WorldWideScience

Sample records for solar radio storms

  1. Radio Astronomers Get Their First Glimpse of Powerful Solar Storm

    Science.gov (United States)

    2001-08-01

    Astronomers have made the first radio-telescope images of a powerful coronal mass ejection on the Sun, giving them a long-sought glimpse of hitherto unseen aspects of these potentially dangerous events. "These observations are going to provide us with a new and unique tool for deciphering the mechanisms of coronal mass ejections and how they are related to other solar events," said Tim Bastian, an astronomer at the National Science Foundation's National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia. Radio image of coronal mass ejection; circle indicates the size and location of the Sun. White dots are where radio spectral measurements were made. Bastian, along with Monique Pick, Alain Kerdraon and Dalmiro Maia of the Paris Observatory, and Angelos Vourlidas of the Naval Research Laboratory in Washington, D.C., used a solar radio telescope in Nancay, France, to study a coronal mass ejection that occurred on April 20, 1998. Their results will be published in the September 1 edition of the Astrophysical Journal Letters. Coronal mass ejections are powerful magnetic explosions in the Sun's corona, or outer atmosphere, that can blast billions of tons of charged particles into interplanetary space at tremendous speeds. If the ejection is aimed in the direction of Earth, the speeding particles interact with our planet's magnetic field to cause auroral displays, radio-communication blackouts, and potentially damage satellites and electric-power systems. "Coronal mass ejections have been observed for many years, but only with visible-light telescopes, usually in space. While previous radio observations have provided us with powerful diagnostics of mass ejections and associated phenomena in the corona, this is the first time that one has been directly imaged in wavelengths other than visible light," Bastian said. "These new data from the radio observations give us important clues about how these very energetic events work," he added. The radio images show an

  2. Interplanetary radio storms. II - Emission levels and solar wind speed in the range 0.05-0.8 AU

    Science.gov (United States)

    Bougeret, J.-L.; Fainberg, J.; Stone, R. G.

    1984-01-01

    Storms of interplanetary type III radio bursts (IP storms) are commonly observed in the interplanetary medium by the ISEE-3 radio instrument. This instrument has the capability of accurately determining the arrival direction of the radio emission. At each observing frequency, the storm radio sources are tracked as they cross the line-of-sight to the sun. Using a simple model, the emission levels are determined at a number of radio frequencies for four separate storms. The IP storm radiation is found to occur in regions of enhanced density at levels of 0.05 to 0.8 AU. The density in these enhancements falls off faster than R(-2). The solar wind speed in the storm region is also measured. The analysis is consistent with steady conditions in the storm region during a few days around the III storm burst radio emission at the harmonic of the local plasma frequency.

  3. SOLAR RADIO TYPE-I NOISE STORM MODULATED BY CORONAL MASS EJECTIONS

    International Nuclear Information System (INIS)

    Iwai, K.; Tsuchiya, F.; Morioka, A.; Misawa, H.; Miyoshi, Y.; Masuda, S.; Shimojo, M.; Shiota, D.; Inoue, S.

    2012-01-01

    The first coordinated observations of an active region using ground-based radio telescopes and the Solar Terrestrial Relations Observatory (STEREO) satellites from different heliocentric longitudes were performed to study solar radio type-I noise storms. A type-I noise storm was observed between 100 and 300 MHz during a period from 2010 February 6 to 7. During this period the two STEREO satellites were located approximately 65° (ahead) and –70° (behind) from the Sun-Earth line, which is well suited to observe the earthward propagating coronal mass ejections (CMEs). The radio flux of the type-I noise storm was enhanced after the preceding CME and began to decrease before the subsequent CME. This time variation of the type-I noise storm was directly related to the change of the particle acceleration processes around its source region. Potential-field source-surface extrapolation from the Solar and Heliospheric Observatory/Michelson Doppler Imager (SOHO/MDI) magnetograms suggested that there was a multipolar magnetic system around the active region from which the CMEs occurred around the magnetic neutral line of the system. From our observational results, we suggest that the type-I noise storm was activated at a side-lobe reconnection region that was formed after eruption of the preceding CME. This magnetic structure was deformed by a loop expansion that led to the subsequent CME, which then suppressed the radio burst emission.

  4. Solar storms; Tormentas solares

    Energy Technology Data Exchange (ETDEWEB)

    Collaboration: Pereira Cuesta, S.; Pereira Pagan, B.

    2016-08-01

    Solar storms begin with an explosion, or solar flare, on the surface of the sun. The X-rays and extreme ultraviolet radiation from the flare reach the Earths orbit minutes later-travelling at light speed. The ionization of upper layers of our atmosphere could cause radio blackouts and satellite navigation errors (GPS). Soon after, a wave of energetic particles, electrons and protons accelerated by the explosion crosses the orbit of the Earth, and can cause real and significant damage. (Author)

  5. Energetics of small electron acceleration episodes in the solar corona from radio noise storm observations

    Science.gov (United States)

    James, Tomin; Subramanian, Prasad

    2018-05-01

    Observations of radio noise storms can act as sensitive probes of nonthermal electrons produced in small acceleration events in the solar corona. We use data from noise storm episodes observed jointly by the Giant Metrewave Radio Telescope (GMRT) and the Nancay Radioheliograph (NRH) to study characteristics of the nonthermal electrons involved in the emission. We find that the electrons carry 1021 to 1024 erg/s, and that the energy contained in the electrons producing a representative noise storm burst ranges from 1020 to 1023 ergs. These results are a direct probe of the energetics involved in ubiquitous, small-scale electron acceleration episodes in the corona, and could be relevant to a nanoflare-like scenario for coronal heating.

  6. Interplanetary radio storms. 2: Emission levels and solar wind speed in the range 0.05-0.8 AU

    Science.gov (United States)

    Bougeret, J. L.; Fainberg, J.; Stone, R. G.

    1982-01-01

    Storms of interplanetary type III radio bursts (IP storms) are commonly observed in the interplanetry medium by the ISEE-3 radio instrument. This instrument has the capability of accurately determining the arrival direction of the radio emission. At each observing frequency, the storm radio sources are tracked as they cross the line-of-sight to the Sun. Usng a simple model, the emission levels are determined at a number of radio frequencies for four separate storms. The IP storm radiation is found to occur in regions of enhanced density at levels of 0.05 to 0.8 AU. The density in these enhancements falls off faster than R(-2). The solar wind speed in the storm region is also measured. The analysis is consistent with steady conditions in the storm region during a few days around the central meridian passage of the storm. The comparison with average in situ density measurements compiled from the HELIOS 1-2 observations favors type III storm burst radio emission at the harmonic of the local plasma frequency.

  7. EFFECTS OF ALFVEN WAVES ON ELECTRON CYCLOTRON MASER EMISSION IN CORONAL LOOPS AND SOLAR TYPE I RADIO STORMS

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, G. Q.; Chen, L.; Wu, D. J. [Purple Mountain Observatory, CAS, Nanjing 210008 (China); Yan, Y. H., E-mail: djwu@pmo.ac.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, CAS, Beijing 100012 (China)

    2013-06-10

    Solar type I radio storms are long-lived radio emissions from the solar atmosphere. It is believed that these type I storms are produced by energetic electrons trapped within a closed magnetic structure and are characterized by a high ordinary (O) mode polarization. However, the microphysical nature of these emissions is still an open problem. Recently, Wu et al. found that Alfven waves (AWs) can significantly influence the basic physics of wave-particle interactions by modifying the resonant condition. Taking the effects of AWs into account, this work investigates electron cyclotron maser emission driven by power-law energetic electrons with a low-energy cutoff distribution, which are trapped in coronal loops by closed solar magnetic fields. The results show that the emission is dominated by the O mode. It is proposed that this O mode emission may possibly be responsible for solar type I radio storms.

  8. Solar radio continuum storms and a breathing magnetic field model. Final report

    International Nuclear Information System (INIS)

    1975-01-01

    Radio noise continuum emissions observed in metric and decametric wave frequencies are, in general, associated with actively varying sunspot groups accompanied by the S-component of microwave radio emissions. These continuum emission sources, often called type I storm sources, are often associated with type III burst storm activity from metric to hectometric wave frequencies. This storm activity is, therefore, closely connected with the development of these continuum emission sources. It is shown that the S-component emission in microwave frequencies generally precedes, by several days, the emission of these noise continuum storms of lower frequencies. In order for these storms to develop, the growth of sunspot groups into complex types is very important in addition to the increase of the average magnetic field intensity and area of these groups. After giving a review on the theory of these noise continuum storm emissions, a model is briefly considered to explain the relation of the emissions to the storms

  9. Geomagnetic storm related to intense solar radio burst type II and III ...

    African Journals Online (AJOL)

    The strong energetic particles ejected during sun's activity will propagate towards earth and contribute to solar radio bursts. These solar radio bursts can be detected using CALLISTO system. The open website of the NASA provides us the data including CALLISTO, TESIS, solar monitor, SOHO and space weather. The type ...

  10. Solar Radio

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Scientists monitor the structure of the solar corona, the outer most regions of the Sun's atmosphere, using radio waves (100?s of MHz to 10?s of GHz). Variations in...

  11. Type 2 solar radio burst with the reverse frequency drift on the background of a noise storm

    International Nuclear Information System (INIS)

    Korolev, O.S.; Fomichev, V.V.; Chertok, I.M.

    1979-01-01

    Discussed are the main peculiarities of solar radio burst of the 2nd type recorded on November, 19, 1975 in 11sup(h)02sup(m)-11sup(h)06sup(m)UT in the 45-90 MHz range. The burst considered occurred at the background of the developed noise storm with continuum radiation chearacteristic of it and narrow band. Short-term burst of the first type. The burst band drift was accompanied by the successive cessation of noise storm radiation at frequencies of 50-70 MHz. This phenomenon is interpreted as the result of the interaction between the shock wave spreading in the direction of increasing electron density, and the source of noise storm in coronal plasma. Estimated is the shock wave rate and the paremeters of coronal plasma in the direction of its spreading. A mechanism of interaction between the shock wave and the noise storm source is studied. The observed cessation of noise storm generation is explained by violation of conditions of development of instabilities, in particular, with the isotropization of electrons in the radiation source

  12. Solar noise storms

    CERN Document Server

    Elgaroy, E O

    2013-01-01

    Solar Noise Storms examines the properties and features of solar noise storm phenomenon. The book also presents some theories that can be used to gain a better understanding of the phenomenon. The coverage of the text includes topics that cover the features and behavior of noise storms, such as the observable features of noise storms; the relationship between noise storms and the observable features on the sun; and ordered behavior of storm bursts in the time-frequency plane. The book also covers the spectrum, polarization, and directivity of noise storms. The text will be of great use to astr

  13. Storms

    International Nuclear Information System (INIS)

    Kai, Keizo; Melrose, D.B.; Suzuki, S.

    1985-01-01

    At metre and decametre wavelengths long-lasting solar radio emission, consisting of thousands of short-lived spikes superimposed on a slowly varying continuum, is observed. This type of storm emission may continue for periods ranging from a few hours to several days; the long duration is one of the characteristics which distinguish storms from other types of solar radio emission. These events are called storms or noise storms by analogy with geomagnetic storms. (author)

  14. Origin of solar radio waves

    International Nuclear Information System (INIS)

    Olmr, J.

    1977-01-01

    Solar radiowave radiation amounts to about 10 -7 of the total solar radiation. The solar atmosphere emits radiation of different wavelengths from a fraction of nanometer to kilometer waves. The solar radiowaves are of thermal origin and except for neutral hydrogen emission and solid body radio emission their emission always results from free electrons. The radiowave radiation active components were classified in several types, such as noise storms, flashes, flares, continuum, and flashes lasting for several minutes. The respective types are discussed and their origins shown. The mechanisms are described permitting the formation of radio waves of nonthermal origin, i.e., plasma oscillations, gyromagnetic emission, synchrotron and Cherenkov radiations. (J.P.)

  15. Solar flares associated coronal mass ejection accompanied with DH type II radio burst in relation with interplanetary magnetic field, geomagnetic storms and cosmic ray intensity

    Science.gov (United States)

    Chandra, Harish; Bhatt, Beena

    2018-04-01

    In this paper, we have selected 114 flare-CME events accompanied with Deca-hectometric (DH) type II radio burst chosen from 1996 to 2008 (i.e., solar cycle 23). Statistical analyses are performed to examine the relationship of flare-CME events accompanied with DH type II radio burst with Interplanetary Magnetic field (IMF), Geomagnetic storms (GSs) and Cosmic Ray Intensity (CRI). The collected sample events are divided into two groups. In the first group, we considered 43 events which lie under the CME span and the second group consists of 71 events which are outside the CME span. Our analysis indicates that flare-CME accompanied with DH type II radio burst is inconsistent with CSHKP flare-CME model. We apply the Chree analysis by the superposed epoch method to both set of data to find the geo-effectiveness. We observed different fluctuations in IMF for arising and decay phase of solar cycle in both the cases. Maximum decrease in Dst during arising and decay phase of solar cycle is different for both the cases. It is noted that when flare lie outside the CME span CRI shows comparatively more variation than the flare lie under the CME span. Furthermore, we found that flare lying under the CME span is more geo effective than the flare outside of CME span. We noticed that the time leg between IMF Peak value and GSs, IMF and CRI is on average one day for both the cases. Also, the time leg between CRI and GSs is on average 0 to 1 day for both the cases. In case flare lie under the CME span we observed high correlation (0.64) between CRI and Dst whereas when flare lie outside the CME span a weak correlation (0.47) exists. Thus, flare position with respect to CME span play a key role for geo-effectiveness of CME.

  16. The impact of solar flares and magnetic storms on humans

    International Nuclear Information System (INIS)

    Joselyn, J.A.

    1992-01-01

    Three classes of solar emanations, namely, photon radiation from solar flares, solar energetic particles, and inhomogeneities in the solar wind that drive magnetic storms, are examined, and their effects on humans and technological systems are discussed. Solar flares may disrupt radio communications in the HF and VLF ranges. Energetic particles pose a special hazard at low-earth orbit and above, where they can penetrate barriers such as spacesuits and aluminum and destroy cells and solid state electronics. Energetic solar particles also influence terrestrial radio waves propagating through polar regions. Magnetic storms may disturb the operation of navigation instruments, power lines and pipelines, and satellites; they give rise to ionospheric storms which affect radio communication at all latitudes. There is also a growing body of evidence that changes in the geomagnetic field affect biological systems. 3 refs

  17. The impact of solar flares and magnetic storms on humans

    Energy Technology Data Exchange (ETDEWEB)

    Joselyn, J.A. (NOAA, Space Environment Laboratory, Boulder, CO (United States))

    1992-03-01

    Three classes of solar emanations, namely, photon radiation from solar flares, solar energetic particles, and inhomogeneities in the solar wind that drive magnetic storms, are examined, and their effects on humans and technological systems are discussed. Solar flares may disrupt radio communications in the HF and VLF ranges. Energetic particles pose a special hazard at low-earth orbit and above, where they can penetrate barriers such as spacesuits and aluminum and destroy cells and solid state electronics. Energetic solar particles also influence terrestrial radio waves propagating through polar regions. Magnetic storms may disturb the operation of navigation instruments, power lines and pipelines, and satellites; they give rise to ionospheric storms which affect radio communication at all latitudes. There is also a growing body of evidence that changes in the geomagnetic field affect biological systems. 3 refs.

  18. Solar radio observations and interpretations

    International Nuclear Information System (INIS)

    Rosenberg, H.

    1976-01-01

    The recent solar radio observations related to flares are reviewed for the frequency range of a few kilohertz to several gigahertz. The analysis of the radio data leads to boundary conditions on the acceleration processes which are responsible for the fast particles which cause radio emission. The role and cause of plasma turbulence at the plasma-frequency and at much lower frequencies is discussed in relation to the acceleration processes and the radio emission mechanisms for the various radio bursts. (author)

  19. Solar Indices - Solar Radio Flux

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  20. Nuclear magnetohydrodynamic EMP, solar storms, and substorms

    International Nuclear Information System (INIS)

    Rabinowitz, M.; Meliopoulous, A.P.S.; Glytsis, E.N.

    1992-01-01

    In addition to a fast electromagnetic pulse (EMP), a high altitude nuclear burst produces a relatively slow magnetohydrodynamic EMP (MHD EMP), whose effects are like those from solar storm geomagnetically induced currents (SS-GIC). The MHD EMP electric field E approx-lt 10 - 1 V/m and lasts approx-lt 10 2 sec, whereas for solar storms E approx-gt 10 - 2 V/m and lasts approx-gt 10 3 sec. Although the solar storm electric field is lower than MHD EMP, the solar storm effects are generally greater due to their much longer duration. Substorms produce much smaller effects than SS-GIC, but occur much more frequently. This paper describes the physics of such geomagnetic disturbances and analyzes their effects

  1. Polarization reversal during the solar noise storm activity of August 1971

    International Nuclear Information System (INIS)

    Kurihara, Masahiro

    1975-01-01

    Reversals of the sense of circular polarization of solar radio emission were observed for active type I storms in August 1971. Observations with a 160-MHz interferometer revealed that the reversals were caused by sudden growth and decay of a secondary storm source whose sense of polarization was opposite to that of the long-lasting main source. The time variations of both the associated S-component sources and sunspots are compared with that of the storm sources. The role of the magnetic field, which presumably connects the storm sources, the S-component sources, and the sunspots, is discussed in relation to the origin of the storm activity. (author)

  2. Introduction to solar radio astronomy and radio physics

    International Nuclear Information System (INIS)

    Krueger, A.

    1979-01-01

    A systematic summary is presented of the work done during the last thirty years in the field of solar radio astronomy from the standpoint of general solar physics. Instrumental aspects, observations and theory are covered. A brief introduction is given to the matter consisting of the history of solar radio astronomy and some fundamentals of astronomy and solar physics are outlined. Some topics of the instrumental background of solar radio astronomy and the main results of observations are presented. The elements of a theoretical interpretation of solar radio observations are reported and a synthesis of both observation and theory contributing to a general picture of solar and solar-terrestrial physics is outlined. (C.F./Auth)

  3. Spectropolarimetric Observations of Solar Noise Storms at Low Frequencies

    Science.gov (United States)

    Mugundhan, V.; Ramesh, R.; Kathiravan, C.; Gireesh, G. V. S.; Hegde, Aathira

    2018-03-01

    A new high-resolution radio spectropolarimeter instrument operating in the frequency range of 15 - 85 MHz has recently been commissioned at the Radio Astronomy Field Station of the Indian Institute of Astrophysics at Gauribidanur, 100 km north of Bangalore, India. We describe the design and construction of this instrument. We present observations of a solar radio noise storm associated with Active Region (AR) 12567 in the frequency range of {≈} 15 - 85 MHz during 18 and 19 July 2016, observed using this instrument in the meridian-transit mode. This is the first report that we are aware of in which both the burst and continuum properties are derived simultaneously. Spectral indices and degree of polarization of both the continuum radiation and bursts are estimated. It is found that i) Type I storm bursts have a spectral index of {≈} {+}3.5, ii) the spectral index of the background continuum is ≈+2.9, iii) the transition frequency between Type I and Type III storms occurs at ≈55 MHz, iv) Type III bursts have an average spectral index of ≈-2.7, v) the spectral index of the Type III continuum is ≈-1.6, and vi) the degree of circular polarization of all Type I (Type III) bursts is ≈90% (30%). The results obtained here indicate that the continuum emission is due to bursts occurring in rapid succession. We find that the derived parameters for Type I bursts are consistent with suprathermal electron acceleration theory and those of Type III favor fundamental plasma emission.

  4. Advances in solar radio astronomy

    Science.gov (United States)

    Kundu, M. R.

    1982-01-01

    The status of the observations and interpretations of the sun's radio emission covering the entire radio spectrum from millimeter wavelengths to hectometer and kilometer wavelengths is reviewed. Emphasis is given to the progress made in solar radio physics as a result of recent advances in plasma and radiation theory. It is noted that the capability now exists of observing the sun with a spatial resolution of approximately a second of arc and a temporal resolution of about a millisecond at centimeter wavelengths and of obtaining fast multifrequency two-dimensional pictures of the sun at meter and decameter wavelengths. A summary is given of the properties of nonflaring active regions at millimeter, centimeter, and meter-decameter wavelengths. The properties of centimeter wave bursts are discussed in connection with the high spatial resolution observations. The observations of the preflare build-up of an active region are reviewed. High spatial resolution observations (a few seconds of arc to approximately 1 arcsec) are discussed, with particular attention given to the one- and two-dimensional maps of centimeter-wavelength burst sources.

  5. 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.

  6. Ionospheric Caustics in Solar Radio Observations

    Science.gov (United States)

    Koval, A.; Chen, Y.; Stanislavsky, A.

    2016-12-01

    The Earth ionosphere possesses by natural focusing and defocusing effects on radio waves due to presence of variable ionospheric irregularities which could act like convergent and divergent lenses on incident radiation. In particular, the focusing of emission from the Sun was firstly detected on the Nançay Decameter Array dynamic spectra in the 1980s. On time-frequency spectrograms the intensity variations form specific structures different from well-known solar radio bursts and clearly distinguishing on a background of solar radiation. Such structures have been identified as ionospheric caustics (ICs) and considered to be the result of radio waves refraction on medium scale travelling ionospheric disturbances (MSTIDs). Although nowadays the ICs are registered by different radio observatories due to augmentation of low-frequency radio telescopes, the most recent papers devoted to ICs in solar radio records date back to the 1980s. In this study, we revisit the ICs issue with some new results by conducting a statistical analysis of occurrence rate of ICs in solar dynamic spectra in meter-decameter wavelength range for long continuous period (15 years). The seasonal variations in ICs appearance have been found for the first time. Besides, we report the possible solar cycle dependence of ICs emergence. The radio waves propagation in the ionosphere comprising MSTIDs will be considered. The present research renews the subject of ICs in the low-frequency solar radio astronomy after about 35-year letup.

  7. Solar energetic particles and radio burst emission

    Directory of Open Access Journals (Sweden)

    Miteva Rositsa

    2017-01-01

    Full Text Available We present a statistical study on the observed solar radio burst emission associated with the origin of in situ detected solar energetic particles. Several proton event catalogs in the period 1996–2016 are used. At the time of appearance of the particle origin (flare and coronal mass ejection we identified radio burst signatures of types II, III and IV by inspecting dynamic radio spectral plots. The information from observatory reports is also accounted for during the analysis. The occurrence of solar radio burst signatures is evaluated within selected wavelength ranges during the solar cycle 23 and the ongoing 24. Finally, we present the burst occurrence trends with respect to the intensity of the proton events and the location of their solar origin.

  8. Possible mechanism of solar noise storm generation in meter wavelength

    International Nuclear Information System (INIS)

    Genkin, L.G.; Erukhimov, L.M.; Levin, B.N.

    1989-01-01

    Fluctuation plasma mechanism of noise storm generation is proposed. The sporadic formation of density irregularities in plasma (Langmuir) turbulence region is shown to be the result of thermal stratification of plasma. The noise storm type 1 bursts in their typical parameters are like radio emission due to plasma turbulence conversion on this structures

  9. First Colombian Solar Radio Interferometer: current stage

    Science.gov (United States)

    Guevara Gómez, J. C.; Martínez Oliveros, J. C.; Calvo-Mozo, B.

    2017-10-01

    Solar radio astronomy is a fast developing research field in Colombia. Here, we present the scientific goals, specifications and current state of the First Colombian Solar Radio Interferometer consisting of two log-periodic antennas covering a frequency bandwidth op to 800 MHz. We describe the importance and benefits of its development to the radioastronomy in Latin America and its impact on the scientific community and general public.

  10. A dynamic system to forecast ionospheric storm disturbances based on solar wind conditions

    Directory of Open Access Journals (Sweden)

    L. R. Cander

    2005-06-01

    Full Text Available For the reliable performance of technologically advanced radio communications systems under geomagnetically disturbed conditions, the forecast and modelling of the ionospheric response during storms is a high priority. The ionospheric storm forecasting models that are currently in operation have shown a high degree of reliability during quiet conditions, but they have proved inadequate during storm events. To improve their prediction accuracy, we have to take advantage of the deeper understanding in ionospheric storm dynamics that is currently available, indicating a correlation between the Interplanetary Magnetic Field (IMF disturbances and the qualitative signature of ionospheric storm disturbances at middle latitude stations. In this paper we analyse observations of the foF2 critical frequency parameter from one mid-latitude European ionospheric station (Chilton in conjunction with observations of IMF parameters (total magnitude, Bt and Bz-IMF component from the ACE spacecraft mission for eight storm events. The determination of the time delay in the ionospheric response to the interplanetary medium disturbances leads to significant results concerning the forecast of the ionospheric storms onset and their development during the first 24 h. In this way the real-time ACE observations of the solar wind parameters may be used in the development of a real-time dynamic ionospheric storm model with adequate accuracy.

  11. Space weather effects on radio propagation: study of the CEDAR, GEM and ISTP storm events

    Directory of Open Access Journals (Sweden)

    D. V. Blagoveshchensky

    2008-06-01

    Full Text Available The impact of 14 geomagnetic storms from a list of CEDAR, GEM and ISTP storms, that occurred during 1997–1999, on radio propagation conditions has been investigated. The propagation conditions were estimated through variations of the MOF and LOF (the maximum and lowest operation frequencies on three high-latitude HF radio paths in north-west Russia. Geophysical data of Dst, Bz, AE as well as some riometer data from Sodankyla observatory, Finland, were used for the analysis. It was shown that the storm impact on the ionosphere and radio propagation for each storm has an individual character. Nevertheless, there are common patterns in variation of the propagation parameters for all storms. Thus, the frequency range Δ=MOF−LOF increases several hours before a storm, then it narrows sharply during the storm, and expands again several hours after the end of the storm. This regular behaviour should be useful for the HF radio propagation predictions and frequency management at high latitudes. On the trans-auroral radio path, the time interval when the signal is lost through a storm (tdes depends on the local time. For the day-time storms an average value tdes is 6 h, but for night storms tdes is only 2 h. The ionization increase in the F2 layer before storm onset is 3.5 h during the day-time and 2.4 h at night. Mechanisms to explain the observed variations are discussed including some novel possibilities involving energy input through the cusp.

  12. Space weather effects on radio propagation: study of the CEDAR, GEM and ISTP storm events

    Directory of Open Access Journals (Sweden)

    D. V. Blagoveshchensky

    2008-06-01

    Full Text Available The impact of 14 geomagnetic storms from a list of CEDAR, GEM and ISTP storms, that occurred during 1997–1999, on radio propagation conditions has been investigated. The propagation conditions were estimated through variations of the MOF and LOF (the maximum and lowest operation frequencies on three high-latitude HF radio paths in north-west Russia. Geophysical data of Dst, Bz, AE as well as some riometer data from Sodankyla observatory, Finland, were used for the analysis. It was shown that the storm impact on the ionosphere and radio propagation for each storm has an individual character. Nevertheless, there are common patterns in variation of the propagation parameters for all storms. Thus, the frequency range Δ=MOF−LOF increases several hours before a storm, then it narrows sharply during the storm, and expands again several hours after the end of the storm. This regular behaviour should be useful for the HF radio propagation predictions and frequency management at high latitudes. On the trans-auroral radio path, the time interval when the signal is lost through a storm (tdes depends on the local time. For the day-time storms an average value tdes is 6 h, but for night storms tdes is only 2 h. The ionization increase in the F2 layer before storm onset is 3.5 h during the day-time and 2.4 h at night. Mechanisms to explain the observed variations are discussed including some novel possibilities involving energy input through the cusp.

  13. Observation of solar wind with radio-star scintillation

    International Nuclear Information System (INIS)

    Watanabe, Takashi

    1974-01-01

    Large solar flares occurred in groups in early August 1972, and many interesting phenomena were observed. The solar wind condition during this period, obtained by scintillation observation, is reviewed. The velocity of solar wind has been determined from the observation of interplanetary space scintillation at Toyokawa, Fujigamine and Sugadaira. Four to ten radio wave sources were observed for ten minutes at each southing every day. Strong earth magnetic storm and the Forbush decrease of cosmic ray were observed during the period from August 3rd to 7th. Pioneer 9 observed a solar wind having the maximum velocity as high as 1,100 km/sec, and HEOS-II observed a solar wind having the velocity close to 2,000 km/sec. On the other hand, according to the scintillation of 3C-48 and 3C-144, the velocity of solar wind passing in the interplanetary space on the westside of the earth was only 300 to 400 km/sec. Therefore it is considered that the condition of solar wind on the east side of the earth differs from that on the west side of the earth. Pioneer 9 observed the pass of a shock wave on August 9th. With all radio wave sources, high velocity solar wind was observed and Pioneer 6 positioned on the west side of the earth also observed it. The thickness of this shock wave is at least 0.3 AU. Discussion is made on the cause for the difference between the asymmetric shock wave in the direction of south-west and symmetrical shock wave. The former may be blast wave, and the latter may be piston driven shock wave and the like. (Iwakiri, K.)

  14. Solar energetic particles and radio burst emission

    Czech Academy of Sciences Publication Activity Database

    Miteva, R.; Samwel, S. W.; Krupař, Vratislav

    2017-01-01

    Roč. 7 (2017), č. článku A37. ISSN 2115-7251 R&D Projects: GA ČR(CZ) GJ17-06818Y Institutional support: RVO:68378289 Keywords : solar energetic particles * solar radio burst emission * solar cycle Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.446, year: 2016 https://www.swsc-journal.org/ articles /swsc/abs/2017/01/swsc170028/swsc170028.html

  15. Solar Radio Bursts and Space Weather

    Science.gov (United States)

    Gopalswamy, Natchimuthuk,

    2012-01-01

    Radio bursts from the Sun are produced by electron accelerated to relativistic energies by physical processes on the Sun such as solar flares and coronal mass ejections (CMEs). The radio bursts are thus good indicators of solar eruptions. Three types of nonthermal radio bursts are generally associated with CMEs. Type III bursts due to accelerated electrons propagating along open magnetic field lines. The electrons are thought to be accelerated at the reconnection region beneath the erupting CME, although there is another view that the electrons may be accelerated at the CME-driven shock. Type II bursts are due to electrons accelerated at the shock front. Type II bursts are also excellent indicators of solar energetic particle (SEP) events because the same shock is supposed accelerate electrons and ions. There is a hierarchical relationship between the wavelength range of type /I bursts and the CME kinetic energy. Finally, Type IV bursts are due to electrons trapped in moving or stationary structures. The low frequency stationary type IV bursts are observed occasionally in association with very fast CMEs. These bursts originate from flare loops behind the erupting CME and hence indicate tall loops. This paper presents a summary of radio bursts and their relation to CMEs and how they can be useful for space weather predictions.

  16. Solar system radio astronomy at low frequencies

    International Nuclear Information System (INIS)

    Desch, M.D.

    1987-01-01

    The planetary radio-astronomy observations obtained with the two Voyager spacecraft since their launch in 1977 are briefly characterized and illustrated with graphs, diagrams, and sample spectra. Topics addressed include the spacecraft designs and trajectories, the wavelength coverage of the radio instruments, the Io-controlled LF emission of Jupiter, the solar-wind effect on the Saturn kilometric radiation, the Saturn electrostatic discharges, and the use of the clocklike feature of the Uranus emission to measure the planet's rotation period. 23 references

  17. The Effect of Solar Radiation on Radio Signal for Radio Astronomy Purposes

    International Nuclear Information System (INIS)

    Nor Hazmin Sabri; Atiq Wahidah Azlan; Roslan Umar; Roslan Umar; Shahirah Syafa Sulan; Zainol Abidin Ibrahim; Wan Zul Adli Wan Mokhtar

    2015-01-01

    Radio astronomy is a subfields of astronomy which is discovers the celestial objects at radio frequencies. Observation in radio astronomy is conducted using single antenna or array of antennas, known as radio telescope. Other than that, radio astronomy also holds an advantage over other alternatives to optical astronomy due to its capability of observing from the ground level. In this study, the effect of solar radiation that contributes the Radio Frequency Interferences (RFI) is reviewed. The low RFI level is required to set up the radio telescope for radio astronomy observation. The effect of solar radiation on radio signal was investigated by determining the RFI pattern using spectrum analyzer. The solar radiation data was obtained from weather station located at KUSZA Observatory, East Coast Environmental Research Institute (ESERI), UniSZA. We can conclude that the solar radiation factor give the minimum significant effect to radio signal. (author)

  18. Southern hemisphere solar radio heliograph

    Science.gov (United States)

    Sawant, H. S.; Fernandes, F. C. R.; Neri, J. A. C. F.; Cecatto, J. R.; Faria, C.; Stephany, S.; Rosa, R. R.; Andrade, M. C.; Ludke, E.; Subramanian, K. R.; Ramesh, R.; Sundrarajan, M. S.; Sankararaman, M. R.; Ananthakrishnan, S.; Swarup, G.; Boas, J. W. V.; Botti, L. C. L.; Moron, C. E.; Saito, J. H.; Karlický, M.

    2002-12-01

    The Brazilian Decimetric Array (BDA) is being developed at National Institute for Space Research (INPE) as an international collaborative program. Initially, the BDA will operate in the tuneable frequency range of 1.2-1.7 GHz. The initial planned baseline for BDA 'T' array is 256×144 m and will be extended to 2.2×1.1 km. In this paper, we present the results of developments concerning the prototype of BDA (PBDA). The PBDA will initially operate in the frequency range of 1.2-1.7 GHz, with a five-antenna array, using 4-meter parabolic dishes with altitude and azimuth mountings and complete tracking capability. The spatial resolution for solar images with the PBDA will be about 3.5 arc-minutes leading to a sensitivity of ≍2×104 mJy/beam for an integration time of 1 sec. The array will be installed at -22°41'19" latitude and 45°0'22" W longitude and it is under operation between 9 and 21 UT for continuous solar flux monitoring. Details of the PBDA system are presented.

  19. Overview of on-board measurements during solar storm periods

    Czech Academy of Sciences Publication Activity Database

    Beck, P.; Dyer, C.; Fuller, N.; Hands, A.; Latocha, M.; Rollet, S.; Spurný, František

    2009-01-01

    Roč. 136, č. 4 (2009), s. 297-303 ISSN 0144-8420 R&D Projects: GA ČR GA205/09/0171 Institutional research plan: CEZ:AV0Z10480505 Keywords : solar storm * aircraft crew * cosmic radiation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.707, year: 2009

  20. Solar flare effects and storm sudden commencement even in ...

    African Journals Online (AJOL)

    1998-05-08

    Variations in the three components of geomagnetic field were observed at the twenty-two geomagnetic Euro-African Observatories during the solar flare that occurred on the 6 May, 1998 at 0080UT and storm sudden commencement that took place on May 8, 1998 at 15.00 UT. The geomagnetic field on 6 May, 1998 was ...

  1. Full PIC simulations of solar radio emission

    Science.gov (United States)

    Sgattoni, A.; Henri, P.; Briand, C.; Amiranoff, F.; Riconda, C.

    2017-12-01

    Solar radio emissions are electromagnetic (EM) waves emitted in the solar wind plasma as a consequence of electron beams accelerated during solar flares or interplanetary shocks such as ICMEs. To describe their origin, a multi-stage model has been proposed in the 60s which considers a succession of non-linear three-wave interaction processes. A good understanding of the process would allow to infer the kinetic energy transfered from the electron beam to EM waves, so that the radio waves recorded by spacecraft can be used as a diagnostic for the electron beam.Even if the electrostatic problem has been extensively studied, full electromagnetic simulations were attempted only recently. Our large scale 2D-3V electromagnetic PIC simulations allow to identify the generation of both electrostatic and EM waves originated by the succession of plasma instabilities. We tested several configurations varying the electron beam density and velocity considering a background plasma of uniform density. For all the tested configurations approximately 105 of the electron-beam kinetic energy is transfered into EM waves emitted in all direction nearly isotropically. With this work we aim to design experiments of laboratory astrophysics to reproduce the electromagnetic emission process and test its efficiency.

  2. Radio Emissions from Electrical Activity in Martian Dust Storms

    Science.gov (United States)

    Majid, W.; Arabshahi, S.; Kocz, J.; Schulter, T.; White, L.

    2017-12-01

    Dust storms on Mars are predicted to be capable of producing electrostatic fields and discharges, even larger than those in dust storms on Earth. There are three key elements in the characterization of Martian electrostatic discharges: dependence on Martian environmental conditions, event rate, and the strength of the generated electric fields. The detection and characterization of electric activity in Martian dust storms has important implications for habitability, and preparations for human exploration of the red planet. Furthermore, electrostatic discharges may be linked to local chemistry and plays an important role in the predicted global electrical circuit. Because of the continuous Mars telecommunication needs of NASA's Mars-based assets, the Deep Space Network (DSN) is the only facility in the world that combines long term, high cadence, observing opportunities with large sensitive telescopes, making it a unique asset worldwide in searching for and characterizing electrostatic activity from large scale convective dust storms at Mars. We will describe a newly inaugurated program at NASA's Madrid Deep Space Communication Complex to carry out a long-term monitoring campaign to search for and characterize the entire Mars hemisphere for powerful discharges during routine tracking of spacecraft at Mars on an entirely non-interfering basis. The ground-based detections will also have important implications for the design of a future instrument that could make similar in-situ measurements from orbit or from the surface of Mars, with far greater sensitivity and duty cycle, opening up a new window in our understanding of the Martian environment.

  3. The Ring Current Response to Solar and Interplanetary Storm Drivers

    Science.gov (United States)

    Mouikis, C.; Kistler, L. M.; Bingham, S.; Kronberg, E. A.; Gkioulidou, M.; Huang, C. L.; Farrugia, C. J.

    2014-12-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), corotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure, in turn, change the global magnetic field, controlling the transport of the radiation belts. To quantitatively determine the field changes during a storm throughout the magnetosphere, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. Because the measured ring current energy spectra depend not only on local processes, but also on the history of the ions along their entire drift path, measurements of ring current energy spectra at two or more locations can be used to strongly constrain the time dependent magnetic and electric fields. In this study we use data predominantly from the Cluster and the Van Allen Probes, covering more than a full solar cycle (from 2001 to 2014). For the period 2001-2012, the Cluster CODIF and RAPID measurements of the inner magnetosphere are the primary data set used to monitor the storm time ring current variability. After 2012, the Cluster data set complements the data from the Van Allen Probes HOPE and RBSPICE instruments, providing additional measurements from different MLT and L shells. Selected storms from this periods, allow us to study the ring current dynamics and pressure changes, as a function of L shell, magnetic local time, and the type of interplanetary disturbances.

  4. The extreme solar storm of May 1921: observations and a complex topological model

    Directory of Open Access Journals (Sweden)

    H. Lundstedt

    2015-01-01

    Full Text Available A complex solid torus model was developed in order to be able to study an extreme solar storm, the so-called "Great Storm" or "New York Railroad Storm" of May 1921, when neither high spatial and time resolution magnetic field measurements, solar flare nor coronal mass ejection observations were available. We suggest that a topological change happened in connection with the occurrence of the extreme solar storm. The solar storm caused one of the most severe space weather effects ever.

  5. Deka-keV X-ray emission associated with the onset of radio noise storms

    DEFF Research Database (Denmark)

    Crosby, N.; Vilmer, N.; Lund, Niels

    1996-01-01

    Radio noise storms show that suprathermal electrons (a few tens of keV) are present in the vicinity of active regions during several hours or even a few days. Where and how these electrons are energized is not yet well known. A flare-like sudden energy release in the active region is in general o...

  6. NASA seeks to revive lost probe that traced solar storms

    Science.gov (United States)

    Voosen, Paul

    2018-02-01

    NASA's Imager for Magnetopause-to-Aurora Global Exploration (IMAGE), a satellite that failed in 2005, was recently discovered to be reactivated by an amateur astronomer. Until its demise, IMAGE provided unparalleled views of solar storms crashing into Earth's magnetosphere, a capability that has not been replaced since. The amateur astronomer was on the search for Zuma, a classified U.S. satellite that's believed to have failed after launch. He instead discovered IMAGE, broadcasting again, likely thanks to a reboot that occurred after its batteries drained during a past solar eclipse. NASA scientists are now working to communicate with the satellite in the hopes of reviving its six scientific instruments.

  7. Distant Tail Behavior During High Speed Solar Wind Streams and Magnetic Storms

    Science.gov (United States)

    Ho, C. M.; Tsurutani, B. T.

    1997-01-01

    We have examined the ISEE 3 distant tail data during three intense magnetic storms and have identified the tail response to high-speed solar wind streams, interplanetary magnetic clouds, and near-Earth storms.

  8. (abstract) The Distant Tail Behavior During High Speed Solar Wind Streams and Magnetic Storms

    Science.gov (United States)

    Ho, C. M.; Tsurutani, B. T.

    1996-01-01

    We have examined the ISEE-3 distant tail data during three intense magnetic storms and have identified the tail response to high speed solar wind streams, interplanetary magnetic clouds, and near-Earth storms.

  9. Remote Sensing of the Heliospheric Solar Wind using Radio ...

    Indian Academy of Sciences (India)

    tribpo

    Astr. (2000) 21, 439–444. Remote Sensing of the Heliospheric Solar Wind using Radio. Astronomy Methods and Numerical Simulations. S. Ananthakrishnan, National Center for Radio Astrophysics, Tata Institute of. Fundamental Research, Pune, India. Abstract. The ground-based radio astronomy method of interplanetary.

  10. Solar wind drivers of geomagnetic storms during more than four solar cycles

    Directory of Open Access Journals (Sweden)

    Richardson Ian G.

    2012-05-01

    Full Text Available Using a classification of the near-Earth solar wind into three basic flow types: (1 High-speed streams associated with coronal holes at the Sun; (2 Slow, interstream solar wind; and (3 Transient flows originating with coronal mass ejections (CMEs at the Sun, including interplanetary CMEs and the associated upstream shocks and post-shock regions, we determine the drivers of geomagnetic storms of various size ranges based on the Kp index and the NOAA “G” criteria since 1964, close to the beginning of the space era, to 2011, encompassing more than four solar cycles (20–23. We also briefly discuss the occurrence of storms since the beginning of the Kp index in 1932, in the minimum before cycle 17. We note that the extended low level of storm activity during the minimum following cycle 23 is without precedent in this 80-year interval. Furthermore, the “typical” numbers of storm days/cycle quoted in the standard NOAA G storm table appear to be significantly higher than those obtained from our analysis, except for the strongest (G5 storms, suggesting that they should be revised downward.

  11. On the Reduced Geoeffectiveness of Solar Cycle 24: A Moderate Storm Perspective

    Science.gov (United States)

    Selvakumaran, R.; Veenadhari, B.; Akiyama, S.; Pandya, Megha; Gopalswamy, N,; Yashiro, S.; Kumar, Sandeep; Makela, P.; Xie, H.

    2016-01-01

    The moderate and intense geomagnetic storms are identified for the first 77 months of solar cycles 23 and 24. The solar sources responsible for the moderate geomagnetic storms are indentified during the same epoch for both the cycles. Solar cycle 24 has shown nearly 80% reduction in the occurrence of intense storms whereas it is only 40% in case of moderate storms when compared to previous cycle. The solar and interplanetary characteristics of the moderate storms driven by coronal mass ejection (CME) are compared for solar cycles 23 and 24 in order to see reduction in geoeffectiveness has anything to do with the occurrence of moderate storm. Though there is reduction in the occurrence of moderate storms, the Dst distribution does not show much difference. Similarly, the solar source parameters like CME speed, mass, and width did not show any significant variation in the average values as well as the distribution. The correlation between VBz and Dst is determined, and it is found to be moderate with value of 0.68 for cycle 23 and 0.61 for cycle 24. The magnetospheric energy flux parameter epsilon (epsilon) is estimated during the main phase of all moderate storms during solar cycles 23 and 24. The energy transfer decreased in solar cycle 24 when compared to cycle 23. These results are significantly different when all geomagnetic storms are taken into consideration for both the solar cycles.

  12. Calibration of Solar Radio Spectrometer of the Purple Mountain Observatory

    Science.gov (United States)

    Lei, LU; Si-ming, LIU; Qi-wu, SONG; Zong-jun, NING

    2015-10-01

    Calibration is a basic and important job in solar radio spectral observations. It not only deduces the solar radio flux as an important physical quantity for solar observations, but also deducts the flat field of the radio spectrometer to display the radio spectrogram clearly. In this paper, we first introduce the basic method of calibration based on the data of the solar radio spectrometer of Purple Mountain Observatory. We then analyze the variation of the calibration coefficients, and give the calibrated results for a few flares. These results are compared with those of the Nobeyama solar radio polarimeter and the hard X-ray observations of the RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) satellite, it is shown that these results are consistent with the characteristics of typical solar flare light curves. In particular, the analysis on the correlation between the variation of radio flux and the variation of hard X-ray flux in the pulsing phase of a flare indicates that these observations can be used to study the relevant radiation mechanism, as well as the related energy release and particle acceleration processes.

  13. Variability of fractal dimension of solar radio flux

    Science.gov (United States)

    Bhatt, Hitaishi; Sharma, Som Kumar; Trivedi, Rupal; Vats, Hari Om

    2018-04-01

    In the present communication, the variation of the fractal dimension of solar radio flux is reported. Solar radio flux observations on a day to day basis at 410, 1415, 2695, 4995, and 8800 MHz are used in this study. The data were recorded at Learmonth Solar Observatory, Australia from 1988 to 2009 covering an epoch of two solar activity cycles (22 yr). The fractal dimension is calculated for the listed frequencies for this period. The fractal dimension, being a measure of randomness, represents variability of solar radio flux at shorter time-scales. The contour plot of fractal dimension on a grid of years versus radio frequency suggests high correlation with solar activity. Fractal dimension increases with increasing frequency suggests randomness increases towards the inner corona. This study also shows that the low frequency is more affected by solar activity (at low frequency fractal dimension difference between solar maximum and solar minimum is 0.42) whereas, the higher frequency is less affected by solar activity (here fractal dimension difference between solar maximum and solar minimum is 0.07). A good positive correlation is found between fractal dimension averaged over all frequencies and yearly averaged sunspot number (Pearson's coefficient is 0.87).

  14. EUV and Magnetic Activities Associated with Type-I Solar Radio Bursts

    Science.gov (United States)

    Li, C. Y.; Chen, Y.; Wang, B.; Ruan, G. P.; Feng, S. W.; Du, G. H.; Kong, X. L.

    2017-06-01

    Type-I bursts ( i.e. noise storms) are the earliest-known type of solar radio emission at the meter wavelength. They are believed to be excited by non-thermal energetic electrons accelerated in the corona. The underlying dynamic process and exact emission mechanism still remain unresolved. Here, with a combined analysis of extreme ultraviolet (EUV), radio and photospheric magnetic field data of unprecedented quality recorded during a type-I storm on 30 July 2011, we identify a good correlation between the radio bursts and the co-spatial EUV and magnetic activities. The EUV activities manifest themselves as three major brightening stripes above a region adjacent to a compact sunspot, while the magnetic field there presents multiple moving magnetic features (MMFs) with persistent coalescence or cancelation and a morphologically similar three-part distribution. We find that the type-I intensities are correlated with those of the EUV emissions at various wavelengths with a correlation coefficient of 0.7 - 0.8. In addition, in the region between the brightening EUV stripes and the radio sources there appear consistent dynamic motions with a series of bi-directional flows, suggesting ongoing small-scale reconnection there. Mainly based on the induced connection between the magnetic motion at the photosphere and the EUV and radio activities in the corona, we suggest that the observed type-I noise storms and the EUV brightening activities are the consequence of small-scale magnetic reconnection driven by MMFs. This is in support of the original proposal made by Bentley et al. ( Solar Phys. 193, 227, 2000).

  15. 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.

  16. Direct observations of low-energy solar electrons associated with a type 3 solar radio burst

    Science.gov (United States)

    Frank, L. A.; Gurnett, D. A.

    1972-01-01

    On 6 April 1971 a solar X-ray flare and a type 3 solar radio noise burst were observed with instrumentation on the eccentric-orbiting satellite IMP 6. The type 3 solar radio noise burst was detected down to a frequency of 31 kHz. A highly anisotropic packet of low-energy solar electron intensities arrived at the satellite approximately 6000 seconds after the onset of the solar flare. This packet of solar electron intensities was observed for 4200 seconds. Maximum differential intensities of the solar electrons were in the energy range of one to several keV. The frequency drift rate of the type 3 radio noise at frequencies below 178 kHz also indicated an average particle speed corresponding to that of a 3-keV electron. The simultaneous observations of these solar electron intensities and of the type 3 solar radio burst are presented, and their interrelationships are explored.

  17. 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 Bzmin 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 VBsmax in an active period is much larger than in a quiet period. (5 Solar wind parameters, Bzmin, Vmax and VBsmax are correlated well with geomagnetic storm intensity, Dstmin during a solar active period. (6 Solar wind parameters, Bzmin, and VBsmax are not correlated well (very poorly for Vmax 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 Dstmin≤−100 nT caused by MCs occurred in the solar active period than in the solar quiet period.

  18. 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)

  19. Variation of Magnetic Field (By , Bz) Polarity and Statistical Analysis of Solar Wind Parameters during the Magnetic Storm Period

    OpenAIRE

    Ga-Hee Moon

    2011-01-01

    It is generally believed that the occurrence of a magnetic storm depends upon the solar wind conditions, particularly the southward interplanetary magnetic field (IMF) component. To understand the relationship between solar wind parameters and magnetic storms, variations in magnetic field polarity and solar wind parameters during magnetic storms are examined. A total of 156 storms during the period of 1997~2003 are used. According to the interplanetary driver, magnetic storms are ...

  20. Solar observations with a low frequency radio telescope

    Science.gov (United States)

    Myserlis, I.; Seiradakis, J.; Dogramatzidis, M.

    2012-01-01

    We have set up a low frequency radio monitoring station for solar bursts at the Observatory of the Aristotle University in Thessaloniki. The station consists of a dual dipole phased array, a radio receiver and a dedicated computer with the necessary software installed. The constructed radio receiver is based on NASA's Radio Jove project. It operates continuously, since July 2010, at 20.1 MHz (close to the long-wavelength ionospheric cut-off of the radio window) with a narrow bandwidth (~5 kHz). The system is properly calibrated, so that the recorded data are expressed in antenna temperature. Despite the high interference level of an urban region like Thessaloniki (strong broadcasting shortwave radio stations, periodic experimental signals, CBs, etc), we have detected several low frequency solar radio bursts and correlated them with solar flares, X-ray events and other low frequency solar observations. The received signal is monitored in ordinary ASCII format and as audio signal, in order to investigate and exclude man-made radio interference. In order to exclude narrow band interference and calculate the spectral indices of the observed events, a second monitoring station, working at 36 MHz, is under construction at the village of Nikiforos near the town of Drama, about 130 km away of Thessaloniki. Finally, we plan to construct a third monitoring station at 58 MHz, in Thessaloniki. This frequency was revealed to be relatively free of interference, after a thorough investigation of the region.

  1. The 2015 Summer Solstice Storm: One of the Major Geomagnetic Storms of Solar Cycle 24 Observed at Ground Level

    Science.gov (United States)

    Augusto, C. R. A.; Navia, C. E.; de Oliveira, M. N.; Nepomuceno, A. A.; Raulin, J. P.; Tueros, E.; de Mendonça, R. R. S.; Fauth, A. C.; Vieira de Souza, H.; Kopenkin, V.; Sinzi, T.

    2018-05-01

    We report on the 22 - 23 June 2015 geomagnetic storm that occurred at the summer solstice. There have been fewer intense geomagnetic storms during the current solar cycle, Solar Cycle 24, than in the previous cycle. This situation changed after mid-June 2015, when one of the largest solar active regions (AR 12371) of Solar Cycle 24 that was located close to the central meridian, produced several coronal mass ejections (CMEs) associated with M-class flares. The impact of these CMEs on the Earth's magnetosphere resulted in a moderate to severe G4-class geomagnetic storm on 22 - 23 June 2015 and a G2 (moderate) geomagnetic storm on 24 June. The G4 solstice storm was the second largest (so far) geomagnetic storm of Cycle 24. We highlight the ground-level observations made with the New-Tupi, Muonca, and the CARPET El Leoncito cosmic-ray detectors that are located within the South Atlantic Anomaly (SAA) region. These observations are studied in correlation with data obtained by space-borne detectors (ACE, GOES, SDO, and SOHO) and other ground-based experiments. The CME designations are taken from the Computer Aided CME Tracking (CACTus) automated catalog. As expected, Forbush decreases (FD) associated with the passing CMEs were recorded by these detectors. We note a peculiar feature linked to a severe geomagnetic storm event. The 21 June 2015 CME 0091 (CACTus CME catalog number) was likely associated with the 22 June summer solstice FD event. The angular width of CME 0091 was very narrow and measured {˜} 56° degrees seen from Earth. In most cases, only CME halos and partial halos lead to severe geomagnetic storms. We perform a cross-check analysis of the FD events detected during the rise phase of Solar Cycle 24, the geomagnetic parameters, and the CACTus CME catalog. Our study suggests that narrow angular-width CMEs that erupt in a westward direction from the Sun-Earth line can lead to moderate and severe geomagnetic storms. We also report on the strong solar proton

  2. Automated solar radio burst detection on radio spectrum: a review of ...

    African Journals Online (AJOL)

    By doing manual detection, human effort and error become the issues when the solar astronomer needs the fast and accurate result. Recently, the success of various techniques in image processing to identify solar radio burst automatically was presented. This paper reviews previous technique in image processing.

  3. SOLAR ENERGETIC PARTICLE EVENT ASSOCIATED WITH THE 2012 JULY 23 EXTREME SOLAR STORM

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Bei; Liu, Ying D.; Hu, Huidong; Wang, Rui; Yang, Zhongwei [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Luhmann, Janet G., E-mail: liuxying@spaceweather.ac.cn [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

    2016-08-20

    We study the solar energetic particle (SEP) event associated with the 2012 July 23 extreme solar storm, for which Solar Terrestrial Relations Observatory (STEREO) and the spacecraft at L1 provide multi-point remote sensing and in situ observations. The extreme solar storm, with a superfast shock and extremely enhanced ejecta magnetic fields observed near 1 au at STEREO A , was caused by the combination of successive coronal mass ejections (CMEs). Meanwhile, energetic particles were observed by STEREO and near-Earth spacecraft such as the Advanced Composition Explorer and SOlar and Heliospheric Observatory , suggesting a wide longitudinal spread of the particles at 1 au. Combining the SEP observations with in situ plasma and magnetic field measurements, we investigate the longitudinal distribution of the SEP event in connection with the associated shock and CMEs. Our results underscore the complex magnetic configuration of the inner heliosphere formed by solar eruptions. Examination of particle intensities, proton anisotropy distributions, element abundance ratios, magnetic connectivity, and spectra also gives important clues for particle acceleration, transport, and distribution.

  4. A model for radio emission from solar coronal shocks

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, G. Q.; Chen, L.; Wu, D. J., E-mail: djwu@pmo.ac.cn [Purple Mountain Observatory, CAS, Nanjing 210008 (China)

    2014-05-01

    Solar coronal shocks are very common phenomena in the solar atmosphere and are believed to be the drivers of solar type II radio bursts. However, the microphysical nature of these emissions is still an open question. This paper proposes that electron cyclotron maser (ECM) emission is responsible for the generation of radiation from the coronal shocks. In the present model, an energetic ion beam accelerated by the shock first excites the Alfvén wave (AW), then the excited AW leads to the formation of a density-depleted duct along the foreshock boundary of the shock. In this density-depleted duct, the energetic electron beam produced via the shock acceleration can effectively excite radio emission by ECM instability. Our results show that this model may potentially be applied to solar type II radio bursts.

  5. A model for radio emission from solar coronal shocks

    International Nuclear Information System (INIS)

    Zhao, G. Q.; Chen, L.; Wu, D. J.

    2014-01-01

    Solar coronal shocks are very common phenomena in the solar atmosphere and are believed to be the drivers of solar type II radio bursts. However, the microphysical nature of these emissions is still an open question. This paper proposes that electron cyclotron maser (ECM) emission is responsible for the generation of radiation from the coronal shocks. In the present model, an energetic ion beam accelerated by the shock first excites the Alfvén wave (AW), then the excited AW leads to the formation of a density-depleted duct along the foreshock boundary of the shock. In this density-depleted duct, the energetic electron beam produced via the shock acceleration can effectively excite radio emission by ECM instability. Our results show that this model may potentially be applied to solar type II radio bursts.

  6. RADIO EMISSION FROM ACCELERATION SITES OF SOLAR FLARES

    International Nuclear Information System (INIS)

    Li Yixuan; Fleishman, Gregory D.

    2009-01-01

    This Letter takes up the question of what radio emission is produced by electrons at the very acceleration site of a solar flare. Specifically, we calculate incoherent radio emission produced within two competing acceleration models-stochastic acceleration by cascading MHD turbulence and regular acceleration in collapsing magnetic traps. Our analysis clearly demonstrates that radio emission from acceleration sites (1) has sufficiently strong intensity to be observed by currently available radio instruments, and (2) has spectra and light curves that are distinctly different in these two competing models, which makes them observationally distinguishable. In particular, we suggest that some of the narrowband microwave and decimeter continuum bursts may be a signature of the stochastic acceleration in solar flares.

  7. The Distant Tail Behavior During High Speed Solar Wind Streams and Magnetic Storms

    Science.gov (United States)

    Ho, C. M.; Tsurutani, B. T.

    1996-01-01

    We have examined the ISEE-3 distant tail data during three intense (Dststorms and have identified the tail response to high speed solar wind streams, interplanetary magnetic clouds, and near-Earth storms. The three storms have a peak Dst ranging from -150 to -220 nT, and occur on Jan. 9, Feb. 4, and Aug. 8, 1993.

  8. Solar radio observations in support of Skylab A

    Science.gov (United States)

    Gotwols, B. L.

    1974-01-01

    The solar radio spectra were recorded in real time, both on film and magnetic tape, during the period from November 1972 to February 1974. A catalogue of the observations is given for the frequency range 565-1000 MHz and includes descriptions of the bursts, intensity scales, and pertinent remarks. Some theoretical considerations resulting from the research are given. Equipment modified for the experiment is described and the text of the final report which summarizes the research on type IV solar radio bursts is included.

  9. Morphology of geomagnetic storms, recorded at Hurbanovo, and its relation to solar activity

    International Nuclear Information System (INIS)

    Ochabova, P.; Psenakova, M.

    1977-01-01

    The morphological structure of geomagnetic storms was investigated using the data on 414 storms, recorded in the years 1949 to 1968 at the Geomagnetic Observatory of Hurbanovo (phi=47.9 deg N, lambda=18.2 deg E). These data also formed a suitable basis for investigating the effect of the solar activity on the characteristic features of storms. The storm-time variation of the geomagnetic field was considered after the Sq-variation had been eliminated. The sets of storms, i.e. 263 storms recorded at a time of high sunspot activity and 151 storms recorded at a time of low activity, were divided into 7 groups, depending on the duration of their initial phase. In 92% of the investigated storms the increase in the horizontal component lasted from 0 to 15 hrs. The effect of the solar activity was markedly reflected in the occurrence of very severe storms, as well as in the maximum decrease in the H-component in the main phase. This can also be seen in the rate at which the storms recover. (author)

  10. Statistical Analysis of Solar Events Associated with Storm Sudden Commencements over One Year of Solar Maximum During Cycle 23: Propagation from the Sun to the Earth and Effects

    Science.gov (United States)

    Bocchialini, K.; Grison, B.; Menvielle, M.; Chambodut, A.; Cornilleau-Wehrlin, N.; Fontaine, D.; Marchaudon, A.; Pick, M.; Pitout, F.; Schmieder, B.; Régnier, S.; Zouganelis, I.

    2018-05-01

    Taking the 32 storm sudden commencements (SSCs) listed by the International Service of Geomagnetic Indices (ISGI) of the Observatory de l'Ebre during 2002 (solar activity maximum in Cycle 23) as a starting point, we performed a multi-criterion analysis based on observations (propagation time, velocity comparisons, sense of the magnetic field rotation, radio waves) to associate them with solar sources, identified their effects in the interplanetary medium, and looked at the response of the terrestrial ionized and neutral environment. We find that 28 SSCs can be related to 44 coronal mass ejections (CMEs), 15 with a unique CME and 13 with a series of multiple CMEs, among which 19 (68%) involved halo CMEs. Twelve of the 19 fastest CMEs with speeds greater than 1000 km s-1 are halo CMEs. For the 44 CMEs, including 21 halo CMEs, the corresponding X-ray flare classes are: 3 X-class, 19 M-class, and 22 C-class flares. The probability for an SSC to occur is 75% if the CME is a halo CME. Among the 500, or even more, front-side, non-halo CMEs recorded in 2002, only 23 could be the source of an SSC, i.e. 5%. The complex interactions between two (or more) CMEs and the modification of their trajectories have been examined using joint white-light and multiple-wavelength radio observations. The detection of long-lasting type IV bursts observed at metric-hectometric wavelengths is a very useful criterion for the CME-SSC events association. The events associated with the most depressed Dst values are also associated with type IV radio bursts. The four SSCs associated with a single shock at L1 correspond to four radio events exhibiting characteristics different from type IV radio bursts. The solar-wind structures at L1 after the 32 SSCs are 12 magnetic clouds (MCs), 6 interplanetary coronal mass ejections (ICMEs) without an MC structure, 4 miscellaneous structures, which cannot unambiguously be classified as ICMEs, 5 corotating or stream interaction regions (CIRs/SIRs), one CIR

  11. Saturn radio emission and the solar wind - Voyager-2 studies

    International Nuclear Information System (INIS)

    Desch, M.D.; Rucker, H.O.; Observatorium Lustbuhel, Graz, Austria)

    1985-01-01

    Voyager 2 data from the Plasma Science experiment, the Magnetometer experiment and the Planetary Radio Astronomy experiment were used to analyze the relationship between parameters of the solar wind/interplanetary medium and the nonthermal Saturn radiation. Solar wind and interplanetary magnetic field properties were combined to form quantities known to be important in controlling terrestrial magnetospheric processes. The Voyager 2 data set used in this investigation consists of 237 days of Saturn preencounter measurements. However, due to the immersion of Saturn and the Voyager 2 spacecraft into the extended Jupiter magnetic tail, substantial periods of the time series were lacking solar wind data. To cope with this problem a superposed epoch method (CHREE analysis) was used. The results indicate the superiority of the quantities containing the solar wind density in stimulating the radio emission of Saturn - a result found earlier using Voyager 1 data - and the minor importance of quantities incorporating the interplanetary magnetic field. 10 references

  12. Solar Wind Features Responsible for Magnetic Storms and Substorms During the Declining Phase of the Solar Cycle: 197

    Science.gov (United States)

    Tsurutani, B.; Arballo, J.

    1994-01-01

    We examine interplanetary data and geomagnetic activity indices during 1974 when two long-lasting solar wind corotating streams existed. We find that only 3 major storms occurred during 1974, and all were associated with coronal mass ejections. Each high speed stream was led by a shock, so the three storms had sudden commencements. Two of the 1974 major storms were associated with shock compression of preexisting southward fields and one was caused by southward fields within a magnetic cloud. Corotating streams were responsible for recurring moderate to weak magnetic storms.

  13. Solar Plasma Radio Emission in the Presence of Imbalanced Turbulence of Kinetic-Scale Alfvén Waves

    Science.gov (United States)

    Lyubchyk, O.; Kontar, E. P.; Voitenko, Y. M.; Bian, N. H.; Melrose, D. B.

    2017-09-01

    We study the influence of kinetic-scale Alfvénic turbulence on the generation of plasma radio emission in the solar coronal regions where the ratio β of plasma to magnetic pressure is lower than the electron-to-ion mass ratio me/mi. The present study is motivated by the phenomenon of solar type I radio storms that are associated with the strong magnetic field of active regions. The measured brightness temperature of the type I storms can be up to 10^{10} K for continuum emission, and can exceed 10^{11} K for type I bursts. At present, there is no generally accepted theory explaining such high brightness temperatures and some other properties of the type I storms. We propose a model with an imbalanced turbulence of kinetic-scale Alfvén waves that produce an asymmetric quasi-linear plateau on the upper half of the electron velocity distribution. The Landau damping of resonant Langmuir waves is suppressed and their amplitudes grow spontaneously above the thermal level. The estimated saturation level of Langmuir waves is high enough to generate observed type I radio emission at the fundamental plasma frequency. Harmonic emission does not appear in our model because the backward-propagating Langmuir waves undergo strong Landau damping. Our model predicts 100% polarization in the sense of the ordinary (o-) mode of type I emission.

  14. AN IMAGING STUDY OF A COMPLEX SOLAR CORONAL RADIO ERUPTION

    Energy Technology Data Exchange (ETDEWEB)

    Feng, S. W.; Chen, Y.; Song, H. Q.; Wang, B.; Kong, X. L., E-mail: yaochen@sdu.edu.cn [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, and Institute of Space Sciences, Shandong University, Weihai, Shandong 264209 (China)

    2016-08-10

    Solar coronal radio bursts are enhanced radio emission excited by energetic electrons accelerated during solar eruptions. Studying these bursts is important for investigating the origin and physical mechanism of energetic particles and further diagnosing coronal parameters. Earlier studies suffered from a lack of simultaneous high-quality imaging data of the radio burst and the eruptive structure in the inner corona. Here we present a study on a complex solar radio eruption consisting of a type II burst and three reversely drifting type III bursts, using simultaneous EUV and radio imaging data. It is found that the type II burst is closely associated with a propagating and evolving CME-driven EUV shock structure, originated initially at the northern shock flank and later transferred to the top part of the shock. This source transfer is coincident with the presence of shock decay and enhancing signatures observed at the corresponding side of the EUV front. The electron energy accelerated by the shock at the flank is estimated to be ∼0.3 c by examining the imaging data of the fast-drifting herringbone structure of the type II burst. The reverse-drifting type III sources are found to be within the ejecta and correlated with a likely reconnection event therein. The implications for further observational studies and relevant space weather forecasting techniques are discussed.

  15. Gradient pattern analysis of short solar radio bursts

    Czech Academy of Sciences Publication Activity Database

    Rosa, R. R.; Karlický, Marian; Veronese, T.B.; Vijaykumar, N. L.; Sawant, H. S.; Borgazzi, A. I.; Dantas, M. S.; Barbosa, E. M. B.; Sych, R.A.; Mendes, O.

    2008-01-01

    Roč. 42, č. 5 (2008), s. 844-851 ISSN 0273-1177 Institutional research plan: CEZ:AV0Z10030501 Keywords : solar radio bursts * stochastic processes * wavelets Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.860, year: 2008

  16. Slowly varying component of extreme ultraviolet solar radiation and its relation to solar radio radiation

    Science.gov (United States)

    Chapman, R. D.; Neupert, W. M.

    1974-01-01

    A study of the correlations between solar EUV line fluxes and solar radio fluxes has been carried out. A calibration for the Goddard Space Flight Center EUV spectrum is suggested. The results are used to obtain an equation for the absolute EUV flux for several lines in the 150- to 400-A region and the total flux of 81 intense lines in the region, the 2800-MHz radio flux being used as independent variable.

  17. Solar radio bursts and their relation of coronal magnetic structures

    International Nuclear Information System (INIS)

    Kattenberg, A.

    1981-01-01

    Following a general introduction, chapters II and III describe a model for coronal flux tubes. The model tube is a cylindrically symmetric localized force free current, that is embedded in a potential field. In both chapters the growth rates and sizes of the kink mode instability are calculated by solving the linearized equation of motion. In chapters IV and V, observations of solar Type-I radio bursts are presented and analysed. The observations were gathered with the 60-channel radio spectrograph in Dwingeloo. Chapters VI, VII, VIII, IX and X are concerned with observations of solar microwave bursts. The observations, with high time resolution (0.1 s) and high one-dimensional angular resolution (max. 4'') were made with the Westerbork Synthesis Radio Telescope. (Auth.)

  18. Solar wind-magnetosphere coupling during intense magnetic storms (1978-1979)

    Science.gov (United States)

    Gonzalez, Walter D.; Gonzalez, Alicia L. C.; Tsurutani, Bruce T.; Smith, Edward J.; Tang, Frances

    1989-01-01

    The solar wind-magnetosphere coupling problem during intense magnetic storms was investigated for ten intense magnetic storm events occurring between August 16, 1978 to December 28, 1979. Particular attention was given to the dependence of the ring current energization on the ISEE-measured solar-wind parameters and the evolution of the ring current during the main phase of the intense storms. Several coupling functions were tested as energy input, and several sets of the ring current decay time-constant were searched for the best correlation with the Dst response. Results indicate that a large-scale magnetopause reconnection operates during an intense storm event and that the solar wind ram pressure plays an important role in the energization of the ring current.

  19. Ground-based solar radio observations of the August 1972 events

    International Nuclear Information System (INIS)

    Bhonsle, R.V.; Degaonkar, S.S.; Alurkar, S.K.

    1976-01-01

    Ground-based observations of the variable solar radio emission ranging from few millimetres to decametres have been used here as a diagnostic tool to gain coherent phenomenological understanding of the great 2, 4 and 7 August, 1972 solar events in terms of dominant physical processes like generation and propagation of shock waves in the solar atmosphere, particle acceleration and trapping. Four major flares are selected for detailed analysis on the basis of their ability to produce energetic protons, shock waves, polar cap absorptions (PCA) and sudden commencement (SC) geomagnetic storms. A comparative study of their radio characteristics is made. Evidence is seen for the pulsations during microwave bursts by the mechanism similar to that proposed by McLean et al. (1971), to explain the pulsations in the metre wavelength continuum radiation. It is suggested that the multiple peaks observed in some microwave bursts may be attributable to individual flares occurring sequentially due to a single initiating flare. Attempts have been made to establish identification of Type II bursts with the interplanetary shock waves and SC geomagnetic storms. Furthermore, it is suggested that it is the mass behind the shock front which is the deciding factor for the detection of shock waves in the interplantary space. It appears that more work is necessary in order to identify which of the three moving Type IV bursts (Wild and Smerd, 1972), namely, advancing shock front, expanding magnetic arch and ejected plasma blob serves as the piston-driver behind the interplanetary shocks. The existing criteria for proton flare prediction have been summarized and two new criteria have been proposed. (Auth.)

  20. Solar radio proxies for improved satellite orbit prediction

    Science.gov (United States)

    Yaya, Philippe; Hecker, Louis; Dudok de Wit, Thierry; Fèvre, Clémence Le; Bruinsma, Sean

    2017-12-01

    Specification and forecasting of solar drivers to thermosphere density models is critical for satellite orbit prediction and debris avoidance. Satellite operators routinely forecast orbits up to 30 days into the future. This requires forecasts of the drivers to these orbit prediction models such as the solar Extreme-UV (EUV) flux and geomagnetic activity. Most density models use the 10.7 cm radio flux (F10.7 index) as a proxy for solar EUV. However, daily measurements at other centimetric wavelengths have also been performed by the Nobeyama Radio Observatory (Japan) since the 1950's, thereby offering prospects for improving orbit modeling. Here we present a pre-operational service at the Collecte Localisation Satellites company that collects these different observations in one single homogeneous dataset and provides a 30 days forecast on a daily basis. Interpolation and preprocessing algorithms were developed to fill in missing data and remove anomalous values. We compared various empirical time series prediction techniques and selected a multi-wavelength non-recursive analogue neural network. The prediction of the 30 cm flux, and to a lesser extent that of the 10.7 cm flux, performs better than NOAA's present prediction of the 10.7 cm flux, especially during periods of high solar activity. In addition, we find that the DTM-2013 density model (Drag Temperature Model) performs better with (past and predicted) values of the 30 cm radio flux than with the 10.7 flux.

  1. Wavelet Based Characterization of Low Radio Frequency Solar Emissions

    Science.gov (United States)

    Suresh, A.; Sharma, R.; Das, S. B.; Oberoi, D.; Pankratius, V.; Lonsdale, C.

    2016-12-01

    Low-frequency solar radio observations with the Murchison Widefield Array (MWA) have revealed the presence of numerous short-lived, narrow-band weak radio features, even during quiet solar conditions. In their appearance in in the frequency-time plane, they come closest to the solar type III bursts, but with much shorter spectral spans and flux densities, so much so that they are not detectable with the usual swept frequency radio spectrographs. These features occur at rates of many thousand features per hour in the 30.72 MHz MWA bandwidth, and hence necessarily require an automated approach to determine robust statistical estimates of their properties, e.g., distributions of spectral widths, temporal spans, flux densities, slopes in the time-frequency plane and distribution over frequency. To achieve this, a wavelet decomposition approach has been developed for feature recognition and subsequent parameter extraction from the MWA dynamic spectrum. This work builds on earlier work by the members of this team to achieve a reliable flux calibration in a computationally efficient manner. Preliminary results show that the distribution of spectral span of these features peaks around 3 MHz, most of them last for less than two seconds and are characterized by flux densities of about 60% of the background solar emission. In analogy with the solar type III bursts, this non-thermal emission is envisaged to arise via coherent emission processes. There is also an exciting possibility that these features might correspond to radio signatures of nanoflares, hypothesized (Gold, 1964; Parker, 1972) to explain coronal heating.

  2. Coronal mass ejections and solar radio bursts

    International Nuclear Information System (INIS)

    Kundu, M.R.

    1990-01-01

    The properties of coronal mass ejection (CME) events and their radio signatures are discussed. These signatures are mostly in the form of type II and type IV burst emissions. Although type II bursts are temporally associated with CMEs, it is shown that there is no spatial relationship between them. Type II's associated with CMEs have in most cases a different origin, and they are not piston-driven by CMEs. Moving type IV and type II bursts can be associated with slow CMEs with speeds as low as 200 km/s, contrary to the earlier belief that only CMEs with speeds >400 km/s are associated with radio bursts. A specific event has been discussed in which the CME and type IV burst has nearly the same speed and direction, but the type II burst location was behind the CME and its motion was transverse. The speed and motion of the type II burst strongly suggest that the type II shock was decoupled from the CME and was probably due to a flare behind the limb. Therefore only the type IV source could be directly associated with the slow CME. The electrons responsble for the type IV emission could be produced in the flare or in the type II and then become trapped in a plasmoid associated with the CME. The reconnected loop could then move outwards as in the usual palsmoid model. Alternatively, the type IV emission could be interpreted as due to electrons produced by acceleration in wave turbulence driven by currents in the shock front driven by the CME. The lower-hybrid model Lampe and Papadopoulos (1982), which operates at both fast and slow mode shocks, could be applied to this situation. (author). 31 refs., 12 figs

  3. 3DCORE: Forward modeling of solar storm magnetic flux ropes for space weather prediction

    Science.gov (United States)

    Möstl, C.; Amerstorfer, T.; Palmerio, E.; Isavnin, A.; Farrugia, C. J.; Lowder, C.; Winslow, R. M.; Donnerer, J. M.; Kilpua, E. K. J.; Boakes, P. D.

    2018-05-01

    3DCORE forward models solar storm magnetic flux ropes called 3-Dimensional Coronal Rope Ejection (3DCORE). The code is able to produce synthetic in situ observations of the magnetic cores of solar coronal mass ejections sweeping over planets and spacecraft. Near Earth, these data are taken currently by the Wind, ACE and DSCOVR spacecraft. Other suitable spacecraft making these kind of observations carrying magnetometers in the solar wind were MESSENGER, Venus Express, MAVEN, and even Helios.

  4. The application of coronal scattering measurements to solar radio bursts

    International Nuclear Information System (INIS)

    Bradford, H.M.

    1980-01-01

    The interpretation of ground based observations of solar 'plasma frequency' radio bursts has been hampered in the past by an insufficient knowledge of coronal scattering by density inhomogeneities close to the Sun. Calculations based on measuurements of the angular broadening of natural radio sources, and Woo's 1975 measurement of the angular broadening of the telemetry carrier by Helios I near occultation (Woo, 1978), indicate that plasma frequency solar bursts should undergo considerable scattering, at least near the maximum of the sunspot cycle. The calculated displacements of the apparent positions of the bursts are about equal to the observed displacements which have been attributed to the bursts occurring in dense streamers. In order to obtain more scattering data close to the Sun, interferometer measurements of the angular broadening of spacecraft signals are planned, and the important contribution which could be made with large dishes is discussed. (Auth.)

  5. Physics of the Solar Active Regions from Radio Observations

    Science.gov (United States)

    Gelfreikh, G. B.

    1999-12-01

    Localized increase of the magnetic field observed by routine methods on the photosphere result in the growth of a number of active processes in the solar atmosphere and the heliosphere. These localized regions of increased magnetic field are called active regions (AR). The main processes of transfer, accumulation and release of energy in an AR is, however, out of scope of photospheric observations being essentially a 3D-process and happening either under photosphere or up in the corona. So, to investigate these plasma structures and processes we are bound to use either extrapolation of optical observational methods or observations in EUV, X-rays and radio. In this review, we stress and illustrate the input to the problem gained from radio astronomical methods and discuss possible future development of their applicatications. Historically speaking each new step in developing radio technique of observations resulted in detecting some new physics of ARs. The most significant progress in the last few years in radio diagnostics of the plasma structures of magnetospheres of the solar ARs is connected with the developing of the 2D full disk analysis on regular basis made at Nobeyama and detailed multichannel spectral-polarization (but one-dimensional and one per day) solar observations at the RATAN-600. In this report the bulk of attention is paid to the new approach to the study of solar activity gained with the Nobeyama radioheliograph and analyzing the ways for future progress. The most important new features of the multicomponent radio sources of the ARs studied using Nobeyama radioheliograph are as follow: 1. The analysis of magnetic field structures in solar corona above sunspot with 2000 G. Their temporal evolution and fluctuations with the periods around 3 and 5 minutes, due to MHD-waves in sunspot magnetic tubes and surrounding plasma. These investigations are certainly based on an analysis of thermal cyclotron emission of lower corona and CCTR above sunspot

  6. Low-dimensionality and predictability of solar wind and global magnetosphere during magnetic storms

    OpenAIRE

    Zivkovic, Tatjana; Rypdal, Kristoffer

    2011-01-01

    This article is part of Tatjana Živkovics' doctoral thesis. Available in Munin at http://hdl.handle.net/10037/3231 The storm index SYM-H, the solar wind velocity v, and interplanetary magnetic field Bz show no signatures of low-dimensional dynamics in quiet periods, but tests for determinism in the time series indicate that SYM-H exhibits a significant low-dimensional component during storm time, suggesting that self-organization takes place during magnetic storms. Even though our analysis...

  7. Two-Step Forecast of Geomagnetic Storm Using Coronal Mass Ejection and Solar Wind Condition

    Science.gov (United States)

    Kim, R.-S.; Moon, Y.-J.; Gopalswamy, N.; Park, Y.-D.; Kim, Y.-H.

    2014-01-01

    To forecast geomagnetic storms, we had examined initially observed parameters of coronal mass ejections (CMEs) and introduced an empirical storm forecast model in a previous study. Now we suggest a two-step forecast considering not only CME parameters observed in the solar vicinity but also solar wind conditions near Earth to improve the forecast capability. We consider the empirical solar wind criteria derived in this study (Bz = -5 nT or Ey = 3 mV/m for t = 2 h for moderate storms with minimum Dst less than -50 nT) (i.e. Magnetic Field Magnitude, B (sub z) less than or equal to -5 nanoTeslas or duskward Electrical Field, E (sub y) greater than or equal to 3 millivolts per meter for time greater than or equal to 2 hours for moderate storms with Minimum Disturbance Storm Time, Dst less than -50 nanoTeslas) and a Dst model developed by Temerin and Li (2002, 2006) (TL [i.e. Temerin Li] model). Using 55 CME-Dst pairs during 1997 to 2003, our solar wind criteria produce slightly better forecasts for 31 storm events (90 percent) than the forecasts based on the TL model (87 percent). However, the latter produces better forecasts for 24 nonstorm events (88 percent), while the former correctly forecasts only 71 percent of them. We then performed the two-step forecast. The results are as follows: (i) for 15 events that are incorrectly forecasted using CME parameters, 12 cases (80 percent) can be properly predicted based on solar wind conditions; (ii) if we forecast a storm when both CME and solar wind conditions are satisfied (n, i.e. cap operator - the intersection set that is comprised of all the elements that are common to both), the critical success index becomes higher than that from the forecast using CME parameters alone, however, only 25 storm events (81 percent) are correctly forecasted; and (iii) if we forecast a storm when either set of these conditions is satisfied (?, i.e. cup operator - the union set that is comprised of all the elements of either or both

  8. Solar wind-magnetosphere coupling during intense magnetic storms (1978--1979)

    International Nuclear Information System (INIS)

    Gonzalez, W.D.; Tsurutani, B.T.; Gonzalez, A.L.C.; Smith, E.J.; Tang, F.; Akasofu, S.

    1989-01-01

    The solar wind-magnetosphere coupling problem is investigated for the ten intense magnetic storms (Dst <-100 nT) that occurred during the 500 days (August 16, 1978 to December 28, 1979) studied by Gonzalez and Tsurutani [1987]. This investigation concentrates on the ring current energization in terms of solar wind parameters, in order to explain the | -Dst | growth observed during these storms. Thus several coupling functions are tested as energy input and several sets of the ring current decay time-constant τ are searched to find best correlations with the Dst response. From the fairly large correlation coefficients found in this study, there is strong evidence that large scale magnetopause reconnection operates during such intense storm events and that the solar wind ram pressure plays an important role in the ring current energization. Thus a ram pressure correction factor is suggested for expressions concerning the reconnection power during time intervals with large ram pressure variations

  9. The effect of solar radio bursts on the GNSS radio occultation signals

    Science.gov (United States)

    Yue, Xinan; Schreiner, William S.; Kuo, Ying-Hwa; Zhao, Biqiang; Wan, Weixing; Ren, Zhipeng; Liu, Libo; Wei, Yong; Lei, Jiuhou; Solomon, Stan; Rocken, Christian

    2013-09-01

    radio burst (SRB) is the radio wave emission after a solar flare, covering a broad frequency range, originated from the Sun's atmosphere. During the SRB occurrence, some specific frequency radio wave could interfere with the Global Navigation Satellite System (GNSS) signals and therefore disturb the received signals. In this study, the low Earth orbit- (LEO-) based high-resolution GNSS radio occultation (RO) signals from multiple satellites (COSMIC, CHAMP, GRACE, SAC-C, Metop-A, and TerraSAR-X) processed in University Corporation for Atmospheric Research (UCAR) were first used to evaluate the effect of SRB on the RO technique. The radio solar telescope network (RSTN) observed radio flux was used to represent SRB occurrence. An extreme case during 6 December 2006 and statistical analysis during April 2006 to September 2012 were studied. The LEO RO signals show frequent loss of lock (LOL), simultaneous decrease on L1 and L2 signal-to-noise ratio (SNR) globally during daytime, small-scale perturbations of SNR, and decreased successful retrieval percentage (SRP) for both ionospheric and atmospheric occultations during SRB occurrence. A potential harmonic band interference was identified. Either decreased data volume or data quality will influence weather prediction, climate study, and space weather monitoring by using RO data during SRB time. Statistically, the SRP of ionospheric and atmospheric occultation retrieval shows ~4% and ~13% decrease, respectively, while the SNR of L1 and L2 show ~5.7% and ~11.7% decrease, respectively. A threshold value of ~1807 SFU of 1415 MHz frequency, which can result in observable GNSS SNR decrease, was derived based on our statistical analysis.

  10. Statistical Analysis of Solar Events Associated with Storm Sudden Commencements over One Year of Solar Maximum during Cycle 23: Propagation and Effects from the Sun to the Earth.

    Science.gov (United States)

    Bocchialini, K.; Grison, B.; Menvielle, M.; Chambodut, A.; Cornilleau-Wehrlin, N.; Fontaine, D.; Marchaudon, A.; Pick, M.; Pitout, F.; Schmieder, B.; Régnier, S.; Zouganelis, I.

    2017-12-01

    From the list of 32 SSCs over the year 2002, we performed a multi-criteria analysis based on propagation time, velocity comparison, sense of the magnetic field rotation, radio waves to associate them with solar sources, identify their causes in the interplanetary medium and then look at the response of the terrestrial ionized and neutral environment to them. The complex interactions between two (or more) CMEs and the modification in their trajectory have been examined using joint white light and multiple-wavelength radio observations. The structures at L_1 after the 32 SSCs are regarded as Magnetic Clouds (MCs), ICMEs without a MC structure, Miscellaneous structures, CIRs/SIRs, and shock-only events. In terms of geoeffectivity, generally CMEs with velocities at the Sun larger than 1000 km.s-1 have larger probabilities to trigger moderate or intense storms. The most geoeffective events are MCs, since 92% of them trigger moderate or intense storms. The geoeffective events trigger an increased and combined AKR and NTC wave activity in the magnetosphere, an enhanced convection in the ionosphere and a stronger response in the thermosphere.

  11. Solar--geophysical data number 406, June 1978, Part I. (prompt reports). Data for May 1978, April 1978

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1978-06-01

    This prompt report provides data for May 1978 on: alert period, daily solar indices, solar flares, solar radio waves, solar x-ray radiation, coronal holes, inferred IP Magnetic field polarities, mean solar magnetic field, solar wind measurements, geomagnetic substorms, magnetograms of geomagnetic storm 30 April - 4 May, and energetic solar particles. It also provides data for April 1978 on: daily solar activity center, sudden ionospheric disturbances, solar x-ray radiation, solar radio waves, cosmic rays, geomagnetic indices, and radio propagation

  12. First solar radio spectrometer deployed in Scotland, UK

    Science.gov (United States)

    Monstein, Christian

    2012-10-01

    A new Callisto solar radio spectrometer system has recently been installed and set into operation at Acre Road Observatory, a facility of University of Glasgow, Scotland UK. There has been an Observatory associated with Glasgow University since 1757, and they presently occupy two different sites. The main observatory ('Acre Road') is close to the Garscube Estate on the outskirts of the city of Glasgow. The outstation ('Cochno', housing the big 20 inch Grubb Parsons telescope) is located farther out at a darker site in the Kilpatrick Hills. The Acre Road Observatory comprises teaching and research labs, a workshop, the main dome housing the 16 inch Meade, the solar dome, presently housing the 12 inch Meade, a transit house containing the transit telescope, a 3m HI radio telescope and a 408 MHz pulsar telescope. They also have 10 and 8 inch Meade telescopes and several 5 inch Celestron instruments. There is a small planetarium beneath the solar dome. The new Callisto instrument is mainly foreseen for scientific solar burst observations as well as for student projects and for 'bad-weather' outreach activities.

  13. On the statistics of the largest geomagnetic storms per solar cycle

    International Nuclear Information System (INIS)

    Siscoe, G.L.

    1976-01-01

    The theory of extreme value statistics is applied to the first, second, and third largest geomagnetic storms in nine solar cycles measured by the average half-daily aa indices compiled by Mayaud. Analytic expressions giving the probability of the extremes per solar cycle as a contour function of storm magnitude are obtained by least squares fitting of the observations to the appropriate theoretical extreme value probability functions. The results are used to obtain the statistical characteristics (mode, median, mean, and standard deviation) for the extreme values. The results are applied to find the expected range of extreme values in a set as a function of the number of solar cycles in the set. We find that the expected range of the largest storm is quite narrow and is larger for the second and third largest storms. The observed range of the extreme half-daily aa index for the nine solar cycles is 354--546 γ. In a set of 100 cycles the range is expanded esentially to 311--680γ, an increase of only 39% in the range. The result supports the argument for a change in solar cycle statistics in the latter part of the Seventeenth Century (the Maunder minimum)

  14. Global ionospheric effects of geomagnetic storm on May 2-3, 2010 and their influence on HF radio wave propagation

    Science.gov (United States)

    Kotova, Daria; Klimenko, Maxim; Klimenko, Vladimir; Zakharov, Veniamin

    2013-04-01

    In this work we have investigated the global ionospheric response to geomagnetic storm on May 2-3, 2010 using GSM TIP (Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere) simulation results. In the GSM TIP storm time model runs, several input parameters such as cross-polar cap potential difference and R2 FAC (Region 2 Field-Aligned Currents) varied as a function of the geomagnetic activity AE-index. Current simulation also uses the empirical model of high-energy particle precipitation by Zhang and Paxton. In this model, the energy and energy flux of precipitating electrons depend on a 3 hour Kp-index. We also have included the 30 min time delay of R2 FAC variations with respect to the variations of cross-polar cap potential difference. In addition, we use the ground-based ionosonde data for comparison our model results with observations. We present an analysis of the physical mechanisms responsible for the ionospheric effects of geomagnetic storms. The obtained simulation results are used by us as a medium for HF radio wave propagation at different latitudes in quiet conditions, and during main and recovery phase of a geomagnetic storm. To solve the problem of the radio wave propagation we used Zakharov's (I. Kant BFU) model based on geometric optics. In this model the solution of the eikonal equation for each of the two normal modes is reduced using the method of characteristics to the integration of the six ray equation system for the coordinates and momentum. All model equations of this system are solved in spherical geomagnetic coordinate system by the Runge-Kutta method. This model was tested for a plane wave in a parabolic layer. In this study, the complex refractive indices of the ordinary and extraordinary waves at ionospheric heights was calculated for the first time using the global first-principal model of the thermosphere-ionosphere system that describes the parameters of an inhomogeneous anisotropic medium during a

  15. Solar radio proxies for improved satellite orbit prediction

    Directory of Open Access Journals (Sweden)

    Yaya Philippe

    2017-01-01

    Full Text Available Specification and forecasting of solar drivers to thermosphere density models is critical for satellite orbit prediction and debris avoidance. Satellite operators routinely forecast orbits up to 30 days into the future. This requires forecasts of the drivers to these orbit prediction models such as the solar Extreme-UV (EUV flux and geomagnetic activity. Most density models use the 10.7 cm radio flux (F10.7 index as a proxy for solar EUV. However, daily measurements at other centimetric wavelengths have also been performed by the Nobeyama Radio Observatory (Japan since the 1950's, thereby offering prospects for improving orbit modeling. Here we present a pre-operational service at the Collecte Localisation Satellites company that collects these different observations in one single homogeneous dataset and provides a 30 days forecast on a daily basis. Interpolation and preprocessing algorithms were developed to fill in missing data and remove anomalous values. We compared various empirical time series prediction techniques and selected a multi-wavelength non-recursive analogue neural network. The prediction of the 30 cm flux, and to a lesser extent that of the 10.7 cm flux, performs better than NOAA's present prediction of the 10.7 cm flux, especially during periods of high solar activity. In addition, we find that the DTM-2013 density model (Drag Temperature Model performs better with (past and predicted values of the 30 cm radio flux than with the 10.7 flux.

  16. Time Delay Between Dst Index and Magnetic Storm Related Structure in the Solar Wind

    Science.gov (United States)

    Osherovich, Vladimir A.; Fainberg, Joseph

    2015-01-01

    Benson et al. (2015, this volume) selected 10 large magnetic storms, with associated Dst minimum values less than or equal to -100 nT, for which high-latitude topside ionospheric electron density profiles are available from topside-sounder satellites. For these 10 storms, we performed a superposition of Dst and interplanetary parameters B, v, N(sub p) and T(sub p). We have found that two interplanetary parameters, namely B and v, are sufficient to reproduce Dst with correlation coefficient cc approximately 0.96 provided that the interplanetary parameter times are taken 0.15 days earlier than the associated Dst times. Thus we have found which part of the solar wind is responsible for each phase of the magnetic storm. This result is also verified for individual storms as well. The total duration of SRS (storm related structure in the solar wind) is 4 - 5 days which is the same as the associated Dst interval of the magnetic storm.

  17. Aperture synthesis observations of solar and stellar radio emission

    International Nuclear Information System (INIS)

    Bastian, T.S.

    1987-01-01

    The work presented in this thesis relied upon the radio astronomical instrument, The Very Large Array. The thesis is divided into three major sections. In the first the author applied maximum entropy-type image reconstruction techniques, using both single dish and iterferometer data, to generate full disk images of the Sun at a wavelength λ ∼ 21 cm. Using a set of six such images obtained during the Sun's decline from sunspot maximum to minimum, he has noted a number of previously unreported phenomena. Among these: (1) a systematic decrease in quiet Sun's brightness temperature as it declined to minimum; (2) a systematic decrease in the Sun's radius at 21 cm; (3) evidence for the evolution of polar coronal holes during the course of the solar cycle. The observed variation, though not noted previously at radio wavelengths, is entirely consistent with white light K coronagraph data. The results reported here explain the conflicting nature of a number of past observations. In the second section of the thesis, he presents the results of a long term survey of magnetic cataclysmic variables (CVs). Cataclysmic variables are close binary systems which contain a white dwarf accreting mass from a late-type secondary, typically a dwarf of spectral type, G, K, or M. The survey resulted in the detection of two out of the eighteen systems observed. In the third section of the thesis, he presents new results on flare stars in the solar neighborhood and in the Pleiades. He has successfully employed the technique of dynamic spectroscopy to constrain the mechanisms(s) for radio flaring on other stars. The second part of section three is devoted to a search for radio emission from flare stars in the Pleiades which was motivated by the evolutionary questions raised by flare stars and the Pleiades lower main sequence

  18. Variation of Magnetic Field (By , Bz Polarity and Statistical Analysis of Solar Wind Parameters during the Magnetic Storm Period

    Directory of Open Access Journals (Sweden)

    Ga-Hee Moon

    2011-06-01

    Full Text Available It is generally believed that the occurrence of a magnetic storm depends upon the solar wind conditions, particularly the southward interplanetary magnetic field (IMF component. To understand the relationship between solar wind parameters and magnetic storms, variations in magnetic field polarity and solar wind parameters during magnetic storms are examined. A total of 156 storms during the period of 1997~2003 are used. According to the interplanetary driver, magnetic storms are divided into three types, which are coronal mass ejection (CME-driven storms, co-rotating interaction region (CIR-driven storms, and complicated type storms. Complicated types were not included in this study. For this purpose, the manner in which the direction change of IMF By and Bz components (in geocentric solar magnetospheric coordinate system coordinate during the main phase is related with the development of the storm is examined. The time-integrated solar wind parameters are compared with the time-integrated disturbance storm time (Dst index during the main phase of each magnetic storm. The time lag with the storm size is also investigated. Some results are worth noting: CME-driven storms, under steady conditions of Bz < 0, represent more than half of the storms in number. That is, it is found that the average number of storms for negative sign of IMF Bz (T1~T4 is high, at 56.4%, 53.0%, and 63.7% in each storm category, respectively. However, for the CIR-driven storms, the percentage of moderate storms is only 29.2%, while the number of intense storms is more than half (60.0% under the Bz < 0 condition. It is found that the correlation is highest between the time-integrated IMF Bz and the time-integrated Dst index for the CME-driven storms. On the other hand, for the CIR-driven storms, a high correlation is found, with the correlation coefficient being 0.93, between time-integrated Dst index and time-integrated solar wind speed, while a low correlation, 0.51, is

  19. STUDY OF CALIBRATION OF SOLAR RADIO SPECTROMETERS AND THE QUIET-SUN RADIO EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Chengming; Yan, Yihua; Tan, Baolin; Fu, Qijun; Liu, Yuying [Key Laboratory of Solar Activity, National Astronomical Observatories of Chinese Academy of Sciences, Datun Road A20, Chaoyang District, Beijing 100012 (China); Xu, Guirong [Hubei Key Laboratory for Heavy Rain Monitoring and Warning Research, Institute of Heavy Rain, China Meteorological Administration, Wuhan 430205 (China)

    2015-07-20

    This work presents a systematic investigation of the influence of weather conditions on the calibration errors by using Gaussian fitness, least chi-square linear fitness, and wavelet transform to analyze the calibration coefficients from observations of the Chinese Solar Broadband Radio Spectrometers (at frequency bands of 1.0–2.0 GHz, 2.6–3.8 GHz, and 5.2–7.6 GHz) during 1997–2007. We found that calibration coefficients are influenced by the local air temperature. Considering the temperature correction, the calibration error will reduce by about 10%–20% at 2800 MHz. Based on the above investigation and the calibration corrections, we further study the radio emission of the quiet Sun by using an appropriate hybrid model of the quiet-Sun atmosphere. The results indicate that the numerical flux of the hybrid model is much closer to the observation flux than that of other ones.

  20. Radio Remote Sensing of Coronal Mass Ejections: Implications for Parker Solar Probe and Solar Orbiter

    Science.gov (United States)

    Kooi, J. E.; Thomas, N. C.; Guy, M. B., III; Spangler, S. R.

    2017-12-01

    Coronal mass ejections (CMEs) are fast-moving magnetic field structures of enhanced plasma density that play an important role in space weather. The Solar Orbiter and Parker Solar Probe will usher in a new era of in situ measurements, probing CMEs within distances of 60 and 10 solar radii, respectively. At the present, only remote-sensing techniques such as Faraday rotation can probe the plasma structure of CMEs at these distances. Faraday rotation is the change in polarization position angle of linearly polarized radiation as it propagates through a magnetized plasma (e.g. a CME) and is proportional to the path integral of the electron density and line-of-sight magnetic field. In conjunction with white-light coronagraph measurements, Faraday rotation observations have been used in recent years to determine the magnetic field strength of CMEs. We report recent results from simultaneous white-light and radio observations made of a CME in July 2015. We made radio observations using the Karl G. Jansky Very Large Array (VLA) at 1 - 2 GHz frequencies of a set of radio sources through the solar corona at heliocentric distances that ranged between 8 - 23 solar radii. These Faraday rotation observations provide a priori estimates for comparison with future in situ measurements made by the Solar Orbiter and Parker Solar Probe. Similar Faraday rotation observations made simultaneously with observations by the Solar Orbiter and Parker Solar Probe in the future could provide information about the global structure of CMEs sampled by these probes and, therefore, aid in understanding the in situ measurements.

  1. Solar radiophysics

    International Nuclear Information System (INIS)

    McLean, D.J.; Labrum, N.R.

    1985-01-01

    This book treats all aspects of solar radioastronomy at metre wavelengths, particularly work carried out on the Australian radioheliograph at Culgoora, with which most of the authors have been associated in one way or another. After an introductory section on historical aspects, the solar atmosphere, solar flares, and coronal radio emission, the book deals with instrumentation, theory, and details of observations and interpretations of the various aspects of metrewave solar radioastronomy, including burst types, solar storms, and the quiet sun. (U.K.)

  2. Type III-L Solar Radio Bursts and Solar Energetic Particle Events

    International Nuclear Information System (INIS)

    Duffin, R T; White, S M; Ray, P S; Kaiser, M L

    2015-01-01

    A radio-selected sample of fast drift radio bursts with complex structure occurring after the impulsive phase of the associated flare (“Type III-L bursts”) is identified by inspection of radio dynamic spectra from 1 to 180 MHz for over 300 large flares in 2001. An operational definition that takes into account previous work on these radio bursts starting from samples of solar energetic particle (SEP) events is applied to the data, and 66 Type III-L bursts are found in the sample. In order to determine whether the presence of these radio bursts can be used to predict the occurrence of SEP events, we also develop a catalog of all SEP proton events in 2001 using data from the ERNE detector on the SOHO satellite. 68 SEP events are found, for 48 of which we can identify a solar source and hence look for associated Type III-L emission. We confirm previous work that found that most (76% in our sample) of the solar sources of SEP events exhibit radio emission of this type. However, the correlation in the opposite direction is not as strong: starting from a radio-selected sample of Type III-L events, around 64% of the bursts that occur at longitudes magnetically well-connected to the Earth, and hence favorable for detection of SEPs, are associated with SEP events. The degree of association increases when the events have durations over 10 minutes at 1 MHz, but in general Type III-L bursts do not perform any better than Type II bursts in our sample as predictors of SEP events. A comparison of Type III-L timing with the arrival of near-relativistic electrons at the ACE spacecraft is not inconsistent with a common source for the accelerated electrons in both phenomena. (paper)

  3. Type III-L Solar Radio Bursts and Solar Energetic Particle Events

    Science.gov (United States)

    Duffin, R. T.; White, S. M.; Ray, P. S.; Kaiser, M. L.

    2015-09-01

    A radio-selected sample of fast drift radio bursts with complex structure occurring after the impulsive phase of the associated flare (“Type III-L bursts”) is identified by inspection of radio dynamic spectra from 1 to 180 MHz for over 300 large flares in 2001. An operational definition that takes into account previous work on these radio bursts starting from samples of solar energetic particle (SEP) events is applied to the data, and 66 Type III-L bursts are found in the sample. In order to determine whether the presence of these radio bursts can be used to predict the occurrence of SEP events, we also develop a catalog of all SEP proton events in 2001 using data from the ERNE detector on the SOHO satellite. 68 SEP events are found, for 48 of which we can identify a solar source and hence look for associated Type III-L emission. We confirm previous work that found that most (76% in our sample) of the solar sources of SEP events exhibit radio emission of this type. However, the correlation in the opposite direction is not as strong: starting from a radio-selected sample of Type III-L events, around 64% of the bursts that occur at longitudes magnetically well-connected to the Earth, and hence favorable for detection of SEPs, are associated with SEP events. The degree of association increases when the events have durations over 10 minutes at 1 MHz, but in general Type III-L bursts do not perform any better than Type II bursts in our sample as predictors of SEP events. A comparison of Type III-L timing with the arrival of near-relativistic electrons at the ACE spacecraft is not inconsistent with a common source for the accelerated electrons in both phenomena.

  4. Gnevyshev peaks in solar radio emissions at different frequencies

    Directory of Open Access Journals (Sweden)

    R. P. Kane

    2009-04-01

    Full Text Available Sunspots have a major 11-year cycle, but the years near the sunspot maximum show two or more peaks called GP (Gnevyshev Peaks. In this communication, it was examined whether these peaks in sunspots are reflected in other parameters such as Lyman-α (the chromospheric emission 121.6 nm, radio emissions 242–15 400 MHz emanating from altitude levels 2000–12 000 km, the low latitude (+45° to −45° solar open magnetic flux and the coronal green line emission (Fe XIV, 530.3 nm. In the different solar cycles 20–23, the similarity extended at least upto the level of 609 MHz, but in cycle 22, the highest level was of 242 MHz. The extension to the higher level in cycle 22 does not seem to be related to the cycle strength Rz(max, or to the cycle length.

  5. What is the Relationship between the Solar Wind and Storms/Substorms?

    Science.gov (United States)

    Fairfield, D. H.; Burlaga, L. F.

    1999-01-01

    The interplanetary magnetic field (IMF) carried past the Earth by the solar wind has long been known to be the principal quantity that controls geomagnetic storms and substorms. Intervals of strong southward IMF with durations of at least a significant fraction of a day produce storms, while more typical, shorter intervals of less-intense southward fields produce substorms. The strong, long-duration southward fields are generally associated with coronal mass ejections and magnetic clouds or else they are produced by interplanetary dynamics initiated by fast solar wind flows that compress preexisting southward fields. Smaller, short-duration southward fields that occur on most days are related to long period waves, turbulence, or random variations in the IMF. Southward IMF enhances dayside reconnection between the IMF and the Earth's dipole with the reconnected field lines supplementing open field lines of the geomagnetic tail and producing an expanded polar cap and increased tail energy. Although the frequent storage of solar wind energy and its release during substorms is the most common mode of solar wind/magnetosphere interaction, under certain circumstances, steady southward IMF seems to produce intervals of relatively steady magnetosphere convection without substorms. During these latter times, the inner magnetosphere remains in a stressed tail-like state while the more distant magnetotail has larger northward field and more dipolar-like field lines. Recent evidence suggests that enhanced magnetosphere particle densities associated with enhanced solar wind densities allow more particles to be accelerated for the ring current, thus creating larger storms.

  6. Characteristics of shocks in the solar corona, as inferred from radio, optical, and theoretical investigations

    Science.gov (United States)

    Maxwell, A.; Dryer, M.

    1982-01-01

    Solar radio bursts of spectral type II provide one of the chief diagnostics for the propagation of shocks through the solar corona. Radio data on the shocks are compared with computer models for propagation of fast-mode MHD shocks through the solar corona. Data on coronal shocks and high-velocity ejecta from solar flares are then discussed in terms of a general model consisting of three main velocity regimes.

  7. Dynamics of the Solar Wind Electromagnetic Energy Transmission Into Magnetosphere during Large Geomagnetic Storms

    Science.gov (United States)

    Kuznetsova, Tamara; Laptukhov, Alexej; Petrov, Valery

    Causes of the geomagnetic activity (GA) in the report are divided into temporal changes of the solar wind parameters and the changes of the geomagnetic moment orientation relative directions of the solar wind electric and magnetic fields. Based on our previous study we concluded that a reconnection based on determining role of mutual orientation of the solar wind electric field and geomagnetic moment taking into account effects of the Earth's orbital and daily motions is the most effective compared with existing mechanisms. At present a reconnection as paradigma that has applications in broad fields of physics needs analysis of experimental facts to be developed. In terms of reconnection it is important not only mutual orientation of vectors describing physics of interaction region but and reconnection rate which depends from rate of energy flux to those regions where the reconnection is permitted. Applied to magnetosphere these regions first of all are dayside magnetopause and polar caps. Influence of rate of the energy flux to the lobe magnetopause (based on calculations of the Poyting electromagnetic flux component controlling the reconnection rate along the solar wind velocity Pv) on planetary GA (Dst, Kp indices) is investigated at different phases of geomagnetic storms. We study also the rate of energy flux to the polar caps during storms (based on calculations of the Poyting flux vector component along the geomagnetic moment Pm) and its influence on magnetic activity in the polar ionosphere: at the auroral zone (AU,AL indices). Results allow to evaluate contributions of high and low latitude sources of electromagnetic energy to the storm development and also to clear mechanism of the electromagnetic energy transmission from the solar wind to the magnetosphere. We evaluate too power of the solar wind electromagnetic energy during well-known large storms and compare result with power of the energy sources of other geophysical processes (atmosphere, ocean

  8. Frequency dependent characteristics of solar impulsive radio bursts

    International Nuclear Information System (INIS)

    Das, T.K.; Das Gupta, M.K.

    1983-01-01

    An investigation was made of the impulsive radio bursts observed in the frequency range 0.245 to 35 GHz. Important results obtained are: (i) Simple type 1 bursts with intensities 0 to 10 f.u. and simple type 2 bursts with intensities 10 to 500 f.u. are predominant in the frequency ranges 1.415 to 4.995 GHz and 4.995 to 8.8 GHz, respectively; (ii) With maxima around 2.7 GHz and 4 GHz for the first and second types respectively, the durations of the radio bursts decrease gradually both towards lower and higher frequencies; (iii) As regards occurrences, the first type dominates in the southern solar hemisphere peaking around 8.8 GHz, whereas the second type favours the north with no well-defined maximum in any frequency; (iv) Both types prefer the eastern hemisphere, the peak occurrences being around 8.8 GHz and 5 GHz for the two successive types, respectively; (c) The spectra of impulsive radio bursts are generally of the inverted U-type with the maximum emission intensity between 5 and 15 GHz. (author)

  9. The Future of Geomagnetic Storm Predictions: Implications from Recent Solar and Interplanetary Observations

    Science.gov (United States)

    Tsurutani, B. T.; Gonzalez, W. D.

    1995-01-01

    Within the last 7-8 years, there has been a substantial growth in out knowledge of the solar and interplanetary causes of geomagnetic storms at Earth. This review article will not attempt to cover all of the work done during this period. This can be found elsewhere. Our emphasis here will be on recent efforts that expose important, presently unanswered questions that must be addressed and solved before true predictability of storms can be possible. Hopefully, this article will encourage some readers to join this effort and perhaps make major contributions to the field.

  10. Classification and quantification of solar wind driver gases leading to intense geomagnetic storms

    Science.gov (United States)

    Adekoya, B. J.; Chukwuma, V. U.

    2018-01-01

    Classification and quantification of the interplanetary structures causing intense geomagnetic storms (Dst ≤ -100 nT) that occurred during 1997-2016 are studied. The subject of this consists of solar wind parameters of seventy-three intense storms that are associated with the southward interplanetary magnetic field. About 30.14% of the storms were driven by a combination of the sheath and ejecta (S + E), magnetic clouds (MC) and sheath field (S) are 26% each, 10.96% by combined sheath and MCs (S + C), while 5.48% of the storms were driven by ejecta (E) alone. Therefore, we want to aver that for storms driven by: (1) S + E. The Bz is high (≥10 nT), high density (ρ) (>10 N/cm3), high plasma beta (β) (>0.8), and unspecified (i.e. high or low) structure of the plasma temperature (T) and the flow speed (V); (2) MC. The Bz is ≥10 nT, low temperature (T ≤ 400,000 K), low ρ (≤10 N/cm3), high V (≥450 km), and low β (≤0.8); (3) The structures of S + C are similar to that of MC except that the V is low (V ≤ 450 km); (4) S. The Bz is high, low T, high ρ, unspecified V, and low β; and (5) E. Is when the structures are directly opposite of the one driven by MCs except for high V. Although, westward ring current indicates intense storms, but the large intensity of geomagnetic storms is determined by the intense nature of the electric field strength and the Bz. Therefore, great storms (i.e. Dst ≤ -200 nT) are manifestation of high electric field strength (≥13 mV/m).

  11. Recent results of zebra patterns in solar radio bursts

    International Nuclear Information System (INIS)

    Chernov, Gennady P.

    2010-01-01

    This review covers the most recent experimental results and theoretical research on zebra patterns (ZPs) in solar radio bursts. The basic attention is given to events with new peculiar elements of zebra patterns received over the last few years. All new properties are considered in light of both what was known earlier and new theoretical models. Large-scale ZPs consisting of small-scale fiber bursts could be explained by simultaneous inclusion of two mechanisms when whistler waves 'highlight' the levels of double plasma resonance (DPR). A unique fine structure was observed in the event on 2006 December 13: spikes in absorption formed dark ZP stripes against the absorptive type III-like bursts. The spikes in absorption can appear in accordance with well known mechanisms of absorptive bursts. The additional injection of fast particles filled the loss-cone (breaking the loss-cone distribution), and the generation of the continuum was quenched at these moments. The maximum absorptive effect occurs at the DPR levels. The parameters of millisecond spikes are determined by small dimensions of the particle beams and local scale heights in the radio source. Thus, the DPR model helps to understand several aspects of unusual elements of ZPs. However, the simultaneous existence of several tens of the DPR levels in the corona is impossible for any realistic profile of the plasma density and magnetic field. Three new theories of ZPs are examined. The formation of eigenmodes of transparency and opacity during the propagation of radio waves through regular coronal inhomogeneities is the most natural and promising mechanism. Two other models (nonlinear periodic space - charge waves and scattering of fast protons on ion-sound harmonics) could happen in large radio bursts. (invited reviews)

  12. LOFAR tied-array imaging of Type III solar radio bursts

    NARCIS (Netherlands)

    Morosan, D.E.; et al., [Unknown; Hessels, J.W.T.; Markoff, S.

    2014-01-01

    Context. The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), the Sun has not been imaged extensively because of the instrumental limitations of previous radio

  13. LOFAR tied-array imaging of Type III solar radio bursts

    NARCIS (Netherlands)

    Morosan, D.E.; Gallagher, P.T.; Zucca, P.; Fallows, R.; Carley, E.P.; Mann, G.; Bisi, M.M.; Kerdraon, A.; Avruch, I.M.; Bentum, Marinus Jan; Bernardi, G.; Best, P.; Bonafede, A.; Bregman, J.; Breitling, F.

    2014-01-01

    Context: The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), the Sun has not been imaged extensively because of the instrumental limitations of previous radio

  14. Annals of the International Geophysical Year solar radio emission during the International Geophysical Year

    CERN Document Server

    Smerd, S F

    1969-01-01

    Annals of the International Geophysical Year, Volume 34: Solar Radio Emission During the International Geophysical Year covers the significant solar radio emission events observed during the International Geophysical Year (IGY). This book is composed of six chapters, and begins with a summary of tabulated quantities describing solar radio emission during the IGY. The tabulated figures illustrate the method of recording the position of radio sources on the sun, the use of symbols in describing the structure of bursts observed at single frequencies, and the different types used in a spectral

  15. COMPARATIVE EVALUATION OF THE INFLUENCING EFFECTS OF GEOMAGNETIC SOLAR STORMS ON EARTHQUAKES IN ANATOLIAN PENINSULA

    Directory of Open Access Journals (Sweden)

    Yesugey Sadik Cengiz

    2009-07-01

    Full Text Available Earthquakes are tectonic events that take place within the fractures of the earth's crust, namely faults. Above certain scale, earthquakes can result in widespread fatalities and substantial financial loss. In addition to the movement of tectonic plates relative to each other, it is widely discussed that there are other external influences originate outside earth that can trigger earthquakes. These influences are called "triggering effects". The purpose of this article is to present a statistical view to elaborate if the solar geomagnetic storms trigger earthquakes.As a model, the research focuses on the Anatolian peninsula, presenting 41 years of historical data on magnetic storms and earthquakes collated from national and international resources. As a result of the comparative assessment of the data, it is concluded that the geomagnetic storms do not trigger earthquakes.

  16. Solar radio emissions: 2D full PIC simulations

    Science.gov (United States)

    Pierre, H.; Sgattoni, A.; Briand, C.; Amiranoff, F.; Riconda, C.

    2016-12-01

    Solar radio emissions are electromagnetic waves observed at the local plasma frequency and/or at twice the plasma frequency. To describe their origin a multi-stage model has been proposed by Ginzburg & Zhelezniakov (1958) and further developed by several authors, which consider a succession of non-linear three-wave interaction processes. Electron beams accelerated by solar flares travel in the interplanetary plasma and provide the free energy for the development of plasma instabilities. The model describes how part of the free energy of these beams can be transformed in a succession of plasma waves and eventually into electromagnetic waves. Following the work of Thurgood & Tsiklauri (2015) we performed several 2D Particle In Cell simulations. The simulations follow the entire set of processes from the electron beam propagation in the background plasma to the generation of the electromagnetic waves in particular the 2ωp emission, including the excitation of the low frequency waves. As suggested by Thurgood & Tsiklauri (2015) it is possible to identify regimes where the radiation emission can be directly linked to the electron beams. Our attention was devoted to estimate the conversion efficiency from electron kinetic energy to the em energy, and the growth rate of the several processes which can be identified. We studied the emission angles of the 2ωpradiation and compared them with the theoretical predictions of Willes et. al. (1995). We also show the role played by some numerical parameters i.e. the size and shape of the simulation box. This work is the first step to prepare laser-plasma experiments. V. L. Ginzburg, V. V. Zhelezniakov On the Possible Mechanisms of Sporadic Solar Radio Emission (Radiation in an Isotropic Plasma) Soviet Astronomy, Vol. 2, p.653 (1958) J. O. Thurgood and D. Tsiklauri Self-consistent particle-in-cell simulations of funda- mental and harmonic plasma radio emission mechanisms. Astronomy & Astrophysics 584, A83 (2015). A. Willes, P

  17. `Fingerprint' Fine Structure in the Solar Decametric Radio Spectrum Solar Physics

    Science.gov (United States)

    Zlotnik, E. Y.; Zaitsev, V. V.; Melnik, V. N.; Konovalenko, A. A.; Dorovskyy, V. V.

    2015-07-01

    We study a unique fine structure in the dynamic spectrum of the solar radio emission discovered by the UTR-2 radio telescope (Kharkiv, Ukraine) in the frequency band of 20 - 30 MHz. The structure was observed against the background of a broadband type IV radio burst and consisted of parallel drifting narrow bands of enhanced emission and absorption on the background emission. The observed structure differs from the widely known zebra pattern at meter and decimeter wavelengths by the opposite directions of the frequency drift within a single stripe at a given time. We show that the observed properties can be understood in the framework of the radiation mechanism by virtue of the double plasma resonance effect in a nonuniform coronal magnetic trap. We propose a source model providing the observed frequency drift of the stripes.

  18. Tracking Solar Type II Bursts with Space Based Radio Interferometers

    Science.gov (United States)

    Hegedus, Alexander M.; Kasper, Justin C.; Manchester, Ward B.

    2018-06-01

    The Earth’s Ionosphere limits radio measurements on its surface, blocking out any radiation below 10 MHz. Valuable insight into many astrophysical processes could be gained by having a radio interferometer in space to image the low frequency window for the first time. One application is observing type II bursts tracking solar energetic particle acceleration in Coronal Mass Ejections (CMEs). In this work we create a simulated data processing pipeline for several space based radio interferometer (SBRI) concepts and evaluate their performance in the task of localizing these type II bursts.Traditional radio astronomy software is hard coded to assume an Earth based array. To circumvent this, we manually calculate the antenna separations and insert them along with the simulated visibilities into a CASA MS file for analysis. To create the realest possible virtual input data, we take a 2-temperature MHD simulation of a CME event, superimpose realistic radio emission models from the CME-driven shock front, and propagate the signal through simulated SBRIs. We consider both probabilistic emission models derived from plasma parameters correlated with type II bursts, and analytical emission models using plasma emission wave interaction theory.One proposed SBRI is the pathfinder mission SunRISE, a 6 CubeSat interferometer to circle the Earth in a GEO graveyard orbit. We test simulated trajectories of SunRISE and image what the array recovers, comparing it to the virtual input. An interferometer on the lunar surface would be a stable alternative that avoids noise sources that affect orbiting arrays, namely the phase noise from positional uncertainty and atmospheric 10s-100s kHz noise. Using Digital Elevation Models from laser altimeter data, we test different sets of locations on the lunar surface to find near optimal configurations for tracking type II bursts far from the sun. Custom software is used to model the response of different array configurations over the lunar year

  19. The solar wind control of electron fluxes in geostationary orbit during magnetic storms

    International Nuclear Information System (INIS)

    Popov, G.V.; Degtyarev, V.I.; Sheshukov, S.S.; Chudnenko, S.E.

    1999-01-01

    The dynamics of electron fluxes (with energies from 30 to 1360 keV) in geostationary orbit during magnetic storms was investigated on the basis of LANL spacecraft 1976-059 and 1977-007 data. Thirty-seven magnetic storms with distinct onsets from the time interval July 1976-December 1978 were used in the analysis. A treatment of experimental data involved the moving averaging and the overlapping epoch method. The smoothed component of electron fluxes represents mainly trapped electrons and shows their strong dependence on the solar wind velocity. The time lag between a smoothed electron flux and the solar wind velocity increases with electron energy reflecting dynamics of the inner magnetosphere filling with trapped energetic electrons originating from substorm injection regions located not far outside geostationary orbit

  20. Statistical Characteristics of Solar Wind Dynamic Pressure Enhancements During Geomagnetic Storms

    Directory of Open Access Journals (Sweden)

    C.-R. Choi

    2008-06-01

    Full Text Available Solar wind dynamic pressure enhancements are known to cause various types of disturbances to the magnetosphere. In particular, dynamic pressure enhancements may affect the evolution of magnetic storms when they occur during storm times. In this paper, we have investigated the statistical significance and features of dynamic pressure enhancements during magnetic storm times. For the investigation, we have used a total of 91 geomagnetic storms for 2001-2003, for which the Dst minimum (Dst_min is below -50 nT. Also, we have imposed a set of selection criteria for a pressure enhancement to be considered an event: The main selection criterion is that the pressure increases by ≥50% or ≥3nPa within 30 min and remains to be elevated for 10 min or longer. For our statistical analysis, we define the storm time to be the interval from the main Dst decrease, through Dst_min, to the point where the Dst index recovers by 50%. Our main results are summarized as follows. (i ~81% of the studied storms indicate at least one event of pressure enhancements. When averaged over all the 91 storms, the occurrence rate is 4.5 pressure enhancement events per storm and 0.15 pressure enhancement events per hour. (ii The occurrence rate of the pressure enhancements is about three times higher for CME-driven storm times than for CIR-driven storm times. (iii Only 21.1% of the pressure enhancements show a clear association with an interplanetary shock. (iv A large number of the pressure enhancement events are accompanied with a simultaneous change of IMF By and/or Bz: For example, 73.5% of the pressure enhancement events are associated with an IMF change of either |∆Bz|>2nT or |∆By|>2nT. This last finding suggests that one should consider possible interplay effects between the simultaneous pressure and IMF changes in many situations.

  1. The solar activity, magnetic storms and their effects on biological systems

    International Nuclear Information System (INIS)

    Salakhitdinova, M.K.; Yusupov, A.A.

    2004-01-01

    In the present time much attention is spent on the electromagnetic waves, solar radiation and magnetic storms on biological systems, including on person. However, there are few publications describing the mechanism of these influences on human. First of all it is necessary to point out that electromagnetic waves, the flow of particles in space and magnetic storms, acting on person human-all is connected with biophysical processes. So approach to influence of these factors on organism follows the processes of influence of these waves on bio system. Magnetic storms are phenomena continuously connected with solar activity. Investigation of cosmic space has intensified the practical importance of the problem of interaction with natural factors of external ambience. Much attention deserves the cosmic radiation, geomagnetic field, elements of climate and weathers. However the mechanism of bio tropic action of these factors is not enough studied. Beginning XXI century was already signified the successes in investigation of Mars. The Space shuttles 'Spirit' and 'Opportunity' successfully have carried out some work on examining and finding of water on Mars. A flight of person to Mars is being considered. One of the important mechanisms of influence on human organism is, in our opinion, the rising of the resonance at coincidence of frequencies and their more important factor is a phenomena of electromagnetic induction and forming the radicals in the organism. (author)

  2. Thermospheric response observed over Fritz peak, Colorado, during two large geomagnetic storms near solar cycle maximum

    International Nuclear Information System (INIS)

    Hernandez, G.; Roble, R.G.; Ridley, E.C.; Allen, J.H.

    1982-01-01

    Nightime thermospheric winds and temperatures have been measured over Fritz Peak Observatory, Colorado (39.9 0 N, 105.5 0 W), with a high resolution Fabry-Perot spectrometer. The winds and temperatures are obtained from the Doppler shifts and line profiles of the (O 1) 15,867K (630 nm) line emission. Measurements made during two large geomagnetic storm periods near solar cycle maximum reveal a thermospheric response to the heat and momentum sources associated with these storms that is more complex than the ones measured near solar cycle minimum. In the earlier measurements made during solar cycle minimum, the winds to the north of Fritz Peak Observatory had an enhanced equatorward component and the winds to the south were also equatorward, usually with smaller velocities. The winds measured to the east and west of the observatory both had an enhanced westward wind component. For the two large storms near the present solar cycle maximum period converging winds are observed in each of the cardinal directions from Fritz Peak Observatory. These converging winds with speeds of hundreds of meters per second last for several hours. The measured neutral gas temperature in each of the directions also increases several hundred degrees Kelvin. Numerical experiments done with the NCAR thermospheric general circulation model (TGCM) suggest that the winds to the east and north of the station are driven by high-latitude heating and enhanced westward ion drag associated with magnetospheric convection. The cause of the enhanced poleward and eastward winds measured to the south and west of Fritz Peak Observatory, respectively, is not known. During geomagnetic quiet conditions the circulation is typically from the soutwest toward the northeast in the evening hours

  3. Cosmic radio-noise absorption bursts caused by solar wind shocks

    Directory of Open Access Journals (Sweden)

    A. Osepian

    2004-09-01

    Full Text Available Bursts of cosmic noise absorption observed at times of sudden commencements (SC of geomagnetic storms are examined. About 300SC events in absorption for the period 1967-1990 have been considered. It is found that the response of cosmic radio-noise absorption to the passage of an interplanetary shock depends on the level of the planetary magnetic activity preceding the SC event and on the magnitude of the magnetic field perturbation associated with the SC (as measured in the equatorial magnetosphere. It is shown that for SC events observed against a quiet background (Kp<2, the effects of the SC on absorption can be seen only if the magnitude of the geomagnetic field perturbation caused by the solar wind shock exceeds a threshold value ΔBth. It is further demonstrated that the existence of this threshold value, ΔBth, deduced from experimental data, can be related to the existence of a threshold for exciting and maintaining the whistler cyclotron instability, as predicted by quasi-linear theory. SC events observed against an active background (Kp<2 are accompanied by absorption bursts for all magnetic field perturbations, however small. A quantitative description of absorption bursts associated with SC events is provided by the whistler cyclotron instability theory.

  4. Energy Storage and Release through the Solar Activity Cycle Models Meet Radio Observations

    CERN Document Server

    Nindos, Alexander

    2012-01-01

    For nearly sixty years, radio observations have provided a unique insight into the physics of the active and quiescent solar atmosphere. Thanks to the variety of emission mechanisms and to the large altitude range available to observations, fundamental plasma parameters have been measured from the low chromosphere to the upper corona and interplanetary medium. This book presents current research in solar radio astronomy and shows how well it fits in the exceptional scientific context brought by the current space solar observatories. It essentially contains contributed research and review papers presented during the 2010 Community of European Solar Radio Astronomers (CESRA) meeting, which took place in Belgium in June 2010. This book is aimed at graduate students and researchers working in solar physics and space science. Previously published in Solar Physics journal, Vol. 273/2, 2011.

  5. Development of solar flares and features of the fine structure of solar radio emission

    Science.gov (United States)

    Chernov, G. P.; Fomichev, V. V.; Yan, Y.; Tan, B.; Tan, Ch.; Fu, Q.

    2017-11-01

    The reason for the occurrence of different elements of the fine structure of solar radio bursts in the decimeter and centimeter wavelength ranges has been determined based on all available data from terrestrial and satellite observations. In some phenomena, fast pulsations, a zebra structre, fiber bursts, and spikes have been observed almost simultaneously. Two phenomena have been selected to show that the pulsations of radio emission are caused by particles accelerated in the magnetic reconnection region and that the zebra structure is excited in a source, such as a magnetic trap for fast particles. The complex combination of unusual fiber bursts, zebra structure, and spikes in the phenomenon on December 1, 2004, is associated with a single source, a magnetic island formed after a coronal mass ejection.

  6. AN ANALYSIS OF INTERPLANETARY SOLAR RADIO EMISSIONS ASSOCIATED WITH A CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Krupar, V.; Eastwood, J. P. [The Blackett Laboratory, Imperial College London, London (United Kingdom); Kruparova, O.; Santolik, O.; Soucek, J., E-mail: v.krupar@imperial.ac.uk, E-mail: jonathan.eastwood@imperial.ac.uk, E-mail: ok@ufa.cas.cz, E-mail: os@ufa.cas.cz, E-mail: soucek@ufa.cas.cz [Institute of Atmospheric Physics CAS, Prague (Czech Republic); and others

    2016-05-20

    Coronal mass ejections (CMEs) are large-scale eruptions of magnetized plasma that may cause severe geomagnetic storms if Earth directed. Here, we report a rare instance with comprehensive in situ and remote sensing observations of a CME combining white-light, radio, and plasma measurements from four different vantage points. For the first time, we have successfully applied a radio direction-finding technique to an interplanetary type II burst detected by two identical widely separated radio receivers. The derived locations of the type II and type III bursts are in general agreement with the white-light CME reconstruction. We find that the radio emission arises from the flanks of the CME and are most likely associated with the CME-driven shock. Our work demonstrates the complementarity between radio triangulation and 3D reconstruction techniques for space weather applications.

  7. Highlighting the history of Japanese radio astronomy. 5: The 1950 Osaka solar grating array proposal

    Science.gov (United States)

    Wendt, Harry; Orchiston, Wayne; Ishiguro, Masato; Nakamura, Tsuko

    2017-04-01

    In November 1950, a paper was presented at the 5th Annual Assembly of the Physical Society of Japan that outlined the plan for a radio frequency grating array, designed to provide high-resolution observations of solar radio emission at 3.3 GHz. This short paper provides details of the invention of this array, which occurred independently of W.N. Christiansen's invention of the solar grating array in Australia at almost the same time.

  8. Characteristics of coronal shock waves and solar type 2 radio bursts

    Science.gov (United States)

    Mann, G.; Classen, H.-T.

    1995-01-01

    In the solar corona shock waves generated by flares and/or coronal mass ejections can be observed by radio astronomical methods in terms of solar type 2 radio bursts. In dynamic radio spectra they appear as emission stripes slowly drifting from high to low frequencies. A sample of 25 solar type 2 radio bursts observed in the range of 40 - 170 MHz with a time resolution of 0.1 s by the new radiospectrograph of the Astrophvsikalisches Institut Potsdam in Tremsdorf is statistically investigated concerning their spectral features, i.e, drift rate, instantaneous bandwidth, and fundamental harmonic ratio. In-situ plasma wave measurements at interplanetary shocks provide the assumption that type 2 radio radiation is emitted in the vicinity of the transition region of shock waves. Thus, the instantaneous bandwidth of a solar type 2 radio burst would reflect the density jump across the associated shock wave. Comparing the inspection of the Rankine-Hugoniot relations of shock waves under coronal circumstances with those obtained from the observational study, solar type 2 radio bursts should be regarded to be generated by weak supercritical, quasi-parallel, fast magnetosonic shock waves in the corona.

  9. NARX neural network Prediction of SYMH and ASYH indices for geomagnetic storms of solar cycle 24 including recent St. Patrick's day, 2015 storm

    Science.gov (United States)

    Bhaskar, A. T.; Vichare, G.

    2017-12-01

    Here, an attempt is made to develop a prediction model for SYMH and ASYH geomagnetic indices using Artificial Neural Network (ANN). SYMH and ASYH indices represent longitudinal symmetric and asymmetric component of the ring current. The ring current state depends on its past conditions therefore, it is necessary to consider its history for prediction. To account this effect Nonlinear Autoregressive Network with eXogenous inputs (NARX) is implemented. This network considers input history of 30 minutes and output feedback of 120 minutes. Solar wind parameters mainly velocity, density and interplanetary magnetic field are used as inputs. SYMH and ASYH indices during geomagnetic storms of 1998-2013, having minimum SYMH training two independent networks. We present the prediction of SYMH and ASYH indices during 9 geomagnetic storms of solar cycle 24 including the recent largest storm occurred on St. Patrick's day, 2015. The present prediction model reproduces the entire time profile of SYMH and ASYH indices along with small variations of 10-30 minutes to good extent within noise level, indicating significant contribution of interplanetary sources and past state of the magnetosphere. However, during the main phase of major storms, residuals (observed-modeled) are found to be large, suggesting influence of internal factors such as magnetospheric processes.

  10. Predicting geomagnetic storms from solar-wind data using time-delay neural networks

    Directory of Open Access Journals (Sweden)

    H. Gleisner

    1996-07-01

    Full Text Available We have used time-delay feed-forward neural networks to compute the geomagnetic-activity index Dst one hour ahead from a temporal sequence of solar-wind data. The input data include solar-wind density n, velocity V and the southward component Bz of the interplanetary magnetic field. Dst is not included in the input data. The networks implement an explicit functional relationship between the solar wind and the geomagnetic disturbance, including both direct and time-delayed non-linear relations. In this study we especially consider the influence of varying the temporal size of the input-data sequence. The networks are trained on data covering 6600 h, and tested on data covering 2100 h. It is found that the initial and main phases of geomagnetic storms are well predicted, almost independent of the length of the input-data sequence. However, to predict the recovery phase, we have to use up to 20 h of solar-wind input data. The recovery phase is mainly governed by the ring-current loss processes, and is very much dependent on the ring-current history, and thus also the solar-wind history. With due consideration of the time history when optimizing the networks, we can reproduce 84% of the Dst variance.

  11. NOAA Satellites Provide a Keen View of the Martin Luther King Solar Storm of January 2005

    Science.gov (United States)

    Wilkinson, D. C.; Allen, J. H.

    2005-05-01

    Solar active region 0720 rotated onto the east limb on January 10th and put on a pyrotechnic display uncharacteristic for this phase of the solar cycle before disappearing beyond the west limb on January 23rd. On January 15th this region released the first of five X-class solar flares. The last of those flares, January 20th, was associated with an extraordinary ion storm whose effect reached Earth's surface. This paper highlights the record of this event made by NOAA's GOES satellites via their Space Environment Monitor (SEM) subsystems that measures X-ray, energetic particles, and the magnetic field vector at the satellite. Displays of those data are supplemented by neutron monitor data to illustrate their relationship to the January 20th Ground Level Event. GOES-12 is also equipped with the Solar X-ray Imager (SXI) that produces an image of the Sun in X-ray wavelengths once per minute. Movies created from those data perfectly illustrate the cause-and-effect relationship between intense solar activity and satellite disruptions. The flares on January 17th and 20th are closely followed by noise in the SXI telescope resulting from energetic ions penetrating SXI. Ions with sufficient velocity and atomic number can penetrate satellite components and deposit charge along their path. Sufficient charge deposition can introduce erroneous information into solid-state devices. A survey of satellites that experienced problems of this type during this event will also be presented.

  12. A study of solar and interplanetary parameters of CMEs causing major geomagnetic storms during SC 23

    Directory of Open Access Journals (Sweden)

    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.

  13. Fluctuation analysis of solar radio bursts associated with geoeffective X-class flares

    Czech Academy of Sciences Publication Activity Database

    Veronese, T.B.; Rosa, R. R.; Bolzan, M.J.A.; Fernandes, F. C. R.; Sawant, H. S.; Karlický, Marian

    2011-01-01

    Roč. 73, 11-12 (2011), s. 1311-1316 ISSN 1364-6826 Institutional research plan: CEZ:AV0Z10030501 Keywords : decimetric solar radio bursts * solar flares * detrended fluctuation analysis Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.596, year: 2011

  14. On the effects of solar storms to the decaying orbital space debris

    International Nuclear Information System (INIS)

    Herdiwijaya, Dhani; Rachman, Abdul

    2014-01-01

    Any man-made object in Earth's orbit that no longer serves a useful purpose is classified as orbital debris. Debris objects come from a variety of sources. The majority is related to satellite fragmentation. Other major sources of debris are propulsion systems, and fragmentation of spent upper stages, payload and mission related debris. Serious concern about orbital debris has been growing. Knowledge of the future debris environment is important to both satellite designers, and mission planners, who need to know what hazards a satellite might encounter during the course of its mission. Therefore, it is important to know how much debris is in orbit, where it is located, and when it will decay. The debris environment is complex and dynamically evolving. Objects of different shape and size behave differently in orbit. The geoeffectiveness space environments include solar flux at 10.7 cm, solar energetic particles flux or speed, solar wind flow pressure, electric field, and geomagnetic indices. We study the decaying orbital debris from Tracking and Impact Prediction (TIP) messages in conjuction with geoeffectiveness space environments through time epoch correlation. We found that the decaying and reentry orbital debris are triggered by space environment enhancement within at least one week before reentry. It is not necessary a transient or high energetic and severe solar storm events are needed in decaying processes. We propose that the gradual enhancement processes of space environment will cause satellite surface charging due to energetic electron and enhance drag force

  15. On the effects of solar storms to the decaying orbital space debris

    Energy Technology Data Exchange (ETDEWEB)

    Herdiwijaya, Dhani, E-mail: dhani@as.itb.ac.id [Astronomy Division and Bosscha Observatory, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Ganesha 10, Bandung 40132 (Indonesia); Rachman, Abdul [Space Science Center, National Institute of Aeronautics and Space, Junjunan 133, Bandung 40173 (Indonesia)

    2014-03-24

    Any man-made object in Earth's orbit that no longer serves a useful purpose is classified as orbital debris. Debris objects come from a variety of sources. The majority is related to satellite fragmentation. Other major sources of debris are propulsion systems, and fragmentation of spent upper stages, payload and mission related debris. Serious concern about orbital debris has been growing. Knowledge of the future debris environment is important to both satellite designers, and mission planners, who need to know what hazards a satellite might encounter during the course of its mission. Therefore, it is important to know how much debris is in orbit, where it is located, and when it will decay. The debris environment is complex and dynamically evolving. Objects of different shape and size behave differently in orbit. The geoeffectiveness space environments include solar flux at 10.7 cm, solar energetic particles flux or speed, solar wind flow pressure, electric field, and geomagnetic indices. We study the decaying orbital debris from Tracking and Impact Prediction (TIP) messages in conjuction with geoeffectiveness space environments through time epoch correlation. We found that the decaying and reentry orbital debris are triggered by space environment enhancement within at least one week before reentry. It is not necessary a transient or high energetic and severe solar storm events are needed in decaying processes. We propose that the gradual enhancement processes of space environment will cause satellite surface charging due to energetic electron and enhance drag force.

  16. Solar storm effects during Saint Patrick's Days in 2013 and 2015 on the Schumann resonances measured by the ELF station at Sierra Nevada (Spain)

    Science.gov (United States)

    Salinas, A.; Toledo-Redondo, S.; Navarro, E. A.; Fornieles-Callejón, J.; Portí, J. A.

    2016-12-01

    The effects of solar storms occurring during the days 17 to 19 March 2013 and 2015, St. Patrick's Day intervals, on Schumann resonances (SRs) have been studied. To do this, the experimental data recorded by the Juan Antonio Morente extremely low frequency station located at Sierra Nevada, Spain, have been processed in order to obtain hourly averaged information on the first three resonance modes. Results are compared with monthly averages of the SR data for each hour to detect deviations from the regular behavior. Evidence of significant changes in the peak amplitudes and frequencies of the SRs have been identified in the station's measurements and related to the coronal mass ejection impact in the magnetosphere, detected by in situ plasma measurements onboard spacecraft in the solar wind. However, the complicated nature of the Schumann resonances, dependent on multiple variables and subject to multiple unavoidable interferences (e.g., lightning or human radio sources), in conjunction with the complex magnetosphere-ionosphere-atmosphere coupling processes, makes it difficult to conclude that the observed deviations are exclusively due to the solar events mentioned. Results extracted from only two solar events cannot be considered as conclusive, and therefore, independent comparison with results reported by other research would seem advisable in future works on this subject.

  17. Jupiter's Spot Seen Glowing - Scientists Get First Look at Weather Inside the Solar System's Biggest Storm

    Science.gov (United States)

    2010-03-01

    New ground-breaking thermal images obtained with ESO's Very Large Telescope and other powerful ground-based telescopes show swirls of warmer air and cooler regions never seen before within Jupiter's Great Red Spot, enabling scientists to make the first detailed interior weather map of the giant storm system linking its temperature, winds, pressure and composition with its colour. "This is our first detailed look inside the biggest storm of the Solar System," says Glenn Orton, who led the team of astronomers that made the study. "We once thought the Great Red Spot was a plain old oval without much structure, but these new results show that it is, in fact, extremely complicated." The observations reveal that the reddest colour of the Great Red Spot corresponds to a warm core within the otherwise cold storm system, and images show dark lanes at the edge of the storm where gases are descending into the deeper regions of the planet. The observations, detailed in a paper appearing in the journal Icarus, give scientists a sense of the circulation patterns within the solar system's best-known storm system. Sky gazers have been observing the Great Red Spot in one form or another for hundreds of years, with continuous observations of its current shape dating back to the 19th century. The spot, which is a cold region averaging about -160 degrees Celsius, is so wide that about three Earths could fit inside its boundaries. The thermal images were mostly obtained with the VISIR [1] instrument attached to ESO's Very Large Telescope in Chile, with additional data coming from the Gemini South telescope in Chile and the National Astronomical Observatory of Japan's Subaru Telescope in Hawaii. The images have provided an unprecedented level of resolution and extended the coverage provided by NASA's Galileo spacecraft in the late 1990s. Together with observations of the deep cloud structure by the 3-metre NASA Infrared Telescope Facility in Hawaii, the level of thermal detail observed

  18. Characteristic studies on solar x-ray flares and solar radio bursts during descending phases of solar cycles 22 and 23

    International Nuclear Information System (INIS)

    Bhattacharya, J.; De, B.K.; Guha, A.

    2014-01-01

    In this paper, a comparative study between the solar X-ray flares and solar radio bursts in terms of their duration and energy has been done. This has been done by analyzing the data in a statistical way covering the descending phase of the 22nd and 23rd solar cycles. It has been observed that the most probable value of duration of both solar X-ray flares and solar radio bursts remain same for a particular cycle. There is a slight variation in the most probable value of duration in going from 22nd cycle to 23rd cycle in the case of both kinds of events. This small variation may be due to the variation of polar field. A low correlation has been observed between energy fluxes in solar X-ray flares and in solar radio bursts. This has been attributed to the non symmetric contribution of energy to the solar radio and X-ray band controlled by solar magnetic field

  19. Radio astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Nagnibeda, V.G.

    1981-01-01

    The history of radio astronomical observations at the Astronomical Observatory of Leningrad State University is reviewed. Various facilities are described, and methods and instruments used are discussed. Some results are summarized for radio observations of the sun, including observations of local sources of solar radio emission, the absolute solar radio flux, and radio emission from filaments and prominences.

  20. Solar sources of interplanetary southward B/sub z/ events responsible for major magnetic storms (1978--1979)

    International Nuclear Information System (INIS)

    Tang, F.; Tsurutani, B.T.; Gonzalez, W.D.; Akasofu, S.I.; Smith, E.J.

    1989-01-01

    Tsurutani et al. [1988] analyzed the 10 intense interplanetary southward B/sub z/ events that led to major magnetic storms (Dst 3.0) are associated with prominence eruptions. For three of the five southward B/sub z/ events in which the driver gases are the causes of the intense southward field leading to magnetic storms, the photospheric fields of the solar sources have no dominant southward component, indicating the driver gas fields do not always result from a simple outward convection of solar magnetic fields. Finally we compare the solar events and their resulting interplanetary shocks and find that the standard solar parameters do not correlate with the strengths of the resulting shocks at 1 AU. The implications are discussed. copyright American Geophysical Union 1989

  1. Observation of solar radio bursts using swept-frequency radiospectrograph in 20 - 40 MHz band

    International Nuclear Information System (INIS)

    Aoyama, Takashi; Oya, Hiroshi.

    1987-01-01

    A new station for the observation of solar decametric radio bursts has been developed at Miyagi Vocational Training College in Tsukidate, Miyagi, Japan. Using the swept frequency radiospectrograph covering a frequency range from 20 MHz to 40 MHz within 200 msec, with bandwidth of 30 kHz, the radio outbursts from the sun have been currently monitored with colored dynamic spectrum display. After July 1982, successful observations provide the data which include all types of solar radio bursts such as type I, II, III, IV and V in the decametric wavelength range. In addition to these typical radio bursts, rising tone bursts with fast drift rate followed by strong type III bursts and a series of bursts repeating rising and falling tone bursts with slow drift rate have been observed. (author)

  2. The velocities of type II solar radio bursts

    International Nuclear Information System (INIS)

    Tlamicha, A.; Karlicky, M.

    1976-01-01

    A list is presented of type II radio bursts identified at Ondrejov between January 1973 and December 1974 in the frequency range of the dynamic spectrum 70 to 810 MHz. The velocities of shock waves in the individual cases of type II bursts are given using the fourfold Newkirk model. Some problems associated with type II radio bursts and with the propagation of the shock wave into the interplanetary space and into the region of the Earth are also discussed. (author)

  3. A Proton-Cyclotron Wave Storm Generated by Unstable Proton Distribution Functions in the Solar Wind

    Science.gov (United States)

    Wicks, R. T.; Alexander, R. L.; Stevens, M.; Wilson, L. B., III; Moya, P. S.; Vinas, A.; Jian, L. K.; Roberts, D. A.; O’Modhrain, S.; Gilbert, J. A.; hide

    2016-01-01

    We use audification of 0.092 seconds cadence magnetometer data from the Wind spacecraft to identify waves with amplitudes greater than 0.1 nanoteslas near the ion gyrofrequency (approximately 0.1 hertz) with duration longer than 1 hour during 2008. We present one of the most common types of event for a case study and find it to be a proton-cyclotron wave storm, coinciding with highly radial magnetic field and a suprathermal proton beam close in density to the core distribution itself. Using linear Vlasov analysis, we conclude that the long-duration, large-amplitude waves are generated by the instability of the proton distribution function. The origin of the beam is unknown, but the radial field period is found in the trailing edge of a fast solar wind stream and resembles other events thought to be caused by magnetic field footpoint motion or interchange reconnection between coronal holes and closed field lines in the corona.

  4. Solar cooker effect test and temperature field simulation of radio telescope subreflector

    International Nuclear Information System (INIS)

    Chen, Deshen; Wang, Huajie; Qian, Hongliang; Zhang, Gang; Shen, Shizhao

    2016-01-01

    Highlights: • Solar cooker effect test of a telescope subreflector is conducted for the first time. • The cause and temperature distribution regularities are analyzed contrastively. • Simulation methods are proposed using light beam segmentation and tracking methods. • The validity of simulation methods is evaluated using the test results. - Abstract: The solar cooker effect can cause a local high temperature of the subreflector and can directly affect the working performance of the radio telescope. To study the daily temperature field and solar cooker effect of a subreflector, experimental studies are carried out with a 3-m-diameter radio telescope model for the first time. Initially, the solar temperature distribution rules, especially the solar cooker effect, are summarized according to the field test results under the most unfavorable conditions. Then, a numerical simulation for the solar temperature field of the subreflector is studied by light beam segmentation and tracking methods. Finally, the validity of the simulation methods is evaluated using the test results. The experimental studies prove that the solar cooker effect really exists and should not be overlooked. In addition, simulation methods for the subreflector temperature field proposed in this paper are effective. The research methods and conclusions can provide valuable references for thermal design, monitoring and control of similar high-precision radio telescopes.

  5. Solar Storm GIC Forecasting: Solar Shield Extension Development of the End-User Forecasting System Requirements

    Science.gov (United States)

    Pulkkinen, A.; Mahmood, S.; Ngwira, C.; Balch, C.; Lordan, R.; Fugate, D.; Jacobs, W.; Honkonen, I.

    2015-01-01

    A NASA Goddard Space Flight Center Heliophysics Science Division-led team that includes NOAA Space Weather Prediction Center, the Catholic University of America, Electric Power Research Institute (EPRI), and Electric Research and Management, Inc., recently partnered with the Department of Homeland Security (DHS) Science and Technology Directorate (S&T) to better understand the impact of Geomagnetically Induced Currents (GIC) on the electric power industry. This effort builds on a previous NASA-sponsored Applied Sciences Program for predicting GIC, known as Solar Shield. The focus of the new DHS S&T funded effort is to revise and extend the existing Solar Shield system to enhance its forecasting capability and provide tailored, timely, actionable information for electric utility decision makers. To enhance the forecasting capabilities of the new Solar Shield, a key undertaking is to extend the prediction system coverage across Contiguous United States (CONUS), as the previous version was only applicable to high latitudes. The team also leverages the latest enhancements in space weather modeling capacity residing at Community Coordinated Modeling Center to increase the Technological Readiness Level, or Applications Readiness Level of the system http://www.nasa.gov/sites/default/files/files/ExpandedARLDefinitions4813.pdf.

  6. Dependence of regular background noise of VLF radiation and thunder-storm activity on solar wind proton density

    International Nuclear Information System (INIS)

    Sobolev, A.V.; Kozlov, V.I.

    1997-01-01

    Correlation of the intensity of slowly changing regular background noise within 9.7 kHz frequency in Yakutsk (L = 3) and of the solar wind density protons was determined. This result explains the reverse dependence of the intensity of the regular background noise on the solar activity, 27-day frequency, increase before and following geomagnetic storms, absence of relation with K p index of geomagnetic activity. Conclusion is made that growth of density of the solar wind protons results in increase of the regular background noise and thunderstorm activity

  7. Determination of plasma parameters in solar zebra radio sources

    Czech Academy of Sciences Publication Activity Database

    Karlický, Marian; Yasnov, L. V.

    2015-01-01

    Roč. 581, September (2015), A115/1-A115/6 ISSN 0004-6361 R&D Projects: GA ČR GAP209/12/0103 Grant - others:EC(XE) 606862 Program:FP7 Institutional support: RVO:67985815 Keywords : Sun * flares * radio radiation Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

  8. Solar radio bursts with spectral fine structures in preflares

    Czech Academy of Sciences Publication Activity Database

    Zhang, J.; Tan, B.-L.; Karlický, Marian; Mészárosová, Hana; Huang, J.; Tan, C.M.; Simoes, P.J.A.

    2015-01-01

    Roč. 799, č. 1 (2015), 30/1-30/13 ISSN 0004-637X Institutional support: RVO:67985815 Keywords : Sun corona * Sun flares * radio radiation Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.909, year: 2015

  9. Assessing the Performance of GPS Precise Point Positioning Under Different Geomagnetic Storm Conditions during Solar Cycle 24

    Directory of Open Access Journals (Sweden)

    Xiaomin Luo

    2018-06-01

    Full Text Available The geomagnetic storm, which is an abnormal space weather phenomenon, can sometimes severely affect GPS signal propagation, thereby impacting the performance of GPS precise point positioning (PPP. However, the investigation of GPS PPP accuracy over the global scale under different geomagnetic storm conditions is very limited. This paper for the first time presents the performance of GPS dual-frequency (DF and single-frequency (SF PPP under moderate, intense, and super storms conditions during solar cycle 24 using a large data set collected from about 500 international GNSS services (IGS stations. The global root mean square (RMS maps of GPS PPP results show that stations with degraded performance are mainly distributed at high-latitude, and the degradation level generally depends on the storm intensity. The three-dimensional (3D RMS of GPS DF PPP for high-latitude during moderate, intense, and super storms are 0.393 m, 0.680 m and 1.051 m, respectively, with respect to only 0.163 m on quiet day. RMS errors of mid- and low-latitudes show less dependence on the storm intensities, with values less than 0.320 m, compared to 0.153 m on quiet day. Compared with DF PPP, the performance of GPS SF PPP is inferior regardless of quiet or disturbed conditions. The degraded performance of GPS positioning during geomagnetic storms is attributed to the increased ionospheric disturbances, which have been confirmed by our global rate of TEC index (ROTI maps. Ionospheric disturbances not only lead to the deteriorated ionospheric correction but also to the frequent cycle-slip occurrence. Statistical results show that, compared with that on quiet day, the increased cycle-slip occurrence are 13.04%, 56.52%, and 69.57% under moderate, intense, and super storms conditions, respectively.

  10. Comparison of nonflare solar soft x ray flux with 10.7-cm radio flux

    International Nuclear Information System (INIS)

    Donnelly, R.F.

    1982-01-01

    The similarities and differences of the nonflare solar 1- to 8-A X ray flux and the daily 10.7-cm Ottawa solar radio flux are examined. The radio flux is shown to be much less sensitive than the soft X ray flux on the average to the coronal emission of active regions located near or beyond the solar chromospheric limb relative to regions near the center of the solar disk. This is caused by the solar soft X ray emission's being optically thin while much of the 10.7-cm active region emission is from optical depths of tauapprox.1. The radio flux includes a large quiet sun flux which is emitted mostly from the tenuous chromosphere-corona transition region (Tapprox.10 4 --10 6 0 K) and partly from the cooler portions of the quiet corona Tapprox.1.5 x 10 6 0 K. Conversely, the solar soft X ray flux has a very small quiet sun component

  11. Solar radio bursts as a tool for space weather forecasting

    Science.gov (United States)

    Klein, Karl-Ludwig; Matamoros, Carolina Salas; Zucca, Pietro

    2018-01-01

    The solar corona and its activity induce disturbances that may affect the space environment of the Earth. Noticeable disturbances come from coronal mass ejections (CMEs), which are large-scale ejections of plasma and magnetic fields from the solar corona, and solar energetic particles (SEPs). These particles are accelerated during the explosive variation of the coronal magnetic field or at the shock wave driven by a fast CME. In this contribution, it is illustrated how full Sun microwave observations can lead to (1) an estimate of CME speeds and of the arrival time of the CME at the Earth, (2) the prediction of SEP events attaining the Earth. xml:lang="fr"

  12. Changed Relation between Solar 10.7-cm Radio Flux and some ...

    Indian Academy of Sciences (India)

    The time series of monthly average values of sunspot numbers SSN, 10.7 cm flux ... This radio emission comes from the higher part of the chromosphere and .... work elements on the solar surface on one hand and spots on the other hand ... size, their magnetic fields were less composite and characterized by the greater life-.

  13. Sporadic radio emission connected with a definite manifestation of solar activity in the near Earth space

    Science.gov (United States)

    Dudnic, A. V.; Zaljubovski, I. I.; Kartashev, V. M.; Shmatko, E. S.

    1985-01-01

    Sporadic radio emission of near Earth space at the frequency of 38 MHz is shown to appear in the event of a rapid development of instabilities in the ionospheric plasma. The instabilities are generated due to primary ionospheric disturbances occurring under the influence of solar chromospheric flares.

  14. The solar eruption of 13 May 2005: EISCAT and MERLIN observations of a coronal radio burst

    Directory of Open Access Journals (Sweden)

    R. A. Jones

    2006-09-01

    Full Text Available We report results from EISCAT and MERLIN observations of radio scintillation during a solar eruptive event in May 2005. Anomalous increases in signal strength detected at sites more than 2000 km apart are shown to arise from the detection of a strong coronal radio burst in the distant off-axis response of the MERLIN and EISCAT antennas. These observations show that EISCAT is capable of detecting the signatures of explosive events in the solar atmosphere with a high degree of time resolution. We further suggest that the highly time-structured variation in signal strength caused by distant off-axis detection of a powerful coronal radio signal could provide an explanation for previously unexplained anomalies in EISCAT IPS observations, as well as being a potential source of errors in active observations using radar codes with a completion time longer than the time-variation of the coronal signal.

  15. Radio evidence for shock acceleration of electrons in the solar corona

    Science.gov (United States)

    Cane, H. V.; Stone, R. G.; Fainberg, J.; Steinberg, J. L.; Hoang, S.; Stewart, R. T.

    1981-01-01

    It is pointed out that the new class of kilometer-wavelength solar radio bursts observed with the ISEE-3 Radio Astronomy Experiment occurs at the reported times of type II events, which are indicative of a shock wave. An examination of records from the Culgoora Radio Observatory reveals that the associated type II bursts have fast drift elements emanating from them; that is, a herringbone structure is formed. It is proposed that this new class of bursts is a long-wavelength continuation of the herringbone structure, and it is thought probable that the electrons producing the radio emission are accelerated by shocks. These new events are referred to as shock-accelerated events, and their characteristics are discussed.

  16. Solar Type II Radio Bursts and IP Type II Events

    Science.gov (United States)

    Cane, H. V.; Erickson, W. C.

    2005-01-01

    We have examined radio data from the WAVES experiment on the Wind spacecraft in conjunction with ground-based data in order to investigate the relationship between the shocks responsible for metric type II radio bursts and the shocks in front of coronal mass ejections (CMEs). The bow shocks of fast, large CMEs are strong interplanetary (IP) shocks, and the associated radio emissions often consist of single broad bands starting below approx. 4 MHz; such emissions were previously called IP type II events. In contrast, metric type II bursts are usually narrowbanded and display two harmonically related bands. In addition to displaying complete dynamic spectra for a number of events, we also analyze the 135 WAVES 1 - 14 MHz slow-drift time periods in 2001-2003. We find that most of the periods contain multiple phenomena, which we divide into three groups: metric type II extensions, IP type II events, and blobs and bands. About half of the WAVES listings include probable extensions of metric type II radio bursts, but in more than half of these events, there were also other slow-drift features. In the 3 yr study period, there were 31 IP type II events; these were associated with the very fastest CMEs. The most common form of activity in the WAVES events, blobs and bands in the frequency range between 1 and 8 MHz, fall below an envelope consistent with the early signatures of an IP type II event. However, most of this activity lasts only a few tens of minutes, whereas IP type II events last for many hours. In this study we find many examples in the radio data of two shock-like phenomena with different characteristics that occur simultaneously in the metric and decametric/hectometric bands, and no clear example of a metric type II burst that extends continuously down in frequency to become an IP type II event. The simplest interpretation is that metric type II bursts, unlike IP type II events, are not caused by shocks driven in front of CMEs.

  17. A theory of solar type III radio bursts

    International Nuclear Information System (INIS)

    Goldstein, M.L.; Smith, R.A.

    1979-01-01

    A theory of type III bursts is reviewed. Energetic electrons propagating through the interplanetary medium are shown to excite the one dimensional oscillating two stream instability (OTSI). The OTSI is in turn stabilized by anomalous resistivity which completes the transfer of long wavelength Langmuir waves to short wavelengths, out of resonance with the electrons. The theory explains the small energy losses suffered by the electrons in propagating to 1 AU, the predominance of second harmonic radiation, and the observed correlation between radio and electron fluxes. (Auth.)

  18. Flow of Energy through the Inner Magnetosphere during the March 17, 2015 solar storm as observed by the Van Allen Probes Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE)

    Science.gov (United States)

    Manweiler, J. W.; Madanian, H.; Gerrard, A. J.; Patterson, J. D.; Mitchell, D. G.; Lanzerotti, L. J.

    2017-12-01

    On March 17, 2015, a large solar storm impacted the Earth's magnetosphere with a maximum negative Dst of -232 nT. We report on the temporal and spatial evolution of the proton energetic particle distributions in phase space during this storm, as measured by the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument on board each of the Van Allen Probes. We characterize the distribution prior to onset of the storm to provide a definition of quiet time conditions. We then show how the distribution evolves during the storm noting key changes of the distribution as a function of L and MLT and showing how the pitch angle distributions change throughout the storm. These observations displayed a number of interesting features of the storm including high beta plasma conditions and multiple injections of protons into the inner magnetosphere. We present the radial changes of the distribution at storm onset and following the evolution of the distribution during storm recovery. We compare observations of the East/West asymmetry in the proton distribution before versus after onset using both Van Allen Probes A and B spacecraft observations. Finally, we note interesting changes in the distribution showing an anomalous dropout in mid-energies of the distribution and observe an outward radial propagation of this dropout during recovery.

  19. Optical-to-Radio Continua in Solar Flares

    Czech Academy of Sciences Publication Activity Database

    Heinzel, Petr; Avrett, E.H.

    2012-01-01

    Roč. 227, č. 1 (2012), s. 31-44 ISSN 0038-0938 R&D Projects: GA ČR GAP209/10/1680 Institutional research plan: CEZ:AV0Z10030501 Keywords : solar flares * spectral continua * diagnostics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.256, year: 2012

  20. Cyclotron Line in Solar Microwave Radiation by Radio Telescope RATAN-600 Observations of the Solar Active Region NOAA 12182

    Science.gov (United States)

    Peterova, N. G.; Topchilo, N. A.

    2017-12-01

    This paper presents the results of observation of a rare phenomenon—a narrowband increase in the brightness of cyclotron radiation of one of the structural details of a radio source located in the solar corona above the solar active region NOAA 12182 in October 2014 at a frequency of 4.2 ± 0.1 GHz. The brightness of radiation in the maximum of the phenomenon has reached 10 MK; its duration was equal to 3 s. The exact location of the source of the narrowband cyclotron radiation is indicated: it is a corona above a fragmented (4-nuclear) sunspot, on which a small UV flare loop was closed.

  1. Prediction of geomagnetic storms from solar wind data with the use of a neural network

    Directory of Open Access Journals (Sweden)

    H. Lundstedt

    Full Text Available An artificial feed-forward neural network with one hidden layer and error back-propagation learning is used to predict the geomagnetic activity index (Dst one hour in advance. The Bz-component and ΣBz, the density, and the velocity of the solar wind are used as input to the network. The network is trained on data covering a total of 8700 h, extracted from the 25-year period from 1963 to 1987, taken from the NSSDC data base. The performance of the network is examined with test data, not included in the training set, which covers 386 h and includes four different storms. Whilst the network predicts the initial and main phase well, the recovery phase is not modelled correctly, implying that a single hidden layer error back-propagation network is not enough, if the measured Dst is not available instantaneously. The performance of the network is independent of whether the raw parameters are used, or the electric field and square root of the dynamical pressure.

  2. Prediction of SYM-H index during large storms by NARX neural network from IMF and solar wind data

    Directory of Open Access Journals (Sweden)

    L. Cai

    2010-02-01

    Full Text Available Similar to the Dst index, the SYM-H index may also serve as an indicator of magnetic storm intensity, but having distinct advantage of higher time-resolution. In this study the NARX neural network has been used for the first time to predict SYM-H index from solar wind (SW and IMF parameters. In total 73 time intervals of great storm events with IMF/SW data available from ACE satellite during 1998 to 2006 are used to establish the ANN model. Out of them, 67 are used to train the network and the other 6 samples for test. Additionally, the NARX prediction model is also validated using IMF/SW data from WIND satellite for 7 great storms during 1995–1997 and 2005, as well as for the July 2000 Bastille day storm and November 2001 superstorm using Geotail and OMNI data at 1 AU, respectively. Five interplanetary parameters of IMF Bz, By and total B components along with proton density and velocity of solar wind are used as the original external inputs of the neural network to predict the SYM-H index about one hour ahead. For the 6 test storms registered by ACE including two super-storms of min. SYM-H<−200 nT, the correlation coefficient between observed and NARX network predicted SYM-H is 0.95 as a whole, even as high as 0.95 and 0.98 with average relative variance of 13.2% and 7.4%, respectively, for the two super-storms. The prediction for the 7 storms with WIND data is also satisfactory, showing averaged correlation coefficient about 0.91 and RMSE of 14.2 nT. The newly developed NARX model shows much better capability than Elman network for SYM-H prediction, which can partly be attributed to a key feedback to the input layer from the output neuron with a suitable length (about 120 min. This feedback means that nearly real information of the ring current status is effectively directed to take part in the prediction of SYM-H index by ANN. The proper history length of the output-feedback may mainly reflect

  3. Prediction of SYM-H index during large storms by NARX neural network from IMF and solar wind data

    Directory of Open Access Journals (Sweden)

    L. Cai

    2010-02-01

    Full Text Available Similar to the Dst index, the SYM-H index may also serve as an indicator of magnetic storm intensity, but having distinct advantage of higher time-resolution. In this study the NARX neural network has been used for the first time to predict SYM-H index from solar wind (SW and IMF parameters. In total 73 time intervals of great storm events with IMF/SW data available from ACE satellite during 1998 to 2006 are used to establish the ANN model. Out of them, 67 are used to train the network and the other 6 samples for test. Additionally, the NARX prediction model is also validated using IMF/SW data from WIND satellite for 7 great storms during 1995–1997 and 2005, as well as for the July 2000 Bastille day storm and November 2001 superstorm using Geotail and OMNI data at 1 AU, respectively. Five interplanetary parameters of IMF Bz, By and total B components along with proton density and velocity of solar wind are used as the original external inputs of the neural network to predict the SYM-H index about one hour ahead. For the 6 test storms registered by ACE including two super-storms of min. SYM-H<−200 nT, the correlation coefficient between observed and NARX network predicted SYM-H is 0.95 as a whole, even as high as 0.95 and 0.98 with average relative variance of 13.2% and 7.4%, respectively, for the two super-storms. The prediction for the 7 storms with WIND data is also satisfactory, showing averaged correlation coefficient about 0.91 and RMSE of 14.2 nT. The newly developed NARX model shows much better capability than Elman network for SYM-H prediction, which can partly be attributed to a key feedback to the input layer from the output neuron with a suitable length (about 120 min. This feedback means that nearly real information of the ring current status is effectively directed to take part in the prediction of SYM-H index by ANN. The proper history length of the output-feedback may mainly reflect on average the characteristic time of ring

  4. Solar maximum mission: Ground support programs at the Harvard Radio Astronomy Station

    Science.gov (United States)

    Maxwell, A.

    1983-01-01

    Observations of the spectral characteristics of solar radio bursts were made with new dynamic spectrum analyzers of high sensitivity and high reliability, over the frequency range 25-580 MHz. The observations also covered the maximum period of the current solar cycle and the period of international cooperative programs designated as the Solar Maximum Year. Radio data on shock waves generated by solar flares were combined with optical data on coronal transients, taken with equipment on the SMM and other satellites, and then incorporated into computer models for the outward passage of fast-mode MHD shocks through the solar corona. The MHD models are non-linear, time-dependent and for the most recent models, quasi-three-dimensional. They examine the global response of the corona for different types of input pulses (thermal, magnetic, etc.) and for different magnetic topologies (for example, open and closed fields). Data on coronal shocks and high-velocity material ejected from solar flares have been interpreted in terms of a model consisting of three main velocity regimes.

  5. Far-IR and Radio Thermal Continua in Solar Flares

    Czech Academy of Sciences Publication Activity Database

    Kašparová, Jana; Heinzel, Petr; Karlický, Marian; Moravec, Z.; Varady, M.

    2009-01-01

    Roč. 33, - (2009), s. 309-315 ISSN 1845-8319 R&D Projects: GA ČR GA205/04/0358; GA ČR GP205/06/P135; GA ČR GA205/07/1100 Institutional research plan: CEZ:AV0Z10030501 Keywords : solar flares * radiative hydrodynamics * continuum emission Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  6. Changes in the High-Latitude Topside Ionospheric Vertical Electron-Density Profiles in Response to Solar-Wind Perturbations During Large Magnetic Storms

    Science.gov (United States)

    Benson, Robert F.; Fainberg, Joseph; Osherovich, Vladimir; Truhlik, Vladimir; Wang, Yongli; Arbacher, Becca

    2011-01-01

    The latest results from an investigation to establish links between solar-wind and topside-ionospheric parameters will be presented including a case where high-latitude topside electron-density Ne(h) profiles indicated dramatic rapid changes in the scale height during the main phase of a large magnetic storm (Dst wind data obtained from the NASA OMNIWeb database indicated that the magnetic storm was due to a magnetic cloud. This event is one of several large magnetic storms being investigated during the interval from 1965 to 1984 when both solar-wind and digital topside ionograms, from either Alouette-2, ISIS-1, or ISIS-2, are potentially available.

  7. Solar wind variations and geomagnetic storms - A study of individual storms based on high time resolution ISEE 3 data

    Science.gov (United States)

    Akasofu, S.-I.; Olmsted, C.; Smith, E. J.; Tsurutani, B.; Okida, R.; Baker, D. N.

    1985-01-01

    Two independent methods are employed to determine the relationship between the parameter epsilon and total energy dissipation rate of the magnetosphere U sub T by selecting disturbed periods from the same data d set used by Baker et al. (1983). Specifically, four storms are examined in detail, since the accuracy of estimating U sub T is significantly improved during disturbed periods. The first method assumes that U sub T = M sub A exp.2- alpha(epsilon) where M sub A is the Alfven Mach number and alpha varies with time. The second method considers a linear, time-invariant dynamic system with epsilon as input and U sub T as output. This means that U sub T = W(asterisk)epsilon where asterisk is the convolution and W is a transfer function characteristic of the system. It is found that alpha values fluctuate mainly between 0 and -0.25. The transfer function analysis indicates that W often resembles a delta-function or a narrow rectangular impulse. Both results give the same implication (namely that U sub T is approximately equal to epsilon) and thus are consistent with the view that the magnetosphere is primarily a directly driven system during disturbed periods.

  8. Propagation of interplanetary shock waves by observations of type II solar radio bursts on IMP-6

    International Nuclear Information System (INIS)

    Chertok, I.M.; Fomichev, V.V.

    1976-01-01

    A new interpretation of the low frequency type II solar radio bursts of 30 June 1971, and 7-8 August 1972 observed with IMP-6 satellite (Malitson, H.H., Fainberg, J. and Stone, R.G., 1973, Astrophys. Lett., vol. 14, 111; Astrophys. J., vol. 183, L35) is suggested. The analysis is carried out for two models of the electron density distribution in the interplanetary medium taking into account that N approximately 3.5 cm -3 at a distance of 1 a.u. It is assumed that the frequency of the radio emission corresponds to the average electron density behind the shock front which exceeds the undisturbed electron density by the factor of 3. The radio data indicate essential deceleration of the shock waves during propagation from the Sun up to 1 a.u. The characteristics of the shock waves obtained from the type II bursts agree with the results of the in situ observations. (author)

  9. Resonators for magnetohydrodynamic waves in the solar corona: The effect of modulation of radio emission

    International Nuclear Information System (INIS)

    Zaitsev, V.V.; Stepanov, A.V.

    1982-01-01

    It is shown that the existence of a minimum of the Alfven speed in the corona at a height of approx.1R/sub sun/ follows from the characteristics of type II radio bursts. The region of a reduced Alfven speed is a resonator for a fast magnetosonic (FMS) waves. The eigenmodes of the resonator are determined. The period of the fundamental mode has the order of several minutes. In the resonator FMS waves can be excited at the Cherenkov resonance by streams of energetic ions. Modulations of metal solar radio emission with a period of several minutes is explained by the effect of the propagation of radio waves through an oscillating magnetohydrodynamic (MHD) resonator

  10. The Relationship Between Solar Radio and Hard X-Ray Emission

    Science.gov (United States)

    White, S. M.; Benz, A. O.; Christe, S.; Farnik, F.; Kundu, M. R.; Mann, G.; Ning, Z.; Raulin, J.-P.; Silva-Valio, A. V. R.; Saint-Hilaire, P.; hide

    2011-01-01

    This review discusses the complementary relationship between radio and hard Xray observations of the Sun using primarily results from the era of the Reuven Ramaty High Energy Solar Spectroscopic Imager satellite. A primary focus of joint radio and hard X-ray studies of solar flares uses observations of nonthermal gyrosynchrotron emission at radio wavelengths and bremsstrahlung hard X-rays to study the properties of electrons accelerated in the main flare site, since it is well established that these two emissions show very similar temporal behavior. A quantitative prescription is given for comparing the electron energy distributions derived separately from the two wavelength ranges: this is an important application with the potential for measuring the magnetic field strength in the flaring region, and reveals significant differences between the electrons in different energy ranges. Examples of the use of simultaneous data from the two wavelength ranges to derive physical conditions are then discussed, including the case of microflares, and the comparison of images at radio and hard X-ray wavelengths is presented. There have been puzzling results obtained from observations of solar flares at millimeter and submillimeter wavelengths, and the comparison of these results with corresponding hard X-ray data is presented. Finally, the review discusses the association of hard X-ray releases with radio emission at decimeter and meter wavelengths, which is dominated by plasma emission (at lower frequencies) and electron cyclotron maser emission (at higher frequencies), both coherent emission mechanisms that require small numbers of energetic electrons. These comparisons show broad general associations but detailed correspondence remains more elusive.

  11. Faraday rotation fluctuations of MESSENGER radio signals through the equatorial lower corona near solar minimum

    Science.gov (United States)

    Wexler, D. B.; Jensen, E. A.; Hollweg, J. V.; Heiles, C.; Efimov, A. I.; Vierinen, J.; Coster, A. J.

    2017-02-01

    Faraday rotation (FR) of transcoronal radio transmissions from spacecraft near superior conjunction enables study of the temporal variations in coronal plasma density, velocity, and magnetic field. The MESSENGER spacecraft 8.4 GHz radio, transmitting through the corona with closest line-of-sight approach 1.63-1.89 solar radii and near-equatorial heliolatitudes, was recorded soon after the deep solar minimum of solar cycle 23. During egress from superior conjunction, FR gradually decreased, and an overlay of wave-like FR fluctuations (FRFs) with periods of hundreds to thousands of seconds was found. The FRF power spectrum was characterized by a power law relation, with the baseline spectral index being -2.64. A transient power increase showed relative flattening of the spectrum and bands of enhanced spectral power at 3.3 mHz and 6.1 mHz. Our results confirm the presence of coronal FRF similar to those described previously at greater solar offset. Interpreted as Alfvén waves crossing the line of sight radially near the proximate point, low-frequency FRF convey an energy flux density higher than that of the background solar wind kinetic energy, but only a fraction of that required to accelerate the solar wind. Even so, this fraction is quite variable and potentially escalates to energetically significant values with relatively modest changes in estimated magnetic field strength and electron concentration. Given the uncertainties in these key parameters, as well as in solar wind properties close to the Sun at low heliolatitudes, we cannot yet confidently assign the quantitative role for Alfvén wave energy from this region in driving the slow solar wind.

  12. Coronal Radio Sounding Experiments with Mars Express: Scintillation Spectra during Low Solar Activity

    International Nuclear Information System (INIS)

    Efimov, A. I.; Lukanina, L. A.; Samoznaev, L. N.; Rudash, V. K.; Chashei, I. V.; Bird, M. K.; Paetzold, M.; Tellmann, S.

    2010-01-01

    Coronal radio sounding observations were carried out with the radio science experiment MaRS on the ESA spacecraft Mars Express during the period from 25 August to 22 October 2004. Differential frequency and log-amplitude fluctuations of the dual-frequency signals were recorded during a period of low solar activity. The data are applicable to low heliographic latitudes, i.e. to slow solar wind. The mean frequency fluctuation and power law index of the frequency fluctuation temporal spectra are determined as a function of heliocentric distance. The radial dependence of the frequency fluctuation spectral index α reflects the previously documented flattening of the scintillation power spectra in the solar wind acceleration region. Temporal spectra of S-band and X-band normalized log-amplitude fluctuations were investigated over the range of fluctuation frequencies 0.01 Hz<ν<0.5 Hz, where the spectral density is approximately constant. The radial variation of the spectral density is analyzed and compared with Ulysses 1991 data, a period of high solar activity. Ranging measurements are presented and compared with frequency and log-amplitude scintillation data. Evidence for a weak increase in the fractional electron density turbulence level is obtained in the range 10-40 solar radii.

  13. Space Weather Action Plan Solar Radio Burst Phase 1 Benchmarks and the Steps to Phase 2

    Science.gov (United States)

    Biesecker, D. A.; White, S. M.; Gopalswamy, N.; Black, C.; Love, J. J.; Pierson, J.

    2017-12-01

    Solar radio bursts, when at the right frequency and when strong enough, can interfere with radar, communication, and tracking signals. In severe cases, radio bursts can inhibit the successful use of radio communications and disrupt a wide range of systems that are reliant on Position, Navigation, and Timing services on timescales ranging from minutes to hours across wide areas on the dayside of Earth. The White House's Space Weather Action Plan asked for solar radio burst intensity benchmarks for an event occurrence frequency of 1 in 100 years and also a theoretical maximum intensity benchmark. The benchmark team has developed preliminary (phase 1) benchmarks for the VHF (30-300 MHz), UHF (300-3000 MHz), GPS (1176-1602 MHz), F10.7 (2800 MHz), and Microwave (4000-20000) bands. The preliminary benchmarks were derived based on previously published work. Limitations in the published work will be addressed in phase 2 of the benchmark process. In addition, deriving theoretical maxima requires additional work, where it is even possible to, in order to meet the Action Plan objectives. In this presentation, we will present the phase 1 benchmarks, the basis used to derive them, and the limitations of that work. We will also discuss the work that needs to be done to complete the phase 2 benchmarks.

  14. Observation of solar radio bursts of type II and III at kilometer wavelengths from Prognoz-8 during STIP Interval XII

    International Nuclear Information System (INIS)

    Pinter, S.; Kecskemety, K.; Kudela, K.

    1982-04-01

    Type II and type III radio events were observed at low frequencies (2.16 MHz to 114 kHz) by the Prognoz-8 satellite during the period of STIP Interval XII in April and May, 1981, respectively. This review covers briefly a chronology of the sub-megahertz radio events, and where possible their association with both groundbased radio observations and solar flare. (author)

  15. Energetic evaluation of the largest geomagnetic storms of solar cycle 24 on March 17, 2015 and September 8, 2017 during solar maximum and minimum, respectively

    International Nuclear Information System (INIS)

    Tomova, Dimitrinka; Velinov, Peter; Tassev, Yordan; Tomova, Dimitrinka

    2018-01-01

    Some of the most powerful Earth’s directed coronal mass ejections (CMEs) from the current 24 solar cycle have been investigated. These are CMEs on March 15, 2015 and on September 4 and 6, 2017. As a result of these impacts of Sun on Earth, the highest intensity of the geomagnetic storms for the 24th solar cycle is observed. These G4 – Severe geomagnetic storms are in the periods March 17÷19, 2015 and September 7÷10, 2017. We use the solar wind parameters (velocity V, density or concentration N , temperature T p and intensity of the magnetic field B) from measurements by WIND, ACE and SOHO space crafts in the Lagrange equilibrium point L1 between Sun and Earth. We make calculations for the kinetic (dynamic) energy density E k , thermal energy density E t and magnetic energy density E m during the investigated periods May 10÷24, 2015 and September 2÷16, 2017. Both the energy densities for the individual events and the cumulative energy for each of them are evaluated. The quantitative analysis shows that not always the size of the geomagnetic reaction is commensurate with the density of the energy flux reaching the magnetosphere. In both studied periods, the energy densities have different behaviour over time. But for both periods, we can talk about the prognostic effect – with varying degrees of increase of the dynamic and thermal energies. Such an effect is not observed in the density of magnetic energy. An inverse relationship between the magnitude of the density of energies and the effect of Forbush decrease of the galactic cosmic rays is established. Key words: solar activity, flares, coronal mass ejection (CME), G4 –Severe geomagnetic storms, energy density of the solar wind, space weather

  16. Fast drift kilometric radio bursts and solar proton events

    Science.gov (United States)

    Cliver, E. W.; Kahler, S. W.; Cane, H. V.; Mcguire, R. E.; Vonrosenvinge, T. T.; Stone, R. G.

    1985-01-01

    Initial results of a comparative study of major fast drift kilometric bursts and solar proton events from Sep. 1978 to Feb. 1983 are presented. It was found that only about half of all intense, long duration ( 40 min above 500 sfu) 1 MHz bursts can be associated with F 20 MeV proton events. However, for the subset of such fast drift bursts accompanied by metric Type 2 and/or 4 activity (approximately 40% of the total), the degree of association with 20 MeV events is 80%. For the reverse association, it was found that proton events with J( 20 MeV) 0.01 1 pr cm(-2)s(-1)sr(-1)MeV(-1) were typically (approximately 80% of the time) preceded by intense 1 MHz bursts that exceeded the 500 sfu level for times 20 min (median duration approximately 35 min).

  17. Fast drift kilometric radio bursts and solar proton events

    International Nuclear Information System (INIS)

    Cliver, E.W.; Kahler, S.W.; Cane, H.V.; Mcguire, R.E.; Vonrosenvinge, T.T.; Stone, R.G.

    1985-01-01

    Initial results of a comparative study of major fast drift kilometric bursts and solar proton events from Sep. 1978 to Feb. 1983 are presented. It was found that only about half of all intense, long duration ( 40 min above 500 sfu) 1 MHz bursts can be associated with F 20 MeV proton events. However, for the subset of such fast drift bursts accompanied by metric Type 2 and/or 4 activity (approximately 40% of the total), the degree of association with 20 MeV events is 80%. For the reverse association, it was found that proton events with J( 20 MeV) 0.01 1 pr cm(-2)s(-1)sr(-1)MeV(-1) were typically (approximately 80% of the time) preceded by intense 1 MHz bursts that exceeded the 500 sfu level for times of approx. 20 min (median duration approximately 35 min)

  18. Imaging spectroscopy of type U and J solar radio bursts with LOFAR

    Science.gov (United States)

    Reid, Hamish A. S.; Kontar, Eduard P.

    2017-10-01

    Context. Radio U-bursts and J-bursts are signatures of electron beams propagating along magnetic loops confined to the corona. The more commonly observed type III radio bursts are signatures of electron beams propagating along magnetic loops that extend into interplanetary space. Given the prevalence of solar magnetic flux to be closed in the corona, why type III bursts are more frequently observed than U-bursts or J-bursts is an outstanding question. Aims: We use Low-Frequency Array (LOFAR) imaging spectroscopy between 30-80 MHz of low-frequency U-bursts and J-bursts, for the first time, to understand why electron beams travelling along coronal loops produce radio emission less often. Radio burst observations provide information not only about the exciting electron beams but also about the structure of large coronal loops with densities that are too low for standard extreme ultraviolet (EUV) or X-ray analysis. Methods: We analysed LOFAR images of a sequence of two J-bursts and one U-burst. The different radio source positions were used to model the spatial structure of the guiding magnetic flux tube and then deduce the energy range of the exciting electron beams without the assumption of a standard density model. We also estimated the electron density along the magnetic flux rope and compared it to coronal models. Results: The radio sources infer a magnetic loop that is 1 solar radius in altitude with the highest frequency sources starting around 0.6 solar radii. Electron velocities were found between 0.13 c and 0.24 c with the front of the electron beam travelling faster than the back of the electron beam. The velocities correspond to energy ranges within the beam from 0.7-11 keV to 0.7-43 keV. The density along the loop is higher than typical coronal density models and the density gradient is smaller. Conclusions: We found that a more restrictive range of accelerated beam and background plasma parameters can result in U-bursts or J-bursts, causing type III

  19. SOLAR CYCLE VARIATIONS OF THE RADIO BRIGHTNESS OF THE SOLAR POLAR REGIONS AS OBSERVED BY THE NOBEYAMA RADIOHELIOGRAPH

    Energy Technology Data Exchange (ETDEWEB)

    Nitta, Nariaki V.; DeRosa, Marc L. [Lockheed Martin Advanced Technology Center, Dept/A021S, B/252, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Sun, Xudong; Hoeksema, J. Todd [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)

    2014-01-10

    We have analyzed daily microwave images of the Sun at 17 GHz obtained with the Nobeyama Radioheliograph (NoRH) in order to study the solar cycle variations of the enhanced brightness in the polar regions. Unlike in previous works, the averaged brightness of the polar regions is obtained from individual images rather than from synoptic maps. We confirm that the brightness is anti-correlated with the solar cycle and that it has generally declined since solar cycle 22. Including images up to 2013 October, we find that the 17 GHz brightness temperature of the south polar region has decreased noticeably since 2012. This coincides with a significant decrease in the average magnetic field strength around the south pole, signaling the arrival of solar maximum conditions in the southern hemisphere more than a year after the northern hemisphere. We do not attribute the enhanced brightness of the polar regions at 17 GHz to the bright compact sources that occasionally appear in synthesized NoRH images. This is because they have no correspondence with small-scale bright regions in images from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory with a broad temperature coverage. Higher-quality radio images are needed to understand the relationship between microwave brightness and magnetic field strength in the polar regions.

  20. Coronal mass ejections, type II radio bursts, and solar energetic particle events in the SOHO era

    Directory of Open Access Journals (Sweden)

    N. Gopalswamy

    2008-10-01

    Full Text Available Using the extensive and uniform data on coronal mass ejections (CMEs, solar energetic particle (SEP events, and type II radio bursts during the SOHO era, we discuss how the CME properties such as speed, width and solar-source longitude decide whether CMEs are associated with type II radio bursts and SEP events. We discuss why some radio-quiet CMEs are associated with small SEP events while some radio-loud CMEs are not associated with SEP events. We conclude that either some fast and wide CMEs do not drive shocks or they drive weak shocks that do not produce significant levels of particle acceleration. We also infer that the Alfvén speed in the corona and near-Sun interplanetary medium ranges from <200 km/s to ~1600 km/s. Radio-quiet fast and wide CMEs are also poor SEP producers and the association rate of type II bursts and SEP events steadily increases with CME speed and width (i.e. energy. If we consider western hemispheric CMEs, the SEP association rate increases linearly from ~30% for 800 km/s CMEs to 100% for ≥1800 km/s. Essentially all type II bursts in the decametre-hectometric (DH wavelength range are associated with SEP events once the source location on the Sun is taken into account. This is a significant result for space weather applications, because if a CME originating from the western hemisphere is accompanied by a DH type II burst, there is a high probability that it will produce an SEP event.

  1. STORM IN A {sup T}EACUP{sup :} A RADIO-QUIET QUASAR WITH ≈10 kpc RADIO-EMITTING BUBBLES AND EXTREME GAS KINEMATICS

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, C. M.; Thomson, A. P.; Alexander, D. M.; Edge, A. C.; Hogan, M. T.; Swinbank, A. M. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Bauer, F. E. [Instituto de Astrofísica, Facultad de Física, Pontifica Universidad Católica de Chile, 306, Santiago 22 (Chile); Mullaney, J. R., E-mail: c.m.harrison@mail.com [Department of Physics and Astronomy, University of Sheffield, Sheffield S7 3RH (United Kingdom)

    2015-02-10

    We present multi-frequency (1-8 GHz) Very Large Array data, combined with VIsible MultiObject Spectrograph integral field unit data and Hubble Space Telescope imaging, of a z = 0.085 radio-quiet type 2 quasar (with L {sub 1.4} {sub GHz} ≈ 5 × 10{sup 23} W Hz{sup –1} and L {sub AGN} ≈ 2 × 10{sup 45} erg s{sup –1}). Due to the morphology of its emission-line region, the target (J1430+1339) has been referred to as the ''Teacup'' active galactic nucleus (AGN) in the literature. We identify ''bubbles'' of radio emission that are extended ≈10-12 kpc to both the east and west of the nucleus. The edge of the brighter eastern bubble is co-spatial with an arc of luminous ionized gas. We also show that the ''Teacup'' AGN hosts a compact radio structure, located ≈0.8 kpc from the core position, at the base of the eastern bubble. This radio structure is co-spatial with an ionized outflow with an observed velocity of v = –740 km s{sup –1}. This is likely to correspond to a jet, or possibly a quasar wind, interacting with the interstellar medium at this position. The large-scale radio bubbles appear to be inflated by the central AGN, which indicates that the AGN can also interact with the gas on ≳ 10 kpc scales. Our study highlights that even when a quasar is formally ''radio-quiet'' the radio emission can be extremely effective for observing the effects of AGN feedback.

  2. THE CHROMOSPHERIC SOLAR LIMB BRIGHTENING AT RADIO, MILLIMETER, SUB-MILLIMETER, AND INFRARED WAVELENGTHS

    Energy Technology Data Exchange (ETDEWEB)

    De la Luz, V. [Conacyt—SCiESMEX, Instituto de Geofísica, Unidad Michoacán, Universidad Nacional Autónoma de México, Morelia, Michoacán, 58190, México (Mexico)

    2016-07-10

    Observations of the emission at radio, millimeter, sub-millimeter, and infrared wavelengths in the center of the solar disk validate the autoconsistence of semi-empirical models of the chromosphere. Theoretically, these models must reproduce the emission at the solar limb. In this work, we tested both the VALC and C7 semi-empirical models by computing their emission spectrum in the frequency range from 2 GHz to 10 THz at solar limb altitudes. We calculate the Sun's theoretical radii as well as their limb brightening. Non-local thermodynamic equilibrium was computed for hydrogen, electron density, and H{sup −}. In order to solve the radiative transfer equation, a three-dimensional (3D) geometry was employed to determine the ray paths, and Bremsstrahlung, H{sup −}, and inverse Bremsstrahlung opacity sources were integrated in the optical depth. We compared the computed solar radii with high-resolution observations at the limb obtained by Clark. We found that there are differences between the observed and computed solar radii of 12,000 km at 20 GHz, 5000 km at 100 GHz, and 1000 km at 3 THz for both semi-empirical models. A difference of 8000 km in the solar radii was found when comparing our results against the heights obtained from H α observations of spicules-off at the solar limb. We conclude that the solar radii cannot be reproduced by VALC and C7 semi-empirical models at radio—infrared wavelengths. Therefore, the structures in the high chromosphere provide a better measurement of the solar radii and their limb brightening as shown in previous investigations.

  3. THE CHROMOSPHERIC SOLAR LIMB BRIGHTENING AT RADIO, MILLIMETER, SUB-MILLIMETER, AND INFRARED WAVELENGTHS

    International Nuclear Information System (INIS)

    De la Luz, V.

    2016-01-01

    Observations of the emission at radio, millimeter, sub-millimeter, and infrared wavelengths in the center of the solar disk validate the autoconsistence of semi-empirical models of the chromosphere. Theoretically, these models must reproduce the emission at the solar limb. In this work, we tested both the VALC and C7 semi-empirical models by computing their emission spectrum in the frequency range from 2 GHz to 10 THz at solar limb altitudes. We calculate the Sun's theoretical radii as well as their limb brightening. Non-local thermodynamic equilibrium was computed for hydrogen, electron density, and H − . In order to solve the radiative transfer equation, a three-dimensional (3D) geometry was employed to determine the ray paths, and Bremsstrahlung, H − , and inverse Bremsstrahlung opacity sources were integrated in the optical depth. We compared the computed solar radii with high-resolution observations at the limb obtained by Clark. We found that there are differences between the observed and computed solar radii of 12,000 km at 20 GHz, 5000 km at 100 GHz, and 1000 km at 3 THz for both semi-empirical models. A difference of 8000 km in the solar radii was found when comparing our results against the heights obtained from H α observations of spicules-off at the solar limb. We conclude that the solar radii cannot be reproduced by VALC and C7 semi-empirical models at radio—infrared wavelengths. Therefore, the structures in the high chromosphere provide a better measurement of the solar radii and their limb brightening as shown in previous investigations.

  4. Radio wave propagation in the inhomogeneous magnetic field of the solar corona

    International Nuclear Information System (INIS)

    Zheleznyakov, V.V.; Zlotnik, E.Ya.

    1977-01-01

    Various types of linear coupling between ordinary and extra-ordinary waves in the coronal plasma with the inhomogeneous magnetic field and the effect of this phenomenon upon the polarization characteristics of solar radio emission are considered. A qualitative analysis of the wave equation indicates that in a rarefied plasma the coupling effects can be displayed in a sufficiently weak magnetic field or at the angles between the magnetic field and the direction of wave propagation close enough to zero or π/2. The wave coupling parameter are found for these three cases. The radio wave propagation through the region with a quasi-transverse magnetic field and through the neutral current sheet is discussed more in detail. A qualitative picture of coupling in such a layer is supported by a numerical solution of the ''quasi-isotropic approximation'' equations. The role of the coupling effects in formation of polarization characteristics of different components of solar radio emission has been investigated. For cm wave range, the polarization is essentially dependent on the conditions in the region of the transverse magnetic field

  5. Solar radio bursts of spectral type II, coronal shocks, and optical coronal transients

    Science.gov (United States)

    Maxwell, A.; Dryer, M.

    1981-01-01

    An examination is presented of the association of solar radio bursts of spectral type II and coronal shocks with solar flare ejecta observed in H-alpha, the green coronal line, and white-light coronagraphs. It is suggested that fast-moving optical coronal transients should for the most part be identified with piston-type phenomena well behind the outward-traveling shock waves that generate type II radio bursts. A general model is presented which relates type II radio bursts and coronal shocks to optically observed ejecta and consists of three main velocity regimes: (1) a quasi-hemispherical shock wave moving outward from the flare at speeds of 1000-2000 km/sec and Alfven Mach number of about 1.5; (2) the velocity of the piston driving the shock, on the order of 0.8 that of the shock; and (3) the regime of the slower-moving H-alpha ejecta, with velocities of 300-500 km/sec.

  6. The influence of solar active region evolution on solar wind streams, coronal hole boundaries and geomagnetic storms

    International Nuclear Information System (INIS)

    Gold, R.E.; Dodson-Prince, H.W.; Hedeman, E.R.; Roelof, E.C.

    1982-01-01

    We have studied solar and interplanetary data by identification of the heliographic longitudes of the coronal source regions of high speed solar wind streams and by mapping the velocities measured near earth back to the sun using the approximation of constant radial velocity. Interplay of active regions and solar wind were studied

  7. Fast solar electrons, interplanetary plasma and km-wave type-III radio bursts observed from the IMP-6 spacecraft

    International Nuclear Information System (INIS)

    Alvarez, H.; Lin, R.P.

    1975-01-01

    IMP-6 spacecraft observations of low frequency radio emission, fast electrons, and solar wind plasma are used to examine the dynamics of the fast electron streams which generate solar type-III radio bursts. Of twenty solar electron events observed between April 1971 and August 1972, four were found to be amenable to detailed analysis. Observations of the direction of arrival of the radio emission at different frequencies were combined with the solar wind density and velocity measurements at 1 AU to define an Archimedean spiral trajectory for the radio burst exciter. The propagation characteristics of the exciter and of the fast electrons observed at 1 AU were then compared. It is found that: (1) the fast electrons excite the radio emission at the second harmonic; (2) the total distance travelled by the electrons was between 30 and 70% longer than the length of the smooth spiral defined by the radio observations; (3) this additional distance travelled is the result of scattering of the electrons in the interplanetary medium; (4) the observations are consistent with negligible true energy loss by the fast electrons.(Auth.)

  8. An analysis of interplanetary solar radio emissions associated with a coronal mass ejection

    Czech Academy of Sciences Publication Activity Database

    Krupař, Vratislav; Eastwood, J. P.; Krupařová, Oksana; Santolík, Ondřej; Souček, Jan; Magdalenic, J.; Vourlidas, A.; Maksimovic, M.; Bonnin, X.; Bothmer, V.; Mrotzek, N.; Pluta, A.; Barnes, D.; Davies, J. A.; Oliveros, J.C.M.; Bale, S. D.

    2016-01-01

    Roč. 823, č. 1 (2016) ISSN 2041-8205 R&D Projects: GA ČR GJ16-16050Y; GA ČR(CZ) GAP209/12/2394; GA MŠk(CZ) LH15304 Grant - others:AV ČR(CZ) AP1401 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378289 Keywords : solar -terrestrial relations * coronal mass ejections (CMEs) * radio radiation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 5.522, year: 2016 http://iopscience.iop.org/article/10.3847/2041-8205/823/1/L5/meta

  9. The effect of initial conditions on the electromagnetic radiation generation in type III solar radio bursts

    International Nuclear Information System (INIS)

    Schmitz, H.; Tsiklauri, D.

    2013-01-01

    Extensive particle-in-cell simulations of fast electron beams injected in a background magnetised plasma with a decreasing density profile were carried out. These simulations were intended to further shed light on a newly proposed mechanism for the generation of electromagnetic waves in type III solar radio bursts [D. Tsiklauri, Phys. Plasmas, 18, 052903 (2011)]. The numerical simulations were carried out using different density profiles and fast electron distribution functions. It is shown that electromagnetic L and R modes are excited by the transverse current, initially imposed on the system. In the course of the simulations, no further interaction of the electron beam with the background plasma could be observed

  10. Solar Radio Observation using Callisto Spectrometer at Sumedang West Java Indonesia: Current Status and Future Development Plan in Indonesia

    Science.gov (United States)

    Manik, T.; Sitompul, P.; Batubara, M.; Harjana, T.; Yatini, C. Y.; Monstein, C.

    2016-04-01

    Sumedang Observatory (6.91°S, 107,84°E) was established in 1975 and is one of the solar observation facilities of the Space Science Center of Indonesian National Institute of Aeronautics and Space (LAPAN), located around 40 km, east part of Bandung City, West Java, Indonesia. Several instrumentations for solar and space observation such as optical telescopes, radio solar spectrograph, flux gate magnetometer, etc. are operated there, together with an ionosphere sounding system (ionosonde) that was set up later. In July 2014, a standard Callisto (Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory) spectrometer was installed at Sumedang Observatory for solar radio activity monitoring. Callisto has been developed in the framework of IHY2007 and ISWI, supported by UN and NASA. Callisto spectrometer has observation capability in the frequency range of 45-870 MHz. The Callisto spectrometer receives signal by using a set of 21 elements log-periodic antenna, model CLP5130-1N, pointed to the Sun and equipped with a low noise pre-amplifier. With respect to the Radio Frequency Interferences (RFI) measurements, the Callisto spectrometer is operated individually in frequency ranges of 45-80 MHz and 180-450 MHz. Observation status and data flow are monitored in on-line from center office located in Bandung. The data was transferred to central database at FHNW (Fachhochschule Nordwestschweiz) server every 15 minutes to appear on e-Callisto network subsequently. A real time data transfer and data processing based on Python software also has been developed successfully to be used as an input for Space Weather Information and Forecasting Services (SWIFtS) provided by LAPAN. On 5th November 2014, Callisto spectrometer at Sumedang observed the first clear solar radio event, a solar radio burst type II corresponding to a coronal mass ejection (CME), indicated by a strong X-ray event of M7.9 that was informed on by Space Weather

  11. Three-dimensional Langmuir wave instabilities in type III solar radio bursts

    International Nuclear Information System (INIS)

    Bardwell, S.; Goldman, M.V.

    1976-01-01

    Assuming that type III solar radio bursts are associated with electron streams moving at about c/3, Langmuir waves should be strongly excited. We have studied all of the Langmuir-wave linear parametric instabilities excited in cylindrical symmetry by an electron-stream--driven Langmuir wave-pump propagating along the stream axis. Included in this unified homogeneous treatment are induced backscattering off ions, the oscillating two-stream instability, and a new ''stimulated modulational instability,'' previously unconsidered in this context. Near a few solar radii, the latter two deposit Langmuir wave energy into a forward-scattering cone about the stream axis. It is concluded that the linear stage of the forward-scattering instabilities involves transfer of energy to Langmuir waves which remain in resonance with the stream, and therefore probably do not prevent rapid depletion of the electron stream due to quasilinear plateau formation at these distances from the Sun

  12. Stimulation of auroral kilometric radiation by type III solar radio bursts

    International Nuclear Information System (INIS)

    Calvert, W.

    1981-01-01

    It has been found that the onset of auroral kilometric radiation (AKR) frequently coincides with the arrival of type III solar radio bursts. Although the AKR onsets are usually abrupt and appear to be spontaneous, they sometimes develop from a discrete frequency near the leading edge of a type III burst or sometimes occur at progressively lower frequencies following that edge. From this, and the absence of the related solar electrons in specific cases, it was concluded that the incoming type III waves were sometimes responsible for stimulating auroral kilometric radiation. It was estimated that intense, isolated type III bursts were capable of stimulating AKR roughly one third of the time, and that at least ten percent of the observed AKR onsets could be attributed to these and weaker bursts, including some barely detectable by the ISEE plasma wave receivers

  13. Detailed Analysis of Solar Data Related to Historical Extreme Geomagnetic Storms: 1868 – 2010

    DEFF Research Database (Denmark)

    Lefèvre, Laure; Vennerstrøm, Susanne; Dumbović, Mateja

    2016-01-01

    An analysis of historical Sun–Earth connection events in the context of the most extreme space weather events of the last ∼ 150 years is presented. To identify the key factors leading to these extreme events, a sample of the most important geomagnetic storms was selected based mainly on the well-...

  14. Variation in the WWV, 15 MHz field strength received at Hiraiso during a low solar activity and the application of the result to radio disturbance warning services

    International Nuclear Information System (INIS)

    Ohshio, Mitsuo; Kidokoro, Tsuneichi

    1978-01-01

    Recurrent geomagnetic storms occur predominantly apparently during the period of low solar activity. Radio disturbance warning services are apt to be made in terms of geomagnetic disturbances in this period. This analysis has been made from the standpoint of making the electric field strength of a short wave (WWV, 15 MHz) circuit with a long distance received at Hiraiso, Japan correspond to not only geomagnetic disturbances, but also its absorption in the ionosphere. The electric field strength has been treated as a newly introduced daily mean value of time-integrated one in this paper. The result has been obtained from the analysis that about 2/3 of the daily electric field strength of the total cases treated were influenced by geomagnetic disturbances and that about 2/3 within the remaining about 1/3 proved to be influenced by the ionospheric absorption, ionospheric parameters such as f sub(min) and the phase of a VLF radio wave circuit being used. The strength has been considered to be influenced by the absorption also in case of being influenced by geomagnetic disturbances. The remaining about 1/9 of the total cases could not correspond to its cause. Some applications of the consideration have been made to practical problems. (author)

  15. An operational integrated short-term warning solution for solar radiation storms: introducing the Forecasting Solar Particle Events and Flares (FORSPEF) system

    Science.gov (United States)

    Anastasiadis, Anastasios; Sandberg, Ingmar; Papaioannou, Athanasios; Georgoulis, Manolis; Tziotziou, Kostas; Jiggens, Piers; Hilgers, Alain

    2015-04-01

    We present a novel integrated prediction system, of both solar flares and solar energetic particle (SEP) events, which is in place to provide short-term warnings for hazardous solar radiation storms. FORSPEF system provides forecasting of solar eruptive events, such as solar flares with a projection to coronal mass ejections (CMEs) (occurrence and velocity) and the likelihood of occurrence of a SEP event. It also provides nowcasting of SEP events based on actual solar flare and CME near real-time alerts, as well as SEP characteristics (peak flux, fluence, rise time, duration) per parent solar event. The prediction of solar flares relies on a morphological method which is based on the sophisticated derivation of the effective connected magnetic field strength (Beff) of potentially flaring active-region (AR) magnetic configurations and it utilizes analysis of a large number of AR magnetograms. For the prediction of SEP events a new reductive statistical method has been implemented based on a newly constructed database of solar flares, CMEs and SEP events that covers a large time span from 1984-2013. The method is based on flare location (longitude), flare size (maximum soft X-ray intensity), and the occurrence (or not) of a CME. Warnings are issued for all > C1.0 soft X-ray flares. The warning time in the forecasting scheme extends to 24 hours with a refresh rate of 3 hours while the respective warning time for the nowcasting scheme depends on the availability of the near real-time data and falls between 15-20 minutes. We discuss the modules of the FORSPEF system, their interconnection and the operational set up. The dual approach in the development of FORPSEF (i.e. forecasting and nowcasting scheme) permits the refinement of predictions upon the availability of new data that characterize changes on the Sun and the interplanetary space, while the combined usage of solar flare and SEP forecasting methods upgrades FORSPEF to an integrated forecasting solution. This

  16. Numerical simulation of nonlinear beam-plasma interaction for the application to solar radio burst

    International Nuclear Information System (INIS)

    Takakura, T.

    1981-01-01

    By the use of semi-analytical method the numerical simulations for the nonlinear scattering of axially symmetric plasma waves into plasma waves and radio waves have been made. The initial electron beam has a finite length and one-dimensional velocity distribution of power law. Induced back-scattering of plasma waves by thermal ions is strong even for a solar electron stream of rather low flux, say 2x10 11 cm -2 above 5 keV at fsub(p) of 40 MHz, which is enough to emit the observed type III bursts as the second harmonic. The ratio between the energy densities of plasma waves and thermal electrons (nkT) is of the order of 10 -6 , which may be a few orders lower than the threshold value for a caviton collapse of the plasma waves to occur. The second harmonic radio emission as attributed to the coalescence of two plasma waves, i.e. one excited by electron beam and one back-scattered by ions, is several orders higher than the fundamental radio emission caused by the scattering of plasma waves by thermal ions. (Auth.)

  17. Magnetic storm injection of 0.9- to 16-keV/e solar and terrestrial ions into the high-altitude magnetosphere

    International Nuclear Information System (INIS)

    Balsiger, H.; Eberhardt, P.; Geiss, J.; Young, D.T.

    1980-01-01

    The Geos 1 ion composition experiments has surveyed the plasma composition in the energy per charge range below 16 keV/e at all local times and at L=3--8. During quiet and moderately disturbed times, H + is the dominant species with a few percent of heavy (M/Q>1) ions. Substorms and storms increase the relative amount of heavy ions, and occasionally, they can become the dominant species in the outer magnetosphere. Two sources, the solar wind (characterized by 4 He ++ ) and the ionosphere (characterized by O + ), give on the average comparable contributions to storm time plasma, although in individual storms one or the other may dominate. Data presented here suggest that high-altitude thermal plasma or the plasmasphere (characterized by He + and O ++ ) must be considered as a third source. Under storm conditions with Geos in the dawn-noon local time sector we have observed a mixed composition region just inside the magnetopause where high fluxes of H + , He ++ , O + , and occasionally He + ions are present. During several storms a composition profile could be measured down to Lapprox.3. Both O + and He + increase toward low altitudes, and O + (within our energy range) can become dominant at the inner edge of the ring current. On April 30, 1978, during a storm, O + contributed > or approx. =8% to the total local energy density of the ring current particles at L=4.1. In no storm has He + been observed to be the main constituent during the recovery phase. During storm recovery, H + and O + are the dominant ions, the H + /O + ratio remaining constant or even increasing during the days following the main phase of the storms. This suggests that charge exchange is not the only loss mechanism for the storm time ring current and/or that H + is replenished during the recovery phase

  18. Low-Frequency Radio Bursts and Space Weather

    Science.gov (United States)

    Gopalswamy, N.

    2016-01-01

    Low-frequency radio phenomena are due to the presence of nonthermal electrons in the interplanetary (IP) medium. Understanding these phenomena is important in characterizing the space environment near Earth and other destinations in the solar system. Substantial progress has been made in the past two decades, because of the continuous and uniform data sets available from space-based radio and white-light instrumentation. This paper highlights some recent results obtained on IP radio phenomena. In particular, the source of type IV radio bursts, the behavior of type III storms, shock propagation in the IP medium, and the solar-cycle variation of type II radio bursts are considered. All these phenomena are closely related to solar eruptions and active region evolution. The results presented were obtained by combining data from the Wind and SOHO missions.

  19. Production of fine structures in type III solar radio bursts due to turbulent density profiles

    International Nuclear Information System (INIS)

    Loi, Shyeh Tjing; Cairns, Iver H.; Li, Bo

    2014-01-01

    Magnetic reconnection events in the corona release energetic electron beams along open field lines, and the beams generate radio emission at multiples of the electron plasma frequency f p to produce type III solar radio bursts. Type III bursts often exhibit irregularities in the form of flux modulations with frequency and/or local temporal advances and delays, and a type IIIb burst represents the extreme case where a type III burst is fragmented into a chain of narrowband features called striae. Remote and in situ spacecraft measurements have shown that density turbulence is ubiquitous in the corona and solar wind, and often exhibits a Kolmogorov power spectrum. In this work, we numerically investigate the effects of one-dimensional macroscopic density turbulence (along the beam direction) on the behavior of type III bursts, and find that this turbulence produces stria-like fine structures in the dynamic spectra of both f p and 2 f p radiation. Spectral and temporal fine structures in the predicted type III emission are produced by variations in the scattering path lengths and group speeds of radio emission, and in the locations and sizes of emitting volumes. Moderate turbulence levels yield flux enhancements with much broader half-power bandwidths in f p than 2 f p emission, possibly explaining the often observed type IIIb-III harmonic pairs as being where intensifications in 2 f p radiation are not resolved observationally. Larger turbulence levels producing trough-peak regions in the plasma density profile may lead to broader, resolvable intensifications in 2 f p radiation, which may account for the type IIIb-IIIb pairs that are sometimes observed.

  20. Atlas of fine structures of dynamic spectra of solar type IV-dm and some type II radio bursts

    International Nuclear Information System (INIS)

    Slottje, C.

    1982-01-01

    The author presents an atlas of spectral fine structures of solar radio bursts of types IV and II around 1 m wavelength, as obtained with a multichannel spectrograph at Dwingeloo. The structures form largely a collection of observations of these events during late 1968 through 1974, thus covering almost entirely the declining branch of solar cycle 20. The spectrograph has an extra enhanced contrast output with properties quite different from those of the commonly used swept frequency spectrographs. The corresponding instrumental characteristics and effects are discussed. A classification of fine structures and an analysis of their statistical properties and of those of the pertinent radio events are also given. (Auth.)

  1. Dense solar wind cloud geometries deduced from comparisons of radio signal delay and in situ plasma measurements

    Science.gov (United States)

    Landt, J. A.

    1974-01-01

    The geometries of dense solar wind clouds are estimated by comparing single-location measurements of the solar wind plasma with the average of the electron density obtained by radio signal delay measurements along a radio path between earth and interplanetary spacecraft. Several of these geometries agree with the current theoretical spatial models of flare-induced shock waves. A new class of spatially limited structures that contain regions with densities greater than any observed in the broad clouds is identified. The extent of a cloud was found to be approximately inversely proportional to its density.

  2. Effects of the 2017 Solar Eclipse on HF Radio Propagation and the D-Region Ionosphere: Citizen Science Investigation

    Science.gov (United States)

    Fry, C. D.; Adams, M.; Gallagher, D. L.; Habash Krause, L.; Rawlins, L.; Suggs, R. M.; Anderson, S. C.

    2017-12-01

    August 21, 2017 provided a unique opportunity to investigate the effects of the total solar eclipse on high frequency (HF) radio propagation and ionospheric variability. In Marshall Space Flight Center's partnership with the US Space and Rocket Center (USSRC) and Austin Peay State University (APSU), we engaged students and citizen scientists in an investigation of the eclipse effects on the mid-latitude ionosphere. The Amateur Radio community has developed several automated receiving and reporting networks that draw from widely-distributed, automated and manual radio stations to build a near-real time, global picture of changing radio propagation conditions. We used these networks and employed HF radio propagation modeling in our investigation. A Ham Radio Science Citizen Investigation (HamSCI) collaboration with the American Radio Relay League (ARRL) ensured that many thousands of amateur radio operators would be "on the air" communicating on eclipse day, promising an extremely large quantity of data would be collected. Activities included implementing and configuring software, monitoring the HF Amateur Radio frequency bands and collecting radio transmission data on days before, the day of, and days after the eclipse to build a continuous record of changing propagation conditions as the moon's shadow marched across the United States. Our expectations were the D-Region ionosphere would be most impacted by the eclipse, enabling over-the-horizon radio propagation on lower HF frequencies (3.5 and 7 MHz) that are typically closed during the middle of the day. Post-eclipse radio propagation analysis provided insights into ionospheric variability due to the eclipse. We report on results, interpretation, and conclusions of these investigations.

  3. Modeling the entry and trapping of solar energetic particles in the magnetosphere during the November 24-25, 2001 storm

    Science.gov (United States)

    Richard, R. L.; El-Alaoui, M.; Ashour-Abdalla, M.; Walker, R. J.

    2009-04-01

    We have modeled the entry of solar energetic particles (SEPs) into the magnetosphere during the November 24-25, 2001 magnetic storm and the trapping of particles in the inner magnetosphere. The study used the technique of following many test particles, protons with energies greater than about 100 keV, in the electric and magnetic fields from a global magnetohydrodynamic (MHD) simulation of the magnetosphere during this storm. SEP protons formed a quasi-trapped and trapped population near and within geosynchronous orbit. Preliminary data comparisons show that the simulation does a reasonably good job of predicting the differential flux measured by geosynchronous spacecraft. Particle trapping took place mainly as a result of particles becoming non-adiabatic and crossing onto closed field lines. Particle flux in the inner magnetosphere increased dramatically as an interplanetary shock impacted and compressed the magnetosphere near 0600 UT, but long term trapping (hours) did not become widespread until about an hour later, during a further compression of the magnetosphere. Trapped and quasi-trapped particles were lost during the simulation by motion through the magnetopause and by precipitation, primarily the former. This caused the particle population near and within geosynchronous orbit to gradually decrease later on during the latter part of the interval.

  4. Solar Flares, Type III Radio Bursts, Coronal Mass Ejections, and Energetic Particles

    Science.gov (United States)

    Cane, Hilary V.; Erickson, W. C.; Prestage, N. P.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    In this correlative study between greater than 20 MeV solar proton events, coronal mass ejections (CMEs), flares, and radio bursts it is found that essentially all of the proton events are preceded by groups of type III bursts and all are preceded by CMEs. These type III bursts (that are a flare phenomenon) usually are long-lasting, intense bursts seen in the low-frequency observations made from space. They are caused by streams of electrons traveling from close to the solar surface out to 1 AU. In most events the type III emissions extend into, or originate at, the time when type II and type IV bursts are reported (some 5 to 10 minutes after the start of the associated soft X-ray flare) and have starting frequencies in the 500 to approximately 100 MHz range that often get lower as a function of time. These later type III emissions are often not reported by ground-based observers, probably because of undue attention to type II bursts. It is suggested to call them type III-1. Type III-1 bursts have previously been called shock accelerated (SA) events, but an examination of radio dynamic spectra over an extended frequency range shows that the type III-1 bursts usually start at frequencies above any type II burst that may be present. The bursts sometimes continue beyond the time when type II emission is seen and, furthermore, sometimes occur in the absence of any type II emission. Thus the causative electrons are unlikely to be shock accelerated and probably originate in the reconnection regions below fast CMEs. A search did not find any type III-1 bursts that were not associated with CMEs. The existence of low-frequency type III bursts proves that open field lines extend from within 0.5 radius of the Sun into the interplanetary medium (the bursts start above 100 MHz, and such emission originates within 0.5 solar radius of the solar surface). Thus it is not valid to assume that only closed field lines exist in the flaring regions associated with CMEs and some

  5. The influence of solar active region evolution on solar wind streams, coronal hole boundaries and geomagnetic storms

    Science.gov (United States)

    Gold, R. E.; Dodson-Prince, H. W.; Hedeman, E. R.; Roelof, E. C.

    1982-01-01

    Solar and interplanetary data are examined, taking into account the identification of the heliographic longitudes of the coronal source regions of high speed solar wind (SW) streams by Nolte and Roelof (1973). Nolte and Roelof have 'mapped' the velocities measured near earth back to the sun using the approximation of constant radial velocity. The 'Carrington carpet' for rotations 1597-1616 is shown in a graph. Coronal sources of high speed streams appear in the form of solid black areas. The contours of the stream sources are laid on 'evolutionary charts' of solar active region histories for the Southern and Northern Hemispheres. Questions regarding the interplay of active regions and solar wind are investigated, giving attention to developments during the years 1973, 1974, and 1975.

  6. Reconstruction of solar wind features that caused a super geomagnetic storm

    Science.gov (United States)

    Lui, A. T. Y.; Gonzalez, W. D.

    2013-06-01

    A superstorm with Dst < -300 nT can cause major space disturbances. We examine one on March 31, 2001 that has the minimum Dst of -387 nT and obtain two-dimensional maps in pressure and magnetic field of the sheath region and a magnetic cloud behind it. Both the sheath and the magnetic cloud play a role in building the storm strength. Several properties of the magnetic cloud are inferred, including an estimated total magnetic flux of ~6.5×1012 Wb.

  7. Generation of type III solar radio bursts: the role of induced scattering of plasma waves by ions

    International Nuclear Information System (INIS)

    Levin, B.N.; Lerner, A.M.; Rapoport, V.O.

    1984-01-01

    The plasma waves in type III solar radio-burst sources might have a spectrum which can explain why, in the quasilinear burst generation model, nonlinear scattering of the waves by ions is so weak. The agent exciting a burst would travel through the corona at velocities limited to a definite range

  8. Role of the lifetime of ring current particles on the solar wind-magnetosphere power transfer during the intense geomagnetic storm of 28 August 1978

    International Nuclear Information System (INIS)

    Gonzalez, W.D.; Gonzalez, A.L.C.; Lee, L.C.

    1990-01-01

    For the intense magnetic storms of 28 August 1978 it is shown that the power transfer from the solar wind to the magnetosphere is well represented by the expression obtained by Vasyliunas et al. (1982, Planet. Space Sci. 30, 359) from dimensional analysis, but this representation becomes improved when such an expression is modified by a factor due to an influence of the lifetime of ring current particles as suggested by Lee and Akasofu (1984, Planet. Space Sci. 32, 1423). During a steady state regime of the ring current evolution of this storm, our study suggests that the power transfer depends on the solar wind density, the transverse component of the IMF (Interplanetary magnetic field) (with respect to the Sun-Earth line) and also, explicitly, on the time constant for ring current energy decay, but not on the solar wind speed. (author)

  9. Solar--geophysical data number 381. Part II. (Comprehensive reports). Data for November 1975-October 1975 and miscellanea. Explanation of data reports issued as number 378 (supplement) February 1976

    International Nuclear Information System (INIS)

    Leighton, H.I.

    1976-05-01

    This is part two (comprehensive reports) of a two part report on Solar--Geophysical Data. Included in this report are data for the months of October and November. The data recorded include solar flares, solar radio waves, energetic solar particles and plasma, and magnetograms of geomagnetic storms

  10. LOW-FREQUENCY OBSERVATIONS OF TRANSIENT QUASI-PERIODIC RADIO EMISSION FROM THE SOLAR ATMOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Sasikumar Raja, K.; Ramesh, R., E-mail: sasikumar@iiap.res.in [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560 034 (India)

    2013-09-20

    We report low-frequency observations of quasi-periodic, circularly polarized, harmonic type III radio bursts whose associated sunspot active regions were located close to the solar limb. The measured periodicity of the bursts at 80 MHz was ≈5.2 s, and their average degree of circular polarization (dcp) was ≈0.12. We calculated the associated magnetic field B (1) using the empirical relationship between the dcp and B for the harmonic type III emission, and (2) from the observed quasi-periodicity of the bursts. Both the methods result in B ≈ 4.2 G at the location of the 80 MHz plasma level (radial distance r ≈ 1.3 R{sub ☉}) in the active region corona.

  11. Relation between gamma-ray emission, radio bursts, and proton fluxes from solar flares

    International Nuclear Information System (INIS)

    Fomichev, V.V.; Chertok, I.M.

    1985-01-01

    Data on solar gamma-ray flares, including 24 flares with gamma-ray lines, recorded up to June 1982, are analyzed. It is shown that from the point of view of radio emission the differences between flares with and without gamma-ray lines has a purely quantitative character: the former are accompanied by the most intense microwave bursts. Meter type II bursts are not a distinctive feature of flares with gamma-ray lines. Pulsed flares, regardless of the presence or absence of gamma-ray lines, are not accompanied by significant proton fluxes at the earth. On the whole, contrary to the popular opinion in the literature, flares with gamma-ray lines do not display a deficit of proton flux in interplanetary space in comparison with similar flares without gamma-ray lines. The results of quantitative diagnostics of proton flares based on radio bursts are not at variance with the presence of flares without detectable gamma-ray emission in lines but with a pronounced increase in the proton flux at the earth. 23 references

  12. Wavelet-based Characterization of Small-scale Solar Emission Features at Low Radio Frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, A. [Indian Institute of Science Education and Research, Pune-411008 (India); Sharma, R.; Oberoi, D. [National Centre for Radio Astrophysics, Tata Institute for Fundamental Research, Pune 411007 (India); Das, S. B. [Indian Institute of Science Education and Research, Kolkata-741249 (India); Pankratius, V.; Lonsdale, C. J.; Cappallo, R. J.; Corey, B. E.; Kratzenberg, E. [MIT Haystack Observatory, Westford, MA 01886 (United States); Timar, B. [California Institute of Technology, Pasadena, CA 91125 (United States); Bowman, J. D. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Briggs, F. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Deshpande, A. A. [Raman Research Institute, Bangalore 560080 (India); Emrich, D. [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102 (Australia); Goeke, R. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Greenhill, L. J. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Hazelton, B. J. [Department of Physics, University of Washington, Seattle, WA 98195 (United States); Johnston-Hollitt, M. [School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140 (New Zealand); Kaplan, D. L. [Department of Physics, University of Wisconsin–Milwaukee, Milwaukee, WI 53201 (United States); Kasper, J. C., E-mail: akshay@students.iiserpune.ac.in [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); and others

    2017-07-01

    Low radio frequency solar observations using the Murchison Widefield Array have recently revealed the presence of numerous weak short-lived narrowband emission features, even during moderately quiet solar conditions. These nonthermal features occur at rates of many thousands per hour in the 30.72 MHz observing bandwidth, and hence necessarily require an automated approach for their detection and characterization. Here, we employ continuous wavelet transform using a mother Ricker wavelet for feature detection from the dynamic spectrum. We establish the efficacy of this approach and present the first statistically robust characterization of the properties of these features. In particular, we examine distributions of their peak flux densities, spectral spans, temporal spans, and peak frequencies. We can reliably detect features weaker than 1 SFU, making them, to the best of our knowledge, the weakest bursts reported in literature. The distribution of their peak flux densities follows a power law with an index of −2.23 in the 12–155 SFU range, implying that they can provide an energetically significant contribution to coronal and chromospheric heating. These features typically last for 1–2 s and possess bandwidths of about 4–5 MHz. Their occurrence rate remains fairly flat in the 140–210 MHz frequency range. At the time resolution of the data, they appear as stationary bursts, exhibiting no perceptible frequency drift. These features also appear to ride on a broadband background continuum, hinting at the likelihood of them being weak type-I bursts.

  13. Interplanetary ions during an energetic storm particle event - The distribution function from solar wind thermal energies to 1.6 MeV

    Science.gov (United States)

    Gosling, J. T.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Zwickl, R. D.; Paschmann, G.; Sckopke, N.; Hynds, R. J.

    1981-01-01

    An ion velocity distribution function of the postshock phase of an energetic storm particle (ESP) event is obtained from data from the ISEE 2 and ISEE 3 experiments. The distribution function is roughly isotropic in the solar wind frame from solar wind thermal energies to 1.6 MeV. The ESP event studied (8/27/78) is superposed upon a more energetic particle event which was predominantly field-aligned and which was probably of solar origin. The observations suggest that the ESP population is accelerated directly out of the solar wind thermal population or its quiescent suprathermal tail by a stochastic process associated with shock wave disturbance. The acceleration mechanism is sufficiently efficient so that approximately 1% of the solar wind population is accelerated to suprathermal energies. These suprathermal particles have an energy density of approximately 290 eV cubic centimeters.

  14. Association of solar flares with coronal mass ejections accompanied by Deca-Hectometric type II radio burst for two solar cycles 23 and 24

    Science.gov (United States)

    Kharayat, Hema; Prasad, Lalan; Pant, Sumit

    2018-05-01

    The aim of present study is to find the association of solar flares with coronal mass ejections (CMEs) accompanied by Deca-Hectometric (DH) type II radio burst for the period 1997-2014 (solar cycle 23 and ascending phase of solar cycle 24). We have used a statistical analysis and found that 10-20∘ latitudinal belt of northern region and 80-90∘ longitudinal belts of western region of the sun are more effective for flare-CME accompanied by DH type II radio burst events. M-class flares (52%) are in good association with the CMEs accompanied by DH type II radio burst. Further, we have calculated the flare position and found that most frequent flare site is at the center of the CME span. However, the occurrence probability of all flares is maximum outside the CME span. X-class flare associated CMEs have maximum speed than that of M, C, and B-class flare associated CMEs. We have also found a good correlation between flare position and central position angle of CMEs accompanied by DH type II radio burst.

  15. Solar particle radiation storms forecasting and analysis the HESPERIA HORIZON 2020 project and beyond

    CERN Document Server

    Crosby, Norma

    2018-01-01

    Solar energetic particles (SEPs) emitted from the Sun are a major space weather hazard motivating the development of predictive capabilities. This book presents the results and findings of the HESPERIA (High Energy Solar Particle Events forecasting and Analysis) project of the EU HORIZON 2020 programme. It discusses the forecasting operational tools developed within the project, and presents progress to SEP research contributed by HESPERIA both from the observational as well as the SEP modelling perspective. Using multi-frequency observational data and simulations HESPERIA investigated the chain of processes from particle acceleration in the corona, particle transport in the magnetically complex corona and interplanetary space, to the detection near 1 AU. The book also elaborates on the unique software that has been constructed for inverting observations of relativistic SEPs to physical parameters that can be compared with spac e-borne measurements at lower energies. Introductory and pedagogical material incl...

  16. 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.

  17. Statistical survey of type III radio bursts at long wavelengths observed by the Solar TErrestrial RElations Observatory (STEREO)/Waves instruments: radio flux density variations with frequency

    Czech Academy of Sciences Publication Activity Database

    Krupař, Vratislav; Maksimovic, M.; Santolík, Ondřej; Kontar, E. P.; Cecconi, B.; Hoang, S.; Krupařová, Oksana; Souček, Jan; Reid, H.; Zaslavsky, A.

    2014-01-01

    Roč. 289, č. 8 (2014), s. 3121-3135 ISSN 0038-0938 R&D Projects: GA ČR(CZ) GAP209/12/2394; GA ČR GP13-37174P; GA ČR GAP205/10/2279 Institutional support: RVO:68378289 Keywords : solar radio emissions * plasma radiation Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.039, year: 2014 http://link.springer.com/article/10.1007%2Fs11207-014-0522-x

  18. Statistical survey of type III radio bursts at long wavelengths observed by the Solar TErrestrial RElations Observatory (STEREO)/Waves instruments: goniopolarimetric properties and radio source locations

    Czech Academy of Sciences Publication Activity Database

    Krupař, Vratislav; Maksimovic, M.; Santolík, Ondřej; Cecconi, B.; Krupařová, Oksana

    2014-01-01

    Roč. 289, č. 12 (2014), s. 4633-4652 ISSN 0038-0938 R&D Projects: GA ČR GP13-37174P; GA ČR GAP205/10/2279; GA ČR(CZ) GAP209/12/2394 Institutional support: RVO:68378289 Keywords : plasma radiation * solar radio emissions Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.039, year: 2014 http://link.springer.com/article/10.1007%2Fs11207-014-0601-z

  19. 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.

  20. Solar Particle Radiation Storms Forecasting and Analysis within the Framework of the `HESPERIA' HORIZON 2020 Project

    Science.gov (United States)

    Posner, A.; Malandraki, O.; Nunez, M.; Heber, B.; Labrenz, J.; Kühl, P.; Milas, N.; Tsiropoula, G.; Pavlos, E.

    2017-12-01

    Two prediction tools that have been developed in the framework of HESPERIA based upon the proven concepts UMASEP and REleASE. Near-relativistic (NR) electrons traveling faster than ions (30 MeV protons have 0.25c) are used to forecast the arrival of protons of Solar Energetic Particle (SEP) events with real-time measurements of NR electrons. The faster electrons arrive at L1 30 to 90 minutes before the slower protons. REleASE (Relativistic Electron Alert System for Exploration, Posner, 2007) uses this effect to predict the proton flux by utilizing actual electron fluxes and their most recent increases. Through HESPERIA, a clone of REleASE was built in open source programming language. The same forecasting principle was adapted to real-time data from ACE/EPAM. It is shown that HESPERIA REleASE forecasting works with any NR electron flux measurements. >500 MeV solar protons are so energetic that they usually have effects on the ground, producing Ground Level Enhancement (GLE) events. Within HESPERIA, a predictor of >500 SEP proton events near earth (geostationary orbit) has been developed. In order to predict these events, UMASEP (Núñez, 2011, 2015) has been used. UMASEP makes a lag-correlation of solar electromagnetic (EM) flux with the particle flux near earth. If the correlation is high, the model infers that there is a magnetic connection through which particles are arriving. If, additionally, the intensity of the flux of the associated solar event is also high, then UMASEP issues a SEP prediction. In the case of the prediction of >500 MeV SEP events, the implemented system, called HESPERIA UMASEP-500, correlates X-ray flux with differential proton fluxes by GOES, and with fluxes collected by neutron monitor stations around the world. When the correlation estimation and flare surpasses thresholds, a >500 MeV SEP forecast is issued. These findings suggest that a synthesis of the various approaches may improve over the status quo. Both forecasting tools are

  1. A comparative study of night-time enhancement of TEC at a low latitude station on storm and quiet nights including the local time, seasonal and solar activity dependence

    Directory of Open Access Journals (Sweden)

    K. Unnikrishnan

    Full Text Available The main characteristics of night-time enhancements in TEC during magnetic storms are compared with those during quiet nights for different seasons and solar activity conditions at Palehua, a low latitude station during the period 1980–1989. We find that the mean amplitude has both a seasonal and solar activity dependence: in winter, the values are higher for weak storms as compared to those during quiet nights and increase with an increase in solar activity. In summer, the mean amplitude values during weak storms and quiet nights are almost equal. But during equinox, the mean amplitude values for quiet nights are greater than those during weak storms. The mean half-amplitude duration is higher during weak storms as compared to that during quiet nights in summer. However, during winter and equinox, the durations are almost equal for both quiet and weak storm nights. For the mean half-amplitude duration, the quiet night values for all the seasons and equinoctial weak storm values increase with an increase in solar activity. The occurrence frequency (in percent of TEC enhancement during weak storms is greater than during quiet nights for all seasons. The mean amplitude, the mean half-amplitude duration and the occurrence frequency (in percent of TEC enhancement values are higher during major storms as compared to those during quiet nights. The above parameters have their highest values during pre-midnight hours. From the data analysed, this behaviour is true in the case of major storms also.

    Key words. Ionosphere (ionospheric disturbances; plasma convection Magnetospheric physics (storms and substorms

  2. DISSOLUÇÃO DE FRONTEIRAS E A EXPERIÊNCIA TRANSICIONAL EM SOLAR STORMS, DE LINDA HOGAN

    Directory of Open Access Journals (Sweden)

    Caroline Garcia de Souza

    2014-12-01

    Full Text Available O presente trabalho analisa a experiência transicional no romance Solar Storms, publicado pela escritora nativo-americana Linda Hogan (Chickasaw em 1995. A obra narra a jornada de Angela, uma mestiça indígena órfã que retorna à terra de seus antepassados na tentativa de desvendar sua história e de religar os fragmentos de um passado parcialmente obscuro. Ao longo da narrativa, percebe-se um processo de gradual desconstrução de categorias – temporais, físicas, espaciais – e de superação das relações dicotômicas que opõem, por exemplo, indivíduo e comunidade, interioridade e exterioridade, o mundo humano e o não humano. Esse movimento se dá na direção de uma dissolução das falsas fronteiras e no sentido de uma integração total.

  3. Impulsiveness and energetics in solar flares with and without type II radio bursts - A comparison of hard X-ray characteristics for over 2500 solar flares

    Science.gov (United States)

    Pearson, Douglas H.; Nelson, Robert; Kojoian, Gabriel; Seal, James

    1989-01-01

    The hard X-ray characteristics of more than 2500 solar flares are used to study the relative size, impulsiveness, and energetics of flares with and without type II radio bursts. A quantitative definition of the hard X-ray impulsiveness is introduced, which may be applied to a large number of events unambiguously. It is found that the flares with type II bursts are generally not significantly larger, more impulsive, or more energetic than those without type II bursts. Also, no evidence is found to suggest a simple classification of the flares as either 'impulsive' or 'gradual'. Because type II bursts are present even in small flares with relatively unimpulsive energy releases, it is concluded that changes in the ambient conditions of the solar atmosphere causing an unusually low Alfven speed may be important in the generation of the shock wave that produces type II radio bursts.

  4. On the Reflection in the Solar Radio Emission of Processes in the Chromosphere and the lower Corona preceded CMEs Registration

    Science.gov (United States)

    Durasova, M. S.; Tikhomirov, Yu. V.; Fridman, V. M.; Sheiner, O. A.

    The phenomena preceding the Coronal Mass Ejections (CMEs) and observed in the radio-frequency band represent a lot of sporadic components of the emission, that cover the wide frequency range. The study of these phenomena composes the new, prevailing for the last ten years direction. This is caused by the fact that solar radioastronomy possesses the developed network of observant tools, by the sensitive methods of observations. It makes possible in a number of cases to obtain information from the layers of solar atmosphere, inaccessible for the studies by other methods of observations. The purpose of this work is analysis of information about the CMEs preceding radio-events and their dynamics in the centimeter and decimeter radio emission in 1998. We use the data of the worldwide network of solar observatories in the radio-frequency band, the data about the CMEs phenomena and the characteristics are taken from Internet: http://sdaw.gsfc.nasa.gov./CME_list}. From great number of the CMEs we select only such, before which there were no more recorded events in the time interval of 8 hours, and before which sporadic radio emission was observed on 2-hours interval. The selection of this interval was caused by available study about the mean lifetime of precursors before CMEs and powerful flares, as a rule, accompanying CMEs, in the optical, X-ray and radio emissions. It constitutes, on the average, about 30 min. The total volume of data composed 68 analyzed events of CMEs in 1998. The analysis of the spectral- temporary characteristics of sporadic radio emission in the dependence on the CMEs parameters is carried out. The nature of processes at the stage of formation and initial propagation of CMEs, such as floating up of new magnetic fluxes, the development of instabilities, the characteristic scales of phenomena, that have an effect upon the observed radio emission is analyzed. The work is carried out with the support of Russian Fund of Basic Research (grant 03

  5. A dynamo theory prediction for solar cycle 22: Sunspot number, radio flux, exospheric temperature, and total density at 400 km

    Science.gov (United States)

    Schatten, K. H.; Hedin, A. E.

    1986-01-01

    Using the dynamo theory method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

  6. A dynamo theory prediction for solar cycle 22 - Sunspot number, radio flux, exospheric temperature, and total density at 400 km

    Science.gov (United States)

    Schatten, K. H.; Hedin, A. E.

    1984-01-01

    Using the 'dynamo theory' method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

  7. Fibre structure of decametric type II radio bursts as a manifestation of emission propagation effects in a disturbed near-solar plasma

    OpenAIRE

    A. N. Afanasiev

    2009-01-01

    This paper addresses the fine structure of solar decametric type II radio bursts in the form of drifting narrowband fibres on the dynamic spectrum. Observations show that this structure appears in those events where there is a coronal mass ejection (CME) traveling in the near-solar space ahead of the shock wave responsible for the radio burst. The diversity in observed morphology of fibres and values of their parameters implies that the fibres may be caused by different formation mechanisms. ...

  8. Solar-terrestrial disturbances in June-September 1982, 5

    International Nuclear Information System (INIS)

    Ondoh, Tadanori

    1985-01-01

    The x-ray detector on the SMS-GOES satellite observed 77 solar x-ray flares (1 - 8A) with flux above 10 -5 W/m 2 in June, 1982, and 33 SIDs with importance above 2 were observed in Hiraiso, Japan. However, the geomagnetic storm with Dst above 100 nT did not occur at that time since most solar flares occurred near the east rim of the sun. These solar active regions lasted for 5 solar rotations, then, the great geomagnetic storms with Dst above 100 nT occurred on July 13 - 15, September 5 - 7 and September 21 - 23, 1982. These geomagnetic storms were preceded by the solar flares of importance above 2B occurred in the central part of the solar disc. From September 26 to 27, 1982, a great geomagnetic storm which was not accompanied by solar flare occurred. This paper summarized the studies on solar-terrestrial events from June to September, 1982, made by the space physics and aeronomy groups of the Radio Research Laboratories, Japan. The solar flares occurred on July 12, September 4 and 19, 1982, the geomagnetic storms corresponding to them, the cosmic ray storms observed on July 13 - 19, September 6 - 9 and 21 - 26, 1982, global equivalent current system and others are reported. (Kako, I.)

  9. [Electrical storm].

    Science.gov (United States)

    Barnay, C; Taieb, J; Morice, R

    2007-11-01

    Electrical storm is defined as repeated occurrence of severe ventricular arrhythmias requiring multiple cardioversions, two or more or three or more following different studies. The clinical aspect can sometimes be made of multiple, self aggravating, life threatening accesses. There are three main clinical circumstances of occurrence: in patients equipped with intracardiac defibrillators, during the acute phase of myocardial infarction and in Brugada syndrome. 10 to 15% of patients with cardiac defibrillators are subject to electrical storms in a period of two years. The causative arrhythmia is most often ventricular tachycardia than ventricular fibrillation, especially in secondary prevention and if the initial arrhythmias justifying the device was a ventricular tachycardia. Precipitaing factors are present in one third of cases, mainly acute heart failure, ionic disorders and arrhythmogenic drugs. Predictive factors are age, left ventricular ejection fractionelectrical shock in 50% of cases, antitachycardi stimulation in 30% and in 20% by association of the two. Treatment, after elimination of inappropriate shocks, is mainly based on beta-blockers and amiodarone, class I antiarrhythmics, lidocaïne or bretylium in some cases, and sedation pushed to general anesthesia in some cases. Radio-frequency ablation and even heart transplantation have been proposed in extreme cases. Quinidine has been proved efficient in cases of Brugada syndrome.

  10. Noise storm coordinated observations

    International Nuclear Information System (INIS)

    Elgaroey, Oe.; Tlamicha, A.

    1983-01-01

    The usually accepted bipolar model of noise storm centers is irrelevant for the present observations. An alternative model has been proposed in which the different sources of a noise storm center are located in different flux tubes connecting active regions with their surroundings. Radio emission is observed from the wide, descending branch of the flux tubes, opposite to the flaring site. The relation between the sense of circular polarization of the radio emission and the magnetic polarity, has been more precisely defined. The radiation is in the ordinary mode with respect to the underlying large scale photospheric magnetic polarity. Thus the ''irregular'' polarity of noice storm center ''B'' is explained. As regards center ''C'', one should note that although the observed radio emission is polarized in the ordinary mode with respect to the leading spot of region HR 17653, center ''C'' is not situated in flux tubes originating from the leading part of this region according to the proposed model. Rather, the radio sources are located in the wide and descending part of flux tubes connecting a large, quiet area of south magnetic polarity with the following part of the region HR 17653 (of north magnetic polarity). Thus it is the polarity of the extended area which determines the polarization of the radio emission. The observed polarization should result rather from the emission process than from complicated conditions of propagation for the radio waves

  11. RadWorks Storm Shelter Design for Solar Particle Event Shielding

    Science.gov (United States)

    Simon, Matthew A.; Cerro, Jeffrey; Clowdsley, Martha

    2013-01-01

    In order to enable long-duration human exploration beyond low-Earth orbit, the risks associated with exposure of astronaut crews to space radiation must be mitigated with practical and affordable solutions. The space radiation environment beyond the magnetosphere is primarily a combination of two types of radiation: galactic cosmic rays (GCR) and solar particle events (SPE). While mitigating GCR exposure remains an open issue, reducing astronaut exposure to SPEs is achievable through material shielding because they are made up primarily of medium-energy protons. In order to ensure astronaut safety for long durations beyond low-Earth orbit, SPE radiation exposure must be mitigated. However, the increasingly demanding spacecraft propulsive performance for these ambitious missions requires minimal mass and volume radiation shielding solutions which leverage available multi-functional habitat structures and logistics as much as possible. This paper describes the efforts of NASA's RadWorks Advanced Exploration Systems (AES) Project to design minimal mass SPE radiation shelter concepts leveraging available resources. Discussion items include a description of the shelter trade space, the prioritization process used to identify the four primary shelter concepts chosen for maturation, a summary of each concept's design features, a description of the radiation analysis process, and an assessment of the parasitic mass of each concept.

  12. Great magnetic storms

    International Nuclear Information System (INIS)

    Tsurutani, B.T.; Yen Te Lee; Tang, F.; Gonzalez, W.D.

    1992-01-01

    The five largest magnetic storms that occurred between 1971 and 1986 are studied to determine their solar and interplanetary causes. All of the events are found to be associated with high speed solar wind streams led by collisionless shocks. The high speed streams are clearly related to identifiable solar flares. It is found that (1) it is the extreme values of the southward interplanetary magnetic fields rather than solar wind speeds that are the primary causes of great magnetic storms, (2) shocked and draped sheath fields preceding the driver gas (magnetic cloud) are at least as effective in causing the onset of great magnetic storms (3 of 5 events ) as the strong fields within the driver gas itself, and (3) precursor southward fields ahead of the high speed streams allow the shock compression mechanism (item 2) to be particularly geoeffective

  13. Evidence for four- and three-wave interactions in solar type III radio emissions

    Directory of Open Access Journals (Sweden)

    G. Thejappa

    2013-08-01

    Full Text Available The high time resolution observations obtained by the STEREO/WAVES experiment show that in the source regions of solar type III radio bursts, Langmuir waves often occur as intense localized wave packets with short durations of only few ms. One of these wave packets shows that it is a three-dimensional field structure with WLneTe ~ 10−3, where WL is the peak energy density, and ne and Te are the electron density and temperature, respectively. For this wave packet, the conditions of the oscillating two-stream instability (OTSI and supersonic collapse are satisfied within the error range of determination of main parameters. The density cavity, observed during this wave packet indicates that its depth, width and temporal coincidence are consistent with those of a caviton, generated by the ponderomotive force of the collapsing wave packet. The spectrum of each of the parallel and perpendicular components of the wave packet contains a primary peak at fpe, two secondary peaks at fpe ± fS and a low-frequency enhancement below fS, which, as indicated by the frequency and wave number resonance conditions, and the fast Fourier transform (FFT-based tricoherence spectral peak at (fpe, fpe, fpe + fS, fpe − fS, are coupled to each other by the OTSI type of four-wave interaction (fpe is the local electron plasma frequency and fS is the frequency of ion sound waves. In addition to the primary peak at fpe, each of these spectra also contains a peak at 2fpe, which as indicated by the frequency and wave number resonance conditions, and the wavelet-based bicoherence spectral peak at (fpe, fpe, appears to correspond to the second harmonic electromagnetic waves generated as a result of coalescence of oppositely propagating sidebands excited by the OTSI. Thus, these observations for the first time provide combined evidence that (1 the OTSI and related strong turbulence processes play a significant role in the stabilization of the electron beam, (2 the coalescence

  14. Summary of daily observational results of solar phenomena, cosmic ray, geomagnetic variation, ionosphere, radio wave propagation and airglow

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    The diagrams in this section of the publication illustrate the summary of daily observational results of solar phenomena, cosmic ray, geomagnetic variation, ionosphere, radio wave propagation and airglow observed in Japan. For convenience, the observational results are arranged by the solar rotation number. The aim of this illustration is to disseminate an outline of daily events observed in Japan for the benefit of active research workers who plan to make detailed study of the specific solar and terrestrial events. Therefore, the illustrations do not show all observational results in Japan but only representative ones at some key stations in Japan. They will suffice for the present purpose. The method of illustration shown in the instruction on the next page is still a preliminary one, and it is subject to change resulting from the kind advice of the users of this part of the publication. We welcome any advice for making the data arrangement and expression better and more convenient. (auth.)

  15. Information Content in Radio Waves: Student Investigations in Radio Science

    Science.gov (United States)

    Jacobs, K.; Scaduto, T.

    2013-12-01

    We describe an inquiry-based instructional unit on information content in radio waves, created in the summer of 2013 as part of a MIT Haystack Observatory (Westford, MA) NSF Research Experiences for Teachers (RET) program. This topic is current and highly relevant, addressing science and technical aspects from radio astronomy, geodesy, and atmospheric research areas as well as Next Generation Science Standards (NGSS). Projects and activities range from simple classroom demonstrations and group investigations, to long term research projects incorporating data acquisition from both student-built instrumentation as well as online databases. Each of the core lessons is applied to one of the primary research centers at Haystack through an inquiry project that builds on previously developed units through the MIT Haystack RET program. In radio astronomy, students investigate the application of a simple and inexpensive software defined radio chip (RTL-SDR) for use in systems implementing a small and very small radio telescope (SRT and VSRT). Both of these systems allow students to explore fundamental principles of radio waves and interferometry as applied to radio astronomy. In ionospheric research, students track solar storms from the initial coronal mass ejection (using Solar Dynamics Observatory images) to the resulting variability in total electron density concentrations using data from the community standard Madrigal distributed database system maintained by MIT Haystack. Finally, students get to explore very long-baseline interferometry as it is used in geodetic studies by measuring crustal plate displacements over time. Alignment to NextGen standards is provided for each lesson and activity with emphasis on HS-PS4 'Waves and Their Applications in Technologies for Information Transfer'.

  16. Interplanetary ions during an energetic storm particle event: The distribution function from solar wind thermal energies to 1.6 MeV

    International Nuclear Information System (INIS)

    Gosling, J.T.; Asbridge, J.R.; Bame, S.J.; Feldman, W.C.; Zwickl, R.D.; Paschmann, G.; Sckopke, N.; Hynds, R.J.

    1981-01-01

    Data from the Los Alamos Scientific Laboratory/Max-Planck-Institut fast plasma experiment on Isee 2 have been combined with data from the European Space Agency/Imperial College/Space Research Laboratory low-energy proton experiment on Isee 3 to obtain for the first time an ion velocity distribution function f(v) extending from solar wind energies (-1 keV) to 1.6 MeV during the postshock phase of an energetic storm particle (ESP) event. This study reveals that f(v) of the ESP population is roughly isotropic in the solar wind frame from solar wind thermal energies out to 1.6 MeV. Emerging smoothly out of the solar wind thermal distribution, the ESP f(v) initially falls with increasing energy as E/sup -2.4/ in the solar wind frame. Above about 40 keV no single power law exponent adequately describes the energy dependence of f(v) in the solar wind frame. Above approx.200 keV in both the spacecraft frame and the solar wind frame, f(v) can be described by an exponential in speed (f(v)proportionale/sup -v/v//sub o/) with v/sub o/ = 1.05 x 10 8 cm s -1 . The ESP event studied (August 27, 1978) was superposed upon a more energetic particle event which was predominantly field-aligned and which was probably of solar origin. Our observations suggest that the ESP population is accelerated directly out of the solar wind thermal population or its quiescent suprathermal tail by a stochastic process associated with the shock wave disturbance. The acceleration mechanism is sufficiently efficient that approx.1% of the solar wind population is accelerated to suprathermal energies. These suprathermal particles have an energy density of approx.290 eV cm -3

  17. Geospatial Analysis of Low-frequency Radio Signals Collected During the 2017 Solar Eclipse

    Science.gov (United States)

    Liles, W. C.; Nelson, J.; Kerby, K. C.; Lukes, L.; Henry, J.; Oputa, J.; Lemaster, G.

    2017-12-01

    The total solar eclipse of 2017, with a path that crosses the continental United States, offers a unique opportunity to gather geospatially diverse data. The EclipseMob project has been designed to crowdsource this data by building a network of citizen scientists across the country. The project focuses on gathering low-frequency radio wave data before, during, and after the eclipse. WWVB, a 60 KHz transmitter in Ft. Collins, CO operated by the National Institutes of Standard and Technology, will provide the transmit signal that will be observed by project participants. Participating citizen scientists are building simple antennas and receivers designed by the EclipseMob team and provided to participants in the form of "receiver kits." The EclipseMob receiver downsamples the 60 KHz signal to 18 KHz and supplies the downsampled signal to the audio jack of a smartphone. A dedicated app is used to collect data and upload it to the EclipseMob server. By studying the variations in WWVB amplitude observed during the eclipse at over 150 locations across the country, we aim to understand how the ionization of the D layer of the ionosphere is impacted by the eclipse as a function of both time and space (location). The diverse locations of the EclipseMob participants will provide data from a wide variety of propagation paths - some crossing the path of the total eclipse, and some remaining on the same side of the eclipse path as the transmitter. Our initial data analysis will involve identifying characteristics that define geospatial relationships in the behavior of observed WWVB signal amplitudes.

  18. Coronal mass ejection kinematics deduced from white light (Solar Mass Ejection Imager) and radio (Wind/WAVES) observations

    Science.gov (United States)

    Reiner, M. J.; Jackson, B. V.; Webb, D. F.; Mizuno, D. R.; Kaiser, M. L.; Bougeret, J.-L.

    2005-09-01

    White-light and radio observations are combined to deduce the coronal and interplanetary kinematics of a fast coronal mass ejection (CME) that was ejected from the Sun at about 1700 UT on 2 November 2003. The CME, which was associated with an X8.3 solar flare from W56°, was observed by the Mauna Loa and Solar and Heliospheric Observatory (SOHO) Large-Angle Spectrometric Coronograph (LASCO) coronagraphs to 14 R⊙. The measured plane-of-sky speed of the LASCO CME was 2600 km s-1. To deduce the kinematics of this CME, we use the plane-of-sky white light observations from both the Solar Mass Ejection Imager (SMEI) all-sky camera on board the Coriolis spacecraft and the SOHO/LASCO coronagraph, as well as the frequency drift rate of the low-frequency radio data and the results of the radio direction-finding analysis from the WAVES experiment on the Wind spacecraft. In agreement with the in situ observations for this event, we find that both the white light and radio observations indicate that the CME must have decelerated significantly beginning near the Sun and continuing well into the interplanetary medium. More specifically, by requiring self-consistency of all the available remote and in situ data, together with a simple, but not unreasonable, assumption about the general characteristic of the CME deceleration, we were able to deduce the radial speed and distance time profiles for this CME as it propagated from the Sun to 1 AU. The technique presented here, which is applicable to mutual SMEI/WAVES CME events, is expected to provide a more complete description and better quantitative understanding of how CMEs propagate through interplanetary space, as well as how the radio emissions, generated by propagating CME/shocks, relate to the shock and CME. This understanding can potentially lead to more accurate predictions for the onset times of space weather events, such as those that were observed during this unique period of intense solar activity.

  19. Non-uniform temperature field measurement and simulation of a radio telescope’s main reflector under solar radiation

    International Nuclear Information System (INIS)

    Chen, Deshen; Qian, Hongliang; Wang, Huajie; Zhang, Gang; Fan, Feng; Shen, Shizhao

    2017-01-01

    Highlights: • Solar non-uniform temperature field test of a telescope’s reflector is conducted initially. • Time-varying distribution regularities are analyzed contrastively. • Simulation methods are proposed involving environmental factors and self-shadowing. • Refined discrimination method for the shadow distribution is put forward. • Validity of simulation methods is evaluated with the experimental data. - Abstract: To improve the ability of deep-space exploration, many astronomers around the world are actively engaged in the construction of large-aperture and high-precision radio telescopes. The temperature effect is one of three main factors affecting the reflector accuracy of radio telescopes. To study the daily non-uniform temperature field of the main reflector, experimental studies are first carried out with a 3-m-aperture radio telescope model. According to the test results for 16 working conditions, the distribution rule and time-varying regularity of the daily temperature field are summarized initially. Next, theoretical methods for the temperature field of the main reflector are studied considering multiple environmental parameters and self-shadows. Finally, the validity of the theoretical methods is evaluated with test results. The experimental study demonstrates that the non-uniform temperature distribution of the main reflector truly exists and should not be overlooked, and that the theoretical methods for the reflector temperature field proposed in this paper are effective. The research methods and conclusions can provide valuable references for thermal design, monitoring and control of similar high-precision radio telescopes.

  20. Observation of quasi-periodic solar radio bursts associated with propagating fast-mode waves

    Science.gov (United States)

    Goddard, C. R.; Nisticò, G.; Nakariakov, V. M.; Zimovets, I. V.; White, S. M.

    2016-10-01

    Aims: Radio emission observations from the Learmonth and Bruny Island radio spectrographs are analysed to determine the nature of a train of discrete, periodic radio "sparks" (finite-bandwidth, short-duration isolated radio features) which precede a type II burst. We analyse extreme ultraviolet (EUV) imaging from SDO/AIA at multiple wavelengths and identify a series of quasi-periodic rapidly-propagating enhancements, which we interpret as a fast wave train, and link these to the detected radio features. Methods: The speeds and positions of the periodic rapidly propagating fast waves and the coronal mass ejection (CME) were recorded using running-difference images and time-distance analysis. From the frequency of the radio sparks the local electron density at the emission location was estimated for each. Using an empirical model for the scaling of density in the corona, the calculated electron density was used to obtain the height above the surface at which the emission occurs, and the propagation velocity of the emission location. Results: The period of the radio sparks, δtr = 1.78 ± 0.04 min, matches the period of the fast wave train observed at 171 Å, δtEUV = 1.7 ± 0.2 min. The inferred speed of the emission location of the radio sparks, 630 km s-1, is comparable to the measured speed of the CME leading edge, 500 km s-1, and the speeds derived from the drifting of the type II lanes. The calculated height of the radio emission (obtained from the density) matches the observed location of the CME leading edge. From the above evidence we propose that the radio sparks are caused by the quasi-periodic fast waves, and the emission is generated as they catch up and interact with the leading edge of the CME. The movie associated to Fig. 2 is available at http://www.aanda.org

  1. Ion Acoustic Wave Frequencies and Onset Times During Type 3 Solar Radio Bursts

    Science.gov (United States)

    Cairns, Iver H.; Robinson, P. A.

    1995-01-01

    Conflicting interpretations exist for the low-frequency ion acoustic (S) waves often observed by ISEE 3 in association with intense Langmuir (L) waves in the source regions of type III solar radio bursts near 1 AU. Two indirect lines of observational evidence, as well as plasma theory, suggest they are produced by the electrostatic (ES) decay L yields L(PRIME) + S. However, contrary to theoretical predictions, an existing analysis of the wave frequencies instead favors the electromagnetic (EM) decays L yields T + S, where T denotes an EM wave near the plasma frequency. This conflict is addressed here by comparing the observed wave frequencies and onset times with theoretical predictions for the ES and EM decays, calculated using the time-variable electron beam and magnetic field orientation data, rather than the nominal values used previously. Field orientation effects and beam speed variations are shown analytically to produce factor-of-three effects, greater than the difference in wave frequencies predicted for the ES and EM decays; effects of similar magnitude occur in the events analyzed here. The S-wave signals are extracted by hand from a sawtooth noise background, greatly improving the association between S waves and intense L waves. Very good agreement exists between the time-varying predictions for the ES decay and the frequencies of most (but not all) wave bursts. The waves occur only after the ES decay becomes kinematically allowed, which is consistent with the ES decay proceeding and producing most of the observed signals. Good agreement exists between the EM decay's predictions and a significant fraction of the S-wave observations while the EM decay is kinematically allowed. The wave data are not consistent, however, with the EM decay being the dominant nonlinear process. Often the observed waves are sufficiently broadband to overlap simultaneously the frequency ranges predicted for the ES and EM decays. Coupling the dominance of the ES decay with this

  2. A Study of Solar Flare Effects on Mid and High Latitude Radio Wave Propagation using SuperDARN.

    Science.gov (United States)

    Ruohoniemi, J. M.; Chakraborty, S.; Baker, J. B.

    2017-12-01

    Over the Horizon (OTH) communication is strongly dependent on the state of the ionosphere, which is sensitive to solar X-ray flares. The Super Dual Auroral Radar Network (SuperDARN), whose working principle is dependent on trans-ionospheric radio communication, uses HF radio waves to remotely sense the ionosphere. The backscatter returns from the terrestrial surface (also known as ground-scatter) transit the ionosphere four times and simulate the operation of an HF communications link. SuperDARN backscatter signal properties are altered (strongly attenuated and changes apparent phase) during a sudden ionospheric disturbance following a solar flare, commonly known as Short-Wave Fadeout or SWF. During an SWF the number of SuperDARN backscatter echoes drops suddenly (≈1 min) and sharply, often to near zero, and recovers within 30 minutes to an hour. In this study HF propagation data (SuperDARN backscatter) obtained during SWF events are analyzed for the purpose of validating and improving the performance of HF absorption models, such as, Space Weather Prediction Center (SWPC) D-region Absorption model (DRAP) and CCMC physics based AbbyNormal model. We will also present preliminary results from a physics based model for the mid and high latitude ionospheric response to flare-driven space weather anomalies, which can be used to estimate different physical parameters of the ionosphere such as electron density, collision frequency, absorption coefficients, response time of D-region etc.

  3. A HIGH-FREQUENCY TYPE II SOLAR RADIO BURST ASSOCIATED WITH THE 2011 FEBRUARY 13 CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Cho, K.-S.; Kim, R.-S. [Korea Astronomy and Space Science Institute, Whaamdong, Yooseong-ku, Daejeon, 305-348 (Korea, Republic of); Gopalswamy, N.; Kwon, R.-Y.; Yashiro, S., E-mail: kscho@kasi.re.kr [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-03-10

    We examine the relationship between the high-frequency (425 MHz) type II radio burst and the associated white-light coronal mass ejection (CME) that occurred on 2011 February 13. The radio burst had a drift rate of 2.5 MHz s{sup -1}, indicating a relatively high shock speed. From SDO/AIA observations we find that a loop-like erupting front sweeps across high-density coronal loops near the start time of the burst (17:34:17 UT). The deduced distance of shock formation (0.06 Rs) from the flare center and speed of the shock (1100 km s{sup -1}) using the measured density from SDO/AIA observations are comparable to the height (0.05 Rs, from the solar surface) and speed (700 km s{sup -1}) of the CME leading edge observed by STEREO/EUVI. We conclude that the type II burst originates even in the low corona (<59 Mm or 0.08 Rs, above the solar surface) due to the fast CME shock passing through high-density loops.

  4. Fibre structure of decametric type II radio bursts as a manifestation of emission propagation effects in a disturbed near-solar plasma

    Directory of Open Access Journals (Sweden)

    A. N. Afanasiev

    2009-10-01

    Full Text Available This paper addresses the fine structure of solar decametric type II radio bursts in the form of drifting narrowband fibres on the dynamic spectrum. Observations show that this structure appears in those events where there is a coronal mass ejection (CME traveling in the near-solar space ahead of the shock wave responsible for the radio burst. The diversity in observed morphology of fibres and values of their parameters implies that the fibres may be caused by different formation mechanisms. The burst emission propagates through extremely inhomogeneous plasma of the CME, so one possible mechanism can be related to radio propagation effects. I suggest that the fibres in some events represent traces of radio emission caustics, which are formed due to regular refraction of radio waves on the large-scale inhomogeneous structure of the CME front. To support this hypothesis, I have modeled the propagation of radio waves through inhomogeneous plasma of the CME, taking into consideration the presence of electron density fluctuations in it. The calculations, which are based on the Monte Carlo technique, indicate that, in particular, the emission of the fibres should be harmonic. Moreover, the mechanism under consideration suggests that in solar observations from two different points in space, the observed sets of fibres can be shifted in frequency with respect to one another or can have a different structure. This potentially can be used for identifying fibres caused by the propagation effects.

  5. Substorms during different storm phases

    Directory of Open Access Journals (Sweden)

    N. Partamies

    2011-11-01

    Full Text Available After the deep solar minimum at the end of the solar cycle 23, a small magnetic storm occurred on 20–26 January 2010. The Dst (disturbance storm time index reached the minimum of −38 nT on 20 January and the prolonged recovery that followed the main phase that lasted for about 6 days. In this study, we concentrate on three substorms that took place (1 just prior to the storm, (2 during the main phase of the storm, and (3 at the end of the recovery of the storm. We analyse the solar wind conditions from the solar wind monitoring spacecraft, the duration and intensity of the substorm events as well as the behaviour of the electrojet currents from the ground magnetometer measurements. We compare the precipitation characteristics of the three substorms. The results show that the F-region electron density enhancements and dominant green and red auroral emission of the substorm activity during the storm recovery resembles average isolated substorm precipitation. However, the energy dissipated, even at the very end of a prolonged storm recovery, is very large compared to the typical energy content of isolated substorms. In the case studied here, the dissipation of the excess energy is observed over a 3-h long period of several consecutive substorm intensifications. Our findings suggest that the substorm energy dissipation varies between the storm phases.

  6. Study of s-component of the solar radio emission and short-term quantitative prediction of powerful solar flares

    International Nuclear Information System (INIS)

    Guseynov, Sh; Gakhramanov, I.G.

    2012-01-01

    Full text : All living and non-living things on Earth is dependent on the processes occurring in the Sun. Therefore the study of the Sun with the aim to predict powerful solar flares is of great scientific and practical importance. It is known that the main drawback of modern forecasting of solar flares and the low reliability of forecasts is the lack of use of the physical concepts of the mechanism of flares

  7. Learning Storm

    CERN Document Server

    Jain, Ankit

    2014-01-01

    If you are a Java developer who wants to enter into the world of real-time stream processing applications using Apache Storm, then this book is for you. No previous experience in Storm is required as this book starts from the basics. After finishing this book, you will be able to develop not-so-complex Storm applications.

  8. Solar effects on communications

    International Nuclear Information System (INIS)

    Cleveland, F.; Malcolm, W.; Nordell, D.E.; Zirker, J.

    1991-01-01

    When people involved in the power industry think of Solar Magnetic Disturbances (SMD), they normally consider the potential for disrupting power transmission which results form solar-induced disturbances to the earth's magnetic field known as geomagnetic storms. However, in addition to the disruption of power transmission, solar phenomena can interfere with utility communication systems. Utilities use many different types of communication media, some of which can be affected by various solar phenomena. These include wire-based facilities (metallic cables and power line carrier), radio systems (HF, VHF, UHF mobile radio, microwave networks, and satellite transmissions), and fiber optic systems. This paper reports that the solar flares and other solar phenomena can affect these media through different mechanisms: Radio communications can be disturbed by flare-induced changes in the ionispheric layer of the atmosphere; Cable communications can be disrupted by the flare-induced changes in the magnetosphere which surrounds the earth. These changes, in turn, induce currents in the power equipment that energizes long communications cables; Satellite communications can be disrupted by the flare-induced perturbations of satellite orbits and equipment

  9. Geomagnetic storm effects on GPS based navigation

    Directory of Open Access Journals (Sweden)

    P. V. S. Rama Rao

    2009-05-01

    Full Text Available The energetic events on the sun, solar wind and subsequent effects on the Earth's geomagnetic field and upper atmosphere (ionosphere comprise space weather. Modern navigation systems that use radio-wave signals, reflecting from or propagating through the ionosphere as a means of determining range or distance, are vulnerable to a variety of effects that can degrade the performance of the navigational systems. In particular, the Global Positioning System (GPS that uses a constellation of earth orbiting satellites are affected due to the space weather phenomena.

    Studies made during two successive geomagnetic storms that occurred during the period from 8 to 12 November 2004, have clearly revealed the adverse affects on the GPS range delay as inferred from the Total Electron Content (TEC measurements made from a chain of seven dual frequency GPS receivers installed in the Indian sector. Significant increases in TEC at the Equatorial Ionization anomaly crest region are observed, resulting in increased range delay during the periods of the storm activity. Further, the storm time rapid changes occurring in TEC resulted in a number of phase slips in the GPS signal compared to those on quiet days. These phase slips often result in the loss of lock of the GPS receivers, similar to those that occur during strong(>10 dB L-band scintillation events, adversely affecting the GPS based navigation.

  10. A Solar Stationary Type IV Radio Burst and Its Radiation Mechanism

    Science.gov (United States)

    Liu, Hongyu; Chen, Yao; Cho, Kyungsuk; Feng, Shiwei; Vasanth, Veluchamy; Koval, Artem; Du, Guohui; Wu, Zhao; Li, Chuanyang

    2018-04-01

    A stationary Type IV (IVs) radio burst was observed on September 24, 2011. Observations from the Nançay RadioHeliograph (NRH) show that the brightness temperature (TB) of this burst is extremely high, over 10^{11} K at 150 MHz and over 108 K in general. The degree of circular polarization (q) is between -60% ˜ -100%, which means that it is highly left-handed circularly polarized. The flux-frequency spectrum follows a power-law distribution, and the spectral index is considered to be roughly -3 ˜ -4 throughout the IVs. Radio sources of this event are located in the wake of the coronal mass ejection and are spatially dispersed. They line up to present a formation in which lower-frequency sources are higher. Based on these observations, it is suggested that the IVs was generated through electron cyclotron maser emission.

  11. Solar wind electron densities from Viking dual-frequency radio measurements

    International Nuclear Information System (INIS)

    Muhleman, D.O.; Anderson, J.D.

    1981-01-01

    Simultaneous phase coherent, two-frequency measurements of the time delay between the Earth station and the Viking spacecraft have been analyzed in terms of the electron density profiles from 4 solar radii (R/sub sun/) to 200 R/sub sun/. The measurements were made during a period of solar activity minimum (1976--1977) and show a strong solar latitude effect. The data were analyzed with both a model independent, direct numerical inversion technique and with model fitting, yielding essentially the same results. It is shown that the solar wind density can be represented by two power laws near the solar equator proportional to r/sup -2.7/ and r/sup -2.04/. However, the more rapidly falling term quickly disappears at moderate latitudes (approx.20 0 ), leaving only the inverse-square behavior

  12. First detection of thermal radio emission from solar-type stars with the Karl G. Jansky very large array

    Energy Technology Data Exchange (ETDEWEB)

    Villadsen, Jackie; Hallinan, Gregg; Bourke, Stephen [Department of Astronomy, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125 (United States); Güdel, Manuel [Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna (Austria); Rupen, Michael, E-mail: jrv@astro.caltech.edu [National Radio Astronomy Observatory, Socorro, NM 87801 (United States)

    2014-06-20

    We present the first detections of thermal radio emission from the atmospheres of solar-type stars τ Cet, η Cas A, and 40 Eri A. These stars all resemble the Sun in age and level of magnetic activity, as indicated by X-ray luminosity and chromospheric emission in Ca II H and K lines. We observed these stars with the Karl G. Jansky Very Large Array with sensitivities of a few μJy at combinations of 10.0, 15.0, and 34.5 GHz. τ Cet, η Cas A, and 40 Eri A are all detected at 34.5 GHz with signal-to-noise ratios of 6.5, 5.2, and 4.5, respectively. 15.0 GHz upper limits imply a rising spectral index greater than 1.0 for τ Cet and 1.6 for η Cas A, at the 95% confidence level. The measured 34.5 GHz flux densities correspond to stellar disk-averaged brightness temperatures of roughly 10,000 K, similar to the solar brightness temperature at the same frequency. We explain this emission as optically thick thermal free-free emission from the chromosphere, with possible contributions from coronal gyroresonance emission above active regions and coronal free-free emission. These and similar quality data on other nearby solar-type stars, when combined with Atacama Large Millimeter/Submillimeter Array observations, will enable the construction of temperature profiles of their chromospheres and lower transition regions.

  13. First detection of thermal radio emission from solar-type stars with the Karl G. Jansky very large array

    International Nuclear Information System (INIS)

    Villadsen, Jackie; Hallinan, Gregg; Bourke, Stephen; Güdel, Manuel; Rupen, Michael

    2014-01-01

    We present the first detections of thermal radio emission from the atmospheres of solar-type stars τ Cet, η Cas A, and 40 Eri A. These stars all resemble the Sun in age and level of magnetic activity, as indicated by X-ray luminosity and chromospheric emission in Ca II H and K lines. We observed these stars with the Karl G. Jansky Very Large Array with sensitivities of a few μJy at combinations of 10.0, 15.0, and 34.5 GHz. τ Cet, η Cas A, and 40 Eri A are all detected at 34.5 GHz with signal-to-noise ratios of 6.5, 5.2, and 4.5, respectively. 15.0 GHz upper limits imply a rising spectral index greater than 1.0 for τ Cet and 1.6 for η Cas A, at the 95% confidence level. The measured 34.5 GHz flux densities correspond to stellar disk-averaged brightness temperatures of roughly 10,000 K, similar to the solar brightness temperature at the same frequency. We explain this emission as optically thick thermal free-free emission from the chromosphere, with possible contributions from coronal gyroresonance emission above active regions and coronal free-free emission. These and similar quality data on other nearby solar-type stars, when combined with Atacama Large Millimeter/Submillimeter Array observations, will enable the construction of temperature profiles of their chromospheres and lower transition regions.

  14. Solar flares: radio and X-ray signatures of magnetic reconnection processes

    Czech Academy of Sciences Publication Activity Database

    Karlický, Marian

    2014-01-01

    Roč. 14, č. 7 (2014), s. 753-772 ISSN 1674-4527 R&D Projects: GA ČR GAP209/12/0103 Institutional support: RVO:67985815 Keywords : Sun: flares * Sun: radio radiation * Sun: X- rays Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.640, year: 2014

  15. The Relationship Between Solar Radio and Hard X-ray Emission

    Czech Academy of Sciences Publication Activity Database

    White, S.M.; Benz, A. O.; Christe, S.; Fárník, František; Kundu, M.R.; Mann, G.; Ning, Z.; Raulin, J.-P.; Silva-Valio, A.V.R.; Saint-Hilaire, P.; Vilmer, N.; Warmuth, A.

    2011-01-01

    Roč. 159, 1-4 (2011), s. 225-261 ISSN 0038-6308 Institutional support: RVO:67985815 Keywords : Sun * radio radiation * X-rays Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.611, year: 2011

  16. Radio wave scattering observations of the solar corona: First-order measurements of expansion velocity and turbulence spectrum using Viking and Mariner 10 spacecraft

    International Nuclear Information System (INIS)

    Tyler, G.L.; Vesecky, J.F.; Plume, M.A.; Howard, H.T.; Barnes, A.

    1981-01-01

    Solar conjunction of Mars on 1976 November 25 occurred very near the beginning of solar cycle 21, about 4 months after the first Viking spacecraft arrived at the planet. Radio wave scattering data were collected at 3.6 and 13 cm wavelengths, using the radio link between the Viking orbiters and the Earth. These data allow measurements of solar wind properties over a range of heliocentric radial distance from approx.6 to 44 R/sub sun/ with solar latitudes ranging from -17 0 to +7 0 . Observations with Mariner 10 during a period of moderate solar activity in 1974 cover from 6 to 24 R/sub sun/ and from approx.20 0 to near 90 0 . We have found that the temporal frequency variance spectrum of amplitude fluctuations is useful for characterizing the bulk motion of the plasma. This spectrum has an approximately constant low frequency plateau and a power-law high frequency asymptote; the plateau-asymptote intersection frequency provides a measure of the solar wind velocity V. We also obtain the spectral index p of electron density turbulence, Phi/sub N/approx.kappa/sup -p/, where kappa is spatial wavenumber. These results apply to a cylindrical region oriented with its axis along the radio ray path and its center at the point of closest approach to the Sun. The measurements of V and p cover some 78/sup d/ for Viking and 49 2 for Mariner 10 and show the combined effects of changing heliocentric distance rho, solar latitude theta, and solar longitude Psi, as well as solar activity. The Viking results can be regarded as a function primary of rho and Psi since the observations are concentrated in the equatorial regions when solar activity was near minimum. For Mariner 10, rho, theta, and Psi variations were important. The Viking results show an abrupt change in V(rho) and the turbulence spectral index at approx.15 R/sub sun/

  17. Radio Spectral Imaging of Reflective MHD Waves during the Impulsive Phase of a Solar Flare

    Science.gov (United States)

    Yu, S.; Chen, B.; Reeves, K.

    2017-12-01

    We report a new type of coherent radio bursts observed by the Karl G. Jansky Very Large Array (VLA) in 1-2 GHz during the impulsive phase of a two-ribbon flare on 2014 November 1, which we interpret as MHD waves reflected near the footpoint of flaring loops. In the dynamic spectrum, this burst starts with a positive frequency drift toward higher frequencies until it slows down near its highest-frequency boundary. Then it turns over and drifts toward lower frequencies. The frequency drift rate in its descending and ascending branch is between 50-150 MHz/s, which is much slower than type III radio bursts associated with fast electron beams but close to the well-known intermediate drift bursts, or fiber bursts, which are usually attributed to propagating whistler or Alfvenic waves. Thanks to VLA's unique capability of imaging with spectrometer-like temporal and spectral resolution (50 ms and 2 MHz), we are able to obtain an image of the radio source at every time and frequency in the dynamic spectrum where the burst is present and trace its spatial evolution. From the imaging results, we find that the radio source firstly moves downward toward one of the flaring ribbons before it "bounces off" at the lowest height (corresponding to the turnover frequency in the dynamic spectrum) and moves upward again. The measured speed in projection is at the order of 1-2 Mm/s, which is characteristic of Alfvenic or fast-mode MHD waves in the low corona. We conclude that the radio burst is emitted by trapped nonthermal electrons in the flaring loop carried along by a large-scale MHD wave. The waves are probably launched during the eruption of a magnetic flux rope in the flare impulsive phase.

  18. Solar Drift-Pair Bursts

    Science.gov (United States)

    Stanislavsky, A.; Volvach, Ya.; Konovalenko, A.; Koval, A.

    2017-08-01

    In this paper a new sight on the study of solar bursts historically called drift pairs (DPs) is presented. Having a simple morphology on dynamic spectra of radio records (two short components separated in time, and often they are very similar) and discovered at the dawn of radio astronomy, their features remain unexplained totally up to now. Generally, the DPs are observed during the solar storms of type III bursts, but not every storm of type III bursts is linked with DPs. Detected by ground-based instruments at decameter and meter wavelengths, the DP bursts are limited in frequency bandwidth. They can drift from high frequencies to low ones and vice versa. Their frequency drift rate may be both lower and higher than typical rates of type III bursts at the same frequency range. The development of low-frequency radio telescopes and data processing provide additional possibilities in the research. In this context the fresh analysis of DPs, made from recent observations in the summer campaign of 2015, are just considered. Their study was implemented by updated tools of the UTR-2 radio telescope at 9-33 MHz. During 10-12 July of 2015, DPs forming the longest patterns on dynamic spectra are about 7% of the total number of recorded DPs. Their marvelous resemblance in frequency drift rates with the solar S-bursts is discussed.

  19. Some results of model calculations of the solar S-component radio emission

    International Nuclear Information System (INIS)

    Krueger, A.; Hildebrandt, J.

    1985-01-01

    Numerical calculations of special characteristics of the solar S-component microwave radiation are presented on the basis of recent sunspot and plage models. Quantitative results are discussed and can be used for the plasma diagnostics of solar active regions by comparisons with observations with high spatial and spectral resolution. The possibility of generalized applications to magnetic stars and stellar activity is briefly noted. (author)

  20. Extreme Geomagnetic Storms – 1868–2010

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Lefèvre, L.; Dumbović, M.

    2016-01-01

    presents our investigation of the corresponding solar eventsand their characteristics. The storms were selected based on their intensity in the aa index,which constitutes the longest existing continuous series of geomagnetic activity. They areanalyzed statistically in the context of more well...... occurring in May 1921 and the Quebec storm from March 1989. We identifykey characteristics of the storms by combining several different available data sources, listsof storm sudden commencements (SSCs) signifying occurrence of interplanetary shocks,solar wind in-situ measurements, neutron monitor data...... %), Forbushdecreases (100 %), and energetic solar proton events (70 %). A quantitative comparison ofthese associations relative to less intense storms is also presented. Most notably, we findthat most often the extreme storms are characterized by a complexity that is associated with multiple, often interacting, solar...

  1. Development of Power Supply Management Module for Radio Signal Repeaters of Automatic Metering Reading System in Variable Solar Density Conditions

    Science.gov (United States)

    Kondratjevs, K.; Zabasta, A.; Selmanovs-Pless, V.

    2016-02-01

    In recent years, there has been significant research focus that revolves around harvesting and minimising energy consumption by wireless sensor network nodes. When a sensor node is depleted of energy, it becomes unresponsive and disconnected from the network that can significantly influence the performance of the whole network. The purpose of the present research is to create a power supply management module in order to provide stable operating voltage for autonomous operations of radio signal repeaters, sensors or gateways of WSN. The developed management module is composed of a solar panel, lithium battery and power supply management module. The novelty of the research is the management module, which ensures stable and uninterrupted operations of electronic equipment in various power supply modes in different situations, simultaneously ensuring energy protection and sustainability of the module components. The management module is able to provide power supply of 5 V for electronics scheme independently, without power interruption switching between power sources and power flows in different directions.

  2. Some results of observations of solar radio bursts of the ''drift pairs'' type near 25 and 12.5 MHz

    International Nuclear Information System (INIS)

    Abranin, Eh.P.; Bazelyan, L.L.; Goncharov, N.Yu.; Zajtsev, V.V.; Zinichev, V.A.; Levin, B.N.; Rapoport, V.O.; Tsybko, Ya.G.; Gor'kovskij Gosudarstvennyj Univ.

    1977-01-01

    The drift pairs in the frequency range of 12-13 MHz and 24-26 MHz are considered. It is shown that double bursts may be observed both at the second and at the first harmonics. The time interval between the elements of the double burst remains practically unchanged. This fact creates difficulties when interpreting double bursts due to the radio echo in the solar corona. It is suggested that the double (and generally multiple) structure of burst may be associated with the successive transmission of a fast electron beam in regions of double plasma resonance. It is considered that the radiation occurs due to cyclotron instability at the forward front of the electron beam travelling along the decreasing magnetic field of the coronal ray. It is shown that the properties of these burst can be explained by the proposed mechanism of drift pairs formation

  3. RADIO DIAGNOSTICS OF ELECTRON ACCELERATION SITES DURING THE ERUPTION OF A FLUX ROPE IN THE SOLAR CORONA

    Energy Technology Data Exchange (ETDEWEB)

    Carley, Eoin P.; Gallagher, Peter T. [Astrophysics Research Group, School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Vilmer, Nicole, E-mail: eoin.carley@obspm.fr [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, F-92195 Meudon (France)

    2016-12-10

    Electron acceleration in the solar corona is often associated with flares and the eruption of twisted magnetic structures known as flux ropes. However, the locations and mechanisms of such particle acceleration during the flare and eruption are still subject to much investigation. Observing the exact sites of particle acceleration can help confirm how the flare and eruption are initiated and how they evolve. Here we use the Atmospheric Imaging Assembly to analyze a flare and erupting flux rope on 2014 April 18, while observations from the Nançay Radio Astronomy Facility allow us to diagnose the sites of electron acceleration during the eruption. Our analysis shows evidence of a pre-formed flux rope that slowly rises and becomes destabilized at the time of a C-class flare, plasma jet, and the escape of ≳75 keV electrons from the rope center into the corona. As the eruption proceeds, continued acceleration of electrons with energies of ∼5 keV occurs above the flux rope for a period over 5 minutes. At the flare peak, one site of electron acceleration is located close to the flare site, while another is driven by the erupting flux rope into the corona at speeds of up to 400 km s{sup −1}. Energetic electrons then fill the erupting volume, eventually allowing the flux rope legs to be clearly imaged from radio sources at 150–445 MHz. Following the analysis of Joshi et al. (2015), we conclude that the sites of energetic electrons are consistent with flux rope eruption via a tether cutting or flux cancellation scenario inside a magnetic fan-spine structure. In total, our radio observations allow us to better understand the evolution of a flux rope eruption and its associated electron acceleration sites, from eruption initiation to propagation into the corona.

  4. Temperature dependent growth rates of the upper-hybrid waves and solar radio zebra patterns

    Czech Academy of Sciences Publication Activity Database

    Benáček, J.; Karlický, Marian; Yasnov, L. V.

    2017-01-01

    Roč. 598, February (2017), A106/1-A106/6 E-ISSN 1432-0746 R&D Projects: GA ČR GAP209/12/0103 Grant - others:GA MŠk(CZ) LM2015042 Institutional support: RVO:67985815 Keywords : Sun radio radiation * instabilities * methods analytical Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.014, year: 2016

  5. Direct measurements of the 160.01-min oscillation in the solar radio brightness

    International Nuclear Information System (INIS)

    Efanov, V.A.; Moiseev, I.G.; Nesterov, N.S.

    1983-01-01

    Direct (nondifferential) brightness measurements of the quiet sun at lambda = 8.2 and 13.5 mm, corrected by the Bouguer law for absorption in the terrestrial atmosphere, confirm the presence of a 160.009 +- 0.002 min periodicity. At the two wavelengths the relative amplitudes are roughly-equal0.6 x 10 -3 , 1 x 10 -3 . Maximum radio brightness occurs at the phase when optical data indicate the photosphere radius is largest

  6. Frequency variations of solar radio zebras and their power-law spectra

    Czech Academy of Sciences Publication Activity Database

    Karlický, Marian

    2014-01-01

    Roč. 561, January (2014), A34/1-A34/4 ISSN 0004-6361 R&D Projects: GA ČR GAP209/12/0103 Grant - others:EU(XE) PIRSES-GA-2011-295272 Institutional support: RVO:67985815 Keywords : Sun * radio radiation * plasmas Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

  7. Fiber fine structure during solar type IV radio bursts: Observations and theory of radiation in presence of localized whistler turbulence

    International Nuclear Information System (INIS)

    Bernold, T.E.X.; Treumann, R.A.

    1983-01-01

    Observations with a digital spectrometer within the frequency band between 250 and 273 MHz of fiber fine structures during the type IV solar radio burst of 1978 October 1 are presented and analyzed. The results are summarized in histograms. Typical values for drift rates are in the range between -2.3 and -9.9 MHz s -1 . Frequency intervals between absorption and emission within the spectrum were measured to be within 0.9 and 2.7 MHz. Several types of spectra are discussed. A theoretical interpretation is based upon the model of a population of electrons trapped within a magnetic-mirror loop-configuration. It is shown that the fiber emission can be explained assuming an interaction between spatially localized strong whistler turbulence (solitons) and a broad-band Langmuir wave spectrum. Estimates using the observed flux values indicate that a fiber is composed of some 10 11 --10 14 solitons occupying a volume of about 10 5 --10 8 km 3 . Ducting of whistler solitons in low-density magnetic loops provides a plausible explanation for coherent behavior during the lifetime of an individual fiber. The magnetic field strength is found to be 6.2< or =B< or =35 gauss at the radio source and 15.3< or =B< or =76 gauss at the lower hybrid wave level respectively. The quasi-periodicity of the fiber occurrence is interpreted as periodically switched-on soliton production

  8. CONSTRAINING THE SOLAR CORONAL MAGNETIC FIELD STRENGTH USING SPLIT-BAND TYPE II RADIO BURST OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kishore, P.; Ramesh, R.; Hariharan, K.; Kathiravan, C. [Indian Institute of Astrophysics, 2nd Block, Koramangala, Bangalore—560034 (India); Gopalswamy, N., E-mail: kishore@iiap.res.in [Code 671, Solar Physics Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)

    2016-11-20

    We report on low-frequency radio (85–35 MHz) spectral observations of four different type II radio bursts, which exhibited fundamental-harmonic emission and split-band structure. Each of the bursts was found to be closely associated with a whitelight coronal mass ejection (CME) close to the Sun. We estimated the coronal magnetic field strength from the split-band characteristics of the bursts, by assuming a model for the coronal electron density distribution. The choice of the model was constrained, based on the following criteria: (1) when the radio burst is observed simultaneously in the upper and lower bands of the fundamental component, the location of the plasma level corresponding to the frequency of the burst in the lower band should be consistent with the deprojected location of the leading edge (LE) of the associated CME; (2) the drift speed of the type II bursts derived from such a model should agree closely with the deprojected speed of the LE of the corresponding CMEs. With the above conditions, we find that: (1) the estimated field strengths are unique to each type II burst, and (2) the radial variation of the field strength in the different events indicate a pattern. It is steepest for the case where the heliocentric distance range over which the associated burst is observed is closest to the Sun, and vice versa.

  9. Type II solar radio bursts, interplanetary shocks, and energetic particle events

    International Nuclear Information System (INIS)

    Cane, H.V.; Stone, R.G.

    1984-01-01

    Using the ISEE 3 radio astronomy experiment data we have identified 37 interplanetary type II bursts in the period 1978 September to 1981 December. We lists these events and the associated phenomena. The events are preceded by intense, soft X-ray events with long decay times and type II or type IV bursts, or both, at meter wavelengths. The meter wavelength type II bursts are usually intense and exhibit herringbone structure. The extension of the herringbone structure into the kilometer wavelength range appears as a fast drift radio feature which we refer to as a shock associated radio event. The shock associated event is an important diagnostic for the presence of a strong shock and particle acceleration. The majority of the interplanetary type II bursts are associated with energetic particle events. Our results support other studies which indicate that energetic soalr particles detected at 1 A.U. are generatd by shock acceleration. From a preliminary analysis of the available data there appears to be a high correlation with white light coronal transients. The transients are fast: i.e., velocities greater than 500 km s -1

  10. Wave disturbances in the solar corona: radio observations at 24.5-25.5 MHz

    International Nuclear Information System (INIS)

    Kobrin, M.M.; Snegriev, S.D.

    1984-01-01

    We present an analysis of observations of fluctuations in the integrated flux of radio emission from the ''quiet'' sun. The observations were made on the UTR-2 radiotelescope, simultaneously at 11 frequencies in the range 24.5-25.5 MHz. Control observations of Taurus were made in order to allow for the effects of the earth's ionosphere. We measured the phase dependences between oscillations in the radio emission intensity which looked like wave trains. From these measurements we found that for periods of about 10 min we always observed disturbances propagating from the lower levels of the corona to the upper levels. The frequency drift in the trains is observed to be about 10 -3 MHz/sec, corresponding to a disturbance velocity of about 100 km/sec. This may be associated with the propagation of magnetosonic waves. Our estimates show that the observed effects cannot be explained by a bremsstrahlung mechanism: We need to rely on plasma mechanisms in order to explain how the radio emission is generated

  11. 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.

  12. Midlatitude ionospheric changes to four great geomagnetic storms of solar cycle 23 in Southern and Northern Hemispheres

    Czech Academy of Sciences Publication Activity Database

    Matamba, T. M.; Habarulema, J. B.; Burešová, Dalia

    2016-01-01

    Roč. 14, č. 12 (2016), s. 1155-1171 ISSN 1542-7390 R&D Projects: GA ČR(CZ) GAP209/12/2440 Institutional support: RVO:68378289 Keywords : total electron-content * traveling atmospheric disturbances * November 2004 superstorms * magnetic storm s * interplanetary origins * equatorial ionosphere * neutral composition * physical-mechanism * middle latitudes * content response Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.581, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/2016SW001516/abstract

  13. Spacecraft radio scattering observations of the power spectrum of electron density fluctuations in the solar wind

    International Nuclear Information System (INIS)

    Woo, R.; Armstrong, J.W.

    1979-01-01

    Solar wind electron density power spectra in the solar equatorial region are inferred from observations of phase scintillations and spectral broadening made with the Viking, Helios, and Pioneer spacecraft. The heliocentric distance range covered is 2--215 R/sub S/, and for some observations close to the sun the spectra extend to fluctuation frequencies as high as 100 Hz. For heliocentric distances > or approx. =20 R/sub S/ the equivalent spacecraft-measured one-dimensional density spectrym V/sub n/e is well modeled by a single power law (f/sup -alpha/) in the frequency range 10 -4 -5 x 10 -2 Hz. The mean spectral index α is 1.65, very close to the Kolmogorov value of 5/3. Under the assumption of constant solar wind speed, V/sub n/e varies as R/sup -3.45/, where R is heliocentric distance. Within 20 R/sub S/, V/sub n/e can still be modeled by a single power law over the frequency range 10 -3 -10 1 Hz, but the spectral index becomes smaller, αapprox.1.1. The flattening of the density spectrum with 20 R/sub S/ is presumably associated with energy deposition in the near-sun region and acceleration of the solar wind

  14. Direct conversion of light to radio frequency energy. [using photoklystrons for solar power satellites

    Science.gov (United States)

    Freeman, J. W.; Simons, S.

    1981-01-01

    A description is presented of the test results obtained with the latest models of the phototron. The phototron was conceived as a replacement for the high voltage solar cell-high power klystron combination for the solar power satellite concept. Physically, the phototron is a cylindrical evacuated glass tube with a photocathode, two grids, and a reflector electrode in a planar configuration. The phototron can be operated either in a biased mode where a low voltage is used to accelerate the electron beam produced by the photocathode or in an unbiased mode referred to as self-oscillation. The device is easily modulated by light input or voltage to broadcast in AM or FM. The range of operation of the present test model phototrons is from 2 to 200 MHz.

  15. The First Use of Coordinated Ionospheric Radio and Optical Observations Over Italy: Convergence of High-and Low-Latitude Storm-Induced Effects

    Science.gov (United States)

    Cesaroni, C.; Alfonsi, L.; Pezzopane, M.; Martinis, C.; Baumgardner, J.; Wroten, J.; Mendillo, M.; Musicò, E.; Lazzarin, M.; Umbriaco, G.

    2017-11-01

    Ionospheric storm effects at midlatitudes were analyzed using different ground-based instruments distributed in Italy during the 13-15 November 2012 geomagnetic storm. These included an all-sky imager (ASI) in Asiago (45.8°N, 11.5°E), a network of dual-frequeny Global Navigation Satellite Systems receivers (Rete Integrata Nazionale GPS network), and ionosondes in Rome (41.8°N, 12.5°E) and San Vito (40.6°N, 17.8°E). GPS measurements showed an unusual enhancement of total electron content (TEC) in southern Italy, during the nights of 14 and 15 November. The ASI observed colocated enhancements of 630 nm airglow at the same time, as did variations in NmF2 measured by the ionosondes. Moreover, wave-like perturbations were identified propagating from the north. The Ensemble Empirical Mode Decomposition, applied to TEC values revealed the presence of traveling ionospheric disturbances (TIDs) propagating southward between 01:30 UT and 03:00 UT on 15 November. These TIDs were characterized by weak TEC oscillations ( ±0.5 TEC unit), period of 45 min, and velocity of 500 m/s typical of large-scale TIDs. Optical images showed enhanced airglow entering the field of view of the ASI from the N-NE at 02:00 UT and propagating to the S-SW, reaching the region covered by the GPS stations after 03:00 UT, when TEC fluctuations are very small ( ±0.2 TEC unit). The enhancement of TEC and airglow observed in southern Italy could be a consequence of a poleward expansion of the northern crest of the equatorial ionization anomaly. The enhanced airglow propagating from the north and the TEC waves resulted from energy injected at auroral latitudes as confirmed by magnetometer observations in Scandinavia.

  16. Radio astronomy

    CERN Document Server

    Alder, Berni

    1975-01-01

    Methods in Computational Physics, Volume 14: Radio Astronomy is devoted to the role of the digital computer both as a control device and as a calculator in addressing problems related to galactic radio noise. This volume contains four chapters and begins with a technical description of the hardware and the special data-handling problems of using radioheliography, with an emphasis on a selection of observational results obtained with the Culgoora radioheliograph and their significance to solar physics and to astrophysics in general. The subsequent chapter examines interstellar dispersion, i

  17. Peculiarities of frequency dependence of type 3 solar radio bursts duration

    International Nuclear Information System (INIS)

    Tsybko, Ya.G.

    1989-01-01

    From the averaged data of type 3 bursts at the fixed frequencies in the range 12.5-25 MHz and out of this limit it is concluded that there exist two branges of the burst duration dependence on the frequency. This splitting allows to distinguish bursts occurring at the fundamental and the second harmonics of the plasma frequency decreasing with height in the solar corona. The type 3b radiation is characterized by a separate diagram of the mean duration versus frequency of the stria-bursts at the fundamental harmonic

  18. Ionospheric Data Assimilation and Targeted Observation Strategies: Proof of Concept Analysis in a Geomagnetic Storm Event

    Science.gov (United States)

    Kostelich, Eric; Durazo, Juan; Mahalov, Alex

    2017-11-01

    The dynamics of the ionosphere involve complex interactions between the atmosphere, solar wind, cosmic radiation, and Earth's magnetic field. Geomagnetic storms arising from solar activity can perturb these dynamics sufficiently to disrupt radio and satellite communications. Efforts to predict ``space weather,'' including ionospheric dynamics, require the development of a data assimilation system that combines observing systems with appropriate forecast models. This talk will outline a proof-of-concept targeted observation strategy, consisting of the Local Ensemble Transform Kalman Filter, coupled with the Thermosphere Ionosphere Electrodynamics Global Circulation Model, to select optimal locations where additional observations can be made to improve short-term ionospheric forecasts. Initial results using data and forecasts from the geomagnetic storm of 26-27 September 2011 will be described. Work supported by the Air Force Office of Scientific Research (Grant Number FA9550-15-1-0096) and by the National Science Foundation (Grant Number DMS-0940314).

  19. Constraints on Nonlinear and Stochastic Growth Theories for Type 3 Solar Radio Bursts from the Corona to 1 AU

    Science.gov (United States)

    Cairns, Iver H.; Robinson, P. A.

    1998-01-01

    Existing, competing theories for coronal and interplanetary type III solar radio bursts appeal to one or more of modulational instability, electrostatic (ES) decay processes, or stochastic growth physics to preserve the electron beam, limit the levels of Langmuir-like waves driven by the beam, and produce wave spectra capable of coupling nonlinearly to generate the observed radio emission. Theoretical constraints exist on the wavenumbers and relative sizes of the wave bandwidth and nonlinear growth rate for which Langmuir waves are subject to modulational instability and the parametric and random phase versions of ES decay. A constraint also exists on whether stochastic growth theory (SGT) is appropriate. These constraints are evaluated here using the beam, plasma, and wave properties (1) observed in specific interplanetary type III sources, (2) predicted nominally for the corona, and (3) predicted at heliocentric distances greater than a few solar radii by power-law models based on interplanetary observations. It is found that the Langmuir waves driven directly by the beam have wavenumbers that are almost always too large for modulational instability but are appropriate to ES decay. Even for waves scattered to lower wavenumbers (by ES decay, for instance), the wave bandwidths are predicted to be too large and the nonlinear growth rates too small for modulational instability to occur for the specific interplanetary events studied or the great majority of Langmuir wave packets in type III sources at arbitrary heliocentric distances. Possible exceptions are for very rare, unusually intense, narrowband wave packets, predominantly close to the Sun, and for the front portion of very fast beams traveling through unusually dilute, cold solar wind plasmas. Similar arguments demonstrate that the ES decay should proceed almost always as a random phase process rather than a parametric process, with similar exceptions. These results imply that it is extremely rare for

  20. Preparation and properties of radio-frequency-sputtered half-Heusler films for use in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kieven, D., E-mail: david.kieven@helmholtz-berlin.d [Helmholtz-Zentrum fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Grimm, A. [Helmholtz-Zentrum fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Beleanu, A.; Blum, C.G.F. [Johannes Gutenberg Universitaet, Institut fuer Anorganische Chemie und Analytische Chemie, Staudingerweg 9, 55128 Mainz (Germany); Schmidt, J. [Fraunhofer Institut Fertigungstechnik Materialforschung IFAM, Winterbergstrasse 28, 01277 Dresden (Germany); Rissom, T.; Lauermann, I. [Helmholtz-Zentrum fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Gruhn, T.; Felser, C. [Johannes Gutenberg Universitaet, Institut fuer Anorganische Chemie und Analytische Chemie, Staudingerweg 9, 55128 Mainz (Germany); Klenk, R. [Helmholtz-Zentrum fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

    2011-01-03

    The class of half-Heusler compounds opens possibilities to find alternatives for II-VI or III-V compound semiconductors. We aim to find suitable substitutes for the cadmium sulphide buffer layer in chalcopyrite-based thin film solar cells, where the buffer layer is located between the p-type chalcopyrite absorber and an n-type transparent window layer. We report here the preparation of radio-frequency-sputtered lithium copper sulphide 'LiCuS' and lithium zinc phosphide 'LiZnP' films. The optical analysis of these films revealed band gaps between 1.8 and 2.5 eV, respectively. Chemical properties of the film surface and both interfaces between the film and a Cu(In,Ga)Se{sub 2} layer and between the film and an (Zn,Mg)O layer were investigated by in-situ photoelectron spectroscopy. The valence band offsets to the Cu(In,Ga)Se{sub 2} layer were estimated to be (0.4 {+-} 0.1) eV for 'LiCuS'/Cu(In,Ga)Se{sub 2} and (0.5 {+-} 0.8) eV for 'LiZnP'/Cu(In,Ga)Se{sub 2}. This leads to positive conduction band offsets of > 1 eV. These rather large offsets are not compatible with efficient solar cell devices. Under atmospheric conditions 'LiCuS' and 'LiZnP' films show rapid decomposition.

  1. IRI STORM validation over Europe

    Science.gov (United States)

    Haralambous, Haris; Vryonides, Photos; Demetrescu, Crişan; Dobrică, Venera; Maris, Georgeta; Ionescu, Diana

    2014-05-01

    The International Reference Ionosphere (IRI) model includes an empirical Storm-Time Ionospheric Correction Model (STORM) extension to account for storm-time changes of the F layer peak electron density (NmF2) during increased geomagnetic activity. This model extension is driven by past history values of the geomagnetic index ap (The magnetic index applied is the integral of ap over the previous 33 hours with a weighting function deduced from physically based modeling) and it adjusts the quiet-time F layer peak electron density (NmF2) to account for storm-time changes in the ionosphere. In this investigation manually scaled hourly values of NmF2 measured during the main and recovery phases of selected storms for the maximum solar activity period of the current solar cycle are compared with the predicted IRI-2012 NmF2 over European ionospheric stations using the STORM model option. Based on the comparison a subsequent performance evaluation of the STORM option during this period is quantified.

  2. Empirical STORM-E Model. [I. Theoretical and Observational Basis

    Science.gov (United States)

    Mertens, Christopher J.; Xu, Xiaojing; Bilitza, Dieter; Mlynczak, Martin G.; Russell, James M., III

    2013-01-01

    Auroral nighttime infrared emission observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite is used to develop an empirical model of geomagnetic storm enhancements to E-region peak electron densities. The empirical model is called STORM-E and will be incorporated into the 2012 release of the International Reference Ionosphere (IRI). The proxy for characterizing the E-region response to geomagnetic forcing is NO+(v) volume emission rates (VER) derived from the TIMED/SABER 4.3 lm channel limb radiance measurements. The storm-time response of the NO+(v) 4.3 lm VER is sensitive to auroral particle precipitation. A statistical database of storm-time to climatological quiet-time ratios of SABER-observed NO+(v) 4.3 lm VER are fit to widely available geomagnetic indices using the theoretical framework of linear impulse-response theory. The STORM-E model provides a dynamic storm-time correction factor to adjust a known quiescent E-region electron density peak concentration for geomagnetic enhancements due to auroral particle precipitation. Part II of this series describes the explicit development of the empirical storm-time correction factor for E-region peak electron densities, and shows comparisons of E-region electron densities between STORM-E predictions and incoherent scatter radar measurements. In this paper, Part I of the series, the efficacy of using SABER-derived NO+(v) VER as a proxy for the E-region response to solar-geomagnetic disturbances is presented. Furthermore, a detailed description of the algorithms and methodologies used to derive NO+(v) VER from SABER 4.3 lm limb emission measurements is given. Finally, an assessment of key uncertainties in retrieving NO+(v) VER is presented

  3. Development of Power Supply Management Module for Radio Signal Repeaters of Automatic Metering Reading System in Variable Solar Density Conditions

    Directory of Open Access Journals (Sweden)

    Kondratjevs K.

    2016-02-01

    Full Text Available In recent years, there has been significant research focus that revolves around harvesting and minimising energy consumption by wireless sensor network nodes. When a sensor node is depleted of energy, it becomes unresponsive and disconnected from the network that can significantly influence the performance of the whole network. The purpose of the present research is to create a power supply management module in order to provide stable operating voltage for autonomous operations of radio signal repeaters, sensors or gateways of WSN. The developed management module is composed of a solar panel, lithium battery and power supply management module. The novelty of the research is the management module, which ensures stable and uninterrupted operations of electronic equipment in various power supply modes in different situations, simultaneously ensuring energy protection and sustainability of the module components. The management module is able to provide power supply of 5 V for electronics scheme independently, without power interruption switching between power sources and power flows in different directions.

  4. The structure of the big magnetic storms

    International Nuclear Information System (INIS)

    Mihajlivich, J. Spomenko; Chop, Rudi; Palangio, Paolo

    2010-01-01

    The records of geomagnetic activity during Solar Cycles 22 and 23 (which occurred from 1986 to 2006) indicate several extremely intensive A-class geomagnetic storms. These were storms classified in the category of the Big Magnetic Storms. In a year of maximum solar activity during Solar Cycle 23, or more precisely, during a phase designated as a post-maximum phase in solar activity (PPM - Phase Post maximum), near the autumn equinox, on 29, October 2003, an extremely strong and intensive magnetic storm was recorded. In the first half of November 2004 (7, November 2004) an intensive magnetic storm was recorded (the Class Big Magnetic Storm). The level of geomagnetic field variations which were recorded for the selected Big Magnetic Storms, was ΔD st=350 nT. For the Big Magnetic Storms the indicated three-hour interval indices geomagnetic activity was Kp = 9. This study presents the spectral composition of the Di - variations which were recorded during magnetic storms in October 2003 and November 2004. (Author)

  5. Radio and X-ray observations of a multiple impulsive solar burst with high time resolution

    International Nuclear Information System (INIS)

    Kosugi, T.

    1981-01-01

    A well-developed multiple impulsive microwave burst occurred on February 17, 1979 simultaneously with a hard X-ray burst and a large group of type III bursts at metric wavelengths. The whole event is composed of serveral subgroups of elementary spike bursts. Detailed comparisons between these three classes of emissions with high time resolution of approx. equal to0.5 s reveal that individual type III bursts coincide in time with corresponding elementary X-ray and microwave spike bursts. It suggests that a non-thermal electron pulse generating a type III spike burst is produced simultaneously with those responsible for the corresponding hard X-ray and microwave spike bursts. The rise and decay characteristic time scales of the elementary spike burst are << 1 s, and approx. equal to1 s and approx. equal to3 s for type III, hard X-ray and microwave emissions respectively. Radio interferometric observations made at 17 GHz reveal that the spatial structure varies from one subgroup to others while it remains unchanged in a subgroup. Spectral evolution of the microwave burst seems to be closely related to the spatial evolution. The spatial evolution together with the spectral evolution suggests that the electron-accelerating region shifts to a different location after it stays at one location for several tens of seconds, duration of a subgroup of elementary spike bursts. We discuss several requirements for a model of the impulsive burst which come out from these observational results, and propose a migrating double-source model. (orig.)

  6. Predicting the occurrence of super-storms

    Directory of Open Access Journals (Sweden)

    N. Srivastava

    2005-11-01

    Full Text Available A comparative study of five super-storms (Dst<-300 nT of the current solar cycle after the launch of SoHO, to identify solar and interplanetary variables that influence the magnitude of resulting geomagnetic storms, is described. Amongst solar variables, the initial speed of a CME is considered the most reliable predictor of the strength of the associated geomagnetic storm because fast mass ejections are responsible for building up the ram pressure at the Earth's magnetosphere. However, although most of the super-storms studied were associated with high speed CMEs, the Dst index of the resulting geomagnetic storms varied between -300 to -472 nT. The most intense storm of 20 November 2003, (Dst ~ -472 nT had its source in a comparatively smaller active region and was associated with a relatively weaker, M-class flare while all other super-storms had their origins in large active regions and were associated with strong X-class flares. However, this superstorm did not show any associated extraordinary solar and interplanetary characteristics. The study also reveals the challenge in the reliable prediction of the magnitude of a geomagnetic storm from solar and interplanetary variables.

  7. Predicting the occurrence of super-storms

    Directory of Open Access Journals (Sweden)

    N. Srivastava

    2005-11-01

    Full Text Available A comparative study of five super-storms (Dst<-300 nT of the current solar cycle after the launch of SoHO, to identify solar and interplanetary variables that influence the magnitude of resulting geomagnetic storms, is described. Amongst solar variables, the initial speed of a CME is considered the most reliable predictor of the strength of the associated geomagnetic storm because fast mass ejections are responsible for building up the ram pressure at the Earth's magnetosphere. However, although most of the super-storms studied were associated with high speed CMEs, the Dst index of the resulting geomagnetic storms varied between -300 to -472 nT. The most intense storm of 20 November 2003, (Dst ~ -472 nT had its source in a comparatively smaller active region and was associated with a relatively weaker, M-class flare while all other super-storms had their origins in large active regions and were associated with strong X-class flares. However, this superstorm did not show any associated extraordinary solar and interplanetary characteristics. The study also reveals the challenge in the reliable prediction of the magnitude of a geomagnetic storm from solar and interplanetary variables.

  8. Multifluid Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme: Magnetospheric Composition and Dynamics During Geomagnetic Storms-Initial Results

    Science.gov (United States)

    Glocer, A.; Toth, G.; Ma, Y.; Gombosi, T.; Zhang, J.-C.; Kistler, L. M.

    2009-01-01

    The magnetosphere contains a significant amount of ionospheric O+, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multifluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single-fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multifluid MHD model (with outflow) gives comparable results to the multispecies MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multispecies and multifluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H+ and O+, which is not possible when utilizing the other techniques considered

  9. Polarization Characteristics of Zebra Patterns in Type IV Solar Radio Bursts

    International Nuclear Information System (INIS)

    Kaneda, K.; Misawa, H.; Tsuchiya, F.; Obara, T.; Iwai, K.; Katoh, Y.; Masuda, S.

    2017-01-01

    The polarization characteristics of zebra patterns (ZPs) in type IV solar bursts were studied. We analyzed 21 ZP events observed by the Assembly of Metric-band Aperture Telescope and Real-time Analysis System between 2010 and 2015 and identified the following characteristics: a degree of circular polarization (DCP) in the range of 0%–70%, a temporal delay of 0–70 ms between the two circularly polarized components (i.e., the right- and left-handed components), and dominant ordinary-mode emission in about 81% of the events. For most events, the relation between the dominant and delayed components could be interpreted in the framework of fundamental plasma emission and depolarization during propagation, though the values of DCP and delay were distributed across wide ranges. Furthermore, it was found that the DCP and delay were positively correlated (rank correlation coefficient R = 0.62). As a possible interpretation of this relationship, we considered a model based on depolarization due to reflections at sharp density boundaries assuming fundamental plasma emission. The model calculations of depolarization including multiple reflections and group delay during propagation in the inhomogeneous corona showed that the DCP and delay decreased as the number of reflections increased, which is consistent with the observational results. The dispersive polarization characteristics could be explained by the different numbers of reflections causing depolarization.

  10. Polarization Characteristics of Zebra Patterns in Type IV Solar Radio Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Kaneda, K.; Misawa, H.; Tsuchiya, F.; Obara, T. [Planetary Plasma and Atmospheric Research Center, Tohoku University, Sendai, Miyagi 980-8578 (Japan); Iwai, K. [National Institute of Information and Communications Technology, 4-2-1, Nukui-Kitamachi, Koganei, Tokyo 184-8795 (Japan); Katoh, Y. [Department of Geophysics, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578 (Japan); Masuda, S., E-mail: k.kaneda@pparc.gp.tohoku.ac.jp [Institute for Space—Earth Environmental Research, Nagoya University, Nagoya, Aichi 464-8601 (Japan)

    2017-06-10

    The polarization characteristics of zebra patterns (ZPs) in type IV solar bursts were studied. We analyzed 21 ZP events observed by the Assembly of Metric-band Aperture Telescope and Real-time Analysis System between 2010 and 2015 and identified the following characteristics: a degree of circular polarization (DCP) in the range of 0%–70%, a temporal delay of 0–70 ms between the two circularly polarized components (i.e., the right- and left-handed components), and dominant ordinary-mode emission in about 81% of the events. For most events, the relation between the dominant and delayed components could be interpreted in the framework of fundamental plasma emission and depolarization during propagation, though the values of DCP and delay were distributed across wide ranges. Furthermore, it was found that the DCP and delay were positively correlated (rank correlation coefficient R = 0.62). As a possible interpretation of this relationship, we considered a model based on depolarization due to reflections at sharp density boundaries assuming fundamental plasma emission. The model calculations of depolarization including multiple reflections and group delay during propagation in the inhomogeneous corona showed that the DCP and delay decreased as the number of reflections increased, which is consistent with the observational results. The dispersive polarization characteristics could be explained by the different numbers of reflections causing depolarization.

  11. Summary of daily observational results of solar phenomena, cosmic ray, geomagnetic variation, ionosphere, radio wave propagation and airglow. During October 1973 through September 1975

    Energy Technology Data Exchange (ETDEWEB)

    1976-12-01

    The diagrams in this section of the publication illustrate the summary of daily observational results of solar phenomena, cosmic ray, geomagnetic variation, ionosphere, radio wave propagation and airglow observed in Japan. For convenience, the observational results are arranged by the solar rotation number. The aim of this illustration is to disseminate an outline of daily events observed in Japan for the benefit of active research workers who plan to make detailed study of the specific solar and terrestrial events. Therefore, the illustrations do not show all observational results in Japan but only representative ones at some key stations in Japan. They will suffice for the present purpose. The method of illustration shown in the instruction on the next page is still a preliminary one, and it is subject to change resulting from the kind advice of the users of this part of the publication.

  12. Magnetic Storms at Mars and Earth

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Falkenberg, Thea Vilstrup

    In analogy with magnetic storms at the Earth, periods of significantly enhanced global magnetic activity also exist at Mars. The extensive database of magnetic measurements from Mars Global Surveyor (MGS), covering almost an entire solar cycle, is used in combination with geomagnetic activity...... indices at Earth to compare the occurrence of magnetic storms at Mars and Earth. Based on superposed epochs analysis the time-development of typical magnetic storms at Mars and Earth is described. In contradiction to storms at Earth, most magnetic storms at Mars are found to be associated...... with heliospheric current sheet crossings, where the IMF changes polarity. While most storms at the Earth occur due to significant southward excursions of the IMF associated with CMEs, at Mars most storms seem to be associated with the density enhancement of the heliospheric current sheet. Density enhancements...

  13. GPS phase scintillation during the geomagnetic storm of March 17, 2015: The relation to auroral electrojet currents

    DEFF Research Database (Denmark)

    Prikryl, Paul; Ghoddousi-Fard, Reza; Connors, Martin

    and magnetometers. GPS phase scintillation index is computed for L1 signal sampled at the rate of 50 Hz by specialized GPS scintillation receivers of the Expanded Canadian High Arctic Ionospheric Network (ECHAIN). To further extend the geographic coverage, the phasescintillation proxy index is obtained from......Ionospheric irregularities cause rapid fluctuations of radio wave amplitude and phase that candegrade GPS positional accuracy and affect performance of radio communication and navigation systems. The ionosphere becomes particularly disturbed during geomagnetic storms caused by impacts of coronal...... mass ejections compounded by high-speed plasma streams from coronal holes. Geomagnetic storm of March 17, 2015 was the largest in the current solar cycle. The high-latitude ionosphere dynamics is studied using arrays of ground-based instruments including GPS receivers, HF radars, ionosondes, riometers...

  14. 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)

  15. Current understanding of magnetic storms: Storm-substorm relationships

    International Nuclear Information System (INIS)

    Kamide, Y.; Gonzalez, W.D.; Baumjohann, W.; Daglis, I.A.; Grande, M.; Joselyn, J.A.; Singer, H.J.; McPherron, R.L.; Phillips, J.L.; Reeves, E.G.; Rostoker, G.; Sharma, A.S.; Tsurutani, B.T.

    1998-01-01

    This paper attempts to summarize the current understanding of the storm/substorm relationship by clearing up a considerable amount of controversy and by addressing the question of how solar wind energy is deposited into and is dissipated in the constituent elements that are critical to magnetospheric and ionospheric processes during magnetic storms. (1) Four mechanisms are identified and discussed as the primary causes of enhanced electric fields in the interplanetary medium responsible for geomagnetic storms. It is pointed out that in reality, these four mechanisms, which are not mutually exclusive, but interdependent, interact differently from event to event. Interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs) are found to be the primary phenomena responsible for the main phase of geomagnetic storms. The other two mechanisms, i.e., HILDCAA (high-intensity, long-duration, continuous auroral electrojet activity) and the so-called Russell-McPherron effect, work to make the ICME and CIR phenomena more geoeffective. The solar cycle dependence of the various sources in creating magnetic storms has yet to be quantitatively understood. (2) A serious controversy exists as to whether the successive occurrence of intense substorms plays a direct role in the energization of ring current particles or whether the enhanced electric field associated with southward IMF enhances the effect of substorm expansions. While most of the Dst variance during magnetic storms can be solely reproduced by changes in the large-scale electric field in the solar wind and the residuals are uncorrelated with substorms, recent satellite observations of the ring current constituents during the main phase of magnetic storms show the importance of ionospheric ions. This implies that ionospheric ions, which are associated with the frequent occurrence of intense substorms, are accelerated upward along magnetic field lines, contributing to the energy density of the

  16. Solar weather monitoring

    Directory of Open Access Journals (Sweden)

    J.-F. Hochedez

    2005-11-01

    Full Text Available Space Weather nowcasting and forecasting require solar observations because geoeffective disturbances can arise from three types of solar phenomena: coronal mass ejections (CMEs, flares and coronal holes. For each, we discuss their definition and review their precursors in terms of remote sensing and in-situ observations. The objectives of Space Weather require some specific instrumental features, which we list using the experience gained from the daily operations of the Solar Influences Data analysis Centre (SIDC at the Royal Observatory of Belgium. Nowcasting requires real-time monitoring to assess quickly and reliably the severity of any potentially geoeffective solar event. Both research and forecasting could incorporate more observations in order to feed case studies and data assimilation respectively. Numerical models will result in better predictions of geomagnetic storms and solar energetic particle (SEP events. We review the data types available to monitor solar activity and interplanetary conditions. They come from space missions and ground observatories and range from sequences of dopplergrams, magnetograms, white-light, chromospheric, coronal, coronagraphic and radio images, to irradiance and in-situ time-series. Their role is summarized together with indications about current and future solar monitoring instruments.

  17. A Challenging Solar Eruptive Event of 18 November 2003 and the Causes of the 20 November Geomagnetic Superstorm. II. CMEs, Shock Waves, and Drifting Radio Bursts

    Science.gov (United States)

    Grechnev, V. V.; Uralov, A. M.; Chertok, I. M.; Slemzin, V. A.; Filippov, B. P.; Egorov, Y. I.; Fainshtein, V. G.; Afanasyev, A. N.; Prestage, N. P.; Temmer, M.

    2014-04-01

    We continue our study (Grechnev et al., 2013, doi:10.1007/s11207-013-0316-6; Paper I) on the 18 November 2003 geoffective event. To understand possible impact on geospace of coronal transients observed on that day, we investigated their properties from solar near-surface manifestations in extreme ultraviolet, LASCO white-light images, and dynamic radio spectra. We reconcile near-surface activity with the expansion of coronal mass ejections (CMEs) and determine their orientation relative to the earthward direction. The kinematic measurements, dynamic radio spectra, and microwave and X-ray light curves all contribute to the overall picture of the complex event and confirm an additional eruption at 08:07 - 08:20 UT close to the solar disk center presumed in Paper I. Unusual characteristics of the ejection appear to match those expected for a source of the 20 November superstorm but make its detection in LASCO images hopeless. On the other hand, none of the CMEs observed by LASCO seem to be a promising candidate for a source of the superstorm being able to produce, at most, a glancing blow on the Earth's magnetosphere. Our analysis confirms free propagation of shock waves revealed in the event and reconciles their kinematics with "EUV waves" and dynamic radio spectra up to decameters.

  18. Radio continua modulated by waves: Zebra patterns in solar and pulsar radio spectra?n in the 2001 June 15 flare

    Czech Academy of Sciences Publication Activity Database

    Karlický, Marian

    2013-01-01

    Roč. 552, April (2013), A90/1-A90/6 ISSN 0004-6361 R&D Projects: GA ČR GAP209/12/0103 Grant - others:EU(XE) PIRSES-GA-2011-295272 Institutional support: RVO:67985815 Keywords : Sun * radio radiation * pulsar s Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.479, year: 2013

  19. A superposed epoch analysis of geomagnetic storms

    Directory of Open Access Journals (Sweden)

    J. R. Taylor

    1994-06-01

    Full Text Available A superposed epoch analysis of geomagnetic storms has been undertaken. The storms are categorised via their intensity (as defined by the Dst index. Storms have also been classified here as either storm sudden commencements (SSCs or storm gradual commencements (SGCs, that is all storms which did not begin with a sudden commencement. The prevailing solar wind conditions defined by the parameters solar wind speed (vsw, density (ρsw and pressure (Psw and the total field and the components of the interplanetary magnetic field (IMF during the storms in each category have been investigated by a superposed epoch analysis. The southward component of the IMF, appears to be the controlling parameter for the generation of small SGCs (-100 nT< minimum Dst ≤ -50 nT for ≥ 4 h, but for SSCs of the same intensity solar wind pressure is dominant. However, for large SSCs (minimum Dst ≤ -100 nT for ≥ 4 h the solar wind speed is the controlling parameter. It is also demonstrated that for larger storms magnetic activity is not solely driven by the accumulation of substorm activity, but substantial energy is directly input via the dayside. Furthermore, there is evidence that SSCs are caused by the passage of a coronal mass ejection, whereas SGCs result from the passage of a high speed/ slow speed coronal stream interface. Storms are also grouped by the sign of Bz during the first hour epoch after the onset. The sign of Bz at t = +1 h is the dominant sign of the Bz for ~24 h before the onset. The total energy released during storms for which Bz was initially positive is, however, of the same order as for storms where Bz was initially negative.

  20. Space storms as natural hazards

    Directory of Open Access Journals (Sweden)

    L. I. Dorman

    2008-04-01

    Full Text Available Eruptive activity of the Sun produces a chain of extreme geophysical events: high-speed solar wind, magnetic field disturbances in the interplanetary space and in the geomagnetic field and also intense fluxes of energetic particles. Space storms can potentially destroy spacecrafts, adversely affect astronauts and airline crew and human health on the Earth, lead to pipeline breaking, melt electricity transformers, and discontinue transmission. In this paper we deal with two consequences of space storms: (i rise in failures in the operation of railway devices and (ii rise in myocardial infarction and stroke incidences.

  1. Observations by the CUTLASS radar, HF Doppler, oblique ionospheric sounding, and TEC from GPS during a magnetic storm

    Directory of Open Access Journals (Sweden)

    D. V. Blagoveshchensky

    2005-07-01

    Full Text Available Multi-diagnostic observations, covering a significant area of northwest Europe, were made during the magnetic storm interval (28–29 April 2001 that occurred during the High Rate SolarMax IGS/GPS-campaign. HF radio observations were made with vertical sounders (St. Petersburg and Sodankyla, oblique incidence sounders (OIS, on paths from Murmansk to St. Petersburg, 1050 km, and Inskip to Leicester, 170 km, Doppler sounders, on paths from Cyprus to St. Petersburg, 2800 km, and Murmansk to St. Petersburg, and a coherent scatter radar (CUTLASS, Hankasalmi, Finland. These, together with total electron content (TEC measurements made at GPS stations from the Euref network in northwest Europe, are presented in this paper. A broad comparison of radio propagation data with ionospheric data at high and mid latitudes, under quiet and disturbed conditions, was undertaken. This analysis, together with a geophysical interpretation, allow us to better understand the nature of the ionospheric processes which occur during geomagnetic storms. The peculiarity of the storm was that it comprised of three individual substorms, the first of which appears to have been triggered by a compression of the magnetosphere. Besides the storm effects, we have also studied substorm effects in the observations separately, providing an improved understanding of the storm/substorm relationship. The main results of the investigations are the following. A narrow trough is formed some 10h after the storm onset in the TEC which is most likely a result of enhanced ionospheric convection. An enhancement in TEC some 2–3 h after the storm onset is most likely a result of heating and upwelling of the auroral ionosphere caused by enhanced currents. The so-called main effect on ionospheric propagation was observed at mid-latitudes during the first two substorms, but only during the first substorm at high latitudes. Ionospheric irregularities observed by CUTLASS were clearly related to the

  2. Acceleration and loss of relativistic electrons during small geomagnetic storms.

    Science.gov (United States)

    Anderson, B R; Millan, R M; Reeves, G D; Friedel, R H W

    2015-12-16

    Past studies of radiation belt relativistic electrons have favored active storm time periods, while the effects of small geomagnetic storms ( D s t  > -50 nT) have not been statistically characterized. In this timely study, given the current weak solar cycle, we identify 342 small storms from 1989 through 2000 and quantify the corresponding change in relativistic electron flux at geosynchronous orbit. Surprisingly, small storms can be equally as effective as large storms at enhancing and depleting fluxes. Slight differences exist, as small storms are 10% less likely to result in flux enhancement and 10% more likely to result in flux depletion than large storms. Nevertheless, it is clear that neither acceleration nor loss mechanisms scale with storm drivers as would be expected. Small geomagnetic storms play a significant role in radiation belt relativistic electron dynamics and provide opportunities to gain new insights into the complex balance of acceleration and loss processes.

  3. Some early results from the ATS-6 radio beacon experiment

    International Nuclear Information System (INIS)

    Davies, K.; Fritz, R.B.; Grubb, R.N.; Jones, J.E.

    1975-01-01

    The multifrequency satellite radio beacon enables the measurement of the columnar electron content of the ionosphere and plasmasphere along the ray path and its spatial and temporal structure. Measurements include modulation phase, Faraday rotation, and amplitude. The characteristics of the beacon transmitter and its design are presented together with the design of the Boulder receiver and antennas and the calibration procedures. A shape factor F is defined which depends on the electron density and geomagnetic field distributions. It is found that F varies by about 30 percent from day to night. It is shown that the ratio of the plasmaspheric content to total content varies from about 0.08 during the day to about 0.35 at night. Other examples which are presented to illustrate the uses of the radio beacon include sunrise effects, solar flare enhancements of total content, and the ionospheric storms of early July 1974

  4. Recent progress in satellite radio beacon studies with particular emphasis on the ATS-6 radio beacon experiment

    International Nuclear Information System (INIS)

    Davies, K.

    1980-01-01

    In May 1974 a new era in satellite radio beacon studies of the ionosphere opened with the ATS-6 Radio Beacon Experiment. The history of radio beacon studies up to that time is reviewed briefly and the particular features of the ATS-6 beacon are discussed together with the basic theory required to interpret the measurements. The main emphasis is on the ATS-6 beacon experiment but other beacon data are discussed which provide the necessary background. The diurnal and seasonal variations of the total electron content and the plasmaspheric content are presented for the U.S.A. and Europe. In winter the plasmaspheric content over the Western Hemisphere maximizes at night while in Europe and the Pacific it appears to peak near noon. This is thought to be caused by flow of plasma from the local and conjugate ionospheres. Night maxima of total electron content are found showing that they do not arise from depletions of the plasmaspheric content. The plasmaspheric content is highly sensitive to solar-terrestrial disturbance, it reaches a minimum on the third day of a storm and may take between 10 and 20 days of partial filling and emptying to recover. Travelling disturbances in U.S.A., Europe, and India show similarities of speeds but not of direction. Beacon observations of micropulsations in total content, tropospheric fluctuations and Fresnel diffraction by intense ionospheric irregularities are discussed together with radio wave scintillations and some applications of beacon radio data to communications and navigation. (orig.)

  5. 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...

  6. EclipseMob: Results from a nation-wide citizen science experiment on the effects of the 2017 Solar Eclipse on Low-frequency (LF) Radio Propagation

    Science.gov (United States)

    Liles, W. C.; Lukes, L.; Nelson, J.; Henry, J.; Oputa, J.; Kerby-Patel, K. C.

    2017-12-01

    Early experiments to study the effects of a solar eclipse on radio wave propagation were done with either a limited number of sites before any theory of the ionosphere had been confirmed or involved collecting data that proved to be unusable because submissions were missing critical information such as date, time or location. This study used the 2017 solar eclipse over the continental U.S. to conduct the first wide-area (across the U.S.) low-frequency (LF) propagation study. The data collection process was crowdsourced through the engagement of students/educators, citizens, ham radio enthusiasts, and the scientific community. In order to accomplish data collection by geographically dispersed citizen scientists, the EclipseMob team designed and shared a low cost, low tool/skill DIY receiver system to collect LF data that leveraged existing cell phone technology and made the experiment more accessible to students and people with no prior experience constructing electronic systems. To support engagement, in addition to web guides (eclipsemob..org), EclipseMob supplied 150 DIY kits and provided build/Q&A webinars and events. For the experiment, participants constructed a simple receiver system consisting of a homemade antenna, a simple homemade receiver to convert the radio frequency (RF) signals to audio frequencies, and a smart phone app. Before, during, and after the eclipse, participants used their receiver systems to record transmitter signal data from WWVB located near Fort Collins, Colorado on 60.000 kHz (a U.S. frequency standard that is operated by NIST and transmits time codes). A second frequency, 55.500 kHz transmitted by a LF station in Dixon, CA was also used. By using the time, date and location features of the smart phone, the problems experienced in earlier experiments could be minimized. By crowdsourcing the observation sites across the U.S., data from a number of different short, medium and long- paths could be obtained as the total eclipse crossed

  7. 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.

  8. 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.

  9. Relationships of storm-time changes in thermospheric mass density with solar wind/IMF parameters and ring current index of Sym-H

    Science.gov (United States)

    Zhou, Yunliang; Ma, S. Y.; Xiong, Chao; Luehr, Hermann

    The total air mass densities at about 500 km altitude are derived using super-STAR accelerom-eter measurements onboard GRACE satellites for 25 great magnetic storms with minimum Dst less than 100 nT during 2002 to 2006 years. Taking NRLMSISE-00 model-predicted densities without active ap index input as a reference baseline of quiet-time mass density, the storm-time changes in upper thermospheric mass densities are obtained by subtraction for all the storm events and sorted into different grids of latitude by local time sector. The relationships of the storm-time density changes with various interplanetary parameters and magnetospheric ring current index of Sym-H are statistically investigated. The parameters include Akasofu energy coupling function, the merging electric field Em, the magnitude of IMF component in the GSM y-z plane etc. as calculated from OMNI data at 1 AU. It is found that the storm-time changes in the upper thermospheric mass density have the best linear correlation with the Sym-H index in general, showing nearly zero time delay at low-latitudes and a little time ahead at high-latitudes for most cases. Unexpectedly, the magnitude of IMF component in the y-z plane, Byz, shows correlation with storm-time mass density changes better and closer than Akasofu function and even Em. And, the mass density changes lag behind Byz about 1-4 hours for most cases at low-latitudes. The correlations considered above are local time dependent, showing the lowest at dusk sectors. For the largest superstorm of November 2003, the changes in mass density are correlated very closely with Byz, Em, and Sym-H index, showing correlation coefficients averaged over all latitudes in noon sector as high as 0.93, 0.91 and 0.90 separately. The physical factors controlling the lag times between the mass density changes at mid-low-latitudes and the interplanetary parameter variations are also analyzed. The results in this study may pro-vide useful suggestions for establishing

  10. Measurement of macroscopic plasma parameters with a radio experiment: Interpretation of the quasi-thermal noise spectrum observed in the solar wind

    Science.gov (United States)

    Couturier, P.; Hoang, S.; Meyer-Vernet, N.; Steinberg, J. L.

    1983-01-01

    The ISEE-3 SBH radio receiver has provided the first systematic observations of the quasi-thermal (plasma waves) noise in the solar wind plasma. The theoretical interpretation of that noise involves the particle distribution function so that electric noise measurements with long antennas provide a fast and independent method of measuring plasma parameters: densities and temperatures of a two component (core and halo) electron distribution function have been obtained in that way. The polarization of that noise is frequency dependent and sensitive to the drift velocity of the electron population. Below the plasma frequency, there is evidence of a weak noise spectrum with spectral index -1 which is not yet accounted for by the theory. The theoretical treatment of the noise associated with the low energy (thermal) proton population shows that the moving electrical antenna radiates in the surrounding plasma by Carenkov emission which becomes predominant at the low frequencies, below about 0.1 F sub P.

  11. First Ionospheric Results From the MAVEN Radio Occultation Science Experiment (ROSE)

    Science.gov (United States)

    Withers, Paul; Felici, M.; Mendillo, M.; Moore, L.; Narvaez, C.; Vogt, M. F.; Jakosky, B. M.

    2018-05-01

    Radio occultation observations of the ionosphere of Mars can span the full vertical extent of the ionosphere, in contrast to in situ measurements that rarely sample the main region of the ionosphere. However, most existing radio occultation electron density profiles from Mars were acquired without clear context for the solar forcing or magnetospheric conditions, which presents challenges for the interpretation of these profiles. Here we present 48 ionospheric electron density profiles acquired by the Mars Atmosphere and Volatile EvolutioN mission (MAVEN) Radio Occultation Science Experiment (ROSE) from 5 July 2016 to 27 June 2017 at solar zenith angles of 54° to 101°. Latitude coverage is excellent, and comprehensive context for the interpretation of these profiles is provided by other MAVEN instruments. The profiles show a 9-km increase in ionospheric peak altitude in January 2017 that is associated with a lower atmospheric dust storm, variations in electron densities in the M1 layer that cannot be explained by variations in the solar soft X-ray flux, and topside electron densities that are larger in strongly magnetized regions than in weakly magnetized regions. MAVEN Radio Occultation Science Experiment electron density profiles are publicly available on the NASA Planetary Data System.

  12. Mathematical modeling of the moderate storm on 28 February 2008

    Science.gov (United States)

    Eroglu, Emre

    2018-04-01

    The sun is an active star with plasma-filled prominences. The sudden ejection of the solar plasma creates storms in the form of bursting or spraying. A magnetospheric storm is a typical phenomenon that lasts 1-3 days and involves all magnetosphere from the earth's ionosphere to the magnetotail. The storms are known by different categorical names such as weak, moderate, strong, intense. One of these is the moderate geomagnetic storm on February 28, 2008, which occurred in the 24th solar cycle. The reason for discussing this storm is that it is the first moderate storm in the 24th solar cycle. In this study, we investigate the storm and entered the 24th solar cycle. The correlation among the parametres has been investigated via statistics. The solar wind parameters and the zonal geomagnetic indices have been analyzed separately and then the interaction with each other has been exhibited. The author has concluded the work with two new nonlinear mathematical models. These explain the storm with 79.1% and 87.5% accuracy.

  13. Modeling of very low frequency (VLF radio wave signal profile due to solar flares using the GEANT4 Monte Carlo simulation coupled with ionospheric chemistry

    Directory of Open Access Journals (Sweden)

    S. Palit

    2013-09-01

    Full Text Available X-ray photons emitted during solar flares cause ionization in the lower ionosphere (~60 to 100 km in excess of what is expected to occur due to a quiet sun. Very low frequency (VLF radio wave signals reflected from the D-region of the ionosphere are affected by this excess ionization. In this paper, we reproduce the deviation in VLF signal strength during solar flares by numerical modeling. We use GEANT4 Monte Carlo simulation code to compute the rate of ionization due to a M-class flare and a X-class flare. The output of the simulation is then used in a simplified ionospheric chemistry model to calculate the time variation of electron density at different altitudes in the D-region of the ionosphere. The resulting electron density variation profile is then self-consistently used in the LWPC code to obtain the time variation of the change in VLF signal. We did the modeling of the VLF signal along the NWC (Australia to IERC/ICSP (India propagation path and compared the results with observations. The agreement is found to be very satisfactory.

  14. Importance of post-shock streams and sheath region as drivers of intense magnetospheric storms and high-latitude activity

    Directory of Open Access Journals (Sweden)

    K. E. J. Huttunen

    2004-04-01

    Full Text Available Magnetic disturbances in the Earth's magnetosphere can be very different depending on the type of solar wind driver. We have determined the solar wind causes for intense magnetic storms (DstDst index was more difficult to model for a sheath region or a post-shock stream driven storm than for a storm caused by a magnetic cloud.

  15. Non-storm irregular variation of the Dst index

    Directory of Open Access Journals (Sweden)

    S. Nakano

    2012-01-01

    Full Text Available The Dst index has a long-term variation that is not associated with magnetic storms. We estimated the long-term non-storm component of the Dst variation by removing the short-term variation related to magnetic storms. The results indicate that the variation of the non-storm component includes not only a seasonal variation but also an irregular variation. The irregular long-term variation is likely to be due to an anti-correlation with the long-term variation of solar-wind activity. In particular, a clear anti-correlation is observed between the non-storm component of Dst and the long-term variation of the solar-wind dynamic pressure. This means that in the long term, the Dst index tends to increase when the solar-wind dynamic pressure decreases. We interpret this anti-correlation as an indication that the long-term non-storm variation of Dst is influenced by the tail current variation. The long-term variation of the solar-wind dynamic pressure controls the plasma sheet thermal pressure, and the change of the plasma sheet thermal pressure would cause the non-storm tail current variation, resulting in the non-storm variation of Dst.

  16. 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

  17. 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

  18. NCDC Storm Events Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Storm Data is provided by the National Weather Service (NWS) and contain statistics on personal injuries and damage estimates. Storm Data covers the United States of...

  19. An alternative to the plasma emission model: Particle-in-cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts

    International Nuclear Information System (INIS)

    Tsiklauri, David

    2011-01-01

    High-resolution (sub-Debye length grid size and 10 000 particle species per cell), 1.5D particle-in-cell, relativistic, fully electromagnetic simulations are used to model electromagnetic wave emission generation in the context of solar type III radio bursts. The model studies generation of electromagnetic waves by a super-thermal, hot beam of electrons injected into a plasma thread that contains uniform longitudinal magnetic field and a parabolic density gradient. In effect, a single magnetic line connecting Sun to Earth is considered, for which five cases are studied. (i) We find that the physical system without a beam is stable and only low amplitude level electromagnetic drift waves (noise) are excited. (ii) The beam injection direction is controlled by setting either longitudinal or oblique electron initial drift speed, i.e., by setting the beam pitch angle (the angle between the beam velocity vector and the direction of background magnetic field). In the case of zero pitch angle, i.e., when v-vector b ·E-vector perpendicular =0, the beam excites only electrostatic, standing waves, oscillating at local plasma frequency, in the beam injection spatial location, and only low level electromagnetic drift wave noise is also generated. (iii) In the case of oblique beam pitch angles, i.e., when v-vector b ·E-vector perpendicular =0, again electrostatic waves with same properties are excited. However, now the beam also generates the electromagnetic waves with the properties commensurate to type III radio bursts. The latter is evidenced by the wavelet analysis of transverse electric field component, which shows that as the beam moves to the regions of lower density and hence lower plasma frequency, frequency of the electromagnetic waves drops accordingly. (iv) When the density gradient is removed, an electron beam with an oblique pitch angle still generates the electromagnetic radiation. However, in the latter case no frequency decrease is seen. (v) Since in most of

  20. 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.

  1. Solar Features - Solar Flares - SIDS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Sudden Ionospheric Disturbance (SID) is any of several radio propagation anomalies due to ionospheric changes resulting from solar or geophysical events.

  2. Fine structure in fast drift storm bursts

    International Nuclear Information System (INIS)

    McConnell, D.; Ellis, G.R.A.

    1981-01-01

    Recent observations with high time resolution of fast drift storm (FDS) solar bursts are described. A new variety of FDS bursts characterised by intensity maxima regularly placed in the frequency domain is reported. Possible interpretations of this are mentioned and the implications of the short duration of FDS bursts are discussed. (orig.)

  3. FLARE-GENERATED SHOCK WAVE PROPAGATION THROUGH SOLAR CORONAL ARCADE LOOPS AND AN ASSOCIATED TYPE II RADIO BURST

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Pankaj; Cho, Kyung-Suk [Korea Astronomy and Space Science Institute (KASI), Daejeon, 305-348 (Korea, Republic of); Innes, D. E., E-mail: pankaj@kasi.re.kr [Max-Planck Institut für Sonnensystemforschung, D-37077 Göttingen (Germany)

    2016-09-01

    This paper presents multiwavelength observations of a flare-generated type II radio burst. The kinematics of the shock derived from the type II burst closely match a fast extreme ultraviolet (EUV) wave seen propagating through coronal arcade loops. The EUV wave was closely associated with an impulsive M1.0 flare without a related coronal mass ejection, and was triggered at one of the footpoints of the arcade loops in active region NOAA 12035. It was initially observed in the 335 Å images from the Atmospheric Image Assembly with a speed of ∼800 km s{sup −1} and it accelerated to ∼1490 km s{sup −1} after passing through the arcade loops. A fan–spine magnetic topology was revealed at the flare site. A small, confined filament eruption (∼340 km s{sup −1}) was also observed moving in the opposite direction to the EUV wave. We suggest that breakout reconnection in the fan–spine topology triggered the flare and associated EUV wave that propagated as a fast shock through the arcade loops.

  4. FLARE-GENERATED SHOCK WAVE PROPAGATION THROUGH SOLAR CORONAL ARCADE LOOPS AND AN ASSOCIATED TYPE II RADIO BURST

    International Nuclear Information System (INIS)

    Kumar, Pankaj; Cho, Kyung-Suk; Innes, D. E.

    2016-01-01

    This paper presents multiwavelength observations of a flare-generated type II radio burst. The kinematics of the shock derived from the type II burst closely match a fast extreme ultraviolet (EUV) wave seen propagating through coronal arcade loops. The EUV wave was closely associated with an impulsive M1.0 flare without a related coronal mass ejection, and was triggered at one of the footpoints of the arcade loops in active region NOAA 12035. It was initially observed in the 335 Å images from the Atmospheric Image Assembly with a speed of ∼800 km s −1 and it accelerated to ∼1490 km s −1 after passing through the arcade loops. A fan–spine magnetic topology was revealed at the flare site. A small, confined filament eruption (∼340 km s −1 ) was also observed moving in the opposite direction to the EUV wave. We suggest that breakout reconnection in the fan–spine topology triggered the flare and associated EUV wave that propagated as a fast shock through the arcade loops.

  5. Solar-geophysical data number 389. Part I. Prompt reports. Data for December 1976--November 1976

    International Nuclear Information System (INIS)

    Leighton, H.

    1977-01-01

    This prompt report provides December 1976 and November 1976 data on alert periods, daily solar indices, solar flares, solar radio waves, solar wind measurements, solar x-ray radiation, coronal holes, and inferred IP magnetic field polarities for December. It also provides data on daily solar activity center, sudden ionospheric disturbances, solar radio waves, cosmic rays, geomagnetic indices and radio propagation indices for November

  6. Dynamics of long-period irregular pulsations in high latitudes during strong magnetic storms

    International Nuclear Information System (INIS)

    Kurazhkovskaya, N.A.; Klajn, B.I.

    1995-01-01

    Effects of strong magnetic storms within np type high-latitudinal long-period irregular pulsations at Mirny studied using data obtained at observatory of the magnetosphere south hemisphere. Variation of long-period irregular pulsation amplitude is shown to depend essentially on duration of storm initial phase and on the nature of solar wind heterogeneity enabling growth of strong storm. 14 refs

  7. Optimal series-parallel connection method of dye-sensitized solar cell for Pt thin film deposition using a radio frequency sputter system

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jin-Young; Hong, Ji-Tae; Seo, Hyunwoong; Kim, Mijeong; Son, Min-Kyu; Lee, Kyoung-Jun [Department of Electrical Engineering, Pusan National University Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Lee, Dong-Yoon [Advanced Materials and Application research Laboratory, Korea Electrotechnology Research Institute, 28-1, Seongju-dong, Changwon-city, Kyongnam, 641-120 (Korea, Republic of); Kim, Hee-Je [Department of Electrical Engineering, Pusan National University Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of)], E-mail: heeje@pusan.ac.kr

    2008-11-28

    The counter electrode widely used in DSC (Dye-sensitized solar cells) is constructed of a conducting glass substrate coated with a Pt film, in which the platinum acts as a catalyst. The characteristics of the platinum electrode depend strongly on the fabrication process and the electrode's surface condition. In this study, Pt counter electrodes were deposited by radio frequency (RF) sputtering with 6.7 x 10{sup -1} Pa Ar, RF power of 120 W and substrate temperature of 100 deg. C . The surface morphology of Pt electrodes was investigated using field emission scanning electron microscopy and atomic force microscopy. Comparison of samples prepared by RF sputtering and RF magnetron sputtering showed that the surface of the RF sputter deposited electrode had a larger surface area resulting in more effective catalytic characteristics. Finally, an open voltage of 4.8 V, a short circuit current of 569 mA and a photoelectric conversion efficiency of approximately 3.6% were achieved for cells composed of 30 DSC units of 6 cm x 4 cm DSC units with 6 cells in series and 5 cells in parallel.

  8. Detection of Propagating Fast Sausage Waves through Detailed Analysis of a Zebra-pattern Fine Structure in a Solar Radio Burst

    Science.gov (United States)

    Kaneda, K.; Misawa, H.; Iwai, K.; Masuda, S.; Tsuchiya, F.; Katoh, Y.; Obara, T.

    2018-03-01

    Various magnetohydrodynamic (MHD) waves have recently been detected in the solar corona and investigated intensively in the context of coronal heating and coronal seismology. In this Letter, we report the first detection of short-period propagating fast sausage mode waves in a metric radio spectral fine structure observed with the Assembly of Metric-band Aperture Telescope and Real-time Analysis System. Analysis of Zebra patterns (ZPs) in a type-IV burst revealed a quasi-periodic modulation in the frequency separation between the adjacent stripes of the ZPs (Δf ). The observed quasi-periodic modulation had a period of 1–2 s and exhibited a characteristic negative frequency drift with a rate of 3–8 MHz s‑1. Based on the double plasma resonance model, the most accepted generation model of ZPs, the observed quasi-periodic modulation of the ZP can be interpreted in terms of fast sausage mode waves propagating upward at phase speeds of 3000–8000 km s‑1. These results provide us with new insights for probing the fine structure of coronal loops.

  9. On the equivalence of the solar wind coupling parameter ε and the magnetospheric energy output parameter UT during intense geomagnetic storms

    International Nuclear Information System (INIS)

    Gonzalez, W.D.; Gonzalez, A.L.C.; Tsurutani, B.T.

    1990-01-01

    For intervals with intense geomagnetic activity it is shown that the solar wind coupling parameter ε and the magnetospheric output parameter U T are equivalent and that ranges of values of ε can be set up in terms of values of the ring current-time constant τ. (author)

  10. The differences between storms driven by helmet streamer CIRs and storms driven by pseudostreamer CIRs

    OpenAIRE

    Borovsky, Joseph E.; Denton, Michael

    2013-01-01

    A corotating interaction region (CIR) is formed when fast coronal hole origin solar wind overtakes slow solar wind and forms a region of compressed plasma and magnetic field. The slow wind upstream of the coronal hole fast wind can be either of helmet streamer origin or pseudostreamer origin. For a collection of 125 CIR-driven geomagnetic storms, the slow wind ahead of each CIR is examined; for those storm not containing ejecta, each CIR is categorized as a helmet streamer CIR (74 of the 125 ...

  11. Radio stars

    International Nuclear Information System (INIS)

    Hjellming, R.M.

    1976-01-01

    Any discussion of the radio emission from stars should begin by emphasizing certain unique problems. First of all, one must clarify a semantic confusion introduced into radio astronomy in the late 1950's when most new radio sources were described as radio stars. All of these early 'radio stars' were eventually identified with other galactic and extra-galactic objects. The study of true radio stars, where the radio emission is produced in the atmosphere of a star, began only in the 1960's. Most of the work on the subject has, in fact, been carried out in only the last few years. Because the real information about radio stars is quite new, it is not surprising that major aspects of the subject are not at all understood. For this reason this paper is organized mainly around three questions: what is the available observational information; what physical processes seem to be involved; and what working hypotheses look potentially fruitful. (Auth.)

  12. Multi-Fluid Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme: Magnetospheric Composition and Dynamics During Geomagnetic Storms, Initial Results

    Science.gov (United States)

    Gkocer, A.; Toth, G.; Ma, Y.; Gombosi, T.; Zhang, J. C.; Kistler, L. M.

    2010-01-01

    The magnetosphere contains a significant amount of ionospheric O{+}, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the BATS-R-US model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multi-fluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single- fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multi-fluid MHD model (with outflow) gives comparable results to the multi-species MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multi-species and multi-fluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H{+} and O(+}, which is not possible when utilizing the other techniques considered.

  13. Radio stars

    International Nuclear Information System (INIS)

    Hjellming, R.M.; Gibson, D.M.

    1985-01-01

    Studies of stellar radio emission became an important field of research in the 1970's and have now expanded to become a major area of radio astronomy with the advent of new instruments such as the Very Large Array in New Mexico and transcontinental telescope arrays. This volume contains papers from the workshop on stellar continuum radio astronomy held in Boulder, Colorado, and is the first book on the rapidly expanding field of radio emission from stars and stellar systems. Subjects covered include the observational and theoretical aspects of stellar winds from both hot and cool stars, radio flares from active double star systems and red dwarf stars, bipolar flows from star-forming regions, and the radio emission from X-ray binaries. (orig.)

  14. Solar-Terrestrial Interactions

    National Research Council Canada - National Science Library

    Kahler, Stephen W

    2008-01-01

    ...) particle events, the solar wind, and geomagnetic storms. The investigators, working at Hanscom AFB, MA, have used many different kinds of space- and ground-based observations and have collaborated with workers at various institutions in this work...

  15. Nippon Storm Study design

    Directory of Open Access Journals (Sweden)

    Takashi Kurita

    2012-10-01

    Full Text Available An understanding of the clinical aspects of electrical storm (E-storms in patients with implantable cardiac shock devices (ICSDs: ICDs or cardiac resynchronization therapy with defibrillator [CRT-D] may provide important information for clinical management of patients with ICSDs. The Nippon Storm Study was organized by the Japanese Heart Rhythm Society (JHRS and Japanese Society of Electrocardiology and was designed to prospectively collect a variety of data from patients with ICSDs, with a focus on the incidence of E-storms and clinical conditions for the occurrence of an E-storm. Forty main ICSD centers in Japan are participating in the present study. From 2002, the JHRS began to collect ICSD patient data using website registration (termed Japanese cardiac defibrillator therapy registration, or JCDTR. This investigation aims to collect data on and investigate the general parameters of patients with ICSDs, such as clinical backgrounds of the patients, purposes of implantation, complications during the implantation procedure, and incidence of appropriate and inappropriate therapies from the ICSD. The Nippon Storm Study was planned as a sub-study of the JCDTR with focus on E-storms. We aim to achieve registration of more than 1000 ICSD patients and complete follow-up data collection, with the assumption of a 5–10% incidence of E-storms during the 2-year follow-up.

  16. Assessing storm erosion hazards

    NARCIS (Netherlands)

    Ranasinghe, Ranasinghe W M R J B; Callaghan, D.; Ciavola, Paolo; Coco, Giovanni

    2017-01-01

    The storm erosion hazard on coasts is usually expressed as an erosion volume and/or associated episodic coastline retreat. The accurate assessment of present-day and future storm erosion volumes is a key task for coastal zone managers, planners and engineers. There are four main approaches that can

  17. The Role of Ionospheric Outflow Preconditioning in Determining Storm Geoeffectiveness

    Science.gov (United States)

    Welling, D. T.; Liemohn, M. W.; Ridley, A. J.

    2012-12-01

    It is now well accepted that ionospheric outflow plays an important role in the development of the plasma sheet and ring current during geomagnetic storms. Furthermore, even during quiet times, ionospheric plasma populates the magnetospheric lobes, producing a reservoir of hydrogen and oxygen ions. When the Interplanetary Magnetic Field (IMF) turns southward, this reservoir is connected to the plasma sheet and ring current through magnetospheric convection. Hence, the conditions of the ionosphere and magnetospheric lobes leading up to magnetospheric storm onset have important implications for storm development. Despite this, there has been little research on this preconditioning; most global simulations begin just before storm onset, neglecting preconditioning altogether. This work explores the role of preconditioning in determining the geoeffectiveness of storms using a coupled global model system. A model of ionospheric outflow (the Polar Wind Outflow Model, PWOM) is two-way coupled to a global magnetohydrodynamic model (the Block-Adaptive Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), which in turn drives a ring current model (the Ring current Atmosphere interactions Model, RAM). This unique setup is used to simulate an idealized storm. The model is started at many different times, from 1 hour before storm onset to 12 hours before. The effects of storm preconditioning are examined by investigating the total ionospheric plasma content in the lobes just before onset, the total ionospheric contribution in the ring current just after onset, and the effects on Dst, magnetic elevation angle at geosynchronous, and total ring current energy density. This experiment is repeated for different solar activity levels as set by F10.7 flux. Finally, a synthetic double-dip storm is constructed to see how two closely spaced storms affect each other by changing the preconditioning environment. It is found that preconditioning of the magnetospheric lobes via ionospheric

  18. Forecasts of geomagnetic activities and HF radio propagation conditions made at Hiraiso/Japan

    Science.gov (United States)

    Marubashi, K.; Miyamoto, Y.; Kidokoro, T.; Ishii, T.

    1979-01-01

    The Hiraiso Branch of RRL prediction techniques are summarized separately for the 27 day recurrent storm and the flare-associated storm. The storm predictions are compared with the actual geomagnetic activities in two ways. The first one is the comparison on a day to day basis. In the second comparison, the accuracy of the storm predictions during 1965-1976 are evaluated. In addition to the storm prediction, short-term predictions of HF radio propagation conditions are conducted at Hiraiso. The HF propagation predictions are briefly described as an example of the applications of the magnetic storm prediction.

  19. Tools of radio astronomy

    CERN Document Server

    Wilson, Thomas L; Hüttemeister, Susanne

    2013-01-01

    This 6th edition of “Tools of Radio Astronomy”, the most used introductory text in radio astronomy, has been revised to reflect the current state of this important branch of astronomy. This includes the use of satellites, low radio frequencies, the millimeter/sub-mm universe, the Cosmic Microwave Background and the increased importance of mm/sub-mm dust emission. Several derivations and presentations of technical aspects of radio astronomy and receivers, such as receiver noise, the Hertz dipole and  beam forming have been updated, expanded, re-worked or complemented by alternative derivations. These reflect advances in technology. The wider bandwidths of the Jansky-VLA and long wave arrays such as LOFAR and mm/sub-mm arrays such as ALMA required an expansion of the discussion of interferometers and aperture synthesis. Developments in data reduction algorithms have been included. As a result of the large amount of data collected in the past 20 years, the discussion of solar system radio astronomy, dust em...

  20. The 3-D solar radioastronomy and the structure of the corona and the solar wind. [solar probes of solar activity

    Science.gov (United States)

    Steinberg, J. L.; Caroubalos, C.

    1976-01-01

    The mechanism causing solar radio bursts (1 and 111) is examined. It is proposed that a nonthermal energy source is responsible for the bursts; nonthermal energy is converted into electromagnetic energy. The advantages are examined for an out-of-the-ecliptic solar probe mission, which is proposed as a means of stereoscopically viewing solar radio bursts, solar magnetic fields, coronal structure, and the solar wind.

  1. Ionospheric storms at geophysically-equivalent sites – Part 1: Storm-time patterns for sub-auroral ionospheres

    Directory of Open Access Journals (Sweden)

    M. Mendillo

    2009-04-01

    Full Text Available The systematic study of ionospheric storms has been conducted primarily with groundbased data from the Northern Hemisphere. Significant progress has been made in defining typical morphology patterns at all latitudes; mechanisms have been identified and tested via modeling. At higher mid-latitudes (sites that are typically sub-auroral during non-storm conditions, the processes that change significantly during storms can be of comparable magnitudes, but with different time constants. These include ionospheric plasma dynamics from the penetration of magnetospheric electric fields, enhancements to thermospheric winds due to auroral and Joule heating inputs, disturbance dynamo electrodynamics driven by such winds, and thermospheric composition changes due to the changed circulation patterns. The ~12° tilt of the geomagnetic field axis causes significant longitude effects in all of these processes in the Northern Hemisphere. A complementary series of longitude effects would be expected to occur in the Southern Hemisphere. In this paper we begin a series of studies to investigate the longitudinal-hemispheric similarities and differences in the response of the ionosphere's peak electron density to geomagnetic storms. The ionosonde stations at Wallops Island (VA and Hobart (Tasmania have comparable geographic and geomagnetic latitudes for sub-auroral locations, are situated at longitudes close to that of the dipole tilt, and thus serve as our candidate station-pair choice for studies of ionospheric storms at geophysically-comparable locations. They have an excellent record of observations of the ionospheric penetration frequency (foF2 spanning several solar cycles, and thus are suitable for long-term studies. During solar cycle #20 (1964–1976, 206 geomagnetic storms occurred that had Ap≥30 or Kp≥5 for at least one day of the storm. Our analysis of average storm-time perturbations (percent deviations from the monthly means showed a remarkable

  2. Topographic Correction Module at Storm (TC@Storm)

    Science.gov (United States)

    Zaksek, K.; Cotar, K.; Veljanovski, T.; Pehani, P.; Ostir, K.

    2015-04-01

    Different solar position in combination with terrain slope and aspect result in different illumination of inclined surfaces. Therefore, the retrieved satellite data cannot be accurately transformed to the spectral reflectance, which depends only on the land cover. The topographic correction should remove this effect and enable further automatic processing of higher level products. The topographic correction TC@STORM was developed as a module within the SPACE-SI automatic near-real-time image processing chain STORM. It combines physical approach with the standard Minnaert method. The total irradiance is modelled as a three-component irradiance: direct (dependent on incidence angle, sun zenith angle and slope), diffuse from the sky (dependent mainly on sky-view factor), and diffuse reflected from the terrain (dependent on sky-view factor and albedo). For computation of diffuse irradiation from the sky we assume an anisotropic brightness of the sky. We iteratively estimate a linear combination from 10 different models, to provide the best results. Dependent on the data resolution, we mask shades based on radiometric (image) or geometric properties. The method was tested on RapidEye, Landsat 8, and PROBA-V data. Final results of the correction were evaluated and statistically validated based on various topography settings and land cover classes. Images show great improvements in shaded areas.

  3. Plasma Diagnostics of the Interstellar Medium with Radio Astronomy

    OpenAIRE

    Haverkorn, Marijke; Spangler, Steven R.

    2013-01-01

    We discuss the degree to which radio propagation measurements diagnose conditions in the ionized gas of the interstellar medium (ISM). The "signal generators" of the radio waves of interest are extragalactic radio sources (quasars and radio galaxies), as well as Galactic sources, primarily pulsars. The polarized synchrotron radiation of the Galactic non-thermal radiation also serves to probe the ISM, including space between the emitting regions and the solar system. Radio propagation measurem...

  4. 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

  5. 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

  6. From pre-storm activity to magnetic storms: a transition described in terms of fractal dynamics

    Directory of Open Access Journals (Sweden)

    G. Balasis

    2006-12-01

    Full Text Available We show that distinct changes in scaling parameters of the Dst index time series occur as an intense magnetic storm approaches, revealing a gradual reduction in complexity. The remarkable acceleration of energy release – manifested in the increase in susceptibility – couples to the transition from anti-persistent (negative feedback to persistent (positive feedback behavior and indicates that the occurence of an intense magnetic storm is imminent. The main driver of the Dst index, the VBSouth electric field component, does not reveal a similar transition to persistency prior to the storm. This indicates that while the magnetosphere is mostly driven by the solar wind the critical feature of persistency in the magnetosphere is the result of a combination of solar wind and internal magnetospheric activity rather than solar wind variations alone. Our results suggest that the development of an intense magnetic storm can be studied in terms of "intermittent criticality" that is of a more general character than the classical self-organized criticality phenomena, implying the predictability of the magnetosphere.

  7. Solar-geophysical data number 408, August 1978, Part I. (Prompt reports). Data for July 1978, June 1978

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1978-08-01

    This prompt report provides data for July 1978 on: alert period, daily solar indices, solar flares, solar radio waves, solar x-ray radiation, coronal holes, solar wind measurements, inferred IP magnetic field polarities, mean solar magnetic field, spacecraft observations, Boulder geomagnetic substorm log, and energetic solar particles. It also provides data for June 1978 on: daily solar activity center, sudden ionospheric disturbances, solar x-ray radiation, solar radio waves, cosmic rays, geomagnetic indices, and radio propagation indices

  8. A Regional GPS Receiver Network For Monitoring Mid-latitude Total Electron Content During Storms

    Science.gov (United States)

    Vernon, A.; Cander, Lj. R.

    A regional GPS receiver network has been used for monitoring mid-latitude total elec- tron content (TEC) during ionospheric storms at the current solar maximum. Differ- ent individual storms were examined to study how the temporal patterns of changes develop and how they are related to solar and geomagnetic activity for parameter de- scriptive of plasmaspheric-ionospheric ionisation. Use is then made of computer con- touring techniques to produce snapshot maps of TEC for different study cases. Com- parisons with the local ionosonde data at different phases of the storms enable the storm developments to be studied in detail.

  9. 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.

  10. 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.

  11. Storm Data Publication

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — 'Storm Data and Unusual Weather Phenomena' is a monthly publication containing a chronological listing, by state, of hurricanes, tornadoes, thunderstorms, hail,...

  12. Ionosphere and its Influence on Radio Communications

    Indian Academy of Sciences (India)

    Italian radio pioneer G Marconi succeeded in transmitting. 'wireless' signals over a distance of about 2000 miles across the. Atlantic Ocean. Physicists had .... indirectly, to the ionizing power of the solar radiation. As this radiation penetrates the ...

  13. Storm surge climatology report

    OpenAIRE

    Horsburgh, Kevin; Williams, Joanne; Cussack, Caroline

    2017-01-01

    Any increase in flood frequency or severity due to sea level rise or changes in storminess would adversely impact society. It is crucial to understand the physical drivers of extreme storm surges to have confidence in the datasets used for extreme sea level statistics. We will refine and improve methods to the estimation of extreme sea levels around Europe and more widely. We will do so by developing a comprehensive world picture of storm surge distribution (including extremes) for both tropi...

  14. Orbiting low frequency array for radio astronomy

    NARCIS (Netherlands)

    Rajan, Rai Thilak; Rajan, Raj; Engelen, Steven; Bentum, Marinus Jan; Verhoeven, Chris

    2011-01-01

    Recently new and interesting science drivers have emerged for very low frequency radio astronomy from 0.3 MHz to 30 MHz. However Earth bound radio observations at these wavelengths are severely hampered by ionospheric distortions, man made interference, solar flares and even complete reflection

  15. Solar-geophysical data number 584, April 1993. Part 1 (prompt reports). Data for March, February 1993, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1993-04-01

    Contents: data for march 1993: solar-terrestrial environment; iuwds alert periods (advance and worldwide); solar activity indices; solar flares; solar radio emission; stanford mean solar magnetic field; data for february 1993: solar active regions; sudden ionospheric disturbances; solar radio spectral observations; cosmic ray measurements by neutron monitor; geomagnetic indices. This research is applicable to studies in communications, environmental science,and solar energy

  16. Radio science investigations with Voyager

    International Nuclear Information System (INIS)

    Eshleman, V.R.; Tyler, G.L.; Croft, T.A.

    1977-01-01

    The planned radio science investigations during the Voyager missions to the outer planets involve: (1) the use of the radio links to and from the spacecraft for occultation measurements of planetary and satellite atmospheres and ionospheres, the rings of Saturn, the solar corona, and the general-relativistic time delay for radiowave propagation through the Sun's gravity field; (2) radio link measurements of true or apparent spacecraft motion caused by the gravity fields of the planets, the masses of their larger satellites, and characteristics of the interplanetary medium; and (3) related measurements which could provide results in other areas, including the possible detection of long-wavelength gravitational radiation propagating through the Solar System. The measurements will be used to study: atmospheric and ionospheric structure, constituents, and dynamics; the sizes, radial distribution, total mass, and other characteristics of the particles in the rings of Saturn; interior models for the major planets and the mean density and bulk composition of a number of their satellites; the plasma density and dynamics of the solar corona and interplanetary medium; and certain fundamental questions involving gravitation and relativity. The instrumentation for these experiments is the same ground-based and spacecraft radio systems as will be used for tracking and communicating with the Voyager spacecraft, although several important features of these systems have been provided primarily for the radio science investigations. (Auth.)

  17. Role of neutral wind and storm time electric fields inferred from the storm time ionization distribution at low latitudes: in-situ measurements by Indian satellite SROSS-C2

    OpenAIRE

    Subrahmanyam , P.; Jain , A. R.; Singh , L.; Garg , S. C.

    2005-01-01

    Recently, there has been a renewal of interest in the study of the effects of solar weather events on the ionization redistribution and irregularity generation. The observed changes at low and equatorial latitudes are rather complex and are noted to be a function of location, the time of the storm onset and its intensity, and various other characteristics of the geomagnetic storms triggered by solar weather events. At these latitudes, the effects of geomagnetic storms are basically due to (a)...

  18. Radio astronomy

    International Nuclear Information System (INIS)

    Parijskij, Y.N.; Gossachinskij, I.V.; Zuckerman, B.; Khersonsky, V.K.; Pustilnik, S.; Robinson, B.J.

    1976-01-01

    A critical review of major developments and discoveries in the field of radioastronomy during the period 1973-1975 is presented. The report is presented under the following headings:(1) Continuum radiation from the Galaxy; (2) Neutral hydrogen, 21 cm (galactic and extragalactic) and recombination lines; (3) Radioastronomy investigations of interstellar molecules; (4) Extragalactic radio astronomy and (6) Development in radio astronomy instruments. (B.R.H.)

  19. Solar-geophysical data number 391. Part I. Prompt reports. Data for February 1977--January 1977

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1977-03-01

    This prompt report provides data for February 1977 on alert periods, daily solar indices, solar flares, solar radio waves, solar X-ray radiation, coronal holes, solar wind measurements, spacecraft observations, inferred IP magnetic field polarities and mean solar magnetic field. It also provides data for January 1977 on daily solar activity center, sudden ionospheric disturbances, solar radio waves, cosmic rays, geomagnetic indices and radio propagation indices

  20. Solar--geophysical data number 398, October 1977. Part I. (Prompt reports). Data for September 1977--August 1977

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1977-10-01

    This prompt report provides data for September 1977 on alert period, daily solar indices, solar flares, solar radio waves, coronal holes, solar x-ray radiation, solar wind measurements, inferred IP magnetic field polarities, mean solar magnetic field, and solar proton event (Provisional). It also provides data for August 1977 on daily solar activity centers, sudden ionospheric disturbances, solar radio waves, cosmic rays, geomagnetic indices and radio propagation indices

  1. Solar-geophysical data number 410, October 1978, Part I (Prompt reports). Data for September 1978, August 1978

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1978-10-01

    This prompt report provides data for September 1978 on alert period, daily solar indices, solar flares, solar radio waves, solar x-ray radiation, coronal holes, solar wind measurements, inferred IP magnetic field polarities, mean solar magnetic field and Boulder geomagnetic substorm log. It also provides data for August 1978 on daily solar activity center, sudden ionospheric disturbances, solar x-ray radiation, solar radio waves, cosmic rays, geomagnetic indices and radio propagation indices

  2. 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

  3. 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

  4. Storm and cloud dynamics

    CERN Document Server

    Cotton, William R

    1992-01-01

    This book focuses on the dynamics of clouds and of precipitating mesoscale meteorological systems. Clouds and precipitating mesoscale systems represent some of the most important and scientifically exciting weather systems in the world. These are the systems that produce torrential rains, severe winds including downburst and tornadoes, hail, thunder and lightning, and major snow storms. Forecasting such storms represents a major challenge since they are too small to be adequately resolved by conventional observing networks and numerical prediction models.Key Features* Key Highlight

  5. Radio emission of the sun and planets

    CERN Document Server

    Zheleznyakov, V V

    1970-01-01

    International Series of Monographs in Natural Philosophy, Volume 25: Radio Emission of the Sun and Planets presents the origin of the radio emission of the planets. This book examines the outstanding triumphs achieved by radio astronomy of the solar system. Comprised of 10 chapters, this volume begins with an overview of the physical conditions in the upper layers of the Sun, the Moon, and the planets. This text then examines the three characteristics of radio emission, namely, the frequency spectrum, the polarization, and the angular spectrum. Other chapters consider the measurements of the i

  6. 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

  7. Interplanetary sources of magnetic storms: A statistical study

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne

    2001-01-01

    Magnetic storms are mainly caused by the occurrence of intense southward magnetic fields in the interplanetary medium. These fields can be formed directly either by ejection of magnetic structures from the Sun or by stream interaction processes during solar wind propagation. In the present study we...... examine 30 years of satellite measurement of the solar wind during magnetic storms, with the aim of estimating the relative importance of these two processes. We use the solar wind proton temperature relative to the temperature expected from the empirical relation to the solar wind speed T......-p/T-exp, together with the speed gradient, and the interplanetary magnetic field azimuth in the ecliptic, in order to distinguish between the two processes statistically. We find that compression due to stream interaction is at least as important as the direct effect of ejection of intense fields, and probably more...

  8. Interplanetary sources to magnetic storms - A statistical study

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne

    2001-01-01

    Magnetic storms are mainly caused by the occurrence of intense southward magnetic fields in the interplanetary medium. These fields can be formed directly either by ejection of magnetic structures from the Sun or by stream interaction processes during solar wind propagation. In the present study we...... examine 30 years of satellite measurement of the solar wind during magnetic storms, with the aim of estimating the relative importance of these two processes. We use the solar wind proton temperature relative to the temperature expected from the empirical relation to the solar wind speed Tp/Texp, together...... with the speed gradient, and the interplanetary magnetic field azimuth in the ecliptic, in order to distinguish between the two processes statistically. We find that compression due to stream interaction is at least as important as the direct effect of ejection of intense fields, and probably more so. Only...

  9. The Equatorial Scintillations and Space Weather Effects on its Generation during Geomagnetic Storms

    Science.gov (United States)

    Biktash, Lilia

    Great diversity of the ionospheric phenomena leads to a variety of irregularity types with spatial size from many thousands of kilometers to few centimeters and lifetimes from days to fractions of second. Since the ionosphere strongly influences the propagation of radio waves, signal distortions caused by these irregularities affect short-wave transmissions on Earth, transiono-spheric satellite communications and navigation. In this work the solar wind and the equatorial ionosphere parameters, Kp, Dst, AU, AL indices characterized contribution of different mag-netospheric and ionospheric currents to the H-component of geomagnetic field are examined to test the space weather effect on the generation of ionospheric irregularities producing VLF scintillations. According to the results of the current statistical studies, one can predict scintil-lations from Aarons' criteria using the Dst index, which mainly depicts the magnetospheric ring current field. To amplify Aarons' criteria or to propose new criteria for predicting scintillation characteristics is the question. In the present phase of the experimental investigations of elec-tron density irregularities in the ionosphere new ways are opened up because observations in the interaction between the solar wind -magnetosphere -ionosphere during magnetic storms have progressed greatly. We have examined scintillation relation to magnetospheric and ionospheric currents and show that the factor, which presents during magnetic storms to fully inhibit scin-tillation, is the positive Bz-component of the IMF. During the positive Bz IMF F layer cannot raise altitude where scintillations are formed. The auroral indices and Kp do better for the prediction of the ionospheric scintillations at the equator. The interplanetary magnetic field data and models can be used to explain the relationship between the equatorial ionospheric parameters, h'F, foF2, and the equatorial geomagnetic variations with the polar ionosphere cur-rents and

  10. California's Perfect Storm

    Science.gov (United States)

    Bacon, David

    2010-01-01

    The United States today faces an economic crisis worse than any since the Great Depression of the 1930s. Nowhere is it sharper than in the nation's schools. Last year, California saw a perfect storm of protest in virtually every part of its education system. K-12 teachers built coalitions with parents and students to fight for their jobs and their…

  11. Dave Storm esitleb singlit

    Index Scriptorium Estoniae

    2002-01-01

    7. märtsil klubis Spirit ja 8. märtsil klubis Terminal presenteerib tallinlane DJ Dave Storm oma uut singlit "Ride", millel teeb laulmisega kaasa ameeriklane Charlie C. Singelplaadi annab peadselt välja Inglise plaadifirma Refunkt

  12. Interview with Gert Storm

    NARCIS (Netherlands)

    Storm, Gerrit

    2013-01-01

    Gert Storm studied biology at the Utrecht University, The Netherlands, and obtained his PhD degree in 1987 at the Department of Pharmaceutics of the same university. He is now Professor of targeted drug delivery at the University of Utrecht, as well as Professor of targeted therapeutics at the MIRA

  13. Synthesis imaging in radio astronomy

    International Nuclear Information System (INIS)

    Perley, R.A.; Schwab, F.R.; Bridle, A.H.

    1989-01-01

    Recent advances in techniques and instrumentation for radio synthesis imaging in astronomy are discussed in a collection of review essays. Topics addressed include coherence in radio astronomy, the interferometer in practice, primary antenna elements, cross correlators, calibration and editing, sensitivity, deconvolution, self-calibration, error recognition, and image analysis. Consideration is given to wide-field imaging (bandwidth and time-average smearing, noncoplanar arrays, and mosaicking), high-dynamic-range imaging, spectral-line imaging, VLBI, solar imaging with a synthesis telescope, synthesis imaging of spatially coherent objects, noise in images of very bright sources, synthesis observing strategies, and the design of aperture-synthesis arrays

  14. New discoveries with radio telescopes

    International Nuclear Information System (INIS)

    Schmidt, J.

    1985-01-01

    The author describes in a simple fashion the results obtained by astronomers from ETH Zurich using the broadband 7-m radio telescope in Switzerland to observe the sun over a period of six years. He explains the results in terms of our present understanding of the sun's workings. The astronomers found that a solar eruption is not a single event but consists of tens of thousands of small eruptions or spikes each only 200 km high and producing a burst of radio waves 10-100 times as intense as the background. (T.J.R.A.)

  15. Solar--geophysical data number 402, February 1978. Part I. Prompt reports. Data for January 1978--December 1977

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1978-02-01

    This prompt report provides data for January 1978 on alert period, daily solar indices, solar flares, solar radio waves, solar x-ray radiation, coronal holes, spacecraft observations, inferred IP magnetic field polarities, mean solar magnetic field and solar wind measurements. It also provides data for December 1977 on daily solar activity center, sudden ionospheric disturbances, solar radio waves, cosmic rays, geomagnetic indices, and radio propagation indices

  16. Solar-Geophysical Data Number 539, July 1989. Part 1 (prompt reports). Data for June, May 1989, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1989-07-01

    Contents include: detailed index for 1988-1989; data for June 1989 -- IUWDS alert periods (advance and worldwide), solar-activity indices, solar flares, solar radio emission, Stanford mean solar magnetic field; data for May 1989 -- solar active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic-ray measurements by neutron monitor, geomagnetic indices; late data -- solar radio emission (Nancay 169-MHz solar interferometric chart, May 1989)

  17. Equatorial ionospheric electric fields during the November 2004 magnetic storm

    OpenAIRE

    Fejer, Bela G.; Jensen, J. W.; Kikuchi, T.; Abdu, M. A.; Chau, J. L.

    2007-01-01

    [1] We use radar measurements from the Jicamarca Radio Observatory, magnetometer observations from the Pacific sector and ionosonde data from Brazil to study equatorial ionospheric electric fields during the November 2004 geomagnetic storm. Our data show very large eastward and westward daytime electrojet current perturbations with lifetimes of about an hour (indicative of undershielding and overshielding prompt penetration electric fields) in the Pacific equatorial region during the November...

  18. Solar activity during the space weather incident of Nov 4., 2015 - Complex data and lessons learned

    Science.gov (United States)

    Opgenoorth, Hermann; Pulkkinen, Antti; Buchert, Stephan; Monstein, Christian; Klein, Karl Ludwig; Marqué, Christophe; Krucker, Säm

    2016-04-01

    During the afternoon of November 4, 2015 most southern Swedish aviation radar systems experienced heavy disturbances, which eventually forced an outing of the majority of the radars. In consequence the entire southern Swedish aerospace had to be closed for incoming and leaving air traffic for about 2 hours. Immediately after the incident space weather anomalies were made responsible for the radar disturbances, but it took a very thorough investigation to differentiate disturbances from an ongoing magnetic storm caused by earlier solar activity, which had no disturbing effects on the flight radars, from a new and, indeed, extreme radio-burst on the Sun, which caused the Swedish radar anomalies. Other systems in various European countries also experienced major radio-disturbances during this extreme event, but they were not of the gravity as experienced in Sweden, or at least not causing a similar damage. One of the problems in reaching the right conclusions about the incident was that the extreme radio-burst around 1400 UT on Nov 4 (more than 50000 SFU at GHz frequencies), emerged from a medium size M3.7 Flare on the Sun, which did not trigger any immediate warnings. We will report about the analysis leading to the improved understanding of this extreme space weather event, evaluate the importance of solar radio observations, and discuss possible mitigation strategies for future events of similar nature.

  19. Disturbance phenomena in VLF standard radio wave observation

    International Nuclear Information System (INIS)

    Muraoka, Yoshikazu

    1977-01-01

    Storm aftereffect, i.e. the phase disturbance after initiation of a magnetic storm has been revealed in the observation of VLF standard radio waves. In VLF long distance propagation at middle latitudes (L - 3), the phase disturbance for several days after the initiation of a magnetic storm is due to electron fall from the radiation belt. This has been confirmed by the comparison with electron flux detected by an artificial satellite. The correlations between VLF phase disturbance and magnetism activity or ionosphere absorption are described. The relation between winter anomaly and phase disturbance is also discussed. (Mori, K.)

  20. Solar-Geophysical Data Number 528, August 1988. Part 1 (prompt reports). Data for July, June 1988, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.; McKinnon, J.A.

    1988-08-01

    Contents include: data for July 1988; IUWDS alert periods (advance and worldwide); solar-activity indices; solar flares; solar radio emission; solar interferometric chart; Stanford mean solar magnetic field

  1. Leonid storm research

    CERN Document Server

    Rietmeijer, Frans; Brosch, Noah; Fonda, Mark

    2000-01-01

    This book will appeal to all researchers that have an interest in the current Leonid showers It contains over forty research papers that present some of the first observational results of the November 1999 Leonid meteor storm, the first storm observed by modern observing techniques The book is a first glimpse of the large amount of information obtained during NASA's Leonid Multi-Instrument Aircraft Campaign and groundbased campaigns throughout the world It provides an excellent overview on the state of meteor shower research for any professional researcher or amateur meteor observer interested in studies of meteors and meteoroids and their relation to comets, the origin of life on Earth, the satellite impact hazard issue, and upper atmosphere studies of neutral atom chemistry, the formation of meteoric debris, persistent trains, airglow, noctilucent clouds, sprites and elves

  2. Dust storm, northern Mexico

    Science.gov (United States)

    1983-01-01

    This large dust storm along the left side of the photo, covers a large portion of the state of Coahuila, Mexico (27.5N, 102.0E). The look angle of this oblique photo is from the south to the north. In the foreground is the Sierra Madre Oriental in the states Coahuila and Nuevo Leon with the Rio Grande River, Amistad Reservoir and Texas in the background.

  3. LibrarySTORM

    DEFF Research Database (Denmark)

    Breüner, Niels; Bech, Tine

    2013-01-01

    Når flere uddannelser samles i en nybygning til Campus C på Ceres grunden i Aarhus, skal der også indrettes et fælles bibliotek. Når der samtidig er midler til at arbejde med brugerdreven innovation, lå det lige for at inddrage de studerende og få deres visioner for fremtidens bibliotek. Der blev...... arrangeret en udviklingsdag, hvor der skulle brainstormes – og projektet blev kaldt LibrarySTORM....

  4. Modeling storm waves

    International Nuclear Information System (INIS)

    Benoit, M.; Marcos, F.; Teisson, Ch.

    1999-01-01

    Nuclear power stations located on the coast take the water they use to cool their circuits from the sea. The water intake and discharge devices must be able to operate in all weathers, notably during extreme storms, with waves 10 m high and over. To predict the impact of the waves on the equipment, they are modeled digitally from the moment they form in the middle of the ocean right up to the moment they break on the shore. (authors)

  5. The Radio JOVE Project - Shoestring Radio Astronomy

    Science.gov (United States)

    Thieman, J.; Flagg, R.; Greenman, W.; Higgins, C.; Reyes, F.; Sky, J.

    2010-01-01

    Radio JOVE is an education and outreach project intended to give students and other interested individuals hands-on experience in learning radio astronomy. They can do this through building a radio telescope from a relatively inexpensive kit that includes the parts for a receiver and an antenna as well as software for a computer chart recorder emulator (Radio Skypipe) and other reference materials

  6. Space Telecommunications Radio System STRS Cognitive Radio

    Science.gov (United States)

    Briones, Janette C.; Handler, Louis M.

    2013-01-01

    Radios today are evolving from awareness toward cognition. A software defined radio (SDR) provides the most capability for integrating autonomic decision making ability and allows the incremental evolution toward a cognitive radio. This cognitive radio technology will impact NASA space communications in areas such as spectrum utilization, interoperability, network operations, and radio resource management over a wide range of operating conditions. NASAs cognitive radio will build upon the infrastructure being developed by Space Telecommunication Radio System (STRS) SDR technology. This paper explores the feasibility of inserting cognitive capabilities in the NASA STRS architecture and the interfaces between the cognitive engine and the STRS radio. The STRS architecture defines methods that can inform the cognitive engine about the radio environment so that the cognitive engine can learn autonomously from experience, and take appropriate actions to adapt the radio operating characteristics and optimize performance.

  7. Artificial twin-layer configurations of Zn(O,S) films by radio frequency sputtering in all dry processed eco-friendly Cu(In,Ga)Se2 solar cells

    Science.gov (United States)

    Liu, Wei; Fan, Yu; Li, Xiaodong; Lin, Shuping; Liu, Yang; Shi, Sihan; Wang, He; Zhou, Zhiqiang; Zhang, Yi; Sun, Yun

    2018-03-01

    Cu(In,Ga)Se2 thin film solar cells are of great interest for research and industrial applications with their high conversion efficiencies, long-term stability and significant lifetimes. Such a solar cell of a p-n junction consists of p-type Cu(In,Ga)Se2 films as a light absorber and n-type CdS as a buffer layer, which often emerges with intrinsic ZnO. Aimed at eco-friendly fabrication protocols, a large number of strategies have been investigated to fabricate a Cd-free n-type buffer layer such as Zn(O,S) in Cu(In,Ga)Se2 solar cells. Also, if the Zn(O,S) films are prepared by coevaporation or sputtering, it will offer high compatibility with the preferred mass production. Here, we propose and optimize a dry method for Zn(O,S) deposition in a radio frequency sputtering. In particular, the strategy for the twin-layer configurations of Zn(O,S) films not only greatly improve their electrical conductance and suppress charge carrier recombination, but also avoid degradation of the Zn(O,S)/Cu(In,Ga)Se2 interfaces. Indeed, the high quality of such twin Zn(O,S) layers have been reflected in the similar conversion efficiencies of the complete solar cells as well as the large short-circuit current density, which exceeds the CdS reference device. In addition, Zn(O,S) twin layers have reduced the production time and materials by replacing the CdS/i-ZnO layers, which removes two fabrication steps in the multilayered thin film solar cells. Furthermore, the device physics for such improvements have been fully unveiled with both experimental current-voltage and capacitance-voltage spectroscopies and device simulations via wxAMPS program. Finally, the proposed twin-layer Zn(O,S)/Cu(In,Ga)Se2 interfaces account for the broadening of the depletion region of photogenerated charge carriers, which greatly suppress the carrier recombination at the space charge region, and eventually lead to the more efficient collection of charge carriers at both electrodes.

  8. Frequency agile solar radiotelescope

    Science.gov (United States)

    Bastian, Tim S.

    2003-02-01

    The Frequency Agile Solar Radiotelescope (FASR) is a solar-dedicated, ground based, interferometric array optimized to perform broadband imaging spectroscopy from ~ 0.1-30+ GHz. It will do so with the angular, spectral, and temporal resolution required to exploit radio emission from the Sun as a diagnostic of the wide variety of astrophysical processes that occur there. FASR represents a major advance over existing radioheliographs, and is expected to remain the world's premier solar radio instrument for two decades or more after completion. FASR will be a versatile and powerful instrument, providing unique data to a broad users community. Solar, solar-terrestrial, and space physicists will exploit FASR to attack a broad science program, including problems of fundamental interest: coronal magnetography, solar flares and particle acceleration, drivers of space weather, and the thermal structure and dynamics of the solar atmosphere. A design study and implementation planning are underway. Recent progress is reviewed here.

  9. Radio frequency sputter deposition of high-quality conductive and transparent ZnO:Al films on polymer substrates for thin film solar cells applications

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, S. [Departamento de Energias Renovables, Energia Solar Fotovoltaica, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, 28040 Madrid (Spain)], E-mail: susanamaria.fernandez@ciemat.es; Martinez-Steele, A.; Gandia, J.J. [Departamento de Energias Renovables, Energia Solar Fotovoltaica, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, 28040 Madrid (Spain); Naranjo, F.B. [Grupo de Ingenieria Fotonica (GRIFO), Departamento de Electronica, Escuela Politecnica Superior, Universidad de Alcala. Campus Universitario, 28871 Alcala de Henares, Madrid (Spain)

    2009-03-31

    Thick aluminum-doped zinc oxide films were deposited at substrate temperatures from 100 {sup o}C to room temperature on polyethylene terephthalate by radio frequency magnetron sputtering, varying the deposition parameters such as radio frequency power and working pressure. Structural, optical and electrical properties were analyzed using an x-ray diffractometer, a spectrophotometer and a four-point probe, respectively. Films were polycrystalline showing a strong preferred c-axis orientation (002). The best optical and electrical results were achieved using a substrate temperature of 100 {sup o}C. Furthermore, high transmittances close to 80% in the visible wavelength range were obtained for those films deposited at the lowest Argon pressure used of 0.2 Pa. In addition, resistivities as low as 1.1 x 10{sup -3} {omega} cm were reached deposited at a RF power of 75 W. Finally, a comparison of the properties of the films deposited on polymer and glass substrates was performed, obtaining values of the figure of merit for the films on polymer comparable to those obtained on glass substrates, 17,700 {omega}{sup -1} cm{sup -1} vs 14,900 {omega}{sup -1} cm{sup -1}, respectively.

  10. Radio frequency sputter deposition of high-quality conductive and transparent ZnO:Al films on polymer substrates for thin film solar cells applications

    International Nuclear Information System (INIS)

    Fernandez, S.; Martinez-Steele, A.; Gandia, J.J.; Naranjo, F.B.

    2009-01-01

    Thick aluminum-doped zinc oxide films were deposited at substrate temperatures from 100 o C to room temperature on polyethylene terephthalate by radio frequency magnetron sputtering, varying the deposition parameters such as radio frequency power and working pressure. Structural, optical and electrical properties were analyzed using an x-ray diffractometer, a spectrophotometer and a four-point probe, respectively. Films were polycrystalline showing a strong preferred c-axis orientation (002). The best optical and electrical results were achieved using a substrate temperature of 100 o C. Furthermore, high transmittances close to 80% in the visible wavelength range were obtained for those films deposited at the lowest Argon pressure used of 0.2 Pa. In addition, resistivities as low as 1.1 x 10 -3 Ω cm were reached deposited at a RF power of 75 W. Finally, a comparison of the properties of the films deposited on polymer and glass substrates was performed, obtaining values of the figure of merit for the films on polymer comparable to those obtained on glass substrates, 17,700 Ω -1 cm -1 vs 14,900 Ω -1 cm -1 , respectively

  11. 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)

  12. Solar-Geophysical Data Number 538, June 1989. Part 1 (prompt reports). Data for May, April 1989, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1989-06-01

    Contents include: detailed index for 1988-1989; data for May 1989--(IUWDS alert periods (advance and worldwide), solar activity indices, solar flares, solar radio emission, Stanford mean solar magnetic field); data for April 1989--(solar-active regions, sudden ionospheric disturbances, solar radio-spectral observations, geomagnetic indices, radio-propagation indices); late data--(solar active regions--H-alpha synoptic charts 1813 March 1989, solar radio emission--Nancay 169-Mhz solar interferometric chart April 1989, cosmic rays climax and Huancayo--March 1989, geomagnetic indices-sudden commencements/solar flare effects February 1989)

  13. Observations and global numerical modelling of the St. Patrick's Day 2015 geomagnetic storm event

    Science.gov (United States)

    Foerster, M.; Prokhorov, B. E.; Doornbos, E.; Astafieva, E.; Zakharenkova, I.

    2017-12-01

    With a sudden storm commencement (SSC) at 04:45 UT on St. Patrick's day 2015 started the most severe geomagnetic storm in solar cycle 24. It appeared as a two-stage geomagnetic storm with a minimum SYM-H value of -233 nT. In the response to the storm commencement in the first activation, a short-term positive effect in the ionospheric vertical electron content (VTEC) occurred at low- and mid-latitudes on the dayside. The second phase commencing around 12:30 UT lasted longer and caused significant and complex storm-time changes around the globe with hemispherical different ionospheric storm reactions in different longitudinal ranges. Swarm-C observations of the neutral mass density variation along the orbital path as well as Langmuir probe plasma and magnetometer measurements of all three Swarm satellites and global TEC records are used for physical interpretations and modelling of the positive/negative storm scenario. These observations pose a challenge for the global numerical modelling of thermosphere-ionosphere storm processes as the storm, which occurred around spring equinox, obviously signify the existence of other impact factors than seasonal dependence for hemispheric asymmetries to occur. Numerical simulation trials using the Potsdam version of the Upper Atmosphere Model (UAM-P) are presented to explain these peculiar M-I-T storm processes.

  14. Magnetic storm effect on the occurrence of ionospheric irregularities at an equatorial station in the African sector

    Directory of Open Access Journals (Sweden)

    Olushola Abel Oladipo

    2014-01-01

    Full Text Available Large-scale ionospheric irregularities usually measured by GPS TEC fluctuation indices are regular occurrence at the equatorial region shortly after sunset around solar maximum. Magnetic storm can trigger or inhibit the generation of these irregularities depending on the local time the main phase of a particular storm occurs. We studied the effect of nine (9 distinct storms on the occurrence of ionospheric irregularities at Fraceville in Gabon (Lat = −1.63˚, Long = 13.55˚, dip lat. = −15.94˚, an equatorial station in the African sector. These storms occurred between November 2001 and September 2002. We used TEC fluctuation indices (i.e. ROTI and ROTIAVE estimated from 30 s interval Rinex data and also we used the storm indices (i.e. Dst, dDst/dt, and IMF BZ to predict the likely effect of each storm on the irregularities occurrence at this station. The results obtained showed that most of the storms studied inhibited ionospheric irregularities. Only one out of all the storms studied (i.e. September 4, 2002 storms with the main phase on the night of September 7-8 triggered post-midnight ionospheric irregularities. There are two of the storms during which ionospheric irregularities were observed. However, these may not be solely attributed to the storms event because the level of irregularities observed during these two storms is comparable to that observed during previous days before the storms. For this station and for the storms investigated, it seems like a little modification to the use of Aarons categories in terms of the local time the maximum negative Dst occurs could lead to a better prediction. However, it would require investigating many storms during different level of solar activities and at different latitudes to generalize this modification.

  15. Relative outflow enhancements during major geomagnetic storms – Cluster observations

    Directory of Open Access Journals (Sweden)

    A. Schillings

    2017-12-01

    Full Text Available The rate of ion outflow from the polar ionosphere is known to vary by orders of magnitude, depending on the geomagnetic activity. However, the upper limit of the outflow rate during the largest geomagnetic storms is not well constrained due to poor spatial coverage during storm events. In this paper, we analyse six major geomagnetic storms between 2001 and 2004 using Cluster data. The six major storms fulfil the criteria of Dst  < −100 nT or Kp  > 7+. Since the shape of the magnetospheric regions (plasma mantle, lobe and inner magnetosphere are distorted during large magnetic storms, we use both plasma beta (β and ion characteristics to define a spatial box where the upward O+ flux scaled to an ionospheric reference altitude for the extreme event is observed. The relative enhancement of the scaled outflow in the spatial boxes as compared to the data from the full year when the storm occurred is estimated. Only O+ data were used because H+ may have a solar wind origin. The storm time data for most cases showed up as a clearly distinguishable separate peak in the distribution toward the largest fluxes observed. The relative enhancement in the outflow region during storm time is 1 to 2 orders of magnitude higher compared to less disturbed time. The largest relative scaled outflow enhancement is 83 (7 November 2004 and the highest scaled O+ outflow observed is 2  ×  1014 m−2 s−1 (29 October 2003.

  16. Storm Warnings for Cuba

    Science.gov (United States)

    1994-01-01

    Services: Telephone: (310) 451-7002; Fax: (310) 451-6915; Internet : order@rand.org. al Accesion For "Ni %&’ Storm WarningsDTI’ TAB E03 --- - - -for...reaction leading to an uncontrol- lable burgeoning of private entrepreneurial activity. As one observer 14See Acuerdo del Buro Politico , "Para llevar a...34 10Comisi6n de Relaciones Internacionales, Asamblea Nacional del Poder Popular, Datos, Reflexiones y Argumentos Sobre la Actual Situaci6n de Cuba, n.p

  17. The women day storm

    OpenAIRE

    Parnowski, Aleksei; Polonska, Anna; Semeniv, Oleg

    2012-01-01

    On behalf of the International Women Day, the Sun gave a hot kiss to our mother Earth in a form of a full halo CME generated by the yesterday's double X-class flare. The resulting geomagnetic storm gives a good opportunity to compare the performance of space weather forecast models operating in near-real-time. We compare the forecasts of most major models and identify some common problems. We also present the results of our own near-real-time forecast models.

  18. The Origin of Powerful Radio Sources

    Science.gov (United States)

    Wilson, A. S.; Colbert, E. J. M.

    1995-05-01

    Radio-loud active galaxies are associated with elliptical or elliptical-like galaxies, many of which appear to be the result of a recent merger. In contrast, radio-quiet active galaxies prefer spiral hosts. Despite the very large difference in radio luminosities between the two classes, their continua and line spectra from infrared through X-ray frequencies are very similar. In this paper, we describe recent developments of our model (Ap. J. 438, 62 1995) in which the radio-loud phenomenon is the result of a merger of two galaxies, with each galaxy nucleus containing a slowly (or non-) rotating supermassive black hole. It is envisaged that the two black holes eventually coalesce. For the small fraction of mergers in which the two holes are both massive and of comparable mass, a rapidly-spinning, high-mass hole results. The spin energy of a rapidly rotating 10(8-9) solar mass hole suffices to provide the ~ 10(60) ergs in relativistic particles and magnetic fields in the most energetic radio sources. Luminous radio-quiet active galaxies contain high-mass, slowly-rotating holes, with the infrared through X-ray emission of both classes being fuelled by accretion as commonly assumed. We discuss constraints on the model from the luminosity functions of radio-loud and radio-quiet galaxies and from the known cosmological evolution of the radio source population; this evolution is assumed to reflect higher galaxy merger rates in the past.

  19. Solar-geophysical data number 417, May 1979. Part II. Data for November 1978--October 1978 and miscellanea

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1979-05-01

    This comprehensive report provides data for November 1978 on active regions, synoptic solar maps, solar flares, solar radio emission, energetic solar particles and plasma, and solar x-ray radiation. It also provides synoptic charts, abbreviated calendar record and regional flare index for October 1978. The miscellaneous data includes solar radio emission for January and February 1979 and cosmic rays for February 1979

  20. Comparative study about Al-doped zinc oxide thin films deposited by Pulsed Electron Deposition and Radio Frequency Magnetron Sputtering as Transparent Conductive Oxide for Cu(In,Ga)Se{sub 2}-based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Pattini, F., E-mail: pattini@imem.cnr.it [IMEM-CNR, Institute of Materials for Electronics and Magnetism, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Annoni, F.; Bissoli, F.; Bronzoni, M. [IMEM-CNR, Institute of Materials for Electronics and Magnetism, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Garcia, J.P. [Delft University of Technology, Faculty of Applied Sciences, Delft Product and Process Design Institute, Julianalaan 67, 2628 BC Delft (Netherlands); Gilioli, E.; Rampino, S. [IMEM-CNR, Institute of Materials for Electronics and Magnetism, Parco Area delle Scienze 37/A, 43124 Parma (Italy)

    2015-05-01

    In this study, a comparison between Al-doped ZnO (AZO) as Transparent Conductive Oxide for Cu(In,Ga)Se{sub 2}-based solar cells grown by Pulsed Electron Deposition (PED) and Radio Frequency Magnetron Sputtering (RFMS) was performed. PED yielded polycrystalline [002] mono-oriented thin films with low electrical resistivity and high optical transparency with heater temperatures ranging from room temperature (RT) to 250 °C. The electrical resistivity of these films can be tuned by varying the heater temperature, reaching a minimum value of 3.5 × 10{sup −4} Ωcm at 150 °C and an average transmittance over 90% in the visible range. An AZO film grown at RT was deposited by PED on an actual Cu(In,Ga)Se{sub 2}-based solar cell, resulting to an efficiency value of 15.2% on the best device. This result clearly shows that PED is a suitable technique for growing ZnO-based thin films for devices/applications where low deposition temperature is required. On the other hand, an optimized AZO thin film front contact for thin film solar cells was studied and fabricated via RFMS. The parameters of this technique were tweaked to obtain highly conductive and transparent AZO thin films. The lowest resistivity value of 3.7 × 10{sup −4} Ωcm and an average transmittance of 86% in the 400-1100 nm wavelength range was obtained with a heater temperature of 250 °C. A thick sputtered AZO film was deposited at RT onto an identical cell used for PED-grown AZO, reaching the highest conversion efficiency value of 14.7%. In both cases, neither antireflection coatings nor pure ZnO layer was used. - Highlights: • Pulsed Electron Deposition (PED) lets high quality films grow at low temperature. • Al:ZnO (AZO) thin films grown by PED present high optical and electrical quality. • AZO electrical resistivity can be tuned from 10{sup −4} to 10{sup −2} Ωcm in proper condition. • Cu(In,Ga)Se{sub 2}-based simplified solar cells achieved efficiency of 15.2% for PED-grown AZO.

  1. Solar--geophysical data number 372. Part I (prompt reports). Data for June 1975--July 1975. Explanation of data reports issued as number 366 (supplement) February 1975

    International Nuclear Information System (INIS)

    Leighton, H.I.

    1975-08-01

    This is Part 1 (Prompt reports) of Solar--Geophysical Data for July 1975 and June 1975. The July 1975 Data include sections on Alert Period, Daily Solar Indices, Solar Flares, Solar Radio Waves, Solar Wind Measurements, Spacecraft Observations, Solar X-ray Radiation, and Inferred IP Magnetic Field Polarities. The June 1975 Data includes sections on Daily Solar Activity Centers, Sudden Ionospheric Disturbances, Solar Radio Waves, Cosmic Waves, Geomagnetic Indices, and Radio Propagation Indices

  2. Solar--geophysical data number 378. Part I. (Prompt reports). Data for January 1976--December 1975. Explanation of data reports issued as number 366 (supplement) February 1975

    International Nuclear Information System (INIS)

    Leighton, H.I.

    1976-02-01

    The January 1976 data for Solar--Geophysical Data, prompt reports for January 1976--December 1975, Part 1, include sections on alert period, daily solar indices, solar flares, solar radio waves, solar wind measurement, spacecraft observations, solar x radiation, coronal holes, and inferred IP magnetic field polarities. The December 1975 data include daily solar activity centers, sudden ionospheric disturbances, solar radio waves, cosmic rays, geomagnetic indices, and radio propagation indices

  3. Solar--geophysical data number 375. Part I (prompt reports). Data for October 1975--September 1975. Explanation of data reports issued as number 366 (supplement) February 1975

    International Nuclear Information System (INIS)

    Leighton, H.I.

    1975-11-01

    This is Part I, Prompt reports, of Solar--Geophysical Data for October 1975 and September 1975. The October 1975 data includes sections on alert period, daily solar indices, solar flares, solar radio waves, solar wind measurements, spacecraft observations, solar x-ray radiation, and inferred IP magnetic polarities. The September 1975 data includes sections on daily solar activity centers, sudden ionospheric disturbances, solar radio waves, cosmic rays, geomagnetic indices, and radio propagation indices

  4. Solar-Geophysical Data Number 553, September 1990. Part 1 (prompt reports). Data for August 1990, July 1990 and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1990-09-01

    ;Contents: Detailed index for 1990; Data for August 1990--Solar-terrestrial environment, IUWDS alert periods (Advance and Worldwide), Solar activity indices, Solar flares, Solar radio emission, Standford mean solar magnetic field; Data for July 1990--Solar active regions, Sudden ionospheric disturbances, Solar radio spectral observations, Cosmic ray measurements by neutron monitor, Geomagnetic indices; Late data--Solar radio spectral Bleien and Ondrejov Jun 90, Cosmic ray Huancayo Jun 90, Geomagnetic activity indices May-Jun 90

  5. Influence of storm characteristics on soil erosion and storm runoff

    Science.gov (United States)

    Johnny M. III Grace

    2008-01-01

    Unpaved forest roads can be major sources of sediment from forested watersheds. Storm runoff from forest roads are a concern due to their potential delivery of sediments and nutrients to stream systems resulting in degraded water quality. The volume and sediment concentrations of stormwater runoff emanating from forest roads can be greatly influenced by storm...

  6. Magnetic storms and variations in hormone levels among residents of North Polar area - Svalbard

    Science.gov (United States)

    Breus, Tamara; Zenchenko, Tatiana; Boiko, Evgeni

    It was previously shown that magnetic storms lead to an increase in the level of cortisol and noradrenalin in healthy and sick people with cardiovascular diseases [Breus Rapoport. 2003]. However, in the healthy group in the cited study was only 4 people and it seemed that these results need to be checked. In the present work the 4 examinations (January, March, June, October) of large groups of healthy inhabitants of high latitudes (Svalbard, the most northerly in the world year-round inhabited settlements) on the blood levels of adrenal hormones (cortisol) and thyroid hormones (triiodothyronine (T3 ) and thyroxine T4) have been done. The aim was to study the possible sensitivity of these biochemical parameters in three independent groups of people living in this region (men working underground (364 samples), the men working on the ground (274 samples) and women (280 samples)) to variations in external natural factors of high latitudes. For the analysis we used the following parameters of space and terrestrial weather :index of intensity of solar radio emission at a wavelength 10.7sm (RF10.7), planetary geomagnetic activity index - daily Kp index ( Kp) , the daily average Ap index ( Ap) , the maximum per every 3 -hour Kp index ) as well as the daily average indicators of flow rate of galactic cosmic rays neutron component (N), atmospheric pressure ( RATM ) and its rate of change ( the difference between the Ratm today and yesterday ) according to the geophysical station Oulu (Finland , http://cosmicrays.oulu.fi/). The obtained data indicate that the most expressed dependence of the level of studied three hormones is from the level of geomagnetic activity (GMA)-Kp, Ap, Kpmax - 3h. For two of the four seasons (June and October) with increasing levels of GMA a significant (p stress reaction in reply on GMA disturbance. 1. Breus T.K. and Rapoport S.I. Magnetic storms. Medico- biological aspects (in Russian), Publ.Co Soviet Sport,.Moscow, 2003, 271p.

  7. The Application of an Online Data Visualization Tool, Ptplot, in the World Data Center (WDC for Solar-Terrestrial Science (STS in IPS Radio and Space Services, Australia

    Directory of Open Access Journals (Sweden)

    K Wang

    2013-02-01

    Full Text Available Ptplot is a set of two dimensional signal plotters components written in Java with multiple properties, such as being embeddable in applets or applications, utilizing automatic or manual tick marks, logarithmic axes, infinite zooming, and much more. The World Data Centre of IPS applies Ptplot as a multiple function online data plot tool by converting various text format data files into Ptplot recognizable XML files with the AWK language. At present, Ptplot has allowed eight archived solar-terrestrial science data sets to be easily plotted, viewed, and downloaded from the IPS web site.

  8. Corruption of radio metric Doppler due to solar plasma dynamics: S/X dual-frequency Doppler calibration for these effects

    Science.gov (United States)

    Winn, F. B.; Reinbold, S. R.; Yip, K. W.; Koch, R. E.; Lubeley, A.

    1975-01-01

    Doppler data from Mariner 6, 7, 9, and 10 and Pioneer 10 and 11 were discussed and the rms noise level for various sun-earth-probe angles were shown. The noise levels of both S- and X-band Doppler data for sun-earth-probe angles smaller than 20 deg were observed to be orders of magnitude greater than nominal. Such solar plasma-related Doppler degradation reduced the Mariner 10-Mercury 11 encounter navigation accuracy by nearly a factor of 10. Furthermore, this degradation was shown to be indirectly related to plasma dynamics and not a direct measure of the dynamics.

  9. The radio universe

    International Nuclear Information System (INIS)

    Worvill, R.

    1977-01-01

    Elementary description of the development of radioastronomy, radio waves from the sun and planets, the use of radio telescopes and the detection of nebulae, supernova, radio galaxies and quasars is presented. A brief glossary of terms is included. (UK)

  10. Wind in the Solar System

    Science.gov (United States)

    McIntosh, Gordon

    2010-01-01

    As an astronomy instructor I am always looking for commonly experienced Earthly phenomena to help my students and me understand and appreciate similar occurrences elsewhere in the solar system. Recently I wrote short "TPT" articles on frost and precipitation. The present article is on winds in the solar system. A windy day or storm might…

  11. Analysis of the Relationship Between the Solar X-Ray Radiation Intensity and the D-Region Electron Density Using Satellite and Ground-Based Radio Data

    Science.gov (United States)

    Nina, Aleksandra; Čadež, Vladimir M.; Bajčetić, Jovan; Mitrović, Srdjan T.; Popović, Luka Č.

    2018-04-01

    Increases in the X-ray radiation that is emitted during a solar X-ray flare induce significant changes in the ionospheric D region. Because of the numerous complex processes in the ionosphere and the characteristics of the radiation and plasma, the causal-consequential relationship between the X-ray radiation and ionospheric parameters is not easily determined. In addition, modeling the ionospheric D-region plasma parameters is very difficult because of the lack of data for numerous time- and space-dependent physical quantities. In this article we first give a qualitative analysis of the relationship between the electron density and the recorded solar X-ray intensity. After this, we analyze the differences in the relationships between the D-region response and various X-ray radiation properties. The quantitative study is performed for data observed on 5 May 2010 in the time period between 11:40 UT - 12:40 UT when the GOES 14 satellite detected a considerable X-ray intensity increase. Modeling the electron density is based on characteristics of the 23.4 kHz signal emitted in Germany and recorded by the receiver in Serbia.

  12. Magnetospheric storm dynamics in terms of energy output rate

    International Nuclear Information System (INIS)

    Prigancova, A.; Feldstein, Ya.I.

    1992-01-01

    Using hourly values of both the global magnetospheric disturbance characteristic DR, and AE index of auroral ionospheric currents during magnetic storm intervals, the energy output rate dynamics is evaluated for a magnetic storm main/recovery phase and a whole storm interval. The magnetospheric response to the solar wind energy input rate under varying interplanetary and magnetospheric conditions is considered from the temporal variability point of view. The peculiarities of the response are traced separately. As far as quantitative characteristics of energy output rate are concerned, the time dependence pattern of the ring current decay parameter is emphasized to be fairly important. It is pointed out that more insight into the plasma processes, especially at L = 3 - 5, is needed for adequate evidence of the dependence. (Author)

  13. Optimization of aluminum-doped zinc oxide films deposited at low temperature by radio-frequency sputtering on flexible substrates for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, S. [Departamento de Energias Renovables, Energia Solar Fotovoltaica, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, 28040 Madrid (Spain); Naranjo, F.B. [Grupo de Ingenieria Fotonica (GRIFO), Departamento de Electronica, Escuela Politecnica Superior, Universidad de Alcala, Campus Universitario, 28871 Alcala de Henares, Madrid (Spain)

    2010-02-15

    Aluminum-doped zinc oxide films were deposited at 100 C on polyethylene terephthalate by radio-frequency magnetron sputtering. The sputtering parameters such as RF power and Argon working pressure were varied from 25 to 125 W and from 1.1 to 0.2 Pa, respectively. The structural properties of as-deposited films were analysed by X-ray diffraction, showing that all the deposited films were polycrystalline, with hexagonal structure and a strong preferred c-axis orientation (0 0 2). Full width at half maximum and grain sizes were around 0.27 and ranged from 24 to 32 nm, respectively. The strain state of the samples was also estimated from X-ray diffraction measurements, obtaining compressive stresses from 0.29 to 0.05 GPa. Resistivity as low as 1.1 x 10{sup -3} {omega} cm was achieved for the film deposited at 75 W and 0.2 Pa, sample that showed a low strain state of -0.06 GPa. High optical transmittance ({proportional_to}80%) was exhibited when films were deposited at RF powers below 100 W. Band gap energies ranged from 3.36 to 3.39 eV and a refractive index of 1.80{+-}0.05, constant in the visible region, was also obtained. (author)

  14. Controlling of merging electric field and IMF magnitude on storm-time changes in thermospheric mass density

    NARCIS (Netherlands)

    Zhou, Y.L.; Ma, S.Y.; Liu, R.S.; Luehr, H.; Doornbos, E.

    2013-01-01

    The controls of merging electrical field, Em, and IMF (interplanetary magnetic field) magnitude, B, on the storm-time changes in upper thermospheric mass density are statistically investigated using GRACE accelerometer observations and the OMNI data of solar wind and IMF for 35 great storms during

  15. Solar-geophysical data number 586, June 1993. Part 1 (prompt reports). Data for May, April 1993, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1993-06-01

    Contents: data for may 1993; solar-terrestrial environment; iuwds alert periods (advance and worldwide); solar activity indices; solar flares; solar radio emission; stanford mean solar magnetic field; data for april 1993; solar active regions; sudden ionospheric disturbances; solar radio spectral observations; solar radioheliograph; cosmic ray measurements by neutron monitor; geomagnetic indices. This research is relevant to studies in atmospheric/environmental science, solar energy, plasma physics, and communications

  16. Solar-geophysical data number 587, July 1993. Part 1 (prompt reports). data for June, May 1993, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1993-07-01

    Contents: data for june 1993; solar-terrestrial environment; iuwds alert periods (advance and worldwide); solar activity indices; solar flares; solar radio emission; stanford mean solar magnetic field; data for may 1993; solar active regions; sudden ionospheric disturbances; solar radio spectral observations; solar radioheliograph - 164 mhz - nancay; cosmic ray measurements by neutron monitor; geomagnetic indices. This research is applicable to research in solar energy, plasma physics, communications, and environmental science

  17. Magnetic storms on Mars

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne

    2011-01-01

    and typical time profile of such periods is investigated and compared to solar wind measurements at Earth. Typical durations of the events are 20–40h, and there is a tendency for large events to last longer, but a large spread in duration and intensity are found. The large and medium intensity events at Mars......Based on data from the Mars Global Surveyor magnetometer we examine periods of significantly enhanced magnetic disturbances in the martian space environment. Using almost seven years of observations during the maximum and early declining phase of the previous solar cycle the occurrence pattern...... are found to occur predominantly in association with interplanetary sector boundaries, with solar wind dynamic pressure enhancements being the most likely interplanetary driver. In addition it is found that, on time scales of months to several years, the dominant cause of global variability of the magnetic...

  18. Relationship between substorms and storms

    International Nuclear Information System (INIS)

    Kamide, Y.

    1980-01-01

    In an attempt to deduce a plausible working model of the relationship between magnetospheric substorms and storms, recent relevant studies of various processes occurring during disturbed periods are integrated along with some theoretical suggestions. It has been shown that the main phase of geomagnetic storms is associated with the successive occurrence of intense substorms and with the sustained southward component of the interplanetary magnetic field (IMF). However, these relations are only qualitatively understood, and thus basic questions remain unanswered involving the hypothesis whether a magnetic storm is a non-linear (or linear) superposition of intense substorms, each of which constitutes an elementary storm, or the main phase of magnetic storms occurs as a result of the intense southward IMF which enhances magnetospheric convection and increases occurrence probability of substorms. (Auth.)

  19. Thyroid storm: an updated review.

    Science.gov (United States)

    Chiha, Maguy; Samarasinghe, Shanika; Kabaker, Adam S

    2015-03-01

    Thyroid storm, an endocrine emergency first described in 1926, remains a diagnostic and therapeutic challenge. No laboratory abnormalities are specific to thyroid storm, and the available scoring system is based on the clinical criteria. The exact mechanisms underlying the development of thyroid storm from uncomplicated hyperthyroidism are not well understood. A heightened response to thyroid hormone is often incriminated along with increased or abrupt availability of free hormones. Patients exhibit exaggerated signs and symptoms of hyperthyroidism and varying degrees of organ decompensation. Treatment should be initiated promptly targeting all steps of thyroid hormone formation, release, and action. Patients who fail medical therapy should be treated with therapeutic plasma exchange or thyroidectomy. The mortality of thyroid storm is currently reported at 10%. Patients who have survived thyroid storm should receive definite therapy for their underlying hyperthyroidism to avoid any recurrence of this potentially fatal condition. © The Author(s) 2013.

  20. Geomagnetic response to solar and interplanetary disturbances

    Directory of Open Access Journals (Sweden)

    Maris Georgeta

    2013-07-01

    Full Text Available The space weather discipline involves different physical scenarios, which are characterised by very different physical conditions, ranging from the Sun to the terrestrial magnetosphere and ionosphere. Thanks to the great modelling effort made during the last years, a few Sun-to-ionosphere/thermosphere physics-based numerical codes have been developed. However, the success of the prediction is still far from achieving the desirable results and much more progress is needed. Some aspects involved in this progress concern both the technical progress (developing and validating tools to forecast, selecting the optimal parameters as inputs for the tools, improving accuracy in prediction with short lead time, etc. and the scientific development, i.e., deeper understanding of the energy transfer process from the solar wind to the coupled magnetosphere-ionosphere-thermosphere system. The purpose of this paper is to collect the most relevant results related to these topics obtained during the COST Action ES0803. In an end-to-end forecasting scheme that uses an artificial neural network, we show that the forecasting results improve when gathering certain parameters, such as X-ray solar flares, Type II and/or Type IV radio emission and solar energetic particles enhancements as inputs for the algorithm. Regarding the solar wind-magnetosphere-ionosphere interaction topic, the geomagnetic responses at high and low latitudes are considered separately. At low latitudes, we present new insights into temporal evolution of the ring current, as seen by Burton’s equation, in both main and recovery phases of the storm. At high latitudes, the PCC index appears as an achievement in modelling the coupling between the upper atmosphere and the solar wind, with a great potential for forecasting purposes. We also address the important role of small-scale field-aligned currents in Joule heating of the ionosphere even under non-disturbed conditions. Our scientific results in

  1. Cosmic noise: a history of early radio astronomy

    National Research Council Canada - National Science Library

    Sullivan, Woodruff Turner

    2009-01-01

    .... The whole of worldwide radio and radar astronomy is covered, beginning with the discoveries by Jansky and Reber of cosmic noise before World War II, through the wartime detections of solar noise...

  2. Near Earth space sporadic radio emission busts occurring during sunrise

    Science.gov (United States)

    Dudnik, A. V.; Zaljubovsky, I. I.; Kartashev, V. M.; Lasarev, A. V.; Shmatko, E. S.

    1985-01-01

    During the period of low solar activity at sunrise the effect of sporadic high frequency near Earth space radio emission was experimentally discovered at middle latitudes. The possible mechanism of its origin is discussed.

  3. 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.

  4. Mars atmospheric phenomena during major dust storms, as measured at surface

    International Nuclear Information System (INIS)

    Ryan, J.A.; Henry, R.M.

    1979-01-01

    Meteorological instrumentation aboard the Viking Mars Landers measures wind, temperature, and pressure. Two global dust storms occurred during northern autumn and winter, observed both by the orbiters and by the landers. The meteorological data from the landers has been analyzed for the period just before first storm arrival to just after second storm arrival, with the objectives being definition of meteorological phenomena during the storm period, determination of those associated with storm and dust arrival, and evaluation of effects on synoptic conditions and the general circulation. Times of dust arrival over the sites could be defined fairly closely from optical and pressure (solar tide) data, and dust arrival was also accompanied by changes in diurnal temperature range, temperature maxima, and temperature minima. The arrivals of the storms at VL-1 were accompanied by significant increase in wind speed and pressure. No such changes were observed at VL-2. It is possible that surface material could have been raised locally at VL-1. Throughout the period except following the second dust storm synoptic picture at VL-2 was one of eastward moving cyclonic and anticyclonic systems. These disappeared following the second storm, a phenomenon which may be related to the storm

  5. The detectability of radio emission from exoplanets

    Science.gov (United States)

    Lynch, C. R.; Murphy, Tara; Lenc, E.; Kaplan, D. L.

    2018-05-01

    Like the magnetised planets in our Solar System, magnetised exoplanets should emit strongly at radio wavelengths. Radio emission directly traces the planetary magnetic fields and radio detections can place constraints on the physical parameters of these features. Large comparative studies of predicted radio emission characteristics for the known population of exoplanets help to identify what physical parameters could be key for producing bright, observable radio emission. Since the last comparative study, many thousands of exoplanets have been discovered. We report new estimates for the radio flux densities and maximum emission frequencies for the current population of known exoplanets orbiting pre-main sequence and main-sequence stars with spectral types F-M. The set of exoplanets predicted to produce observable radio emission are Hot Jupiters orbiting young stars. The youth of these system predicts strong stellar magnetic fields and/or dense winds, which are key for producing bright, observable radio emission. We use a new all-sky circular polarisation Murchison Widefield Array survey to place sensitive limits on 200 MHz emission from exoplanets, with 3σ values ranging from 4.0 - 45.0 mJy. Using a targeted Giant Metre Wave Radio Telescope observing campaign, we also report a 3σ upper limit of 4.5 mJy on the radio emission from V830 Tau b, the first Hot Jupiter to be discovered orbiting a pre-main sequence star. Our limit is the first to be reported for the low-frequency radio emission from this source.

  6. 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....

  7. Thromboembolic complications of thyroid storm.

    Science.gov (United States)

    Min, T; Benjamin, S; Cozma, L

    2014-01-01

    Thyroid storm is a rare but potentially life-threatening complication of hyperthyroidism. Early recognition and prompt treatment are essential. Atrial fibrillation can occur in up to 40% of patients with thyroid storm. Studies have shown that hyperthyroidism increases the risk of thromboembolic events. There is no consensus with regard to the initiation of anticoagulation for atrial fibrillation in severe thyrotoxicosis. Anticoagulation is not routinely initiated if the risk is low on a CHADS2 score; however, this should be considered in patients with thyroid storm or severe thyrotoxicosis with impending storm irrespective of the CHADS2 risk, as it appears to increase the risk of thromboembolic episodes. Herein, we describe a case of thyroid storm complicated by massive pulmonary embolism. Diagnosis of thyroid storm is based on clinical findings. Early recognition and prompt treatment could lead to a favourable outcome.Hypercoagulable state is a recognised complication of thyrotoxicosis.Atrial fibrillation is strongly associated with hyperthyroidism and thyroid storm.Anticoagulation should be considered for patients with severe thyrotoxicosis and atrial fibrillation irrespective of the CHADS2 score.Patients with severe thyrotoxicosis and clinical evidence of thrombosis should be immediately anticoagulated until hyperthyroidism is under control.

  8. Statistical Analysis of Solar Events Associated with SSC over Year of Solar Maximum during Cycle 23: 1. Identification of Related Sun-Earth Events

    Science.gov (United States)

    Grison, B.; Bocchialini, K.; Menvielle, M.; Chambodut, A.; Cornilleau-Wehrlin, N.; Fontaine, D.; Marchaudon, A.; Pick, M.; Pitout, F.; Schmieder, B.; Regnier, S.; Zouganelis, Y.

    2017-12-01

    Taking the 32 sudden storm commencements (SSC) listed by the observatory de l'Ebre / ISGI over the year 2002 (maximal solar activity) as a starting point, we performed a statistical analysis of the related solar sources, solar wind signatures, and terrestrial responses. For each event, we characterized and identified, as far as possible, (i) the sources on the Sun (Coronal Mass Ejections -CME-), with the help of a series of herafter detailed criteria (velocities, drag coefficient, radio waves, polarity), as well as (ii) the structure and properties in the interplanetary medium, at L1, of the event associated to the SSC: magnetic clouds -MC-, non-MC interplanetary coronal mass ejections -ICME-, co-rotating/stream interaction regions -SIR/CIR-, shocks only and unclear events that we call "miscellaneous" events. The categorization of the events at L1 is made on published catalogues. For each potential CME/L1 event association we compare the velocity observed at L1 with the one observed at the Sun and the estimated balistic velocity. Observations of radio emissions (Type II, Type IV detected from the ground and /or by WIND) associated to the CMEs make the solar source more probable. We also compare the polarity of the magnetic clouds with the hemisphere of the solar source. The drag coefficient (estimated with the drag-based model) is calculated for each potential association and it is compared to the expected range values. We identified a solar source for 26 SSC related events. 12 of these 26 associations match all criteria. We finally discuss the difficulty to perform such associations.

  9. Detection of Propagating Fast Sausage Waves through a Detailed Analysis of a Zebra Pattern Fine Structure in a Solar Radio Burst

    Science.gov (United States)

    Kaneda, K.; Misawa, H.; Iwai, K.; Masuda, S.; Tsuchiya, F.; Katoh, Y.; Obara, T.

    2017-12-01

    Recent observations have revealed that various modes of magnetohydrodynamic (MHD) waves are ubiquitous in the corona. In imaging observations in EUV, propagating fast magnetoacoustic waves are difficult to observe due to the lack of time resolution. Quasi-periodic modulation of radio fine structures is an important source of information on these MHD waves. Zebra patterns (ZPs) are one of such fine structures in type IV bursts, which consist of several parallel stripes superimposed on the background continuum. Although the generation mechanism of ZPs has been discussed still, the most favorable model of ZPs is so-called double plasma resonance (DPR) model. In the DPR model, the frequency separation between the adjacent stripes (Δf) is determined by the plasma density and magnetic field in their source. Hence, the variation of Δf in time and frequency represents the disturbance in their source region in the corona. We report the detection of propagating fast sausage waves through the analysis of a ZP event on 2011 June 21. The variation of Δf in time and frequency was obtained using highly resolved spectral data from the Assembly of Metric-band Aperture Telescope and Real-time Analysis System (AMATERAS). We found that Δf increases with the increase of emission frequency as a whole, which is consistent with the DPR model. Furthermore, we also found that irregularities in Δf are repetitively drifting from the high frequency side to the low frequency side. Their frequency drift rate was 3 - 8 MHz/s and the repetitive frequency was several seconds. Assuming the ZP generation by the DPR model, the drifting irregularities in Δf correspond to propagating disturbances in plasma density and magnetic field with speeds of 3000 - 8000 km/s. Taking account of these facts, the observed modulations in Δf can be explained by fast sausage waves propagating through the corona. We will also discuss the plasma conditions in the corona estimated from the observational results.

  10. Geomagnetic storms and electric fields in the equatorial ionosphere

    International Nuclear Information System (INIS)

    Rastogi, R.G.

    1977-01-01

    Using direct measurements of equatorial electric field during a geomagnetic storm it is shown that the large decrease in the field observed near the dip equator is due to the reversal of the equatorial electrojet current. This is caused by the imposition of an additional westward electric field on the equatorial ionosphere which was originated by the interaction of solar wind with the interplanetary magnetic field. (author)

  11. Mathematical models of some geomagnetic storms with SC

    International Nuclear Information System (INIS)

    Ivanova, P.K.

    1990-01-01

    Regressive equations for H horizontal component of three geomagnetic storms with Sc:0.1.03.82, 24.01.74 and 23.03.69 -are calculated using step-by-step regression analysis. These equations relate H with parameters of solar wind and interplanetary magnetic field. Nonlinear, square, logarithmic and trigonometric dependences are considered, as well. Most essential parameters, which contribute mostly into Sc, are determined from multiplicity (46 factors) of independent parameters

  12. Deep Space Storm Shelter Simulation Study

    Science.gov (United States)

    Dugan, Kathryn; Phojanamongkolkij, Nipa; Cerro, Jeffrey; Simon, Matthew

    2015-01-01

    Missions outside of Earth's magnetic field are impeded by the presence of radiation from galactic cosmic rays and solar particle events. To overcome this issue, NASA's Advanced Exploration Systems Radiation Works Storm Shelter (RadWorks) has been studying different radiation protective habitats to shield against the onset of solar particle event radiation. These habitats have the capability of protecting occupants by utilizing available materials such as food, water, brine, human waste, trash, and non-consumables to build short-term shelters. Protection comes from building a barrier with the materials that dampens the impact of the radiation on astronauts. The goal of this study is to develop a discrete event simulation, modeling a solar particle event and the building of a protective shelter. The main hallway location within a larger habitat similar to the International Space Station (ISS) is analyzed. The outputs from this model are: 1) the total area covered on the shelter by the different materials, 2) the amount of radiation the crew members receive, and 3) the amount of time for setting up the habitat during specific points in a mission given an event occurs.

  13. AMPTE/CCE observations of the plasma composition below 17 keV during the September 4, 1984 magnetic storm

    International Nuclear Information System (INIS)

    Shelley, E.G.; Klumpar, D.M.; Peterson, W.K.; Ghielmetti, A.; Balsiger, H.; Geiss, J.; Rosenbauer, H.; Bern Universitaet, Switzerland; Max-Planck-Institut fuer Aeronomie, Katlenburg, West Germany)

    1985-01-01

    Observations from the Hot Plasma Composition Experiment on the AMPTE/CCE spacecraft during the magnetic storm of 4-5 September 1984 reveal that significant injection of ions of terrestrial origin accompanied the storm development. The compression of the magnetosphere at storm sudden commencement carried the magnetopause inside the CCE orbit clearly revealing the shocked solar wind plasma. A build up of suprathermal ions is observed near the plasmapause during the storm main phase and recovery phase. Pitch angle distributions in the ring current during the main phase show differences between H(+) and O(+) that suggest mass dependent injection, transport and/or loss processes. 9 references

  14. Radio Ranging Techniques to test Relativistic Gravitation

    OpenAIRE

    Cowsik, R.

    1999-01-01

    It is suggested that modern techniques of radio ranging when applied to study the motion of the Moon, can improve the accuracy of tests of relativistic gravitation obtained with currently operating laser ranging techniques. Other auxillary information relevant to the Solar system would also emerge from such a study.

  15. The effect of magnetic storm on the bottomside profile parameters B0 and

    International Nuclear Information System (INIS)

    Adeniyi, J.O.; Radicella, S.M.

    2001-01-01

    We have used data from an equatorial station for the investigation of magnetic storm effects on B0 and B1. Three storm events, which occurred in January, April and October of a low solar activity year (1995), were used for the study. B0 is the parameter that is mostly affected and the effect is concentrated on the daytime period (0700-1700LT). (author)

  16. Thyroid storm causing placental abruption: Cardiovascular and management complications for the Intensivist.

    Science.gov (United States)

    Lane, Andrew S; Tarvade, Sanjay

    2015-08-01

    Thyroid storm is a rare and serious complication of pregnancy which can lead to spontaneous abortion, preterm delivery, preeclampsia and cardiac failure. It is also associated with high maternal and foetal mortality if not diagnosed and managed promptly. The diagnosis of thyroid storm in pregnancy can pose significant challenges due to its presentation being similar to other pregnancy-related complications. We present a patient who developed thyroid storm at 29 weeks of pregnancy, which resulted in pre-term delivery, cardiac failure and thyroidectomy. We discuss the treatment of thyroid storm in pregnancy, the decision making involved in proceeding to thyroidectomy or to use radio-iodine, and foetal thyroid status in thyrotoxicosis.

  17. Affirmation of triggered Jovian radio emissions and their attribution to corotating radio lasers

    Science.gov (United States)

    Calvert, W.

    1985-01-01

    It is argued that the original statistical evidence for the existence of triggered radio emissions and corotating radio lasers on Jupiter remains valid notwithstanding the critique of Desch and Kaiser (1985). The Voyager radio spectrograms used to identify the triggered emissions are analyzed and the results are discussed. It is shown that the critique by Desch and Kaiser is unjustified because it is not based on the original event criteria, i.e., the correlation between the occurrence of Jovian auroral kilometric radiation and fast-drift type III solar bursts in the same frequency.

  18. US Weather Bureau Storm Reports

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weather Bureau and US Army Corps and other reports of storms from 1886-1955. Hourly precipitation from recording rain gauges captured during heavy rain, snow,...

  19. Apparent Relations Between Solar Activity and Solar Tides Caused by the Planets

    Science.gov (United States)

    Hung, Ching-Cheh

    2007-01-01

    A solar storm is a storm of ions and electrons from the Sun. Large solar storms are usually preceded by solar flares, phenomena that can be characterized quantitatively from Earth. Twenty-five of the thirty-eight largest known solar flares were observed to start when one or more tide-producing planets (Mercury, Venus, Earth, and Jupiter) were either nearly above the event positions (less than 10 deg. longitude) or at the opposing side of the Sun. The probability for this to happen at random is 0.039 percent. This supports the hypothesis that the force or momentum balance (between the solar atmospheric pressure, the gravity field, and magnetic field) on plasma in the looping magnetic field lines in solar corona could be disturbed by tides, resulting in magnetic field reconnection, solar flares, and solar storms. Separately, from the daily position data of Venus, Earth, and Jupiter, an 11-year planet alignment cycle is observed to approximately match the sunspot cycle. This observation supports the hypothesis that the resonance and beat between the solar tide cycle and nontidal solar activity cycle influences the sunspot cycle and its varying magnitudes. The above relations between the unpredictable solar flares and the predictable solar tidal effects could be used and further developed to forecast the dangerous space weather and therefore reduce its destructive power against the humans in space and satellites controlling mobile phones and global positioning satellite (GPS) systems.

  20. Toward an integrated storm surge application: ESA Storm Surge project

    Science.gov (United States)

    Lee, Boram; Donlon, Craig; Arino, Olivier

    2010-05-01

    Storm surges and their associated coastal inundation are major coastal marine hazards, both in tropical and extra-tropical areas. As sea level rises due to climate change, the impact of storm surges and associated extreme flooding may increase in low-lying countries and harbour cities. Of the 33 world cities predicted to have at least 8 million people by 2015, at least 21 of them are coastal including 8 of the 10 largest. They are highly vulnerable to coastal hazards including storm surges. Coastal inundation forecasting and warning systems depend on the crosscutting cooperation of different scientific disciplines and user communities. An integrated approach to storm surge, wave, sea-level and flood forecasting offers an optimal strategy for building improved operational forecasts and warnings capability for coastal inundation. The Earth Observation (EO) information from satellites has demonstrated high potential to enhanced coastal hazard monitoring, analysis, and forecasting; the GOCE geoid data can help calculating accurate positions of tide gauge stations within the GLOSS network. ASAR images has demonstrated usefulness in analysing hydrological situation in coastal zones with timely manner, when hazardous events occur. Wind speed and direction, which is the key parameters for storm surge forecasting and hindcasting, can be derived by using scatterometer data. The current issue is, although great deal of useful EO information and application tools exist, that sufficient user information on EO data availability is missing and that easy access supported by user applications and documentation is highly required. Clear documentation on the user requirements in support of improved storm surge forecasting and risk assessment is also needed at the present. The paper primarily addresses the requirements for data, models/technologies, and operational skills, based on the results from the recent Scientific and Technical Symposium on Storm Surges (www

  1. Magnetic storms and induction hazards

    Science.gov (United States)

    Love, Jeffrey J.; Rigler, E. Joshua; Pulkkinen, Antti; Balch, Christopher

    2014-01-01

    Magnetic storms are potentially hazardous to the activities and technological infrastructure of modern civilization. This reality was dramatically demonstrated during the great magnetic storm of March 1989, when surface geoelectric fields, produced by the interaction of the time-varying geomagnetic field with the Earth's electrically conducting interior, coupled onto the overlying Hydro-Québec electric power grid in Canada. Protective relays were tripped, the grid collapsed, and about 9 million people were temporarily left without electricity [Bolduc, 2002].

  2. [Thyroid Storm and Myxedema Coma].

    Science.gov (United States)

    Milkau, Malte; Sayk, Friedhelm

    2018-03-01

    Thyroid storm and myxedema coma are the most severe clinical forms of thyroid dysfunction. While both hyper- and hypothyroidsm are common diseases, thyroid storm and myxedema coma are rare. Due to their unspecific signs and symptoms they are often difficult to diagnose. Both disorders are medical emergencies, which still show a significant mortality. The following article summarizes diagnostic tools and treatment options for these disorders. © Georg Thieme Verlag KG Stuttgart · New York.

  3. Coastal Storm Surge Analysis: Storm Forcing. Report 3. Intermediate Submission No. 1.3

    Science.gov (United States)

    2013-07-01

    The storm surge study considers both tropical storms and extratropical cyclones for determination of return period storm surge elevations. The...Appendix B: Extratropical Cyclone Selection in Support of FEMA Region III Storm Surge Modeling...stations applied in the storm selection process. ............................................. 56  Table B2. Extratropical cyclones selected from the

  4. StormReady in a Box: Enhancing NOAA's Presence in Schools

    Science.gov (United States)

    Grondin, N. S.; Franks, C.

    2015-12-01

    The National Weather Service StormReady Supporter program exists to give schools, companies, TV stations, and other facilities the opportunity to earn recognition for their weather preparedness and awareness. Requirements to earn StormReady Supporter status include having a facility warning point, use of NOAA Weather Radios, and weather hazard Emergency Operation Plans. Despite the increasing importance of weather preparedness in schools, only 1.2% of Minnesota schools are deemed StormReady by the National Weather Service. It was determined that the major impedance for schools becoming StormReady Supporters is the lack of time for administrators to engage in anything "extra" beyond their listed duties. As part of a 2015 Hollings Scholar project, the StormReady in a Box concept was developed to remedy this, by empowering teachers and students to take charge and complete the StormReady Supporter application for their school. StormReady in a Box is a project developed for Junior High School students to learn about weather preparedness and to help their school acquire StormReady status. The project was designed to be relevant to the Minnesota State Education Standards in Science, be simple for teachers to do with their students, and most importantly, to be enjoyable for Junior High School age students to do. The project was also designed to enhance critical thinking skills and logical reasoning abilities, as they relate to the StormReady Supporter application. This presentation will present the overall rationale for the undertaking of this project, the creation of, and the logical next steps for the StormReady in a Box project.

  5. Solar-Geophysical Data Number 551, July 1990. Part 1 (prompt reports). Data for June, May 1990 and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1990-07-01

    ;Contents: Detailed index for 1989-1990; Data for June 1990--Solar-terrestrial environment, IUWDS alert periods (Advance and worldwide), Solar activity indices, Solar flares, Solar radio emission, Stanford mean solar magnetic field; Data for May 1990--Solar active regions, Sudden ionospheric disturbances, Solar radio spectral observations, Cosmic ray measurements by neutron monitor, Geomagnetic indices; Late data--Geomagnetic indices February-April 1990--sudden commencements/solar flare effects

  6. Citizen Science Opportunity With the NASA Heliophysics Education Consortium (HEC)-Radio JOVE Project

    Science.gov (United States)

    Fung, S. F.; Higgins, C.; Thieman, J.; Garcia, L. N.; Young, C. A.

    2016-12-01

    The Radio JOVE project has long been a hands-on inquiry-based educational project that allows students, teachers and the general public to learn and practice radio astronomy by building their own radio antenna and receiver system from an inexpensive kit that operates at 20.1 MHz and/or using remote radio telescopes through the Internet. Radio JOVE participants observe and analyze natural radio emissions from Jupiter and the Sun. Within the last few years, several Radio JOVE amateurs have upgraded their equipment to make semi-professional spectrographic observations in the frequency band of 15-30 MHz. Due to the widely distributed Radio JOVE observing stations across the US, the Radio JOVE observations can uniquely augment observations by professional telescopes, such as the Long Wavelength Array (LWA) . The Radio JOVE project has recently partnered with the NASA Heliophysics Education Consortium (HEC) to work with students and interested amateur radio astronomers to establish additional spectrograph and single-frequency Radio JOVE stations. These additional Radio JOVE stations will help build a larger amateur radio science network and increase the spatial coverage of long-wavelength radio observations across the US. Our presentation will describe the Radio JOVE project within the context of the HEC. We will discuss the potential for citizen scientists to make and use Radio JOVE observations to study solar radio bursts (particularly during the upcoming solar eclipse in August 2017) and Jovian radio emissions. Radio JOVE observations will also be used to study ionospheric radio scintillation, promoting appreciation and understanding of this important space weather effect.

  7. Solar Flares and the High Energy Solar Spectroscopic Imager (HESSI)

    Science.gov (United States)

    Holman, Gordon D.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Solar flares are the biggest explosions in the solar system. They are important both for understanding explosive events in the Universe and for their impact on human technology and communications. The satellite-based HESSI is designed to study the explosive release of energy and the acceleration of electrons, protons, and other charged particles to high energies in solar flares. HESSI produces "color" movies of the Sun in high-energy X rays and gamma rays radiated by these energetic particles. HESSI's X-ray and gamma-ray images of flares are obtained using techniques similar to those used in radio interferometry. Ground-based radio observations of the Sun provide an important complement to the HESSI observations of solar flares. I will describe the HESSI Project and the high-energy aspects of solar flares, and how these relate to radio astronomy techniques and observations.

  8. Onset of frequent dust storms in northern China at ~AD 1100.

    Science.gov (United States)

    He, Yuxin; Zhao, Cheng; Song, Mu; Liu, Weiguo; Chen, Fahu; Zhang, Dian; Liu, Zhonghui

    2015-11-26

    Dust storms in northern China strongly affect the living and health of people there and the dusts could travel a full circle of the globe in a short time. Historically, more frequent dust storms occurred during cool periods, particularly the Little Ice Age (LIA), generally attributed to the strengthened Siberian High. However, limited by chronological uncertainties in proxy records, this mechanism may not fully reveal the causes of dust storm frequency changes. Here we present a late Holocene dust record from the Qaidam Basin, where hydrological changes were previously reconstructed, and examine dust records from northern China, including the ones from historical documents. The records, being broadly consistent, indicate the onset of frequent dust storms at ~AD 1100. Further, peaked dust storm events occurred at episodes of high total solar irradiance or warm-dry conditions in source regions, superimposed on the high background of frequent dust storms within the cool LIA period. We thus suggest that besides strong wind activities, the centennial-scale dust storm events over the last 1000 years appear to be linked to the increased availability of dust source. With the anticipated global warming and deteriorating vegetation coverage, frequent occurrence of dust storms in northern China would be expected to persist.

  9. 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.

  10. High-Latitude Topside Ionospheric Vertical Electron Density Profile Changes in Response to Large Magnetic Storms

    Science.gov (United States)

    Benson, Robert F.; Fainberg, Joseph; Osherovich, Vladimir A.; Truhlik, Vladimir; Wang, Yongli; Bilitza, Dieter; Fung, Shing F.

    2016-01-01

    Large magnetic-storm-induced changes were detected in high-latitude topside vertical electron density profiles Ne(h) in a database of profiles and digital topside ionograms, from the International Satellites for Ionospheric Studies (ISIS) program, that enabled Ne(h) profiles to be obtained in nearly the same region of space before, during, and after a major magnetic storm (Dst -100nT). Storms where Ne(h) profiles were available in the high-latitude Northern Hemisphere had better coverage of solar wind parameters than storms with available Ne(h) profiles in the high-latitude Southern Hemisphere. Large Ne(h) changes were observed during all storms, with enhancements and depletions sometimes near a factor of 10 and 0.1, respectively, but with substantial differences in the responses in the two hemispheres. Large spatial andor temporal Ne(h) changes were often observed during Dst minimum and during the storm recovery phase. The storm-induced Ne(h) changes were the most pronounced and consistent in the Northern Hemisphere in that large enhancements were observed during winter nighttime and large depletions during winter and spring daytime. The limited available cases suggested that these Northern Hemisphere enhancements increased with increases of the time-shifted solar wind velocity v, magnetic field B, and with more negative values of the B components except for the highest common altitude (1100km) of the profiles. There was also some evidence suggesting that the Northern Hemisphere depletions were related to changes in the solar wind parameters. Southern Hemisphere storm-induced enhancements and depletions were typically considerably less with depletions observed during summer nighttime conditions and enhancements during summer daytime and fall nighttime conditions.

  11. From the Sun to the Earth: impact of the 27-28 May 2003 solar events on the magnetosphere, ionosphere and thermosphere

    Directory of Open Access Journals (Sweden)

    C. Hanuise

    2006-03-01

    Full Text Available During the last week of May 2003, the solar active region AR 10365 produced a large number of flares, several of which were accompanied by Coronal Mass Ejections (CME. Specifically on 27 and 28 May three halo CMEs were observed which had a significant impact on geospace. On 29 May, upon their arrival at the L1 point, in front of the Earth's magnetosphere, two interplanetary shocks and two additional solar wind pressure pulses were recorded by the ACE spacecraft. The interplanetary magnetic field data showed the clear signature of a magnetic cloud passing ACE. In the wake of the successive increases in solar wind pressure, the magnetosphere became strongly compressed and the sub-solar magnetopause moved inside five Earth radii. At low altitudes the increased energy input to the magnetosphere was responsible for a substantial enhancement of Region-1 field-aligned currents. The ionospheric Hall currents also intensified and the entire high-latitude current system moved equatorward by about 10°. Several substorms occurred during this period, some of them - but not all - apparently triggered by the solar wind pressure pulses. The storm's most notable consequences on geospace, including space weather effects, were (1 the expansion of the auroral oval, and aurorae seen at mid latitudes, (2 the significant modification of the total electron content in the sunlight high-latitude ionosphere, (3 the perturbation of radio-wave propagation manifested by HF blackouts and increased GPS signal scintillation, and (4 the heating of the thermosphere, causing increased satellite drag. We discuss the reasons why the May 2003 storm is less intense than the October-November 2003 storms, although several indicators reach similar intensities.

  12. From the Sun to the Earth: impact of the 27-28 May 2003 solar events on the magnetosphere, ionosphere and thermosphere

    Directory of Open Access Journals (Sweden)

    C. Hanuise

    2006-03-01

    Full Text Available During the last week of May 2003, the solar active region AR 10365 produced a large number of flares, several of which were accompanied by Coronal Mass Ejections (CME. Specifically on 27 and 28 May three halo CMEs were observed which had a significant impact on geospace. On 29 May, upon their arrival at the L1 point, in front of the Earth's magnetosphere, two interplanetary shocks and two additional solar wind pressure pulses were recorded by the ACE spacecraft. The interplanetary magnetic field data showed the clear signature of a magnetic cloud passing ACE. In the wake of the successive increases in solar wind pressure, the magnetosphere became strongly compressed and the sub-solar magnetopause moved inside five Earth radii. At low altitudes the increased energy input to the magnetosphere was responsible for a substantial enhancement of Region-1 field-aligned currents. The ionospheric Hall currents also intensified and the entire high-latitude current system moved equatorward by about 10°. Several substorms occurred during this period, some of them - but not all - apparently triggered by the solar wind pressure pulses. The storm's most notable consequences on geospace, including space weather effects, were (1 the expansion of the auroral oval, and aurorae seen at mid latitudes, (2 the significant modification of the total electron content in the sunlight high-latitude ionosphere, (3 the perturbation of radio-wave propagation manifested by HF blackouts and increased GPS signal scintillation, and (4 the heating of the thermosphere, causing increased satellite drag. We discuss the reasons why the May 2003 storm is less intense than the October-November 2003 storms, although several indicators reach similar intensities.

  13. Impact of cognitive radio on radio astronomy

    NARCIS (Netherlands)

    Bentum, Marinus Jan; Boonstra, A.J.; Baan, W.A.

    2010-01-01

    The introduction of new communication techniques requires an increase in the efficiency of spectrum usage. Cognitive radio is one of the new techniques that fosters spectrum efficiency by using unoccupied frequency spectrum for communications. However, cognitive radio will increase the transmission

  14. Radio observations of the fine structure inside a post-CME current sheet

    International Nuclear Information System (INIS)

    Gao Guan-Nan; Wang Min; Lin Jun; Kliem Berhard; Wu Ning; Tan Cheng-Ming; Su Yang

    2014-01-01

    A solar radio burst was observed in a coronal mass ejection/flare event by the Solar Broadband Radio Spectrometer at the Huairou Solar Observing Station on 2004 December 1. The data exhibited various patterns of plasma motions, suggestive of the interaction between sunward moving plasmoids and the flare loop system during the impulsive phase of the event. In addition to the radio data, the associated white-light, Hα, extreme ultraviolet light, and soft and hard X-rays were also studied. (mini-volume: solar radiophysics — recent results on observations and theories)

  15. Fast Radio Bursts

    Indian Academy of Sciences (India)

    Akshaya Rane

    2017-09-12

    ) which were first discovered a decade ago. Following an introduction to radio transients in general, including pulsars and rotating radio transients, we discuss the discovery of FRBs. We then discuss FRB follow-up ...

  16. Tormenta tiroidea Thyroid storm

    Directory of Open Access Journals (Sweden)

    Lisette Leal Curí

    2012-12-01

    Full Text Available La tormenta tiroidea es una de las situaciones más críticas entre las emergencias endocrinas y tiene una significativa mortalidad. La etiología más común de tirotoxicosis es la enfermedad de Graves y el factor precipitante que predomina es la infección. Clínicamente se caracteriza por la disfunción de varios sistemas (termorregulador, nervioso central, gastrointestinal y cardiovascular, con niveles de hormonas tiroideas libres o totales por encima de los valores normales. El tratamiento debe tener un enfoque multidisciplinario, e incluye medidas de soporte en unidades de cuidados intensivos, normalización de la temperatura corporal, reducción de la producción y liberación de hormonas tiroideas, con antitiroideos de síntesis y yodo respectivamente, bloqueo de los efectos periféricos mediante la administración de beta-bloqueadores, y corrección del factor desencadenante. Una vez que el paciente se encuentra estable es necesario planificar una terapia definitiva que impida la recurrencia futura de la crisis tirotóxica.The thyroid storm is one of the most critical situations in the endocrine emergencies and exhibits a significant mortality rate. The most common etiology of thyrotoxicosis is Graves' disease and the predominant precipitating factor is infection. The clinical characteristics are dysfunction of several systems (heat-regulator, central nervous, gastrointestinal and cardiovascular, and levels of total or free thyroid hormones that exceed the normal values. The treatment must be multidisciplinary and include support measures in intensive care units, normalization of body temperature, reduction of the production and the release of thyroid hormones by using synthesis and iodine anti-thyroid products respectively, blockade of the peripheral effects through administration of Beta-blockers and correction of the unleashing factor. Once the patients are stabilized, it is necessary to plan the final therapy that will prevent the

  17. La radio digital

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Cortés S.

    2015-01-01

    Full Text Available La radio digital es un producto de la llamada convergencia digital. Las nuevas tecnologías interconectadas permiten la aparición de nuevos modos de audiencia y la implementación de herramientas versátiles. Habla del problema de los estándares, de la radio satelital, la radio digital terrestre, las radios internacionales, la interactividad.

  18. Ionospheric Response to the Magnetic Storm of 22 June 2015

    Science.gov (United States)

    Mansilla, Gustavo A.

    2018-03-01

    A global study is made of the response of the total electron content of the ionosphere (TEC) to the geomagnetic storm occurred on 22 June 2015 (one of the strongest geomagnetic storms of the current Solar Cycle 24). Using data from 44 sites, a hemispheric comparison is made by considering high latitudes (> 50°), middle latitudes (30°-50°) and low latitudes (30°N-30°S). The main features observed were: increases in TEC at high latitudes prior to the storm main phase, a considerable asymmetry of TEC response at middle and low latitudes of the Northern Hemisphere and the Southern Hemisphere and decreases at equatorial latitudes. The long duration enhancements in TEC were well correlated with increases in the O/N2 ratio but decreases in TEC had not associated decreases in the O/N2 ratio as occur with the decreases in the electron density. Besides, prompt penetration electric fields can play an important role in the equatorial and low-latitude ionosphere during main phase of the storm.

  19. 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 (Bzsolar 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.

  20. Commercial Radio as Communication.

    Science.gov (United States)

    Rothenbuhler, Eric W.

    1996-01-01

    Compares the day-to-day work routines of commercial radio with the principles of a theoretical communication model. Illuminates peculiarities of the conduct of communication by commercial radio. Discusses the application of theoretical models to the evaluation of practicing institutions. Offers assessments of commercial radio deriving from…

  1. High-Latitude Topside Ionospheric Vertical Electron-Density-Profile Changes in Response to Large Magnetic Storms

    Science.gov (United States)

    Benson, Robert F.; Fainberg, Joseph; Osherovich, Vladimir A.; Truhlik, Vladimir; Wang, Yongli; Bilitza, Dieter; Fung, Shing F.

    2015-01-01

    Large magnetic-storm induced changes have been detected in high-latitude topside vertical electron-density profiles Ne(h). The investigation was based on the large database of topside Ne(h) profiles and digital topside ionograms from the International Satellites for Ionospheric Studies (ISIS) program available from the NASA Space Physics Data Facility (SPDF) at http://spdf.gsfc.nasa.gov/isis/isis-status.html. This large database enabled Ne(h) profiles to be obtained when an ISIS satellite passed through nearly the same region of space before, during, and after a major magnetic storm. A major goal was to relate the magnetic-storm induced high-latitude Ne(h) profile changes to solar-wind parameters. Thus an additional data constraint was to consider only storms where solar-wind data were available from the NASA/SPDF OMNIWeb database. Ten large magnetic storms (with Dst less than -100 nT) were identified that satisfied both the Ne(h) profile and the solar-wind data constraints. During five of these storms topside ionospheric Ne(h) profiles were available in the high-latitude northern hemisphere and during the other five storms similar ionospheric data were available in the southern hemisphere. Large Ne(h) changes were observed during each one of these storms. Our concentration in this paper is on the northern hemisphere. The data coverage was best for the northern-hemisphere winter. Here Ne(h) profile enhancements were always observed when the magnetic local time (MLT) was between 00 and 03 and Ne(h) profile depletions were always observed between 08 and 10 MLT. The observed Ne(h) deviations were compared with solar-wind parameters, with appropriate time shifts, for four storms.

  2. 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.

  3. Solar--geophysical data number 410, October 1978. Part II. (Comprehensive reports). Data for April 1978--March 1978 and miscellanea

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1978-10-01

    This comprehensive report for April 1978, March 1978 and Miscellaneous data provides data on active regions, synoptic solar maps, solar flares, solar radio waves, energetic solar particles and plasma, synoptic chart, abbreviated calendar record, regional flare index, solar x-ray radiation, cosmic rays, energetic solar particles and plasma for March 1978 and solar flares for February 1978

  4. Ham radio for dummies

    CERN Document Server

    Silver, H Ward

    2013-01-01

    An ideal first step for learning about ham radio Beyond operating wirelessly, today's ham radio operators can transmit data and pictures; use the Internet, laser, and microwave transmitters; and travel to places high and low to make contact. This hands-on beginner guide reflects the operational and technical changes to amateur radio over the past decade and provides you with updated licensing requirements and information, changes in digital communication (such as the Internet, social media, and GPS), and how to use e-mail via radio. Addresses the critical use of ham radio for replacing downe

  5. Solar-Geophysical Data Number 571, March 1992. Part 1 (prompt reports). Data for February, January 1992 and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1992-03-01

    The contents include: Detailed index for 1991-1992; Data for February 1992--Solar-terrestrial environment, IUWDS alert periods (advance and worldwide), Solar activity indices, Solar flares, Solar radio emission, Stanford mean solar magnetic field; Data for January 1992--Solar active regions, Sudden ionospheric disturbances, Solar radio spectral observations, Cosmic ray measurements by neutron monitor, Geomagnetic indices; Late data--Cosmic rays Climax and Huancayo Jul-Dec 91, Sudden Commencements Jun-Aug 91, and Geomagnetic indices Dec 91

  6. Radiography of Spanish Radio

    Directory of Open Access Journals (Sweden)

    Dra. Emma Rodero Antón

    2007-01-01

    Full Text Available In its eighty years of existence, radio has been always characterized to adapt to the social, cultural and technological transformations. Thus it has been until this moment. Nevertheless, some years ago, the authors and professionals of this medium have been detecting a stagnation that affects to its structure. At a time in continuous technological evolution, radio demands a deep transformation. For that reason, from the conviction of which the future radio, public and commercial, will necessarily have to renew itself, in this paper we establish ten problems and their possible solutions to the radio crisis in order to draw an x-ray of radio in Spain. Radio has future, but it is necessary to work actively by it. That the radio continues being part of sound of our life, it will depend on the work of all: companies, advertisers, professionals, students, investigators and listeners.

  7. 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)

  8. Patterns of Storm Injury and Tree Response

    Science.gov (United States)

    Kevin Smith; Walter Shortle; Kenneth Dudzik

    2001-01-01

    The ice storm of January 1998 in the northeastern United States and adjacent Canada was an extreme example of severe weather that injures trees every year. Broken branches, split branch forks, and snapped stems are all examples of storm injury.

  9. Solar-Geophysical Data Number 546, February 1990. Part 1 (prompt reports). data for January 1990, December 1989, and late data

    International Nuclear Information System (INIS)

    Coffey, H.E.

    1990-02-01

    Contents include: detailed index for 1989-1990; data for January 1990--solar-terrestrial environment, IUWDS alert periods (advance and worldwide), solar activity indices, solar flares, solar radio emission, Stanford mean solar magnetic field; data for December 1989--solar-active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic-ray measurements by neutron monitor, geomagnetic indices; late data--cosmic-ray measurements by neutron monitor, reprint of halftone-page Kitt Peak solar magnetic field synoptic chart November 1989

  10. Solar--geophysical data number 368. Part I (prompt reports). Data for March 1975--February 1975. Explanation of data reports issued as number 366 (supplement) February 1975

    International Nuclear Information System (INIS)

    Leighton, H.I.

    1975-04-01

    The bulletin gives various statistical and pictorial solar and geophysical data for the period February--March, 1975. The following aspects of solar activity are explored: Daily solar indices, solar flares, solar radio waves, solar wind measurements, solar x-ray radiation, and solar proton monitoring. Other topics include: Alert period, spacecraft observations, inferred IP magnetic field polarities, sudden ionospheric disturbances, cosmic rays, geomagnetic indices, and radio propagation indices

  11. Identification of possible intense historical geomagnetic storms using combined sunspot and auroral observations from East Asia

    Directory of Open Access Journals (Sweden)

    D. M. Willis

    2005-03-01

    Full Text Available Comprehensive catalogues of ancient sunspot and auroral observations from East Asia are used to identify possible intense historical geomagnetic storms in the interval 210 BC-AD 1918. There are about 270 entries in the sunspot catalogue and about 1150 entries in the auroral catalogue. Special databases have been constructed in which the scientific information in these two catalogues is placed in specified fields. For the purposes of this study, an historical geomagnetic storm is defined in terms of an auroral observation that is apparently associated with a particular sunspot observation, in the sense that the auroral observation occurred within several days of the sunspot observation. More precisely, a selection criterion is formulated for the automatic identification of such geomagnetic storms, using the oriental records stored in the sunspot and auroral databases. The selection criterion is based on specific assumptions about the duration of sunspot visibility with the unaided eye, the likely range of heliographic longitudes of an energetic solar feature, and the likely range of transit times for ejected solar plasma to travel from the Sun to the Earth. This selection criterion results in the identification of nineteen putative historical geomagnetic storms, although two of these storms are spurious in the sense that there are two examples of a single sunspot observation being associated with two different auroral observations separated by more than half a (synodic solar rotation period. The literary and scientific reliabilities of the East Asian sunspot and auroral records that define the nineteen historical geomagnetic storms are discussed in detail in a set of appendices. A possible time sequence of events is presented for each geomagnetic storm, including possible dates for both the central meridian passage of the sunspot and the occurrence of the energetic solar feature, as well as likely transit times for the ejected solar plasma

  12. Damping of type III solar radio bursts

    International Nuclear Information System (INIS)

    Levin, B.N.

    1982-01-01

    The meter- and decameter-wavelength damping of type III bursts may be attributable to stabilization of the Langmuir-wave instability of the fast-electron streams through excitation of cyclotron-branch plasma waves

  13. Dynamic auroral storms on Saturn as observed by the Hubble Space Telescope.

    Science.gov (United States)

    Nichols, J D; Badman, S V; Baines, K H; Brown, R H; Bunce, E J; Clarke, J T; Cowley, S W H; Crary, F J; Dougherty, M K; Gérard, J-C; Grocott, A; Grodent, D; Kurth, W S; Melin, H; Mitchell, D G; Pryor, W R; Stallard, T S

    2014-05-28

    We present observations of significant dynamics within two UV auroral storms observed on Saturn using the Hubble Space Telescope in April/May 2013. Specifically, we discuss bursts of auroral emission observed at the poleward boundary of a solar wind-induced auroral storm, propagating at ∼330% rigid corotation from near ∼01 h LT toward ∼08 h LT. We suggest that these are indicative of ongoing, bursty reconnection of lobe flux in the magnetotail, providing strong evidence that Saturn's auroral storms are caused by large-scale flux closure. We also discuss the later evolution of a similar storm and show that the emission maps to the trailing region of an energetic neutral atom enhancement. We thus identify the auroral form with the upward field-aligned continuity currents flowing into the associated partial ring current.

  14. Storm Water Management Model (SWMM)

    Science.gov (United States)

    Stormwater discharges continue to cause impairment of our Nation’s waterbodies. Regulations that require the retention and/or treatment of frequent, small storms that dominate runoff volumes and pollutant loads are becoming more common. The U.S. Environmental Protection Agency (E...

  15. Stochastic Optical Reconstruction Microscopy (STORM).

    Science.gov (United States)

    Xu, Jianquan; Ma, Hongqiang; Liu, Yang

    2017-07-05

    Super-resolution (SR) fluorescence microscopy, a class of optical microscopy techniques at a spatial resolution below the diffraction limit, has revolutionized the way we study biology, as recognized by the Nobel Prize in Chemistry in 2014. Stochastic optical reconstruction microscopy (STORM), a widely used SR technique, is based on the principle of single molecule localization. STORM routinely achieves a spatial resolution of 20 to 30 nm, a ten-fold improvement compared to conventional optical microscopy. Among all SR techniques, STORM offers a high spatial resolution with simple optical instrumentation and standard organic fluorescent dyes, but it is also prone to image artifacts and degraded image resolution due to improper sample preparation or imaging conditions. It requires careful optimization of all three aspects-sample preparation, image acquisition, and image reconstruction-to ensure a high-quality STORM image, which will be extensively discussed in this unit. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

  16. Shoreline resilience to individual storms and storm clusters on a meso-macrotidal barred beach

    NARCIS (Netherlands)

    Angnuureng, Donatus Bapentire; Almar, Rafael; Senechal, Nadia; Castelle, Bruno; Addo, Kwasi Appeaning; Marieu, Vincent; Ranasinghe, Roshanka

    2017-01-01

    This study investigates the impact of individual storms and storm clusters on shoreline recovery for the meso-to macrotidal, barred Biscarrosse beach in SW France, using 6 years of daily video observations. While the study area experienced 60 storms during the 6-year study period, only 36 storms

  17. 46 CFR 108.221 - Storm rails.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Storm rails. 108.221 Section 108.221 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the following...

  18. 46 CFR 169.329 - Storm rails.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must be...

  19. Er Storm P. en hardcore vagabond?

    DEFF Research Database (Denmark)

    Sortkær, Allan

    2002-01-01

    Den vagabond, som vi kender som Storm P.s, er ikke en figur, der kom fra en guddommelig inspiration eller deslige. Den var en allerede velkendt figur, før Storm P. tog den til sig, og figuren gennemgik radikale forandringer gennem Storm P.s liv: Krads social satire, hypervoldelig eller hyggelig...

  20. 46 CFR 116.920 - Storm rails.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Storm rails. 116.920 Section 116.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE THAN 150... and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must be installed where necessary...

  1. 46 CFR 177.920 - Storm rails.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Storm rails. 177.920 Section 177.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must be...

  2. 46 CFR 127.320 - Storm rails.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Storm rails. 127.320 Section 127.320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in each passageway and at...

  3. Energetic electron precipitation in weak to moderate corotating interaction region-driven storms

    Science.gov (United States)

    Ødegaard, Linn-Kristine Glesnes; Tyssøy, Hilde Nesse; Søraas, Finn; Stadsnes, Johan; Sandanger, Marit Irene

    2017-03-01

    High-energy electron precipitation from the radiation belts can penetrate deep into the mesosphere and increase the production rate of NOx and HOx, which in turn will reduce ozone in catalytic processes. The mechanisms for acceleration and loss of electrons in the radiation belts are not fully understood, and most of the measurements of the precipitating flux into the atmosphere have been insufficient for estimating the loss cone flux. In the present study the electron flux measured by the NOAA POES Medium Energy Proton and Electron Detectors 0° and 90° detectors is combined together with theory of pitch angle diffusion by wave-particle interaction to quantify the electron flux lost below 120 km altitude. Using this method, 41 weak and moderate geomagnetic storms caused by corotating interaction regions during 2006-2010 are studied. The dependence of the energetic electron precipitation fluxes upon solar wind parameters and geomagnetic indices is investigated. Nine storms give increased precipitation of >˜750 keV electrons. Nineteen storms increase the precipitation of >˜300 keV electrons, but not the >˜750 keV population. Thirteen storms either do not change or deplete the fluxes at those energies. Storms that have an increase in the flux of electrons with energy >˜300 keV are characterized by an elevated solar wind velocity for a longer period compared to the storms that do not. Storms with increased precipitation of >˜750 keV flux are distinguished by higher-energy input from the solar wind quantified by the ɛ parameter and corresponding higher geomagnetic activity.

  4. Development of VLF noise storm and its relation to dynamics of magnetosphere during geomagnetic storms

    International Nuclear Information System (INIS)

    Fedyakina, N.I.; Khorosheva, O.V.

    1989-01-01

    Dependence between the development of geomagnetic storm and VLF noise storm is studied. Two conditions should be met for the development of noise storm in VLF-hiss (f ≅ 0.5-10 kHz): a) threshold intensity of electron fluxes with E e > 40 keV in plasma layers; b) the presence of substorms resulting to widening of electron belt and its collision with cold plasma of plasmasphere. The noise storm at the fixed longitude begins about midnight independently of the phase of magnetic storm; Noise storm duration is connected with geomagnetic storm intensity by direct linear relationship

  5. Observations of energetic helium ions in the Earth's radiation belts during a sequence of geomagnetic storms

    International Nuclear Information System (INIS)

    Spjeldvik, W.N.; Fritz, T.A.

    1981-01-01

    Every year a significant number of magnetic storms disturb the earth's magnetosphere and the trapped particle populations. In this paper, we present observations of energetic (MeV) helium ions made with Explorer 45 during a sequence of magnetic storms during June through December of 1972. The first of these storms started on June 17 and had a Dst index excursion to approx.190 gamma, and the MeV helium ions were perturbed primarily beyond 3 earth radii in the equatorial radiation belts with a typical flux increase of an order of magnitude at L = 4. The second storm period took place during August and was associated with very major solar flare activity. Although the Dst extremum was at best 35 gamma less than the June storm, this period can be characterized as irregular (or multi-storm) with strong compression of the magnetosphere and very large (order of magnitude) MeV helium ion flux enhancements down to Lapprox.2. Following this injection the trapped helium ion fluxes showed positive spectral slope with the peak beyond 3.15 MeV at L = 2.5; and at the lowest observable L shells (Lapprox.2--3) little flux decay (tau>100 days) was seen during the rest of the year. Any effects of two subsequent major magnetic storms in September and November were essentially undetectable in the prolonged after-effect of the August solar flare associated MeV helium ion injection. The helium ion radial profile of the phase space density showed a significant negative slope during this period, and we infer that radial diffusion constitutes a significant loss of helium ions on L shells above Lapprox. =4 during the aftermath of the August 1972 magnetic storm

  6. Solar Variability and Planetary Climates

    CERN Document Server

    Calisesi, Y; Gray, L; Langen, J; Lockwood, M

    2007-01-01

    Variations in solar activity, as revealed by variations in the number of sunspots, have been observed since ancient times. To what extent changes in the solar output may affect planetary climates, though, remains today more than ever a subject of controversy. In 2000, the SSSI volume on Solar Variability and Climate reviewed the to-date understanding of the physics of solar variability and of the associated climate response. The present volume on Solar Variability and Planetary Climates provides an overview of recent advances in this field, with particular focus at the Earth's middle and lower atmosphere. The book structure mirrors that of the ISSI workshop held in Bern in June 2005, the collection of invited workshop contributions and of complementary introductory papers synthesizing the current understanding in key research areas such as middle atmospheric processes, stratosphere-troposphere dynamical coupling, tropospheric aerosols chemistry, solar storm influences, solar variability physics, and terrestri...

  7. Propagation of Energetic Electrons from the Corona into Interplanetary Space and Type III Radio Emission. Planetary Radio Emissions| PLANETARY RADIO EMISSIONS VII 7|

    OpenAIRE

    Vocks, C.; Breitling, F.; Mann, G.

    2011-01-01

    During solar flares a large amount of electrons with energies greater than 20 keV is generated with a production rate of typically 1036 s-1. A part of them is able to propagate along open magnetic field lines through the corona into interplanetary space. During their travel they emit radio radiation which is observed as type III radio bursts in the frequency range from 100 MHz down to 10 kHz by the WAVES radio spectrometer aboard the spacecraft WIND, for instance. From the drift rates of thes...

  8. AUTOMATIC RECOGNITION OF CORONAL TYPE II RADIO BURSTS: THE AUTOMATED RADIO BURST IDENTIFICATION SYSTEM METHOD AND FIRST OBSERVATIONS

    International Nuclear Information System (INIS)

    Lobzin, Vasili V.; Cairns, Iver H.; Robinson, Peter A.; Steward, Graham; Patterson, Garth

    2010-01-01

    Major space weather events such as solar flares and coronal mass ejections are usually accompanied by solar radio bursts, which can potentially be used for real-time space weather forecasts. Type II radio bursts are produced near the local plasma frequency and its harmonic by fast electrons accelerated by a shock wave moving through the corona and solar wind with a typical speed of ∼1000 km s -1 . The coronal bursts have dynamic spectra with frequency gradually falling with time and durations of several minutes. This Letter presents a new method developed to detect type II coronal radio bursts automatically and describes its implementation in an extended Automated Radio Burst Identification System (ARBIS 2). Preliminary tests of the method with spectra obtained in 2002 show that the performance of the current implementation is quite high, ∼80%, while the probability of false positives is reasonably low, with one false positive per 100-200 hr for high solar activity and less than one false event per 10000 hr for low solar activity periods. The first automatically detected coronal type II radio burst is also presented.

  9. Relativistic electron acceleration during HILDCAA events: are precursor CIR magnetic storms important?

    Czech Academy of Sciences Publication Activity Database

    Hajra, R.; Tsurutani, B. T.; Echer, E.; Gonzalez, W. D.; Brum, Ch. G. M.; Antunes Vieira, L. E.; Santolík, Ondřej

    2015-01-01

    Roč. 67, Article Number 109 (2015), 109/1-109/11 ISSN 1880-5981 R&D Projects: GA MŠk LH12231 Institutional support: RVO:68378289 Keywords : HILDCAAs * high-speed streams * CIRs * chorus plasma waves * radiation belt * magnetospheric relativistic electrons * solar wind * geomagnetic storms Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.871, year: 2015

  10. Ionospheric Anomalies of the 2011 Tohoku Earthquake with Multiple Observations during Magnetic Storm Phase

    Science.gov (United States)

    Liu, Yang

    2017-04-01

    days. Associated with geomagnetic storm at similar time, radio occultation data provided by COSMIC were deeply investigated within the whole month. It's quite different that the storm or earthquake didn't trigger scintillation burst. This is probably due to the storm occurrence local time was in noon sector, which has little impact on ionospheric irregularities increase, but help to enhance the effect of westward electricity, which on the other hand diminishes scintillation bubbles (Li et al 2008). A small geomagnetic disturbance was also found almost a week prior to the earthquake, the relationship of this event to the major earthquake is worth further discussion. Similar analysis of GNSS TECs have been done, the results indicated that it can be also referred as precursor to the major earthquake. Li G, Ning B, Zhao B, et al. Effects of geomagnetic storm on GPS ionospheric scintillations at Sanya[J]. Journal of Atmospheric and Solar-Terrestrial Physics, 2008, 70(7):1034-1045. Liu J Y, Chen Y I, Chuo Y J, et al. A statistical investigation of pre-earthquake ionospheric anomaly[J]. Journal of Geophysical Research Atmospheres, 2006, 111(A5). Liu J Y, Sun Y Y. Seismo-traveling ionospheric disturbances of ionograms observed during the 2011 Mw 9.0 Tohoku Earthquake[J]. Earth, Planets and Space, 2011, 63(7):897-902. Zhao B, Wang M, Yu T, et al. Is an unusual large enhancement of ionospheric electron density linked with the 2008 great Wenchuan earthquake?[J]. Journal of Geophysical Research Atmospheres, 2008, 113(A11):A11304. Pulinets S A. Seismic activity as a source of the ionospheric variability [J]. Advances in Space Research, 1998, 22(6):903-906.

  11. Senior radio listeners

    DEFF Research Database (Denmark)

    Blaakilde, Anne Leonora

    Radiobroadcasting and the hardware materialization of radio have during the 20th century changed significantly, which means that senior radio listeners have travelled along with this evolution from large, impressive radio furnitures to DAB and small, wireless, mobile devices, and from grave...... and solemn radio voices to lightharted, laughing and chatting speakers. Senior radio listerners have experienced the development and refinements of technique, content and genres. It is now expected of all media users that they are capable of crossing media, combining, juggling and jumping between various...... media platforms, not the least when listening to radio. The elder generation is no exception from this. Recently, for instance, the Danish public broadcast DR has carried out an exodus of programmes targeted for the senior segment. These programmes are removed from regular FM and sent to DAB receivers...

  12. The storm-time ring current: a statistical analysis at two widely separated low-latitude stations

    Directory of Open Access Journals (Sweden)

    P. Francia

    2004-11-01

    Full Text Available We conducted a statistical analysis of the geomagnetic field variations during the storm main phase at two low-latitude stations, separated by several hours in magnetic local time, in order to investigate the asymmetry and longitudinal extent of the storm-time ring current. The results show evidence for an asymmetric current which typically extends from evening to noon and, during moderate solar wind electric field conditions, up to the early morning, confirming the important role of the magnetospheric convection in the ring current energization. We also analyzed a possible relationship between the local current intensity during the storm main phase and the substorm activity observed at different time delays τ with respect to the storm onset. The results show a significant anticorrelation for τ =-1h, indicating that if the substorm activity is high just before the storm, a weaker ring current develops.

  13. Analysis of High-Latitude lonospheric Processes During HSS and CME-Induced Geomagnetic Storms

    DEFF Research Database (Denmark)

    Durgonics, Tibor; Komjathy, Attila; Verkhoglyadova, Olga

    processes responsible for the negative phase have less pronounced impact on the diurnal TEC variations than on patch formation. We also investigated and assessed storm influences on airborne navigation at high-latitudes in order to determine the possible cause of the radio communication disturbances....... This effort may lead us to a better understanding of the phenomenon and might help develop communication hardware that is more resistant to such effects....

  14. Solar cycle distribution of strong solar proton events and the related solar-terrestrial phenomena

    Science.gov (United States)

    Le, Guiming; Yang, Xingxing; Ding, Liuguang; Liu, Yonghua; Lu, Yangping; Chen, Minhao

    2014-08-01

    We investigated the solar cycle distribution of strong solar proton events (SPEs, peak flux ≥1000 pfu) and the solar-terrestrial phenomena associated with the strong SPEs during solar cycles 21-23. The results show that 37 strong SPEs were registered over this period of time, where 20 strong SPEs were originated from the super active regions (SARs) and 28 strong SPEs were accompanied by the X-class flares. Most strong SPEs were not associated with the ground level enhancement (GLE) event. Most strong SPEs occurred in the descending phases of the solar cycles. The weaker the solar cycle, the higher the proportion of strong SPES occurred in the descending phase of the cycle. The number of the strong SPEs that occurred within a solar cycle is poorly associated with the solar cycle size. The intensity of the SPEs is highly dependent of the location of their source regions, with the super SPEs (≥20000 pfu) distributed around solar disk center. A super SPE was always accompanied by a fast shock driven by the associated coronal mass ejection and a great geomagnetic storm. The source location of strongest GLE event is distributed in the well-connected region. The SPEs associated with super GLE events (peak increase rate ≥100%) which have their peak flux much lower than 10000 pfu were not accompanied by an intense geomagnetic storm.

  15. The road to OLFAR - a roadmap to interferometric long-wavelength radio astronomy using miniaturized distributed space systems

    NARCIS (Netherlands)

    Engelen, Steven; Quillien, Kevin A.; Verhoeven, Chris; Noroozi, Arash; Sundaramoorthy, Prem; van der Veen, Alle-Jan; Rajan, Raj; Rajan, Raj Thilak; Boonstra, Albert Jan; Bentum, Marinus Jan; Meijerink, Arjan; Budianu, A.

    2013-01-01

    The Orbiting Low Frequency Antennas for Radio Astronomy (OLFAR) project aims to develop a space-based low frequency radio telescope that will explore the universe's so-called dark ages, map the interstellar medium, and discover planetary and solar bursts in other solar systems. The telescope,

  16. Measurement Technique in Radio Frequency Interference (RFI) Study for Radio Astronomy Purposes

    International Nuclear Information System (INIS)

    Roslan Umar; Roslan Umar; Nor Hazmin Sabri; Zainol Abidin Ibrahim; Zamri Zainal Abidin; Asyaari Muhamad

    2015-01-01

    In this paper, we will review our method in making measurements of radio frequency interference (RFI) in order to investigate the sereneness of interference in selected radio interference in Malaysia and Thailand. The selected site are University of Malaya (UM), Universiti Pendidikan Sultan Idris (UPSI), Ubon (UB) and Chiang Mai (CM). The major RFI affecting radio astronomical windows below 1 GHz are electronic equipment system specifically radio navigation between 73.1 MHz and 75.2 MHz, radio broadcasting (151 MHz, 151.8 MHz and 152 MHz), aeronautical navigation (245.5 MHz, 248.7 MHz and 249 MHz and also fixed mobile at 605 MHz, 608.3 MHz, 612.2 MHz, 613.3 MHz. It is obviously showed that all sites within this region are free from interference between 320MHz and 330 MHz and is the best specific region to be considered for solar burst monitoring. We also investigate the effect of RFI on discovery of solar burst. (author)

  17. Decreasing the stable trapping region during geomagnetic storm

    International Nuclear Information System (INIS)

    Mal'tsev, Yu.P.; Feshchenko, E.Yu.

    1998-01-01

    Within the frameworks of the magnetic field model, depending on the solar wind pressure, the B = B s (B s is the magnetic field in the undersolar point) contour behaviour in the equatorial plane is calculated. The boundary of stable trapping in the quiet time is at the distance of 10-11 R E by day and ∼ 7 R E by night. During strong storms this distance may be decreased up 4-5 R E . The calculation results coincide satisfactorily with satellite measurements

  18. [Diagnosis and treatment of thyroid storm].

    Science.gov (United States)

    Akamizu, Takashi

    2012-11-01

    Thyrotoxic storm is a life-threatening condition requiring emergency treatment. Neither its epidemiological data nor diagnostic criteria have been fully established. We clarified the clinical and epidemiological characteristics of thyroid storm using nationwide surveys and then formulate diagnostic criteria for thyroid storm. To perform the nationwide survey on thyroid storm, we first developed tentative diagnostic criteria for thyroid storm, mainly based upon the literature (the first edition). We analyzed the relationship of the major features of thyroid storm to mortality and to certain other features. Finally, based upon the findings of these surveys, we revised the diagnostic criteria. Thyrotoxic storm is still a life-threatening disorder with over 10% mortality in Japan.

  19. Thermospheric storms and related ionospheric effects

    International Nuclear Information System (INIS)

    Chandra, S.; Spencer, N.W.

    1976-01-01

    A comparative study of thermospheric storms for the equinox and winter conditions is presented based on the neutral composition measurements from the Aeros-A Nate (Neutral Atmosphere Temperature Experiment) experiment. The main features of the two storms as inferred from the changes in N 2 , Ar, He, and O are described, and their implications to current theories of thermospheric storms are discussed. On the basis of the study of the F region critical frequency measured from a chain of ground-based ionospheric stations during the two storm periods, the general characteristics of the ionospheric storms and the traveling ionospheric disturbances are described. It is suggested that the positive and negative phases of ionospheric storms are the various manifestations of thermospheric storms

  20. Thyroid storm precipitated by duodenal ulcer perforation.

    Science.gov (United States)

    Natsuda, Shoko; Nakashima, Yomi; Horie, Ichiro; Ando, Takao; Kawakami, Atsushi

    2015-01-01

    Thyroid storm is a rare and life-threatening complication of thyrotoxicosis that requires prompt treatment. Thyroid storm is also known to be associated with precipitating events. The simultaneous treatment of thyroid storm and its precipitant, when they are recognized, in a patient is recommended; otherwise such disorders, including thyroid storm, can exacerbate each other. Here we report the case of a thyroid storm patient (a 55-year-old Japanese male) complicated with a perforated duodenal ulcer. The patient was successfully treated with intensive treatment for thyroid storm and a prompt operation. Although it is believed that peptic ulcer rarely coexists with hyperthyroidism, among patients with thyroid storm, perforation of a peptic ulcer has been reported as one of the causes of fatal outcome. We determined that surgical intervention was required in this patient, reported despite ongoing severe thyrotoxicosis, and reported herein a successful outcome.