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Sample records for period event observations

  1. Observations of deep long-period (DLP) seismic events beneath Aleutian arc volcanoes; 1989-2002

    USGS Publications Warehouse

    Power, J.A.; Stihler, S.D.; White, R.A.; Moran, S.C.

    2004-01-01

    Between October 12, 1989 and December 31, 2002, the Alaska Volcano Observatory (AVO) located 162 deep long-period (DLP) events beneath 11 volcanic centers in the Aleutian arc. These events generally occur at mid- to lower-crustal depths (10-45 km) and are characterized by emergent phases, extended codas, and a strong spectral peak between 1.0 and 3.0 Hz. Observed wave velocities and particle motions indicate that the dominant phases are P- and S-waves. DLP epicenters often extend over broad areas (5-20 km) surrounding the active volcanoes. The average reduced displacement of Aleutian DLPs is 26.5 cm2 and the largest event has a reduced displacement of 589 cm2 (or ML 2.5). Aleutian DLP events occur both as solitary events and as sequences of events with several occurring over a period of 1-30 min. Within the sequences, individual DLPs are often separated by lower-amplitude volcanic tremor with a similar spectral character. Occasionally, volcano-tectonic earthquakes that locate at similar depths are contained within the DLP sequences. At most, Aleutian volcanoes DLPs appear to loosely surround the main volcanic vent and occur as part of background seismicity. A likely explanation is that they reflect a relatively steady-state process of magma ascent over broad areas in the lower and middle portions of the crust. At Mount Spurr, DLP seismicity was initiated by the 1992 eruptions and then slowly declined until 1997. At Shishaldin Volcano, a short-lived increase in DLP seismicity occurred about 10 months prior to the April 19, 1999 eruption. These observations suggest a link between eruptive activity and magma flux in the mid- to lower-crust and uppermost mantle.

  2. Cells anticipate periodic events

    NASA Astrophysics Data System (ADS)

    Nakagaki, Toshiyuki

    2009-03-01

    We show that an amoeboid organism can anticipate the timing of periodic events. The plasmodium of the true slime mold Physarum polycephalum moves rapidly under favourable conditions, but stops moving when transferred to less-favourable conditions. Plasmodia exposed to unfavourable conditions, presented in three consecutive pulses at constant intervals, reduced their locomotive speed in response to each episode. When subsequently subjected to favourable conditions, the plasmodia spontaneously reduced their locomotive speed at the time point when the next unfavourable episode would have occurred. This implied anticipation of impending environmental change. After this behaviour had been evoked several times, the locomotion of the plasmodia returned to normal; however, the anticipatory response could subsequently be induced by a single unfavourable pulse, implying recall of the memorized periodicity. We explored the mechanisms underlying these behaviours from a dynamical systems perspective. Our results hint at the cellular origins of primitive intelligence and imply that simple dynamics might be sufficient to explain its emergence.

  3. Cluster observations of quasi-periodic impulsive signatures in the dayside northern lobe: High-latitude flux transfer events?

    NASA Technical Reports Server (NTRS)

    Thompson, S. M.; Kivelson, M. G.; Khurana, K. K.; Balogh, A.; Reme, H.; Fazakerley, A. N.; Kistler, L. M.

    2004-01-01

    We report on a series of quasi-periodic reversals in GSM B(sub Z) observed by the four Cluster spacecraft in the northern dayside lobe poleward of the cusp on 23 February 2001. During an interval of about 35 min, multiple reversals (negative to positive) in B(sub Z) of approximately 1-min duration with an approximate 8-min recurrence time were observed. The individual structures do not resemble low-latitude flux transfer events (FTE) [Russell and Elphic, 1979] but the 8-min recurrence frequency suggests that intermittent reconnection may be occurring .Measurements (appropriately lagged) of the solar wind at ACE show that the IMF was southward-oriented with a strong B(sub X) and that a modest dynamic pressure increased as the events started. The multi-point observations afforded by the Cluster spacecraft were used to infer the motion (direction and speed) of the observed magnetic field reversals. The associated currents were also calculated and they are consistent with the spatial confinement of the observed magnetic field reversals. We propose that the observed reversals are due to flux tubes reconnecting with closed field lines on the dayside. Ancillary data from the Cluster Ion Spectrometry (CIS) and Plasma Electron And Current Experiment (PEACE) instruments were used to develop a physical picture of the reversals.

  4. Preliminary analysis of the Intensive Observation Period events occurred in Italy during the HyMeX campaign

    NASA Astrophysics Data System (ADS)

    Ferretti, Rossella

    2013-04-01

    HyMeX (Hydrological cycle in the Mediterranean eXperiment) is a project aimed at a better understanding and quantification of the hydrological cycle and related processes in the Mediterranean. As a part of HyMeX, Special Observation Periods (SOPs) are dedicated to provide detailed and specific observations to study key processes leading to orographic precipitation (ORP), heavy precipitation events (HPEs), and flash flood events (FFEs) in certain Target Areas (TAs). Informed by numerical weather forecasts and standard observations, Intensive Operation Periods (IOPs) are declared during the SOPs. Specific observations in the TAs are provided by operational measurements (ground meteorological networks, soundings, and remote-sensing instruments), coupled with specific measurements during IOPs from several instruments, such as disdrometers, sodars, lidars, research radars, extra soundings, etc. In this paper an overview is presented of the HyMeX IOPs in Italy during SOP1 (5 September - 6 November, 2012). The Hydro-Meteorological sites of interest were: Liguria-Tuscany (LT), northeastern Italy (NEI) and central Italy (CI). Typical situations encountered for HPEs in LT involved upper-level southwesterly flow with low-level moist southerly or southeasterly flow over the Tyrrhenian and the Ligurian Sea. Highlights include a measurement of 300 mm/24h of rain at the border between Liguria and Emilia on Sept. 26, 2012 during IOP7b. For NEI region, HPEs mainly occurred with upper level southwesterly flow ahead of advancing troughs with low-level moist southerly or southeasterly flow over the Adriatic Sea. Highlights include 120 mm/24h of rain in Friuli Venezia Giulia on Sept. 12, 2012 during IOP2. For CI region, HPEs and FFEs, a slowly propagating cut-off low centered over southern Italy was observed; the associated easterly flow on the north side of the cut-off low would frequently bring moisture into east central Italy from the Adriatic Sea. Highlights include an event with

  5. Periodicity in marine extinction events

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. John, Jr.; Raup, David M.

    1986-01-01

    The periodicity of extinction events is examined in detail. In particular, the temporal distribution of specific, identifiable extinction events is analyzed. The nature and limitations of the data base on the global fossil record is discussed in order to establish limits of resolution in statistical analyses. Peaks in extinction intensity which appear to differ significantly from background levels are considered, and new analyses of the temporal distribution of these peaks are presented. Finally, some possible causes of periodicity and of interdependence among extinction events over the last quarter billion years of earth history are examined.

  6. Operation of a digital seismic network on Mount St. Helens volcano and observations of long period seismic events that originate under the volcano

    SciTech Connect

    Fehler, M.; Chouet, B.

    1982-09-01

    A 9 station digital seismic array was operated on Mount St. Helens volcano in Washington State during 1981. One of the stations was placed inside the crater of the volcano, six were located on the flanks of the volcano within two km of the crater and two were approximately ten km from the crater. Four of the instruments recorded three components of motion and the remaining five recorded only the vertical component. A one day experiment was carried out during which the crater monitoring seismometer was complimented by the addition of two ink recording instruments. During the one day experiment six observers recorded times of rockfall, felt-earthquake occurrences, and changes in steam emissions from the dome in the crater. Using information obtained during the one day experiment seismic events recorded by the digital instruments were classified as earthquakes, rockfalls, helicopter noise and a type of event that is unique to volcanoes which is called long period. Waveforms of these long period events have a duration of up to 30 seconds and a spectrum that is peaked at approximately 2 Hz. The frequency at which the peak in the spectrum occurs is nearly the same at all stations which means that the unique waveform of long period events is due to a source effect, not a path effect. The peak frequency is fairly insensitive to the amplitude of the signal which means that the size of the source region is constant, independent of the signal amplitude. Long period events were not felt and were accompanied by no visible changes inside the crater which lead to the conclusion that they are some sort of seismic disturbance generated inside the Volcano.

  7. Auroral activities observed by SNPP VIIRS day/night band during a long period geomagnetic storm event on April 29-30, 2014

    NASA Astrophysics Data System (ADS)

    Shao, Xi; Cao, Changyong; Liu, Tung-chang; Zhang, Bin; Wang, Wenhui; Fung, Shing F.

    2015-10-01

    The Day/Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP represents a major advancement in night time imaging capabilities. The DNB senses radiance that can span 7 orders of magnitude in one panchromatic (0.5-0.9 μm) reflective solar band and provides imagery of clouds and other Earth features over illumination levels ranging from full sunlight to quarter moon. When the satellite passes through the day-night terminator, the DNB sensor is affected by stray light due to solar illumination on the instrument. With the implementation of stray light correction, stray light-corrected DNB images enable the observation of aurora occurred in the high latitude regions during geomagnetic storms. In this paper, DNB observations of auroral activities are analyzed during a long period (> 20 hours) of geomagnetic storm event occurred on Apr. 29-30, 2014. The storm event has the Bz component of interplanetary magnetic field (IMF) pointing southward for more than 20 hours. During this event, the geomagnetic storm index Dst reached -67 nT and the geomagnetic auroral electrojet (AE) index increased and reached as high as 1200 nT with large amplitude fluctuations. The event occurred during new moon period and DNB observation has minimum moon light contamination. During this event, auroras are observed by DNB for each orbital pass on the night side (~local time 1:30am) in the southern hemisphere. DNB radiance data are processed to identify regions of aurora during each orbital pass. The evolution of aurora is characterized with time series of the poleward and equatorward boundary of aurora, area, peak radiance and total light emission of the aurora in DNB observation. These characteristic parameters are correlated with solar wind and geomagnetic index parameters. It is found that the evolution of total area-integrated radiance of auroral region over the southern hemisphere correlated well with the ground geomagnetic AE index with correlation

  8. A Peculiar Lapse of Periodic Eclipsing Event at Low Mass X-ray Binary GRS 1747-312 during Suzaku Observation in 2009

    NASA Astrophysics Data System (ADS)

    Saji, Shigetaka; Mori, Hideyuki; Matsumoto, Hironori; Dotani, Tadayasu; Iwai, Masachika; Maeda, Yoshitomo

    2015-08-01

    The Low Mass X-ray Binary (LMXB) GRS 1747-312 is a part of the globular cluster Terzan 6, located at a distance of 9.5 kpc from the Earth. Based on previous observations performed with BeppoSAX and RXTE, recurrent outbursts are known to occur with an interval of about 130-142 days. During the outbursts, periodic eclipses were discovered. During an eclipsing event, its flux declined precipitously by two orders of magnitude compared to its pre-eclipsing state. The periodic nature and its characteristic decline imply that this is likely a bona fide eclipsing event by an orbiting star. The duration (d) and orbital period (P) were estimated to be d = 2596 sec and P = 0.514980303 days.To investigate further, observations for outbursts were performed with Chandra (2004) and Swift (2013). In addition, XMM-Newton (2004) and Suzaku (2009) caught it at the quiescent state. All of the observations except for XMM-Newton included the time of the eclipses predicted. We analyzed archival data of these observations. The measured 0.5-10 keV flux were 5.7 × 10-10 erg cm-2 s-1 (Chandra), 2.0 × 10-13 (XMM), 1.1 × 10-11 (Suzaku) and 4.4 × 10-10 (Swift). During the Chandra and Swift observations, we found a sudden declining in the observed flux at the expected time of the eclipses. During the Suzaku observation, however, there were no signs for the predicted eclipses.Except for the Suzaku observation, the spectra were well described with a combination of blackbody and Comptonized emission models, commonly used for fitting on the spectra of LMXBs. The Suzaku spectrum, on the other hand, could be described with a Comptonized component covered partially by an absorber with NH ˜ 1023 cm-2 and covering fraction of ˜ 0.9. The spectrum had been becoming softer during the Suzaku observation. The softening may be explained by gradual decrease in the column density and covering fraction of the absorber. The spectral interpretation was consistent with the vanishing of the eclipses: the heavy

  9. Modeling event-related heart period responses.

    PubMed

    Paulus, Philipp C; Castegnetti, Giuseppe; Bach, Dominik R

    2016-06-01

    Cardiac rhythm is generated locally in the sinoatrial node, but modulated by central neural input. This may provide a possibility to infer central processes from observed phasic heart period responses (HPR). Currently, operational methods are used for HPR analysis. These methods embody implicit assumptions on how central states influence heart period. Here, we build an explicit psychophysiological model (PsPM) for event-related HPR. This phenomenological PsPM is based on three experiments involving white noise sounds, an auditory oddball task, and emotional picture viewing. The model is optimized with respect to predictive validity-the ability to separate experimental conditions from each other. To validate the PsPM, an independent sample of participants is presented with auditory stimuli of varying intensity and emotional pictures of negative and positive valence, at short intertrial intervals. Our model discriminates these experimental conditions from each other better than operational approaches. We conclude that our PsPM is more sensitive to distinguish experimental manipulations based on heart period data than operational methods, and furnishes a principled approach to analysis of HPR. PMID:26849101

  10. Interferometric observation of microlensing events

    NASA Astrophysics Data System (ADS)

    Cassan, Arnaud; Ranc, Clément

    2016-05-01

    Interferometric observations of microlensing events have the potential to provide unique constraints on the physical properties of the lensing systems. In this work, we first present a formalism that closely combines interferometric and microlensing observable quantities, which lead us to define an original microlensing (u, v) plane. We run simulations of long-baseline interferometric observations and photometric light curves to decide which observational strategy is required to obtain a precise measurement on vector Einstein radius. We finally perform a detailed analysis of the expected number of targets in the light of new microlensing surveys (2011+) which currently deliver 2000 alerts per year. We find that a few events are already at reach of long-baseline interferometers (CHARA, VLTI), and a rate of about six events per year is expected with a limiting magnitude of K ≃ 10. This number would increase by an order of magnitude by raising it to K ≃ 11. We thus expect that a new route for characterizing microlensing events will be opened by the upcoming generations of interferometers.

  11. Peculiar lapse of periodic eclipsing event at low-mass X-ray binary GRS 1747-312 during Suzaku observation in 2009

    NASA Astrophysics Data System (ADS)

    Saji, Shigetaka; Mori, Hideyuki; Matsumoto, Hironori; Dotani, Tadayasu; Iwai, Masachika; Maeda, Yoshitomo; Mitsuishi, Ikuyuki; Ozaki, Masanobu; Tawara, Yuzuru

    2016-03-01

    GRS 1747-312 is a neutron star low-mass X-ray binary in the globular cluster Terzan 6, located at a distance of 9.5 kpc from the Earth. During its outbursts, periodic eclipses were known to occur. Observations for the outbursts were performed with Chandra in 2004 and Swift in 2013. XMM-Newton observed its quiescent state in 2004. In addition, when Suzaku observed it in 2009 as a part of Galactic center mapping observations, GRS 1747-312 was found to be in a low-luminosity state with Lx ˜ 1.2 × 1035 erg s-1. All of the observations except for XMM-Newton included the time of the eclipses predicted. We analyzed archival data of these observations. During the Chandra and Swift observations, we found clear flux decreases at the expected time of the eclipses. During the Suzaku observation, however, there were no clear signs for the predicted eclipses. The lapse of the predicted eclipses during the Suzaku observation can be explained by a contaminant source quite close to GRS 1747-312. When GRS 1747-312 is in the quiescent state, we observe X-rays from the contaminant source rather than from GRS 1747-312. However, we have no clear evidence for the contaminant source in our data. The lapse might also be explained by thick material (NH > 1024 cm-2) between the neutron star and the companion star, though the origin of the thick material is not clear.

  12. Peculiar lapse of periodic eclipsing event at low-mass X-ray binary GRS 1747-312 during Suzaku observation in 2009

    NASA Astrophysics Data System (ADS)

    Saji, Shigetaka; Mori, Hideyuki; Matsumoto, Hironori; Dotani, Tadayasu; Iwai, Masachika; Maeda, Yoshitomo; Mitsuishi, Ikuyuki; Ozaki, Masanobu; Tawara, Yuzuru

    2016-06-01

    GRS 1747-312 is a neutron star low-mass X-ray binary in the globular cluster Terzan 6, located at a distance of 9.5 kpc from the Earth. During its outbursts, periodic eclipses were known to occur. Observations for the outbursts were performed with Chandra in 2004 and Swift in 2013. XMM-Newton observed its quiescent state in 2004. In addition, when Suzaku observed it in 2009 as a part of Galactic center mapping observations, GRS 1747-312 was found to be in a low-luminosity state with Lx ˜ 1.2 × 1035 erg s-1. All of the observations except for XMM-Newton included the time of the eclipses predicted. We analyzed archival data of these observations. During the Chandra and Swift observations, we found clear flux decreases at the expected time of the eclipses. During the Suzaku observation, however, there were no clear signs for the predicted eclipses. The lapse of the predicted eclipses during the Suzaku observation can be explained by a contaminant source quite close to GRS 1747-312. When GRS 1747-312 is in the quiescent state, we observe X-rays from the contaminant source rather than from GRS 1747-312. However, we have no clear evidence for the contaminant source in our data. The lapse might also be explained by thick material (NH > 1024 cm-2) between the neutron star and the companion star, though the origin of the thick material is not clear.

  13. Observations of flux transfer events

    NASA Astrophysics Data System (ADS)

    Farrugia, C. J.; Southwood, D. J.; Cowley, S. W. H.

    A decade of research on flux transfer events (FTEs) has supported their interpretation as signatures of reconnection between the solar and terrestrial magnetic fields. Some of the observational evidence is reviewed. Another observational signature of reconnection has been studied in the literature: high speed plasma flows satisfying approximately stress balance calculations. A well-documented crossing of the magnetopause is revisited to show how these signatures, which are prima facie so diverse and which have hitherto been studied in isolation, can be understood in terms of unsteady Petschek reconnection occurring at the magnetopause. A review of some works on FTEs using data from the AMPTE spacecraft highlights the advances made possible by that mission.

  14. Identifying multiple periodicities in sparse photon event time series

    NASA Astrophysics Data System (ADS)

    Koen, Chris

    2016-07-01

    The data considered are event times (e.g. photon arrival times, or the occurrence of sharp pulses). The source is multiperiodic, or the data could be multiperiodic because several unresolved sources contribute to the time series. Most events may be unobserved, either because the source is intermittent, or because some events are below the detection limit. The data may also be contaminated by spurious pulses. The problem considered is the determination of the periods in the data. A two-step procedure is proposed: in the first, a likely period is identified; in the second, events associated with this periodicity are removed from the time series. The steps are repeated until the remaining events do not exhibit any periodicity. A number of period-finding methods from the literature are reviewed, and a new maximum likelihood statistic is also introduced. It is shown that the latter is competitive compared to other techniques. The proposed methodology is tested on simulated data. Observations of two rotating radio transients are discussed, but contrary to claims in the literature, no evidence for multiperiodicity could be found.

  15. Identifying Multiple Periodicities in Sparse Photon Event Time Series

    NASA Astrophysics Data System (ADS)

    Koen, Chris

    2016-04-01

    The data considered are event times (e.g. photon arrival times, or the occurrence of sharp pulses). The source is multiperiodic, or the data could be multiperiodic because several unresolved sources contribute to the time series. Most events may be unobserved, either because the source is intermittent, or because some events are below the detection limit. The data may also be contaminated by spurious pulses. The problem considered is the determination of the periods in the data. A two-step procedure is proposed: in the first, a likely period is identified; in the second, events associated with this periodicity are removed from the time series. The steps are repeated until the remaining events do not exhibit any periodicity. A number of period-finding methods from the literature are reviewed, and a new maximum likelihood statistic is also introduced. It is shown that the latter is competitive compared to other techniques. The proposed methodology is tested on simulated data. Observations of two rotating radio transients are discussed, but contrary to claims in the literature, no evidence for multiperiodicity could be found.

  16. The INTIMATE event stratigraphy of the last glacial period

    NASA Astrophysics Data System (ADS)

    Olander Rasmussen, Sune; Svensson, Anders

    2015-04-01

    The North Atlantic INTIMATE (INtegration of Ice-core, MArine and TErrestrial records) group has previously recommended an Event Stratigraphy approach for the synchronisation of records of the Last Termination using the Greenland ice core records as the regional stratotypes. A key element of these protocols has been the formal definition of numbered Greenland Stadials (GS) and Greenland Interstadials (GI) within the past glacial period as the Greenland expressions of the characteristic Dansgaard-Oeschger events that represent cold and warm phases of the North Atlantic region, respectively. Using a recent synchronization of the NGRIP, GRIP, and GISP2 ice cores that allows the parallel analysis of all three records on a common time scale, we here present an extension of the GS/GI stratigraphic template to the entire glacial period. In addition to the well-known sequence of Dansgaard-Oeschger events that were first defined and numbered in the ice core records more than two decades ago, a number of short-lived climatic oscillations have been identified in the three synchronized records. Some of these events have been observed in other studies, but we here propose a consistent scheme for discriminating and naming all the significant climatic events of the last glacial period that are represented in the Greenland ice cores. In addition to presenting the updated event stratigraphy, we make a series of recommendations on how to refer to these periods in a way that promotes unambiguous comparison and correlation between different proxy records, providing a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations. The work presented is a part of a newly published paper in an INTIMATE special issue of Quaternary Science Reviews: Rasmussen et al., 'A stratigraphic framework for abrupt climatic changes during the Last Glacial period based on three synchronized Greenland ice-core records: refining and extending the INTIMATE event

  17. Operation of a digital seismic network on Mount St. Helens volcano and observations of long-period seismic events that originate under the volcano

    SciTech Connect

    Fehler, M.; Chouet, B.

    1982-01-01

    During the period May through October 1981, a nine station digital seismic array was operated on the flanks of Mount St. Helens volcano in the state of Washington. The purpose was to obtain high quality digital seismic data from a dense seismic array operating near and in the summit crater of the volcano to facilitate study of near field seismic waveforms generated under the volcano. Our goal is to investigate the source mechanism of volcanic tremor and seismic activity associated with magma intrusion, dome growth and steam-ash emissions occurring within the crater of Mount St. Helens.

  18. Estimation of Maximum Likelihood of the Unextendable Dead Time Period in a Flow of Physical Events

    NASA Astrophysics Data System (ADS)

    Gortsev, A. M.; Solov'ev, A. A.

    2016-03-01

    A flow of physical events (photons, electrons, etc.) is studied. One of the mathematical models of such flows is the MAP-flow of events. The flow circulates under conditions of the unextendable dead time period, when the dead time period is unknown. The dead time period is estimated by the method of maximum likelihood from observations of arrival instants of events.

  19. HR 1225 - New observations and period search

    NASA Astrophysics Data System (ADS)

    DuPuy, D. L.; Collins, G.; Swingler, D. N.

    1982-02-01

    Four nights of photoelectric observations of the delta Scuti star HR 1225 have been obtained. The light curve has a variable amplitude envelope indicating that more than one period is present. A search for periodicities using the Jurkevich method and Fourier analysis suggests periods of 0.156 d and 0.097 d. A least-squares solution yields a fair fit to the data with these two periods. The Fourier transform suggests that three periods are present.

  20. Calculation of fission observables through event-by-event simulation

    NASA Astrophysics Data System (ADS)

    Randrup, Jørgen; Vogt, Ramona

    2009-08-01

    The increased interest in more exclusive fission observables has demanded more detailed models. We present here a new computational model, FREYA, that aims to meet this need by producing large samples of complete fission events from which any observable of interest can then be extracted consistently, including arbitrary correlations. The various model assumptions are described and the potential utility of the model is illustrated by means of several novel correlation observables.

  1. Calculation of Fission Observables Through Event-by-Event Simulation

    SciTech Connect

    Randrup, J; Vogt, R

    2009-06-04

    The increased interest in more exclusive fission observables has demanded more detailed models. We present here a new computational model, FREYA, that aims to met this need by producing large samples of complete fission events from which any observable of interest can then be extracted consistently, including arbitrary correlations. The various model assumptions are described and the potential utility of the model is illustrated by means of several novel correlation observables.

  2. HR 5960 - New observations and period search

    NASA Astrophysics Data System (ADS)

    DuPuy, D. L.; Burgoyne, L. G.

    1983-01-01

    New photoelectric observations of the Delta Scuti star HR 5960 (CL Dra) obtained on nine closely spaced nights are discussed. It is noted that periodicities in the range of 0.06 d to 0.069 d have already been reported for this star. A Jurkevich periodogram analysis and nonlinear least-squares analysis give a primary period of 0.0676 d, with a secondary period of 0.0493 d. There is still some uncertainty whether the primary period is 0.0676 d or 0.0685 d. On the average, 55 observations of the variable were obtained each night, with an average interval of 5.5 minutes between observations. The air mass of the observations varied from 1.06 to 1.3. In all, 492 observations of the variable star were made.

  3. Solar Energetic Particle Events Observed by MAVEN

    NASA Astrophysics Data System (ADS)

    Lee, C. O.; Larson, D. E.; Lillis, R. J.; Luhmann, J. G.; Halekas, J. S.; Brain, D.; Connerney, J. E. P.; Espley, J. R.; Epavier, F.; Thiemann, E.; Zeitlin, C.; Jakosky, B. M.

    2015-12-01

    We present observations of solar energetic particle (SEP) events made by the Mars Atmosphere and Volatile EvolutioN (MAVEN) SEP instrument, which measures energetic ions and electrons impacting the upper Martian atmosphere. Since the arrival of the MAVEN spacecraft at Mars, a large number of solar flares and a few major coronal mass ejections (CMEs) erupted from the Sun. The SEPs are accelerated by the related shock in the solar corona or by the propagating interplanetary shock ahead of the CME ejecta. Mixed in with these SEPs are particles accelerated by the shocks of corotating streams, some of which have recurred for several solar cycles due to the persistent coronal hole sources. The SEP events are analyzed together with the upstream solar wind observations from the MAVEN Solar Wind Ion Analyzer (SWIA) and magnetometer (MAG). The sources of the SEP events are determined from Earth-based solar imagery and the MAVEN Extreme Ultra-violet Monitor (EUVM) together with numerical simulations of the inner heliospheric conditions. A comparison with the radiation dose rate measurements from the Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD) reveals a lack of ground signatures during the onset of the highest energy SEPs for the events observed by MAVEN, indicating that the SEPs fully deposit their energies into the Martian atmosphere. Using measurements made from the ensemble of instruments onboard MAVEN, we investigate the consequences of SEPs at Mars for a number of events observed during the primary science mapping phase of the MAVEN mission.

  4. Observations of Pluto-Charon mutual events

    SciTech Connect

    Blanco, C.; Di Martino, M.; Ferreri, W.; Osservatorio Astronomico, Turin )

    1989-07-01

    As part of the planned 'Pluto-Charon Mutual Eclipse Season Campaign', one mutual event was observed at the ESO Observatory on July 10, 1986 and seven mutual events were observed at the Serra La Nave stellar station of Catania Astrophysical Observatory from April 29 to July 21, 1987. At ESO the measurements were performed at the 61-cm Bochum telescope equipped with a photon-counting system and U, B, V, filters; at Serra La Nave the Cassegrain focus of the 91-cm reflector was equipped with a photon-counting system and B and V filters. The observed light losses and contact times do not show relevant systematic deviations from the predicted ones. An examination of the behavior of the B and V light curves gives slight indications of a different slope of the B and V light loss of the same event for a superior or an inferior event, and shows that the superior events are shallower at wavelengths longer than B. 6 refs.

  5. Molecular clouds and periodic events in the geologic past

    NASA Technical Reports Server (NTRS)

    Thaddeus, P.

    1986-01-01

    The suggestion that a claimed 30 Myr period in the geologic past resulted from cometary impacts following encounters with molecular clouds as the solar system oscillates about the galactic plane poses a well-defined problem in the theory of shot noise. All recent CO surveys of the Galaxy clearly indicate that the concentration of molecular clouds in the galactic plane is not sufficient to allow a statistically significant period to be extracted from the small number of dated events. Of the order of 1000 events is probably required to obtain a credible period.

  6. Conditions for Recurrence of a Flow of Physical Events with Unextendable Dead Time Period

    NASA Astrophysics Data System (ADS)

    Nezhel'skaya, L. A.

    2016-04-01

    A flow of physical events (photons, electrons, etc.) is studied. One of the mathematical models of such flows is the modulated MAP flow of events circulating under conditions of unextendable dead time period. The explicit form of the probability density of interarrival interval of the flow is presented together with the explicit form of the joint probability density of two adjacent intervals in the observed flow. The conditions for recurrence of the observable flow of events are presented.

  7. [Period-tripling in Multiscale Physical and Biological Events].

    PubMed

    Bondar, A T; Fedorov, M V; Kolombet, V A

    2015-01-01

    A recent paper by S.J. Puetz et al. (Chaos, Solitons -& Fractals, v. 62-63, p. 55, 2014) described a fundamental period-tripled model. It involves periods of different astronomical (quasars, Sun), geophysical (geomagnetic, climatic, volcanic) and some biological processes. This work contains statistics for sixteen pairs of a period-tripled sequence. These periods range from -50 years to 1.5 billion years and no signs of the timescale limitations are found. We believe that the universal scope of the fundamental period-tripled model can be used for the development of new methodology of research data analysis: the main idea is that the spectrum of the periods of the studied event should be tested for the similarity with the spectrum of fundamental period-tripling pattern (because of the fundamental nature of the period-tripled model). Using this method, in this study we complement an already described period-tripled model with periods of human memory performance ranging from one minute to one month also adding seven relevant periods/frequencies of the period-tripled model in the range of human hearing. We make a conclusion that these characteristic frequencies may form the basis for music and singing phenomena. The new methodology is particularly appropriate for being applied in medicine and engineering. PMID:26841519

  8. Multispacecraft observations of quasi-periodic emissions

    NASA Astrophysics Data System (ADS)

    Nemec, Frantisek; Picket, Jolene S.; Santolik, Ondrej

    2014-05-01

    Quasi-periodic (QP) emissions are VLF electromagnetic waves in the frequency range of about 0.5-5 kHz which exhibit a periodic time modulation of the wave intensity. The modulation period is usually on the order of a few tens of seconds. The generation mechanism of these emissions is still not understood, but at least in some cases it appears to be related to ULF magnetic field pulsations which result in periodic modifications of the resonant conditions in the source region. We use multipoint measurements of QP emissions by the 4 Cluster spacecraft. The observations are obtained close to the equatorial region at radial distances of about 4 Earth radii, i.e. close to a possible generation region. A combined analysis of the high resolution data obtained by the WBD instruments and the ULF magnetic field data obtained by the FGM instruments allows for a detailed case-study analysis of these unique emissions. The presented analysis benefits from the recent close-separation configuration of three of the Cluster spacecraft (≡20-100 km) and a related timing analysis, which would be impossible otherwise.

  9. Events and Periods as Concepts for Organizing Historical Knowledge

    ERIC Educational Resources Information Center

    Shaw, Ryan Benjamin

    2010-01-01

    Events and periods are not objectively existing phenomena, but "concepts" we use to organize our knowledge of history. They make historical change comprehensible and help us orient ourselves with respect to the history of the culture in which we participate. Thus they are indispensable for describing both the content of history scholarship and the…

  10. Infrasonic observations of large scale HE events

    SciTech Connect

    Whitaker, R.W.; Mutschlecner, J.P.; Davidson, M.B.; Noel, S.D.

    1990-01-01

    The Los Alamos Infrasound Program has been operating since about mid-1982, making routine measurements of low frequency atmospheric acoustic propagation. Generally, we work between 0.1 Hz to 10 Hz; however, much of our work is concerned with the narrower range of 0.5 to 5.0 Hz. Two permanent stations, St. George, UT, and Los Alamos, NM, have been operational since 1983, collecting data 24 hours a day. This discussion will concentrate on measurements of large, high explosive (HE) events at ranges of 250 km to 5330 km. Because the equipment is well suited for mobile deployments, it can easily establish temporary observing sites for special events. The measurements in this report are from our permanent sites, as well as from various temporary sites. In this short report will not give detailed data from all sites for all events, but rather will present a few observations that are typical of the full data set. The Defense Nuclear Agency sponsors these large explosive tests as part of their program to study airblast effects. A wide variety of experiments are fielded near the explosive by numerous Department of Defense (DOD) services and agencies. This measurement program is independent of this work; use is made of these tests as energetic known sources, which can be measured at large distances. Ammonium nitrate and fuel oil (ANFO) is the specific explosive used by DNA in these tests. 6 refs., 6 figs.

  11. Automatic detection of iceberg calving events using seismic observations

    NASA Astrophysics Data System (ADS)

    Andersen, M. L.; Larsen, T.; Hamilton, G. S.; Nettles, M.

    2014-12-01

    Iceberg calving at large, marine-terminating glaciers has been shown to be seismogenic. Seismic energy from these events is released slowly, resulting in characteristic low-frequency signals. The events therefore typically escape detection by traditional systematic methods. Here we show the results of a detection algorithm applied to data observed at two stations, both ~100 km from Helheim Glacier, South East Greenland, in 2007 and 2008 for the purpose of detecting calving-related seismic signals. The detector entails sliding a 150 s wide window over the observed vertical displacement seismograms at steps of one second. Relative power in the 1.1-3.3 s band is monitored, and the detector is activated when a pre-defined threshold is exceeded. We determine the threshold by calibrating the detector with a record of known events observed by time lapse cameras at Helheim Glacier and automatic detections of glacial earthquakes from the GSN (Global Seismic Network) stations. The resulting list of detections is then filtered for events overlapping with tectonic events, both local and global. We observe a clear periodicity in the detections, with most events occurring during the late summer and early fall, roughly coinciding with the end of the melt season. This apparent offset from peak melt intensity leads us to speculate that the pattern in calving is the result of a combination of the seasonal development of multiple physical properties of the glacier, i.e., surface crevassing, subglacial melt and crevassing, and the subglacial drainage system.

  12. Black Hole Observations - Towards the Event Horizon

    NASA Astrophysics Data System (ADS)

    Britzen, Silke

    Black Holes are probably the most elusive solutions of Einstein's theory of General Relativity. Despite numerous observations of the direct galactic environment and indirect influence of astrophysical black holes (e.g. jets, variable emission across the wavelength spectrum, feedback processes, etc.) -- a direct proof of their existence is still lacking. This article highlights some aspects deduced from many observations and concentrates on the experimental results with regard to black holes with masses from millions to billions of solar masses. The focus will be on the challenges and remaining questions. The Event Horizon Telescopce (EHT) project to image the photon sphere of Sgr A* and its potential is briefly sketched. This instrumental approach shall lead to highest resolution observations of the supermassive black hole at the center of the Milky Way (Sgr A*).

  13. Plasma and field observations of a Pc 5 wave event

    NASA Technical Reports Server (NTRS)

    Waite, J. H.; Gallagher, D. L.; Chappell, C. R.; Chandler, M. O.; Olsen, R. C.; Comfort, R. H.; Johnson, J. F. E.; Peterson, W. K.; Weimer, D.; Shawhan, S. D.

    1986-01-01

    The particle detector and electric field data collected by the Dynamo Explorer 1 on the Pc 5 wave event encounter on July 14, 1982 are presented, yielding a nearly complete picture of the event. The overall structure of the Pc 5 seems to order the event into two distinct halves, suggesting a temporal or spatial variation of the micropulsation. Thermal plasma measurements showed that the dominant ion throughout both lobes was H(+). Significant quantities of He(+), O(+), N(+), and O(2+) were also observed to be present and rotating together in a plane normal to the magnetic field direction, due to the Pc5 E x B drift. The plasma parameters determined for the two lobes were used in theoretical calculations to predict the period of the observed resonance.

  14. Validation in the Absence of Observed Events

    DOE PAGESBeta

    Lathrop, John; Ezell, Barry

    2015-07-22

    Here our paper addresses the problem of validating models in the absence of observed events, in the area of Weapons of Mass Destruction terrorism risk assessment. We address that problem with a broadened definition of “Validation,” based on “backing up” to the reason why modelers and decision makers seek validation, and from that basis re-define validation as testing how well the model can advise decision makers in terrorism risk management decisions. We develop that into two conditions: Validation must be based on cues available in the observable world; and it must focus on what can be done to affect thatmore » observable world, i.e. risk management. That in turn leads to two foci: 1.) the risk generating process, 2.) best use of available data. Based on our experience with nine WMD terrorism risk assessment models, we then describe three best use of available data pitfalls: SME confidence bias, lack of SME cross-referencing, and problematic initiation rates. Those two foci and three pitfalls provide a basis from which we define validation in this context in terms of four tests -- Does the model: … capture initiation? … capture the sequence of events by which attack scenarios unfold? … consider unanticipated scenarios? … consider alternative causal chains? Finally, we corroborate our approach against three key validation tests from the DOD literature: Is the model a correct representation of the simuland? To what degree are the model results comparable to the real world? Over what range of inputs are the model results useful?« less

  15. Validation in the Absence of Observed Events

    SciTech Connect

    Lathrop, John; Ezell, Barry

    2015-07-22

    Here our paper addresses the problem of validating models in the absence of observed events, in the area of Weapons of Mass Destruction terrorism risk assessment. We address that problem with a broadened definition of “Validation,” based on “backing up” to the reason why modelers and decision makers seek validation, and from that basis re-define validation as testing how well the model can advise decision makers in terrorism risk management decisions. We develop that into two conditions: Validation must be based on cues available in the observable world; and it must focus on what can be done to affect that observable world, i.e. risk management. That in turn leads to two foci: 1.) the risk generating process, 2.) best use of available data. Based on our experience with nine WMD terrorism risk assessment models, we then describe three best use of available data pitfalls: SME confidence bias, lack of SME cross-referencing, and problematic initiation rates. Those two foci and three pitfalls provide a basis from which we define validation in this context in terms of four tests -- Does the model: … capture initiation? … capture the sequence of events by which attack scenarios unfold? … consider unanticipated scenarios? … consider alternative causal chains? Finally, we corroborate our approach against three key validation tests from the DOD literature: Is the model a correct representation of the simuland? To what degree are the model results comparable to the real world? Over what range of inputs are the model results useful?

  16. Validation in the Absence of Observed Events.

    PubMed

    Lathrop, John; Ezell, Barry

    2016-04-01

    This article addresses the problem of validating models in the absence of observed events, in the area of weapons of mass destruction terrorism risk assessment. We address that problem with a broadened definition of "validation," based on stepping "up" a level to considering the reason why decisionmakers seek validation, and from that basis redefine validation as testing how well the model can advise decisionmakers in terrorism risk management decisions. We develop that into two conditions: validation must be based on cues available in the observable world; and it must focus on what can be done to affect that observable world, i.e., risk management. That leads to two foci: (1) the real-world risk generating process, and (2) best use of available data. Based on our experience with nine WMD terrorism risk assessment models, we then describe three best use of available data pitfalls: SME confidence bias, lack of SME cross-referencing, and problematic initiation rates. Those two foci and three pitfalls provide a basis from which we define validation in this context in terms of four tests-Does the model: … capture initiation? … capture the sequence of events by which attack scenarios unfold? … consider unanticipated scenarios? … consider alternative causal chains? Finally, we corroborate our approach against three validation tests from the DOD literature: Is the model a correct representation of the process to be simulated? To what degree are the model results comparable to the real world? Over what range of inputs are the model results useful? PMID:26198395

  17. Location of Tremor and Long Period Events Using Seismic Amplitudes

    NASA Astrophysics Data System (ADS)

    Battaglia, J.; Battaglia, J.; Ferrazzini, V.; Okubo, P. G.

    2001-12-01

    Tremor and Long Period (LP) events are of particular interest for understanding the behavior of volcanoes as it is assumed that they directly involve fluids in their source mechanisms. However, those events are usually difficult or impossible to locate using traditional arrival times methods, because of their emergent onsets or because they are stationary for a long time. While techniques have been proposed using seismic arrays, this task remains problematic using data from classical short period volcano monitoring networks. A method based on the use of seismic amplitudes was developed on the Piton de la Fournaise (Réunion island) for locating tremor, LP events or rockfalls. For each event, seismic amplitudes are corrected for the site effects at each station using coda amplification factors. The spatial amplitude distributions are usually smooth and coherent, and the decay of the amplitude as a function of distance can be used to locate their source. In Réunion, this method was applied to locate the source(s) of eruption tremor. Those sources are usually found at shallow depth and close to the eruptive vents. An application of this characteristic is the possibility of using eruption tremor for locating the eruptive fissures at the beginning of eruptions. We apply this technique in Hawaii for locating LP events at Kilauea volcano. We calculated coda amplification factors for all stations of the network, and coherent and smooth amplitude distributions are also obtained after correcting for the site effect. We located about 150 events which occurred in January 1998 during an increased phase of LP activity. This seismicity, which peaked on January 15, was related to a surge of magma that reached the Pu`u`O`o vent on January 14, following a rapid inflation of Kilauea's summit. The use of the amplitude method provides a new image of the LP activity. The events appear to cluster in a single group, while they are much more scattered when located using arrival times

  18. 1 CFR 19.4 - Proclamations calling for the observance of special days or events.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... special days or events. 19.4 Section 19.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL... PROCLAMATIONS § 19.4 Proclamations calling for the observance of special days or events. Except as may be... calling for the observance of special days, or other periods of time, or events, shall be assigned by...

  19. 1 CFR 19.4 - Proclamations calling for the observance of special days or events.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... special days or events. 19.4 Section 19.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL... PROCLAMATIONS § 19.4 Proclamations calling for the observance of special days or events. Except as may be... calling for the observance of special days, or other periods of time, or events, shall be assigned by...

  20. 1 CFR 19.4 - Proclamations calling for the observance of special days or events.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... special days or events. 19.4 Section 19.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL... PROCLAMATIONS § 19.4 Proclamations calling for the observance of special days or events. Except as may be... calling for the observance of special days, or other periods of time, or events, shall be assigned by...

  1. 1 CFR 19.4 - Proclamations calling for the observance of special days or events.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... special days or events. 19.4 Section 19.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL... PROCLAMATIONS § 19.4 Proclamations calling for the observance of special days or events. Except as may be... calling for the observance of special days, or other periods of time, or events, shall be assigned by...

  2. 1 CFR 19.4 - Proclamations calling for the observance of special days or events.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... special days or events. 19.4 Section 19.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL... PROCLAMATIONS § 19.4 Proclamations calling for the observance of special days or events. Except as may be... calling for the observance of special days, or other periods of time, or events, shall be assigned by...

  3. Aerosol classification using EARLINET measurements for an intensive observational period

    NASA Astrophysics Data System (ADS)

    Papagiannopoulos, Nikolaos; Mona, Lucia; Pappalardo, Gelsomina

    2016-04-01

    ACTRIS (Aerosols, Clouds and Trace gases Research Infrastructure Network) organized an intensive observation period during summer 2012. This campaign aimed at the provision of advanced observations of physical and chemical aerosol properties, at the delivery of information about the 3D distribution of European atmospheric aerosols, and at the monitoring of Saharan dust intrusions events. EARLINET (European Aerosol Research Lidar Network) participated in the ACTRIS campaign through the addition of measurements according to the EARLINET schedule as well as daily lidar-profiling measurements around sunset by 11 selected lidar stations for the period from 8 June - 17 July. EARLINET observations during this almost two-month period are used to characterize the optical properties and vertical distribution of long-range transported aerosol over the broader area of Mediterranean basin. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, Angstrom exponents) are shown to vary with location and aerosol type. A methodology based on EARLINET observations of frequently observed aerosol types is used to classify aerosols into seven separate types. The summertime Mediterranean basin is prone to African dust aerosols. Two major dust events were studied. The first episode occurred from the 18 to 21 of the June and the second one lasted from 28 June to 6 July. The lidar ratio within the dust layer was found to be wavelength independent with mean values of 58±14 sr at 355 nm and 57±11 sr at 532 nm. For the particle linear depolarization ratio, mean values of 0.27±0.04 at 532 nm have been found. Acknowledgements. The financial support for EARLINET in the ACTRIS Research Infrastructure Project by the European Union's Horizon 2020 research and innovation programme under grant agreement no. 654169 and previously under grant agreement no. 262254 in the Seventh Framework Programme (FP7/2007-2013) is gratefully acknowledged.

  4. Mars atmosphere pressure periodicities from Viking observations

    NASA Technical Reports Server (NTRS)

    Sharman, R. D.; Ryan, J. A.

    1980-01-01

    The first Martian year of pressure data taken by the Viking landers on Mars is subjected to power spectrum analysis. The analysis suggests that strong periodicities are present in the Martian atmosphere, especially at the high-latitude (48 deg N) site of the second lander. Most of these periodicities are probably due to the passage of baroclinic waves. Inspection of individual segments of data shows that the periodicities of the dominant waves vary significantly with time of year. This may be related to the amount of dust in the atmosphere since the dominant frequencies of the waves during times of major dust storms are quite different than at other times.

  5. Protoplasmic Computing to Memorize and Recall Periodic Environmental Events

    NASA Astrophysics Data System (ADS)

    Tero, Atsushi; Saigusa, Tetsu; Nakagaki, Toshiyuki

    Single-celled organisms might be more intelligent than previously envisaged [1]-[5]. The acts of anticipating and recalling events are higher functions performed by the brains of higher animals; their evolutionary origins and the way they self-organize, however, remain open questions. Here we show that an amoeboid organism can anticipate the timing of periodic events. The plasmodium of the true slime mold Physarum polycephalum moves rapidly under favorable conditions, but stops moving when transferred to less-favorable conditions. For example, plasmodia exposed to low temperature and low humidity, presented in three consecutive pulses at constant intervals, reduced their locomotive speed in response to each episode. When favorable conditions were subsequently reintroduced, the plasmodia spontaneously reduced their locomotive speed at the point in time when the next unfavorable episode would have occurred. This implies that the plasmodia are able to anticipate impending environmental change. After this anticipatory response had been evoked several times, the locomotion of the plasmodia returned to normal speed; however, the slowing down could subsequently be induced by a single unfavorable pulse, implying recall of the periodicity that had been memorized. We have explored the mechanisms underlying this behavior from a dynamical systems perspective. Our results suggest that this primitive intelligence is of cellular origin and that simple dynamics might be sufficient to explain its emergence. abstract environment.

  6. A new type of ion injection event observed by Viking

    SciTech Connect

    Yamauchi, M.; Lundin, R.; Woch, J. ); Shapshak, M. ); Elphinstone, R. )

    1993-05-07

    The authors report on the observation of a new type of ion injection event observed by Viking spacecraft several degrees equatorward of the cusp. Its signature seems considerably different than previously reported events such as flux transfer events or impulsive or transient magnetosheath plasma injection events. It consists of low energy ions, as the pattern drops sharply above 100 to 200 eV.

  7. Multiple Flux transfer events observed by Cluster

    NASA Astrophysics Data System (ADS)

    Trenchi, Lorenzo; Trattner, Karlheinz; Fazakerley, Andrew; Fear, Robert; Mihaljcic, Branislav

    2016-07-01

    Time-varying reconnection at the Earth magnetopause generates magnetic structures called Flux Transfer Events (FTE) characterized by the typical bipolar variation in the magnetic field component normal to the magnetopause. Different generation mechanisms have been proposed: the original Russell and Elphic FTE model (1978) predicts a pair of elbow shaped flux tubes of reconnected field lines generated by intermittent and localized reconnection. Alternatively, Lee and Fu (1985) propose that FTEs are caused by reconnection along multiple extended X-lines while a third FTE model is based on bursty reconnection along a single X-line (Scholer et al. 1988; Southwood et al., 1988). In this presentation, we present the detailed analysis of several FTEs sequentially observed by Cluster on 27 March 2007. While the Grad Shafranov analysis gives FTE orientations completely different from each other that are more in agreement with the Russell and Elphic model, the FTE orientations obtained from multi-spacecraft timing, which are probably more reliable, have smaller deviations with respect to the X line orientation, and are therefore more consistent with the extended X line models. Most of these FTEs are associated with a single reconnection jet, moving in the same direction of the FTEs, which appears consistently at the trailing edge of the FTEs. This signature suggests a generation mechanism based on single X line reconnection. We also used the Grad Shafranov reconstruction to recover the field topology of a large FTE, which is not associated with reconnection jets. The reconstruction suggests that this FTE is a flux rope with nested helical field lines, which is expected in the multiple X line reconnection. A possible interpretation suggests that both single X line and multiple X line generation mechanisms contributed to the formation of the FTEs during this magnetopause crossing.

  8. Observation of monojet events and tentative interpretation

    NASA Astrophysics Data System (ADS)

    Buskulic, D.; Casper, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Odier, P.; Pietrzyk, B.; Ariztazabal, F.; Chmeissani, M.; Crespo, J. M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Gaitan, V.; Garrido, Ll.; Martinez, M.; Mattison, T.; Orteu, S.; Pacheco, A.; Padilla, C.; Palla, F.; Pascual, A.; Perlas, J. A.; Teubert, F.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Marinelli, N.; Natali, S.; Nuzzo, S.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Chai, Y.; Huang, D.; Huang, X.; Lin, J.; Wang, T.; Xie, Y.; Xu, D.; Zhang, J.; Zhang, L.; Zhao, W.; Donvicini, G.; Boudreau, J.; Comas, P.; Coyle, P.; Drevermann, H.; Engelhardt, A.; Foà, L.; Forty, R. W.; Ganis, G.; Gay, C.; Girone, M.; Hagelberg, R.; Harvey, J.; Jacobsen, R.; Jost, B.; Knobloch, J.; Lehraus, I.; Maggi, M.; Markou, C.; Martin, E. B.; Mato, P.; Meinhard, H.; Minten, A.; Miquel, R.; Palazzi, P.; Pater, J. R.; Perrodo, P.; Pusztaszeri, J.-F.; Ranjard, F.; Rolandi, L.; Rothberg, J.; Saich, M.; Schlatter, D.; Schmelling, M.; Tejessy, W.; Tomalin, I. R.; Veenhof, R.; Venturi, A.; Wachsmuth, H.; Wasserbaech, S.; Wiedenmann, W.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Bardadin-Otwinowska, M.; Barres, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Saadi, F.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Johnson, S. D.; Møllerud, R.; Nilsson, B. S.; Kyriakis, A.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Passalacqua, L.; Rougé, A.; Rumpf, M.; Tanaka, R.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Veitch, E.; Focardi, E.; Parrini, G.; Corden, M.; Delfino, M.; Georgiopoulos, C.; Jaffe, D. E.; Levinthal, D.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Pepe-Altarelli, M.; Salomone, S.; Colrain, P.; Ten Have, I.; Knowles, I. G.; Lynch, J. G.; Maitland, W.; Morton, W. T.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Smith, M. G.; Thompson, A. S.; Thorn, S.; Turnbull, R. M.; Becker, U.; Braun, O.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Putzer, A.; Rensch, B.; Schmidt, M.; Stenzel, H.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Cattaneo, M.; Colling, D. J.; Dornan, P. J.; Hassard, J. F.; Konstantinidis, N.; Moneta, L.; Moutoussi, A.; Nash, J.; Payne, D. G.; San Martin, G.; Sedgbeer, J. K.; Wright, A. G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Vogl, R.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Jackson, D.; Keemer, N. R.; Nuttall, M.; Patel, A.; Sloan, T.; Snow, S. W.; Whelan, E. P.; Galla, A.; Greene, A. M.; Kleinknecht, K.; Raab, J.; Renk, B.; Sander, H.-G.; Schmidt, H.; Walther, S. M.; Wanke, R.; Wolf, B.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Calvet, D.; Carr, J.; Diaconu, C.; Etienne, F.; Nicod, D.; Payre, P.; Roos, L.; Rousseau, D.; Schwemling, P.; Talby, M.; Abt, I.; Adlung, S.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Cattaneo, P.; Dehning, B.; Dietl, H.; Dydak, F.; Frank, M.; Halley, A. W.; Jakobs, K.; Kroha, H.; Lauber, J.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Schröder, J.; Schwarz, A. S.; Settles, R.; Seywerd, H.; Stierlin, U.; Stiegler, U.; St. Denis, R.; Wolf, G.; Alemany, R.; Boucrot, J.; Callot, O.; Cordier, A.; Courault, F.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacquet, M.; Janot, P.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Musolino, G.; Nikolic, I.; Park, H. J.; Park, I. C.; Schune, M.-H.; Simion, S.; Veillet, J.-J.; Videau, I.; Abbaneo, D.; Bagliwsi, G.; Batignani, G.; Bottigli, U.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Ferrante, I.; Fidecaro, F.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Rizzo, G.; Sanguinetti, G.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Gao, Y.; Green, M. G.; Johnson, D. L.; March, P. V.; Medcalf, T.; Mir, Ll. M.; Quazi, I. S.; Strong, J. A.; Bertin, V.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Edwards, M.; Norton, P. R.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Duarte, H.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Si Mohand, D.; Vallage, B.; Johnson, R. P.; Litke, A. M.; Taylor, G.; Wear, J.; Beddall, A.; Booth, C. N.; Cartwright, S.; Combley, F.; Dawson, I.; Koksal, A.; Rankin, C.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Feigl, E.; Grupen, C.; Lutters, G.; Minguet-Rodriguez, J.; Rivera, F.; Saraiva, P.; Schäfer, U.; Smolik, L.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Pitis, L.; Ragusa, F.; Bellantoni, L.; Conway, J. S.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; Grahl, J.; Harton, J. L.; Hayes, O. J.; Hu, H.; Nachtman, J. M.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I.; Sharma, V.; Turk, J. D.; Walsh, A. M.; Weber, F. V.; San Lan Wu; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.; Aleph Collaboration

    1994-08-01

    A data sample corresponding to almost two million hadronic Z decays collected by the ALEPH detector at LEP has been searched for monojet events. Three events were found, in agreement with the expectation from the process ee→γ*vvbar, with γ*→ffbar. Two events are hadronic, the third one being an e+e- pair. All monojet masses are in excess of 3 GeV/c2, and two of the event have large transverse momenta: 18.5 and 20.3 GeV/c. These kinematic characteristics are quite unlikely in the process ee→γ*vvbar. The probability of their occurence increases substantially when processes involving further Z or W exchanges are taken into account, but still remains at the 5% level.

  9. Determination of Main Periodicities in Solar Wind and Magnetosphere Data During HILDCAAs Events Using Wavelet Analysis

    NASA Astrophysics Data System (ADS)

    de Souza, A. M.; Echer, E.; Bolzam, M. J. A.

    2015-12-01

    The High-Intensity Long-Duration Continuous AE activity events (HILDCAAs) were first identified by Tsurutani and Gonzalez (1987), when they studied geomagnetic storms with a recovery phase longer than what is generally observed. They have used four criteria for defining the HILDCAA events, that are: First, the AE index must be 1000 nT at least once during the event; second, the event must be at last two days long; third, the AE index can not decay more than 200 nT for longer than two hours in each time; finally, the event must occurs outside of the main phase of the geomagnetic storm. Although several works have been done recently on HILCAAS, the main periodicities in solar wind and magnetosphere parameters during these events are still not well know. It is the aim of this work to determine these periods. In order to conduct this study, the global spectrum wavelet was used to determine the main periods of HILDCAA events. The 1-minute AE index and the Bz component of the interplanetary magnetic field (IMF) were used to characterize the magnetosphic and solar wind. We have used data of events that occurred between 1975 and 2011 for the AE index, and between 1995 and 2011 for Bz component of the IMF (GSE and GSM coordinates systems). During HILDCAAs events, the main periods found in the AE index were between 4 and 12 hours, corresponding to 50% of the total periods identified. For the Bz component, the main periods were ≤ 8 hours, independently of the coordinate system used. We conjecture that those periods can be associates with Alfvén waves that present periods between 1 and 10 hours. These Alfven waves are associated to coronal holes because the HILDCAAs events occur more often in the descending phase of solar cycles, when the high speed streams are dominant and it are emitted from coronal holes. Cross-wavelet analysis results between IMF Bz and AE are also presented and discussed.

  10. IRIS and SDO Observations of Recurrent Explosive Events

    NASA Astrophysics Data System (ADS)

    Gupta, G. R.; Tripathi, Durgesh

    2015-08-01

    Observations of recurrent explosive events (EEs) with timescales of 3–5 minutes are reported. These EEs have been observed with the Interface Region Imaging Spectrograph (IRIS) and have a spatial dimension of ∼ 1\\buildrel{\\prime\\prime}\\over{.} 5 along the slit. The spectral line profiles of C ii 1335/1336 Å and Si iv 1394/1403 Å become highly broadened both in red as well as blue wings. Several absorption lines on top of the broadened profiles were identified. In addition, emission lines corresponding to neutral lines such as Cl i 1351.66 Å, C i 1354.29 Å, and C i 1355.84 Å were identified. The C i 1354.29 Å and C i 1355.84 Å lines were found only during the EEs, whereas Cl i 1351.66 Å broadens during the EEs. The estimated lower limit on electron number density obtained using the line ratios of Si iv and O iv is about {10}13.5 cm‑3, suggesting that the observed events are most likely occurring at heights corresponding to a lower chromosphere. To the best of our knowledge, for the first time we have detected short-period variability (30 s and 60–90 s) within the EE bursts. Observations of the photospheric magnetic fields underneath EEs indicate that a negative polarity field emerges in the neighborhood of oppositely directed positive fields that undergo repetitive reconnection (magnetic flux cancellation) events. The dynamic changes observed in AIA 1700 Å, 1600 Å, C ii 1330 Å, and Si iv 1400 Å intensity images corresponded very well with the emergence and cancellation of photospheric magnetic field (negative polarity) on a timescale of 3–5 minutes. The observations reported here suggest that these EEs are formed due to magnetic reconnection and are occurring in the lower chromosphere.

  11. Sensitivity analyses for partially observed recurrent event data.

    PubMed

    Akacha, Mouna; Ogundimu, Emmanuel O

    2016-01-01

    Recurrent events involve the occurrences of the same type of event repeatedly over time and are commonly encountered in longitudinal studies. Examples include seizures in epileptic studies or occurrence of cancer tumors. In such studies, interest lies in the number of events that occur over a fixed period of time. One considerable challenge in analyzing such data arises when a large proportion of patients discontinues before the end of the study, for example, because of adverse events, leading to partially observed data. In this situation, data are often modeled using a negative binomial distribution with time-in-study as offset. Such an analysis assumes that data are missing at random (MAR). As we cannot test the adequacy of MAR, sensitivity analyses that assess the robustness of conclusions across a range of different assumptions need to be performed. Sophisticated sensitivity analyses for continuous data are being frequently performed. However, this is less the case for recurrent event or count data. We will present a flexible approach to perform clinically interpretable sensitivity analyses for recurrent event data. Our approach fits into the framework of reference-based imputations, where information from reference arms can be borrowed to impute post-discontinuation data. Different assumptions about the future behavior of dropouts dependent on reasons for dropout and received treatment can be made. The imputation model is based on a flexible model that allows for time-varying baseline intensities. We assess the performance in a simulation study and provide an illustration with a clinical trial in patients who suffer from bladder cancer. PMID:26540016

  12. Earthquake nucleation mechanisms and periodic loading: Models, Experiments, and Observations

    NASA Astrophysics Data System (ADS)

    Dahmen, K.; Brinkman, B.; Tsekenis, G.; Ben-Zion, Y.; Uhl, J.

    2010-12-01

    The project has two main goals: (a) Improve the understanding of how earthquakes are nucleated ¬ with specific focus on seismic response to periodic stresses (such as tidal or seasonal variations) (b) Use the results of (a) to infer on the possible existence of precursory activity before large earthquakes. A number of mechanisms have been proposed for the nucleation of earthquakes, including frictional nucleation (Dieterich 1987) and fracture (Lockner 1999, Beeler 2003). We study the relation between the observed rates of triggered seismicity, the period and amplitude of cyclic loadings and whether the observed seismic activity in response to periodic stresses can be used to identify the correct nucleation mechanism (or combination of mechanisms). A generalized version of the Ben-Zion and Rice model for disordered fault zones and results from related recent studies on dislocation dynamics and magnetization avalanches in slowly magnetized materials are used in the analysis (Ben-Zion et al. 2010; Dahmen et al. 2009). The analysis makes predictions for the statistics of macroscopic failure events of sheared materials in the presence of added cyclic loading, as a function of the period, amplitude, and noise in the system. The employed tools include analytical methods from statistical physics, the theory of phase transitions, and numerical simulations. The results will be compared to laboratory experiments and observations. References: Beeler, N.M., D.A. Lockner (2003). Why earthquakes correlate weakly with the solid Earth tides: effects of periodic stress on the rate and probability of earthquake occurrence. J. Geophys. Res.-Solid Earth 108, 2391-2407. Ben-Zion, Y. (2008). Collective Behavior of Earthquakes and Faults: Continuum-Discrete Transitions, Evolutionary Changes and Corresponding Dynamic Regimes, Rev. Geophysics, 46, RG4006, doi:10.1029/2008RG000260. Ben-Zion, Y., Dahmen, K. A. and J. T. Uhl (2010). A unifying phase diagram for the dynamics of sheared solids

  13. Testing Quantum Mechanics with Observations of Causally Disconnected Cosmological Events

    NASA Astrophysics Data System (ADS)

    Friedman, Andrew S.; Kaiser, D. I.; Gallicchio, J.; Guth, A. H.

    2014-01-01

    We discuss a thought experiment which would leverage cosmology to test quantum mechanics using astronomical observations. Specifically, we aim to close the "settings-independence" loophole in experimental tests of Bell's inequality by choosing the detector settings (e.g. polarizer orientations) using real-time observations of causally disconnected cosmic sources. This would help close one of the most important remaining Bell test loopholes whereby a local hidden variable theory could mimic the quantum predictions if the experimental settings choices shared even a small correlation due to unknown local causal influences prior to the experiment. The talk will focus on the theoretical cosmology constraints needed to choose optimal sources for such an experiment, describing general conditions for pairs of cosmic events with arbitrary redshifts and angular separations to have shared causal pasts in Friedman-Lemaitre-Robertson-Walker universes with arbitrary curvature, including flat, dark energy dominated, accelerating universes like our own. While causally disjoint patches of the cosmic microwave background radiation at redshift z ~ 1090 could be used to set the detectors, z > 3.65 quasars observed at optical wavelengths are arguably the optimal candidate source pairs using present technology that meet the condition of having no shared causal past since the end of any period of inflation, 13.82 Gyr ago. Results are illustrated for our universe with causal structure animations to help visualize the intersections of past light cones for arbitrary event pairs.

  14. Long-period events and tremor at Popocatepetl volcano (1994-2000) and their broadband characteristics

    USGS Publications Warehouse

    Arciniega-Ceballos, A.; Chouet, B.; Dawson, P.

    2003-01-01

    Following an initial phreatic eruption on 21 December 1994, activity at Popocatepetl has been dominated by fumarolic emissions interspersed with more energetic emissions of ashes and gases. A phase of repetitive dome-building and dome-destroying episodes began in March 1996 and is still ongoing at present. We describe the long-period (LP) seismicity accompanying eruptive activity at Popocatepetl from December 1994 through May 2000, using data from a three-component broadband seismometer located 5 km from the summit crater. The broadband records display a variety of signals, with periods ranging in the band 0.04-90 s. Long-period events and tremor with typical dominant periods in the range 0.3-2.0 s are the most characteristic signals observed at Popocatepetl. These signals appear to reflect volumetric sources driven by pressure fluctuations associated with the unsteady transport of gases beneath the crater. Very-long-period (VLP) signals are also observed in association with LP events and tremor. The VLP signals which accompany LP events display Ricker-like wavelets with periods near 36 s, whereas VLP signals associated with tremor waveforms typically show sustained oscillations at periods ranging up to 90 s. The spectra and particle motion patterns remain similar from event to event for the majority of LP and tremor signals analyzed during the time span of this study, suggesting a repeated, non-destructive activation of a common source. Hypocenters determined by phase pick analyses of selected LP events recorded by the seven-station, permanent Popocatepetl short-period network suggest that the majority of these events are confined to a source region in the top 1.5 km below the crater floor. The repetitive occurrences of VLP signals with closely matched waveform characteristics are consistent with a non-destructive reactivation of at least two sources. One source appears to coincide with the main source region of LP seismicity, whereas the second is a deeper source

  15. A flare event of the long-period RS Canum Venaticorum system IM Pegasi

    NASA Technical Reports Server (NTRS)

    Buzasi, Derek L.; Ramsey, Lawrence W.; Huenemoerder, David P.

    1987-01-01

    The characteristics of a flare event detected on the long-period RS CVn system IM Pegasi are reported. The low-resolution spectrum show enhancements of up to a factor of five in some emission lines. All of the ultraviolet emission lines normally visible are enhanced significantly more than the normal 30 rotational modulation. Emission fluxes of both the quiescent and flare event are used to construct models of the density and temperature variation with height. These models reveal a downward shift of the transition region during the flare. Scaled models of the quiet and flaring solar outer atmosphere are used to estimate the filling factor of the flare event at about 30 percent of the stellar surface. The pattern of line enhancements in the flare is the same as a previous event in Lambda Andromeda observed previously.

  16. JCMT Observations of the Deep Impact Event

    NASA Astrophysics Data System (ADS)

    Coulson, I. M.; Butner, H. M.; Moriarty-Schieven, G.; Woodney, L. M.; Charnley, S. B.; Rodgers, S. D.; Stüwe, J.; Schulz, R.; Meech, K. J.; Fernández, Y.; Vora, P.

    Spectroscopic observations were made from the James Clerk Maxwell Telescope of comet 9P/Tempel 1 before, during and after the impact by the NASA spacecraft Deep Impact on UT 04 July 2005. Several molecular species (HCN, CH3OH, CO, CS, HCO+) were targeted but none was detected. Nonetheless, upper limits on emission line strengths may weakly constrain the chemical composition of the ices in the excavated part of the comet nucleus. Preliminary analysis of the HCN data is presented here.

  17. Semi-Periodic Sequences and Extraneous Events in Earthquake Forecasting: I. Theory and Method, Parkfield Application

    NASA Astrophysics Data System (ADS)

    Nava Pichardo, Fidencio Alejandro; Quinteros Cartaya, Claudia Beatriz; Glowacka, Ewa; Frez Cárdenas, José Duglas

    2014-07-01

    We present a new method to identify semi-periodic sequences in the occurrence times of large earthquakes, which allows for the presence of multiple semi-periodic sequences and/or events not belonging to any identifiable sequence in the time series. The method, based on the analytic Fourier transform, yields estimates of the departure from periodicity of an observed sequence, and of the probability that the sequence is not due to chance. These estimates are used to make and to evaluate forecasts of future events belonging to each sequence. Numerous tests with synthetic catalogs show that the method is surprisingly capable of correctly identifying sequences, unidentifiable by eye, in complicated time series. Correct identification of a given sequence depends on the number of events it contains, on the sequence's departure from periodicity, and, in some cases, on the choice of starting and ending times of the analyzed time window; as well as on the total number of events in the time series. Some particular data combinations may result in spectra where significant periods are obscured by large amplitudes artifacts of the transform, but artifacts can be usually recognized because they lack harmonics; thus, in most of these cases, true semi-periodic sequences may not be identified, but no false identifications will be made. A first example of an application of the method to real seismicity data is the analysis of the Parkfield event series. The analysis correctly aftcasts the September 2004 earthquake. Further applications to real data from Japan and Venezuela are shown in a companion paper.

  18. First observations of Trimpi events at Durban (L = 1. 69) using an OMSKI receiver

    SciTech Connect

    Friedel, R.H.W.; Hughes, A.R.W. ); Dowden, R.L.; Adams, C.D.D. )

    1993-02-01

    We report observations of transient ionospheric disturbances at VLF reflection heights, manifested as perturbations on sub-ionospherically propagating VLF transmitter signals: Trimpi events. Four VLF transmitter signals were monitored at Durban using an OM- SKI receiver. Both traditional Trimpi events and a new dome shaped event were observed at Durban. Occurrence of Trimpis at low L values can be interpreted as the precipitation of very high energy electrons which are capable of producing events during daylight, or as evidence of the fast Trimpi mechanism which could dominate at low L. The average winter event rate observed at Durban was quite low (7 per day on four transmitter signals) but during one very active period on the NAA-Durban signal 88 Trimpi events were observed in 2 hours. This activity was linked to an isolated thunderstorm occurring over the signal path over South Africa. 26 refs., 14 figs., 2 tabs.

  19. More Interesting Than You Thought: IRIS Observations of Explosive Events

    NASA Astrophysics Data System (ADS)

    Kankelborg, C. C.; Jaeggli, S.

    2013-12-01

    Transition region explosive events (EEs) are characterized by line broadenings (to the blue or red or both) with nonthermal velocity > 100 km/s. They are widely attributed to reconnection, though their nature is still obscure and some observers have reported rotary motion. The transition region is an excellent laboratory to study reconnection in a solar context, with high emission measure in the reconnection region, a high event rate, and optically thin spectral lines. The Interface Region Imaging Spectrograph (IRIS) has observed many explosive events in Si IV and C II. We describe the substructure of supersonic flows in EEs observed by IRIS, and their morphology as revealed by IRIS slit jaw images.

  20. Observations of hybrid seismic events at Soufriere Hills Volcano, Montserrat: July 1995 to September 1996

    USGS Publications Warehouse

    White, R.A.; Miller, A.D.; Lynch, L.; Power, J.

    1998-01-01

    Swarms of small repetitive events with similar waveforms and magnitudes are often observed during the emplacement of lava domes. Over 300 000 such events were recorded in association with the emplacement of the lava dome at Soufriere Hills Volcano, Montserrat, from August 1995 through August 1996. These events originated <2-3 km deep. They exhibited energy ranging over ??1.5-4.5 Hz and were broader band than typical long-period events. We term the events 'hybrid' between long-period and voclano-tectonic. The events were more impulsive and broader band prior to, compared with during and after, periods of inferred increased magma flux rate. Individual swarms contained up to 10 000 events often exhibiting very similar magnitudes and waveforms throughout the swarm. Swarms lasted hours to weeks, during which inter-event intervals generally increased, then decreased, often several times. Long-duration swarms began about every two months starting in late September 1995. We speculate that the events were produced as the magma column degassed into adjacent cracks.Swarms of small repetitive events with similar waveforms and magnitudes are often observed during the emplacement of lava domes. Over 300,000 such events were recorded in association with the emplacement of the lava dome at Soufriere Hills Volcano, Montserrat, from August 1995 through August 1996. These events originated <2-3 km deep. They exhibited energy ranging over approximately 1.5-4.5 Hz and were broader band than typical long-period events. We term the events `hybrid' between long-period and volcano-tectonic. The events were more impulsive and broader band prior to, compared with during and after, periods of inferred increased magma flux rate. Individual swarms contained up to 10,000 events often exhibiting very similar magnitudes and waveforms throughout the swarm. Swarms lasted hours to weeks, during which inter-event intervals generally increased, then decreased, often several times. Long-duration swarms

  1. Characteristics of Long-Period Events Associated With Volcanic Degassing at Popocatepetl Volcano, Mexico.

    NASA Astrophysics Data System (ADS)

    Arciniega, A.; Chouet, B.; Dawson, P.

    2004-05-01

    Emissions of gas and ash dominate volcanic eruptive activity in Popocatepetl volcano since 1994. Volcanic eruptive activity consists of construction and destruction dome phases. Ash emissions ranged from small short-lived plumes rising a few hundred meters above the crater rim, to larger plumes reaching up to 15 km above the crater. Resulting tephra falls dusted the entire summit area. Bursts of volcanic degassing accompanied by long-period (LP) seismic signals observed as isolated events, or as sequences of discrete events with overall durations and amplitudes. Some gas emissions accompanied by persistent or spasmodic tremor. There are four families of LP events identified within the frequency range between 0.5 and 5 Hz. Family-one presents low-frequency emergent onsets with higher amplitudes at higher frequencies. Family-two includes emergent onsets with modulate amplitudes simulating tremor and dominant frequencies in defined picks in the band between 1 and 3 Hz. Family-three presents LP events with impulsive onset and decaying amplitude with time, these events present a wide range of amplitudes and dominant frequencies around 2 Hz. Family-four includes LP events with monochromatic appearance with sharp picks below 3 Hz. From thousands of LP events preliminary locations based on phase picks suggest that LP seismicity occur within uppermost 1000 m below the crater floor, consistently constrain defined clusters in the east-region of the crater and in the area where the domes growth. The network used to located LP events included 15 broadband stations distributed along radial profiles on the upper flanks of Popocatepetl. We report data collected during a broadband seismic experiment carried out at Popocatepetl Volcano as part of an international cooperative program between the GeoForschungsZentr um, Potsdam, Germany, the U.S. Geological Survey and the Institute of Geophysics, UNAM, MEXICO.

  2. A brittle failure model for long-period seismic events recorded at Turrialba Volcano, Costa Rica

    NASA Astrophysics Data System (ADS)

    Eyre, Thomas S.; Bean, Christopher J.; De Barros, Louis; Martini, Francesca; Lokmer, Ivan; Mora, Mauricio M.; Pacheco, Javier F.; Soto, Gerardo J.

    2015-03-01

    A temporary seismic network, consisting of 23 broadband and six short-period stations, was installed in a dense network at Turrialba Volcano, Costa Rica, between 8 March and 4 May 2011. During this time 513 long-period (LP) events were observed. Due to their pulse-like waveforms, the hypothesis that the events are generated by a slow-failure mechanism, based on a recent new model by Bean et al. (2014), is tested. A significant number (107) of the LPs are jointly inverted for their source locations and mechanisms, using full-waveform moment tensor inversion. The locations are mostly shallow, with depths < 800 m below the active Southwest Crater. The results of the decompositions of the obtained moment tensor solutions show complex source mechanisms, composed of high proportions of isotropic and low, but seemingly significant, proportions of compensated linear vector dipole and double-couple components. It is demonstrated that this can be explained as mode I tensile fracturing with a strong shear component. The source mechanism is further investigated by exploring scaling laws within the data. The LPs recorded follow relationships very similar to those of conventional earthquakes, exhibiting frequency-magnitude and corner frequency versus magnitude relationships that can be explained by brittle failure. All of these observations indicate that a slow-failure source model can successfully describe the generation of short-duration LP events at Turrialba Volcano.

  3. Quasi-periodic emissions and related electron precipitation observed by the low-altitude DEMETER spacecraft

    NASA Astrophysics Data System (ADS)

    Hayosh, M.; Nemec, F.; Pasmanik, D.; Santolik, O.; Demekhov, A. G.; Parrot, M.; Titova, L.

    2012-12-01

    We present a survey of quasi-periodic (QP) ELF/VLF emissions detected on board the DEMETER satellite (altitude of about 700 km, nearly Sun-synchronous orbit at 10:30/22:30 LT). Three years of data have been visually inspected for the presence of QP emissions. It is found that QP events occur in about 3 percents of daytime half-orbits, while they are basically absent during the night (note that we were likely to miss QP events with the modulation periods lower than about 10 s or the frequency bandwidth lower than about 400 Hz). The events occur predominantly during quiet geomagnetic conditions following the periods of enhanced geomagnetic activity. Their occurrence and properties are systematically analyzed. Three events with a simultaneous periodic modulation of wave intensity and energetic electron precipitation were analyzed in detail. All events are observed at quiet geomagnetic conditions. Most probably, they are not associated with geomagnetic pulsations. Energetic electron flux data measured by the NOAA-17 satellite are used to supplement DEMETER data in order to determine the spatial and temporal extent of the observed energetic electron precipitation events. Based on the observed correlation between bursts of wave intensity and energetic electron flux we estimate the location and the spatial extent of the source region of QP emissions.

  4. Free-Choice Family Learning Experiences at Telescope Observing Events

    NASA Astrophysics Data System (ADS)

    Wenger, M. C.; Carter, K.; Harris, C. J.

    2011-09-01

    This study examines family experiences at nighttime telescope observing events. The goal was to observe family visitors and understand how they negotiate meaning and incorporate these experiences into their family culture. In this case study of one family's telescope observing experience, the participants' motivations and agenda are described as well as ways in which they negotiated identity and family-community membership at the same time as they were involved in the construction of meaning. The analysis revealed evidence of both meaning making and identity negotiation during, and related to, the educational leisure activity of attending a nighttime telescope observing event.

  5. Broadband moment-tensor inversion of long-period events on volcanoes: example from Turrialba volcano

    NASA Astrophysics Data System (ADS)

    Lokmer, Ivan; Thun, Johannes; Bean, Christopher

    2015-04-01

    Seismic events on volcanoes form a spectral continuum, from the high-frequency (> 10 Hz) tectonic-like events to ultra long period events with dominant periods longer than 100s of seconds. Long-period events (LP) are characterised by the dominant frequencies between 0.5 and 2Hz and relatively simple waveforms. They are mainly located within the first several hundred meters below volcano summit and are thought to reflect the dynamics of the shallow magmatic and/or hydrothermal plumbing system. It is still puzzling if they are generated by the pressure perturbations within fluid-filled cracks and conduits, or by a more classical faulting model in the extremely weak material, where the role of fluid is to modulate overall stress rather than being directly involved in the source generation process. So far, several moment-tensor (MT) inversions of LP events have been performed. A typical MT solution comprises a tensile crack source mechanism, and a pulsing or resonating source-time function (STF). However, due to generally small magnitudes of these events (a small S/N ratio), only the most energetic part of the signal is used in inversions. More precisely, the low frequency limit of the STF is determined by the lowest frequency of the most energetic part of the recorded waveform (usually about 0.3 - 0.5 Hz). Since it is extremely difficult to recover longer period ground displacements from such small-amplitude velocity records by using classical instrument response removal approach, it is almost impossible to infer if the obtained STF represents the real displacement in the source or it is just its band-limited representation. Here we used a good-quality dataset recorded near the summit of Turrialba volcano and applied some of the techniques used for the "baseline correction" in the strong motion seismology. In this way we managed to recover very low frequency part of LP signals, i.e. much lower than usual 0.3-0.5 Hz. Although the velocity records processed in this way

  6. Jiamusi Pulsar Observations: I. Abnormal emission events of PSR B0919+06

    NASA Astrophysics Data System (ADS)

    Han, Jun; Han, J. L.; Peng, Ling-Xiang; Tang, De-Yu; Wang, Jun; Li, Jun-Qiang; Wang, Chen; Yu, Ye-Zhao; Dong, Bin

    2016-03-01

    PSR B0919+06 generally radiates radio pulses in a normal phase range. It is known for its occasional perplexing abnormal emission events wherein individual pulses come to an earlier phase range for a few tens of periods and then it returns to its usual phase. Heretofore, only a few such events have been available for study. We observed PSR B0919+06 for about 30 h using the Jiamusi 66-m telescope at the Jiamusi Deep Space Station at the S band, and we detected 92 abnormal emission events. We identify four types of events based on the abrupted or gradual phase-shifting of individual pulses. The abnormal emission events are seen to occur randomly about every 1000-3000 periods, and they affect the leading edge of the mean profile by up to 2 per cent in amplitude. The abnormal emission events are probably related to gradual changes of emission processing in the pulsar magnetosphere.

  7. Oval intensification event observed by STARE and Viking

    SciTech Connect

    Nielsen, E. ); Elphinstone, R.; Hearn, D.; Murphree, J.S. ); Potemra, T. )

    1993-04-01

    The existence of polar arcs has been accepted for a long time, though there is no clear nomenclature, nor is there a good explanation for the origin or time behavior of these objects. The authors report on a thirty minute observation of such an event and its associated ionospheric response. The event, in the region of the auroral oval was seen by ultraviolet imagers on the Viking spacecraft, which provided time and spatially resolved images. Ground based observations were made by the coherent radar system STARE, which can make measurements of the electron drift velocities in the ionosphere over a large area. The authors were able to follow the optical and electron drift properties of this event as it developed. The arc was observed in conjunction with a band of electrojet, and other arcs. Shortly after its observation another electojet appeared, and moved to replace the previous system which disappeared. Following this there was a major intensification observed, or a substorm.

  8. Event-by-event study of neutron observables in spontaneous and thermal fission

    NASA Astrophysics Data System (ADS)

    Vogt, R.; Randrup, J.

    2011-10-01

    The event-by-event fission model freya is extended to spontaneous fission of actinides and a variety of neutron observables are studied for spontaneous fission and fission induced by thermal neutrons with a view toward possible applications for detection of special nuclear materials.

  9. Periodic Properties and Inquiry: Student Mental Models Observed during a Periodic Table Puzzle Activity

    ERIC Educational Resources Information Center

    Larson, Kathleen G.; Long, George R.; Briggs, Michael W.

    2012-01-01

    The mental models of both novice and advanced chemistry students were observed while the students performed a periodic table activity. The mental model framework seems to be an effective way of analyzing student behavior during learning activities. The analysis suggests that students do not recognize periodic trends through the examination of…

  10. Optimizing observing sequence design for periodic and non-periodic phenomena : a Bayesian approach

    NASA Technical Reports Server (NTRS)

    Johnston, Mark D.; Knight, Russell

    2005-01-01

    In this paper we report on our progress on addressing these issues. We have developed an approximate expression for the uniformity of phase coverage that can be used when scheduling to assess candidate sample times. We describe the results obtained using this estimator, and compare them with detailed simulations. We describe our progress and plans for integrating optimizing criteria for both periodic and non-periodic observations into a single observation sequence.

  11. 7 CFR 760.1001 - Eligible counties, disaster events, and disaster periods.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Eligible counties, disaster events, and disaster..., disaster events, and disaster periods. (a) Except as provided in this subpart, FSA will provide assistance... eligible disaster events in eligible disaster counties provided in paragraph (c) of this section. (b)...

  12. 7 CFR 760.1001 - Eligible counties, disaster events, and disaster periods.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 7 2013-01-01 2013-01-01 false Eligible counties, disaster events, and disaster..., disaster events, and disaster periods. (a) Except as provided in this subpart, FSA will provide assistance... eligible disaster events in eligible disaster counties provided in paragraph (c) of this section. (b)...

  13. 7 CFR 760.1001 - Eligible counties, disaster events, and disaster periods.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 7 2012-01-01 2012-01-01 false Eligible counties, disaster events, and disaster..., disaster events, and disaster periods. (a) Except as provided in this subpart, FSA will provide assistance... eligible disaster events in eligible disaster counties provided in paragraph (c) of this section. (b)...

  14. 7 CFR 760.1001 - Eligible counties, disaster events, and disaster periods.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 7 2014-01-01 2014-01-01 false Eligible counties, disaster events, and disaster..., disaster events, and disaster periods. (a) Except as provided in this subpart, FSA will provide assistance... eligible disaster events in eligible disaster counties provided in paragraph (c) of this section. (b)...

  15. 7 CFR 760.1001 - Eligible counties, disaster events, and disaster periods.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 7 2011-01-01 2011-01-01 false Eligible counties, disaster events, and disaster..., disaster events, and disaster periods. (a) Except as provided in this subpart, FSA will provide assistance... eligible disaster events in eligible disaster counties provided in paragraph (c) of this section. (b)...

  16. A study of the equatorial signatures of long period transient events (600 - 7200 s)

    NASA Astrophysics Data System (ADS)

    Santos, J.; Dutra, S.; Trivedi, N.; Vieira, L.; Echer, E.; Schuch, N.

    Transient variations in the H magnetic field component of magnetograms at high latitude are a common feature. They are associated with energy transference from solar wind to the magnetosphere. Abrupt changes in the solar wind generate Alfvén and fast mode waves through the magnetosphere. The Alfvén wave doesn't propagate in the direction perpendicular to the geomagnetic field, so equatorial signatures are probably caused by fast mode waves. On the other hand, complicated signatures observed at high latitudes represent a composition of Alfvén and fast mode waves. A second suggested propagation mechanism to low latitudes is the Earth-ionosphere wave-guide. In this work, geomagnetic data from the Brazilian magnetic stations at Belém (BLM), Eusébio (EUS), Ji-Paraná (JIP), São luis (SLZ) and São Martinho da Serra (SMS), all located near the geomagnetic equator, are used to look for equatorial signatures of transient events with periods of 600 - 7200s. This period range includes two special types of transient variations named Traveling convection vortices (TCV) and DP2 fluctuations. We try to identify their morphological characteristics and compare with the high latitude phenomena's characteristics. Satellite data (WIND, ACE and GOES) are used to see magnetosphere signatures and solar wind and interplanetary magnetic field (IMF) conditions during the events. The main objective is try to find the contribution of each propagation mechanism of these transient events arriving at the equatorial latitudes.

  17. Analysis of recurrent event data with incomplete observation gaps.

    PubMed

    Kim, Yang-Jin; Jhun, Myoungshic

    2008-03-30

    In analysis of recurrent event data, recurrent events are not completely experienced when the terminating event occurs before the end of a study. To make valid inference of recurrent events, several methods have been suggested for accommodating the terminating event (Statist. Med. 1997; 16:911-924; Biometrics 2000; 56:554-562). In this paper, our interest is to consider a particular situation, where intermittent dropouts result in observation gaps during which no recurrent events are observed. In this situation, risk status varies over time and the usual definition of risk variable is not applicable. In particular, we consider the case when information on the observation gap is incomplete, that is, the starting time of intermittent dropout is known but the terminating time is not available. This incomplete information is modeled in terms of an interval-censored mechanism. Our proposed method is applied to the study of the Young Traffic Offenders Program on conviction rates, wherein a certain proportion of subjects experienced suspensions with intermittent dropouts during the study. PMID:17611955

  18. Discrete self-oscillation period branches observed in semiconductor superlattices

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Hu, Bambi; Zheng, Zhigang; Li, Zhigang

    2011-04-01

    We investigate the self-sustained current oscillation of a weakly coupled semiconductor superlattice in the dynamical voltage band using a microscopic sequential tunneling model. With the voltage as a control parameter, two types of branches of current oscillation period versus voltage have been observed, which correspond to various oscillation scenarios. The first branch type consists of a series of period branches in accordance with how many charge dipoles need to be created at the emitter side to trigger a dipole-tripole oscillation scenario. For the second branch type, charge dipoles are generated periodically at the emitter, but all of them fail to develop completely and die out, thereby leading to a low-period oscillation scenario without the dipole-tripole process. The bistability between different branches is also observed by voltage up-sweeping and down-sweeping.

  19. Type 2 solar radio events observed in the interplanetary medium. Part 1: General characteristics

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    Twelve type 2 solar radio events were observed in the 2 MHz to 30 kHz frequency range by the radio astronomy experiment on the ISEE-3 satellite over the period from September 1978 to December 1979. These data provide the most comprehensive sample of type 2 radio bursts observed at kilometer wavelengths. Dynamic spectra of a number of events are presented. Where possible, the 12 events were associated with an initiating flare, ground based radio data, the passage of a shock at the spacecraft, and the sudden commencement of a geomagnetic storm. The general characteristics of kilometric type 2 bursts are discussed.

  20. OBSERVED CORE OF A GRADUAL SOLAR ENERGETIC PARTICLE EVENT

    SciTech Connect

    Kocharov, L.; Valtonen, E.; Reiner, M. J.; Thompson, B. J.; Klassen, A.

    2010-12-20

    Using space-borne particle and EUV detection and radio spectrograms from both ground-based and space-borne instruments, we study the first phase of the major solar energetic particle (SEP) event associated with the western solar flare and fast and wide coronal mass ejection (CME) on 2000 April 4. The SEP event being observed at the magnetic connection to the eruption's center starts with deka-MeV nucl{sup -1} helium- and relativistic electron-rich production from coronal sources identified with the electromagnetic diagnostics and the SEP event modeling. The broadband observations and modeling of the initial phase of the 'well-connected' major SEP event support the idea that acceleration of SEPs starts in the helium-rich plasma of the eruption's core in association with coronal shocks and magnetic reconnections caused by the CME liftoff, and that the coronal component dominates during the first hour of the SEP event considered, not yet being shielded by the CME bow shock in the solar wind. The first phase of the SEP event is followed by a second phase of SEP production associated with a decelerating CME-driven shock wave in the solar wind, which accelerates ions from a distinct, helium-poor seed particle population that may originate from the CME interaction with a coronal streamer.

  1. Stochastic Event Counter for Discrete-Event Systems Under Unreliable Observations

    SciTech Connect

    Tae-Sic Yoo; Humberto E. Garcia

    2008-06-01

    This paper addresses the issues of counting the occurrence of special events in the framework of partiallyobserved discrete-event dynamical systems (DEDS). First, we develop a noble recursive procedure that updates active counter information state sequentially with available observations. In general, the cardinality of active counter information state is unbounded, which makes the exact recursion infeasible computationally. To overcome this difficulty, we develop an approximated recursive procedure that regulates and bounds the size of active counter information state. Using the approximated active counting information state, we give an approximated minimum mean square error (MMSE) counter. The developed algorithms are then applied to count special routing events in a material flow system.

  2. Some observations on the periodate oxidation of amino compounds

    PubMed Central

    Clamp, J. R.; Hough, L.

    1966-01-01

    Various aliphatic and aromatic amines are oxidized by sodium metaperiodate and these reactions have been studied quantitatively in acidic, unbuffered and basic media. Significant differences have been observed between the behaviour of aliphatic and aromatic amines. Certain compounds also behaved differently under acidic and basic conditions. These reactions are related to the periodate oxidation of amino acids and, from observations on a number of glycine derivatives, a reaction mechanism is proposed for this process. PMID:4291354

  3. Modelling of an explosive event observed by SUMER & TRACE

    NASA Astrophysics Data System (ADS)

    Price, Daniel; Taroyan, Youra; Ishak, Bebe

    2016-07-01

    To fully understand coronal heating, we must first understand the different solar processes that move energy throughout the solar atmosphere. TRACE observations have revealed a short cold loop evolving over a small timescale, seemingly with multiple explosive events occurring along its length. An adaptive hydrodynamic radiation code was used to simulate the loop under non-equilibrium ionization. Footpoint heating and cold plasma injection were considered as possible scenarios to reproduce the observations. The simulation results were converted into synthetic observations through forward modelling, for comparison to SOHO/SUMER spectral observations of the loop.

  4. Simultaneous observation of monochromatic and variable period geomagnetic pulsations

    SciTech Connect

    McDiarmid, D.R.; Nielsen, E. )

    1987-05-01

    On February 4, 1983, following a storm sudden commencement, a monochromatic and a variable period pulsation were simultaneously observed by the Scandinavian Twin Auroral Radar Experiment (STARE) and Sweden and Britain Radar Experiment (SABRE) radar systems. Both pulsations differed from previously analyzed examples of their class. The phase of the monochromatic pulsation increased linearly with latitude rather than decreased. Its amplitude remained relatively constant over the latitude interval of linear phase change. The variable period pulsation experienced a change of orientation of its essentially linear polarization diagram in association with a discontinuity of its period. The variable period pulsation was thus manifest in both the toroidal and poloidal components. The results are discussed in terms of recent developments in theoretical pulsation modeling.

  5. Analysis of Suprathermal Events Observed by STEREO/PLASTIC

    NASA Astrophysics Data System (ADS)

    Barry, J. A.; Galvin, A. B.; Farrugia, C. J.; Popecki, M.; Klecker, B.; Ellis, L.; Lee, M. A.; Kistler, L. M.; Luhmann, J. G.; Russell, C. T.; Simunac, K.; Kucharek, H.; Blush, L.; Bochsler, P.; Möbius, E.; Thompson, B. J.; Wimmer-Schweingruber, R.; Wurz, P.

    2008-12-01

    Since the late 1960's, suprathermal and energetic ion events with energies ranging from just above the solar wind energies up to 2MeV and lasting for several minutes to hours, have been detected upstream of the Earth. Possible sources of these ions include magnetospheric ions, solar wind ions accelerated between the Earth's bow shock and hydromagnetic waves to energies just above the solar wind energies, and remnant ions from heliospheric processes (such as Solar Energetic Particle (SEP) events or Corotating Interaction Regions (CIRs)). The unique orbits of both STEREO spacecraft, STEREO-A (STA) drifting ahead in Earth's orbit and STEREO-B (STB) lagging behind in Earth's orbit, allow for analysis of upstream events in these unexamined regions. Using both the PLASTIC and IMPACT instruments on board STA/B we can examine protons in the energy range of solar wind energies up to 80keV, their spatial distribution, and determine if the spacecraft is magnetically connected to the Earth's bow shock. Suprathermal events observed by STEREO/PLASTIC during solar minimum conditions are examined for possible upstream events using anisotropy measurements, velocity dispersion, magnetic connection to the bow shock, and frequency of events as a function of time and distance.

  6. Analysis of suprathermal proton events observed by STEREO/PLASTIC focusing on the observation of bow shock/magnetospheric events

    NASA Astrophysics Data System (ADS)

    Barry, J. A.; Galvin, A. B.; Popecki, M.; Klecker, B.; Kucharek, H.; Simunac, K.; Farrugia, C. J.; Luhmann, J. G.; Jian, L. K.

    2013-06-01

    The topic of suprathermal and energetic ion events upstream of the Earth's bow shock has been investigated since the late 1960's. Over the past 50 years, these events have been characterized as having energies ranging from just above the solar wind energies on through 2MeV, time spans of minutes to hours, and particle distributions ranging from field aligned to isotropic. The seed particles of these events accelerated within the magnetosphere and/or at the Earth's bow shock have been shown to be of ions originating in the magnetosphere, solar wind, as well as ions energized in other heliospheric processes (such as solar energetic particle (SEP), corotating interaction regions (CIRs), Pick-up ions, etc.). In this study we utilize STEREO/PLASTIC to examine bow shock/magnetospheric energetic proton events observed throughout 2007 in the region far upstream of the Earth's ion foreshock. To do this, we first employ an automated procedure to identify suprathermal proton events in the energy range of 4keV up to 80keV. The occurrence of events, magnetic connection to the Earth, and Compton-Getting transformed energy spectra of 66 possible STA bow shock/magnetospheric events are investigated as a function of spacecraft-Earth separation.

  7. Broadband source inversion of Long-Period (LP) events on Turrialba volcano, Costa Rica

    NASA Astrophysics Data System (ADS)

    Lokmer, I.; Thun, J.; Bean, C. J.

    2015-12-01

    A typical moment-tensor (MT) solution of long-period (LP) volcanic signals comprises a tensile crack source mechanism and a pulsing or resonating source-time function (STF). However, due to the small magnitudes of LP events, only the most energetic part of the signals (as seen from velocity waveforms) is used in inversions. Ground displacement periods longer than 5 seconds - if they exist - are very difficult (if not impossible) to recover from such small signals due to the contamination of the signal by high-amplitude microseisms and the velocity signal base-line fluctuations (long-period instrumental noise). Consequently, the source-time functions (STF) obtained in LP inversions are band-limited representations of the true displacements in the source. Here we use a good-quality LP dataset recorded near the summit of Turrialba volcano. Aided by results from step table laboratory experiments we carefully recover the broadband ground motion displacement, containing frequencies much lower than 0.3 Hz observed on the velocity seismograms. The resulting MT solution that we recover is a classical earthquake "ramp" function, rather than a pulsing or oscillating waveform. We suggest that this new observation will contribute to a better understanding of LP seismicity.

  8. AGILE Observations of the Gravitational-wave Event GW150914

    NASA Astrophysics Data System (ADS)

    Tavani, M.; Pittori, C.; Verrecchia, F.; Bulgarelli, A.; Giuliani, A.; Donnarumma, I.; Argan, A.; Trois, A.; Lucarelli, F.; Marisaldi, M.; Del Monte, E.; Evangelista, Y.; Fioretti, V.; Zoli, A.; Piano, G.; Munar-Adrover, P.; Antonelli, L. A.; Barbiellini, G.; Caraveo, P.; Cattaneo, P. W.; Costa, E.; Feroci, M.; Ferrari, A.; Longo, F.; Mereghetti, S.; Minervini, G.; Morselli, A.; Pacciani, L.; Pellizzoni, A.; Picozza, P.; Pilia, M.; Rappoldi, A.; Sabatini, S.; Vercellone, S.; Vittorini, V.; Giommi, P.; Colafrancesco, S.; Cardillo, M.; Galli, M.; Fuschino, F.

    2016-07-01

    We report the results of an extensive search through the AGILE data for a gamma-ray counterpart to the LIGO gravitational-wave (GW) event GW150914. Currently in spinning mode, AGILE has the potential of cover 80% of the sky with its gamma-ray instrument, more than 100 times a day. It turns out that AGILE came within a minute of the event time of observing the accessible GW150914 localization region. Interestingly, the gamma-ray detector exposed ∼65% of this region during the 100 s time intervals centered at ‑100 and +300 s from the event time. We determine a 2σ flux upper limit in the band 50 MeV–10 GeV, UL = 1.9 × 10‑8 erg cm‑2 s‑1, obtained ∼300 s after the event. The timing of this measurement is the fastest ever obtained for GW150914, and significantly constrains the electromagnetic emission of a possible high-energy counterpart. We also carried out a search for a gamma-ray precursor and delayed emission over five timescales ranging from minutes to days: in particular, we obtained an optimal exposure during the interval ‑150/‑30 s. In all these observations, we do not detect a significant signal associated with GW150914. We do not reveal the weak transient source reported by Fermi-GBM 0.4 s after the event time. However, even though a gamma-ray counterpart of the GW150914 event was not detected, the prospects for future AGILE observations of GW sources are decidedly promising.

  9. NOAA POES Observations of Relativistic Electron Precipitation during a Radiation Belt Depletion Event

    NASA Astrophysics Data System (ADS)

    Millan, R. M.; Yando, K.; Green, J. C.

    2008-12-01

    We present POES observations of relativistic electron precipitation during an electron depletion event observed by GOES and GPS. On January 19, 2000 NOAA-15 passed very near the MAXIS balloon payload (L=4.7) which detected an intense duskside precipitation event (Millan et al., 2007). Recent work has shown that the NOAA MEPED proton detector responds to electrons above ~700 keV. We combine data from this high energy channel with data from the MEPED electron detector to examine the energy distribution and spatial extent of precipitation during this period. The results are compared with the MAXIS balloon observations.

  10. Wavefield properties of a shallow long-period event and tremor at Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Saccorotti, G.; Chouet, B.; Dawson, P.

    2001-01-01

    The wavefields of tremor and a long-period (LP) event associated with the ongoing eruptive activity at Kilauea Volcano, Hawaii, are investigated using a combination of dense small-aperture (300 m) and sparse large-aperture (5 km) arrays deployed in the vicinity of the summit caldera. Measurements of azimuth and slowness for tremor recorded on the small-aperture array indicate a bimodal nature of the observed wavefield. At frequencies below 2 Hz, the wavefield is dominated by body waves impinging the array with steep incidence. These arrivals are attributed to the oceanic microseismic noise. In the 2-6 Hz band, the wavefield is dominated by waves propagating from sources located at shallow depths (<1 km) beneath the eastern edge of the Halemaumau pit crater. The hypocenter of the LP event, determined from frequency-slowness analyses combined with phase picks, appears to be located close to the source of tremor but at a shallower depth (<0.1 km). The wavefields of tremor and LP event are characterized by a complex composition of body and surface waves, whose propagation and polarization properties are strongly affected by topographic and structural features in the summit caldera region. Analyses of the directional properties of the wavefield in the 2-6 Hz band point to the directions of main scattering sources, which are consistent with pronounced velocity contrasts imaged in a high-resolution three-dimensional velocity model of the caldera region. The frequency and Q of the dominant peak observed in the spectra of the LP event may be explained as the dominant oscillation mode of a crack with scale length 20-100 m and aperture of a few centimeters filled with bubbly water. The mechanism driving the shallow tremor appears to be consistent with a sustained excitation originating in the oscillations of a bubbly cloud resulting from vesiculation and degassing in the magma. ?? 2001 Elsevier Science B.V. All rights reserved.

  11. ICME events at Mars: MAVEN observations and models

    NASA Astrophysics Data System (ADS)

    Curry, Shannon; Luhmann, Janet; Dong, Chuanfei; Hara, Takuya; Leblanc, Francois; Modolo, Ronan; Fraenz, Markus; Holmstrom, Mats; Ramstad, Robin; Juan Ma, Ying; Halekas, Jasper; Gruesbeck, Jacob; Dong, Yaxue; Brain, David; McFadden, James; Connerney, Jack; Mitchell, David; Fillingim, Matt; Espley, Jared; Jakosky, Bruce

    2016-04-01

    The MAVEN spacecraft has observed the Mars upper atmosphere, ionosphere, magnetic topology and interactions with the Sun and solar wind during numerous Interplanetary Coronal Mass Ejection (ICME) impacts spanning from March 2015 to January 2016. Observations include dramatic changes in the bow shock and magnetosheath boundaries, open and closed magnetic field lines, and extreme enhancements of escaping and precipitating pick-up ions. We will compare three ICMEs using MAVEN and MEX observations at Mars, with an emphasis on the response of the planetary pick-up ions. Additionally, we will present global MHD and test particle simulations of the ICMEs using MAVEN and MEX observations as initial conditions, which show a significant enhancement in the nonthermal escape of planetary ions during these events. We also will put the observed ICME events in context with a model of an idealized extreme ICME interacting with Mars. Accordingly, atmospheric escape during extreme solar events in Mars' early history may have been a significant contributor to the evolution of the Martian atmosphere and may also have implications for exoplanets interacting with younger, more active stars.

  12. Long-term Spatial and Temporal Variations of Aurora Borealis Events in the Period 1700 - 1905

    NASA Astrophysics Data System (ADS)

    Vázquez, M.; Vaquero, J. M.; Gallego, M. C.

    2014-05-01

    Catalogues and other records of aurora-borealis events were used to study the long-term spatial and temporal variation of these phenomena in the period from 1700 to 1905 in the Northern Hemisphere. For this purpose, geographic and geomagnetic coordinates were assigned to approximately 27 000 auroral events with more than 80 000 observations. They were analyzed separately in three large-scale areas: i) Europe and North Africa, ii) North America, and iii) Asia. There was a clear need to fill some gaps existing in the records so as to have a reliable proxy of solar activity, especially during the 18th century. In order to enhance the long-term variability, an 11-year smoothing window was applied to the data. Variations in the cumulative numbers of auroral events with latitude (in both geographic and geomagnetic coordinates) were used to discriminate between the two main solar sources: coronal mass ejections and high-speed streams from coronal holes. The characteristics of the associated auroras correlate differently with the solar-activity cycle.

  13. Transient Events in Archival VLA Observations of the Galactic Center

    NASA Astrophysics Data System (ADS)

    Chiti, Anirudh; Chatterjee, S.; Wharton, R.; Cordes, J. M.; Lazio, J.; Kaplan, D. L.; Bower, G. C.; Croft, S.

    2014-01-01

    A number of different classes of stars, sub-stellar objects, and stellar remnants exhibit variability at radio wavelengths on time scales ranging from sub-seconds to hours. The direction toward the Galactic center not only has the highest stellar densities in the Galaxy, but also appears to have a range of interstellar scattering properties that may aid in the detection of new, radio-selected transient events. We have examined all archival VLA observations of the Galactic center field from 1985 to 2005 at 5 GHz and 8.4 GHz for a total of 214 hours of integration time, spanning 99 observations at 5 GHz with a typical area of 4.41E-4 square degrees and 116 observations at 8.4 GHz with a typical area of 8E-4 square degrees. We used a pipeline to search for transient events down to the shortest time scales allowed by the data (typically 10 seconds) by generating model-subtracted visibility data for each observation and then imaging the residual visibilities over short time intervals to search for outlier events. We present one radio transient event and at least 7 other promising candidates with significances ranging from 5.6 to 10.2 sigma that have passed all our tests, and discuss the possible source classes for these candidates and the event rate implications. We acknowledge support from the National Science Foundation for this work. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  14. Semi-Periodic Sequences and Extraneous Events in Earthquake Forecasting. II: Application, Forecasts for Japan and Venezuela

    NASA Astrophysics Data System (ADS)

    Quinteros Cartaya, Claudia Beatriz; Nava Pichardo, Fidencio Alejandro; Glowacka, Ewa; Frez Cárdenas, José Duglas

    2014-07-01

    In order to analyze observed seismicity in central Japan and Venezuela, we applied a new method to identify semi-periodic sequences in the occurrence times of large earthquakes, which allows for the presence of multiple periodic sequences and/or events not belonging to any sequence in the time series. We also explored a scheme for diminishing the effects of a sharp cutoff magnitude threshold in selecting the events to analyze. A main four-event sequence with probability P c = 0.991 of not having occurred by chance was identified for earthquakes with M ≥ 8.0 in central Japan. Venezuela is divided, from West to East, into four regions; for each of these, the magnitude ranges and identified sequences are as follows. Region 1: M ≥ 6.0, a six-event sequence with P c = 0.923, and a four-event sequence with P c = 0.706. Region 2: M ≥ 5.6, a five-event sequence with P c = 0.942. Region 3: M ≥ 5.6, a four-event sequence with P c = 0.882. Region 4: M ≥ 6.0, a five-event sequence with P c = 0.891. Forecasts are made and evaluated for all identified sequences having four or more events and probabilities ≥0.5. The last event of all these sequences was satisfactorily aftcast by previous events. Whether the identified sequences do, in fact, correspond to physical processes resulting in semi-periodic seismicity is, of course, an open question; but the forecasts, properly used, may be useful as a factor in seismic hazard estimation.

  15. Fast and Statistically Optimal Period Search in Uneven Sampled Observations

    NASA Astrophysics Data System (ADS)

    Schwarzenberg-Czerny, A.

    1996-04-01

    The classical methods for searching for a periodicity in uneven sampled observations suffer from a poor match of the model and true signals and/or use of a statistic with poor properties. We present a new method employing periodic orthogonal polynomials to fit the observations and the analysis of variance (ANOVA) statistic to evaluate the quality of the fit. The orthogonal polynomials constitute a flexible and numerically efficient model of the observations. Among all popular statistics, ANOVA has optimum detection properties as the uniformly most powerful test. Our recurrence algorithm for expansion of the observations into the orthogonal polynomials is fast and numerically stable. The expansion is equivalent to an expansion into Fourier series. Aside from its use of an inefficient statistic, the Lomb-Scargle power spectrum can be considered a special case of our method. Tests of our new method on simulated and real light curves of nonsinusoidal pulsators demonstrate its excellent performance. In particular, dramatic improvements are gained in detection sensitivity and in the damping of alias periods.

  16. Quantitative analysis of long-period events recorded during hydrofracture experiments at Fenton Hill, New Mexico

    NASA Astrophysics Data System (ADS)

    Ferrazzini, Valerie; Chouet, Bernard; Fehler, Mike; Aki, Keiiti

    1990-12-01

    A three-dimensional fluid-filled crack model recently developed by Chouet is used to reproduce and explain the spectral characteristics of different classes of long-period events recorded during a hydrofracture experiment conducted at Fenton Hill, New Mexico. We study the dependence on the model parameters of the far-field P-wave radiation due to the vibration of the fluid-filled crack. Those parameters are given by the properties of the fluid and solid, the crack dimensions, the area and location of the crack surface over which the excess pressure is applied, the time history of this excess pressure, and the station location. In this model, the resonance of the crack is sustained by a very slow and dispersive wave called "crack wave". The phase velocity of the crack wave depends critically on the impedance contrast between fluid and solid and on the crack dimensions. We are able to fit the dominant features of the Fenton Hill data in the time and frequency domains and draw inferences on the impedance contrast between the fluid and solid. The various classes of events observed can be modeled by a single crack over which the geometry of the applied excess pressure changes. The length, width, and thickness of the crack are estimated to be on the order of 3 m, 1 m, and 3 mm, respectively. The observed spectral roll-off can be explained by a ramp function time dependence of the pressure transient. The rise time necessary to simulate the observed data varies between 2 and 4 ms, depending on the event considered. Assuming the source-receiver distance of 700 m, the amplitude of displacement of the data agree with the model's prediction if the excess pressure applied on the crack is on the order of 20 bars.

  17. Infrasound observation of seismic events occurring in North Korea

    NASA Astrophysics Data System (ADS)

    Park, Y.; Che, I.; Nam, S.; Kim, Y.; Lee, J.

    2012-12-01

    Seismic events of North Korea were analyzed by using data set from the regional network including 31 seismic stations and 5 seismo-acoustic arrays of Korea Institute of Geoscience and Mineral Resources(KIGAM) and 7 Korea-China joint seismic stations in China. Infrasonic data were analysed using the PMCC method, to detect blast-associated infrasonic signals. Phase velocity and back-azimuth of infrasound signals varied between 250 to 400 m/s and ±10° respectively. Seismo-acoustic analysis was conducted to discriminate 375 events which are 38.1 percent of the total seismic events. More than 60 percent of seismo-acoustic events occurred around the Pyeongyang and Wonsan area of North Korea. In the case of the events occurred in the southeastern part of North Korea, the percentage was relatively small. The seismo-acoustic location were improved by using grid-search method. This method was based the observed travel times and azimuths of infrasonic signals and seismic parameter.

  18. Coordinated Solar Observation and Event Searches using the Heliophysics Events Knowledgebase (HEK)

    NASA Astrophysics Data System (ADS)

    Timmons, R.; Hurlburt, N. E.

    2014-12-01

    We present new capabilities of the HEK allowing for joint searches, returning overlapping data from multiple instruments (IRIS, SOT, XRT, EIS) that also include particular solar features and events (active regions, (large) flares, sunspots, etc.). The new search tools aid the process of finding particular observations from non-synotpic instruments.

  19. Observations of Waves with Observed Periods less than the Buoyancy Period in the Winter Polar Mesopause Region

    NASA Astrophysics Data System (ADS)

    Williams, B. P.; Fritts, D. C.

    2009-12-01

    The sodium wind-temperature lidar at the ALOMAR observatory (69N,16E) can measure the sodium density from 85-100km altitude with 150m height and 15 sec time resolution during winter under good conditions. Radial winds and temperatures can be measured with 1-2 m/s and 1-2 K error after averaging to 1 min in time and 1-2 km in altitude. This allows determination of the short period wave spectrum down to 30sec in Na density and 2min in wind and temperature. Preliminary analysis shows a number of oscillations with observed periods that are less than the buoyancy period. We have also observed an oscillation in the height of a strong summertime sodium sporadic layer with 500m amplitude and 45sec period. We will show the short period spectrum for the full high-resolution database and investigate the sources of these oscillations. Some possibilities include Doppler shifting of the intrinsic frequencies, acoustic waves, or advection of horizontal gradients through our lidar beam.

  20. Quantifying the influence of observed global warming on the probability of unprecedented extreme climate events

    NASA Astrophysics Data System (ADS)

    Diffenbaugh, N. S.; Rajaratnam, B.; Charland, A.; Haugen, M.; Horton, D. E.; Singh, D.; Swain, D. L.; Tsiang, M.

    2014-12-01

    Now that observed global warming has been clearly attributed to human activities, there has been increasing interest in the extent to which that warming has influenced the occurrence and severity of individual extreme climate events. However, although trends in the extremes of the seasonal- and daily-scale distributions of climate records have been analyzed for many years, quantifying the contribution of observed global warming to individual events that are unprecedented in the observed record presents a particular scientific challenge. We will describe a modified method for leveraging observations and large climate model ensembles to quantify the influence of observed global warming on the probability of unprecedented extreme events. In this approach, we first diagnose the causes of the individual event in order to understand which climate processes to target in the probability quantification. We then use advanced statistical techniques to quantify the uncertainty in the return period of the event in the observed record. We then use large ensembles of climate model simulations to quantify the distribution of return period ratios between the current level of climate forcing and the pre-industrial climate forcing. We will compare the structure of this approach to other approaches that exist in the literature. We will then examine a set of individual extreme events that have been analyzed in the literature, and compare the results of our approach with those that have been previously published. We will conclude with a discussion of the observed agreement and disagreement between the different approaches, including implications for interpretation of the role of human forcing in shaping unprecedented extreme events.

  1. Infrasonic observations of large-scale HE events

    NASA Technical Reports Server (NTRS)

    Whitaker, Rodney W.; Mutschlecner, J. Paul; Davidson, Masha B.; Noel, Susan D.

    1990-01-01

    The Los Alamos Infrasound Program has been operating since about mid-1982, making routine measurements of low frequency atmospheric acoustic propagation. Generally, the authors work between 0.1 Hz to 10 Hz; however, much of the work is concerned with the narrower range of 0.5 to 5.0 Hz. Two permanent stations, St. George, UT, and Los Alamos, NM, have been operational since 1983, collecting data 24 hours a day. For the purposes of this discussion, the authors concentrate on their measurements of large, high explosive (HE) events at ranges of 250 km to 5330 km. Because their equipment is well suited for mobile deployments, they can easily establish temporary observing sites for special events. The measurements are from the permanent sites, as well as from various temporary sites. A few observations that are typical of the full data set are given.

  2. Polarimetric radar observations during an orographic rain event

    NASA Astrophysics Data System (ADS)

    Frech, M.; Steinert, J.

    2015-03-01

    An intense orographic precipitation event on 5 January 2013 is analyzed using a polarimetric C-band radar situated north of the Alps. The radar is operated at the meteorological observatory Hohenpeißenberg (MHP, 1006 m a.s.l. - above sea level) of the German Meteorological Service (DWD). The event lasted about 1.5 days and in total 44 mm precipitation was measured at Hohenpeißenberg. Detailed high resolution observation on the vertical structure of this event is obtained through a birdbath scan at 90° elevation which is part of the operational scanning. This scan is acquired every 5 min and provides meteorological profiles at high spatial resolution which are often not available in other radar networks. In the course of this event, the melting layer (ML) descends until the transition from rain into snow is observed at ground level. This transition from rain into snow is well documented by local weather observers and a present-weather sensor. The orographic precipitation event reveals mesoscale variability above the melting layer which can be attributed to a warm front. This variability manifests itself through substantially increased hydrometeor fall velocities. Radiosounding data indicate a layered structure in the thermodynamic field with increased moisture availability in relation to warm air advection. Rimed snowflakes and aggregation in a relatively warm environment lead to a signature in the radar data which is attributed to wet snow. The passage of the warm front leads to a substantial increase in rain rate at the surface. We use the newly implemented hydrometeor classification scheme "Hymec" to illustrate issues when relating radar products to local observations. For this, we employ data from the radar near Memmingen (MEM, 65 km west of MHP, 600 m a.s.l.) which is part of DWD's operational radar network. The detection, in location and timing, of the ML agrees well with the Hohenpeißenberg radar data. Considering the size of the Memmingen radar sensing

  3. The Search for Periodic Components in Observational Data

    NASA Astrophysics Data System (ADS)

    Baluev, R. V.

    2014-09-01

    This review is devoted to the problem of searching for periodicities in observational data using periodograms based on the general statistical likelihood ratio test and special variants of it, including the classical Lomb-Scargle periodogram. Primary emphasis is on the problem of estimating the statistical significance of the periodicities detected in this manner. We assume that a universal solution of this problem exists involving an effective method in which the periodogram is regarded as a random process (or random field), while an approximation for the required "false alarm probability" is constructed by a generalized Rice method. Besides a unified method for determining the expected noise levels (or significance levels) of these periodograms, we also examine some important special cases with different models of periodic signals (linear and nonlinear). The false alarm probability associated with an observed signal is approximated in most cases by a formula of the type , where z is the observed maximum readout in the periodogram and P is an algebraic polynomial with coefficients that depend on the conditions of the problem. We also examine the problem of separating composite signals with several frequencies from noise. In this case correct analysis of the data requires the use of so-called multifrequency periodograms based on models of signals containing several periodic components. We show that a complete solution to this problem requires construction of 2n-1 such periodograms, where n is the total number of possible frequencies. Finally, we describe some program packages that we have developed which make it easier to perform practical frequency analysis of series using this theory.

  4. Solar energetic particles events observed by Prognoz-10 Intercosmos (May-October 1985)

    NASA Technical Reports Server (NTRS)

    Lutserko, V.; Fischer, S.; Vandas, M.; Kudela, K.; Stivka, M.

    1987-01-01

    On 26 April 1985, Intershock began observation of a solar energetic particle (SEP) event, resulting from a 3B solar flare which originated on 24 April. The following observation period was quiet with only a few weak increases of low-energy protons of several days duration. Two prominent SEP events occurred on 9 July 1985 (start 0133 UT, position S13, W25) and 17 July (no optical data, type II radio burst from 0333 to 0348 UT). These mass ejection and particle propagation episodes were studied on the basis of X-ray, radio, and energetic particle emissions.

  5. Solar energetic particles events observed by Prognoz-10 Intercosmos (May-October 1985)

    NASA Astrophysics Data System (ADS)

    Lutserko, V.; Fischer, S.; Vandas, M.; Kudela, K.; Stivka, M.

    1987-09-01

    On 26 April 1985, Intershock began observation of a solar energetic particle (SEP) event, resulting from a 3B solar flare which originated on 24 April. The following observation period was quiet with only a few weak increases of low-energy protons of several days duration. Two prominent SEP events occurred on 9 July 1985 (start 0133 UT, position S13, W25) and 17 July (no optical data, type II radio burst from 0333 to 0348 UT). These mass ejection and particle propagation episodes were studied on the basis of X-ray, radio, and energetic particle emissions.

  6. The source of infrasound associated with long-period events at mount St. Helens

    USGS Publications Warehouse

    Matoza, R.S.; Garces, M.A.; Chouet, B.A.; D'Auria, L.; Hedlin, M.A.H.; De Groot-Hedlin, C.; Waite, G.P.

    2009-01-01

    During the early stages of the 2004-2008 Mount St. Helens eruption, the source process that produced a sustained sequence of repetitive long-period (LP) seismic events also produced impulsive broadband infrasonic signals in the atmosphere. To assess whether the signals could be generated simply by seismic-acoustic coupling from the shallow LP events, we perform finite difference simulation of the seismo-acoustic wavefield using a single numerical scheme for the elastic ground and atmosphere. The effects of topography, velocity structure, wind, and source configuration are considered. The simulations show that a shallow source buried in a homogeneous elastic solid produces a complex wave train in the atmosphere consisting of P/SV and Rayleigh wave energy converted locally along the propagation path, and acoustic energy originating from , the source epicenter. Although the horizontal acoustic velocity of the latter is consistent with our data, the modeled amplitude ratios of pressure to vertical seismic velocity are too low in comparison with observations, and the characteristic differences in seismic and acoustic waveforms and spectra cannot be reproduced from a common point source. The observations therefore require a more complex source process in which the infrasonic signals are a record of only the broadband pressure excitation mechanism of the seismic LP events. The observations and numerical results can be explained by a model involving the repeated rapid pressure loss from a hydrothermal crack by venting into a shallow layer of loosely consolidated, highly permeable material. Heating by magmatic activity causes pressure to rise, periodically reaching the pressure threshold for rupture of the "valve" sealing the crack. Sudden opening of the valve generates the broadband infrasonic signal and simultaneously triggers the collapse of the crack, initiating resonance of the remaining fluid. Subtle waveform and amplitude variability of the infrasonic signals as

  7. The Incubation Period of Primary Epstein-Barr Virus Infection: Viral Dynamics and Immunologic Events

    PubMed Central

    Dunmire, Samantha K.; Grimm, Jennifer M.; Schmeling, David O.; Balfour, Henry H.; Hogquist, Kristin A.

    2015-01-01

    Epstein-Barr virus (EBV) is a human herpesvirus that causes acute infectious mononucleosis and is associated with cancer and autoimmune disease. While many studies have been performed examining acute disease in adults following primary infection, little is known about the virological and immunological events during EBV’s lengthy 6 week incubation period owing to the challenge of collecting samples from this stage of infection. We conducted a prospective study in college students with special emphasis on frequent screening to capture blood and oral wash samples during the incubation period. Here we describe the viral dissemination and immune response in the 6 weeks prior to onset of acute infectious mononucleosis symptoms. While virus is presumed to be present in the oral cavity from time of transmission, we did not detect viral genomes in the oral wash until one week before symptom onset, at which time viral genomes were present in high copy numbers, suggesting loss of initial viral replication control. In contrast, using a sensitive nested PCR method, we detected viral genomes at low levels in blood about 3 weeks before symptoms. However, high levels of EBV in the blood were only observed close to symptom onset–coincident with or just after increased viral detection in the oral cavity. These data imply that B cells are the major reservoir of virus in the oral cavity prior to infectious mononucleosis. The early presence of viral genomes in the blood, even at low levels, correlated with a striking decrease in the number of circulating plasmacytoid dendritic cells well before symptom onset, which remained depressed throughout convalescence. On the other hand, natural killer cells expanded only after symptom onset. Likewise, CD4+ Foxp3+ regulatory T cells decreased two fold, but only after symptom onset. We observed no substantial virus specific CD8 T cell expansion during the incubation period, although polyclonal CD8 activation was detected in concert with viral

  8. The Incubation Period of Primary Epstein-Barr Virus Infection: Viral Dynamics and Immunologic Events.

    PubMed

    Dunmire, Samantha K; Grimm, Jennifer M; Schmeling, David O; Balfour, Henry H; Hogquist, Kristin A

    2015-12-01

    Epstein-Barr virus (EBV) is a human herpesvirus that causes acute infectious mononucleosis and is associated with cancer and autoimmune disease. While many studies have been performed examining acute disease in adults following primary infection, little is known about the virological and immunological events during EBV's lengthy 6 week incubation period owing to the challenge of collecting samples from this stage of infection. We conducted a prospective study in college students with special emphasis on frequent screening to capture blood and oral wash samples during the incubation period. Here we describe the viral dissemination and immune response in the 6 weeks prior to onset of acute infectious mononucleosis symptoms. While virus is presumed to be present in the oral cavity from time of transmission, we did not detect viral genomes in the oral wash until one week before symptom onset, at which time viral genomes were present in high copy numbers, suggesting loss of initial viral replication control. In contrast, using a sensitive nested PCR method, we detected viral genomes at low levels in blood about 3 weeks before symptoms. However, high levels of EBV in the blood were only observed close to symptom onset-coincident with or just after increased viral detection in the oral cavity. These data imply that B cells are the major reservoir of virus in the oral cavity prior to infectious mononucleosis. The early presence of viral genomes in the blood, even at low levels, correlated with a striking decrease in the number of circulating plasmacytoid dendritic cells well before symptom onset, which remained depressed throughout convalescence. On the other hand, natural killer cells expanded only after symptom onset. Likewise, CD4+ Foxp3+ regulatory T cells decreased two fold, but only after symptom onset. We observed no substantial virus specific CD8 T cell expansion during the incubation period, although polyclonal CD8 activation was detected in concert with viral

  9. Substorms observations over Apatity during geomagnetic storms in the period 2012 - 2016

    NASA Astrophysics Data System (ADS)

    Guineva, Veneta; Werner, Rolf; Despirak, Irina; Kozelov, Boris

    2016-07-01

    In this work we studied substorms, generated during enhanced geomagnetic activity in the period 2012 - 2016. Observations of the Multiscale Aurora Imaging Network (MAIN) in Apatity have been used. Solar wind and interplanetary magnetic field parameters were judged by the 1-min sampled OMNI data base. Substorm onset and further development were verified by the 10-s sampled data of IMAGE magnetometers and by data of the all-sky camera at Apatity. Subject of the study were substorms occurred during geomagnetic storms. The so-called "St. Patrick's day 2015 event" (17-21 March 2015), the events on 17-18 March 2013 and 7-17 March 2012 (a chain of events generated four consecutive storms) which were among the events of strongest geomagnetic activity during the current solar cycle 24, were part of the storms under consideration. The behavior of the substorms developed during different phases of the geomagnetic storms was discussed.

  10. Periodic impact cratering and extinction events over the last 260 million years

    NASA Astrophysics Data System (ADS)

    Rampino, Michael R.; Caldeira, Ken

    2015-12-01

    The claims of periodicity in impact cratering and biological extinction events are controversial. A newly revised record of dated impact craters has been analyzed for periodicity, and compared with the record of extinctions over the past 260 Myr. A digital circular spectral analysis of 37 crater ages (ranging in age from 15 to 254 Myr ago) yielded evidence for a significant 25.8 ± 0.6 Myr cycle. Using the same method, we found a significant 27.0 ± 0.7 Myr cycle in the dates of the eight recognized marine extinction events over the same period. The cycles detected in impacts and extinctions have a similar phase. The impact crater dataset shows 11 apparent peaks in the last 260 Myr, at least 5 of which correlate closely with significant extinction peaks. These results suggest that the hypothesis of periodic impacts and extinction events is still viable.

  11. Event-by-event study of neutron observables in spontaneous and thermal fission

    SciTech Connect

    Vogt, R; Randrup, J

    2011-09-14

    The event-by-event fission model FREYA is extended to spontaneous fission of actinides and a variety of neutron observables are studied for spontaneous fission and fission induced by thermal neutrons with a view towards possible applications for SNM detection. We have shown that event-by-event models of fission, such as FREYA, provide a powerful tool for studying fission neutron correlations. Our results demonstrate that these correlations are significant and exhibit a dependence on the fissioning nucleus. Since our method is phenomenological in nature, good input data are especially important. Some of the measurements employed in FREYA are rather old and statistics limited. It would be useful to repeat some of these studies with modern detector techniques. In addition, most experiments made to date have not made simultaneous measurements of the fission products and the prompt observables, such as neutron and photons. Such data, while obviously more challenging to obtain, would be valuable for achieving a more complete understanding of the fission process.

  12. Skylab ATM/S-056 X-ray event analyzer observations versus solar flare activity: An event compilation. [tables (data)

    NASA Technical Reports Server (NTRS)

    Wilson, R. M.

    1977-01-01

    An event compilation is presented which correlates ATM/S-056 X-ray event analyzer solar observations with solar flare activity. Approximately 1,070 h of pulse height analyzed X-ray proportional counter data were obtained with the X-ray event analyzer during Skylab. During its operation, 449 flares (including 343 flare peaks) were observed. Seventy events of peak X-ray emission or = Cl were simultaneously observed by ground based telescopes, SOLRAD 9 and/or Vela, and the X-ray event analyzer. These events were observed from preflare through flare rise to peak and through flare decline.

  13. 313 new asteroid rotation periods from Palomar Transient Factory observations

    SciTech Connect

    Chang, Chan-Kao; Ip, Wing-Huen; Lin, Hsing-Wen; Cheng, Yu-Chi; Ngeow, Chow-Choong; Yang, Ting-Chang; Waszczak, Adam; Kulkarni, Shrinivas R.; Levitan, David; Sesar, Branimir; Prince, Thomas A.; Laher, Russ; Surace, Jason

    2014-06-10

    A new asteroid rotation period survey has been carried out by using the Palomar Transient Factory (PTF). Twelve consecutive PTF fields, which covered an area of 87 deg{sup 2} in the ecliptic plane, were observed in the R band with a cadence of ∼20 minutes during 2013 February 15-18. We detected 2500 known asteroids with a diameter range of 0.5 km ≤D ≤ 200 km. Of these, 313 objects had highly reliable rotation periods and exhibited the 'spin barrier' at ∼2 hr. In contrast to the flat spin-rate distribution of the asteroids with 3 km ≤D ≤ 15 km shown by Pravec et al., our results deviated somewhat from a Maxwellian distribution and showed a decrease at the spin rate greater than 5 rev day{sup –1}. One superfast rotator candidate and two possible binary asteroids were also found in this work.

  14. Space based observations for monitoring extreme weather and climate events

    SciTech Connect

    Rao, P.K.

    1996-12-31

    Observations are essential for monitoring, understanding, and predicting the potential for extreme weather and climate events. These events occur on all time and spatial scales. Current NOAA operational satellites have a unique capability of providing many of the observations that are critical for monitoring these events. These observations and derived geophysical quantities can also be used for diagnostics and prediction purposes. Extreme weather conditions such as severe thunderstorms and flash floods, occur very quickly, may last for a short time, and create a considerable amount of damage. Advance warnings of the order of a few minutes are needed to alert the public so they may take adequate precautions. Some extreme weather conditions such as tropical storms (hurricanes) may last for days, and in order to predict the exact track, intensity of the storm and forecast the land fall, frequent observations are critical. Examples of satellite data that are obtained from the NOAA satellites are presented to demonstrate their ability to monitor the extreme weather phenomena. Examples of extreme climate conditions are droughts over continents and the annual depletion of ozone over the Antarctic. Data derived from NOAA satellites were used to monitor the severe drought over Texas and Southwestern U.S.A. in early 1996. Similar data are being used by other countries to monitor the drought in their regions. The development of the ozone hole over the Antarctic during the last fifteen years has been a major scientific and environmental concern. Data from NOAA operational satellites have been extensively used to show the yearly development and dissipation of the ozone hole during the Southern Hemisphere springtime.

  15. Equatorial Emissions Events in the Inner Magnetosphere from THEMIS Observations

    NASA Astrophysics Data System (ADS)

    Wang, K.; Chen, R.; Tam, W. Y.; Chen, L.; Jan, Y.; Yang, Y.

    2013-12-01

    Two specific emission events near equator are found by analyzing wave data from SCM (Search Coil Magnetometer) and EFI (Electric Field Instrument) of THEMIS mission in the local afternoon sector for the year of 2008. These events are both with emissions of frequencies at about 70Hz and 110Hz, between the local proton gyrofrequency fcH+ and the lower hybrid frequency flhr, around 5RE. The analyzed wave vectors are shown to be nearly perpendicular to the ambient geomagnetic fields. The observed ion velocity distributions at the same time exhibit ring features at about 3600 km/sec in perpendicular velocity, which is larger than the local Alfvén velocity. Wave growth rates over different frequencies are calculated to compare with the emission intensity at different frequencies based on dispersion relation of magnetosonic waves.

  16. Limb Event Brightenings and Fast Ejection Using IRIS Mission Observations

    NASA Astrophysics Data System (ADS)

    Tavabi, E.; Koutchmy, S.; Golub, L.

    2015-10-01

    The Interface Region Imaging Spectrograph (IRIS) of the recently commissioned NASA small explorer mission provides significantly more complete and higher resolution spectral coverage of the dynamical conditions inside the chromosphere and transition region (TR) than has been available ever before. High temporal, spatial (0.3'') and spectral resolution observations from the ultraviolet IRIS spectra near the solar limb reveal high-energy limb event brightenings (LEBs) at low chromospheric heights at about 1 Mm above the limb. They can be characterized as explosive events producing jets. We selected two events showing spectra of a confined eruption just off or near the quiet-Sun limb, the jet part showing obvious moving material with short-duration large Doppler shifts in three directions that were identified as macrospicules on slit-jaw (SJ) images in Si iv and He ii 304 Å. The events were analyzed from a sequence of very close rasters taken near the central meridian and the South Pole limb. We analyzed the processed SJ images and the simultaneously observed fast spectral sequences, which have large Doppler shifts, with a pair of redshifted elements together with a faster blueshifted element from almost the same position. Shifts correspond to velocities of up to 100 km s^{-1} in projection on the plane of the sky. Erupting spicules and macrospicules from these regions are visible in images taken before and after the spectra. The cool low first ionization potential (FIP) element simultaneous line emissions of the Mg ii h and k resonance lines do not clearly show a similar signature because of optical thickness effects, but the Si iv broadband SJ images do. The bidirectional plasma jets ejected from a small reconnection site are interpreted to be the result of coronal loop-loop interactions that lead to reconnection in nearby sites.

  17. Coordinated Solar Observation and Event Searches using the Heliophysics Events Knowledgebase (HEK)

    NASA Astrophysics Data System (ADS)

    Timmons, Ryan; Hurlburt, Neal E.; De Pontieu, Bart

    2016-05-01

    We present capabilities of the HEK for joint searches, returning overlapping data from multiple instruments (IRIS, Hinode) that also include particular solar features and events (active regions, (large) flares, sunspots, etc.). The new search tools aid the process of finding observations of particular interest from non-synoptic instruments. They also include new data products: processed cutout cubes of SOT-FG and AIA data co-aligned with IRIS.

  18. VLP-Discriminated Strombolian Event Families and Video Observations at Mount Erebus, Antarctica

    NASA Astrophysics Data System (ADS)

    Aster, R. C.; Mah, S. Y.; McNamara, S.; Ruiz, M.; Kyle, P.; McIntosh, W.; Dunbar, N.

    2002-12-01

    Strombolian eruptive activity from the phonolitic lava lake of Mt. Erebus generates VLP (Very Long Period) signals with spectral components as grave as 20 s. These signals have been observed on a seasonal basis with broadband seismometers during three Antarctic field seasons in targeted PASSCAL deployments and, more recently, with permanently installed broadband seismometers. Associated eruptive and other lava lake behavior has also been observed since 2000 with a time-stamped crater surveillance video camera. VLP signals persist for several minutes during lava lake refilling following eruptions and have highly similar waveform characteristics from event to event. The initial few seconds of signal associated with the pre-eruptive phase, however, exhibit significant variations and can be readily classified into 3 families, two simply based on initial polarity. A third event family, infrequently observed, shows a very different pulse-like shape and different frequency content. Video observation of eruptions suggest a correlation between the eruptive character and the initial polarity of the event. Positive polarity events have a vertical, jet-like eruptive style, while negative polarity events feature more radial ejecta. All lava lake eruptions are due to simple Strombolian gas slugs nucleating in the near-summit conduit system, becoming dislodged from buoyancy forces, and rising nearly intact to the lake surface. Distinct families of eruptive styles from a single vent and their correlation with VLP signals generated by ascent forces suggest distinct source zones and/or delivery paths of gas slugs to the lava lake surface.

  19. Solar particle events observed at Mars: dosimetry measurements and model calculations

    NASA Technical Reports Server (NTRS)

    Cleghorn, Timothy F.; Saganti, Premkumar B.; Zeitlin, Cary J.; Cucinotta, Francis A.

    2004-01-01

    During the period from March 13, 2002 to mid-September, 2002, six solar particle events (SPE) were observed by the MARIE instrument onboard the Odyssey Spacecraft in Martian Orbit. These events were observed also by the GOES 8 satellite in Earth orbit, and thus represent the first time that the same SPE have been observed at these separate locations. The characteristics of these SPE are examined, given that the active regions of the solar disc from which the event originated can usually be identified. The dose rates at Martian orbit are calculated, both for the galactic and solar components of the ionizing particle radiation environment. The dose rates due to galactic cosmic rays (GCR) agree well with the HZETRN model calculations. Published by Elsevier Ltd on behalf of COSPAR.

  20. Solar particle events observed at Mars: dosimetry measurements and model calculations.

    PubMed

    Cleghorn, Timothy F; Saganti, Premkumar B; Zeitlin, Cary J; Cucinotta, Francis A

    2004-01-01

    During the period from March 13, 2002 to mid-September, 2002, six solar particle events (SPE) were observed by the MARIE instrument onboard the Odyssey Spacecraft in Martian Orbit. These events were observed also by the GOES 8 satellite in Earth orbit, and thus represent the first time that the same SPE have been observed at these separate locations. The characteristics of these SPE are examined, given that the active regions of the solar disc from which the event originated can usually be identified. The dose rates at Martian orbit are calculated, both for the galactic and solar components of the ionizing particle radiation environment. The dose rates due to galactic cosmic rays (GCR) agree well with the HZETRN model calculations. PMID:15791734

  1. MESSENGER Observations of Large Flux Transfer Events at Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Lepping, Ronald P.; Wu, Chin-Chun; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Killen, Rosemary M.; Korth, Haje; Krimigis, Stamatios M.; McClintock, William E.; McNutt, Ralph L., Jr.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Travnicek, Pavel; Zurbuchen, Thomas H.

    2010-01-01

    Six flux transfer events (FTEs) were encountered during MESSENGER's first two flybys of Mercury (M1 and M2). For M1 the interplanetary magnetic field (IMF) was predominantly northward and four FTEs with durations of 1 to 6 s were observed in the magnetosheath following southward IMF turnings. The IMF was steadily southward during M2, and an FTE 4 s in duration was observed just inside the dawn magnetopause followed approx. 32 s later by a 7 s FTE in the magnetosheath. Flux rope models were fit to the magnetic field data to determine FTE dimensions and flux content. The largest FTE observed by MESSENGER had a diameter of approx. 1 R(sub M) (where R(sub M) is Mercury s radius), and its open magnetic field increased the fraction of the surface exposed to the solar wind by 10 - 20 percent and contributed up to approx. 30 kV to the cross-magnetospheric electric potential.

  2. MESSENGER Observations of Large Flux Transfer Events at Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Lepping, Ronald P.; Wu, Chin-Chun; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Killen, Rosemary M.; Korth, Haje; Krimigis, Stamatios M.; McClintock, William E.; McNutt, Ralph L., Jr.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Travnicek, Pavel; Zurbuchen, Thomas H.

    2010-01-01

    Six flux transfer events (FTEs) were encountered during MESSENGER's first two flybys of Mercury (MI and M2). For MI the interplanetary magnetic field (IMF) was predominantly northward and four FTEs with durations of 1 to 6 s were observed in the magnetosheath following southward 1M F turnings. The IMF was steadily southward during M2, and an FTE 4 s in duration was observed just inside the dawn magnetopause followed approx.32 s later by a 7-s FTE in the magnetosheath. Flux rope models were fit to the magnetic field data to detem11ne PTE dimensions and flux content The largest FTE observed by MESSENGER had a diameter of approx. 1 R(sub M) (where R(sub M) is Mercury's radius), and its open magnetic field increased the fraction of the surface exposed to the solar wind by 10 - 20 percent and contributed up to approx.30 kV to the cross-magnetospheric electric potential.

  3. Substorms observations during two geomagnetically active periods in March 2012 and March 2015

    NASA Astrophysics Data System (ADS)

    Guineva, V.; Despirak, I.; Kozelov, B.

    2016-05-01

    In this work two events of strong geomagnetic activity were examined: the period 7-17 March 2012, which is one of the most disturbed periods during the ascending phase of Solar Cycle 24, and the severe geomagnetic storm on 17-20 March 2015. During the first period four consecutive magnetic storms occurred on 7, 9, 12, and 15 March. These storms were caused by Sheath, MC and HSS, and the detailed scenarios for the storms were different. The second event is a storm of fourth level with Kp = 8, the strongest one during the last four years, the so-called "St. Patrick's Day 2015 Event". A geomagnetic storm of such intensity was observed in September 2011. Our analysis was based on the 10-s sampled IMAGE magnetometers data, the 1-min sampled OMNI solar wind and interplanetary magnetic field (IMF) data and observations of the Multiscale Aurora Imaging Network (MAIN) in Apatity. The particularities in the behaviours of substorms connected with different storms during these two interesting strongly disturbed periods are discussed.

  4. 35 Cascadia Episodic Tremor and Slip events observed on GPS, seismic, and strain/tiltmeter arrays

    NASA Astrophysics Data System (ADS)

    Melbourne, T. I.; Aguiar, A. C.; Santillan, V. M.; Szeliga, W.; Miller, M.

    2007-12-01

    Several rapidly expanding GPS networks along the greater Cascadia forearc have enabled identification of 36 isolated Episodic Tremor and Slip (ETS) events since 1997, including two in 2007. ETS events are observed throughout the forearc, from northern California to southwestern British Columbia, with station density generally increasing towards the north. Events located in well-instrumented regions can be tracked as they migrate laterally north-south along the plate boundary, but increasing station density has resolved many smaller transients that could not previously be confidently identified. At the specific latitude of the northern Washington State and southwestern British Columbia, the 14-month average recurrence interval still holds true, 5 events after first recognition. Elsewhere, this periodicity is not observed. Along central Vancouver Island, a host of smaller events distinct from the 14-month recurrence occur with an aperiodic fashion. Sporadic smaller events also appear throughout the subduction zone to the south, including within the region known for the 14-month periodicity. In southern Washington State, some of the largest transient displacements are observed, but lack any obvious periodicity in their recurrence. Along central Oregon, an 18-month recurrence is evident, while in northern California (Yreka) the 11-month periodicity previously documented still holds true. We invert estimated GPS offsets for the largest 14 events using non-negative thrust faulting along a plate interface divided into roughly 500 subfaults. Those events have equivalent moment magnitudes ranging from 6.3 (smallest resolvable with GPS) to 6.8, and typically 2-3 cm of slip. The largest spatial extent of the events resolved to date is just under 500 km along strike, and maximum duration is seven weeks, which lies in marked contrast to other subduction zones. Averaged over many ETS events, the upper limit of transient slip in the vicinity of Seattle, WA lies just west of the

  5. Quantifying uncertainties in location and source mechanism for Long-Period events at Mt Etna, Italy.

    NASA Astrophysics Data System (ADS)

    Cauchie, Léna; Saccorotti, Gilberto; Bean, Christopher

    2014-05-01

    The manifestation of Long-Period events is documented at many volcanoes worldwide. However the mechanism at their origin is still object of discussion. Models proposed so far involve (i) the resonance of fluid-filled cracks or conduits that are triggered by fluid instabilities or the brittle failure of high viscous magmas and (ii) the slow-rupture earthquakes in the shallow portion of volcanic edifices. Since LP activity usually precedes and accompanies volcanic eruption, the understanding of these sources is important in terms of hazard assessment and eruption early warning. The work is thus primarily aimed at the assessment of the uncertainties in the determination of LP source properties as a consequence of poor knowledge of the velocity structure and location errors. We used data from temporary networks deployed on Mt Etna in 2005. During August, 2005, about 13000 LP events were detected through a STA/LTA approach, and were classified into two families on the basis of waveform similarity. For each family of events, we located the source using three different approaches: (1) a single-station-location method based on the back-propagation of the polarization vector estimated from covariance analysis of three-component signals; (2) multi-channel analysis of data recorded by two seismic arrays; (3) relative locations based on inversion of differential times obtained through cross-correlation of similar waveforms. For all these three different methods, the solutions are very sensitive to the chosen velocity model. We thus iterated the location procedure for different medium properties; the preferred velocity is that for which the results obtained with the three different methods are consistent each other. For each family, we then defined a volume of possible source location and performed a full-waveform, moment tensor (MT) inversion for the entire catalog of events. In this manner, we obtained a MT solution for each grid node of the investigated volume. The MT

  6. Current reduction in a pseudo-breakup event: THEMIS observations

    NASA Astrophysics Data System (ADS)

    Yao, Z. H.; Pu, Z. Y.; Owen, C. J.; Fu, S. Y.; Chu, X. N.; Liu, J.; Angelopoulos, V.; Rae, I. J.; Yue, C.; Zhou, X.-Z.; Zong, Q.-G.; Cao, X.; Shi, Q. Q.; Forsyth, C.; Du, A. M.

    2014-10-01

    Pseudo-breakup events are thought to be generated by the same physical processes as substorms. This paper reports on the cross-tail current reduction in an isolated pseudo-breakup observed by three of the THEMIS probes (THEMIS A (THA), THEMIS D (THD), and THEMIS E (THE)) on 22 March 2010. During this pseudo-breakup, several localized auroral intensifications were seen by ground-based observatories. Using the unique spatial configuration of the three THEMIS probes, we have estimated the inertial and diamagnetic currents in the near-Earth plasma sheet associated with flow braking and diversion. We found the diamagnetic current to be the major contributor to the current reduction in this pseudo-breakup event. During flow braking, the plasma pressure was reinforced, and a weak electrojet and an auroral intensification appeared. After flow braking/diversion, the electrojet was enhanced, and a new auroral intensification was seen. The peak current intensity of the electrojet estimated from ground-based magnetometers, ~0.7 × 105 A, was about 1 order of magnitude lower than that in a typical substorm. We suggest that this pseudo-breakup event involved two dynamical processes: a current-reduction associated with plasma compression ahead of the earthward flow and a current-disruption related to the flow braking/diversion. Both processes are closely connected to the fundamental interaction between fast flows, the near-Earth ambient plasma, and the magnetic field.

  7. OMI Tropospheric NO2 from Lightning in Observed Convective Events

    NASA Technical Reports Server (NTRS)

    Pickering, Kenneth; Bucsela, Eric; Gleason, James; Levelt, Pieternel

    2007-01-01

    Lightning is responsible for an estimated 10-20% of NO(x) emissions in the troposphere. In this study, we present evidence of lightning-generated NO2 (LNO2) using data from the Ozone Monitoring Instrument (OMI), which has observed tropospheric NO2 since its launch in 2004. Although LNO2 has been also reported in previous satellite studies from the Global Ozone Monitoring Experiment (GOME) and SCIAMACHY, OMI is better suited for such measurements by virtue of its higher resolution and daily global coverage. The LNO2 signal is clearly seen in OMI data on two days over and downwind of convective systems in the US Midwest in 2006. We also present an analysis of OMI data over northern Australia during the SCOUT-O3/ACTIVE field campaigns in November and December 2005. Both single- and multi-day averages are presented to examine possible LNO2 signals from individual diurnally recurrent convective events. In these events we compare the OMI signals with aircraft observations from the storm anvils.

  8. Characteristics of extreme rainfall events in northwestern Peru during the 1982-1983 El Nino period

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Tisnado, G. M.; Scofield, R. A.

    1987-01-01

    Histograms and contour maps describing the daily rainfall characteristics of a northwestern Peru area most severely affected by the 1982-1983 El Nino event were prepared from daily rainfall data obtained from 66 stations in this area during the El Nino event, and during the same 8-month intervals for the two years preceding and following the event. These data were analyzed, in conjunction with the anlysis of visible and IR satellite images, for cloud characteristics and structure. The results present a comparison of the rainfall characteristics as a function of elevation, geographic location, and the time of year for the El Nino and non-El Nino periods.

  9. Calculation of 239Pu fission observables in an event-by-event simulation

    SciTech Connect

    Vogt, R; Randrup, J; Pruet, J; Younes, W

    2010-03-31

    The increased interest in more exclusive fission observables has demanded more detailed models. We describe a new computational model, FREYA, that aims to meet this need by producing large samples of complete fission events from which any observable of interest can then be extracted consistently, including any interesting correlations. The various model assumptions are described and the potential utility of the model is illustrated. As a concrete example, we use formal statistical methods, experimental data on neutron production in neutron-induced fission of {sup 239}Pu, along with FREYA, to develop quantitative insights into the relation between reaction observables and detailed microscopic aspects of fission. Current measurements of the mean number of prompt neutrons emitted in fission taken together with less accurate current measurements for the prompt post-fission neutron energy spectrum, up to the threshold for multi-chance fission, place remarkably fine constraints on microscopic theories.

  10. Long period pulsation events in electron precipitation and magnetic fields at the South Pole

    SciTech Connect

    Paquette, J.A.

    1992-01-01

    Geomagnetic pulsation events with long (100-1000 second) periods that are accompanied by electron precipitation pulsations at the same frequency were reported at various latitudes. A search of the data from South Pole station for the period from 1982 to 1989 revealed over 200 such events. A comparison of these events with the predictions of Coroniti and Kennel was undertaken, including examination of VLF data, interplanetary magnetic field data, DMSP satellite data, and data from South Pole's conjugate station at Iqaluit, as well as the riometer and magnetometer data from South Pole used in the original search. Data from the IRIS Imaging Radiometer were also used when available. A consideration of the respective wave and particle transit times from the magnetic equator to the ground leads to an expectation that the onset of pulsations in the magnetometer data will lag the onset of pulsations in the riometer data by several minutes. This disparity in onset times, together with VLF modulation in the proper frequency range, serve as important indicators of whether or not an event can be explained by the above-cited theory. While about a third of the events fit the prediction of Coroniti and Kennel, another third cannot be explained by this theory, and possible alternative mechanisms are explored. The remaining third of the events appear at first to be inexplicable in terms of any transit time argument, but analysis of the IRIS data shows that this third class of events arises from differences in the spatial coverage of the instruments.

  11. W-band spaceborne radar observations of atmospheric river events

    NASA Astrophysics Data System (ADS)

    Matrosov, S. Y.

    2010-12-01

    While the main objective of the world first W-band radar aboard the CloudSat satellite is to provide vertically resolved information on clouds, it proved to be a valuable tool for observing precipitation. The CloudSat radar is generally able to resolve precipitating cloud systems in their vertical entirety. Although measurements from the liquid hydrometer layer containing rainfall are strongly attenuated, special retrieval approaches can be used to estimate rainfall parameters. These approaches are based on vertical gradients of observed radar reflectivity factor rather than on absolute estimates of reflectivity. Concurrent independent estimations of ice cloud parameters in the same vertical column allow characterization of precipitating systems and provide information on coupling between clouds and rainfall they produce. The potential of CloudSat for observations atmospheric river events affecting the West Coast of North America is evaluated. It is shown that spaceborne radar measurements can provide high resolution information on the height of the freezing level thus separating areas of rainfall and snowfall. CloudSat precipitation rate estimates complement information from the surface-based radars. Observations of atmospheric rivers at different locations above the ocean and during landfall help to understand evolutions of atmospheric rivers and their structures.

  12. Event-based internet biosurveillance: relation to epidemiological observation

    PubMed Central

    2012-01-01

    Background The World Health Organization (WHO) collects and publishes surveillance data and statistics for select diseases, but traditional methods of gathering such data are time and labor intensive. Event-based biosurveillance, which utilizes a variety of Internet sources, complements traditional surveillance. In this study we assess the reliability of Internet biosurveillance and evaluate disease-specific alert criteria against epidemiological data. Methods We reviewed and compared WHO epidemiological data and Argus biosurveillance system data for pandemic (H1N1) 2009 (April 2009 – January 2010) from 8 regions and 122 countries to: identify reliable alert criteria among 15 Argus-defined categories; determine the degree of data correlation for disease progression; and assess timeliness of Internet information. Results Argus generated a total of 1,580 unique alerts; 5 alert categories generated statistically significant (p < 0.05) correlations with WHO case count data; the sum of these 5 categories was highly correlated with WHO case data (r = 0.81, p < 0.0001), with expected differences observed among the 8 regions. Argus reported first confirmed cases on the same day as WHO for 21 of the first 64 countries reporting cases, and 1 to 16 days (average 1.5 days) ahead of WHO for 42 of those countries. Conclusion Confirmed pandemic (H1N1) 2009 cases collected by Argus and WHO methods returned consistent results and confirmed the reliability and timeliness of Internet information. Disease-specific alert criteria provide situational awareness and may serve as proxy indicators to event progression and escalation in lieu of traditional surveillance data; alerts may identify early-warning indicators to another pandemic, preparing the public health community for disease events. PMID:22709988

  13. Pluvial Period over NE Brazil linked to Heinrich Stadial Event 1

    NASA Astrophysics Data System (ADS)

    Wendt, Kathleen A.; Berry, Akemi; Häuselmann, Anamaria; Fleitmann, Dominik; Wang, Xianfeng; Auler, Augusto S.; Cheng, Hai; Edwards, R. Lawrence

    2016-04-01

    The precise timing of Heinrich Stadial (HS) 1 and its impact on tropical regions remain a topic of active debate. We present a high-resolution precipitation record of HS-1 using a stalagmite collected from Toca da Barriguda cave located in the interior of NE Brazil (40o51'39"W 10o09'36"S, 600m asl). Stalagmite growth in this region is caused by increased rainfall due to a southerly displacement of the Intertropical Convergence Zone (ITCZ) during HS Events. Stalagmite TBR14 includes a 107mm calcitic growth phase 230Th dated from 17070 ±40 to 15640 ±65 BP, which we interpret to be the period of rainfall maximum over NE Brazil in association with HS-1. Oxygen isotope analysis reveals a two-stepped structure to the HS-1 pluvial period: starting with a 970-year period of δ18O values averaging -5‰ followed by an abrupt 2.5‰ drop between 16100 to 16080 BP (±20). We infer that rainfall amount increased during this time, as supported by the modern day observation of anti-correlated δ18O values and precipitation amount. A second step of the HS-1 growth phase shows a gradual increase from -7‰ over 440 years followed by the termination of stalagmite growth. Fluorescent banding was discovered throughout the stalagmite using confocal laser fluorescence microscopy. If annual, band counts may add additional constrains to the duration of the abrupt decrease in δ18O values observed at 16100 BP (±20). The two-stepped δ18O pattern observed in our stalagmite record may correlate in detail with other low-latitude high-resolution records of HS-1 such as the Hulu Cave record (Wang et al. 2001) from China, in which an abrupt (2.2) weakening of the East Asian Monsoon at 16070 BP (±40) is followed by a 600 year recovery (decreasing) of δ18O values. The possible anti-phase relationship between these two distant records is concurrent with the hypothesis of a southward migrating ITCZ, and suggests rapid transmission of atmospheric signals during HS-1.

  14. Pattern of cryospheric seismic events observed at Ekström Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Hammer, Conny; Ohrnberger, Matthias; Schlindwein, Vera

    2015-05-01

    Mobility of glaciers such as rapid retreat or disintegration of large ice volumes produces a large variety of different seismic signals. Thus, evaluating cryospheric seismic events (e.g., changes of their occurrence in space and time) allows to monitor glacier dynamics. We analyze a 1 year data span recorded at the Neumayer seismic network in Antarctica. Events are automatically recognized using hidden Markov models. In this study we focused on a specific event type occurring close to the grounding line of the Ekström ice shelf. Observed waveform characteristics are consistent with an initial fracturing followed by the resonance of a water-filled cavity resulting in a so-called hybrid event. The number of events detected strongly correlates with dominant tide periods. We assume the cracking to be driven by existing glacier stresses trough bending. Voids are then filled by seawater, exciting the observed resonance. In agreement with this model, events occur almost exclusively during rising tides where cavities are opened at the bottom of the glacier, i.e., at the sea/ice interface.

  15. Observations of ozone depletion associated with solar proton events

    NASA Technical Reports Server (NTRS)

    Mcpeters, R. D.; Jackman, C. H.; Stassinopoulos, E. G.

    1981-01-01

    Ozone profiles from the solar proton events (SPE) of January and September 1971 and August 1972 were obtained after the backscattered ultraviolet (BUV) measured radiances were corrected for the direct effects of protons on the instrument. The SPE of August 1972 produced an ozone depletion of 15% at 42 km that persisted for one month in both northern and southern polar regions. This long recovery time indicates that NO(x) was produced in a quantity sufficient to alter the ozone chemistry. The two SPE in 1971 were of moderate size, but produced ozone depletions of 10-30% at 50 km with a 36 hour recovery time. This rapid recovery is consistent with the assumption that HO(x) is responsible for altering the ozone chemistry (Weeks et al., 1972). The magnitude of the observed depletion, however, exceeds that predicted by the chemical models.

  16. Fermi-LAT Observations of the LIGO Event GW150914

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Anderson, B.; Arimoto, M.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Becerra Gonzalez, J.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Britto, R. J.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Cohen-Tanugi, J.; Cominsky, L. R.; Condon, B.; Costanza, F.; Cuoco, A.; Cutini, S.; D’Ammando, F.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Domínguez, A.; Drell, P. S.; Dubois, R.; Dumora, D.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Giglietto, N.; Giomi, M.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gomez-Vargas, G. A.; Granot, J.; Green, D.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Jogler, T.; Jóhannesson, G.; Kamae, T.; Kensei, S.; Kocevski, D.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Magill, J.; Maldera, S.; Manfreda, A.; Marelli, M.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Meyer, M.; Michelson, P. F.; Mirabal, N.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Negro, M.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Romani, R. W.; Saz Parkinson, P. M.; Sgrò, C.; Simone, D.; Siskind, E. J.; Smith, D. A.; Spada, F.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tajima, H.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Troja, E.; Uchiyama, Y.; Venters, T. M.; Vianello, G.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zhu, S.; Zimmer, S.

    2016-05-01

    The Fermi Large Area Telescope (LAT) has an instantaneous field of view (FoV) covering ∼ 1/5 of the sky and it completes a survey of the entire sky in high-energy gamma-rays every 3 hr. It enables searches for transient phenomena over timescales from milliseconds to years. Among these phenomena could be electromagnetic counterparts to gravitational wave (GW) sources. In this paper, we present a detailed study of the LAT observations relevant to Laser Interferometer Gravitational-wave Observatory (LIGO) event GW150914, which is the first direct detection of gravitational waves and has been interpreted as being due to the coalescence of two stellar-mass black holes. The localization region for GW150914 was outside the LAT FoV at the time of the GW signal. However, as part of routine survey observations, the LAT observed the entire LIGO localization region within ∼70 minutes of the trigger and thus enabled a comprehensive search for a γ-ray counterpart to GW150914. The study of the LAT data presented here did not find any potential counterparts to GW150914, but it did provide limits on the presence of a transient counterpart above 100 MeV on timescales of hours to days over the entire GW150914 localization region.

  17. The discovery of 50 minute periodic absorption events from 4U1915-05

    NASA Technical Reports Server (NTRS)

    White, N. E.; Swank, J. H.

    1981-01-01

    The steady flux from 4U1916-05 which undergoes periodic absorption dips every 50 minutes was demonstrated. This period represents the underlying orbital period of the system. It is suggested that variations in the depth and duration of these events are caused by a bulge in the edge of the accretion disk, at the point where the gas stream impacts the disk. The mass losing star in this system is probably a low mass white dwarf. The spectrum of the dips indicates that the metallicity of the absorbing material is at least a factor 17 below solar values.

  18. The Use of Ensemble-Based Sensitivity with Observations to Improve Predictability of Severe Convective Events

    NASA Astrophysics Data System (ADS)

    Ancell, B. C.; Hill, A. J.; Burghardt, B.

    2014-12-01

    Ensemble sensitivity can reveal important weather features early in a forecast window relevant to the predictability of high-impact events later in time. Sensitivity has been shown on synoptic scales with simulated observations to be useful in identifying ensemble subsets that are more likely than the full ensemble mean, which may potentially add value to operational guidance of high-impact events. On convective scales, with highly nonlinear ensemble perturbation evolution and very non-Gaussian distributions of severe weather responses (e.g., simulated reflectivity above some threshold), it becomes more difficult to apply linear-based ensemble sensitivity to improve predictability of severe events. Here we test the ability of ensemble sensitivity to improve predictability of a severe convective event through identifying errors in sensitive regions of different members early in a forecast period using radar and surface-based observations. In this case, through the inspection of a number of operational models, an overnight mesoscale convective system (MCS) and its associated cold pool appeared to strongly influence whether or not severe convection would occur the following afternoon. Since both the overnight MCS and next-day convection are associated with strong nonlinearity and non-Gaussian distributions in the ensemble, this case allows a rigid test of using ensemble sensitivity and related techniques with observations for convective events. The performance of the sensitivity-based technique will be presented, and integration into an operational tool for severe convection will be discussed.

  19. Periodicity in the spatial-temporal earthquake distributions for the Pacific region: observation and modeling.

    NASA Astrophysics Data System (ADS)

    Sasorova, Elena; Levin, Boris

    2014-05-01

    In the course of the last century a cyclic increasing and decreasing of the Earth's seismic activity (SA) was marked. The variations of the SA for the events with M>=7.0 from 1900 up to date were under study. The two subsets of the worldwide NEIC (USGS) catalog were used: USGS/NEIC from 1973 to 2012 and catalog of the significant worldwide earthquakes (2150 B.C. - 1994 A.D.), compiled by USGS/NEIC from the NOAA agency. The preliminary standardization of magnitudes and elimination of aftershocks from list of events was performed. The entire period of observations was subdivided into 5-year intervals. The temporal distributions of the earthquake (EQ) density and released energy density were calculated separately for the Southern hemisphere (SH), and for the Northern hemisphere (NH) and for eighteen latitudinal belts: 90°-80°N, 80°-70°N, 70°-60°N, 60°-50°N and so on (the size of each belt is equal to 10°). The periods of the SA was compared for different latitudinal belts of the Earth. The peaks and decays of the seismicity do not coincide in time for different latitudinal belts and especially for the belts located in NH and SH. The peaks and decays of the SA for the events (with M>=8) were marked in the temporal distributions of the EQ for all studied latitudinal belts. The two-dimension distributions (over latitudes and over time) of the EQ density and released energy density highlighted that the periods of amplification of the SA are equal to 30-35 years approximately. Next, we check the existence of a non-random component in the EQ occurrence between the NH and the SH. All events were related to the time axis according to their origin time. We take into consideration the set of the EQs in the studied catalog as the sequence of events if each event may have only one of two possible outcome (occurrence in the NH or in the SH). A nonparametric run test was used for testing of hypothesis about an existence the nonrandom component in the examined sequence of

  20. The first massive astronomical observation event in Mexico City

    NASA Astrophysics Data System (ADS)

    Espinosa, Mariana; Hernandez, Xavier

    2011-06-01

    On the night of the 20th of February 2008 there was a total eclipse of the moon visible from Mexico City, with a total duration from 19:42 hrs to 23:09 hrs. At the Instituto de Astronomía, UNAM, we took this opportunity to organise a massive astronomical party on the central plaza of the city, the Zocalo. Over a period of about 6 hrs. we set up a huge astro-party, with free use of over 100 telescopes, where we estimate over 40,000 persons looked through an astronomical telescope at the moon and Saturn, most for the first time in their lives. Numerous stands including a children's games, an Astronomy conference room, and the free distribution of Astronomical material were organised. Here we describe some of the issues associated with the planning and implementation of the event. Coordination issues were complex, involving interaction with divers and numerous authorities, city, national, police, traffic, medical assistance in readiness, aide from other universities, and amateur astronomical societies, which supplied most of the telescopes. An extensive publicity campaign was launched with several weeks of anticipation, and although we had no way of estimating the public response, we were ready with over 800 volunteers at the Zócalo on the 20th of February. The public response was massive and overwhelmingly positive, thousands swarmed the square in a completely peaceful and well organised interaction between Astronomy and society at large, over many complementary levels

  1. Correlation between tectonic events in the most recent period of earth evolution

    NASA Astrophysics Data System (ADS)

    Kukina, N. V.; Makarov, V. I.; Trifonov, V. G.; Volchkova, G. I.

    Methods used in correlating various neotectonic events are described, together with a general discussion of short-lived changes in tectonic activity. Neotectonic events in the Carpathian-Caucasus-Kopetdag segment and in ancient folded areas (including Tien Shan and segments of Rhodope mountains) of the Alpine-Asian orogenic belt are analyzed. Correlation of neotectonic events of the earth's mobile belts revealed the presence in the earth crust of segments which are characterized by the synchronism of the most important events in tectonic activity. Common activating phases disclosed in these areas indicate the presence of global rhythmicity in tectogenesis. In addition, the studies have uncovered some specificities in the neotectonic stage of the Mesozoic-Cenozoic period of the earth evolution.

  2. Oscillation of a Shallow Hydrothermal Fissure Inferred from Long-Period Seismic Events at Taal Volcano, the Philippines

    NASA Astrophysics Data System (ADS)

    Maeda, Y.; Kumagai, H.; Lacson, R.; Figueroa, M. S.; Yamashina, T.

    2012-12-01

    We installed a multi-parameter monitoring network including five broadband seismometers at Taal volcano, the Philippines, where a high risk of near-future eruption is expected. The network detected more than 40,000 long-period (LP) seismic events which have a peak frequency of 0.8 Hz and a Q value of 6. Most of the events occurred in a 2-month-long swarm period of ~600 events/day. Our travel time analysis pointed to a shallow source (100-200 m) beneath the northeastern flank of the active volcanic island. To determine the source mechanism of the LP events, we performed waveform inversion. We first fixed the source location to that obtained by the travel time analysis, and performed inversion using waveforms with and without site amplification corrections and assuming four simple source geometries (a vertical crack, a horizontal crack, a vertical pipe, and a sphere). We obtained the minimum AIC value for the vertical crack source geometry using the corrected waveforms. We next performed a grid search for dip, azimuth, and the location of the tensile crack source using the corrected waveforms. We obtained small residuals for crack dips between 30 and 60 degrees at similar locations to that of the travel time analysis. We used the fluid-filled crack model to interpret the observed complex frequencies of the events. The observed waveforms of the events show a small Q value (= 6), which may be explained by bubbly basalt, bubbly water, or gas. However, since the source location is estimated to be shallow (100-200 m) and we have no evidence for an ascent of magma to such a shallow depth in the swarm period, bubbly basalt seems to be unrealistic. It seems difficult to maintain bubbly water in the inclined crack. For bubbly water, a peak frequency variation is expected to occur due to a variation of the bubble content, whereas the observed peak frequencies of the events are almost constant. The constant frequency is more easily realized by gas in a crack. We therefore

  3. Recurrent event data analysis with intermittently observed time-varying covariates.

    PubMed

    Li, Shanshan; Sun, Yifei; Huang, Chiung-Yu; Follmann, Dean A; Krause, Richard

    2016-08-15

    Although recurrent event data analysis is a rapidly evolving area of research, rigorous studies on estimation of the effects of intermittently observed time-varying covariates on the risk of recurrent events have been lacking. Existing methods for analyzing recurrent event data usually require that the covariate processes are observed throughout the entire follow-up period. However, covariates are often observed periodically rather than continuously. We propose a novel semiparametric estimator for the regression parameters in the popular proportional rate model. The proposed estimator is based on an estimated score function where we kernel smooth the mean covariate process. We show that the proposed semiparametric estimator is asymptotically unbiased, normally distributed, and derives the asymptotic variance. Simulation studies are conducted to compare the performance of the proposed estimator and the simple methods carrying forward the last covariates. The different methods are applied to an observational study designed to assess the effect of group A streptococcus on pharyngitis among school children in India. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26887664

  4. Combining EarthScope Long Period Magnetotelluri and Geomagnetic Observatory Data: Hypothetical Events at Continental Scale

    NASA Astrophysics Data System (ADS)

    Egbert, G. D.

    2015-12-01

    The EarthScope USArray project has been collecting long period (1 hz) MT data on a quasi-uniform 70 km grid since 2006, using a "rolling" array of approximately 20 long period MT sensors. Up to this point over 700 sites have been occupied (each for ~3-4 weeks) covering almost half the continental US. Seven "backbone" EarthScope MT sites were deployed (but did not fully operate) continuously from 2008-2011. At the same time, continuous high-quality 1 hz vector magnetic field data are available from eight geomagnetic observatories spread over the continental US/southern Canada since 2007. These data can be supplemented with long term (but again not always continuous) magnetometer deployments used for space physics research—e.g., up to 25 sites are available from the Themis project. I will discuss application of multivariate array processing methods to these datasets, with the goal of merge the large scale synoptic observatory, with the other sites, including the spatially dense, but short duration, partially overlapping EarthScope arrays. The merged array can be used to create true hypothetical events -- maps of the electromagnetic that would be observed for highly idealized sources—both plane wave and gradient. These maps can provide a unique perspective on the internal induced fields within the Earth, and suggest novel strategies for extracting reliable information about crust and mantle conductivity. The synthesis may also provide new insights into external source characteristics, and their interaction with the conducting Earth. Application of these results to development and validation of methods for modeling and predicting geomagnetically induced currents (GIC) will also be discussed.

  5. The variations of long time period slow slip events along the Ryukyu subduction zone

    NASA Astrophysics Data System (ADS)

    Tu, Y. T.; Heki, K.

    2014-12-01

    Slow slip events (SSEs) are a type of slow earthquakes that can be observed with Global Positioning System (GPS) networks in the world. Those events are detected on intensely coupled plate boundaries such as Cascadia subduction zone (Dragert et al., 2001), western North America, Mexico (Kostoglodov et al., 2003), Alaska (Ohta et al., 2007) and Tokai and Boso areas (Ozawa et al., 2002, 2003), central Japan and are considered to have relations to large subduction thrust earthquakes. However, in southwestern Ryukyu trench where most of researchers believe that it should be a decoupled plate boundary, SSEs recur regularly and are located at a patch that is as deep as 20 to 40 km (Heki and Kataoka, 2008). For comprehending the characteristics and time variations of SSEs in this area, the GEONET GPS data of 16 years are used in this study. During 1997 to 2014, more than thirty SSEs are identified near Hateruma Island, Ryukyu. The average recurrence interval is calculated to be 6.3 months and release seismic moment is Mw 6.6 on average. However, the values of recurrence interval are not invariable. From 1997 to 2002, interval period of SSEs is 7.5 months, but during 2002 to 2008, the interval period decreases suddenly to 5.5 months. After 2008, the value restores to 7.2 months again. Furthermore, the slip amount of SSEs in this area varies with time. From 1997 to 2002, the slip is 9.5 cm/year; and during 2002 to 2008, the value slightly increases to 10.5 cm/year. However, in 2008 to 2013, the slip drops to 6.6 cm/year, but accord to the trend of cumulative slip, the slip value would increase in 2014. Considering these data, we find the slip values increase conspicuously in 2002 and 2013. Coincidentally, one Mw 7.1 thrust earthquake occurred in 2002 and earthquake swarm activity started in the Okinawa trough approximately 50km north of the SSE patch. In 2013, another earthquake swarm activity occurred in nearly the same area as the 2002 activity. This suggests that the

  6. Observed high aerosol loading during dust events in Delhi

    NASA Astrophysics Data System (ADS)

    Singh, Khem; Aggarwal, Shankar G.; Jha, Arvind K.; Singh, Nahar; Soni, Daya; Gupta, Prabhat K.

    2012-07-01

    The present study reports aerosol mass loadings and their chemical property during integrated campaign for aerosol and radiation budget (ICARB) in the month of March to May 2006, at NPL, New Delhi. The Thar Desert in Rajasthan is located on the western end of India and south-west of Delhi is hot and arid region with intense aeolian activity and transport of aerosol by the prevailing southwest-west summer wind. Several dust episodes were observed in Delhi during summer 2006. The dust storm peaked on 29th April, 1 ^{st} and 8 ^{th} May 2006, with very high suspended particulate matter (SPM) concentrations 1986μg/m ^{3}, 1735μg/m ^{3} and 1511μg/m ^{3}, respectively. The average concentration of SPM in the month of March, April and May 2006 was 338 μg/m ^{3}, 698 μg/m ^{3} and 732 μg/m ^{3}, respectively. The SPM filter samples were analysed for water-soluble major cations (Na ^{+}, Ca ^{2+}, K ^{+}, and Mg ^{2+}) by atomic absorption spectrophotometry (AAS). Na ^{+} and Ca ^{2+} contribute about 54% and 20%, respectively of the total identified cation mass, indicating that they were most abundant cations. Strong correlations between Na ^{+}, Ca ^{2+}, K ^{+}, and Mg ^{2+} suggest their soil and dust origin. Such a high particle concentration observed during dust events may also be useful for study the effect of these aerosols on communication medium.

  7. Field observations of a debris flow event in the Dolomites

    NASA Astrophysics Data System (ADS)

    Berti, Matteo; Genevois, Rinaldo; Simoni, Alessandro; Tecca, Pia Rosella

    1999-09-01

    A debris flow event occurred in June 1997 in the Dolomites (Eastern Alps, Italy). The phenomenon was directly observed in the field and recorded by a video camera near its initiation area. The debris flow originated shortly after an intense rainstorm (25 mm in 30 min) whose runoff mobilised the loose coarse debris that filled the bottom of the channel in its upper part. The analysis of the steep headwater basin indicates a very short concentration time (9-14 min) that fits the quick hydrological response observed in the field. The debris flow mobilisation was not contemporaneous with the arrival of the peak water discharge in the initiation area probably due to the time required for the saturation of the highly conductive channel-bed material. Channel cross-section measurements taken along the flow channel indicate debris flow peak velocity and discharge ranging from 3.1 to 9.0 m/s and from 23 to 71 m 3/s, respectively. Samples collected immediately after deposition were used to determine the water content and bulk density of the material. Channel scouring, fines enrichment and transported volume increase testify erosion and entrainment of material along the flow channel. Field estimates of the rheological properties based on open channel flow of Bingham fluid indicate a yield strength of 5000±400 Pa and relatively low viscosity (60-326 Pa s), probably due to a high percentage of fines (approx. 30%).

  8. Examining Periodic Solar-Wind Density Structures Observed in the SECCHI Heliospheric Imagers

    NASA Technical Reports Server (NTRS)

    Viall, Nicholeen M.; Spence, Harlan E.; Vourlidas, Angelos; Howard, Russell

    2010-01-01

    We present an analysis of small-scale, periodic, solar-wind density enhancements (length scales as small as approximately equals 1000 Mm) observed in images from the Heliospheric Imager (HI) aboard STEREO-A. We discuss their possible relationship to periodic fluctuations of the proton density that have been identified at 1 AU using in-situ plasma measurements. Specifically, Viall, Kepko, and Spence examined 11 years of in-situ solar-wind density measurements at 1 AU and demonstrated that not only turbulent structures, but also nonturbulent, periodic density structures exist in the solar wind with scale sizes of hundreds to one thousand Mm. In a subsequent paper, Viall, Spence, and Kasper analyzed the alpha-to-proton solar-wind abundance ratio measured during one such event of periodic density structures, demonstrating that the plasma behavior was highly suggestive that either temporally or spatially varying coronal source plasma created those density structures. Large periodic density structures observed at 1 AU, which were generated in the corona, can be observable in coronal and heliospheric white-light images if they possess sufficiently high density contrast. Indeed, we identify such periodic density structures as they enter the HI field of view and follow them as they advect with the solar wind through the images. The smaller, periodic density structures that we identify in the images are comparable in size to the larger structures analyzed in-situ at 1 AU, yielding further evidence that periodic density enhancements are a consequence of coronal activity as the solar wind is formed.

  9. Distortion of the seismic radiation pattern in a long period band: Absence of clear node observations

    NASA Astrophysics Data System (ADS)

    Sakai, T.; Kumagai, H.

    2015-12-01

    Sakai et al. (2014, 10th ASC) estimated the source amplitudes in a long-period band of 50 - 100 s using broadband seismic records of earthquakes that occurred in the Philippine and Indonesia, and showed that the source amplitudes fell within a constant band against the moment magnitudes (Mw). Long-period waveforms are thought to be less influenced by structural heterogeneities, and the radiation pattern in a long-period band may not be distorted. However, the results of Sakai et al. (2014) suggest that the nodes are not clearly observed in the long-period band. In this study, we analyzed seismic data from the Japan broadband seismograph network (F-net), which is denser than the networks in the Philippine and Indonesia, and carried out numerical tests using synthetic waveforms to investigate the characteristics of long-period wavefields. We used earthquakes that occurred in Japan with Mw between 4 and 8 since 2003, and estimated their source amplitudes in a long-period band of 50 - 100 s using waveform data from F-net. In each event, we calculated the ratios of the minimum source amplitude to other source amplitudes. We found that the ratios for most of events had values ranging up to roughly 10 regardless of their moment magnitudes and the nodes were also not clearly observed in the F-net data. Using the discrete wavenumber method, we calculated synthetic seismograms assuming uniform station distributions with horizontal intervals of 50 and 100 km as well as the Philippine and F-net station distributions. We assumed an earthquake located in the center of the distributed stations, and systematically changed the dip, strike, and rake angels. We estimated the source amplitudes in the long-period band from the seismograms synthesized with these different fault angles. Our numerical tests indicated that the ratios of the source amplitudes become larger as the density of stations is higher and the ratios depend on the mechanisms. These estimated ratios were larger than

  10. Viking magnetic and electric field observations of periodic Pc 1 waves: Pearl pulsations

    SciTech Connect

    Erlandson, R.E.; Anderson, B.J.; Zanetti, L.J.

    1992-10-01

    Pearl pulsations, with an average repetition period of 60 s, were recorded using the magnetic and electric field experiments on the polar-orbiting Viking satellite. The wave event occurred on September 30, 1986, during Viking orbit 1212 at 1030 MLT, from L=3.6 to L=4.1, and at an altitude of 13,500 km. Electron density observations obtained from Viking show that the waves were generated at the plasmapause and at lower amplitudes in the plasmasphere. The wave Poynting flux, calculated using the magnetic and electric field, indicated that the waves generally were propagating downward toward the ionosphere, although upward Poynting fluxes were observed. Clear evidence of upward propagating waves, associated with downward propagating waves reflected at the ionosphere, was not observed. Linear convective growth rates suggest that the anisotropic ions which provide the free energy have a perpendicular temperature around 15 keV. The repetition period, calculated using the measured electron density and magnetic field strength at Viking, is consistent with the double-hop transit time for ion cyclotron waves which propagate along field lines from one hemisphere to the other. However, the absence of upward propagating waves packets implies that the upper limit of the wave ionospheric reflection coefficient is on the order of 10 to 20%. Alternative mechanism for producing the observed repetition are also investigated and include a periodic generation model of pearl pulsations at the ion bounce period. 42 refs., 5 figs., 4 tabs.

  11. Photometric Observations of the η Carinae 2009.0 Spectroscopic Event

    NASA Astrophysics Data System (ADS)

    Landes, H.; Fitzgerald, M.

    2010-09-01

    We have observed η Carinae over 34 nights between 2009 January 4 and 2009 March 27 covering the estimated timeframe for a predicted spectroscopic event related to a suspected binary system concealed within the homunculus nebula. A photometric minimum feature was confirmed to be periodic and comparison to a previous event indicated that the period to within our error was 2022.6+/-1.0d. Using the E-region standard star system, the apparent V magnitudes determined for the local comparison stars were HD 303308 8.14+/-0.02, HD 93205 7.77+/-0.03, and HD 93162 8.22+/-0.05. The latter star was found to be dimmer than previously reported.

  12. Nucleation events at a coastal city during the warm period: Kerbside versus urban background measurements

    NASA Astrophysics Data System (ADS)

    Siakavaras, D.; Samara, C.; Petrakakis, M.; Biskos, G.

    2016-09-01

    Number size distributions of atmospheric aerosol particles were simultaneously measured at a kerbside and an urban background site in the city of Thessaloniki, Greece, from June to October 2009. New particle formation events were observed ca. 27% of the days at the urban kerbside site and 29% of the days at the urban background site. In almost all the cases the events started between 10:00 and 12:00, and continued for several hours. The total number concentration (TNC) of the particles having diameters from 10 to ca. 500 nm during the events increased from 1.4 × 104 to 6.5 × 104 #/cm3 at the urban kerbside site, and from 0.2 × 104 to 2.4 × 104 #/cm3 at the urban background site. At the urban kerbside site, 9% of the days exhibited class I events (i.e., events followed by a clear growth of the newly formed particles), 10% class II (i.e., events during which the concentration of nucleation mode particles were high but their growth was not continuous), 67% were characterised as non-event days, and 14% of the days exhibited no clear particle formation pattern (undefined). At the urban background site, 15% of the days were classified as class I, 5% as class II, 75% of the days showed no nucleation, whereas only 5% of the days were undefined. While the fraction of event days (both class I and class II) at both sites was similar (ca. 20%), the higher fraction of class I events observed at Eptapyrgio can be attributed to the cleaner environment of the urban background site that allows better identification of the particle concentration increase. The nucleation bursts show a similar pattern at both sites, with the newly formed particles reaching a final size of ca. 80-100 nm. A distinct difference between the two stations was that the smallest particles observed during the new-particle formation events had a diameter of ca. 10 nm (i.e., the smallest particles we could observe) at the kerbside site and ca. 20 nm at the urban background site. This is an indication that

  13. Characteristics of extreme rainfall events in northwestern Peru during the 1982-1983 El Niño period

    NASA Astrophysics Data System (ADS)

    Goldberg, R. A.; Tisnado M., G.; Scofield, R. A.

    1987-12-01

    Using rainfall data from 66 stations within the Chira-Piura Project of northwestern Peru, we have prepared an atlas of histograms and contour maps describing the daily rainfall characteristics of the region during the El Niño period from November 1982 to June 1983. We have compared these data with those for the same 8-month intervals during the 2 years preceding and following the designated period. Uniquely during the El Niño period, these data often exhibit localized storms of high rainfall intensity (>100 mm/d) which may then disperse over wider areas of the region during the following 2-3 days. The region nearby and to the east of Chulucanas (5.10°S, 80.17°W) appears to be a focal point for the initiation of such events, particularly during the 1983 months of the period. Case studies for a few of the most severe events have been performed and compared with an analysis using GOES satellite cloud imagery in conjunction with upper air and surface weather maps, to arrive at a possible scenario for the cause and evolution of such events. Statistically, a high percentage of the storms are found to be multicellular with scale sizes approaching 250 km, with minimum cloud temperatures colder than -60°C, and of durations exceeding 6 hours. Such storm systems are consistent with the extreme and disastrous rainfall events observed from ground stations. The satellite analysis has also permitted us to identify significant storms beyond the range of the ground-based stations during this same time period, demonstrating the complementary value of satellite coverage for developing a more comprehensive view of the processes in effect.

  14. High upwind concentrations observed during an upslope tracer event

    SciTech Connect

    Ciolek, J.T. Jr.

    1993-10-01

    In February of 1991 the Rocky Flats Plant conducted twelve tracer experiments to validate an emergency response dispersion model known as the Terrain-Responsive Atmospheric Code (TRAC) (Hodgin 1985). Experimenters released 140 to 260 kilograms of inert tracer gas (sulfur hexafloride) from the plant over an 11 hour period. During each release, one hundred and sixty-five samples, most of which formed concentric rings of 8 and 16 km radius from the plant, recorded cumulative hourly concentrations of the tracer at one meter above ground level (AGL). Figure 1 contains a depiction of the sampler location, the terrain, and the meteorological stations available within the tracer study area. Brown (1991) describes the experimental setup in more detail. The subject of this paper is an event that occurred early in the fifth experiment, on February 9, 1991. In this experiment, tracer material released from 13:00 to 17:00 LST appeared both downwind and upwind of the source, with the highest concentrations upwind. During the fifth experiment, high pressure in Utah produced mostly sunny skis around Rocky Flats. For most of the day, one could find moderate (5 to 10 ms{sup {minus}1}) northerly (from the North) flow within the 700 to 500 mb level of the atmosphere (approximately 3000 to 5500 meters above Mean Sea Level (MSL)). Synoptic scale motions were isolated enough from the surface layer and heating was great enough to produce a 1 km deep upslope flow (flow from the East to the West) by late afternoon. The winds reversed and became downslope at approximately 17:30 LST.

  15. Summary of types of precipitation events observed by BARREL during storms.

    NASA Astrophysics Data System (ADS)

    Halford, A. J.; Millan, R. M.; Chakrabarti, S.; Woodger, L. A.; Kavanagh, A. J.

    2015-12-01

    In this poster we summarize the types of storm time precipitation observed by BARREL. One storm will be specifically highlighted which occurred on 26 January 2013 when a solar wind shock hit the Earth. After impact, electromagnetic ion cyclotron (EMIC) waves, observed both on the ground and with the Van Allen Probes, and relativistic electron precipitation (REP) were observed. A few hours later a substorm injection, observed by GOES and LANL, led to 100s keV electron precipitation. Throughout the substorm microbursts were clearly observed. Both during the REP as well as during the substorm precipitation, ULF time scale modulation of the X-rays was observed. This storm period also covered a time period where ~150 keV electron precipitation was observed to correlate well with drift echoes at 300 keV. This last event has not yet been fully explained. We will also present new results from storm periods during the second and third (Swedish) BARREL campaigns. We hope to be able to include results from conjunctions with EISCAT Tromso radar and HiT&MIS, a day time auroral imager, along with the current heliospheric fleet of satellites.

  16. Continental seismic events observed by the MPL vertical DIFAR array

    SciTech Connect

    Harris, D.B.; D`Spain, G.

    1993-11-01

    The vertical DIFAR array, an underwater acoustic sensor system, deployed by the Marine Physical Laboratory (MPL) was in place over the continental shelf off of Southern California and recorded the HUNTERS TROPHY nuclear test and nearly a score of after-shocks of the Landers/Big Bear earthquakes. Data from this array raise the possibility that detection thresholds for continental events may be significantly lower for arrays over the continental shelf than for arrays in the deep ocean basins. Offshore stations could be used to fill gaps in land-based seismic networks for monitoring the NPT and a CTBT, especially for monitoring non-cooperating nations with large coastlines. This preliminary report provides an analysis of the HUNTERS TROPHY observation as well as one of the Landers aftershocks. The analysis suggests detection thresholds for vertical hydrophone arrays below mb 3.0 at ranges between 3 and 4 degrees, and below mb 4.4 out to 6 degrees. This report also describes two signal processing techniques that enhance the detection potential of short vertical arrays. These methods are deterministic null steering to suppress horizontally propagating ambient ocean noise, and matched field processing for vertically-incident acoustic fields. The latter technique is ideally suited for acoustic fields derived from incident seismic waves, and may be viewed as a {open_quotes}synthetic aperture{close_quotes} approach to increase the effective aperture of the array.

  17. Constraints on Cumulus Parameterization from Simulations of Observed MJO Events

    NASA Technical Reports Server (NTRS)

    Del Genio, Anthony; Wu, Jingbo; Wolf, Audrey B.; Chen, Yonghua; Yao, Mao-Sung; Kim, Daehyun

    2015-01-01

    Two recent activities offer an opportunity to test general circulation model (GCM) convection and its interaction with large-scale dynamics for observed Madden-Julian oscillation (MJO) events. This study evaluates the sensitivity of the Goddard Institute for Space Studies (GISS) GCM to entrainment, rain evaporation, downdrafts, and cold pools. Single Column Model versions that restrict weakly entraining convection produce the most realistic dependence of convection depth on column water vapor (CWV) during the Atmospheric Radiation Measurement MJO Investigation Experiment at Gan Island. Differences among models are primarily at intermediate CWV where the transition from shallow to deeper convection occurs. GCM 20-day hindcasts during the Year of Tropical Convection that best capture the shallow–deep transition also produce strong MJOs, with significant predictability compared to Tropical Rainfall Measuring Mission data. The dry anomaly east of the disturbance on hindcast day 1 is a good predictor of MJO onset and evolution. Initial CWV there is near the shallow–deep transition point, implicating premature onset of deep convection as a predictor of a poor MJO simulation. Convection weakly moistens the dry region in good MJO simulations in the first week; weakening of large-scale subsidence over this time may also affect MJO onset. Longwave radiation anomalies are weakest in the worst model version, consistent with previous analyses of cloud/moisture greenhouse enhancement as the primary MJO energy source. The authors’ results suggest that both cloud-/moisture-radiative interactions and convection–moisture sensitivity are required to produce a successful MJO simulation.

  18. Observation of neutrino-induced neutral current charm events

    NASA Astrophysics Data System (ADS)

    Alton, Andrew Knight

    We report results from the analysis of wrong sign muon (WSM) events in deep inelastic nmN and nmN scattering with the NuTeV experiment at the Fermi National Accelerator Laboratory. These measurements are made possible by the high-purity NuTeV sign-selected beams. Using the anti-neutrino mode (WSM) sample we extract the normalizations for all known sources of beam impurities. The corrected charm production at the target measures the cross section, sp+p-->cc using linear atomic mass dependence. Using a boson-gluon fusion model and the neutrino mode WSM sample open neutral current charm production in neutrino scattering has been observed, and the charm mass is determined to be mc=1.40+0.83- 0.36+/-0.2 6 GeV/c2. The average energy of neutrinos which produce a pair of charm quarks is 154 GeV, and at this energy the cross section is sn+N-->cc =(2.14+1.76- 1.54)×10 -1fb . A search for Flavor-Changing Neutral-Current (FCNC) production of bottom and charm has demonstrated a new method of placing limits on FCNC. These limits are of comparable sensitivity to the current best limits, and effectively limit other decay modes.

  19. Measurements of temporal and spatial sequences of events in periodic precipitation processes

    NASA Astrophysics Data System (ADS)

    Kai, Shoichi; Müller, Stefan C.; Ross, John

    1982-02-01

    A series of new experiments on Liesegang ring (or band) formation is presented which is concerned with the temporal and spatial evolution of the process of structure formation. We have chosen NH4OH and MgSO4 to form rings of Mg(OH)2 precipitate in a gelatin gel, as well as KI and Pb(NO3)2 for periodic precipitation of PbI2 in an agar gel. A temporal sequence of events during the entire period from the start of a Liesegang experiment in a test tube to the completion of the final ring pattern has been determined at many locations in the tube by visual observations and by measurements of transmitted light, of scattered light, of deflection of the transmitted light beam, and of gravity effects. After diffusion of one electrolyte into the gel medium containing the second electrolyte results in an ion product larger than three times the solubility product, at any and all points in space, we observe the onset of homogeneous nucleation of colloidal particles by a steplike increase of the index of refraction. The colloid concentration and the particle number density at the nucleation site are estimated to be 10-2 mol/l and 1015 to 1016 cm-3, respectively. Nucleation is followed by the growth of colloidal particles which gives rise to distinct light scattering (turbidity). Both nucleation and colloid formation take place in space continuously; the fronts of these phenomena move through the system and obey a simple diffusion law. A substantial time interval after their passage, there arises a localized gradient of the index of refraction at the prospective ring positions which indicates onset of structure formation by means of a focusing mechanism. While the localized gradient becomes more pronounced and narrower in space, the turbidity in the regions on either side of the ring location decreases, which indicates a depletion in colloidal material in the neighboring zones. Eventually, a sharp band of visible precipitate appears, which is clearly separated from the preceding

  20. Forbush Decrease events in Lunar Radiation Environment observed by the LRO/CRaTER

    NASA Astrophysics Data System (ADS)

    Sohn, J.; Oh, S.; Yi, Y.; Kim, E.; Lee, J.; Spence, H. E.

    2012-12-01

    The Lunar Reconnaissance Orbiter (LRO) launched on June 16, 2009 has six experiments including of the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) onboard. The CRaTER instrument characterizes the radiation environment to be experienced by humans during future lunar missions. The CRaTER instrument measures the effects of ionizing energy loss in matter specifically in silicon solid-state detectors due to penetrating solar energetic protons (SEP) and galactic cosmic rays (GCR) after interactions with tissue-equivalent plastic (TEP), a synthetic analog of human tissue. The CRaTER instrument houses a compact and highly precise microdosimeter. It measures dose rates below one micro-Rad/sec in lunar radiation environment. Forbush decrease (FD) event is the sudden decrease of galactic cosmic ray (GCR) flux. The FD event is considered to be caused by exclusion of GCR due to intense interplanetary magnetic field (IMF) structures of interplanetary shock (IP) sheath region and/or the interplanetary coronal mass ejection (CME) following the IP shocks as a shock driver. We use the data of cosmic ray flux and dose rates observed by the CRaTER instrument. We also use the CME list of STEREO SECCHI inner, outer coronagraph and the IMF (Interplanetary CME) data of the ACE/MAG instrument. We examine the origins and the characteristics of the FD-like events in lunar radiation environment. We also compare these events with the FD events on the Earth. We find that whenever the FD events are recorded at ground Neutron Monitor stations, the FD-like events also occur on the lunar environments. The flux variation amplitude of FD-like events on the Moon is approximately two times larger than that of FD events on the Earth. We compare time profiles of GCR flux with of the dose rate of FD-like events in the lunar environment. We figure out that the distinct FD-like events correspond to dose rate events in the CRaTER on lunar environment during the event period.

  1. Periodic waves in the lower thermosphere observed by OI630 nm airglow images

    NASA Astrophysics Data System (ADS)

    Paulino, I.; Medeiros, A. F.; Vadas, S. L.; Wrasse, C. M.; Takahashi, H.; Buriti, R. A.; Leite, D.; Filgueira, S.; Bageston, J. V.; Sobral, J. H. A.; Gobbi, D.

    2016-02-01

    Periodic wave structures in the thermosphere have been observed at São João do Cariri (geographic coordinates: 36.5° W, 7.4° S; geomagnetic coordinates based on IGRF model to 2015: 35.8° E, 0.48° N) from September 2000 to November 2010 using OI630.0 nm airglow images. During this period, which corresponds to almost one solar cycle, characteristics of 98 waves were studied. Similarities between the characteristics of these events and observations at other places around the world were noted, primarily the spectral parameters. The observed periods were mostly found between 10 and 35 min; horizontal wavelengths ranged from 100 to 200 km, and phase speed from 30 to 180 m s-1. These parameters indicated that some of the waves, presented here, are slightly faster than those observed previously at low and middle latitudes (Indonesia, Carib and Japan), indicating that the characteristics of these waves may change at different places. Most of observed waves have appeared during magnetically quiet nights, and the occurrence of those waves followed the solar activity. Another important characteristic is the quasi-monochromatic periodicity that distinguish them from the single-front medium-scale traveling ionospheric disturbances (MSTIDs) that have been observed previously over the Brazilian region. Moreover, most of the observed waves did not present a phase front parallel to the northeast-southwest direction, which is predicted by the Perkins instability process. It strongly suggests that most of these waves must have had different generation mechanisms from the Perkins instability, which have been pointed out as being a very important mechanism for the generation of MSTIDs in the lower thermosphere.

  2. Inferring Rotation Periods of Young Stars from Synoptic Observations

    NASA Astrophysics Data System (ADS)

    Hartigan, Patrick; Johns-Krull, Christopher M.; Scowen, Paul

    2012-04-01

    Using known distributions for the periods, amplitudes and light-curve shapes of young stars, we examine how well one could measure periods of these objects in the upcoming era of large synoptic surveys. Surveys like the LSST should be able to recover accurate rotation periods for over 90% of targets of interest in regions near to massive-star formation. That information will usher in a new era in our understanding of how the angular momentum of a young star/disk system evolves with time.

  3. Examining Insurance Loss Return Periods with Extreme Event Intensity Thresholds across the US: 1980-2010

    NASA Astrophysics Data System (ADS)

    Smith, A. B.

    2010-12-01

    To improve the “effectiveness” of NOAA storm event information for risk managers, planners, policy makers and public safety, NOAA’s NCDC is integrating U.S. hazards/exposure data with respective insurance loss return periods. This is performed by calculating county-level extreme event intensity thresholds using these data types: hurricanes (NHC), winter storms (NESIS/RESIS), tornadoes (SPC; SWDI), hail (SPC; SWDI), high winds (SPC), drought (USDM/NIDIS), and U.S. insurance loss datasets (Munich Re, USDA-RMA, PCS, FEMA). This research also utilizes NWS warning data, socioeconomic data from the Bureau of Economic Analysis (BEA), and U.S. Census data (e.g., gridded population/density, mean housing value, per capita income, production wealth) to normalize for increases in population, inflation, and wealth. This work seeks to establish county-level U.S. extreme event economic risk climatologies for the period 1980-2010. This research will inform a new derived risk data product to improve information on extreme event loss frequencies and clustering across time and space horizons. Acronyms: FEMA: Federal Emergency Management Administration NESIS: Northeast Snowfall Impact Scale NHC: (NOAA) National Hurricane Center NIDIS: National Integrated Drought Information System PCS: Property Claim Services RESIS: Regional Snowfall Impact Scale SPC: (NOAA) Storm Prediction Center SWDI: (NOAA) Severe Weather Data Inventory USDA-RMA: U.S. Department of Agriculture - Risk Management Agency USDM: U.S. Drought Monitor

  4. Superconducting gravimeter observation for identifying slow slip events at Ryukyu Trench

    NASA Astrophysics Data System (ADS)

    Imanishi, Y.; Nawa, K.; Tamura, Y.; Ikeda, H.; Miyaji, T.; Tanaka, Y.

    2012-12-01

    Analysis of the data from the dense GPS network of Japan (GEONET) revealed quasi-periodic occurrences of long-term slow slip events at the Ryukyu Trench (Heki and Kataoka, 2008). The recurrence period of the events is about half a year, much shorter than typically found in other regions where slow slips are known to take place. Therefore, this region provides an interesting field for investigating the nature of slow slip events. In February 2012, we started gravity observation using a superconducting gravimeter (SG) at the VERA Ishigakijima Station, National Astronomical Observatory of Japan. The Ishigakijima island is located slightly east off the presumed fault area of the slow slip events. Our purpose is to detect gravity changes associated with the slow slip events by making full use of the high resolution of the SG. Of particular interest is the possible effect of water on the slow slip events, which might be identified from gravity observations. In addition to the SG, we installed an FG5 absolute gravimeter at the Iriomotejima island, located about 10 km west of the Ishigakijima island. The SG used in this study (serial number CT36) is the one which was in operation at the Inuyama Seismological Observatory, Nagoya University for about ten years. Before moving it to Ishigakijima, we made a thorough examination of the instruments. Because we found a serious problem in transferring liquid helium because of the ice inside, we warmed up the Dewar to initialize it. This not only solved the ice problem but also resulted in a significant decrease of the heater power for the gravity sensor. As of this writing, we have about six months worth of data from the SG. The condition of the gravimeter is good except for the first month when temperature control was unstable. Because of the ground vibrations caused by the movement of the 20-m VLBI antenna (about 30 m apart from the SG), the noise level is significantly enhanced compared with other domestic SG stations. Also we

  5. Locations and focal mechanisms of deep long period events beneath Aleutian Arc volcanoes using back projection methods

    NASA Astrophysics Data System (ADS)

    Lough, A. C.; Roman, D. C.; Haney, M. M.

    2015-12-01

    Deep long period (DLP) earthquakes are commonly observed in volcanic settings such as the Aleutian Arc in Alaska. DLPs are poorly understood but are thought to be associated with movements of fluids, such as magma or hydrothermal fluids, deep in the volcanic plumbing system. These events have been recognized for several decades but few studies have gone beyond their identification and location. All long period events are more difficult to identify and locate than volcano-tectonic (VT) earthquakes because traditional detection schemes focus on high frequency (short period) energy. In addition, DLPs present analytical challenges because they tend to be emergent and so it is difficult to accurately pick the onset of arriving body waves. We now expect to find DLPs at most volcanic centers, the challenge lies in identification and location. We aim to reduce the element of human error in location by applying back projection to better constrain the depth and horizontal position of these events. Power et al. (2004) provided the first compilation of DLP activity in the Aleutian Arc. This study focuses on the reanalysis of 162 cataloged DLPs beneath 11 volcanoes in the Aleutian arc (we expect to ultimately identify and reanalyze more DLPs). We are currently adapting the approach of Haney (2014) for volcanic tremor to use back projection over a 4D grid to determine position and origin time of DLPs. This method holds great potential in that it will allow automated, high-accuracy picking of arrival times and could reduce the number of arrival time picks necessary for traditional location schemes to well constrain event origins. Back projection can also calculate a relative focal mechanism (difficult with traditional methods due to the emergent nature of DLPs) allowing the first in depth analysis of source properties. Our event catalog (spanning over 25 years and volcanoes) is one of the longest and largest and enables us to investigate spatial and temporal variation in DLPs.

  6. Estimating interevent time distributions from finite observation periods in communication networks

    NASA Astrophysics Data System (ADS)

    Kivelä, Mikko; Porter, Mason A.

    2015-11-01

    A diverse variety of processes—including recurrent disease episodes, neuron firing, and communication patterns among humans—can be described using interevent time (IET) distributions. Many such processes are ongoing, although event sequences are only available during a finite observation window. Because the observation time window is more likely to begin or end during long IETs than during short ones, the analysis of such data is susceptible to a bias induced by the finite observation period. In this paper, we illustrate how this length bias is born and how it can be corrected without assuming any particular shape for the IET distribution. To do this, we model event sequences using stationary renewal processes, and we formulate simple heuristics for determining the severity of the bias. To illustrate our results, we focus on the example of empirical communication networks, which are temporal networks that are constructed from communication events. The IET distributions of such systems guide efforts to build models of human behavior, and the variance of IETs is very important for estimating the spreading rate of information in networks of temporal interactions. We analyze several well-known data sets from the literature, and we find that the resulting bias can lead to systematic underestimates of the variance in the IET distributions and that correcting for the bias can lead to qualitatively different results for the tails of the IET distributions.

  7. Determining the Return Period of Storm Surge Events in the Philippines

    NASA Astrophysics Data System (ADS)

    Santiago, Joy; Suarez, John Kenneth; Lapidez, John Phillip; Mendoza, Jerico; Caro, Carl Vincent; Tablazon, Judd; Ladiero, Christine; Mahar Francisco Lagmay, Alfredo

    2015-04-01

    The devastating damages generated by the Tropical Cyclone Haiyan storm surges in Eastern Samar, Philippines prompted the Department of Science and Technology-Project NOAH (Nationwide Operational Assessment of Hazards) to calculate the return period and storm surge exceedance probability of these events. The recurrence interval or the period of return of a storm surge event is the estimated likelihood that that event would occur again. Return periods are measured through historical data denoting the interval of recurrence in average over a period of time. The exceedance probability however, is a graphical representation that describes the probability that some various levels of loss will be exceeded over a future time period or will be surpassed over a given time. DOST-Project NOAH simulates storm surge height time series using JMA storm surge model which is a numerical model based on shallow water equations. To determine the period of recurrence of storm surges with this type of intensity, the agency intends to compute the estimation of storm surge heights generated by tropical cyclones for 2-year, 5-year, 10-year, 25-year, 50-year and 100-year return periods for the Philippine coast. The storm surge time series generated from JMA combined with WXTide simulation, a software containing archives/catalogues of world-wide astronomical tides, and 5-meter resolution DEM were used as input parameters for the inundation model, which shows probable extent of flooding at a specific storm surge return period. Flo-2D two-dimensional flood routing model, a GIS integrated software tool that facilitates the creation of the flood model grid system, was used for flood hazard model. It is a simple volume conservation model composed of processor program that facilitate graphical editing and mapping of flooding details which uses continuity equation and the dynamic wave momentum equations. The measurements of storm surge return period and probable extent of coastal flooding in the

  8. Cascadia Episodic Tremor and Slip events observed on GPS, seismic, and strain/tiltmeter arrays

    NASA Astrophysics Data System (ADS)

    Melbourne, T.

    2008-12-01

    The rapidly expanding GPS networks along the greater Cascadia forearc have enabled identification of nearly 40 isolated Episodic Tremor and Slip (ETS) events from 1992 through 2008. ETS events are observed throughout the forearc, from northern California to southwestern British Columbia, with station density generally increasing towards the north. Events located in well-instrumented regions can be tracked as they migrate laterally north-south along the plate boundary, but increasing station density has resolved many smaller transients that could not previously be confidently identified. At the specific latitude of the northern Washington State and southwestern British Columbia, the 14-month average recurrence interval still holds true, 6 events after first recognition. Elsewhere, this periodicity is not observed. Along central Oregon, an 18-month recurrence is evident, while in northern California (Yreka) the 11-month periodicity previously documented still holds true. Sporadic smaller events appear frequently throughout the subduction zone, including within the region known for the 14-month periodicity. For the most recent events that have the best GPS and seismic coverage, there is an increasingly strong correspondence between GPS-inversions for slip and tremor epicentral locations. Moreover, the 2007 and 2008 ETS events were also recorded by the PBO borehole strain and PANGA long-baseline tiltmeter arrays. These instruments show up to 200 nr of induced tilts and strain signals whose evolution are temporally coincident with tremor and whose total amplitudes are consistent with that predicted by GPS inversions for slip. GPS offsets for the largest 23 events inverted for slip show moment magnitudes ranging from 6.3 (smallest resolvable with GPS) to 6.8, and typically 2-3 cm of slip. The largest spatial extent of the events resolved to date is just under 500 km along strike, and maximum duration is seven weeks, which lies in marked contrast to other subduction zones

  9. Strains by Geodetic Observations Associated with Seismic Events in Latin America

    NASA Astrophysics Data System (ADS)

    Marotta, G. S.; Franca, G. S.; Galera Monico, J. F.; Fuck, R. A.

    2012-12-01

    In this study, we investigate surface strains related to seismic events and their relationship with pre- and post-seismic events in in Latin America, by analyzing the variation of estimated earth coordinates using GNSS positioning techniques supplied by a continuous monitoring geodetic network called SIRGAS-CON. That network consists of points in the South American lithospheric plates, Antarctica, Nazca, Cocos, North American and Caribbean. Based on data provided by the USGS for the period 2000-2011, and after the Global Congruency test, we selected four events associated with unstable geodetic network points. The determination of the resulting strain was estimated based on the finite element method using networks of points considered unstable connected to neighboring points with the method by Delaunay. It was possible to determine the strains along with the resulting guidelines for pre- and post-seismic, considering each triangular lattice formed for analysis as a homogeneous solid body. Using Global Congruency Test, from the 23 chosen events, 4 were associated to unstable points in the geodetic network. Those events were located in Northern Chile (Mw = 7.8 on 06/13/2005), Costa Rica (Mw = 6.1 on 01/08/2009), Off-shore Bio-Bio - Chile (Mw = 8.8 on 02/27/2010) and Baja - Mexico (Mw = 7.2 on 04/04/2010). The instability analysis detected displacements of the vector components of the points between 1cm and 3m approximately. The calculation of strains and verification of the results to the 4 events found allowed to analyze the interactions between lithospheric plates from the contraction and extension directions between points located in different plates. Despite the association between seismic events and the strain of geodetic network, events of Mw ≥ 5.8 were excluded because it does not show the surface strain, which is located at great depths. It was confirmed that events of greater magnitude provide increased surface strain rate when compared with other similar

  10. Dust storm events over Delhi: verification of dust AOD forecasts with satellite and surface observations

    NASA Astrophysics Data System (ADS)

    Singh, Aditi; Iyengar, Gopal R.; George, John P.

    2016-05-01

    Thar desert located in northwest part of India is considered as one of the major dust source. Dust storms originate in Thar desert during pre-monsoon season, affects large part of Indo-Gangetic plains. High dust loading causes the deterioration of the ambient air quality and degradation in visibility. Present study focuses on the identification of dust events and verification of the forecast of dust events over Delhi and western part of IG Plains, during the pre-monsoon season of 2015. Three dust events have been identified over Delhi during the study period. For all the selected days, Terra-MODIS AOD at 550 nm are found close to 1.0, while AURA-OMI AI shows high values. Dust AOD forecasts from NCMRWF Unified Model (NCUM) for the three selected dust events are verified against satellite (MODIS) and ground based observations (AERONET). Comparison of observed AODs at 550 nm from MODIS with NCUM predicted AODs reveals that NCUM is able to predict the spatial and temporal distribution of dust AOD, in these cases. Good correlation (~0.67) is obtained between the NCUM predicted dust AODs and location specific observations available from AERONET. Model under-predicted the AODs as compared to the AERONET observations. This may be mainly because the model account for only dust and no anthropogenic activities are considered. The results of the present study emphasize the requirement of more realistic representation of local dust emission in the model both of natural and anthropogenic origin, to improve the forecast of dust from NCUM during the dust events.

  11. Observations of Single Event Failure in Power MOSFETS

    NASA Technical Reports Server (NTRS)

    Nichols, D.; McCarty, K.; Coss, J.

    1994-01-01

    The first compendium of single event test data for power MOSFETs provides failure thresholds from burnout or gate rupture for over 100 devices of eight manufacturers. Ordering the data has also provided some useful insights.

  12. On quasi-periodic variations of low-energy cosmic rays observed near earth.

    PubMed

    Kudela, Karel; Langer, Ronald

    2015-06-01

    Cosmic ray (CR) may partially, especially at high altitudes, contribute to the dosimetric characteristics. Along with irregular CR variations as Forbush decreases and solar particle events are, the quasi-periodic variations may be of some relevance too. A very short review (with references to original papers) of the present knowledge of various types of such variations is presented, namely (i) diurnal wave, (ii) ~27 d variability due to the solar rotation, (iii) Rieger-type periodicity, and (iv) quasi-biennial oscillations as well as waves on longer time scales related to solar activity and to polarity of magnetic field of the Sun. Variability is illustrated in measurements of secondary CR on the ground including the high-altitude observations at Lomnický štít. PMID:25979741

  13. Recurrence times and periodicities in 4U 1608-52 as observed by Vela 5B

    NASA Technical Reports Server (NTRS)

    Lochner, James C.; Roussel-Dupre, Diane

    1994-01-01

    We report on the Vela 5B 10 year history of the soft X-ray transient 4U 1608-52, and on the characteristics of its soft X-ray outbursts. The Vela 5B satellite observed the four known outbursts in 1975, 1977, and 1979, and four new outbursts in 1970 and 1971, altering the recurrence pattern of outbursts from this source. One of the 1970 outbursts is symmetric in its intensity profile, while the two outbursts in 1971 have short exponential profiles separated by 80 days. Despite suggestive recurrence periods of approximately 85 and approximately 150 days evident in the time intervals between the outbursts, there is no single statistically significant recurrence time on which the outbursts recur consistently. In the 1970 symmetric event, there is evidence for a period of either 4.10 or 5.19 days. Drawing upon the analogy with SU Ursa Majoris dwarf novae, we suggest that the short period is orbital and any longer period would be associated with a precession period of the accretion disk.

  14. Concentric waves and short-period oscillations observed in the ionosphere after the 2013 Moore EF5 tornado

    NASA Astrophysics Data System (ADS)

    Nishioka, Michi; Tsugawa, Takuya; Kubota, Minoru; Ishii, Mamoru

    2013-11-01

    We detected clear concentric waves and short-period oscillations in the ionosphere after an Enhanced Fujita scale (EF)5 tornado hit Moore, Oklahoma, U.S., on 20 May 2013 using dense wide-coverage ionospheric total electron content (TEC) observations in North America. These concentric waves were nondispersive, with a horizontal wavelength of ~120 km and a period of ~13 min. They were observed for more than 7 h throughout North America. TEC oscillations with a period of ~4 min were also observed to the south of Moore for more than 8 h. A comparison between the TEC observations and infrared cloud image from the GOES satellite indicates that the concentric waves and short-period oscillations are caused by supercell-induced atmospheric gravity waves and acoustic resonances, respectively. This observational result provides the first clear evidence of a severe meteorological event causing atmospheric waves propagating upward in the upper atmosphere and reaching the ionosphere.

  15. Total ozone and Umkehr observations at Hoher Sonnblick 1994-2011: Climatology and extreme events

    NASA Astrophysics Data System (ADS)

    Fitzka, M.; Hadzimustafic, J.; Simic, S.

    2014-01-01

    Umkehr and total ozone measurements have been carried out at Hoher Sonnblick (47.05°N, 12.95°E; 3106 m above sea level) since 1994 with the Brewer MkIV #093 spectrophotometer. These measurements are used to investigate trends in total and vertically resolved ozone in the period 1994-2011 and for establishing an Umkehr climatology. A method to estimate daily thresholds for extreme events in total ozone (TO3) based on skewed log-Weibull distributions is presented and applied to the record. An analysis of the such defined extreme events reveals a significant decline in the number of low events, whereas the high events increased by about the same amount. However, no significant trend is observed in the magnitude of extreme events. Solar activity and equivalent effective stratospheric chlorine show weak to no correlation with vertically resolved ozone, presumably due to the record's limited extent, while tropopause pressure and quasi-biennial oscillation show a significant influence. Trend analysis of total and vertically resolved ozone indicates a significant increase in TO3 of 2.0% per decade since 1994, whereas no recovery is observed in the upper stratosphere. While ozone concentrations continue to decrease or stagnate in the upper stratosphere, the loss is overcompensated by large gains in the lowest layers during winter, leading to a significant overall increase in TO3. During events with extremely low TO3, the largest deficiencies are found in the bottommost layers with a marked seasonal component. The topmost layers mainly contribute to TO3 reductions during late winter and fall.

  16. Conjugate observations of a remarkable quasiperiodic event by the low-altitude DEMETER spacecraft and ground-based instruments

    NASA Astrophysics Data System (ADS)

    Bezdekova, Barbora; Nemec, Frantisek; Manninen, Jyrki; Parrot, Michel; Santolik, Ondrej; Hayosh, Mykhaylo

    2016-04-01

    Quasiperiodic (QP) events are electromagnetic waves observed in the inner magnetosphere at frequencies between about 0.5 and 4 kHz that exhibit a nearly periodic modulation of the wave intensity. The modulation periods may range from tens of seconds up to minutes. We present a detailed multipoint analysis of a remarkable QP event observed consecutively for several hours on 26 February 2008. The event was detected by ground-based instruments of Sodankyla Geophysical Observatory (Finland) and by the low-altitude DEMETER spacecraft, both in the same and conjugate hemispheres. The time intervals when the event was observed on board the satellite/on the ground provide us with an estimate of the event dimensions. When the event is detected simultaneously by the satellite and on the ground, its observed frequency-time structure is generally the same. However, the ratio of detected intensities varies significantly as a function of the spacecraft latitude. Moreover, there is a delay as large as about 10 s between the times when individual QP elements are detected by the spacecraft/on the ground. This appears to be related to the azimuthal separation of the instruments, and it is highly relevant to the identification of a possible source mechanism. Finally, we find that the intensity of the QP event is correlated with the amplitude of Alfvenic ULF pulsations measured on the ground.

  17. Multi-Spacecraft Observations of Interplanetary Shock Accelerated Particle Events

    NASA Technical Reports Server (NTRS)

    Ho, G. C.; Lario, D.; Decker, R. B.; Desai, M. I.; Hu, Q.; Kasper, J.

    2006-01-01

    We use simultaneous measurements from the Wind and ACE spacecraft to determine the spatial properties of both interplanetary (IP) shocks and the shock-associated energetic particle events. We combine plasma, magnetic field and energetic particle data from ACE and Wind for 124 energetic storm particle (ESP) events from 1998 to 2003 and examine the spatial and temporal variations of these events in the Earth's vicinity. We find that even though the two spacecraft were occasionally separated by more than 400 RE, the plasma, field, and energetic particle time-intensity profiles during the events were very similar. In addition, we find that the ion composition and energy spectra in individual IP shock events are identical at the two spacecraft locations. We also use the fitted shock velocity along the normal from ACE and estimate the shock transit time to Wind location. In general, there is poor agreement between the estimated transit time and the actual measured transit time. Hence, our assumptions that a) the IP shock at 1 AU propagates radially, and/or b) the IP shock is spherically symmetric at 1 AU are not valid. In this paper, we will also study, for the first time, the anisotropy measurements of low-energy IP shock-associated ions at both ACE and Wind. We will then compare these new anisotropy analyses with locally measured shock parameters and identify possible signatures of different shock acceleration processes as predicted by the first-order Fermi and shock-drift models.

  18. Large geomagnetic storms of extreme solar event periods in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Wang, R. G.; Wang, J. X.

    At the duration of extreme solar events solar eruption associated with big flares or and energetic coronal mass ejections CMEs can not only make high energy particles acceleration but also give rise to large geomagnetic storms which have significant effects on the Earth s environment and human life Around 14 solar cosmic ray ground level enhancement GLE events in solar cycle 23 we examine the cosmic ray variations solar wind speeds ion densities interplanetary magnetic fields and geomagnetic disturbance storm time indices Dst We find that all but one of GLEs are always followed by a geomagnetic storm with Dst leq -50 nT within 1-5 days later Most 10 14 geomagnetic storms have Dst index leq -100 nT suggesting that GLE event prediction of geomagnetic storms is 93 for moderate storms and 71 for large storms More than half 57 Dst depressions are simultaneously accompanied by cosmic ray decreases and other Dst variabilities are without clear cosmic ray deceases We also investigated the interplanetary plasma features during GLE events Most geomagnetic storm correspond significant periods of southward B z and in close to 80 of the cases that the B z was first northward then turning southward after storm sudden commencement SSC Plasma flow speed ion number density and interplanetary plasma temperature near 1 AU also have a peak at interplanetary shock arrival Solar cause and energetic particle signatures of large geomagnetic storms are discussed

  19. Survey of DMSP Charging Events During the Period Preceding Cycle 23 Solar Maximum

    NASA Technical Reports Server (NTRS)

    Parker, Linda Neergaard; Minow, Joseph I.

    2013-01-01

    It has been well established that POLAR orbiting satellites can see mild to severe charging levels during solar minimum conditions (Frooninckx and Sojka, 1992, Anderson and Koons, 1996, Anderson, 2012). However, spacecraft operations during solar maximum cannot be considered safe from auroral charging. Recently, we have seen examples of high level charging during the recent approach to solar maximum. We present here a survey of charging events seen by the Defense Meteorological Satellite Program (DMSP) satellites (F16, F17) during the solstices of 2011 and 2012. In this survey, we summarize the condition necessary for charging to occur in this environment, we describe how the lower than normal maximum conditions are conducive to the environment conditions necessary for charging in the POLAR orbit, and we show examples of the more extreme charging events, sometimes exceeding 1 kV, during this time period. We also show examples of other interesting phenomenological events seen in the DMSP data, but which are not considered surface charging events, and discuss the differences.

  20. Specific features of the generation of long-periodic geomagnetic pulsations in the event on June 25, 2008

    NASA Astrophysics Data System (ADS)

    Moiseev, A. V.; Baishev, D. G.; Barkova, E. S.; Du, A.; Yumoto, K.

    2015-03-01

    The event of the generation of long-periodic geomagnetic Pc5 pulsations occurring on June 25, 2008 under undisturbed geomagnetic conditions is considered using data from ground-based and satellite observations. Two maxima in the frequency bands 1.9-2.2 and 2.9-3.3 mHz are revealed in the spectra of oscillations in the interplanetary medium, magnetosphere, and on the Earth. Pulsations with frequency 1.9-2.2 mHz were detected in all time sectors from low to high latitudes. The maximum amplitude of the oscillations was recorded in the longitude sector coinciding with position of the ion foreshock region. It is assumed that the event under consideration was caused both by variations of the solar wind dynamic pressure (amplified by the foreshock region) and by the direct penetration of ultra-low-frequency waves from solar wind to the magnetosphere.

  1. Characterization And State-Of-The-Art Modeling Of Extreme Precipitation Events Over Africa During The Historical Period

    NASA Astrophysics Data System (ADS)

    Gibba, P.; Sylla, M. B.

    2015-12-01

    The ability of the state-of-the-art climate models to reproduce the mean spatial characteristics of extreme precipitation indices over Africa is evaluated. The ensembles of eight precipitation-based indices as defined by ETCCDI were extracted from seventeen CMIP5 GCMs and twelve CORDEX RCMs simulations based on absolute and percentile (95th) thresholds and computed from the 1975 to 2004 historical period. Daily precipitation indices calculated from GPCP and TRMM satellite-derived observation datasets during the period 1997 to 2012 and 1998 to 2011 respectively were also employed in this study for model validation. Results of spatial representation of the frequency of extreme precipitation events (R1mm, CDD, CWD and R95p) highlight a generally good consistency between the two observations. Equally, in the regional analysis some similarities exist in their median and interquartile (25th and 75th percentile) spread especially for CDD, CWD and R95p for most regions. In the associated intensities (SDII, RX5day, R95 and R95ptot), results indicate large spatial differences between the two observational datasets, with finer resolution TRMM generating higher rainfall intensities than the coarser resolution GPCP. TRMM has also demonstrated higher median and interquartile range as compared to GPCP. The CORDEX RCMs and CMIP5 GCMs simulations have estimated more number of extreme precipitation events, while underestimated the intensities. The differences between the models and observations can be as large as the typical model interquartile spread of the ensembles for some indices (R1mm, CWD, SDII and R95) in some regions. Meanwhile, CORDEX estimations are generally closer to the observations than CMIP5 in reproducing the frequency of extreme rainfall indices. For the estimation of rainfall intensities, CORDEX simulations are in most cases more consistence with TRMM observations whilst the CMIP5 GCMs simulations are closer to GPCP observations.

  2. Tests of ionospheric control of young injection events identified from magnetometer observations at Saturn

    NASA Astrophysics Data System (ADS)

    Kivelson, M.; Jia, X.

    2015-12-01

    Kennelly et al. (2013) reported that young plasma injection events observed in Saturn's nightside magnetosphere and identified from plasma wave signatures are modulated at the period associated with the winter hemisphere. In a system unstable to interchange, radial motion of flux tubes is constrained by the "line-tying" effect of high ionospheric conductance (Southwood and Kivelson, 1989). Slippage of a flux tube would then occur initially in the hemisphere in which the ionospheric conductance is lowest. Saturn's ionospheric conductances vary not only with season, but also with rotation phase because of the presence of a pattern of rotating field-aligned currents that drive "planetary period oscillations" (Jia and Kivelson, 2012). The conductance should minimize near the center of the downward current region and, at this rotation phase in the winter hemisphere, the growth rate of the instability would be largest, accounting for control by the northern period. With motion starting in the winter hemisphere, the flux tube would develop a tilt of predictable sense and the initial inward motion of the interchanging flux tube would occur at a specific rotation phase of the winter ionosphere. For a subset of the Kennelly events, we found that the tilt and phase are consistent with expectations based on the control of displacement by ionospheric conductance. Many additional young interchange events have been identified by K. K. Khurana [personal communication, 2015] whom we thank for making the list available. We examine this more extensive set of events and use them to investigate the proposed mechanism more fully. __________ Jia, X., and M. G. Kivelson (2012), J. Geophys. Res., 117, A11219. Kennelly, T. J., J. S. Leisner, G. B. Hospodarsky, and D. A. Gurnett (2013), J. Geophys. Res. Space Physics, 118, 832-838. Kivelson, M., and X. Jia (2014), , AGU Fall meeting, 2014, SM51E-4295. Southwood, D. J., and M. G. Kivelson (1989), J. Geophys. Res., 94, 299-308.

  3. Reconnection events in Saturn's magnetotail: Dependence of plasmoid occurrence on planetary period oscillation phase

    NASA Astrophysics Data System (ADS)

    Jackman, C. M.; Provan, G.; Cowley, S. W. H.

    2016-04-01

    During its exploration of Saturn's magnetotail the Cassini magnetometer has detected many in situ examples of magnetic reconnection, in the form of plasmoids, traveling compression regions (TCRs), and dipolarizations. Meanwhile, many magnetospheric phenomena have been shown to be organized with particular regularity by planetary period oscillation systems driven separately from the Northern and Southern Hemispheres of the planet. Here we examine the relationship between the occurrence of plasmoids and TCRs and the magnetic phases of the northern and southern systems. We find a striking degree of organization of the events by both northern and southern phases, with events linked preferentially to intervals in which the magnetospheric plasma and field lines are displaced outward from the planet and the current sheet thinned, both effects being likely to favor the occurrence of reconnection and plasmoid-related mass loss. Little evidence is found for significant visibility effects associated with north-south motions of the plasma sheet.

  4. Possible transient creep events in a brittle-ductile continental crust: observations, experiments and potential models.

    NASA Astrophysics Data System (ADS)

    Lavier, Luc

    2016-04-01

    In a given tectonic province and over thousands to millions of years, slip on faults is believed to be constant and approximately equal to the local tectonic rate in agreement with rigid plate tectonic theory. In this model the ductile lower crust flows in response to this steady plate motion. Moreover brittle and ductile behaviors interact only at a sharp boundary defined as the brittle ductile transition (BDT). However in the continental lithosphere brittle and ductile behavior may coexist over a large range of pressure and temperature conditions for different mineral compositions. This generates heterogeneities in the brittle and ductile crust that are often ignored in models of shear zones. We hypothesize that the interaction between brittle (elastic) and ductile (viscous) behavior may cause deviations from steady-state slip and generates transient creep events on shear zones that release many meters of creep over years to thousands of years marked by a single period of tectonic activity followed by quiescence. We present a set of numerical and analytical models, analogue experiments as well as some observations in nature that may support this hypothesis. In this presentation we extend an analytic formulation to model creep events within shear zones at the transition between brittle and ductile behavior in the crust. We assume that creep events are triggered by a set of interconnected fractures modeled as propagating dislocations. The amount of connectivity controls the nature and the intensity of the transient creep events. The shear zone behaves as a forced damped oscillator that can release strain accumulated during jammed/locked periods. The creep can be over-, critically-, or under-damped. The time scale of the events may vary between seconds to thousands of years depending on the viscous, elastic and plastic (fractures) properties of the shear zone.

  5. Long-period seismic events with strikingly regular temporal patterns on Katla volcano's south flank (Iceland)

    NASA Astrophysics Data System (ADS)

    Sgattoni, Giulia; Jeddi, Zeinab; Gudmundsson, Ólafur; Einarsson, Páll; Tryggvason, Ari; Lund, Björn; Lucchi, Federico

    2016-09-01

    Katla is a threatening volcano in Iceland, partly covered by the Mýrdalsjökull ice cap. The volcano has a large caldera with several active geothermal areas. A peculiar cluster of long-period seismic events started on Katla's south flank in July 2011, during an unrest episode in the caldera that culminated in a glacier outburst. The seismic events were tightly clustered at shallow depth in the Gvendarfell area, 4 km south of the caldera, under a small glacier stream at the southern margin of Mýrdalsjökull. No seismic events were known to have occurred in this area before. The most striking feature of this seismic cluster is its temporal pattern, characterized by regular intervals between repeating seismic events, modulated by a seasonal variation. Remarkable is also the stability of both the time and waveform features over a long time period, around 3.5 years. We have not found any comparable examples in the literature. Both volcanic and glacial processes can produce similar waveforms and therefore have to be considered as potential seismic sources. Discerning between these two causes is critical for monitoring glacier-clad volcanoes and has been controversial at Katla. For this new seismic cluster on the south flank, we regard volcano-related processes as more likely than glacial ones for the following reasons: 1) the seismic activity started during an unrest episode involving sudden melting of the glacier and a jökulhlaup; 2) the glacier stream is small and stagnant; 3) the seismicity remains regular and stable for years; 4) there is no apparent correlation with short-term weather changes, such as rainstorms. We suggest that a small, shallow hydrothermal system was activated on Katla's south flank in 2011, either by a minor magmatic injection or by changes of permeability in a local crack system.

  6. Waves associated to COMPLEX EVENTS observed by STEREO

    NASA Astrophysics Data System (ADS)

    Siu Tapia, A. L.; Blanco-Cano, X.; Kajdic, P.; Aguilar-Rodriguez, E.; Russell, C. T.; Jian, L. K.; Luhmann, J. G.

    2012-12-01

    Complex Events are formed by two or more large-scale solar wind structures which interact in space. Typical cases are interactions of: (i) a Magnetic Cloud/Interplanetary Coronal Mass Ejection (MC/ICME) with another MC/ICME transient; and (ii) an ICME followed by a Stream Interaction Region (SIR). Complex Events are of importance for space weather studies and studying them can enhance our understanding of collisionless plasma physics. Some of these structures can produce or enhance southward magnetic fields, a key factor in geomagnetic storm generation. Using data from the STEREO mission during the years 2006-2011, we found 17 Complex Events preceded by a shock wave. We use magnetic field and plasma data to study the micro-scale structure of the shocks, and the waves associated to these shocks and within Complex Events structures. To determine wave characteristics we perform Power Spectra and Minimum Variance Analysis. We also use PLASTIC WAP protons data to study foreshock extensions and the relationship between Complex Regions and particle acceleration to suprathermal energies.

  7. An Observing Campaign of the Mutual Events Within (617) Patroclus-Menoetius Binary Trojan System

    NASA Astrophysics Data System (ADS)

    Berthier, Jerome; Marchis, F.; Descamps, P.; Assafin, M.; Bouley, S.; Colas, F.; Dubos, G.; Emery, J. P.; De Cat, P.; Farrell, J. A.; Leroy, A.; Pauwels, T.; Pollock, J. T.; Reddy, V.; Sada, P. V.; Vingerhoets, P.; Vachier, F.; Vieira-Martins, R.; Wong, M. H.; Reichart, D. E.; Ivarsen, K. M.; Crain, J. A.; LaCluyze, A. P.; Nysewander, M. C.

    2007-10-01

    In 2006-2007, the binary Trojan system (617) Patroclus-Menotius reached one of its annual equinoxes. As a consequence, the system underwent a 6 months season of mutual eclipses and occultations. We organized a campaign of observations of these mutual events mostly centered along the first semester of 2007. We took advantage of an orbit solution of the similary-sized binary system published by Marchis et al. (Nature, 2006) to predict the timing of mutual eclipses and occultations observable from January to July 2007. During the campaign, the magnitude of Patroclus system varied from 15.8 to 16.6 and its solar phase from 9°.5 to 2°.7 at opposition (end of March). The amplitude of the events ranged between 0.2 and 0.3 magnitude. A large number of stations around the world were involved in the campaign and 20 lightcurves with mutual events signature were collected (http://www.imcce.fr/page.php?nav=en/observateur/campagnes_obs/patroclus/). With such favorable circumstances, photometric observations of the events will provide tight constraints regarding physical properties of the system such as sizes, shapes, sidereal spin period and surface composition. Combining AO observations collected at Keck and Gemini with this lightcurve data, we have refined the orbital parameters of the binary system to an unprecedented accuracy. We will present these findings, the determination of the sizes and shapes, and other results from the data analysis. This material is partly based upon work supported by the National Aeronautics and Space Administration issue through the Science Mission Directorate Research and Analysis Programs number NNG05GF09G.

  8. Feature selection of seismic waveforms for long period event detection at Cotopaxi Volcano

    NASA Astrophysics Data System (ADS)

    Lara-Cueva, R. A.; Benítez, D. S.; Carrera, E. V.; Ruiz, M.; Rojo-Álvarez, J. L.

    2016-04-01

    Volcano Early Warning Systems (VEWS) have become a research topic in order to preserve human lives and material losses. In this setting, event detection criteria based on classification using machine learning techniques have proven useful, and a number of systems have been proposed in the literature. However, to the best of our knowledge, no comprehensive and principled study has been conducted to compare the influence of the many different sets of possible features that have been used as input spaces in previous works. We present an automatic recognition system of volcano seismicity, by considering feature extraction, event classification, and subsequent event detection, in order to reduce the processing time as a first step towards a high reliability automatic detection system in real-time. We compiled and extracted a comprehensive set of temporal, moving average, spectral, and scale-domain features, for separating long period seismic events from background noise. We benchmarked two usual kinds of feature selection techniques, namely, filter (mutual information and statistical dependence) and embedded (cross-validation and pruning), each of them by using suitable and appropriate classification algorithms such as k Nearest Neighbors (k-NN) and Decision Trees (DT). We applied this approach to the seismicity presented at Cotopaxi Volcano in Ecuador during 2009 and 2010. The best results were obtained by using a 15 s segmentation window, feature matrix in the frequency domain, and DT classifier, yielding 99% of detection accuracy and sensitivity. Selected features and their interpretation were consistent among different input spaces, in simple terms of amplitude and spectral content. Our study provides the framework for an event detection system with high accuracy and reduced computational requirements.

  9. Large-Scale periodic solar velocities: An observational study

    NASA Technical Reports Server (NTRS)

    Dittmer, P. H.

    1977-01-01

    Observations of large-scale solar velocities were made using the mean field telescope and Babcock magnetograph of the Stanford Solar Observatory. Observations were made in the magnetically insensitive ion line at 5124 A, with light from the center (limb) of the disk right (left) circularly polarized, so that the magnetograph measures the difference in wavelength between center and limb. Computer calculations are made of the wavelength difference produced by global pulsations for spherical harmonics up to second order and of the signal produced by displacing the solar image relative to polarizing optics or diffraction grating.

  10. Some observations regarding the thermal flux from Earth's erupting volcanoes for the period 2000 to 2014

    NASA Astrophysics Data System (ADS)

    Wright, R.; Blackett, M.; Hill-Butler, C.

    2014-12-01

    This presentation will describe 15 years of MODIS observations of the thermal flux from Earth's sub-aerially erupting volcanoes. The MODVOLC algorithm has been providing data regarding volcanic eruptions on Earth to the volcanological community since the launch of Terra MODIS, via the internet, in near-real-time (http:modis.higp.hawaii.edu). During this time, eruptions at 102 volcanoes have been observed, including activity associated with mafic lava flows, lava lakes, vent-based explosive activity and felsic lava domes. This presentation will present an overview of how MODIS has documented every eruption to occur on Earth since 2000, and will describe some of the more interesting result that have been obtained from the analysis of this archive. The total amount of energy radiated into the atmosphere can be divided into two parts: a baseline level of emission which has increased gradually over this 15 period, superimposed on which are large "spikes" attributable to large, lava-flow-forming eruptions. The most intense eruption during this period of time was the 2004 eruption of Nyamuragira, in the Democratic Republic of Congo, whilst the largest magnitude event was the 2012-2013 eruption of Tolbachik, Russia. Spatio-temporal patterns in thermal output will be addressed. Time-series analysis of heat flux from these 102 volcanoes has revealed while some volcanoes exhibit statistically significant periodicity in the magnitude of their heat output, many do not.

  11. Observation and Analysis of Jovian and Saturnian Satellite Mutual Events

    NASA Technical Reports Server (NTRS)

    Tholen, David J.

    2001-01-01

    The main goal of this research was to acquire high time resolution photometry of satellite-satellite mutual events during the equatorial plane crossing for Saturn in 1995 and Jupiter in 1997. The data would be used to improve the orbits of the Saturnian satellites to support Cassini mission requirements, and also to monitor the secular acceleration of Io's orbit to compare with heat flow measurements.

  12. Estimating return periods for daily precipitation extreme events over the Brazilian Amazon

    NASA Astrophysics Data System (ADS)

    Santos, Eliane Barbosa; Lucio, Paulo Sérgio; Santos e Silva, Cláudio Moisés

    2015-08-01

    This paper aims to model the occurrence of daily precipitation extreme events and to estimate the return period of these events through the extreme value theory (generalized extreme value distribution (GEV) and the generalized Pareto distribution (GPD)). The GEV and GPD were applied in precipitation series of homogeneous regions of the Brazilian Amazon. The GEV and GPD goodness of fit were evaluated by quantile-quantile (Q-Q) plot and by the application of the Kolmogorov-Smirnov (KS) test, which compares the cumulated empirical distributions with the theoretical ones. The Q-Q plot suggests that the probability distributions of the studied series are appropriated, and these results were confirmed by the KS test, which demonstrates that the tested distributions have a good fit in all sub-regions of Amazon, thus adequate to study the daily precipitation extreme event. For all return levels studied, more intense precipitation extremes is expected to occur within the South sub-regions and the coastal area of the Brazilian Amazon. The results possibly will have some practical application in local extreme weather forecast.

  13. Early Oligocene geomagnetic field behavior from ODP Site 1128: Complex records of short-period polarity events

    NASA Astrophysics Data System (ADS)

    Molina-Garza, R. S.; Fuller, M. D.

    2001-12-01

    intermediate- (10-40 mT) and a high-coercivity (40-80 mT) component. Only the intermediate coercivity magnetization records normal polarities, although transitional directions are observed in both components. Hysteresis data suggest the presence of PSD particles, and show no discernable difference between sediments recording short-period polarity events and those with uniform near univectorial behavior and single polarity, suggesting uniformity of remanence carriers. The two components of the NRM can be attributed to the presence of two carriers with different lock-in time mechanisms.

  14. Results of Lunar Impact Observations During Geminid Meteor Shower Events

    NASA Technical Reports Server (NTRS)

    Suggs, R. J.; Suggs, R. M.

    2015-01-01

    Geminids' relatively large intensity and unique origin, it is important to monitor and gain information about the Geminids so as to improve their forecasts and understand their contribution to the meteoroid environment in Earth's orbit and at the Moon. It is the purpose of this Technical Memorandum (TM) to document two lunar observing periods coinciding with the Geminid meteor showers that occurred in 2006 and 2010.

  15. Adverse events from spinal manipulation in the pregnant and postpartum periods: a critical review of the literature

    PubMed Central

    2012-01-01

    Background The safety of spinal manipulation during pregnancy and the postpartum periods has been a matter of debate among manual therapists. Spinal manipulative therapy during these periods is a commonly performed intervention as musculoskeletal pain is common in these patients. To date there has not been an evaluation of the literature on this topic exclusively. Methods A literature search was conducted on PubMed, CINAHL and the Index to Chiropractic Literature along with reference searching for articles published in English and French in the peer-reviewed literature that documented adverse effects of spinal manipulation during either pregnancy or postpartum. Case reports, case series, and any other clinical study designs were deemed acceptable for inclusion, as were systematic reviews. The appropriate Scottish Intercollegiate Guidelines Network (SIGN) tools were used to rate included articles for quality when applicable. Results Five articles identifying adverse events in seven subjects following spinal manipulation were included in this review, along with two systematic reviews. The articles were published between 1978 and 2009. Two articles describing adverse effects from spinal manipulation on two postpartum patients were included, while the remaining three articles on five patients with adverse effects following spinal manipulation were on pregnant patients. Injury severity ranged from minor injury such as increasing pain after treatment that resolved within a few days to more severe injuries including fracture, stroke, and epidural hematoma. SIGN scores of the prospective observational cohort study and systematic reviews indicated acceptable quality. Conclusions There are only a few reported cases of adverse events following spinal manipulation during pregnancy and the postpartum period identified in the literature. While improved reporting of such events is required in the future, it may be that such injuries are relatively rare. PMID:22455720

  16. HF radar observations of ionospheric backscatter during geomagnetically quiet periods

    NASA Astrophysics Data System (ADS)

    Kane, T. A.; Makarevich, R. A.; Devlin, J. C.

    2012-01-01

    The quiet-time coherent backscatter from the F-region observed by the Tasman International Geospace Environment Radar (TIGER) Bruny Island HF radar is analysed statistically in order to determine typical trends and controlling factors in the ionospheric echo occurrence. A comparison of the F-region peak density values from the IRI-2007 model and ionosonde measurements in the vicinity of the radar's footprint shows a very good agreement, particularly at subauroral and auroral latitudes, and model densities within the radar's footprint are used in the following analyses. The occurrence of F-region backscatter is shown to exhibit distinct diurnal, seasonal and solar cycle variations and these are compared with model trends in the F-region peak electron density and Pedersen conductance of the underlying ionosphere. The solar cycle effects in occurrence are demonstrated to be strong and more complex than a simple proportionality on a year-to-year basis. The diurnal and seasonal effects are strongly coupled to each other, with diurnal trends exhibiting a systematic gradual variation from month to month that can be explained when both electron density and conductance trends are considered. During the night, the echo occurrence is suggested to be controlled directly by the density conditions, with a direct proportionality observed between the occurrence and peak electron density. During the day, the echo occurrence appears to be controlled by both conductance and propagation conditions. It is shown that the range of echo occurrence values is smaller for larger conductances and that the electron density determines what value the echo occurrence takes in that range. These results suggest that the irregularity production rates are significantly reduced by the highly conducting E layer during the day while F-region density effects dominate during the night.

  17. ENERGETIC PARTICLE OBSERVATIONS AND PROPAGATION IN THE THREE-DIMENSIONAL HELIOSPHERE DURING THE 2006 DECEMBER EVENTS

    SciTech Connect

    Malandraki, O. E.; Marsden, R. G.; Tranquille, C.; Lario, D.; Heber, B.; Mewaldt, R. A.; Cohen, C. M. S.; Lanzerotti, L. J.; Forsyth, R. J.; Elliott, H. A.; Vogiatzis, I. I.; Geranios, A.

    2009-10-10

    We report observations of solar energetic particles obtained by the HI-SCALE and COSPIN/LET instruments onboard Ulysses during the period of isolated but intense solar activity in 2006 December, in the declining phase of the solar activity cycle. We present measurements of particle intensities and also discuss observations of particle anisotropies and composition in selected energy ranges. Active Region 10930 produced a series of major solar flares with the strongest one (X9.0) recorded on December 5 after it rotated into view on the solar east limb. Located over the South Pole of the Sun, at >72{sup 0}S heliographic latitude and 2.8 AU radial distance, Ulysses provided unique measurements for assessing the nature of particle propagation to high latitudes under near-minimum solar activity conditions, in a relatively undisturbed heliosphere. The observations seem to exclude the possibility that magnetic field lines originating at low latitudes reached Ulysses, suggesting either that the energetic particles observed as large solar energetic particle (SEP) events over the South Pole of the Sun in 2006 December were released when propagating coronal waves reached high-latitude field lines connected to Ulysses, or underwent perpendicular diffusion. We also discuss comparisons with energetic particle data acquired by the STEREO and Advanced Composition Explorer in the ecliptic plane near 1 AU during this period.

  18. Temporal evolution of a hydrothermal system in Kusatsu-Shirane Volcano, Japan, inferred from the complex frequencies of long-period events

    USGS Publications Warehouse

    Kumagai, H.; Chouet, B.A.; Nakano, M.

    2002-01-01

    We present a detailed description of temporal variations in the complex frequencies of long-period (LP) events observed at Kusatsu-Shirane Volcano. Using the Sompi method, we analyze 35 LP events that occurred during the period from August 1992 through January 1993. The observed temporal variations in the complex frequencies can be divided into three periods. During the first period the dominant frequency rapidly decreases from 5 to 1 Hz, and Q of the dominant spectral peak remains roughly constant with an average value near 100. During the second period the dominant frequency gradually increases up to 3 Hz, and Q gradually decreases from 160 to 30. During the third period the dominant frequency increases more rapidly from 3 to 5 Hz, and Q shows an abrupt increase at the beginning of this period and then remains roughly constant with an average value near 100. Such temporal variations can be consistently explained by the dynamic response of a hydrothermal crack to a magmatic heat pulse. During the first period, crack growth occurs in response to the overall pressure increase in the hydrothermal system caused by the heat pulse. Once crack formation is complete, heat gradually changes the fluid in the crack from a wet misty gas to a dry gas during the second period. As heating of the hydrothermal system gradually subsides, the overall pressure in this system starts to decrease, causing the collapse of the crack during the third period.

  19. CRRES observations of ion composition during EMIC mode wave events

    SciTech Connect

    Macdonald, Elizabeth; Larsen, Brian

    2010-12-13

    EMIC mode waves may play an important role in the dynamics of the growth and loss of the radiation belts. CRRES mission analysis has provided extensive information on the distributions of EMIC mode waves. Less well studied and understood is the role that ion composition plays in the formation of the EMIC mode waves. The CRESS plasma mass spectrometer LOMICS measured all ion species of interest up to 45 keV/q. This preliminary study will examine the characteristics of heavy ions during a multitude of wave events, in particular, the effect of ion composition on wave-particle interactions, amplitude, and frequency. The relevance of such data to the upcoming RBSP mission will be highlighted.

  20. Human event observations in the individual plant examinations

    SciTech Connect

    Forester, J.

    1995-04-01

    A major objective of the Individual Plant Examination Insights Program is to identify the important determinants of core damage frequency for the different reactor and containment types and plant designs as indicated in the IPEs. The human reliability analysis is a critical component of the probabilistic risk assessments which were done for the IPEs. The determination and selection of human actions for incorporation into the event and fault tree models and the quantification of their failure probabilities can have an important impact on the resulting estimates of CDF and risk. Two important goals of the NRCs IPE Insights Program are (1) to determine the extent to which human actions and their corresponding failure probabilities influenced the results of the IPEs and (2) to identify which factors played significant roles in determining the differences and similarities in the results of the HRA analyses across the different plants. To obtain the relevant information, the NRC`s IPE database, which contains information on plant design, CDF, and containment performance obtained from the IPEs, was used in conjunction with a systematic examination of the HRA analyses and results from the IPEs. Regarding the extent to which the results of the HRA analyses were significant contributors to the plants` CDFs, examinations of several different measures indicated that while individual human actions could have important influences on CDF for particular initiators, the HRA results did not appear to be the most significant driver of plant risk. Another finding was that while there were relatively wide variations in the calculated human error probabilities for similar events across plants, there was no evidence for any systematic variation as a function of the HRA methods used in the analyses. Much of the variability in HEP values can be explained by differences in plant characteristics and sequence-specific factors. Details of these results and other findings are discussed.

  1. Human event observations in the individual plant examinations

    SciTech Connect

    Forester, J.

    1995-01-01

    A major objective of the Nuclear Regulatory Commission`s (NRC) Individual Plant Examination (IPE) Insights Program is to identify the important determinants of core damage frequency (CDF) for the different reactor and containment types and plant designs as indicated in the IPEs. The human reliability analysis (HRA) is a critical component of the probabilistic risk assessments (PRAS) which were done for the IPES. The determination and selection of human actions for incorporation into the event and fault tree models and the quantification of their failure probabilities can have an important impact on the resulting estimates of CDF and risk. Therefore, two important goals of the NRCs IPE Insights Program are (1) to determine the extent to which human actions and their corresponding failure probabilities influenced the results of the IPEs and (2) to identify which factors played significant roles in determining the differences and similarities in the results of the HRA analyses across the different plants. To obtain the relevant information, the NRC`s IPE database, which contains information on plant design, CDF, and containment performance obtained from the IPES, was used in conjunction with a systematic examination of the HRA analyses and results from the IPES. Regarding the extent to which the results of the HRA analyses were significant contributors to the plants` CDFs, examinations of several different measures indicated that while individual human actions could have important influences on CDF for particular initiators, the HRA results did not appear to be the most significant driver of plant risk (CDF). Another finding was that while there were relatively wide variations in the calculated human error probabilities (HEPs) for similar events across plants, there was no evidence for any systematic variation as a function of the HRA methods used in the analyses.

  2. Shallow degassing events as a trigger for very-long-period seismicity at Kīlauea Volcano, Hawai‘i

    USGS Publications Warehouse

    Patrick, Matthew; Wilson, David; Fee, David; Orr, Tim R.; Swanson, Donald A.

    2011-01-01

    The first eruptive activity at Kīlauea Volcano’s summit in 25 years began in March 2008 with the opening of a 35-m-wide vent in Halema‘uma‘u crater. The new activity has produced prominent very-long-period (VLP) signals corresponding with two new behaviors: episodic tremor bursts and small explosive events, both of which represent degassing events from the top of the lava column. Previous work has shown that VLP seismicity has long been present at Kīlauea’s summit, and is sourced approximately 1 km below Halema‘uma‘u. By integrating video observations, infrasound and seismic data, we show that the onset of the large VLP signals occurs within several seconds of the onset of the degassing events. This timing indicates that the VLP is caused by forces—sourced at or very near the lava free surface due to degassing—transmitted down the magma column and coupling to the surrounding rock at 1 km depth.

  3. Large geomagnetic storms of extreme solar event periods in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Wang, Ruiguang

    During extreme solar events such as big flares or/and energetic coronal mass ejections (CMEs) high energy particles are accelerated by the shocks formed in front of fast interplanetary coronal mass ejections (ICMEs). The ICMEs (and their sheaths) also give rise to large geomagnetic storms which have significant effects on the Earth's environment and human life. Around 14 solar cosmic ray ground level enhancement (GLE) events in solar cycle 23 we examined the cosmic ray variation, solar wind speed, ions density, interplanetary magnetic field, and geomagnetic disturbance storm time index ( Dst). We found that all but one of GLEs are always followed by a geomagnetic storm with Dst ⩽ -50 nT within 1-5 days later. Most(10/14) geomagnetic storms have Dst index ⩽ -100 nT therefore generally belong to strong geomagnetic storms. This suggests that GLE event prediction of geomagnetic storms is 93% for moderate storms and 71% for large storms when geomagnetic storms preceded by GLEs. All Dst depressions are associated with cosmic ray decreases which occur nearly simultaneously with geomagnetic storms. We also investigated the interplanetary plasma features. Most geomagnetic storm correspond significant periods of southward Bz and in close to 80% of the cases that the Bz was first northward then turning southward after storm sudden commencement (SSC). Plasma flow speed, ion number density and interplanetary plasma temperature near 1 AU also have a peak at interplanetary shock arrival. Solar cause and energetic particle signatures of large geomagnetic storms and a possible prediction scheme are discussed.

  4. Observing trends in total ozone and extreme ozone events

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2014-05-01

    The ozone layer in the stratosphere has been recovering since the 1989 Montreal Protocol reduced the use of ozone-destroying chlorofluorocarbons. Fitzka et al. observed trends in total ozone levels and the vertical distribution of ozone at Hoher Sonnblick, a mountain in Austria, from 1994 to 2011.

  5. Observing and Studying Extreme Low Pressure Events with Altimetry

    PubMed Central

    Carrère, Loren; Mertz, Françoise; Dorandeu, Joel; Quilfen, Yves; Patoux, Jerome

    2009-01-01

    The ability of altimetry to detect extreme low pressure events and the relationship between sea level pressure and sea level anomalies during extra-tropical depressions have been investigated. Specific altimeter treatments have been developed for tropical cyclones and applied to obtain a relevant along-track sea surface height (SSH) signal: the case of tropical cyclone Isabel is presented here. The S- and C-band measurements are used because they are less impacted by rain than the Ku-band, and new sea state bias (SSB) and wet troposphere corrections are proposed. More accurate strong altimeter wind speeds are computed thanks to the Young algorithm. Ocean signals not related to atmospheric pressure can be removed with accuracy, even within a Near Real Time context, by removing the maps of sea level anomaly (SLA) provided by SSALTO/Duacs. In the case of Extra-Tropical Depressions, the classical altimeter processing can be used. Ocean signal not related to atmospheric pressure is along-track filtered. The sea level pressure (SLP)-SLA relationship is investigated for the North Atlantic, North Pacific and Indian oceans; three regression models are proposed allowing restoring an altimeter SLP with a mean error of 5 hPa if compared to ECMWF or buoys SLP. The analysis of barotropic simulation outputs points out the regional variability of the SLP/Model Sea Level relationship and the wind effects. PMID:22573955

  6. Observing and studying extreme low pressure events with altimetry.

    PubMed

    Carrère, Loren; Mertz, Françoise; Dorandeu, Joel; Quilfen, Yves; Patoux, Jerome

    2009-01-01

    The ability of altimetry to detect extreme low pressure events and the relationship between sea level pressure and sea level anomalies during extra-tropical depressions have been investigated. Specific altimeter treatments have been developed for tropical cyclones and applied to obtain a relevant along-track sea surface height (SSH) signal: the case of tropical cyclone Isabel is presented here. The S- and C-band measurements are used because they are less impacted by rain than the Ku-band, and new sea state bias (SSB) and wet troposphere corrections are proposed. More accurate strong altimeter wind speeds are computed thanks to the Young algorithm. Ocean signals not related to atmospheric pressure can be removed with accuracy, even within a Near Real Time context, by removing the maps of sea level anomaly (SLA) provided by SSALTO/Duacs. In the case of Extra-Tropical Depressions, the classical altimeter processing can be used. Ocean signal not related to atmospheric pressure is along-track filtered. The sea level pressure (SLP)-SLA relationship is investigated for the North Atlantic, North Pacific and Indian oceans; three regression models are proposed allowing restoring an altimeter SLP with a mean error of 5 hPa if compared to ECMWF or buoys SLP. The analysis of barotropic simulation outputs points out the regional variability of the SLP/Model Sea Level relationship and the wind effects. PMID:22573955

  7. Coupling rainfall observations and satellite soil moisture for predicting event soil loss in Central Italy

    NASA Astrophysics Data System (ADS)

    Todisco, Francesca; Brocca, Luca; Termite, Loris Francesco; Wagner, Wolfgang

    2015-04-01

    always the lowest; the accuracy in estimating the event soil loss of a models with erosivity factor that includes the estimated runoff is always overcome by at least one model that uses the antecedent soil moisture θ in the erosivity index; the power models generally, at Masse, work better than the linear. The more accurate models are that with the estimated antecedent soil moisture, θest, when all the database is used and with the satellite retrieved soil moisture, θsat, when only the wet periods' events are considered. In fact it was also verified that much of the inaccuracy of the tested models is due to summer rainfall events, probably because of the particular characteristics that the soil assumes in the dry period (superficial crusts causing higher runoff): in this cases, high soil losses are observed in association to low values of soil moisture, while the simulated runoff assume low values too, since they are based on the antecedent wetness conditions. Thus, the analyses were repeated excluding the summer events. As expected, the performance of all the models increases, but still the use of θ provides the best results. The results of the analysis open interesting scenarios in the use of USLE-derived models for the unit event soil loss estimation at large scale. In particular the use of the soil moisture to correct the rainfall erosivity factor acquires a great practical importance, since it is a relatively simple measurable data and moreover because remote sensing soil moisture data are widely available and useful in large-scale erosion assessment. Bagarello, V., Di Piazza, G. V., Ferro, V., Giordano, G., 2008. Predicting unit soil loss in Sicily, south Italy. Hydrol. Process. 22, 586-595. Bagarello, V., Ferro, V., Giordano, G., Mannocchi, F., Todisco, F., Vergni, L., 2013. Predicting event soil loss form bare plots at two Italian sites. Catena 109, 96-102. Brocca, L., Melone, F., Moramarco, T., 2011. Distributed rainfall-runoff modeling for flood frequency

  8. ULF Oscillations in Magma in the Period of seismic Event Preparation

    NASA Astrophysics Data System (ADS)

    Kopytenko, Yu. A.; Nikitina, L. V.

    2003-04-01

    ULF OSCILLATIONS IN MAGMA IN THE PERIOD OF SEISMIC EVENT PREPARATION Yu.A.Kopytenko, L.V.Nikitina SPbF IZMIRAN, Muchnoi per.2, p/b 188, St-Petersburg, Russia, 191023 lida@mail.spbnit.ru Magma movements in volcanic center are activated in the period of the seismic event preparation. Hydrodynamic processes in the moving magma can lead to appearance of waves and vortices in the flow. In this work different sources of ULF pulsations in magma are considered. The electromagnetic emission induced by ULF pulsations in magma is estimated. An initial source of magma is at the depth about 100km. When volcano activity increases magma moves upward to the Earth surface by volcano channels, filling intermediate volcano reservoirs. Magma is a two-phase liquid (liquid with gas). If volcanic activity increases some bubbles of gas in magma are floating up to its surface. Bubbles of gas disturb the magma surface and support the oscillations on this surface. The magnetic fields induced by this oscillations are about 0.01-0.1 nT if we assume that a conductivity of hot magma is about 0.01 Sm/m. The second cause of the ULF movements in magma is connected with vortex structures that appear in magma flow under the action of Coriolys force. Corresponding quasiconstant magnetic fields are about 0.2nT. The describing mechanism allows to explain some features of electromagnetic emissions in the period of the Earthquake preparation: the increase of the electromagnetic emission about 1.5-2 months before the earthquake and a sharp decrease of emission about 1.5 - 2 days before the earthquake. It's considered a spreading of the variable electromagnetic fields from the source to the Earth surface. It's shown that at the distance about 100 km from the source the magnetic field decreases to 0.05-0.1 nT. Gradient of the magnetic field is about 1-5pT/km that is in accordance with the measured data.

  9. Brightening event seen in observations of Jupiter's extended sodium nebula

    NASA Astrophysics Data System (ADS)

    Yoneda, M.; Kagitani, M.; Tsuchiya, F.; Sakanoi, T.; Okano, S.

    2015-11-01

    Jupiter's sodium nebula, which originates from Io's volcanic gas, shows variations in its brightness due to the volcanic activity on Io. Imaging observation of D-line brightness in the sodium nebula was performed from 2013 through 2015 in a conjunction with the HISAKI mission. The D-line brightness of the sodium nebula had been stably faint and dim until January 2015, but it showed a distinct enhancement from February through March, 2015. The brightness increased by three times during this enhancement. Details in variations of Jupiter's sodium nebula are shown in this paper.

  10. Use of Earth Observation in Support of Major Sport Events: The Post Games Assessment of the Sporting Events of the Olympic Games 2004

    NASA Astrophysics Data System (ADS)

    Asimakopoulos, D.; Cartalis, C.; Petrakis, M.; Adaktylou, N.; Stathopoulou, M.; Chrysoulakis, N.

    2013-01-01

    Major sport events may result in the modification of the urban environment, or may be used as a tool for urban planning and/or urban regeneration projects. To this end, the main objective of the DRAGON-2 Project 5295 was to support the planning needs of major sport events with the use of Earth Observation (EO). The project also focused on the post games assessment of sporting events, with application to the Olympic Games (OG) of 2004 and 2008. More specifically, the research that was contacted in the project’s lifecycle was to examine how a major sporting event affected the urban fabric and the urban environmental quality in both Athens and Beijing. A wide number of thematic areas such as land use and cover, urban microclimate, urban green and air quality were examined and specific indicators for each thematic area were evaluated. Special emphasis was given on the description of thermal comfort, as well as on the changes in the quality of life in the host cities prior and following to the organization of the sporting events. A synopsis of the research results of the period 2008 - 2011 is given in this study along with an assessment of the potential of EO to actually support sport events.

  11. Modulation of Young Injection Events at Saturn at the Rotation Period of Perturbations in the Winter Hemisphere: A Proposed Mechanism

    NASA Astrophysics Data System (ADS)

    Kivelson, M.; Jia, X.

    2014-12-01

    Non-dispersive or "young" plasma injection events observed near midnight at Saturn are modulated at the period associated with the winter hemisphere [Kennelly et al., 2013]. Most other periodic dynamics of the magnetosphere are dominated by responses at the period of the summer hemisphere. The anomalous periodicity of plasma injection has not been explained. We present a theoretical explanation of ionospheric control, noting (as do Kennelly et al.) that the growth rate of the interchange instability is controlled by ionospheric conductance although the instability condition does not involve the ionosphere [Southwood and Kivelson, 1989]. The motion of the foot of a flux tube through the ionosphere is impeded by high conductance (line tying). Low conductance allows slippage and rapid growth of the instability. When the ionospheres have very different conductances, flux tube motion may be asymmetrical, with rapid displacement occurring only in the low conductance, winter hemisphere. A rotationally modulated low conductivity in that hemisphere would impose periodicity on injections. Pre-equinox (2009) at Saturn, the northern hemisphere conductance was low but probably varied with rotation phase because of the pattern of field-aligned currents (FACs) thought to rotate about the pole at the northern period, TN[Jia and Kivelson, 2012]. The upward current region in the ionosphere was probably more highly ionized than the downward current region because of electron precipitation. Two predictions follow. (1) The probability of an injection event in the midnight sector should maximize when the downward FAC in the winter hemisphere (conductivity minimum) has rotated into the midnight sector and (2) in northern winter, the tilt of the interchanging flux tube should produce positive radial field perturbations at and above the equator for inward-moving flux tubes and negative radial field perturbations for outward-moving flux tubes. Tests of these predictions will be reported

  12. OMI Tropospheric NO2 from Lightning in Observed Convective Events

    NASA Technical Reports Server (NTRS)

    Pickering, Kenneth; Bucsela, Eric; Kucsera, Tom; Pan, Laura; Davis, Chris; Gleason, James; Levelt, Pieternel

    2007-01-01

    Lightning is responsible for an estimated 15 percent of total NO emissions, and is one of the most prominent sources in the upper troposphere. In this study, we present evidence of lightning-generated NO2 (LNO2) using data from the Ozone Monitoring Instrument (OMI), which has observed tropospheric NO2 since its launch in 2004. Although LNO2 has been also reported in previous satellite studies from the Global Ozone Monitoring Experiment (GOME) and SCIAMACHY, OMI is better suited for such measurements by virtue of its higher spatial resolution and daily global coverage. We will present data clearly showing the LNO2 signal in the OMI tropospheric NO2 product on two days over and downwind of specific convective systems in the US Midwest. Gridded monthly mean tropospheric NO 2 data are subtracted from the daily gridded data to obtain the presumed LNO2 signal. Observed cloud-to-ground (CG) lightning flashes from the National Lightning Detection Network (NLDN) were counted along middle and upper tropospheric back trajectories that were run from the regions containing the LNO2 signal. A vertically-weighted average number of upwind CG flashes was obtained using a profile of LNO(x) mass obtained from a series of midlatitude cloud-resolved storm chemistry simulations. The number of CG flashes was scaled up to total flashes (intracloud (IC) flashes plus CG) using a climatological IC/CG ratio. The number of moles of LNO(x) in the region considered was estimated by assuming that LNO2 is 30 percent of LNO(x). This value was divided by the number of upwind flashes to obtain an average estimate of the number of moles produced per flash. Results yield values in the range obtained through other estimation techniques (e.g., aircraft measurements, models). We will also present a similar analysis over northern Australia during the SCOUT-O3/ACTIVE field campaigns in November and December 2005, in which we will compare the OMI LNOx signals with aircraft observations from the storm anvils.

  13. Freja observations of multiple injection events in cusp

    NASA Astrophysics Data System (ADS)

    Norberg, O.; Yamauchi, M.; Eliasson, L.; Lundin, R.

    The TICS (Three-dimensional Ion Composition Spectrometer) instrument on board the Freja satellite provides particle data with high spatial, temporal, spectral, and mass resolution. The Freja orbit (inclination 63°) is suitable for studies of the cusp since the satellite traverses this region longitudinally when the cusp is located lower than 75° geomagnetic latitude, i.e. when the interplanetary magnetic field (IMF) points southward. The satellite traverses the dayside polar region during two weeks every 100 days due to orbit precession, and nearly 50 cusp traversals were recorded during the first year of operation. Both multiple injections and single injections are clearly identified and distinguished, the former being more frequently observed than the latter. Freja has also resolved overlapping injections (special cases of multiple injections), for the first time at low altitudes.

  14. Shock Connectivity in the August 2010 and July 2012 Solar Energetic Particle Events Inferred from Observations and ENLIL Modeling

    NASA Astrophysics Data System (ADS)

    Bain, H. M.; Mays, M. L.; Luhmann, J. G.; Li, Y.; Jian, L. K.; Odstrcil, D.

    2016-07-01

    During periods of increased solar activity, coronal mass ejections (CMEs) can occur in close succession and proximity to one another. This can lead to the interaction and merger of CME ejecta as they propagate in the heliosphere. The particles accelerated in these shocks can result in complex solar energetic particle (SEP) events, as observing spacecraft form both remote and local shock connections. It can be challenging to understand these complex SEP events from in situ profiles alone. Multipoint observations of CMEs in the near-Sun environment, from the Solar Terrestrial Relations Observatory–Sun Earth Connection Coronal and Heliospheric Investigation and the Solar and Heliospheric Observatory Large Angle and Spectrometric Coronagraph, greatly improve our chances of identifying the origin of these accelerated particles. However, contextual information on conditions in the heliosphere, including the background solar wind conditions and shock structures, is essential for understanding SEP properties well enough to forecast their characteristics. Wang–Sheeley–Arge WSA-ENLIL + Cone modeling provides a tool to interpret major SEP event periods in the context of a realistic heliospheric model and to determine how much of what is observed in large SEP events depends on nonlocal magnetic connections to shock sources. We discuss observations of the SEP-rich periods of 2010 August and 2012 July in conjunction with ENLIL modeling. We find that much SEP activity can only be understood in the light of such models, and in particular from knowing about both remote and local shock source connections. These results must be folded into the investigations of the physics underlying the longitudinal extent of SEP events, and the source connection versus diffusion pictures of interpretations of SEP events.

  15. Observations of planetary waves in the mesosphere-lower thermosphere during stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Stray, N. H.; Orsolini, Y. J.; Espy, P. J.; Limpasuvan, V.; Hibbins, R. E.

    2015-05-01

    This study investigates the effect of stratospheric sudden warmings (SSWs) on planetary wave (PW) activity in the mesosphere-lower thermosphere (MLT). PW activity near 95 km is derived from meteor wind data using a chain of eight SuperDARN radars at high northern latitudes that span longitudes from 150° W to 25° E and latitudes from 51 to 66° N. Zonal wave number 1 and 2 components were extracted from the meridional wind for the years 2000-2008. The observed wintertime PW activity shows common features associated with the stratospheric wind reversals and the accompanying stratospheric warming events. Onset dates for seven SSW events accompanied by an elevated stratopause (ES) were identified during this time period using the Specified Dynamics Whole Atmosphere Community Climate Model (SD-WACCM). For the seven events, a significant enhancement in wave number 1 and 2 PW amplitudes near 95 km was found to occur after the wind reversed at 50 km, with amplitudes maximizing approximately 5 days after the onset of the wind reversal. This PW enhancement in the MLT after the event was confirmed using SD-WACCM. When all cases of polar cap wind reversals at 50 km were considered, a significant, albeit moderate, correlation of 0.4 was found between PW amplitudes near 95 km and westward polar-cap stratospheric winds at 50 km, with the maximum correlation occurring ∼ 3 days after the maximum westward wind. These results indicate that the enhancement of PW amplitudes near 95 km is a common feature of SSWs irrespective of the strength of the wind reversal.

  16. An ionospheric travelling convection vortex event observed by ground-based magnetometers and by VIKING

    SciTech Connect

    Vogelsang, H.; Voelker, H. ); Luehr, H. ); Woch, J. ); Boesinger, T. ); Potemra, T.A. ); Lindqvist, P.A. )

    1993-11-05

    This paper reports the ground based observation of an ionospheric travelling convection vortex event, which was observed in coincidence with observation of the VIKING spacecraft passing through closed field lines which map to this region. The spacecraft saw electric and magnetic signatures which were consistent with it having passed through field aligned current tubes, oppositely directed. This is the first such simultaneous observation and supports the theoretical models which relate such ionospheric travelling convection vortex events to field aligned currents.

  17. Fortuitous Plasma Observations During the Mars Atmospheric "Plume" Event of March-April 2012

    NASA Astrophysics Data System (ADS)

    Andrews, David; Barabash, Stas; Edberg, Niklas; Gurnett, Donald; Hall, Ben; Holmström, Mats; Lester, Mark; Opgenoorth, Hermann; Ramstad, Robin; Sanchez-Cano, Beatriz; Way, Michael; Witasse, Olivier; Morgan, David

    2016-04-01

    We present initial analysis and conclusions from plasma observations made during the reported `Mars Dust plume event' of March - April 2012.During this period, multiple independent amateur observers detected a localized, high-altitude feature over the Martian terminator [Sanchez-Lavega et al., Nature, 2015, doi:10.1038/nature14162], the explanation for which remains incomplete. The brightness of the feature in visible light is too extreme for auroral emissions to explain, despite its occurrence at a location where these have been previously reported. Likewise, the (projected) altitude of the feature is significantly too high to allow for the local formation of clouds. Fortuitously, the orbit of ESA's Mars Express allowed the measurement of ionospheric plasma density and solar wind parameters over the precise location of the plume sighting at multiple points during this interval. Based on these observations, we tentatively conclude that the formation and/or transport of this plume to the altitudes where it was observed was in part the result of a large Coronal Mass Ejection encountering the Martian system. However, while measurements of ionospheric plasma density at the corresponding altitudes indicate a disturbed structure, this is not a-typical of this location over Mars. Finally, we briefly discuss some possible mechanisms that may lead to the formation of this plume.

  18. The excitation and characteristic frequency of the long-period volcanic event: An approach based on an inhomogeneous autoregressive model of a linear dynamic system

    USGS Publications Warehouse

    Nakano, M.; Kumagai, H.; Kumazawa, M.; Yamaoka, K.; Chouet, B.A.

    1998-01-01

    We present a method to quantify the source excitation function and characteristic frequencies of long-period volcanic events. The method is based on an inhomogeneous autoregressive (AR) model of a linear dynamic system, in which the excitation is assumed to be a time-localized function applied at the beginning of the event. The tail of an exponentially decaying harmonic waveform is used to determine the characteristic complex frequencies of the event by the Sompi method. The excitation function is then derived by operating an AR filter constructed from the characteristic frequencies to the entire seismogram of the event, including the inhomogeneous part of the signal. We apply this method to three long-period events at Kusatsu-Shirane Volcano, central Japan, whose waveforms display simple decaying monochromatic oscillations except for the beginning of the events. We recover time-localized excitation functions lasting roughly 1 s at the start of each event and find that the estimated functions are very similar to each other at all the stations of the seismic network for each event. The phases of the characteristic oscillations referred to the estimated excitation function fall within a narrow range for almost all the stations. These results strongly suggest that the excitation and mode of oscillation are both dominated by volumetric change components. Each excitation function starts with a pronounced dilatation consistent with a sudden deflation of the volumetric source which may be interpreted in terms of a choked-flow transport mechanism. The frequency and Q of the characteristic oscillation both display a temporal evolution from event to event. Assuming a crack filled with bubbly water as seismic source for these events, we apply the Van Wijngaarden-Papanicolaou model to estimate the acoustic properties of the bubbly liquid and find that the observed changes in the frequencies and Q are consistently explained by a temporal change in the radii of the bubbles

  19. Mix of methods is needed to identify adverse events in general practice: A prospective observational study

    PubMed Central

    Wetzels, Raymond; Wolters, René; van Weel, Chris; Wensing, Michel

    2008-01-01

    Background The validity and usefulness of incident reporting and other methods for identifying adverse events remains unclear. This study aimed to compare five methods in general practice. Methods In a prospective observational study, with five general practitioners, five methods were applied and compared. The five methods were physician reported adverse events, pharmacist reported adverse events, patients' experiences of adverse events, assessment of a random sample of medical records, and assessment of all deceased patients. Results A total of 68 events were identified using these methods. The patient survey accounted for the highest number of events and the pharmacist reports for the lowest number. No overlap between the methods was detected. The patient survey accounted for the highest number of events and the pharmacist reports for the lowest number. Conclusion A mix of methods is needed to identify adverse events in general practice. PMID:18554418

  20. Coupling rainfall observations and satellite soil moisture for predicting event soil loss in Central Italy

    NASA Astrophysics Data System (ADS)

    Todisco, Francesca; Brocca, Luca; Termite, Loris Francesco; Wagner, Wolfgang

    2015-04-01

    The accuracy of water soil loss prediction depends on the ability of the model to account for effects of the physical phenomena causing the output and the accuracy by which the parameters have been determined. The process based models require considerable effort to obtain appropriate parameter values and their failure to produce better results than achieved using the USLE/RUSLE model, encourages the use of the USLE/RUSLE model in roles of which it was not designed. In particular it is widely used in watershed models even at the event temporal scale. At hillslope scale, spatial variability in soil and vegetation result in spatial variations in soil moisture and consequently in runoff within the area for which soil loss estimation is required, so the modeling approach required to produce those estimates needs to be sensitive to those spatial variations in runoff. Some models include explicit consideration of runoff in determining the erosive stresses but this increases the uncertainty of the prediction due to the difficulty in parameterising the models also because the direct measures of surface runoff are rare. The same remarks are effective also for the USLE/RUSLE models including direct consideration of runoff in the erosivity factor (i.e. USLE-M by Kinnell and Risse, 1998, and USLE-MM by Bagarello et al., 2008). Moreover actually most of the rainfall-runoff models are based on the knowledge of the pre-event soil moisture that is a fundamental variable in the rainfall-runoff transformation. In addiction soil moisture is a readily available datum being possible to have easily direct pre-event measures of soil moisture using in situ sensors or satellite observations at larger spatial scale; it is also possible to derive the antecedent water content with soil moisture simulation models. The attempt made in the study is to use the pre-event soil moisture to account for the spatial variation in runoff within the area for which the soil loss estimates are required. More

  1. The FU Orionis Outburst as a Thermal Disk Accretion Event: Detailed Calculations and Comparison to Observations

    NASA Technical Reports Server (NTRS)

    Bell, K. R.

    1994-01-01

    FU Orionis outbursts are temporary large increases in luminosity: x(40-250) thought to occur repeatedly in all low mass young stellar systems. We discuss detailed calculations of viscous accretion disks suggesting that FU Ori events signify the existence of a protostellar disk transporting mass at a rate of (1-10) x 10(exp -6) Solar Mass/yr, in agreement with theoretical and observational estimates of molecular cloud core collapse rates. Accretion through the inner edge of disks subject to outburst is self-regulated through the thermal ionization instability such that long periods (approximately 1000 yrs) of low mass flux: (1-10) x 10(exp -8) Solar Mass/yr, are punctuated by short periods (approximately 100 yrs) of high mass flux: (1-10) x 10(exp -5) Solar Mass/yr. The unstable region of the disk extends radially only to a distance of approximately 1/4 AU. Beyond this region matter is transported stably at the infall rate. In systems for which M = 1 Solar Mass, with an inner disk edge of 3 Solar Radius, the critical rate for outbursts is 5 x 10(exp -7) Solar Mass/yr independent of the magnitude of the viscous alpha parameter consistent with estimates of boundary layer mass flux in T Tauri stars. We use timescales of observed outbursts to constrain the magnitude of the alpha parameter to be 10(exp -4) where hydrogen is neutral and 10(exp -3) where ionized. Light curves of V1515 Cyg, FU Ori, and V1057 Cyg are reproduced; the latter two require application of a small perturbation in surface density to produce observed rapid rise times. Detailed reply is made to objections to the accretion disk model for outbursts. Comparison to observations are made of time dependent spectral energy distributions, colors, and line-width velocity evolution.

  2. The FU Orionis Outburst as a Thermal Disk Accretion Event: Detailed Calculations and Comparison to Observations

    NASA Technical Reports Server (NTRS)

    Bell, K. R.; Cuzzi, Jeff (Technical Monitor)

    1994-01-01

    FU Orionis outbursts are temporary large increases in luminosity: x (40 - 250) thought to occur repeatedly in all low mass young stellar systems. We discuss detailed calculations of viscous accretion disks suggesting that FU Ori events signify the existence of a protostellar disk transporting mass at a rate of (1 - 10) x 10(exp 6) solar mass / yr, in agreement with theoretical and observational estimates of molecular cloud core collapse rates. Accretion through the inner edge of disks subject to outburst is self-regulated through the thermal ionization instability such that long periods (approx. 1000 yrs) of low mass flux: (1 - 10) x 10(exp -5) solar mass / yr, are punctuated by short periods (approx. 100 yrs) of high mass flux: (1-10) x 10(exp -5) solar mass / yr. The unstable region of the disk extends radially only to a distance of approx. = 1/4 AU. Beyond this region matter is transported stably at the infall rate. In systems for which M(sum *) = 1 solar mass with an inner disk edge of 3 solar radius, the critical rate for outbursts is 5 x 10(exp -7) solar mass / yr independent of the magnitude of the viscous ce parameter consistent with estimates of boundary layer mass flux in T Tauri stars. We use timescales of observed outbursts to constrain the magnitude of the alpha parameter to be 10(exp -4) where hydrogen is neutral and 10(exp -3) where ionized. Light curves of V1515 Cyg, FU Ori, and V1057 Cya are reproduced; the latter two require application of a small perturbation in surface density to produce observed rapid rise times. Detailed reply is made to objections to the accretion disk model for outbursts. Comparison to observations are made of time dependent spectral energy distributions, colors, and line-width velocity evolution.

  3. Adaptive periodic event-triggered consensus for multi-agent systems subject to input saturation

    NASA Astrophysics Data System (ADS)

    Yin, Xiuxia; Yue, Dong; Hu, Songlin

    2016-04-01

    This paper investigates the distributed adaptive event-triggered consensus control for a class of nonlinear agents. Each agent is subject to input saturation. Two kinds of distributed event-triggered control scheme are introduced, one is continuous-time-based event-triggered scheme and the other is sampled-data-based event-triggered scheme. Compared with the traditional event-triggered schemes in the existing literatures, the parameters of the event-triggered schemes in this paper are adaptively adjusted by using some event-error-dependent adaptive laws. The problem of simultaneously deriving the controller gain matrix and the event-triggering parameter matrix, and tackling the saturation nonlinearity is cast into standard linear matrix inequalities problem. A convincing simulation example is given to demonstrate the theoretical results.

  4. Damaging events along roads during bad weather periods: a case study in Calabria (Italy)

    NASA Astrophysics Data System (ADS)

    Petrucci, O.; Pasqua, A. A.

    2012-02-01

    The study focuses on circumstances that affect people during periods of bad weather conditions characterised by winds, rainfall, landslides, flooding, and storm surges. A methodological approach and its application to a study area in southern Italy are presented here. A 10-yr database was generated by mining data from a newspaper. Damaging agents were sorted into five types: flood, urban flooding, landslide, wind, and storm surge. Damage to people occurred in 126 cases, causing 13 victims, 129 injured and about 782 people involved but not injured. For cases of floods, urban flooding and landslides, the analysis does not highlight straightforward relationships between rainfall and damage to people, even if the events showed different features according to the months of occurrence. The events occurring between May and October were characterised by concentrated and intense rainfall, and between May and July, the highest values of hourly (103 mm on the average) and monthly rainfall (114 mm on the average) were recorded. Urban flooding and flash floods were the most common damaging agents: injured, involved people and more rarely, cases with victims were reported. Between November and April, the highest number of events was recorded. Rainfall presented longer durations and hourly and sub-hourly rainfall were lower than those recorded between May and October. Landslides were the most frequent damaging agents but the highest number of cases with victims, which occurred between November and January, were mainly related to floods and urban flooding. Motorists represent the totality of the victims; 84% of the people were injured and the whole of people involved. All victims were men, and the average age was 43 yr. The primary cause of death was drowning caused by floods, and the second was trauma suffered in car accidents caused by urban flooding. The high number of motorists rescued in submerged cars reveals an underestimation of danger in the case of floods, often

  5. The results of the 2015 campaign of observation of mutual events of the Jovian satellites

    NASA Astrophysics Data System (ADS)

    Arlot, J. E.; Saquet, E.; Emelianov, N.

    2015-10-01

    From September 2014 to June 2015 mutual events of the Galilean satellites occurred around the Jovian equinox occurring on February 6, 2015. The observations of these events provide very accurate information on the relative astrometry of the satellites. Previous campaign of observations have shown the high interest of such observations now performed mainly by amateur astronomers: the Galilean satellites are bright and the magnitude drop during these events is easily observable. The 2014- 2015 campaign is especially favorable because of the maximum of events which will occur during the opposition between the Sun and Jupiter. More, eclipses of Thebe and Amalthea by the Galileans have been observed. Note that the positive declination of Jupiter made the observations easier in the Northern hemisphere where, unfortunately, the meteorological conditions were bad.

  6. Analysis of Suprathermal Events Observed by STEREO/PLASTIC with a Focus on Upstream/Magnetospheric Events

    NASA Astrophysics Data System (ADS)

    Barry, J. A.; Galvin, A. B.; Popecki, M.; Ellis, L.; Klecker, B.; Lee, M. A.; Kucharek, H.

    2010-05-01

    The topic of suprathermal and energetic ion events upstream of the Earth's bow shock has been a topic of investigation since the late 1960's. Over the past 50 years these events have been characterized as having energies ranging from just above the solar wind energies on up to 2MeV, time spans of minutes to hours, and particle distribution functions ranging from field aligned to isotropic. The possible sources of these ions include magnetospheric ions and solar wind ions accelerated between the Earth's bow shock and low-frequency large amplitude waves in the ion foreshock. Also, energetic ions from other heliospheric processes (such as Solar Energetic Particle (SEP) events or Corotating Interaction Regions (CIRs)) can be further accelerated at the Earth's bow shock. Utilizing the particularly quiet solar minimum and the unique orbit of STEREO-A (STA), drifting ahead of the Earth in its heliocentric orbit, we are able to examine field-aligned upstream/magnetospheric energetic ion events in the unexamined region far upstream of the Earth's ion foreshock. Using both the PLASTIC and IMPACT instruments on board STA we have examined protons throughout 2007 in the energy range of 4keV up to 80keV. We find that the occurrence of automatically defined suprathermal events falls off with increasing STA-Earth separation. More importantly, it is shown through a crude approximation of the magnetic field via the Parker spiral that after a STA-Earth separation of about 3000Re it is unlikely that the Earth and STA will be magnetically connected. This corresponds well with the observed cutoff of the occurrence of suprathermal events with field-aligned anisotropies. The detection of upstream/magnetospheric events at these large distances from the Earth's bow shock indicates that the ions propagate relatively scatter free beyond the ion foreshock.

  7. Shallow degassing events as a trigger for very-long-period seismicity at Kilauea Volcano, Hawai`i

    NASA Astrophysics Data System (ADS)

    Patrick, M. R.; Wilson, D.; Fee, D.; Orr, T. R.; Swanson, D.

    2009-12-01

    The ongoing eruptive activity at the summit of Kilauea Volcano, Hawai`i, provides numerous opportunities for integrated data analysis due to dense geophysical monitoring combined with ease of viewing vent behavior. We focus on two behaviors not present during the preceding non-eruptive period. First, episodic seismic tremor, consisting of high-amplitude bursts lasting a few minutes and separated by seismically quiet intervals of similar duration, has appeared sporadically. Second, the eruptive activity has included seven small explosive eruptions in addition to the initial March 19, 2008, vent-opening explosion. Associated with many of the episodic tremor bursts and all of the explosive eruptions are very-long-period (VLP) seismic signals, and previous studies have shown the VLP source location to be at a depth of about 1 km beneath the central part of Kilauea caldera. By comparing precisely-timed video data with broadband seismicity and infrasound, we show that the largest amplitude portions of the VLP events coincide in time with apparent peak degassing from the top of the lava column during both the episodic tremor bursts and explosive eruptions. Because the top of the lava column is only a few hundred meters below local ground level, this timing suggests that the VLP events are caused by degassing-related energy transmitted down the magma column, which then couples with the surrounding rock at a depth of 1 km. This “top-down” model for the VLPs runs counter to previous analogue models which support a “bottom-up” process for VLPs at basaltic volcanoes, whereby gas slugs rise through a deep flare in the conduit, triggering VLPs at that location. Our work, which focuses on the geologic observations and their integration with geophysical data, is consistent with - and complements - recent seismic modeling of Kilauea’s VLPs by other researchers.

  8. Plasma observations during the Mars atmospheric "plume" event of March-April 2012

    NASA Astrophysics Data System (ADS)

    Andrews, D. J.; Barabash, S.; Edberg, N. J. T.; Gurnett, D. A.; Hall, B. E. S.; Holmström, M.; Lester, M.; Morgan, D. D.; Opgenoorth, H. J.; Ramstad, R.; Sanchez-Cano, B.; Way, M.; Witasse, O.

    2016-04-01

    We present initial analyses and conclusions from plasma observations made during the reported "Mars plume event" of March-April 2012. During this period, multiple independent amateur observers detected a localized, high-altitude "plume" over the Martian dawn terminator, the cause of which remains to be explained. The estimated brightness of the plume exceeds that expected for auroral emissions, and its projected altitude greatly exceeds that at which clouds are expected to form. We report on in situ measurements of ionospheric plasma density and solar wind parameters throughout this interval made by Mars Express, obtained over the same surface region but at the opposing terminator. Measurements in the ionosphere at the corresponding location frequently show a disturbed structure, though this is not atypical for such regions with intense crustal magnetic fields. We tentatively conclude that the formation and/or transport of this plume to the altitudes where it was observed could be due in part to the result of a large interplanetary coronal mass ejection (ICME) encountering the Martian system. Interestingly, we note that the only similar plume detection in May 1997 may also have been associated with a large ICME impact at Mars.

  9. Modeling Pluto-Charon Mutual Events. 2; CCD Observations with the 60 in. Telescope at Palomar Mountain

    NASA Technical Reports Server (NTRS)

    Buratti, B. J.; Dunbar, R. S.; Tedesco, E. F.; Gibson, J.; Marcialis, R. L.; Wong, F.; Bennett, S.; Dobrovolskis, A.

    1995-01-01

    We present observations of 15 Pluto-Charon mutual events which were obtained with the 60 in. telescope at Palomar Mountain Observatory. A CCD camera and Johnson V filter were used for the observations, except for one event that was observed with a Johnson B filter, and another event that was observed with a Gunn R filter. We observed two events in their entirety, and three pairs of complementary mutual occultation-transit events.

  10. Observational signatures of the influence of the interplanetary shocks on the associated low-energy particle events

    NASA Astrophysics Data System (ADS)

    Heras, A. M.; Sanahuja, B.; Sanderson, T. R.; Marsden, R. G.; Wenzel, K.-P.

    1994-01-01

    We have analyzed the temporal evolution of the upstream particle fluxes and anisotropies in a set of particle events associated with interplanetary shocks, detected by International Sun-Earth Explorer (ISEE) 3 during the period 1978-1980 in the 147-238 and 620-1000 keV energy ranges. In particular, we have studied those features that can perhaps be used as signatures of the history of the influence of the shock on the particle event. We have paid special attention to the evolution of the flux anisotropy that can carry relevant information on the contribution of shock accelerated particles to the total observed flux. Our analysis shows that during most events, long-lasting (between 5 and 36 hours) large anisotropies are observed upstream of the shock, supporting the hypothesis of continuous injection of shock accelerated paricles in the interplanetary medium while the shock is propagating outward from the Sun. The evolution of the anisotropy throughout each event shows a dependence on the longitude of the parent solar source. We have interpreted the observations considering that shock accelerated particles contribute significantly to the total observed flux from the time when the shock intersects the magnetic field line that connects with the observer. The heliocentric distance of this initial intersection point has been derived from the flux anisotropy observations for each event. The values obtained show a distribution with respect to the longitude of the solar source that can be reproduced with a simple model, which assumes a spherical shock with an angular extension approximately equals 100 deg and an archimedian spiral structure for the interplanetary magnetic field. The results of this work provide a further insight into both the importance of shock acceleration, as well as the influence of the large-scale shock structure in low-energy particle events.

  11. MASTER follow up observation of IceCube 160731A event

    NASA Astrophysics Data System (ADS)

    Lipunov, V.; Gorbovskoy, E.; Tyurina, N.; Kornilov, V.; Balanutsa, P.; Kuznetsov, A.; Kuvshinov, D.; Gorbunov, I.; Tlatov, A.; Senik, V.; Parhomenko, A. V.; Dormidontov, D.; Buckley, D.; Potter, S.; Kniazev, A.; Kotze, M.; Rebolo, R.; Serra, M.; Lodieu, N.; Israelian, G.; Podesta, R.; Lopez, C.; Podest, F.; Levato, H.; Saffe, C.; Gres, O.; Ivanov, K.; Yazev, S.; Budnev, N.; Poleshchuk, V.; Yurkov, V.; Sergienko, Yu.; Gabovich, A.

    2016-08-01

    MASTER Global robotic Net (MASTER-Net: http://observ.pereplet.ru , Lipunov et al., Advances in Astronomy, 2010, 30L ) received IceCube HESE event IceCube-160731A (AMON ICECUBE HESE 128290 6888376) at 2016-07-31 01:55:34.5 UT (30s after the EHE_event_time).

  12. Unusual attenuation events in the VLF range observed by the DEMETER spacecraft

    NASA Astrophysics Data System (ADS)

    Zahlava, Jan; Nemec, Frantisek; Parrot, Michel; Rodger, Craig J.; Santolik, Ondrej

    2015-04-01

    Results of a systematic study of unusual attenuation events observed by the DEMETER spacecraft in the VLF range are presented. In the frequency-time spectrograms of wave intensity, these attenuation events consist of several lines with significantly lower intensity. Detailed analysis of the events shows that they are formed by consecutive lightning generated whistlers. These whistlers are attenuated at some specific frequencies which vary continuously during the event, resulting in lines of lower intensity. We inspected all available DEMETER data for the presence of these attenuation events. Altogether, 1580 events have been identified. They occur exclusively during the nighttime. We compare the overall geographic distribution of the total event duration with the geographic distribution of the mean lightning occurrence. It is found that the event locations are closely related to the areas of enhanced lightning activity, but they are shifted by about 30 degrees westward. We present a simple model of a possible event formation based on a basic theory of wave propagation in the Earth-ionosphere waveguide. This model, however, does not explain the observed longitudinal shift. We believe that the shift is due to an azimuthal dependence of the wave attenuation in the Earth-ionosphere waveguide, which is not considered in the used simplified waveguide theory.

  13. Quasi-periodic pulsations with varying period in multi-wavelength observations of an X-class flare

    SciTech Connect

    Huang, Jing; Tan, Baolin; Zhang, Yin; Karlický, Marian; Mészárosová, Hana

    2014-08-10

    This work presents an interesting phenomenon of the period variation in quasi-periodic pulsations (QPPs) observed during the impulsive phase of a coronal mass ejection-related X1.1 class flare on 2012 July 6. The period of QPPs was changed from 21 s at soft X-rays (SXR) to 22-23 s at microwaves, to ∼24 s at extreme ultraviolet emissions (EUV), and to 27-32 s at metric-decimetric waves. The microwave, EUV, and SXR QPPs, emitted from flare loops of different heights, were oscillating in phase. Fast kink mode oscillations were proposed to be the modulation mechanism, which may exist in a wide region in the solar atmosphere from the chromosphere to the upper corona or even to the interplanetary space. Changed parameters of flare loops through the solar atmosphere could result in the varying period of QPPs at different wavelengths. The first appearing microwave QPPs and quasi-periodic metric-decimetric type III bursts were generated by energetic electrons. This may imply that particle acceleration or magnetic reconnection were located between these two non-thermal emission sources. Thermal QPPs (in SXR and EUV emissions) occurred later than the nonthermal ones, which would suggest a some time for plasma heating or energy dissipation in flare loops during burst processes. At the beginning of flare, a sudden collapse and expansion of two separated flare loop structures occurred simultaneously with the multi-wavelength QPPs. An implosion in the corona, including both collapse and expansion of flare loops, could be a trigger of loop oscillations in a very large region in the solar atmosphere.

  14. Biofilm formation and sanitizer resistance of Escherichia coli 0157:H7 strains isolated from "High Event Period" meat contamination

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the meat industry, a “High Event Period” (HEP) is defined as a time period during which commercial meat plants experience a higher than usual rate of E. coli O157:H7 contamination. Genetic analysis indicated that within a HEP, most of the E. coli O157:H7 strains belong to a singular dominant str...

  15. Response of a hydrothermal system to magmatic heat inferred from temporal variations in the complex frequencies of long-period events at Kusatsu-Shirane Volcano, Japan

    USGS Publications Warehouse

    Nakano, M.; Kumagai, H.

    2005-01-01

    We investigate temporal variations in the complex frequencies (frequency and quality factor Q) of long-period (LP) events that occurred at Kusatsu-Shirane Volcano, central Japan. We analyze LP waveforms observed at this volcano in the period between 1988 and 1995, which covers a seismically active period between 1989 and 1993. Systematic temporal variations in the complex frequencies are observed in October-November 1989, July-October 1991, and September 1992-January 1993. We use acoustic properties of a crack filled with hydrothermal fluids to interpret the observed temporal variations in the complex frequencies. The temporal variations in October-November 1989 can be divided into two periods, which are explained by a gradual decrease and increase of a gas-volume fraction in a water-steam mixture in a crack, respectively. The temporal variations in July-October 1991 can be also divided into two periods. These variations in the first and second periods are similar to those observed in November 1989 and in September-November 1992, respectively, and are interpreted as drying of a water-steam mixture and misty gas in a crack, respectively. The repeated nature of the temporal variations observed in similar seasons between July and November suggests the existence of seasonality in the occurrence of LP events. This may be caused by a seasonally variable meteoritic water supply to a hydrothermal system, which may have been heated by the flux of volcanic gases from magma beneath this volcano. ?? 2005 Elsevier B.V. All rights reserved.

  16. Isotropic events observed with a borehole array in the Chelungpu fault zone, Taiwan.

    PubMed

    Ma, Kuo-Fong; Lin, Yen-Yu; Lee, Shiann-Jong; Mori, Jim; Brodsky, Emily E

    2012-07-27

    Shear failure is the dominant mode of earthquake-causing rock failure along faults. High fluid pressure can also potentially induce rock failure by opening cavities and cracks, but an active example of this process has not been directly observed in a fault zone. Using borehole array data collected along the low-stress Chelungpu fault zone, Taiwan, we observed several small seismic events (I-type events) in a fluid-rich permeable zone directly below the impermeable slip zone of the 1999 moment magnitude 7.6 Chi-Chi earthquake. Modeling of the events suggests an isotropic, nonshear source mechanism likely associated with natural hydraulic fractures. These seismic events may be associated with the formation of veins and other fluid features often observed in rocks surrounding fault zones and may be similar to artificially induced hydraulic fracturing. PMID:22837526

  17. Archive of observations of periodic comet Crommelin made during its 1983-84 apparition

    NASA Technical Reports Server (NTRS)

    Sekanina, Z. (Editor); Aronsson, M.

    1985-01-01

    This is an archive of 680 reduced observations of Periodic Comet Crommelin made during its 1984 apparition. The archive integrates reports by members of the eight networks of the International Halley Watch (IHW) and presents the results of a trial run designed to test the preparedness of the IHW organization for the current apparition of Periodic Comet Halley.

  18. Observations of a transient event in the subsolar magnetosheath during strongly northward IMF

    NASA Astrophysics Data System (ADS)

    Dias Silveira, M. V.; Sibeck, D. G.; Gonzalez, W. D.; Koga, D.

    2013-12-01

    We present multipoint THEMIS observation of a transient event in the subsolar magnetosheath on July 10, 2007. The event exhibits some features of a flux transfer event, such as a bipolar variation in the magnetic field component normal to the nominal magnetopause centered on a peak in the total magnetic field strength. Four THEMIS spacecraft were in the magnetosheath and one in the magnetosphere. Timing analysis and the absence of flow perturbation suggest that the event is a small scale structure (~0.12 Re in the direction of the flow) moving with the background magnetosheath flow. Despite the inferred small size of the event, THC and THD both observed large amplitude (~40 nT) bipolar magnetic field signatures normal to the nominal magnetopause. Nearby spacecraft THE (only 0.2 Re further outward in the Xgsm direction) observed no significant magnetic field perturbation. Neither did THB or THA, located further away in the magnetosheath and magnetosphere, respectively. During the event, the IMF was strongly northward (approximately 20nT), which does not favor subsolar magnetic reconnection. Inside the structure, the magnetic field briefly rotates 90° away from northward to dawnward. Ions stream antiparallel to the magnetic field in the magnetosheath, parallel to the magnetic field in the event.

  19. Elemental Abundance Variations Observed in Solar Energetic Particle Events During Solar Cycle 23

    NASA Technical Reports Server (NTRS)

    vonRosenvinge, T. T.; Cohen, C. M. S.; Cummings, A. C.; Leske, R. A.; Mewaldt, R. A.; Stone, E. C.; Widenbeck, M. E.

    2004-01-01

    We report on observations of the abundances of elements from Helium to Nickel in over 50 different solar energetic particle events using the Solar Isotope Spectrometer (SIS) on-board the Advanced Composition Explorer (ACE) spacecraft. It had originally been expected that the energy spectra of different elements would show spectral roll-overs at energies related to the Q/M ratio of each element. Due to the partial stripping of Fe and essentially complete stripping of O, it was expected that the Fe/O ratio would be observed to decrease with increasing energy. While many events show this pattern, others have Fe/O which is constant with energy, while for yet others Fe/O actually increases with energy. Events having constant Fe/O could simply have their spectral breaks outside of the observed energy range. However, events which show increasing Fe/O cannot be explained within the framework of spectral breaks. Possible explanations include injection of remnant heavy ions from earlier impulsive events, hybrid Events consisting of a combination of flare-accelerated and shock-accelerated particles from a single solar event, and some new physical process in shock acceleration. We will report on efforts to distinguish these possible explanations.

  20. The streaming of 1.3 - 2.3 MeV cosmic-ray protons during periods between prompt solar particle events. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Marshall, F. E.

    1977-01-01

    The anisotropy of 1.3 to 2.3 MeV protons in interplanetary space was measured using the Caltech electron/isotope spectrometer aboard IMP-7 for 317 6 hour periods from 72/273 to 74/2. Periods dominated by prompt solar particle events are not included. The convective and diffusive anisotropies were determined from the observed anisotropy using concurrent solar wind speed measurements and observed energy spectra. The diffusive flow of particles was found to be typically toward the sun, indicating a positive radial gradient in the particle density. This anisotropy was inconsistent with previously proposed sources of low energy proton increases seen at 1 AU which involve continual solar acceleration. The typical properties of this new component of low-energy cosmic rays were determined for this period which is near solar minimum.

  1. GUVI observations of the airglow response to solar flares: Results from the CAWSES campaign period

    NASA Astrophysics Data System (ADS)

    Wolven, B. C.; Paxton, L. J.; Morrison, D.

    2006-05-01

    GUVI limb and disk observations of oxygen and nitrogen airglow emissions show strong variability during solar events; both the intensity and the altitude of peak limb emission vary in response to the brightened and hardened solar spectrum. We present the observed response, and compare it to model predictions generated using a flare-type solar input spectrum. We examine the difference in atmospheric response to consecutive flare events, owing to the modification of thermospheric density and composition by the initial flare and subsequent geomagnetic disturbances.

  2. Observation on internal waves propagation during Land breeze event in Northern Tyrrhenian coast

    NASA Astrophysics Data System (ADS)

    Martellucci, Riccardo; Pierattini, Alberto; Paladini de Mendoza, Francesco; Melchiorri, Cristiano; Piermattei, Viviana; Ciampa, Francesco; Marcelli, Marco

    2015-04-01

    Internal wave propagation and water column mixing phenomena play an important role in many marine ecosystem coastal process. In Northern Tyrrhenian coast the experimental proposed approach is aimed to identify these type of oscillation in presence of breeze circulation. Along the Tyrrhenian coast summer period climate conditions allow the generations of high frequency land-sea breeze events. This local circulation, land-sea breeze indeed, may generate significant modifications of the sea waters physical parameters. Thay often appear as internal gravity waves especially in presence of stratified water and stable thermocline. Since the whole investigated process evolves on diurnal scale and in the space of a few miles the sampling plan was operated with a series of oceanographic surveys at 40 meters depth with 20 minutes interval one from another between 5 a.m. and 11 a.m. and they were repeted during each summers between 2012 - 2014. Coupled with the acquisition of physical parameters current data were collected with 500 kHz ADCP every 20s, the resolution of vertical profiles of CTD matches the ADCP 1 meter magnitude vertical resolution. in order to investigate the water column layers dynamics behavior, Brunt-Vaisala and Richardson number were computed using the sampled physical parameters. Coastal surveys analysis highlights the presence of temperature oscillation in proximity of the thermocline and bottom layers; these oscillations have been observed during all measure surveys, when the land breeze was over. Indeed the land breeze tends to generate an offshore transport causing bottom layers to lift. At the same time solar radiation heating causes a sink of the surface layers which flatten the layers in proximity of the thermocline. Therefore the oscillations of temperature observed during the oceanographic surveys have to considered as internal waves, as during earlier studies conducted in the Tyrrhenian Sea has been observed.

  3. Oscillation Responses to an Extreme Weather Event from a Deep Moored Observing System

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Dimarco, S. F.; Stoessel, M. M.; Zhang, X.; Ingle, S.

    2011-12-01

    In June 2007 tropical Cyclone Gonu passed directly over an ocean observing system consisting of four, deep autonomous mooring stations along the 3000 m isobath in the northern Arabian Sea. Gonu was the largest cyclone known to have occurred in the Arabian Sea or to strike the Arabian Peninsula. The mooring system was designed by Lighthouse R & D Enterprises, Inc. and installed in cooperation with the Oman Ministry of Agriculture and Fisheries Wealth. The instruments on the moorings continuously recorded water velocities, temperature, conductivity, pressure, dissolved oxygen and turbidity at multiple depths and at hourly intervals during the storm. Near-inertial oscillations at all moorings from thermocline to seafloor are coincident with the arrival of Gonu. Sub-inertial oscillations with periods of 2-10 days are recorded at the post-storm relaxation stage of Gonu, primarily in the thermocline. These oscillations consist of warm, saline water masses, likely originating from the Persian Gulf. Prominent 12.7-day sub-inertial waves, measured at a station ~300 km offshore, are bottom-intensified and have characteristics of baroclinic, topographically-trapped waves. Theoretical results from a topographically-trapped wave model are in a good agreement with the observed 12.7-day waves. The wavelength of the 12.7-day waves is about 590 km calculated from the dispersion relationship. Further analysis suggests that a resonant standing wave is responsible for trapping the 12.7-day wave energy inside the Sea of Oman basin. The observational results reported here are the first measurements of deepwater responses to a tropical cyclone in the Sea of Oman/Arabian Sea. Our study demonstrates the utility of sustained monitoring for studying the impact of extreme weather events on the ocean.

  4. Biofilm formation and sanitizer resistance of Escherichia coli O157:H7 strains isolated from "high event period" meat contamination.

    PubMed

    Wang, Rong; Kalchayanand, Norasak; King, David A; Luedtke, Brandon E; Bosilevac, Joseph M; Arthur, Terrance M

    2014-11-01

    In the meat industry, a "high event period" (HEP) is defined as a time period during which commercial meat plants experience a higher than usual rate of Escherichia coli O157:H7 contamination. Genetic analysis indicated that within a HEP, most of the E. coli O157:H7 strains belong to a singular dominant strain type. This was in disagreement with the current beef contamination model stating that contamination occurs when incoming pathogen load on animal hides, which consists of diverse strain types of E. coli O157:H7, exceeds the intervention capacity. Thus, we hypothesize that the HEP contamination may be due to certain in-plant colonized E. coli O157:H7 strains that are better able to survive sanitization through biofilm formation. To test our hypothesis, a collection of 45 E. coli O157:H7 strains isolated from HEP beef contamination incidents and a panel of 47 E. coli O157:H7 strains of diverse genetic backgrounds were compared for biofilm formation and sanitizer resistance. Biofilm formation was tested on 96-well polystyrene plates for 1 to 6 days. Biofilm cell survival and recovery growth after sanitization were compared between the two strain collections using common sanitizers, including quaternary ammonium chloride, chlorine, and sodium chlorite. No difference in "early stage" biofilms was observed between the two strain collections after incubation at 22 to 25°C for 1 or 2 days. However, the HEP strains demonstrated significantly higher potency of "mature" biofilm formation after incubation for 4 to 6 days. Biofilms of the HEP strains also exhibited significantly stronger resistance to sanitization. These data suggest that biofilm formation and sanitization resistance could have a role in HEP beef contamination by E. coli O157:H7, which highlights the importance of proper and complete sanitization of food contact surfaces and food processing equipment in commercial meat plants. PMID:25364934

  5. Proxy records of Late Holocene climate events in the eastern United States: Medieval Warm Period and Little Ice Age

    NASA Astrophysics Data System (ADS)

    Willard, D. A.; Cronin, T. M.; Hayo, K. M.

    2006-12-01

    We are conducting a multiproxy, regional reconstruction of climate variability during the last two millennia including the Medieval Warm Period (MWP) and Little Ice Age (LIA) in eastern North America. Pollen, benthic foraminifers, ostracodes, and other proxies were analyzed from high-resolution sampling of continuous sedimentary records from lakes, wetlands, and estuaries in Florida, North Carolina, Chesapeake Bay, and Lake Champlain. These records document multi-decadal changes in vegetation, temperature, precipitation, and estuarine salinity across a latitudinal transect. During both the MWP and LIA, decreased precipitation altered plant community composition and distribution in the southeastern United States, and the LIA triggered threshold changes in vegetation that persisted until anthropogenic land-cover change overwhelmed the climate signature. In the mid-Atlantic region, progressively cooler and wetter late Holocene springs culminated in a cool, wet LIA; this trend correlates with observed oceanic changes. Trend analysis of the data suggest that inter-regional correlation of multi-decadal and centennial-scale Holocene climate events will be forthcoming.

  6. Conjugate observations of traveling convection vortices associated with transient events at the magnetopause

    NASA Astrophysics Data System (ADS)

    Kim, H.; Clauer, C. R.; Engebretson, M. J.; Matzka, J.; Sibeck, D. G.; Singer, H. J.; Stolle, C.; Weimer, D. R.; Xu, Z.

    2015-03-01

    Traveling convection vortices (TCVs) are generally produced by field-aligned currents (FACs) at high latitudes associated with transient changes of the magnetopause. This paper presents multipoint conjugate observations of transient events at the magnetopause measured in space and on the ground. The transient events showing radial fluctuation of the magnetopause in association with sudden increases in solar wind dynamic pressure were detected by both the Time History of Events and Macroscale Interactions during Substorms and the Geostationary Operational Environmental Satellite spacecraft. Geomagnetic signatures seen as TCVs in response to the transient events were observed by the ground magnetometer array in Greenland and Canada and their conjugate locations in Antarctica including recently developed Antarctic magnetometers, mostly located along the 40° magnetic meridian. This new conjugate network provides a unique opportunity to observe geomagnetic field signatures over a relatively large region in both hemispheres. This study focuses mainly on the spatial and temporal features of the TCVs in the conjugate hemispheres in relation to the transient events at the magnetopause. The TCV events are characterized by their single or twin vortex, of which the centers are located approximately at 72°-76° magnetic latitude, propagating either dawnward or duskward away from local noon. While interhemispheric conjugacy is expected with an assumption that TCV signatures are created by FACs directed in both hemispheres, our observations suggest that there might be more complex mechanisms contributing the asymmetrical features, perhaps due to field line mapping and/or conductivity differences.

  7. Strain Rate by Geodetic Observations Associated with Seismic Events in the SIRGAS-CON Network Region.

    NASA Astrophysics Data System (ADS)

    Marotta, G. S.; Franca, G.; Galera Monico, J. F.; Fuck, R. A.

    2014-12-01

    This research investigates surface strains related to seismic events and their relationship with pre- and post-seismic events in South American, Antarctica, Nazca, Cocos, North American and Caribbean plates , by analyzing the variation of estimated earth coordinates, for the period 2000-2014, supplied by a geodetic network called SIRGAS-CON. Based on data provided by the USGS for the same period, and after the Global Congruency test, we selected the events associated with unstable geodetic network points. The resulting strains were estimated based on the finite element method. It was possible to determine the strains along with the resulting guidelines for pre- and post-seismic, considering each region formed for analysis as a homogeneous solid body. Later, a multi-year solution of the network was estimated and used to estimate the strain rates of the earth surface from the changing directions of the velocity vectors of 332 geodetic points located in the South American plate and surround plates. The strain rate was determined and, using Euler vector computed, it was possible to estimate the convergence and accommodation rates to each plate. The results showed that contraction regions coincide with locations with most of the high magnitude seismic events. It suggest that major movements detected on the surface occur in regions with more heterogeneous geological structures and multiple rupture events; significant amounts of elastic strain can be accumulated on geological structures away from the plate boundary faults; and, behavior of contractions and extensions is similar to what has been found in seismological studies. Despite the association between seismic events and the strain of geodetic network, some events of high magnitude were excluded because it does not show the surface strain, which is located at great depths. It was confirmed that events of greater magnitude provide increased surface strain rate when compared with other similar depths.

  8. Consistent Observational and Numerical Modeling Support for Ice Sheet Forcing of DOI event 8

    NASA Astrophysics Data System (ADS)

    Lu, S.; Jackson, C.; Marchal, O.; Thompson, W.; Stocker, T.

    2008-12-01

    The Binge/Purge (B/P) hypothesis of abrupt climate change (MacAyeal, 1993a,b, Paleoceanography) suggests that an instability and periodic collapse of the Laurentide ice sheet is responsible for the observed abrupt warmings of Greenland (Dansgaard-Oeschger Interstadials or DOIs) through the influence of ice sheet meltwater on ocean circulation and its poleward heat transport. If the B/P hypothesis is correct, then one should be able to use the Greenland paleotemperature data and a climate model to infer changes in global sea level associated with the DOIs. The B/P hypothesis could then be tested by comparing the inferred sea level changes with independent reconstructions based on marine records (corals and sediments). We use stochastic inversion of a seasonal resolving climate model (Schmittner and Stocker, 1999, J. Climate), composed of a zonally averaged ocean model (Wright and Stocker, 1992, J. Geophys. Res.) coupled to an energy and moisture balance model of the atmosphere, to infer the changes in ice sheet meltwater required to explain the Greenland paleotemperature record from 39 ka to 34 ka which include DOIs 8, 7, and 6. We found a compelling consistency between modeled and reconstructed sea level changes for DOI 8 (a particularly long interstadial following Heinrich Event 4), which tends to support the B/P hypothesis. On the other hand, the large estimated uncertainties in the inversion solution and sea level reconstructions do not permit a firm test of the B/P hypothesis for DOIs 7 and 6.

  9. Observations of effects from magnetospheric cusp movement during a solar proton event

    SciTech Connect

    Brown, R.R.; Barcus, J.R.; Stauning, P.; Karas, R.H.

    1981-09-01

    The interplanetary magnetic field underwent a strong southward turning at the location of the ISEE 3 spacecraft, with B/sub z/ (in satellite coordinates) decreasing from +15..gamma.. to -15..gamma.. in the interval from 1540 UT to 1600 UT on August, 1979. Solar wind speed measurements at the spacecraft indicated that the southward turning of the IMF should have reached the front of the magnetosphere around 1625 UT. At that time the solar proton event of August 18, 1979, was still in progress. Observations from balloon-borne and ground-based instrumentation in Greenland in that period, around 1415 magnetic local time, showed an expansion of the polar cap, the cusp moving southward by at least 5/sup 0/ in latitude in 15 min, starting around 1635 UT. From changes in the energetic photon spectrum at ballon altitude, it is shown that the proton cutoff energy at Sondre Stromfjord, Greenland, prior to the cusp motion was in the range 6--10 MeV.

  10. Periodic variations of oxygen EUV dayglow in the upper atmosphere of Venus: Hisaki/EXCEED observations

    NASA Astrophysics Data System (ADS)

    Masunaga, K.; Seki, K.; Terada, N.; Tsuchiya, F.; Kimura, T.; Yoshioka, K.; Murakami, G.; Yamazaki, A.; Kagitani, M.; Tao, C.; Fedorov, A.; Futaana, Y.; Zhang, T. L.; Shiota, D.; Leblanc, F.; Chaufray, J.-Y.; Yoshikawa, I.

    2015-12-01

    Using the Extreme Ultraviolet Spectroscope for Exospheric Dynamics (EXCEED) aboard Hisaki and the Solar Extreme Ultraviolet Monitor on the Solar and Heliospheric Observatory, we investigate variations of the extreme ultraviolet (EUV) dayglow brightness for OII 83.4 nm, OI 130.4 nm, and OI 135.6 nm in the Venusian upper atmosphere observed in March-April (period 1), April-May (period 2), and June-July (period 3) in 2014. The result shows that characteristic periodicities exist in the dayglow variations other than the ~27 day solar rotational effect of the solar EUV flux: 1.8, 2.8, 3.1, 4.5, and 9.9 day in period 1; 1.1 day in period 2; and 1.0 and 11 day in period 3. Many of these periodicities are consistent with previous observations and theory. We suggest these periodicities are related to density oscillations of oxygen atoms or photoelectrons in the thermosphere. The cause of these periodicities is still uncertain, but planetary-scale waves and/or gravity waves propagating from the middle atmosphere, and/or minor periodic variations of the solar EUV radiation flux may play a role. Effects of the solar wind parameters (velocity, dynamic pressure, and interplanetary magnetic field's intensity) on the dayglow variations are also investigated using the Analyser of Space Plasma and Energetic Atoms (ASPERA-4) and magnetometer aboard Venus Express. Although clear correlation with the dayglow variations is not found, their minor periodicities are similar to the dayglow periodicities. Contribution of the solar wind to the dayglow remains still unknown, but the solar wind parameters might affect the dayglow variations.

  11. Observing a Chemically and/or Climatically Important Volcano: Facilitating Rapid Response to an Unanticipated yet Inevitable Event

    NASA Astrophysics Data System (ADS)

    Kaye, J. A.

    2015-12-01

    A large volcanic event has the potential to influence the chemical and/or physical state of the Earth's atmosphere in a significant way. In particular, changes in the trace constituent and/or particulate composition of the stratosphere, as well as the temperature distribution of the troposphere and stratosphere can both take place (and persist over a period of time), as has been observed in several eruptions in recent years (e.g., the Mount Pinatubo eruption in 1991). Characterizing the impacts of these eruptions and predicting their impacts on the evolution of the atmosphere requires observations of gas and particle distributions over time period from as soon after eruption as possible to the longer time period over which the Earth system is affected. This characterization may make use of observation capabilities from ongoing surface-based and existing satellite-based observing systems, and can also benefit significantly from focused airborne campaigns that make use of both in situ and remote sensing instrumentation. This presentation will review the relevant surface- and space-based observing capability operated by NASA in the broader context of the global observing capabilities of the international community, and and will discuss potential approaches to airborne campaigns (platforms, sensors, systems, logistical consideration) that would provide the data most useful for both characterization and forecasting of both the chemical and climatic forcing and impacts associated with the eruption.

  12. Observation and Interpretation of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Event

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.; Leske, R. A.; Stone, E. C.; Barghouty, A. F.; Shih, A. Y.; von Rosenvinge, T. T.; Labrador, A. W.; Cohen, C. M. S.; Cummings, A. C.; Cummings, A. C.

    2009-01-01

    We report the first observations of energetic neutral atoms (ENAs) from a solar flare/coronal mass ejection event. The observations were made during the December 5, 2006 X9 solar flare, located at E79, by the Low Energy Telescopes (LETs) on the STEREO A and B spacecraft. Within 1-2 hours of the flare onset, both LETs observed a sudden burst of 1.6 to 15 MeV protons arriving hours before the onset of the main solar energetic particle (SEP) event at Earth. More than 70% of these particles arrived from a longitude within +-10 degrees of the Sun. The derived emission profile at the Sun lasted for more than an hour and had a profile remarkably similar to the GOES soft X-ray profile. The observed arrival directions and energy spectrum argue strongly that the particle events <5 MeV were due to energetic neutral hydrogen atoms that were stripped of their electrons upon entering the LET sensor. To our knowledge, this is the first reported observation of ENA emission from a solar flare/coronal mass ejection. We discuss possible origins for the production of ENAs in solar events, including charge-transfer reactions involving both flare and shock-accelerated protons. Assuming isotropic emission, we find that 2 x 10E28 ENAs escaped from the Sun in the upper hemisphere. Based on the 2.2 MeV gamma-ray emission observed by RHESSI in this event, and using measured and theoretical cross sections, we estimate that 3 x 10E31 ENAs with 1.8 - 5 MeV could be produced by protons accelerated in the flare. CME-driven shock acceleration is also a possible ENA source, but unfortunately there were no CME observations available from this event. Taking into account ENA losses, we conclude that the observed ENAs were most likely produced in the high corona at heliocentric distances 1.6 solar radii.

  13. Video and photometric observations of a sprite in coincidence with a meteor-triggered jet event

    SciTech Connect

    Suszcynsky, D. M.; Strabley, R.; Roussel-Dupre, R.; Symbalisty, E. M. D.; Armstrong, R. A.; Lyons, W. A.; Taylor, M.

    1999-12-27

    Video and photometric observations of a meteor-triggered ''jet'' event in association with the occurrence of a sprite were collected during the SPRITES '98 campaign. The event raises interest in the question of possible meteoric triggering of upper atmospheric transients as originally suggested by Muller [1995]. The event consisted of three stages: (1) the observation of a moderately bright meteor, (2) the development of a sprite in the immediate vicinity of the meteor as the meteor reached no lower than {approx}70 km altitude, and (3) a slower-forming jet of luminosity that appeared during the late stages of the sprite and propagated back up the ionization trail of the meteor. The event is analyzed in terms of its geometry, its relevance to the meteor, and the implications to existing theories for sprite formation. (c) 1999 American Geophysical Union.

  14. BARREL observations of a solar energetic electron and solar energetic proton event

    NASA Astrophysics Data System (ADS)

    Halford, A. J.; McGregor, S. L.; Hudson, M. K.; Millan, R. M.; Kress, B. T.

    2016-05-01

    During the second Balloon Array for Radiation Belt Relativistic Electron Losses (BARREL) campaign two solar energetic proton (SEP) events were observed. Although BARREL was designed to observe X-rays created during electron precipitation events, it is sensitive to X-rays from other sources. The gamma lines produced when energetic protons hit the upper atmosphere are used in this paper to study SEP events. During the second SEP event starting on 7 January 2014 and lasting ˜3 days, which also had a solar energetic electron (SEE) event occurring simultaneously, BARREL had six payloads afloat spanning all magnetic local time (MLT) sectors and L values. Three payloads were in a tight array (˜2 h in MLT and ˜2 ΔL) inside the inner magnetosphere and at times conjugate in both L and MLT with the Van Allen Probes (approximately once per day). The other three payloads mapped to higher L values with one payload on open field lines for the entire event, while the other two appear to be crossing from open to closed field lines. Using the observations of the SEE and SEP events, we are able to map the open-closed boundary. Halford et al. (2015) demonstrated how BARREL can monitor electron precipitation following an interplanetary shock created by a coronal mass ejection (ICME-shock) arrival at Earth, while in this study we look at the SEP event precursor to the arrival of the ICME-Shock in our cradle-to-grave view: from flare, to SEE and SEP events, to radiation belt electron precipitation.

  15. Periodic Crossings of Saturn's Current Sheet by Cassini: Observations and Modeling

    NASA Astrophysics Data System (ADS)

    Khurana, K. K.; Arridge, C. S.; Dougherty, M. K.; Russell, C. T.

    2006-12-01

    Cassini continues to provide exciting new observations from the magnetosphere of Saturn. These observations are helping us understand the structure and dynamics of this rotationally dominant magnetosphere. One of the puzzling observations from the latest magnetotail passes is the occurrence of periodic current sheet crossings in a magnetosphere known for its almost axis-symmetric magnetic field. In these crossings, the radial and azimuthal components of the magnetic field reverse sign twice during a spin period of Saturn in a manner similar to the dipole tilt induced motions of the Jovian current sheet. As the dipole tilt of Saturn's magnetic field is less than 0.2 degree, it is not clear how the current sheet can flap up and down over the spacecraft when it is located quite far from the nominal location of the current sheet. In this presentation, we will examine all of the data so far collected by Cassini to catalogue all of the periodic current sheet crossings in the data. We will examine parameters like the radial distance, latitude, longitude and local time of the spacecraft to understand under what conditions the current sheet crossings are observed. We comment on the relationship between these periodic current sheet crossings to periodicities in the quasi- dipolar region of the magnetosphere. Finally, we will explore models of Saturn's current sheet that can explain the periodicities of the observed magnetic field.

  16. Observation of Long Ionospheric Recoveries from Lightning-induced Electron Precipitation Events

    NASA Astrophysics Data System (ADS)

    Mohammadpour Salut, M.; Cohen, M.

    2015-12-01

    Lightning strokes induces lower ionospheric nighttime disturbances which can be detected through Very Low Frequency (VLF) remote sensing via at least two means: (1) direct heating and ionization, known as an Early event, and (2) triggered precipitation of energetic electrons from the radiation belts, known as Lightning-induced Electron Precipitation (LEP). For each, the ionospheric recover time is typically a few minutes or less. A small class of Early events have been identified as having unusually long ionospheric recoveries (10s of minutes), with the underlying mechanism still in question. Our study shows for the first time that some LEP events also demonstrate unusually long recovery. The VLF events were detected by visual inspection of the recorded data in both the North-South and East-West magnetic fields. Data from the National Lightning Detection Network (NLDN) are used to determine the location and peak current of the lightning responsible for each lightning-associated VLF perturbation. LEP or Early VLF events are determined by measuring the time delay between the causative lightning discharges and the onset of all lightning-associated perturbations. LEP events typically possess an onset delay greater than ~ 200 msec following the causative lightning discharges, while the onset of Early VLF events is time-aligned (<20 msec) with the lightning return stroke. Nonducted LEP events are distinguished from ducted events based on the location of the causative lightning relative to the precipitation region. From 15 March to 20 April and 15 October to 15 November 2011, a total of 385 LEP events observed at Indiana, Montana, Colorado and Oklahoma VLF sites, on the NAA, NLK and NML transmitter signals. 46 of these events exhibited a long recovery. It has been found that the occurrence rate of ducted long recovery LEP events is higher than nonducted. Of the 46 long recovery LEP events, 33 events were induced by ducted whistlers, and 13 events were associated with

  17. Observations and Light Curve Solutions of Four Ultrashort-Period Binaries

    NASA Astrophysics Data System (ADS)

    Kjurkchieva, D.; Popov, V.; Vasileva, D.; Petrov, N.

    2016-03-01

    The paper presents light curve solutions of our observations of four new ultrashort-period eclipsing binaries with MS components. Two of them have periods almost at the upper limit (0.22 days) of the ultrashort-period binaries, while the periods of around 0.18 days of CSS J171508.5+350658 and CSS J214633.8+120016 are amongst the shortest known orbital periods. CSS J171410.0+445850, CSS J214633.8+120016 and CSS J224326.0+154532 are overcontact binaries with fillout factors around 0.25 while CSS J171508.5+350658 is a semidetached system. The two targets with shortest periods consist of M dwarfs.

  18. Observations and Light Curve Solutions of Four Ultrashort-Period Binaries

    NASA Astrophysics Data System (ADS)

    Kjurkchieva, D.; Popov, V.; Vasileva, D.; Petrov, N.

    2016-06-01

    The paper presents light curve solutions of our observations of four new ultrashort-period eclipsing binaries with MS components. Two of them have periods almost at the upper limit (0.22 days) of the ultrashort-period binaries, while the periods of around 0.18 days of CSS J171508.5+350658 and CSS J214633.8+120016 are amongst the shortest known orbital periods. CSS J171410.0+445850, CSS J214633.8+120016 and CSS J224326.0+154532 are overcontact binaries with fillout factors around 0.25 while CSS J171508.5+350658 is a semidetached system. The two targets with shortest periods consist of M dwarfs.

  19. Flux Transfer Event in the Subsolar Region and Near the Cusp: Simultaneous Polar and Cluster Observations

    NASA Technical Reports Server (NTRS)

    Le, G.; Zheng, Y.; Russell, C. T.; Pfaff, R. F.; Slavin, J. A.; Lin, N.; Mozer, F.; Parks, G.; Petrinec, S. M.; Lucek, e. A.; Reme, Henri

    2005-01-01

    The phenomenon called flux transfer events (FTEs) is widely accepted as the manifestation of time-dependent reconnection. In this paper, we present an observational evidence of a flux transfer event observed simultaneously at low-latitude by Polar and high-latitude by Cluster. This event occurred on March 21, 2002, when both Cluster and Polar were located near the local noon but with large latitudinal distance. Cluster was moving outbound from polar cusp to the magnetosheath, and Polar was in the magnetosheath near the equatorial magnetopause. The observations show that a flux transfer event was formed between the equator and the northern cusp. Polar and Cluster observed the FTE's two open flux tubes: Polar saw the southward moving flux tube near the equator; and Cluster the , northward moving flux tube at high latitude. Unlike low-latitude FTEs, the high-latitude FTE did not exhibit the characteristic bi-polar BN signature. But the plasma data clearly showed its open flux tube configuration. Enhanced electric field fluctuations were observed within the FTE core, both at low- and high-attitudes. This event provides us a unique opportunity to understand high-latitude FTE signatures and the nature of time-varying reconnection.

  20. Intense Particulate Pollution Events Observed with Lidar over the Paris Megalopolis

    NASA Astrophysics Data System (ADS)

    Chazette, Patrick; Royer, Philippe

    2016-06-01

    The great particulate pollution event that affected the Paris Megalopolis in March 2014 was due to long-range transport from the northern-northeastern Europe. Although this phenomenon has appeared as exceptional in the media, this is not an exception and similar events have already been observed by lidar measurements. Here we will briefly describe and illustrate the origin of this intense pollution obviously harmful to health.

  1. Observation of events with an energetic forward neutron in deep inelastic scattering at HERA

    NASA Astrophysics Data System (ADS)

    Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Okrasinski, J. R.; Repond, J.; Stanek, R.; Talaga, R. L.; Zhang, H.; Mattingly, M. C. K.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Polini, A.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Amelung, C.; Bornheim, A.; Crittenden, J.; Deffner, R.; Doeker, T.; Eckert, M.; Feld, L.; Frey, A.; Geerts, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mengel, S.; Paul, E.; Pfeiffer, M.; Rembser, Ch.; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Cottingham, W. N.; Dyce, N.; Foster, B.; George, S.; Hayes, M. E.; Heath, G. P.; Heath, H. F.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Yoshida, R.; Arneodo, M.; Ayad, R.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Parsons, J. A.; Titz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Jakubowski, Z.; Przybycień, M. B.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Duliński, Z.; Kotański, A.; Abbiendi, G.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Cases, G.; Deppe, O.; Desler, K.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Haas, T.; Hain, W.; Hasell, D.; Heßling, H.; Iga, Y.; Johnson, K. F.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Kötz, U.; Kowalski, H.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mainusch, J.; Mańczak, O.; Milewski, J.; Monteiro, T.; Ng, J. S. T.; Notz, D.; Ohrenberg, K.; Poitrzkowski, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Surrow, B.; Voß, T.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Grabosch, H. J.; Kharchilava, A.; Mari, S. M.; Meyer, A.; Schlenstedt, S.; Wulff, N.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; De Pasquale, S.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Trefzger, T.; Wölfle, S.; Bromley, J. T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Saxon, D. H.; Sinclair, L. E.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Sinkus, R.; Wick, K.; Burow, B. D.; Hagge, L.; Lohrmann, E.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Brümmer, N.; Butterworth, I.; Harris, V. L.; Howell, G.; Hung, B. H. Y.; Lamberti, L.; Long, K. R.; Miller, D. B.; Pavel, N.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Whitfield, A. F.; Mallik, U.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; An, S. H.; Cho, G. H.; Ko, B. J.; Lee, S. B.; Nam, S. W.; Park, H. S.; Park, S. K.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Fernandez, J. P.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martinez, M.; del Peso, J.; Puga, J.; Terron, J.; de Trocóniz, J. F.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Ullmann, R.; Zacek, G.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Yu. A.; Kobrin, V. D.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Botje, M.; Chlebana, F.; Engelen, J.; de Kamps, M.; Kooijman, P.; Kruse, A.; van Sighem, A.; Tiecke, H.; Verkerke, W.; Vossebeld, J.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Li, C.; Ling, T. Y.; Nylander, P.; Park, I. H.; Romanowski, T. A.; Bailey, D. S.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Lindemann, L.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Wilson, F. F.; Yip, T.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Zuin, F.; Bulmahn, J.; Feild, R. G.; Oh, B. Y.; Whitmore, J. J.; D'Agostini, G.; Marini, G.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Barberis, E.; Dubbs, T.; Heusch, C.; Van Hook, M.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Biltzinger, J.; Seifert, R. J.; Schwarzer, O.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Levy, A.; Fleck, J. I.; Inuzuka, M.; Ishii, T.; Kuze, M.; Mine, S.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Umemori, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Matsushita, T.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Benard, F.; Brkic, M.; Fagerstroem, C.-P.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sampson, C. R.; Simmons, D.; Teuscher, R. J.; Butterworth, J. M.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Sutton, M. R.; Lu, B.; Mo, L. W.; Bogusz, W.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Coldewey, C.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Revel, D.; Zer-Zion, D.; Badgett, W. F.; Breitweg, J.; Chapin, D.; Cross, R.; Dasu, S.; Foudas, C.; Loveless, R. J.; Mattingly, S.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Bhadra, S.; Cardy, M. L.; Fagerstroem, C.-P.; Frisken, W. R.; Furutani, K. M.; Khakzad, M.; Murray, W. N.; Schmidke, W. B.; ZEUS Collaboration

    1996-02-01

    In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q2 in the range 3 · 10 -4 < xBJ < 6 · 10 -3 and 10 < Q2 < 100 GeV 2.

  2. Source regions of long-period pulsation events in electron precipitation and magnetic fields at South Pole Station

    SciTech Connect

    Paquette, J.A.; Matthews, D.L.; Rosenberg, T.J.; Lanzerotti, L.J.; Inan, U.S.

    1994-03-01

    Pulsation events with long (100-1000 s) periods with a consistent frequency in both particle precipitation and surface geomagnetic field variations have been reported in the past from measurements made at various geomagnetic latitudes. An examination of broad beam riometer and magnetometer data from South Pole Station for the interval from 1982 to 1989 revealed nearly 200 such events. The onset times of these events were determined. This mechanism ascribes the occurrence of correlated magnetic and precipitation pulsations to ULF modulation of equatorial VLF wave-particle interactions. For this reason, VLF data from South Pole Station were also examined. Taking into consideration the ULF wave and particle transit times from an interaction region near the magnetic equator to the ground leads to an expectation that the onset of pulsations in the magnetometer data will lag the onset of pulsations in the riometer data by several minutes. This disparity in onset times, together with modulation of VLF emissions in the 0.5-1 kHz band, serves as an important indicator of whether or not an event can be explained by the above-cited theory. While about a third of the events fit the prediction of Coroniti and Kennel, another third do not. In these events, the onset of magnetic and precipitation pulsations is nearly simultaneous, and possible alternative generation mechanisms are explored. In the remaining third of the events, magnetic pulsations begin substantially earlier than precipitation pulsations. Events of this type appear at first to be inexplicable in terms of any transit time argument. However, data from the imaging riometer at South Pole Station indicate that this third class of events is probably not physically distinct from the first two but is the result of the differing areas to which the riometer and magnetometer are sensitive and can be accounted for by considering the effects of transverse motion of a persistent precipitation region. 24 refs., 13 rigs.

  3. High-cadence observations of spicular-type events and their wave-signatures

    NASA Astrophysics Data System (ADS)

    Shetye, Juie

    2016-05-01

    We present, a statistical study of spectral images, taken from the CRISP instrument at the Swedish 1-m Solar Telescope in H-alpha 656.28 nm of fast spicules with Doppler velocities in the range of -41km/s to +41 km/s. Remarkably, many of these spicules display apparent velocities above 500 km/s, very short lifetimes of up to 20 s combined with width or thickness of 100 km and apparent lengths of around 3500 km. Here we present, the other spectral properties of these events in the H-alpha line scan. Most features showed signature in multiple line position as we scan along the line scan. In around 89 % of the cases, there is temporal offset by 3.7 s to 5 s between the red-wing and blue-wing signatures. Another result is that 25% of cases are repetitive i.e. appear at the same location but they are not co-temporal or necessarily periodic in nature. Putting all the evidence together, we interpret the observations as mass motions (of flux tubes) that appear in the field-of-view of CRISP’s 0.0060 nm filters in the line of sight, along their projection as we scan. Further we observed transverse motion associated with these structures, which in some cases could be related to high-frequency kink-waves. We describe some cases showing this motion and the energies associated with them. The current work presented already tests the limits of current telescopes in terms of the temporal and spatial resolution. DKIST VTF instrument, having 3 times more spatial resolution than CRISP and much higher temporal resolution, we can being to understand the nature of such fine-scale transient phenomena in greater details.

  4. Solar wind plasma periodicities observed at 1 AU by IMP 8

    NASA Technical Reports Server (NTRS)

    Paularena, K. I.; Szabo, A.; Lazarus, A. J.

    1995-01-01

    The IMP 8 spacecraft has been in Earth orbit since 1973, gathering plasma data over one complete 22-year solar cycle. These data are being examined to look for periodicities at time scales ranging from several hours to the entire span of the data set. A 1.3-year periodicity in the radial speed observed by IMP 8 and Voyager 2 has already been reported for the years from 1987 to 1993. The periodogram method, useful for unevenly sampled data such as the IMP 8 plasma data, has been used to search for other periods. It is interesting to note that the 13-year period is not present in the out-of-the-ecliptic component of the velocity (Vz), although a 1-year period is very obvious both visually and on the periodogram. Both components show a very strong peak associated with the 11-year solar cycle variation. This work will be extended to the thermal speed (a measure of the wind's temperature) and density, although the frequent correlations between these parameters and the velocity are expected to cause similar results. Additionally, the fine resolution data will be examined for shorter time periods than are visible using the hourly average data which are appropriate for longer periods. A comparison with periods observed at other spacecraft may also be made.

  5. Approaching Solar Maximum 24 with Stereo-Multipoint Observations of Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Dresing, N.; Cohen, C. M. S.; Gomez-Herrero, R.; Heber, B.; Klassen, A.; Leske, R. A.; Mason, G. M.; Mewaldt, R. A.; von Rosenvinge, T. T.

    2014-01-01

    Since the beginning of the Solar Terrestrial Relations Observatory (STEREO) mission at the end of 2006, the two spacecraft have now separated by more than 130? degrees from the Earth. A 360-degree view of the Sun has been possible since February 2011, providing multipoint in situ and remote sensing observations of unprecedented quality. Combining STEREO observations with near-Earth measurements allows the study of solar energetic particle (SEP) events over a wide longitudinal range with minimal radial gradient effects. This contribution provides an overview of recent results obtained by the STEREO/IMPACT team in combination with observations by the ACE and SOHO spacecraft. We focus especially on multi-spacecraft investigations of SEP events. The large longitudinal spread of electron and 3He-rich events as well as unusual anisotropies will be presented and discussed.

  6. Observations of systematic temporal evolution in elemental composition during gradual solar energetic particle events

    NASA Astrophysics Data System (ADS)

    Tylka, Allan J.; Reames, Donald V.; Ng, Chee K.

    The WIND/EPACT experiment offers a ˜100 fold increase in collecting power over instruments flown in previous solar cycles, thus allowing unprecedented detailed studies of temporal evolution in gradual solar energetic particle (SEP) events. We present hourly WIND/EPACT observations at ˜2-10 MeV/nuc from the 20 April 1998 and 26 August 1998 SEP events. These observations show striking patterns in elemental composition which evolve in a systematic fashion throughout the events' several-day durations. These data, combined with theoretical modeling in a companion Letter [Ng et al. 1999], suggest that a dynamic Alfvén wave field, generated primarily by streaming energetic protons, is responsible for the complex behavior which is observed.

  7. Loa loa microfilarial periodicity in ivermectin-treated patients: comparison between those developing and those free of serious adverse events.

    PubMed

    Kamgno, Joseph; Pion, Sébastien D; Mackenzie, Charles D; Thylefors, Björn; Boussinesq, Michel

    2009-12-01

    The main risk factor of post-ivermectin serious adverse events (SAEs) is the presence of a high Loa loa microfilaremia. However, the majority of patients with such high loads do not develop SAEs, suggesting that co-factors may be involved. An infection with simian Loa parasites, whose microfilariae show a nocturnal periodicity, might be such a co-factor. The periodicity of Loa microfilariae was compared, using cosinor methodology, in 4 patients who had developed a post-ivermectin neurologic SAE, 4 patients who had experienced a non-neurologic SAE, and 14 control individuals. The periodicity was similar in all three groups, with a peak of microfilaremia occurring between 12:30 and 2:00 PM. The results of this study, which for the first time characterizes the periodicity of Loa microfilariae mathematically, suggest that post-ivermectin SAEs are not related to an infection with a Loa simian strain. PMID:19996437

  8. Field and video observations of morphological change under consecutive storm events (ECORS Truc Vert'08)

    NASA Astrophysics Data System (ADS)

    Senechal, Nadia; Rejas, Antoine; Coco, Giovanni; Bryan, Karin; Macmahan, Jamie; Capo, Sylvain; Parisot, Jean-Paul

    2010-05-01

    Morphological changes occurring over short and long temporal scales remain a major challenge in nearshore research. Because of the expected rise in mean sea level and storminess increase, beach response to changing wave conditions is of key interest to coastal managers. Current numerical models of beach change have limited predictive skills and the need to collect field observations to gain insight on processes determining beach response is widely acknowledged. A field experiment was performed in 2008 at Truc Vert, a macrotidal beach on the southern part of the French Atlantic coast. The experiment involved scientists from 6 countries (for a total of 16 institutions) and measurements of waves, currents, sediment transport and morphological changes were collected for a period of 6 weeks. We here focus on the analysis of morphological changes that occurred on the beachface and intertidal area during the experiment. Bed levels over an area spanning about 800 m in the alongshore direction were monitored daily using a DGPS system mounted on an ATV while the lower part of the swash zone was surveyed on foot. Video observations were collected using a 2-camera system deployed on a tower on top of the dunes and provided observations of shoreline and underwater sandbar position. During the field experiment, the beach experienced 2 major storms (offshore significant wave height above 5 m) as well as a period of time when offshore wave height was constantly around or above 3 m (average annual wave height at this site is 1.36 m) for a period of 10 days. Morphological response to storms and subsequent recovery patterns varied in both the alongshore and cross-shore direction and appear to be strongly influenced by the angle of wave approach and pre-existing morphological conditions of the beachface and the intertidal sandbar. Our analysis shows that the response of the upper intertidal part of the beach was very different between the three storms. In particular, whereas the first

  9. The spatial extent of radial magnetic pulsation events observed in the dayside near synchronous orbit

    SciTech Connect

    Engebretson, M.J.; Murr, D.L.; Erickson, K.N. ); Strangeway, R.J. ); Klumpar, D.M.; Fuselier, S.A. ); Zanetti, L.J.; Potemra, T.A. )

    1992-09-01

    The authors have used simultaneous observations from the AMPTE CCE satellite, in an elliptical orbit with apogee at 8.8 R[sub E], and GOES 5 and GOES 6, in a geostationary orbit at 6.6R[sub E], to investigate the radial and longitudinal extent of magnetic pulsation events with predominantly radial polarization. Twenty-one events were selected. Local time of the observed events ranged from 0900 to 1900 MLT, but the apparent longitudinal extent of the oscillation region varied considerably from event to event, ranging from the minimum resolution of 1.5 hours MLT to 8 hours MLT. Plasma wave data from AMPTE CCE indicated the waves occurred in regions of density characteristic of the outer plasmasphere ([approximately]10cm[sup [minus]3]) and quite far outside the L shell region where densities reached 400cm[sup [minus]3]. These events occurred during magnetically quiet times usually after magnetic storms;interplanetary magnetic field data, when available, indicated an either roughly radial or northward orientation during the events. Wave onset often (but not always) occurred within one hour after sharp drops in the AE index to values of 100 or below. There was no apparent correlation of wave onset or amplitude with plasma beta, which ranged from 0.23 to 1.09 during the nine events presented here. The frequent observation of the simultaneous onset of waves at different local times with considerably different frequencies reinforces the belief that the onset of these pulsations is determined by an instability that covers some longitudinal extent but that the frequencies are determined by local Alfven resonance conditions, not by the bandwidth of an external source. The data suggest that local plasma density increases associated with plasmaspheric refilling are the immediate cause of local instabilities leading to wave onset.

  10. Probability Estimates of Solar Particle Event Doses During a Period of Low Sunspot Number for Thinly-Shielded Spacecraft and Short Duration Missions

    NASA Technical Reports Server (NTRS)

    Atwell, William; Tylka, Allan J.; Dietrich, William; Rojdev, Kristina; Matzkind, Courtney

    2016-01-01

    In an earlier paper (Atwell, et al., 2015), we investigated solar particle event (SPE) radiation exposures (absorbed dose) to small, thinly-shielded spacecraft during a period when the sunspot number (SSN) was less than 30. These SPEs contain Ground Level Events (GLE), sub-GLEs, and sub-sub-GLEs (Tylka and Dietrich, 2009, Tylka and Dietrich, 2008, and Atwell, et al., 2008). GLEs are extremely energetic solar particle events having proton energies extending into the several GeV range and producing secondary particles in the atmosphere, mostly neutrons, observed with ground station neutron monitors. Sub-GLE events are less energetic, extending into the several hundred MeV range, but do not produce secondary atmospheric particles. Sub-sub GLEs are even less energetic with an observable increase in protons at energies greater than 30 MeV, but no observable proton flux above 300 MeV. In this paper, we consider those SPEs that occurred during 1973-2010 when the SSN was greater than 30 but less than 50. In addition, we provide probability estimates of absorbed dose based on mission duration with a 95% confidence level (CL). We also discuss the implications of these data and provide some recommendations that may be useful to spacecraft designers of these smaller spacecraft.

  11. Observing deeper magmatic cycles from shallow seismic and infrasonic events, Villarrica Volcano, Chile

    NASA Astrophysics Data System (ADS)

    Richardson, J. P.; Waite, G. P.

    2013-12-01

    Villarrica volcano is presently an open-vent volcano, characterized by continuous but variable passive degassing. This persistent degassing produces both infrasonic and seismic tremor. Minor strombolian style eruptions at the surface of the lava lake, which rarely deposit material outside of the crater rim, produce both seismic long-period events and infrasonic pulses. During three campaigns between 2010 and 2012, we investigated the activity using temporary seismic networks with collocated infrasound sensors. These sensors were deployed from within the crater to greater than ten kilometers distance. Using our station distribution, we created a matched filter to identify events similar to a template event associated with a strombolian eruption. Although the bubble bursting events were found to be small, we found that they were nearly identical in seismic signature. By stacking these events, we were able to perform an inversion of the event as seen by our network, and found that the best-fit was a nearly horizontal, E-W directed force within the crater. We interpret this mechanism as the response of the lava lake to outgassing, where lava sloshes to fill the void left by the escaping gas, producing seismic signals as the lava drags along the floor and sides of the crater. Using the catalog created by the matched filter for the seismic long-period events, we also compared the response of the collocated infrasound sensors to the bubble burst events. We found the signals recorded at the infrasound sensors to be coherent when aligned according to the seismic catalog, but the seismic-acoustic delay time was found to systematically vary throughout the deployment. We also calculated the volcano acoustic-seismic ratio (VASR) using our catalog of seismic and infrasonic events. We found that shorter seismic-acoustic delays were well correlated with a higher VASR, corresponding to shallower lava lake levels. The lava lake high stands also correlated with higher seismic and

  12. Observation of an optical event horizon in a silicon-on-insulator photonic wire waveguide.

    PubMed

    Ciret, Charles; Leo, François; Kuyken, Bart; Roelkens, Gunther; Gorza, Simon-Pierre

    2016-01-11

    We report on the first experimental observation of an optical analogue of an event horizon in integrated nanophotonic waveguides, through the reflection of a continuous wave on an intense pulse. The experiment is performed in a dispersion-engineered silicon-on-insulator waveguide. In this medium, solitons do not suffer from Raman induced self-frequency shift as in silica fibers, a feature that is interesting for potential applications of optical event horizons. As shown by simulations, this also allows the observation of multiple reflections at the same time on fundamental solitons ejected by soliton fission. PMID:26832243

  13. Investigating Visitors' and Facilitators' Experiences at International Observe the Moon Night Events

    NASA Astrophysics Data System (ADS)

    Wenger, Matthew; Buxner, Sanlyn; Jones, Andrea; Hsu, Brooke; Shaner, Andy; Bleacher, Lora; Day, Brian

    2014-11-01

    International Observe the Moon Night (InOMN) is an annual event where people around the world are encouraged to look up at the Moon and share in the excitement of lunar science and exploration. The Lunar Reconnaissance Orbiter (LRO) leads the coordination of InOMN, with support from partner NASA mission and institution teams, including the Solar System Exploration Research Virtual Institute (SSERVI) and the Lunar Atmosphere and Dust Environment Explorer (LADEE). In 2013, InOMN was held on October 12th and a total of 521 unique events were registered on the InOMN website from around the world. These 521 events were held in 56 different countries, 46% of which were events in the United States. The InOMN evaluation was designed to characterize the overall participation of sites and visitors, characterize the types of visitors who attended, understand visitors’ intentions for attending an InOMN event, and understand how can facilitators be better supported for future events. Data was collected from event facilitators before and after the event and from visitors at the event. The follow-up facilitator survey was designed to understand to what extent the InOMN hosts were aware of the LRO mission and more generally understand how to support InOMN events in the future. Thirty-eight visitor surveys were collected and 186 facilitators completed follow-up surveys to give us an insight into both visitors’ and facilitators’ experiences.Most of the visitors (67%) who responded to the surveys were new to InOMN and reported that they had not attended a previous InOMN event. As with the 2012 events, the findings from 2013 continue to support the findings that InOMN events are social experiences and that most visitors attend with other people. The majority of visitors attended in family groups (72%), and another 20% attended with groups of other individuals (friends or other groups) with only 7% attending by themselves. A majority of survey respondents were aware of the LRO

  14. Characteristics of the extreme events observed in the Kerr-lens mode-locked Ti:sapphire laser

    NASA Astrophysics Data System (ADS)

    Hnilo, Alejandro A.; Kovalsky, Marcelo G.; Agüero, Mónica B.; Tredicce, Jorge R.

    2015-01-01

    Kerr-lens mode-locked Ti:sapphire lasers are known to display three coexistent modes of operation: continuous wave, transform limited pulses (P1), and positive chirped pulses (P2). Extreme events (sometimes also called optical rogue waves), in the form of pulses of high energy appearing much often than in a Gaussian distribution, are observed in the chaotic regime of the P2 mode, but not of P1. The extreme events in P2 appear unpredictably, but their separation (measured in number of round trips) is a simple combination of the numbers 11 and 12 (which were named "magic numbers"). The existence of extreme events in P2 and not in P1, and also of the magic numbers, have been successfully reproduced by numerical simulations based on a five-variables iterative map, but the intuitive insight on the physical causes has been limited. In this paper, we present evidence that the extreme events in this laser appear if the amount of self-phase modulation on the pulses is above a certain threshold, and also that the P1 mode becomes unstable before crossing that threshold. This explains why the extreme events are observed in P2, and not in P1. Remarkably, even though the values of self-phase modulation on all the pulses (in the chaotic regime) are widely spread, the values inside the set of extreme events are relatively well defined. Finally, the magic numbers are found to be the residuals of the periodical orbits of the "cold" laser cavity when they are perturbed by the opposite effects of a dissipative term, due to the presence of transversal apertures, and an expansive term, due to the self-focusing.

  15. SAS 3 observations of two X-ray transient events with precursors

    NASA Technical Reports Server (NTRS)

    Hoffman, J. A.; Lewin, W. H. G.; Doty, J.; Jernigan, J. G.; Haney, M.; Richardson, J. A.

    1978-01-01

    SAS 3 has observed two unusual fast transient X-ray events from different sources, one lasting about 150 s and one, approximately 1500 s. Both events were preceded by precursor pulses which lasted a few seconds and which rose and fell in less than 0.4 s. The precursors were separated from the 'main' events by several seconds, during which no X-rays were detected. There are similarities between the two main events and X-ray bursts in both their temporal and spectral evolution. The spectra of the main events started out much softer than the spectra of the precursors, became harder as they approached maximum intensity, and softened as they decayed. In the 1500-s event, X-rays with energies greater than 10 keV were delayed by about 80 s compared with 1.5-6-keV X-rays. A blackbody fit to the spectral data of the main event of approximately 1500-s duration gives a maximum temperature of 29 million K and a radius for the emitting region of at least about 9 km (at a distance of 10 kpc); this is similar to the temperature and sizes found for several X-ray burst sources.

  16. Predictions and observations of events and configurations occurring during the Uranian equinox

    NASA Astrophysics Data System (ADS)

    Arlot, Jean-Eudes; Sicardy, Bruno

    2008-11-01

    The occurrence of the Earth and Sun transits through the equatorial plane of Uranus will bring us the opportunity for observations only possible at that time: mutual events of the satellites, search for new faint satellites and measurement of the thickness of the rings. The predictions of the mutual events need a theoretical model of the motion of the satellites. The calculated occurrences of the occultations and eclipses highly depend on the model since these predictions are very sensitive to the relative positions of the satellites. A difference of 0.05 arcsec in latitude may make an event inexistent and the accuracy of the theoretical models is around 0.1 arcsec. In order to be sure of the occurrence of each event, we made the predictions using three theoretical models: the first one is GUST86 made by Laskar and Jacobson in 1986, the second is GUST06 based on the former model fitted by Emelianov on new observations and the third one is LA06 based on a brand new theory with an accuracy 10 times better than GUST and fitted on recent observations made since 1950. This comparison shows that some events predicted with one model are not predicted using another one. We try to select the events which will occur surely in order to help the observers to catch the best phenomena. The search for new satellites and the measurement of the thickness of the rings are planned by means of observations at the time of the transit of the Earth in the ring plane.

  17. Estimating the Period and Q of the Chandler Wobble from Observations and Models of its Excitation

    NASA Astrophysics Data System (ADS)

    Gross, R. S.; Nastula, J.

    2014-12-01

    Any irregularly shaped solid body rotating about some axis that is not aligned with its figure axis will freely wobble as it rotates. For the Earth, this free wobble is known as the Chandler wobble in honor of S. C. Chandler, Jr. who first observed it in 1891. Unlike the forced wobbles of the Earth, such as the annual wobble, whose periods are the same as the periods of the forcing mechanisms, the period of the free Chandler wobble is a function of the internal structure and rheology of the Earth, and its decay time constant, or quality factor Q, is a function of the dissipation mechanism(s), like mantle anelasticity, that are acting to dampen it. Improved estimates of the period and Q of the Chandler wobble can therefore be used to improve our understanding of these properties of the Earth. Here, estimates of the period and Q of the Chandler wobble are obtained by finding those values that minimize the power within the Chandler band of the difference between observed and modeled polar motion excitation spanning 1962-2010. Atmosphere, ocean, and hydrology models are used to model the excitation caused by both mass and motion variations within these global geophysical fluids. Direct observations of the excitation caused by mass variations as determined from GRACE time varying gravitational field measurements are also used. The resulting estimates of the period and Q of the Chandler wobble will be presented along with a discussion of the robustness of the estimates.

  18. Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA

    NASA Astrophysics Data System (ADS)

    Gorham, P. W.; Nam, J.; Romero-Wolf, A.; Hoover, S.; Allison, P.; Banerjee, O.; Beatty, J. J.; Belov, K.; Besson, D. Z.; Binns, W. R.; Bugaev, V.; Cao, P.; Chen, C.; Chen, P.; Clem, J. M.; Connolly, A.; Dailey, B.; Deaconu, C.; Cremonesi, L.; Dowkontt, P. F.; Duvernois, M. A.; Field, R. C.; Fox, B. D.; Goldstein, D.; Gordon, J.; Hast, C.; Hebert, C. L.; Hill, B.; Hughes, K.; Hupe, R.; Israel, M. H.; Javaid, A.; Kowalski, J.; Lam, J.; Learned, J. G.; Liewer, K. M.; Liu, T. C.; Link, J. T.; Lusczek, E.; Matsuno, S.; Mercurio, B. C.; Miki, C.; Miočinović, P.; Mottram, M.; Mulrey, K.; Naudet, C. J.; Ng, J.; Nichol, R. J.; Palladino, K.; Rauch, B. F.; Reil, K.; Roberts, J.; Rosen, M.; Rotter, B.; Russell, J.; Ruckman, L.; Saltzberg, D.; Seckel, D.; Schoorlemmer, H.; Stafford, S.; Stockham, J.; Stockham, M.; Strutt, B.; Tatem, K.; Varner, G. S.; Vieregg, A. G.; Walz, D.; Wissel, S. A.; Wu, F.; Anita Collaboration

    2016-08-01

    We report on four radio-detected cosmic-ray (CR) or CR-like events observed with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload. Two of the four were previously identified as stratospheric CR air showers during the ANITA-I flight. A third stratospheric CR was detected during the ANITA-II flight. Here, we report on characteristics of these three unusual CR events, which develop nearly horizontally, 20-30 km above the surface of Earth. In addition, we report on a fourth steeply upward-pointing ANITA-I CR-like radio event which has characteristics consistent with a primary that emerged from the surface of the ice. This suggests a possible τ -lepton decay as the origin of this event, but such an interpretation would require significant suppression of the standard model τ -neutrino cross section.

  19. Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA.

    PubMed

    Gorham, P W; Nam, J; Romero-Wolf, A; Hoover, S; Allison, P; Banerjee, O; Beatty, J J; Belov, K; Besson, D Z; Binns, W R; Bugaev, V; Cao, P; Chen, C; Chen, P; Clem, J M; Connolly, A; Dailey, B; Deaconu, C; Cremonesi, L; Dowkontt, P F; DuVernois, M A; Field, R C; Fox, B D; Goldstein, D; Gordon, J; Hast, C; Hebert, C L; Hill, B; Hughes, K; Hupe, R; Israel, M H; Javaid, A; Kowalski, J; Lam, J; Learned, J G; Liewer, K M; Liu, T C; Link, J T; Lusczek, E; Matsuno, S; Mercurio, B C; Miki, C; Miočinović, P; Mottram, M; Mulrey, K; Naudet, C J; Ng, J; Nichol, R J; Palladino, K; Rauch, B F; Reil, K; Roberts, J; Rosen, M; Rotter, B; Russell, J; Ruckman, L; Saltzberg, D; Seckel, D; Schoorlemmer, H; Stafford, S; Stockham, J; Stockham, M; Strutt, B; Tatem, K; Varner, G S; Vieregg, A G; Walz, D; Wissel, S A; Wu, F

    2016-08-12

    We report on four radio-detected cosmic-ray (CR) or CR-like events observed with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload. Two of the four were previously identified as stratospheric CR air showers during the ANITA-I flight. A third stratospheric CR was detected during the ANITA-II flight. Here, we report on characteristics of these three unusual CR events, which develop nearly horizontally, 20-30 km above the surface of Earth. In addition, we report on a fourth steeply upward-pointing ANITA-I CR-like radio event which has characteristics consistent with a primary that emerged from the surface of the ice. This suggests a possible τ-lepton decay as the origin of this event, but such an interpretation would require significant suppression of the standard model τ-neutrino cross section. PMID:27563945

  20. Safety evaluation and confidence intervals when the number of observed events is small or zero.

    PubMed

    Jovanovic, B D; Zalenski, R J

    1997-09-01

    A common objective in many clinical studies is to determine the safety of a diagnostic test or therapeutic intervention. In these evaluations, serious adverse effects are either rare or not encountered. In this setting, the estimation of the confidence interval (CI) for the unknown proportion of adverse events has special importance. When no adverse events are encountered, commonly used approximate methods for calculating CIs cannot be applied, and such information is not commonly reported. Furthermore, when only a few adverse events are encountered, the approximate methods for calculation of CIs can be applied, but are neither appropriate nor accurate. In both situations, CIs should be computed with the use of the exact binomial distribution. We discuss the need for such estimation and provide correct methods and rules of thumb for quick computations of accurate approximations of the 95% and 99.9% CIs when the observed number of adverse events is zero. PMID:9287891

  1. Lobe crossing events observed by the Van Allen Probes as tests of magnetic field line mapping

    NASA Astrophysics Data System (ADS)

    Dixon, P.; MacDonald, E.; Grande, M.; Glocer, A.

    2014-04-01

    In this paper we examine a series of lobe crossing events witnessed by the twin Van Allen Probes spacecraft between 0200 and 0515 on November 14th 2012. The events occurred on the flank between 0400 and 0635 local time and at altitudes between 5.6 and 6.2 RE. During the events Dst was less than 100nT with the IMF being strongly southward (Bz = - 15nT) and eastward (By = 20 nT). Other observations at geosynchronous orbit also show lobe crossings at dawn and dusk flanks. These events provide a chance to examine the magnetic field topology in detail and compare it with models. We will show that the spacecraft were in locations with access to the open field lines by comparison to the CRCM + BATS-RUS models as well as comparing spacecraft encounters with the lobe to the predicted magnetic field topology.

  2. River flood events in Thailand and Bangladesh observed by CryoSat-2

    NASA Astrophysics Data System (ADS)

    Nielsen, Karina; Villadsen, Heidi; Andersen, Ole; Stenseng, Lars; Knudsen, Per

    2015-04-01

    The high along track resolution of the SIRAL altimeter carried on-board CryoSat-2 offers a wide range of unique opportunities for satellite monitoring. This study focuses on the ability of CryoSat-2 to detect the effects of flood events such as increased river levels and inundation of land. Here we study two flood events; the Bangladesh flood event of June 2012 and the flooding in Thailand that lasted between July 2011 and January 2012. The flooding in these areas was caused by abnormal monsoonal rainfall and affected millions of people. We process CryoSat-2 level 1b SAR mode data to derive water levels for the areas and compare these levels before, during and after the flooding events. Other parameters such as the backscatter coefficient and pulse peakiness are also considered. To verify the extent of the flooding observed by CryoSat-2 we compare with independent sources such as Landsat images.

  3. Observations and Interpretations of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Event

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.; Leske, R. A.; Shih, A. Y.; Stone, E. C.; Barghouty, A. f.; Cohen, C. M. S.; Cummings, A. c.; Labrador, A. W.; vonRosenvinge, T. T.

    2009-01-01

    We discuss recently reported observations of energetic neutral hydrogen atoms (ENAs) from an X9 solar flare/coronal mass ejection event on 5 December 2006, located at E79. The observations were made by the Low Energy Telescopes (LETs) on STEREO A and B. Prior to the arrival of the main solar energetic particle (SEP) event at Earth, both LETs observed a sudden burst of 1.6 to 15 MeV energetic neutral hydrogen atoms produced by either flare or shock-accelerated protons. RHESSI measurements of the 2.2-MeV gamma-ray line provide an estimate of the number of interacting flare-accelerated protons in this event, which leads to an improved estimate of ENA production by flare-accelerated protons. Taking into account ENA losses, we find that the observed ENAs must have been produced in the high corona at heliocentric distances > or equal to 2 solar radii. Although there are no CME images from this event, it is shown that CME-shock-accelerated protons can, in principle, produce a time-history consistent with the observations.

  4. Multipoint Observations of Coronal Mass Ejection and Solar Energetic Particle Events on Mars and Earth During November 2001

    NASA Technical Reports Server (NTRS)

    Falkenberg, T. V.; Vennerstrom, S.; Brain, D. A.; Delory, G.; Taktakishvili, A.

    2011-01-01

    Multipoint spacecraft observations provide unique opportunities to constrain the propagation and evolution of interplanetary coronal mass ejections (ICMEs) throughout the heliosphere. Using Mars Global Surveyor (MGS) data to study both ICME and solar energetic particle (SEP) events at Mars and OMNI and Geostationary Operational Environmental Satellite (GOES) data to study ICMEs and SEPs at Earth, we present a detailed study of three CMEs and flares in late November 2001. In this period, Mars trailed Earth by 56deg solar longitude so that the two planets occupied interplanetary magnetic field lines separated by only approx.25deg. We model the interplanetary propagation of CME events using the ENLIL version 2.6 3-D MHD code coupled with the Wang-Sheeley-Arge version 1.6 potential source surface model, using Solar and Heliospheric Observatory (SOHO) Large Angle and Spectrometric Coronagraph (LASCO) images to determine CME input parameters. We find that multipoint observations are essential to constrain the simulations of ICME propagation, as two very different ICMEs may look very similar in only one observational location. The direction and width of the CME as parameters essential to a correct estimation of arrival time and amplitude of the ICME signal. We find that these are problematic to extract from the analysis of SOHO/LASCO images commonly used for input to ICME propagation models. We further confirm that MGS magnetometer and electron reflectometer data can be used to study not only ICME events but also SEP events at Mars, with good results providing a consistent picture of the events when combined with near-Earth data.

  5. High latitude artificial periodic irregularity observations with the upgraded EISCAT heating facility

    NASA Astrophysics Data System (ADS)

    Vierinen, Juha; Kero, Antti; Rietveld, Michael T.

    2013-12-01

    We present a recently developed ionospheric modification experiment that produces artificial periodic irregularities in the ionosphere and uses them to make observations of the spatiotemporal behaviour of the irregularities. In addition, the method can be used to measure Faraday rotation and vertical velocities. We also introduce a novel experiment that allows monitoring the formation of the irregularities during heating, in addition to observing their decay after heating. The first measurements indicate, contrary to existing theory, that the amplitude of the radar echoes from the periodic irregularities grows faster than they decay. We focus on the API effects in the D- and E-region of the ionosphere.

  6. The growth of the oceanic boundary layer during the COARE intensive observational period: Large Eddy simulation results

    SciTech Connect

    Skyllingstad, E.D.; Wijesekera, H.W.; Gregg, M.C.

    1995-03-01

    A principal goal of the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE) is to gain an understanding of the processes that control mixing in the upper 100 m of the western tropical Pacific warm pool. The warm pool is an important heat reservoir for the global ocean and is responsible for many of the observed climatic changes associated with El Nino/Southern Oscillation (ENSO) events. This water mass is highly sensitive to mixed-layer processes that are controlled by surface heat, salinity, and momentum fluxes. During most of the year, these fluxes are dominated by solar heating and occasional squalls that freshen the top of the mixed layer and force shallow mixing of about 10-20 m. From November to April, the usual weather pattern is frequently altered by westerly wind bursts that are forced by tropical cyclones and intraseasonal oscillations. These wind bursts generate a strong eastward surface current and can force mixing as deep as 100 m over a period of days. Observations from the intensive observation period (IOP) in COARE indicate that mixed-layer deepening is accompanied by strong turbulence dissipation at the mixed layer base. A short westerly wind burst occurred during the first leg of TOGA-COARE, and lasted about 4-5 days. During this period, the maximum winds were about 10 m s{sup -1}, and the resulting eastward surface flow was about 0.5 m s{sup -1}. The strength of this event was somewhat weaker than a typical westerly wind burst, but the mixed-layer structure and growth are similar to the more vigorous wind bursts discussed.

  7. The magnetic network location of explosive events observed in the solar transition region

    NASA Technical Reports Server (NTRS)

    Porter, J. G.; Dere, K. P.

    1991-01-01

    Compact short-lived explosive events have been observed in solar transition region lines with the High-Resolution Telescope and Spectrograph (HRTS) flown by the Naval Research Laboratory on a series of rockets and on Spacelab 2. Data from Spacelab 2 are coaligned with a simultaneous magnetogram and near-simultaneous He I 10,380 -A spectroheliogram obtained at the National Solar Observatory at Kitt Peak. The comparison shows that the explosive events occur in the solar magnetic network lanes at the boundaries of supergranular convective cells. However, the events occur away from the larger concentrations of magnetic flux in the network, in contradiction to the observed tendency of the more energetic solar phenomena to be associated with the stronger magnetic fields.

  8. Enrichment of heavy nuclei in He-3-rich flares. [Imp-7 observed solar events

    NASA Technical Reports Server (NTRS)

    Hurford, G. J.; Mewaldt, R. A.; Stone, E. C.; Vogt, R. E.

    1975-01-01

    IMP-7 observations of five solar-flare particle events characterized by He-3 enrichment are reported which show that such events are also enriched in nuclei with charges (Z) of at least 6. The ratio of these nuclei to H-1 at approximately 3 MeV/nucleon was found to be enriched by about 10 to 100 times, while the ratio with respect to He-4 was enriched by about 3 to 30 times. It is suggested that the simultaneous enhancement of He-3 and the heavier nuclei as well as the absence of H-2 and H-3 during the observed events may be partly due to a preferential acceleration process which depends on the ratio of the square of the charge to the atomic weight of the nuclei.

  9. Onset Times of Solar Particle Events Observed by MSL/RAD - Constraints on Particle Transport

    NASA Astrophysics Data System (ADS)

    Wimmer-Schweingruber, R. F.; Hassler, D. M.; Boettcher, S.; Martin, C.; Zeitlin, C.; Brinza, D.; Koehler, J.; Guo, J.; Posner, A.; Appel, J.

    2012-12-01

    En route to Mars, Mars Science Laboratory's (MSL's) Radiation Assessment Detector (RAD) was already operational and observed a number of solar particle events. These were also seen by an array of spacecraft in the heliosphere. This constellation provides an unique opportunity to investigate particle propagation in the ecliptic plane and thus constrain particle propagation models. RAD measures energetic ions up to approximately 100 MeV/nuc, but was buried deep inside the Mars Science Laboratory (MSL). Due to the significant shielding provided by the MSL cruise stage, back-shell, heat shield, and skycrane, RAD was sensitive to particles in a significantly higher and somewhat uncertain energy range. Even behind the aforementioned shielding, onset times of particle events can be clearly identified. In this work, we will provide them for the particle events observed by RAD in 2012. We will also relate them to other data and solar/interplanetary acceleration sites.

  10. CRRES observation and STEERB simulation of the 9 October 1990 electron radiation belt dropout event

    NASA Astrophysics Data System (ADS)

    Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; Wang, Shui

    2011-03-01

    We examine and simulate the electron radiation belt dropout event on 9 October 1990. CRRES observations show that significant depletions of electron fluxes occurred at energies ˜0.1-1.0 MeV beyond 6 RE and at energies > ˜0.4 MeV within 6 RE. The three-dimensional kinetic radiation belt model STEERB is used to simulate this dropout event, taking into account the magnetopause shadowing, adiabatic transport, radial diffusion, and plume and chorus wave-particle interactions. Our results show that STEERB code can basically reproduce the observed depletion of ˜0.1-1.0 MeV electron fluxes throughout the outer radiation belt, suggesting that the competition and combination of all these physical mechanisms can well explain this electron radiation belt dropout event.

  11. Characteristics of extreme dust events observed over two urban areas in Iran

    NASA Astrophysics Data System (ADS)

    Bidokhti, Abbas-Ali A.; Gharaylou, Maryam; Pegahfar, Nafiseh; Sabetghadam, Samaneh; Rezazadeh, Maryam

    2016-03-01

    Determination of dust loading in the atmosphere is important not only from the public health point of view, but also for regional climate changes. The present study focuses on the characteristics of two major dust events for two urban areas in Iran, Kermanshah and Tehran, over the period of 4 years from 2006 to 2009. To detect extreme dust outbreaks, various datasets including synoptic data, dust concentration, reanalysis data and numerical results of WRF and HYSPLIT models were used. The weather maps demonstrate that for these events dusts are mainly generated when wind velocity is high and humidity is low in the lower troposphere and the region is under the influence of a thermal low. The event lasts until the atmospheric stability prevails and the surface wind speed weakens. The thermal low nature of the synoptic conditions of these major events is also responsible for deep boundary layer development with its thermals affecting the vertical dust flux over the region. Trajectory studies show that the dust events originated from deserts in Iraq and Syria and transported towards Iran. The main distinction between the two types of mobilizations seems to affect the dust concentrations in the Tehran urban area.

  12. Mutual Events of the Uranian Satellites Observed with the Faulkes Telescopes

    NASA Astrophysics Data System (ADS)

    Christou, Apostolos; Lewis, F.; Hidas, M. G.; Brown, T. M.; Roche, P.

    2008-09-01

    The 2007 Uranian Equinox allowed unique observations of the planet, its rings and satellites, possible only twice during the planet's 84 year orbit. Among these were mutual eclipses and occultations between the 5 classical satellites Ariel, Umbriel, Titania, Oberon and Miranda. These ``mutual'' events are extremely useful as reality checks of satellite ephemerides. In addition, they provide an opportunity to improve our knowledge of the satellite orbits and the system constants. We observed several mutual events in 2007 using the 2m Faulkes Telescopes North (FTN) and South (FTS) located in Haleakala, Maui and Siding Spring, Australia respectively, operated by the Las Cumbres Observatory Global Telescope (LCOGT) network. To mitigate against Uranus' glare, we utilized wide-band imaging in the near-IR, a small image scale and a posteriori subtraction of the planet's PSF. We obtained positive detections of six mutual events, three occultations and three eclipses, among these satellites. Three of these events involved Miranda, a difficult target due to its proximity to Uranus. Furthermore, we recorded at least two events that were predicted to occur with high confidence but did not, in fact, occur. During this presentation we will describe our observing strategy, operational setup and data reduction techniques and present examples of obtained lightcurves. Our observational results have been compared with predictions based on ephemerides by Laskar and Jacobson (1987; GUST86), by Lainey and Arlot (2006; LA06) and by Rush and Jacobson (2007; RJ07). Offsets with respect to the Voyager-era GUST86 are quite significant, of the order of minutes in the event midtimes. Smaller, yet significant trends in the data also appear with respect to LA06 and RJ07. We will discuss the nature of these trends and how they can be interpreted in terms of potential improvements in our knowledge of the Uranian system.

  13. An analysis of observations of mutual events of the Galilean satellites made in 1985 in Brazil

    NASA Astrophysics Data System (ADS)

    Arlot, J.-E.; Barroso, J.; Jablonsky, F. J.; Quast, G. R.; Thuillot, W.

    1990-03-01

    Mutual phenomena of the Galilean satellites occur every six years. These eclipses and occultations of a satellite by another lead to very accurate astrometric observations. During the last period in 1985 the Bureau des Longitudes organized a campaign of observation, and the Laboratorio Nacional de Astrofisica in Brazil joined it. This paper gives an analysis of the results obtained.

  14. Transition Region Explosive Events in He II 304Å: Observation and Analysis

    NASA Astrophysics Data System (ADS)

    Rust, Thomas; Kankelborg, Charles C.

    2016-05-01

    We present examples of transition region explosive events observed in the He II 304Å spectral line with the Multi Order Solar EUV Spectrograph (MOSES). With small (<5000 km) spatial scale and large non-thermal (100-150 km/s) velocities these events satisfy the observational signatures of transition region explosive events. Derived line profiles show distinct blue and red velocity components with very little broadening of either component. We observe little to no emission from low velocity plasma, making the plasmoid instability reconnection model unlikely as the plasma acceleration mechanism for these events. Rather, the single speed, bi-directional jet characteristics suggested by these data are consistent with acceleration via Petschek reconnection.Observations were made during the first sounding rocket flight of MOSES in 2006. MOSES forms images in 3 orders of a concave diffraction grating. Multilayer coatings largely restrict the passband to the He II 303.8Å and Si XI 303.3Å spectral lines. The angular field of view is about 8.5'x17', or about 20% of the solar disk. These images constitute projections of the volume I(x,y,λ), the intensity as a function of sky plane position and wavelength. Spectral line profiles are recovered via tomographic inversion of these projections. Inversion is carried out using a multiplicative algebraic reconstruction technique.

  15. Acceleration of a Static Observer Near the Event Horizon of a Static Isolated Black Hole.

    ERIC Educational Resources Information Center

    Doughty, Noel A.

    1981-01-01

    Compares the magnitude of the proper acceleration of a static observer in a static, isolated, spherically symmetric space-time region with the Newtonian result including the situation in the interior of a perfect-fluid star. This provides a simple physical interpretation of surface gravity and illustrates the global nature of the event horizon.…

  16. BEACHES: An Observational System for Assessing Children's Eating and Physical Activity Behaviors and Associated Events.

    ERIC Educational Resources Information Center

    McKenzie, Thomas L.; And Others

    1991-01-01

    The Behaviors of Eating and Activity for Children's Health Evaluation System (BEACHES) codes direct observations of children's dietary and physical activity behaviors and associated environmental events, including physical location, antecedents, and consequences. The system's reliability and validity was assessed in a study of 42 children (ages…

  17. Satellite and ground based observations of a large-scale electron precipitation event

    NASA Astrophysics Data System (ADS)

    Gamble, R. J.; Rodger, C. J.; Clilverd, M.; Thomson, N. R.; Ulich, T.; Parrot, M.; Sauvaud, J.; Berthelier, J.

    2010-12-01

    In order to describe how geomagnetic storms couple to the upper atmosphere, and hence to atmospheric chemistry and dynamics, measurements are required of energetic electron precipitation into the atmosphere. However, satellite observations are currently poorly suited to providing measurements of energetic and relativistic electron precipitation. The AARDDVARK network (Antarctic-Arctic Radiation-belt (Dynamic) Deposition - VLF Atmospheric Research Konsortium) provides continuous long-range observations of ionisation levels from ~30-85 km altitude, with the goal of increasing the understanding of energy coupling between the Earth's atmosphere, Sun, and Space. In this study we combine AARDDVARK subionospheric VLF measurements with DEMETER electron spectra using modelling techniques to study >100 keV energetic and relativistic electron precipitation into the atmosphere for the 24-hour period beginning 0600UT 19 January during the 17-21 January 2005 geomagnetic storms. The study augments large-scale regional observations using VLF measurements of multiple subionospheric paths to our receiver at Sodankylä, Finland (67.4°N, 26.6°E, L=5.31), combined with detailed in situ measurements from the DEMETER satellite to allow the spatial extent, flux, and energy distribution of the precipitation to be determined. In contrast to other satellites, DEMETER’s electron spectrometer has excellent energy resolution. The DEMETER-measured precipitation spectrum is used to infer an altered electron density profile, modelled using a simple ionospheric electron model. This altered electron profile is then used in a subionospheric VLF model and compared with AARDDVARK VLF results. Matching model results with subionospheric VLF measurements allows calculation of both the intensity and geographic extent (in L) of the precipitation region required to produce such an effect. We find that a flux of 7000 elec.cm-2s-1 >100 keV electrons precipitates into the atmosphere over an L range of 3

  18. Effect of initial conditions and of intra-event rainfall intensity variability on shallow landslide triggering return period

    NASA Astrophysics Data System (ADS)

    Peres, David Johnny; Cancelliere, Antonino

    2016-04-01

    Assessment of shallow landslide hazard is important for appropriate planning of mitigation measures. Generally, return period of slope instability is assumed as a quantitative metric to map landslide triggering hazard on a catchment. The most commonly applied approach to estimate such return period consists in coupling a physically-based landslide triggering model (hydrological and slope stability) with rainfall intensity-duration-frequency (IDF) curves. Among the drawbacks of such an approach, the following assumptions may be mentioned: (1) prefixed initial conditions, with no regard to their probability of occurrence, and (2) constant intensity-hyetographs. In our work we propose the use of a Monte Carlo simulation approach in order to investigate the effects of the two above mentioned assumptions. The approach is based on coupling a physically based hydrological and slope stability model with a stochastic rainfall time series generator. By this methodology a long series of synthetic rainfall data can be generated and given as input to a landslide triggering physically based model, in order to compute the return period of landslide triggering as the mean inter-arrival time of a factor of safety less than one. In particular, we couple the Neyman-Scott rectangular pulses model for hourly rainfall generation and the TRIGRS v.2 unsaturated model for the computation of transient response to individual rainfall events. Initial conditions are computed by a water table recession model that links initial conditions at a given event to the final response at the preceding event, thus taking into account variable inter-arrival time between storms. One-thousand years of synthetic hourly rainfall are generated to estimate return periods up to 100 years. Applications are first carried out to map landslide triggering hazard in the Loco catchment, located in highly landslide-prone area of the Peloritani Mountains, Sicily, Italy. Then a set of additional simulations are performed

  19. Characterization of exceptionally strong mesospheric wave events using all-sky and zenith airglow observations

    NASA Astrophysics Data System (ADS)

    Smith, Steven M.; Scheer, Jürgen; Reisin, Esteban R.; Baumgardner, Jeffrey; Mendillo, Michael

    2006-09-01

    Two unusually clear mesospheric gravity wave events were observed by the Boston University all-sky imager and the Argentine airglow spectrometer on two consecutive nights at the El Leoncito Observatory, Argentina (31.8°S, 69.3°W), during August 2001. Both events exhibited brightness amplitudes an order of magnitude above typical values. The first event had the appearance of a large-amplitude (>60% in OH(6-2), 22% in O2, and 37% in O(1S) emissions (peak to peak), compared to 1-5% typically), upward propagating gravity wave with pronounced nonlinear behavior. The waves also showed noticeably curved wavefronts, indicating that they had originated from a relatively small source region within ˜180 km of El Leoncito. Estimates of the vertical flux of horizontal energy and momentum for the wave event in the OH and O2 emissions were very large compared to typical values, and they also indicated a high degree of flux divergence over the nominal 8 km altitude between the two layers. The second event occurred on the following night and exhibited a frontal morphology and behavior consistent with an internal ducted gravity wave showing nonlinear behavior akin to a mesospheric bore. The disturbance also had several interesting characteristics; in particular, the propagation speed decreased during its passage across the sky. In addition, a strong vertical temperature gradient due to the semidiurnal tide appeared to influence the occurrence of the bore event.

  20. International Observe the Moon Night: Using Public Outreach Events to Tell Your Story to the Public

    NASA Astrophysics Data System (ADS)

    Hsu, B. C.; International Observe the Moon Night Coordinating Committee

    2011-12-01

    From various interpretations of the lunar "face," early pictograms of the Moon's phases, or to the use of the lunar cycle for festivals or harvests, the Moon has an undeniable influence on human civilization. International Observe the Moon Night (InOMN) capitalizes on the human connection to the Moon by engaging the public in annual lunar observation campaigns that share the excitement of lunar science and exploration. In 2010 (InOMN's inaugural year), over 500,000 people attended events in 53 countries around the world. About 68% of InOMN hosts - astronomy clubs, museums, schools, or other groups - used the resources on the InOMN website (http://observethemoonnight.org). The InOMN website provided supporting materials for InOMN event hosts in the form of downloadable advertising materials, Moon maps, suggestions for hands-on educational activities, and links to lunar science content. InOMN event participants shared their experiences with the world using the Web and social media, event hosts shared their experiences with evaluation data, and amateur astronomers and photographers shared their images of the Moon through the lunar photography contest. The overwhelming response from InOMN in 2010 represents an untapped potential for infusing cutting edge lunar science and exploration into a large-scale public outreach event.

  1. Spurious One-Month and One-Year Periods in Visual Observations of Variable Stars

    NASA Astrophysics Data System (ADS)

    Percy, J. R.

    2015-12-01

    Visual observations of variable stars, when time-series analyzed with some algorithms such as DC-DFT in vstar, show spurious periods at or close to one synodic month (29.5306 days), and also at about a year, with an amplitude of typically a few hundredths of a magnitude. The one-year periods have been attributed to the Ceraski effect, which was believed to be a physiological effect of the visual observing process. This paper reports on time-series analysis, using DC-DFT in vstar, of visual observations (and in some cases, V observations) of a large number of stars in the AAVSO International Database, initially to investigate the one-month periods. The results suggest that both the one-month and one-year periods are actually due to aliasing of the stars' very low-frequency variations, though they do not rule out very low-amplitude signals (typically 0.01 to 0.02 magnitude) which may be due to a different process, such as a physiological one. Most or all of these aliasing effects may be avoided by using a different algorithm, which takes explicit account of the window function of the data, and/or by being fully aware of the possible presence of and aliasing by very low-frequency variations.

  2. On the Mechanisms Producing Iceberg Discharges During Last Glacial Period, Including Heinrich Events

    NASA Astrophysics Data System (ADS)

    Alvarez-Solas, J.; Robinson, A.; Banderas, R.; Montoya, M.

    2014-12-01

    Proxy data reveal the existence of episodes of increased deposition of ice-rafted debris in the North Atlantic Ocean during the last glacial period. These are interpreted as massive iceberg discharges mainly from the Laurentide Ice Sheet. Although these have long been attributed to self-sustained ice sheet oscillations, growing evidence points to an active role of the oceanic circulation. Here we present simulations of the last glacial period carried out with a hybrid ice sheet-ice shelf model. Two mechanisms producing iceberg discharges are compared. First, we reproduce the classic binge-purge by which the iceberg surges are produced thanks to the existence of an internal thermo-mechanical feedback that allows the ice sheet to behave under an oscillatory regime. Second, our ice-sheet model is forced by an oceanic warming index derived from proxy data that accounts for the impact of past ocean circulation changes on ocean temperatures. In this case, the model generates a time series of iceberg calving that agrees with ice-rafted debris records over the past 80 ka. We compare the two theories and discuss their advantages and weaknesses in terms of both the robustness of the physics on which they are based and their comparison with proxies.

  3. Distributions of topological observables in inclusive three- and four-jet events in pp collisions at

    NASA Astrophysics Data System (ADS)

    Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knünz, V.; Krammer, M.; Krätschmer, I.; Liko, D.; Mikulec, I.; Rabady, D.; Rahbaran, B.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; Bansal, S.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Knutsson, A.; Lauwers, J.; Luyckx, S.; Ochesanu, S.; Rougny, R.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Daci, N.; Heracleous, N.; Keaveney, J.; Lowette, S.; Maes, M.; Olbrechts, A.; Python, Q.; Strom, D.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Caillol, C.; Clerbaux, B.; De Lentdecker, G.; Dobur, D.; Favart, L.; Gay, A. P. R.; Grebenyuk, A.; Léonard, A.; Mohammadi, A.; Perniè, L.; Randle-conde, A.; Reis, T.; Seva, T.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Zenoni, F.; Adler, V.; Beernaert, K.; Benucci, L.; Cimmino, A.; Costantini, S.; Crucy, S.; Dildick, S.; Fagot, A.; Garcia, G.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Salva Diblen, S.; Sigamani, M.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Beluffi, C.; Bruno, G.; Castello, R.; Caudron, A.; Ceard, L.; Da Silveira, G. G.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Jafari, A.; Jez, P.; Komm, M.; Lemaitre, V.; Nuttens, C.; Pagano, D.; Perrini, L.; Pin, A.; Piotrzkowski, K.; Popov, A.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Vizan Garcia, J. M.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Júnior, W. L. Aldá; Alves, G. A.; Brito, L.; Correa Martins Junior, M.; Martins, T. Dos Reis; Mora Herrera, C.; Pol, M. E.; Rebello Teles, P.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Malbouisson, H.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santaolalla, J.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Bernardes, C. A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Aleksandrov, A.; Genchev, V.; Hadjiiska, R.; Iaydjiev, P.; Marinov, A.; Piperov, S.; Rodozov, M.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Cheng, T.; Du, R.; Jiang, C. H.; Plestina, R.; Romeo, F.; Tao, J.; Wang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Zou, W.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; Gomez Moreno, B.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Polic, D.; Puljak, I.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Kadija, K.; Luetic, J.; Mekterovic, D.; Sudic, L.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Bodlak, M.; Finger, M.; Finger, M.; Assran, Y.; Ellithi Kamel, A.; Mahmoud, M. A.; Radi, A.; Kadastik, M.; Murumaa, M.; Raidal, M.; Tiko, A.; Eerola, P.; Fedi, G.; Voutilainen, M.; Härkönen, J.; Karimäki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Baffioni, S.; Beaudette, F.; Busson, P.; Charlot, C.; Dahms, T.; Dalchenko, M.; Dobrzynski, L.; Filipovic, N.; Florent, A.; Granier de Cassagnac, R.; Mastrolorenzo, L.; Miné, P.; Mironov, C.; Naranjo, I. N.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Regnard, S.; Salerno, R.; Sauvan, J. B.; Sirois, Y.; Veelken, C.; Yilmaz, Y.; Zabi, A.; Agram, J.-L.; Andrea, J.; Aubin, A.; Bloch, D.; Brom, J.-M.; Chabert, E. C.; Collard, C.; Conte, E.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Goetzmann, C.; Le Bihan, A.-C.; Skovpen, K.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Beaupere, N.; Boudoul, G.; Bouvier, E.; Brochet, S.; Carrillo Montoya, C. A.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fan, J.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Kurca, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Ruiz Alvarez, J. D.; Sabes, D.; Sgandurra, L.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Xiao, H.; Tsamalaidze, Z.; Autermann, C.; Beranek, S.; Bontenackels, M.; Edelhoff, M.; Feld, L.; Heister, A.; Hindrichs, O.; Klein, K.; Ostapchuk, A.; Raupach, F.; Sammet, J.; Schael, S.; Schulte, J. F.; Weber, H.; Wittmer, B.; Zhukov, V.; Ata, M.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Erdmann, M.; Fischer, R.; Güth, A.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Klingebiel, D.; Knutzen, S.; Kreuzer, P.; Merschmeyer, M.; Meyer, A.; Millet, P.; Olschewski, M.; Padeken, K.; Papacz, P.; Reithler, H.; Schmitz, S. A.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Weber, M.; Cherepanov, V.; Erdogan, Y.; Flügge, G.; Geenen, H.; Geisler, M.; Haj Ahmad, W.; Hoehle, F.; Kargoll, B.; Kress, T.; Kuessel, Y.; Künsken, A.; Lingemann, J.; Nowack, A.; Nugent, I. M.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Asin, I.; Bartosik, N.; Behr, J.; Behrens, U.; Bell, A. J.; Bethani, A.; Borras, K.; Burgmeier, A.; Cakir, A.; Calligaris, L.; Campbell, A.; Choudhury, S.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Dooling, S.; Dorland, T.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Flucke, G.; Garcia, J. Garay; Geiser, A.; Gunnellini, P.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Kasemann, M.; Katsas, P.; Kieseler, J.; Kleinwort, C.; Korol, l.; Krücker, D.; Lange, W.; Leonard, J.; Lipka, K.; Lobanov, A.; Lohmann, W.; Lutz, B.; Mankel, R.; Marfin, I.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Naumann-Emme, S.; Nayak, A.; Ntomari, E.; Perrey, H.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Ribeiro Cipriano, P. M.; Roland, B.; Ron, E.; Sahin, M. Ö.; Salfeld-Nebgen, J.; Saxena, P.; Schoerner-Sadenius, T.; Schröder, M.; Seitz, C.; Spannagel, S.; Vargas Trevino, A. D. R.; Walsh, R.; Wissing, C.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Erfle, J.; Garutti, E.; Goebel, K.; Görner, M.; Haller, J.; Hoffmann, M.; Höing, R. S.; Junkes, A.; Kirschenmann, H.; Klanner, R.; Kogler, R.; Lange, J.; Lapsien, T.; Lenz, T.; Marchesini, I.; Ott, J.; Peiffer, T.; Perieanu, A.; Pietsch, N.; Poehlsen, J.; Poehlsen, T.; Rathjens, D.; Sander, C.; Schettler, H.; Schleper, P.; Schlieckau, E.; Schmidt, A.; Seidel, M.; Sola, V.; Stadie, H.; Steinbrück, G.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Barth, C.; Baus, C.; Berger, J.; Böser, C.; Butz, E.; Chwalek, T.; De Boer, W.; Descroix, A.; Dierlamm, A.; Feindt, M.; Frensch, F.; Giffels, M.; Gilbert, A.; Hartmann, F.; Hauth, T.; Husemann, U.; Katkov, I.; Kornmayer, A.; Kuznetsova, E.; Lobelle Pardo, P.; Mozer, M. U.; Müller, T.; Müller, Th.; Nürnberg, A.; Quast, G.; Rabbertz, K.; Röcker, S.; Simonis, H. J.; Stober, F. M.; Ulrich, R.; Wagner-Kuhr, J.; Wayand, S.; Weiler, T.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Markou, A.; Markou, C.; Psallidas, A.; Topsis-Giotis, I.; Agapitos, A.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Stiliaris, E.; Aslanoglou, X.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Strologas, J.; Bencze, G.; Hajdu, C.; Hidas, P.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Molnar, J.; Palinkas, J.; Szillasi, Z.; Makovec, A.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Swain, S. K.; Beri, S. B.; Bhatnagar, V.; Gupta, R.; Bhawandeep, U.; Kalsi, A. K.; Kaur, M.; Kumar, R.; Mittal, M.; Nishu, N.; Singh, J. B.; Kumar, Ashok; Kumar, Arun; Ahuja, S.; Bhardwaj, A.; Choudhary, B. C.; Kumar, A.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Sharma, V.; Banerjee, S.; Bhattacharya, S.; Chatterjee, K.; Dutta, S.; Gomber, B.; Jain, Sa.; Jain, Sh.; Khurana, R.; Modak, A.; Mukherjee, S.; Roy, D.; Sarkar, S.; Sharan, M.; Abdulsalam, A.; Dutta, D.; Kumar, V.; Mohanty, A. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Banerjee, S.; Bhowmik, S.; Chatterjee, R. M.; Dewanjee, R. K.; Dugad, S.; Ganguly, S.; Ghosh, S.; Guchait, M.; Gurtu, A.; Kole, G.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Mohanty, G. B.; Parida, B.; Sudhakar, K.; Wickramage, N.; Bakhshiansohi, H.; Behnamian, H.; Etesami, S. M.; Fahim, A.; Goldouzian, R.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Calabria, C.; Chhibra, S. S.; Colaleo, A.; Creanza, D.; De Filippis, N.; De Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Selvaggi, G.; Sharma, A.; Silvestris, L.; Venditti, R.; Verwilligen, P.; Abbiendi, G.; Benvenuti, A. C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Rossi, A. M.; Primavera, F.; Rovelli, T.; Siroli, G. P.; Tosi, N.; Travaglini, R.; Albergo, S.; Cappello, G.; Chiorboli, M.; Costa, S.; Giordano, F.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Gallo, E.; Gonzi, S.; Gori, V.; Lenzi, P.; Meschini, M.; Paoletti, S.; Sguazzoni, G.; Tropiano, A.; Benussi, L.; Bianco, S.; Fabbri, F.; Piccolo, D.; Ferretti, R.; Ferro, F.; Lo Vetere, M.; Robutti, E.; Tosi, S.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Gerosa, R.; Ghezzi, A.; Govoni, P.; Lucchini, M. T.; Malvezzi, S.; Manzoni, R. A.; Martelli, A.; Marzocchi, B.; Menasce, D.; Moroni, L.; Paganoni, M.; Pedrini, D.; Ragazzi, S.; Redaelli, N.; Tabarelli de Fatis, T.; Buontempo, S.; Cavallo, N.; Di Guida, S.; Fabozzi, F.; Iorio, A. O. M.; Lista, L.; Meola, S.; Merola, M.; Paolucci, P.; Azzi, P.; Bacchetta, N.; Bellato, M.; Biasotto, M.; Dall'Osso, M.; Dorigo, T.; Galanti, M.; Giubilato, P.; Gonella, F.; Gozzelino, A.; Kanishchev, K.; Lacaprara, S.; Margoni, M.; Meneguzzo, A. T.; Montecassiano, F.; Passaseo, M.; Pazzini, J.; Pegoraro, M.; Pozzobon, N.; Ronchese, P.; Simonetto, F.; Torassa, E.; Tosi, M.; Vanini, S.; Ventura, S.; Zotto, P.; Zucchetta, A.; Gabusi, M.; Ratti, S. P.; Re, V.; Riccardi, C.; Salvini, P.; Vitulo, P.; Biasini, M.; Bilei, G. M.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Mantovani, G.; Menichelli, M.; Saha, A.; Santocchia, A.; Spiezia, A.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Bernardini, J.; Boccali, T.; Broccolo, G.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Fiori, F.; Foà, L.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Moon, C. S.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Serban, A. T.; Spagnolo, P.; Squillacioti, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Vernieri, C.; Barone, L.; Cavallari, F.; D'imperio, G.; Del Re, D.; Diemoz, M.; Jorda, C.; Longo, E.; Margaroli, F.; Meridiani, P.; Micheli, F.; Nourbakhsh, S.; Organtini, G.; Paramatti, R.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Soffi, L.; Traczyk, P.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bellan, R.; Biino, C.; Cartiglia, N.; Casasso, S.; Costa, M.; Degano, A.; Demaria, N.; Finco, L.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Musich, M.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Potenza, A.; Romero, A.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Tamponi, U.; Belforte, S.; Candelise, V.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; Gobbo, B.; La Licata, C.; Marone, M.; Schizzi, A.; Umer, T.; Zanetti, A.; Chang, S.; Kropivnitskaya, T. A.; Nam, S. K.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Kim, M. S.; Kong, D. J.; Lee, S.; Oh, Y. D.; Park, H.; Sakharov, A.; Son, D. C.; Kim, T. J.; Kim, J. Y.; Song, S.; Choi, S.; Gyun, D.; Hong, B.; Jo, M.; Kim, H.; Kim, Y.; Lee, B.; Lee, K. S.; Park, S. K.; Roh, Y.; Yoo, H. D.; Choi, M.; Kim, J. H.; Park, I. C.; Ryu, G.; Ryu, M. S.; Choi, Y.; Choi, Y. K.; Goh, J.; Kim, D.; Kwon, E.; Lee, J.; Yu, I.; Juodagalvis, A.; Komaragiri, J. R.; Md Ali, M. A. B.; Casimiro Linares, E.; Castilla-Valdez, H.; De La Cruz-Burelo, E.; Heredia-de La Cruz, I.; Hernandez-Almada, A.; Lopez-Fernandez, R.; Sanchez-Hernandez, A.; Carrillo Moreno, S.; Vazquez Valencia, F.; Pedraza, I.; Salazar Ibarguen, H. A.; Morelos Pineda, A.; Krofcheck, D.; Butler, P. H.; Reucroft, S.; Ahmad, A.; Ahmad, M.; Hassan, Q.; Hoorani, H. R.; Khan, W. 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V.; Vinogradov, A.; Belyaev, A.; Boos, E.; Dubinin, M.; Dudko, L.; Ershov, A.; Gribushin, A.; Klyukhin, V.; Kodolova, O.; Lokhtin, I.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Snigirev, A.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Krychkine, V.; Petrov, V.; Ryutin, R.; Sobol, A.; Tourtchanovitch, L.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Ekmedzic, M.; Milosevic, J.; Rekovic, V.; Alcaraz Maestre, J.; Battilana, C.; Calvo, E.; Cerrada, M.; Chamizo Llatas, M.; Colino, N.; De La Cruz, B.; Delgado Peris, A.; Domínguez Vázquez, D.; Escalante Del Valle, A.; Fernandez Bedoya, C.; Ramos, J. P. Fernández; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Navarro De Martino, E.; Yzquierdo, A. Pérez-Calero; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; Albajar, C.; de Trocóniz, J. 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V.; Maksimovic, P.; Martin, C.; Swartz, M.; Baringer, P.; Bean, A.; Benelli, G.; Bruner, C.; Kenny, R. P.; Malek, M.; Murray, M.; Noonan, D.; Sanders, S.; Sekaric, J.; Stringer, R.; Wang, Q.; Wood, J. S.; Chakaberia, I.; Ivanov, A.; Khalil, S.; Makouski, M.; Maravin, Y.; Saini, L. K.; Skhirtladze, N.; Svintradze, I.; Gronberg, J.; Lange, D.; Rebassoo, F.; Wright, D.; Baden, A.; Belloni, A.; Calvert, B.; Eno, S. C.; Gomez, J. A.; Hadley, N. J.; Kellogg, R. G.; Kolberg, T.; Lu, Y.; Mignerey, A. C.; Pedro, K.; Skuja, A.; Tonjes, M. B.; Tonwar, S. C.; Apyan, A.; Barbieri, R.; Busza, W.; Cali, I. A.; Chan, M.; Di Matteo, L.; Gomez Ceballos, G.; Goncharov, M.; Gulhan, D.; Klute, M.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Paus, C.; Ralph, D.; Roland, C.; Roland, G.; Stephans, G. S. F.; Sumorok, K.; Velicanu, D.; Veverka, J.; Wyslouch, B.; Yang, M.; Zanetti, M.; Zhukova, V.; Dahmes, B.; Gude, A.; Kao, S. C.; Klapoetke, K.; Kubota, Y.; Mans, J.; Pastika, N.; Rusack, R.; Singovsky, A.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Bose, S.; Claes, D. R.; Dominguez, A.; Gonzalez Suarez, R.; Keller, J.; Knowlton, D.; Kravchenko, I.; Lazo-Flores, J.; Meier, F.; Ratnikov, F.; Snow, G. R.; Zvada, M.; Dolen, J.; Godshalk, A.; Iashvili, I.; Kharchilava, A.; Kumar, A.; Rappoccio, S.; Alverson, G.; Barberis, E.; Baumgartel, D.; Chasco, M.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Trocino, D.; Wang, R. J.; Wood, D.; Zhang, J.; Hahn, K. A.; Kubik, A.; Mucia, N.; Odell, N.; Pollack, B.; Pozdnyakov, A.; Schmitt, M.; Stoynev, S.; Sung, K.; Velasco, M.; Won, S.; Brinkerhoff, A.; Chan, K. M.; Drozdetskiy, A.; Hildreth, M.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Lynch, S.; Marinelli, N.; Musienko, Y.; Pearson, T.; Planer, M.; Ruchti, R.; Smith, G.; Valls, N.; Wayne, M.; Wolf, M.; Woodard, A.; Antonelli, L.; Brinson, J.; Bylsma, B.; Durkin, L. 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P.; Redjimi, R.; Roberts, J.; Zabel, J.; Betchart, B.; Bodek, A.; Covarelli, R.; de Barbaro, P.; Demina, R.; Eshaq, Y.; Ferbel, T.; Garcia-Bellido, A.; Goldenzweig, P.; Han, J.; Harel, A.; Khukhunaishvili, A.; Korjenevski, S.; Petrillo, G.; Vishnevskiy, D.; Ciesielski, R.; Demortier, L.; Goulianos, K.; Mesropian, C.; Arora, S.; Barker, A.; Chou, J. P.; Contreras-Campana, C.; Contreras-Campana, E.; Duggan, D.; Ferencek, D.; Gershtein, Y.; Gray, R.; Halkiadakis, E.; Hidas, D.; Kaplan, S.; Lath, A.; Panwalkar, S.; Park, M.; Patel, R.; Salur, S.; Schnetzer, S.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Rose, K.; Spanier, S.; York, A.; Bouhali, O.; Castaneda Hernandez, A.; Eusebi, R.; Flanagan, W.; Gilmore, J.; Kamon, T.; Khotilovich, V.; Krutelyov, V.; Montalvo, R.; Osipenkov, I.; Pakhotin, Y.; Perloff, A.; Roe, J.; Rose, A.; Safonov, A.; Suarez, I.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Kovitanggoon, K.; Kunori, S.; Lee, S. W.; Libeiro, T.; Volobouev, I.; Appelt, E.; Delannoy, A. G.; Greene, S.; Gurrola, A.; Johns, W.; Maguire, C.; Mao, Y.; Melo, A.; Sharma, M.; Sheldon, P.; Snook, B.; Tuo, S.; Velkovska, J.; Arenton, M. W.; Boutle, S.; Cox, B.; Francis, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Li, H.; Lin, C.; Neu, C.; Wood, J.; Clarke, C.; Harr, R.; Karchin, P. E.; Kottachchi Kankanamge Don, C.; Lamichhane, P.; Sturdy, J.; Belknap, D. A.; Carlsmith, D.; Cepeda, M.; Dasu, S.; Dodd, L.; Duric, S.; Friis, E.; Hall-Wilton, R.; Herndon, M.; Hervé, A.; Klabbers, P.; Lanaro, A.; Lazaridis, C.; Levine, A.; Loveless, R.; Mohapatra, A.; Ojalvo, I.; Perry, T.; Pierro, G. A.; Polese, G.; Ross, I.; Sarangi, T.; Savin, A.; Smith, W. H.; Taylor, D.; Vuosalo, C.; Woods, N.

    2015-07-01

    This paper presents distributions of topological observables in inclusive three- and four-jet events produced in pp collisions at a centre-of-mass energy of 7 with a data sample collected by the CMS experiment corresponding to a luminosity of 5.1. The distributions are corrected for detector effects, and compared with several event generators based on two- and multi-parton matrix elements at leading order. Among the considered calculations, MadGraph interfaced with pythia6 displays the overall best agreement with data.

  4. Dimuon events produced in high energy antineutrino interactions observed in BEBC

    NASA Astrophysics Data System (ADS)

    Armenise, N.; Calicchio, M.; Erriquez, O.; Fogli-Muciaccia, M. T.; Natali, S.; Nuzzo, S.; Romano, F.; Belusevic, R.; Colley, D. C.; Jones, G. T.; Lowe, L.; O'Neale, S.; Sewell, S. J.; Votruba, M. F.; Bertrand, D.; Sacton, J.; Vander Velde-Wilquet, C.; Van Doninck, W.; Wilquet, G.; Brisson, V.; Francois, T.; Kluberg, L.; Petiau, P.; Cooper, A. M.; Guy, J. G.; Michette, A. G.; Tyndel, M.; Venus, W.; Gerbier, G.; Alitti, J.; Baton, J. P.; Iori, M.; Kochowski, C.; Neveu, M.; Baker, N. J.; Bartley, J. H.; BEBC “TST” Neutrino Collaboration

    1980-08-01

    A study is presented of dimuon events from an exposure of BEBC to a wide band overlineν beam from the CERN SPS. These data double the available statistics on overlineν induced dilepton events observed in bubble chambers. The relative production rate and V 0 yield have been measured and found to agree with previous experiments. The analysis of several kinematical variables shows that the gros features of the data agree with the predictions of the GIM model. Some indication exists that part of the signal could be due to quasi elastic production of the “beautiful baryon”, but the statistical significance is too weak to draw definitive conclusions.

  5. Sensor Configuration Selection for Discrete-Event Systems under Unreliable Observations

    SciTech Connect

    Wen-Chiao Lin; Tae-Sic Yoo; Humberto E. Garcia

    2010-08-01

    Algorithms for counting the occurrences of special events in the framework of partially-observed discrete event dynamical systems (DEDS) were developed in previous work. Their performances typically become better as the sensors providing the observations become more costly or increase in number. This paper addresses the problem of finding a sensor configuration that achieves an optimal balance between cost and the performance of the special event counting algorithm, while satisfying given observability requirements and constraints. Since this problem is generally computational hard in the framework considered, a sensor optimization algorithm is developed using two greedy heuristics, one myopic and the other based on projected performances of candidate sensors. The two heuristics are sequentially executed in order to find best sensor configurations. The developed algorithm is then applied to a sensor optimization problem for a multiunit- operation system. Results show that improved sensor configurations can be found that may significantly reduce the sensor configuration cost but still yield acceptable performance for counting the occurrences of special events.

  6. C3Winds: A Novel 3D Wind Observing System to Characterize Severe Weather Events

    NASA Astrophysics Data System (ADS)

    Kelly, M. A.; Wu, D. L.; Yee, J. H.; Boldt, J.; Demajistre, R.; Reynolds, E.; Tripoli, G. J.; Oman, L.; Prive, N.; Heidinger, A. K.; Wanzong, S.

    2015-12-01

    The CubeSat Constellation Cloud Winds (C3Winds) is a NASA Earth Venture Instrument (EV-I) concept with the primary objective to resolve high-resolution 3D dynamic structures of severe wind events. Rapid evolution of severe weather events highlights the need for high-resolution mesoscale wind observations. Yet mesoscale observations of severe weather dynamics are quite rare, especially over the ocean where extratropical and tropical cyclones (ETCs and TCs) can undergo explosive development. Measuring wind velocity at the mesoscale from space remains a great challenge, but is critically needed to understand and improve prediction of severe weather and tropical cyclones. Based on compact, visible/IR imagers and a mature stereoscopic technique, C3Winds has the capability to measure high-resolution (~2 km) cloud motion vectors and cloud geometric heights accurately by tracking cloud features from two formation-flying CubeSats, separated by 5-15 minutes. Complementary to lidar wind measurements from space, C3Winds will provide high-resolution wind fields needed for detailed investigations of severe wind events in occluded ETCs, rotational structures inside TC eyewalls, and ozone injections associated with tropopause folding events. Built upon mature imaging technologies and long history of stereoscopic remote sensing, C3Winds provides an innovative, cost-effective solution to global wind observations with the potential for increased diurnal sampling via CubeSat constellation.

  7. A polar cap absorption event observed using the Southern Hemisphere SuperDARN radar network.

    NASA Astrophysics Data System (ADS)

    Breed, A.; Morris, R.; Parkinson, M.; Duldig, M.; Dyson, P.

    A large X5 class solar flare and coronal mass ejection were observed emanating from the sun on July 14, 2000. Approximately 10 minutes later a large cosmic ray ground level enhancement was observed using neutron monitors located at Mawson station (70.5°S CGM), Antarctica; Large increases in proton flux were also observed using satellites during this time. This marked the start of a large polar cap absorption event with cosmic noise absorption peaking at 30 dB, as measured by a 30 MHz riometer located at Casey station (80.4°S CGM), Antarctica. The spatial evolution of this event and its subsequent recovery were studied using the Southern Hemisphere SuperDARN radar network, including the relatively low latitude observation provided by the Tasman International Geospace Environment Radar (TIGER) located on Bruny Island (54.6°S GGM), Tasmania. When the bulk of the CME arrived at the Earth two days later it triggered an intense geomagnetic storm. This paper presents observations of the dramatic sequence of events.

  8. Thermal movement of the regolith. [seismic event observed at Apollo 17 landing site

    NASA Technical Reports Server (NTRS)

    Duennebier, F.

    1976-01-01

    High-frequency seismic events observed at the Apollo landing sites indicate that the regolith moves in response to diurnal variations of thermal stresses. While these events (thermal moonquakes) are observed by each of the Passive Seismic Experiment stations, the location of their sources was not possible until they were observed by the Lunar Surface Profiling Experiment (LSPE) array at the Apollo 17 site. Comparison of source locations with topographic features near the LSPE array indicate that thermal moonquakes are associated to some degree with large rocks and to a larger degree with craters. They are not associated with man-made disturbances of the lunar surface. It is suggested that thermal moonquakes are the seismic expression of a phenomenon that is actively degrading slopes on the lunar surface.

  9. Visual search is postponed during the period of the AB: An event-related potential study.

    PubMed

    Lagroix, Hayley E P; Grubert, Anna; Spalek, Thomas M; Di Lollo, Vincent; Eimer, Martin

    2015-08-01

    In the phenomenon known as the attentional blink (AB), perception of the second of two rapidly sequential targets (T2) is impaired when presented shortly after the first (T1). Studies in which T2 consisted of a pop-out search array provided evidence suggesting that visual search is postponed during the AB. In the present work, we used behavioral and electrophysiological measures to test this postponement hypothesis. The behavioral measure was reaction time (RT) to T2; the electrophysiological measure was the onset latency of an ERP index of attentional selection, known as the N2pc. Consistent with the postponement hypothesis, both measures were delayed during the AB. The delay in N2pc was substantially shorter than that in RT, pointing to multiple sources of delay in the chain of processing events, as distinct from the single source postulated in current theories of the AB. Finally, the finding that the N2pc was delayed during the AB strongly suggests that attention is involved in the processing of pop-out search arrays. PMID:25871502

  10. Strainmeter observations of the 2010 slow slip event in Cascadia: A critical look at noise, artifacts, and tectonic signals

    NASA Astrophysics Data System (ADS)

    Krogstad, R.; Schmidt, D. A.

    2010-12-01

    Periodic slow-slip events along the Cascadia subduction zone represent the transient release of accumulated strain along the plate interface. The location of these events helps to map the lower edge of the seismogenic zone and constrain the seismic hazard. The primary observations of these slow-slip events have come from a large array of GPS stations in the Pacific Northwest. However, newly installed borehole strainmeters provide greater temporal resolution and greater precision than GPS. Incorporating strainmeter data into current slip inversion models, which have previously depended upon GPS data, will help to further constrain models of the slip distribution at depth. Understanding the capabilities and limitations of strainmeter data, especially in regards to the quantification of noise sources and identification of non-tectonic artifacts, is necessary for the data to be used in formal inversions. The method of power density spectra is used to analyze noise as a function of frequency for several strainmeters in the PBO network. Preliminary work shows that the noise spectra obey a random walk model where the amplitude is proportional to f-2. The noise levels of these strainmeters are compared to each other and to closely located GPS stations in order to evaluate their ability to detect tectonic signals. We particularly focus our analysis of the time series for the August 2010 slow slip event in Washington State. Our initial analysis of the data suggests that the event originated under Puget Sound and propagated both to the north and south. A clear signal of approximately 0.10 microstrain can be seen in several strainmeters in the Olympic Peninsula area of the PBO network, including stations B003, B004, B005, B006, B007, B014 and B018. The temporal signal of the transient strain correlates with the timing and location of tremor activity associated with the slow-slip event. By calculating strain from the GPS displacement measurements, the magnitude and quality of

  11. Experimental Observation of a Periodically Oscillating Plasma Sphere in a Gridded Inertial Electrostatic Confinement Device

    SciTech Connect

    Park, J.; Nebel, R.A.; Stange, S.; Murali, S. Krupakar

    2005-07-01

    The periodically oscillating plasma sphere (POPS) [D. C. Barnes and R. A. Nebel, Phys. Plasmas 5, 2498 (1998).] oscillation has been observed in a gridded inertial electrostatic confinement device. In these experiments, ions in the virtual cathode exhibit resonant behavior when driven at the POPS frequency. Excellent agreement between the observed POPS resonance frequency and theoretical predictions has been observed for a wide range of potential well depths and for three different ion species. The results provide the first experimental validation of the POPS concept proposed by Barnes and Nebel [R. A. Nebel and D. C. Barnes, Fusion Technol. 34, 28 (1998).].

  12. Systematic observations of long-range transport events and climatological backscatter profiles with the DWD ceilometer network

    NASA Astrophysics Data System (ADS)

    Mattis, Ina; Müller, Gerhard; Wagner, Frank; Hervo, Maxime

    2015-04-01

    The German Meteorological Service (DWD) operates a network of about 60 CHM15K-Nimbus ceilometers for cloud base height observations. Those very powerful ceilometers allow for the detection and characterization of aerosol layers. Raw data of all network ceilometers are transferred online to DWD's data analysis center at the Hohenpeißenberg Meteorological Observatory. There, the occurrence of aerosol layers from long-range transport events in the free troposphere is systematically monitored on daily basis for each single station. If possible, the origin of the aerosol layers is determined manually from the analysis of the meteorological situation and model output. We use backward trajectories as well as the output of the MACC and DREAM models for the decision, whether the observed layer originated in the Sahara region, from forest fires in North America or from another, unknown source. Further, the magnitude of the observed layers is qualitatively estimated taking into account the geometrical layer depth, signal intensity, model output and nearby sun photometer or lidar observations (where available). All observed layers are attributed to one of the categories 'faint', 'weak', 'medium', 'strong', or 'extreme'. We started this kind of analysis in August 2013 and plan to continue this systematic documentation of long-range transport events of aerosol layers to Germany on long-term base in the framework of our GAW activities. Most of the observed aerosol layers have been advected from the Sahara region to Germany. In the 15 months between August 2013 and November 2014 we observed on average 46 days with Sahara dust layers per station, but only 16 days with aerosol layers from forest fires. The occurrence of Sahara dust layers vary with latitude. We observed only 28 dusty days in the north, close to the coasts of North Sea and Baltic Sea. In contrast, in southern Germany, in Bavarian Pre-Alps and in the Black Forest mountains, we observed up to 59 days with dust. At

  13. Statistical properties of quasi-periodic pulsations in white-light flares observed with Kepler

    NASA Astrophysics Data System (ADS)

    Pugh, C. E.; Armstrong, D. J.; Nakariakov, V. M.; Broomhall, A.-M.

    2016-07-01

    We embark on a study of quasi-periodic pulsations (QPPs) in the decay phase of white-light stellar flares observed by Kepler. Out of the 1439 flares on 216 different stars detected in the short-cadence data using an automated search, 56 flares are found to have pronounced QPP-like signatures in the light curve, of which 11 have stable decaying oscillations. No correlation is found between the QPP period and the stellar temperature, radius, rotation period and surface gravity, suggesting that the QPPs are independent of global stellar parameters. Hence they are likely to be the result of processes occurring in the local environment. There is also no significant correlation between the QPP period and flare energy, however there is evidence that the period scales with the QPP decay time for the Gaussian damping scenario, but not to a significant degree for the exponentially damped case. This same scaling has been observed for MHD oscillations on the Sun, suggesting that they could be the cause of the QPPs in those flares. Scaling laws of the flare energy are also investigated, supporting previous reports of a strong correlation between the flare energy and stellar temperature/radius. A negative correlation between the flare energy and stellar surface gravity is also found.

  14. Statistical Properties of Quasi-Periodic Pulsations in White-Light Flares Observed With Kepler

    NASA Astrophysics Data System (ADS)

    Pugh, C. E.; Armstrong, D. J.; Nakariakov, V. M.; Broomhall, A.-M.

    2016-04-01

    We embark on a study of quasi-periodic pulsations (QPPs) in the decay phase of white-light stellar flares observed by Kepler. Out of the 1439 flares on 216 different stars detected in the short-cadence data using an automated search, 56 flares are found to have pronounced QPP-like signatures in the light curve, of which 11 have stable decaying oscillations. No correlation is found between the QPP period and the stellar temperature, radius, rotation period and surface gravity, suggesting that the QPPs are independent of global stellar parameters. Hence they are likely to be the result of processes occurring in the local environment. There is also no significant correlation between the QPP period and flare energy, however there is evidence that the period scales with the QPP decay time for the Gaussian damping scenario, but not to a significant degree for the exponentially damped case. This same scaling has been observed for MHD oscillations on the Sun, suggesting that they could be the cause of the QPPs in those flares. Scaling laws of the flare energy are also investigated, supporting previous reports of a strong correlation between the flare energy and stellar temperature/radius. A negative correlation between the flare energy and stellar surface gravity is also found.

  15. Multi-spacecraft Observations and Transport Modeling of Energetic Electrons for a Series of Solar Particle Events in August 2010

    NASA Astrophysics Data System (ADS)

    Dröge, W.; Kartavykh, Y. Y.; Dresing, N.; Klassen, A.

    2016-08-01

    During 2010 August a series of solar particle events was observed by the two STEREO spacecraft as well as near-Earth spacecraft. The events, occurring on August 7, 14, and 18, originated from active regions 11093 and 11099. We combine in situ and remote-sensing observations with predictions from our model of three-dimensional anisotropic particle propagation in order to investigate the physical processes that caused the large angular spreads of energetic electrons during these events. In particular, we address the effects of the lateral transport of the electrons in the solar corona that is due to diffusion perpendicular to the average magnetic field in the interplanetary medium. We also study the influence of two coronal mass ejections and associated shock waves on the electron propagation, and a possible time variation of the transport conditions during the above period. For the August 18 event we also utilize electron observations from the MESSENGER spacecraft at a distance of 0.31 au from the Sun for an attempt to separate between radial and longitudinal dependencies in the transport process. Our modelings show that the parallel and perpendicular diffusion mean free paths of electrons can vary significantly not only as a function of the radial distance, but also of the heliospheric longitude. Normalized to a distance of 1 au, we derive values of λ ∥ in the range of 0.15–0.6 au, and values of λ ⊥ in the range of 0.005–0.01 au. We discuss how our results relate to various theoretical models for perpendicular diffusion, and whether there might be a functional relationship between the perpendicular and the parallel mean free path.

  16. EVOLUTIONARY TRACKS OF TRAPPED, ACCRETING PROTOPLANETS: THE ORIGIN OF THE OBSERVED MASS-PERIOD RELATION

    SciTech Connect

    Hasegawa, Yasuhiro; Pudritz, Ralph E. E-mail: pudritz@physics.mcmaster.ca

    2012-12-01

    The large number of observed exoplanets ({approx}>700) provides important constraints on their origin as deduced from the mass-period diagram of planets. The most surprising features in the diagram are (1) the (apparent) pileup of gas giants at a period of {approx}500 days ({approx}1 AU) and (2) the so-called mass-period relation, which indicates that planetary mass is an increasing function of orbital period. We construct the evolutionary tracks of growing planets at planet traps in evolving protoplanetary disks and show that they provide a good physical understanding of how these observational properties arise. The fundamental feature of our model is that inhomogeneities in protoplanetary disks give rise to multiple (up to 3) trapping sites for rapid (type I) planetary migration of planetary cores. The viscous evolution of disks results in the slow radial movement of the traps and their cores from large to small orbital periods. In our model, the slow inward motion of planet traps is coupled with the standard core accretion scenario for planetary growth. As planets grow, type II migration takes over. Planet growth and radial movement are ultimately stalled by the dispersal of gas disks via photoevaporation. Our model makes a number of important predictions: that distinct sub-populations of planets that reflect the properties of planet traps where they have grown result in the mass-period relation, that the presence of these sub-populations naturally explains a pileup of planets at {approx}1 AU, and that evolutionary tracks from the ice line do put planets at short periods and fill an earlier claimed {sup p}lanet desert{sup -}a sparse population of planets in the mass-semimajor axis diagram.

  17. Local Scale Radiobrightness Modelling during Intensive Observing Period-4 of the Cold Land Processes Experiment-1

    NASA Technical Reports Server (NTRS)

    Kim, Edward J.; Tedesco, Marco; deRoo, Roger; England, Anthony W.; Gu, Haoyu; Pham, Hanh; Boprie, David; Graf, Tobias; Koike, Toshio; Armstrong, Richard

    2004-01-01

    The NASA Cold Land Processes Field Experiment (CLPX-1) was designed to provide microwave remote sensing observations and ground truth for studies of snow and frozen ground remote sensing, particularly issues related to scaling. CLPX-1 was conducted in the spring of 2003 in Colorado, USA. Initial forward model validation work is concentrating on the Local-Scale Observation Site (LSOS), a 0.8 ha study site consisting of open meadows separated by trees where the most detailed measurements were made of snow depth and temperature, density, and grain size profiles. This paper will focus on the ability of forward Dense Medium Radiative Transfer (DMRT) modelling, combined with snowpack measurements to reproduce the radiobrightness signatures observed by the University of Michigan s Truck-Mounted Radiometer System at 19 and 37 GHz during the 4th Intensive Observing Period (IOP4) in March, 2003. Unlike the earlier IOP3, conditions during IOP4 include both wet and dry periods, providing a valuable test of DMRT model performance. Observations of upwelling and downwelling tree radiobrightness will be used to formulate a simple model for the effect of trees within the field of view. In addition, a comparison will be made for the one day of coincident observations by the University of Tokyo s Ground- Based Microwave Radiometer-7 (GBMR-7). These analyses will help guide the choice of future snow retrieval algorithms and the design of future Cold Lands observing systems.

  18. Coronal Waves and Solar Energetic Particle Events Observed at Widely Separate Locations

    NASA Astrophysics Data System (ADS)

    Nitta, N.; Jian, L.; Gomez-Herrero, R.

    2015-12-01

    During solar cycle 24, thanks largely to the Solar Terrestrial Relations Observatory (STEREO), many solar energetic particle (SEP) events have been observed at widely separate locations in the heliosphere, even including impulsive events that are usually assumed to reflect localized acceleration and injection. It is found that many of these wide SEP events accompany coronal waves that typically appear in extreme-ultraviolet (EUV) images. The EUV wave phenomenon has been observed much more closely than before by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory that continuously produces full-disk EUV images with unprecedentedly fast cadence and high sensitivity in multiple wavelength bands covering a broad temperature range. This is complemented by the EUV Imager on STEREO that traces the wave front into regions inaccessible from Earth. Several authors have attempted to explain wide SEP events in terms of EUV waves, especially comparing the SEP release times with how and when the EUV wave fronts traverse the magnetic footprints of the locations of SEPs. They have come to mixed results. The primary reason for the mixed results may be that they tend to overlook or underestimate the uncertainties inherent in the works. For example, how well do we model magnetic field connection in the corona and heliosphere? Do we adequately take into account the evolving solar wind conditions? Here we study a number of SEP events with various angular spreads in comparison with newly analyzed EUV waves. We discuss the importance of including the above-mentioned uncertainties as well as understanding EUV waves as part of the 3d propagation of CME-driven shock waves into the coronagraph fields of view. Without these approaches, it may remain ambiguous how much of the angular spread of SEP events is attributable to coronal shock waves.

  19. A TRANSITION REGION EXPLOSIVE EVENT OBSERVED IN He II WITH THE MOSES SOUNDING ROCKET

    SciTech Connect

    Fox, J. Lewis; Kankelborg, Charles C.; Thomas, Roger J. E-mail: kankel@solar.physics.montana.ed

    2010-08-20

    Transition region explosive events (EEs) have been observed with slit spectrographs since at least 1975, most commonly in lines of C IV (1548 A, 1550 A) and Si IV (1393 A, 1402 A). We report what we believe to be the first observation of a transition region EE in He II 304 A. With the Multi-Order Solar EUV Spectrograph (MOSES) sounding rocket, a novel slitless imaging spectrograph, we are able to see the spatial structure of the event. We observe a bright core expelling two jets that are distinctly non-collinear, in directions that are not anti-parallel. The jets have sky-plane velocities of order 75 km s{sup -1} and line-of-sight velocities of +75 km s{sup -1} (blue) and -30 km s{sup -1} (red). The core is a region of high non-thermal Doppler broadening, characteristic of EEs, with maximal broadening 380 km s{sup -1} FWHM. It is possible to resolve the core broadening into red and blue line-of-sight components of maximum Doppler velocities +160 km s{sup -1} and -220 km s{sup -1}. The event lasts more than 150 s. Its properties correspond to the larger, long-lived, and more energetic EEs observed in other wavelengths.

  20. Swift Follow-up Observations of Candidate Gravitational-wave Transient Events

    NASA Astrophysics Data System (ADS)

    Evans, P. A.; Fridriksson, J. K.; Gehrels, N.; Homan, J.; Osborne, J. P.; Siegel, M.; Beardmore, A.; Handbauer, P.; Gelbord, J.; Kennea, J. A.; Smith, M.; Zhu, Q.; LIGO Scientific Collaboration; Virgo Collaboration; Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Ast, S.; Aston, S. M.; Astone, P.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P.; Ballardin, G.; Ballmer, S.; Bao, Y.; Barayoga, J. C. B.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Beck, D.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Benacquista, M.; Berliner, J. M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bhadbade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biswas, R.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Blom, M.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bond, C.; Bondarescu, R.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bouhou, B.; Braccini, S.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burguet-Castell, J.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chalermsongsak, T.; Charlton, P.; Chassande-Mottin, E.; Chen, W.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chua, S. S. Y.; Chung, C. T. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Clayton, J. H.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colacino, C. N.; Colla, A.; Colombini, M.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M.; Coulon, J.-P.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, R. M.; Dahl, K.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Dent, T.; Dergachev, V.; DeRosa, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Emilio, M. Di Paolo; Di Virgilio, A.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorsher, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Eikenberry, S.; Endrőczi, G.; Engel, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Farr, B. F.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franc, J.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M. A.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P. J.; Fyffe, M.; Gair, J.; Galimberti, M.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gáspár, M. E.; Gelencser, G.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; González, G.; Gorodetsky, M. L.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gupta, R.; Gustafson, E. K.; Gustafson, R.; Hallam, J. M.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Hayau, J.-F.; Heefner, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Herrera, V.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Hough, J.; Howell, E. J.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Izumi, K.; Jacobson, M.; James, E.; Jang, Y. J.; Jaranowski, P.; Jesse, E.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Keitel, D.; Kelley, D.; Kells, W.; Keppel, D. G.; Keresztes, Z.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, H.; Kim, K.; Kim, N.; Kim, Y. M.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kurdyumov, R.; Kwee, P.; Lam, P. K.; Landry, M.; Langley, A.; Lantz, B.; Lastzka, N.; Lawrie, C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Leong, J. R.; Leonor, I.; Leroy, N.; Letendre, N.; Lhuillier, V.; Li, J.; Li, T. G. F.; Lindquist, P. E.; Litvine, V.; Liu, Y.; Liu, Z.; Lockerbie, N. A.; Lodhia, D.; Logue, J.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Lubinski, M.; Lück, H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Masserot, A.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McDaniel, P.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meadors, G. D.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Menéndez, D. F.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Moraru, D.; Moreno, G.; Morgado, N.; Morgia, A.; Mori, T.; Morriss, S. R.; Mosca, S.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Müller-Ebhardt, H.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nash, T.; Naticchioni, L.; Necula, V.; Nelson, J.; Neri, I.; Newton, G.; Nguyen, T.; Nishizawa, A.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Oldenberg, R. G.; O'Reilly, B.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Page, A.; Palladino, L.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Paoletti, R.; Papa, M. A.; Parisi, M.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Penn, S.; Perreca, A.; Persichetti, G.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pihlaja, M.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Poggiani, R.; Pöld, J.; Postiglione, F.; Poux, C.; Prato, M.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Rakhmanov, M.; Ramet, C.; Rankins, B.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Roberts, M.; Robertson, N. A.; Robinet, F.; Robinson, C.; Robinson, E. L.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Rolland, L.; Rollins, J. G.; Romano, J. D.; Romano, R.; Romie, J. H.; Rosińska, D.; Röver, C.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sankar, S.; Sannibale, V.; Santamaría, L.; Santiago-Prieto, I.; Santostasi, G.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R. L.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sentenac, D.; Sergeev, A.; Shaddock, D. A.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Somiya, K.; Sorazu, B.; Speirits, F. C.; Sperandio, L.; Stefszky, M.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S. E.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sung, M.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.; Taffarello, L.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Thüring, A.; Titsler, C.; Tokmakov, K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.; Tournefier, E.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Vahlbruch, H.; Vajente, G.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van Veggel, A. A.; Vass, S.; Vasuth, M.; Vaulin, R.; Vavoulidis, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Villar, A. E.; Vinet, J.-Y.; Vitale, S.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Wallace, L.; Wan, Y.; Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wiesner, K.; Wilkinson, C.; Willems, P. A.; Williams, L.; Williams, R.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wiseman, A. G.; Wittel, H.; Woan, G.; Wooley, R.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yamamoto, K.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, F.; Zhang, L.; Zhao, C.; Zotov, N.; Zucker, M. E.; Zweizig, J.

    2012-12-01

    We present the first multi-wavelength follow-up observations of two candidate gravitational-wave (GW) transient events recorded by LIGO and Virgo in their 2009-2010 science run. The events were selected with low latency by the network of GW detectors (within less than 10 minutes) and their candidate sky locations were observed by the Swift observatory (within 12 hr). Image transient detection was used to analyze the collected electromagnetic data, which were found to be consistent with background. Off-line analysis of the GW data alone has also established that the selected GW events show no evidence of an astrophysical origin; one of them is consistent with background and the other one was a test, part of a "blind injection challenge." With this work we demonstrate the feasibility of rapid follow-ups of GW transients and establish the sensitivity improvement joint electromagnetic and GW observations could bring. This is a first step toward an electromagnetic follow-up program in the regime of routine detections with the advanced GW instruments expected within this decade. In that regime, multi-wavelength observations will play a significant role in completing the astrophysical identification of GW sources. We present the methods and results from this first combined analysis and discuss its implications in terms of sensitivity for the present and future instruments.

  1. Swift Follow-Up Observations of Candidate Gravitational-Wave Transient Events

    NASA Technical Reports Server (NTRS)

    Evans, P. A.; Fridriksson, J. K.; Gehrels, N.; Homan, J.; Osborne, J. P.; Siegel, M.; Beardmore, A.; Handbauer, P.; Gelbord, J.; Kennea, J. A.; Smith, M.; Zhu, Q.; Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Blackburn, J. K.; Camp, J. B.; Kanner, J. B.

    2012-01-01

    We present the first multi-wavelength follow-up observations of two candidate gravitational-wave (GW) transient events recorded by LIGO and Virgo in their 2009-2010 science run. The events were selected with low latency by the network of GW detectors (within less than 10 minutes) and their candidate sky locations were observed by the Swift observatory (within 12 hr). Image transient detection was used to analyze the collected electromagnetic data, which were found to be consistent with background. Off-line analysis of the GW data alone has also established that the selected GW events show no evidence of an astrophysical origin; one of them is consistent with background and the other one was a test, part of a "blind injection challenge." With this work we demonstrate the feasibility of rapid follow-ups of GW transients and establish the sensitivity improvement joint electromagnetic and GW observations could bring. This is a first step toward an electromagnetic follow-up program in the regime of routine detections with the advanced GW instruments expected within this decade. In that regime, multi-wavelength observations will play a significant role in completing the astrophysical identification of GW sources. We present the methods and results from this first combined analysis and discuss its implications in terms of sensitivity for the present and future instruments.

  2. Total Lightning Observations of Extreme Weather Events over the Contiguous United States

    NASA Technical Reports Server (NTRS)

    Carey, Lawrence D.; Petersen, Walter A.; Christian, Hugh J.

    2008-01-01

    The overall objective is to investigate total lightning characteristics of extreme weather events over the contiguous United States (CONUS) using TRMM (Tropical Rainfall Measuring Mission) LIS (Lightning Image Sensor) and OTD (Optical Transient Detector) satellite observations. A large LIS (10+ years) and OTD (5 years) data base is available to study the instantaneous total or cloud-to-ground (CG) plus intracloud (IC) lightning characteristics of extreme weather events. More specifically, the LIS and OTD data are combined with National Lightning Detection Network (NLDN) observations to examine the total and CG lightning flash rate and density, the IC:CG ratio, and positive CG percentage. These instantaneous lightning characteristics can be used for basic science studies to better understand the physical and dynamical linkages between lightning and precipitation and their environmental controls. They can also provide a first-look of extreme weather events leading up to future satellite observations (e.g., NOAA GOES-R Geostationary Lightning Mapper [GLM]) for use in climate studies and the short-term prediction and warning process. Extreme weather events are defined by the NOAA Storm Data reports of tornadoes, large hail (at least 0.75 inch) and strong straight-line winds (at least 50 kts). Over CONUS, there are over 70,000 severe storm reports in the TRMM spatial domain (< 35 N) from 1998-2007 and over 100,000 storm reports in the OTD spatial domain (5/1995-4/2000). Temporal co-location is on the order of 1% (i.e., 1000 s of coincident overpasses), providing a statistically significant sample of instantaneous total lightning properties. This instantaneous behavior of lightning in extreme weather is then compared to that of typical thunderstorm events, or randomly sampled LIS/OTD events in which the extreme events have been eliminated from the population. Results describing the instantaneous behavior of total lightning within a large sample of extreme and typical

  3. Long-period events, the most characteristic seismicity accompanying the emplacement and extrusion of a lava dome in Galeras Volcano, Colombia, in 1991

    USGS Publications Warehouse

    Gil, Cruz F.; Chouet, B.A.

    1997-01-01

    Since its reactivation in 1988 the principal eruptions of Galeras Volcano occurred on May 4-9, 1989, July 16, 1992, and January 14, March 23, April 3, April 14 and June 7, 1993. The initial eruption was a phreatic event which clearly marked a new period of activity. A lava dome was extruded within the main crater in October 1991 and subsequently destroyed in an explosive eruption on July 16, 1992. The eruptions that followed were all vulcanian-type explosions. The seismicity accompanying the emplacement, extrusion, and destruction of the lava dome was dominated by a mix of long-period (LP) events and tremor displaying a variety of waveforms. Repetitive LP events with dominant periods in the range 0.2-1 s were observed in October and November 1991 and visually correlated with short energetic pulses of gas venting through a crack bisecting the dome surface. Each LP event was characterized by a weak precursory signal with dominant periods in the range 0.05-0.1 s lasting roughly 7 s. Using the fluid-driven crack model of Chouet (1988, 1992), we infer that two distinct cracks may have acted as sources for the LP and precursor signals. Spectral analyses of the data yield the following parameters for the LP source: crack length, 240-360 m; crack width, 130-150 m; crack aperture, 0.5-3.4 mm; crack stiffness, 100-500; sound speed of fluid, 880 m/s; and excess pressure, 0.01-0.19 MPa. Similar analyses yield the parameters of the precursor source: crack length, 20-30 m; crack width, 15-25 m; crack aperture, 2.3-8.7 mm; crack stiffness, 5-15; sound speed of fluid, 140 m/s; and excess pressure, 0.06-0.15 MPa. Combined with geologic and thermodynamic constraints obtained from field observations, these seismic parameters suggest a gas-release mechanism in which the episodic collapse of a foam layer trapped at the top of the magma column subjacent to the dome releases a slug of pressurized gas which escapes to the surface while dilating a preexisting system of cracks in the dome

  4. IMAGING OBSERVATIONS OF QUASI-PERIODIC PULSATIONS IN SOLAR FLARE LOOPS WITH SDO/AIA

    SciTech Connect

    Su, J. T.; Mao, X. J.; Shen, Y. D.; Liu, Y.

    2012-08-20

    Quasi-periodic pulsations (QPPs) of flaring emission with periods from a few seconds to tens of minutes have been widely detected from radio bands to {gamma}-ray emissions. However, in the past the spatial information of pulsations could not be utilized well due to the instrument limits. We report here imaging observations of the QPPs in three loop sections during a C1.7 flare with periods of P = 24 s-3 minutes by means of the extreme-ultraviolet 171 A channel of the Atmospheric Imaging Assembly (AIA) instrument on board the Solar Dynamics Observatory. We confirm that the QPPs with the shortest period of 24 s were not of an artifact produced by the Nyquist frequency of the AIA 12 s cadence. The QPPs in the three loop sections were interconnected and closely associated with the flare. The detected perturbations propagated along the loops at speeds of 65-200 km s{sup -1}, close to those of acoustic waves in them. The loops were made up of many bright blobs arranged in alternating bright and dark changes in intensity (spatial periodical distribution) with the wavelengths 2.4-5 Mm (as if they were magnetohydrodynamic waves). Furthermore, in the time-distance diagrams, the detected perturbation wavelengths of the QPPs are estimated to be {approx}10 Mm, which evidently do not fit the above ones of the spatial periodic distributions and produce a difference of a factor of 2-4 with them. It is suggested that the short QPPs with periods P < 60 s were possibly sausage-mode oscillations and the long QPPs with periods P > 60 s were the higher (e.g., >2nd) harmonics of slow magnetoacoustic waves.

  5. OBSERVATIONS OF A TWO-STAGE SOLAR ERUPTIVE EVENT (SEE): EVIDENCE FOR SECONDARY HEATING

    SciTech Connect

    Su Yang; Dennis, Brian R.; Holman, Gordon D.; Wang, Tongjiang; Chamberlin, Phillip C.; Savage, Sabrina; Veronig, Astrid

    2012-02-10

    We present RHESSI, SDO/AIA, SOHO/LASCO, STEREO, and GOES observations of a partially occulted solar eruptive event that occurred at the southwest limb on 2011 March 8. The GOES X-ray light curve shows two peaks separated by almost 2 hr that we interpret as two stages of a single event associated with the delayed eruption of a coronal mass ejection (CME). A hot flux rope formed during the first stage and continued expanding and rising throughout the event. The speed of the flux rope decreased from {approx}120 to 14 km s{sup -1} during the decay phase of the first stage and increased again during the second stage to become the CME with a speed of {approx}516 km s{sup -1}. RHESSI and GOES data analyses show that the plasma temperature reached over 20 MK in the first stage, then decreased to {approx}10 MK and increased to 15 MK in the second stage. This event provides clear evidence for a secondary heating phase. The enhanced EUV and X-ray emission came from the high corona ({approx}60 arcsec above the limb) in the second stage, {approx}40 arcsec higher than the site of the initial flare emission. STEREO-A on-disk observations indicate that the post-flare loops during this stage were of larger scale sizes and spatially distinct from those in the first stage.

  6. Genoa 2014 flash flood event: from precipitation observations to flood mapping

    NASA Astrophysics Data System (ADS)

    Rebora, Nicola; Fiorini, Mattia; Gabellani, Simone; Parodi, Antonio; Pignone, Flavio; Rudari, Roberto; Silvestro, Francesco

    2015-04-01

    On the 9th of October, the city of Genoa, the capital of the Liguria Region, located at the meridional edge of the local Appennines range was gutted by an extreme rainfall event with up to 300 millimeters of rain in 5 hours. Only three years ago an anomalous intense rainstorm ripped through the Liguria Region and inflicted serious damage at the city of Genoa. The raingauge stations, in the center of the event, registered up to 450 millimetres of rain in 5 hours (7 km from the coast over a 300 m hill), a third of the average annual rainfall, with a peak of 150 mm in one hour. Six people were killed. With this work we analyze the Genoa 2014 Flash Flood in terms of precipitation observations by radar and raingauges, in terms of hydrological response of the Bisagno river using the Continuum hydrological model, and in terms of urban flooding in the city center using a 2D hydraulic model. Our aim is twofold: from one side we want to present the event through the observational data and through the simulations available, and on the other side we want to discuss the steps we can do in managing such events in a densely populated area.

  7. Observations of a Two-Stage Solar Eruptive Event (SEE): Evidence for Secondary Heating

    NASA Technical Reports Server (NTRS)

    Su, Yang; Dennis, Brian R.; Holman, Gordon D.; Wang, Tongjiang; Chamberlin, Phillip C.; Savage, Sabrina; Veronig, Astrid

    2012-01-01

    We present RHESSI, SDO/AIA, SOHO/LASCO, STEREO, and GOES observations of a partially occulted solar eruptive event (SEE) that occurred at the South-West limb on 8 March, 2011. The GOES X-ray light curve shows two peaks separated by almost two hours that we interpret as two stages of a single event associated with the delayed eruption of a CME. A hot flux rope formed during the first stage and continued expanding and rising throughout the event. The speed of the flux rope decreased from approx.120 to 14 km/s during the decay phase of the first stage and increased again during the second stage to become the CME with a speed of approx.516 km/s. RHESSI and GOES data analyses show that the plasma temperature reached over 20 MK in the first stage, then decreased to approx.10 MK and increased to 15 MK in the second stage. This event provides clear evidence for a secondary heating phase. The enhanced EUV and X-ray emission came from the high corona ( approx.60 arcsec above the limb) in the second stage, approx.40 arcsec higher than the site of the initial flare emission. STEREO-A on-disk observations indicate that the post-flare loops during this stage were of larger scale sizes and spatially distinct from those in the first stage.

  8. Coordinated Einstein and IUE observations of a disparitions brusques type flare event and quiescent emission from Proxima Centauri

    NASA Technical Reports Server (NTRS)

    Haisch, B. M.; Linsky, J. L.; Bornmann, P. L.; Stencel, R. E.; Antiochos, S. K.; Golub, L.; Vaiana, G. S.

    1983-01-01

    The Einstein Imaging Particle Counter observed a major X-ray flare in its entirety during a 5-hr period of simultaneous observations, with the IUE, of the dM5e flare star Proxima Centauri in August, 1980. The detailed X-ray light curve, temperature determinations during various intervals, and UV line fluxes obtained before, during, and after the flare indirectly indicate a 'two-ribbon flare' prominence eruption. The calculated ratio of coronal to bolometric luminosity for the event is about 100 times the solar ratio. The Proxima Cen corona is analyzed in the context of static loop models, in light of which it is concluded that less than 6% of the stellar surface seems to be covered by X-ray emitting active regions.

  9. Video camera observation for assessing overland flow patterns during rainfall events

    NASA Astrophysics Data System (ADS)

    Silasari, Rasmiaditya; Oismüller, Markus; Blöschl, Günter

    2015-04-01

    Physically based hydrological models have been widely used in various studies to model overland flow propagation in cases such as flood inundation and dam break flow. The capability of such models to simulate the formation of overland flow by spatial and temporal discretization of the empirical equations makes it possible for hydrologists to trace the overland flow generation both spatially and temporally across surface and subsurface domains. As the upscaling methods transforming hydrological process spatial patterns from the small obrseved scale to the larger catchment scale are still being progressively developed, the physically based hydrological models become a convenient tool to assess the patterns and their behaviors crucial in determining the upscaling process. Related studies in the past had successfully used these models as well as utilizing field observation data for model verification. The common observation data used for this verification are overland flow discharge during natural rainfall events and camera observations during synthetic events (staged field experiments) while the use of camera observations during natural events are hardly discussed in publications. This study advances in exploring the potential of video camera observations of overland flow generation during natural rainfall events to support the physically based hydrological model verification and the assessment of overland flow spatial patterns. The study is conducted within a 64ha catchment located at Petzenkirchen, Lower Austria, known as HOAL (Hydrological Open Air Laboratory). The catchment land covers are dominated by arable land (87%) with small portions (13%) of forest, pasture and paved surfaces. A 600m stream is running at southeast of the catchment flowing southward and equipped with flumes and pressure transducers measuring water level in minutely basis from various inlets along the stream (i.e. drainages, surface runoffs, springs) to be calculated into flow discharge. A

  10. Effects of Periodically Repeated Heat Events on Reproduction and Ovary Development of Agasicles hygrophila (Coleoptera: Chrysomelidae).

    PubMed

    Zhao, Mei-Ting; Wang, Yao; Zhou, Zhong-Shi; Wang, Ren; Guo, Jian-Ying; Wan, Fang-Hao

    2016-08-01

    Insect development occurs within a specific temperature range. Constant temperature studies may produce misleading information on the eco-physiological impacts of temperature on the population dynamics of an insect species, as in most natural environments, temperature usually undergoes daily variation. In China, field surveys showed that the decline in the Agasicles hygrophila (Selman & Vogt) (Coleoptera: Chrysomelidae) population from early August to late September in summer resulted in difficulties in effectively controlling the population of Alternanthera philoxeroides (Mart.) Griseb (Amaranthaceae). Previous studies have largely ignored more natural, fluctuating conditions. In our study, we first investigated the impacts of different temperature conditions (25°C constant temperature for 20 h with a 4-h period of a high temperature of either 30°C, 33°C, 36°C, or 39°C) on adult reproduction and longevity, egg development time, egg hatch rate, female ovarian development, and oogenesis of A. hygrophila. Our results indicated that high temperatures of 30°C and 33°C did not affect the female ovarian development and oogenesis of A. hygrophila Contrarily, high temperatures of 36°C and 39°C negatively affected the population development of A. hygrophila. At 36°C and 39°C, the egg hatch rates were very low, and the egg development times significantly lengthened. The frequency of abnormal ovaries significantly rose at 39°C. We concluded that the decline in the A. hygrophila population during August and September may be related to the extreme high temperatures that frequently occur in summer. These results help provide a better understanding of A. hygrophila population dynamics under natural conditions. PMID:27270575

  11. VizieR Online Data Catalog: Observed Periods of Ap and Bp stars (Catalano+ 1998)

    NASA Astrophysics Data System (ADS)

    Catalano, F. A.; Renson, P.

    1997-11-01

    A catalogue of all the periods published up to 31 October 1996 on 364 CP stars is presented; it supersedes the previous version (catalog ). The paper version (catalog.tex) is arranged in three tables: the bulk of the data, i.e. those referring to CP2, CP3, and CP4 stars, are given in Table 1, while the data concerning He-strong stars are given in Table 2 and those for eclipsing or ellipsoidal variables are collected in Table 3. Notes are also provided at the end of each table, mainly about duplicities. The machine-readable version was arranged in two main parts: the main parameters of the 364 stars (identifiers and names, positions, spectral types, magnitudes and peculiarities) are tabulated in the file 'stars'; periods and the of the observed variations (light, spectrum, magnetic field, etc.) are listed in the 'periods' file. Two other files contains the notes and the references. (5 data files).

  12. Observations of narrow bipolar events reveal how lightning is initiated in thunderstorms

    PubMed Central

    Rison, William; Krehbiel, Paul R.; Stock, Michael G.; Edens, Harald E.; Shao, Xuan-Min; Thomas, Ronald J.; Stanley, Mark A.; Zhang, Yang

    2016-01-01

    A long-standing but fundamental question in lightning studies concerns how lightning is initiated inside storms, given the absence of physical conductors. The issue has revolved around the question of whether the discharges are initiated solely by conventional dielectric breakdown or involve relativistic runaway electron processes. Here we report observations of a relatively unknown type of discharge, called fast positive breakdown, that is the cause of high-power discharges known as narrow bipolar events. The breakdown is found to have a wide range of strengths and is the initiating event of numerous lightning discharges. It appears to be purely dielectric in nature and to consist of a system of positive streamers in a locally intense electric field region. It initiates negative breakdown at the starting location of the streamers, which leads to the ensuing flash. The observations show that many or possibly all lightning flashes are initiated by fast positive breakdown. PMID:26876654

  13. Observations of narrow bipolar events reveal how lightning is initiated in thunderstorms

    DOE PAGESBeta

    Rison, William; Krehbiel, Paul R.; Stock, Michael G.; Edens, Harald E.; Shao, Xuan-Min; Thomas, Ronald J.; Stanley, Mark A.; Zhang, Yang

    2016-02-15

    A long-standing but fundamental question in lightning studies concerns how lightning is initiated inside storms, given the absence of physical conductors. The issue has revolved around the question of whether the discharges are initiated solely by conventional dielectric breakdown or involve relativistic runaway electron processes. Here we report observations of a relatively unknown type of discharge, called fast positive breakdown, that is the cause of high-power discharges known as narrow bipolar events. We find that the breakdown has a wide range of strengths and is the initiating event of numerous lightning discharges. It appears to be purely dielectric in naturemore » and to consist of a system of positive streamers in a locally intense electric field region. It initiates negative breakdown at the starting location of the streamers, which leads to the ensuing flash. The observations show that many or possibly all lightning flashes are initiated by fast positive breakdown.« less

  14. Acceleration of a static observer near the event horizon of a static isolated black hole

    NASA Astrophysics Data System (ADS)

    Doughty, Noel A.

    1981-05-01

    The magnitude of the proper acceleration of a static observer (or test particle) in a static, isolated, spherically symmetric space-time region is compared with the Newtonian result including the situation in the interior of a perfect-fluid star. The calculation shows that the proper acceleration diverges on the event horizon of a spherically symmetric black hole. The 'surface gravity' of a spherically symmetric black hole, as used in descriptions of the Hawking radiation, is then explicitly related to the accelerations of such static observers, thus providing a simple physical interpretation of the surface gravity and illustrating the global (nonlocal) nature of the event horizon. The calculations are presented in the SI physical equations used almost exclusively by many students and teachers of physics.

  15. Events related to lithosphere-atmosphere-ionosphere-magnetosphere coupling observed by DEMETER

    NASA Astrophysics Data System (ADS)

    Parrot, Michel; Hattori, Katsumi; Liu, Tiger; Namgaladze, Alexander; Ouzounov, Dimitar; Pulinets, Sergey; Tramutoli, Valerio

    2015-04-01

    There are several models of Lithosphere-Atmosphere-Ionosphere-Magnetosphere (LAIM) coupling to explain ionospheric perturbations which are observed prior to earthquakes. In 2013 an ISSI Team led by S. Pulinets (RU) and D. Ouzounov (US) started to work with the following aim: "Multi-instrument Space-Borne Observations and Validation of the Physical Model of the LAIM Coupling" (see http://www.issibern.ch/teams/spaceborneobserve/). In the frame of this model validation several events have been studied with the DEMETER satellite data. It concerns the effects of (i) the ancient natural nuclear reactor located at Oklo (Gabon), (ii) the sand storms in Sahara, (iii) the volcanic activity, (iv) the lightning activity, and (v) the hurricanes. The main signature of these events in the ionosphere will be shown in this presentation.

  16. Observations of narrow bipolar events reveal how lightning is initiated in thunderstorms

    NASA Astrophysics Data System (ADS)

    Rison, William; Krehbiel, Paul R.; Stock, Michael G.; Edens, Harald E.; Shao, Xuan-Min; Thomas, Ronald J.; Stanley, Mark A.; Zhang, Yang

    2016-02-01

    A long-standing but fundamental question in lightning studies concerns how lightning is initiated inside storms, given the absence of physical conductors. The issue has revolved around the question of whether the discharges are initiated solely by conventional dielectric breakdown or involve relativistic runaway electron processes. Here we report observations of a relatively unknown type of discharge, called fast positive breakdown, that is the cause of high-power discharges known as narrow bipolar events. The breakdown is found to have a wide range of strengths and is the initiating event of numerous lightning discharges. It appears to be purely dielectric in nature and to consist of a system of positive streamers in a locally intense electric field region. It initiates negative breakdown at the starting location of the streamers, which leads to the ensuing flash. The observations show that many or possibly all lightning flashes are initiated by fast positive breakdown.

  17. Observations of narrow bipolar events reveal how lightning is initiated in thunderstorms.

    PubMed

    Rison, William; Krehbiel, Paul R; Stock, Michael G; Edens, Harald E; Shao, Xuan-Min; Thomas, Ronald J; Stanley, Mark A; Zhang, Yang

    2016-01-01

    A long-standing but fundamental question in lightning studies concerns how lightning is initiated inside storms, given the absence of physical conductors. The issue has revolved around the question of whether the discharges are initiated solely by conventional dielectric breakdown or involve relativistic runaway electron processes. Here we report observations of a relatively unknown type of discharge, called fast positive breakdown, that is the cause of high-power discharges known as narrow bipolar events. The breakdown is found to have a wide range of strengths and is the initiating event of numerous lightning discharges. It appears to be purely dielectric in nature and to consist of a system of positive streamers in a locally intense electric field region. It initiates negative breakdown at the starting location of the streamers, which leads to the ensuing flash. The observations show that many or possibly all lightning flashes are initiated by fast positive breakdown. PMID:26876654

  18. OBSERVATIONS OF SOLAR ENERGETIC PARTICLES FROM {sup 3}He-RICH EVENTS OVER A WIDE RANGE OF HELIOGRAPHIC LONGITUDE

    SciTech Connect

    Wiedenbeck, M. E.; Mason, G. M.; Haggerty, D. K; Cohen, C. M. S.; Nitta, N. V.; Gomez-Herrero, R.

    2013-01-01

    A prevailing model for the origin of {sup 3}He-rich solar energetic particle (SEP) events attributes particle acceleration to processes associated with the reconnection between closed magnetic field lines in an active region and neighboring open field lines. The open field from the small reconnection volume then provides a path along which accelerated particles escape into a relatively narrow range of angles in the heliosphere. The narrow width (standard deviation <20 Degree-Sign ) of the distribution of X-ray flare longitudes found to be associated with {sup 3}He-rich SEP events detected at a single spacecraft at 1 AU supports this model. We report multispacecraft observations of individual {sup 3}He-rich SEP events that occurred during the solar minimum time period from 2007 January through 2011 January using instrumentation carried by the two Solar Terrestrial Relations Observatory spacecraft and the Advanced Composition Explorer. We find that detections of {sup 3}He-rich events at pairs of spacecraft are not uncommon, even when their longitudinal separation is >60 Degree-Sign . We present the observations of the {sup 3}He-rich event of 2010 February 7, which was detected at all three spacecraft when they spanned 136 Degree-Sign in heliographic longitude. Measured fluences of {sup 3}He in this event were found to have a strong dependence on longitude which is well fit by a Gaussian with standard deviation {approx}48 Degree-Sign centered at the longitude that is connected to the source region by a nominal Parker spiral magnetic field. We discuss several mechanisms for distributing flare-accelerated particles over a wide range of heliographic longitudes including interplanetary diffusion perpendicular to the magnetic field, spreading of a compact cluster of open field lines between the active region and the source surface where the field becomes radial and opens out into the heliosphere, and distortion of the interplanetary field by a preceding coronal mass

  19. IRIS observations and MHD simulations of explosive events in the transition region of the Sun

    NASA Astrophysics Data System (ADS)

    Guo, Lijia; Innes, Davina; Huang, Yi-Min; Bhattacharjee, Amitava

    2016-05-01

    Small-scale explosive events on the Sun are thought to be related to magnetic reconnection. While Petschek reconnection has been considered as a reconnection mechanism for explosive events on the Sun for quite a long time, the fragmentation of a current sheet in the high-Lundquist-number regime caused by the plasmoid instability has recently been proposed as a possible mechanism for fast reconnection. The actual reconnection sites are too small to be resolved with images but these reconnection mechanisms, Petschek and the plasmoid instability, have very different density and velocity structures and so can be distinguished by high-resolution line profiles observations. We use high-resolution sit-and-stare spectral observations of the Si IV line, obtained by the IRIS spectrometer, to identify sites of reconnection, and follow the development of line profiles. The aim is to obtain a survey of typical line profiles produced by small-scale reconnection events in the transition region and compare them with synthetic line profiles from numerical simulations of a reconnecting current sheet to determine whether reconnection occurs via the plasmoid instabilty or the Petschek mechanism. Direct comparison between IRIS observations and numerical results suggests that the observed Si IV profiles can be reproduced with a fragmented current layer subject to plasmoid instability but not by bi-directional jets that characterise the Petschek mechanism. This result suggests that if these small-scale events are reconnection sites, then fast reconnection proceeds via the plasmoid instability, rather than the Petschek mechanism during small-scale reconnection on the Sun.

  20. Elemental GCR Observations during the 2009-2010 Solar Minimum Period

    NASA Technical Reports Server (NTRS)

    Lave, K. A.; Israel, M. H.; Binns, W. R.; Christian, E. R.; Cummings, A. C.; Davis, A. J.; deNolfo, G. A.; Leske, R. A.; Mewaldt, R. A.; Stone, E. C.; vonRosenvinge, T. T.; Wiedenbeck, M. E.

    2013-01-01

    Using observations from the Cosmic Ray Isotope Spectrometer (CRIS) onboard the Advanced Composition Explorer (ACE), we present new measurements of the galactic cosmic ray (GCR) elemental composition and energy spectra for the species B through Ni in the energy range approx. 50-550 MeV/nucleon during the record setting 2009-2010 solar minimum period. These data are compared with our observations from the 1997-1998 solar minimum period, when solar modulation in the heliosphere was somewhat higher. For these species, we find that the intensities during the 2009-2010 solar minimum were approx. 20% higher than those in the previous solar minimum, and in fact were the highest GCR intensities recorded during the space age. Relative abundances for these species during the two solar minimum periods differed by small but statistically significant amounts, which are attributed to the combination of spectral shape differences between primary and secondary GCRs in the interstellar medium and differences between the levels of solar modulation in the two solar minima. We also present the secondary-to-primary ratios B/C and (Sc+Ti+V)/Fe for both solar minimum periods, and demonstrate that these ratios are reasonably well fit by a simple "leaky-box" galactic transport model that is combined with a spherically symmetric solar modulation model.

  1. Ten-year transient luminous events and Earth observations of FORMOSAT-2

    NASA Astrophysics Data System (ADS)

    Chern, Rock Jeng-Shing; Lin, Shin-Fa; Wu, An-Ming

    2015-07-01

    The purpose of this paper is to summarize the enormous contributions of FS2 (FORMOSAT-2 or Formosa satellite #2) in both Earth and transient luminous events (TLEs) observations in 10 years. As a small satellite operated for 10 years (20 May 2004 to 20 May 2014) in orbit, FS2 keeps its two unique characteristics: (1) to orbit 14 revolutions around the Earth per day with daily revisit capability, and (2) to provide the capabilities of Earth observation in sunlight time and TLEs observation in eclipsed time every day. It carries two payloads: the remote sensing instrument (RSI) for Earth imaging in satellite's day time and the imager of sprites and upper atmospheric lightning instrument (ISUAL) for scientific observations in satellite's night time, respectively. Daily revisit capability provides changes of events on Earth in either short time (several days) or long term (several years). Examples include: Indian Ocean earthquake and tsunami (December 2004), disintegration of Wilkins Ice Shelf in Antarctica region (2006-2014, long term), Sichuan earthquake (May 2008), Tohoku earthquake and tsunami (March 2011), polar regions (2006-2014, long term), etc. In the TLEs observation, ISUAL had recorded more than 35,000 events in 10 years with 73.93% elves, 6.54% red sprites, 5.81% halos, 13.42% blue jets and 0.30% gigantic jets. Major contributions of FS2 in this specific scientific area are presented. In particular, current and future research topics on TLEs are discussed. Also, major contributions of FS2's RSI to the United Nations Institute for Training and Research (UNITAR) Operational Satellite Applications Programme (UNOSAT) and Group of Earth Observation System of Systems (GEOSS) are summarized. This paper also addresses briefly the health status of FS2 after working 10 years in orbit.

  2. Implications of the observed distributions of very long period comet orbits

    NASA Astrophysics Data System (ADS)

    Harrington, R. S.

    1985-01-01

    It is argued that the calculations of Van Flandern (1977), and Byl (1983) seriously underestimate the effects of galactic perturbations on the distributions and orientations of very-long-period comets. Revised calculations are given which take into account the effects of galactic perturbation and observational error. It is shown that the revised calculations are consistent with a uniform distribution of comets within the Oort Cloud.

  3. Reconstructing Methane Emission Events in the Arctic Ocean: Observations from the Past to Present

    NASA Astrophysics Data System (ADS)

    Panieri, G.; Mienert, J.; Fornari, D. J.; Torres, M. E.; Lepland, A.

    2015-12-01

    Methane hydrates are ice-like crystals that are present along continental margins, occurring in the pore space of deep sediments or as massive blocks near the seafloor. They form in high pressure and low temperature environments constrained by thermodynamic stability, and supply of methane. In the Arctic, gas hydrates are abundant, and the methane released by their destabilization can affect local to global carbon budgets and cycles, ocean acidification, and benthic community survival. With the aim to locate in space and time the periodicity of methane venting, CAGE is engaged in a vast research program in the Arctic, a component of which comprises the analyses of numerous sediment cores and correlative geophysical and geochemical data from different areas. Here we present results from combined analyses of biogenic carbonate archives along the western Svalbard Margin, which reveal past methane venting events in this region. The reconstruction of paleo-methane discharge is complicated by precipitation of secondary carbonate on foraminifera shells, driven by an increase in alkalinity during anaerobic oxidation of methane (AOM). The biogeochemical processes involved in methane cycling and processes that drive methane migration affect the depth where AOM occurs, with relevance to secondary carbonate formation. Our results show the value and complexity of separating primary vs. secondary signals in bioarchives with relevance to understanding fluid-burial history in methane seep provinces. Results from our core analyses are integrated with observations made during the CAGE15-2 cruise in May 2015, when we deployed a towed vehicle equipped with camera, multicore and water sampling capabilities. The instrument design was based on the Woods Hole Oceanographic Institution (WHOI) MISO TowCam sled equipped with a deep-sea digital camera and CTD real-time system. Sediment sampling was visually-guided using this system. In one of the pockmarks along the Vestnesa Ridge where high

  4. Fermi GBM Observations of LIGO Gravitational-wave Event GW150914

    NASA Astrophysics Data System (ADS)

    Connaughton, V.; Burns, E.; Goldstein, A.; Blackburn, L.; Briggs, M. S.; Zhang, B.-B.; Camp, J.; Christensen, N.; Hui, C. M.; Jenke, P.; Littenberg, T.; McEnery, J. E.; Racusin, J.; Shawhan, P.; Singer, L.; Veitch, J.; Wilson-Hodge, C. A.; Bhat, P. N.; Bissaldi, E.; Cleveland, W.; Fitzpatrick, G.; Giles, M. M.; Gibby, M. H.; von Kienlin, A.; Kippen, R. M.; McBreen, S.; Mailyan, B.; Meegan, C. A.; Paciesas, W. S.; Preece, R. D.; Roberts, O. J.; Sparke, L.; Stanbro, M.; Toelge, K.; Veres, P.

    2016-07-01

    With an instantaneous view of 70% of the sky, the Fermi Gamma-ray Burst Monitor (GBM) is an excellent partner in the search for electromagnetic counterparts to gravitational-wave (GW) events. GBM observations at the time of the Laser Interferometer Gravitational-wave Observatory (LIGO) event GW150914 reveal the presence of a weak transient above 50 keV, 0.4 s after the GW event, with a false-alarm probability of 0.0022 (2.9σ). This weak transient lasting 1 s was not detected by any other instrument and does not appear to be connected with other previously known astrophysical, solar, terrestrial, or magnetospheric activity. Its localization is ill-constrained but consistent with the direction of GW150914. The duration and spectrum of the transient event are consistent with a weak short gamma-ray burst (GRB) arriving at a large angle to the direction in which Fermi was pointing where the GBM detector response is not optimal. If the GBM transient is associated with GW150914, then this electromagnetic signal from a stellar mass black hole binary merger is unexpected. We calculate a luminosity in hard X-ray emission between 1 keV and 10 MeV of {1.8}-1.0+1.5× {10}49 erg s‑1. Future joint observations of GW events by LIGO/Virgo and Fermi GBM could reveal whether the weak transient reported here is a plausible counterpart to GW150914 or a chance coincidence, and will further probe the connection between compact binary mergers and short GRBs.

  5. Observed changes in aerosol physical and optical properties before and after precipitation events

    NASA Astrophysics Data System (ADS)

    Li, Xingmin; Dong, Yan; Dong, Zipeng; Du, Chuanli; Chen, Chuang

    2016-08-01

    Precipitation scavenging of aerosol particles is an important removal process in the atmosphere that can change aerosol physical and optical properties. This paper analyzes the changes in aerosol physical and optical properties before and after four rain events using in situ observations of mass concentration, number concentration, particle size distribution, scattering and absorption coefficients of aerosols in June and July 2013 at the Xianghe comprehensive atmospheric observation station in China. The results show the effect of rain scavenging is related to the rain intensity and duration, the wind speed and direction. During the rain events, the temporal variation of aerosol number concentration was consistent with the variation in mass concentration, but their size-resolved scavenging ratios were different. After the rain events, the increase in aerosol mass concentration began with an increase in particles with diameter <0.8 μm [measured using an aerodynamic particle sizer (APS)], and fine particles with diameter <0.1 μm [measured using a scanning mobility particle sizer (SMPS)]. Rainfall was most efficient at removing particles with diameter ~0.6 μm and greater than 3.5 μm. The changes in peak values of the particle number distribution (measured using the SMPS) before and after the rain events reflect the strong scavenging effect on particles within the 100-120 nm size range. The variation patterns of aerosol scattering and absorption coefficients before and after the rain events were similar, but their scavenging ratios differed, which may have been related to the aerosol particle size distribution and chemical composition.

  6. Multi-wavelength Observations of a Subarcsecond Penumbral Transient Brightening Event

    NASA Astrophysics Data System (ADS)

    Bai, X. Y.; Su, J. T.; Cao, W. D.; Liu, S. Q.; Deng, Y. Y.; Priya, T. G.

    2016-05-01

    We report a subarcsecond penumbral transient brightening event with the high-spatial resolution observations from the 1.6 m New Solar Telescope (NST), Interface Region Imaging Spectrograph (IRIS), and the Solar Dynamics Observatory. The transient brightening, whose thermal energy is in the range of nanoflares, has signatures in the chromosphere, the transient region, and the corona. NST's Hα channel reveals the fine structure of the event with a width as narrow as 101 km (0.″14), which is much smaller than the width from the previous observation. The transient brightening lasts for about 3 minutes. It is associated with a redshift of about 17 km s‑1, found in the Si iv 1402.77 Å line and exhibits an inward motion to the umbra with a speed of 87 km s‑1. The small-scale energy released from the event has a multi-temperature component. Spectral analysis of the brightening region from IRIS shows that not only the transition region lines such as Si iv 1402.77 Å and C ii 1334.53 Å, but also the chromospheric Mg ii k 2796.35 Å line are significantly enhanced and broadened. In addition, the event can be found in all the extreme-ultraviolet passbands of the Atmospheric Imaging Assembly and the derived differential emission measure profile increases between 4 and 15 MK (or 6.6 ≤ log T ≤ 7.2) in the transient brightening phase. It is possible that the penumbral transient brightening event is caused by magnetic reconnection.

  7. Observations of quasi-periodic scintillations and their possible relation to the dynamics of Es plasma blobs

    SciTech Connect

    Maruyama, Takashi )

    1991-06-01

    Quasi-periodic scintillations at a mid-latitude station, Wakkanai, Japan, are examined using 136-MHz geostationary satellite transmissions. Observations are compared with the ionospheric parameter obtained at the same station and random scintillation records. The results indicate that the quasi-periodic scintillations are most likely produced by plasma blobs within the sporadic E layers. Discussion focuses on characteristics of the ringing pattern which precedes and follows the primary deep fade-out, in field strength. In the majority of events the ringing pattern tends to develop after the distinct deep fade-out, i.e., the pattern is asymmetric. Quasi-periodic scintillation patterns are produced by the movement of plasma blobs in the case of geostationary satellite experiments. Thus the shape of the blob must be deformed so that a steep density gradient is attained on the backside. When the blob is highly deformed by the plasma instability which grows at the steep density gradient, burstlike random scintillations may be produced by the blob. 16 refs.

  8. X-ray and Gamma-ray Observations of Solar Flares and SEP Events

    NASA Astrophysics Data System (ADS)

    Winter, Lisa M.

    2016-05-01

    We present a statistical analysis of the X-ray and gamma ray observations of C, M, and X-class flares from solar cycle 24. Extending upon the Winter & Balasubramaniam 2015 study of the GOES XIS observations of 50,000 flares from 1986 to the present, we include Fermi GBM and LAT data from the Fermi solar flare catalogs. As in the previous work, we use machine-learning techniques to determine whether the higher energy data reveal further temperature diagnostics to establish clustering of flare properties. Additionally, we compare the X-ray and gamma ray intensities and flare timing with the intensity and timing of solar energetic particle events.

  9. New Space Shuttle Observations of Transient Luminous Events During the MEIDEX

    NASA Astrophysics Data System (ADS)

    Yair, Y.; Price, C.; Israelevitch, P.; Devir, A.; Moalem, M.; Ziv, B.; Levin, Z.; Joseph, J.

    2003-12-01

    The Mediterranean Israeli Dust Experiment (MEIDEX) was conducted on-board the space shuttle Columbia during its last mission in January 2003. Nocturnal observations with a multispectral CCD video camera were targeted above thunderstorms near the Earth's limb, with the aim or recording Transient Luminous Events (TLEs) in the mesosphere. Most of our nighttime observations were conducted in the SE-Pacific (Australia and Papua-New Guinea), equatorial Africa, the southern Indian Ocean and South America. Relevant inputs and information on the active storms during a specific orbit were uplinked to the crew daily. The necessary shuttle attitude maneuvers were deduced based on the use of (almost) real-time IR satellite images and VLF lightning location data that were available on the Internet. In order to enhance the probability of success of each observation, the astronauts were instructed to visually observe lightning activity (easily discernable from the shuttle) and to direct the gimbaled camera toward these regions. A total of more than 8 hours of video obtained during the MEIDEX was saved, and it includes a considerable amount of new sprite data. Most events were captured at ranges 1600-1900 km from the shuttle, using the red filter (665nm). The results suggest the occurrence rate of sprites and elves over oceanic and continental storms may be higher than earlier estimates. Strong enhancements of the brightness of the airglow layer above lightning flashes were observed, with lateral dimensions on the order of 400-500 km. It is assumed that these may be Elves observed edge-on, though it may also be a new type of airglow enhancement. The calculated brightness of these events is in the range 2.2-8.8 MR. This phenomena seems to be widespread and is probably a manifestation of the interaction between lightning EMP and QE fields and the lower nocturnal ionosphere. A unique observation from space of the Congo basin in Africa caught a chain of events where in the span of less

  10. THEMIS Observations of Unusual Bow Shock Motion, Attending a Transient Magnetospheric Event

    NASA Technical Reports Server (NTRS)

    Korotova, Galina; Sibeck, David; Omidi, N.; Angelopoulos, V.

    2013-01-01

    We present a multipoint case study of solar wind and magnetospheric observations during a transient magnetospheric compression at 2319 UT on October 15, 2008. We use high-time resolution magnetic field and plasma data from the THEMIS and GOES-11/12 spacecraft to show that this transient event corresponded to an abrupt rotation in the IMF orientation, a change in the location of the foreshock, and transient outward bow shock motion. We employ results from a global hybrid code model to reconcile the observations indicating transient inward magnetopause motion with the outward bow shock motion.

  11. Air Twitter: Mashing Crowdsourced Air Quality Event Identification with Scientific Earth Observations (Invited)

    NASA Astrophysics Data System (ADS)

    Robinson, E. M.

    2010-12-01

    , which allows time series of the number of tweets hourly and daily. Monitoring the time series AQ events are identified from the background chatter about air quality. As the events are identified, collaborative, EventSpaces (Robinson, 2008) are created using the ESIP wiki to collect and merge social and scientific information about the event. The EventSpaces are monitored using Google Analytics. During the August California Fires the traffic increased five-fold to the ESIP wiki. Furthermore, the increase in traffic was entirely due to views of the SoCal FireEventSpace. A top driver to the site was through tweeting the link to the EventSpace and having that link re-tweeted by others like the LA Times. An interesting an unexpected observation, was that most of the increased traffic was coming from Southern California. So the right people were finding the right information at the right time. The overall benefit of using the online community as an AQ event indicator, allows specific effort to be made for initial documentation of air quality events and the result is a catalog of events with some sparse analysis that can be followed-up.

  12. Volcanic Centers in the East African Rift: Imaging Volcanic Processes with Long-Period Event Identification and Ambient Noise Tomography

    NASA Astrophysics Data System (ADS)

    Patlan, E.; Wamalwa, A. M.; Hardy, S.; Kaip, G.; Velasco, A. A.

    2014-12-01

    Kenya actively seeks to produce geothermal energy, and the country lies within the East African Rift System (EARS). The EARS, an active continental rift zone, appears to be a developing tectonic plate boundary and thus, has a number of active as well as dormant volcanoes through its extent. These volcanic centers can be used as potential sources for geothermal energy. The University of Texas at El Paso (UTEP) and the Geothermal Development Company (GDC) began collaborating to monitor several volcanic centers, which have included passive seismic sensor deployments experiment. A number of seismological techniques will be applied to the data being collected at the four volcanic centers: Menengai, Silali, and Paka, and Korosi. In particular, we will identify long-period signals and tremor local using a time-reversal approach. Low-frequency earthquakes are interpreted as magma passing through conduits of the magma chamber and/or fluid being transported as a function of magma movement or hydrothermal activity. The time-reversal locations will help identify the margin of the volcano and caldera, and faults that could form conduits for fluids. We will also perform ambient noise tomography to image the magma chamber and the conduit feeding the volcanoes. The combination of the velocity snapshots of the magma chamber, low-frequency events, and long period events will help us interpret the activity of the calderas and volcanoes. Overall, all these techniques will help us understand magma movement and volcanic processes in the region.

  13. STEREO observations of quasi-periodically driven high velocity outflows in polar plumes

    NASA Astrophysics Data System (ADS)

    McIntosh, S. W.; Innes, D. E.; de Pontieu, B.; Leamon, R. J.

    2010-02-01

    Context. Plumes are one of the most ubiquitous features seen at the limb in polar coronal holes and are considered to be a source of high density plasma streams to the fast solar wind. Aims: We analyze STEREO observations of plumes and aim to reinterpret and place observations with previous generations of EUV imagers within a new context that was recently developed from Hinode observations. Methods: We exploit the higher signal-to-noise, spatial and temporal resolution of the EUVI telescopes over that of SOHO/EIT to study the temporal variation of polar plumes in high detail. We employ recently developed insight from imaging (and spectral) diagnostics of active region, plage, and quiet Sun plasmas to identify the presence of apparent motions as high-speed upflows in magnetic regions as opposed to previous interpretations of propagating waves. Results: In almost all polar plumes observed at the limb in these STEREO sequences, in all coronal passbands, we observe high speed jets of plasma traveling along the structures with a mean velocity of 135 km s-1 at a range of temperatures from 0.5-1.5 MK. The jets have an apparent brightness enhancement of ~5% above that of the plumes they travel on and repeat quasi-periodically, with repeat-times ranging from five to twenty-five minutes. We also notice a very weak, fine scale, rapidly evolving, but ubiquitous companion of the plumes that covers the entire coronal hole limb. Conclusions: The observed jets are remarkably similar in intensity enhancement, periodicity and velocity to those observed in other magnetic regions of the solar atmosphere. They are multi-thermal in nature. We infer that the jets observed on the plumes are a source of heated mass to the fast solar wind. Further, based on the previous results that motivated this study, we suggest that these jets originated in the upper chromosphere. Five movies are only available in electronic form at http://www.aanda.org

  14. Mechanisms and observations of coronal dimming for the 201 August 7 event

    SciTech Connect

    Mason, James Paul; Woods, T. N.; Caspi, A.; Thompson, B. J.; Hock, R. A.

    2014-07-01

    Coronal dimming of extreme ultraviolet (EUV) emission has the potential to be a useful forecaster of coronal mass ejections (CMEs). As emitting material leaves the corona, a temporary void is left behind which can be observed in spectral images and irradiance measurements. The velocity and mass of the CMEs should impact the character of those observations. However, other physical processes can confuse the observations. We describe these processes and the expected observational signature, with special emphasis placed on the differences. We then apply this understanding to a coronal dimming event with an associated CME that occurred on 2010 August 7. Data from the Solar Dynamics Observatory's Atmospheric Imaging Assembly and EUV Variability Experiment (EVE) are used for observations of the dimming, while the Solar and Heliospheric Observatory's Large Angle and Spectrometric Coronagraph and the Solar Terrestrial Relations Observatory's COR1 and COR2 are used to obtain velocity and mass estimates for the associated CME. We develop a technique for mitigating temperature effects in coronal dimming from full-disk irradiance measurements taken by EVE. We find that for this event, nearly 100% of the dimming is due to mass loss in the corona.

  15. Mechanisms and Observations of Coronal Dimming for the 2010 August 7 Event

    NASA Technical Reports Server (NTRS)

    Mason, James P.; Woods, Thomas N.; Caspi, Amir; Thompson, Barbara J.; Hock, Rachel A.

    2014-01-01

    Coronal dimming of extreme ultraviolet (EUV) emission has the potential to be a useful forecaster of coronal mass ejections (CMEs). As emitting material leaves the corona, a temporary void is left behind which can be observed in spectral images and irradiance measurements. The velocity and mass of the CMEs should impact the character of those observations. However, other physical processes can confuse the observations. We describe these processes and the expected observational signature, with special emphasis placed on the differences. We then apply this understanding to a coronal dimming event with an associated CME that occurred on 2010 August 7. Data from the Solar Dynamics Observatory's (SDO) Atmospheric Imaging Assembly (AIA) and EUV Variability Experiment (EVE) are used for observations of the dimming, while the Solar and Heliospheric Observatory's (SoHO) Large Angle and Spectrometric Coronagraph (LASCO) and the Solar Terrestrial Relations Observatory's (STEREO) COR1 and COR2 are used to obtain velocity and mass estimates for the associated CME. We develop a technique for mitigating temperature effects in coronal dimming from full-disk irradiance measurements taken by EVE. We find that for this event, nearly 100% of the dimming is due to mass loss in the corona.

  16. Source mechanism of long-period events at Kusatsu-Shirane Volcano, Japan, inferred from waveform inversion of the effective excitation functions

    USGS Publications Warehouse

    Nakano, M.; Kumagai, H.; Chouet, B.A.

    2003-01-01

    We investigate the source mechanism of long-period (LP) events observed at Kusatsu-Shirane Volcano, Japan, based on waveform inversions of their effective excitation functions. The effective excitation function, which represents the apparent excitation observed at individual receivers, is estimated by applying an autoregressive filter to the LP waveform. Assuming a point source, we apply this method to seven LP events the waveforms of which are characterized by simple decaying and nearly monochromatic oscillations with frequency in the range 1-3 Hz. The results of the waveform inversions show dominant volumetric change components accompanied by single force components, common to all the events analyzed, and suggesting a repeated activation of a sub-horizontal crack located 300 m beneath the summit crater lakes. Based on these results, we propose a model of the source process of LP seismicity, in which a gradual buildup of steam pressure in a hydrothermal crack in response to magmatic heat causes repeated discharges of steam from the crack. The rapid discharge of fluid causes the collapse of the fluid-filled crack and excites acoustic oscillations of the crack, which produce the characteristic waveforms observed in the LP events. The presence of a single force synchronous with the collapse of the crack is interpreted as the release of gravitational energy that occurs as the slug of steam ejected from the crack ascends toward the surface and is replaced by cooler water flowing downward in a fluid-filled conduit linking the crack and the base of the crater lake. ?? 2003 Elsevier Science B.V. All rights reserved.

  17. Validation of a global 3D heliospheric model with observations for the May 12, 1997 CME event

    NASA Astrophysics Data System (ADS)

    Cohen, O.; Sokolov, I. V.; Roussev, I. I.; Lugaz, N.; Manchester, W. B.; Gombosi, T. I.; Arge, C. N.

    2008-02-01

    We simulate the May 12, 1997 space weather event from the Sun to the Earth. The initiation of the coronal mass ejection (CME) was done by superimposing a semi-circular, out-of-equilibrium magnetic flux rope onto a semi-empirical, steady-state solar corona model (SCM). The result at 1 AU was obtained by coupling the SCM with an inner heliosphere model (IHM). Our results demonstrate that the CME parameters can be obtained from magnetogram data and white-light observations and that the results at 1 AU can be simulated faster than the real time, even with the use of a relatively moderate computation resources. This particular event, however, is found to be very difficult to model, despite the fact that it is temporarily isolated in time from other CME events and it occurred during a solar minimum period. We found that the active region flux rope should be resolved with higher resolution in order to maintain its integrity while propagating into space. This way we can obtain a better agreement with measurements at 1 AU.

  18. The blue luminous events observed by ISUAL payload on board FORMOSAT-2 satellite

    NASA Astrophysics Data System (ADS)

    Kuo, C. L.; Su, H. T.; Hsu, R. R.

    2015-11-01

    We report the blue luminous events observed by the Imager of Sprite/Upper Atmospheric Lightning (ISUAL) payload on board the FORMOSAT-2 satellite. The ISUAL 427.8 nm filtered Imager campaign was conducted near Australia in the summer of the Southern Hemisphere during February-March 2008. On 18 February 2008, the 427.8 nm filtered Imager recorded a series of blue luminous events. One blue starter and nine smaller blue starters were recorded in 2 min and 34 s in a localized region with the radius < 4 km over the cloud top. The average time interval between subsequent blue luminous events was ~ 17 s. The occurrence rate of blue luminous events was 3.5 events per minute, slightly lower than the occurrence rate of pixies (4.2 events per minute) but higher than the occurrence rate of gnomes and blue jets in the previous observations. The recorded first blue starter lasted up to 2-3 frame times (60-90 ms) and extended its altitude about 8 ± 0.3 km with a width of ~2-4 km over the cloud top. After the first blue starter, subsequent nine smaller blue starters had the decreased heights of ~2-4 km, and their optical duration was shorter and is down to 1 ms. But their major emissions were 2PN2 and 1NN2+, without lightning OI 777.4 nm emission. The ISUAL recorded blue smaller starters had the spatial average brightness of 130 kR for the 427.8 nm filtered Imager with exposure time (29 ms) and 1.2 MR for the spectrophotometer (337 nm). Using the spectrophotometer, the emission time of blue starters was 1 ms. It is estimated that the 1NN2+ emission was ~ 22 MR and the 2PN2 emission was ~ 132 MR. We can estimate the degree of ionization was 10-11-10-12 in these blue luminous events using the 427.8 nm filtered Imager measured 1NN2+ (0,1) emission.

  19. Cloud and Precipitation Variations Associated with MJO Events Observed from AMIE/DYNAMO and ARM TWP Sites

    NASA Astrophysics Data System (ADS)

    Deng, M.; Long, C. N.; McFarlane, S. A.; Zhang, C.; Mace, J.

    2013-12-01

    The MJO is characterized by eastward propagation of regions of enhanced and suppressed tropical rainfall in the tropics with a cycle of 30-60 days, associated with distinct patterns of tropical lower and upper atmospheric circulation anomalies (Madden and Julian 1971, 1972). However, not all of the elements of the MJO -- convection, zonal wind, moisture convergence, and SST anomalies -- are always visible. Consecutive oscillations have varying amplitudes, periods, and wavelengths. The ARM MJO Investigation Experiment (AMIE) campaign is collaborated with the DYNAMO project to fully characterize the ensemble of convection associated with MJO with ARM Ka-band zenith pointing radars (KAZR), along with other suite of measurements, which is about 10 km around from NCAR S-Pol radar and C-band radar. A KAZR cloud and precipitation detection and classification algorithm is developed and evaluated with collocated precipitating radar and surface rain gauge observations. The results show that KAZR can effectively detect and separate convective and stratiform rain, which show two distinct surface rain rates. This algorithm is adapted for ARM long-term cloud radar observations. AMIE has observations at two well separated sites: AMF2 on Gan Island in the Indian Ocean (AMIE-Gan), where the MJO enhanced convective phase initiates and starts its eastward propagation; and the ARM Manus site (AMIE-Manus) at the tropical western pacific, which is in the general area where the MJO usually starts to weaken in climate models. We find very different correlation patterns between cloud field and thermodynamic structure for three MJO events observed at these two locations. MJO events at Gan have tilted RH structure with time and height, which means lifting of moisture level at the pre-onset stage and low-level drying at the post-onset stage. Increases in high cloud lag behind low and middle level clouds. These features are consistent with the discharge-recharge mechanism (Blade and Hartmann

  20. Time-varying autoregressive model for spectral analysis of microseismic experiments and long-period volcanic events

    NASA Astrophysics Data System (ADS)

    Tary, J. B.; Herrera, R. H.; van der Baan, M.

    2014-01-01

    Recent studies show that the frequency content of continuous passive recordings contains useful information for the study of hydraulic fracturing experiments as well as longstanding applications in volcano and global seismology. The short-time Fourier transform (STFT) is usually used to obtain the time-frequency representation of a seismic trace. Yet, this transform has two main disadvantages, namely its fixed time-frequency resolution and spectral leakage. Here, we describe two methods based on autoregressive (AR) models: the short-time autoregressive method (ST-AR) and the Kalman smoother (KS). These two methods allow for the AR coefficients to vary over time in order to follow time-varying frequency contents. The outcome of AR methods depends mainly on the number of AR coefficients. We use a robust approach to estimate the optimum order of the AR methods that best matches the spectral comparison between Fourier and AR spectra. Comparing the outcomes of the three methods on a synthetic signal, a long-period volcanic event, and microseismic data, we show that the STFT and both AR methods are able to track fast changes in frequency content. The STFT provides reasonable results even for noisy data using a simple and effective algorithm. The coefficients of the AR filter are defined at all time in the case of the KS. However, its better time resolution is slightly offset by a lower frequency resolution and its computational complexity. The ST-AR has a high spectral resolution and the lowest sensitivity to background noises, facilitating the identification of the various frequency components. The estimated AR coefficients can also be used to extract parts of the signal. The study of long-term phenomena, such as resonance frequencies, or transient events, such as long-period events, could help to gain further insight on reservoir deformation during hydraulic fracturing experiments as well as global or volcano seismological signals.

  1. Identifying the occurrence of lightning and transient luminous events by nadir spectrophotometric observation

    NASA Astrophysics Data System (ADS)

    Adachi, Toru; Sato, Mitsuteru; Ushio, Tomoo; Yamazaki, Atsushi; Suzuki, Makoto; Kikuchi, Masayuki; Takahashi, Yukihiro; Inan, Umran S.; Linscott, Ivan; Hobara, Yasuhide; Frey, Harald U.; Mende, Stephen B.; Chen, Alfred B.; Hsu, Rue-Ron; Kusunoki, Kenichi

    2016-07-01

    We propose a new technique to identify the occurrence of lightning and transient luminous events (TLEs) using multicolor photometric data obtained by space borne nadir measurements. We estimate the spectral characteristics of lightning and TLEs by converting the optical data obtained by the ISUAL limb experiment to the GLIMS nadir geometry. We find that the estimated spectral shapes of TLE-accompanied lightning are clearly different from those of pure lightning. The obtained results show that (1) the intensity of FUV signals and (2) the ratio of 337/red (609-753 nm) spectral irradiance are useful to identify the occurrence of TLEs. The occurrence probabilities of TLEs are 10%, 40%, 80%, in the case of lightning events having the 337/red spectral irradiance ratio of 0.95, 2.95, 14.79, respectively. By using the 60% criterion of the 337/red ratio and the existence of FUV emissions, we classify the 1039 GLIMS-observed lightning events into 828 pure lightning and 211 TLE-accompanied lightning. Since the GLIMS trigger level is adjusted to observe extremely-bright events, the occurrence probability of TLEs obtained here most probably reflects the characteristics of energetic lightning. The estimated global map is consistent with previously determined distributions: the highest activities of lightning and TLEs are found over the North/South American continents, African continent, and Asian maritime regions. While the absolute occurrence number of pure lightning and TLE-accompanied lightning are found to maximize in the equatorial region, the occurrence probability of TLEs possibly increase somewhat in the mid-latitude region. Since the occurrence probabilities of TLEs are higher over the ocean than over land, it is likely that the GLIMS-observed TLEs are due primarily to elves which tends to occur more frequently over the ocean.

  2. Microlensing Events from the 11 Year Observations of the Wendelstein Calar Alto Pixellensing Project

    NASA Astrophysics Data System (ADS)

    Lee, C.-H.; Riffeser, A.; Seitz, S.; Bender, R.; Koppenhoefer, J.

    2015-06-01

    We present the results of the decade-long M31 observation from the Wendelstein Calar Alto Pixellensing Project (WeCAPP). WeCAPP has monitored M31 from 1997 until 2008 in both R- and I-filters, and thus provides the longest baseline of all M31 microlensing surveys. The data are analyzed with difference imaging analysis, which is most suitable for studying variability in crowded stellar fields. We extracted light curves based on each pixel, and devised selection criteria that are optimized to identify microlensing events. This leads to 10 new events, and adds up to a total of 12 microlensing events from WeCAPP, for which we derive their timescales, flux excesses, and colors from their light curves. The colors of the lensed stars fall in the range (R - I) = 0.56 to 1.36, with a median of 1.0 mag, in agreement with our expectation that the sources are most likely bright, red stars at the post-main-sequence stage. The event FWHM timescales range from 0.5 to 14 days, with a median of 3 days, in good agreement with predictions based on the model of Riffeser et al.

  3. River flood events in Thailand and Bangladesh observed by CryoSat

    NASA Astrophysics Data System (ADS)

    Andersen, O. B.; Nielsen, K.; Villadsen, H.; Stenseng, L.; Knudsen, P.

    2014-12-01

    The high along track resolution of the SIRAL altimeter carried on-board CryoSat-2 offers a wide range of unique opportunities for satellite monitoring of inland water level. This study focuses on the ability of CryoSat-2 to detect the effects of flood events such as increased river levels and inundation of land. Here we study two flood events; the Bangladesh flood event of June 2012 and the flooding in Thailand that lasted between July 2011 and January 2012. The flooding in these areas was caused by abnormal monsoonal rainfall and affected millions of people. We process CryoSat-2 level 1b SAR mode data to derive water levels for the areas and compare these levels before, during and after the flooding events. Other parameters such as the backscatter coefficient and pulse peakiness are also considered. To verify the extent of the flooding observed by CryoSat-2 we compare with independent sources such as Landsat images.

  4. Rayleigh/raman Greenland Lidar Observations of Atmospheric Temperature During a Major Arctic Stratospheric Warming Event

    NASA Technical Reports Server (NTRS)

    Meriwether, John W.; Farley, Robert; Mcnutt, R.; Dao, Phan D.; Moskowitz, Warren P.

    1992-01-01

    Between Jan. 22 1991 to Feb. 5 1991, we made numerous observations of atmospheric temperature profiles between 10 and 70 km by using the combination of Rayleigh and Raman lidar systems contained in the PL Mobile Lidar Facility located at the National Science Foundation Incoherent Radar Facility of Sondrestrom in Greenland. The purpose of these measurements was to observe the dynamics of the winter Arctic stratosphere and mesosphere regions during a winter period from the succession of temperature profiles obtained in our campaign observations. Various aspects of this investigation are presented.

  5. Intrinsic parameters of periodic waves observed in the OI6300 over Brazilian equatorial region

    NASA Astrophysics Data System (ADS)

    Medeiros, Amauri; Buriti, Ricardo; Paulino, Igo; Meriwether, John; Takahashi, Hisao; Maranhão, Glelson

    2016-07-01

    Using two Fabry-Perot interferometers (FPIs) deployed at São João do Cariri (36.5oW, 7.4oS) and Cajazeiras (38.6oW and 6.9oS ) and an all sky imager installed at São João do Cariri, the intrinsic parameters of 23 periodic waves, observed in the OI630.0 nm airglow layer, were estimated and studied. The observed horizontal parameters of these waves were estimated using two-dimensional Fourier analysis. In order to estimate the intrinsic parameters, simultaneous horizontal winds measurements performed by the FPI were used. The results show that the observed parameters of the waves were quite similar to the previous observation, indicating the sources of these waves are not changing along the time. The horizontal wavelengths were mostly found between 90 and 180 km, intrinsic periods ranged from 12 to 36 min and horizontal intrinsic phase speed from 50 to 200 ms-1. Furthermore, the wind was blowing almost perpendicular to the propagation direction of these waves, suggesting that the wind is as important factor to the filtering process of these waves in the lower thermosphere.

  6. Aerosol and Cloud-Nucleating Particle Observations during an Atmospheric River Event

    NASA Astrophysics Data System (ADS)

    DeMott, P. J.; McCluskey, C. S.; Petters, M.; Suski, K. J.; Levin, E. J.; Hill, T. C. J.; Atwood, S. A.; Schill, G. P.; Rocci, K.; Boose, Y.; Martin, A.; Cornwell, G.; Al-Mashat, H.; Moore, K.; Prather, K. A.; Rothfuss, N.; Taylor, H.; Leung, L. R.; Tomlinson, J. M.; Mei, F.; Hubbe, J. M.; Rosenfeld, D.; Spackman, J. R.; Fairall, C. W.; Creamean, J.; White, A. B.; Kreidenweis, S. M.

    2015-12-01

    The multi-agency CalWater 2015 project occurred over North Central CA and the Eastern Pacific during January to March 2015 (Spackman et al., this session). The goals of the campaign were to document the structure of atmospheric rivers (ARs) that deliver much of the water vapor associated with major winter storms along the U.S. West Coast and to investigate the modulating effect of aerosols on precipitation. Aerosol sources that may influence orographic cloud properties for air lifted over the mountains in California in winter include pollution, biomass burning, soil dusts and marine aerosols, but their roles will also be influenced by transport, vertical stratification, and scavenging processes. We present results from a comprehensive study of aerosol distributions, compositions, and cloud nucleating properties during an intense winter storm during February 2015, including data from an NSF-supported measurement site at Bodega Bay, from the DOE-ARM Cloud Aerosol Precipitation Experiment that included sampling on the NOAA RV Ron Brown offshore and the G-1 aircraft over ocean and land, and with context provided by other NOAA aircraft and remote sensing facilities. With a special focus on the coastal site, we discuss changes in aerosol distributions, aerosol hygroscopicity, and number concentrations of fluorescent particles, cloud condensation nuclei (CCN), and ice nucleating particles (INPs) during the AR event. We compare with periods preceding and following the event. For example, total aerosol number and surface area concentrations at below 0.5 μm diameter decreased from typical values of a few thousand cm-3 and 100 μm2 cm-3, respectively, to a few hundred cm-3 and 10 μm2cm-3 at Bodega Bay during the AR event. CCN concentrations were similarly lower, but hygroscopicity parameter (kappa) increased from typical values of 0.2 to values > 0.5 during the AR.INP and fluorescent particle number concentrations were generally lower during the AR event than at any other

  7. Observations of Sub-3 nm Particles and Sulfuric acid Concentrations during Aerosol Life Cycle Intensive Observation Period 2011 in Long Island, New York

    NASA Astrophysics Data System (ADS)

    Yu, H.; Kanawade, V. P.; You, Y.; Hallar, A. G.; Mccubbin, I. B.; Chirokova, G.; Sedlacek, A. J.; Springston, S. R.; Wang, J.; Kuang, C.; Lee, Y.; McGraw, R. L.; Mikkila, J.; Lee, S.

    2012-12-01

    Atmospheric new particle formation (NPF) is an important source of aerosol particles. But the NPF processes are not well understood, in part because of our limited understanding of the formation of atmospheric sub-3 nm size aerosols and the limited number of simultaneous observations of particle size distributions and the aerosol nucleation precursors. During Aerosol Life Cycle Intensive Observation Period (July-August 2011) in Long Island, New York, we deployed a particle size magnifier (Airmodus A09) running at different working fluid saturation ratios and a TSI CPC3776 to extract the information of sub-3 nm particles formation. A scanning mobility particle spectrometer (SMPS), a chemical ionization mass spectrometer (CIMS), and a number of atmospheric trace gas analyzers were used to simultaneously measure aerosol size distributions, sulfuric acid, and other possible aerosol precursors, respectively. Our observation results show that sub-3 nm particles existed during both NPF and non-NPF events, indicating the formation of sub-3nm particle didn't always lead to NPF characterized by typical banana shaped aerosol size distributions measured by SMPS. However, sub-3 nm particles were much higher during NPF events. Sub-3 nm particles were well-correlated with sulfuric acid showing the same diurnal variations and noontime peaks, especially for NPF days. These results are consistent with laboratory studies showing that formation of sub-3 nm particles is very sensitive to sulfuric acid (than amines and ammonia) [Yu et al. GRL 2012]. HYSPLIT back trajectory analysis indicates that air masses from Great Lakes, containing more SO2, VOCs and secondary organics, may contribute to growth of sub-3 nm particles and NPF.

  8. Progresses on the Intensive Observation Period of Watershed Allied Telemetry Experimental Research

    NASA Astrophysics Data System (ADS)

    Li, Xin; Li, Xiaowen; Li, Zengyuan; Ma, Mingguo; Wang, Jian; Liu, Qiang; Xiao, Qing; Chen, Erxue; Che, Tao; Hu, Zeyong

    2010-05-01

    The Watershed Allied Telemetry Experimental Research (WATER) is an intensively simultaneous airborne, satellite-borne and ground based remote sensing experiment aiming to improve the observability, understanding, and predictability of hydrological and related ecological processes at catchment scale. It was taken place in the Heihe River Basin, the second largest inland river basin in the arid regions of northwest China. WATER consists of the cold region, forest, and arid region hydrological experiments as well as a hydrometeorology experiment. It was divided into 4 phases, namely, the experiment planning period, pre-observation period, intensive observation period (IOP) and persistent observation period. The field campaigns have been completed, with the IOP lasting from March 7 to April 12, May 15 to July 22, and August 23 to September 5, 2008, in total, 120 days, more than 280 individuals of scientists, engineers, students, and aircrews from 28 different institutes and universities were involved in. A total of 26 airborne missions, about 110 hours were flown. Airborne sensors including microwave radiometers at L, K and Ka bands, imaging spectrometer, thermal imager, CCD and LIDAR were used. Ground measurements were carried out concurrently with the airborne and space-borne remote sensing at four scales, i.e., key experimental area, foci experimental area, experiment site and elementary sampling plot. A network of hydro meteorological and flux observations was established in the upper and middle reaches of the Heihe River Basin. The network was composed of 12 super Automatic Meteorological Stations (AMS), 6 Eddy Covariance (EC) systems, 2 Large Aperture Scintillometers (LAS), and plenty of China Meteorological Administration (CMA) operational meteorological and hydrological stations. Additionally, we also used ground-based remote sensing instruments, such as Doppler Radar, ground based microwave radiometer and truck-mounted scatterometer and lots of auto

  9. Saturn's Ionospheric Clock(s): A Concept for Generating and Maintaining Saturn's Observed Magnetospheric Periodicities

    NASA Astrophysics Data System (ADS)

    Mitchell, D. G.; Brandt, P. C.; Ukhorskiy, A. Y.

    2010-12-01

    Saturn’s 10.X hour periodicity, observed throughout the magnetosphere, remains a mystery. It has been observed in many regions, modulating many phenomena. During the Cassini mission most observations have shown a period at about 10.8 hours, expressed in Saturn kilometric radiation from the high latitude auroral zone, in magnetic field components (both equatorial and high latitude) from 3 to 12 Rs, in current sheet encounters in the outer magnetosphere and magnetotail, in energetic neutral atom emission from the equatorial magnetosphere, and in plasma and energetic particles throughout the magnetosphere. More recently, various authors have shown at least two dominant periods expressed (in SKR and in magnetic field components), with slightly different values in the southern and northern hemispheres. The cause of this behavior is still not accounted for. Although loosely associated with Saturn’s rotation, the variability in the period precludes a direct connection with Saturn’s interior (e.g., a magnetic anomaly). Other candidates that have been discussed by others are an ionospheric source (conductivity anomaly), a perturbation in the cold plasma circulation pattern, a magnetospheric cam, asymmetric ring current particle pressure, and/or a natural frequency of the magnetosphere (cavity mode or traveling wave front of some sort). In this paper we present a concept that derives its energy from the subcorotating cold, dense plasma (which exhibits a rotation period on the order of 13 to 14 hours throughout L-shells between ~3 and 20), but is triggered by a process linked with the ionosphere. Key components of the model include significant slippage between the ionosphere and the magnetosphere (with the ionosphere rotating at the expressed period in each hemisphere, only slightly more slowly than the planet interior), subcorotating cold dense plasma with a source in the inner magnetosphere, predominantly radial transport of the cold dense plasma in the rotational

  10. XMM-Newton Slew Survey Observations of the Gravitational Wave Event GW150914

    NASA Astrophysics Data System (ADS)

    Troja, E.; Read, A. M.; Tiengo, A.; Salvaterra, R.

    2016-05-01

    The detection of the first gravitational wave (GW) transient GW150914 prompted an extensive campaign of follow-up observations at all wavelengths. Although no dedicated XMM-Newton observations have been performed, the satellite passed through the GW150914 error region during normal operations. Here we report the analysis of the data taken during these satellite slews performed two hours and two weeks after the GW event. Our data cover 1.1 and 4.8 deg2 of the final GW localization region. No X-ray counterpart to GW150914 is found down to a sensitivity of 6 × 10‑13 erg cm‑2 s‑1 in the 0.2–2 keV band. Nevertheless, these observations show the great potential of XMM-Newton slew observations for searching for the electromagnetic counterparts of GW events. A series of adjacent slews performed in response to a GW trigger would take ≲1.5 days to cover most of the typical GW credible region. We discuss this scenario and its prospects for detecting the X-ray counterpart of future GW detections.

  11. Observations and Analysis of Mutual Events between the Uranus Main Satellites

    NASA Astrophysics Data System (ADS)

    Assafin, M.; Vieira-Martins, R.; Braga-Ribas, F.; Camargo, J. I. B.; da Silva Neto, D. N.; Andrei, A. H.

    2009-04-01

    Every 42 years, the Earth and the Sun pass through the plane of the orbits of the main satellites of Uranus. In these occasions, mutual occultations and eclipses between these bodies can be seen from the Earth. The current Uranus equinox from 2007 to 2009 offers a precious opportunity to observe these events. Here, we present the analysis of five occultations and two eclipses observed from Brazil during 2007. For the reduction of the CCD images, we developed a digital coronagraphic method that removed the planet's scattered light around the satellites. A simple geometric model of the occultation/eclipse was used to fit the observed light curves. Dynamical quantities such as the impact parameter, the relative speed, and the central time of the event were then obtained with precisions of 7.6 km, 0.18 km s-1, and 2.9 s, respectively. These results can be further used to improve the parameters of the dynamical theories of the main Uranus satellites. Based on observations made at Laboratório Nacional de Astrofísica (LNA), Itajubá-MG, Brazil.

  12. Ionospheric irregularities during a substorm event: Observations of ULF pulsations and GPS scintillations

    NASA Astrophysics Data System (ADS)

    Kim, H.; Clauer, C. R.; Deshpande, K.; Lessard, M. R.; Weatherwax, A. T.; Bust, G. S.; Crowley, G.; Humphreys, T. E.

    2014-07-01

    Plasma instability in the ionosphere is often observed as disturbances and distortions of the amplitude and phase of the radio signals, which are known as ionospheric scintillations. High-latitude ionospheric plasma, closely connected to the solar wind and magnetospheric dynamics, produces very dynamic and short-lived Global Positioning System (GPS) scintillations, making it challenging to characterize them. It is observed that scintillations in the high-latitude ionosphere occur frequently during geomagnetic storms and substorms. In addition, it is well known that Ultra Low Frequency (ULF) pulsations (Pi2 and Pi1B) are closely associated with substorm activity. This study reports simultaneous observations of Pi2 and Pi1B pulsations and GPS phase scintillations during a substorm using a newly designed Autonomous Adaptive Low-Power Instrument Platform (AAL-PIP) installed at the South Pole. The magnetic field and GPS data from the instruments appear to be associated in terms of their temporal and spectral features. Moreover, the scintillation events were observed near the auroral latitudes where Pi1B pulsations are commonly detected. The temporal, spectral and spatial association between the scintillation and geomagnetic pulsation events suggests that the magnetic field perturbations and enhanced electric fields caused by substorm currents could contribute to the creation of plasma instability in the high-latitude ionosphere, leading to GPS scintillations.

  13. Management of Toxoplasmic Retinochoroiditis during Pregnancy, Postpartum Period and Lactation: Clinical Observations

    PubMed Central

    Brydak-Godowska, Joanna; Moneta-Wielgoś, Joanna; Kęcik, Dariusz; Borkowski, Piotr Karol

    2015-01-01

    Background During pregnancy and labor, the immune response is physiologically impaired and women are more susceptible to infections. Since many drugs may have potentially adverse effects on the fetus and newborn, less aggressive treatment regimens should be considered in pregnant and lactating patients. The aim of our study was to present the management of toxoplasmic retinochoroiditis during pregnancy, postpartum period, and lactation. Material/Methods A retrospective study was undertaken of the clinical records of 24 women during pregnancy, postpartum period, and lactation who were referred in the years 1994–2014 to the Department of Zoonoses and Tropical Diseases or the Department of Ophthalmology, Medical University of Warsaw for toxoplasmic retinochoroiditis. The diagnosis was based on the typical ophthalmoscopic picture, confirmed by serological testing using an ELISA method. Results A total of 28 attacks of toxoplasmic retinochoroiditis were observed in 24 patients during pregnancy, postpartum period, and lactation. The choice of treatment was guided by the character and location of the inflammatory lesion and the gestational age. Topical (steroidal/nonsteroidal eye drops) and systemic treatments with spiramycin or azithromycin, Fansidar (pyrimethamine 25 mg/sulfadoxine 500 mg), and prednisone were used. Conclusions Management of toxoplasmic retinochoroiditis during pregnancy, postpartum period, or lactation must be individualized and guided by the gestational age and location of the active lesion. Women of childbearing age with toxoplasma ocular lesions should be informed by their doctors about possible active recurrences during pregnancy and followed carefully by an ophthalmologist when pregnant. PMID:25711713

  14. Confrontation Between a Quantized Periods of Some Exo-planetary Systems and Observations

    NASA Astrophysics Data System (ADS)

    El Fady Morcos, Abd

    2012-07-01

    Confrontation Between a Quantized Periods of Some Exo-planetary Systems and Observations A.B. Morcos Corot and Kepler were designed to detect Earth-like extra solar planets. The orbital elements and periods of these planets will contain some uncertainties. Many theoretical treatments depend on the idea of quantization were done aiming to find orbital elements of these exoplenets. In the present work, as an extension of previous works, the periods of some extoplanetary systems are calculated by using a simple derived formula. The orbital velocities of some of them are predicted . A comparison between the calculated and observed data is done References 1-J.M. Barnothy , the stability of the Solar System and of small Stellar Systems . (Y.Kazai edn,IAU,1974). 2-L.Nottale,Fractal Space-Time and Microphysics,Towards a Theory of Scale Relativity,( World Scientific, London,1994). 3-L. Nottale, A&A Lett. 315, L9 (1996). 4-L. Nottale, G. Schumacher and J. Gay, A&A , 322, 1018 , (1997). 5-L. Nottale, A&A , 361, 379 (2000). 6-A.G. Agnese and R.Festa, arXiv:astro-ph/9807186v1, (1998). 7-A.G. Agnese and R.Festa, arXiv:astro-ph/9910534v2. (1999). 8- A.B.Morcos, MG 12 , France (2009). 9- A.B.Morcs, Cospar 38 , Bremen , Germany (2010)

  15. Jellyfish: Observational Properties of Extreme Ram-Pressure Stripping Events in Massive Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Conor, McPartland; Ebeling, Harald; Roediger, Elke

    2015-08-01

    We investigate the physical origin and observational signatures of extreme ram-pressure stripping (RPS) in 63 massive galaxy clusters at z=0.3-0.7, based on data in the F606W passband obtained with the Advanced Camera for Surveys aboard the Hubble Space Telescope. Using a training set of a dozen ``jellyfish" galaxies identified earlier in the same imaging data, we define quantitative morphological criteria to select candidate galaxies which are similar to known cases of RPS. Considering a sample of 16 ``jellyfish" galaxies (10 of which we present for the first time), we visually derive estimates of the projected direction of motion based on dynamical features such as apparent compression shocks and debris trails. Our findings suggest that the observed events occur primarily at large distances from the cluster core and involve infall trajectories featuring high impact parameters. Simple models of cluster growth show that such trajectories are consistent with two scenarios: 1) galaxy infall along filaments; and 2) infall at high velocities (≥1000 km/s) characteristic of cluster mergers. The observed distribution of events is best described by timescales of ˜few Myr in agreement with recent numerical simulations of RPS. The broader areal coverage of the Hubble Frontier Fields should provide an even larger sample of RPS events to determine the relative contributions of infall and cluster mergers. Prompted by the discovery of several jellyfish galaxies whose brightness in the F606W passband rivals or exceeds that of the respective brightest cluster galaxy, we attempt to constrain the luminosity function of galaxies undergoing RPS. The observed significant excess at the bright end compared to the luminosity functions of blue cluster members strongly suggests enhanced star formation, thus challenging theoretical and numerical studies according to which RPS merely displaces existing star-forming regions. In-depth studies of individual objects will help test our

  16. Observing and modeling long-period tidal variations in polar motion

    NASA Astrophysics Data System (ADS)

    Gross, R. S.; Dickman, S. R.

    2011-10-01

    By exchanging angular momentum with the solid Earth, ocean tides cause the Earth's rotation to change. While hydrodynamic tide models have been used to study the effect of ocean tides on polar motion, it is shown here that none of the published models can fully account for the observed variations. An empirical ocean tide model is therefore determined by fitting periodic terms at the tidal frequencies to polar motion excitation observations spanning 1980.0-2010.4 from which atmospheric and non-tidal oceanic effects were removed. While the empirical ocean tide model does fully account for all of the observed tidal power, tests indicate that the model may not have completely converged. So better models of the effects of ocean tides on polar motion are still needed, both dynamical and empirical.

  17. Observing and Modeling Long-Period Tidal Variations in Polar Motion

    NASA Technical Reports Server (NTRS)

    Gross, Richard S.; Dickman, S. R.

    2011-01-01

    By exchanging angular momentum with the solid Earth, ocean tides cause the Earth's rotation to change. While hydrodynamic tide models have been used to study the effect of ocean tides on polar motion, it is shown here that none of the published models can fully account for the observed variations. An empirical ocean tide model is therefore determined by fitting periodic terms at the tidal frequencies to polar motion excitation observations, from which atmospheric and non-tidal oceanic effects were removed. While the empirical ocean tide model does fully account for allof the observed tidal power, tests indicate that the model may not have completely converged. So better models of the effects of ocean tides on polar motion are still needed, both dynamical and empirical.

  18. First simultaneous observations of a near-relativistic electron spike event by both STEREO spacecraft

    NASA Astrophysics Data System (ADS)

    Klassen, A.; Dresing, N.; Gómez-Herrero, R.; Heber, B.

    2015-08-01

    Solar electron spike events are a special subclass of near-relativistic electron events characterized by their short duration, symmetric time profile, and their strong anisotropic pitch angle distribution. All previous studied events were only observed by a single spacecraft (s/c). For the first time, we present measurements of this kind of an electron spike event that was observed simultaneously by both close-spaced STEREO s/c on 2 May 2014. The longitudinal separation angle between STEREO-A (STA) and STEREO-B (STB) was 38°. The spikes at STA and STB are characterized by very short durations of ≤12 min at full-width at half maximum (FWHM) and almost identical and symmetric time profiles. They exhibit similar properties in durations, pitch angle distributions (PADs), energy spectra, and peak intensities. The spike parent source was situated close to the STA nominal magnetic footpoint and was separated by 48° from STB's footpoint. The intensity distribution and the relative onset timing behaved opposite to what is expected: STB measured a higher intensity and an earlier onset than the nominally better connected STA. We suggest that the spike electrons undergo a substantial nonradial injection into interplanetary (IP) space from the parent source, a flaring active region (AR), and propagate in a strong nonradial diverging magnetic field. In addition we show that because of the spike properties it is evident that, irrespective of how the electrons were injected into the IP medium, the en route particle scattering conditions along the paths to STA and STB were very similar. Evidently both s/c detected different parts of the same beam whose angular extension was at least 38° at 1 AU, comparable to the longitudinal separation between STA and STB.

  19. Observations of 20-day period meridional current oscillations in the upper ocean along the Pacific Equator

    NASA Technical Reports Server (NTRS)

    Halpern, David; Knox, Robert A.; Luther, Douglas S.

    1988-01-01

    Prominent oscillations of the meridional current, with a mean period of approximately 20 days, is observed in the upper ocean from May 1979 to October 1985 using moored current measurements along the Pacific equator at 95, 110, 124, 140, and 152 deg W, as well as off (but near) the equator at 110 and 140 deg W. The fluctuations are relatively narrowband in frequency. A 95 percent statistically significant peak in the power spectra of the meridional current occurs at 110, 124, and 140 deg W, but not at 95 and 152 deg W where the spectral peaks are smaller. The dominant wave period decreases by about 4 percent from 110 to 140 deg W. The wave amplitude decreases with depth, and the wave is essentially confined to the upper 80 m. The penetration depth of the oscillation is greatest at 110 deg W and least at 140 deg W.

  20. SOHO/SWAN OBSERVATIONS OF SHORT-PERIOD SPACECRAFT TARGET COMETS

    SciTech Connect

    Combi, M. R.; Lee, Y.; Patel, T. S.; Maekinen, J. T. T.; Bertaux, J.-L.; Quemerais, E.

    2011-04-15

    SWAN, the Solar Wind ANisotropies all-sky hydrogen Ly{alpha} camera on the Solar and Heliospheric Observatory spacecraft that makes all-sky images of interplanetary neutral hydrogen, has an ongoing campaign to make special observations of comets, both short- and long-period ones, in addition to the serendipitous observations of comets as part of the all-sky monitoring program. We report here on a study of several short-period comets that were detected by SWAN: 21P/Giacobini-Zinner (1998 and 2005 apparitions), 19P/Borrelly (2001 apparition), 81P/Wild 2 (1997 apparition), and 103P/Hartley 2 (1997 apparition). SWAN observes comets over long continuous stretches of their visible apparitions and therefore provides excellent temporal coverage of the water production. For some of the observations we are also able to analyze an entire sequence of images over many days to several weeks/months using our time-resolved model and extract daily average water production rates over continuous periods of several days to months. The short-term (outburst) and long-term behavior can be correlated with other observations. The overall long-term variation is examined in light of seasonal effects seen in the pre- to post-perihelion differences. For 21P/Giacobini-Zinner and 81P/Wild 2 the activity variations over each apparition were more continuously monitored but nonetheless consistent with previous observations. For 19P/Borrelly we found a very steep variation of water production rates, again consistent with some previous observations, and a variation over six months around perihelion that was reasonably consistent with the spin-axis model of Schleicher et al. and the illumination of the main active areas. During the 1997-1998 apparition of 103P/Hartley 2, the target comet of the EPOXI mission (the Deep Impact extended mission), we found a variation with heliocentric distance ({approx}r{sup -3.6}) that was almost as steep as 19P/Borrelly and, given the small measured radius near

  1. An overview of present and future multi-point observations of SEP events

    NASA Astrophysics Data System (ADS)

    Vainio, R. O.

    2012-12-01

    I will present an overview of the present and future multi-point observations of solar energetic particle (SEP) events. The present fleet of interplanetary spacecraft carries several high-quality SEP instruments near the Earth (ACE, Wind, SOHO), at 1 AU on other heliolongitudes (STEREO), and in the inner heliosphere (MESSENGER). In addition, recent observations by Ulysses provide additional information on the propagation of SEPs to further radial distances and higher latitudes. In the future especially the instrumentation carried to the inner heliosphere will expand dramatically by the launches of Solar Orbiter, Solar Probe Plus, and BepiColombo. I will review some multi-spacecraft observations from the 24th solar cycle and discuss the findings in the light of SEP transport and acceleration modeling, and highlight some remaining open questions on the acceleration an transport of SEPs. Finally, I will discuss the foreseen capability of the future missions and models to give answers to these questions.

  2. The advantages of using a Lucky Imaging camera for observations of microlensing events

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Rahvar, Sohrab; Dominik, Martin; Hundertmark, Markus

    2016-05-01

    In this work, we study the advantages of using a Lucky Imaging camera for the observations of potential planetary microlensing events. Our aim is to reduce the blending effect and enhance exoplanet signals in binary lensing systems composed of an exoplanet and the corresponding parent star. We simulate planetary microlensing light curves based on present microlensing surveys and follow-up telescopes where one of them is equipped with a Lucky Imaging camera. This camera is used at the Danish 1.54-m follow-up telescope. Using a specific observational strategy, for an Earth-mass planet in the resonance regime, where the detection probability in crowded fields is smaller, Lucky Imaging observations improve the detection efficiency which reaches 2 per cent. Given the difficulty of detecting the signal of an Earth-mass planet in crowded-field imaging even in the resonance regime with conventional cameras, we show that Lucky Imaging can substantially improve the detection efficiency.

  3. First Ground-based Observation of Transient Luminous Events over Southern Africa

    NASA Astrophysics Data System (ADS)

    Nnadih, Ogechukwu; Kosch, Michael; Martinez, Peter

    2016-07-01

    We present the first ground-based observations in southern Africa of Transient Luminous Events (TLEs) in the summer of 2015/16 over convective thunderstorms. For the months of December to February, South Africa has one of the highest lightning stroke rates in the world. This was part of the AfriSprite campaign initiated by the South African National Space Agency. These observations show a variety of fine structures such as tree-like shaped, carrot, angel and jellyfish-shaped sprites. The South African Weather Service array of VLF receivers is used to locate and quantify the magnitude and polarity of the lightning strikes associated with TLEs. We plan to make bi-static as well as multi-wavelength observations in future.

  4. Ozone depletion events observed in the high latitude surface layer during the TOPSE aircraft program

    NASA Astrophysics Data System (ADS)

    Ridley, B. A.; Atlas, E. L.; Montzka, D. D.; Browell, E. V.; Cantrell, C. A.; Blake, D. R.; Blake, N. J.; Cinquini, L.; Coffey, M. T.; Emmons, L. K.; Cohen, R. C.; Deyoung, R. J.; Dibb, J. E.; Eisele, F. L.; Flocke, F. M.; Fried, A.; Grahek, F. E.; Grant, W. B.; Hair, J. W.; Hannigan, J. W.; Heikes, B. J.; Lefer, B. L.; Mauldin, R. L.; Moody, J. L.; Shetter, R. E.; Snow, J. A.; Talbot, R. W.; Thornton, J. A.; Walega, J. G.; Weinheimer, A. J.; Wert, B. P.; Wimmers, A. J.

    2003-02-01

    During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) aircraft program, ozone depletion events (ODEs) in the high latitude surface layer were investigated using lidar and in situ instruments. Flight legs of 100 km or longer distance were flown 32 times at 30 m altitude over a variety of regions north of 58° between early February and late May 2000. ODEs were found on each flight over the Arctic Ocean but their occurrence was rare at more southern latitudes. However, large area events with depletion to over 2 km altitude in one case were found as far south as Baffin Bay and Hudson Bay and as late as 22 May. There is good evidence that these more southern events did not form in situ but were the result of export of ozone-depleted air from the surface layer of the Arctic Ocean. Surprisingly, relatively intact transport of ODEs occurred over distances of 900-2000 km and in some cases over rough terrain. Accumulation of constituents in the frozen surface over the dark winter period cannot be a strong prerequisite of ozone depletion since latitudes south of the Arctic Ocean would also experience a long dark period. Some process unique to the Arctic Ocean surface or its coastal regions remains unidentified for the release of ozone-depleting halogens. There was no correspondence between coarse surface features such as solid ice/snow, open leads, or polynyas with the occurrence of or intensity of ozone depletion over the Arctic or subarctic regions. Depletion events also occurred in the absence of long-range transport of relatively fresh "pollution" within the high latitude surface layer, at least in spring 2000. Direct measurements of halogen radicals were not made. However, the flights do provide detailed information on the vertical structure of the surface layer and, during the constant 30 m altitude legs, measurements of a variety of constituents including hydroxyl and peroxy radicals. A summary of the behavior of these constituents is made. The

  5. Amoebae Anticipate Periodic Events

    NASA Astrophysics Data System (ADS)

    Saigusa, Tetsu; Tero, Atsushi; Nakagaki, Toshiyuki; Kuramoto, Yoshiki

    2008-01-01

    When plasmodia of the true slime mold Physarum were exposed to unfavorable conditions presented as three consecutive pulses at constant intervals, they reduced their locomotive speed in response to each episode. When the plasmodia were subsequently subjected to favorable conditions, they spontaneously reduced their locomotive speed at the time when the next unfavorable episode would have occurred. This implied the anticipation of impending environmental change. We explored the mechanisms underlying these types of behavior from a dynamical systems perspective.

  6. Two types of ion energy dispersions observed in the nightside auroral regions during geomagnetically disturbed periods

    NASA Astrophysics Data System (ADS)

    Hirahara, M.; Mukai, T.; Nagai, T.; Kaya, N.; Hayakawa, H.; Fukunishi, H.

    1996-04-01

    The Akebono satellite has observed two types of energy dispersion signatures of discrete ion precipitation event in the nightside auroral regions during active geomagnetic conditions. The charged particle experiments and electric and magnetic field detectors on board Akebono provide us with essential clues to characterize the source regions and acceleration and/or injection processes associated with these two types of ion signatures. The magnetic field data obtained simultaneously by the geosynchronous GOES 6 and 7 satellites and the ground magnetograms are useful to examine their relationships with geomagnetic activity. Mass composition data and pitch angle distributions show that different sources and processes should be attributed to two types (Types I and II) of energy dispersion phenomena. Type I consists of multiple bouncing ion clusters constituted by H+. These H+ clusters tend to be detected at the expansion phase of substorms and have characteristic multiple energy-dispersed signatures. Type II consists of O+ energy dispersion(s), which is often observed at the recovery phase. It is reasonable to consider that the H+ clusters of Type I are accelerated by dipolarization at the equator, are injected in the field-aligned direction, and bounce on closed field lines after the substorm onset. We interpret these multiple energy dispersion events as mainly due to the time-of-flight (TOF) effect, although the convection may influence the energy-dispersed traces. Based of the TOF model, we estimate the source distance to be 20-30 RE along the field lines. On the other hand, the O+ energy dispersion of Type II is a consequence of reprecipitation of terrestrial ions ejected as an upward flowing ion (UFI) beam from the upper ionosphere by a parallel electrostatic potential difference. The O+ energy dispersion is induced by the E×B drift during the field-aligned transport from the source region to the observation point.

  7. Development of an event search and download system for analyzing waveform data observed at seafloor seismic network, DONET

    NASA Astrophysics Data System (ADS)

    Takaesu, M.; Horikawa, H.; Sueki, K.; Kamiya, S.; Nakamura, T.; Nakano, M.; Takahashi, N.; Sonoda, A.; Tsuboi, S.

    2014-12-01

    Mega-thrust earthquakes are anticipated to occur in the Nankai Trough in southwest Japan. In the source areas, we installed seafloor seismic network, DONET (Dense Ocean-floor Network System for Earthquake and Tsunamis), in 2010 in order to monitor seismicity, crustal deformations, and tsunamis. DONET system consists of totally 20 stations, which is composed of six kinds of sensors; strong-motion and broadband seismometers, quartz and differential pressure gauges, hydrophone, and thermometer. The stations are densely distributed with an average spatial interval of 15-20 km and cover near coastal areas to the trench axis. Observed data are transferred to a land station through a fiber-optical cable and then to JAMSTEC (Japan Agency for Marine-Earth Science and Technology) data management center through a private network in real time. The data are based on WIN32 format in the private network and finally archived in SEED format in the management center to combine waveform data with related metadata. We are developing a web-based application system to easily download seismic waveform data of DONET. In this system, users can select 20 Hz broadband (BH type) and 200 Hz strong-motion (EH type) data and download them in SEED. Users can also search events from the options of time periods, magnitude, source area and depth in a GUI platform. Event data are produced referring to event catalogues from USGS and JMA (Japan Meteorological Agency). The thresholds of magnitudes for the production are M6 for far-field and M4 for local events using the USGS and JMA lists, respectively. Available data lengths depend on magnitudes and epicentral distances. In this presentation, we briefly introduce DONET stations and then show our developed application system. We open DONET data through the system and want them to be widely recognized so that many users analyze. We also discuss next plans for further developments of the system.

  8. Unexpected spatial intensity distributions and onset timing of solar electron events observed by closely spaced STEREO spacecraft

    NASA Astrophysics Data System (ADS)

    Klassen, A.; Dresing, N.; Gómez-Herrero, R.; Heber, B.; Müller-Mellin, R.

    2016-09-01

    We present multi-spacecraft observations of four solar electron events using measurements from the Solar Electron Proton Telescope (SEPT) and the Electron Proton Helium INstrument (EPHIN) on board the STEREO and SOHO spacecraft, respectively, occurring between 11 October 2013 and 1 August 2014, during the approaching superior conjunction period of the two STEREO spacecraft. At this time the longitudinal separation angle between STEREO-A (STA) and STEREO-B (STB) was less than 72°. The parent particle sources (flares) of the four investigated events were situated close to, in between, or to the west of the STEREO's magnetic footpoints. The STEREO measurements revealed a strong difference in electron peak intensities (factor ≤12) showing unexpected intensity distributions at 1 AU, although the two spacecraft had nominally nearly the same angular magnetic footpoint separation from the flaring active region (AR) or their magnetic footpoints were both situated eastwards from the parent particle source. Furthermore, the events detected by the two STEREO imply a strongly unexpected onset timing with respect to each other: the spacecraft magnetically best connected to the flare detected a later arrival of electrons than the other one. This leads us to suggest the concept of a rippled peak intensity distribution at 1 AU formed by narrow peaks (fingers) superposed on a quasi-uniform Gaussian distribution. Additionally, two of the four investigated solar energetic particle (SEP) events show a so-called circumsolar distribution and their characteristics make it plausible to suggest a two-component particle injection scenario forming an unusual, non-uniform intensity distribution at 1 AU.

  9. Fluid dynamics beneath a wet volcano inferred from the complex frequencies of long-period (LP) events: An example from Papandayan volcano, West Java, Indonesia during the 2011 seismic unrest

    NASA Astrophysics Data System (ADS)

    Kamil Syahbana, Devy; Caudron, Corentin; Jousset, Philippe; Lecocq, Thomas; Camelbeeck, Thierry; Bernard, Alain; Surono, Surono

    2014-05-01

    We present results of our study aiming at understanding the dynamics of fluids beneath a wet volcano through the analysis of swarms of long-period (LP) events accompanying the 2011 seismic unrest at Papandayan volcano, West Java, Indonesia. Prior to this unrest, we measured a large amount (100%) of CO2 in the ground at the summit crater, however with very low value of SO2 (less than 10 tons/day). Increase in volcanic activity was also observed from the records of a tiltmeter. A long-term inflation was followed by an abrupt deflation which was concurrent with the swarms of LP events. Hereafter, swarms of volcano-tectonic (VT) and local-tectonic (LT) earthquakes started. We focus here on analyzing the LP events with the following manner. First, we estimate the source location of LP events by applying a non-linear hypocenter algorithm including topography. We then study the waveforms and spectral characteristics of LP events and investigate whether or not these events are due to source effect. We compute the complex frequencies (f and Q) for the coda of the LP events using the Sompi method and subsequently, we estimate the physical processes related to the observed temporal variations in the complex frequencies by following the fluid-filled crack model. We divide the swarms of LP events into two periods. The first period occurred between June and July 2011 (48 LP events) while the second period started from September to October 2011 (36 LP events). The dominant frequencies (f) of LP events observed during these periods range between 1.1 and 6.2 Hz while the attenuation factors (Q) are widely scattered between 20 and 400. We estimate the compositions of fluids inside the crack during both periods as either water foam (mixtures of water and H2O gas/steam) or misty gas (mixtures of water droplets and H2O gas/steam). We finally suggest that if an eruption would have taken place following the 2011 unrest, it would have been in phreatic style rather than magmatic style. The

  10. Results of IPS Observations in the Period Near Solar Activity Minimum

    NASA Astrophysics Data System (ADS)

    Chashei, I. V.; Shishov, V. I.; Tyul'bashev, S. A.; Subaev, I. A.; Oreshko, V. V.

    2013-07-01

    IPS observations with the Big Scanning Array of Lebedev Physical Institute (BSA LPI) radio telescope at the frequency 111 MHz have been monitored since 2006. All the sources, about several hundred daily, with a scintillating flux greater than 0.2 Jy are recorded for 24 hours in the 16 beams of the radio telescope covering a sky strip of 8∘ declination width. We present some results of IPS observations for the recent period of low solar activity considering a statistical ensemble of scintillating radio sources. The dependences of the averaged over ensemble scintillation index on heliocentric distance are considerably weaker than the dependence expected for a spherically symmetric geometry. The difference is especially pronounced in the year 2008 during the very deep solar activity minimum period. These features are explained by the influence of the heliospheric current sheet that is seen as a strong concentration of turbulent solar wind plasma aligned with the solar equatorial plane. A local maximum of the scintillation index is found in the anti-solar direction. Future prospects of IPS observations using BSA LPI are briefly discussed.

  11. Statistical study on magnetotail lobe waves with period 40 - 600 s observed by Cluster

    NASA Astrophysics Data System (ADS)

    Wang, Guoqiang; Zhang, Tielong; Volwerk, Martin

    2016-04-01

    Ultra low frequency (ULF) waves play an important role in energy transport and dissipation in the magnetosphere. In this paper, 263 waves with period 40 - 150 s and 161 waves with period 150 - 600 s in the Earth's magnetotail lobe have been studied by using Cluster data from years 2001 to 2009. Our findings are as follows: (1) 90% of the wave amplitudes with period 40 - 150 s are below ~0.25 nT for transverse components, and ~0.16 nT for compressional component; The amplitudes of longer period waves are somewhat larger; For waves with period 150 - 600 s, 90% of the wave amplitudes are below ~0.36 nT and ~0.39 nT for transverse and compressional components, respectively. (2) Waves within 40 - 150 s prefer to occur in the lobe region close to the plasma sheet, while waves within 150 - 600 s can be observed throughout the lobe region; (3) The amplitudes of lobe waves and AE index are weakly correlated; However, we find that amplitudes tend to be larger when the AE index is larger; (4) Amplitudes also tend to be larger when the solar wind velocity, the solar wind dynamic pressure or its variations (∆PSW) is larger; The correlation coefficient between amplitudes of waves within 150 - 600 s and ∆PSW is up to ~0.58. We suggest that both dynamic pressure in the plasma sheet boundary layer or plasma sheet (inner source) and solar wind conditions (outer source) can contribute to the generation of lobe ULF waves; Waves within 40 - 150 s are effected more by inner source; ∆PSW is more associated with compressional waves within 150 - 600 s than that within 40 - 150 s.

  12. Subarcsecond bright points and quasi-periodic upflows below a quiescent filament observed by IRIS

    NASA Astrophysics Data System (ADS)

    Li, T.; Zhang, J.

    2016-04-01

    Context. The new Interface Region Imaging Spectrograph (IRIS) mission provides high-resolution observations of UV spectra and slit-jaw images (SJIs). These data have become available for investigating the dynamic features in the transition region (TR) below the on-disk filaments. Aims: The driver of "counter-streaming" flows along the filament spine is still unknown yet. The magnetic structures and the upflows at the footpoints of the filaments and their relations with the filament mainbody have not been well understood. We study the dynamic evolution at the footpoints of filaments in order to find some clues for solving these questions. Methods: Using UV spectra and SJIs from the IRIS, along with coronal images and magnetograms from the Solar Dynamics Observatory (SDO), we present the new features in a quiescent filament channel: subarcsecond bright points (BPs) and quasi-periodic upflows. Results: The BPs in the TR have a spatial scale of about 350-580 km and lifetimes of more than several tens of minutes. They are located at stronger magnetic structures in the filament channel with a magnetic flux of about 1017-1018 Mx. Quasi-periodic brightenings and upflows are observed in the BPs, and the period is about 4-5 min. The BP and the associated jet-like upflow comprise a "tadpole-shaped" structure. The upflows move along bright filament threads, and their directions are almost parallel to the spine of the filament. The upflows initiated from the BPs with opposite polarity magnetic fields have opposite directions. The velocity of the upflows in the plane of sky is about 5-50 km s-1. The emission line of Si IV 1402.77 Å at the locations of upflows exhibits obvious blueshifts of about 5-30 km s-1, and the line profile is broadened with the width of more than 20 km s-1. Conclusions: The BPs seem to be the bases of filament threads, and the upflows are able to convey mass for the dynamic balance of the filament. The "counter-streaming" flows in previous observations

  13. Subarcsecond bright points and quasi-periodic upflows below a quiescent filament observed by IRIS

    NASA Astrophysics Data System (ADS)

    Li, T.; Zhang, J.

    2016-05-01

    Context. The new Interface Region Imaging Spectrograph (IRIS) mission provides high-resolution observations of UV spectra and slit-jaw images (SJIs). These data have become available for investigating the dynamic features in the transition region (TR) below the on-disk filaments. Aims: The driver of "counter-streaming" flows along the filament spine is still unknown yet. The magnetic structures and the upflows at the footpoints of the filaments and their relations with the filament mainbody have not been well understood. We study the dynamic evolution at the footpoints of filaments in order to find some clues for solving these questions. Methods: Using UV spectra and SJIs from the IRIS, along with coronal images and magnetograms from the Solar Dynamics Observatory (SDO), we present the new features in a quiescent filament channel: subarcsecond bright points (BPs) and quasi-periodic upflows. Results: The BPs in the TR have a spatial scale of about 350-580 km and lifetimes of more than several tens of minutes. They are located at stronger magnetic structures in the filament channel with a magnetic flux of about 1017-1018 Mx. Quasi-periodic brightenings and upflows are observed in the BPs, and the period is about 4-5 min. The BP and the associated jet-like upflow comprise a "tadpole-shaped" structure. The upflows move along bright filament threads, and their directions are almost parallel to the spine of the filament. The upflows initiated from the BPs with opposite polarity magnetic fields have opposite directions. The velocity of the upflows in the plane of sky is about 5-50 km s-1. The emission line of Si IV 1402.77 Å at the locations of upflows exhibits obvious blueshifts of about 5-30 km s-1, and the line profile is broadened with the width of more than 20 km s-1. Conclusions: The BPs seem to be the bases of filament threads, and the upflows are able to convey mass for the dynamic balance of the filament. The "counter-streaming" flows in previous observations

  14. Compact object mergers: observations of supermassive binary black holes and stellar tidal disruption events

    NASA Astrophysics Data System (ADS)

    Komossa, S.; Zensus, J. A.

    2016-02-01

    The capture and disruption of stars by supermassive black holes (SMBHs), and the formation and coalescence of binaries, are inevitable consequences of the presence of SMBHs at the cores of galaxies. Pairs of active galactic nuclei (AGN) and binary SMBHs are important stages in the evolution of galaxy mergers, and an intense search for these systems is currently ongoing. In the early and advanced stages of galaxy merging, observations of the triggering of accretion onto one or both BHs inform us about feedback processes and BH growth. Identification of the compact binary SMBHs at parsec and sub-parsec scales provides us with important constraints on the interaction processes that govern the shrinkage of the binary beyond the ``final parsec''. Coalescing binary SMBHs are among the most powerful sources of gravitational waves (GWs) in the universe. Stellar tidal disruption events (TDEs) appear as luminous, transient, accretion flares when part of the stellar material is accreted by the SMBH. About 30 events have been identified by multi-wavelength observations by now, and they will be detected in the thousands in future ground-based or space-based transient surveys. The study of TDEs provides us with a variety of new astrophysical tools and applications, related to fundamental physics or astrophysics. Here, we provide a review of the current status of observations of SMBH pairs and binaries, and TDEs, and discuss astrophysical implications.

  15. Spectral lags of flaring events in LS I+61°303 from RXTE Observations

    NASA Astrophysics Data System (ADS)

    Sarkar, Tamal; Sarkar, Samir; Bhadra, Arunava

    2016-07-01

    This work reports the first discovery of (negative) spectral lags in X-ray emission below 10keV from the gamma ray binary LS I+61° 303 during large flaring episodes using Rossi X-ray Timing Explorer (RXTE) observations. It is found from the RXTE data that during the flares, low energy (3–5 keV) variations lead the higher energy (8–10 keV) variations by a few tens of seconds whereas no significant time lag is observed during the non-flaring states. The observed spectral lag features for flaring events suggest that inverse Compton scattering may be operating, at least in some part of the system. Another possibility is that the sites of particle acceleration may be different for flaring and non-flaring events such as in the microquasar model, in which the flaring radiation may come from hot spots sitting above the black hole while steady state emissions are due to the jets.

  16. OBSERVATIONS AND ANALYSIS OF MUTUAL EVENTS BETWEEN THE URANUS MAIN SATELLITES

    SciTech Connect

    Assafin, M.; Vieira-Martins, R.; Braga-Ribas, F.; Camargo, J. I. B.; Da Silva Neto, D. N.; Andrei, A. H. E-mail: rvm@on.br

    2009-04-15

    Every 42 years, the Earth and the Sun pass through the plane of the orbits of the main satellites of Uranus. In these occasions, mutual occultations and eclipses between these bodies can be seen from the Earth. The current Uranus equinox from 2007 to 2009 offers a precious opportunity to observe these events. Here, we present the analysis of five occultations and two eclipses observed from Brazil during 2007. For the reduction of the CCD images, we developed a digital coronagraphic method that removed the planet's scattered light around the satellites. A simple geometric model of the occultation/eclipse was used to fit the observed light curves. Dynamical quantities such as the impact parameter, the relative speed, and the central time of the event were then obtained with precisions of 7.6 km, 0.18 km s{sup -1}, and 2.9 s, respectively. These results can be further used to improve the parameters of the dynamical theories of the main Uranus satellites.

  17. MESSENGER observations of a flux-transfer-event shower at Mercury

    NASA Astrophysics Data System (ADS)

    Slavin, James A.; Imber, Suzanne M.; Boardsen, Scott A.; DiBraccio, Gina A.; Sundberg, Torbjorn; Sarantos, Menelaos; Nieves-Chinchilla, Teresa; Szabo, Adam; Anderson, Brian J.; Korth, Haje; Zurbuchen, Thomas H.; Raines, Jim M.; Johnson, Catherine L.; Winslow, Reka M.; Killen, Rosemary M.; McNutt, Ralph L., Jr.; Solomon, Sean C.

    2012-10-01

    Analysis of MESSENGER magnetic field observations taken in the southern lobe of Mercury's magnetotail and the adjacent magnetosheath on 11 April 2011 indicates that a total of 163 flux transfer events (FTEs) occurred within a 25 min interval. Each FTE had a duration of ˜2-3 s and was separated in time from the next by ˜8-10 s. A range of values have been reported at Earth, with mean values near ˜1-2 min and ˜8 min, respectively. We term these intervals of quasiperiodic flux transfer events “FTE showers.” The northward and sunward orientation of the interplanetary magnetic field during this shower strongly suggests that the FTEs observed during this event formed just tailward of Mercury's southern magnetic cusp. The point of origin for the shower was confirmed with the Cooling model of FTE motion. Modeling of the individual FTE-type flux ropes in the magnetosheath indicates that these flux ropes had elliptical cross sections, a mean semimajor axis of 0.15 RM (where RM is Mercury's radius, or 2440 km), and a mean axial magnetic flux of 1.25 MWb. The lobe magnetic field was relatively constant until the onset of the FTE shower, but thereafter the field magnitude decreased steadily until the spacecraft crossed the magnetopause. This decrease in magnetic field intensity is frequently observed during FTE showers. Such a decrease may be due to the diamagnetism of the new magnetosheath plasma being injected into the tail by the FTEs.

  18. Plasma Streaming and Explosive Events in the Solar Transition Region: Theory and Observations

    NASA Astrophysics Data System (ADS)

    Ryutova, M.; Tarbell, T.

    1999-05-01

    As shown by Tarbell et al. (ApJ, 514, L47, 1999 ) a sporadic excess of temperature and wide variety of plasma jets observed in the chromosphere and transition region overlying quiet sun regions may be explained by hydrodynamic cumulation resulted from the acoustic shocks generated by the reconnecting small scale network magnetic elements in the solar photosphere. Here we study magneto-hydrodynamic cumulation resulted from post-reconnection MHD shocks generated in complex magnetic field geometries typical to upper chromosphere and low corona. We present the results for the observed regularities obtained from simultaneous measurements taken by TRACE in chromospheric, transition region and coronal images and MDI on SOHO showing time series of high resolution magnetograms. We find that (1) All the essential features of the hydrodynamic cumulation remain in place: the MHD shocks driven by the post-reconnection sling-shot effect and self-focusing of these shocks lead to several well observed signatures of the energy release. (2) The evolution of generated flows depends on the geometry of intermittent magnetic fields and the height of jet formation. In regions of open magnetic structures plasma flows have tendency to accelerate and reach supersonic and super-Alfvenic velocities. Due to linear KH instability such flows may generate high frequency Alfven waves propagating along the magnetic structures. (3) In those regions where cumulative effects result in the predominant heating which is accompanied by generation of "moderate" (sub-Alfvenic) velocity jets, there are conditions when high velocity explosive events are driven. Our theoretical model shows that the explosive events proceeded by appearance of the bright transients are caused by the development of shear flow dissipative (nonlinear) instabilities. We also suggest that "non-bright"explosive events may be driven by rare effect of the cylindrical focusing of the MHD shocks (the Guderley's effect).

  19. Time Periods of Unusual Density Behavior Observed by GRACE and CHAMP

    NASA Astrophysics Data System (ADS)

    McLaughlin, C. A.; Fattig, E.; Mysore Krishna, D.; Locke, T.; Mehta, P. M.

    2011-12-01

    Time periods of low cross correlation between precision orbit ephemeris (POE) derived density and accelerometer density for CHAMP and GRACE are examined. In particular, the cross correlation for GRACE dropped from typical values near 0.9 to much lower values and then returned to typical over the time period of late October to late December of 2005. This time period includes a maneuver where GRACE-A and GRACE-B swapped positions. However, the drop in cross correlation begins and reaches its low point before the maneuvers begin. In addition, the densities were found using GRACE-A, but GRACE-B did most of the maneuvering. The time period is characterized by high frequency variations in accelerometer density of the same magnitude as the daylight to eclipse variations over the course of an orbit. However, the daylight to eclipse variations are particularly small during this time period because the orbit plane is near the terminator. Additionally, the difference between the accelerometer and POE derived densities are not unusually large during this time period. This implies the variations are not unusual, just more significant when the orbit plane is near terminator. Cyclical variations in correlation of the POE derived densities with accelerometer derived densities are seen for both GRACE and CHAMP, but the magnitude of the variations are much larger for GRACE, possibly because of the higher altitude of GRACE. The cycles seem to be phased so that low correlations occur with low beta angle when the orbit plane is near the terminator. The low correlation is possibly caused by the lower amplitude of the daylight to eclipse signal making higher frequency variations relatively more important. However, another possible explanation is terminator waves in density that propagate to the thermosphere from lower in the atmosphere. These waves have been observed in CHAMP accelerometer data and global circulation model simulations. Further investigation is needed to see if the

  20. Infrasonic observations and modeling of the Minor Uncle High Explosive event

    SciTech Connect

    Whitaker, R.; Noel, S.D.; Meadows, W.R.

    1994-09-01

    Minor Uncle was a Department of Defense sponsored explosive test of 2440 tons of ammonium nitrate and fuel oil (ANFO) executed on June 10, 1993, at White Sands Missile Range, NM. Los Alamos National Laboratory made infrasonic observations of this event at three stations: Los Alamos, NM, 250 km range; St. George, UT, 750 km range; and the Nevada Test Site, NV, 928 km range. All three stations obtained positive results and had very low background noise levels. Data from all stations will be presented, and normal mode calculations of the wave propagation, including upper atmospheric winds, to St. George will be compared to the data.

  1. High time resolution observation of the transient event of 5 March 1979

    NASA Technical Reports Server (NTRS)

    Weisskopf, M. C.; Darbro, W.; Ghosh, P.; Sutherland, P. G.; Grindlay, J.

    1980-01-01

    The detection of an intense gamma ray burst with the monitor proportional counter on the HEAO 2 spacecraft is discussed with particular emphasis on the measurement of the time of onset of the event. Based on the mean observed counting rate in the burst and assuming a sharp rise, the uncertainty in the burst onset is found to be + or - 220 microseconds. The time of occurrence was 57124.826908 + or - 0.000220 s UT on March 5, 1979, and the location of the HEAO 2 satellite at this time was latitude 22.15 deg, longitude -27.60 deg at an altitude of 525.0 km.

  2. Observation of a significant excess of pi0pi0 events in B meson decays.

    PubMed

    Aubert, B; Barate, R; Boutigny, D; Gaillard, J-M; Hicheur, A; Karyotakis, Y; Lees, J P; Robbe, P; Tisserand, V; Zghiche, A; Palano, A; Pompili, A; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Borgland, A W; Breon, A B; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Day, C T; Gill, M S; Gritsan, A V; Groysman, Y; Jacobsen, R G; Kadel, R W; Kadyk, J; Kerth, L T; Kolomensky, Yu G; Kral, J F; Kukartsev, G; LeClerc, C; Levi, M E; Lynch, G; Mir, L M; Oddone, P J; Orimoto, T J; Pripstein, M; Roe, N A; Romosan, A; Ronan, M T; Shelkov, V G; Telnov, A V; Wenzel, W A; Ford, K; Harrison, T J; Hawkes, C M; Knowles, D J; Morgan, S E; Penny, R C; Watson, A T; Watson, N K; Goetzen, K; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Peters, K; Schmuecker, H; Steinke, M; Barlow, N R; Boyd, J T; Chevalier, N; Cottingham, W N; Kelly, M P; Latham, T E; Mackay, C; Wilson, F F; Abe, K; Cuhadar-Donszelmann, T; Hearty, C; Mattison, T S; McKenna, J A; Thiessen, D; Kyberd, P; McKemey, A K; Blinov, V E; Bukin, A D; Golubev, V B; Ivanchenko, V N; Kravchenko, E A; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Yushkov, A N; Best, D; Bruinsma, M; Chao, M; Kirkby, D; Lankford, A J; Mandelkern, M; Mommsen, R K; Roethel, W; Stoker, D P; Buchanan, C; Hartfiel, B L; Shen, B C; Del Re, D; Hadavand, H K; Hill, E J; MacFarlane, D B; Paar, H P; Rahatlou, Sh; Sharma, V; Berryhill, J W; Campagnari, C; Dahmes, B; Kuznetsova, N; Levy, S L; Long, O; Lu, A; Mazur, M A; Richman, J D; Verkerke, W; Beck, T W; Beringer, J; Eisner, A M; Heusch, C A; Lockman, W S; Schalk, T; Schmitz, R E; Schumm, B A; Seiden, A; Turri, M; Walkowiak, W; Williams, D C; Wilson, M G; Albert, J; Chen, E; Dubois-Felsmann, G P; Dvoretskii, A; Hitlin, D G; Narsky, I; Porter, F C; Ryd, A; Samuel, A; Yang, S; Jayatilleke, S; Mancinelli, G; Meadows, B T; Sokoloff, M D; Abe, T; Blanc, F; Bloom, P; Chen, S; Clark, P J; Ford, W T; Nauenberg, U; Olivas, A; Rankin, P; Roy, J; Smith, J G; Van Hoek, W C; Zhang, L; Harton, J L; Hu, T; Soffer, A; Toki, W H; Wilson, R J; Zhang, J; Altenburg, D; Brandt, T; Brose, J; Colberg, T; Dickopp, M; Dubitzky, R S; Hauke, A; Lacker, H M; Maly, E; Müller-Pfefferkorn, R; Nogowski, R; Otto, S; Schubert, J; Schubert, K R; Schwierz, R; Spaan, B; Wilden, L; Bernard, D; Bonneaud, G R; Brochard, F; Cohen-Tanugi, J; Grenier, P; Thiebaux, Ch; Vasileiadis, G; Verderi, M; Khan, A; Lavin, D; Muheim, F; Playfer, S; Swain, J E; Andreotti, M; Azzolini, V; Bettoni, D; Bozzi, C; Calabrese, R; Cibinetto, G; Luppi, E; Negrini, M; Piemontese, L; Sarti, A; Treadwell, E; Anulli, F; Baldini-Ferroli, R; Biasini, M; Calcaterra, A; De Sangro, R; Falciai, D; Finocchiaro, G; Patteri, P; Peruzzi, I M; Piccolo, M; Pioppi, M; Zallo, A; Buzzo, A; Capra, R; Contri, R; Crosetti, G; Lo Vetere, M; Macri, M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Bailey, S; Morii, M; Won, E; Bhimji, W; Bowerman, D A; Dauncey, P D; Egede, U; Eschrich, I; Gaillard, J R; Morton, G W; Nash, J A; Sanders, P; Taylor, G P; Grenier, G J; Lee, S-J; Mallik, U; Cochran, J; Crawley, H B; Lamsa, J; Meyer, W T; Prell, S; Rosenberg, E I; Yi, J; Davier, M; Grosdidier, G; Höcker, A; Laplace, S; Le Diberder, F; Lepeltier, V; Lutz, A M; Petersen, T C; Plaszczynski, S; Schune, M H; Tantot, L; Wormser, G; Brigljević, V; Cheng, C H; Lange, D J; Wright, D M; Bevan, A J; Coleman, J P; Fry, J R; Gabathuler, E; Gamet, R; Kay, M; Parry, R J; Payne, D J; Sloane, R J; Touramanis, C; Back, J J; Harrison, P F; Shorthouse, H W; Strother, P; Vidal, P B; Brown, C L; Cowan, G; Flack, R L; Flaecher, H U; George, S; Green, M G; Kurup, A; Marker, C E; McMahon, T R; Ricciardi, S; Salvatore, F; Vaitsas, G; Winter, M A; Brown, D; Davis, C L; Allison, J; Barlow, R J; Forti, A C; Hart, P A; Hodgkinson, M C; Jackson, F; Lafferty, G D; Lyon, A J; Weatherall, J H; Williams, J C; Farbin, A; Jawahery, A; Kovalskyi, D; Lae, C K; Lillard, V; Roberts, D A; Blaylock, G; Dallapiccola, C; Flood, K T; Hertzbach, S S; Kofler, R; Koptchev, V B; Moore, T B; Saremi, S; Staengle, H; Willocq, S; Cowan, R; Sciolla, G; Taylor, F; Yamamoto, R K; Mangeol, D J J; Patel, P M; Lazzaro, A; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Cote-Ahern, D; Hast, C; Taras, P; Nicholson, H; Cartaro, C; Cavallo, N; De Nardo, G; Fabozzi, F; Gatto, C; Lista, L; Paolucci, P; Piccolo, D; Sciacca, C; Baak, M A; Raven, G; LoSecco, J M; Gabriel, T A; Brau, B; Gan, K K; Honscheid, K; Hufnagel, D; Kagan, H; Kass, R; Pulliam, T; Wong, Q K; Brau, J; Frey, R; Potter, C T; Sinev, N B; Strom, D; Torrence, E; Colecchia, F; Dorigo, A; Galeazzi, F; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Tiozzo, G; Voci, C; Benayoun, M; Briand, H; Chauveau, J; David, P; De La Vaissière, Ch; Del Buono, L; Hamon, O; John, M J J; Leruste, Ph; Ocariz, J; Pivk, M; Roos, L; Stark, J; T'Jampens, S; Therin, G; Manfredi, P F; Re, V; Behera, P K; Gladney, L; Guo, Q H; Panetta, J; Angelini, C; Batignani, G; Bettarini, S; Bondioli, M; Bucci, F; Calderini, G; Carpinelli, M; Del Gamba, V; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Martinez-Vidal, F; Morganti, M; Neri, N; Paoloni, E; Rama, M; Rizzo, G; Sandrelli, F; Walsh, J; Haire, M; Judd, D; Paick, K; Wagoner, D E; Danielson, N; Elmer, P; Lu, C; Miftakov, V; Olsen, J; Smith, A J S; Tanaka, H A; Varnes, E W; Bellini, F; Cavoto, G; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Mazzoni, M A; Morganti, S; Pierini, M; Piredda, G; Safai Tehrani, F; Voena, C; Christ, S; Wagner, G; Waldi, R; Adye, T; De Groot, N; Franek, B; Geddes, N I; Gopal, G P; Olaiya, E O; Xella, S M; Aleksan, R; Emery, S; Gaidot, A; Ganzhur, S F; Giraud, P-F; Hamel de Monchenault, G; Kozanecki, W; Langer, M; Legendre, M; London, G W; Mayer, B; Schott, G; Vasseur, G; Yeche, Ch; Zito, M; Purohit, M V; Weidemann, A W; Yumiceva, F X; Aston, D; Bartoldus, R; Berger, N; Boyarski, A M; Buchmueller, O L; Convery, M R; Coupal, D P; Dong, D; Dorfan, J; Dujmic, D; Dunwoodie, W; Field, R C; Glanzman, T; Gowdy, S J; Grauges-Pous, E; Hadig, T; Halyo, V; Hryn'ova, T; Innes, W R; Jessop, C P; Kelsey, M H; Kim, P; Kocian, M L; Langenegger, U; Leith, D W G S; Luitz, S; Luth, V; Lynch, H L; Marsiske, H; Messner, R; Muller, D R; O'Grady, C P; Ozcan, V E; Perazzo, A; Perl, M; Petrak, S; Ratcliff, B N; Robertson, S H; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Simi, G; Snyder, A; Soha, A; Stelzer, J; Su, D; Sullivan, M K; Va'vra, J; Wagner, S R; Weaver, M; Weinstein, A J R; Wisniewski, W J; Wright, D H; Young, C C; Burchat, P R; Edwards, A J; Meyer, T I; Petersen, B A; Roat, C; Ahmed, S; Alam, M S; Ernst, J A; Saleem, M; Wappler, F R; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Kim, H; Ritchie, J L; Schwitters, R F; Izen, J M; Kitayama, I; Lou, X C; Ye, S; Bianchi, F; Bona, M; Gallo, F; Gamba, D; Borean, C; Bosisio, L; Della Ricca, G; Dittongo, S; Grancagnolo, S; Lanceri, L; Poropat, P; Vitale, L; Vuagnin, G; Panvini, R S; Banerjee, Sw; Brown, C M; Fortin, D; Jackson, P D; Kowalewski, R; Roney, J M; Band, H R; Dasu, S; Datta, M; Eichenbaum, A M; Johnson, J R; Kutter, P E; Li, H; Liu, R; Di Lodovico, F; Mihalyi, A; Mohapatra, A K; Pan, Y; Prepost, R; Sekula, S J; von Wimmersperg-Toeller, J H; Wu, J; Wu, S L; Yu, Z; Neal, H

    2003-12-12

    We present a study of the decay B0-->pi(0)pi(0) based on a sample of 124 x 10(6) BB pairs recorded by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We observe 46+/-13+/-3 events, where the first error is statistical and the second is systematic, corresponding to a significance of 4.2 standard deviations including systematic uncertainties. We measure the branching fraction B(B0-->pi(0)pi(0))=(2.1+/-0.6+/-0.3)x10(-6), averaged over B0 and B(0) decays. PMID:14683107

  3. Characteristics of Electron Distributions Observed During Large Amplitude Whistler Wave Events in the Magnetosphere

    NASA Technical Reports Server (NTRS)

    Wilson, Lynn B., III

    2010-01-01

    We present a statistical study of the characteristics of electron distributions associated with large amplitude whistler waves inside the terrestrial magnetosphere using waveform capture data as an addition of the study by Kellogg et al., [2010b]. We identified three types of electron distributions observed simultaneously with the whistler waves including beam-like, beam/flattop, and anisotropic distributions. The whistlers exhibited different characteristics dependent upon the observed electron distributions. The majority of the waveforms observed in our study have f/fce < or = 0.5 and are observed primarily in the radiation belts outside the plasmapause simultaneously with anisotropic electron distributions. We also present an example waveform capture of the largest magnetic field amplitude (> or = 8 nT pk-pk) whistler wave measured in the radiation belts. The majority of the largest amplitude whistlers occur during magnetically active periods (AE > 200 nT).

  4. Observations of rapid-fire event tremor at Lascar volcano, Chile

    USGS Publications Warehouse

    Asch, Guenter; Wylegalla, K.; Hellweg, M.; Seidl, D.; Rademacher, H.

    1996-01-01

    During the Proyecto de Investigacio??n Sismolo??gica de la Cordillera Occidental (PISCO '94) in the Atacama desert of Northern Chile, a continuously recording broadband seismic station was installed to the NW of the currently active volcano, Lascar. For the month of April, 1994, an additional network of three, short period, three-component stations was deployed around the volcano to help discriminate its seismic signals from other local seismicity. During the deployment, the volcanic activity at Lascar appeared to be limited mainly to the emission of steam and SO2. Tremor from Lascar is a random, ??rapid-fire?? series of events with a wide range of amplitudes and a quasi-fractal structure. The tremor is generated by an ensemble of independent elementary sources clustered in the volcanic edifice. In the short-term, the excitation of the sources fluctuates strongly, while the long-term power spectrum is very stationary.

  5. Solar Particle Events Observed by the Odyssey MARIE Instrument at Mars: Dose and Model Calculations

    NASA Technical Reports Server (NTRS)

    Cleghorn, T. F.; Saganti, P. B.; Zeitlin, C. J.; Cucinotta, F. A.

    2003-01-01

    One of the primary concerns prior to human exploration of Mars is the need to accurately characterize the charged particle radiation environment both for the surface stay, and for the transit period to and from the planet. The Odyssey spacecraft, currently in Mars orbit includes a charged particle radiation detector, MARIE, which can measure particle fluxes with energies above approx. 30 MeV and charges between 1 and 10. Two classes of particles are of particular interest: the Galactic Cosmic Rays, (GCR), and those charged particles associated with Solar Particle Events, (SPE). The GCR are present continuously throughout the solar activity cycle, and their numbers vary inversely with the level of solar activity. They are characteristically more energetic than those particles originating from solar activity, and hence less influences by the solar magnetic field.

  6. Mutual events in the Uranian system: the 2007 Brazilian observational campaign by the Rio Group

    NASA Astrophysics Data System (ADS)

    Vieira Martins, R.; Assafin, M.; Camargo, J. I.; Ribas, F. B.; da Silva Neto, D. N.; Andrei, A. H.

    2008-09-01

    Following the mutual events in the Uranian system, predicted for 2007 by Arlot et al. (2006) for the LNA Observatory (site 874, Itajuba, Brazil), we have successfully recorded and reduced 14 events including hazing ones and comprising all main 5 satellites. From these, 6 occultations and 3 eclipses actually occurred, as predicted. Here we present the results. The observations were carried out at the 1.6m B&C telescope using an I filter to cut the planet light. To further diminish this effect, we have developed and applied a technique we call digital coronagraphy, which successfully eliminated the planet's light scatter to within only 5 arcsec from the planet. We applied a model which describes the light drop during the occultation, allowing for the determination of the central instant of occultation, of the impact parameter and of the albedo ratios. All obtained light curves are analyzed and discussed, including results for Miranda. Prospects for the upcoming Brazilian campaign of the mutual events of the Saturn system in 2009 are also given.

  7. Iodine observed in new particle formation events in the Arctic atmosphere during ACCACIA

    NASA Astrophysics Data System (ADS)

    Allan, J. D.; Williams, P. I.; Najera, J.; Whitehead, J. D.; Flynn, M. J.; Taylor, J. W.; Liu, D.; Darbyshire, E.; Carpenter, L. J.; Chance, R.; McFiggans, G.

    2014-11-01

    Accurately accounting for new particle formation (NPF) is crucial to our ability to predict aerosol number concentrations and thus cloud properties, which is in turn vital in simulating radiative transfer and climate. Here we present an analysis of NPF events observed in the Greenland Sea during the summertime as part of the Aerosol-Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) project. While NPF events have been reported in the Arctic before, we were able, for the first time, to detect iodine in the growing particles using an Aerosol Mass Spectrometer (AMS) during a persistent event in the region of the coastal sea ice near Greenland. Given the potency of iodine as a nucleation precursor, the results imply that iodine was responsible for the initial NPF, a phenomenon that has been reported at lower latitudes and associated with molecular iodine emissions from coastal macroalgae. The initial source of iodine in this instance is not clear, but it was associated with air originating approximately 1 day previously over melting coastal sea ice. These results show that atmospheric models must consider iodine as a source of new particles in addition to established precursors such as sulphur compounds.

  8. Iodine observed in new particle formation events in the Arctic atmosphere during ACCACIA

    NASA Astrophysics Data System (ADS)

    Allan, J. D.; Williams, P. I.; Najera, J.; Whitehead, J. D.; Flynn, M. J.; Taylor, J. W.; Liu, D.; Darbyshire, E.; Carpenter, L. J.; Chance, R.; Andrews, S. J.; Hackenberg, S. C.; McFiggans, G.

    2015-05-01

    Accurately accounting for new particle formation (NPF) is crucial to our ability to predict aerosol number concentrations in many environments and thus cloud properties, which is in turn vital in simulating radiative transfer and climate. Here we present an analysis of NPF events observed in the Greenland Sea during the summertime as part of the Aerosol-Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) project. While NPF events have been reported in the Arctic before, we were able, for the first time, to detect iodine in the growing particles using an Aerosol Mass Spectrometer (AMS) during a persistent event in the region of the coastal sea-ice near Greenland. Given the potency of iodine as a nucleation precursor, the results imply that iodine was responsible for the initial NPF, a phenomenon that has been reported at lower latitudes and associated with molecular iodine emissions from coastal macroalgae. The initial source of iodine in this instance is not clear, but it was associated with air originating approximately 1 day previously over melting coastal sea-ice. These results show that atmospheric models must consider iodine as a source of new particles in addition to established precursors such as sulfur compounds.

  9. IUE observations of long period eclipsing binaries - A study of accretion onto non-degenerate stars

    NASA Technical Reports Server (NTRS)

    Plavec, M. J.

    1980-01-01

    IUE observations made in 1978-1979 recorded a whole class of interacting long-period binaries similar to beta Lyrae, which includes RX Cas, SX Cas, V 367 Cyg, W Cru, beta Lyr, and W Ser, called the W Serpentis stars. These mass-transferring binaries with relatively high mass transfer rate show two prominent features in the far ultraviolet: a continuum with a color temperature higher than the one observed in the optical region (about 12,000 K), and a strong emission line spectrum with the N V doublet at 1240 A, C IV doublet at 1550 A and lines of Si II, Si III, Si IV, C II, Fe III, AI III, etc. These phenomena are discussed on the assumption that they are due to accretion onto non-degenerate stars.

  10. Observation of gamma rays with a 4.8 hour periodicity from CYG X-3

    NASA Technical Reports Server (NTRS)

    Lamb, R. C.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.

    1976-01-01

    Energetic (E35 MeV) Gamma rays were observed from Cyg X-3 with the SAS-2 Gamma ray telescope. They are modulated at the 4.8 sup h period observed in the X-ray and infrared regions, and within the statistical error are in phase with this emission. The flux above 100 MeV has an average value of (4.4 + or - 1.1)x 10 to the -6 power/sq cm/sec. If the distance to Cyg X-3 is 10 kpcs, this flux implies a luminosity of more than 10 to the 37th power ergs/s if the radiation is isotropic and about 10 to the 36th power ergs/s if the radiation is restricted to a cone of one steradian, as it might be in a pulsar.

  11. Ginga observations of quasi-periodic oscillations in type II bursts from the Rapid Burster

    NASA Technical Reports Server (NTRS)

    Dotani, T.; Mitsuda, K.; Inoue, H.; Tanaka, Y.; Kawai, N.

    1990-01-01

    During Ginga observations of the 'Rapid Burster' in August 1988, strong quasi-periodic oscillations (QPOs) were detected in its X-ray intensity. The QPOs had centroid frequencies of 5 and 2 Hz during type II X-ray bursts which lasted for 10 and 30 s, respectively. The presence of the QPOs is correlated with the time scale-invariant burst profile. They are very strong during the initial peak in the burst, absent in the second peak, and strong again at the onset of the third peak. From an analysis of the X-ray spectrum as observed during the maxima and minima of the oscillations, it is found that the oscillations can be described by changes of the temperature of a blackbody emitter of constant apparent area.

  12. Effects of amines on particle growth observed in new particle formation events

    NASA Astrophysics Data System (ADS)

    Tao, Ye; Ye, Xingnan; Jiang, Shuqing; Yang, Xin; Chen, Jianmin; Xie, Yuanyuan; Wang, Ruyu

    2016-01-01

    Particle size distributions in the range of 0.01-10 µm were measured in urban Shanghai in the summer of 2013 using a Wide-range Particle Spectrometer (WPS). Size-segregated aerosol samples were collected concurrently using a Micro-Orifice Uniform Deposit Impactor (MOUDI), which aided our in-depth understanding of the new particle formation (NPF) mechanism in the polluted Yangtze River Delta area. During the observations, 16 NPF events occurred at high temperatures (~34.7°C) on clear and sunny days. In the ammonium-poor PM1.0 (particulate matter less than 1.0 µm), sulfate and ammonium accounted for 92% of the total water-soluble inorganic species. Six aminiums were detected in these MOUDI samples, among which the group of diethylaminium and trimethylaminium (DEAH+ + TMAH+) was the most abundant. The very high level of aminiums (average concentration up to 86.4 ng m-3 in PM1.8), together with highly acidic aerosols, provided insight into the frequent NPF events. The high mass ratio of total aminiums to NH4+ (>0.2 for PM0.056) further highlighted the important role of amines in promoting NPF. The concentration of DEAH+ + TMAH+ in new particles below 180 nm was strongly correlated with aerosol phase acidity, indicating that acid-base reactions dominated the aminium formation in NPF events. The unexpected enhancement of DEAH+ + TMAH+ on a nonevent day was attributed to the transportation of an SO2 plume. Our results reveal that the heterogeneous uptake of amines is dominated by the acid-base reaction mechanism, which can effectively contribute to particle growth in NPF events.

  13. African Monsoon Multidisciplinary Analysis (AMMA) : The Special Observing Period of 2006

    NASA Astrophysics Data System (ADS)

    Polcher, J.; Cairo, F.; Fierli, F.; Höller, H.; Law, K.; Mari, C.; Reeves, C.; Schlager, H.

    2006-12-01

    The AMMA project aims at enhancing our understanding of the West African monsoon and its underlying physical, chemical and biological processes. This enhanced knowledge of the processes involved in the establishment and variability of the monsoon will be used to improve our capacity to predict it and evaluate the impacts on land-productivity, management of water resources and public health. The objective is to provide societies in Africa with improved tools to manage their dependence on environmental conditions. In the framework of AMMA a dense observational network has been established both as routine and campaign- based facilities. The aim is to provide a complete picture of the physical, chemical and biological processes over the ocean, the continent and in the atmosphere. The base network has been established over the last few year and covers surface states and surface flux monitoring in a number catchments over the climatic gradient of the region. The upper-air sounding network was upgraded and enhanced to improve the data available for operational weather forecasting. During 2006 AMMA supported a large field campaign to cover the dry season (SOP0), the monsoon onset (SOP1) and the wet season (SOP2). The enhancement to the observing system in 2006 included balloon borne instruments, a lightning network over northern Benin, 3 research vessels and 5 research aircraft stationed in the Niamey and Ouagadougou. Most of SOP2 observations were dedicated to the intense mesoscale convective systems which are generated in the region and travel to the West. Their impact on the circulation in the troposphere and lower stratosphere, the water cycle in the region and the transport of trace gases and aerosols have been observed at different stages of the life cycle of these systems. This talk will provide a overview of the AMMA project and the observations carried out in 2006, focusing on the most relevant events.

  14. Using ACE Observations of Interplanetary Particles and Magnetic Fields as Possible Contributors to Variations Observed at Van Allen Probes during Major events in 2013

    NASA Astrophysics Data System (ADS)

    Armstrong, T. P.; Manweiler, J. W.; Gerrard, A. J.; Gkioulidou, M.; Lanzerotti, L. J.; Patterson, J. D.

    2013-12-01

    Observations from ACE EPAM including energy spectra of protons, helium, and oxygen will be prepared for coordinated use in estimating the direct and indirect access of energetic particles to inner and outer geomagnetic trapping zones. Complete temporal coverage from ACE at 12 seconds, 5 minutes, 17 minutes, hourly and daily cadences will be used to catalog interplanetary events arriving at Earth including interplanetary magnetic field sector boundaries, interplanetary shocks, and interplanetary coronal mass ejections, ICMEs. The first 6 months of 2013 have included both highly disturbed times, March 17 and May 22, and extended quiet periods of little or no variations. Among the specific questions that ACE and Van Allen Probes coordinated observations may aid in resolving are: 1. How much, if any, direct capture of interplanetary energetic particles occurs and what conditions account for it? 2. How much influence do interplanetary field and particle variations have on energization and/or loss of geomagnetically trapped populations? The poster will also present important links and describe methods and important details of access to numerically expressed ACE EPAM and Van Allen Probes RBSPICE observations that can be flexibly and easily accessed via the internet for student and senior researcher use.

  15. Observations of reverse polarity flux transfer events at the earth's dayside magnetopause

    NASA Technical Reports Server (NTRS)

    Rijnbeek, R. P.; Cowley, S. W. H.; Southwood, D. J.; Russell, C. T.

    1982-01-01

    High resolution plasma and magnetic field measurements made by the ISEE 1 and 2 spacecraft have provided the first definitive observations of magnetic reconnection at the dayside boundary, occurring either as a large-scale, quasisteady process enduring on time scales of at least tens of minutes or as a transient process localized in both temporal and spatial extent. Observations of flux transfer events (FTEs) at the earth's dayside magnetopause are presented which have plasma and magnetic field signatures reversed in sign from those previously reported. These FTEs are interpreted in terms of localized and transitory reconnection with the spacecraft located south of the reconnection site. They are associated with a previously reported interval of quasisteady reconnection which is similarly located, indicating that a close physical connection exists between the two processes.

  16. High Cadence Observations and Analysis of Spicular-type Events Using CRISP Onboard SST

    NASA Astrophysics Data System (ADS)

    Shetye, J.; Doyle, J. G.; Scullion, E.; Nelson, C. J.; Kuridze, D.

    2016-04-01

    We present spectroscopic and imaging observations of apparent ultra-fast spicule-like features observed with CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish 1-m Solar Telescope (SST). The data shows spicules with an apparent velocity above 500 km s-1, very short lifetimes of up to 20 s and length/height around 3500 km. The spicules are seen as dark absorption structures in the Hα wings ±516 mÅ, ±774 mÅ and ±1032 mÅ which suddenly appear and disappear from the FOV. These features show a time delay in their appearance in the blue and red wings by 3-5 s. We suggest that their appearance/disappearance is due to their Doppler motion in and out of the 60 mÅ filter. See Fig. 1 for the evolution of the event at two line positions.

  17. The Connection between the Corona and Chromosphere during a Multiple Event Observation

    NASA Technical Reports Server (NTRS)

    Cirtain, Jonathan

    2008-01-01

    NOAA AR 10940 (Jan 25 2007 - Feb 09 2007) rotated into view producing a CME and EIT wave, and followed by at least 27 B and C class flares as rotated across the disk. As it reached the west limb it proceeded to produce a sequence of jets and filament eruptions that were observed in unprecedented detail. I present observations from TRACE, EIT, HINODE XRT / SOT / EIS, RHESSI, GOES 12 and STEREO-A COR 1 to investigate part of the sequence of events that lead to a filament eruption and sympathetic jet at 02:30 - 03:00 02/09/07. I concentrate on the topology changes and infer that external breakout reconnection was the mechanism that lead to the removal of overlying field and subsequent filament eruption I will also discuss the instrument development activities at MSFC.

  18. Continuous GPS observations of crustal loading from hydrometeorological events on the scale of storms to drought

    NASA Astrophysics Data System (ADS)

    Borsa, A. A.; Cayan, D. R.; Agnew, D. C.

    2015-12-01

    Recent studies using continuous GPS to estimate changes in terrestrial water storage point to a future where the global GPS infrastructure for monitoring crustal deformation can be leveraged for hydrological applications. Seasonal water and snow loading has long been known to generate an elastic earth response that is observable by GPS, but only recently have these signals been modeled to recover the underlying loads at local and regional scales. It has also been shown that GPS can be used to monitor subtle surface deformation due to the response of the hydrological system to drought, and to estimate the magnitude and spatial distribution of related water loss. In this work, we extend the temporal range of the analysis from drought-focused interannual signals to event-scale loading from individual storms and show the promise and challenges of applying GPS observations to these new higher-frequency hydrometeorological phenomena. We also estimate the magnitude and distribution of surface water fluctuations from recent extreme precipitation events in the continental USA and show how GPS might be used to better characterize the accompanying water storage changes and potential hydrometerological hazards.

  19. Estimating observing locations for advancing beyond the winter predictability barrier of Indian Ocean dipole event predictions

    NASA Astrophysics Data System (ADS)

    Feng, Rong; Duan, Wansuo; Mu, Mu

    2016-04-01

    In this paper, we explored potential observing locations (i.e., the sensitive areas) of positive Indian Ocean dipole (IOD) events to advance beyond the winter predictability barrier (WPB) using the geophysical fluid dynamics laboratory climate model version 2p1 (GFDL CM2p1). The sensitivity analysis is conducted through perfect model predictability experiments, in which the model is assumed to be perfect and so any prediction errors are caused by initial errors. The results show that the initial errors with an east-west dipole pattern are more likely to result in a significant WPB than spatially correlated noises; the areas where the large values of the dipole pattern initial errors are located have great effects on prediction uncertainties in winter and provide useful information regarding the sensitive areas. Further, the prediction uncertainties in winter are more sensitive to the initial errors in the subsurface large value areas than to those in the surface large value areas. The results indicate that the subsurface large value areas are sensitive areas for advancing beyond the WPB of IOD predictions and if we carry out intensive observations across these areas, the prediction errors in winter may be largely reduced. This will lead to large improvements in the skill of wintertime IOD event forecasts.

  20. Event-Driven Observations and Comprehensive Evaluation for Natural Disaster Assessment in China

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Li, Z.; Shen, Y.; Wu, L.; Li, H.

    2012-08-01

    The Chinese event-driven observations and disaster assessment system is established so as to make information related to environmental risk and vulnerability easily accessible to decision-makers through this centralized platform. At 7:49 AM on April 14, 2010, an earthquake of 7.1 magnitude collapsed buildings in Yushu County, Yushu Tibetan Autonomous Prefecture in Qinghai Province. For emergence response, we presented a method for generating seismic intensity map based on seismological mechanism solutions. The disaster assessment system automatically drew the distribution map of affected population 1 hour after the Yushu earthquake. In the case of distribution map of affected population, we made the judgment that the Gyêgu town maybe the worst hit town in the Yushu earthquake because it is not only near the epicenter, but also the capital of Yushu Tibetan Autonomous Prefecture. Then event-driven observations are taken on Gyêgu town. Referring to usable data, the chains of rapid assessment on earthquake disaster were analyzed, and different models were established for assessing affected population, damaged houses and lifelines and comprehensive earthquake loss evaluation.

  1. Detection of Rain-on-Snow (ROS) Events Using the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and Weather Station Observations

    NASA Astrophysics Data System (ADS)

    Ryan, E. M.; Brucker, L.; Forman, B. A.

    2015-12-01

    During the winter months, the occurrence of rain-on-snow (ROS) events can impact snow stratigraphy via generation of large scale ice crusts, e.g., on or within the snowpack. The formation of such layers significantly alters the electromagnetic response of the snowpack, which can be witnessed using space-based microwave radiometers. In addition, ROS layers can hinder the ability of wildlife to burrow in the snow for vegetation, which limits their foraging capability. A prime example occurred on 23 October 2003 in Banks Island, Canada, where an ROS event is believed to have caused the deaths of over 20,000 musk oxen. Through the use of passive microwave remote sensing, ROS events can be detected by utilizing observed brightness temperatures (Tb) from AMSR-E. Tb observed at different microwave frequencies and polarizations depends on snow properties. A wet snowpack formed from an ROS event yields a larger Tb than a typical dry snowpack would. This phenomenon makes observed Tb useful when detecting ROS events. With the use of data retrieved from AMSR-E, in conjunction with observations from ground-based weather station networks, a database of estimated ROS events over the past twelve years was generated. Using this database, changes in measured Tb following the ROS events was also observed. This study adds to the growing knowledge of ROS events and has the potential to help inform passive microwave snow water equivalent (SWE) retrievals or snow cover properties in polar regions.

  2. An overview of the lightning and atmospheric electricity observations collected in Southern France during the HYdrological cycle in Mediterranean EXperiment (HyMeX), Special Observation Period 1

    NASA Astrophysics Data System (ADS)

    Defer, E.; Pinty, J.-P.; Coquillat, S.; Martin, J.-M.; Prieur, S.; Soula, S.; Richard, E.; Rison, W.; Krehbiel, P.; Thomas, R.; Rodeheffer, D.; Vergeiner, C.; Malaterre, F.; Pedeboy, S.; Schulz, W.; Farges, T.; Gallin, L.-J.; Ortéga, P.; Ribaud, J.-F.; Anderson, G.; Betz, H.-D.; Meneux, B.; Kotroni, V.; Lagouvardos, K.; Roos, S.; Ducrocq, V.; Roussot, O.; Labatut, L.; Molinié, G.

    2014-08-01

    The PEACH (Projet en Electricité Atmosphérique pour la Campagne HyMeX - the Atmospheric Electricity Project of HyMeX Program) project is the Atmospheric Electricity component of the HyMeX (Hydrology cycle in the Mediterranean Experiment) experiment and is dedicated to the observation of both lightning activity and electrical state of continental and maritime thunderstorms in the area of the Mediterranean Sea. During the HyMeX SOP1 (Special Observation Period; 5 September-6 November 2012), four European Operational Lightning Locating Systems (OLLSs) (ATDNET, EUCLID, LINET, ZEUS) and the HyMeX Lightning Mapping Array network (HyLMA) were used to locate and characterize the lightning activity over the Southeastern Mediterranean at flash, storm and regional scales. Additional research instruments like slow antennas, video cameras, micro-barometer and microphone arrays were also operated. All these observations in conjunction with operational/research ground-based and airborne radars, rain gauges and in situ microphysical records aimed at characterizing and understanding electrically active and highly precipitating events over Southeastern France that often lead to severe flash floods. Simulations performed with Cloud Resolving Models like Meso-NH and WRF are used to interpret the results and to investigate further the links between dynamics, microphysics, electrification and lightning occurrence. A description of the different instruments deployed during the field campaign as well as the available datasets is given first. Examples of concurrent observations from radio frequency to acoustic for regular and atypical lightning flashes are then presented showing a rather comprehensive description of lightning flashes available from the SOP1 records. Then examples of storms recorded during HyMeX SOP1 over Southeastern France are briefly described to highlight the unique and rich dataset collected. Finally the next steps of the work required for the delivery of reliable

  3. Strong aerosol-cloud interaction in altocumulus during updraft periods: lidar observations over central Europe

    NASA Astrophysics Data System (ADS)

    Schmidt, J.; Ansmann, A.; Bühl, J.; Wandinger, U.

    2015-09-01

    For the first time, a liquid-water cloud study of the aerosol-cloud-dynamics relationship, solely based on lidar, was conducted. Twenty-nine cases of pure liquid-water altocumulus layers were observed with a novel dual-field-of-view Raman lidar over the polluted central European site of Leipzig, Germany, between September 2010 and September 2012. By means of the novel Raman lidar technique, cloud properties such as the droplet effective radius and cloud droplet number concentration (CDNC) in the lower part of altocumulus layers are obtained. The conventional aerosol Raman lidar technique provides the aerosol extinction coefficient (used as aerosol proxy) below cloud base. A collocated Doppler lidar measures the vertical velocity at cloud base and thus updraft and downdraft occurrence. Here, we present the key results of our statistical analysis of the 2010-2012 observations. Besides a clear aerosol effect on cloud droplet number concentration in the lower part of the altocumulus layers during updraft periods, turbulent mixing and entrainment of dry air is assumed to be the main reason for the found weak correlation between aerosol proxy and CDNC higher up in the cloud. The corresponding aerosol-cloud interaction parameter based on changes in cloud droplet number concentration with aerosol loading was found to be close to 0.8 at 30-70 m above cloud base during updraft periods and below 0.4 when ignoring vertical-wind information in the analysis. Our findings are extensively compared with literature values and agree well with airborne observations.

  4. Fog Induced Aerosol Modification Observed by AERONET, Including Occurrences During Major Air Pollution Events

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Giles, D. M.; Rivas, M.; Singh, R. P.; Tripathi, S. N.; Bruegge, C. J.; Li, Z.; Platnick, S. E.; Arnold, T.; Ferrare, R. A.; Hostetler, C. A.; Burton, S. P.; Kim, J.; Kim, Y. J.; Sinyuk, A.; Dubovik, O.; Arola, A. T.; Schafer, J.; Artaxo, P.; Smirnov, A.; Chen, H.; Goloub, P.

    2014-12-01

    The modification of aerosol optical properties due to interaction with fog is examined from measurements made by sun/sky radiometers at several AERONET sites. Retrieved total column volume size distributions for cases identified as aerosol modified by fog often show very a large 'middle mode' submicron radius (~0.4 to 0.5 microns), which is typically seen as a component of a bimodal sub-micron distribution. These middle mode sized particles are often called cloud-processed or residual aerosol. This bimodal accumulation mode distribution may be due to one mode (the larger one) from fog-processed aerosol and the other from interstitial aerosol, or possibly from two different aerosol species (differing chemical composition) with differing hygroscopic growth factors. The size of the fine mode particles from AERONET retrieved for these cases exceeds the size of sub-micron sized particles retrieved for nearly all other aerosol types, suggesting significant modification of aerosols within the fog or cloud environment. In-situ measured aerosol size distributions made during other fog events are compared to the AERONET retrievals, and show close agreement in the residual mode particle size. Almucantar retrievals are analyzed from the Kanpur site in the Indo-Gangetic Plain in India (fog in January), Beijing (fog in winter), Fresno, CA in the San Joaquin Valley (fog in winter), South Korea (Yellow Sea fog in spring), Arica on the northern coast of Chile (stratocumulus), and several other sites with aerosol observations made after fog dissipated. Additionally, several major air pollution events are discussed where extremely high aerosol concentrations were measured at the surface and during which fog also occurred, resulting in the detection very large fine mode aerosols (residual mode) from AERONET retrievals in some of these events. Low wind speeds that occurred during these events were conducive to both pollutant accumulation and also fog formation. The presence of fog then

  5. Fog Induced Aerosol Modification Observed by AERONET, Including Occurrences During Major Air Pollution Events

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Giles, D. M.; Rivas, M.; Singh, R. P.; Tripathi, S. N.; Bruegge, C. J.; Li, Z.; Platnick, S. E.; Arnold, T.; Ferrare, R. A.; Hostetler, C. A.; Burton, S. P.; Kim, J.; Kim, Y. J.; Sinyuk, A.; Dubovik, O.; Arola, A. T.; Schafer, J.; Artaxo, P.; Smirnov, A.; Chen, H.; Goloub, P.

    2015-12-01

    The modification of aerosol optical properties due to interaction with fog is examined from measurements made by sun/sky radiometers at several AERONET sites. Retrieved total column volume size distributions for cases identified as aerosol modified by fog often show very a large 'middle mode' submicron radius (~0.4 to 0.5 microns), which is typically seen as a component of a bimodal sub-micron distribution. These middle mode sized particles are often called cloud-processed or residual aerosol. This bimodal accumulation mode distribution may be due to one mode (the larger one) from fog-processed aerosol and the other from interstitial aerosol, or possibly from two different aerosol species (differing chemical composition) with differing hygroscopic growth factors. The size of the fine mode particles from AERONET retrieved for these cases exceeds the size of sub-micron sized particles retrieved for nearly all other aerosol types, suggesting significant modification of aerosols within the fog or cloud environment. In-situ measured aerosol size distributions made during other fog events are compared to the AERONET retrievals, and show close agreement in the residual mode particle size. Almucantar retrievals are analyzed from the Kanpur site in the Indo-Gangetic Plain in India (fog in January), Beijing (fog in winter), Fresno, CA in the San Joaquin Valley (fog in winter), South Korea (Yellow Sea fog in spring), Arica on the northern coast of Chile (stratocumulus), and several other sites with aerosol observations made after fog dissipated. Additionally, several major air pollution events are discussed where extremely high aerosol concentrations were measured at the surface and during which fog also occurred, resulting in the detection very large fine mode aerosols (residual mode) from AERONET retrievals in some of these events. Low wind speeds that occurred during these events were conducive to both pollutant accumulation and also fog formation. The presence of fog then

  6. Source mechanism of small long-period events at Mount St. Helens in July 2005 using template matching, phase-weighted stacking, and full-waveform inversion

    USGS Publications Warehouse

    Matoza, Robin S.; Chouet, Bernard A.; Dawson, Phillip B.; Shearer, Peter M.; Haney, Matthew M.; Waite, Gregory P.; Moran, Seth C.; Mikesell, T. Dylan

    2015-01-01

    Long-period (LP, 0.5-5 Hz) seismicity, observed at volcanoes worldwide, is a recognized signature of unrest and eruption. Cyclic LP “drumbeating” was the characteristic seismicity accompanying the sustained dome-building phase of the 2004–2008 eruption of Mount St. Helens (MSH), WA. However, together with the LP drumbeating was a near-continuous, randomly occurring series of tiny LP seismic events (LP “subevents”), which may hold important additional information on the mechanism of seismogenesis at restless volcanoes. We employ template matching, phase-weighted stacking, and full-waveform inversion to image the source mechanism of one multiplet of these LP subevents at MSH in July 2005. The signal-to-noise ratios of the individual events are too low to produce reliable waveform-inversion results, but the events are repetitive and can be stacked. We apply network-based template matching to 8 days of continuous velocity waveform data from 29 June to 7 July 2005 using a master event to detect 822 network triggers. We stack waveforms for 359 high-quality triggers at each station and component, using a combination of linear and phase-weighted stacking to produce clean stacks for use in waveform inversion. The derived source mechanism pointsto the volumetric oscillation (~10 m3) of a subhorizontal crack located at shallow depth (~30 m) in an area to the south of Crater Glacier in the southern portion of the breached MSH crater. A possible excitation mechanism is the sudden condensation of metastable steam from a shallow pressurized hydrothermal system as it encounters cool meteoric water in the outer parts of the edifice, perhaps supplied from snow melt.

  7. Source mechanism of small long-period events at Mount St. Helens in July 2005 using template matching, phase-weighted stacking, and full-waveform inversion

    NASA Astrophysics Data System (ADS)

    Matoza, Robin S.; Chouet, Bernard A.; Dawson, Phillip B.; Shearer, Peter M.; Haney, Matthew M.; Waite, Gregory P.; Moran, Seth C.; Mikesell, T. Dylan

    2015-09-01

    Long-period (LP, 0.5-5 Hz) seismicity, observed at volcanoes worldwide, is a recognized signature of unrest and eruption. Cyclic LP "drumbeating" was the characteristic seismicity accompanying the sustained dome-building phase of the 2004-2008 eruption of Mount St. Helens (MSH), WA. However, together with the LP drumbeating was a near-continuous, randomly occurring series of tiny LP seismic events (LP "subevents"), which may hold important additional information on the mechanism of seismogenesis at restless volcanoes. We employ template matching, phase-weighted stacking, and full-waveform inversion to image the source mechanism of one multiplet of these LP subevents at MSH in July 2005. The signal-to-noise ratios of the individual events are too low to produce reliable waveform inversion results, but the events are repetitive and can be stacked. We apply network-based template matching to 8 days of continuous velocity waveform data from 29 June to 7 July 2005 using a master event to detect 822 network triggers. We stack waveforms for 359 high-quality triggers at each station and component, using a combination of linear and phase-weighted stacking to produce clean stacks for use in waveform inversion. The derived source mechanism points to the volumetric oscillation (˜10 m3) of a subhorizontal crack located at shallow depth (˜30 m) in an area to the south of Crater Glacier in the southern portion of the breached MSH crater. A possible excitation mechanism is the sudden condensation of metastable steam from a shallow pressurized hydrothermal system as it encounters cool meteoric water in the outer parts of the edifice, perhaps supplied from snow melt.

  8. Plasma-wave observations at Uranus from Voyager 2. Progress report for period ending February 1986

    SciTech Connect

    Gurnett, D.A.; Kurth, W.S.; Scarf, F.L.; Poynter, R.L.

    1986-03-26

    Radio emissions from Uranus were detected by the Voyager 2 plasma-wave instrument about 5 days before closest approach at frequencies of 31.1 and 56.2 khz. The bow shock was identified by an abrupt broadband burst of electrostatic turbulence about 10 hours before closest approach at a radial distance of 23.5 ru. Once inside of the magnetosphere, strong whistler mode hiss and chorus emissions were observed at radial distances less than about 8 R/sub u/, in the same region where the energetic-particle instruments detected intense fluxes of energetic electrons. A variety of other plasma waves, such as (f sub c) electron-cyclotron waves, were also observed in this same region. At the ring plane crossing, the plasma wave instrument detected a large number of impulsive events that are interpreted as impacts of micron-sized dust particles on the spacecraft. The maximum impact rate was about 20 to 30 impacts/sec, and the north-south thickness of the impact region was about 4000 km. This paper presents an overview of the principal results from the plasma-wave instrument, starting with the first detection of radio emissions from Uranus, and ending a few days after closest approach.

  9. STEREO Observations of an SEP Event Injected Into Both Loop Legs of a Magnetic Cloud

    NASA Astrophysics Data System (ADS)

    Dresing, N.; Gomez-Herrero, R.; Heber, B.; Hidalgo, M. A. U.; Klassen, A.; Temmer, M.; Veronig, A.

    2015-12-01

    On 7 Nov 2013 STEREO B was embedded in a magnetic-cloud (MC) like structure when an SEP event occurred reaching both STEREO spacecraft. The bi-drectional near relativistic electron distribution observed by STEREO B reveals such timing and relative intensity characteristics suggesting that the SEPs were injected separately into both loop legs of the MC. Observations by the Nancay Radioheliograph (NRH) of two distinct radio sources at the same time further support the above scenario. In order to derive the 3D morphology and average speed of the CME close to the Sun, we use the graduated cylindrical shell model (GCS) which is applied to the white-light coronagraph observations by the STEREO spacecraft and SOHO. Furthermore, a global magnetic topology model for magnetic clouds is applied to the in-situ measurements of the magnetic field. Both models suggest that the MC is strongly inclined with respect to the ecliptic yielding a north/south orientation. The energetic electron observations are used to probe the structure of the magnetic cloud: We determine the electron path lengths along both loop legs of the structure to infer the amount of field line twist inside the MC. The resulting path lengths are around 50% longer than the estimated lengths of the loop legs of the MC itself suggesting that the amount of field line winding is moderate.

  10. Magnetic Upflow Events in the Quiet-Sun Photosphere. I. Observations

    NASA Astrophysics Data System (ADS)

    Jafarzadeh, S.; Rouppe van der Voort, L.; de la Cruz Rodríguez, J.

    2015-09-01

    Rapid magnetic upflows in the quiet-Sun photosphere were recently uncovered from both Sunrise/IMaX and Hinode/SOT observations. Here, we study magnetic upflow events (MUEs) from high-quality, high- (spatial, temporal, and spectral) resolution, and full Stokes observations in four photospheric magnetically sensitive Fe i lines centered at 5250.21, 6173.34, 6301.51, and 6302.50 Å acquired with the Swedish Solar Telescope (SST)/CRISP. We detect MUEs by subtracting in-line Stokes V signals from those in the far blue wing whose signal-to-noise ratio (S/N) ≥slant 7. We find a larger number of MUEs at any given time (2.0× {10}-2 arcsec-2), larger by one to two orders of magnitude, than previously reported. The MUEs appear to fall into four classes presenting different shapes of Stokes V profiles with (I) asymmetric double lobes, (II) single lobes, (III) double-humped (two same-polarity lobes), and (IV) three lobes (an extra blueshifted bump in addition to double lobes), of which less than half are single-lobed. We also find that MUEs are almost equally distributed in network and internetwork areas and they appear in the interior or at the edge of granules in both regions. Distributions of physical properties, except for horizontal velocity, of the MUEs (namely, Stokes V signal, size, line-of-sight velocity, and lifetime) are almost identical for the different spectral lines in our data. A bisector analysis of our spectrally resolved observations shows that these events host modest upflows and do not show a direct indication of the presence of supersonic upflows reported earlier. Our findings reveal that the numbers, types (classes), and properties determined for MUEs can strongly depend on the detection techniques used and the properties of the employed data, namely, S/Ns, resolutions, and wavelengths.

  11. Experimental studies in natural groundwater-recharge dynamics: The analysis of observed recharge events

    USGS Publications Warehouse

    Sophocleous, M.; Perry, C.A.

    1985-01-01

    The amounts and time distribution of groundwater recharge from precipitation over an approximately 19-month period were investigated at two instrumented sites in south-central Kansas. Precipitation and evapotranspiration sequences, soil-moisture profiles and storage changes, water fluxes in the unsaturated zone and hydraulic gradients in the saturated zone at various depths, soil temperatures, water-table hydrographs, and water-level changes in nearby wells clearly depict the recharge process. Antecedent moisture conditions and the thickness and nature of the unsaturated zone were found to be the major factors affecting recharge. Although the two instrumented sites are located in sand-dune environments in areas characterized by shallow water table and subhumid continental climate, a significant difference was observed in the estimated effective recharge. The estimates ranged from less than 2.5 to approximately 154 mm at the two sites from February to June 1983. The main reasons for this large difference in recharge estimates were the greater thickness of the unsaturated zone and the lower moisture content in that zone resulting from lower precipitation and higher potential evapotranspiration for one of the sites. Effective recharge took place only during late winter and spring. No summer or fall recharge was observed at either site during the observation period of this study. ?? 1985.

  12. Stochastic generation of flood events to extend observed hydrological series by combining a copula model with hydrometeorological modelling

    NASA Astrophysics Data System (ADS)

    Requena, Ana; Flores, Isabel; Mediero, Luis; Garrote, Luis

    2013-04-01

    A multivariate flood frequency analysis is required for designing some structures like dams. Multivariate copula models are usually used to obtain joint return periods of the flood variables. There exist several families of copulas and a selection procedure is required to find the copula that best fits the observations. Moreover, observed hydrological series are usually short and the fit of the right tail of the copula remains highly uncertain. In this work, a procedure to extend short observed series is proposed by the use of both hydrometeorological modelling and a copula model to generate synthetic hydrographs. The procedure takes synthetic rainstorms events generated by the RainSim software as input. The RIBS rainfall-runoff model is used to simulate the hydrological processes in the basin. The procedure was tested in the Santillana reservoir in Spain, were both RainSim and RIBS models were calibrated prior to this study. A sensitivity analysis was conducted in order to find the minimum synthetic length that makes the copula selection process robust enough. As computational time of hydrometeorological modelling is not negligible, the extended record from modelling results could be re-extended by the fitted copula, reducing the computation time. This final extended hydrological series can be used to improve flood risk assessment studies. Key words: Stochastic generation, copulas, rainfall-runoff modelling Session: HS7.15 - Hydroclimatic stochastics Convener: S. Grimaldi Co-Conveners: A. A. Carsteanu, D. Koutsoyiannis, X. L. Wang and S. M. Papalexiou

  13. Bringing Order to Life Events: Memory for the Temporal Order of Autobiographical Events over an Extended Period in School-Aged Children and Adults

    ERIC Educational Resources Information Center

    Pathman, Thanujeni; Doydum, Ayzit; Bauer, Patricia J.

    2013-01-01

    Remembering temporal information associated with personal past events is critical. Yet little is known about the development of temporal order memory for naturally occurring events. In the current research, 8- to 10-year-old children and adults took photographs daily for 4 weeks. Later, they participated in a primacy/recency task (were shown 2 of…

  14. A mesoscale gravity wave event observed during CCOPE. I - Multiscale statistical analysis of wave characteristics

    NASA Technical Reports Server (NTRS)

    Koch, Steven E.; Golus, Robert E.

    1988-01-01

    This paper presents a statistical analysis of the characteristics of the wavelike activity that occurred over the north-central United States on July 11-12, 1981, using data from the Cooperative Convective Precipitation Experiment in Montana. In particular, two distinct wave episodes of about 8-h duration within a longer (33 h) period of wave activity were studied in detail. It is demonstrated that the observed phenomena display features consistent with those of mesoscale gravity waves. The principles of statistical methods used to detect and track mesoscale gravity waves are discussed together with their limitations.

  15. Periodic behaviors in the observed vertical column abundances of atmospheric hydroxyl

    NASA Technical Reports Server (NTRS)

    Burnett, Elizabeth Beaver; Burnett, Clyde R.; Minschwaner, Kenneth R.

    1989-01-01

    The data base for the vertical column abundance of atmospheric hydroxyl (OH) for Fritz Peak Observatory, Colorado (40 N, 105 W), now extends from 1976 through 1988 and is composed of 8849 independent data sets, averaging about 15 percent uncertainty and 20-minute time resolution each. The dominant solar zenith angle (chi) dependence of the OH abundance is characterized by an empirical curve, N(88), which has been updated from N(82) to include all valid data from 1980 through 1988. The chi-dependence of the OH abundance has been, to a first order, removed from the data base by a normalization procedure in which each data point is divided by the N(88,AM) value for the corresponding solar zenith angle. The resulting normalized OH values may then be examined for other systematic effects, particularly for periodic variations. Observations have also been made at Boca Raton, Florida (26 N, 80 W) and at Truk, Federated States of Micronesia (7 N, 152 E). These data bases are much less extensive and, as such, are less amenable to analysis for periodic behaviors. Some comparisons with the Colorado data may be made, however.

  16. An overview of an intensive observation period on variability of coastal atmospheric refractivity

    NASA Astrophysics Data System (ADS)

    Paulus, Richard A.

    1995-02-01

    This paper is an overview of an experiment called Variability of Coastal Atmospheric Refractivity (VOCAR). VOCAR was designed to be conducted under a larger program called Coastal Variability Analysis, Measurements, and Prediction and is a multi-year experimental effort to investigate the variability of atmospheric refractivity with emphasis on the coastal zone. The experiment is being conducted jointly with the Naval Air Warfare Center Weapons Division, Point Mugu, CA, the Naval Research Laboratory, and the Naval Postgraduate School. In addition, the National Oceanic and Atmospheric Administration Environmental Technology Laboratory and Penn State University/Applied Research Laboratory are participating in the measurement phase of VOCAR. The propagation measurements being made during VOCAR consist of monitoring signal strength variations of VHF/UHF transmitters in the southern California coastal region. Corresponding meteorological measurements are made during routine, special, and intensive observation periods. During an intensive measurement period from 23 August to 3 September 1993, radio data were collected at two receiver sites and meteorological data were collected from three profiler sites, eight radiosonde sites, three aircraft, and numerous surface weather sites. Samples of the data will be shown.

  17. "Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period"

    SciTech Connect

    J. J. Michalsky, G. P. Anderson, J. Barnard, J. Delamere, C. Gueymard, S. Kato, P. Kiedron, A. McComiskey, and P. Ricchiazzi

    2006-04-01

    The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large intensive observation period (IOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses on using the redundant aerosol and radiation measurements during this IOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear-sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar-zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled and measured direct irradiances are less than 1%, and biases between modeled and measured diffuse irradiances are less than 2%.

  18. Observations of a new class of upstream waves with periods near 3 seconds

    NASA Technical Reports Server (NTRS)

    Le, G.; Russell, C. T.; Thomsen, M. F.; Gosling, J. T.

    1992-01-01

    A new class of ULF waves with periods near 3 s in the earth's upstream region is found by examining the high time resolution magnetic field data from the ISEE spacecraft. These waves are observed in the part of the upstream region which is magnetically connected to the bow shock, but only when the solar wind plasma beta is high (greater than 1). The waves are always right-handed, nearly circularly polarized in the spacecraft frame. The directions of the wave vectors are in the general direction of the average magnetic field, and the waves are convected downstream in the spacecraft frame. This study of these waves has shown that they appear to be intrinsically left-handed ion cyclotron waves in the plasma rest frame.

  19. Equatorial planetary waves in the mesosphere observed by airglow periodic oscillations

    NASA Astrophysics Data System (ADS)

    Buriti, R. A.; Takahashi, H.; Lima, L. M.; Medeiros, A. F.

    Planetary scale waves in the equatorial upper mesosphere were studied by measuring the airglow OI557.7 nm, O 2b(0,1) and OH(6,2) emission intensities and OH rotational temperature at São João do Cariri (7.4°S; 36.5°W). From four years of data, 1998-2001, periodic oscillations of the airglow emissions were analyzed using the Lomb-Scargle spectral analysis. An oscillation of 3-4 days was frequently observed, which might be ultra-fast Kelvin waves. No seasonal dependency of the wave activity was found. On some occasions we found a quasi-5-day oscillation with a phase difference between the emissions, suggesting an upward energy flow. This is interpreted as a normal mode Rossby wave.

  20. Observation of stimulated emission in an ultrashort-period nonsymmetric GaAs/AlAs superlattice

    SciTech Connect

    Litovchenko, V. G.; Korbutyak, D. V.; Bercha, A. I.; Kryuchenko, Yu. V.; Krylyuk, S. G.; Grahn, H. T.; Hey, R.; Ploog, K. H.

    2001-06-25

    Nonsymmetric short-period GaAs/AlAs superlattices, for which the well thickness is at least a factor of 2 larger than the barrier thickness, have been shown to exhibit a direct band gap for any well thickness. These superlattices are characterized by an enhanced intensity of the luminescence as compared to their symmetric indirect-gap counterparts with the same well width, and, thus, may be used as light-emitting devices, in particular, as low-threshold lasers in the red visible spectrum. This conjecture is supported by the observation of stimulated emission at T=80K for a GaAs/AlAs superlattice with six monolayers well and three monolayers barrier width. {copyright} 2001 American Institute of Physics.

  1. Observation of Exchange Anisotropy in Single-Phase Layer-Structured Oxides with Long Periods

    PubMed Central

    Huang, Yan; Wang, Guopeng; Sun, Shujie; Wang, Jianlin; Peng, Ranran; Lin, Yue; Zhai, Xiaofang; Fu, Zhengping; Lu, Yalin

    2015-01-01

    A remarkable exchange bias effect arising from the temperature-dependent interaction among the ferromagnetic-like cluster glasses and antiferromagnetic regions was observed in a newly developed single-phase multiferroic compound of Bi10Fe6Ti3O30 which has a nine-layer Aurivillius structure. Inhomogeneous distribution of magnetic Fe ions inside this long-period layered structure was experimentally identified via the atomic level imaging. The results confirmed the presence of the short-range magnetic ordering (the cluster glassy state) and the canted antiferromagnetism, and then the direct interaction among them was further confirmed. Finding of this new single-phase material accompanying this remarkable exchange bias effect would be beneficial to both basic physics understanding and the potential device development. PMID:26487509

  2. OBSERVATIONAL EVIDENCE ON THE PRESENCE OF AN OUTER REFLECTING BOUNDARY IN SOLAR ENERGETIC PARTICLE EVENTS

    SciTech Connect

    Tan, Lun C.; Reames, Donald V.; Ng, Chee K.; Saloniemi, Oskari; Wang Linghua

    2009-08-20

    We have focused primarily on the 2001 September 24 solar energetic particle (SEP) event to verify previous indications of the presence of an outer reflecting boundary of SEPs. By using energetic electron and ion data obtained from multi-spacecraft observations, we have identified a collimated particle beam consisting of reflected particles returning from an outer boundary. The peak of reflected particles appears before the arrival of particles at 90 deg. pitch angle. In addition, an onset time analysis is carried out in order to determine parameters characterizing the boundary. Our analysis suggests that the presence of a counter-streaming particle beam with a deep depression at {approx}90 deg. pitch angle during the onset phase is evidence for a nearby reflecting boundary. We have compared this property in the SEP events of 2002 April 21 and August 24. A reflecting boundary that blocks a flux tube is important in space weather forecasting since it can cause the 'reservoir' effect that may enhance the intensity and duration of high-energy particles.

  3. Discovery of an Outflow from Radio Observations of the Tidal Disruption Event ASASSN-14li

    NASA Astrophysics Data System (ADS)

    Alexander, K. D.; Berger, E.; Guillochon, J.; Zauderer, B. A.; Williams, P. K. G.

    2016-03-01

    We report the discovery of transient radio emission from the nearby optically discovered tidal disruption event (TDE) ASASSN-14li (distance of 90 Mpc), making it the first typical TDE detected in the radio, and unambiguously pointing to the formation of a non-relativistic outflow with a kinetic energy of ≈(4-10) × 1047 erg, a velocity of ≈12,000-36,000 km s-1, and a mass of ≈3 × 10-5-7 × 10-4 M⊙. We show that the outflow was ejected on 2014 August 11-25, in agreement with an independent estimate of the timing of super-Eddington accretion based on the optical, ultraviolet, and X-ray observations, and that the ejected mass corresponds to about 1%-10% of the mass accreted in the super-Eddington phase. The temporal evolution of the radio emission also uncovers the circumnuclear density profile, ρ (R)\\propto {R}-2.5 on a scale of about 0.01 pc, a scale that cannot be probed via direct measurements even in the nearest supermassive black holes. Our discovery of radio emission from the nearest well-studied TDE to date, with a radio luminosity lower than all previous limits, indicates that non-relativistic outflows are ubiquitous in TDEs, and that future, more sensitive, radio surveys will uncover similar events.

  4. Connecting Macroscopic Observables and Microscopic Assembly Events in Amyloid Formation Using Coarse Grained Simulations

    PubMed Central

    Bieler, Noah S.; Knowles, Tuomas P. J.; Frenkel, Daan; Vácha, Robert

    2012-01-01

    The pre-fibrillar stages of amyloid formation have been implicated in cellular toxicity, but have proved to be challenging to study directly in experiments and simulations. Rational strategies to suppress the formation of toxic amyloid oligomers require a better understanding of the mechanisms by which they are generated. We report Dynamical Monte Carlo simulations that allow us to study the early stages of amyloid formation. We use a generic, coarse-grained model of an amyloidogenic peptide that has two internal states: the first one representing the soluble random coil structure and the second one the -sheet conformation. We find that this system exhibits a propensity towards fibrillar self-assembly following the formation of a critical nucleus. Our calculations establish connections between the early nucleation events and the kinetic information available in the later stages of the aggregation process that are commonly probed in experiments. We analyze the kinetic behaviour in our simulations within the framework of the theory of classical nucleated polymerisation, and are able to connect the structural events at the early stages in amyloid growth with the resulting macroscopic observables such as the effective nucleus size. Furthermore, the free-energy landscapes that emerge from these simulations allow us to identify pertinent properties of the monomeric state that could be targeted to suppress oligomer formation. PMID:23071427

  5. Observing a fictitious stressful event: haematological changes, including circulating leukocyte activation.

    PubMed

    Mian, Rubina; Shelton-Rayner, Graham; Harkin, Brendan; Williams, Paul

    2003-03-01

    The aim of this study was to assess the effect of watching a psychological stressful event on the activation of leukocytes in healthy human volunteers. Blood samples were obtained from 32 healthy male and female subjects aged between 20 and 26 years before, during and after either watching an 83-minute horror film that none of the subjects had previously seen (The Texas Chainsaw Massacre, 1974) or by sitting quietly in a room (control group). Total differential cell counts, leukocyte activation as measured by the nitroblue tetrazolium (NBT) test, heart rate and blood pressure (BP) measurements were taken at defined time points. There were significant increases in peripheral circulating leukocytes, the number of activated circulating leukocytes, haemoglobin (Hb) concentration and haematocrit (Hct) in response to the stressor. These were accompanied by significant increases in heart rate, systolic and diastolic BP (P<0.05 from baseline). This is the first reported study on the effects of observing a psychologically stressful, albeit fictitious event on circulating leukocyte numbers and the state of leukocyte activation as determined by the nitrotetrazolium test. PMID:12637206

  6. Intermittent turbulence events observed with a sonic anemometer and minisodar during CASES99.

    SciTech Connect

    Coulter, R. L.; Doran, J. C.

    2000-05-12

    The Cooperative Air Surface Exchange Study 1999 (CASES99), designed to investigate in detail the nocturnal boundary layer (NBL) of the atmosphere with particular emphasis on turbulence and turbulence events, took place during October 1999, within the Atmospheric Boundary Layer Experiments (ABLE) region east of Wichita KS. The principal measurement site was a heavily instrumented 2-km square located near Leon (LE), KS, but additional sites at Smileyberg (SM) and Beaumont (BE) were also used. The authors augmented the normal ABLE measurements at Beaumont (radar wind profiler, minisodar, 10-m meteorological tower, precipitation gauge) with a sonic anemometer mounted on the tower, 7 m above the surface. For this campaign, the minisodar data were saved in single-pulse mode with no averaging. The Beaumont site is within gently rolling rangeland used primarily for grazing. The site is on a flat plain rising gradually to the east.The Flint Hills escarpment, located approximately 2 km to the east, marks the highest point in, and the eastern boundary of, the Walnut River watershed. Although most terrain features are subtle, terrain effects on atmospheric flows are still possible, particularly in stable conditions. The intent was to observe turbulence and, hopefully, turbulence events with the sonic anemometer and minisodar. The horizontal extent of these occurrences can be studied by including the Beaumont data with those obtained at the Leon site. In this report the authors are concerned with the occurrence of intermittent turbulence.

  7. A climatology of dust emission events from northern Africa using long-term surface observations