic E layer near the dip equator is shown to disappear with maximum error of five minutes during the period when the difference of the geomagnetic H field between the equatorial and non-equatorial station decreases below the night level. These periods are identified with the reversal to westward direction of the electrojet currents at the base of the E region around 100 km level irrespective of the changes in the S/subq/ current system which might be produced by the disturbance

Two-dimensional computer simulation of hypervelocity impact cratering: some preliminary results for Meteor Crater, Arizona

International Nuclear Information System (INIS)

Bryan, J.B.; Burton, D.E.; Cunningham, M.E.; Lettis, L.A. Jr.

1978-04-01

A computational approach used for subsurface explosion cratering has been extended to hypervelocity impact cratering. Meteor (Barringer) Crater, Arizona, was selected for our first computer simulation because it was the most thoroughly studied. It is also an excellent example of a simple, bowl-shaped crater and is one of the youngest terrestrial impact craters. Shoemaker estimates that the impact occurred about 20,000 to 30,000 years ago [Roddy (1977)]. Initial conditions for this calculation included a meteorite impact velocity of 15 km/s. meteorite mass of 1.57E + 08 kg, with a corresponding kinetic energy of 1.88E + 16 J (4.5 megatons). A two-dimensional Eulerian finite difference code called SOIL was used for this simulation of a cylindrical iron projectile impacting at normal incidence into a limestone target. For this initial calculation a Tillotson equation-of-state description for iron and limestone was used with no shear strength. A color movie based on this calculation was produced using computer-generated graphics. Results obtained for this preliminary calculation of the formation of Meteor Crater, Arizona, are in good agreement with Meteor Crater Measurements

Risk Analysis and Forecast Service for Geomagnetically Induced Currents in Europe

Science.gov (United States)

Wik, Magnus; Pirjola, Risto; Viljanen, Ari; Lundstedt, Henrik

Geomagnetically induced currents (GIC), occurring during magnetic storms, pose a widespread natural disaster risk to the reliable operation of electric power transmission grids, oil and gas pipelines, telecommunication cables and railway systems. The solar magnetic activity is the cause of GIC. Solar coronal holes can cause recurrent inter-vals of raised geomagnetic activity, and coronal mass ejections (CME) at the Sun, sometimes producing very high speed plasma clouds with enhanced magnetic fields and particle densities, can cause the strongest geomagnetic storms. When the solar wind interacts with the geomag-netic field, energy is transferred to the magnetosphere, driving strong currents in the ionosphere. When these currents change in time a geoelectric field is induced at the surface of the Earth and in the ground. Finally, this field drives GIC in the ground and in any technological conductor systems. The worst consequence of a severe magnetic storm within a power grid is a complete blackout, as happened in the province of Québec, Canada, in March 1989, and in the city of Malmü, Sweden, in October 2003. Gas and oil pipelines are not regarded as vulnerable to the immediate impact of GIC, but the corrosion rate of buried steel pipes can increase due to GIC, which may thus shorten the lifetime of a pipe. European Risk from Geomagnetically Induced Currents (EURISGIC) is an EU project, that, if approved, will produce the first European-wide real-time prototype forecast service of GIC in power systems, based on in-situ solar wind observations and comprehensive simulations of the Earth's magnetosphere. This project focuses on high-voltage power transmission networks, which are probably currently the most susceptible to GIC effects. Geomagnetic storms cover large geographical regions, at times the whole globe. Consequently, power networks are rightly described as being European critical infrastructures whose disruption or destruction could have a significant impact

Impacts of Extreme Space Weather Events on Power Grid Infrastructure: Physics-Based Modelling of Geomagnetically-Induced Currents (GICs) During Carrington-Class Geomagnetic Storms

Science.gov (United States)

Henderson, M. G.; Bent, R.; Chen, Y.; Delzanno, G. L.; Jeffery, C. A.; Jordanova, V. K.; Morley, S.; Rivera, M. K.; Toth, G.; Welling, D. T.; Woodroffe, J. R.; Engel, M.

2017-12-01

Large geomagnetic storms can have devastating effects on power grids. The largest geomagnetic storm ever recorded - called the Carrington Event - occurred in 1859 and produced Geomagnetically Induced Currents (GICs) strong enough to set fires in telegraph offices. It has been estimated that if such a storm occurred today, it would have devastating, long-lasting effects on the North American power transmission infrastructure. Acutely aware of this imminent threat, the North American Electric Reliability Corporation (NERC) was recently instructed to establish requirements for transmission system performance during geomagnetic disturbance (GMD) events and, although the benchmarks adopted were based on the best available data at the time, they suffer from a severely limited physical understanding of the behavior of GMDs and the resulting GICs for strong events. To rectify these deficiencies, we are developing a first-of-its-kind data-informed modelling capability that will provide transformational understanding of the underlying physical mechanisms responsible for the most harmful intense localized GMDs and their impacts on real power transmission networks. This work is being conducted in two separate modes of operation: (1) using historical, well-observed large storm intervals for which robust data-assimilation can be performed, and (2) extending the modelling into a predictive realm in order to assess impacts of poorly and/or never-before observed Carrington-class events. Results of this work are expected to include a potential replacement for the current NERC benchmarking methodology and the development of mitigation strategies in real power grid networks. We report on progress to date and show some preliminary results of modeling large (but not yet extreme) events.

Impact of the Lower Atmosphere on the Ionosphere Response to a Geomagnetic Superstorm

Science.gov (United States)

Pedatella, N. M.

2016-12-01

Numerical simulations in the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) are performed to elucidate the impacts of lower atmosphere forcing on the ionosphere response to a geomagnetic superstorm. In particular, how the ionosphere variability due to the October 2003 Halloween storm would be different if it occurred in January coincident with a major sudden stratosphere warming (SSW) event is investigated. The TIE-GCM simulations reveal that the E x B vertical drift velocity and total electron content (TEC) respond differently to the geomagnetic disturbance when the lower atmosphere forcing is representative of SSW conditions compared to climatological lower atmosphere forcing conditions. Notably, the storm time variations in the E x B vertical drift velocity differ when the effects of the SSW are considered, and this is in part due to effects of the SSW on the equatorial ionosphere being potentially misinterpreted as being of geomagnetic origin. Differences in the TEC response to the geomagnetic storm can be up to 100% ( 30 TECU) of the storm induced TEC change, and the temporal variability of the TEC during the storm recovery phase is considerably different if SSW effects are considered. The results demonstrate that even during periods of extreme geomagnetic forcing it is important to consider the effects of lower atmosphere forcing on the ionosphere variability.

Visual evidence of the Sterno-Etrussia geomagnetic excursion (~2700 BP)?

Science.gov (United States)

Raspopov, O. M.; Dergachev, V. A.; Goos'kova, E. G.; Morner, N.-A.

2003-04-01

In the Bible's Old Testament Book of Ezekiel there is a description of the Ezekiel's vision of "a great cloud with brightness round about it" to the north of the observation site. The event described in the Bible occurred in 593 BC, i.e., approximately 2600 years ago. Ezekiel was at that time approximately 100 km south of Babylon (latitude ~ 32 N, longitude ~ 45 E). Auroral specialists interpret the Ezekiel's vision as observation of coronal auroral displays at low latitudes. However, to support this hypothesis, it is necessary to understand the physical mechanism responsible for generation of these forms of auroras at low latitudes. Analysis of palaeo- and archaeomagnetic data, including our data on magnetic properties of sediments of the Barents and White Seas and the literature data, has shown that about 2700 BP, i.e., in Ezekiel's time, development of a geomagnetic "Sterno-Etrussia" excursion took place. The duration of the excursion during which the northern geomagnetic pole wandered to the Southern Hemisphere was no more than 200-300 years. Manifestations of this excursion were found in 16 regions of the Eurasian continent and adjacent seas and also in the North and South America. By plotting the path along which the northern geomagnetic pole wandered to the southern latitudes during this excursion on the basis of palaeomagnetic data, we have found that it wandered in the longitude sector plus or minus 30 degrees, and about 2700 BP the northern geomagnetic pole was at the longitude close to the Babylon longitude, where Ezekiel had his vision. Thus, at that time Babylon was at high geomagnetic latitudes where regular coronal auroral displays occur. Records of observation of the unusual brightness of the sky in the V-VI centuries BC can also be found in Greek chronicles. This indicates that the Ezekiel's vision was not the only observation of auroras at low latitudes during the period considered here. This work was supported by INTAS, Grant 97-31008 and PFBR

Atmospheric helium and geomagnetic field reversals.

Science.gov (United States)

Sheldon, W. R.; Kern, J. W.

1972-01-01

The problem of the earth's helium budget is examined in the light of recent work on the interaction of the solar wind with nonmagnetic planets. It is proposed that the dominant mode of helium (He4) loss is ion pumping by the solar wind during geomagnetic field reversals, when the earth's magnetic field is very small. The interaction of the solar wind with the earth's upper atmosphere during such a period is found to involve the formation of a bow shock. The penetration altitude of the shock-heated solar plasma is calculated to be about 700 km, and ionization rates above this level are estimated for a cascade ionization (electron avalanche) process to average 10 to the 9th power ions/sq cm/sec. The calculated ionization rates and the capacity of the solar wind to remove ionized helium (He4) from the upper atmosphere during geomagnetic dipole reversals are sufficient to yield a secular equilibrium over geologic time scales. The upward transport of helium from the lower atmosphere under these conditions is found to be adequate to sustain the proposed loss rate.

Manifestation of interplanetary medium parameters in development of a geomagnetic storm initial phase

International Nuclear Information System (INIS)

Chkhetiya, A.M.

1988-01-01

The role of solar wind plasma parameters in formation of a geomagnetic storm initial phase is refined. On the basis of statistical analysis an empirical formula relating the interplanetary medium parameters (components of interplanetary magnetic field, proton velocity and concentration) and D st -index during the geomagnetic storm initial phase is proposed

The Challenge Posed by Geomagnetic Activity to Electric Power Reliability: Evidence From England and Wales

Science.gov (United States)

Forbes, Kevin F.; St. Cyr, O. C.

2017-10-01

This paper addresses whether geomagnetic activity challenged the reliability of the electric power system during part of the declining phase of solar cycle 23. Operations by National Grid in England and Wales are examined over the period of 11 March 2003 through 31 March 2005. This paper examines the relationship between measures of geomagnetic activity and a metric of challenged electric power reliability known as the net imbalance volume (NIV). Measured in megawatt hours, NIV represents the sum of all energy deployments initiated by the system operator to balance the electric power system. The relationship between geomagnetic activity and NIV is assessed using a multivariate econometric model. The model was estimated using half-hour settlement data over the period of 11 March 2003 through 31 December 2004. The results indicate that geomagnetic activity had a demonstrable effect on NIV over the sample period. Based on the parameter estimates, out-of-sample predictions of NIV were generated for each half hour over the period of 1 January to 31 March 2005. Consistent with the existence of a causal relationship between geomagnetic activity and the electricity market imbalance, the root-mean-square error of the out-of-sample predictions of NIV is smaller; that is, the predictions are more accurate, when the statistically significant estimated effects of geomagnetic activity are included as drivers in the predictions.

Earth orientation and its excitations by atmosphere, oceans, and geomagnetic jerks

OpenAIRE

Vondrák J.; Ron C.

2015-01-01

In addition to torques exerted by the Moon, Sun, and planets, changes of the Earth orientation parameters (EOP) are known to be caused also by excitations by the atmosphere and oceans. Recently appeared studies, hinting that geomagnetic jerks (GMJ, rapid changes of geomagnetic field) might be associated with sudden changes of phase and amplitude of EOP (Holme and de Viron 2005, 2013, Gibert and Le Mouёl 2008, Malkin 2013). We (Ron et al. 2015) used addition...

A first generation numerical geomagnetic storm prediction scheme

International Nuclear Information System (INIS)

Akasofu, S.-I.; Fry, C.F.

1986-01-01

Because geomagnetic and auroral disturbances cause significant interference on many electrical systems, it is essential to develop a reliable geomagnetic and auroral storm prediction scheme. A first generation numerical prediction scheme has been developed. The scheme consists of two major computer codes which in turn consist of a large number of subroutine codes and of empirical relationships. First of all, when a solar flare occurs, six flare parameters are determined as the input data set for the first code which is devised to show the simulated propagation of solar wind disturbances in the heliosphere to a distance of 2 a.u. Thus, one can determine the relative location of the propagating disturbances with the Earth's position. The solar wind speed and the three interplanetary magnetic field (IMF) components are then computed as a function of time at the Earth's location or any other desired (space probe) locations. These quantities in turn become the input parameters for the second major code which computes first the power of the solar wind-magnetosphere dynamo as a function of time. The power thus obtained and the three IMF components can be used to compute or infer: the predicted geometry of the auroral oval; the cross-polar cap potential; the two geomagnetic indices AE and Dst; the total energy injection rate into the polar ionosphere; and the atmospheric temperature, etc. (author)

He+ dominance in the plasmasphere during geomagnetically disturbed periods: 1. Observational results

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C. R. Wilford

Full Text Available Observations made by the DMSP F10 satellite during the recovery phase from geomagnetic disturbances in June 1991 show regions of He+ dominance around 830 km altitude at 09:00 MLT. These regions are co-located with a trough in ionisation observed around 55° in the winter hemisphere. Plasma temperature and concentration observations made during the severe geomagnetic storm of 24 March 1991 are used as a case study to determine the effects of geomagnetic disturbances along the orbit of the F10 satellite. Previous explanations for He+ dominance in this trough region relate to the part of the respective flux tubes that is in darkness. Such conditions are not relevant for this study, since the whole of the respective flux tubes are sunlit. A new mechanism is proposed to explain the He+ dominance in the trough region. This mechanism is based on plasma transport and chemical reaction effects in the F-region and topside ionosphere, and on the time scales for such chemical reactions. Flux tubes previously depleted by geomagnetic storm effects refill during the recovery phase from the ionosphere as a result of pressure differences along the flux tubes. Following a geomagnetic disturbance, the He+ ion recovers quickly via the rapid photoionisation of neutral helium, in the F-region and the topside. The recovery of the O+ and H+ ions is less rapid. This is proposed as a result of the respective charge exchange reactions with neutral atomic hydrogen and oxygen. Preliminary model calculations support the proposed mechanism.Key words. Magnetospheric physics (storms and sub-storms, plasmasphere

Chemical abundances determined from meteor spetra. I. Rations of the main chemical clements

Czech Academy of Sciences Publication Activity Database

Trigo-Rodríguez, J.M.; Llorca, J.; Borovička, Jiří; Fabregat, J.

2003-01-01

Roč. 38, č. 8 (2003), s. 1283-1294 ISSN 0026-1114 Institutional research plan: CEZ:AV0Z1003909 Keywords : meteors * spectra * composition Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.992, year: 2003

Elliptical magnetic clouds and geomagnetic storms

Czech Academy of Sciences Publication Activity Database

Antoniadou, I.; Geranios, A.; Vandas, Marek; Panagopoulou, M.; Zacharopoulou, O.; Malandraki, O.

2008-01-01

Roč. 56, 3-4 (2008), s. 492-500 ISSN 0032-0633 R&D Projects: GA AV ČR 1QS300120506; GA ČR GA205/06/0875 Institutional research plan: CEZ:AV0Z10030501 Keywords : magnetic clouds * geomagnetic storms * solar wind Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.506, year: 2008

Total electron content responses to HILDCAAs and geomagnetic storms over South America

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P. M. de Siqueira Negreti

2017-12-01

Full Text Available Total electron content (TEC is extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. This subject is of greatest importance for space weather applications. Under disturbed conditions the two main sources of electric fields, which are responsible for changes in the plasma drifts and for current perturbations, are the short-lived prompt penetration electric fields (PPEFs and the longer-lasting ionospheric disturbance dynamo (DD electric fields. Both mechanisms modulate the TEC around the globe and the equatorial ionization anomaly (EIA at low latitudes. In this work we computed vertical absolute TEC over the low latitude of South America. The analysis was performed considering HILDCAA (high-intensity, long-duration, continuous auroral electrojet (AE activity events and geomagnetic storms. The characteristics of storm-time TEC and HILDCAA-associated TEC will be presented and discussed. For both case studies presented in this work (March and August 2013 the HILDCAA event follows a geomagnetic storm, and then a global scenario of geomagnetic disturbances will be discussed. Solar wind parameters, geomagnetic indices, O ∕ N2 ratios retrieved by GUVI instrument onboard the TIMED satellite and TEC observations will be analyzed and discussed. Data from the RBMC/IBGE (Brazil and IGS GNSS networks were used to calculate TEC over South America. We show that a HILDCAA event may generate larger TEC differences compared to the TEC observed during the main phase of the precedent geomagnetic storm; thus, a HILDCAA event may be more effective for ionospheric response in comparison to moderate geomagnetic storms, considering the seasonal conditions. During the August HILDCAA event, TEC enhancements from  ∼  25 to 80 % (compared to quiet time were observed. These enhancements are much higher than the quiet-time variability observed in the ionosphere. We show that ionosphere is quite sensitive to

Development of a Remote Monitoring System Using Meteor Burst Technology

International Nuclear Information System (INIS)

Ewanic, M.A.; Dunstan, M.T.; Reichhardt, D.K.

2006-01-01

Monitoring the cleanup and closure of contaminated sites requires extensive data acquisition, processing, and storage. At remote sites, the task of monitoring often becomes problematical due to the lack of site infrastructure (i.e., electrical power lines, telephone lines, etc.). MSE Technology Applications, Inc. (MSE) has designed an economical and efficient remote monitoring system that will handle large amounts of data; process the data, if necessary; and transmit this data over long distances. Design criteria MSE considered during the development of the remote monitoring system included: the ability to handle multiple, remote sampling points with independent sampling frequencies; robust (i.e., less susceptible to moisture, heat, and cold extremes); independent of infrastructure; user friendly; economical; and easy to expand system capabilities. MSE installed and tested a prototype system at the Mike Mansfield Advanced Technology Center (MMATC), Butte, Montana, in June 2005. The system MSE designed and installed consisted of a 'master' control station and two remote 'slave' stations. Data acquired at the two slave stations were transmitted to the master control station, which then transmits a complete data package to a ground station using meteor burst technology. The meteor burst technology has no need for hardwired land-lines or man-made satellites. Instead, it uses ionized particles in the Earth's atmosphere to propagate a radio signal. One major advantage of the system is that it can be configured to accept data from virtually any type of device, so long as the signal from the device can be read and recorded by a standard data-logger. In fact, MSE has designed and built an electrical resistivity monitoring system that will be powered and controlled by the meteor burst system components. As sites move through the process of remediation and eventual closure, monitoring provides data vital to the successful long term management of the site. The remote

The effect of the August 11, 1999 total solar eclipse on geomagnetic pulsations

Czech Academy of Sciences Publication Activity Database

Střeštík, Jaroslav

2001-01-01

Roč. 31, č. 1 (2001), s. 335-338 ISSN 1335-2806. [IAGA Workshop /9./. Hurbanovo, 12.06.2000-18.06.2000] R&D Projects: GA ČR GA205/99/0915 Institutional research plan: CEZ:AV0Z3012916 Keywords : solar eclipse * geomagnetic pulsations * geomagnetic observatories Subject RIV: DE - Earth Magnetism, Geodesy, Geography

Orbital Noise of the Earth Causes Intensity Fluctuation in the Geomagnetic Field

Science.gov (United States)

Liu, Han-Shou; Kolenkiewicz, R.; Wade, C., Jr.

2003-01-01

Orbital noise of Earth's obliquity can provide an insight into the core of the Earth that causes intensity fluctuations in the geomagnetic field. Here we show that noise spectrum of the obliquity frequency have revealed a series of frequency periods centered at 250-, 1OO-, 50-, 41-, 30-, and 26-kyr which are almost identical with the observed spectral peaks from the composite curve of 33 records of relative paleointensity spanning the past 800 kyr (Sint-800 data). A continuous record for the past two million years also reveals the presence of the major 100 kyr periodicity in obliquity noise and geomagnetic intensity fluctuations. These results of correlation suggest that obliquity noise may power the dynamo, located in the liquid outer core of the Earth, which generates the geomagnetic field.

Optical observations of the Phoenicid meteor shower in 2014 and activity of comet 289P/Blanpain in the early 20th century

Science.gov (United States)

Fujiwara, Yasunori; Nakamura, Takuji; Uehara, Satoshi; Sagayama, Toru; Toda, Hiroyuki

2017-08-01

Optical observations of the Phoenicid meteor shower were made in North Carolina, USA, with seven video cameras and two digital cameras over a period of about 5 hr between 22:30 UT on 2014 December 1 and 04:00 UT on December 2. Activity of the Phoenicids was confirmed during this period, including the predicted maximum around 00 h UT on December 2. The activity level was not high, considering that 29 Phoenicid meteors and 109 non-Phoenicid meteors were detected. A gentle peak in the activity was recognized between 01:00 UT and 03:00 UT on December 2. The compact radiant of the Phoenicids agreed well with what was predicted. A comparison of the observed and predicted peak times, radiant position, bright meteors' dominance, and radiants' spread revealed that the observed meteors originated from the dust trails formed by comet 289P/Blanpain at the perihelion passage in the early 20th century. This indicates that the parent body of the Phoenicids, comet 289P/Blanpain, was still active as a comet in the early 20th century and provided meteoroids, although its activity level was significantly weaker than that at the beginning of the 19th century.

The International Geomagnetic Reference Field: the twelfth generation

Science.gov (United States)

Thebault, Erwan; Finlay, Christopher; The IGRF Working Group

2015-04-01

The IGRF is an internationally-agreed reference model of the Earth's magnetic field produced under the auspices of the International Association of Geomagnetism and Aeronomy. The IGRF-12 is the latest update of this well-known model which is used each year by many thousands of users for both industrial and scientific purposes. In October 2014, ten institutions worldwide have made contributions to the IGRF. These models were evaluated and the twelfth generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014. In this presentation, we will report on the IGRF activities, briefly describe the candidate models, summarize the evaluation of models performed by different independent teams, show how the IGRF-12 models were calculated and finally discuss some of the main magnetic features of this new model.

Low-altitude trapped protons at the geomagnetic equator

International Nuclear Information System (INIS)

Guzik, T.G.; Miah, M.A.; Mitchell, J.W.; Wefel, J.P.

1989-01-01

Geomagnetically trapped protons in the 0.6- to 9-MeV energy range were measured at latitudes near the geomagnetic equator by the Phoenix 1 experiment on board the S81-1 mission from May to November 1982. The protons show a distribution in latitude along the line of minimum magnetic field strength with a full width at half maximum of ∼10 0 but with no appreciable longitudinal variation. Between 170 and 290 km the peak proton flux shows a fifth-power altitude dependence, in contrast to previous measurements at higher altitudes, possibly demonstrating source attenuation. The efficiency of the telescope is calculated as a function of particle pitch angle and used to investigate the time dependence (1969--1982) of the intensity. copyright American Geophysical Union 1989

Methodology for simulation of geomagnetically induced currents in power systems

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Boteler David

2014-07-01

Full Text Available To assess the geomagnetic hazard to power systems it is useful to be able to simulate the geomagnetically induced currents (GIC that are produced during major geomagnetic disturbances. This paper examines the methodology used in power system analysis and shows how it can be applied to modelling GIC. Electric fields in the area of the power network are used to determine the voltage sources or equivalent current sources in the transmission lines. The power network can be described by a mesh impedance matrix which is combined with the voltage sources to calculate the GIC in each loop. Alternatively the power network can be described by a nodal admittance matrix which is combined with the sum of current sources into each node to calculate the nodal voltages which are then used to calculate the GIC in the transmission lines and GIC flowing to ground at each substation. Practical calculations can be made by superposition of results calculated separately for northward and eastward electric fields. This can be done using magnetic data from a single observatory to calculate an electric field that is a uniform approximation of the field over the area of the power system. It is also shown how the superposition of results can be extended to use data from two observatories: approximating the electric field by a linear variation between the two observatory locations. These calculations provide an efficient method for simulating the GIC that would be produced by historically significant geomagnetic storm events.

Solar Wind Charge Exchange During Geomagnetic Storms

Science.gov (United States)

Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

2012-01-01

On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

Geomagnetically trapped carbon, nitrogen, and oxygen nuclei.

Science.gov (United States)

Mogro-Campero, A.

1972-01-01

Results of measurements carried out with the University of Chicago nuclear composition telescope on the Ogo 5 satellite, establishing the presence of 13- to 33-MeV/nucleon geomagnetically trapped C and O nuclei, with some evidence for N nuclei. These trapped nuclei were found at L less than or equal to 5 and near the geomagnetic equator. The data cover the period from Mar. 3, 1968, to Dec. 31, 1969. The distribution of CNO flux as a function of L is given. No change in the intensity of the average trapped CNO flux was detected by comparing data for 1968 and 1969. The results reported set a new value for the observed high energy limit of trapping as described by the critical adiabaticity parameter. The penetration of solar flare CNO up to L = 4 was observed twice in 1968, in disagreement with Stormer theory predictions. The effects of these results on some models for the origin of the trapped radiation are discussed.

Meteor radar measurements of MLT winds near the equatorial electro jet region over Thumba (8.5° N, 77° E: comparison with TIDI observations

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S. R. John

2011-07-01

Full Text Available The All-Sky interferometric meteor (SKYiMET radar (MR derived winds in the vicinity of the equatorial electrojet (EEJ are discussed. As Thumba (8.5° N, 77° E; dip lat. 0.5° N is under the EEJ belt, there has been some debate on the reliability of the meteor radar derived winds near the EEJ height region. In this regard, the composite diurnal variations of zonal wind profiles in the mesosphere-lower thermosphere (MLT region derived from TIMED Doppler Interferometer (TIDI and ground based meteor radar at Thumba are compared. In this study, emphasis is given to verify the meteor radar observations at 98 km height region, especially during the EEJ peaking time (11:00 to 14:00 LT. The composite diurnal cycles of zonal winds over Thumba are constructed during four seasons of the year 2006 using TIDI and meteor radar observations, which showed good agreement especially during the peak EEJ hours, thus assuring the reliability of meteor radar measurements of neutral winds close to the EEJ height region. It is evident from the present study that on seasonal scales, the radar measurements are not biased by the EEJ. The day-time variations of HF radar measured E-region drifts at the EEJ region are also compared with MR measurements to show there are large differences between ionospheric drifts and MR measurements. The significance of the present study lies in validating the meteor radar technique over Thumba located at magnetic equator by comparing with other than the radio technique for the first time.

Geomagnetically conjugate observations of ionospheric and thermospheric variations accompanied by a midnight brightness wave at low latitudes

Science.gov (United States)

Fukushima, D.; Shiokawa, K.; Otsuka, Y.; Kubota, M.; Yokoyama, T.; Nishioka, M.; Komonjinda, S.; Yatini, C. Y.

2017-08-01

We conducted geomagnetically conjugate observations of 630-nm airglow for a midnight brightness wave (MBW) at Kototabang, Indonesia [geomagnetic latitude (MLAT): 10.0°S], and Chiang Mai, Thailand (MLAT: 8.9°N), which are geomagnetically conjugate points at low latitudes. An airglow enhancement that was considered to be an MBW was observed in OI (630-nm) airglow images at Kototabang around local midnight from 2240 to 2430 LT on February 7, 2011. This MBW propagated south-southwestward, which is geomagnetically poleward, at a velocity of 290 m/s. However, a similar wave was not observed in the 630-nm airglow images at Chiang Mai. This is the first evidence of an MBW that does not have geomagnetic conjugacy, which also implies generation of MBW only in one side of the hemisphere from the equator. We simultaneously observed thermospheric neutral winds observed by a co-located Fabry-Perot interferometer at Kototabang. The observed meridional winds turned from northward (geomagnetically equatorward) to southward (geomagnetically poleward) just before the wave was observed. This indicates that the observed MBW was generated by the poleward winds which push ionospheric plasma down along geomagnetic field lines, thereby increasing the 630-nm airglow intensity. The bottomside ionospheric heights observed by ionosondes rapidly decreased at Kototabang and slightly increased at Chiang Mai. We suggest that the polarization electric field inside the observed MBW is projected to the northern hemisphere, causing the small height increase observed at Chiang Mai. This implies that electromagnetic coupling between hemispheres can occur even though the original disturbance is caused purely by the neutral wind.[Figure not available: see fulltext.

Bangs and meteors from the quiet comet 15P/Finlay

Czech Academy of Sciences Publication Activity Database

Ye, Q.Z.; Brown, P. G.; Bell, Ch.; Gao, X.; Mašek, Martin; Hui, M.T.

2015-01-01

Roč. 814, č. 1 (2015), s. 1-10, č. článku 79. ISSN 0004-637X R&D Projects: GA MŠk(CZ) LG13007 EU Projects: European Commission(XE) 283783 - GLORIA Institutional support: RVO:68378271 Keywords : comet s * 15P/Finlay * meteorites * meteors * meteoroids Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.909, year: 2015

Measurements of meteor smoke particles during the ECOMA-2006 campaign: 2. Results

Science.gov (United States)

Strelnikova, Irina; Rapp, Markus; Strelnikov, Boris; Baumgarten, Gerd; Brattli, Alvin; Svenes, Knut; Hoppe, Ulf-Peter; Friedrich, Martin; Gumbel, Jörg; Williams, Bifford P.

2009-03-01

The first sounding rocket of the European ECOMA-project (ECOMA, Existence and Charge state Of Meteoric smoke particles in the middle Atmosphere) was launched on 8 September 2006. Measurements with a new particle detector described in the companion paper by Rapp and Strelnikova [2008. Measurements of meteor smoke particles during the ECOMA-2006 campaign: 1. Particle detection by active photoionization. Journal of Atmospheric and Solar-Terrestrial Physics, this issue, doi:10.1016/j.jastp.2008.06.002] clearly showed meteor smoke particle (MSP) signatures in both data channels. The data channels measure particles directly impacting on the detector electrode and photoelectrons from the particles actively created using ionization by the UV-photons of a xenon-flashlamp. Measured photoelectron currents resemble model expectations of the shape of the MSP layer almost perfectly, whereas derived number densities in the altitude range 60-90 km are larger than model results by about a factor of 5. Given the large uncertainties inherent to both model and the analysis of our measurements (e.g., the composition of the particles is not known and must be assumed) we consider this a satisfactory agreement and proof that MSPs do extend throughout the entire mesosphere as predicted by models. The measurements of direct particle impacts revealed a confined layer of negative charge between 80 and 90 km. This limited altitude range, however, is quantitatively shown to be the consequence of the aerodynamics of the rocket flight and does not have any geophysical origin. Measured charge signatures are consistent with expectations of particle charging given our own measurements of the background ionization. Unfortunately, however, a contamination of these measurements from triboelectric charging cannot be excluded at this stage.

On the formation of meteor showers of comet Halley

International Nuclear Information System (INIS)

Babadzhanov, P.B.; Obrubov, J.V.; Pushkarev, A.N.; Hajduk, A.

1987-01-01

The orbits of test particles ejected from the nucleus of Halley comet at its perihelion passage in 1910 with different velocities are studied for the next three passages of the comet up to 2134 taking into consideration perturbations from all planets. Some characteristics of the stream formation are presented. The calculations show that the return of the comet to its perihelion cannot produce an immediate influence on the activity of its meteor showers. (author). 2 figs., 1 tab., 13 refs

Analysis of the monitoring data of geomagnetic storm interference in the electrification system of a high-speed railway

Science.gov (United States)

Liu, Lianguang; Ge, Xiaoning; Zong, Wei; Zhou, You; Liu, Mingguang

2016-10-01

To study the impact of geomagnetic storm on the equipment of traction electrification system in the high-speed railway, geomagnetically induced current (GIC) monitoring devices were installed in the Hebi East traction power supply substation of the Beijing-Hong Kong Dedicated Passenger Line in January 2015, and GICs were captured during the two geomagnetic storms on 17 March and 23 June 2015. In order to investigate the GIC flow path, both in the track circuit and in the traction network adopting the autotransformer feeding system, a GIC monitor plan was proposed for the electrical system in the Hebi East traction power supply substation. This paper analyzes the correlation between the GIC captured on 17 March and the geomagnetic data obtained from the Malingshan Geomagnetic Observatory and presents a regression analysis between the measured GIC and the calculated geoelectric fields on 23 June in the high-speed railway. The maximum GICs measured in the track circuit are 1.08 A and 1.74 A during the two geomagnetic storms. We find that it is necessary to pay attention on the throttle transformers and track circuits, as the most sensitive elements responding to the extreme geomagnetic storms in the high-speed railway.

Effect of ionic composition of meteor trace on its relaxation time in the presence of external electric field

International Nuclear Information System (INIS)

Klimov, M.P.; Lyatskaya, A.M.

1989-01-01

The dissipation of meteor trace as the function of ionic composition and electric field is investigated numerically. Critical values of electric field E 1 and E 2 are determined. At E 1 the dissipation process is similar to the diffusion one; lifetimes are proportional to diffusion coefficient. At E 1 2 - the dissipation process falls into two phases with different character of lifetime dependence on meteor trace mass. At E>E 2 lifetime does not depend on the electric field

Ground based observations of Pc3-Pc5 geomagnetic pulsation power at Antarctic McMurdo station

Directory of Open Access Journals (Sweden)

C. G. Maclennan

1998-06-01

Full Text Available The two horizontal geomagnetic components and, measured by a fluxgate magnetometer at Antarctic McMurdo station (corrected geomagnetic coordinates 80.0° S, 327.5° E, are analyzed for the period May-June 1994; the spectral powers are calculated and integrated over three frequency intervals corresponding to the nominal ranges. The time dependence of those integrated powers and their correlations with northern auroral indices and solar wind speed are considered. The observations are compared with previous results reported from Terra Nova Bay station (located near McMurdo at the same corrected geomagnetic latitude during Antarctic summer intervals. The differences found between the two stations are discussed in terms of the seasonal dependence of geomagnetic field line configurations in the near cusp region.

The Development of Models for Assessment of the Geomagnetically Induced Currents Impact on Electric Power Grids during Geomagnetic Storms

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VAKHNINA, V. V.

2015-02-01

Full Text Available A model and an algorithm for the calculation of the functioning of an electric power grid of arbitrary configuration and complexity during geomagnetic storms were developed. The calculations were performed in the MATLAB mathematical package and the Simulink environment. The binding of objects to geographical coordinates is realized in the model, which enables to determine the matrix of potentials of geoelectric fields in nodal points. In order to define the instantaneous magnetizing currents, the power transformers are designed on the basis of the T-shaped equivalent circuit with a nonlinear mutual inductance of magnetization branch. Calculation of RMS values of active, reactive and total power values in all the elements is done with regard to the impact of harmonic components of the current and voltage. The results of modeling of the impact of geomagnetic storms of various intensity with the west-east direction of the geoelectric field vector for Samara region electric power grid are given.

Local geomagnetic events associated with displacements on the san andreas fault.

Science.gov (United States)

Breiner, S; Kovach, R L

1967-10-06

The piezomagnetic properties of rock suggest that a change in subsurface stress will manifest itself as a change in the magnetic susceptibility and remanent magnetization and hence the local geomagnetic field. A differential array of magnetometers has been operating since late 1965 on the San Andreas fault in the search for piezomagnetic signals under conditions involving active fault stress. Local changes in the geomagnetic field have been observed near Hollister, California, some tens of hours preceding the onset of abrupt creep displacement on the San Andreas fault.

Seasonal and diurnal variability of the meteor flux at high latitudes observed using PFISR

Science.gov (United States)

Sparks, J. J.; Janches, D.; Nicolls, M. J.; Heinselman, C. J.

2009-05-01

We report in this and a companion paper [Fentzke, J.T., Janches, D., Sparks, J.J., 2008. Latitudinal and seasonal variability of the micrometeor input function: A study using model predictions and observations from Arecibo and PFISR. Journal of Atmospheric and Solar-Terrestrial Physics, this issue, doi:10.1016/j.jastp.2008.07.015] a complete seasonal study of the micrometeor input function (MIF) at high latitudes using meteor head-echo radar observations performed with the Poker Flat Incoherent Scatter Radar (PFISR). This flux is responsible for a number of atmospheric phenomena; for example, it could be the source of meteoric smoke that is thought to act as condensation nuclei in the formation of ice particles in the polar mesosphere. The observations presented here were performed for full 24-h periods near the summer and winter solstices and spring and autumn equinoxes, times at which the seasonal variability of the MIF is predicted to be large at high latitudes [Janches, D., Heinselman, C.J., Chau, J.L., Chandran, A., Woodman, R., 2006. Modeling of the micrometeor input function in the upper atmosphere observed by High Power and Large Aperture Radars, JGR, 11, A07317, doi:10.1029/2006JA011628]. Precise altitude and radar instantaneous line-of-sight (radial) Doppler velocity information are obtained for each of the hundreds of events detected every day. We show that meteor rates, altitude, and radial velocity distributions have a large seasonal dependence. This seasonal variability can be explained by a change in the relative location of the meteoroid sources with respect to the observer. Our results show that the meteor flux into the upper atmosphere is strongly anisotropic and its characteristics must be accounted for when including this flux into models attempting to explain related aeronomical phenomena. In addition, the measured acceleration and received signal strength distribution do not seem to depend on season; which may suggest that these observed

Improved analysis of all-sky meteor radar measurements of gravity wave variances and momentum fluxes

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V. F. Andrioli

2013-05-01

Full Text Available The advantages of using a composite day analysis for all-sky interferometric meteor radars when measuring mean winds and tides are widely known. On the other hand, problems arise if this technique is applied to Hocking's (2005 gravity wave analysis for all-sky meteor radars. In this paper we describe how a simple change in the procedure makes it possible to use a composite day in Hocking's analysis. Also, we explain how a modified composite day can be constructed to test its ability to measure gravity wave momentum fluxes. Test results for specified mean, tidal, and gravity wave fields, including tidal amplitudes and gravity wave momentum fluxes varying strongly with altitude and/or time, suggest that the modified composite day allows characterization of monthly mean profiles of the gravity wave momentum fluxes, with good accuracy at least at the altitudes where the meteor counts are large (from 89 to 92.5 km. In the present work we also show that the variances measured with Hocking's method are often contaminated by the tidal fields and suggest a method of empirical correction derived from a simple simulation model. The results presented here greatly increase our confidence because they show that our technique is able to remove the tide-induced false variances from Hocking's analysis.

Solar and Geomagnetic Activity Variations Correlated to Italian M6+ Earthquakes Occurred in 2016

Science.gov (United States)

Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

2017-04-01

Between August 2016 and October 2016 in Italy were recorded three strong earthquakes: M6.2 on August 2016 at 01:36:32 UTC; M6.1 on October 26, 2016 at 19:18:08 UTC and M6,6 on October 30, 2016 at 06:40:18 UTC. The authors of this study wanted to verify the existence of a correlation between these earthquakes and solar/geomagnetic activity. To confirming or not the presence of this kind of correlation, the authors analyzed the conditions of Spaceweather "near Earth" and the characteristics of the Earth's geomagnetic field in the hours that preceded the three earthquakes. The data relating to the three earthquakes were provided by the United States Geological Survey (USGS). The data on ion density used to realize the correlation study are represented by: solar wind ion density variation detected by ACE (Advanced Composition Explorer) Satellite, in orbit near the L1 Lagrange point, at 1.5 million of km from Earth, in direction of the Sun. The instrument used to perform the measurement of the solar wind ion density is the Electron, Proton, and Alpha Monitor (EPAM) instrument, equipped on the ACE Satellite. To conduct the study, the authors have taken in consideration the variation of the solar wind protons density of three different energy fractions: differential proton flux 1060-1900 keV (p/cm^2-sec-ster-MeV); differential proton flux 761-1220 keV (p/cm^2-sec-ster-MeV); differential proton flux 310-580 keV (p/cm^2-sec-ster-MeV). Geomagnetic activity data were provided by Tromsø Geomagnetic Observatory (TGO), Norway; by Scoresbysund Geomagnetic Observatory (SCO), Greenland, Denmark; Dikson Geomagnetic Observatory (DIK), Russia and by Pushkov Institute of terrestrial magnetism, ionosphere and radio wave propagation (IZMIRAN), Troitsk, Moscow Region. The results of the study, in agreement with what already ascertained by authors from 2012, have confirmed that the three strong Italian earthquakes were preceded by a clear increase of the solar wind proton density which

Ten cycles of solar and geomagnetic activity

International Nuclear Information System (INIS)

Legrand, J.P.

1981-01-01

Series of 110 years of sunspot numbers and indices of geomagnetic activity are used with 17 years of solar wind data in order to study through solar cycles both stream and shock event solar activity. According to their patterns on Bartels diagrams of geomagnetic indices, stable wind streams and transient solar activities are separated from each other. Two classes of stable streams are identified: equatorial streams occurring sporadically, for several months, during the main phase of sunspot cycles and both polar streams established, for several years, at each cycle, before sunspot minimum. Polar streams are the first activity of solar cycles. For study of the relationship between transient geomagnetic phenomena and sunspot activity, we raise the importance of the contribution, at high spot number, of severe storms and, at low spot number, of short lived and unstable streams. Solar wind data are used to check and complete the above results. As a conclusion, we suggest a unified scheme of solar activity evolution with a starting point every eleventh year, a total duration of 17 years and an overlapping of 6 years between the first and the last phase of both successive series of phenomena: first, from polar field reversal to sunspot minimum, a phase of polar wind activity of the beginning cycle is superimposed on the weak contribution of shock events of the ending cycle; secondly, an equatorial phase mostly of shock events is superimposed on a variable contribution of short lived and sporadic stable equatorial stream activities; and thirdly a phase of low latitude shock events is superimposed on the polar stream interval of the following cycle. (orig.)

Cabozantinib Versus Everolimus in Patients with Advanced Renal Cell Carcinoma: Results of a Randomised Phase III Trial (METEOR

Directory of Open Access Journals (Sweden)

Toni Choueiri

2015-11-01

Full Text Available The METEOR trial of cabozantinib versus everolimus in advanced renal cell carcinoma (RCC was reported by Prof Choueiri at the European Cancer Congress 2015. This presentation follows the publication in the New England Journal of Medicine of the METEOR trial back-to-back with the CheckMate 025 trial of nivolumab versus everolimus in the same patient setting. Excitingly, these trials demonstrated, for the first time, significant benefits over the standard of care for heavily pre-treated patients with advanced RCC. Cabozantinib, an oral multi-targeted tyrosine kinase inhibitor (TKI aims to address the challenge of resistance to targeted therapy with TKIs. While the METEOR trial has not yet reached its final analysis of overall survival (OS, the clear progression-free survival (PFS benefit, acceptable safety profile, and similar tolerability to other TKIs shown by cabozantinib indicate that this represents a promising new treatment option for second-line or subsequent therapy for patients with advanced RCC.

Letter to the Editor: Geomagnetic storm effects at low latitudes

OpenAIRE

R. G. Rastogi; R. G. Rastogi

1999-01-01

The geomagnetic horizontal (H) field from the chain of nine observatories in India are used to study the storm-time and disturbance daily variations. The peak decrease in storm-time variation in H showed significant enhancements at the equatorial electrojet stations over and above the normally expected decrease due to the ring current effects corrected for geomagnetic latitudes. The disturbance daily variation of H at equatorial stations showed a large decrease around midday...

Up-to-date Geomagnetic Coordinate Transforms with AACGM

Science.gov (United States)

Stephens, G. K.; Morrison, D.; Barnes, R. J.; Potter, M.; Schaefer, R. K.

2017-12-01

Geomagnetic plasmas organize along magnetic field lines, thus, it is often appropriate to use magnetic field line conjunctions for comparisons between spacecraft observations. Due to the expense of tracing magnetic field lines, the Altitude-Adjusted Corrected GeoMagnetic (AACGM) coordinate system is used. The (AACGM) coordinates are defined by the best fit dipole of the Earth's magnetic field and have been a standard tool used by the SPA community for a long time. However, standard 5 year updated coefficients for this transform are no longer available after the 2010 set. A new version of AACGM (V2 - Shepard, 2014) has been defined. AACGM V2 is fit to a spherical harmonic expansion. A pitfall with this V2 coordinate system is that it is undefined near the magnetic equator, which is problematic for determining conjunctions for spacecraft that with ground stations that pass through these regions. We have derived a new set of coefficients valid for the current epoch that allow us to continue to use the original version of AACGM. We also explore the errors that are introduced by ignoring the magnetic field caused by magnetospheric electric currents. The derived coefficients are made available to the public along with Java software that can be used to evaluate the AACGM coordinates. Shepard, S., 2014, Altitude-Adjusted Corrected Geomagnetic Coordinates: Definition and Functional Approximations, Jour. Geophys. Res., 119, 020264, DOI:10.1002/2014JA020264

The response of the 11 August 1999 total solar eclipse in the geomagnetic field

Czech Academy of Sciences Publication Activity Database

Střeštík, Jaroslav

85-86, 1/3 (2001), s. 561-566 ISSN 0167-9295 R&D Projects: GA ČR GA205/99/0915 Institutional research plan: CEZ:AV0Z3012916 Keywords : geomagnetic pulsations * geomagnetic variations * total solar eclipse Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.457, year: 2001

Dynamical modeling validation of parent bodies associated with newly discovered CMN meteor showers

Czech Academy of Sciences Publication Activity Database

Šegon, D.; Vaubaillon, J.; Gural, P.S.; Vida, D.; Andreić, Z.; Korlević, K.; Skokić, Ivica

2017-01-01

Roč. 598, February (2017), A15/1-A15/13 E-ISSN 1432-0746 Institutional support: RVO:67985815 Keywords : meteorites * meteors * meteoroids Subject RIV: BN - Astronomy , Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.014, year: 2016

The South Atlantic Anomaly: the key for a possible geomagnetic reversal

Directory of Open Access Journals (Sweden)

F. Javier ePavón-Carrasco

2016-04-01

Full Text Available The South Atlantic Anomaly is nowadays one of the most important features of the Earth’s magnetic field. Its extent area at the Earth’s surface is continuously growing since the intensity instrumental measurements are available covering part of the Southern Hemisphere and centred in South America. Several studies associate this anomaly as an indicator of an upcoming geomagnetic transition, such an excursion or reversal. In this paper we carry out a detailed study about this issue using the most recent models that also include data from the last ESA mission Swarm. Our results reveal that one of the reversed polarity patch located under the South Atlantic Ocean is growing with a pronounced rate of -2.54•105 nT per century and with western drift. In addition, we demonstrate that the quadrupole field mainly controls this reversal patch at the CMB along with the rapid decay of the dipolar field. The presence of the reversal patches at the CMB seems to be characteristic during the preparation phase of a geomagnetic transition. However, the present value of the dipolar moment (7.7 1022A•m2 is not so low when compared with recent paleomagnetic data for the Holocene (last 12ka and for the entire Brunhes geomagnetic normal polarity (last 0.8 Ma, although the rate of decay is similar of the previous documented geomagnetic reversals or excursions.

IAGA Geomagnetic Data Analysis format - Analysis_IAGA

Science.gov (United States)

-Emilian Toader, Victorin; Marmureanu, Alexandru

2013-04-01

Geomagnetic research involves a continuous Earth's magnetic field monitoring and software for processing large amounts of data. The Analysis_IAGA program reads and analyses files in IAGA2002 format used within the INTERMAGNET observer network. The data is made available by INTERMAGNET (http://www.intermagnet.org/Data_e.php) and NOAA - National Geophysical Data Center (ftp://ftp.ngdc.noaa.gov/wdc/geomagnetism/data/observatories/definitive) cost free for scientific use. The users of this software are those who study geomagnetism or use this data along with other atmospheric or seismic factors. Analysis_IAGA allows the visualization of files for the same station, with the feature of merging data for analyzing longer time intervals. Each file contains data collected within a 24 hour time interval with a sampling rate of 60 seconds or 1 second. Adding a large number of files may be done by dividing the sampling frequency. Also, the program has the feature of combining data files gathered from multiple stations as long as the sampling rate and time intervals are the same. Different channels may be selected, visualized and filtered individually. Channel properties can be saved and edited in a file. Data can be processed (spectral power, P / F, estimated frequency, Bz/Bx, Bz/By, convolutions and correlations on pairs of axis, discrete differentiation) and visualized along with the original signals on the same panel. With the help of cursors/magnifiers time differences can be calculated. Each channel can be analyzed separately. Signals can be filtered using bandpass, lowpass, highpass (Butterworth, Chebyshev, Inver Chebyshev, Eliptic, Bessel, Median, ZeroPath). Separate graphics visualize the spectral power, frequency spectrum histogram, the evolution of the estimated frequency, P/H, the spectral power. Adaptive JTFA spectrograms can be selected: CSD (Cone-Shaped Distribution), CWD (Choi-Williams Distribution), Gabor, STFT (short-time Fourier transform), WVD (Wigner

Meteoroid orbits from video meteors. The case of the Geminid stream

Czech Academy of Sciences Publication Activity Database

Hajduková jr., M.; Koten, Pavel; Kornoš, L.; Toth, J.

2017-01-01

Roč. 143, SI (2017), s. 89-98 ISSN 0032-0633. [Meteoroids 2016. Nordwijk, 06.06.2016-10.06.2016] R&D Projects: GA ČR GA14-25251S Institutional support: RVO:67985815 Keywords : meteors * meteoroid orbits * meteoroid streams Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science ) Impact factor: 1.892, year: 2016

How does the predicted geomagnetic main field variation alter the thermosphere-ionosphere storm-time response?

Science.gov (United States)

Maute, A. I.; Lu, G.; Richmond, A. D.

2017-12-01

Earth's magnetic main field plays an important role in the thermosphere-ionosphere (TI) system, as well as its coupling to Earth's magnetosphere. The ionosphere consists of a weakly ionized plasma strongly influenced by the main field and embedded in the thermosphere. Therefore, ion-neutral coupling and ionospheric electrodynamics can influence the plasma distribution and neutral dynamics. There are strong longitude variations of the TI storm response. At high latitude magnetosphere-ionosphere coupling is organized by the geomagnetic main field, leading in general to stronger northern middle latitude storm time response in the American sector due to the geomagnetic dipole location. In addition, the weak geomagnetic main field in the American sector leads to larger local ExB drift and can alter the plasma densities. During geomagnetic storms the intense energy input into the high latitude region is redistributed globally, leading to thermospheric heating, wind circulation changes and alterations of the ionospheric electrodynamics. The storm time changes are measurable in the plasma density, ion drift, temperature, neutral composition, and other parameters. All these changes depend, to some degree, on the geomagnetic main field which changes on decadal time scales. In this study, we employ a forecast model of the geomagnetic main field based on data assimilation and geodynamo modeling [Aubert et al., 2015]. The main field model predicts that in 50 years the South Atlantic Anomaly is further weakened by 2 mT and drifts westward by approximately 10o. The dipole axis moves northward and westward by 2o and 6o, respectively. Simulating the March 2015 geomagnetic storm with the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM) driven by the Assimilative Mapping of Ionospheric Electrodynamics (AMIE), we evaluate the thermosphere-ionosphere response using the geomagnetic main field of 2015, 2065, and 2115. We compare the TI response for 2015 with

Modelling geomagnetically induced currents in midlatitude Central Europe using a thin-sheet approach

Science.gov (United States)

Bailey, Rachel L.; Halbedl, Thomas S.; Schattauer, Ingrid; Römer, Alexander; Achleitner, Georg; Beggan, Ciaran D.; Wesztergom, Viktor; Egli, Ramon; Leonhardt, Roman

2017-06-01

Geomagnetically induced currents (GICs) in power systems, which can lead to transformer damage over the short and the long term, are a result of space weather events and geomagnetic variations. For a long time, only high-latitude areas were considered to be at risk from these currents, but recent studies show that considerable GICs also appear in midlatitude and equatorial countries. In this paper, we present initial results from a GIC model using a thin-sheet approach with detailed surface and subsurface conductivity models to compute the induced geoelectric field. The results are compared to measurements of direct currents in a transformer neutral and show very good agreement for short-period variations such as geomagnetic storms. Long-period signals such as quiet-day diurnal variations are not represented accurately, and we examine the cause of this misfit. The modelling of GICs from regionally varying geoelectric fields is discussed and shown to be an important factor contributing to overall model accuracy. We demonstrate that the Austrian power grid is susceptible to large GICs in the range of tens of amperes, particularly from strong geomagnetic variations in the east-west direction.

Automated Meteor Detection by All-Sky Digital Camera Systems

Czech Academy of Sciences Publication Activity Database

Suk, Tomáš; Šimberová, Stanislava

2017-01-01

Roč. 120, č. 3 (2017), s. 189-215 ISSN 0167-9295 R&D Projects: GA ČR GA15-16928S Institutional support: RVO:67985815 ; RVO:67985556 Keywords : meteor detection * autonomous fireball observatories * fish-eye camera * Hough transformation Subject RIV: IN - Informatics, Computer Science; BN - Astronomy, Celestial Mechanics, Astrophysics (ASU-R) OBOR OECD: Computer sciences, information science, bioinformathics (hardware development to be 2.2, social aspect to be 5.8); Astronomy (including astrophysics,space science) (ASU-R) Impact factor: 0.875, year: 2016

Near real-time geomagnetic data for space weather applications in the European sector

Science.gov (United States)

Johnsen, M. G.; Hansen, T. L.

2012-12-01

Tromsø Geophysical Observatory (TGO) is responsible for making and maintaining long time-series of geomagnetic measurements in Norway. TGO is currently operating 3 geomagnetic observatories and 11 variometer stations from southern Norway to Svalbard . Data from these 14 locations are acquired, processed and made available for the user community in near real-time. TGO is participating in several European Union (EU) and European Space Agency (ESA) space weather related projects where both near real-time data and derived products are provided. In addition the petroleum industry is benefiting from our real-time data services for directional drilling. Near real-time data from TGO is freely available for non-commercial purposes. TGO is exchanging data in near real-time with several institutions, enabling the presentation of near real-time geomagnetic data from more than 40 different locations in Fennoscandia and Greenland. The open exchange of non real-time geomagnetic data has been successfully going on for many years through services such as the world data center in Kyoto, SuperMAG, IMAGE and SPIDR. TGO's vision is to take this one step further and make the exchange of near real-time geomagnetic data equally available for the whole community. This presentation contains an overview of TGO, our activities and future aims. We will show how our near real-time data are presented. Our contribution to the space weather forecasting and nowcasting effort in the EU and ESA will be presented with emphasis on our real-time auroral activity index and brand new auroral activity monitor and electrojet tracker.

Meteor head echo altitude distributions and the height cutoff effect studied with the EISCAT HPLA UHF and VHF radars

Directory of Open Access Journals (Sweden)

A. Westman

2004-04-01

Full Text Available Meteor head echo altitude distributions have been derived from data collected with the EISCAT VHF (224MHz and UHF (930MHz high-power, large-aperture (HPLA radars. At the high-altitude end, the distributions cut off abruptly in a manner reminiscent of the trail echo height ceiling effect observed with classical meteor radars. The target dimensions are shown to be much smaller than both the VHF and the UHF probing wavelengths, but the cutoff heights for the two systems are still clearly different, the VHF cutoff being located several km above the UHF one. A single-collision meteor-atmosphere interaction model is used to demonstrate that meteors in the (1.3–7.2µg mass range will ionise such that critical electron density at 224MHz is first reached at or around the VHF cutoff altitude and critical density at 930MHz will be reached at the UHF cutoff altitude. The observed seasonal variation in the cutoff altitudes is shown to be a function of the seasonal variation of atmospheric density with altitude. Assuming that the electron density required for detection is in the order of the critical density, the abrupt altitude cutoffs can be explained as a consequence of the micrometeoroid joint size-speed distribution dropping off so fast at the large-mass, high-velocity end that above a certain altitude the number of detectable events becomes vanishingly small. Conversely, meteors at the low-mass end of the distribution will be gradually retarded such that the ionisation they generate never reaches critical density. These particles will remain unobservable.Key words. Radio science (instruments and techniques – Interplatery physics (interplanetary dust – General or miscellaneous (new fields

Long-term variations in the geomagnetic activity level Part II: Ascending phases of sunspot cycles

Directory of Open Access Journals (Sweden)

V. Mussino

1994-08-01

Full Text Available Monthly averages of the Helsinki Ak-values have been reduced to the equivalent aa-indices to extend the aa-data set back to 1844. A periodicity of about five cycles was found for the correlation coefficient (r between geomagnetic indices and sunspot numbers for the ascending phases of sunspot cycles 9 to 22, confirming previous findings based on a minor number of sunspot cycles. The result is useful to researchers in topics related to solar-terrestrial physics, particularly for the interpretation of long-term trends in geomagnetic activity during the past, and to forecast geomagnetic activity levels in the future.

Interplanetary magnetic field associated changes in cosmic ray intensity and geomagnetic field during 1973-75

International Nuclear Information System (INIS)

Singh, R.L.; Shukla, J.P.; Shukla, A.K.; Sharma, S.M.; Agrawal, S.P.

1979-01-01

The effects of interplanetary magnetic field (IMF) B and its Bsub(z) component on cosmic ray intensity and geomagnetic field variations have been examined for the period 1973-75. It is observed that: (1) B >= 10γ (magnetic blobs) is pre-requisite in producing cosmic ray intensity and geomagnetic field variations of varying magnitudes, (2) the longer existence of magnetic blobs on successive days produces larger decreases in cosmic ray intensity and geomagnetic field and (3) the southward component (Bsub(z)) of IMF generally gives rise to large Asub(p) changes, though it is not effective in producing cosmic ray intensity decreases. (auth.)

Paleomagnetic record of a geomagnetic field reversal from late miocene mafic intrusions, southern nevada.

Science.gov (United States)

Ratcliff, C D; Geissman, J W; Perry, F V; Crowe, B M; Zeitler, P K

1994-10-21

Late Miocene (about 8.65 million years ago) mafic intrusions and lava flows along with remagnetized host rocks from Paiute Ridge, southern Nevada, provide a high-quality paleomagnetic record of a geomagnetic field reversal. These rocks yield thermoremanent magnetizations with declinations of 227 degrees to 310 degrees and inclinations of -7 degrees to 49 degrees , defining a reasonably continuous virtual geomagnetic pole path over west-central Pacific longitudes. Conductive cooling estimates for the intrusions suggest that this field transition, and mafic magmatism, lasted only a few hundred years. Because this record comes principally from intrusive rocks, rather than sediments or lavas, it is important in demonstrating the longitudinal confinement of the geomagnetic field during a reversal.

The influence of meteorological and geomagnetic factors on acute myocardial infarction and brain stroke in Moscow, Russia.

Science.gov (United States)

Shaposhnikov, Dmitry; Revich, Boris; Gurfinkel, Yuri; Naumova, Elena

2014-07-01

Evidence of the impact of air temperature and pressure on cardiovascular morbidity is still quite limited and controversial, and even less is known about the potential influence of geomagnetic activity. The objective of this study was to assess impacts of air temperature, barometric pressure and geomagnetic activity on hospitalizations with myocardial infarctions and brain strokes. We studied 2,833 myocardial infarctions and 1,096 brain strokes registered in two Moscow hospitals between 1992 and 2005. Daily event rates were linked with meteorological and geomagnetic conditions, using generalized linear model with controls for day of the week, seasonal and long-term trends. The number of myocardial infarctions decreased with temperature, displayed a U-shaped relationship with pressure and variations in pressure, and increased with geomagnetic activity. The number of strokes increased with temperature, daily temperature range and geomagnetic activity. Detrimental effects on strokes of low pressure and falling pressure were observed. Relative risks of infarctions and strokes during geomagnetic storms were 1.29 (95% CI 1.19-1.40) and 1.25 (1.10-1.42), respectively. The number of strokes doubled during cold spells. The influence of barometric pressure on hospitalizations was relatively greater than the influence of geomagnetic activity, and the influence of temperature was greater than the influence of pressure. Brain strokes were more sensitive to inclement weather than myocardial infarctions. This paper provides quantitative estimates of the expected increases in hospital admissions on the worst days and can help to develop preventive health plans for cardiovascular diseases.

Political astronomy: Comet and meteor observations by Muslim historians

Science.gov (United States)

Chander Kapoor, Ramesh

2015-08-01

Eclipses and unexpected phenomena like comets, meteors, novae and earthquakes were viewed among various cultures as violating the established order of the heavens. They were considered to be ill omens for kings and emperors and were routinely monitored. The present work looks into the texts of history and literature by Muslim historians and chroniclers in West Asia and India that carry stray references to such phenomena. The accounts often relate the apparitions to specific disastrous events or prognosticate revolts, deaths, epidemics, earthquakes all that that took place in later times. Obviously, the occurrences interested the astrologers more. Comet appearances would last for days and weeks but nearly all the writings lack sequential observations. Meteor showers are annual features but the Islamic calendar being lunar would not easily lead one to notice periodic nature of the incidents, let alone sensing a periodicity in comet appearances. These are non-astronomy texts with little scientific content but being from different ages permit us to see how the astronomical perceptions changed over the times. The recorded details and firm chronology, tested against modern back calculations, can provide valuable information on them, keeping in mind the text and the context in which the original reference was made. We also notice a qualitative change in the Indian writings of the 18th century and later where the authors begin to show up with influence of exposure to the European scientific progress.

Applicability of meteor radiant determination methods depending on orbit type. I. High-eccentric orbits

Science.gov (United States)

Svoren, J.; Neslusan, L.; Porubcan, V.

1993-07-01

It is evident that there is no uniform method of calculating meteor radiants which would yield reliable results for all types of cometary orbits. In the present paper an analysis of this problem is presented, together with recommended methods for various types of orbits. Some additional methods resulting from mathematical modelling are presented and discussed together with Porter's, Steel-Baggaley's and Hasegawa's methods. In order to be able to compare how suitable the application of the individual radiant determination methods is, it is necessary to determine the accuracy with which they approximate real meteor orbits. To verify the accuracy with which the orbit of a meteoroid with at least one node at 1 AU fits the original orbit of the parent body, we applied the Southworth-Hawkins D-criterion (Southworth, R.B., Hawkins, G.S.: 1963, Smithson. Contr. Astrophys 7, 261). D0.2 the fit is rather poor and the change of orbit unrealistic. The optimal methods with the smallest values of D for given types of orbits are shown in two series of six plots. The new method of rotation around the line of apsides we propose is very appropriate in the region of small inclinations. There is no doubt that Hasegawa's omega-adjustment method (Hasegawa, I.: 1990, Publ. Astron. Soc. Japan 42, 175) has the widest application. A comparison of the theoretical radiants with the observed radiants of seven known meteor showers is also presented.

Isotopic characteristic of meteoric water and groundwater in Ahaggar massif (central Sahara)

International Nuclear Information System (INIS)

Saighi, O.; Michelot, J.L.; Filly, A.

2001-01-01

The mean contents of both oxygen-18 and deuterium in precipitation from the Ahaggar massif (central Sahara) are: δ 18 O = -3 per mille and 2 H = -15 per mille. The heterogeneity in meteoric events and the great scattering of these isotopic contents can be ascribed to the origins and the histories of air masses. The main contribution comes from the inflow of the Guinean monsoon during summer months. During winter, the N/W winds, arriving in the area from the Moroccan coast, provide some rains. The deuterium excess of these precipitation are up to +10 per mille, indicating that the air masses generating these rains are supplied by the recycling of the continental air moisture. Groundwater resources are produced in some little phreatic aquifers, which are recharged by sporadic wadi floods. Aquifer zones that are the most favourable are located in the valleys and occur as three overlying levels of unequal importance: the alluvial aquifer, the weathered zone of the underlying substratum and the deep aquifer of fissured basement. The alluvial aquifer contain weakly mineralised water (0.3 g/l). Their stable isotopes contents (δ 18 O∼ -2.7 per mille) and 14 C activity of them (> 100 pmc) are comparable to present meteoric water, allowing modern meteoric waters to be identified. The weathered zone groundwater's are more mineralised (0.8 g/l) and its isotopic contents (δ 18 O∼ -4.2 per mille) and intermediate radiocarbon activity, prove their old water component. The basement's groundwater are more mineralised (> 1 g/l) and their very depleted isotopic contents (δ 18 O∼ -9 per mille) diverge clearly from the present precipitation. Furthermore, the absence of 3 H and 14 C activity of them, prove an old heritage, resulting from recharge during the last humid episode of the Holocene. (author)

Long-term trends in geomagnetic and climatic variability

Czech Academy of Sciences Publication Activity Database

Bucha, Václav

2002-01-01

Roč. 27, 6/7 (2002), s. 427-731 ISSN 1474-7065 R&D Projects: GA AV ČR IAA3012806 Institutional research plan: CEZ:AV0Z3012916 Keywords : geomagnetic forcing * climatic variability * global warming Subject RIV: DE - Earth Magnetism, Geodesy, Geography

Magnetic local time dependence of geomagnetic disturbances contributing to the AU and AL indices

DEFF Research Database (Denmark)

Tomita, S; Nose´, M; Iyemori, T

2010-01-01

activity in the auroral zone. In the present study, we examine magnetic local time (MLT) dependence of geomagnetic field variations contributing to the AU and AL indices. We use 1-min geomagnetic field data obtained in 2003. It is found that both AU and AL indices have two ranges of MLT (AU: 15:00-22:00MLT...

Relation of geomagnetic activity index variations with parameters of interplanetary scintillations

International Nuclear Information System (INIS)

Vlasov, V.I.; Shishov, V.I.; Shishova, T.D.

1985-01-01

A correlation between the Asub(p)-index of geomagnetic activity, index of interplanetary scintillations and solar wind velocity, has been considered depending on the spatial position of the interplanetary plasma (IPP) regions under study. It is shown, that the scintillation index can be used to forecast the geomagnetic activity, whereas the solar wind velocity can not be used for the purpose. Heliolongitudinal dependence of geoeffectiveness of IPP sreading perturbations agrees well with their structure in the heliolongitudinal cross section (and, on the whole, with the angular structure and direction of IPP perturbation spread). To use interplanetary scintillations in forecasting the geomagnetic activity (on the level of correlation not below 0.5), the angular distance of the investigated IPP regions relative to the Sun-Earth line on the average should not exceed 30-40 deg. The time of delay between the moments of observation of variations in the scintillation index the time of passage of the corresponding heliocentric distances at an average rate of the interplanetary perturbation spread approximately 500 km/s

Evaluation of a new paleosecular variation activity index as a diagnostic tool for geomagnetic field variations

Science.gov (United States)

Panovska, Sanja; Constable, Catherine

2015-04-01

Geomagnetic indices like Dst, K and A, have been used since the early twentieth century to characterize activity in the external part of the modern geomagnetic field and as a diagnostic for space weather. These indices reflect regional and global activity and serve as a proxy for associated physical processes. However, no such tools are yet available for the internal geomagnetic field driven by the geodynamo in Earth's liquid outer core. To some extent this reflects limited spatial and temporal sampling for longer timescales associated with paleomagnetic secular variation, but recent efforts in both paleomagnetic data gathering and modeling activity suggest that longer term characterization of the internal geomagnetic weather/climate and its variability would be useful. Specifically, we propose an index for activity in paleosecular variation, useful as both a local and global measure of field stability during so-called normal secular variation and as a means of identifying more extreme behavior associated with geomagnetic excursions and reversals. To date, geomagnetic excursions have been identified by virtual geomagnetic poles (VGPs) deviating more than some conventional limit from the geographic pole (often 45 degrees), and/or by periods of significant intensity drops below some critical value, for example 50% of the present-day field. We seek to establish a quantitative definition of excursions in paleomagnetic records by searching for synchronous directional deviations and lows in relative paleointensity. We combine paleointensity variations with deviations from the expected geocentric axial dipole (GAD) inclination in a single parameter, which we call the paleosecular variation (PSV) activity index. This new diagnostic can be used on any geomagnetic time series (individual data records, model predictions, spherical harmonic coefficients, etc.) to characterize the level of paleosecular variation activity, find excursions, or even study incipient reversals

Modeling Geomagnetic Variations using a Machine Learning Framework

Science.gov (United States)

Cheung, C. M. M.; Handmer, C.; Kosar, B.; Gerules, G.; Poduval, B.; Mackintosh, G.; Munoz-Jaramillo, A.; Bobra, M.; Hernandez, T.; McGranaghan, R. M.

2017-12-01

We present a framework for data-driven modeling of Heliophysics time series data. The Solar Terrestrial Interaction Neural net Generator (STING) is an open source python module built on top of state-of-the-art statistical learning frameworks (traditional machine learning methods as well as deep learning). To showcase the capability of STING, we deploy it for the problem of predicting the temporal variation of geomagnetic fields. The data used includes solar wind measurements from the OMNI database and geomagnetic field data taken by magnetometers at US Geological Survey observatories. We examine the predictive capability of different machine learning techniques (recurrent neural networks, support vector machines) for a range of forecasting times (minutes to 12 hours). STING is designed to be extensible to other types of data. We show how STING can be used on large sets of data from different sensors/observatories and adapted to tackle other problems in Heliophysics.

Real-Time Detection of Sporadic Meteors in the Intensified TV Imaging Systems.

Science.gov (United States)

Vítek, Stanislav; Nasyrova, Maria

2017-12-29

The automatic observation of the night sky through wide-angle video systems with the aim of detecting meteor and fireballs is currently among routine astronomical observations. The observation is usually done in multi-station or network mode, so it is possible to estimate the direction and the speed of the body flight. The high velocity of the meteorite flying through the atmosphere determines the important features of the camera systems, namely the high frame rate. Thanks to high frame rates, such imaging systems produce a large amount of data, of which only a small fragment has scientific potential. This paper focuses on methods for the real-time detection of fast moving objects in the video sequences recorded by intensified TV systems with frame rates of about 60 frames per second. The goal of our effort is to remove all unnecessary data during the daytime and make free hard-drive capacity for the next observation. The processing of data from the MAIA (Meteor Automatic Imager and Analyzer) system is demonstrated in the paper.

Eruptive prominences and long-delay geomagnetic storms

International Nuclear Information System (INIS)

Wright, C.S.

1983-01-01

The relationship between disappearing solar fragments and geomagnetic disturbances was investigated. It is shown that long-delay storms are associated with filaments well removed from the disc centre, and particularly in the case of large filaments and prominences, the proportion of events that produce long-delay storms increases with angular distance from the centre

Optimal Transmission Line Switching under Geomagnetic Disturbances

International Nuclear Information System (INIS)

Lu, Mowen; Nagarajan, Harsha; Yamangil, Emre; Bent, Russell; Backhaus, Scott

2017-01-01

Recently, there have been increasing concerns about how geomagnetic disturbances (GMDs) impact electrical power systems. Geomagnetically-induced currents (GICs) can saturate transformers, induce hot spot heating and increase reactive power losses. These effects can potentially cause catastrophic damage to transformers and severely impact the ability of a power system to deliver power. To address this problem, we develop a model of GIC impacts to power systems that includes 1) GIC thermal capacity of transformers as a function of normal Alternating Current (AC) and 2) reactive power losses as a function of GIC. We also use this model to derive an optimization problem that protects power systems from GIC impacts through line switching, generator dispatch, and load shedding. We then employ state-of-the-art convex relaxations of AC power flow equations to lower bound the objective. We demonstrate the approach on a modified RTS96 system and UIUC 150-bus system and show that line switching is an effective means to mitigate GIC impacts. We also provide a sensitivity analysis of decisions with respect to GMD direction.

Physical processes affecting the motion of small bodies in the solar system and their application to the evolution of meteor streams

International Nuclear Information System (INIS)

Williams, I.P.

1983-01-01

In addition to planetary perturbations, the small particles which make up a meteor stream are subject to outward radiation pressure and the Poynting-Robertson effect. New particles can also be generated in a stream through being released from the nucleus of a comet. The author summarises the main physical effects, discusses models for meteor stream evolution and gives a brief account of the observational data available. (Auth.)

Ionospheric parameters as the precursors of disturbed geomagnetic conditions

Science.gov (United States)

Blagoveshchensky, D. V.; Sergeeva, M. A.; Kozlovsky, A.

2017-12-01

Geomagnetic storms and substorms are the principal elements of the disturbed Space Weather conditions. The aim of the study was to reveal the ionospheric precursors that can be used to forecast geomagnetic disturbance beginning. To study the ionospheric processes before, during and after magnetic storms and substorms data from Sodankylä Geophysical Observatory was used (geomagnetic coordinates: 64.1oN, 119.2oE). In earlier works the Main Effect (ME) was revealed for substorms. It consists of the following steps: (a) the increase of critical frequency foF2 from its quiet median before and during the substorm growth phase, four-five hours before To moment that is the moment of the expansion phase onset, (b) the foF2 decrease to the level lower than its median just after To and until Te that is the moment of the end of the expansion phase, (c) the issue ;a; repeated during the recovery phase (d) two bell-shape spikes in the cutoff frequency values foEs: first spike occurs three hours before To, second spike - during the expansion phase within the interval between To and Te. In the present work it is shown that ME manifestations can be used as precursors of magnetic substorms at high-latitudes (geomagnetic latitudes 50oN-65oN). In particular, the foF2 growth some hours before To can be used as a precursor of substorm development. The first foEs bell-shaped spike also can be used for short-term forecasting, two-three hours in advance of a substorm. Furthermore, the storms between 2008 and 2012 were studied. It was revealed that the similar ME also takes place in the case of magnetic storms but within the different time scale. More specifically, the first ME maximum in foF2 values occurs one-two days before the storm beginning and can be used as its precursor. In addition, the foEs spike takes place approximately ten hours before a storm and also can be used for the prediction of the storm beginning.

Validation of the CME Geomagnetic forecast alerts under COMESEP alert system

Science.gov (United States)

Dumbovic, Mateja; Srivastava, Nandita; Khodia, Yamini; Vršnak, Bojan; Devos, Andy; Rodriguez, Luciano

2017-04-01

An automated space weather alert system has been developed under the EU FP7 project COMESEP (COronal Mass Ejections and Solar Energetic Particles: http://comesep.aeronomy.be) to forecast solar energetic particles (SEP) and coronal mass ejection (CME) risk levels at Earth. COMESEP alert system uses automated detection tool CACTus to detect potentially threatening CMEs, drag-based model (DBM) to predict their arrival and CME geo-effectiveness tool (CGFT) to predict their geomagnetic impact. Whenever CACTus detects a halo or partial halo CME and issues an alert, DBM calculates its arrival time at Earth and CGFT calculates its geomagnetic risk level. Geomagnetic risk level is calculated based on an estimation of the CME arrival probability and its likely geo-effectiveness, as well as an estimate of the geomagnetic-storm duration. We present the evaluation of the CME risk level forecast with COMESEP alert system based on a study of geo-effective CMEs observed during 2014. The validation of the forecast tool is done by comparing the forecasts with observations. In addition, we test the success rate of the automatic forecasts (without human intervention) against the forecasts with human intervention using advanced versions of DBM and CGFT (self standing tools available at Hvar Observatory website: http://oh.geof.unizg.hr). The results implicate that the success rate of the forecast is higher with human intervention and using more advanced tools. This work has received funding from the European Commission FP7 Project COMESEP (263252). We acknowledge the support of Croatian Science Foundation under the project 6212 „Solar and Stellar Variability".

The Holocene Geomagnetic Field: Spikes, Low Field Anomalies, and Asymmetries

Science.gov (United States)

Constable, C.

2017-12-01

Our understanding of the Holocene magnetic field is constrained by individual paleomagnetic records of variable quality and resolution, composite regional secular variation curves, and low resolution global time-varying geomagnetic field models. Although spatial and temporal data coverages have greatly improved in recent years, typical views of millennial-scale secular variation and the underlying physical processes continue to be heavily influenced by more detailed field structure and short term variability inferred from the historical record and modern observations. Recent models of gyre driven decay of the geomagnetic dipole on centennial time scales, and studies of the evolution of the South Atlantic Anomaly provide one prominent example. Since 1840 dipole decay has largely been driven by meridional flux advection, with generally smaller fairly steady contributions from magnetic diffusion. The decay is dominantly associated with geomagnetic activity in the Southern Hemisphere. In contrast to the present decay, dipole strength generally grew between 1500 and 1000 BC, sustaining high but fluctuating values around 90-100 ZAm2 until after 1500 AD. Thus high dipole moments appear to have been present shortly after 1000 AD at the time of the Levantine spikes, which represent extreme variations in regional geomagnetic field strength. It has been speculated that the growth in dipole moment originated from a strong flux patch near the equatorial region at the core-mantle boundary that migrated north and west to augment the dipole strength, suggesting the presence of a large-scale anticyclonic gyre in the northern hemisphere, not totally unlike the southern hemisphere flow that dominates present day dipole decay. The later brief episodes of high field strength in the Levant may have contributed to prolonged values of high dipole strength until the onset of dipole decay in the late second millennium AD. This could support the concept of a large-scale stable flow

Evaluation of geomagnetic storm effects on the GPS derived Total Electron Content (TEC)

International Nuclear Information System (INIS)

Purohit, P K; Atulkar, Roshni; Mansoori, Azad A; Khan, Parvaiz A; Bhawre, Purushottam; Tripathi, Sharad C; Khatarkar, Prakash; Bhardwaj, Shivangi; Aslam, A M; Waheed, Malik A; Gwal, A K

2015-01-01

The geomagnetic storm represents the most outstanding example of solar wind- magnetospheric interaction, which causes global disturbances in the geomagnetic field as well as triggers ionospheric disturbances. We study the behaviour of ionospheric Total Electron Content (TEC) during the geomagnetic storms. For this investigation we have selected 47 intense geomagnetic storms (Dst ≤ -100nT) that were observed during the solar cycle 23 i.e. during 1998- 2006. We then categorized these storms into four categories depending upon their solar sources like Magnetic Cloud (MC), Co-rotating Interaction Region (CIR), SH+ICME and SH+MC. We then studied the behaviour of ionospheric TEC at a mid latitude station Usuda (36.13N, 138.36E), Japan during these storm events produced by four different solar sources. During our study we found that the smooth variations in TEC are replaced by rapid fluctuations and the value of TEC is strongly enhanced during the time of these storms belonging to all the four categories. However, the greatest enhancements in TEC are produced during those geomagnetic storms which are either caused by Sheath driven Magnetic cloud (SH+MC) or Sheath driven ICME (SH+ICME). We also derived the correlation between the TEC enhancements produced during storms of each category with the minimum Dst. We found the strongest correlation exists for the SH+ICME category followed by SH+MC, MC and finally CIR. Since the most intense storms were either caused by SH+ICME or SH+MC while the least intense storms were caused by CIR, consequently the correlation was strongest with SH+ICME and SH+MC and least with CIR. (paper)

Different geomagnetic indices as an indicator for geo-effective solar storms and human physiological state

Science.gov (United States)

Dimitrova, Svetla

2008-02-01

A group of 86 healthy volunteers were examined on each working day during periods of high solar activity. Data about systolic and diastolic blood pressure, pulse pressure, heart rate and subjective psycho-physiological complaints were gathered. MANOVA was employed to check the significance of the influence of three factors on the physiological parameters. The factors were as follows: (1) geomagnetic activity estimated by daily amplitude of H-component of the local geomagnetic field, Ap- and Dst-index; (2) gender; and (3) the presence of medication. Average values of systolic, diastolic blood pressure, pulse pressure and subjective complaints of the group were found to increase significantly with geomagnetic activity increment.

Effects of geomagnetic storm on low latitude ionospheric total ...

Indian Academy of Sciences (India)

1Department of Physics, Tripura University, Suryamaninagar, Tripura 799 022, India. ... the fact that the electro-dynamic effect of geomagnetic storms around EIA region is more effective than ... causes range of error in GPS communication.

Transequatorial magnetic flux loops on the sun: a possible new source of geomagnetic storms

Directory of Open Access Journals (Sweden)

Takao Saito

2009-11-01

Full Text Available Following the traditional way of expression, geomagnetic storms have been classified into three types; flare-type Sc storms, CH-type Sg storms, and DB-type Sc storms (Sc:sudden commencement;CH:coronal hole;g:gradual;DB:disparition brusque.We have discovered that some transequatorial loops (TEL give rise to geomagnetic storms, when the TEL explodes near the central meridian of the sun. The axial magnetic direction of the TEL can be inferred, since TELs connect sunspot groups or remnant magnetic regions between the northern and southern hemispheres. Since the axial fields tend to have a large Bz component in interplanetary space, we have examined various effects on the configuration of geomagnetic storms. Topics are proposed for future works on the TEL-type Sc storms.

A synoptic study of geomagnetic storms and related solar phenomena during 1976 through 1978

International Nuclear Information System (INIS)

Marubashi, K.

1979-01-01

An attempt has been made to identify the causes of geomagnetic storms which occurred during the three year period from 1976 through 1978. Of the 114 storms with D sub(st) = 25 investigated in this paper, 52 storms are found to be caused by corotating streams, 16 storms by solar flares, and 19 storms by compound effects of both corotating streams and flares. The causes of the remaining 27 storms could not be identified. By examining the characteristics of those solar flares which were taken to be responsible for geomagnetic storms, a semiquantitative conclusion has been obtained about the criteria for the flares which can produce magnetic storms. In addition, clear semiannual variation has been found in geomagnetic activity caused by flare-free corotating streams. (author)

Solar causes of the excitation of earth electric currents and of geomagnetic field disturbances

International Nuclear Information System (INIS)

Krivsky, L.

1977-01-01

A survey is given of the effects of solar activity on geomagnetic and geoelectric disturbances. Indexes are given showing changes in the magnetic field, the occurrence of calm geomagnetic days related to solar activity, proton solar flares and electrical currents in the high layers of the atmosphere in the polar region, powerfull solar activity and electric currents in the polar region, the time rise of shock waves in the development of proton flares and the boundaries of sector structures of the interplanetary magnetic field and its effect on the Earth. It is stated that the geoelectric and geomagnetic fields are affected by the discrete phenomena of solar activity and by the transition of the quasimagnetic sectors of interplanetary fields. (J.P.)

Real-time geomagnetic monitoring for space weather-related applications: Opportunities and challenges

Science.gov (United States)

Love, Jeffrey J.; Finn, Carol A.

2017-07-01

An examination is made of opportunities and challenges for enhancing global, real-time geomagnetic monitoring that would be beneficial for a variety of operational projects. This enhancement in geomagnetic monitoring can be attained by expanding the geographic distribution of magnetometer stations, improving the quality of magnetometer data, increasing acquisition sampling rates, increasing the promptness of data transmission, and facilitating access to and use of the data. Progress will benefit from new partnerships to leverage existing capacities and harness multisector, cross-disciplinary, and international interests.

Modeling of Thermospheric Neutral Density Variations in Response to Geomagnetic Forcing using GRACE Accelerometer Data

Science.gov (United States)

Calabia, A.; Matsuo, T.; Jin, S.

2017-12-01

The upper atmospheric expansion refers to an increase in the temperature and density of Earth's thermosphere due to increased geomagnetic and space weather activities, producing anomalous atmospheric drag on LEO spacecraft. Increased drag decelerates satellites, moving their orbit closer to Earth, decreasing the lifespan of satellites, and making satellite orbit determination difficult. In this study, thermospheric neutral density variations due to geomagnetic forcing are investigated from 10 years (2003-2013) of GRACE's accelerometer-based estimates. In order to isolate the variations produced by geomagnetic forcing, 99.8% of the total variability has been modeled and removed through the parameterization of annual, LST, and solar-flux variations included in the primary Empirical Orthogonal Functions. The residual disturbances of neutral density variations have been investigated further in order to unravel their relationship to several geomagnetic indices and space weather activity indicators. Stronger fluctuations have been found in the southern polar cap, following the dipole-tilt angle variations. While the parameterization of the residual disturbances in terms of Dst index results in the best fit to training data, the use of merging electric field as a predictor leads to the best forecasting performance. An important finding is that modeling of neutral density variations in response geomagnetic forcing can be improved by accounting for the latitude-dependent delay. Our data-driven modeling results are further compared to modeling with TIEGCM.

Revised interpretations of stable C and O patterns in carbonate rocks resulting from meteoric diagenesis

Science.gov (United States)

Swart, Peter K.; Oehlert, Amanda M.

2018-02-01

A positive correlation between the δ13C and δ18O values of carbonate rocks is a screening tool widely used to identify the overprint of meteoric diagenesis on the original isotopic composition of a sample. In particular, it has been suggested that systematic change from negative to positive δ13C and δ18O values with increasing depth in the core is an indicator of alteration within the zone of mixing between meteoric and marine waters. In this paper, we propose that such covariance is not generated within the traditionally defined mixing zone, and that positive correlations between δ13C and δ18O values in marine carbonates are not necessarily indicators of meteoric alteration. This new interpretation is based on data collected from the shallow sub-surface of the Bahamas, a region unequivocally influenced by meteoric waters to depths of at least 200 m below the current sediment-water interface. The classic interpretation of the diagenetic environments, based on changes in the δ13C and δ18O values, would suggest the maximum penetration of freshwater occurs between 65 and 100 m below seafloor. Below these depths, a strong positive covariation between the δ13C and δ18O values exists, and would traditionally be defined as the mixing zone. However, based upon known changes in sea level, the penetration of the freshwater lens extends significantly below this limit. We contend that the zone showing covariance of δ13C and δ18O values is actually altered within the freshwater lens, and not the mixing zone as previously proposed. The co-varying trend in δ13C and δ18O values is the result of diagenetic processes occurring at the interface between vadose and phreatic zones. Significantly greater rates of recrystallization and neomorphism are driven by the increased rates of oxidation of organic matter at this transition with progressively less alteration occurring with increasing depth. As sea level oscillates, the position of this interface moves through the

Day-to-Day Variability of H and Z Components of the Geomagnetic Field at the African Longitudes

OpenAIRE

Obiekezie, T. N.; Obiadazie, S. C.; Agbo, G. A.

2013-01-01

The Day-to-day variability of the geomagnetic field elements at the African longitudes has been studied for the year 1987 using geomagnetic data obtained from four different African observatories. The analysis was carried out on solar quiet days using hourly values of the Horizontal, , and vertical, , geomagnetic field values. The results of this study confirm that Sq is a very changeable phenomenon, with a strong day-to-day variation. This day-to-day variation is seen to be superimposed on m...

Advances in Residential Design Related to the Influence of Geomagnetism

Science.gov (United States)

Arnedo, Israel; Sánchez-Ostiz, Ana

2018-01-01

Since the origin of the Modern Movement, there has been a basic commitment to improving housing conditions and the well-being of occupants, especially given the prediction that 2/3 of humanity will reside in cities by 2050. Moreover, a compact model of the city with tall buildings and urban densification at this scale will be generated. Continuous constructive and technological advances have developed solid foundations on safety, energy efficiency, habitability, and sustainability in housing design. However, studies on improving the quality of life in these areas continue to be a challenge for architects and engineers. This paper seeks to contribute health-related information to the study of residential design, specifically the influence of the geomagnetic field on its occupants. After compiling information on the effects of geomagnetic fields from different medical studies over 23 years, a case study of a 16-story high-rise building is presented, with the goal of proposing architectural design recommendations for long-term occupation in the same place. The purpose of the present work is three-fold: first, to characterize the geomagnetic field variability of buildings; second, to identify the causes and possible related mechanisms; and third, to define architectural criteria on the arrangement of uses and constructive elements for housing. PMID:29473902

A global geomagnetic model based on historical and paleomagnetic data

Science.gov (United States)

Arneitz, P.; Leonhardt, R.; Fabian, K.

2015-12-01

Two main types of data are available to reconstruct the temporal and spatial geomagnetic field evolution. Historical instrumental measurements (direct data) extend from present day to the late Middle Age, and, prior the 19th century, consist mainly of declination values. Further back in the past, field reconstructions rely exclusively on the magnetization acquired by archaeological artefacts and rocks or sediments (indirect data). The major challenges for a reliable inversion approach are the inhomogeneous data distribution, the highly variable data quality, and inconsistent quality parameters. Available historical, archeomagnetic and volcanic records have been integrated into a single database together with corresponding metadata. This combination of compilations enables a joint evaluation of geomagnetic field records from different origins. In particular, data reliability and quality of indirect records are investigated using a detailed comparison with their direct counterparts. The collection forms the basis for combined inverse modeling of the geomagnetic field evolution. The iterative Bayesian inversion approach targets the implementation of reliable error treatments, which allow to combine data from different sources. Furthermore, a verification method scrutinizing the limitations of the applied inversion scheme and the used datasets is developed. Here, we will present strategies for the integration of different data types into the modeling procedure. The obtained modeling results and their validity will be discussed.

Advances in Residential Design Related to the Influence of Geomagnetism

Directory of Open Access Journals (Sweden)

Francisco Glaria

2018-02-01

Full Text Available Since the origin of the Modern Movement, there has been a basic commitment to improving housing conditions and the well-being of occupants, especially given the prediction that 2/3 of humanity will reside in cities by 2050. Moreover, a compact model of the city with tall buildings and urban densification at this scale will be generated. Continuous constructive and technological advances have developed solid foundations on safety, energy efficiency, habitability, and sustainability in housing design. However, studies on improving the quality of life in these areas continue to be a challenge for architects and engineers. This paper seeks to contribute health-related information to the study of residential design, specifically the influence of the geomagnetic field on its occupants. After compiling information on the effects of geomagnetic fields from different medical studies over 23 years, a case study of a 16-story high-rise building is presented, with the goal of proposing architectural design recommendations for long-term occupation in the same place. The purpose of the present work is three-fold: first, to characterize the geomagnetic field variability of buildings; second, to identify the causes and possible related mechanisms; and third, to define architectural criteria on the arrangement of uses and constructive elements for housing.

Protection of power transformers against geomagnetically induced currents

Directory of Open Access Journals (Sweden)

Gurevich Vladimir

2011-01-01

Full Text Available The article examines the problem of saturation and failure of power transformers under geomagnetically induced currents and currents of the E3 component of high-altitude nuclear explosions. It also describes a special protective relay reacting on DC component in the transformer neutral current.

Geomagnetic core field models in the satellite era

DEFF Research Database (Denmark)

Lesur, Vincent; Olsen, Nils; Thomson, Alan W. P.

2011-01-01

After a brief review of the theoretical basis and difficulties that modelers are facing, we present three recent models of the geomagnetic field originating in the Earth’s core. All three modeling approaches are using recent observatory and near-Earth orbiting survey satellite data. In each case...

Geological support for the Umbrella Effect as a link between geomagnetic field and climate

Science.gov (United States)

Kitaba, Ikuko; Hyodo, Masayuki; Nakagawa, Takeshi; Katoh, Shigehiro; Dettman, David L.; Sato, Hiroshi

2017-01-01

The weakening of the geomagnetic field causes an increase in galactic cosmic ray (GCR) flux. Some researchers argue that enhanced GCR flux might lead to a climatic cooling by increasing low cloud formation, which enhances albedo (umbrella effect). Recent studies have reported geological evidence for a link between weakened geomagnetic field and climatic cooling. However, more work is needed on the mechanism of this link, including whether the umbrella effect is playing a central role. In this research, we present new geological evidence that GCR flux change had a greater impact on continental climate than on oceanic climate. According to pollen data from Osaka Bay, Japan, the decrease in temperature of the Siberian air mass was greater than that of the Pacific air mass during geomagnetic reversals in marine isotope stages (MIS) 19 and 31. Consequently, the summer land-ocean temperature gradient was smaller, and the summer monsoon was weaker. Greater terrestrial cooling indicates that a reduction of insolation is playing a key role in the link between the weakening of the geomagnetic field and climatic cooling. The most likely candidate for the mechanism seems to be the increased albedo of the umbrella effect. PMID:28091595

Geophysical variables and behavior: XXI. Geomagnetic variation as possible enhancement stimuli for UFO reports preceding earthtremors.

Science.gov (United States)

Persinger, M A

1985-02-01

The contribution of geomagnetic variation to the occurrence of UFORs (reports of UFOs) within the New Madrid States during the 6-mo. increments before increases in the numbers of IV-V or less intensity earthquakes within the central USA was determined. Although statistically significant zero-order correlations existed between measures of earthquakes, UFORs and geomagnetic variability, the association between the latter two deteriorated markedly when their shared variance with earthquakes was held constant. These outcomes are compatible with the hypothesis that geomagnetic variability (or phenomena associated with it) may enhance UFORs but only if tectonic stress and strain are increasing within the region.

Palaeomagnetic evidence for the persistence or recurrence of geomagnetic main field anomalies in the South Atlantic

Science.gov (United States)

Shah, Jay; Koppers, Anthony A. P.; Leitner, Marko; Leonhardt, Roman; Muxworthy, Adrian R.; Heunemann, Christoph; Bachtadse, Valerian; Ashley, Jack A. D.; Matzka, Jürgen

2016-05-01

We present a dataset of a full-vector palaeomagnetic study of Late Pleistocene lavas from the island Tristan da Cunha in the South Atlantic Ocean. The current day geomagnetic field intensity in this region is approximately 25 μT, compared to an expected value of ∼43 μT; this phenomenon is known as the South Atlantic geomagnetic Anomaly (SAA). Geomagnetic field models extending back to the last 10 ka find no evidence for this being a persistent feature of the geomagnetic field, albeit, all models are constructed from data which is particularly sparse in the southern hemisphere. New 40Ar/39Ar incremental heating dating indicates the studied lavas from Tristan da Cunha extruded between 90 and 46 ka. Palaeointensity estimations of eight lava flows made using the Thellier method yield an average palaeointensity of 18 ± 6 μT and virtual axial dipole moment (VADM) of 3.1 ± 1.2 ×1022 Am2. The lava flows demonstrate four time intervals comparable to the present day SAA, where the average VADM of the Tristan da Cunha lavas is weaker than the global VADM average. This suggests a persistent or recurring low intensity anomaly to the main geomagnetic field similar to the SAA existed in the South Atlantic between 46 and 90 ka.

Evidence for a new geomagnetic jerk in 2014

DEFF Research Database (Denmark)

Torta, J. Miquel; Pavón-Carrasco, Francisco Javier; Marsal, Santiago

2015-01-01

The production of quasi-definitive data at Ebre observatory has enabled us to detect a new geomagnetic jerk in early 2014. This has been confirmed by analyzing data at several observatories in the European-African and Western Pacific-Australian sectors in the classical fashion of looking for the ...

The Ranges Of Subauroral Geomagnetic Field Elements | Rabiu ...

African Journals Online (AJOL)

Nigeria Journal of Pure and Applied Physics ... An anomaly in seasonal response of range at high solar activity is observed on disturbed condition. ... apart from the anomaly - maintain the order e>j>d of seasonal variation which is in agreement with the popular equinoctial maximum observed in geomagnetic activity.

Long-term trends of foF2 independent of geomagnetic activity

Directory of Open Access Journals (Sweden)

A. D. Danilov

Full Text Available A detailed analysis of the foF2 data at a series of ionospheric stations is performed to reveal long-term trends independent of the long-term changes in geomagnetic activity during the recent decades (nongeomagnetic trends. The method developed by the author and published earlier is used. It is found that the results for 21 out of 23 stations considered agree well and give a relative nongeomagnetic trend of -0.0012 per year (or an absolute nongeomagnetic trend of about -0.012 MHz per year for the period between 1958 and the mid-nineties. The trends derived show no dependence on geomagnetic latitude or local time, a fact confirming their independence of geomagnetic activity. The consideration of the earlier period (1948–1985 for a few stations for which the corresponding data are available provides significantly lower foF2 trends, the difference between the later and earlier periods being a factor of 1.6. This is a strong argument in favor of an anthropogenic nature of the trends derived.Key words. Ionosphere (ionosphere-atmosphere interactions; ionospheric disturbances; mid-latitude ionosphere

A Carrington-like geomagnetic storm observed in the 21st century

Directory of Open Access Journals (Sweden)

Cid Consuelo

2015-01-01

Full Text Available In September 1859 the Colaba observatory measured the most extreme geomagnetic disturbance ever recorded at low latitudes related to solar activity: the Carrington storm. This paper describes a geomagnetic disturbance case with a profile extraordinarily similar to the disturbance of the Carrington event at Colaba: the event on 29 October 2003 at Tihany magnetic observatory in Hungary. The analysis of the H-field at different locations during the “Carrington-like” event leads to a re-interpretation of the 1859 event. The major conclusions of the paper are the following: (a the global Dst or SYM-H, as indices based on averaging, missed the largest geomagnetic disturbance in the 29 October 2003 event and might have missed the 1859 disturbance, since the large spike in the horizontal component (H of terrestrial magnetic field depends strongly on magnetic local time (MLT; (b the main cause of the large drop in H recorded at Colaba during the Carrington storm was not the ring current but field-aligned currents (FACs; and (c the very local signatures of the H-spike imply that a Carrington-like event can occur more often than expected.

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.

Geomagnetically conjugate observations of ionospheric and thermospheric variations accompanied with a midnight brightness wave at low latitudes

Science.gov (United States)

Fukushima, D.; Shiokawa, K.; Otsuka, Y.; Kubota, M.; Yokoyama, T.; Nishioka, M.; Komonjinda, S.; Yatini, C. Y.

2014-12-01

A midnight brightness wave (MBW) is the phenomenon that the OI (630-nm) airglow enhancement propagates poleward once at local midnight. In this study, we first conducted geomagnetically conjugate observations of 630nm airglow for an MBW at conjugate stations. An airglow enhancement which is considered to be an MBW was observed in the 630-nm airglow images at Kototabang, Indonesia (geomagnetic latitude (MLAT): 10.0S) at around local midnight from 1540 to 1730 UT (from 2240 to 2430 LT) on 7 February 2011. This MBW was propagating south-southwestward, which is geomagnetically poleward, with a velocity of 290 m/s. However, similar wave was not observed in the 630-nm airglow images at Chiang Mai, Thailand (MLAT: 8.9N), which is close to being conjugate point of Kototabang. This result indicates that the MBW does not have geomagnetic conjugacy. We simultaneously observed thermospheric neutral winds observed by a co-located Fabry-Perot interferometer at Kototabang. The observed meridional winds turned from northward (geomagnetically equatorward) to southward (geomagnetically poleward) just before the MBW was observed. The bottomside ionospheric heights observed by ionosondes rapidly decreased at Kototabang and slightly increased at Chiang Mai simultaneously with the MBW passage. In the presentation, we discuss the MBW generation by the observed poleward neutral winds at Kototabang, and the cause of the coinciding small height increase at Chiang Mai by the polarization electric field inside the observed MBW at Kototabang.

A long-term geomagnetic excursion from Plio-Pleistocene sediments in Java

Science.gov (United States)

Hyodo, Masayuki; Sunata, Wahyu; Susanto, Eko E.

1992-06-01

Duplicate records of a geomagnetic excursion at two sites separated by 200 km in Java, Indonesia, are reported. The existence of a large-scale wing of declination between the Olduvai and Jaramillo event is revealed. The field directions in reverse polarity show a gradual clockwise swing to almost west-pointing directions, followed by a rapid return to south-pointing directions. At both sites, the declinations have maximum deflection more than 70 deg from the axial dipole field direction, and the inclinations remain low during the swing. An upward-pointing eccentric radial dipole model rather than a downward-pointing one seems plausible to explain the geomagnetic behavior during the excursion.

Geomagnetically conjugate observation of plasma bubbles and thermospheric neutral winds at low latitudes

Science.gov (United States)

Fukushima, D.; Shiokawa, K.; Otsuka, Y.; Nishioka, M.; Kubota, M.; Tsugawa, T.; Nagatsuma, T.; Komonjinda, S.; Yatini, C. Y.

2015-03-01

This is the first paper that reports simultaneous observations of zonal drift of plasma bubbles and the thermospheric neutral winds at geomagnetically conjugate points in both hemispheres. The plasma bubbles were observed in the 630 nm nighttime airglow images taken by using highly sensitive all-sky airglow imagers at Kototabang, Indonesia (geomagnetic latitude (MLAT): 10.0°S), and Chiang Mai, Thailand (MLAT: 8.9°N), which are nearly geomagnetically conjugate stations, for 7 h from 13 to 20 UT (from 20 to 03 LT) on 5 April 2011. The bubbles continuously propagated eastward with velocities of 100-125 m/s. The 630 nm images at Chiang Mai and those mapped to the conjugate point of Kototabang fit very well, which indicates that the observed plasma bubbles were geomagnetically connected. The eastward thermospheric neutral winds measured by two Fabry-Perot interferometers were 70-130 m/s at Kototabang and 50-90 m/s at Chiang Mai. We compared the observed plasma bubble drift velocity with the velocity calculated from the observed neutral winds and the model conductivity, to investigate the F region dynamo contribution to the bubble drift velocity. The estimated drift velocities were 60-90% of the observed velocities of the plasma bubbles, suggesting that most of the plasma bubble velocity can be explained by the F region dynamo effect.

A study of the effect of geomagnetic storms on low latitude whistlers

International Nuclear Information System (INIS)

Rao, Manoranjan; Somayajulu, V.V.; Dikshit, S.K.

1974-01-01

This paper presents the results of a detailed study of the influence of geomagnetic storms on low latitude whistlers recorded on ground. Studied in detail is the effect of the geomagnetic storm of March 6-10, 1970 on whistlers recorded at Gulmarg (Geomagnetic coordinates: 24 0 10'N; 147 0 24'E); results of analysis for the earlier storm of January 13-15, 1967 are included for comparison. Some of the important results of the present study are: (i) Both the whistler occurrence rate and dispersion increase simultaneously with Kp, (ii) During the decaying phase of the storm, changes in occurrence rate and in dispersion lag behind those in Kp, (iii) There is an indication of the existence of a cross-over latitude where tube contents may not change appreciably during storm periods, (iv) Multipath whistlers are observed only during disturbed conditions, (v) Duct life ranges between several hours to few days and (vi) Maximum number of ducts is observed during the main and recovery phases of the storm. (auth.)

Response of the middle atmosphere to the geomagnetic storm of November 2004

Science.gov (United States)

Hocke, Klemens

2017-02-01

Ozone and temperature profiles of the satellite microwave limb sounder Aura/MLS are used for the derivation of the middle atmospheric response to the geomagnetic superstorm of 9 November 2004. We find a destruction of the tertiary ozone layer at 0.022 hPa (77 km) in the northern winter hemisphere lasting for about one week. This effect is surely due to the solar proton event (SPE) of November 2004. At the same time, the zonal mean temperature is enhanced by 5-10 K in the northern polar mesosphere. On the other hand, the zonal mean temperature is decreased by 5-10 K in the northern polar stratosphere. We do not think that the strong temperature perturbations are directly related to the SPE. It seems that the polar vortex was moved by the geomagnetic storm, and this vortex movement caused the strong temperature variations in the zonal mean. However, internal variability of temperature in the polar middle atmosphere in winter without any significant link to the geomagnetic storm cannot be excluded.

Hausdorff-Based RC and IESIL Combined Positioning Algorithm for Underwater Geomagnetic Navigation

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Lin Yi

2010-01-01

Full Text Available This paper presents a primitive solution with novel scheme and algorithm for Underwater geoMagnetic Navigation (UMN, which now occurs as the hot-point in the research field of navigation. UMN as an independent or supplementary technique can theoretically supply accurate locations for marine vehicles, but in practice there are plenty of restrictions for UMN's application (e.g., geomagnetic daily variation. After analysis of the theoretical model of geomagnetic positioning in the correlation-matching mode from the viewpoint of pattern recognition, this paper proposed an appropriate matching scenario and a combined positioning algorithm for UMN. The subalgorithm of Hausdorff-based Relative Correlation (RC corresponding to the pattern classification module implements the coarse positioning, and the subalgorithm of Isograms Equidistance-Segmenting theIntersection Lines (IESILs associated with the module of feature extraction continues the fine positioning. The experiments based on the simulation platform and the real-surveyed data both validate the new algorithm, and its efficiency and accuracy are also discussed. It can be concluded that the work introduced in this paper gives an initial and real validation of UMN's potentiality.

Resolving issues concerning Eskdalemuir geomagnetic hourly values

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S. Macmillan

2011-02-01

Full Text Available The hourly values of the geomagnetic field from 1911 to 1931 derived from measurements made at Eskdalemuir observatory in the UK, and available online from the World Data Centre for Geomagnetism at http://www.wdc.bgs.ac.uk/, have now been corrected. Previously they were 2-point averaged and transformed from the original north, east and vertical down values in the tables in the observatory yearbooks. This paper documents the course of events from discovering the post-processing done to the data to the final resolution of the problem. As it was through the development of a new index, the Inter-Hour Variability index, that this post-processing came to light, we provide a revised series of this index for Eskdalemuir and compare it with that from another European observatory. Conclusions of studies concerning long-term magnetic field variability and inferred solar variability, whilst not necessarily consistent with one another, are not obviously invalidated by the incorrect hourly values from Eskdalemuir. This series of events illustrates the challenges that lie ahead in removing any remaining errors and inconsistencies in the data holdings of different World Data Centres.

Geomagnetic control of polar mesosphere summer echoes

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J. Bremer

2000-02-01

Full Text Available Using observations with the ALOMAR SOUSY radar near Andenes (69.3°N, 16.0°E from 1994 until 1997 polar mesosphere summer echoes (PMSE have been investigated in dependence on geomagnetic K indices derived at the Auroral Observatory Tromsø (69.66°N, 18.94°E. During night-time and morning hours a significant correlation between the signal-to-noise ratio (SNR of the radar results and the geomagnetic K indices could be detected with a maximum correlation near midnight. The correlation becomes markedly smaller in the afternoon and early evening hours with a minimum near 17 UT. This diurnal variation is in reasonable agreement with riometer absorption at Ivalo (68.55°N, 27.28°E and can be explained by the diurnal variation of ionization due to precipitating high energetic particles. Therefore, a part of the diurnal PMSE variation is caused by this particle precipitation. The variability of the solar EUV variation, however, has no significant influence on the PMSE during the observation period.Keywords: Ionosphere (auroral ionosphere - Magnetospheric physics (energetic particles, precipitating - Radio science (remote sensing

Wind response in the lower thermosphere to the geomagnetic storm on March, 1989

International Nuclear Information System (INIS)

Kazimirovskij, Eh.S.; Vergasova, G.V.

1991-01-01

The horizontal wind response in the ionospheric D region above Irkutsk to the geomagnetic storm on March 13, 1989 is studied. The geomagnetic storm response is expressed through a stability loss of the wind system, a great speed increase of the meridional and zonal wind, in particular, and their dispersions, respectively, as well as changes in the semidaily tidal phase. The proof of the fact that the Earth magnetic field disturbances destabilize the system of horizontal winds in the lower ionosphere is given

Geomagnetism and Aeronomy activities in Italy during IGY, 1957/58

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Lucilla Alfonsi

2009-06-01

Full Text Available In 2007 several events were organized to celebrate the fiftieth anniversary of the International Geophysical Year
(IGY, 1957-1958. The celebrations will last until 2009 and are taking place within different contexts: the International
Polar Year (IPY, the International Heliophysical Year (IHY, the electronic Geophysical Year (eGY
and the International Year of Planet Earth (IYPE.
IGY offered a very appropriate and timely occasion to undertake a series of coordinated observations of various
geophysical phenomena all over the globe. Italy took part in the broad international effort stimulated by IGY. In
fact, Italy participated in observations and studies in many of the proposed scientific areas, in particular Geomagnetism
and Aeronomy. The Istituto Nazionale di Geofisica (ING started the installation of observatories,
and updated and ensured continuous recording of geophysical observations. Geomagnetism, ionospheric
physics, seismology, and other geophysical disciplines, were advanced. Although much of the work was undertaken
in Italy, some attention was also devoted to other areas of the world, in particular Antarctica, where Italy
participated in seismological observations. This paper gives a summary of the Geomagnetism and Ionospheric
Physics activities within IGY. Furthermore, we highlight the importance of this historical event and its outcomes
for the improvement of geophysical observations and the post-IGY growth of scientific investigations in Italy.

Archaeomagnetic Dating in Europe Using a Global Geomagnetic Field Model

Science.gov (United States)

Lodge, A.; Suttie, N.; Holme, R.; Shaw, J.; Hill, M. J.; Linford, P.

2009-12-01

Using up-to-date archaeomagnetic data from Europe and CALS7K.2 as an apriori model, we produce a global geomagnetic field model to be used for archaeomagnetic dating in Europe. More details on the modelling process will be presented elsewhere (in session GP12, abstract: Geophysical insights from archaeomagnetic dating). Here we apply the global geomagnetic field model to a series of test cases from both recently published data and unpublished data to demonstrate its application to archaeomagnetic dating. We compare the results produced using our model with those from the spherical cap harmonic model, SCHA.DIF.3K (Pavón-Carrasco et al., 2009), the global geomagnetic field model, ARCH3K.1 (Korte et al., 2009) and those produced using the palaeosecular variation curves generated using Bayesian statistics (Lanos, 2004). We include examples which emphasise the importance of using three component data (declination, inclination and intensity) to produce an improved archaeomagnetic date. In addition to the careful selection of an appropriate model for archaeomagnetic dating, the choice of errors on the model curves is vital for providing archaeologists with an age range of possible dates. We discuss how best to constrain the errors on the model curves and alternative ways to the mathematical method of Lanos (2004) for producing an archaeomagnetic date for archaeologists.

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

Dynamic Responses of the Earth's Outer Core to Assimilation of Observed Geomagnetic Secular Variation

Science.gov (United States)

Kuang, Weijia; Tangborn, Andrew

2014-01-01

Assimilation of surface geomagnetic observations and geodynamo models has advanced very quickly in recent years. However, compared to advanced data assimilation systems in meteorology, geomagnetic data assimilation (GDAS) is still in an early stage. Among many challenges ranging from data to models is the disparity between the short observation records and the long time scales of the core dynamics. To better utilize available observational information, we have made an effort in this study to directly assimilate the Gauss coefficients of both the core field and its secular variation (SV) obtained via global geomagnetic field modeling, aiming at understanding the dynamical responses of the core fluid to these additional observational constraints. Our studies show that the SV assimilation helps significantly to shorten the dynamo model spin-up process. The flow beneath the core-mantle boundary (CMB) responds significantly to the observed field and its SV. The strongest responses occur in the relatively small scale flow (of the degrees L is approx. 30 in spherical harmonic expansions). This part of the flow includes the axisymmetric toroidal flow (of order m = 0) and non-axisymmetric poloidal flow with m (is) greater than 5. These responses can be used to better understand the core flow and, in particular, to improve accuracies of predicting geomagnetic variability in future.

Geomagnetic imprinting predicts spatio-temporal variation in homing migration of pink and sockeye salmon

Science.gov (United States)

Putman, Nathan F.; Jenkins, Erica S.; Michielsens, Catherine G. J.; Noakes, David L. G.

2014-01-01

Animals navigate using a variety of sensory cues, but how each is weighted during different phases of movement (e.g. dispersal, foraging, homing) is controversial. Here, we examine the geomagnetic and olfactory imprinting hypotheses of natal homing with datasets that recorded variation in the migratory routes of sockeye (Oncorhynchus nerka) and pink (Oncorhynchus gorbuscha) salmon returning from the Pacific Ocean to the Fraser River, British Columbia. Drift of the magnetic field (i.e. geomagnetic imprinting) uniquely accounted for 23.2% and 44.0% of the variation in migration routes for sockeye and pink salmon, respectively. Ocean circulation (i.e. olfactory imprinting) predicted 6.1% and 0.1% of the variation in sockeye and pink migration routes, respectively. Sea surface temperature (a variable influencing salmon distribution but not navigation, directly) accounted for 13.0% of the variation in sockeye migration but was unrelated to pink migration. These findings suggest that geomagnetic navigation plays an important role in long-distance homing in salmon and that consideration of navigation mechanisms can aid in the management of migratory fishes by better predicting movement patterns. Finally, given the diversity of animals that use the Earth's magnetic field for navigation, geomagnetic drift may provide a unifying explanation for spatio-temporal variation in the movement patterns of many species. PMID:25056214

Application of the SP algorithm to the INTERMAGNET magnetograms of the disturbed geomagnetic field

Science.gov (United States)

Sidorov, R. V.; Soloviev, A. A.; Bogoutdinov, Sh. R.

2012-05-01

The algorithmic system developed in the Laboratory of Geoinformatics at the Geophysical Center, Russian Academy of Sciences, which is intended for recognizing spikes on the magnetograms from the global network INTERMAGNET provides the possibility to carry out retrospective analysis of the magnetograms from the World Data Centers. Application of this system to the analysis of the magnetograms allows automating the job of the experts-interpreters on identifying the artificial spikes in the INTERMAGNET data. The present paper is focused on the SP algorithm (abbreviated from SPIKE) which recognizes artificial spikes on the records of the geomagnetic field. Initially, this algorithm was trained on the magnetograms of 2007 and 2008, which recorded the quiet geomagnetic field. The results of training and testing showed that the algorithm is quite efficient. Applying this method to the problem of recognizing spikes on the data for periods of enhanced geomagnetic activity is a separate task. In this short communication, we present the results of applying the SP algorithm trained on the data of 2007 to the INTERMAGNET magnetograms for 2003 and 2005 sampled every minute. This analysis shows that the SP algorithm does not exhibit a worse performance if applied to the records of a disturbed geomagnetic field.

A study of solar and interplanetary parameters of CMEs causing major geomagnetic storms during SC 23

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C. Oprea

2013-08-01

Full Text Available In this paper we analyse 25 Earth-directed and strongly geoeffective interplanetary coronal mass ejections (ICMEs which occurred during solar cycle 23, using data provided by instruments on SOHO (Solar and Heliospheric Observatory, ACE (Advanced Composition Explorer and geomagnetic stations. We also examine the in situ parameters, the energy transfer into magnetosphere, and the geomagnetic indexes. We compare observed travel times with those calculated by observed speeds projected into the plane of the sky and de-projected by a simple model. The best fit was found with the projected speeds. No correlation was found between the importance of a flare and the geomagnetic Dst (disturbance storm time index. By comparing the in situ parameters with the Dst index we find a strong connection between some of these parameters (such as Bz, Bs · V and the energy transfer into the magnetosphere with the strength of the geomagnetic storm. No correlation was found with proton density and plasma temperature. A superposed epoch analysis revealed a strong dependence of the Dst index on the southward component of interplanetary magnetic field, Bz, and to the Akasofu coupling function, which evaluates the energy transfer between the ICME and the magnetosphere. The analysis also showed that the geomagnetic field at higher latitudes is disturbed before the field around the Earth's equator.

Space weather and dangerous phenomena on the Earth: principles of great geomagnetic storms forcasting by online cosmic ray data

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L. I. Dorman

2005-11-01

Full Text Available According to NOAA space weather scales, geomagnetic storms of scales G5 (3-h index of geomagnetic activity Kp=9, G4 (Kp=8 and G3 (Kp=7 are dangerous for satellites, aircrafts, and even for technology on the ground (influence on power systems, on spacecraft operations, on HF radio-communications and others. We show on the basis of statistical data, that these geomagnetic storms, mostly accompanied by cosmic ray (CR Forbush-decreases, are also dangerous for people's health on spacecraft and on the ground (increasing the rate of myocardial infarctions, brain strokes and car accident road traumas. To prevent these serious damages it is very important to forecast dangerous geomagnetic storms. Here we consider the principles of using CR measurements for this aim: to forecast at least 10-15h before the sudden commencement of great geomagnetic storms accompanied by Forbush-decreases, by using neutron monitor muon telescope worldwide network online hourly data. We show that for this forecast one may use the following features of CR intensity variations connected with geomagnetic storms accompanied by Forbush-decreases: 1 CR pre-increase, 2 CR pre-decrease, 3 CR fluctuations, 4 change in the 3-D CR anisotropy.

Interactions of meteoric smoke particles with sulphuric acid in the Earth's stratosphere

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R. W. Saunders

2012-05-01

Full Text Available Nano-sized meteoric smoke particles (MSPs with iron-magnesium silicate compositions, formed in the upper mesosphere as a result of meteoric ablation, may remove sulphuric acid from the gas-phase above 40 km and may also affect the composition and behaviour of supercooled H₂SO₄-H₂O droplets in the global stratospheric aerosol (Junge layer.

This study describes a time-resolved spectroscopic analysis of the evolution of the ferric (Fe³⁺ ion originating from amorphous ferrous (Fe²⁺-based silicate powders dissolved in varying Wt % sulphuric acid (30–75 % solutions over a temperature range of 223–295 K. Complete dissolution of the particles was observed under all conditions. The first-order rate coefficient for dissolution decreases at higher Wt % and lower temperature, which is consistent with the increased solution viscosity limiting diffusion of H₂SO₄ to the particle surfaces. Dissolution under stratospheric conditions should take less than a week, and is much faster than the dissolution of crystalline Fe²⁺ compounds.

The chemistry climate model UMSLIMCAT (based on the UKMO Unified Model was then used to study the transport of MSPs through the middle atmosphere. A series of model experiments were performed with different uptake coefficients. Setting the concentration of 1.5 nm radius MSPs at 80 km to 3000 cm⁻³ (based on rocket-borne charged particle measurements, the model matches the reported Wt % Fe values of 0.5–1.0 in Junge layer sulphate particles, and the MSP optical extinction between 40 and 75 km measured by a satellite-borne spectrometer, if the global meteoric input rate is about 20 tonnes per day. The model indicates that an uptake coefficient ≥0.01 is required to account for the observed two orders of magnitude depletion of H₂SO₄ vapour above 40 km.

Radar observations of Taurid complex meteor showers in 2003: activity and mass distribution

Czech Academy of Sciences Publication Activity Database

Pecina, Petr; Pecinová, Drahomíra; Porubčan, V.; Toth, J.

2005-01-01

Roč. 95, 1-4 (2005), s. 681-688 ISSN 0167-9295. [Meteoroids 2004. London, Ontario, 16.08.2004-20.08.2004] R&D Projects: GA ČR GA205/03/1405 Institutional research plan: CEZ:AV0Z1003909 Keywords : Taurid complex * meteor showers * activity Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.975, year: 2005

Evaluation of geomagnetic field models using magnetometer measurements for satellite attitude determination system at low earth orbits: Case studies

Science.gov (United States)

Cilden-Guler, Demet; Kaymaz, Zerefsan; Hajiyev, Chingiz

2018-01-01

In this study, different geomagnetic field models are compared in order to study the errors resulting from the representation of magnetic fields that affect the satellite attitude system. For this purpose, we used magnetometer data from two Low Earth Orbit (LEO) spacecraft and the geomagnetic models IGRF-12 (Thébault et al., 2015) and T89 (Tsyganenko, 1989) models to study the differences between the magnetic field components, strength and the angle between the predicted and observed vector magnetic fields. The comparisons were made during geomagnetically active and quiet days to see the effects of the geomagnetic storms and sub-storms on the predicted and observed magnetic fields and angles. The angles, in turn, are used to estimate the spacecraft attitude and hence, the differences between model and observations as well as between two models become important to determine and reduce the errors associated with the models under different space environment conditions. We show that the models differ from the observations even during the geomagnetically quiet times but the associated errors during the geomagnetically active times increase. We find that the T89 model gives closer predictions to the observations, especially during active times and the errors are smaller compared to the IGRF-12 model. The magnitude of the error in the angle under both environmental conditions was found to be less than 1°. For the first time, the geomagnetic models were used to address the effects of the near Earth space environment on the satellite attitude.

K-type geomagnetic index nowcast with data quality control

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René Warnant

2011-07-01

Full Text Available

A nowcast system for operational estimation of a proxy K-type geomagnetic index is presented. The system is based on a fully automated computer procedure for real-time digital magnetogram data acquisition that includes screening of the dataset and removal of the outliers, estimation of the solar regular variation (SR of the geomagnetic field, calculation of the index, and issuing of an alert if storm-level activity is indicated. This is a time-controlled (rather than event-driven system that delivers the regular output of: the index value, the estimated quality flag, and eventually, an alert. The novel features provided are first, the strict control of the data input and processing, and second, the increased frequency of production of the index (every 1 h. Such quality control and increased time resolution have been found to be of crucial importance for various applications, e.g. ionospheric monitoring, that are of particular interest to us and to users of our service. The nowcast system operability, accuracy and precision have been tested with instantaneous measurements from recent years. A statistical comparison between the nowcast and the definitive index values shows that the average root-mean-square error is smaller than 1 KU. The system is now operational at the site of the Geophysical Centre of the Royal Meteorological Institute in Dourbes (50.1ºN, 4.6ºE, and it is being used for alerting users when geomagnetic storms take place.

Remagnetization of lava flows spanning the last geomagnetic reversal

Science.gov (United States)

Vella, Jérôme; Carlut, Julie; Valet, Jean-Pierre; Goff, Maxime Le; Soler, Vicente; Lopes, Fernando

2017-08-01

Large directional changes of remanent magnetization within lava flows that cooled during geomagnetic reversals have been reported in several studies. A geomagnetic scenario implies extremely rapid geomagnetic changes of several degrees per day, thus difficult to reconcile with the rate of the earth's core liquid motions. So far, no complete rock magnetic model provides a clear explanation. We revisited lava flows sandwiched between an underlying reverse and an overlying normal polarity flow marking the last reversal in three distinct volcanic sequences of the La Palma Island (Canary archipelago, Spain) that are characterized by a gradual evolution of the direction of their remanent magnetization from bottom to top. Cleaning efficiency of thermal demagnetization was not improved by very rapid heating and cooling rates as well as by continuous demagnetization using a Triaxe magnetometer. We did not observe partial self-reversals and minor changes in magnetic grain sizes are not related to the within-flow directional changes. Microscopic observations indicate poor exsolution, which suggests post-cooling thermochemical remagnetization processes. This scenario is strongly reinforced by laboratory experiments that show large resistance to thermal demagnetization when thermoremanence was acquired over a long time period. We speculate that in the present situation exsolution was reactivated during in field reheating and yielded formation of new magnetite, yet magnetic domain state rearrangements could also play a role. Initial reheating when the overlying flow took place, albeit moderate (less than 200-300 °C), was enough to produce overlying components with significantly higher unblocking temperatures.

Towards a fully self-consistent inversion combining historical and paleomagnetic data for geomagnetic field reconstructions

Science.gov (United States)

Arneitz, P.; Leonhardt, R.; Fabian, K.; Egli, R.

2017-12-01

Historical and paleomagnetic data are the two main sources of information about the long-term geomagnetic field evolution. Historical observations extend to the late Middle Ages, and prior to the 19th century, they consisted mainly of pure declination measurements from navigation and orientation logs. Field reconstructions going back further in time rely solely on magnetization acquired by rocks, sediments, and archaeological artefacts. The combined dataset is characterized by a strongly inhomogeneous spatio-temporal distribution and highly variable data reliability and quality. Therefore, an adequate weighting of the data that correctly accounts for data density, type, and realistic error estimates represents the major challenge for an inversion approach. Until now, there has not been a fully self-consistent geomagnetic model that correctly recovers the variation of the geomagnetic dipole together with the higher-order spherical harmonics. Here we present a new geomagnetic field model for the last 4 kyrs based on historical, archeomagnetic and volcanic records. The iterative Bayesian inversion approach targets the implementation of reliable error treatment, which allows different record types to be combined in a fully self-consistent way. Modelling results will be presented along with a thorough analysis of model limitations, validity and sensitivity.

Geomagnetic response to sudden expansions of the magnetosphere

International Nuclear Information System (INIS)

Araki, Tohru; Nagano, Hiroshi

1988-01-01

The geomagnetic response to five successive sudden expansions of the magnetosphere was examined by the use of magnetic data observed on the ground and by satellites. At the geosynchronous orbit between 0800 and 1100 LT the magnetic field component parallel to Earth's rotation axis decreased successively. The amplitude and the fall time of each decrease were 20-30 nT and 2.5-3.5 min, respectively. The decrease was propagated about 10 min later to the distance of about 31 R E from Earth in the antisunward direction, indicating propagation speed of about 300 km/s. The H component of ground magnetograms from low-latitude stations showed decreases with waveform similar to that at the geosynchronous orbit, but each decrease at the dayside equator was greatly enhanced and preceded by a short small positive impulse. Each of the corresponding geomagnetic variations at high latitude stations consisted of two successive sharp pulses of opposite sense with 2-3 min duration. The dominant component and the sense of these high-latitude pulses were highly dependent upon local time and latitude. The distribution of equivalent ionospheric current arrows for each high-latitude pulse showed clear twin vortices centered at 70-76 degree geomagnetic latitude in the dayside and was approximately symmetric with respect to the noon meridian. The current direction of the vortices was reversed from the first pulse to the second. it suggests successive appearance of a dawn-to-dusk and then a dusk-to-dawn electric field, both of which were transmitted from the magnetosphere to the polar ionosphere. The effect of ionospheric currents due to these polar electric fields was superposed on the simple magnetic decrease produced by an expansion of the whole magnetosphere and produced the complex waveform distribution on the ground

Investigation of the Effects of Solar and Geomagnetic Changes on the Total Electron Content: Mid-Latitude Region

Science.gov (United States)

Ulukavak, Mustafa; Yalcinkaya, Mualla

2016-04-01

The Global Positioning System (GPS) is used as an important tool for ionosphere monitoring and obtaining the Total Electron Content (TEC). GPS satellites, positioned in the Earth's orbit, are used as sensors to investigate the space weather conditions. In this study, solar and geomagnetic activity variations were investigated between the dates 1 March-30 June 2015 for the mid-latitude region. GPS-TEC variations were calculated for each selected International GNSS Service (IGS) station in Europe. GNSS data was obtained from Crustal Dynamics Data and Information System (CDDIS) archive. Solar and geomagnetic activity indices (Kp, F10.7 ve Dst) were obtained from the Oceanic and Atmospheric Administration (NOAA), the Canadian Space Weather Forecast Centre (CSWFC) and Data Analysis Center for geomagnetism and Space Magnetism Graduate School of Science, Kyoto University (WDC) archives. GPS-TEC variations were determined for the quiet periods of the solar and geomagnetic activities. GPS-TEC changes were then compared with respect to the quiet periods of the solar and geomagnetic activities. Global Ionosphere Maps (GIM) IONEX files, obtained from the IGS analysis center, was used to check the robustness of the GPS-TEC variations. The investigations revealed that it is possible to use the GPS-TEC data for monitoring the ionospheric disturbances.

K-Ar ages of the Auckland geomagnetic excursions