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Sample records for equatorial storm time

  1. Contribution of storm time substorms to the prompt electric field disturbances in the equatorial ionosphere

    International Nuclear Information System (INIS)

    Hui, Debrup; Chakrabarty, D.; Sekar, R.; Reeves, G. D.

    2017-01-01

    This study tries to bring out the fact that storm time substorms can compete and at times significantly contribute to the geomagnetically disturbed time prompt penetration electric field effects on low and equatorial latitudes. Observations of unusual equatorial plasma drift data from Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere during two space weather events show that substorms can induce both eastward and westward penetration electric fields under steady southward interplanetary magnetic field (IMF B z ) conditions. During the first event on 2 January 2005, the enhancement of the daytime eastward electric field over Jicamarca due to substorm is found to be comparable with the Sq and interplanetary electric field (IEFy) generated electric fields combined. During the second event on 19 August 2006, the substorm is seen to weaken the daytime eastward field thereby inducing a westward field in spite of the absence of northward turning of IMF B z (overshielding). The westward electric field perturbation in the absence of any overshielding events is observationally sparse and contrary to the earlier results. Further, the substorm-induced field is found to be strong enough to compete or almost nullify the effects of storm time IEFy fields. This study also shows quantitatively that at times substorm contribution to the disturbed time prompt electric fields can be significant and thus should be taken into consideration in evaluating penetration events over low latitudes.

  2. Occurrence of Equatorial Plasma Bubbles during Intense Magnetic Storms

    Directory of Open Access Journals (Sweden)

    Chao-Song Huang

    2011-01-01

    Full Text Available An important issue in low-latitude ionospheric space weather is how magnetic storms affect the generation of equatorial plasma bubbles. In this study, we present the measurements of the ion density and velocity in the evening equatorial ionosphere by the Defense Meteorological Satellite Program (DMSP satellites during 22 intense magnetic storms. The DMSP measurements show that deep ion density depletions (plasma bubbles are generated after the interplanetary magnetic field (IMF turns southward. The time delay between the IMF southward turning and the first DMSP detection of plasma depletions decreases with the minimum value of the IMF Bz, the maximum value of the interplanetary electric field (IEF Ey, and the magnitude of the Dst index. The results of this study provide strong evidence that penetration electric field associated with southward IMF during the main phase of magnetic storms increases the generation of equatorial plasma bubbles in the evening sector.

  3. Geomagnetic storms and electric fields in the equatorial ionosphere

    International Nuclear Information System (INIS)

    Rastogi, R.G.

    1977-01-01

    Using direct measurements of equatorial electric field during a geomagnetic storm it is shown that the large decrease in the field observed near the dip equator is due to the reversal of the equatorial electrojet current. This is caused by the imposition of an additional westward electric field on the equatorial ionosphere which was originated by the interaction of solar wind with the interplanetary magnetic field. (author)

  4. Increases of equatorial total electron content (TEC) during magnetic storms

    International Nuclear Information System (INIS)

    Yeboah-Amankwah, D.

    1976-01-01

    This paper is a report on the analysis of equatorial electron content, TEC, during magnetic storms. Storms between 1969 and 1972 have been examined as part of an on-going study of TEC morphology during magnetically disturbed days. The published magnetic Ksup(p) indices and TEC data from the Legon abservatory have been employed. The general picture arising from the analysis is that the total electron content of the ionosphere is significantly enhanced during magnetic storms. (author)

  5. Equatorial ionospheric electric fields during the November 2004 magnetic storm

    OpenAIRE

    Fejer, Bela G.; Jensen, J. W.; Kikuchi, T.; Abdu, M. A.; Chau, J. L.

    2007-01-01

    [1] We use radar measurements from the Jicamarca Radio Observatory, magnetometer observations from the Pacific sector and ionosonde data from Brazil to study equatorial ionospheric electric fields during the November 2004 geomagnetic storm. Our data show very large eastward and westward daytime electrojet current perturbations with lifetimes of about an hour (indicative of undershielding and overshielding prompt penetration electric fields) in the Pacific equatorial region during the November...

  6. Time dependent response of equatorial ionospheric electric fieldsto magnetospheric disturbances

    OpenAIRE

    Fejer, Bela G.; Scherliess, L.

    1995-01-01

    We use extensive radar measurements of F region vertical plasma drifts and auroral electrojet indices to determine the storm time dependence of equatorial zonal electric fields. These disturbance drifts result from the prompt penetration of high latitude electric fields and from the dynamo action of storm time winds which produce largest perturbations a few hours after the onset of magnetic activity. The signatures of the equatorial disturbance electric fields change significantly depending o...

  7. Multi-technique investigations of storm-time ionospheric irregularities over the São Luís equatorial station in Brazil

    Directory of Open Access Journals (Sweden)

    E. R. de Paula

    2004-11-01

    Full Text Available On 11 April 2001, a large magnetic storm occurred with SSC at 13:43 UT, and Dst reached below -200nT after two southward Bz excursions. The Kp index during this storm reached 8 and remained high (>4 for about 21h, and the São Luís magnetometer H component presented simultaneous oscillations and decreased substantially relative to the previous magnetically quiet days. This storm triggered strong ionospheric irregularities, as observed by a recently installed 30MHz coherent scatter radar, a digisonde, and a GPS scintillation receiver, all operating at the São Luís equatorial station (2.33° S, 44° W, dip latitude 1.3° S. The ionospheric conditions and the characteristics of the ionospheric irregularities observed by these instruments are presented and discussed. The VHF radar RTI (Range Time Intensity echoes and their power spectra and spectral width for the storm night 11-12 April 2001, were used to analyse the nature and dynamics of the plasma irregularities and revealed the coexistence of many structures in the altitudinal range of 400-1200km, some locally generated and others that drifted from other longitudinal sectors. The radar data also revealed that the plumes had periodic eastward and westward zonal velocities after 22:20 UT, when well-developed quiet-time plumes typically drift eastward. Another interesting new observation is that the F-layer remained anomalously high throughout the 11-12 April 2001 storm night (21:00 UT to 09:00 UT next day (the LT at São Luís is UT -3h, as indicated by the digisonde parameters hmF2 and h'F, which is a condition favourable for spread F generation and maintenance. The AE auroral index showed enhancements (followed by decreases that are indicative of magnetospheric convection enhancements at about 15:00 UT, 20:00 UT and 22:00 UT on 11 April 2001 and at 00:20 UT (small amplitude on 12 April 2001, associated with many Bz fluctuations, including clear two southward incursions that gave rise

  8. Multi-technique investigations of storm-time ionospheric irregularities over the São Luís equatorial station in Brazil

    Directory of Open Access Journals (Sweden)

    E. R. de Paula

    2004-11-01

    Full Text Available On 11 April 2001, a large magnetic storm occurred with SSC at 13:43 UT, and Dst reached below -200nT after two southward Bz excursions. The Kp index during this storm reached 8 and remained high (>4 for about 21h, and the São Luís magnetometer H component presented simultaneous oscillations and decreased substantially relative to the previous magnetically quiet days. This storm triggered strong ionospheric irregularities, as observed by a recently installed 30MHz coherent scatter radar, a digisonde, and a GPS scintillation receiver, all operating at the São Luís equatorial station (2.33° S, 44° W, dip latitude 1.3° S. The ionospheric conditions and the characteristics of the ionospheric irregularities observed by these instruments are presented and discussed. The VHF radar RTI (Range Time Intensity echoes and their power spectra and spectral width for the storm night 11-12 April 2001, were used to analyse the nature and dynamics of the plasma irregularities and revealed the coexistence of many structures in the altitudinal range of 400-1200km, some locally generated and others that drifted from other longitudinal sectors. The radar data also revealed that the plumes had periodic eastward and westward zonal velocities after 22:20 UT, when well-developed quiet-time plumes typically drift eastward. Another interesting new observation is that the F-layer remained anomalously high throughout the 11-12 April 2001 storm night (21:00 UT to 09:00 UT next day (the LT at São Luís is UT -3h, as indicated by the digisonde parameters hmF2 and h'F, which is a condition favourable for spread F generation and maintenance. The AE auroral index showed enhancements (followed by decreases that are indicative of magnetospheric convection enhancements at about 15:00 UT, 20:00 UT and 22:00 UT on 11 April 2001 and at 00:20 UT (small amplitude on 12 April 2001, associated with many

  9. The Southern Hemisphere and equatorial region ionization response for a 22 September 1999 severe magnetic storm

    Directory of Open Access Journals (Sweden)

    E. Yizengaw

    2004-09-01

    Full Text Available The ionospheric storm evolution process was monitored during the 22 September 1999 magnetic storm over the Australian eastern region, through measurements of the ionospheric Total Electron Content (TEC from seven Global Positioning Systems (GPS stations. The spatial and temporal variations of the ionosphere were analysed as a time series of TEC maps. Results of our analysis show that the main ionospheric effect of the storm under consideration are: the long lasting negative storm effect during a magnetic storm at mid-latitude regions; the strong, positive disturbances during the storm's main phase at auroral latitude regions; the effects of storm-induced equatorward directed wind causing a positive disturbance at high and mid-latitude stations with appropriate time shift between higher and lower latitudes; daytime poleward movement of depleted plasma that causes temporary suppression of the equatorial anomaly during the start of the storm recovery phase; and prompt penetration of eastward electric fields to ionospheric altitudes and the production of nearly simultaneous TEC enhancement at all latitudes. In general, we found dominant negative disturbance over mid and high latitudes and positive disturbance at low latitudes. A comparison of storm-time behaviour of TEC determined from GPS satellites, and foF2 derived from ionosondes at a range of latitudes, showed reasonable agreement between the two independent measurements.

  10. Effect of geomagnetic storm conditions on the equatorial ionization anomaly and equatorial temperature anomaly

    Science.gov (United States)

    Bharti, Gaurav; Bag, T.; Sunil Krishna, M. V.

    2018-03-01

    The effect of the geomagnetic storm on the equatorial ionization anomaly (EIA) and equatorial temperature anomaly (ETA) has been studied using the atomic oxygen dayglow emissions at 577.7 nm (OI 557.7 nm) and 732.0 nm (OII 732.0 nm). For the purpose of this study, four intense geomagnetic storms during the ascending phase of solar cycle 24 have been considered. This study is primarily based on the results obtained using photochemical models with necessary inputs from theoretical studies and experimental observations. The latest reaction rate coefficients, quantum yields and the corresponding cross-sections have also been incorporated in these models. The volume emission rate of airglow emissions has been calculated using the neutral densities from NRLMSISE-00 and charged densities from IRI-2012 model. The modeled volume emission rate (VER) for OI 557.7 nm shows a positive correlation with the Dst index at 150 km and negative correlation with Dst at 250 and 280 km altitudes. Latitudinal profile of the greenline emission rate at different altitudes show a distinct behaviour similar to what has been observed in EIA with crests on either sides of the equator. The EIA crests are found to show poleward movement in the higher altitude regions. The volume emission rate of 732.0 nm emission shows a strong enhancement during the main phase of the storm. The changes observed in the airglow emission rates are explained with the help of variations induced in neutral densities and parameters related to EIA and ETA. The latitudinal variation of 732.0 nm emission rate is correlated to the variability in EIA during the storm period.

  11. Equatorial storm sudden commencements and interplanetary magnetic field

    International Nuclear Information System (INIS)

    Rastogi, R.G.

    1980-01-01

    A comparison is made of the signatures of interplanetary (IP) shocks in the B and theta plots of interplanetary magnetic field (IMF) data of satellites Explorer 33, 34 and 35 and in the H magnetograms at ground observatories within the equatorial electrojet belt, Huancayo, Addis Ababa and Trivandrum associated with major storm sudden commencements during 1967-70. The IP shocks showing sudden increase of the scalar value of IMF, i.e. B without any change of the latitude theta or with the southward turning of theta, were followed by a purely positive sudden increase of H, at any of the magnetic observatories, either on the dayside or the nightside of the earth. The IP shocks identified by a sudden increase of B and with the northward turning of the latitude theta (positive ΔBsub(z)) were associated with purely positive sudden commencement (SC) at the observatories in the nightside, but at the equatorial observatories in the dayside of the earth the signature of the shock was a SC in H with a preliminary negative impulse followed by the main positive excursion (SC-+). It is suggested that the SCs in H at low latitudes are composed of two effects, viz. (i) one due to hydromagnetic pressure on the magnetosphere by the solar plasma and (ii) the other due to the induced electric field associated with the solar wind velocity, V and the Z-component of the IP magnetic field (E = - V x Bsub(z)). The effect of magnetosphere electric field is faster than the effect due to the compression of the magnetosphere by the impinging solar plasma. The negative impulse of SC-+ at low latitude is seen at stations close to the dip equator and only during daytime due to the existence of high ionospheric conductivities in the equatorial electrojet region. (author)

  12. Magnetic storm effect on the occurrence of ionospheric irregularities at an equatorial station in the African sector

    Directory of Open Access Journals (Sweden)

    Olushola Abel Oladipo

    2014-01-01

    Full Text Available Large-scale ionospheric irregularities usually measured by GPS TEC fluctuation indices are regular occurrence at the equatorial region shortly after sunset around solar maximum. Magnetic storm can trigger or inhibit the generation of these irregularities depending on the local time the main phase of a particular storm occurs. We studied the effect of nine (9 distinct storms on the occurrence of ionospheric irregularities at Fraceville in Gabon (Lat = −1.63˚, Long = 13.55˚, dip lat. = −15.94˚, an equatorial station in the African sector. These storms occurred between November 2001 and September 2002. We used TEC fluctuation indices (i.e. ROTI and ROTIAVE estimated from 30 s interval Rinex data and also we used the storm indices (i.e. Dst, dDst/dt, and IMF BZ to predict the likely effect of each storm on the irregularities occurrence at this station. The results obtained showed that most of the storms studied inhibited ionospheric irregularities. Only one out of all the storms studied (i.e. September 4, 2002 storms with the main phase on the night of September 7-8 triggered post-midnight ionospheric irregularities. There are two of the storms during which ionospheric irregularities were observed. However, these may not be solely attributed to the storms event because the level of irregularities observed during these two storms is comparable to that observed during previous days before the storms. For this station and for the storms investigated, it seems like a little modification to the use of Aarons categories in terms of the local time the maximum negative Dst occurs could lead to a better prediction. However, it would require investigating many storms during different level of solar activities and at different latitudes to generalize this modification.

  13. An Enduring Rapidly Moving Storm as a Guide to Saturn's Equatorial Jet's Complex Structure

    Science.gov (United States)

    Sanchez-Lavega, A.; Garcia-Melendo, E.; Perez-Hoyos, S.; Hueso, R.; Wong, M. H.; Simon, A.; Sanz-Requena, J. F.; Antunano, A.; Barrado-Izagirre, N.; Garate-Lopez, I.; hide

    2016-01-01

    Saturn has an intense and broad eastward equatorial jet with a complex three-dimensional structure mixed with time variability. The equatorial region experiences strong seasonal insolation variations enhanced by ring shadowing, and three of the six known giant planetary-scale storms have developed in it. These factors make Saturn's equator a natural laboratory to test models of jets in giant planets. Here we report on a bright equatorial atmospheric feature imaged in 2015 that moved steadily at a high speed of 450/ms not measured since 1980-1981 with other equatorial clouds moving within an ample range of velocities. Radiative transfer models show that these motions occur at three altitude levels within the upper haze and clouds. We find that the peak of the jet (latitudes 10degN to 10degS) suffers intense vertical shears reaching + 2.5/ms/km, two orders of magnitude higher than meridional shears, and temporal variability above 1 bar altitude level.

  14. Equatorial E Region Electric Fields and Sporadic E Layer Responses to the Recovery Phase of the November 2004 Geomagnetic Storm

    Science.gov (United States)

    Moro, J.; Resende, L. C. A.; Denardini, C. M.; Xu, J.; Batista, I. S.; Andrioli, V. F.; Carrasco, A. J.; Batista, P. P.; Schuch, N. J.

    2017-12-01

    Equatorial E region electric fields (EEFs) inferred from coherent radar data, sporadic-E (Es) layers observed from a digital ionosonde data, and modeling results are used to study the responses of the equatorial E region over São Luís (SLZ, 2.3°S, 44.2°W, -7° dip angle), Brazil, during the super storm of November 2004. The EEF is presented in terms of the zonal (Ey) and vertical (Ez) components in order to analyze the corresponding characteristics of different types of Es seen in ionograms and simulated with the E region ionospheric model. We bring out the variabilities of Ey and Ez components with storm time changes in the equatorial E region. In addition, some aspects of the electric fields and Es behavior in three cases of weak, very weak, and strong Type II occurrences during the recovery phase of the geomagnetic storm are discussed. The connection between the enhanced occurrence and suppressions of the Type II irregularities and the q-type Es (Esq) controlled by electric fields, with the development or disruption of the blanketing sporadic E (Esb) layers produced by wind shear mechanism, is also presented. The mutual presence of Esq along with the Esb occurrences is a clear indicator of the secular drift of the magnetic equator and hence that of the equatorial electrojet (EEJ) over SLZ. The results show evidence about the EEJ and Es layer electrodynamics and coupling during geomagnetic disturbance time electric fields.

  15. Ionospheric Storm Effects and Equatorial Plasma Irregularities During the 17-18 March 2015 Event

    Science.gov (United States)

    Zhou, Yun-Liang; Luhr, Hermann; Xiong, Chao; Pfaff, Robert F.

    2016-01-01

    The intense magnetic storm on 17-18 March 2015 caused large disturbances of the ionosphere. Based on the plasma density (Ni) observations performed by the Swarm fleet of satellites, the Gravity Recovery and Climate Experiment mission, and the Communications/Navigation Outage Forecasting System satellite, we characterize the storm-related perturbations at low latitudes. All these satellites sampled the ionosphere in morning and evening time sectors where large modifications occurred. Modifications of plasma density are closely related to changes of the solar wind merging electric field (E (sub m)). We consider two mechanisms, prompt penetration electric field (PPEF) and disturbance dynamo electric field (DDEF), as the main cause for the Ni redistribution, but effects of meridional wind are also taken into account. At the start of the storm main phase, the PPEF is enhancing plasma density on the dayside and reducing it on the nightside. Later, DDEF takes over and causes the opposite reaction. Unexpectedly, there appears during the recovery phase a strong density enhancement in the morning/pre-noon sector and a severe Ni reduction in the afternoon/evening sector, and we suggest a combined effect of vertical plasma drift, and meridional wind is responsible for these ionospheric storm effects. Different from earlier studies about this storm, we also investigate the influence of storm dynamics on the initiation of equatorial plasma irregularities (EPIs). Shortly after the start of the storm main phase, EPIs appear in the post-sunset sector. As a response to a short-lived decline of E (sub m), EPI activity appears in the early morning sector. Following the second start of the main phase, EPIs are generated for a few hours in the late evening sector. However, for the rest of the storm main phase, no more EPIs are initiated for more than 12 hours. Only after the onset of recovery phase does EPI activity start again in the post-midnight sector, lasting more than 7 hours

  16. Equatorial All Sky Imager Images from the Seychelles during the March 17th, 2015 geomagnetic storm.

    Science.gov (United States)

    Curtis, B.

    2015-12-01

    An all sky imager was installed in the Seychelles earlier this year. The Seychelles islands are located northeast of Madagascar and east of Somalia in the equatorial Indian Ocean. The all sky imager is located on the island of Mahe (4.6667°S, 55.4667°E geographic), (10.55°S, 127.07°E geomagnetic), with filters of 557.7, 620.0, 630.0, 765.0 and 777.4 nm. Images with a 90 second exposure from Seychelles in 777.4nm and 630.0nm from the night before and night of the March 17th geomagnetic storm are discussed in comparison to solar wind measurements at ACE and the disturbance storm time (Dst) index. These images show line-of-sight intensities of photons received dependent on each filters wavelength. A time series of these images sometimes will show the movement of relatively dark areas, or depletions, in each emission. The depletion regions are known to cause scintillation in GPS signals. The direction and speed of movement of these depletions are related to changes observed in the solar wind.

  17. CONVECTIVE BURSTS AND THE COUPLING OF SATURN'S EQUATORIAL STORMS AND INTERIOR ROTATION

    International Nuclear Information System (INIS)

    Heimpel, Moritz; Aurnou, Jonathan M.

    2012-01-01

    Temporal variations of Saturn's equatorial jet and magnetic field hint at rich dynamics coupling the atmosphere and the deep interior. However, it has been assumed that rotation of the interior dynamo must be steady over tens of years of modern observations. Here we use a numerical convection model and scaling estimates to show how equatorial convective bursts can transfer angular momentum to the deeper interior. The numerical model allows angular momentum transfer between a fluid outer spherical shell and a rigid inner sphere. Convection drives a prograde equatorial jet exhibiting quasiperiodic bursts that fill the equatorial volume outside the tangent cylinder. For each burst strong changes in the equatorial surface velocity are associated with retrograde torque on the inner sphere. Our results suggest that Saturn's Great White Spot, a giant storm that was observed to fill the equatorial region in 1990, could mobilize a volume of fluid carrying roughly 15% of Saturn's moment of inertia. Conservation of angular momentum then implies that a 20% change in the equatorial jet angular velocity could change the average interior rotation rate by about 0.1%—roughly an order of magnitude less than the apparent rotation rate changes associated with Saturn's kilometric radio (SKR) signal. However, if the SKR signal originates outside the liquid metal core in a 'planetary tachocline' that separates the layer of fast zonal flow from the magnetically controlled and slowly convecting deep interior, then convective bursts can provide a possible mechanism for the observed ∼1% SKR changes.

  18. The Equatorial Scintillations and Space Weather Effects on its Generation during Geomagnetic Storms

    Science.gov (United States)

    Biktash, Lilia

    Great diversity of the ionospheric phenomena leads to a variety of irregularity types with spatial size from many thousands of kilometers to few centimeters and lifetimes from days to fractions of second. Since the ionosphere strongly influences the propagation of radio waves, signal distortions caused by these irregularities affect short-wave transmissions on Earth, transiono-spheric satellite communications and navigation. In this work the solar wind and the equatorial ionosphere parameters, Kp, Dst, AU, AL indices characterized contribution of different mag-netospheric and ionospheric currents to the H-component of geomagnetic field are examined to test the space weather effect on the generation of ionospheric irregularities producing VLF scintillations. According to the results of the current statistical studies, one can predict scintil-lations from Aarons' criteria using the Dst index, which mainly depicts the magnetospheric ring current field. To amplify Aarons' criteria or to propose new criteria for predicting scintillation characteristics is the question. In the present phase of the experimental investigations of elec-tron density irregularities in the ionosphere new ways are opened up because observations in the interaction between the solar wind -magnetosphere -ionosphere during magnetic storms have progressed greatly. We have examined scintillation relation to magnetospheric and ionospheric currents and show that the factor, which presents during magnetic storms to fully inhibit scin-tillation, is the positive Bz-component of the IMF. During the positive Bz IMF F layer cannot raise altitude where scintillations are formed. The auroral indices and Kp do better for the prediction of the ionospheric scintillations at the equator. The interplanetary magnetic field data and models can be used to explain the relationship between the equatorial ionospheric parameters, h'F, foF2, and the equatorial geomagnetic variations with the polar ionosphere cur-rents and

  19. Geomagnetic storm effects on the occurrences of ionospheric irregularities over the African equatorial/low-latitude region

    Science.gov (United States)

    Amaechi, P. O.; Oyeyemi, E. O.; Akala, A. O.

    2018-04-01

    The study investigated the effects of intense geomagnetic storms of 2015 on the occurrences of large scale ionospheric irregularities over the African equatorial/low-latitude region. Four major/intense geomagnetic storms of 2015 were analyzed for this study. These storms occurred on 17th March 2015 (-229 nT), 22nd June 2015 (-204 nT), 7th October 2015 (-124 nT), and 20th December 2015 (-170 nT). Total Electron Content (TEC) data obtained from five African Global Navigation Satellite Systems (GNSS) stations, grouped into eastern and western sectors were used to derive the ionospheric irregularities proxy indices, e.g., rate of change of TEC (ROT), ROT index (ROTI) and ROTI daily average (ROTIAVE). These indices were characterized alongside with the disturbance storm time (Dst), the Y component of the Interplanetary Electric Field (IEFy), polar cap (PC) index and the H component of the Earth's magnetic field from ground-based magnetometers. Irregularities manifested in the form of fluctuations in TEC. Prompt penetration of electric field (PPEF) and disturbance dynamo electric field (DDEF) modulated the behaviour of irregularities during the main and recovery phases of the geomagnetic storms. The effect of electric field over both sectors depends on the local time of southward turning of IMF Bz. Consequently, westward electric field inhibited irregularities during the main phase of March and October 2015 geomagnetic storms, while for the June 2015 storm, eastward electric field triggered weak irregularities over the eastern sector. The effect of electric field on irregularities during December 2015 storm was insignificant. During the recovery phase of the storms, westward DDEF suppressed irregularities.

  20. On the Nocturnal Downward and Westward Equatorial Ionospheric Plasma Drifts During the 17 March 2015 Geomagnetic Storm

    Science.gov (United States)

    Bagiya, Mala S.; Vichare, Geeta; Sinha, A. K.; Sripathi, S.

    2018-02-01

    During quiet period, the nocturnal equatorial ionospheric plasma drifts eastward in the zonal direction and downward in the vertical direction. This quiet time drift pattern could be understood through dynamo processes in the nighttime equatorial ionosphere. The present case study reports the nocturnal simultaneous occurrence of the vertically downward and zonally westward plasma drifts over the Indian latitudes during the geomagnetic storm of 17 March 2015. After 17:00 UT ( 22:10 local time), the vertical plasma drift became downward and coincided with the westward zonal drift, a rarely observed feature of low latitude plasma drifts. The vertical drift turned upward after 18:00 UT, while the zonal drift became eastward. We mainly emphasize here the distinct bipolar type variations of vertical and zonal plasma drifts observed around 18:00 UT. We explain the vertical plasma drift in terms of the competing effects between the storm time prompt penetration and disturbance dynamo electric fields. Whereas, the westward drift is attributed to the storm time local electrodynamical changes mainly through the disturbance dynamo field in addition to the vertical Pedersen current arising from the spatial (longitudinal) gradient of the field aligned Pedersen conductivity.

  1. Disruption of Saturn's quasi-periodic equatorial oscillation by the great northern storm

    Science.gov (United States)

    Fletcher, Leigh N.; Guerlet, Sandrine; Orton, Glenn S.; Cosentino, Richard G.; Fouchet, Thierry; Irwin, Patrick G. J.; Li, Liming; Flasar, F. Michael; Gorius, Nicolas; Morales-Juberías, Raúl

    2017-11-01

    The equatorial middle atmospheres of the Earth1, Jupiter2 and Saturn3,4 all exhibit a remarkably similar phenomenon—a vertical, cyclic pattern of alternating temperatures and zonal (east-west) wind regimes that propagate slowly downwards with a well-defined multi-year period. Earth's quasi-biennial oscillation (QBO) (observed in the lower stratospheric winds with an average period of 28 months) is one of the most regular, repeatable cycles exhibited by our climate system1,5,6, and yet recent work has shown that this regularity can be disrupted by events occurring far away from the equatorial region, an example of a phenomenon known as atmospheric teleconnection7,8. Here, we reveal that Saturn's equatorial quasi-periodic oscillation (QPO) (with an 15-year period3,9) can also be dramatically perturbed. An intense springtime storm erupted at Saturn's northern mid-latitudes in December 201010-12, spawning a gigantic hot vortex in the stratosphere at 40° N that persisted for three years13. Far from the storm, the Cassini temperature measurements showed a dramatic 10 K cooling in the 0.5-5 mbar range across the entire equatorial region, disrupting the regular QPO pattern and significantly altering the middle-atmospheric wind structure, suggesting an injection of westward momentum into the equatorial wind system from waves generated by the northern storm. Hence, as on Earth, meteorological activity at mid-latitudes can have a profound effect on the regular atmospheric cycles in Saturn's tropics, demonstrating that waves can provide horizontal teleconnections between the phenomena shaping the middle atmospheres of giant planets.

  2. The postsunset vertical plasma drift during geomagnetic storms and its effects on the generation of equatorial spread F

    Science.gov (United States)

    Huang, C.

    2017-12-01

    We will present two distinct phenomena related to the postsunset vertical plasma drift and equatorial spread F (ESF) observed by the Communication/Navigation Outage Forecasting System satellite over six years. The first phenomenon is the behavior of the prereversal enhancement (PRE) of the vertical plasma drift during geomagnetic storms. Statistically, storm-time disturbance dynamo electric fields cause the PRE to decrease from 30 to 0 m/s when Dst changes from -60 to -100 nT, but the PRE does not show obvious variations when Dst varies from 0 to -60 nT. The observations show that the storm activities affect the evening equatorial ionosphere only for Dst correlated with the PRE and that the occurrence of small-amplitude ESF irregularities does not show a clear pattern at low solar activity but is anti-correlated with large-amplitude irregularities and the PRE at moderate solar activity. That is, the months and longitudes with high occurrence probability of large-amplitude irregularities are exactly those with low occurrence probability of small-amplitude irregularities, and vice versa. The generation of large-amplitude ESF irregularities is controlled by the PRE, and the generation of small-amplitude ESF irregularities may be caused by gravity waves and other disturbances, rather than by the PRE.

  3. The Southern Hemisphere and equatorial region ionization response for a 22 September 1999 severe magnetic storm

    OpenAIRE

    Yizengaw, Endawoke

    2004-01-01

    The ionospheric storm evolution process was monitored during the 22 September 1999 magnetic storm over the Australian eastern region, through measurements of the ionospheric Total Electron Content (TEC) from seven Global Positioning Systems (GPS) stations. The spatial and temporal variations of the ionosphere were analysed as a time series of TEC maps. Results of our analysis show that the main ionospheric effect of the storm under consideration are: the long lasting negative storm effect dur...

  4. Study of the Equatorial and Low-Latitude Electrodynamic and Ionospheric Disturbances During the 22-23 June 2015 Geomagnetic Storm Using Ground-Based and Spaceborne Techniques

    Science.gov (United States)

    Astafyeva, E.; Zakharenkova, I.; Hozumi, K.; Alken, P.; Coïsson, P.; Hairston, M. R.; Coley, W. R.

    2018-03-01

    We use a set of ground-based instruments (Global Positioning System receivers, ionosondes, magnetometers) along with data of multiple satellite missions (Swarm, C/NOFS, DMSP, GUVI) to analyze the equatorial and low-latitude electrodynamic and ionospheric disturbances caused by the geomagnetic storm of 22-23 June 2015, which is the second largest storm in the current solar cycle. Our results show that at the beginning of the storm, the equatorial electrojet (EEJ) and the equatorial zonal electric fields were largely impacted by the prompt penetration electric fields (PPEF). The PPEF were first directed eastward and caused significant ionospheric uplift and positive ionospheric storm on the dayside, and downward drift on the nightside. Furthermore, about 45 min after the storm commencement, the interplanetary magnetic field (IMF) Bz component turned northward, leading to the EEJ changing sign to westward, and to overall decrease of the vertical total electron content (VTEC) and electron density on the dayside. At the end of the main phase of the storm, and with the second long-term IMF Bz southward turn, we observed several oscillations of the EEJ, which led us to conclude that at this stage of the storm, the disturbance dynamo effect was already in effect, competing with the PPEF and reducing it. Our analysis showed no significant upward or downward plasma motion during this period of time; however, the electron density and the VTEC drastically increased on the dayside (over the Asian region). We show that this second positive storm was largely influenced by the disturbed thermospheric conditions.

  5. Storm-time slab thickness at low latitudes

    International Nuclear Information System (INIS)

    Chauhan, N.S.; Gurm, H.S.

    1981-01-01

    The ATS-6 data for a period of 1975-76 is used for the study of slab thickness during two moderate storms (Ksub(p) - ) around the crest of the anomaly, Ahmedabad and a very great (Ksub(p) + ) outside the equatorial anomaly region, Delhi. While at Ahmedabad, on the average, the slab thickness is found to be above the frequency. Comparison of slab thickness with foF2 and the equatorial magnetic record (for Ahmedabad only) shows that the foF2 changes alone cannot be held responsible for the slab thickness variation and thus entry of the plasma flux from the plasmasphere cannot be ruled out. The pressure variation effect of storm-time heating on the slab thickness at Ahmedabad is that even for Ksub(p)=8, the thermal expansion and the contraction effects are unable to explain complete quantitative and qualitative features of the observations

  6. Storm real-time processing cookbook

    CERN Document Server

    Anderson, Quinton

    2013-01-01

    A Cookbook with plenty of practical recipes for different uses of Storm.If you are a Java developer with basic knowledge of real-time processing and would like to learn Storm to process unbounded streams of data in real time, then this book is for you.

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

    Science.gov (United States)

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

    2017-12-01

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

  8. Sudden post-midnight decrease in equatorial F-region electron densities associated with severe magnetic storms

    Directory of Open Access Journals (Sweden)

    D. R. Lakshmi

    1997-03-01

    Full Text Available A detailed analysis of the responses of the equatorial ionosphere to a large number of severe magnetic storms shows the rapid and remarkable collapse of F-region ionisation during post-midnight hours; this is at variance with the presently accepted general behaviour of the low-latitude ionosphere during magnetic storms. This paper discusses such responses as seen in the ionosonde data at Kodaikanal (Geomagn. Lat. 0.6 N. It is also observed that during magnetic storm periods the usual increase seen in the h'F at Kodaikanal during sunset hours is considerably suppressed and these periods are also characterised by increased foF2 values. It is suggested that the primary process responsible for these dramatic pre- and post-midnight changes in foF2 during magnetic storms could be due to changes in the magnitude as well as in the direction of usual equatorial electric fields. During the post-midnight periods the change in electric-field direction from westward to eastward for a short period causes an upward E × B plasma drift resulting in increased h'F and decreased electron densities in the equatorial region. In addition, it is also suggested that the enhanced storm-induced meridional winds in the thermosphere, from the poles towards the equator, may also cause the decreases in electron density seen during post-midnight hours by spatially transporting the F-region ionisation southwards away from Kodaikanal. The paper also includes a discussion on the effects of such decreases in ionisation on low-latitude HF communications.

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

    OpenAIRE

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

    2005-01-01

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

  10. Storm-time meridional flows: a comparison of CINDI observations and model results

    Directory of Open Access Journals (Sweden)

    M. Hairston

    2014-06-01

    Full Text Available During a large geomagnetic storm, the electric field from the polar ionosphere can expand far enough to affect the mid-latitude and equatorial electric fields. These changes in the equatorial zonal electric field, called the penetration field, will cause changes in the meridional ion flows that can be observed by radars and spacecraft. In general this E × B ion flow near the equator caused by the penetration field during undershielding conditions will be upward on the dayside and downward on the nightside of the Earth. Previous analysis of the equatorial meridional flows observed by CINDI instrument on the C/NOFS spacecraft during the 26 September 2011 storm showed that all of the response flows on the dayside were excess downward flows instead of the expected upward flows. These observed storm-time responses are compared to a prediction from a physics-based coupled model of thermosphere–ionosphere–inner-magnetosphere in an effort to explain these observations. The model results suggest that the equatorial downward flow could be attributed to a combined effect of the overshielding and disturbance dynamo processes. However, some discrepancy between the model and observation indicates a need for improving our understanding of how sensitive the equatorial electric field is to various model input parameters that describe the magnetosphere–ionosphere coupling processes.

  11. Variability in the correlation between Asian dust storms and chlorophyll a concentration from the North to Equatorial Pacific.

    Directory of Open Access Journals (Sweden)

    Sai-Chun Tan

    Full Text Available A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997-2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the 50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32-0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (<0.36. These correlation coefficients were further interpreted in terms of the geographical distributions of dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas.

  12. Role of the magnetospheric and ionospheric currents in the generation of the equatorial scintillations during geomagnetic storms

    Directory of Open Access Journals (Sweden)

    L. Z. Biktash

    2004-09-01

    Full Text Available The equatorial ionosphere parameters, Kp, Dst, AU and AL indices characterized contribution of different magnetospheric and ionospheric currents to the H-component of geomagnetic field are examined to test the geomagnetic activity effect on the generation of ionospheric irregularities producing VLF scintillations. According to the results of the current statistical studies, one can predict near 70% of scintillations from Aarons' criteria using the Dst index, which mainly depicts the magnetospheric ring current field. To amplify Aarons' criteria or to propose new criteria for predicting scintillation characteristics is the question. In the present phase of the experimental investigations of electron density irregularities in the ionosphere new ways are opened up because observations in the interaction between the solar wind - magnetosphere - ionosphere during magnetic storms have progressed greatly. According to present view, the intensity of the electric fields and currents at the polar regions, as well as the magnetospheric ring current intensity, are strongly dependent on the variations of the interplanetary magnetic field. The magnetospheric ring current cannot directly penetrate the equatorial ionosphere and because of this difficulties emerge in explaining its relation to scintillation activity. On the other hand, the equatorial scintillations can be observed in the absence of the magnetospheric ring current. It is shown that in addition to Aarons' criteria for the prediction of the ionospheric scintillations, models can be used to explain the relationship between the equatorial ionospheric parameters, h'F, foF2, and the equatorial geomagnetic variations with the polar ionosphere currents and the solar wind.

  13. Equatorial density depletions observed at 840 km during the great magnetic storm of March 1989

    International Nuclear Information System (INIS)

    Greenspan, M.E.; Rasmussen, C.E.; Burke, W.J.; Abdu, M.A.

    1991-01-01

    Early on March 14, 1989, a thermal plasma probe on the Defense Meteorological Satellite Program (DMSP) F9 spacecraft detected extensive and dramatic decreases in the ion density at 840 km, near 2130 LT, during two consecutive transequatorial passes over South America. The order of magnitude decreases in the ion density extended more than 4,000 km along the satellite track. The depletions were accompanied by upward and westward plasma drifts, both in excess of 100 m/s. Their onsets and terminations were marked by extremely sharp density gradients. A partial depletion was detected over the eastern Pacific during the following orbit. The DMSP F9 ground track passed slightly west of a Brazilian total electron content (TEC) station and two Brazilian ionosondes during the first depletion encounter. The TEC fell far below normal during the night of March 13-14. The ionosonde measurements indicate that, in the hour after sunset, before DMSP passed through the depletions, the F 2 layer rose rapidly and disappeared, but at the time of the first depletion encounter, h m F 2 was decreasing over one of the stations. The authors develop a phenomenological model reconciling DMSP F8, F9 and ground-based measurements. The calculations show that rapid upward drifts sustained for several hours can produce depletions in the equatorial ion density with sharp gradients at their high-latitude boundaries, consistent with the data. They discuss possible contributing mechanisms for generating these upward drifts. These include direct penetration of the magnetospheric electric field to low latitudes, the electric fields generated by the disturbance dynamo, and the effects of conductivity gradients near the dusk terminator and the South Atlantic anomaly

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

    International Nuclear Information System (INIS)

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

    1987-01-01

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

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

    Directory of Open Access Journals (Sweden)

    P. Subrahmanyam

    2005-11-01

    Full Text Available Recently, there has been a renewal of interest in the study of the effects of solar weather events on the ionization redistribution and irregularity generation. The observed changes at low and equatorial latitudes are rather complex and are noted to be a function of location, the time of the storm onset and its intensity, and various other characteristics of the geomagnetic storms triggered by solar weather events. At these latitudes, the effects of geomagnetic storms are basically due to (a direct penetration of the magnetospheric electric fields to low latitudes, (b development of disturbance dynamo, (c changes in atmospheric neutral winds at ionospheric level and (d changes in neutral composition triggered by the storm time atmospheric heating.

    In the present study an attempt is made to further understand some of the observed storm time effects in terms of storm time changes in zonal electric fields and meridional neutral winds. For this purpose, observations made by the Retarding Potential Analyzer (RPA payload on board the Indian satellite SROSS-C2 are examined for four prominent geomagnetic storm events that occurred during the high solar activity period of 1997-2000. Available simultaneous observations, from the GPS satellite network, are also used. The daytime passes of SROSS-C2 have been selected to examine the redistribution of ionization in the equatorial ionization anomaly (EIA region. In general, EIA is observed to be weakened 12-24 h after the main phase onset (MPO of the storm. The storm time behaviour inferred by SROSS-C2 and the GPS satellite network during the geomagnetic storm of 13 November 1998, for which simultaneous observations are available, is found to be consistent. Storm time changes in the delay of received GPS signals are noted to be ~1-3 m, which is a significant component of the total delay observed on a quiet day.

    An attempt is made to identify and

  16. Response of equatorial, low- and mid-latitude F-region in the American sector during the intense geomagnetic storm on 24-25 October 2011

    Science.gov (United States)

    de Jesus, R.; Sahai, Y.; Fagundes, P. R.; de Abreu, A. J.; Brunini, C.; Gende, M.; Bittencourt, J. A.; Abalde, J. R.; Pillat, V. G.

    2013-07-01

    In this paper, we present and discuss the response of the ionospheric F-region in the American sector during the intense geomagnetic storm which occurred on 24-25 October 2011. In this investigation ionospheric sounding data obtained of 23, 24, 25, and 26 October 2011 at Puerto Rico (United States), Jicamarca (Peru), Palmas, São José dos Campos (Brazil), and Port Stanley, are presented. Also, the GPS observations obtained at 12 stations in the equatorial, low-, mid- and high-mid-latitude regions in the American sector are presented. During the fast decrease of Dst (about ˜54 nT/h between 23:00 and 01:00 UT) on the night of 24-25 October (main phase), there is a prompt penetration of electric field of magnetospheric origin resulting an unusual uplifting of the F region at equatorial stations. On the night of 24-25 October 2011 (recovery phase) equatorial, low- and mid-latitude stations show h'F variations much larger than the average variations possibly associated with traveling ionospheric disturbances (TIDs) caused by Joule heating at high latitudes. The foF2 variations at mid-latitude stations and the GPS-VTEC observations at mid- and low-latitude stations show a positive ionospheric storm on the night of 24-25 October, possibly due to changes in the large-scale wind circulation. The foF2 observations at mid-latitude station and the GPS-VTEC observations at mid- and high-mid-latitude stations show a negative ionospheric storm on the night of 24-25 October, probably associated with an increase in the density of molecular nitrogen. During the daytime on 25 October, the variations in foF2 at mid-latitude stations show large negative ionospheric storm, possibly due to changes in the O/N2 ratio. On the night of 24-25, ionospheric plasma bubbles (equatorial irregularities that extended to the low- and mid-latitude regions) are observed at equatorial, low- and mid-latitude stations. Also, on the night of 25-26, ionospheric plasma bubbles are observed at equatorial

  17. Storms

    International Nuclear Information System (INIS)

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

    1985-01-01

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

  18. Detection and Characterization of Equatorial Scintillation for Real-Time Operational Support

    National Research Council Canada - National Science Library

    McNeil, W

    1997-01-01

    The Phillips Laboratory Scintillation Network Decision Aid (PL-SCINDA) is a software tool which uses real-time data from remote sites to model ionospheric plasma depletions in the equatorial region...

  19. The storm time central plasma sheet

    Directory of Open Access Journals (Sweden)

    R. Schödel

    2002-11-01

    Full Text Available The plasma sheet plays a key role during magnetic storms because it is the bottleneck through which large amounts of magnetic flux that have been eroded from the dayside magnetopause have to be returned to the dayside magnetosphere. Using about five years of Geotail data we studied the average properties of the near- and midtail central plasma sheet (CPS in the 10–30 RE range during magnetic storms. The earthward flux transport rate is greatly enhanced during the storm main phase, but shows a significant earthward decrease. Hence, since the magnetic flux cannot be circulated at a sufficient rate, this leads to an average dipolarization of the central plasma sheet. An increase of the specific entropy of the CPS ion population by a factor of about two during the storm main phase provides evidence for nonadiabatic heating processes. The direction of flux transport during the main phase is consistent with the possible formation of a near-Earth neutral line beyond ~20 RE.Key words. Magnetospheric physics (plasma convection; plasma sheet; storms and substorms

  20. Real-time analytics with Storm and Cassandra

    CERN Document Server

    Saxena, Shilpi

    2015-01-01

    If you want to efficiently use Storm and Cassandra together and excel at developing production-grade, distributed real-time applications, then this book is for you. No prior knowledge of using Storm and Cassandra together is necessary. However, a background in Java is expected.

  1. Geometry of duskside equatorial current during magnetic storm main phase as deduced from magnetospheric and low-altitude observations

    Directory of Open Access Journals (Sweden)

    S. Dubyagin

    2013-03-01

    Full Text Available We present the results of a coordinated study of the moderate magnetic storm on 22 July 2009. The THEMIS and GOES observations of magnetic field in the inner magnetosphere were complemented by energetic particle observations at low altitude by the six NOAA POES satellites. Observations in the vicinity of geosynchronous orbit revealed a relatively thin (half-thickness of less than 1 RE and intense current sheet in the dusk MLT sector during the main phase of the storm. The total westward current (integrated along the z-direction on the duskside at r ~ 6.6 RE was comparable to that in the midnight sector. Such a configuration cannot be adequately described by existing magnetic field models with predefined current systems (error in B > 60 nT. At the same time, low-altitude isotropic boundaries (IB of > 80 keV protons in the dusk sector were shifted ~ 4° equatorward relative to the IBs in the midnight sector. Both the equatorward IB shift and the current strength on the duskside correlate with the Sym-H* index. These findings imply a close relation between the current intensification and equatorward IB shift in the dusk sector. The analysis of IB dispersion revealed that high-energy IBs (E > 100 keV always exhibit normal dispersion (i.e., that for pitch angle scattering on curved field lines. Anomalous dispersion is sometimes observed in the low-energy channels (~ 30–100 keV. The maximum occurrence rate of anomalous dispersion was observed during the main phase of the storm in the dusk sector.

  2. Storm-associated variations of equatorially mirroring ring current protons, 1--800 keV, at constant first adiabatic invariant

    International Nuclear Information System (INIS)

    Lyons, L.R.; Williams, D.J.

    1976-01-01

    Explorer 45 observations of ring current protons mirroring near the equator, 1--800 keV, are presented at constant first adiabatic invariant μ throughout the period of the December 17, 1971, geomagnetic storm. To obtain μ, simultaneous magnetic field and particle observations are used. Particle deceleration in response to the storm time magnetic field decrease causes ring current measurements viewed at constant energy to underestimate the storm time increase in proton intensities at energies approximately-less-than200 keV. This adiabatic deceleration also accounts for the large flux decreases observed at energies approximately-greater-than200 keV during the storm, in contradiction with previous results (Soraas and Davis, 1968) obtained using a model for the storm time magnetic field

  3. Storm-time total electron content and its response to penetration electric fields over South America

    Directory of Open Access Journals (Sweden)

    P. M. de Siqueira

    2011-10-01

    Full Text Available In this work the response of the ionosphere due to the severe magnetic storm of 7–10 November 2004 is investigated by analyzing GPS Total Electron Content (TEC maps constructed for the South America sector. In order to verify the disturbed zonal electric fields in South America during the superstorm, ionospheric vertical drift data obtained from modeling results are used in the analysis. The vertical drifts were inferred from ΔH magnetometer data (Jicamarca-Piura following the methodology presented by Anderson et al. (2004. Also used were vertical drifts measured by the Jicamarca ISR. Data from a digisonde located at São Luís, Brazil (2.33° S, 44.2° W, dip latitude 0.25° are presented to complement the Jicamarca equatorial data. Penetration electric fields were observed by the comparison between the equatorial vertical drifts and the Interplanetary Electric Field (IEF. The TEC maps obtained from GPS data reflect the ionospheric response over the South America low-latitude and equatorial region. They reveal unexpected plasma distributions and TEC levels during the main phase of the superstorm on 7 November, which is coincident with the local post-sunset hours. At this time an increase in the pre-reversal enhancement was expected to develop the Equatorial Ionization Anomaly (EIA but we observed the absence of EIA. The results also reveal well known characteristics of the plasma distributions on 8, 9, and 10 November. The emphasized features are the expansion and intensification of EIA due to prompt penetration electric fields on 9 November and the inhibition of EIA during post-sunset hours on 7, 8, and 10 November. One important result is that the TEC maps provided a bi-dimensional view of the ionospheric changes offering a spatial description of the electrodynamics involved, which is an advantage over TEC measured by isolated GPS receivers.

  4. Resonant ULF absorption in storm time conditions

    Directory of Open Access Journals (Sweden)

    Badin V.I.

    2017-03-01

    Full Text Available The work deals with ULF radar observations of the high-latitude ionosphere. Doppler data from the Norwegian STARE instrument are analyzed for the moderate magnetic storm observed on December 31, 1999 – January 01, 2000. Upon averaging the Doppler signals along radar beams, the spectral power of signals is determined for each beam as a function of frequency ranging from 1 to 10 mHz. Sharp drops (about 10 dB of spectral powers with frequency are found for all radar beams. A variational analysis of spectral powers is carried out by least squares, with power drops being modeled by stepwise profiles constructed of mean spectral powers preceding and succeeding the drops. Using this variational analysis, the frequency of the power drop is determined for each radar beam. Being averaged over all beams, this frequency is 4.8±0.5 mHz. The results obtained are interpreted as resonant absorption of ultra-low-frequency (ULF waves occurring on eigenfrequencies of magnetic field lines over wave propagation from the magnetopause deep into the magnetosphere.

  5. Continuous day-time time series of E-region equatorial electric fields derived from ground magnetic observatory data

    Science.gov (United States)

    Alken, P.; Chulliat, A.; Maus, S.

    2012-12-01

    The day-time eastward equatorial electric field (EEF) in the ionospheric E-region plays an important role in equatorial ionospheric dynamics. It is responsible for driving the equatorial electrojet (EEJ) current system, equatorial vertical ion drifts, and the equatorial ionization anomaly (EIA). Due to its importance, there is much interest in accurately measuring and modeling the EEF. However, there are limited sources of direct EEF measurements with full temporal and spatial coverage of the equatorial ionosphere. In this work, we propose a method of estimating a continuous day-time time series of the EEF at any longitude, provided there is a pair of ground magnetic observatories in the region which can accurately track changes in the strength of the EEJ. First, we derive a climatological unit latitudinal current profile from direct overflights of the CHAMP satellite and use delta H measurements from the ground observatory pair to determine the magnitude of the current. The time series of current profiles is then inverted for the EEF by solving the governing electrodynamic equations. While this method has previously been applied and validated in the Peruvian sector, in this work we demonstrate the method using a pair of magnetometers in Africa (Samogossoni, SAM, 0.18 degrees magnetic latitude and Tamanrasset, TAM, 11.5 degrees magnetic latitude) and validate the resulting EEF values against the CINDI ion velocity meter (IVM) instrument on the C/NOFS satellite. We find a very good 80% correlation with C/NOFS IVM measurements and a root-mean-square difference of 9 m/s in vertical drift velocity. This technique can be extended to any pair of ground observatories which can capture the day-time strength of the EEJ. We plan to apply this work to more observatory pairs around the globe and distribute real-time equatorial electric field values to the community.

  6. Effective potential for equatorial motion in the Tomimatsu-Sato space-times

    Energy Technology Data Exchange (ETDEWEB)

    Calvani, M [Padua Univ. (Italy). Ist. di Astronomia

    1978-01-28

    We give general rules to draw the effective potential curves for equatorial motion in the T-S space-times either with am. Some general properties of the potentials are pointed out and few examples shown.

  7. Real Rainfall Time Series for Storm Sewer Design

    DEFF Research Database (Denmark)

    Larsen, Torben

    The paper describes a simulation method for the design of retention storages, overflows etc. in storm sewer systems. The method is based on computer simulation with real rainfall time series as input ans with the aply of a simple transfer model of the ARMA-type (autoregressiv moving average model......) as the model of the storm sewer system. The output of the simulation is the frequency distribution of the peak flow, overflow volume etc. from the overflow or retention storage. The parameters in the transfer model is found either from rainfall/runoff measurements in the catchment or from one or a few...

  8. A comparative study of TEC response for the African equatorial and mid-latitudes during storm conditions

    Czech Academy of Sciences Publication Activity Database

    Habarulema, J. B.; McKinnell, L.- A.; Burešová, Dalia; Zhang, Y.; Seemala, G.; Ngwira, Ch.; Chum, Jaroslav; Opperman, B.

    2013-01-01

    Roč. 102, Sep (2013), s. 105-114 ISSN 1364-6826 R&D Projects: GA ČR(CZ) GAP209/11/1908 Institutional support: RVO:68378289 Keywords : Magnetic storm s * African equatorialandmidlatitudeTEC * dynamics * TIDs Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.751, year: 2013 http://www.sciencedirect.com/science/article/pii/S1364682613001545

  9. The Storm Time Evolution of the Ionospheric Disturbance Plasma Drifts

    Science.gov (United States)

    Zhang, Ruilong; Liu, Libo; Le, Huijun; Chen, Yiding; Kuai, Jiawei

    2017-11-01

    In this paper, we use the C/NOFS and ROCSAT-1 satellites observations to analyze the storm time evolution of the disturbance plasma drifts in a 24 h local time scale during three magnetic storms driven by long-lasting southward IMF Bz. The disturbance plasma drifts during the three storms present some common features in the periods dominated by the disturbance dynamo. The newly formed disturbance plasma drifts are upward and westward at night, and downward and eastward during daytime. Further, the disturbance plasma drifts are gradually evolved to present significant local time shifts. The westward disturbance plasma drifts gradually migrate from nightside to dayside. Meanwhile, the dayside downward disturbance plasma drifts become enhanced and shift to later local time. The local time shifts in disturbance plasma drifts are suggested to be mainly attributed to the evolution of the disturbance winds. The strong disturbance winds arisen around midnight can constantly corotate to later local time. At dayside the westward and equatorward disturbance winds can drive the F region dynamo to produce the poleward and westward polarization electric fields (or the westward and downward disturbance drifts). The present results indicate that the disturbance winds corotated to later local time can affect the local time features of the disturbance dynamo electric field.

  10. Empirical Modeling of the Storm Time Innermost Magnetosphere Using Van Allen Probes and THEMIS Data: Eastward and Banana Currents

    Science.gov (United States)

    Stephens, G. K.; Sitnov, M. I.; Ukhorskiy, A. Y.; Roelof, E. C.; Tsyganenko, N. A.; Le, G.

    2016-01-01

    The structure of storm time currents in the inner magnetosphere, including its innermost region inside 4R(sub E), is studied for the first time using a modification of the empirical geomagnetic field model TS07D and new data from Van Allen Probes and Time History of Events and Macroscale Interactions during Substorms missions. It is shown that the model, which uses basis-function expansions instead of ad hoc current modules to approximate the magnetic field, consistently improves its resolution and magnetic field reconstruction with the increase of the number of basis functions and resolves the spatial structure and evolution of the innermost eastward current. This includes a connection between the westward ring current flowing largely at R > or approx. 3R(sub E) and the eastward ring current concentrated at R banana current' was previously inferred from the pressure distributions based on the energetic neutral atom imaging and first-principles ring current simulations. The morphology of the equatorial currents is dependent on storm phase. During the main phase, it is complex, with several asymmetries forming banana currents. Near SYM-H minimum, the banana current is strongest, is localized in the evening-midnight sector, and is more structured compared to the main phase. It then weakens during the recovery phase resulting in the equatorial currents to become mostly azimuthally symmetric.

  11. A near-infrared, optical, and ultraviolet polarimetric and timing investigation of complex equatorial dusty structures

    Science.gov (United States)

    Marin, F.; Rojas Lobos, P. A.; Hameury, J. M.; Goosmann, R. W.

    2018-05-01

    Context. From stars to active galactic nuclei, many astrophysical systems are surrounded by an equatorial distribution of dusty material that is, in a number of cases, spatially unresolved even with cutting edge facilities. Aims: In this paper, we investigate if and how one can determine the unresolved and heterogeneous morphology of dust distribution around a central bright source using time-resolved polarimetric observations. Methods: We used polarized radiative transfer simulations to study a sample of circumnuclear dusty morphologies. We explored a grid of geometrically variable models that are uniform, fragmented, and density stratified in the near-infrared, optical, and ultraviolet bands, and we present their distinctive time-dependent polarimetric signatures. Results: As expected, varying the structure of the obscuring equatorial disk has a deep impact on the inclination-dependent flux, polarization degree and angle, and time lags we observe. We find that stratified media are distinguishable by time-resolved polarimetric observations, and that the expected polarization is much higher in the infrared band than in the ultraviolet. However, because of the physical scales imposed by dust sublimation, the average time lags of months to years between the total and polarized fluxes are important; these time lags lengthens the observational campaigns necessary to break more sophisticated, and therefore also more degenerated, models. In the ultraviolet band, time lags are slightly shorter than in the infrared or optical bands, and, coupled to lower diluting starlight fluxes, time-resolved polarimetry in the UV appears more promising for future campaigns. Conclusions: Equatorial dusty disks differ in terms of inclination-dependent photometric, polarimetric, and timing observables, but only the coupling of these different markers can lead to inclination-independent constraints on the unresolved structures. Even though it is complex and time consuming, polarized

  12. Ionosonde observations of the effects of the major magnetic storm of September 22-26, 1999 at equatorial station in west Africa

    Science.gov (United States)

    Coulibaly, I. S.; Adohi, B. J.-P.; Tanoh, K. S.

    2018-05-01

    A new approach to study the mechanisms of storm-time variations in the F-layer height and critical frequency at dip-equator is proposed. The latitudinal variations in the magnetic disturbance index DP were combined with h'F and foF2 data from an IPS 42-type ionosonde at Korkogo (9.2° N, 5° W; 2.4° S dip lat), Ivory Coast, to investigate the nighttime ionospheric effects of the geomagnetic storm of September 22-26, 1999 in the West-African sector. A clear equatorward penetration of magnetic disturbances from high latitudes regions was observed. At dip-equator, the DP magnetic disturbance pattern showed up to four distinct regimes of disturbance electric fields, each associated with a specific phase of the storm. A regime of westward transient electric fields followed by a regime of eastward transient electric fields occurred during the main phase of the storm. This was preceded by a period of quasi-absence of disturbance during the compression phase, the whole followed by a regime of westward persistent disturbance electric fields during the recovery phase. From the latitudinal variations and the shapes of these perturbations, we could associate the regime of westward (resp. eastward) disturbance electric fields with prompt penetration (resp. overshielding) occasioned by magnetospheric convections and the persistent one with a cumulative effect of storm-time winds and magnetospheric convections from high latitudes regions. The h'F variations were found to be strongly correlated with the DP ones, clearly providing evidence for the prevalence of these electric fields on the observed F-layer motions. Additionally, the foF2 variations showed two periods of depleted electron density, one in the evening during the compression phase of the storm and the other near midnight. We discussed the mechanisms of these ionospheric negative storms in the light of earlier investigations of storm-time ionospheric disturbances and validated our method by comparison of the above

  13. Quiet Time Depression of the Equatorial Electrojet and Dynamics of the F-layer Ionosphere

    Science.gov (United States)

    Khadka, S.; Valladares, C. E.; Doherty, P.

    2017-12-01

    The depression of the equatorial electrojet (EEJ) is marked by a westward current due to streaming movement of laterally limited (±3°) charged particles in the ionospheric E region during the day along the magnetic equator. It is a complex low-latitude phenomenon and driven by various sources of electric fields associated with global neutral wind, solar tidal force, Interplanetary magnetic Field (IMF), etc. This unique physical property of the equatorial ionosphere holds a great promise for sorting out the governing mechanism of the dayside ionospheric electrodynamics and the onset of the enigmatic plasma structures in the ionospheric layers. Present study provides an overview of the special sequence of the longitudinal, seasonal, and occurrence rate variability of the depression of the EEJ, including its temporal variation, using data from an excellent chain of magnetic and ionospheric observatories along the low-latitude regions. A case and statistical study of the geomagnetically quiet time depression of EEJ strengths is presented using a pair of magnetometers, one located at the dip equator and another off the dip equator (±6° to ±9° away) in the American low-latitude regions. The significance of the variability of the depression of the EEJ current observed in the scenario of vertical drifts, sporadic E-layer, the equatorial F region plasma fountain, and height of the peak ionization in the F-layer, as well as GPS-TEC distributions, will be investigated.

  14. Comparing Sources of Storm-Time Ring Current O+

    Science.gov (United States)

    Kistler, L. M.

    2015-12-01

    The first observations of the storm-time ring current composition using AMPTE/CCE data showed that the O+ contribution to the ring current increases significantly during storms. The ring current is predominantly formed from inward transport of the near-earth plasma sheet. Thus the increase of O+ in the ring current implies that the ionospheric contribution to the plasma sheet has increased. The ionospheric plasma that reaches the plasma sheet can come from both the cusp and the nightside aurora. The cusp outflow moves through the lobe and enters the plasma sheet through reconnection at the near-earth neutral line. The nightside auroral outflow has direct access to nightside plasma sheet. Using data from Cluster and the Van Allen Probes spacecraft, we compare the development of storms in cases where there is a clear input of nightside auroral outflow, and in cases where there is a significant cusp input. We find that the cusp input, which enters the tail at ~15-20 Re becomes isotropized when it crosses the neutral sheet, and becomes part of the hot (>1 keV) plasma sheet population as it convects inward. The auroral outflow, which enters the plasma sheet closer to the earth, where the radius of curvature of the field line is larger, does not isotropize or become significantly energized, but remains a predominantly field aligned low energy population in the inner magnetosphere. It is the hot plasma sheet population that gets accelerated to high enough energies in the inner magnetosphere to contribute strongly to the ring current pressure. Thus it appears that O+ that enters the plasma sheet further down the tail has a greater impact on the storm-time ring current than ions that enter closer to the earth.

  15. Tomographic reconstruction of storm time RC ion distribution from ENA images on board multiple spacecraft

    Science.gov (United States)

    Ma, Shu-Ying; Yan, Wei-Nan; Xu, Liang

    2015-11-01

    A quantitative retrieval of 3-D distribution of energetic ions as energetic neutral atoms (ENA) sources is a challenging task. In this paper the voxel computerized tomography (CT) method is initially applied to reconstruct the 3-D distribution of energetic ions in the magnetospheric ring current (RC) region from ENA emission images on board multiple spacecraft. To weaken the influence of low-altitude emission (LAE) on the reconstruction, the LAE-associated ENA intensities are corrected by invoking the thick-target approximation. To overcome the divergence in iteration due to discordant instrument biases, a differential ENA voxel CT method is developed. The method is proved reliable and advantageous by numerical simulation for the case of constant bias independent of viewing angle. Then this method is implemented with ENA data measured by the Two Wide-angle Imaging Neutral-atom Spectrometers mission which performs stereoscopic ENA imaging. The 3-D spatial distributions and energy spectra of RC ion flux intensity are reconstructed for energies of 4-50 keV during the main phase of a major magnetic storm. The retrieved ion flux distributions seem to correspond to an asymmetric partial RC, located mainly around midnight favoring the postmidnight with L = 3.5-7.0 in the equatorial plane. The RC ion distributions with magnetic local time depend on energy, with major equatorial flux peak for lower energy located east of that for higher energy. In comparison with the ion energy spectra measured by Time History of Events and Macroscale Interactions during Substorms-D satellite flying in the RC region, the retrieved spectrum from remotely sensed ENA images are well matched with the in situ measurements.

  16. Radial transport of storm time ring current ions

    Science.gov (United States)

    Lui, A. T. Y.

    1993-01-01

    Radial transport of energetic ions for the development of the main phase of geomagnetic storms is investigated with data from the medium energy particle analyzer (MEPA) on the Charge Composition Explorer spacecraft, which monitored protons, helium ions, and the carbon-nitrogen-oxygen group, which is mostly dominated by oxygen ions. From a study of four geomagnetic storms, we show that the flux increase of these ions in the inner ring current region can be accounted for by an inward displacement of the ring current population by 0.5 to 3.5 R(E). There is a general trend that a larger inward displacement occurs at higher L shells than at lower ones. These results are in agreement with previous findings. The radially injected population consists of the prestorm population modified by substorm injections which occur on a much shorter time scale than that for a storm main phase. It is also found that the inward displacement is relatively independent of ion mass and energy, suggesting that the radial transport of these energetic ions is effected primarily by convective motion from a large electric field or by diffusion resulting from magnetic field fluctuations.

  17. Storm time electric field penetration observed at mid-latitude

    International Nuclear Information System (INIS)

    Yeh, H.C.; Foster, J.C.; Rich, F.J.; Swider, W.

    1991-01-01

    During the height of the February 8-9, 1986, magnetic storm the Millstone Hill radar was in the evening local time sector (1600-2200 MLT). Radar observations indicate that high speed (>1,000 m s -1 ) westward ion flow penetrated deeply below 50 degree invariant latitude (Λ) and persisted for 6 hours between 2100 UT on February 8 and 0300 UT on February 9. The double-peaked ion convection feature was pronounced throughout the period, and the separation in the dual maxima ranged from 4 degree to 10 degree. The latitude positions of the high-latitude ion drift peak and the convection reversal varied in unison. The low-latitude ion drift peak (∼49 degree Λ or L =2.3) did not show significant universal time/magnetic local time (UT/MLT) variation in its latitude location but showed a decrease in magnitude during the initial recovery phase of the storm. Using simultaneous particle (30 eV-30 keV) precipitation data from the DMSP F6 and F7 satellites, the authors find the high-latitude ion drift peak to coincide with the boundary plasma sheet/central plasma sheet transition in the high ionospheric conductivity (>15 mho) region. The low-latitude ion drift peak lay between the equatorward edges of the electron and soft ( + dominated ring current energy density in magnetic latitude. The low-latitude ion drift peak is the low-altitude signature of the electric field shielding effect associated with ring current penetration into the outer layer of the storm time plasmasphere

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

    Directory of Open Access Journals (Sweden)

    M. Mendillo

    2009-04-01

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

  19. Spatio-temporal structure of storm-time chorus

    Czech Academy of Sciences Publication Activity Database

    Santolík, Ondřej; Gurnett, D. A.; Pickett, J. S.; M. Parrot, M.; Cornilleau-Wehrlin, N.

    2003-01-01

    Roč. 108, A7 (2003), s. 7-1-7-14, doi:10.1029/2002JA009791, 2003 ISSN 0148-0227 R&D Projects: GA ČR GA202/03/0832; GA MŠk ME 650 Grant - others:NASA(US) NAG5-9974 Institutional research plan: CEZ:AV0Z3042911; CEZ:MSM 113200004 Keywords : storm -time chorus emissions * whistler mode * propagation analysis Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.992, year: 2003

  20. Complexities of the storm-time characteristics of ionospheric total electron content

    International Nuclear Information System (INIS)

    Kane, R.P.

    1982-01-01

    The complexities of the storm-time variations of the ionospheric total electron content are briefly reviewed. It is suggested that large variations from storm to storm may be due to irregular flows from the auroral region towards equator. A proper study of such flows needs an elaborate network of TEC measuring instruments. The need of planning and organizing such a network is emphasized

  1. Evaluation of the STORM model storm-time corrections for middle latitude

    Czech Academy of Sciences Publication Activity Database

    Burešová, Dalia; McKinnell, L.- A.; Šindelářová, Tereza; de la Morena, B. A.

    2010-01-01

    Roč. 46, č. 8 (2010), s. 1039-1046 ISSN 0273-1177 R&D Projects: GA ČR GA205/08/1356; GA AV ČR 1QS300120506 Institutional research plan: CEZ:AV0Z30420517 Keywords : Ionosphere * Geomagnetic storms * STORM model * International Reference Ionosphere (IRI) Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.076, year: 2010

  2. Letter to the Editor: Geomagnetic storm effects at low latitudes

    OpenAIRE

    R. G. Rastogi; R. G. Rastogi

    1999-01-01

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

  3. Empirical Modeling of the Storm Time Innermost Magnetosphere Using Van Allen Probes and THEMIS Data: Eastward and Banana Currents

    Science.gov (United States)

    Stephens, G. K.; Sitnov, M. I.; Ukhorskiy, A. Y.; Roelof, E. C.; Tsyganenko, N. A.; Le, G.

    2016-01-01

    The structure of storm time currents in the inner magnetosphere, including its innermost region inside 4R(sub E), is studied for the first time using a modification of the empirical geomagnetic field model TS07D and new data from Van Allen Probes and Time History of Events and Macroscale Interactions during Substorms missions. It is shown that the model, which uses basis-function expansions instead of ad hoc current modules to approximate the magnetic field, consistently improves its resolution and magnetic field reconstruction with the increase of the number of basis functions and resolves the spatial structure and evolution of the innermost eastward current. This includes a connection between the westward ring current flowing largely at R > or approx. 3R(sub E) and the eastward ring current concentrated at R storm phase. During the main phase, it is complex, with several asymmetries forming banana currents. Near SYM-H minimum, the banana current is strongest, is localized in the evening-midnight sector, and is more structured compared to the main phase. It then weakens during the recovery phase resulting in the equatorial currents to become mostly azimuthally symmetric.

  4. Effect of Interplanetary Magnetic Field and Disturb Storm Time on H ...

    Indian Academy of Sciences (India)

    E). We also study the effect of vertical component of interplanetary magnetic field (IMF) on the variation of the magnitude of H component during storm time of April, July and. November 2004. Results show that before sudden storm commencement. (SSC) time magnitude of H component and IMF show smooth variation but.

  5. A storm-time plasmasphere evolution study using data assimilation

    Science.gov (United States)

    Nikoukar, R.; Bust, G. S.; Bishop, R. L.; Coster, A. J.; Lemon, C.; Turner, D. L.; Roeder, J. L.

    2017-12-01

    In this work, we study the evolution of the Earth's plasmasphere during geomagnetic active periods using the Plasmasphere Data Assimilation (PDA) model. The total electron content (TEC) measurements from an extensive network of global ground-based GPS receivers as well as GPS receivers on-board Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) satellites and Communications/Navigation Outage Forecasting System (C/NOFS) satellite are ingested into the model. Global Core Plasma model, which is an empirical plasmasphere model, is utilized as the background model. Based on the 3D-VAR optimization, the PDA assimilative model benefits from incorporation of regularization techniques to prevent non-physical altitudinal variation in density estimates due to the limited-angle observational geometry. This work focuses on the plasmapause location, plasmasphere erosion time scales and refilling rates during the main and recovery phases of geomagnetic storms as estimated from the PDA 3-dimensional global maps of electron density in the ionosphere/plasmasphere. The comparison between the PDA results with in-situ density measurements from THEMIS and Van Allen Probes, and the RCM-E first-principle model will be also presented.

  6. Storm time variation of radiative cooling of thermosphere by nitric oxide emission

    Science.gov (United States)

    Krishna, M. V. Sunil; Bag, Tikemani; Bharti, Gaurav

    2016-07-01

    The fundamental vibration-rotation band emission (Δν=1, Δ j=0,± 1) by nitric oxide (NO) at 5.3 µm is one of the most important cooling mechanisms in thermosphere. The collisional vibrational excitation of NO(ν=0) by impact with atomic oxygen is the main source of vibrationally excited nitric oxide. The variation of NO density depends on latitude, longitude and season. The present study aims to understand how the radiative flux gets influenced by the severe geomagnetic storm conditions. The variation of Nitric Oxide (NO) radiative flux exiting thermosphere is studied during the superstorm event of 7-12 November, 2004. The observations of TIMED/SABER suggest a strong anti-correlation with the O/N_2 ratio observed by GUVI during the same period. On a global scale the NO radiative flux showed an enhancement during the main phase on 8 November, 2004, whereas maximum depletion in O/N_2 is observed on 10 November, 2004. Both O/N_2 and NO radiative flux were found to propagate equatorward due to the effect of meridional wind resulting from joule and particle heating in polar region. Larger penetrations is observed in western longitude sectors. These observed variations are effectively connected to the variations in neutral densities. In the equatorial sectors, O/N_2 shows enhancement but almost no variation in radiative flux is observed. The possible reasons for the observed variations in NO radiative emission and O/N_2 ratios are discussed in the light of equator ward increase in the densities and prompt penetration.

  7. Storm blueprints patterns for distributed real-time computation

    CERN Document Server

    Goetz, P Taylor

    2014-01-01

    A blueprints book with 10 different projects built in 10 different chapters which demonstrate the various use cases of storm for both beginner and intermediate users, grounded in real-world example applications.Although the book focuses primarily on Java development with Storm, the patterns are more broadly applicable and the tips, techniques, and approaches described in the book apply to architects, developers, and operations.Additionally, the book should provoke and inspire applications of distributed computing to other industries and domains. Hadoop enthusiasts will also find this book a go

  8. Letter to the Editor: Geomagnetic storm effects at low latitudes

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    Full Text Available The geomagnetic horizontal (H field from the chain of nine observatories in India are used to study the storm-time and disturbance daily variations. The peak decrease in storm-time variation in H showed significant enhancements at the equatorial electrojet stations over and above the normally expected decrease due to the ring current effects corrected for geomagnetic latitudes. The disturbance daily variation of H at equatorial stations showed a large decrease around midday hours over and above the usual dawn-maximum and dusk-minimum seen at any mid-latitude stations around the world. These slow and persistent additional decreases of H of disturbance daily variation at equatorial latitudes could be the effect of a westward electric field due to the Disturbance Ionospheric dynamo coupled with abnormally large electrical conductivities in the E region over the equator.Key words. Ionosphere (electric fields and currents · Magnetospheric physics (electric fields; storms and substorms

  9. Letter to the Editor: Geomagnetic storm effects at low latitudes

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    1999-03-01

    Full Text Available The geomagnetic horizontal (H field from the chain of nine observatories in India are used to study the storm-time and disturbance daily variations. The peak decrease in storm-time variation in H showed significant enhancements at the equatorial electrojet stations over and above the normally expected decrease due to the ring current effects corrected for geomagnetic latitudes. The disturbance daily variation of H at equatorial stations showed a large decrease around midday hours over and above the usual dawn-maximum and dusk-minimum seen at any mid-latitude stations around the world. These slow and persistent additional decreases of H of disturbance daily variation at equatorial latitudes could be the effect of a westward electric field due to the Disturbance Ionospheric dynamo coupled with abnormally large electrical conductivities in the E region over the equator.Key words. Ionosphere (electric fields and currents · Magnetospheric physics (electric fields; storms and substorms

  10. Equatorial night-time spread-F characteristics observed from stations in the Western Pacific

    International Nuclear Information System (INIS)

    Huang Tianxi

    1985-01-01

    A comparative study of the ionospheric spread-F observed at an equatorial station. Port Moresby (9 0 24.5'S, 147 0 9.9'E; magn. Dip lat. 18 0 S), Papua new Guinea, with corresponding data from the East Asian stations during a period 27 May-19 Jun 1983, as well as the same periods for 1981 and 1982, is presented. The Port Moresby spread-F condition is particularly outstanding and persistent at night and the occurrence of spread-F between 23 LT and 05 LT near June solstice is very high, reaching 100% of all observed nights. The latitudinal variation of nocturnal spread-F, its duration and connection with sunspot number are analyzed. The relationship between long-term variation of night-time spread-F occurrence and solar activity during June and December solstices from 1954 up to 1984 at a typical lower magnetic latitudinal station. Wuhan (30 0 32.7'N, 114 0 21.5'E; magn. dip lat. 26 0 N), is also investigated. (author)

  11. Storm-time ring current: model-dependent results

    Directory of Open Access Journals (Sweden)

    N. Yu. Ganushkina

    2012-01-01

    Full Text Available The main point of the paper is to investigate how much the modeled ring current depends on the representations of magnetic and electric fields and boundary conditions used in simulations. Two storm events, one moderate (SymH minimum of −120 nT on 6–7 November 1997 and one intense (SymH minimum of −230 nT on 21–22 October 1999, are modeled. A rather simple ring current model is employed, namely, the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM, in order to make the results most evident. Four different magnetic field and two electric field representations and four boundary conditions are used. We find that different combinations of the magnetic and electric field configurations and boundary conditions result in very different modeled ring current, and, therefore, the physical conclusions based on simulation results can differ significantly. A time-dependent boundary outside of 6.6 RE gives a possibility to take into account the particles in the transition region (between dipole and stretched field lines forming partial ring current and near-Earth tail current in that region. Calculating the model SymH* by Biot-Savart's law instead of the widely used Dessler-Parker-Sckopke (DPS relation gives larger and more realistic values, since the currents are calculated in the regions with nondipolar magnetic field. Therefore, the boundary location and the method of SymH* calculation are of key importance for ring current data-model comparisons to be correctly interpreted.

  12. Real Rainfall Time Series for Storm Sewer Design

    DEFF Research Database (Denmark)

    Larsen, Torben

    1981-01-01

    to a storm sewer system. The output of the simulation is the frequency distribution of the peak flow, overflow volume etc. from the overflow or the retention storage. The parameters in the transfer model are found either from rainfall/runoff measurements in the catchment or from one or more simulations...

  13. Equatorial electrojet as part of the global circuit: a case-study from the IEEY

    Directory of Open Access Journals (Sweden)

    A. T. Kobea

    1998-06-01

    Full Text Available Geomagnetic storm-time variations often occur coherently at high latitude and the day-side dip equator where they affect the normal eastward Sq field. This paper presents an analysis of ground magnetic field and ionospheric electrodynamic data related to the geomagnetic storm which occured on 27 May 1993 during the International Equatorial Electrojet Year (IEEY experiment. This storm-signature analysis on the auroral, mid-latitude and equatorial ground field and ionospheric electrodynamic data leads to the identification of a sensitive response of the equatorial electrojet (EEJ to large-scale auroral return current: this response consists in a change of the eastward electric field during the pre-sunrise hours (0400-0600 UT coherently to the high-, mid-, and equatorial-latitude H decrease and the disappearance of the EEJ irregularities between the time-interval 0800-0950 UT. Subsequent to the change in h'F during pre-sunrise hours, the observed foF2 increase revealed an enhancement of the equatorial ionization anomaly (EIA caused by the high-latitude penetrating electric field. The strengthening of these irregularities attested by the Doppler frequency increase tracks the H component at the equator which undergoes a rapid increase around 0800 UT. The ∆H variations observed at the equator are the sum of the following components: SR, DP, DR, DCF and DT.Keywords. Equatorial electrojet · Magnetosphere-ionosphere interactions · Electric fields and currents · Auroral ionosphere · Ionospheric disturbances

  14. Delayed storm-time increases in the whistler rate at mid-latitudes

    International Nuclear Information System (INIS)

    Andrews, M.K.

    1975-01-01

    The occurrence of whistlers during 105 magnetic storms in the period 1963 to 1968 is studied. Evidence that more whistlers occur during the storm recovery period is presented. Assuming that the increased whistler rate implies the presence of more ducts, similarities are noted between the storm-time duct population and the incidence of mid-latitude spread-F in both time and space. It is suggested that a fresh examination of the physical processes involved in spread-F may aid understanding of the formation of whistler ducts. (author)

  15. Connection of the positive phase of ionospheric storms with the day-time cusp

    International Nuclear Information System (INIS)

    Morozova, L.D.; Danilov, A.D.

    1986-01-01

    Data on the relation of ionospheric storms with the day-time cusp are considered. Experimental data on the velocity and direction of wind from the day-time cusp region, obtained for perturbed conditions on 30.12.1981, are analyzed. It is shown that perturbed wind from the cusp results in the increase of the value δf 0 F2 and under conditions before magnetic storm onset unambiguously causes positive ionosheric perturbation, and under conditions of a developed magnetic storm-either a positive perturbation or a decrease in the amplitude of negative perturbation

  16. Surface-Borne Time-of-Reception Measurements (STORM), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Invocon proposes the Surface-borne Time-Of-Reception Measurements (STORM) system as a method to locate the position of lightning strikes on aerospace vehicles....

  17. Methodology for time-domain estimation of storm time geoelectric fields using the 3-D magnetotelluric response tensors

    Science.gov (United States)

    Kelbert, Anna; Balch, Christopher C.; Pulkkinen, Antti; Egbert, Gary D.; Love, Jeffrey J.; Rigler, E. Joshua; Fujii, Ikuko

    2017-07-01

    Geoelectric fields at the Earth's surface caused by magnetic storms constitute a hazard to the operation of electric power grids and related infrastructure. The ability to estimate these geoelectric fields in close to real time and provide local predictions would better equip the industry to mitigate negative impacts on their operations. Here we report progress toward this goal: development of robust algorithms that convolve a magnetic storm time series with a frequency domain impedance for a realistic three-dimensional (3-D) Earth, to estimate the local, storm time geoelectric field. Both frequency domain and time domain approaches are presented and validated against storm time geoelectric field data measured in Japan. The methods are then compared in the context of a real-time application.

  18. Learning Storm

    CERN Document Server

    Jain, Ankit

    2014-01-01

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

  19. Geomagnetically Induced Currents Around the World During the 17 March 2015 Storm

    Science.gov (United States)

    Carter, B. A.; Yizengaw, E.; Pradipta, R.; Weygand, J. M.; Piersanti, M.; Pulkkinen, Antti Aleksi; Moldwin, M. B.; Norman, R.; Zhang, K.

    2016-01-01

    Geomagnetically induced currents (GICs) represent a significant space weather issue for power grid and pipeline infrastructure, particularly during severe geomagnetic storms. In this study, magnetometer data collected from around the world are analyzed to investigate the GICs caused by the 2015 St. Patricks Day storm. While significant GIC activity in the high-latitude regions due to storm time substorm activity is shown for this event, enhanced GIC activity was also measured at two equatorial stations in the American and Southeast Asian sectors. This equatorial GIC activity is closely examined, and it is shown that it is present both during the arrival of the interplanetary shock at the storm sudden commencement (SSC) in Southeast Asia and during the main phase of the storm approximately 10 h later in South America. The SSC caused magnetic field variations at the equator in Southeast Asia that were twice the magnitude of those observed only a few degrees to the north, strongly indicating that the equatorial electrojet (EEJ) played a significant role. The large equatorial magnetic field variations measured in South America are also examined, and the coincident solar wind data are used to investigate the causes of the sudden changes in the EEJ approximately 10 h into the storm. From this analysis it is concluded that sudden magnetopause current increases due to increases in the solarwind dynamic pressure, and the sudden changes in the resultant magnetospheric and ionospheric current systems, are the primary drivers of equatorial GICs.

  20. Variability in foF2 at an equatorial station and the influence of magnetic activity

    International Nuclear Information System (INIS)

    Adeniyi, J.O.; Radicella, S.M.

    2003-01-01

    Variability in foF2 is investigated for an equatorial station in the African region. Variability during the day time at high solar activity varies between 10 and 30 percent. It varies between 10 and 20 percent at high solar activity. Magnetic storms increase the variability at both solar activity periods. (author)

  1. Factors controlling storm impacts on coastal barriers and beaches - A preliminary basis for near real-time forecasting

    Science.gov (United States)

    Morton, R.A.

    2002-01-01

    Analysis of ground conditions and meteorological and oceanographic parameters for some of the most severe Atlantic and Gulf Coast storms in the U.S. reveals the primary factors affecting morphological storm responses of beaches and barrier islands. The principal controlling factors are storm characteristics, geographic position relative to storm path, timing of storm events, duration of wave exposure, wind stress, degree of flow confinement, antecedent topography and geologic framework, sediment textures, vegetative cover, and type and density of coastal development. A classification of commonly observed storm responses demonstrates the sequential interrelations among (1) land elevations, (2) water elevations in the ocean and adjacent lagoon (if present), and (3) stages of rising water during the storm. The predictable coastal responses, in relative order from high frequency beach erosion to low frequency barrier inundation, include: beach erosion, berm migration, dune erosion, washover terrace construction, perched fan deposition, sheetwash, washover channel incision, washout formation, and forced and unforced ebb flow. Near real-time forecasting of expected storm impacts is possible if the following information is available for the coast: a detailed morphological and topographic characterization, accurate storm-surge and wave-runup models, the real-time reporting of storm parameters, accurate forecasts of the storm position relative to a particular coastal segment, and a conceptual model of geological processes that encompasses observed morphological changes caused by extreme storms.

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

    Science.gov (United States)

    Osherovich, Vladimir A.; Fainberg, Joseph

    2015-01-01

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

  3. Equatorial westward electrojet impacting equatorial ionization anomaly development during the 6 April 2000 superstorm

    Science.gov (United States)

    Horvath, Ildiko; Lovell, Brian C.

    2013-11-01

    investigate the forward plasma fountain and the equatorial ionosphere in the topside region during the 6 April 2000 superstorm in the Australian sector at ~0900 LT. Space- and ground-based multi-instrument measurements, Coupled Thermosphere-Ionosphere-Plasmasphere Electrodynamics (CTIPe) simulations, and field-aligned observations comprise our results. These reveal an unusual storm development during which the eastward prompt penetration electric (E) field (PPEF) developed and operated under the continuous effects of the westward disturbance dynamo E-field (DDEF) while large-scale traveling ionospheric disturbances (TIDs) traveled equatorward and generated strong equatorward wind surges. We have identified the eastward PPEF by the superfountain effect causing the equatorial ionization anomaly (EIA)'s development with crests situated at ~±28°N (geomagnetic) in the topside ionosphere at ~840 km altitude. The westward DDEF's occurrence is confirmed by mapping the "anti-Sq" current system wherein the equatorial westward current created a weak long-lasting westward electrojet event. Line plots of vertical drift data tracked large-scale TIDs. Four scenarios, covering ~3.5 h in universal time, demonstrate that the westward DDEF became superimposed on the eastward PPEF. As these E-fields of different origins became mapped into the F region, they could interact. Consequently, the eastward PPEF-related equatorial upward E × B drift became locally reduced by up to 75 m/s near the dip equator by the westward DDEF-related equatorial downward E × B drift. Meanwhile, the EIA displayed a better development as equatorial wind surges, reproduced by CTIPe, increased from 501 to 629 m/s, demonstrating the crucial role of mechanical wind effects keeping plasma density high.

  4. Storm-time ionization enhancements at the topside low-latitude ionosphere

    Directory of Open Access Journals (Sweden)

    A. Dmitriev

    2008-05-01

    Full Text Available Ion density enhancements at the topside low-latitude ionosphere during a Bastille storm on 15–16 July 2000 and Halloween storms on 29–31 October 2003 were studied using data from ROCSAT-1/IPEI experiment. Prominent ion density enhancements demonstrate similar temporal dynamics both in the sunlit and in the nightside hemispheres. The ion density increases dramatically (up to two orders of magnitude during the main phase of the geomagnetic storms and reaches peak values at the storm maximum. The density enhancements are mostly localized in the region of a South Atlantic Anomaly (SAA, which is characterized by very intense fluxes of energetic particles. The dynamics of near-Earth radiation was studied using SAMPEX/LEICA data on >0.6 MeV electrons and >0.8 MeV protons at around 600 km altitude. During the magnetic storms the energetic particle fluxes in the SAA region and in its vicinity increase more than three orders of magnitude. The location of increased fluxes overlaps well with the regions of ion density enhancements. Two mechanisms were considered to be responsible for the generation of storm-time ion density enhancements: prompt penetration of the interplanetary electric field and abundant ionization of the ionosphere by enhanced precipitation of energetic particles from the radiation belt.

  5. Discovery of energetic molecular ions (NO+ and O2+) in the storm time ring current

    International Nuclear Information System (INIS)

    Klecker, B.; Moebius, E.; Hovestadt, D.; Scholer, M.; Gloeckler, G.; Ipavich, F.M.

    1986-01-01

    A few hours after the onset of a large geomagnetic storm on September 4, 1984, energetic molecular ions in the mass range 28--32, predminantly NO + and O 2 + , have been discovered in the outer ring current at L--7. The data have been obtained with the time-of-flight spectrometer SULEICA on the AMPTE/IRM spacecraft. We find at 160 keV/e a mean abundance ratio of the molecular ions relative to O + ions of 0.031 +- 0.004. During quiet times no molecular ions are observed, the 1 sigma upper limit of the ratio derived by averaging over several quiet periods is 0.003. The observations demonstrate the injection of ionospheric plasma into the storm time ring current and the subsequent acceleration to energies of several hundred keV on a time scale of a few hours after the onset of the magnetic storm

  6. Equatorial Guinea.

    Science.gov (United States)

    1989-03-01

    Equatorial Guinea is situated on the Gulf of Guinea along the west African coast between Cameroon and Gabon. The people are predominantly of Bantu origin. The country's ties with Spain are significant; in 1959, it became the Spanish Equatorial region ruled by Spain's commissioner general. Recent political developments in Equatorial Guinea include the formation of the Democratic Party for Equatorial Guinea in July of 1987 and the formation of a 60-member unicameral Chamber of Representatives of the People in 1983. Concerning the population, 83% of the people are Catholic and the official language is Spanish. Poverty and serious health, education and sanitary problems exist. There is no adequate hospital and few trained physicians, no dentists, and no opticians. Malaria is endemic and immunization for yellow fever is required for entrance into the country. The water is not potable and many visitors to the country bring bottled water. The tropical climate of Equatorial Guinea provides the climate for the country's largest exports and source of economy; cacao, wood and coffee. Although the country, as a whole, has progressed towards developing a participatory political system, there are still problems of governmental corruption in the face of grave health and welfare conditions. In recent years, the country has received assistance from the World Bank and the United States to aid in its development.

  7. Association of time of occurrence of electrical heart storms with environmental physical activity.

    Science.gov (United States)

    Stoupel, Eliiyahu; Kusniec, Jairo; Golovchiner, Gregory; Abramson, Evgeny; Kadmon, Udi; Strasberg, Boris

    2014-08-01

    Many publications in recent decades have reported a temporal link between medical events and environmental physical activity. The aim of this study was to analyze the time of occurrence of electrical heart storms against levels of cosmological parameters. The sample included 82 patients (71 male) with ischemic cardiomyopathy treated with an implantable cardioverter defibrillator at a tertiary medical center in 1999-2012 (5,114 days). The time of occurrence of all electrical heart storms, defined as three or more events of ventricular tachycardia or ventricular fibrillation daily, was recorded from the defibrillator devices. Findings were analyzed against data on solar, geomagnetic, and cosmic ray (neutron) activity for the same time period obtained from space institutions in the United States and Russia. Electrical storms occurred in all months of the year, with a slight decrease in July, August, and September. Most events took place on days with lower-than-average levels of solar and geomagnetic activity and higher-than-average levels of cosmic ray (neutron) activity. There was a significant difference in mean daily cosmic ray activity between the whole observation period and the days of electrical storm activity (P = 0.0001). These data extend earlier findings on the association of the timing of cardiac events and space weather parameters to the most dangerous form of cardiac arrhythmia-electric storms. Further studies are needed to delineate the pathogenetic mechanism underlying this association. ©2014 Wiley Periodicals, Inc.

  8. Storm-time radiation belt electron dynamics: Repeatability in the outer radiation belt

    Science.gov (United States)

    Murphy, K. R.; Mann, I. R.; Rae, J.; Watt, C.; Boyd, A. J.; Turner, D. L.; Claudepierre, S. G.; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Blake, J. B.; Fennell, J. F.

    2017-12-01

    During intervals of enhanced solar wind driving the outer radiation belt becomes extremely dynamic leading to geomagnetic storms. During these storms the flux of energetic electrons can vary by over 4 orders of magnitude. Despite recent advances in understanding the nature of competing storm-time electron loss and acceleration processes the dynamic behavior of the outer radiation belt remains poorly understood; the outer radiation belt can exhibit either no change, an enhancement, or depletion in radiation belt electrons. Using a new analysis of the total radiation belt electron content, calculated from the Van Allen probes phase space density (PSD), we statistically analyze the time-dependent and global response of the outer radiation belt during storms. We demonstrate that by removing adiabatic effects there is a clear and repeatable sequence of events in storm-time radiation belt electron dynamics. Namely, the relativistic (μ=1000 MeV/G) and ultra-relativistic (μ=4000 MeV/G) electron populations can be separated into two phases; an initial phase dominated by loss followed by a second phase dominated by acceleration. At lower energies, the radiation belt seed population of electrons (μ=150 MeV/G) shows no evidence of loss but rather a net enhancement during storms. Further, we investigate the dependence of electron dynamics as a function of the second adiabatic invariant, K. These results demonstrate a global coherency in the dynamics of the source, relativistic and ultra-relativistic electron populations as function of the second adiabatic invariant K. This analysis demonstrates two key aspects of storm-time radiation belt electron dynamics. First, the radiation belt responds repeatably to solar wind driving during geomagnetic storms. Second, the response of the radiation belt is energy dependent, relativistic electrons behaving differently than lower energy seed electrons. These results have important implications in radiation belt research. In particular

  9. Access of energetic particles to storm time ring current through enhanced radial diffusion

    International Nuclear Information System (INIS)

    Lyons, L.R.; Schulz, M.

    1989-01-01

    Magnetic storms are distinguishable from other periods of geomagnetic activity by the injection of trapped electrons and ions to the 2 approx-lt L approx-lt 4 region. It has been proposed previously that this injection results from an inward displacement of the preexisting trapped-particle population by enhanced storm time electric fields. However, high-energy (approx-gt 40 keV) ring-current particles have drift periods that are typically shorter than the time of the main-phase development, and so the direct radial transport of these particles is restricted. The authors propose here that the transport of approx-gt 40 keV particles into the storm time ring current can result from enhanced stochastic radial transport driven by fluctuating electric fields during a storm's main phase. They estimate the effects of such electric fields by applying radial-diffusion theory, assuming a preexisting trapped-particle population as the initial conditions, and they demonstrate the feasibility of explaining observed flux increases of approx-gt 40-keV particles at L approx-lt 4 by enhanced radial diffusion. It is necessary that new particles be injected near the outer boundary of the trapping region so as to maintain the fluxes there as an outer boundary condition, and they estimate that the approx-gt 40-keV portion of the storm time ring current at L ∼ 3 consists of about 50% preexisting and about 50% new particles. They thus find that formation of the storm time ring current may be explainable via a combination of direct radial transport at energies approx-lt 40 keV and diffusive radial transport at higher energies

  10. Seasonal timing of first rain storms affects rare plant population dynamics

    Science.gov (United States)

    Levine, J.M.; McEachern, A.K.; Cowan, C.

    2011-01-01

    A major challenge in forecasting the ecological consequences of climate change is understanding the relative importance of changes to mean conditions vs. changes to discrete climatic events, such as storms, frosts, or droughts. Here we show that the first major storm of the growing season strongly influences the population dynamics of three rare and endangered annual plant species in a coastal California (USA) ecosystem. In a field experiment we used moisture barriers and water addition to manipulate the timing and temperature associated with first major rains of the season. The three focal species showed two- to fivefold variation in per capita population growth rates between the different storm treatments, comparable to variation found in a prior experiment imposing eightfold differences in season-long precipitation. Variation in germination was a major demographic driver of how two of three species responded to the first rains. For one of these species, the timing of the storm was the most critical determinant of its germination, while the other showed enhanced germination with colder storm temperatures. The role of temperature was further supported by laboratory trials showing enhanced germination in cooler treatments. Our work suggests that, because of species-specific cues for demographic transitions such as germination, changes to discrete climate events may be as, if not more, important than changes to season-long variables.

  11. Midday reversal of equatorial ionospheric electric field

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    1997-10-01

    Full Text Available A comparative study of the geomagnetic and ionospheric data at equatorial and low-latitude stations in India over the 20 year period 1956–1975 is described. The reversal of the electric field in the ionosphere over the magnetic equator during the midday hours indicated by the disappearance of the equatorial sporadic E region echoes on the ionograms is a rare phenomenon occurring on about 1% of time. Most of these events are associated with geomagnetically active periods. By comparing the simultaneous geomagnetic H field at Kodaikanal and at Alibag during the geomagnetic storms it is shown that ring current decreases are observed at both stations. However, an additional westward electric field is superimposed in the ionosphere during the main phase of the storm which can be strong enough to temporarily reverse the normally eastward electric field in the dayside ionosphere. It is suggested that these electric fields associated with the V×Bz electric fields originate at the magnetopause due to the interaction of the solar wind and the interplanetary magnetic field.

  12. Midday reversal of equatorial ionospheric electric field

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    Full Text Available A comparative study of the geomagnetic and ionospheric data at equatorial and low-latitude stations in India over the 20 year period 1956–1975 is described. The reversal of the electric field in the ionosphere over the magnetic equator during the midday hours indicated by the disappearance of the equatorial sporadic E region echoes on the ionograms is a rare phenomenon occurring on about 1% of time. Most of these events are associated with geomagnetically active periods. By comparing the simultaneous geomagnetic H field at Kodaikanal and at Alibag during the geomagnetic storms it is shown that ring current decreases are observed at both stations. However, an additional westward electric field is superimposed in the ionosphere during the main phase of the storm which can be strong enough to temporarily reverse the normally eastward electric field in the dayside ionosphere. It is suggested that these electric fields associated with the V×Bz electric fields originate at the magnetopause due to the interaction of the solar wind and the interplanetary magnetic field.

  13. Case studies of the storm time variation of the polar cusp

    International Nuclear Information System (INIS)

    Meng, C.

    1983-01-01

    The latitudinal variations of the polar cusp region were examined during three intense geomagnetic storms. The variations were compared with the intensity of storm time ring current inferred from the Dst index, with the magnitude of the north-south component B/sub z/ of the interplanetary magnetic field and with substorm activity. The common feature is that the rapid equatorward shift occurred during the increase of the ring current growth and during the southward turning of the interplanetary magnetic field orientation. The equatorwardmost latitude of the cusp was reached before the peak of the ring current intensity, by a few to several hours, coinciding with the occurrence of the largest magnitude of the southward interplanetary magnetic field component. However, details of the polar cusp latitudinal movement differ from storm to storm. During the three storms studied, the poleward recovery commenced at the peak magnitude of the negative IMF B/sub z/ component, but the recovery proceeded without a clear relation to variations of the interplanetary B/sub z/ component, to the ring current intensity, or to the substorm activity. The lowest cusp latitude observed was at approx.61.7 0 , and the magnitude of this shift seems to be related to the magnitudes of -B/sub z/. It is further observed that the approximate rates of the cusp macroscopic equatorward and poleward movements are about 3 0 and 1.5 0 per hour, respectively

  14. Observations of ions of ionospheric origin in the storm-time ring current

    International Nuclear Information System (INIS)

    Johnson, R.G.; Sharp, R.D.; Shelley, E.G.

    1977-01-01

    O + , He + , and H + ions in the energy range 0.5 to 16 keV have been observed in the storm-time ring current with an energetic ion mass spectrometer aboard the polar-orbiting S3-3 satellite. During the main phases of the 29 December 1976, 6 April 1977, and 19 April 1977 magnetic storms, the O + number density within the instrument energy range in the inner ring current (L=2.8--4.0) was larger than the H + density in the altitude range from about 5000--7000 km. At two days after the main phase of the 29 December 1976 storm, O + was still the dominant ion at MLT=14.5 hours in the L=2.6--3.4 range at altitudes near 6000 km

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

    Science.gov (United States)

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

    1985-01-01

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

  16. Effect of Interplanetary Magnetic Field and Disturb Storm Time on H ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Home; Journals; Journal of Astrophysics and Astronomy; Volume 29; Issue 1-2. Effect of Interplanetary Magnetic Field and Disturb Storm Time on H Component. Rajni Devi Smita Dubey Shailendra Saini Babita Devi Ajay Dhar S. K. Vijay A. K. Gwal. Volume 29 Issue 1-2 March-June 2008 pp 281-286 ...

  17. Automating Flood Hazard Mapping Methods for Near Real-time Storm Surge Inundation and Vulnerability Assessment

    Science.gov (United States)

    Weigel, A. M.; Griffin, R.; Gallagher, D.

    2015-12-01

    Storm surge has enough destructive power to damage buildings and infrastructure, erode beaches, and threaten human life across large geographic areas, hence posing the greatest threat of all the hurricane hazards. The United States Gulf of Mexico has proven vulnerable to hurricanes as it has been hit by some of the most destructive hurricanes on record. With projected rises in sea level and increases in hurricane activity, there is a need to better understand the associated risks for disaster mitigation, preparedness, and response. GIS has become a critical tool in enhancing disaster planning, risk assessment, and emergency response by communicating spatial information through a multi-layer approach. However, there is a need for a near real-time method of identifying areas with a high risk of being impacted by storm surge. Research was conducted alongside Baron, a private industry weather enterprise, to facilitate automated modeling and visualization of storm surge inundation and vulnerability on a near real-time basis. This research successfully automated current flood hazard mapping techniques using a GIS framework written in a Python programming environment, and displayed resulting data through an Application Program Interface (API). Data used for this methodology included high resolution topography, NOAA Probabilistic Surge model outputs parsed from Rich Site Summary (RSS) feeds, and the NOAA Census tract level Social Vulnerability Index (SoVI). The development process required extensive data processing and management to provide high resolution visualizations of potential flooding and population vulnerability in a timely manner. The accuracy of the developed methodology was assessed using Hurricane Isaac as a case study, which through a USGS and NOAA partnership, contained ample data for statistical analysis. This research successfully created a fully automated, near real-time method for mapping high resolution storm surge inundation and vulnerability for the

  18. Combined TOPEX/Poseidon TEC and ionosonde observations of negative low-latitude ionospheric storms

    Directory of Open Access Journals (Sweden)

    K. J. W. Lynn

    2004-09-01

    Full Text Available Ionospheric storms showing a strong depression in daytime foF2 values were sought which penetrated to low-latitudes, as identified by vertical ionosondes operating at Darwin and Townsville over the period 1992-1998. The 32 storms thus identified showed a seasonal occurrence peaking near the equinoxes with a bias to the summer side. Of these storms, three (27 March 1995, 25 October 1997, 8 November 1997 combined Australian and South East Asian ionosonde observations with local afternoon TOPEX/Poseidon measurements of TEC. The equatorial anomaly is usually well developed at this time of day and consequently these storms were chosen for detailed study. The TOPEX/Poseidon satellite provided vertical profiles of the ionosphere across both hemispheres, thus allowing the totality of storm behaviour to be observed for the first time at low-latitudes and related directly to the ionosonde observations. The three storms were remarkably consistent in their behaviour, the negative ionospheric storm day followed some 24-36h after the beginning of a magnetic storm and the development of the equatorial anomaly was suppressed. However, the suppression of the equatorial anomaly was not the main cause of the strong depression in foF2 observed by the Southern Hemisphere ionosondes. The latter was associated with an additional bite-out in both TEC and foF2 that occurred on the southern side of the magnetic equator. None of the three storms produced any major negative disturbance outside the range of normal variability of TEC and foF2 at the northern latitude sites for which data was available, despite the absence of the anomaly. The satellite measurements show the strength of the anomaly to be highly variable from day-to-day and anomaly peaks are frequently not present even on magnetically quiet days. Thus, an absence of anomaly peaks is contained within the normal variability of non-storm days. The north-south asymmetry and seasonal occurrence are consistent with

  19. Storm-time variation of radiative cooling by Nitric Oxide as observed by TIMED-SABER and GUVI

    Science.gov (United States)

    Sunil Krishna, M. V.; Bharti, G.; Bag, T.

    2017-12-01

    The variation of O/N2 and nitric oxide radiative emission flux exiting thermosphere have been studied over northern hemisphere during the super-storm event of November 7-12, 2004. The data have been obtained from GUVI and SABER onboard the NASA's TIMED satellite. The NO radiative flux is observed to show an anti-correlation with O/N2 on a global scale. Both NO radiative flux and O/N2 ratio show equatorward motion with maximum penetration in western longitude sectors. A local variation of O, O2 and N2 densities have been calculated by using NRLMSISE-00 model over a mid-latitude location (55oN,180oE). On a local scale, model calculated O/O2 and O/N2 ratios are found to follow the observations made by GUVI. The SABER retrieved NO cooling rate (CR) at a local site suggests an enhancement during the storm period with the peak emission rate closely correlated to the progression of the storm. The peak emission altitude of NO CR moves upward during the main phase of the storm. The NO abundance has been calculated by using cooling rate and NOEM model. Both these suggest huge increase in NO density during the storm which is required to account the changes in NO radiative flux.

  20. Impact of the storm-time plasma sheet ion composition on the ring current energy density

    Science.gov (United States)

    Mouikis, C.; Kistler, L. M.; Petrinec, S. M.; Fuselier, S. A.; Cohen, I.

    2017-12-01

    The adiabatic inward transport of the night-side near-earth ( 6 Re) hot plasma sheet is the dominant contributor to the ring current pressure during storm times. During storm times, the plasma sheet composition in the 6 - 12 Re tail region changes due to O+ entry from the lobes (from the cusp) and the direct feeding from the night side auroral region. In addition, at substorm onset the plasma sheet O+ ions can be preferentially accelerated. We use MMS and observations during two magnetic storms, 5/8/2016 and 7/16/2017, to monitor the composition changes and energization in the 6 - 12 Re plasma sheet region. For both storms the MMS apogee was in the tail. In addition, we use subsequent Van Allen Probe observations (with apogee in the dawn and dusk respectively) to test if the 6-12 Re plasma sheet, observed by MMS, is a sufficient source of the O+ in the ring current. For this we will compare the phase space density (PSD) of the plasma sheet source population and the PSD of the inner magnetosphere at constant magnetic moment values as used in Kistler et al., [2016].

  1. Storm time dynamics of auroral electrojets: CHAMP observation and the Space Weather Modeling Framework comparison

    Directory of Open Access Journals (Sweden)

    H. Wang

    2008-03-01

    Full Text Available We investigate variations of the location and intensity of auroral currents during two magnetic storm periods based on magnetic field measurements from CHAMP separately for both hemispheres, as well as for the dayside and nightside. The corresponding auroral electrojet current densities are on average enhanced by about a factor of 7 compared to the quiet time current strengths. The nightside westward current densities are on average 1.8 (2.2 times larger than the dayside eastward current densities in the Northern (Southern Hemisphere. Both eastward and westward currents are present during the storm periods with the most intense electrojets appearing during the main phase of the storm, before the ring current maximizes in strength. The eastward and westward electrojet centers can expand to 55° MLat during intense storms, as is observed on 31 March 2001 with Dst=−387 nT. The equatorward shift of auroral currents on the dayside is closely controlled by the southward IMF, while the latitudinal variations on the nightside are better described by the variations of the Dst index. However, the equatorward and poleward motion of the nightside auroral currents occur earlier than the Dst variations. The Space Weather Modeling Framework (SWMF can capture the general dynamics of the storm time current variations. Both the model and the actual data show that the currents tend to saturate when the merging electric field is larger than 10 mV/m. However, the exact prediction of the temporal development of the currents is still not satisfactory.

  2. Storm time dynamics of auroral electrojets: CHAMP observation and the Space Weather Modeling Framework comparison

    Directory of Open Access Journals (Sweden)

    H. Wang

    2008-03-01

    Full Text Available We investigate variations of the location and intensity of auroral currents during two magnetic storm periods based on magnetic field measurements from CHAMP separately for both hemispheres, as well as for the dayside and nightside. The corresponding auroral electrojet current densities are on average enhanced by about a factor of 7 compared to the quiet time current strengths. The nightside westward current densities are on average 1.8 (2.2 times larger than the dayside eastward current densities in the Northern (Southern Hemisphere. Both eastward and westward currents are present during the storm periods with the most intense electrojets appearing during the main phase of the storm, before the ring current maximizes in strength. The eastward and westward electrojet centers can expand to 55° MLat during intense storms, as is observed on 31 March 2001 with Dst=−387 nT. The equatorward shift of auroral currents on the dayside is closely controlled by the southward IMF, while the latitudinal variations on the nightside are better described by the variations of the Dst index. However, the equatorward and poleward motion of the nightside auroral currents occur earlier than the Dst variations. The Space Weather Modeling Framework (SWMF can capture the general dynamics of the storm time current variations. Both the model and the actual data show that the currents tend to saturate when the merging electric field is larger than 10 mV/m. However, the exact prediction of the temporal development of the currents is still not satisfactory.

  3. The time interval distribution of sand–dust storms in theory: testing with observational data for Yanchi, China

    International Nuclear Information System (INIS)

    Liu, Guoliang; Zhang, Feng; Hao, Lizhen

    2012-01-01

    We previously introduced a time record model for use in studying the duration of sand–dust storms. In the model, X is the normalized wind speed and Xr is the normalized wind speed threshold for the sand–dust storm. X is represented by a random signal with a normal Gaussian distribution. The storms occur when X ≥ Xr. From this model, the time interval distribution of N = Aexp(−bt) can be deduced, wherein N is the number of time intervals with length greater than t, A and b are constants, and b is related to Xr. In this study, sand–dust storm data recorded in spring at the Yanchi meteorological station in China were analysed to verify whether the time interval distribution of the sand–dust storms agrees with the above time interval distribution. We found that the distribution of the time interval between successive sand–dust storms in April agrees well with the above exponential equation. However, the interval distribution for the sand–dust storm data for the entire spring period displayed a better fit to the Weibull equation and depended on the variation of the sand–dust storm threshold wind speed. (paper)

  4. Statistical analysis of storm-time near-Earth current systems

    Directory of Open Access Journals (Sweden)

    M. W. Liemohn

    2015-08-01

    Full Text Available Currents from the Hot Electron and Ion Drift Integrator (HEIDI inner magnetospheric model results for all of the 90 intense storms (disturbance storm-time (Dst minimum < −100 nT from solar cycle 23 (1996–2005 are calculated, presented, and analyzed. We have categorized these currents into the various systems that exist in near-Earth space, specifically the eastward and westward symmetric ring current, the partial ring current, the banana current, and the tail current. The current results from each run set are combined by a normalized superposed epoch analysis technique that scales the timeline of each phase of each storm before summing the results. It is found that there is a systematic ordering to the current systems, with the asymmetric current systems peaking during storm main phase (tail current rising first, then the banana current, followed by the partial ring current and the symmetric current systems peaking during the early recovery phase (westward and eastward symmetric ring current having simultaneous maxima. The median and mean peak amplitudes for the current systems ranged from 1 to 3 MA, depending on the setup configuration used in HEIDI, except for the eastward symmetric ring current, for which the mean never exceeded 0.3 MA for any HEIDI setup. The self-consistent electric field description in HEIDI yielded larger tail and banana currents than the Volland–Stern electric field, while the partial and symmetric ring currents had similar peak values between the two applied electric field models.

  5. Equatorial electrojet as part of the global circuit: a case-study from the IEEY

    Directory of Open Access Journals (Sweden)

    A. T. Kobea

    Full Text Available Geomagnetic storm-time variations often occur coherently at high latitude and the day-side dip equator where they affect the normal eastward Sq field. This paper presents an analysis of ground magnetic field and ionospheric electrodynamic data related to the geomagnetic storm which occured on 27 May 1993 during the International Equatorial Electrojet Year (IEEY experiment. This storm-signature analysis on the auroral, mid-latitude and equatorial ground field and ionospheric electrodynamic data leads to the identification of a sensitive response of the equatorial electrojet (EEJ to large-scale auroral return current: this response consists in a change of the eastward electric field during the pre-sunrise hours (0400-0600 UT coherently to the high-, mid-, and equatorial-latitude H decrease and the disappearance of the EEJ irregularities between the time-interval 0800-0950 UT. Subsequent to the change in h'F during pre-sunrise hours, the observed foF2 increase revealed an enhancement of the equatorial ionization anomaly (EIA caused by the high-latitude penetrating electric field. The strengthening of these irregularities attested by the Doppler frequency increase tracks the H component at the equator which undergoes a rapid increase around 0800 UT. The ∆H variations observed at the equator are the sum of the following components: SR, DP, DR, DCF and DT.

    Keywords. Equatorial electrojet · Magnetosphere-ionosphere interactions · Electric fields and currents · Auroral ionosphere · Ionospheric disturbances

  6. Controlling of merging electric field and IMF magnitude on storm-time changes in thermospheric mass density

    NARCIS (Netherlands)

    Zhou, Y.L.; Ma, S.Y.; Liu, R.S.; Luehr, H.; Doornbos, E.

    2013-01-01

    The controls of merging electrical field, Em, and IMF (interplanetary magnetic field) magnitude, B, on the storm-time changes in upper thermospheric mass density are statistically investigated using GRACE accelerometer observations and the OMNI data of solar wind and IMF for 35 great storms during

  7. The storm-time ring current: a statistical analysis at two widely separated low-latitude stations

    Directory of Open Access Journals (Sweden)

    P. Francia

    2004-11-01

    Full Text Available We conducted a statistical analysis of the geomagnetic field variations during the storm main phase at two low-latitude stations, separated by several hours in magnetic local time, in order to investigate the asymmetry and longitudinal extent of the storm-time ring current. The results show evidence for an asymmetric current which typically extends from evening to noon and, during moderate solar wind electric field conditions, up to the early morning, confirming the important role of the magnetospheric convection in the ring current energization. We also analyzed a possible relationship between the local current intensity during the storm main phase and the substorm activity observed at different time delays τ with respect to the storm onset. The results show a significant anticorrelation for τ =-1h, indicating that if the substorm activity is high just before the storm, a weaker ring current develops.

  8. Effect of anomalous transport coefficients on the thermal structure of the storm time auroral ionosphere

    International Nuclear Information System (INIS)

    Fontheim, E.G.; Ong, R.S.B.; Roble, R.G.; Mayr, H.G.; Hoegy, W.H.; Baron, M.J.; Wickwar, V.B.

    1978-01-01

    By analyzing an observed storm time auroral electron temperature profile it is shown that anomalous transport effects strongly influence the thermal structure of the disturbed auroral ionosphere. Such anomalous transport effects are a consequence of plasma turbulence, the existence of which has been established by a large number of observations in the auroral ionosphere. The electron and composite ion energy equations are solved with anomalous electron thermal conductivity and parallel electrical resistivity coefficients. The solutions are parameterized with respect to a phenomenological altitude-dependent anomaly coefficient A and are compared with an observed storm time electron temperature profile above Chatanika. The calculated temperature profile for the classical case (A=1)disagrees considerably with the measured profile over most of the altitude range up to 450km. It is shown that an anomaly coefficient with a sharp peak of the order of 10 4 centered aroung the F 2 peak is consistent with observations

  9. The Role of Ionospheric O+ in Forming the Storm-time Ring Current

    Science.gov (United States)

    Kistler, L. M.; Mouikis, C.; Menz, A.; Bingham, S.

    2017-12-01

    During storm times, the particle pressure that creates the storm-time ring current in the inner magnetosphere can be dominated by O+. This is surprising, as the immediate source for the ring current is the nightside plasma sheet, and O+ is usually not the dominant species in the plasma sheet. In this talk we examine the many factors that lead to this result. The O+ outflow is enhanced during geomagnetically active times. The transport paths of O+ and H+ are different, such that the O+ that reaches the near-earth plasma sheet is more energetic than H+. The source spectrum in the near-earth plasma sheet can be harder for O+ than for H+, perhaps due to substorm injections, so that the more energetic plasma has a higher O+/H+ ratio. And finally the plasma sheet O+ can be more abundant towards the beginning of the storm, when the convection is largest, so the enhanced O+ is brought the deepest into the inner magnetosphere. We will discuss the interrelationships between these different effects as well as the ways in which O+ itself may influence the system.

  10. The plasmasheet H+ and O+ contribution on the storm time ring current

    Science.gov (United States)

    Mouikis, C.; Bingham, S.; Kistler, L. M.; Spence, H. E.; Gkioulidou, M.; Claudepierre, S. G.; Farrugia, C. J.

    2015-12-01

    The source population of the storm time ring current is the night side plasma sheet. We use Van Allen Probes and Cluster observations to determine the contribution of the convecting plasma sheet H+ and O+ particles in the storm time development of the ring current. Using the Volland-Stern model with a dipole magnetic field together with the identification of the observed energy cutoffs in the particle spectra, we specify the pressure contributed by H+ and O+ populations that are on open drift paths vs. the pressure contributed by the trapped populations, for different local times. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L~2 and their pressure compares to the local magnetic field pressure as deep as L~3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current.

  11. Unexpected storm-time nightside plasmaspheric density enhancement at low L shell

    Science.gov (United States)

    Chu, X.; Bortnik, J.; Denton, R. E.; Yue, C.

    2017-12-01

    We have developed a three-dimensional dynamic electron density (DEN3D) model in the inner magnetosphere using a neural network approach. The DEN3D model can provide spatiotemporal distribution of the electron density at any location and time that spacecraft observations are not available. Given DEN3D's good performance in predicting the structure and dynamic evolution of the plasma density, the salient features of the DEN3D model can be used to gain further insight into the physics. For instance, the DEN3D models can be used to find unusual phenomena that are difficult to detect in observations or simulations. We report, for the first time, an unexpected plasmaspheric density increase at low L shell regions on the nightside during the main phase of a moderate storm during 12-16 October 2004, as opposed to the expected density decrease due to storm-time plasmaspheric erosion. The unexpected density increase is first discovered in the modeled electron density distribution using the DEN3D model, and then validated using in-situ density measurements obtained from the IMAGE satellite. The density increase was likely caused by increased earthward transverse field plasma transport due to enhanced nightside ExB drift, which coincided with enhanced solar wind electric field and substorm activity. This is consistent with the results of physics-based simulation SAMI3 model which show earthward enhanced plasma transport and electron density increase at low L shells during storm main phase.

  12. Storm Time Variation of Radiative Cooling by Nitric Oxide as Observed by TIMED-SABER and GUVI

    Science.gov (United States)

    Bharti, Gaurav; Sunil Krishna, M. V.; Bag, T.; Jain, Puneet

    2018-02-01

    The variation of O/N2 (reference to N2 column density 1017 cm-2) and nitric oxide radiative emission flux exiting the thermosphere have been studied over the Northern Hemisphere during the superstorm event of 7-12 November 2004. The data have been obtained from Global Ultraviolet Imager (GUVI) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the National Aeronautics and Space Administration (NASA)'s Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite. The NO radiative flux is observed to show an anti-correlation with O/N2 on a global scale. Both NO radiative flux and O/N2 ratio show equatorward motion with maximum penetration in western longitude sectors. A local variation of O, O2, and N2 densities have been calculated using NRLMSISE-00 model over a midlatitude location (55°N,180°E). On a local scale, model calculated O/O2 and O/N2 ratios are found to follow the observations made by GUVI. The collisional excitation of NO with atomic oxygen is the most dominant process for the total cooling rate. The SABER-retrieved NO cooling rate (CR) at a local site suggests an enhancement during the storm period with the peak emission rate closely correlated to the progression of the storm. The peak emission altitude of NO CR moves upward during the main phase of the storm. The NO abundance has been calculated by using cooling rate and Nitric Oxide Empirical Model (NOEM) model. Both these suggest a vary large (3-15 times) increase in NO density during the storm, which is required to account the changes in NO radiative flux. A similar kind of enhancement in NO abundance is also noticed in Student Nitric Oxide Explorer observations during intense geomagnetic storms.

  13. Energetic ion injection and formation of the storm-time symmetric ring current

    Directory of Open Access Journals (Sweden)

    L. Xie

    2006-12-01

    Full Text Available An extensive study of ring current injection and intensification of the storm-time ring current is conducted with three-dimensional (3-D test particle trajectory calculations (TPTCs. The TPTCs reveal more accurately the process of ring current injection, with the main results being the following: (1 an intense convection electric field can effectively energize and inject plasma sheet particles into the ring current region within 1–3 h. (2 Injected ions often follow chaotic trajectories in non-adiabatic regions, which may have implications in storm and ring current physics. (3 The shielding electric field, which arises as a consequence of enhanced convection and co-exists with the injection and convection electric field, may cause the original open trajectories of injected ions with higher energy to change into closed ones, thus playing a role in the formation of the symmetric ring current.

  14. Storm-time electron flux precipitation in the inner radiation belt caused by wave-particle interactions

    Directory of Open Access Journals (Sweden)

    H. Tadokoro

    2009-04-01

    Full Text Available It has been believed that electrons in the inner belt do not show the dynamical variation during magnetic storms except for great magnetic storms. However, Tadokoro et al. (2007 recently disclosed that low-altitude electrons in the inner belt frequently show flux variations during storms (Storm Time inner belt Electron Enhancement at the Low altitude (STEEL. This paper investigates a possible mechanism explaining STEEL during small and moderate storms, and shows that it is caused not by radial transport processes but by pitch angle scattering through wave-particle interactions. The waves related to wave-particle interactions are attributed to be banded whistler mode waves around 30 kHz observed in the inner magnetosphere by the Akebono satellite. The estimated pitch angle distribution based on a numerical calculation is roughly consistent with the observed results.

  15. Space Weather Research in the Equatorial Region: A Philosophical Reinforcement

    Science.gov (United States)

    Chukwuma, Victor; Odunaike, Rasaki; Laoye, John

    Investigations using radio waves reflected from the ionosphere, at high-and mid-latitudes indicate that ionospheric absorption can strongly increase following geomagnetic storms; which appears to suggest some definite relationship between ionospheric radio wave absorption and geomagnetic storms at these latitudes. However, corresponding earlier studies in the equatorial region did not appear to show any explicit relationship between ionospheric radio wave absorption and geomagnetic storm activity. This position appeared acceptable to the existing scientific paradigm, until in an act of paradigm shift, by a change of storm selection criteria, some more recent space weather investigations in the low latitudes showed that ionospheric radio wave absorption in the equatorial region clearly increases after intense storms. Given that these results in the equatorial region stood against the earlier results, this paper presently attempts to highlight their philosophical underpinning and posit that they constitute a scientific statement.

  16. Planetary gyre, time-dependent eddies, torsional waves, and equatorial jets at the Earth's core surface

    DEFF Research Database (Denmark)

    Gillet, N.; Jault, D.; Finlay, Chris

    2015-01-01

    between the magnetic field and subdecadal nonzonal motions within the fluid outer core. Both the zonal and the more energetic nonzonal interannual motions were particularly intense close to the equator (below 10∘ latitude) between 1995 and 2010. We revise down the amplitude of the decade fluctuations......We report a calculation of time-dependent quasi-geostrophic core flows for 1940–2010. Inverting recursively for an ensemble of solutions, we evaluate the main source of uncertainties, namely, the model errors arising from interactions between unresolved core surface motions and magnetic fields....... Temporal correlations of these uncertainties are accounted for. The covariance matrix for the flow coefficients is also obtained recursively from the dispersion of an ensemble of solutions. Maps of the flow at the core surface show, upon a planetary-scale gyre, time-dependent large-scale eddies...

  17. Methodology for Time-Domain Estimation of Storm-Time Electric Fields Using the 3D Earth Impedance

    Science.gov (United States)

    Kelbert, A.; Balch, C. C.; Pulkkinen, A. A.; Egbert, G. D.; Love, J. J.; Rigler, E. J.; Fujii, I.

    2016-12-01

    Magnetic storms can induce geoelectric fields in the Earth's electrically conducting interior, interfering with the operations of electric-power grid industry. The ability to estimate these electric fields at Earth's surface in close to real-time and to provide local short-term predictions would improve the ability of the industry to protect their operations. At any given time, the electric field at the Earth's surface is a function of the time-variant magnetic activity (driven by the solar wind), and the local electrical conductivity structure of the Earth's crust and mantle. For this reason, implementation of an operational electric field estimation service requires an interdisciplinary, collaborative effort between space science, real-time space weather operations, and solid Earth geophysics. We highlight in this talk an ongoing collaboration between USGS, NOAA, NASA, Oregon State University, and the Japan Meteorological Agency, to develop algorithms that can be used for scenario analyses and which might be implemented in a real-time, operational setting. We discuss the development of a time domain algorithm that employs discrete time domain representation of the impedance tensor for a realistic 3D Earth, known as the discrete time impulse response (DTIR), convolved with the local magnetic field time series, to estimate the local electric field disturbances. The algorithm is validated against measured storm-time electric field data collected in the United States and Japan. We also discuss our plans for operational real-time electric field estimation using 3D Earth impedances.

  18. Distortions of the magnetic field by storm-time current systems in Earth's magnetosphere

    Directory of Open Access Journals (Sweden)

    N. Yu. Ganushkina

    2010-01-01

    Full Text Available Magnetic field and current system changes in Earth's inner magnetosphere during storm times are studied using two principally different modeling approaches: on one hand, the event-oriented empirical magnetic field model, and, on the other, the Space Weather Modeling Framework (SWMF built around a global MHD simulation. Two storm events, one moderate storm on 6–7 November 1997 with Dst minimum about −120 nT and one intense storm on 21–23 October 1999 with Dst minimum about −250 nT were modeled. Both modeling approaches predicted a large ring current (first partial, later symmetric contribution to the magnetic field perturbation for the intense storm. For the moderate storm, the tail current plays a dominant role in the event-oriented model results, while the SWMF results showed no strong tail current in the main phase, which resulted in a poorly timed storm peak relative to the observations. These results imply that the the development of a ring current depends on a strong force to inject the particles deep into the inner magnetosphere, and that the tail current is an important external source for the distortions of the inner magnetospheric magnetic field for both storms. Neither modeling approach was able to reproduce all the variations in the Bx and By components observed at geostationary orbit by GOES satellites during these two storms: the magnetopause current intensifications are inadequate, and the field-aligned currents are not sufficiently represented. While the event-oriented model reproduces rather well the Bz component at geostationary orbit, including the substorm-associated changes, the SWMF field is too dipolar at these locations. The empirical model is a useful tool for validation of the first-principle based models such as the SWMF.

  19. Climatology of the Occurrence Rate and Amplitudes of Local Time Distinguished Equatorial Plasma Depletions Observed by Swarm Satellite

    Science.gov (United States)

    Wan, Xin; Xiong, Chao; Rodriguez-Zuluaga, Juan; Kervalishvili, Guram N.; Stolle, Claudia; Wang, Hui

    2018-04-01

    In this study, we developed an autodetection technique for the equatorial plasma depletions (EPDs) and their occurrence and depletion amplitudes based on in situ electron density measurements gathered by Swarm A satellite. For the first time, comparisons are made among the detected EPDs and their amplitudes with the loss of Global Positioning System (GPS) signal of receivers onboard Swarm A, and the Swarm Level-2 product, Ionospheric Bubble Index (IBI). It has been found that the highest rate of EPD occurrence takes place generally between 2200 and 0000 magnetic local time (MLT), in agreement with the IBI. However, the largest amplitudes of EPD are detected earlier at about 1900-2100 MLT. This coincides with the moment of higher background electron density and the largest occurrence of GPS signal loss. From a longitudinal perspective, the higher depletion amplitude is always witnessed in spatial bins with higher background electron density. At most longitudes, the occurrence rate of postmidnight EPDs is reduced compared to premidnight ones; while more postmidnight EPDs are observed at African longitudes. CHAMP observations confirm this point regardless of high or low solar activity condition. Further by comparing with previous studies and the plasma vertical drift velocity from ROCSAT-1, we suggest that while the F region vertical plasma drift plays a key role in dominating the occurrence of EPDs during premidnight hours, the postmidnight EPDs are the combined results from the continuing of former EPDs and newborn EPDs, especially during June solstice. And these newborn EPDs during postmidnight hours seem to be less related to the plasma vertical drift.

  20. Solar noise storms

    CERN Document Server

    Elgaroy, E O

    2013-01-01

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

  1. Dependence of ionospheric response on the local time of sudden commencement and the intensity of geomagnetic storms

    International Nuclear Information System (INIS)

    Balan, N.; Rao, P.B.

    1990-01-01

    A study has been designed specifically to investigate the dependence of the ionospheric response on the time of occurrence of sudden commencement (SC) and the intensity of the magnetic storms for a low- and a mid-latitude station by considering total electron content and peak electron density data for more than 60 SC-type geomagnetic storms. The nature of the response, whether positive or negative, is found to be determined largely by the local time of SC, although there is a local time shift of about six hours between low- and mid-latitudes. The time delays associated with the positive responses are low for daytime SCs and high for night-time SCs, whereas the opposite applies for negative responses. The time delays are significantly shorter for mid-latitudes than for low-latitudes and, at both latitudes, are inversely related to the intensity of the storm. There is a positive correlation between the intensity of the ionospheric response and that of the magnetic storm, the correlation being greater at mid-latitudes. The results are discussed in the light of the possible processes which might contribute to the storm-associated ionospheric variations. (author)

  2. Movie-maps of low-latitude magnetic storm disturbance

    Science.gov (United States)

    Love, Jeffrey J.; Gannon, Jennifer L.

    2010-06-01

    We present 29 movie-maps of low-latitude horizontal-intensity magnetic disturbance for the years 1999-2006: 28 recording magnetic storms and 1 magnetically quiescent period. The movie-maps are derived from magnetic vector time series data collected at up to 25 ground-based observatories. Using a technique similar to that used in the calculation of Dst, a quiet time baseline is subtracted from the time series from each observatory. The remaining disturbance time series are shown in a polar coordinate system that accommodates both Earth rotation and the universal time dependence of magnetospheric disturbance. Each magnetic storm recorded in the movie-maps is different. While some standard interpretations about the storm time equatorial ring current appear to apply to certain moments and certain phases of some storms, the movie-maps also show substantial variety in the local time distribution of low-latitude magnetic disturbance, especially during storm commencements and storm main phases. All movie-maps are available at the U.S. Geological Survey Geomagnetism Program Web site (http://geomag.usgs.gov).

  3. Multidecadal Scale Detection Time for Potentially Increasing Atlantic Storm Surges in a Warming Climate

    Science.gov (United States)

    Lee, Benjamin Seiyon; Haran, Murali; Keller, Klaus

    2017-10-01

    Storm surges are key drivers of coastal flooding, which generate considerable risks. Strategies to manage these risks can hinge on the ability to (i) project the return periods of extreme storm surges and (ii) detect potential changes in their statistical properties. There are several lines of evidence linking rising global average temperatures and increasingly frequent extreme storm surges. This conclusion is, however, subject to considerable structural uncertainty. This leads to two main questions: What are projections under various plausible statistical models? How long would it take to distinguish among these plausible statistical models? We address these questions by analyzing observed and simulated storm surge data. We find that (1) there is a positive correlation between global mean temperature rise and increasing frequencies of extreme storm surges; (2) there is considerable uncertainty underlying the strength of this relationship; and (3) if the frequency of storm surges is increasing, this increase can be detected within a multidecadal timescale (≈20 years from now).

  4. Development of a Geomagnetic Storm Correction to the International Reference Ionosphere E-Region Electron Densities Using TIMED/SABER Observations

    Science.gov (United States)

    Mertens, C. J.; Xu, X.; Fernandez, J. R.; Bilitza, D.; Russell, J. M., III; Mlynczak, M. G.

    2009-01-01

    Auroral infrared emission observed from the TIMED/SABER broadband 4.3 micron channel is used to develop an empirical geomagnetic storm correction to the International Reference Ionosphere (IRI) E-region electron densities. The observation-based proxy used to develop the storm model is SABER-derived NO+(v) 4.3 micron volume emission rates (VER). A correction factor is defined as the ratio of storm-time NO+(v) 4.3 micron VER to a quiet-time climatological averaged NO+(v) 4.3 micron VER, which is linearly fit to available geomagnetic activity indices. The initial version of the E-region storm model, called STORM-E, is most applicable within the auroral oval region. The STORM-E predictions of E-region electron densities are compared to incoherent scatter radar electron density measurements during the Halloween 2003 storm events. Future STORM-E updates will extend the model outside the auroral oval.

  5. Ionospheric effects at low latitudes during the March 22, 1979, geomagnetic storm

    International Nuclear Information System (INIS)

    Fesen, C.G.; Crowley, G.; Roble, R.G.

    1989-01-01

    This paper investigates the response of the equatorial ionosphere to the neutral atmosphere perturbations produced by the magnetic storm of March 22, 1979. A numerical model of the equatorial ionosphere is used to calculate the maximum electron densities and F layer heights associated with a storm-perturbed neutral atmosphere and circulation model. Possible electric field perturbations due to the storm are ignored. The neutral atmosphere and dynamics are simulated by the National Center for Atmospheric Research thermospheric general circulation model (TGCM) for the storm day of March 22, 1979, and the preceding quiet day. The most striking feature of the TGCM storm day simulations is the presence of waves in the neutral composition, wind, and temperature fields which propagate from high latitudes to the equator. The TGCM-calculated fields for the two days are input into a low-latitude ionosphere model which calculates n max and h max between ±20 degree dip latitude. The calculated nighttime 6300-angstrom airglow emission and the altitude profiles of electron concentration are also highly perturbed by the storm. Examination of ionosonde data for March 22, 1979, shows remarkable agreement between the measured and predicted changes in f 0 F 2 and h max near 140 degree W. Poorer agreement near 70 degree W may be due to the neglect of electric field perturbations and the approximations inherent in the modeling. The results of these simulations indicate that the major factor influencing the storm time ionospheric behavior in this case is the neutral wind

  6. Empirical Storm-Time Correction to the International Reference Ionosphere Model E-Region Electron and Ion Density Parameterizations Using Observations from TIMED/SABER

    Science.gov (United States)

    Mertens, Christoper J.; Winick, Jeremy R.; Russell, James M., III; Mlynczak, Martin G.; Evans, David S.; Bilitza, Dieter; Xu, Xiaojing

    2007-01-01

    The response of the ionospheric E-region to solar-geomagnetic storms can be characterized using observations of infrared 4.3 micrometers emission. In particular, we utilize nighttime TIMED/SABER measurements of broadband 4.3 micrometers limb emission and derive a new data product, the NO+(v) volume emission rate, which is our primary observation-based quantity for developing an empirical storm-time correction the IRI E-region electron density. In this paper we describe our E-region proxy and outline our strategy for developing the empirical storm model. In our initial studies, we analyzed a six day storm period during the Halloween 2003 event. The results of this analysis are promising and suggest that the ap-index is a viable candidate to use as a magnetic driver for our model.

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

    International Nuclear Information System (INIS)

    Akasofu, S.I.

    1981-01-01

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

  8. Geomagnetic storms

    International Nuclear Information System (INIS)

    McNamara, A.G.

    1980-01-01

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

  9. Correlations between Geomagnetic Disturbances and Field-Aligned Currents during the 22-29 July 2004 Storm Time Interval

    Science.gov (United States)

    Hood, R.; Woodroffe, J. R.; Morley, S.; Aruliah, A. L.

    2017-12-01

    Using the CHAMP fluxgate magnetometer to calculate field-aligned current (FAC) densities and magnetic latitudes, with SuperMAG ground magnetometers analogously providing ground geomagnetic disturbances (GMD) magnetic perturbations and latitudes, we probe FAC locations and strengths as predictors of GMD locations and strengths. We also study the relationships between solar wind drivers and global magnetospheric activity, and both FACs and GMDs using IMF Bz and the Sym-H index. We present an event study of the 22-29 July 2004 storm time interval, which had particularly large GMDs given its storm intensity. We find no correlation between FAC and GMD magnitudes, perhaps due to CHAMP orbit limitations or ground magnetometer coverage. There is, however, a correlation between IMF Bz and nightside GMD magnitudes, supportive of their generation via tail reconnection. IMF Bz is also correlated with dayside FAC and GMD magnetic latitudes, indicating solar wind as an initial driver. The ring current influence increases during the final storm, with improved correlations between the Sym-H index and both FAC magnetic latitudes and GMD magnitudes. Sym-H index correlations may only be valid for higher intensity storms; a statistical analysis of many storms is needed to verify this.

  10. Development of an Agent Based Model to Estimate and Reduce Time to Restoration of Storm Induced Power Outages

    Science.gov (United States)

    Walsh, T.; Layton, T.; Mellor, J. E.

    2017-12-01

    Storm damage to the electric grid impacts 23 million electric utility customers and costs US consumers $119 billion annually. Current restoration techniques rely on the past experiences of emergency managers. There are few analytical simulation and prediction tools available for utility managers to optimize storm recovery and decrease consumer cost, lost revenue and restoration time. We developed an agent based model (ABM) for storm recovery in Connecticut. An ABM is a computer modeling technique comprised of agents who are given certain behavioral rules and operate in a given environment. It allows the user to simulate complex systems by varying user-defined parameters to study emergent, unpredicted behavior. The ABM incorporates the road network and electric utility grid for the state, is validated using actual storm event recoveries and utilizes the Dijkstra routing algorithm to determine the best path for repair crews to travel between outages. The ABM has benefits for both researchers and utility managers. It can simulate complex system dynamics, rank variable importance, find tipping points that could significantly reduce restoration time or costs and test a broad range of scenarios. It is a modular, scalable and adaptable technique that can simulate scenarios in silico to inform emergency managers before and during storm events to optimize restoration strategies and better manage expectations of when power will be restored. Results indicate that total restoration time is strongly dependent on the number of crews. However, there is a threshold whereby more crews will not decrease the restoration time, which depends on the total number of outages. The addition of outside crews is more beneficial for storms with a higher number of outages. The time to restoration increases linearly with increasing repair time, while the travel speed has little overall effect on total restoration time. Crews traveling to the nearest outage reduces the total restoration time

  11. Storm-time Convection Dynamics Viewed from Optical Auroras: from Streamer to Patchy Pulsating Aurora

    Science.gov (United States)

    Yang, B.; Donovan, E.; Liang, J.; Grono, E.

    2016-12-01

    In a series of statistical and event studies we have demonstrated that the motion of patches in regions of Patchy Pulsating Aurora (PPA) is very close to if not exactly convection. Thus, 2D maps of PPA motion provides us the opportunity to remote sense magnetospheric convection with relatively high space and time resolution, subject to uncertainties associated with mapping between the ionosphere and magnetosphere. In this study, we use THEMIS ASI aurora observations (streamers and patchy pulsating aurora) combined with SuperDARN convection measurements, Swarm ion drift velocity measurements, and RBSP electric field measurements to explore the convection dynamics in storm time. From 0500 UT to 0600 UT on March 19 2015, convection observations across 5 magnetic local time (MLT) inferred from the motion of PPA patches and SuperDARN measurements show that a westward SAPS (Subauroral Polarized Streams) enhancement occurs after an auroral streamer. This suggests that plasma sheet fast flows can affect the inner magnetospheric convection, and possibly trigger very fast flows in the inner magnetosphere.

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

    Directory of Open Access Journals (Sweden)

    H. Gleisner

    1996-07-01

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

  13. Effects of solar eclipse on the electrodynamical processes of the equatorial ionosphere: a case study during 11 August 1999 dusk time total solar eclipse over India

    Directory of Open Access Journals (Sweden)

    R. Sridharan

    Full Text Available The effects on the electrodynamics of the equatorial E- and F-regions of the ionosphere, due to the occurrence of the solar eclipse during sunset hours on 11 August 1999, were investigated in a unique observational campaign involving ground based ionosondes, VHF and HF radars from the equatorial location of Trivandrum (8.5° N; 77° E; dip lat. 0.5° N, India. The study revealed the nature of changes brought about by the eclipse in the evening time E- and F-regions in terms of (i the sudden intensification of a weak blanketing ES-layer and the associated large enhancement of the VHF backscattered returns, (ii significant increase in h' F immediately following the eclipse and (iii distinctly different spatial and temporal structures in the spread-F irregularity drift velocities as observed by the HF radar. The significantly large enhancement of the backscattered returns from the E-region coincident with the onset of the eclipse is attributed to the generation of steep electron density gradients associated with the blanketing ES , possibly triggered by the eclipse phenomena. The increase in F-region base height immediately after the eclipse is explained as due to the reduction in the conductivity of the conjugate E-region in the path of totality connected to the F-region over the equator along the magnetic field lines, and this, with the peculiar local and regional conditions, seems to have reduced the E-region loading of the F-region dynamo, resulting in a larger post sunset F-region height (h' F rise. These aspects of E-and F-region behaviour on the eclipse day are discussed in relation to those observed on the control day.

    Key words. Ionosphere (electric fields and currents; equatorial ionosphere; ionospheric irregularities

  14. Effects of solar eclipse on the electrodynamical processes of the equatorial ionosphere: a case study during 11 August 1999 dusk time total solar eclipse over India

    Directory of Open Access Journals (Sweden)

    R. Sridharan

    2002-12-01

    Full Text Available The effects on the electrodynamics of the equatorial E- and F-regions of the ionosphere, due to the occurrence of the solar eclipse during sunset hours on 11 August 1999, were investigated in a unique observational campaign involving ground based ionosondes, VHF and HF radars from the equatorial location of Trivandrum (8.5° N; 77° E; dip lat. 0.5° N, India. The study revealed the nature of changes brought about by the eclipse in the evening time E- and F-regions in terms of (i the sudden intensification of a weak blanketing ES-layer and the associated large enhancement of the VHF backscattered returns, (ii significant increase in h' F immediately following the eclipse and (iii distinctly different spatial and temporal structures in the spread-F irregularity drift velocities as observed by the HF radar. The significantly large enhancement of the backscattered returns from the E-region coincident with the onset of the eclipse is attributed to the generation of steep electron density gradients associated with the blanketing ES , possibly triggered by the eclipse phenomena. The increase in F-region base height immediately after the eclipse is explained as due to the reduction in the conductivity of the conjugate E-region in the path of totality connected to the F-region over the equator along the magnetic field lines, and this, with the peculiar local and regional conditions, seems to have reduced the E-region loading of the F-region dynamo, resulting in a larger post sunset F-region height (h' F rise. These aspects of E-and F-region behaviour on the eclipse day are discussed in relation to those observed on the control day.Key words. Ionosphere (electric fields and currents; equatorial ionosphere; ionospheric irregularities

  15. Controlling of merging electric field and IMF magnitude on storm-time changes in thermospheric mass density

    Directory of Open Access Journals (Sweden)

    Y. L. Zhou

    2013-01-01

    Full Text Available The controls of merging electrical field, Em, and IMF (interplanetary magnetic field magnitude, B, on the storm-time changes in upper thermospheric mass density are statistically investigated using GRACE accelerometer observations and the OMNI data of solar wind and IMF for 35 great storms during 2002–2006. It reveals the following: (1 The correlation coefficients between the air mass density changes and the parameters of Em and B are generally larger at lower latitudes than at higher latitudes, and larger in noon and midnight sectors than in dawn and dusk. (2 The most likely delay time (MLDT of mass density changes in respect to Em is about 1.5 h (4.5 h at high (low latitudes, having no distinct local time dependence, while it is 6 h at middle latitudes in all the local time sectors except for noon, which is longer than at low latitudes. A similar fact of longer delay time at mid-latitude is also seen for B. The MLDTs for B at various latitudes are all local time dependent distinctly with shorter delay time in noon/midnight sector and larger in dawn/dusk. Despite of widely spread of the delay time, IMF B exhibits still larger correlation coefficients with mass density changes among the interplanetary parameters. (3 The linear control factor of B on the density changes increases for large B, in contrast to somewhat saturation trend for larger Em. (4 The influence of B and Em on the mass densities shows different behavior for different types of storms. The influence intensity of Em is much stronger for CIR-driven than for CME-driven storm, while it is not so distinct for B. On the local time asymmetry of the influence, both Em and B have largest influence at noon sector for CME-driven storms, while an obviously larger intensification of the influence is found in dawn/dusk sector during CIR storms, especially for parameter Em.

  16. Magnetospheric signature of some F layer positive storms

    International Nuclear Information System (INIS)

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

    1981-01-01

    Calculations using a self-consistent model of the global thermosphere-ionosphere system perturbed by high-latitude thermospheric heating show that the resultant electron density disturbances within the mid-latitude F layer can propagate upward along magnetic field lines to the equator. The F layer disturbances described by the model calculations correspond to the evolution of enhancements or reductions in electron density that is called the positive or negative phase of an F layer storm. We deduce that the positive phase of dayside F layer storms is initiated when high-latitude thermospheric heating generates equatorward winds. These winds raise the mid-latitude F layer along the geomagnetic field B through momentum transfer from neutral atoms to F layer ons that pull electrons with them. For Lapprox.3 or less the upward movement of ionospheric plasma results in ionization increases at all altitudes along B from the F2 maximum to the equator. An increase in the average magnitude of the equatorial dawn-dusk magnetospheric electric field retards the dayside development of a positive storm phase by drifting plasma away from mid-latitude field lines along which the electron density is increasing. During an F layer storm in June 1972, instruments on Explorer 45 and Ariel 4 detected dayside electron density enhancements simultaneously at 550 km over mid-latitudes and near the equatorial plane in the magnetosphere. These in situ measurements support the model prediction that disturbances in the magnetospheric plasma near the equator can arise through interactions occuring at lower altitudes along a magnetic field line. Our study demonstrates that some storm time enhancements of dayside magnetospheric plasma near Lapprox.2--3 may be signatures of the positive phase of an F layer storm

  17. St. Patrick's Day 2015 geomagnetic storm analysis based on Real Time Ionosphere Monitoring

    Science.gov (United States)

    García-Rigo, Alberto

    2017-04-01

    Ionosphere Monitoring (RTIM) is a new Working Group within the International Association of Geodesy (IAG) Sub-Commission 4.3 "Atmosphere Remote Sensing". The complementary expertise of the participating research groups allows to analyse the ionospheric behaviour from a broad perspective, taking benefit of comparing multiple independent real time and near real time ionospheric approaches. In this context, a detailed analysis will be presented for the days in March, 2015 surrounding St. Patrick's Day 2015 geomagnetic storm, based on the existing ionospheric models (global or regional) within the group, which are mainly based on Global Navigation Satellite Systems (GNSS) and ionosonde data. For this purpose, a variety of ionospheric parameters will be considered, including Total Electron Content (TEC), F2 layer critical frequency (foF2), F2 layer peak (hmF2), bottomside half-thickness (B0) and ionospheric disturbance W-index. Also, ionospheric high-frequency perturbations such as Travelling Ionospheric Disturbances (TIDs), scintillations and the impact of solar flares facing the Earth will be presented to derive a clear picture of the ionospheric dynamics. Among other sources of information to take part in the comparisons, there will be (1) scintillation results -from MONITOR ESA/ESTEC-funded project- derived by means of S4 index and Sigma Phi (IEEA), specially significant in the African sector and European high latitudes, (2) dynamics of the global maps of W-index with 1h resolution derived from JPL Global Ionospheric Maps (GIMs; IZMIRAN), (3) deviations from expected quiet-time behavior analysed in terms of foF2, hmF2, B0 and B1 based on IRTAM and GIRO network of digisondes (Lowell), showing F2 layer peculiar changes due to the storm, (4) statistics based on the median of the VTEC for the 15 previous days considering VTEC european regional maps (ROB), (5) time series of VTEC data that are derived by running the NRT ionosphere model of DGFI-TUM in offline mode, which show

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

    Science.gov (United States)

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

    2017-12-01

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

  19. A comparative study on chaoticity of equatorial/low latitude ionosphere over Indian subcontinent during geomagnetically quiet and disturbed periods

    Directory of Open Access Journals (Sweden)

    K. Unnikrishnan

    2010-12-01

    Full Text Available In the present study, the latitudinal aspect of chaotic behaviour of ionosphere during quiet and storm periods are analyzed and compared by using GPS TEC time series measured at equatorial trough, crest and outside crest stations over Indian subcontinent, by employing the chaotic quantifiers like Lyapunov exponent (LE, correlation dimension (CD, entropy and nonlinear prediction error (NPE. It is observed that the values of LE are low for storm periods compared to those of quiet periods for all the stations considered here. The lowest value of LE is observed at the trough station, Agatti (2.38° N, Geomagnetically, and highest at crest station, Mumbai (10.09° N, Geomagnetically for both quiet and storm periods. The values of correlation dimension computed for TEC time series are in the range 2.23–2.74 for quiet period, which indicate that equatorial ionosphere may be described with three variables during quiet period. But the crest station Mumbai shows a higher value of CD (3.373 during storm time, which asserts that four variables are necessary to describe the system during storm period. The values of non linear prediction error (NPE are lower for Agatti (2.38° N, Geomagnetically and Jodhpur (18.3° N, Geomagnetically, during storm period, compared to those of quiet period, mainly because of the predominance of non linear aspects during storm periods The surrogate data test is carried out and on the basis of the significance of difference of the original data and surrogates for various aspects, the surrogate data test rejects the null hypothesis that the time series of TEC during storm and quiet times represent a linear stochastic process. It is also observed that using state space model, detrended TEC can be predicted, which reasonably reproduces the observed data. Based on the values of the above quantifiers, the features of chaotic behaviour of equatorial trough crest and outside the crest regions of ionosphere during geomagnetically

  20. Predictions of barrier island berm evolution in a time-varying storm climatology

    Science.gov (United States)

    Plant, Nathaniel G.; Flocks, James; Stockdon, Hilary F.; Long, Joseph W.; Guy, Kristy K.; Thompson, David M.; Cormier, Jamie M.; Smith, Christopher G.; Miselis, Jennifer L.; Dalyander, P. Soupy

    2014-01-01

    Low-lying barrier islands are ubiquitous features of the world's coastlines, and the processes responsible for their formation, maintenance, and destruction are related to the evolution of smaller, superimposed features including sand dunes, beach berms, and sandbars. The barrier island and its superimposed features interact with oceanographic forces (e.g., overwash) and exchange sediment with each other and other parts of the barrier island system. These interactions are modulated by changes in storminess. An opportunity to study these interactions resulted from the placement and subsequent evolution of a 2 m high sand berm constructed along the northern Chandeleur Islands, LA. We show that observed berm length evolution is well predicted by a model that was fit to the observations by estimating two parameters describing the rate of berm length change. The model evaluates the probability and duration of berm overwash to predict episodic berm erosion. A constant berm length change rate is also predicted that persists even when there is no overwash. The analysis is extended to a 16 year time series that includes both intraannual and interannual variability of overwash events. This analysis predicts that as many as 10 or as few as 1 day of overwash conditions would be expected each year. And an increase in berm elevation from 2 m to 3.5 m above mean sea level would reduce the expected frequency of overwash events from 4 to just 0.5 event-days per year. This approach can be applied to understanding barrier island and berm evolution at other locations using past and future storm climatologies.

  1. Energy and mass dependence of the contribution to storm-time plasma pressure observed by Arase/MEP-i

    Science.gov (United States)

    Kasahara, S.; Keika, K.; Yokota, S.; Hoshino, M.; Seki, K.; Nose, M.; Amano, T.; Yoshizumi, M.; Shinohara, I.

    2017-12-01

    The ring current is mainly controlled by the ion pressure and its spatial gradient. The ion pressure is dominated by ions with energies of a few to a few 100s keV. Oxygen ions of ionospheric origin can be energized in the plasma sheet and/or the inner magnetosphere up to a few tens to a few hundreds of keV. The ionospheric oxygen ions make a significant contribution to the ion pressure during geomagnetically active periods. This paper examines spatial variations and energy-spectral evolution of energetic ( 10 to 200 keV/q) ions during the main phase of a CIR-driven storm on 17 March 2017 (Storm 1) and a CME-driven storm on 27-28 May 2017 (Storm 2). We use ion data from the MEP-i instrument on board the Arase satellite. The instrument measured energetic ions with energies of 5-120 keV/q during Storm 1 and 9-180 keV/q during Storm 2; ion mass/charge was derived from energy and velocity measurements by an electrostatic analyzer and the time-of-flight system, respectively. Below is a brief summary of the MEP-i observations during the two storms. During Storm 1, MEP-i saw high fluxes of >10 keV/q protons and oxygen ions (and possibly other minor ions) at Lm 3.5 around midnight. MEP-i continued to observe high-flux ions until the end of the main phase. Both proton and oxygen ion pressures increased; the O-to-H ratio increased by about an order of magnitude, from 0.02 to 0.2-0.3. The high-flux >10 keV/q ions consisted of clearly different two populations: one dominated by 5-20 keV/q ions, likely originating from pre-existing cold plasma sheet population; and the other with structured dispersion signatures at 30-90 keV/q, likely due to the penetration of ions accelerated in the near-Earth plasma sheet. We found that both populations contributed to the total pressure almost equally. During Storm 2, MEP-i observed proton and oxygen high fluxes in a wide energy range (10-120 keV/q). The pressure increased for both protons and oxygen ions; the O-to-H ratio increased from 0

  2. A time-compressed simulated geomagnetic storm influences the nest-exiting flight angles of the stingless bee Tetragonisca angustula

    Science.gov (United States)

    Esquivel, D. M. S.; Corrêa, A. A. C.; Vaillant, O. S.; de Melo, V. Bandeira; Gouvêa, G. S.; Ferreira, C. G.; Ferreira, T. A.; Wajnberg, E.

    2014-03-01

    Insects have been used as models for understanding animal orientation. It is well accepted that social insects such as honeybees and ants use different natural cues in their orientation mechanism. A magnetic sensitivity was suggested for the stingless bee Schwarziana quadripunctata, based on the observation of a surprising effect of a geomagnetic storm on the nest-exiting flight angles. Stimulated by this result, in this paper, the effects of a time-compressed simulated geomagnetic storm (TC-SGS) on the nest-exiting flight angles of another stingless bee, Tetragonisca angustula, are presented. Under an applied SGS, either on the horizontal or vertical component of the geomagnetic field, both nest-exiting flight angles, dip and azimuth, are statistically different from those under geomagnetic conditions. The angular dependence of ferromagnetic resonance (FMR) spectra of whole stingless bees shows the presence of organized magnetic nanoparticles in their bodies, which indicates this material as a possible magnetic detector.

  3. Equatorial electrojet in the Indian region during the geomagnetic ...

    Indian Academy of Sciences (India)

    1998-11-14

    Nov 14, 1998 ... In the recovery phase of the storm, the electric field due to shielding layer penetrates to equatorial latitudes as an overshielding electric field with opposite polarity, westward during day- side and eastward during night side (Kelley et al. 1979). In addition to the prompt penetration elec- tric fields, there are ...

  4. Severe ionosphere disturbances caused by the sudden response of evening subequatorial ionospheres to geomagnetic storms

    International Nuclear Information System (INIS)

    Tanaka, T.

    1981-01-01

    By monitoring C band beacon signals from geostationary satellites in Japan, we have observed anomalously strong ionospheric scintillations several times during three years from 1978 to 1980. These severe scinitillations occur associated with geomagnetic storms and accompany sudden and intense ionospheric perturbations in the low-latiude region. Through the analysis of these phenomena we have identified a new type of ionospheric disturbances characterized by intensifications of equatorial anomalies and successive severe ionospheric scintillations that extend to the C band range. The events occur only during a limited local time interval after the sunset, when storm time decreases of midlatitude geomagnetic fields in the same meridan take place during the same time interval. From the viewpoint of ionospheric storms, these disturbances precede the occurrence of midlatitude negative phases and storm time depressions of equatorial anomalies to indicate that the cause of the events is different from distrubed thermospheric circulations. The timing and magnitude of substorms at high-latitudes not always correlate with the events. We have concluded that the phenomena are closely related with penetrations toward low-latitudes of electric fields owing to the partial closure of asymmetrical ring currents

  5. Multipoint investigation of the source region of storm-time chorus

    Czech Academy of Sciences Publication Activity Database

    Santolík, Ondřej; Gurnett, D. A.; Pickett, J. S.

    2004-01-01

    Roč. 22, č. 7 (2004), s. 2555-2563 ISSN 0992-7689 R&D Projects: GA MŠk ME 650; GA ČR GA202/03/0832 Institutional research plan: CEZ:AV0Z3042911 Keywords : Magnetospheric physics (waves in plasma, storm s and substorms) * Space plasma physics (waves and instabilities) Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.610, year: 2004

  6. Evidence for storm-time ionospheric ion precipitation in the cusp with magnetosheath energy

    Directory of Open Access Journals (Sweden)

    H. Stenuit

    2004-04-01

    Full Text Available We present evidence for a sporadic precipitation into the north polar cusp of ionospheric O+ and He+ ions accelerated up to the magnetosheath flow speed during a magnetic storm. This is deduced from data obtained on board the Interball-Auroral satellite showing that the energy/charge ratios of the H+, He++, He+ and O+ populations are similar to those of ion masses. These measurements pertain to a very disturbed magnetic period. A storm was in progress with a Dst reaching -149nT during the cusp measurements, while the AE index reached values higher than 1000nT. This result is discussed in terms of ion circulation from the magnetosphere to the magnetosheath and back to the magnetosphere. We suggest that the acceleration of O+ and He+ ions up to a magnetosheath-like velocity is directly linked to the large By component of the IMF.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetosheath; storms and substorms

  7. Intermonsoonal equatorial jets

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.

    , respectively. Hydrographic features and transport computations favour a well developed equatorial jet during both seasons. The net surface eastward and subsurface westward flows are well balanced during the premonsoon transition period and appear...

  8. Decreasing the stable trapping region during geomagnetic storm

    International Nuclear Information System (INIS)

    Mal'tsev, Yu.P.; Feshchenko, E.Yu.

    1998-01-01

    Within the frameworks of the magnetic field model, depending on the solar wind pressure, the B = B s (B s is the magnetic field in the undersolar point) contour behaviour in the equatorial plane is calculated. The boundary of stable trapping in the quiet time is at the distance of 10-11 R E by day and ∼ 7 R E by night. During strong storms this distance may be decreased up 4-5 R E . The calculation results coincide satisfactorily with satellite measurements

  9. Geomagnetic storm effects on GPS based navigation

    Directory of Open Access Journals (Sweden)

    P. V. S. Rama Rao

    2009-05-01

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

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

  10. Coupled storm-time magnetosphere-ionosphere-thermosphere simulations including microscopic ionospheric turbulence

    Science.gov (United States)

    Merkin, V. G.; Wiltberger, M. J.; Zhang, B.; Liu, J.; Wang, W.; Dimant, Y. S.; Oppenheim, M. M.; Lyon, J.

    2017-12-01

    During geomagnetic storms the magnetosphere-ionosphere-thermosphere system becomes activated in ways that are unique to disturbed conditions. This leads to emergence of physical feedback loops that provide tighter coupling between the system elements, often operating across disparate spatial and temporal scales. One such process that has recently received renewed interest is the generation of microscopic ionospheric turbulence in the electrojet regions (electrojet turbulence, ET) that results from strong convective electric fields imposed by the solar wind-magnetosphere interaction. ET leads to anomalous electron heating and generation of non-linear Pedersen current - both of which result in significant increases in effective ionospheric conductances. This, in turn, provides strong non-linear feedback on the magnetosphere. Recently, our group has published two studies aiming at a comprehensive analysis of the global effects of this microscopic process on the magnetosphere-ionosphere-thermosphere system. In one study, ET physics was incorporated in the TIEGCM model of the ionosphere-thermosphere. In the other study, ad hoc corrections to the ionospheric conductances based on ET theory were incorporated in the conductance module of the Lyon-Fedder-Mobarry (LFM) global magnetosphere model. In this presentation, we make the final step toward the full coupling of the microscopic ET physics within our global coupled model including LFM, the Rice Convection Model (RCM) and TIEGCM. To this end, ET effects are incorporated in the TIEGCM model and propagate throughout the system via thus modified TIEGCM conductances. The March 17, 2013 geomagnetic storm is used as a testbed for these fully coupled simulations, and the results of the model are compared with various ionospheric and magnetospheric observatories, including DMSP, AMPERE, and Van Allen Probes. Via these comparisons, we investigate, in particular, the ET effects on the global magnetosphere indicators such as the

  11. Storm Time Global Observations of Large-Scale TIDs From Ground-Based and In Situ Satellite Measurements

    Science.gov (United States)

    Habarulema, John Bosco; Yizengaw, Endawoke; Katamzi-Joseph, Zama T.; Moldwin, Mark B.; Buchert, Stephan

    2018-01-01

    This paper discusses the ionosphere's response to the largest storm of solar cycle 24 during 16-18 March 2015. We have used the Global Navigation Satellite Systems (GNSS) total electron content data to study large-scale traveling ionospheric disturbances (TIDs) over the American, African, and Asian regions. Equatorward large-scale TIDs propagated and crossed the equator to the other side of the hemisphere especially over the American and Asian sectors. Poleward TIDs with velocities in the range ≈400-700 m/s have been observed during local daytime over the American and African sectors with origin from around the geomagnetic equator. Our investigation over the American sector shows that poleward TIDs may have been launched by increased Lorentz coupling as a result of penetrating electric field during the southward turning of the interplanetary magnetic field, Bz. We have observed increase in SWARM satellite electron density (Ne) at the same time when equatorward large-scale TIDs are visible over the European-African sector. The altitude Ne profiles from ionosonde observations show a possible link that storm-induced TIDs may have influenced the plasma distribution in the topside ionosphere at SWARM satellite altitude.

  12. Modeling the dynamics of a storm-time acceleration event: combining MHD effects with wave-particle interactions

    Science.gov (United States)

    Elkington, S. R.; Alam, S. S.; Chan, A. A.; Albert, J.; Jaynes, A. N.; Baker, D. N.; Wiltberger, M. J.

    2017-12-01

    Global simulations of radiation belt dynamics are often undertaken using either a transport formalism (e.g. Fokker-Plank), or via test particle simulations in model electric and magnetic fields. While transport formalisms offer computational efficiency and the ability to deal with a wide range of wave-particle interactions, they typically rely on simplified background fields, and often are limited to empirically-specified stochastic (diffusive) wave-particle interactions. On the other hand, test particle simulations may be carried out in global MHD simulations that include realistic physical effects such as magnetopause shadowing, convection, and substorm injections, but lack the ability to handle physics outside the MHD approximation in the realm of higher frequency (kHz) wave populations.In this work we introduce a comprehensive simulation framework combining global MHD/test particle techniques to provide realistic background fields and radial transport processes, with a Stochastic Differential Equation (SDE) method for addressing high frequency wave-particle interactions. We examine the March 17, 2013 storm-time acceleration period, an NSF-GEM focus challenge event, and use the framework to examine the relative importance of physical effects such as magnetopause shadowing, diffusive and advective transport processes, and wave-particle interactions through the various phases of the storm.

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

    Directory of Open Access Journals (Sweden)

    K. Unnikrishnan

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

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

  14. Local time dependence of the thermal structure in the Venusian equatorial region revealed by Akatsuki radio occultation measurements

    Science.gov (United States)

    Ando, H.; Fukuhara, T.; Takagi, M.; Imamura, T.; Sugimoto, N.; Sagawa, H.

    2017-12-01

    The radio occultation technique is one of the most useful methods to retrieve vertical temperature profiles in planetary atmospheres. Ultra-Stable Oscillator (USO) onboard Venus Climate Orbiter, Akatsuki, enables us to investigate the thermal structure of the Venus atmosphere between about 40-90 km levels. It is expected that 35 temperature profiles will be obtained by the radio occultation measurements of Akatsuki until August 2017. Static stability derived from the temperature profiles shows its local time dependence above the cloud top level at low-latitudes equatorward of 25˚. The vertical profiles of the static stability in the dawn and dusk regions have maxima at 77 km and 82 km levels, respectively. A general circulation model (GCM) for the Venus atmosphere (AFES-Venus) reproduced the thermal structures above the cloud top qualitatively consistent with the radio occultation measurements; the maxima of the static stability are seen both in the dawn and dusk regions, and the local maximum of the static stability in the dusk region is located at a highler level than in the dawn region. Comparing the thermal structures between the radio occultation measurements and the GCM results, it is suggested that the distribution of the static stability above the cloud top could be strongly affected by the diurnal tide. The thermal tide influences on the thermal structure as well as atmospheric motions above the cloud level. In addition, it is shown that zonally averaged zonal wind at about 80 km altitude could be roughly estimated from the radio occultation measurements using the dispersion relation of the internal gravity wave.

  15. Multipoint investigation of the source region of storm-time chorus

    Directory of Open Access Journals (Sweden)

    O. Santolík

    2004-07-01

    Full Text Available In this case study we investigate the source region of whistler-mode chorus located close to the geomagnetic equator at a radial distance of 4.4 Earth radii. We use measurements from the four Cluster spacecraft at separations of less than a few hundreds of km, recorded during the geomagnetic storm of 18 April 2002. The waveforms of the electric field fluctuations were obtained by the WBD instruments in the frequency range 50Hz-9.5kHz. Using these data, we calculate linear and rank correlation coefficients of the frequency averaged power-spectral density measured by the different spacecraft. Those coefficients have been recently shown to decrease with spacecraft separation distance perpendicular to the static magnetic field cchor03 with a characteristic scale length of 100km. We find this characteristic scale varying between 60 and 200km for different data intervals inside the source region. We examine possible explanations for the observed large scatter of the correlation coefficients, and we suggest a simultaneously acting effect of random positions of locations at which the individual chorus wave packets are generated. The statistical properties of the observations are approximately reproduced by a simple 2-D model of the source region, assuming a perpendicular half-width of 35km (approximately one wavelength of the whistler-mode waves for the distribution of power radiated from individual active areas.

  16. Short-Term Forecasting of Urban Storm Water Runoff in Real-Time using Extrapolated Radar Rainfall Data

    DEFF Research Database (Denmark)

    Thorndahl, Søren Liedtke; Rasmussen, Michael R.

    2013-01-01

    Model based short-term forecasting of urban storm water runoff can be applied in realtime control of drainage systems in order to optimize system capacity during rain and minimize combined sewer overflows, improve wastewater treatment or activate alarms if local flooding is impending. A novel onl....... The radar rainfall extrapolation (nowcast) limits the lead time of the system to two hours. In this paper, the model set-up is tested on a small urban catchment for a period of 1.5 years. The 50 largest events are presented....... online system, which forecasts flows and water levels in real-time with inputs from extrapolated radar rainfall data, has been developed. The fully distributed urban drainage model includes auto-calibration using online in-sewer measurements which is seen to improve forecast skills significantly...

  17. Diagnosing the Growth of Equatorial Typhoon Vamei (2001 from an Energy Standpoint

    Directory of Open Access Journals (Sweden)

    Gin-Rong Liu

    2010-01-01

    Full Text Available Surprisingly, on 27 December 2001, a storm named Typhoon Vamei formed near in Singaporean waters. An examination on the SSM/I-derived rainfall rates and air-sea parameters showed that significant higher latent heat release and air-sea energy flux during convective rainfall activities played a key role in the typhoon¡¦s growth. A quantitative analysis revealed that the energy flux from the ocean to the atmosphere and the latent heat release during the rainfall activities both increased significantly during the initial growth stage. However, the values rapidly decreased just before the storm reached typhoon strength. Separately, in contrast to a case that occurred in 1999, the total thermal energy calculated from Typhoon Vamei¡¦s formation was two times higher. Thus, despite a very weak Coriolis force in the equatorial belt, the special terrain of Borneo Island and narrow channel in the equatorial South China Sea caused a Borneo vortex via northeasterly cold surges, together with the accumulated energy was sufficiently strong enough to induce the formation of Typhoon Vamei.

  18. Cooling in the Post-Sunrise Equatorial Topside Ionosphere During the 22-23 June 2015 Superstorm

    Science.gov (United States)

    Stoneback, R.; Hairston, M. R.; Coley, W. R.; Heelis, R. A.

    2015-12-01

    During the recovery phase of the 22-23 June 2015 superstorm multiple DMSP spacecraft observed two separate and short-lived (~ 30 minutes) events of localized cooling in the topside equatorial ionosphere (~840 km) in the post-sunrise region (between 6:15 and 7:30 local time). The ion temperatures dropped from the nominal 2000-3000° observed in these regions to 1000 to 1500°. This cooling effect was not observed on the corresponding duskside equatorial crossings of the DMSP spacecraft during this storm. Further, these cooling events do not normally occur during major storms; no such phenomenon was observed by DMSP during the March 2015 superstorm. Flow data from DMSP and the CINDI instruments on the C/NOFS spacecraft indicate these cooling events are associated with short-lived vertical flows bringing up cooler plasma from lower altitudes. The two cooling events correspond to large northward turnings of the IMF during the storm and these are being explored as a possible trigger mechanism.

  19. Evolution of the ring current during two geomagnetic storms

    International Nuclear Information System (INIS)

    Lui, A.T.Y.; McEntire, R.W.; Krimigis, S.M.

    1987-01-01

    The progressive developments in the radial profiles of the particle pressure, plasma beta, and electric currents of the storm time ring current are investigated with data from the medium energy particle analyzer on the AMPTE Charged Particle Explorer spacecraft. Measurements of ions from 25 keV to 1 MeV, which carry 70--85% of the energy density of the entire ring current population, are used in this work. Two geomagnetic storms in September of 1984 are selected and four traversals of the equatorial ring current region during the course of each storm are studied. It is shown that enhancements in the particle pressure occur initially in the outer region and reach the inner region in the late phase of the storm. Structures suggestive of multiple particle injections are seen in the pressure profile. The leading and trailing edges of the particle injection structures are associated, respectively, with the depressions and enhancements of the westward current densities of the ring current. Plasma beta occasionally increases to values of the order of 1 in some regions of the ring current from prestorm values of the order of 0.1 or less. It is also found that the location of the maximum ring current particle pressure can be several earth radii from where the most intense westward ring current flows. This is a consequence of the dominance of pressure gradient current over the current associated with the magnetic field line curvature and particle anisotropy. copyright American Geophysical Union 1987

  20. Dynamical variability in Saturn Equatorial Atmosphere

    Science.gov (United States)

    Sánchez-Lavega, A.; Pérez-Hoyos, S.; Hueso, R.; Rojas, J. F.; French, R. G.; Grupo Ciencias Planetarias Team

    2003-05-01

    Historical ground-based and recent HST observations show that Saturn's Equatorial Atmosphere is the region where the most intense large-scale dynamical variability took place at cloud level in the planet. Large-scale convective storms (nicknamed the ``Great White Spots") occurred in 1876, 1933 and 1990. The best studied case (the 1990 storm), produced a dramatic change in the cloud aspect in the years following the outburst of September 1990. Subsequently, a new large storm formed in 1994 and from 1996 to 2002 our HST observations showed periods of unusual cloud activity in the southern part of the Equator. This contrast with the aspect observed during the Voyager 1 and 2 encounters in 1980 and 1981 when the Equator was calm, except for some mid-scale plume-like features seen in 1981. Cloud-tracking of the features have revealed a dramatic slow down in the equatorial winds from maximum velocities of ˜ 475 m/s in 1980-1981 to ˜ 275 m/s during 1996-2002, as we have recently reported in Nature, Vol. 423, 623 (2003). We discuss the possibility that seasonal and ring-shadowing effects are involved in generating this activity and variability. Acknowledgements: This work was supported by the Spanish MCYT PNAYA 2000-0932. SPH acknowledges a PhD fellowship from the Spanish MECD and RH a post-doc fellowship from Gobierno Vasco. RGF was supported in part by NASA's Planetary Geology and Geophysics Program NAG5-10197 and STSCI Grant GO-08660.01A.

  1. Pacific Equatorial Transect

    OpenAIRE

    Pälike, Heiko; Nishi, Hiroshi; Lyle, Mitch; Raffi, Isabella; Klaus, Adam; Gamage, Kusali

    2009-01-01

    Integrated Ocean Drilling Program Expedition 320/321, "Pacific Equatorial Age Transect" (Sites U1331–U1338), was designed to recover a continuous Cenozoic record of the paleoequatorial Pacific by coring above the paleoposition of the Equator at successive crustal ages on the Pacific plate. These sediments record the evolution of the paleoequatorial climate system throughout the Cenozoic. As we gained more information about the past movement of plates and when in Earth's history "critical" cli...

  2. Investigation of a strong positive ionospheric storm during geomagnetic disturbances occurred in the Brazilian sector

    Science.gov (United States)

    de Abreu, A. J.; Sahai, Y.; Fagundes, P. R.; de Jesus, R.; Bittencourt, J. A.; Pillat, V. G.

    2012-12-01

    In this paper, we have investigated the responses of the ionospheric F region at equatorial and low latitude regions in the Brazilian sector during the super geomagnetic storm on 15-16 May 2005. The geomagnetic storm reached a minimum Dst of -263 nT at 0900 UT on 15 May. In this paper, we present vertical total electron content (vTEC) and phase fluctuations (in TECU/min) from Global Positioning System (GPS) observations obtained at Belém (BELE), Brasília (BRAZ), Presidente Prudente (UEPP), and Porto Alegre (POAL), Brazil, during the period 14-17 May 2005. Also, we present ionospheric parameters h'F, hpF2, and foF2, using the Canadian Advanced Digital Ionosonde (CADI) obtained at Palmas (PAL) and São José dos Campos (SJC), Brazil, for the same period. The super geomagnetic storm has fast decrease in the Dst index soon after SSC at 0239 UT on 15 May. It is a good possibility of prompt penetration of electric field of magnetospheric origin resulting in uplifting of the F region. The vTEC observations show a trough at BELE and a crest above UEPP, soon after SSC, indicating strengthening of nighttime equatorial anomaly. During the daytime on 15 and 16 May, in the recovery phase, the variations in foF2 at SJC and the vTEC observations, particularly at BRAZ, UEPP, and POAL, show large positive ionospheric storm. There is ESF on the all nights at PAL, in the post-midnight (UT) sector, and phase fluctuations only on the night of 14-15 May at BRAZ, after the SSC. No phase fluctuations are observed at the equatorial station BELE and low latitude stations (BRAZ, UEPP, and POAL) at all other times. This indicates that the plasma bubbles are generated and confined on this magnetically disturbed night only up to the low magnetic latitude and drifted possibly to west.

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

    Science.gov (United States)

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

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

  4. Storm/Quiet Ratio Comparisons Between TIMED/SABER NO (sup +)(v) Volume Emission Rates and Incoherent Scatter Radar Electron Densities at E-Region Altitudes

    Science.gov (United States)

    Fernandez, J. R.; Mertens, C. J.; Bilitza, D.; Xu, X.; Russell, J. M., III; Mlynczak, M. G.

    2009-01-01

    Broadband infrared limb emission at 4.3 microns is measured by the TIMED/SABER instrument. At night, these emission observations at E-region altitudes are used to derive the so called NO+(v) Volume Emission Rate (VER). NO+(v) VER can be derived by removing the background CO2(v3) 4.3 microns radiance contribution using SABER-based non-LTE radiation transfer models, and by performing a standard Abel inversion on the residual radiance. SABER observations show that NO+(v) VER is significantly enhanced during magnetic storms in accordance with increased ionization of the neutral atmosphere by auroral electron precipitation, followed by vibrational excitation of NO+ (i.e., NO+(v)) from fast exothermic ion-neutral reactions, and prompt infrared emission at 4.3 m. Due to charge neutrality, the NO+(v) VER enhancements are highly correlated with electron density enhancements, as observed for example by Incoherent Scatter Radar (ISR). In order to characterize the response of the storm-time E-region from both SABER and ISR measurements, a Storm/Quiet ratio (SQR) quantity is defined as a function of altitude. For SABER, the SQR is the ratio of the storm-to-quiet NO+(v) VER. SQR is the storm-to-quiet ratio of electron densities for ISR. In this work, we compare SABER and ISR SQR values between 100 to 120 km. Results indicate good agreement between these measurements. SQR values are intended to be used as a correction factor to be included in an empirical storm-time correction to the International Reference Ionosphere model at E-region altitudes.

  5. Recent developments in the understanding of equatorial ionization anomaly: A review

    Science.gov (United States)

    Balan, N.; Souza, J.; Bailey, G. J.

    2018-06-01

    A brief review of the recent developments in the understanding of the equatorial plasma fountain (EPF) and equatorial ionization anomaly (EIA) under quiet and active conditions is presented. It is clarified that (1) the EPF is not upward ExB plasma drift at the equator followed by downward plasma diffusion, but it is field perpendicular ExB plasma drift and field-aligned plasma diffusion acting together all along the field lines at all altitudes and plasma flowing in the direction of the resultant. (2) The EIA is formed not from the accumulation of plasma at the crests but mainly from the removal of plasma from around the equator by the upward ExB drift with small accumulations when the crests are within approximately ±20° magnetic latitude. The accumulations reduce with increasing latitude and become zero by approximately ±25°. (3) An asymmetric neutral wind makes EPF and EIA asymmetric with stronger fountain and stronger crest usually occurring in opposite hemispheres especially at equinoxes when winter anomaly is absent. (4) During the early stages of daytime main phase of major geomagnetic storms, the plasma fountain becomes a super fountain and the EIA becomes strong not due to the eastward prompt penetration electric field (PPEF) alone but due to the combined effect of eastward PPEF and storm-time equatorward winds (SEW). (5) During the later stages of the storms when EIA gets inhibited a peak sometimes occurs around the equator not due to westward electric fields but mainly due to the convergence of plasma from both hemispheres due to SEW.

  6. Central Equatorial Pacific Experiment (CEPEX)

    Energy Technology Data Exchange (ETDEWEB)

    1993-01-01

    The Earth's climate has varied significantly in the past, yet climate records reveal that in the tropics, sea surface temperatures seem to have been remarkably stable, varying by less than a few degrees Celsius over geologic time. Today, the large warm pool of the western Pacific shows similar characteristics. Its surface temperature always exceeds 27[degree]C, but never 31[degree]C. Heightened interest in this observation has been stimulated by questions of global climate change and the exploration of stabilizing climate feedback processes. Efforts to understand the observed weak sensitivity of tropical sea surface temperatures to climate forcing has led to a number of competing ideas about the nature of this apparent thermostat. Although there remains disagreement on the processes that regulate tropical sea surface temperature, most agree that further progress in resolving these differences requires comprehensive field observations of three-dimensional water vapor concentrations, solar and infrared radiative fluxes, surface fluxes of heat and water vapor, and cloud microphysical properties. This document describes the Central Equatorial Pacific Experiment (CEPEX) plan to collect such observations over the central equatorial Pacific Ocean during March of 1993.

  7. Seasonal-longitudinal variability of equatorial plasma bubbles

    Directory of Open Access Journals (Sweden)

    W. J. Burke

    2004-09-01

    Full Text Available We compare seasonal and longitudinal distributions of more than 8300 equatorial plasma bubbles (EPBs observed during a full solar cycle from 1989-2000 with predictions of two simple models. Both models are based on considerations of parameters that influence the linear growth rate, γRT, of the generalized Rayleigh-Taylor instability in the context of finite windows of opportunity available during the prereversal enhancement near sunset. These parameters are the strength of the equatorial magnetic field, Beq, and the angle, α, it makes with the dusk terminator line. The independence of α and Beq from the solar cycle phase justifies our comparisons.

    We have sorted data acquired during more than 75000 equatorial evening-sector passes of polar-orbiting Defense Meteorological Satellite Program (DMSP satellites into 24 longitude and 12 one-month bins, each containing ~250 samples. We show that: (1 in 44 out of 48 month-longitude bins EPB rates are largest within 30 days of when α=0°; (2 unpredicted phase shifts and asymmetries appear in occurrence rates at the two times per year when α≈0°; (3 While EPB occurrence rates vary inversely with Beq, the relationships are very different in regions where Beq is increasing and decreasing with longitude. Results (2 and (3 indicate that systematic forces not considered by the two models can become important. Damping by interhemispheric winds appears to be responsible for phase shifts in maximum rates of EPB occurrence from days when α=0°. Low EPB occurrence rates found at eastern Pacific longitudes suggest that radiation belt electrons in the drift loss cone reduce γRT by enhancing E-layer Pedersen conductances. Finally, we analyze an EPB event observed during a magnetic storm at a time and place where α≈-27°, to illustrate how electric-field penetration from

  8. Ionosphere dynamics over the Southern Hemisphere during the 31 March 2001 severe magnetic storm using multi-instrument measurement data

    Directory of Open Access Journals (Sweden)

    E. Yizengaw

    2005-03-01

    Full Text Available The effects of the 31 March 2001 severe magnetic storm on the Southern Hemisphere ionosphere have been studied using ground-based and satellite measurements. The prime goal of this comprehensive study is to track the ionospheric response from high-to-low latitude to obtain a clear understanding of storm-time ionospheric change. The study uses a combination of ionospheric Total Electron Content (TEC obtained from GPS signal group delay and phase advance measurements, ionosonde data, and data from satellite in-situ measurements, such as the Defense Metrological Satellite Program (DMSP, TOPographic EXplorer (TOPEX, and solar wind data from the Advanced Composition Explorer (ACE. A chain of Global Positioning System (GPS stations near the 150° E meridian has been used to give comprehensive latitude coverage extending from the cusp to the equatorial region. A tomographic inversion algorithm has been applied to the GPS TEC measurements to obtain maps of the latitudinal structure of the ionospheric during this severe magnetic storm period, enabling both the spatial and temporal response of the ionosphere to be studied. Analysis of data from several of the instruments indicates that a strong density enhancement occurred at mid-latitudes at 11:00 UT on 31 March 2001 and was followed by equatorward propagating large-scale Travelling Ionospheric Disturbances (TIDs. The tomographic reconstruction revealed important features in ionospheric structure, such as quasi-wave formations extending finger-like to higher altitudes. The most pronounced ionospheric effects of the storm occurred at high- and mid-latitudes, where strong positive disturbances occurred during the storm main phase, followed by a long lasting negative storm effect during the recovery phase. Relatively minor storm effects occurred in the equatorial region.

  9. Global evolution of storm-time effects in the-F region during 17-18 December 1971

    International Nuclear Information System (INIS)

    Alamelu, V.; Mukunda Rao, M.; Sethuraman, R.

    1982-01-01

    The latitudinal variation of the effect of the great storm of 17 Dec. 71 is investigated by choosing stations of varying latitudes but of approximately the same longitude. In addition, three stations, one each in the American, African and Indian zone, are chosen to find the longitudinal changes produced during this storm. It is seen that the storm is mainly a negative one in the southern hemisphere of this longitude sector. The noon biteout is enhanced on the major storm day, viz., 17 Dec. 71, at the American equator, with large evening peaks on both 17th and 18th. The northern hemisphere does not exhibit any large change in the critical frequency of the F layer. The reported changes in TEC measurements are not reflected in the parameter f 0 F 2 at Lindau

  10. Simultaneous Remote Observations of Intense Reconnection Effects by DMSP and MMS Spacecraft During a Storm Time Substorm.

    Science.gov (United States)

    Varsani, A; Nakamura, R; Sergeev, V A; Baumjohann, W; Owen, C J; Petrukovich, A A; Yao, Z; Nakamura, T K M; Kubyshkina, M V; Sotirelis, T; Burch, J L; Genestreti, K J; Vörös, Z; Andriopoulou, M; Gershman, D J; Avanov, L A; Magnes, W; Russell, C T; Plaschke, F; Khotyaintsev, Y V; Giles, B L; Coffey, V N; Dorelli, J C; Strangeway, R J; Torbert, R B; Lindqvist, P-A; Ergun, R

    2017-11-01

    During a magnetic storm on 23 June 2015, several very intense substorms took place, with signatures observed by multiple spacecraft including DMSP and Magnetospheric Multiscale (MMS). At the time of interest, DMSP F18 crossed inbound through a poleward expanding auroral bulge boundary at 23.5 h magnetic local time (MLT), while MMS was located duskward of 22 h MLT during an inward crossing of the expanding plasma sheet boundary. The two spacecraft observed a consistent set of signatures as they simultaneously crossed the reconnection separatrix layer during this very intense reconnection event. These include (1) energy dispersion of the energetic ions and electrons traveling earthward, accompanied with high electron energies in the vicinity of the separatrix; (2) energy dispersion of polar rain electrons, with a high-energy cutoff; and (3) intense inward convection of the magnetic field lines at the MMS location. The high temporal resolution measurements by MMS provide unprecedented observations of the outermost electron boundary layer. We discuss the relevance of the energy dispersion of the electrons, and their pitch angle distribution, to the spatial and temporal evolution of the boundary layer. The results indicate that the underlying magnetotail magnetic reconnection process was an intrinsically impulsive and the active X-line was located relatively close to the Earth, approximately at 16-18 R E .

  11. DEMETER Observations of Equatorial Plasma Depletions and Related Ionospheric Phenomena

    Science.gov (United States)

    Berthelier, J.; Malingre, M.; Pfaff, R.; Jasperse, J.; Parrot, M.

    2008-12-01

    DEMETER, the first micro-satellite of the CNES MYRIAD program, was launched from Baikonour on June 29, 2004 on a nearly circular, quasi helio-synchronous polar orbit at ~ 715 km altitude. The DEMETER mission focuses primarily on the search for a possible coupling between seismic activity and ionospheric disturbances as well as on the effects of natural phenomena such as tropospheric thunderstorms and man-made activities on the ionosphere. The scientific payload provides fairly complete measurements of the ionospheric plasma, energetic particles above ~ 70 keV, and plasma waves, up to 20 kHz for the magnetic and 3.3 MHz for the electric components. Several studies related to space weather and ionospheric physics have been conducted over the past years. Following a brief description of the payload and the satellite modes of operation, this presentation will focus on a set of results that provide a new insight into the physics of instabilities in the night-time equatorial ionosphere. The observations were performed during the major magnetic storm of November 2004. Deep plasma depletions were observed on several night-time passes at low latitudes characterized by the decrease of the plasma density by nearly 3 orders of magnitude relative to the undisturbed plasma, and a significant abundance of molecular ions. These features can be best interpreted as resulting from the rise of the F-layer above the satellite altitude over an extended region of the ionosphere. In one of the passes, DEMETER was operated in the Burst mode and the corresponding high resolution data allowed for the discovery of two unexpected phenomena. The first one is the existence of high intensity monochromatic wave packets at the LH frequency that develop during the decay phase of intense bursts of broadband LH turbulence. The broadband LH turbulence is triggered by whistlers emitted by lightning from atmospheric thunderstorms beneath the satellite. The second unexpected feature is the detection of a

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

    Science.gov (United States)

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

    2013-01-01

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

  13. Upright in the storm of time. The physicist James Franck 1882-1964

    International Nuclear Information System (INIS)

    Lemmerich, J.

    2007-01-01

    For the 125th birth day of James Franck in the year 2007 for the first time a scientific biography is presented. Born in Hamburg Franck dedicated himself to the exploration of the atom. Together with Gustav Hertz he succeeded in exciting of bound electrons by collision, whereby the atomic model of Bohr was confirmed. For this both got the Nobel price for the year 1925. Starting from 1921 Franck founded together with Max Born and Robert Pohl the world-wide reputation of Goettingen as a center of physical research. 1933 Franck resigned because of protest against the antisemitic policy of the Nazis and imigrated to the USA. There he dedicated himself to the exploration of the foundation of the photosynthesis. To the request to contribute the the construction of the atomic bomb the Hitler opponent not denied, but wrote after the German capitulation the Franck report in May 1945, in which he described impressively the arguments against the application of the bomb and warned for a nuclear armament race. Although he was because of the great crime of the Nazi regime very critical against the Germans soon after the war he stood up - very to the indignation of his friend Einstein - for the reconcilement and visited Germany and his friends there still several times. 1964 he died at a visit in Goettingen

  14. Evolution of Storm-time Subauroral Electric Fields: RCM Event Simulations

    Science.gov (United States)

    Sazykin, S.; Spiro, R. W.; Wolf, R. A.; Toffoletto, F.; Baker, J.; Ruohoniemi, J. M.

    2012-12-01

    Subauroral polarization streams (SAPS) are regions of strongly-enhanced westward ExB plasma drift (poleward-directed electric fields) located just equatorward of the evening auroral oval. Several recently -installed HF (coherent scatter) radars in the SuperDARN chain at mid-latitudes present a novel opportunity for obtaining two-dimensional maps of ionospheric ExB flows at F-region altitudes that span several hours of the evening and nighttime subauroral ionosphere. These new and exciting observations of SAPS provide an opportunity and a challenge to coupled magnetosphere-ionosphere models. In this paper, we use the Rice Convection Model (RCM) to simulate several events where SAPS were observed by the mid-latitude SuperDARN chain. RCM frequently predicts the occurrence of SAPS in the subauroral evening MLT sector; the mechanism is essentially current closure on the dusk side where downward Birkeland currents (associated with the ion plasma sheet inner edge) map to a region of reduced ionospheric conductance just equatorward of the diffuse auroral precipitation (associated with the electron plasma sheet inner edge). We present detailed comparisons of model-computed ionospheric convection patterns with observations, with two goals in mind: (1) to analyze to what extent the observed appearance and time evolution of SAPS structures are driven by time variations of the cross polar cap potential drop (or, equivalently, the z-component of the interplanetary magnetic field), and (2) to evaluate the ability of the model to reproduce the spatial extent and magnitude of SAPS structures.

  15. Thermal Tides During the 2001 Martian Global-Scale Dust Storm

    Science.gov (United States)

    Guzewich, Scott D.; Wilson, R. John; McConnochie, Timothy H.; Toigo, Anthony D.; Bandfield, Donald J.; Smith, Michael D.

    2014-01-01

    The 2001 (Mars Year 25) global dust storm radically altered the dynamics of the Martian atmosphere. Using observations from the Thermal Emission Spectrometer onboard the Mars Global Surveyor spacecraft and Mars WRF general circulation model simulations, we examine the changes to thermal tides and planetary waves caused by the storm. We find that the extratropical diurnal migrating tide is dramatically enhanced during the storm, particularly in the southern hemisphere, reaching amplitudes of more than 20 K. The tropical diurnal migrating tide is weakened to almost undetectable levels. The diurnal Kelvin waves are also significantly weakened, particularly during the period of global expansion at Ls=200deg-210deg. In contrast, the westward propagating diurnal wavenumber 2 tide strengthens to 4-8 K at altitudes above 30km. The wavenumber 1 stationary wave reaches amplitudes of 10-12 K at 50deg-70degN, far larger than is typically seen during this time of year. The phase of this stationary wave and the enhancement of the diurnal wavenumber 2 tide appear to be responses to the high-altitude westward propagating equatorial wavenumber 1 structure in dust mixing ratio observed during the storm in previous works. This work provides a global picture of dust storm wave dynamics that reveals the coupling between the tropics and high-latitude wave responses. We conclude that the zonal distribution of thermotidal forcing from atmospheric aerosol concentration is as important to understanding the atmospheric wave response as the total global mean aerosol optical depth.

  16. The storm time ring current dynamics and response to CMEs and CIRs using Van Allen Probes observations and CIMI simulations

    Science.gov (United States)

    Mouikis, Christopher; Bingham, Samuel; Kistler, Lynn; Spence, Harlan; Gkioulidou, Matina

    2017-04-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), and co-rotating interaction regions (CIR's). Using Van Allen Probes observations, we develop an empirical ring current model of the ring current pressure, the pressure anisotropy and the current density development during the storm phases for both types of storm drivers and for all MLTs inside L 6. Delineating the differences in the ring current development between these two drivers will aid our understanding of the ring current dynamics. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L 2 and their pressure compares to the local magnetic field pressure as deep as L 3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current. However, the largest difference between the CME and CIR ring current responses during the storm main and early recovery phases is caused by how the 15 - 60 keV O+ responds to these drivers. This empirical model is compared to the results of CIMI simulations of a CMEs and a CIRs where the model input is comprised of the superposed epoch solar wind conditions of the storms that comprise the empirical model. Different inner magnetosphere boundary conditions are tested in order to match the empirical model results. Comparing the model and simulation results improves our understanding of the ring current dynamics as part of the highly coupled inner magnetosphere system. In addition, within the framework of this empirical model, the prediction of the EMIC wave generation linear theory is tested using the observed plasma parameters and comparing with the observations of

  17. Proton flux under radiation belts: near-equatorial zone

    International Nuclear Information System (INIS)

    Grigoryan, O.R.; Panasyuk, M.I.; Petrov, A.N.; Kudela, K.

    2005-01-01

    In this work the features of low-energy proton flux increases in near-equatorial region (McIlvein parameter L th the proton flux (with energy from tens keV up to several MeV) increases are registering regularly. However modern proton flux models (for example AP8 model) works at L>1.15 only and does not take into account near-equatorial protons. These fluxes are not too big, but the investigation of this phenomenon is important in scope of atmosphere-ionosphere connections and mechanisms of particles transport in magnetosphere. In according to double charge-exchange model the proton flux in near-equatorial region does not depend on geomagnetic local time (MLT) and longitude. However the Azur satellite data and Kosmos-484, MIR station and Active satellite data revealed the proton flux dependence on longitude. The other feature of near-equatorial proton flux is the dependence on geomagnetic local time revealed in the Sampex satellite experiment and other experiments listed above. In this work the dependences on MLT and longitude are investigated using the Active satellite (30-500 keV) and Sampex satellite (>800 keV). This data confirms that main sources of near-equatorial protons are radiation belts and ring current. The other result is that near-equatorial protons are quasi-trapped. The empirical proton flux dependences on L, B at near-equatorial longitudes are presented. (author)

  18. Field-aligned structure of the storm time Pc 5 wave of November 14-15, 1979

    International Nuclear Information System (INIS)

    Takahashi, K.; Higbie, P.R.; Fennell, J.F.; Amata, E.

    1987-01-01

    Magnetic field data from the four satellites SCATHA (P78-2), GOES 2, GOES 3, and GEOS 2 have been analyzed to examine the magnetic field-aligned structure of a storm time Pc 5 wave that occurred on November 14-15, 1979. The wave had both transverse and compressional components. At a given instance the compressional and the radial components oscillated in phase of 180 degree out of phase, and the compressional and the azimuthal components oscillated +90 degree or -90 degree out of phase. In addition, each component changed its amplitude with magnetic latitude: the compressional component had a minimum at the magnetic equator, whereas the transverse components had a maximum at the equator and minima several degrees off the equator. A 180 degree relative phase switching among the components occurred across the latitudes of amplitude minima. From these observations the field line displacement of the wave is confirmed to have an antisymmetric standing structure about the magnetic equator with a parallel wave length of a few earth radii. The authors also observed other intriguing properties of the wave such as different parallel wave lengths of different field components and small-amplitude second harmonics near the nodes. A dielectric tensor appropriate for the ring current plasma is found to give an explanation for the relation between the polarization and the propagation of the wave. However, plasma data available from SCATHA does not support either the drift mirror instability of A. Hasegawa (1969) or the coupling between a drift mirror wave and a shear Alfven wave as discussed by A.D.M. Walker et al. (1982)

  19. Effect of solar flare on the equatorial electrojet in eastern Brazil region

    Indian Academy of Sciences (India)

    The effect of solar flare, sudden commencement of magnetic storm and of the disturbances ring current on the equatorial electrojet in the Eastern Brazil region, where the ground magnetic declination is as large as 20∘W is studied based on geomagnetic data with one minute resolution from Bacabal during ...

  20. An investigation of ionospheric F region response in the Brazilian sector to the super geomagnetic storm of May 2005

    Science.gov (United States)

    de Abreu, A. J.; Sahai, Y.; Fagundes, P. R.; de Jesus, R.; Bittencourt, J. A.; Pillat, V. G.

    2011-10-01

    In this paper, we have investigated the responses of the ionospheric F region at equatorial and low latitude regions in the Brazilian sector during the super geomagnetic storm on 15-16 May 2005. The geomagnetic storm reached a minimum Dst of -263 nT at 0900 UT on 15 May. In this paper, we present vertical total electron content (vTEC) and phase fluctuations (in TECU/min) from Global Positioning System (GPS) observations obtained at Belém, Brasília, Presidente Prudente, and Porto Alegre, Brazil, during the period 14-17 May 2005. Also, we present ionospheric parameters h'F, hpF2, and foF2, using the Canadian Advanced Digital Ionosonde (CADI) obtained at Palmas and São José dos Campos, Brazil, for the same period. The super geomagnetic storm has fast decrease in the Dst index soon after SSC at 0239 UT on 15 May. It is a good possibility of prompt penetration of electric field of magnetospheric origin resulting in uplifting of the F region. The vTEC observations show a trough at BELE and a crest above UEPP, soon after SSC, indicating strengthening of nighttime equatorial anomaly. During the daytime on 15 and 16 May, in the recovery phase, the variations in foF2 at SJC and the vTEC observations, particularly at BRAZ, UEPP, and POAL, show large positive ionospheric storm. There is ESF on the all nights at PAL, in the post-midnight (UT) sector, and phase fluctuations only on the night of 14-15 May at BRAZ, after the SSC. No phase fluctuations are observed at the equatorial station BELE and low latitude stations (BRAZ, UEPP, and POAL) at all other times. This indicates that the plasma bubbles are generated and confined on this magnetically disturbed night only up to the low magnetic latitude and drifted possibly to west.

  1. Equatorial electrojet in east Brazil longitudes

    Indian Academy of Sciences (India)

    dip latitude as the electrons/ions can move vertically along the inclined magnetic field lines. Equatorial electrojet has been extensively studied from ground, rocket ... Keywords. Equatorial electrojet; Brazilian anomaly in equatorial electrojet; asymmetries in equatorial electrojet. J. Earth Syst. Sci. 119, No. 4, August 2010, pp.

  2. Observations of unusual pre-dawn response of the equatorial F-region during geomagnetic disturbances

    Science.gov (United States)

    Lima, W.; Becker-Guedes, F.; Fagundes, P.; Sahai, Y.; Abalde, J.; Pillat, V.

    It is known that the disturbed solar wind-magnetosphere interactions have important effects on equatorial and low-latitude ionospheric electrodynamics. The response of equatorial ionosphere during storm-time is an important aspect of space weather studies. It has been observed that during geomagnetic disturbances both suppression as well as generation of equatorial spread-F (ESF) or plasma irregularities takes place. However, the mechanism(s) associated with the generation of ESF still needs further investigations. This work reports some unusual events of pre-dawn occurrence of ionospheric F-region satellite traces followed by spread-F and cusp-like spread-F from ionospheric sounding observations carried out by a Canadian Advanced Digital Ionosonde (CADI) localized at Palmas (10.2°, 48.2°W, dip latitude 5.7°S), Brazil during 2002, every 5 minutes. For the present work we have scaled and analyzed the ionospheric sounding data for three events (April 20, September 04 and 08, 2002), which are associated with geomagnetic disturbances. In the events studied, the ionograms show the occurrence of satellite trace followed by cusp-like spread. The cusp like features move up in frequency and height and finally attain the F-layer peak value (foF2) and then disappear. They had duration of about 30 min and always occurred in the early morning hours. Our studies involved seven geomagnetic disturbances as well as quiet days during the year 2002, but only on these three occasions we observed these features. We present and discuss these observations in this paper and suggest possible mechanisms for the occurrence of these unusual features.

  3. A new ionospheric storm scale based on TEC and foF2 statistics

    Science.gov (United States)

    Nishioka, Michi; Tsugawa, Takuya; Jin, Hidekatsu; Ishii, Mamoru

    2017-01-01

    In this paper, we propose the I-scale, a new ionospheric storm scale for general users in various regions in the world. With the I-scale, ionospheric storms can be classified at any season, local time, and location. Since the ionospheric condition largely depends on many factors such as solar irradiance, energy input from the magnetosphere, and lower atmospheric activity, it had been difficult to scale ionospheric storms, which are mainly caused by solar and geomagnetic activities. In this study, statistical analysis was carried out for total electron content (TEC) and F2 layer critical frequency (foF2) in Japan for 18 years from 1997 to 2014. Seasonal, local time, and latitudinal dependences of TEC and foF2 variabilities are excluded by normalizing each percentage variation using their statistical standard deviations. The I-scale is defined by setting thresholds to the normalized numbers to seven categories: I0, IP1, IP2, IP3, IN1, IN2, and IN3. I0 represents a quiet state, and IP1 (IN1), IP2 (IN2), and IP3 (IN3) represent moderate, strong, and severe positive (negative) storms, respectively. The proposed I-scale can be used for other locations, such as polar and equatorial regions. It is considered that the proposed I-scale can be a standardized scale to help the users to assess the impact of space weather on their systems.

  4. Climate change increases the probability of heavy rains in Northern England/Southern Scotland like those of storm Desmond—a real-time event attribution revisited

    Science.gov (United States)

    Otto, Friederike E. L.; van der Wiel, Karin; van Oldenborgh, Geert Jan; Philip, Sjoukje; Kew, Sarah F.; Uhe, Peter; Cullen, Heidi

    2018-02-01

    On 4-6 December 2015, storm Desmond caused very heavy rainfall in Northern England and Southern Scotland which led to widespread flooding. A week after the event we provided an initial assessment of the influence of anthropogenic climate change on the likelihood of one-day precipitation events averaged over an area encompassing Northern England and Southern Scotland using data and methods available immediately after the event occurred. The analysis was based on three independent methods of extreme event attribution: historical observed trends, coupled climate model simulations and a large ensemble of regional model simulations. All three methods agreed that the effect of climate change was positive, making precipitation events like this about 40% more likely, with a provisional 2.5%-97.5% confidence interval of 5%-80%. Here we revisit the assessment using more station data, an additional monthly event definition, a second global climate model and regional model simulations of winter 2015/16. The overall result of the analysis is similar to the real-time analysis with a best estimate of a 59% increase in event frequency, but a larger confidence interval that does include no change. It is important to highlight that the observational data in the additional monthly analysis does not only represent the rainfall associated with storm Desmond but also that of storms Eve and Frank occurring towards the end of the month.

  5. Extreme changes in the dayside ionosphere during a Carrington-type magnetic storm

    Directory of Open Access Journals (Sweden)

    Mannucci Anthony J.

    2012-06-01

    Full Text Available It is shown that during the 30 October 2003 superstorm, dayside O+ ions were uplifted to DMSP altitudes (~850 km. Peak densities were ~9 × 105 cm−3 during the magnetic storm main phase (peak Dst = −390 nT. By comparison the 1–2 September 1859 Carrington magnetic storm (peak Dst estimated at −1760 nT was considerably stronger. We investigate the impact of this storm on the low- to mid-latitude ionosphere using a modified version of the NRL SAMI2 ionospheric code. It is found that the equatorial region (LAT = 0° ± 15° is swept free of plasma within 15 min (or less of storm onset. The plasma is swept to higher altitudes and higher latitudes due to E × B convection associated with the prompt penetration electric field. Equatorial Ionization Anomaly (EIA O+ density enhancements are found to be located within the broad range of latitudes ~ ± (25°–40° at ~500–900 km altitudes. Densities within these peaks are ~6 × 106 oxygen ions-cm−3 at ~700 km altitude, approximately +600% quiet time values. The oxygen ions at the top portions (850–1000 km of uplifted EIAs will cause strong low-altitude satellite drag. Calculations are currently being performed on possible uplift of oxygen neutrals by ion-neutral coupling to understand if there might be further significant satellite drag forces present.

  6. Substorms during different storm phases

    Directory of Open Access Journals (Sweden)

    N. Partamies

    2011-11-01

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

  7. Geomagnetic storm forecasting service StormFocus: 5 years online

    Science.gov (United States)

    Podladchikova, Tatiana; Petrukovich, Anatoly; Yermolaev, Yuri

    2018-04-01

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

  8. IRI STORM validation over Europe

    Science.gov (United States)

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

    2014-05-01

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

  9. [Electrical storm].

    Science.gov (United States)

    Barnay, C; Taieb, J; Morice, R

    2007-11-01

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

  10. Geomagnetic Storm Sudden Commencements

    Data.gov (United States)

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

  11. Development of Real-Time System for Urban Flooding by Surcharge of Storm Drainge and River Inundation

    Science.gov (United States)

    Shim, J. B.; Won, C. Y.; Park, J.; Lee, K.

    2017-12-01

    Korea experiences frequent flood disasters, which cause considerable economic losses and damages to towns and farms. Especially, a regional torrential storm is about 98.5mm/hr on September 21, 2010 in Seoul. The storm exceeds the capacity of urban drainage system of 75mm/hr, and 9,419 houses. How to monitor and control the urban flood disasters is an important issue in Korea. To mitigate the flood damage, a customizing system was developed to estimate urban floods and inundation using by integrating drainage system data and river information database which are managed by local governments and national agencies. In the case of Korean urban city, there are a lot of detention ponds and drainage pumping stations on end of drainage system and flow is going into river. The drainage pumping station, it is very important hydraulic facility for flood control between river and drainage system. So, it is possible to occur different patterns of flood inundation according to operation rule of drainage pumping station. A flood disaster is different damage as how to operate drainage pumping station and plan operation rule.

  12. Alternative approach for management of an electrical storm in Brugada syndrome:Importance of primary ablation within a narrow time window

    Directory of Open Access Journals (Sweden)

    Ahmed Karim Talib, MD, PhD

    2016-06-01

    Full Text Available Placement of an implantable cardioverter–defibrillator (ICD is the only powerful treatment modality for Brugada syndrome in patients presenting with ventricular fibrillation (VF. For those whose first presentation is an electrical storm, pharmacologic therapy is typically used to control VF followed by ICD implantation. We report an alternative approach whereby, before ICD implantation, emergency catheter ablation of the VF-triggering premature ventricular contraction (PVC resulted in long-term VF-free survival. The results suggest that, because VF triggers appear in a narrow time window, ablation of the culprit PVCs that initiate VF before the index PVCs subside is a reasonable alternative approach.

  13. Signatures of storm sudden commencements in geomagnetic H, Y and Z fields at Indian observatories during 1958−1992

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    1999-11-01

    Full Text Available The work describes an intensive study of storm sudden commencement (SSC impulses in horizontal (H, eastward (Y and vertical (Z fields at four Indian geomagnetic observatories between 1958–1992. The midday maximum of ΔH has been shown to exist even at the low-latitude station Alibag which is outside the equatorial electrojet belt, suggesting that SSC is associated with an eastward electric field at equatorial and low latitudes. The impulses in Y field are shown to be linearly and inversely related to ΔH at Annamalainagar and Alibag. The average SC disturbance vector is shown to be about 10–20°W of the geomagnetic meridian. The local time variation of the angle is more westerly during dusk hours in summer and around dawn in the winter months. This clearly suggests an effect of the orientation of shock front plane of the solar plasma with respect to the geomagnetic meridian. The ΔZ at SSC have a positive impulse as in ΔH. The ratio of ΔZ/ΔH are abnormally large exceeding 1.0 in most of the cases at Trivandrum. The latitudinal variation of ΔZ shows a tendency towards a minimum over the equator during the nighttime hours. These effects are explained as (1 resulting from the electromagnetic induction effects due to the equatorial electrojet current in the subsurface conducting layers between India and Sri Lanka, due to channelling of ocean currents through the Palk Strait and (2 due to the concentration of induced currents over extended latitude zones towards the conducting graben between India and Sri Lanka just south of Trivandrum.Key words. Interplanetary physics (interplanetary shocks · Ionosphere (equatorial ionosphere · Magnetospheric physics (storms and substorms

  14. The Earth's revolution, Moon phase, Syzygy astronomy events, their effect in disturbances of the Earth's geomagnetic field, and the ``Magnetic Storm Double Time Method'' for predicting the occurrence time, magnitude and epicenter location of earthquakes

    Science.gov (United States)

    Chen, I. W.

    2003-04-01

    An increasing number of geomagnetic observation stations were established and operated in China since 1966 to the 1980s (and until present), effectively covering a large area of the nation. Close relativity between magnetic storms and earthquakes, as well as close relativity between the regional differences of magnetic disturbance recorded by these stations and the epicenter location of earthquakes, was discovered and observed by Tie-zheng Zhang during1966 - 1969. On such basis during 1969/1970, Zhang developed the “Magnetic Storm Double Time Method” for predicting the occurrence time, magnitude and epicenter location of EQs. By this method,.Zhang successfully predicted the Yunnan Tonghai Ms7.7 EQ Jan. 5, 1970 (occurrence date only), the Bohai ML5.2 EQ, Feb. 12, 1970 and other EQs, including the Haicheng Ms7.3 EQ Feb. 4, 1975, and the Tangshan Ms7.8 EQ July 28, 1976. On the basis of this method, Z.P. Shen developed the “Geomagnetic Deflection Angle Double Time Method” in 1970, and later developed the “Magnetic Storm - Moon Phase Double Time Method” in 1990s. With this method, Shen is able to predict the occurrence dates of most of the strongest EQs Ms37.5 on the Earth since 1991. Zhang also discovered that strong EQs often correspond with a number of sets of magnetic storms. Z.Q. Ren discovered close relativity exists between Syzygy astronomy events and such sets of magnetic storm as well as the occurrence dates of strong EQs. Computerized calculation of historical magnetic storm and EQ data proves the effectiveness of this method. Over 3,000 days of geomagnetic isoline images are computer processed by the Author from over 400,000 geomagnetic field data obtained by Zhang from over 100 geomagnetic observation stations during 1966 - 1984. Clear relativity is shown between the Earth’s revolution, Moon phases, Syzygy astronomy events related to the Earth, and their disturbance effect on the Earth’s geomagnetic field and the occurrence of EQs.

  15. Application of flood-intensity-duration curve, rainfall-intensity-duration curve and time of concentration to analyze the pattern of storms and their corresponding floods for the natural flood events

    Science.gov (United States)

    Kim, Nam Won; Shin, Mun-Ju; Lee, Jeong Eun

    2016-04-01

    The analysis of storm effects on floods is essential step for designing hydraulic structure and flood plain. There are previous studies for analyzing the relationship between the storm patterns and peak flow, flood volume and durations for various sizes of the catchments, but they are not enough to analyze the natural storm effects on flood responses quantitatively. This study suggests a novel method of quantitative analysis using unique factors extracted from the time series of storms and floods to investigate the relationship between natural storms and their corresponding flood responses. We used a distributed rainfall-runoff model of Grid based Rainfall-runoff Model (GRM) to generate the simulated flow and areal rainfall for 50 catchments in Republic of Korea size from 5.6 km2 to 1584.2 km2, which are including overlapped dependent catchments and non-overlapped independent catchments. The parameters of the GRM model were calibrated to get the good model performances of Nash-Sutcliffe efficiency. Then Flood-Intensity-Duration Curve (FIDC) and Rainfall-Intensity-Duration Curve (RIDC) were generated by Flood-Duration-Frequency and Intensity-Duration-Frequency methods respectively using the time series of hydrographs and hyetographs. Time of concentration developed for the Korea catchments was used as a consistent measure to extract the unique factors from the FIDC and RIDC over the different size of catchments. These unique factors for the storms and floods were analyzed against the different size of catchments to investigate the natural storm effects on floods. This method can be easily used to get the intuition of the natural storm effects with various patterns on flood responses. Acknowledgement This research was supported by a grant (11-TI-C06) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government.

  16. Multiple Time-Scale Monitoring to Address Dynamic Seasonality and Storm Pulses of Stream Water Quality in Mountainous Watersheds

    Directory of Open Access Journals (Sweden)

    Hyun-Ju Lee

    2015-11-01

    Full Text Available Rainfall variability and extreme events can amplify the seasonality and storm pulses of stream water chemistry in mountainous watersheds under monsoon climates. To establish a monitoring program optimized for identifying potential risks to stream water quality arising from rainfall variability and extremes, we examined water chemistry data collected on different timescales. At a small forested watershed, bi-weekly sampling lasted over two years, in comparison to three other biweekly sampling sites. In addition, high-frequency continuous measurements of pH, electrical conductivity, and turbidity were conducted in tandem with automatic water sampling at 2 h intervals during eight rainfall events. Biweekly monitoring showed that during the summer monsoon period, electrical conductivity (EC, dissolved oxygen (DO, and dissolved ion concentrations generally decreased, but total suspended solids (TSS slightly increased. A noticeable variation from the usual seasonal pattern was that DO levels substantially decreased during an extended drought. Bi-hourly storm event samplings exhibited large changes in the concentrations of TSS and particulate and dissolved organic carbon (POC; DOC during intense rainfall events. However, extreme fluctuations in sediment export during discharge peaks could be detected only by turbidity measurements at 5 min intervals. Concomitant measurements during rainfall events established empirical relationships between turbidity and TSS or POC. These results suggest that routine monitoring based on weekly to monthly sampling is valid only in addressing general seasonal patterns or long-lasting phenomena such as drought effects. We propose an “adaptive” monitoring scheme that combines routine monitoring for general seasonal patterns and high-frequency instrumental measurements of water quality components exhibiting rapid responses pulsing during intense rainfall events.

  17. Magnetic storms and induction hazards

    Science.gov (United States)

    Love, Jeffrey J.; Rigler, E. Joshua; Pulkkinen, Antti; Balch, Christopher

    2014-01-01

    Magnetic storms are potentially hazardous to the activities and technological infrastructure of modern civilization. This reality was dramatically demonstrated during the great magnetic storm of March 1989, when surface geoelectric fields, produced by the interaction of the time-varying geomagnetic field with the Earth's electrically conducting interior, coupled onto the overlying Hydro-Québec electric power grid in Canada. Protective relays were tripped, the grid collapsed, and about 9 million people were temporarily left without electricity [Bolduc, 2002].

  18. Magnetic Storms at Mars and Earth

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Falkenberg, Thea Vilstrup

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

  19. Instability of equatorial protons in Jupiter's mid-magnetosphere

    International Nuclear Information System (INIS)

    Northrop, T.G.; Schardt, A.W.

    1980-01-01

    Two different models for the distribution function are fit to the Jovian protons seen by Pioneer 10 inbound. The models reproduce the observed energy and angular distributions. These models are then used to assess the collisionless mirror instability. Because of the pancake proton angular distributions in the equatorial ring current region, the ring current particle population appears to be mirror unstable at times, with instability growth rates of approx.10 min. Such a time is consistent with observed proton flux autocorrelation times. An instability such as this (there are other candidates) may be responsible for the previously established proton flux flowing parallel to the magnetic field away from the equatorial region

  20. Geomagnetic field variations at the equatorial electrojet station in Sri Lanka, Peredinia

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    2004-09-01

    Full Text Available The paper discusses the variations of the horizontal (H, vertical (Z and eastward (Y components of the geomagnetic field at Peredinia (PRD, an electrojet station in Sri Lanka, with the time of the day, season, sudden commencement (SSC and during geomagnetic storms. The daily variation of H showed a large peak around midday. The daily variation of Z appeared to be almost a time gradient curve of the daily variation of H, showing a maximum around 09:00 LT (75° EMT when the H field was increasing fastest and not at noon when Δ H was the maximum. Storm time variation of H resembled the variation of the Dst index but that of Z showed a large minimum about 2-3h before the time of minimum Dst or at the time of maximum time gradient of Dst variation. These features are compared with corresponding variations at the equatorial stations Trivandrum (TRD in India, and remarkable similarity in all observations is noticed at PRD and TRD. It is suggested that the observed abnormal features of Z variations at electrojet stations in India-Sri Lanka are due to (i direct effect of the ionospheric electrojet current (ii the induction effect of the image current by the average spatially extended conductivity region and (iii the induction current in the local subsurface conductor. It is suggested that the conductor responsible for the observed features in Z in India and Sri Lanka has to have extended spatial domain to latitudes well south of India, rather than confined to narrow Palk Strait.

  1. Proxy records of Holocene storm events in coastal barrier systems: Storm-wave induced markers

    Science.gov (United States)

    Goslin, Jérôme; Clemmensen, Lars B.

    2017-10-01

    Extreme storm events in the coastal zone are one of the main forcing agents of short-term coastal system behavior. As such, storms represent a major threat to human activities concentrated along the coasts worldwide. In order to better understand the frequency of extreme events like storms, climate science must rely on longer-time records than the century-scale records of instrumental weather data. Proxy records of storm-wave or storm-wind induced activity in coastal barrier systems deposits have been widely used worldwide in recent years to document past storm events during the last millennia. This review provides a detailed state-of-the-art compilation of the proxies available from coastal barrier systems to reconstruct Holocene storm chronologies (paleotempestology). The present paper aims (I) to describe the erosional and depositional processes caused by storm-wave action in barrier and back-barrier systems (i.e. beach ridges, storm scarps and washover deposits), (ii) to understand how storm records can be extracted from barrier and back-barrier sedimentary bodies using stratigraphical, sedimentological, micro-paleontological and geochemical proxies and (iii) to show how to obtain chronological control on past storm events recorded in the sedimentary successions. The challenges that paleotempestology studies still face in the reconstruction of representative and reliable storm-chronologies using these various proxies are discussed, and future research prospects are outlined.

  2. The growth and decay of equatorial backscatter plumes

    Science.gov (United States)

    Tsunoda, R. T.

    1980-02-01

    During the past three years, a series of rocket experiments from the Kwajalein Atoll, Marshall Islands, were conducted to investigate the character of intense, scintillation-producing irregularities that occur in the nighttime equatorial ionosphere. Because the source mechanism of equatorial irregularities, believed to be the Rayleigh-Taylor instability, is analogous to that which generates plasma-density striations in a nuclear-induced environment, there is considerable interest in the underlying physics that controls the characteristics of these irregularities. A primary objective of ALTAIR investigations of equatorial irregularities is to seek an understanding of the underlying physics by establishing the relationship between meter-scale irregularities (detected by ALTAIR), and the large-scale plasma-density depletions (or 'bubbles') that contain the kilometer-scale, scintillation-producing irregularities. We describe the time evolution of backscatter 'plumes' produced by one meter equatorial field-aligned irregularities. Using ALTAIR, a fully steerable backscatter radar, to repeatedly map selected plumes, we characterize the dynamic behavior of plumes in terms of growth and a decay phase. Most of the observed characteristics are found to be consistent with equatorial-irregularity generation predicted by current theories of Rayleigh-Taylor and gradient-drift instabilities. However, other characteristics have been found that suggest key roles played by the eastward neutral wind and by altitude-modulation of the bottomside F layer in establishing the initial conditions for plume growth.

  3. The women day storm

    OpenAIRE

    Parnowski, Aleksei; Polonska, Anna; Semeniv, Oleg

    2012-01-01

    On behalf of the International Women Day, the Sun gave a hot kiss to our mother Earth in a form of a full halo CME generated by the yesterday's double X-class flare. The resulting geomagnetic storm gives a good opportunity to compare the performance of space weather forecast models operating in near-real-time. We compare the forecasts of most major models and identify some common problems. We also present the results of our own near-real-time forecast models.

  4. Relativistic Electrons Observed at UARS and the Interpretation of their Storm-Associated Intensity Variations

    Science.gov (United States)

    Pesnell, W. D.; Goldberg, R. A.; Chenette, D. L.; Gaines, E. E.

    1999-01-01

    The High Energy Particle Spectrometer (HEPS) instrument on the Upper Atmosphere Research Satellite (UARS) provides a database of electron intensities well resolved in energy and pitch-angle. Because of its 57 deg. orbital inclination, UARS encounters with magnetic shells L greater than 2 occur quite far off-equator (B/B (sub 0) greater than 9), corresponding to equatorial pitch angle alpha (sub 0) greater than 20 deg. Data acquired by HEPS (October 1991 through September 1994) span the declining phase of Solar Cycle 22. To reveal the storm-associated time dependence of relativistic electron intensities over the wide range of energies (50 keV to 5 MeV) covered by HEPS, we divide the daily average of the measured spectrum at a given L value (bin width = 0.25) by the corresponding 500-day average and plot the results with a color scale that spans only 2.5 decades. The data show that our off-equatorial electron intensities typically increase with time after the end of recovery phase (not during main phase or recovery phase) of each geomagnetic storm. The delay in off-equatorial energetic electron response and the subsequent lifetime of the corresponding electron flux enhancement seem to increase with particle energy above 300 keV. The trend below 300 keV seems to be opposite, such that the delay varies inversely with electron energy. Our working hypothesis for interpretation is that stormtime radial transport tends to increase the phase-space densities of trapped relativistic electrons but typically leads to a flux increases at specified energies only as the current (as indicated by Dst) decays. Flux enhancements in early recovery phase are greatest for equatorially mirroring electrons, and to pitch-angle anisotropies are initially large. Subsequent pitch-angle diffusion broadens the flux enhancement to particles that mirror off equator, thus gradually increasing low-altitude electron intensities (as detected by HEPS/UARS) on time scales equal to about 20% of

  5. A modeling study of ionospheric F2-region storm effects at low geomagnetic latitudes during 17-22 March 1990

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    2006-05-01

    Full Text Available We have presented a comparison between the modeled NmF2 and hmF2, and NmF2 and hmF2, which were observed in the low-latitude ionosphere simultaneously by the Kokubunji, Yamagawa, Okinawa, Manila, Vanimo, and Darwin ionospheric sounders, by the middle and upper atmosphere (MU radar during 17-22 March 1990, and by the Arecibo radar for the time period of 20-22 March 1990. A comparison between the electron and ion temperatures measured by the MU and Arecibo radars and those produced by the model of the ionosphere and plasmasphere is presented. The empirical zonal electric field, the meridional neutral wind taken from the HWM90 wind model, and the NRLMSISE-00 neutral temperature and densities are corrected so that the model results agree reasonably with the ionospheric sounder observations, and the MU and Arecibo radar data. It is proved that the nighttime weakening of the equatorial zonal electric field (in comparison with that produced by the empirical model of Fejer and Scherliess (1997 or Scherliess and Fejer (1999, in combination with the corrected wind-induced plasma drift along magnetic field lines, provides the development of the nighttime enhancements in NmF2 observed over Manila during 17-22 March 1990. As a result, the new physical mechanism of the nighttime NmF2 enhancement formation close to the geomagnetic equator includes the nighttime weakening of the equatorial zonal electric field and equatorward nighttime plasma drift along magnetic field lines caused by neutral wind in the both geomagnetic hemispheres. It is found that the latitudinal positions of the crests depend on the E×B drift velocity and on the neutral wind velocity. The relative role of the main mechanisms of the equatorial anomaly suppression observed during geomagnetic storms is studied for the first time in terms of storm-time variations of the model crest-to-trough ratios of the equatorial anomaly. During most of the studied time period, a total contribution from

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

    International Nuclear Information System (INIS)

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

    1998-01-01

    storm-time ring current. An apparently new controversy regarding the relative importance of the two processes is thus created. It is important to identify the role of substorm occurrence in the large-scale enhancement of magnetospheric convection driven by solar wind electric fields. (3) Numerical schemes for predicting geomagnetic activity indices on the basis of solar/solar wind/interplanetary magnetic field parameters continue to be upgraded, ensuring reliable techniques for forecasting magnetic storms under real-time conditions. There is a need to evaluate the prediction capability of geomagnetic indices on the basis of physical processes that occur during storm time substorms. (4) It is crucial to differentiate between storms and nonstorm time substorms in terms of energy transfer/conversion processes, i.e., mechanical energy from the solar wind, electromagnetic energy in the magnetotail, and again, mechanical energy of particles in the plasma sheet, ring current, and aurora. To help answer the question of the role of substorms in energizing ring current particles, it is crucial to find efficient magnetospheric processes that heat ions up to some minimal energies so that they can have an effect on the strength of the storm time ring current. (5) The question of whether the Dst index is an accurate and effective measure of the storm time ring-current is also controversial. In particular, it is demonstrated that the dipolarization effect associated with substorm expansion

  7. Longitudinal Variation and Waves in Jupiter's South Equatorial Wind Jet

    Science.gov (United States)

    Simon-Miller, A. A.; Rogers, John H.; Gierasch, Peter J.; Choi, David; Allison, Michael; Adamoli, Gianluigi; Mettig, Hans-Joerg

    2012-01-01

    We have conducted a detailed study of the cloud features in the strong southern equatorial wind jet near 7.5 S planetographic latitude. To understand the apparent variations in average zonal wind jet velocity at this latitude [e.g.. 1,2,3], we have searched for variations iIi both feature latitude and velocity with longitude and time. In particular, we focused on the repetitive chevron-shaped dark spots visible on most dates and the more transient large anticyclonic system known as the South Equatorial Disturbance (SED). These small dark spots are interpreted as cloud holes, and are often used as material tracers of the wind field.

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

    Science.gov (United States)

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

    2015-12-16

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

  9. Toward an integrated storm surge application: ESA Storm Surge project

    Science.gov (United States)

    Lee, Boram; Donlon, Craig; Arino, Olivier

    2010-05-01

    Storm surges and their associated coastal inundation are major coastal marine hazards, both in tropical and extra-tropical areas. As sea level rises due to climate change, the impact of storm surges and associated extreme flooding may increase in low-lying countries and harbour cities. Of the 33 world cities predicted to have at least 8 million people by 2015, at least 21 of them are coastal including 8 of the 10 largest. They are highly vulnerable to coastal hazards including storm surges. Coastal inundation forecasting and warning systems depend on the crosscutting cooperation of different scientific disciplines and user communities. An integrated approach to storm surge, wave, sea-level and flood forecasting offers an optimal strategy for building improved operational forecasts and warnings capability for coastal inundation. The Earth Observation (EO) information from satellites has demonstrated high potential to enhanced coastal hazard monitoring, analysis, and forecasting; the GOCE geoid data can help calculating accurate positions of tide gauge stations within the GLOSS network. ASAR images has demonstrated usefulness in analysing hydrological situation in coastal zones with timely manner, when hazardous events occur. Wind speed and direction, which is the key parameters for storm surge forecasting and hindcasting, can be derived by using scatterometer data. The current issue is, although great deal of useful EO information and application tools exist, that sufficient user information on EO data availability is missing and that easy access supported by user applications and documentation is highly required. Clear documentation on the user requirements in support of improved storm surge forecasting and risk assessment is also needed at the present. The paper primarily addresses the requirements for data, models/technologies, and operational skills, based on the results from the recent Scientific and Technical Symposium on Storm Surges (www

  10. The electric storm of November 1882

    Science.gov (United States)

    Love, Jeffrey J.

    2018-01-01

    In November 1882, an intense magnetic storm related to a large sunspot group caused widespread interference to telegraph and telephone systems and provided spectacular and unusual auroral displays. The (ring current) storm time disturbance index for this storm reached maximum −Dst ≈ 386 nT, comparable to Halloween storm of 29–31 October 2003, but from 17 to 20 November the aa midlatitude geomagnetic disturbance index averaged 214.25 nT, the highest 4 day level of disturbance since the beginning of aa index in 1868. This storm contributed to scientists' understanding of the reality of solar‐terrestrial interaction. Past occurrences of magnetic storms, like that of November 1882, can inform modern evaluations of the deleterious effects that a magnetic superstorm might have on technological systems of importance to society.

  11. Central Equatorial Pacific Experiment (CEPEX). Design document

    Energy Technology Data Exchange (ETDEWEB)

    1993-04-01

    The Earth`s climate has varied significantly in the past, yet climate records reveal that in the tropics, sea surface temperatures seem to have been remarkably stable, varying by less than a few degrees Celsius over geologic time. Today, the large warm pool of the western Pacific shows similar characteristics. Its surface temperature always exceeds 27{degree}C, but never 31{degree}C. Heightened interest in this observation has been stimulated by questions of global climate change and the exploration of stabilizing climate feedback processes. Efforts to understand the observed weak sensitivity of tropical sea surface temperatures to climate forcing has led to a number of competing ideas about the nature of this apparent thermostat. Although there remains disagreement on the processes that regulate tropical sea surface temperature, most agree that further progress in resolving these differences requires comprehensive field observations of three-dimensional water vapor concentrations, solar and infrared radiative fluxes, surface fluxes of heat and water vapor, and cloud microphysical properties. This document describes the Central Equatorial Pacific Experiment (CEPEX) plan to collect such observations over the central equatorial Pacific Ocean during March of 1993.

  12. NCDC Storm Events Database

    Data.gov (United States)

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

  13. equatorial electrojet strength in the african sector during high

    African Journals Online (AJOL)

    Preferred Customer

    shown to be consistent with the earlier similar work carried out for the American and ... reference to the quiet day night time level of H, ... February and July, and shifts equator ward to 27°N ... effect of the equatorial electrojet along this line is.

  14. Radar observation of the equatorial counter-electrojet

    International Nuclear Information System (INIS)

    Hanuise, C.; Crochet, M.; Gouin, P.; Ogubazghi, Ghebrebrhan

    1979-01-01

    Electron drift velocity in the equatorial electrojet has been measured for a few years by coherent radar techniques in Africa. For the first time such measurements were performed during a strong reversal of the ionospheric current dubbed 'counter-electrojet'. These observations agree with the theories of the plasma instabilities at the origin of the electron density irregularities giving the radar echoes

  15. The effect of magnetic storm on the bottomside profile parameters B0 and

    International Nuclear Information System (INIS)

    Adeniyi, J.O.; Radicella, S.M.

    2001-01-01

    We have used data from an equatorial station for the investigation of magnetic storm effects on B0 and B1. Three storm events, which occurred in January, April and October of a low solar activity year (1995), were used for the study. B0 is the parameter that is mostly affected and the effect is concentrated on the daytime period (0700-1700LT). (author)

  16. Examples of storm impacts on barrier islands: Chapter 4

    Science.gov (United States)

    Plant, Nathaniel G.; Doran, Kara; Stockdon, Hilary F.

    2017-01-01

    This chapter focuses on the morphologic variability of barrier islands and on the differences in storm response. It describes different types of barrier island response to individual storms, as well as the integrated response of barrier islands to many storms. The chapter considers case study on the Chandeleur Island chain, where a decadal time series of island elevation measurements have documented a wide range of barrier island responses to storms and long-term processes that are representative of barrier island behaviour at many other locations. These islands are low elevation, extremely vulnerable to storms and exhibit a diversity of storm responses. Additionally, this location experiences a moderately high rate of relative sea-level rise, increasing its vulnerability to the combined impacts of storms and long-term erosional processes. Understanding how natural processes, including storm impacts and intervening recovery periods interact with man-made restoration processes is also broadly relevant to understand the natural and human response to future storms.

  17. Aerosol Transport Over Equatorial Africa

    Science.gov (United States)

    Gatebe, C. K.; Tyson, P. D.; Annegarn, H. J.; Kinyua, A. M.; Piketh, S.; King, M.; Helas, G.

    1999-01-01

    Long-range and inter-hemispheric transport of atmospheric aerosols over equatorial Africa has received little attention so far. Most aerosol studies in the region have focussed on emissions from rain forest and savanna (both natural and biomass burning) and were carried out in the framework of programs such as DECAFE (Dynamique et Chimie Atmospherique en Foret Equatoriale) and FOS (Fires of Savanna). Considering the importance of this topic, aerosols samples were measured in different seasons at 4420 meters on Mt Kenya and on the equator. The study is based on continuous aerosol sampling on a two stage (fine and coarse) streaker sampler and elemental analysis by Particle Induced X-ray Emission. Continuous samples were collected for two seasons coinciding with late austral winter and early austral spring of 1997 and austral summer of 1998. Source area identification is by trajectory analysis and sources types by statistical techniques. Major meridional transports of material are observed with fine-fraction silicon (31 to 68 %) in aeolian dust and anthropogenic sulfur (9 to 18 %) being the major constituents of the total aerosol loading for the two seasons. Marine aerosol chlorine (4 to 6 %), potassium (3 to 5 %) and iron (1 to 2 %) make up the important components of the total material transport over Kenya. Minimum sulfur fluxes are associated with recirculation of sulfur-free air over equatorial Africa, while maximum sulfur concentrations are observed following passage over the industrial heartland of South Africa or transport over the Zambian/Congo Copperbelt. Chlorine is advected from the ocean and is accompanied by aeolian dust recirculating back to land from mid-oceanic regions. Biomass burning products are transported from the horn of Africa. Mineral dust from the Sahara is transported towards the Far East and then transported back within equatorial easterlies to Mt Kenya. This was observed during austral summer and coincided with the dying phase of 1997/98 El

  18. Application of Synthetic Storm Technique for Diurnal and Seasonal Variation of Slant Path Ka-Band Rain Attenuation Time Series over a Subtropical Location in South Africa

    Directory of Open Access Journals (Sweden)

    J. S. Ojo

    2015-01-01

    Full Text Available As technology advances and more demands are on satellite services, rain-induced attenuation still creates one of the most damaging effects of the atmosphere on the quality of radio communication signals, especially those operating above 10 GHz. System designers therefore require statistical information on rain-induced attenuation over the coverage area in order to determine the appropriate transmitter and receiver characteristics to be adopted. This paper presents results on the time-varying rain characterization and diurnal variation of slant path rain attenuation in the Ka-band frequency simulated with synthetic storm techniques over a subtropical location in South Africa using 10-year rain rate time-series data. The analysis is based on the CDF of one-minute rain rate; time-series seasonal variation of rain rate observed over four time intervals: 00:00–06:00, 06:00–12:00, 12:00–18:00, and 18:00–24:00; diurnal fades margin; and diurnal variation of rain attenuation. Comparison was also made between the synthesized values and measured attenuation data. The predicted statistics are in good agreement with those obtained from the propagation beacon measurement in the area. The overall results will be needed for an acceptable planning that can effectively reduce the fade margin to a very low value for an optimum data communication over this area.

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

    Science.gov (United States)

    Karan, Deepak K.; Pallamraju, Duggirala

    2018-05-01

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

  20. Thermospheric dynamics during the March 22, 1979, magnetic storm 1. Model simulations

    International Nuclear Information System (INIS)

    Roble, R.G.; Forbes, J.M.; Marcos, F.A.

    1987-01-01

    The physical processes involved in the transfer of energy from the solar wind to the magnetosphere and its release associated with substorms on March 22, 1979, have been studied in detail by the Coordinated Data Analysis Workshop 6 (CDAW 6). The information derived from the CDAW 6 study, as well as other information obtained from magnetospheric modeling, is used to prescribe the time-dependent variations of the parameterizations for the auroral and magnetospheric convection models that are incorporated within the National Center for Atmospheric Research thermospheric general circulation model (TGCM). The period preceding the magnetic storm (March 21) was geomagnetically quiet, and the TGCM was run until a diurnally reproducible pattern was obtained. The time variations of auroral particle precipitation and enhanced magnetospheric convection on March 22 caused a considerable disturbance in the high-latitude circulation, temperature, and composition during the storm period that began at about 1055 UT. Large- and medium-scale disturbances were launched during the event that propagated to equatorial latitudes. The thermospheric response in the northern hemisphere was larger than that generated in the southern hemisphere, because the auroral oval and magnetospheric convection pattenr in the northern hemisphere were in sunlight during the storm period whereas they were in darkness in the southern hemisphere. The storm response was also different in the upper and the lower thermosphere. In the upper thermosphere the winds generally followed the two-cell pattern of magnetospheric convecton with a lag of only 1/2 to 1 hour. In the lower thermosphere there was a pronounced asymmetry between the circulation cells on the dawnside and on the duskside of the polar cap

  1. Quantum cloning machines for equatorial qubits

    International Nuclear Information System (INIS)

    Fan Heng; Matsumoto, Keiji; Wang Xiangbin; Wadati, Miki

    2002-01-01

    Quantum cloning machines for equatorial qubits are studied. For the case of a one to two phase-covariant quantum cloning machine, we present the networks consisting of quantum gates to realize the quantum cloning transformations. The copied equatorial qubits are shown to be separable by using Peres-Horodecki criterion. The optimal one to M phase-covariant quantum cloning transformations are given

  2. Role of interannual Kelvin wave propagations in the equatorial Atlantic on the Angola Benguela Current system

    Science.gov (United States)

    Imbol Koungue, Rodrigue Anicet; Illig, Serena; Rouault, Mathieu

    2017-06-01

    The link between equatorial Atlantic Ocean variability and the coastal region of Angola-Namibia is investigated at interannual time scales from 1998 to 2012. An index of equatorial Kelvin wave activity is defined based on Prediction and Research Moored Array in the Tropical Atlantic (PIRATA). Along the equator, results show a significant correlation between interannual PIRATA monthly dynamic height anomalies, altimetric monthly Sea Surface Height Anomalies (SSHA), and SSHA calculated with an Ocean Linear Model. This allows us to interpret PIRATA records in terms of equatorial Kelvin waves. Estimated phase speed of eastward propagations from PIRATA equatorial mooring remains in agreement with the linear theory, emphasizing the dominance of the second baroclinic mode. Systematic analysis of all strong interannual equatorial SSHA shows that they precede by 1-2 months extreme interannual Sea Surface Temperature Anomalies along the African coast, which confirms the hypothesis that major warm and cold events in the Angola-Benguela current system are remotely forced by ocean atmosphere interactions in the equatorial Atlantic. Equatorial wave dynamics is at the origin of their developments. Wind anomalies in the Western Equatorial Atlantic force equatorial downwelling and upwelling Kelvin waves that propagate eastward along the equator and then poleward along the African coast triggering extreme warm and cold events, respectively. A proxy index based on linear ocean dynamics appears to be significantly more correlated with coastal variability than an index based on wind variability. Results show a seasonal phasing, with significantly higher correlations between our equatorial index and coastal SSTA in October-April season.

  3. Multiscale empirical modeling of the geomagnetic field: From storms to substorms

    Science.gov (United States)

    Stephens, G. K.; Sitnov, M. I.; Korth, H.; Gkioulidou, M.; Ukhorskiy, A. Y.; Merkin, V. G.

    2017-12-01

    An advanced version of the TS07D empirical geomagnetic field model, herein called SST17, is used to model the global picture of the geomagnetic field and its characteristic variations on both storm and substorm scales. The new SST17 model uses two regular expansions describing the equatorial currents with each having distinctly different scales, one corresponding to a thick and one to a thin current sheet relative to the thermal ion gyroradius. These expansions have an arbitrary distribution of currents in the equatorial plane that is constrained only by magnetometer data. This multi-scale description allows one to reproduce the current sheet thinning during the growth phase. Additionaly, the model uses a flexible description of field-aligned currents that reproduces their spiral structure at low altitudes and provides a continuous transition from region 1 to region 2 current systems. The empirical picture of substorms is obtained by combining magnetometer data from Geotail, THEMIS, Van Allen Probes, Cluster II, Polar, IMP-8, GOES 8, 9, 10 and 12 and then binning this data based on similar values of the auroral index AL, its time derivative and the integral of the solar wind electric field parameter (from ACE, Wind, and IMP-8) in time over substorm scales. The performance of the model is demonstrated for several events, including the 3 July 2012 substorm, which had multi-probe coverage and a series of substorms during the March 2008 storm. It is shown that the AL binning helps reproduce dipolarization signatures in the northward magnetic field Bz, while the solar wind electric field integral allows one to capture the current sheet thinning during the growth phase. The model allows one to trace the substorm dipolarization from the tail to the inner magnetosphere where the dipolarization of strongly stretched tail field lines causes a redistribution of the tail current resulting in an enhancement of the partial ring current in the premidnight sector.

  4. Ionospheric Response to the Magnetic Storm of 22 June 2015

    Science.gov (United States)

    Mansilla, Gustavo A.

    2018-03-01

    A global study is made of the response of the total electron content of the ionosphere (TEC) to the geomagnetic storm occurred on 22 June 2015 (one of the strongest geomagnetic storms of the current Solar Cycle 24). Using data from 44 sites, a hemispheric comparison is made by considering high latitudes (> 50°), middle latitudes (30°-50°) and low latitudes (30°N-30°S). The main features observed were: increases in TEC at high latitudes prior to the storm main phase, a considerable asymmetry of TEC response at middle and low latitudes of the Northern Hemisphere and the Southern Hemisphere and decreases at equatorial latitudes. The long duration enhancements in TEC were well correlated with increases in the O/N2 ratio but decreases in TEC had not associated decreases in the O/N2 ratio as occur with the decreases in the electron density. Besides, prompt penetration electric fields can play an important role in the equatorial and low-latitude ionosphere during main phase of the storm.

  5. Post-midnight occurrence of equatorial plasma bubbles

    Science.gov (United States)

    Ajith, K. K.; Otsuka, Yuichi; Yamamoto, Mamoru; Yokoyama, Tatsuhiro; Tulasiram, S.

    2016-07-01

    The equatorial plasma bubbles (EPBs)/equatorial spread F (ESF) irregularities are an important topic of space weather interest because of their impact on transionospheric radio communications, satellite-based navigation and augmentation systems. This local plasma depleted structures develop at the bottom side F layer through Rayleigh-Taylor instability and rapidly grow to topside ionosphere via polarization electric fields within them. The steep vertical gradients due to quick loss of bottom side ionization and rapid uplift of equatorial F layer via prereversal enhancement (PRE) of zonal electric field makes the post-sunset hours as the most preferred local time for the formation of EPBs. However, there is a different class of irregularities that occurs during the post-midnight hours of June solstice reported by the previous studies. The occurrence of these post-midnight EPBs maximize during the low solar activity periods. The growth characteristics and the responsible mechanism for the formation of these post-midnight EPBs are not yet understood. Using the rapid beam steering ability of 47 MHz Equatorial Atmosphere Radar (EAR) at Kototabang (0.2°S geographic latitude, 100.3°E geographic longitude, and 10.4°S geomagnetic latitude), Indonesia, the spatial and temporal evolution of equatorial plasma bubbles (EPBs) were examined to classify the evolutionary-type EPBs from those which formed elsewhere and drifted into the field of view of radar. The responsible mechanism for the genesis of summer time post-midnight EPBs were discussed in light of growth rate of Rayleigh-Taylor instability using SAMI2 model.

  6. Day-to-day correlation of equatorial electrojet at two stations separated by 2000 km

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    2007-05-01

    Full Text Available Day-to-day fluctuations of the daily range of the geomagnetic field H at the equatorial electrojet stations Ancon (ANC, 77.0° W and Sao Luis (SLZ, 44.2° W are described for the period January–June 1993. The H field started increasing between midnight and sunrise, reaching a peak shortly before noon. The daily range of H was maximum during March and April and minimum during June. Regardless of the month, the range in H was significantly larger at ANC than at SLZ. The 27-day running mean of the range of H varied from 80 nT to 125 nT at SLZ and from 105 nT to 180 nT at ANC. The day-to-day values of the range of H showed very faithful variations at the two stations. The deviations of the daily range of H from its 27-day running mean values showed good correlation between the two stations. Some large storm-time effects were seen at both stations. The correlation was still significant, when data were corrected for Dst index values. It is suggested that the range in H at the two electrojet stations, separated by more than 2000 km, are affected by some common sources other than the ring current, which need to be identified. Spectral analysis of the range of H shows remarkable similarity at the two stations, with a dominant period of 15 days at both stations.

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

    Science.gov (United States)

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

    2014-07-01

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

  8. Transient, Small-Scale Field-Aligned Currents in the Plasma Sheet Boundary Layer During Storm Time Substorms

    Science.gov (United States)

    Nakamura, R.; Sergeev, V. A.; Baumjohann, W.; Plaschke, F.; Magnes, W.; Fischer, D.; Varsani, A.; Schmid, D.; Nakamura, T. K. M.; Russell, C. T.; hide

    2016-01-01

    We report on field-aligned current observations by the four Magnetospheric Multiscale (MMS) spacecraft near the plasma sheet boundary layer (PSBL) during two major substorms on 23 June 2015. Small-scale field-aligned currents were found embedded in fluctuating PSBL flux tubes near the Separatrix region. We resolve, for the first time, short-lived earthward (downward) intense field-aligned current sheets with thicknesses of a few tens of kilometers, which are well below the ion scale, on flux tubes moving equatorward earth ward during outward plasma sheet expansion. They coincide with upward field-aligned electron beams with energies of a few hundred eV. These electrons are most likely due to acceleration associated with a reconnection jet or high-energy ion beam-produced disturbances. The observations highlight coupling of multiscale processes in PSBL as a consequence of magnetotail reconnection.

  9. Thyroid storm precipitated by acute biliary pancreatitis

    Directory of Open Access Journals (Sweden)

    Mehrdad Karimi

    2017-01-01

    Full Text Available Thyroid storm is an acute, life-threatening exacerbation and sudden releasing large amounts of thyroid hormone in a short period of time. Nevertheless, critical aggravation of hyperthyroidism typically resulted from concurrent disorder. Synchronous management of thyroid storm along with its precipitant, such as infection is recommended. We described the case of an acute biliary pancreatitis complicated with a thyroid storm. The patient was successfully managed with a quick surgical intervention and further critical care for thyroid storm. Although it is widely believed that pancreatitis is seldom concurrent with thyrotoxicosis, thyroid storm can be precipitated by a variety of factors, including intra-abdominal infections such as acute pancreatitis or perforated peptic ulcer. In conclusion, acute pancreatitis in patients with thyrotoxicosis seems to be extremely rare, but such patients should be managed intensively against underlying thyroid disorders as well as pancreatitis.

  10. Evaluation of NWP-based Satellite Precipitation Error Correction with Near-Real-Time Model Products and Flood-inducing Storms

    Science.gov (United States)

    Zhang, X.; Anagnostou, E. N.; Schwartz, C. S.

    2017-12-01

    Satellite precipitation products tend to have significant biases over complex terrain. Our research investigates a statistical approach for satellite precipitation adjustment based solely on numerical weather simulations. This approach has been evaluated in two mid-latitude (Zhang et al. 2013*1, Zhang et al. 2016*2) and three topical mountainous regions by using the WRF model to adjust two high-resolution satellite products i) National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center morphing technique (CMORPH) and ii) Global Satellite Mapping of Precipitation (GSMaP). Results show the adjustment effectively reduces the satellite underestimation of high rain rates, which provides a solid proof-of-concept for continuing research of NWP-based satellite correction. In this study we investigate the feasibility of using NCAR Real-time Ensemble Forecasts*3 for adjusting near-real-time satellite precipitation datasets over complex terrain areas in the Continental United States (CONUS) such as Olympic Peninsula, California coastal mountain ranges, Rocky Mountains and South Appalachians. The research will focus on flood-inducing storms occurred from May 2015 to December 2016 and four satellite precipitation products (CMORPH, GSMaP, PERSIANN-CCS and IMERG). The error correction performance evaluation will be based on comparisons against the gauge-adjusted Stage IV precipitation data. *1 Zhang, Xinxuan, et al. "Using NWP simulations in satellite rainfall estimation of heavy precipitation events over mountainous areas." Journal of Hydrometeorology 14.6 (2013): 1844-1858. *2 Zhang, Xinxuan, et al. "Hydrologic Evaluation of NWP-Adjusted CMORPH Estimates of Hurricane-Induced Precipitation in the Southern Appalachians." Journal of Hydrometeorology 17.4 (2016): 1087-1099. *3 Schwartz, Craig S., et al. "NCAR's experimental real-time convection-allowing ensemble prediction system." Weather and Forecasting 30.6 (2015): 1645-1654.

  11. Perturbation electric fields and disturbance currents investigated during the 25 September 1998 great storm

    Science.gov (United States)

    Horvath, Ildiko; Lovell, Brian C.

    2014-10-01

    This study investigates the ionosphere's response to the 25 September 1998 great storm and utilizes multi-instrument observations covering the Australian (140°E; geographic) and Indian (75°E) longitude sectors. Results show the domination of eastward (westward) electrojet at 140°E (75°E). Its causative net eastward (westward) perturbation electric (E) field drove the forward (reverse) plasma fountain, caused the presence (absence) of the equatorial ionization anomaly (EIA). These strong longitudinal differences were due to a combination of various LT-dependent, E field-driven, and competing mechanisms. Perturbation E fields are identified as prompt penetration E field (PPEF) and disturbance dynamo E field (DDEF). Due to the later (earlier) local time at 140°E (75°E), the undershielding PPEF was eastward (westward) directed early in the main phase. A series of periodic substorms occurred during the recovery phase. The substorm-related eastward PPEFs became overpowered by westward DDEFs over India but remained dominant in the Australian sector. Thus, eastward PPEFs (westward DDEFs) dominated at 140°E (75°E). At 140°E these eastward PPEFs exhibited a strong positive correlation with the variations of both the cross polar cap potential drop and the asymmetric ring current, significantly increased the net equatorial upward E × B drift and thus caused EIA development with plasma bubbles scintillating GPS signals. Based on the strong and independent correlation of these asymmetric ring current events with both the EIA development and the scintillation activity, we propose that the ASY-H index could provide a natural tool for modeling EIA development and scintillation episodes during severe storms characterized by periodic substorm-related eastward PPEFs.

  12. EQUATORIAL SUPERROTATION ON TIDALLY LOCKED EXOPLANETS

    International Nuclear Information System (INIS)

    Showman, Adam P.; Polvani, Lorenzo M.

    2011-01-01

    The increasing richness of exoplanet observations has motivated a variety of three-dimensional (3D) atmospheric circulation models of these planets. Under strongly irradiated conditions, models of tidally locked, short-period planets (both hot Jupiters and terrestrial planets) tend to exhibit a circulation dominated by a fast eastward, or 'superrotating', jet stream at the equator. When the radiative and advection timescales are comparable, this phenomenon can cause the hottest regions to be displaced eastward from the substellar point by tens of degrees longitude. Such an offset has been subsequently observed on HD 189733b, supporting the possibility of equatorial jets on short-period exoplanets. Despite its relevance, however, the dynamical mechanisms responsible for generating the equatorial superrotation in such models have not been identified. Here, we show that the equatorial jet results from the interaction of the mean flow with standing Rossby waves induced by the day-night thermal forcing. The strong longitudinal variations in radiative heating-namely intense dayside heating and nightside cooling-trigger the formation of standing, planetary-scale equatorial Rossby and Kelvin waves. The Rossby waves develop phase tilts that pump eastward momentum from high latitudes to the equator, thereby inducing equatorial superrotation. We present an analytic theory demonstrating this mechanism and explore its properties in a hierarchy of one-layer (shallow-water) calculations and fully 3D models. The wave-mean-flow interaction produces an equatorial jet whose latitudinal width is comparable to that of the Rossby waves, namely the equatorial Rossby deformation radius modified by radiative and frictional effects. For conditions typical of synchronously rotating hot Jupiters, this length is comparable to a planetary radius, explaining the broad scale of the equatorial jet obtained in most hot-Jupiter models. Our theory illuminates the dependence of the equatorial jet

  13. Predicting Tropical Cyclogenesis with a Global Mesoscale Model: Preliminary Results with Very Severe Cyclonic Storm Nargis (2008)

    Science.gov (United States)

    Shen, B.; Tao, W.; Atlas, R.

    2008-12-01

    Very Severe Cyclonic Storm Nargis, the deadliest named tropical cyclone (TC) in the North Indian Ocean Basin, devastated Burma (Myanmar) in May 2008, causing tremendous damage and numerous fatalities. An increased lead time in the prediction of TC Nargis would have increased the warning time and may therefore have saved lives and reduced economic damage. Recent advances in high-resolution global models and supercomputers have shown the potential for improving TC track and intensity forecasts, presumably by improving multi-scale simulations. The key but challenging questions to be answered include: (1) if and how realistic, in terms of timing, location and TC general structure, the global mesoscale model (GMM) can simulate TC genesis and (2) under what conditions can the model extend the lead time of TC genesis forecasts. In this study, we focus on genesis prediction for TCs in the Indian Ocean with the GMM. Preliminary real-data simulations show that the initial formation and intensity variations of TC Nargis can be realistically predicted at a lead time of up to 5 days. These simulations also suggest that the accurate representations of a westerly wind burst (WWB) and an equatorial trough, associated with monsoon circulations and/or a Madden-Julian Oscillation (MJO), are important for predicting the formation of this kind of TC. In addition to the WWB and equatorial trough, other favorable environmental conditions will be examined, which include enhanced monsoonal circulation, upper-level outflow, low- and middle-level moistening, and surface fluxes.

  14. Midlatitude Plasma Bubbles Over China and Adjacent Areas During a Magnetic Storm on 8 September 2017

    Science.gov (United States)

    Aa, Ercha; Huang, Wengeng; Liu, Siqing; Ridley, Aaron; Zou, Shasha; Shi, Liqin; Chen, Yanhong; Shen, Hua; Yuan, Tianjiao; Li, Jianyong; Wang, Tan

    2018-03-01

    This paper presents observations of postsunset super plasma bubbles over China and adjacent areas during the second main phase of a storm on 8 September 2017. The signatures of the plasma bubbles can be seen or deduced from (1) deep field-aligned total electron content depletions embedded in regional ionospheric maps derived from dense Global Navigation Satellite System networks, (2) significant equatorial and midlatitudinal plasma bite-outs in electron density measurements on board Swarm satellites, and (3) enhancements of ionosonde virtual height and scintillation in local evening associated with strong southward interplanetary magnetic field. The bubbles/depletions covered a broad area mainly within 20°-45°N and 80°-110°E with bifurcated structures and persisted for nearly 5 hr (˜13-18 UT). One prominent feature is that the bubbles extended remarkably along the magnetic field lines in the form of depleted flux tubes, reaching up to midlatitude of around 50°N (magnetic latitude: 45.5°N) that maps to an altitude of 6,600 km over the magnetic equator. The maximum upward drift speed of the bubbles over the magnetic equator was about 700 m/s and gradually decreased with altitude and time. The possible triggering mechanism of the plasma bubbles was estimated to be storm time eastward prompt penetration electric field, while the traveling ionospheric disturbance could play a role in facilitating the latitudinal extension of the depletions.

  15. Studies of 212Pb storm

    International Nuclear Information System (INIS)

    Yunoki, E.; Kataoka, T.; Michihiro, K.; Sugiyama, H.; Shimizu, M.; Mori, T.

    1996-01-01

    212 Pb which reached its equilibrium state with its daughters in the air was measured around small uranium mines in Japan. Environmental. 212 Pb concentrations rose suddenly and reached a value ten times as high as usual values. These Phenomena were observed many times during the past six Years. We called these Phenomena 212 Pb storms. Meteorological conditions lead to the variations of 220 Rn progeny concentrations. These phenomena have been studied in the point of meteorology. (author)

  16. Common origin of positive ionospheric storms at middle latitudes and the geomagnetic activity effect at low latitudes

    International Nuclear Information System (INIS)

    Proelss, G.W.

    1993-01-01

    The author looks for a correlation between two different atmospheric effects. They are a positive atmospheric storm (an anomalous increase in the F2 region ionization density), observed at middle latitudes, and the geomagnetic activity effect (the anomalous changes of temperature and gas density seen in the thermosphere), observed at low latitudes. A temporal correlation is sought to test the argument that both of these effects are the result of travelling atmospheric disturbances (TAD). A TAD is a pulselike atmospheric wave thought to be generated by substorm activity, and to propagate with high velocity (600 m/s) from polar latitudes toward equatorial latitudes. The author looks at data from five separate events correlating magnetic, ionospheric, and neutral atmospheric measurements. The conclusion is that there is a positive correlation between magnetic substorm activity at high latitudes, and positive ionospheric storms at middle latitudes and geomagnetic activity at low latitudes. The time correlations are consistent with high propagation speeds between these events. The author also presents arguments which indicate that the middle latitude positive ionospheric storms are not the result of electric field effects

  17. Disturbance in the Tropical Ionosphere and Earth Magnetic Field Mensured on the Magnetic Equator Caused by Magnetic Storms

    Science.gov (United States)

    Almeida, Pedro; Sobral, José; Resende, Laysa; Marcos Denardini, Clezio; Carlotto Aveiro, Henrique

    The focus of the present work is to monitor the disturbances in the equatorial F region caused by magnetic storms and comparatively to observe possible effects caused by the storms in the earth magnetics field measured on the ground, aiming to establish the events time occurrence order. The motivation for this work is due to the diversity of phenomena of scientific interest, which are observed in this region and also are capable to disturbance the transionospheric communication. The monitoring on the ionospheric plasma variation in the F region during and after the magnetics storms can generate indications of magnetosphere - ionosphere coupling effects. For this study we have used F region parameters measured by digital sounder installed at the Observatório Espacial de São Lú (2.33° S; 44.20° W; -0.5° DIP): foF2 (critical frequency o a ıs of F layer), hmF2 (real height of electronic density F layer peak) and h'F (minimum virtual height of F layer). For monitoring the disturbance in the magnetic field we have studied the H- and Z-component of the Earth magnetic field measured by magnetometers installed in the same site. The results are presented and discussed.

  18. Nippon Storm Study design

    Directory of Open Access Journals (Sweden)

    Takashi Kurita

    2012-10-01

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

  19. Assessing storm erosion hazards

    NARCIS (Netherlands)

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

    2017-01-01

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

  20. Equatorial enhancement of the nighttime OH mesospheric infrared airglow

    International Nuclear Information System (INIS)

    Baker, D J; Thurgood, B K; Harrison, W K; Mlynczak, M G; Russell, J M

    2007-01-01

    Global measurements of the hydroxyl mesospheric airglow over an extended period of time have been made possible by the NASA SABER infrared sensor aboard the TIMED satellite which has been functioning since December of 2001. The orbital mission has continued over a significant portion of a solar cycle. Experimental data from SABER for several years have exhibited equatorial enhancements of the nighttime mesospheric OH (Δv=2) airglow layer consistent with the high average diurnal solar flux. The brightening of the OH airglow typically means more H+O 3 is being reacted. At both the spring and autumn seasonal equinoxes when the equatorial solar UV irradiance mean is greatest, the peak volume emission rate (VER) of the nighttime Meinel infrared airglow typically appears to be both significantly brighter plus lower in altitude by several kilometres at low latitudes compared with midlatitude findings

  1. Photoelectric panel with equatorial mounting of drive

    Science.gov (United States)

    Kukhta, M. S.; Krauinsh, P. Y.; Krauinsh, D. P.; Sokolov, A. P.; Mainy, S. B.

    2018-03-01

    The relevance of the work is determined by the need to create effective models for sunny energy. The article considers a photoelectric panel equipped with a system for tracking the sun. Efficiency of the system is provided by equatorial mounting, which compensates for the rotation of the Earth by rotating the sunny panel in the plane of the celestial equator. The specificity of climatic and geographical conditions of Tomsk is estimated. The dynamics of power variations of photoelectric panels with equatorial mounting during seasonal fluctuations in Tomsk is calculated. A mobile photovoltaic panel with equatorial mounting of the drive has been developed. The methods of design strategy for placing photovoltaic panels in the architectural environment of the city are presented. Key words: sunny energy, photovoltaics, equatorial mounting, mechatronic model, wave reducer, electric drive.

  2. Geometric effects of ICMEs on geomagnetic storms

    Science.gov (United States)

    Cho, KyungSuk; Lee, Jae-Ok

    2017-04-01

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

  3. Predicting severe winter coastal storm damage

    International Nuclear Information System (INIS)

    Hondula, David M; Dolan, Robert

    2010-01-01

    Over the past 40 years residents of, and visitors to, the North Carolina coastal barrier islands have experienced the destructive forces of several 'named' extratropical storms. These storms have caused large-scale redistributions of sand and loss of coastal structures and infrastructure. While most of the population living on the islands are familiar with the wintertime storms, the damage and scars of the 'super northeasters'-such as the Ash Wednesday storm of 7 March 1962, and the Halloween storm of 1989-are slipping away from the public's memory. In this research we compared the damage zones of the 1962 Ash Wednesday storm, as depicted on aerial photographs taken after the storm, with photos taken of the same areas in 2003. With these high-resolution aerial photos we were able to estimate the extent of new development which has taken place along the Outer Banks of North Carolina since 1962. Three damage zones were defined that extend across the islands from the ocean landward on the 1962 aerial photos: (1) the zone of almost total destruction on the seaward edge of the islands where the storm waves break; (2) the zone immediately inland where moderate structural damage occurs during severe storms; and (3) the zone of flood damage at the landward margin of the storm surge and overwash. We considered the rate of coastal erosion, the rate of development, and increases in property values as factors which may contribute to changing the financial risk for coastal communities. In comparing the values of these four factors with the 1962 damage data, we produced a predicted dollar value for storm damage should another storm of the magnitude of the 1962 Ash Wednesday storm occur in the present decade. This model also provides an opportunity to estimate the rate of increase in the potential losses through time as shoreline erosion continues to progressively reduce the buffer between the development and the edge of the sea. Our data suggest that the losses along the North

  4. Predicting severe winter coastal storm damage

    Energy Technology Data Exchange (ETDEWEB)

    Hondula, David M; Dolan, Robert, E-mail: hondula@virginia.edu [Department of Environmental Sciences, University of Virginia, PO Box 400123, Charlottesville, VA 22903 (United States)

    2010-07-15

    Over the past 40 years residents of, and visitors to, the North Carolina coastal barrier islands have experienced the destructive forces of several 'named' extratropical storms. These storms have caused large-scale redistributions of sand and loss of coastal structures and infrastructure. While most of the population living on the islands are familiar with the wintertime storms, the damage and scars of the 'super northeasters'-such as the Ash Wednesday storm of 7 March 1962, and the Halloween storm of 1989-are slipping away from the public's memory. In this research we compared the damage zones of the 1962 Ash Wednesday storm, as depicted on aerial photographs taken after the storm, with photos taken of the same areas in 2003. With these high-resolution aerial photos we were able to estimate the extent of new development which has taken place along the Outer Banks of North Carolina since 1962. Three damage zones were defined that extend across the islands from the ocean landward on the 1962 aerial photos: (1) the zone of almost total destruction on the seaward edge of the islands where the storm waves break; (2) the zone immediately inland where moderate structural damage occurs during severe storms; and (3) the zone of flood damage at the landward margin of the storm surge and overwash. We considered the rate of coastal erosion, the rate of development, and increases in property values as factors which may contribute to changing the financial risk for coastal communities. In comparing the values of these four factors with the 1962 damage data, we produced a predicted dollar value for storm damage should another storm of the magnitude of the 1962 Ash Wednesday storm occur in the present decade. This model also provides an opportunity to estimate the rate of increase in the potential losses through time as shoreline erosion continues to progressively reduce the buffer between the development and the edge of the sea. Our data suggest that the

  5. Predicting severe winter coastal storm damage

    Science.gov (United States)

    Hondula, David M.; Dolan, Robert

    2010-07-01

    Over the past 40 years residents of, and visitors to, the North Carolina coastal barrier islands have experienced the destructive forces of several 'named' extratropical storms. These storms have caused large-scale redistributions of sand and loss of coastal structures and infrastructure. While most of the population living on the islands are familiar with the wintertime storms, the damage and scars of the 'super northeasters'—such as the Ash Wednesday storm of 7 March 1962, and the Halloween storm of 1989—are slipping away from the public's memory. In this research we compared the damage zones of the 1962 Ash Wednesday storm, as depicted on aerial photographs taken after the storm, with photos taken of the same areas in 2003. With these high-resolution aerial photos we were able to estimate the extent of new development which has taken place along the Outer Banks of North Carolina since 1962. Three damage zones were defined that extend across the islands from the ocean landward on the 1962 aerial photos: (1) the zone of almost total destruction on the seaward edge of the islands where the storm waves break; (2) the zone immediately inland where moderate structural damage occurs during severe storms; and (3) the zone of flood damage at the landward margin of the storm surge and overwash. We considered the rate of coastal erosion, the rate of development, and increases in property values as factors which may contribute to changing the financial risk for coastal communities. In comparing the values of these four factors with the 1962 damage data, we produced a predicted dollar value for storm damage should another storm of the magnitude of the 1962 Ash Wednesday storm occur in the present decade. This model also provides an opportunity to estimate the rate of increase in the potential losses through time as shoreline erosion continues to progressively reduce the buffer between the development and the edge of the sea. Our data suggest that the losses along the

  6. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    Directory of Open Access Journals (Sweden)

    E. Yizengaw

    2017-04-01

    Full Text Available It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ. The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998–2014 of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian have been analyzed. All observations performed during magnetically active periods (Kp>3 have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

  7. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    Energy Technology Data Exchange (ETDEWEB)

    Yizengaw, Endawoke [Boston College, Chestnut Hill, MA (United States). Inst. for Scientific Research; Carter, Brett A. [RMIT Univ., Melbourne, VIC (Australia). SPACE Research Centre

    2017-07-01

    It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998-2014) of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian) have been analyzed. All observations performed during magnetically active periods (K{sub p}>3) have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

  8. Longitudinal, seasonal and solar cycle variation in lunar tide influence on the equatorial electrojet

    International Nuclear Information System (INIS)

    Yizengaw, Endawoke; Carter, Brett A.

    2017-01-01

    It has been well documented that the lunar tidal waves can modulate the ionospheric electrodynamics and create a visible influence on the equatorial electrojet (EEJ). The lunar tide influence gets intensified around noon, primarily during new and full Moon periods. However, the longitudinal, seasonal and solar cycle variability in the lunar tide influence on ionospheric current systems is not well understood yet. In order to investigate this, 17 years (1998-2014) of extensive magnetometer observations at four longitudinal sectors (western American, western and eastern African, and Asian) have been analyzed. All observations performed during magnetically active periods (K p >3) have been excluded for this study to eliminate storm contributions to the geomagnetic field variation at the geomagnetic equator. This study's quantitative analysis revealed significant longitudinal, seasonal and solar cycle dependence of the lunar tide influence on the equatorial electrojet.

  9. Comparison of equatorial GPS-TEC observations over an African station and an American station during the minimum and ascending phases of solar cycle 24

    Directory of Open Access Journals (Sweden)

    A. O. Akala

    2013-11-01

    Full Text Available GPS-TEC data were observed at the same local time at two equatorial stations on both longitudes: Lagos (6.52° N, 3.4° E, 3.04° S magnetic latitude, Nigeria; and Pucallpa (8.38° S, 74.57° W, 4.25° N magnetic latitude, Peru during the minimum (2009, 2010 and ascending (2011 phases of solar cycle 24. These data were grouped into daily, seasonal and solar activity sets. The day-to-day variations in vertical TEC (VTEC recorded the maximum during 14:00–16:00 LT and minimum during 04:00–06:00 LT at both longitudes. Seasonally, during solar minimum, maximum VTEC values were observed during March equinox and minimum during solstices. However, during the ascending phase of the solar activity, the maximum values were recorded during the December solstice and minimum during the June solstice. VTEC also increased with solar activity at both longitudes. On longitude by longitude comparison, the African GPS station generally recorded higher VTEC values than the American GPS station. Furthermore, harmonic analysis technique was used to extract the annual and semi-annual components of the amplitudes of the TEC series at both stations. The semi-annual variations dominated the TEC series over the African equatorial station, while the annual variations dominated those over the American equatorial station. The GPS-TEC-derived averages for non-storm days were compared with the corresponding values derived by the IRI-2007 with the NeQuick topside option. The NeQuick option of IRI-2007 showed better performance at the American sector than the African sector, but generally underestimating TEC during the early morning hours at both longitudes.

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

    Science.gov (United States)

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

    2017-12-01

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

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

    Directory of Open Access Journals (Sweden)

    P. M. de Siqueira Negreti

    2017-12-01

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

  12. Healthcare4VideoStorm: Making Smart Decisions Based on Storm Metrics.

    Science.gov (United States)

    Zhang, Weishan; Duan, Pengcheng; Chen, Xiufeng; Lu, Qinghua

    2016-04-23

    Storm-based stream processing is widely used for real-time large-scale distributed processing. Knowing the run-time status and ensuring performance is critical to providing expected dependability for some applications, e.g., continuous video processing for security surveillance. The existing scheduling strategies' granularity is too coarse to have good performance, and mainly considers network resources without computing resources while scheduling. In this paper, we propose Healthcare4Storm, a framework that finds Storm insights based on Storm metrics to gain knowledge from the health status of an application, finally ending up with smart scheduling decisions. It takes into account both network and computing resources and conducts scheduling at a fine-grained level using tuples instead of topologies. The comprehensive evaluation shows that the proposed framework has good performance and can improve the dependability of the Storm-based applications.

  13. Global mode of Pi2 waves in the equatorial region

    International Nuclear Information System (INIS)

    Kitamura, Tai-ichi; Saka, Ousuke; Shimoizumi, Masashi

    1988-01-01

    Fluxgate magnetometers with accurate timing data logger were set up at two equatorial stations (Garous-Marous and Huancayo), and also at a middle latitude station (Kuju). The phase of Pi2 waves is compared among these stations. It is found that 1) Pi2 pulsations in low and equatorial latitudes are linearly polarized approximately along the magnetic meridian, 2) phase difference of the H component of Pi2 waves at different stations is much less than 1 - 10 of the pulsation period despite a large longitudinal separation (∼ 90 deg) of the stations, showing the so-called azimuthal wave number, m, to be much less than unity and 3) phase difference of the D component at different stations is variable. (author)

  14. Ongoing Analysis of Jupiter's Equatorial Hotspots and Plumes from Cassini

    Science.gov (United States)

    Choi, D. S.; Showmwn, A. P.; Vasavada, A. R.; Simon-Miller, A. A.

    2012-01-01

    We present updated results from our ongoing analysis of Cassini observations of Jupiter's equatorial meteorology. For two months preceding the spacecraft's closest approach of the planet, the ISS instrument onboard Cassini regularly imaged the atmosphere of Jupiter. We created time-lapse movies from this period that show the complex activity and interactions of the equatorial atmosphere. During this period, hot spots exhibited significant variations in size and shape over timescales of days and weeks. Some of these changes appear to be a result of interactions with passing vortex systems in adjacent latitudes. Strong anticyclonic gyres to the southeast of the dark areas converge with flow from the west and appear to circulate into a hot spot at its southwestern corner.

  15. Onset conditions for equatorial spread F

    International Nuclear Information System (INIS)

    Mendillo, M.; Baumgardner, J.; Xiaoqing Pi; Sultan, P.J.; Tsunoda, R.

    1992-01-01

    The problem of day-to-day variability in the occurrence of equatorial spread F (ESF) is addressed using multidiagnostic observations and semiempirical modeling. The observational results are derived from a two-night case study of ESF onset conditions observed at Kwajalein Atoll (Marshall Islands) using the ALTAIR incoherent scatter radar and all-sky optical imaging techniques. The major difference between nights when ESF instabilities did not occur (August 14, 1988) and did occur (August 15, 1988) in the Kwajalein sector was that the northern meridional gradient of 6300-angstrom airglow was reduced on the night of limited ESF activity. Modeling results suggest that this unusual airglow pattern is due to equatorward neutral winds. Previous researchers have shown that transequatorial thermospheric winds can exert a control over ESF seasonal and longitudinal occurrence patterns by inhibiting Rayleigh-Taylor instability growth rates. They present evidence to suggest that this picture can be extended to far shorter time scales, namely, that 'surges' in transequatoral winds acting over characteristic times of a few hours to a day can result in a stabilizing influence upon irregularity growth rates. The seemingly capricious nature of ESF onset may thus be controlled, in part, by the inherent variability of low-latitude thermospheric winds

  16. Computer simulation of inner magnetospheric dynamics for the magnetic storm of July 29, 1977

    International Nuclear Information System (INIS)

    Wolf, R.A.; Harel, M.; Spiro, R.W.; Voigt, G.; Reiff, P.H.; Chen, C.

    1982-01-01

    We present preliminary results of applying the Rice convection model to the early main phase of the magnetic storm of July 29, 1977. The computer model self-consistently computes electric fields and currents, as well as plasma distributions and velocities, in the inner-magnetosphere/ionosphere system. In the equatorial plane, the region modeled includes geocentric distances less than about the magnetopause standoff distance. Particle loss, parallel electric fields, and neutral winds are neglected. On the basis of solar wind parameters and the AL index as input, the model predicts the injection of plasma-sheet plasma to form a substantial storm time ring current. The total strength of the model-predicted ring current agrees accurately with the observed Dst index. Comparison of the model results with electric fields and Birkeland currents measured by S3-3 shows qualitative agreement but interesting quantitative discrepancies. During this event, region 1 currents, which in standard convection theory would connect to the outer magnetosphere, are observed as low as 60 0 invariant latitude at dawn and dusk. We examine the possibility that the magnetic field might be so highly inflated that 60 0 field lines extend to the outer magnetosphere. In the model, distortion of the inner edge of the plasma sheet by the magnetospheric compression associated with the sudden commencement temporarily disturbs the normal Birkeland-current pattern. The normal tendency for the plasma sheet's inner edge to shield low L alues from the convection electric field is also temporarily disrupted. Normal Birkeland currents and shielding reassert themselves after about an hour. Time-integrated Joule heating in the model ionosphere over the first 5.5 hours of the storm main phase is about half the increase in model ring-current energy

  17. Understanding the Longitudinal Variability of Equatorial Electrodynamics using integrated Ground- and Space-based Observations

    Science.gov (United States)

    Yizengaw, E.; Moldwin, M.; Zesta, E.

    2015-12-01

    The currently funded African Meridian B-Field Education and Research (AMBER) magnetometer array comprises more than thirteen magnetometers stationed globally in the vicinity of geomagnetic equator. One of the main objectives of AMBER network is to understand the longitudinal variability of equatorial electrodynamics as function of local time, magnetic activity, and season. While providing complete meridian observation in the region and filling the largest land-based gap in global magnetometer coverage, the AMBER array addresses two fundamental areas of space physics: first, the processes governing electrodynamics of the equatorial ionosphere as a function of latitude (or L-shell), local time, longitude, magnetic activity, and season, and second, ULF pulsation strength at low/mid-latitude regions and its connection with equatorial electrojet and density fluctuation. The global AMBER network can also be used to augment observations from space-based instruments, such us the triplet SWARM mission and the upcoming ICON missions. Thus, in coordination with space-based and other ground-based observations, the AMBER magnetometer network provides a great opportunity to understand the electrodynamics that governs equatorial ionosphere motions. In this paper we present the longitudinal variability of the equatorial electrodynamics using the combination of instruments onboard SWARM and C/NOFS satellites and ground-based AMBER network. Both ground- and pace-based observations show stronger dayside and evening sector equatorial electrodynamics in the American and Asian sectors compared to the African sector. On the other hand, the African sector is home to stronger and year-round ionospheric bubbles/irregularities compared to the American and Asian sectors. This raises the question if the evening sector equatorial electrodynamics (vertical drift), which is believed to be the main cause for the enhancement of Rayleigh-Taylor (RT) instability growth rate, is stronger in the

  18. Storm Data Publication

    Data.gov (United States)

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

  19. Plasma instabilities multifrequency study in equatorial electrojet

    International Nuclear Information System (INIS)

    Hanuise, C.

    1983-01-01

    In this thesis, multifrequential HF coherent radar results are presented, in the field plasma instabilities in equatorial electrojet. In a first part, characteristics of the irregularities observed either at the 3 meter wavelength by VHF radars, either at other wavelengths during pinpoint experiments, or in-situ by probe rockets are recalled. Theoretical studies progressed and are presented, at the same time with these experimental observations: instability linear theory, non linear theories, HF radar specificity, and problems associated to HF waves propagation and refraction in ionosphere. Original experimental results from Ethiopia are gathered in the second part. Plasma instability has been studied in different geophysical conditions and Doppler spectra characteristics are presented for each one of them. These characteristics are completely different according to the various cases; they are also different according to wether observations are made during the day in normal conditions (electric field pointed to the east at the equator) or in counter-electrojet conditions (electric field pointed to the west). The last part is concerned with theoretical interpretation of the previous results. A comprehensive view of the instability physical mechanisms, according to the geophysical conditions encountered, has been allowed by our results, VHF radar measurements at Jicamarca, or in situ probe measurements on the whole. Irregularities study has been limited to the E region [fr

  20. Earlier vegetation green-up has reduced spring dust storms.

    Science.gov (United States)

    Fan, Bihang; Guo, Li; Li, Ning; Chen, Jin; Lin, Henry; Zhang, Xiaoyang; Shen, Miaogen; Rao, Yuhan; Wang, Cong; Ma, Lei

    2014-10-24

    The observed decline of spring dust storms in Northeast Asia since the 1950s has been attributed to surface wind stilling. However, spring vegetation growth could also restrain dust storms through accumulating aboveground biomass and increasing surface roughness. To investigate the impacts of vegetation spring growth on dust storms, we examine the relationships between recorded spring dust storm outbreaks and satellite-derived vegetation green-up date in Inner Mongolia, Northern China from 1982 to 2008. We find a significant dampening effect of advanced vegetation growth on spring dust storms (r = 0.49, p = 0.01), with a one-day earlier green-up date corresponding to a decrease in annual spring dust storm outbreaks by 3%. Moreover, the higher correlation (r = 0.55, p storm outbreak ratio (the ratio of dust storm outbreaks to times of strong wind events) indicates that such effect is independent of changes in surface wind. Spatially, a negative correlation is detected between areas with advanced green-up dates and regional annual spring dust storms (r = -0.49, p = 0.01). This new insight is valuable for understanding dust storms dynamics under the changing climate. Our findings suggest that dust storms in Inner Mongolia will be further mitigated by the projected earlier vegetation green-up in the warming world.

  1. Storm surge climatology report

    OpenAIRE

    Horsburgh, Kevin; Williams, Joanne; Cussack, Caroline

    2017-01-01

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

  2. Meteorology of Jupiter's Equatorial Hot Spots and Plumes from Cassini

    Science.gov (United States)

    Choi, David Sanghun; Showman, Adam P.; Vasavada, Ashwin R.; Simon-Miller, Amy A.

    2013-01-01

    We present an updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes. Hot spots are relatively cloud-free regions that emit strongly at 5 lm; improved knowledge of these features is crucial for fully understanding Galileo probe measurements taken during its descent through one. Hot spots are quasistable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-like 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. These clouds travel at 150-200 m/s, much faster than the 100 m/s hot spot and plume drift speed. This raises the possibility that the scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. Most previously published zonal wind profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby wave controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed.

  3. What does the magnetic storm development depend on?

    International Nuclear Information System (INIS)

    Wodnicka, E.B.

    1991-01-01

    Adiabatic drift model applied to the magnetic storm development simulation reveals the significance of initial energy, initial pitch angle and the site of ions injection for the intensity, growth time and growth rate of a storm produced by two ion species - H + and O + . The most severe storms are caused by the ring current intensified by low initial pitch angle ions injected at low radial distance in the postmidnight local time region. (author)

  4. The oil boom in Equatorial Guinea

    International Nuclear Information System (INIS)

    Frynas, J.G.

    2004-01-01

    In less than a decade, Equatorial Guinea has transformed itself from an African backwater into one of the world's fastest growing economies and a sought-after political partner in the Gulf of Guinea. The sole reason for this transformation has been the discovery of oil and gas. This article outlines the rise of Equatorial Guinea as one of Africa's leading oil-producing countries and investigates the political, economic and social effects of becoming a petro-state. The article is based on the author's field research in Equatorial Guinea in the autumn of 2003 and interviews with senior oil company staff, government officials and staff of international organizations as well as secondary sources. This research demonstrates how reliance on oil and gas exports can lead to profound changes in a country's political economy. (author)

  5. Equatorial waves in the stratosphere of Uranus

    Science.gov (United States)

    Hinson, David P.; Magalhaes, Julio A.

    1991-01-01

    Analyses of radio occultation data from Voyager 2 have led to the discovery and characterization of an equatorial wave in the Uranus stratosphere. The observed quasi-periodic vertical atmospheric density variations are in close agreement with theoretical predictions for a wave that propagates vertically through the observed background structure of the stratosphere. Quantitative comparisons between measurements obtained at immersion and at emersion yielded constraints on the meridional and zonal structure of the wave; the fact that the two sets of measurements are correlated suggests a wave of planetary scale. Two equatorial wave models are proposed for the wave.

  6. Storm-enhanced plasma density and polar tongue of ionization development during the 15 May 2005 superstorm

    Science.gov (United States)

    Horvath, Ildiko; Lovell, Brian C.

    2015-06-01

    We investigate the ionosphere's global response to the 15 May 2005 superstorm in terms of storm evolution and ionospheric electrodynamics. Our aim is to study the global distribution of plasma and the resultant large-scale ionospheric features including the equatorial ionization anomaly (EIA), storm-enhanced density (SED), and polar tongue of ionization (TOI). We have combined multi-instrument ionospheric data, solar and terrestrial magnetic data, and polar convection maps. Results reveal the prompt penetration of the interplanetary electric field to the polar region and then to the equator with a dusk-to-dawn polarity during the initial phase and with a dawn-to-dusk polarity during the main phase. This drove during the initial phase a weak eastward equatorial electrojet (EEJ) in the American sector at nighttime and a weak westward EEJ in the Indian-Australian sector at daytime. During the main phase, these EEJs intensified and changed polarities. SED and polar TOI development was observed prior to and during the initial phase at evening-premidnight hours over North America and during the main phase in the south at afternoon-evening hours in the Australian sector. During the main phase and early in the recovery phase, the EIA-SED structure was well formed in the Asian longitude sector. Then, polar TOI development was absent in the north because of the long distance from the magnetic pole but was supported in the south because of the closeness of daytime cusp and magnetic pole. Thus, the EIA-SED-TOI structure developed twice but each time in a different longitude sector and with different characteristics.

  7. Examine Precipitation Extremes in Terms of Storm Properties

    Science.gov (United States)

    Jiang, P.; Yu, Z.; Chen, L.; Gautam, M. R.; Acharya, K.

    2017-12-01

    The increasing potential of the extreme precipitation is of significant societal concern. Changes in precipitation extremes have been mostly examined using extreme precipitation indices or Intensity-Duration-Frequency (IDF) analyses, which often fail to reveal the characteristics of an integrated precipitation event. In this study, we will examine the precipitation extremes in terms of storm properties including storm duration, storm intensity, total storm precipitation, and within storm pattern. Single storm event will be identified and storm properties will be determined based on the hourly precipitation time series in the selected locations in southwest United States. Three types of extreme precipitation event will be recognized using the criteria as (1) longest storm duration; (2) Highest storm intensity; and (3) largest total precipitation over a storm. The trend and variation of extreme precipitation events will be discussed for each criterion. Based on the comparisons of the characteristics of extreme precipitation events identified using different criteria, we will provide guidelines for choosing proper criteria for extreme precipitation analysis in specific location.

  8. Biological effects of geomagnetic storms

    International Nuclear Information System (INIS)

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

    1995-01-01

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

  9. Great magnetic storms

    International Nuclear Information System (INIS)

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

    1992-01-01

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

  10. Coccolithophores in the equatorial Atlantic Ocean

    DEFF Research Database (Denmark)

    Kinkel, Hanno; Baumann, K.-H.; Cepek, M.

    2000-01-01

    with each other. In general, the living coccolithophores in the surface and subsurface waters show considerable variation in cell numbers and distribution patterns. Cell densities reached a maximum of up to 300 x 10 coccospheres/l in the upwelling area of the equatorial Atlantic. Here, Emiliania huxleyi...

  11. Storm and cloud dynamics

    CERN Document Server

    Cotton, William R

    1992-01-01

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

  12. A case study of storm commencement and recovery plasmaspheric electric fields near L=2.5 at equinox

    Directory of Open Access Journals (Sweden)

    H. F. Balmforth (*

    Full Text Available Data from the VLF Doppler experiment at Faraday, Antarctica (65° S, 64° W are used to study the penetration of the high-latitude convection electric field to lower latitudes during severely disturbed conditions. Alterations of the electric field at L-values within the range 2.0 - 2.7 are studied for two cases at equinox (10 - 12 September 1986 and 1 - 3 May 1986. The recovery of the electric field is found to be approximately an exponential function of time. Values for the equatorial meridional E×B drift velocity, inferred from the data, are used as inputs to a model of the plasmasphere and ionosphere. The model and experimental results are used to investigate the post-storm alteration of ionospheric coupling processes. The magnitude of the effect of ionosphere-plasmasphere coupling fluxes on NmF2 values and the O+-H+ transition height is dependent on the local time of storm commencement, and on the orientation of the electric field. The coupling fluxes appear to have a maximum influence on ionospheric content during the main phase of geomagnetic activity that produces outward motion of plasmaspheric whistler ducts.

  13. Propagation of EMIC triggered emissions toward the magnetic equatorial plane

    Science.gov (United States)

    Grison, B.; Santolik, O.; Pickett, J. S.; Omura, Y.; Engebretson, M. J.; Dandouras, I. S.; Masson, A.; Decreau, P.; Cornilleau-Wehrlin, N.

    2011-12-01

    EMIC triggered emissions are observed close to the equatorial plane of the magnetosphere at locations where EMIC waves are commonly observed: close to the plasmapause region and in the dayside magnetosphere close to the magnetopause. Their overall characteristics (frequency with time dispersion, generation mechanism) make those waves the EMIC analogue of rising frequency whistler-mode chorus emissions. In our observations the Poynting flux of these emissions is usually clearly arriving from the equatorial region direction, especially when observations take place at more than 5 degrees of magnetic latitude. Simulations have also confirmed that the conditions of generation by interaction with energetic ions are at a maximum at the magnetic equator (lowest value of the background magnetic field along the field line). However in the Cluster case study presented here the Poynting flux of EMIC triggered emissions is propagating toward the equatorial region. The large angle between the wave vector and the background magnetic field is also unusual for this kind of emission. The rising tone starts just above half of the He+ gyrofrequency (Fhe+) and it disappears close to Fhe+. At the time of detection, the spacecraft magnetic latitude is larger than 10 degrees and L shell is about 4. The propagation sense of the emissions has been established using two independent methods: 1) sense of the parallel component of the Poynting flux for a single spacecraft and 2) timing of the emission detections at each of the four Cluster spacecraft which were in a relatively close configuration. We propose here to discuss this unexpected result considering a reflection of this emission at higher latitude.

  14. The StoRM Certification Process

    International Nuclear Information System (INIS)

    Ronchieri, Elisabetta; Dibenedetto, Michele; Zappi, Riccardo; Dal Pra, Stefano; Aiftimiei, Cristina; Traldi, Sergio

    2011-01-01

    StoRM is an implementation of the SRM interface version 2.2 used by all Large Hadron Collider (LHC) experiments and non-LHC experiments as SRM endpoint at different Tiers of Worldwide LHC Computing Grid. The complexity of its services and the demand of experiments and users are increasing day by day. The growing needs in terms of service level by the StoRM users communities make it necessary to design and implement a more effective testing procedure to quickly and reliably validate new StoRM candidate releases both in code side (for example via test units, and schema valuator) and in final product software (for example via functionality tests, and stress tests). Testing software service is a very critical quality activity performed in a very ad-hoc informal manner by developers, testers and users of StoRM up to now. In this paper, we describe the certification mechanism used by StoRM team to increase the robustness and reliability of the StoRM services. Various typologies of tests, such as quality, installation, configuration, functionality, stress and performance, defined on the base of a set of use cases gathered as consequence of the collaboration among the StoRM team, experiments and users, are illustrated. Each typology of test is either increased or decreased easily from time to time. The proposed mechanism is based on a new configurable testsuite. This is executed by the certification team, who is responsible for validating the release candidate package as well as bug fix (or patch) package, given a certain testbed that considers all possible use cases. In correspondence of each failure, the package is given back to developers waiting for validating a new package.

  15. The Role of Reversed Equatorial Zonal Transport in Terminating an ENSO Event

    Science.gov (United States)

    Chen, H. C.; Hu, Z. Z.; Huang, B.; Sui, C. H.

    2016-02-01

    In this study, we demonstrate that a sudden reversal of anomalous equatorial zonal current at the peaking ENSO phase triggers the rapid termination of an ENSO event. Throughout an ENSO cycle, the anomalous equatorial zonal current is strongly controlled by the concavity of the anomalous thermocline meridional structure near the equator. During the ENSO developing phase, the anomalous zonal current in the central and eastern Pacific generally enhances the ENSO growth through its zonal SST advection. In the mature phase of ENSO, however, the equatorial thermocline depth anomalies are reflected in the eastern Pacific and slowly propagate westward off the equator in both hemispheres. As a result, the concavity of the thermocline anomalies near the equator is reversed, i.e., the off-equatorial thermocline depth anomalies become higher than that on the equator for El Niño events and lower for La Niño events. This meridional change of thermocline structure reverses zonal transport rapidly in the central-to-eastern equatorial Pacific, which weakens the ENSO SST anomalies by reversed advection. More importantly, the reversed zonal mass transport weakens the existing zonal tilting of equatorial thermocline and suppresses the thermocline feedback. Both processes are concentrated in the eastern equatorial Pacific and can be effective on subseasonal time scales. These current reversal effects are built-in to the ENSO peak phase and independent of the zonal wind effect on thermocline slope. It functions as an oceanic control on ENSO evolution during both El Niño and La Niña events.

  16. California's Perfect Storm

    Science.gov (United States)

    Bacon, David

    2010-01-01

    The United States today faces an economic crisis worse than any since the Great Depression of the 1930s. Nowhere is it sharper than in the nation's schools. Last year, California saw a perfect storm of protest in virtually every part of its education system. K-12 teachers built coalitions with parents and students to fight for their jobs and their…

  17. Dave Storm esitleb singlit

    Index Scriptorium Estoniae

    2002-01-01

    7. märtsil klubis Spirit ja 8. märtsil klubis Terminal presenteerib tallinlane DJ Dave Storm oma uut singlit "Ride", millel teeb laulmisega kaasa ameeriklane Charlie C. Singelplaadi annab peadselt välja Inglise plaadifirma Refunkt

  18. Interview with Gert Storm

    NARCIS (Netherlands)

    Storm, Gerrit

    2013-01-01

    Gert Storm studied biology at the Utrecht University, The Netherlands, and obtained his PhD degree in 1987 at the Department of Pharmaceutics of the same university. He is now Professor of targeted drug delivery at the University of Utrecht, as well as Professor of targeted therapeutics at the MIRA

  19. Discovery Of A Rossby Wave In Jupiter's South Equatorial Region

    Science.gov (United States)

    Simon-Miller, Amy A.; Choi, D. S.; Rogers, J. H.; Gierasch, P. J.

    2012-01-01

    A detailed study of the chevron-shaped dark spots on the strong southern equatorial wind jet near 7.5 deg S planetographic latitude shows variations in velocity with longitude and time. The chevrons move with velocities near the maximum wind jet velocity of approx.140 m/s, as deduced by the history of velocities at this latitude and the magnitude of the symmetric wind jet near 7 deg N latitude. Their repetitive nature is consistent with an inertia-gravity wave (n = 75-100) with phase speed up to 25 m/s, relative to the local flow, but the identity of this wave mode is not well constrained. However, high spatial resolution movies from Cassini images show that the chevrons oscillate in latitude with a approx.7-day period. This oscillating motion has a wavelength of approx.20 deg and a speed of approx.100 m/s, following a pattern similar to that seen in the Rossby wave plumes of the North Equatorial Zone, and possibly reinforced by it, though they are not perfectly in phase. The transient anticyclonic South Equatorial Disturbance (SED) may be a similar wave feature, but moves at slower velocity. All data show chevron latitude variability, but it is unclear if this Rossby wave is present during other epochs, without time series movies that fully delineate it. In the presence of multiple wave modes, the difference in dominant cloud appearance between 7 deg N and 7.5 deg S may be due to the presence of the Great Red Spot, either through changes in stratification and stability or by acting as a wave boundary.

  20. Muon Excess at Sea Level during the Progress of a Geomagnetic Storm and High-Speed Stream Impact Near the Time of Earth's Heliospheric Sheet Crossing

    Science.gov (United States)

    Augusto, C. R. A.; Navia, C. E.; de Oliveira, M. N.; Nepomuceno, A. A.; Kopenkin, V.; Sinzi, T.

    2017-08-01

    In this article we present results of studying the association between the muon flux variation at ground level, registered by the New-Tupi muon telescopes (22° 53'00'' S, 43° 06'13' W; 3 m above sea level), and the geomagnetic storm on 25 - 29 August 2015 that has raged for several days as a result of a coronal mass ejection (CME) impact on Earth's magnetosphere. A sequence of events started with an M3.5 X-ray class flare on 22 August 2015 at 21:19 UTC. The New-Tupi muon telescopes observed a Forbush decrease (FD) triggered by this geomagnetic storm, which began on 26 August 2015. After Earth crossed the heliospheric current sheet (HCS), an increase in particle flux was observed on 28 August 2015 by spacecraft and ground-level detectors. The observed peak was in temporal coincidence with the impact of a high-speed stream (HSS). We study this increase, which has been observed with a significance above 1.5% by ground-level detectors in different rigidity regimes. We also estimate the lower limit of the energy fluence injected on Earth. In addition, we consider the origin of this increase, such as acceleration of particles by shock waves at the front of the HSS and the focusing effect of the HCS crossing. Our results show possible evidence of a prolonged energetic (up to GeV energies) particle injection within the Earth atmosphere system, driven by the HSS. In most cases, these injected particles are directed to the polar regions. However, the particles from the high-energy tail of the spectrum can reach mid-latitudes, and this could have consequences for the atmospheric chemistry. For instance, the creation of NOx species may be enhanced, and this can lead to increased ozone depletion. This topic requires further study.

  1. Progress in the Study of Coastal Storm Deposits

    Science.gov (United States)

    Xiong, Haixian; Huang, Guangqing; Fu, Shuqing; Qian, Peng

    2018-05-01

    Numerous studies have been carried out to identify storm deposits and decipher storm-induced sedimentary processes in coastal and shallow-marine areas. This study aims to provide an in-depth review on the study of coastal storm deposits from the following five aspects. 1) The formation of storm deposits is a function of hydrodynamic and sedimentary processes under the constraints of local geological and ecological factors. Many questions remain to demonstrate the genetic links between storm-related processes and a variety of resulting deposits such as overwash deposits, underwater deposits and hummocky cross-stratification (HCS). Future research into the formation of storm deposits should combine flume experiments, field observations and numerical simulations, and make full use of sediment source tracing methods. 2) Recently there has been rapid growth in the number of studies utilizing sediment provenance analysis to investigate the source of storm deposits. The development of source tracing techniques, such as mineral composition, magnetic susceptibility, microfossil and geochemical property, has allowed for better understanding of the depositional processes and environmental changes associated with coastal storms. 3) The role of extreme storms in the sedimentation of low-lying coastal wetlands with diverse ecosystem services has also drawn a great deal of attention. Many investigations have attempted to quantify widespread land loss, vertical marsh sediment accumulation and wetland elevation change induced by major hurricanes. 4) Paleostorm reconstructions based on storm sedimentary proxies have shown many advantages over the instrumental records and historic documents as they allow for the reconstruction of storm activities on millennial or longer time scales. Storm deposits having been used to establish proxies mainly include beach ridges and shelly cheniers, coral reefs, estuary-deltaic storm sequences and overwash deposits. Particularly over the past few

  2. Analysis of Storm Surge in Hong Kong

    Science.gov (United States)

    Kao, W. H.

    2017-12-01

    A storm surge is a type of coastal flood that is caused by low-pressure systems such as tropical cyclones. Storm surges caused by tropical cyclones can be very powerful and damaging, as they can flood coastal areas, and even destroy infrastructure in serious cases. Some serious cases of storm surges leading to more than thousands of deaths include Hurricane Katrina (2005) in New Orleans and Typhoon Haiyan (2013) in Philippines. Hong Kong is a coastal city that is prone to tropical cyclones, having an average of 5-6 tropical cyclones entering 500km range of Hong Kong per year. Storm surges have seriously damaged Hong Kong in the past, causing more than 100 deaths by Typhoon Wanda (1962), and leading to serious damage to Tai O and Cheung Chau by Typhoon Hagupit (2008). To prevent economic damage and casualties from storm surges, accurately predicting the height of storm surges and giving timely warnings to citizens is very important. In this project, I will be analyzing how different factors affect the height of storm surge, mainly using data from Hong Kong. These factors include the windspeed in Hong Kong, the atmospheric pressure in Hong Kong, the moon phase, the wind direction, the intensity of the tropical cyclone, distance between the tropical cyclone and Hong Kong, the direction of the tropical cyclone relative to Hong Kong, the speed of movement of the tropical cyclone and more. My findings will also be compared with cases from other places, to see if my findings also apply for other places.

  3. Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

    Directory of Open Access Journals (Sweden)

    S. Sharma

    2011-06-01

    Full Text Available Response of low latitude ionosphere to the geomagnetic storm of 15 May 2005 has been studied using total electron content (TEC data, obtained from three GPS stations namely, Yibal, Udaipur and Kunming situated near the northern crest of equatorial ionization anomaly at different longitudes. Solar wind parameters, north-south component of the interplanetary magnetic field (IMF Bz and AE index data have been used to infer the strength of the geomagnetic storm. A large value of eastward interplanetary electric field at 06:15 UT, during the time of maximum southward IMF Bz has been used to infer the transmission of an eastward prompt penetration electric field (PPEF which resulted in a peak in TEC at 07:45 UT due to the local uplift of plasma in the low latitudes near the anomaly crest over a wide range of longitudes. Wave-like modulations superposed over the second enhancement in TEC between 09:15 UT to 10:30 UT have been observed at all the three stations. The second enhancement in TEC along with the modulations of up to 5 TECU have been attributed to the combined effect of super plasma fountain and traveling atmospheric disturbances (TAD. Observed large enhancements in TEC are a cause of concern for satellite based navigation and ground positioning. Increased [O/N2] ratio between 09:15 UT to 10:15 UT when modulations in TEC have been also observed, confirms the presence of TADs over a wide range of longitudes.

  4. Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

    Science.gov (United States)

    Sharma, S.; Galav, P.; Dashora, N.; Pandey, R.

    2011-06-01

    Response of low latitude ionosphere to the geomagnetic storm of 15 May 2005 has been studied using total electron content (TEC) data, obtained from three GPS stations namely, Yibal, Udaipur and Kunming situated near the northern crest of equatorial ionization anomaly at different longitudes. Solar wind parameters, north-south component of the interplanetary magnetic field (IMF Bz) and AE index data have been used to infer the strength of the geomagnetic storm. A large value of eastward interplanetary electric field at 06:15 UT, during the time of maximum southward IMF Bz has been used to infer the transmission of an eastward prompt penetration electric field (PPEF) which resulted in a peak in TEC at 07:45 UT due to the local uplift of plasma in the low latitudes near the anomaly crest over a wide range of longitudes. Wave-like modulations superposed over the second enhancement in TEC between 09:15 UT to 10:30 UT have been observed at all the three stations. The second enhancement in TEC along with the modulations of up to 5 TECU have been attributed to the combined effect of super plasma fountain and traveling atmospheric disturbances (TAD). Observed large enhancements in TEC are a cause of concern for satellite based navigation and ground positioning. Increased [O/N2] ratio between 09:15 UT to 10:15 UT when modulations in TEC have been also observed, confirms the presence of TADs over a wide range of longitudes.

  5. Geomagnetic storm effects in ionospheric TEC at an euatorial station: contribution of EXB drifts and meridional neutral winds

    International Nuclear Information System (INIS)

    Dabas, R.S.; Jain, A.R.

    1985-01-01

    Storm-time variations in TEC measurements at the Indian station Ootacamund with IEC data for four stations in the anomaly region. Variations in Nsub(T)(OOTY) are found to be smaller compared to those observed at anomaly stations. The equatorial electrojet control of Nsub(T)(OOTY) is weaker compared to that of Nsub(m)F2. This result and absence of midday biteout in Nsub(T)(OOTY) are interpreted in terms of plasma exchange between ionosphere and plasmasphere which, to some extent, compensates the loss of plasma in the column due to E x B drifts. The anomaly depth is found to be well correlated with the electrojet strength. It is also noticed that for the same anomaly is weaker on a storm day than for quiet days. This is interpreted in terms of converging equatorward meridional winds. Thus, ionosphere-plasmasphere plasma exchange and, during disturbed period, the converging equatorward meridional winds also have significant effects on the distribution of ionization at these latitudes though the E x B drifts are most important in affecting the ionization distribution at low latitudes. (author)

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

    Science.gov (United States)

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

    2013-04-01

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

  7. Longitudinal Variation of the Lunar Tide in the Equatorial Electrojet

    Science.gov (United States)

    Yamazaki, Yosuke; Stolle, Claudia; Matzka, Jürgen; Siddiqui, Tarique A.; Lühr, Hermann; Alken, Patrick

    2017-12-01

    The atmospheric lunar tide is one known source of ionospheric variability. The subject received renewed attention as recent studies found a link between stratospheric sudden warmings and amplified lunar tidal perturbations in the equatorial ionosphere. There is increasing evidence from ground observations that the lunar tidal influence on the ionosphere depends on longitude. We use magnetic field measurements from the CHAMP satellite during July 2000 to September 2010 and from the two Swarm satellites during November 2013 to February 2017 to determine, for the first time, the complete seasonal-longitudinal climatology of the semidiurnal lunar tidal variation in the equatorial electrojet intensity. Significant longitudinal variability is found in the amplitude of the lunar tidal variation, while the longitudinal variability in the phase is small. The amplitude peaks in the Peruvian sector (˜285°E) during the Northern Hemisphere winter and equinoxes, and in the Brazilian sector (˜325°E) during the Northern Hemisphere summer. There are also local amplitude maxima at ˜55°E and ˜120°E. The longitudinal variation is partly due to the modulation of ionospheric conductivities by the inhomogeneous geomagnetic field. Another possible cause of the longitudinal variability is neutral wind forcing by nonmigrating lunar tides. A tidal spectrum analysis of the semidiurnal lunar tidal variation in the equatorial electrojet reveals the dominance of the westward propagating mode with zonal wave number 2 (SW2), with secondary contributions by westward propagating modes with zonal wave numbers 3 (SW3) and 4 (SW4). Eastward propagating waves are largely absent from the tidal spectrum. Further study will be required for the relative importance of ionospheric conductivities and nonmigrating lunar tides.

  8. The ionospheric response in the Brazilian sector during the super geomagnetic storm on 20 November 2003

    Directory of Open Access Journals (Sweden)

    F. Becker-Guedes

    2007-05-01

    Full Text Available A very intense geomagnetic storm (superstorm began with storm sudden commencement (SSC at 08:03 UT on 20 November 2003, as a result of the coronal mass ejection (CME by sunspot 484 hurled into space on 18 November 2003. The geomagnetic storm attained |Dst|max=472 nT at 20:00 UT (20 November. In this paper we present the simultaneous ionospheric sounding observations, using the Canadian Advanced Digital Ionosondes (CADIs, carried out from Palmas (PAL; 10.2° S, 48.2° W; dip latitude 5.5° S; a near equatorial station and São José dos Campos (SJC; 23.2° S, 45.9° W; dip latitude 17.6° S; station located under the crest of equatorial ionospheric anomaly, Brazil. In addition, total electron content (TEC measurements from several GPS receiving stations in the Brazilian sector during this storm are presented. The simultaneous ionospheric sounding observations carried out at SJC and PAL, and TEC observations on 3 consecutive days viz., 19 November (quiet, 20 November (disturbed and 21 November (recovery phase are presented. Salient features from the ionospheric observations in the Brazilian sector during the superstorm are discussed. The difference in the observed ionospheric response at the two stations (PAL and SJC is considerable. This is not surprising given that PAL is close to the magnetic equator and SJC is near the crest of the equatorial ionospheric anomaly (EIA. It should be pointed out that soon after the SSC (about 4 h later, the F-region critical frequency (foF2, the F-region peak height (hpF2, and variations of virtual heights at different frequencies (iso-frequency plots all show wavelike oscillations of the F-region during daytime at both the ionospheric sounding stations. Unusual rapid uplifting of F-region at PAL was observed during both the main and recovery phases of the storm.

  9. Mathematical modeling of tornadoes and squall storms

    Directory of Open Access Journals (Sweden)

    Sergey A. Arsen’yev

    2011-04-01

    Full Text Available Recent advances in modeling of tornadoes and twisters consist of significant achievements in mathematical calculation of occurrence and evolution of a violent F5-class tornado on the Fujita scale, and four-dimensional mathematical modeling of a tornado with the fourth coordinate time multiplied by its characteristic velocity. Such a tornado can arise in a thunderstorm supercell filled with turbulent whirlwinds. A theory of the squall storms is proposed. The squall storm is modeled by running perturbation of the temperature inversion on the lower boundary of cloudiness. This perturbation is induced by the action of strong, hurricane winds in the upper and middle troposphere, and looks like a running solitary wave (soliton; which is developed also in a field of pressure and velocity of a wind. If a soliton of a squall storm gets into the thunderstorm supercell then this soliton is captured by supercell. It leads to additional pressure fall of air inside a storm supercell and stimulate amplification of wind velocity here. As a result, a cyclostrophic balance inside a storm supercell generates a tornado. Comparison of the radial distribution of wind velocity inside a tornado calculated by using the new formulas and equations with radar observations of the wind velocity inside Texas Tornado Dummit in 1995 and inside the 3 May 1999 Oklahoma City Tornado shows good correspondence.

  10. Long wavelength irregularities in the equatorial electrojet

    OpenAIRE

    Kudeki, E.; Farley, D. T.; Fejer, Bela G.

    1982-01-01

    We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach...

  11. Study of the energy spectra of the major ion species in the ring-current region of the magnetosphere during geomagnetic storms

    International Nuclear Information System (INIS)

    Kistler, L.M.

    1987-01-01

    Using the University of Maryland/Max Planck Institute for Aeronomy Charge Energy Mass (CHEM) spectrometer on the AMPTE Charge Composition Explorer (CCE) spacecraft, the author examined the near-equatorial storm-time energy spectra of four major magnetospheric ions, H + , O + , He + , and He ++ over the energy range 1-300 keV/e in the L-range 3-6. The data were obtained during the main phase of all geomagnetic storms with minimum Dst less than -50 in the time period September 1984 to November 1985. During this period, the orbit of the CCE precessed such that the full range of local times was covered. When the spectra are organized by local time, certain features emerge. In particular, there is a dip in the spectra of all ions at 10-20 keV/e in the drawn-to-noon sector, while in the noon-to-dusk sector the proton distribution function drops off sharply below ∼5 keV. These spectra were compared with those predicted by a model of ion drift and loss in the magnetosphere. It was found that the spectra are most consistent with a Volland-Stern electric field with γ = 2 and with a rotation of the nominal dawn-to-dusk electric field eastward by two hours local time

  12. No iron fertilization in the equatorial Pacific Ocean during the last ice age.

    Science.gov (United States)

    Costa, K M; McManus, J F; Anderson, R F; Ren, H; Sigman, D M; Winckler, G; Fleisher, M Q; Marcantonio, F; Ravelo, A C

    2016-01-28

    The equatorial Pacific Ocean is one of the major high-nutrient, low-chlorophyll regions in the global ocean. In such regions, the consumption of the available macro-nutrients such as nitrate and phosphate is thought to be limited in part by the low abundance of the critical micro-nutrient iron. Greater atmospheric dust deposition could have fertilized the equatorial Pacific with iron during the last ice age--the Last Glacial Period (LGP)--but the effect of increased ice-age dust fluxes on primary productivity in the equatorial Pacific remains uncertain. Here we present meridional transects of dust (derived from the (232)Th proxy), phytoplankton productivity (using opal, (231)Pa/(230)Th and excess Ba), and the degree of nitrate consumption (using foraminifera-bound δ(15)N) from six cores in the central equatorial Pacific for the Holocene (0-10,000 years ago) and the LGP (17,000-27,000 years ago). We find that, although dust deposition in the central equatorial Pacific was two to three times greater in the LGP than in the Holocene, productivity was the same or lower, and the degree of nitrate consumption was the same. These biogeochemical findings suggest that the relatively greater ice-age dust fluxes were not large enough to provide substantial iron fertilization to the central equatorial Pacific. This may have been because the absolute rate of dust deposition in the LGP (although greater than the Holocene rate) was very low. The lower productivity coupled with unchanged nitrate consumption suggests that the subsurface major nutrient concentrations were lower in the central equatorial Pacific during the LGP. As these nutrients are today dominantly sourced from the Subantarctic Zone of the Southern Ocean, we propose that the central equatorial Pacific data are consistent with more nutrient consumption in the Subantarctic Zone, possibly owing to iron fertilization as a result of higher absolute dust fluxes in this region. Thus, ice-age iron fertilization in the

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

    Science.gov (United States)

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

    2015-04-01

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

  14. Thyroid storm precipitated by radioactive iodine therapy

    International Nuclear Information System (INIS)

    Redkar, Neelam N.; Rawat, Kavita J.; Yelale, Abhijit; Shivchand, Akshay

    2015-01-01

    Thyroid storm or thyrotoxic crisis is a rare but life-threatening condition requiring immediate treatment, preferably in an intensive care unit. Its incidence is about 1-2% among patients with overt hyperthyroidism. A thyrotoxic crisis occurs predominantly in the elderly and is three to five times more common in women than in men. The overall mortality is 10-20%. Even though the pathogenesis is still not fully understood, an increased sensitivity to catecholamines appears to be an important mechanism, and a number of endogenous and exogenous stress factors that can provoke the onset of a thyrotoxic storm have been identified. Authors presented a case where the cause of precipitation of thyroid storm was improper preparation of patient for Radioactive iodine treatment

  15. Leonid storm research

    CERN Document Server

    Rietmeijer, Frans; Brosch, Noah; Fonda, Mark

    2000-01-01

    This book will appeal to all researchers that have an interest in the current Leonid showers It contains over forty research papers that present some of the first observational results of the November 1999 Leonid meteor storm, the first storm observed by modern observing techniques The book is a first glimpse of the large amount of information obtained during NASA's Leonid Multi-Instrument Aircraft Campaign and groundbased campaigns throughout the world It provides an excellent overview on the state of meteor shower research for any professional researcher or amateur meteor observer interested in studies of meteors and meteoroids and their relation to comets, the origin of life on Earth, the satellite impact hazard issue, and upper atmosphere studies of neutral atom chemistry, the formation of meteoric debris, persistent trains, airglow, noctilucent clouds, sprites and elves

  16. Occurrence and zonal drifts of small-scale ionospheric irregularities over an equatorial station during solar maximum - Magnetic quiet and disturbed conditions

    Science.gov (United States)

    Muella, M. T. A. H.; de Paula, E. R.; Kantor, I. J.; Rezende, L. F. C.; Smorigo, P. F.

    2009-06-01

    A statistical study of L-band amplitude scintillations and zonal drift velocity of Fresnel-scale ionospheric irregularities is presented. Ground-based global positioning system (GPS) data acquired at the equatorial station of São Luís (2.33°S, 44.21°W, dip latitude 1.3°S), Brazil, during the solar maximum period from March 2001 to February 2002 are used in the analysis. The variation of scintillations and irregularity drift velocities with local time, season and magnetic activity are reported. The results reveal that for the near overhead ionosphere (satellite elevation angle >45°) a broad maximum in the occurrence of scintillation is seen from October to February. In general, weak scintillations (S 4 90%) during equinox (March-April; September-October) and December solstice (November-February) quiet time conditions and, many of the scintillations, occurred during pre-midnight hours. The mean zonal velocities of the irregularities are seen to be ˜30 m s -1 larger near December solstice, while during the equinoctial period the velocities decay faster and the scintillations tend to cease earlier. On geomagnetically disturbed nights, scintillation activity seems to be strongly affected by the prompt penetration of magnetospheric electric fields and disturbance dynamo effects. On disturbed days, during the equinox and December solstice seasons, the scintillations tend to be suppressed in the pre-midnight hours, whereas during June solstice months (May-August) the effect is opposite. In the post-midnight period, the mostly marked increase in the scintillation occurrence is observed during the equinox months. The results show that during disturbed conditions only one type of storm (when the main phase maximum takes place during the daytime hours) agrees with the Aarons' description, that is the suppression of L-band scintillations in the first recovery phase night. The results also reveal that the storm-time irregularity drifts become more spread in velocity and

  17. Dust storm, northern Mexico

    Science.gov (United States)

    1983-01-01

    This large dust storm along the left side of the photo, covers a large portion of the state of Coahuila, Mexico (27.5N, 102.0E). The look angle of this oblique photo is from the south to the north. In the foreground is the Sierra Madre Oriental in the states Coahuila and Nuevo Leon with the Rio Grande River, Amistad Reservoir and Texas in the background.

  18. Solar storms; Tormentas solares

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-01

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

  19. LibrarySTORM

    DEFF Research Database (Denmark)

    Breüner, Niels; Bech, Tine

    2013-01-01

    Når flere uddannelser samles i en nybygning til Campus C på Ceres grunden i Aarhus, skal der også indrettes et fælles bibliotek. Når der samtidig er midler til at arbejde med brugerdreven innovation, lå det lige for at inddrage de studerende og få deres visioner for fremtidens bibliotek. Der blev...... arrangeret en udviklingsdag, hvor der skulle brainstormes – og projektet blev kaldt LibrarySTORM....

  20. Modeling storm waves

    International Nuclear Information System (INIS)

    Benoit, M.; Marcos, F.; Teisson, Ch.

    1999-01-01

    Nuclear power stations located on the coast take the water they use to cool their circuits from the sea. The water intake and discharge devices must be able to operate in all weathers, notably during extreme storms, with waves 10 m high and over. To predict the impact of the waves on the equipment, they are modeled digitally from the moment they form in the middle of the ocean right up to the moment they break on the shore. (authors)

  1. Anthropogenic 236U recorded in annually banded coral skeleton at Majuro atoll, the equatorial Pacific

    International Nuclear Information System (INIS)

    Sakaguchi, Aya; Eto, Asuka; Takahashi, Yoshio; Steier, Peter; Yamazaki, Atsuko; Watanabe, Tsuyoshi; Sasaki, Keiichi; Yamano, Hiroya

    2013-01-01

    Historical 236 U/ 238 U atom ratio and concentration of 236 U were determined by Accelerator Mass Spectrometry (AMS) in skeletons of dated modern coral core sample collected from Majuro atoll, equatorial Pacific, to reconstruct anthropogenic 236 U inputs to the Equatorial Pacific. The maximum hydrogen bomb-pulses of 236 U/ 238 U and 236 U concentration, 2.83x10 -9 and 1.85x10 7 atom/g, in an annually resolved coral core were captured in 1954 (Operation Castle at Bikini and Enewetok atolls). The values were abruptly decreased in a few years, and they have been gradually decreased over time. Our results allow studies of not only the present distribution pattern, but gives access to the temporal evolution of 236 U in surface seawater of North Equatorial Current which is introduced to the Japan Sea and the North West Pacific Ocean as Kuroshio and Tsushima currents over the past decades. (author)

  2. Effects of the equatorial ionosphere on L-band Earth-space transmissions

    Science.gov (United States)

    Smith, Ernest K.; Flock, Warren L.

    1993-01-01

    Ionosphere scintillation can effect satellite telecommunication up to Ku-band. Nighttime scintillation can be attributed to large-scale inhomogeneity in the F-region of the ionosphere predominantly between heights of 200 and 600 km. Daytime scintillation has been attributed to sporadic E. It can be thought of as occurring in three belts: equatorial, high-latitude, and mid-latitude, in order of severity. Equatorial scintillation occurs between magnetic latitudes +/- 25 degrees, peaking near +/- 10 degrees. It commonly starts abruptly near 2000 local time and dies out shortly after midnight. There is a strong solar cycle dependence and a seasonal preference for the equinoxes, particularly the vernal one. Equatorial scintillation occurs more frequently on magnetically quiet than on magnetically disturbed days in most longitudes. At the peak of the sunspot cycle scintillation depths as great as 20 dB were observed at L-band.

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

    Science.gov (United States)

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

    2012-12-01

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

  4. Noise storm coordinated observations

    International Nuclear Information System (INIS)

    Elgaroey, Oe.; Tlamicha, A.

    1983-01-01

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

  5. High altitude flights in equatorial regions

    Science.gov (United States)

    Redkar, R. T.

    A thorough analysis of balloon flights made from Hyderabad, India (Latitude 17°28'N, Longitude 78°35'E), and other equatorial sites has been made. It has been shown that limited success is expected for flights made from equatorial latitudes with balloons made out of natural colour polyethylene film, since the best known balloon film in the world today viz. Winzen Stratofilm is tested for low temperature brittleness only at -80°C., whereas the tropopause temperatures over equatorial latitudes vary between -80°C and -90°C. The success becomes even more critical when flights are made with heavy payloads and larger balloons particularly at night when in the absence of solar radiation the balloon film becomes more susceptible to low temperature brittle failure. It is recommended that in case of capped balloons longer caps should be used to fully cover the inflated protion of the balloon at the higher level equatorial tropopause. It is also advised that the conditions such as wind shears in the tropopause should be critically studied before launching and a day with the tropopause temperature nearer to -80°C should be chosen. Special care also should be taken while handling the balloon on ground and during launching phase. Properties of Winzen Stratofilm have been critically studied and fresh mandates have been recommended on the basis of limiting values of film stresses which caused balloon failures in the equatorial tropopause. It is also emphasized that the data on such flights is still meagre especially for flights with heavy payloads and larger balloons. It has been also shown that it is safest to use balloons made out of grey coloured film which retains its flexibility with the absorption of solar radiation, the success obtained with such balloons so far being 100%. The drawback, however, is that these balloons cannot be used for night flights. Stratospheric wind regimes over Hyderabad are also discussed with a view to determine the period over which long

  6. Zonal wind observations during a geomagnetic storm

    Science.gov (United States)

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

    1986-01-01

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

  7. Observation of low energy particle precipitation at low altitude in the equatorial zone

    Science.gov (United States)

    Miah, M. A.

    1989-01-01

    Precipitation of protons in the equatorial zone was investigated by the Phoenix-1 experiment on the S81-1 mission from May to November, 1982. The protons show a precipitation peak along the line of minimum magnetic field strength with a FWHM of 13 deg. The index of equatorial pitch angle distribution is about 19. The peak proton flux shows a fifth-power altitude dependence, and the proton flux shows approximately a factor of 3 times increase in 1982 compared to that in 1969 due, possibly, to the stronger solar maximum conditions of 10.7-cm radiation in 1982.

  8. Concept development for the ITER equatorial port visible/infrared wide angle viewing system

    International Nuclear Information System (INIS)

    Reichle, R.; Beaumont, B.; Boilson, D.; Bouhamou, R.; Direz, M.-F.; Encheva, A.; Henderson, M.; Kazarian, F.; Lamalle, Ph.; Lisgo, S.; Mitteau, R.; Patel, K. M.; Pitcher, C. S.; Pitts, R. A.; Prakash, A.; Raffray, R.; Schunke, B.; Snipes, J.; Diaz, A. Suarez; Udintsev, V. S.

    2012-01-01

    The ITER equatorial port visible/infrared wide angle viewing system concept is developed from the measurement requirements. The proposed solution situates 4 viewing systems in the equatorial ports 3, 9, 12, and 17 with 4 views each (looking at the upper target, the inner divertor, and tangentially left and right). This gives sufficient coverage. The spatial resolution of the divertor system is 2 times higher than the other views. For compensation of vacuum-vessel movements, an optical hinge concept is proposed. Compactness and low neutron streaming is achieved by orienting port plug doglegs horizontally. Calibration methods, risks, and R and D topics are outlined.

  9. Equatorial noise emissions observed by the DEMETER spacecraft during geomagnetic storms

    Czech Academy of Sciences Publication Activity Database

    Němec, F.; Parrot, M.; Santolík, Ondřej

    121, 10 (2016), s. 9744-9757 ISSN 2169-9380 R&D Projects: GA MŠk(CZ) LH15304; GA ČR(CZ) GA14-31899S Institutional support: RVO:68378289 Keywords : altitude satellite Demeter * proton ring distributions * fast magnetosonic waves * Van Allen probes * cluster spacecraft * elf emissions * ULF waves * spatiotemporal variability * inner magnetosphere * magnetic equator Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.733, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/2016JA023145/full

  10. Fine structure in fast drift storm bursts

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  11. Spring Dust Storm Smothers Beijing

    Science.gov (United States)

    2002-01-01

    A few days earlier than usual, a large, dense plume of dust blew southward and eastward from the desert plains of Mongolia-quite smothering to the residents of Beijing. Citizens of northeastern China call this annual event the 'shachenbao,' or 'dust cloud tempest.' However, the tempest normally occurs during the spring time. The dust storm hit Beijing on Friday night, March 15, and began coating everything with a fine, pale brown layer of grit. The region is quite dry; a problem some believe has been exacerbated by decades of deforestation. According to Chinese government estimates, roughly 1 million tons of desert dust and sand blow into Beijing each year. This true-color image was made using two adjacent swaths (click to see the full image) of data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), flying aboard the OrbView-2 satellite, on March 17, 2002. The massive dust storm (brownish pixels) can easily be distinguished from clouds (bright white pixels) as it blows across northern Japan and eastward toward the open Pacific Ocean. The black regions are gaps between SeaWiFS' viewing swaths and represent areas where no data were collected. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  12. Spatial and temporal variability in nutrients and carbon uptake during 2004 and 2005 in the eastern equatorial Pacific Ocean

    DEFF Research Database (Denmark)

    Palacz, A. P.; Chai, F.

    2012-01-01

    The eastern equatorial Pacific plays a great role in the global carbon budget due to its enhanced biological productivity linked to the equatorial upwelling. However, as confirmed by the Equatorial Biocomplexity cruises in 2004 and 2005, nutrient upwelling supply varies strongly, partly due...... and intraseasonal time scales. Here, high resolution Pacific ROMS-CoSiNE (Regional Ocean Modeling System-Carbon, Silicon, Nitrogen Ecosystem) model results were evaluated with in situ and remote sensing data. The results of model-data comparison revealed a good agreement in domain-average hydrographic....... In order to fully resolve the complexity of biological and physical interactions in the eastern equatorial Pacific, we recommended improving CoSiNE and other models by introducing more phytoplankton groups, variable Redfield and carbon to chlorophyll ratios, as well as resolving the Fe-Si co...

  13. The Plasma Environment Associated With Equatorial Ionospheric Irregularities

    Science.gov (United States)

    Smith, Jonathon M.; Heelis, R. A.

    2018-02-01

    We examine the density structure of equatorial depletions referred to here as equatorial plasma bubbles (EPBs). Data recorded by the Ion Velocity Meter as part of the Coupled Ion Neutral Dynamics Investigation (CINDI) aboard the Communication/Navigation Outage Forecasting System (C/NOFS) satellite are used to study EPBs from 1600 to 0600 h local time at altitudes from 350 to 850 km. The data are taken during the 7 years from 2008 to 2014, more than one half of a magnetic solar cycle, that include solar minimum and a moderate solar maximum. Using a rolling ball algorithm, EPBs are identified by profiles in the plasma density, each having a depth measured as the percent change between the background and minimum density (ΔN/N). During solar moderate activity bubbles observed in the topside postsunset sector are more likely to have large depths compared to those observed in the topside postmidnight sector. Large bubble depths can be observed near 350 km in the bottomside F region in the postsunset period. Conversely at solar minimum the distribution of depths is similar in the postsunset and postmidnight sectors in all longitude sectors. Deep bubbles are rarely observed in the topside postsunset sector and never in the bottomside above 400 km in altitude. We suggest that these features result from the vertical drift of the plasma for these two solar activity levels. These drift conditions affect both the background density in which bubbles are embedded and the growth rate of perturbations in the bottomside where bubbles originate.

  14. Comprehensive Condition Survey and Storm Waves, Circulation, and Sediment Study, Dana Point Harbor, California

    Science.gov (United States)

    2014-12-01

    waters; 3) west to northwest local sea; 4) prefrontal local sea; 5) tropical storm swell; and 6) extratropical cyclone in the southern hemisphere...14-13 58 Prefrontal local sea The coastal zone within the south Orange County area is vulnerable under extratropical winter storm conditions (a...wave characteristics for severe extratropical storms during the 39 yr time period (1970–2008) are comparable to peak storm wave heights that were

  15. Monitoring Hurricane Rita Inland Storm Surge: Chapter 7J in Science and the storms-the USGS response to the hurricanes of 2005

    Science.gov (United States)

    McGee, Benton D.; Tollett, Roland W.; Goree, Burl B.

    2007-01-01

    Pressure transducers (sensors) are accurate, reliable, and cost-effective tools to measure and record the magnitude, extent, and timing of hurricane storm surge. Sensors record storm-surge peaks more accurately and reliably than do high-water marks. Data collected by sensors may be used in storm-surge models to estimate when, where, and to what degree stormsurge flooding will occur during future storm-surge events and to calibrate and verify stormsurge models, resulting in a better understanding of the dynamics of storm surge.

  16. Multi-Instrument Observations of a Geomagnetic Storm and its Effects on the Arctic Ionosphere: A Case Study of the 19 February 2014 Storm

    DEFF Research Database (Denmark)

    Durgonics, Tibor; Komjathy, Attila; Verkhoglyadova, Olga

    2017-01-01

    We present a multi-instrumented approach for the analysis of the Arctic ionosphere during the 19 February 2014 highly complex, multiphase geomagnetic storm, which had the largest impact on the disturbance storm-time (Dst) index that year. The geomagnetic storm was the result of two powerful Earth......-directed coronal mass ejections (CMEs). It produced a strong long lasting negative storm phase over Greenland with a dominant energy input in the polar-cap. We employed GNSS networks, geomagnetic observatories, and a specific ionosonde station in Greenland. We complemented the approach with spaceborne measurements...... specifically found that, (1) Thermospheric O/N2 measurements demonstrated significantly lower values over the Greenland sector than prior to the storm-time. (2) An increased ion flow in the topside ionosphere was observed during the negative storm phase. (3) Negative storm phase was a direct consequence...

  17. Surface temperature of the equatorial Pacific Ocean and the Indian rainfall

    Digital Repository Service at National Institute of Oceanography (India)

    Gopinathan, C.K.

    The time variation of the monthly mean surface temperature of the equatorial Pacific Ocean during 1982-1987 has been studied in relation to summer monsoon rainfall over India The ENSO events of 1982 and 1987 were related to a significant reduction...

  18. Latitudinal variation of the polar cusp during a geomagnetic storm

    International Nuclear Information System (INIS)

    Meng, C.

    1982-01-01

    Large amplitude latitudinal variation of the polar cusp position was observed during the intense geomagnetic storm of 15--16 February 1980. The observation of the polar cusp, identified as the region of intense but extremely soft electron precipitation, was made by two nearly noon-midnight orbit DMSP satellites over both northern and southern hemispheres. The latitudinal shift of the polar cusp is observed to be related to the intensity variation of the ring current indicated by the hourly Dst values. The polar cusp region moved from its normal location at approx.76 0 gm lat down to approx.62 0 gm lat at the peak of this storm. This movement took about 5 hours and was detected over both hemispheres. A drastic variation in the width of the cusp region was also observed; it is very narrow (approx.1 0 ) during the equatorial shift and expands to > or approx. =5 0 during the poleward recovery. Variation of the polar cusp latitude with that of the Dst index was also seen during the period before the intense storm

  19. MACSAT - A Near Equatorial Earth Observation Mission

    Science.gov (United States)

    Kim, B. J.; Park, S.; Kim, E.-E.; Park, W.; Chang, H.; Seon, J.

    MACSAT mission was initiated by Malaysia to launch a high-resolution remote sensing satellite into Near Equatorial Orbit (NEO). Due to its geographical location, Malaysia can have large benefits from NEO satellite operation. From the baseline circular orbit of 685 km altitude with 7 degrees of inclination, the neighboring regions around Malaysian territory can be frequently monitored. The equatorial environment around the globe can also be regularly observed with unique revisit characteristics. The primary mission objective of MACSAT program is to develop and validate technologies for a near equatorial orbit remote sensing satellite system. MACSAT is optimally designed to accommodate an electro-optic Earth observation payload, Medium-sized Aperture Camera (MAC). Malaysian and Korean joint engineering teams are formed for the effective implementation of the satellite system. An integrated team approach is adopted for the joint development for MACSAT. MAC is a pushbroom type camera with 2.5 m of Ground Sampling Distance (GSD) in panchromatic band and 5 m of GSD in four multi-spectral bands. The satellite platform is a mini-class satellite. Including MAC payload, the satellite weighs under 200 kg. Spacecraft bus is designed optimally to support payload operations during 3 years of mission life. The payload has 20 km of swath width with +/- 30 o of tilting capability. 32 Gbits of solid state recorder is implemented as the mass image storage. The ground element is an integrated ground station for mission control and payload operation. It is equipped with S- band up/down link for commanding and telemetry reception as well as 30 Mbps class X-band down link for image reception and processing. The MACSAT system is capable of generating 1:25,000-scale image maps. It is also anticipated to have capability for cross-track stereo imaging for Digital elevation Model (DEM) generation.

  20. The equatorial F-layer: progress and puzzles

    Directory of Open Access Journals (Sweden)

    H. Rishbeth

    Full Text Available This work reviews some aspects of the ionospheric F-layer in the vicinity of the geomagnetic equator. Starting with a historical introduction, brief summaries are given of the physics that makes the equatorial ionosphere so interesting, concentrating on the large-scale structure rather than the smaller-scale instability phenomena. Several individual topics are then discussed, including eclipse effects, the asymmetries of the `equatorial trough', variations with longitude, the semiannual variation, the effects of the global thermospheric circulation, and finally the equatorial neutral thermosphere, including `superrotation' and possible topographic influences.

    Keyword: Ionosphere (equatorial ionosphere

  1. Storm Warnings for Cuba

    Science.gov (United States)

    1994-01-01

    Services: Telephone: (310) 451-7002; Fax: (310) 451-6915; Internet : order@rand.org. al Accesion For "Ni %&’ Storm WarningsDTI’ TAB E03 --- - - -for...reaction leading to an uncontrol- lable burgeoning of private entrepreneurial activity. As one observer 14See Acuerdo del Buro Politico , "Para llevar a...34 10Comisi6n de Relaciones Internacionales, Asamblea Nacional del Poder Popular, Datos, Reflexiones y Argumentos Sobre la Actual Situaci6n de Cuba, n.p

  2. An equatorial coronal hole at solar minimum

    Science.gov (United States)

    Bromage, B. J. I.; DelZanna, G.; DeForest, C.; Thompson, B.; Clegg, J. R.

    1997-01-01

    The large transequatorial coronal hole that was observed in the solar corona at the end of August 1996 is presented. It consists of a north polar coronal hole called the 'elephant's trunk or tusk'. The observations of this coronal hole were carried out with the coronal diagnostic spectrometer onboard the Solar and Heliospheric Observatory (SOHO). The magnetic field associated with the equatorial coronal hole is strongly connected to that of the active region at its base, resulting in the two features rotating at almost the same rate.

  3. Is there a hole in the topside, equatorial ionosphere?

    Directory of Open Access Journals (Sweden)

    D. Gallagher

    Full Text Available A paper in 2000 (Huba, 2000 found a depression in electron density in the topside ionosphere near the magnetic equator, based on the SAMI-2 physical ionospheric model. The model showed, for the first time, the formation of a hole in electron density in the altitude range 1500–2500 km at geomagnetic equatorial latitudes. The model produced the hole because of transhemispheric O+ flows that collisionally couple to H+, transporting it to lower altitudes, and thereby reducing the electron density at high altitudes. At that time and until now, no published observations have been reported to confirm or refute this numerical result. Recent, new analysis of Dynamics Explorer 1 Retarding Ion Mass Spectrometer measurements provides the first tentative experimental support for this model result. Keywords: Ionosphere, Topside, Magnetic equator, Plasmasphere

  4. Copper disinfection ban causes storm.

    Science.gov (United States)

    Lester, Alan

    2013-05-01

    Since 1 February this year, under the EU's Biocidal Products Directive, it has been illegal to sell or use water treatment systems that use elemental copper, a practice employed historically by a significant number of UK healthcare facilities to combat Legionella. Alan Lester, managing director of specialist supplier of 'environmentally-friendly' water treatment systems, Advanced Hydro, says the ban has caused 'a storm of giant proportion,' with advocates of copper ion-based treatment systems arguing that this disinfection method dates back 3,000 years to Egyptian times, making it an 'undoubtedly proven' technology. Here he explains why the ban came into force, considers why the UK's Health and Safety Executive (HSE) is seeking a derogation, looks at the ban's likely impact, and gives a personal viewpoint on the 'pros and cons' of some of the alternative treatment technologies, including a titanium dioxide-based system marketed by Advanced Hydro itself in the UK.

  5. Influence of storm characteristics on soil erosion and storm runoff

    Science.gov (United States)

    Johnny M. III Grace

    2008-01-01

    Unpaved forest roads can be major sources of sediment from forested watersheds. Storm runoff from forest roads are a concern due to their potential delivery of sediments and nutrients to stream systems resulting in degraded water quality. The volume and sediment concentrations of stormwater runoff emanating from forest roads can be greatly influenced by storm...

  6. Shutdown dose rates at ITER equatorial ports considering radiation cross-talk from torus cryopump lower port

    Energy Technology Data Exchange (ETDEWEB)

    Juárez, Rafael, E-mail: rjuarez@ind.uned.es [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain); Pampin, Raul [F4E, Torres Diagonal Litoral B3, Josep Pla 2, Barcelona 08019 (Spain); Levesy, Bruno [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Moro, Fabio [ENEA, Via Enrico Fermi 45, Frascati, Rome (Italy); Suarez, Alejandro [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Sanz, Javier [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain)

    2015-11-15

    Shutdown dose rates for planned maintenance purposes is an active research field in ITER. In this work the radiation (neutron and gamma) cross-talk between ports in the most conservative case foreseen in ITER is investigated: the presence of a torus cryopump lower port, mostly empty for pumping efficiency reasons. There will be six of those ports: #4, #6, #10, #12, #16 and #18. The equatorial ports placed above them will receive a significant amount of additional radiation affecting the shutdown dose rates during in situ maintenance activities inside the cryostat, and particularly in the port interspace area. In this study a general situation to all the equatorial ports placed above torus cryopump lower ports is considered: a generic diagnostics equatorial port placed above the torus cryopump lower port (LP#4). In terms of shutdown dose rates at equatorial port interspace after 10{sup 6} s of cooling time, 405 μSv/h has been obtained, of which 160 μSv/h (40%) are exclusively due to radiation cross-talk from a torus cryopump lower port. Equatorial port activation due to only “local neutrons” contributes 166 μSv/h at port interspace, showing that radiation cross-talk from such a lower port is a phenomenon comparable in magnitude to the neutron leakage though the equatorial port plug.

  7. Signatures of moderate (M-class) and low (C and B class) intensity solar flares on the equatorial electrojet current: Case studies

    Science.gov (United States)

    Chakrabarty, D.; Bagiya, Mala S.; Thampi, Smitha V.; Pathan, B. M.; Sekar, R.

    2013-12-01

    The present investigation brings out, in contrast to the earlier works, the changes in the equatorial electrojet (EEJ) current in response to a few moderate (M-class) and low (C and B class) intensity solar flares during 2005-2010. Special care is taken to pick these flare events in the absence of prompt electric field perturbations associated with geomagnetic storms and substorms that also affect the electrojet current. Interestingly, only the normalized (with respect to the pre-flare level) deviations of daytime EEJ (and not the deviations alone) change linearly with the increases in the EUV and X-ray fluxes. These linear relationships break down during local morning hours when the E-region electric field approaches zero before reversal of polarity. This elicits that the response of EEJ strength corresponding to less-intense flares can be appropriately gauged only when the local time variation of the quiet time E-region zonal electric field is taken into account. The flare events enhanced the EEJ strength irrespective of normal or counter electrojet (CEJ) conditions that shows that solar flares change the E-region ionization density and not the electric field. In addition, the enhancements in the X-ray and EUV fluxes, for these flares occurring during this solar minimum period, are found to be significantly correlated as opposed to the solar maximum period, indicating the differences in the solar processes in different solar epochs.

  8. Preliminary report: STOIC CGCM intercomparison - equatorial sections

    International Nuclear Information System (INIS)

    Davey, M; Huddleston, M; Sperber, K R.

    1999-01-01

    An intercomparison and assessment of the tropical behaviour of coupled general circulation models (CGCMs) is being carried out, to identify common strengths and weaknesses and thus guide future CGCM development. The work is being carried out as part of the CLIVAR climate research programme, as a WG-SIP (Working Group on Seasonal to Interannual Prediction) project called STOIC (Study of Tropical Oceans In CGCMs), organised by Michael Davey. This project complements a companion sub-project called ENSIP (El Ni no Simulation Intercomparison Project) organised by Mojib Latif (Max- Planck-Institute for Meteorology) that focusses on equatorial Pacific CGCM behaviour (Latif et al. 1999). Previous coupled model assessments (Mechoso et al. 1995, Neelin et al. 1992, and ENSIP) have focussed on tropical Pacific behaviour. The aim of STOIC is to look at model performance in all tropical ocean regions. This status report contains a sample of the STOIC assessment work, highlighting mean and inter- annual equatorial sea surface temperatures and zonal windstresses. The intention is to submit STOIC and ENSIP papers in mid-1999 for publication together in a refereed journal

  9. Nighttime ionospheric D region: Equatorial and nonequatorial

    Science.gov (United States)

    Thomson, Neil R.; McRae, Wayne M.

    2009-08-01

    Nighttime ionospheric D region parameters are found to be generally well modeled by the traditional H‧ and β as used by Wait and by the U.S. Navy in their Earth-ionosphere VLF radio waveguide programs. New comparisons with nonequatorial, mainly all-sea VLF path observations reported over several decades are shown to be consistent with the previously determined height H‧ ˜ 85.0 km and sharpness β ˜ 0.63 km-1. These paths include NPM (Hawaii) to Washington, D. C., Omega Hawaii and NLK (Seattle) to Japan, NWC (N.W. Australia) to Madagascar, and NBA (Panama) to Colorado. In marked contrast, transequatorial path observations (even when nearly all-sea) are found to be often not well modeled: for example, for Omega Japan and JJI (Japan) to Dunedin, New Zealand, the observed amplitudes are markedly lower than those which would be expected from H‧ ˜ 85.0 km and β ˜ 0.63 km-1, or any other realistic values of H‧ and β. Other transequatorial observations compared with modeling include NWC to Japan, Omega Hawaii to Dunedin, and NPM (Hawaii) to Dunedin. It is suggested that the effects of irregularities in the equatorial electrojet may extend down into the nighttime D region and so account for the observed equatorial VLF perturbations through scattering or mode conversion.

  10. Post sunset equatorial spread-F at Kwajalein and interplanetary magnetic field

    Science.gov (United States)

    Rastogi, R. G.; Chandra, H.; Janardhan, P.; Reinisch, B. W.; Bisoi, Susanta Kumar

    2017-10-01

    We connect the time sequence of changes in the IMF-Bz to the development of spread-F at an equatorial station Kwajalein on three different nights in November 2004, one during a geomagnetic quiet period and other two during geomagnetic disturbed periods. The chosen days show clear and smooth variations of IMF-Bz without any large fluctuations thereby enabling one to correlate changes in equatorial spread-F with corresponding changes in IMF-Bz. It is shown that a slow and continuous increase in the IMF-Bz over a duration of few hours has a similar effect on the equatorial ionosphere as of a sudden northward turning of the IMF-Bz in causing an electric field through the polar region and then to the equator. We conclude that the Spread-F at equatorial and low latitudes are due to echoes from ionization irregularities that arise due to the plasma instabilities generated by an eastward electric field on the large plasma density gradient in or below the base of the F-layer during any period of the night time along with the gravity driven Rayleigh-Taylor instability.

  11. Spread F – an old equatorial aeronomy problem finally resolved?

    Directory of Open Access Journals (Sweden)

    R. F. Woodman

    2009-05-01

    Full Text Available One of the oldest scientific topics in Equatorial Aeronomy is related to Spread-F. It includes all our efforts to understand the physical mechanisms responsible for the existence of ionospheric F-region irregularities, the spread of the traces in a night-time equatorial ionogram – hence its name – and all other manifestations of the same. It was observed for the first time as an abnormal ionogram in Huancayo, about 70 years ago. But only recently are we coming to understand the physical mechanisms responsible for its occurrence and its capricious day to day variability. Several additional techniques have been used to reveal the spatial and temporal characteristics of the F-region irregularities responsible for the phenomenon. Among them we have, in chronological order, radio star scintillations, trans-equatorial radio propagation, satellite scintillations, radar backscatter, satellite and rocket in situ measurements, airglow, total electron content techniques using the propagation of satellite radio signals and, recently, radar imaging techniques. Theoretical efforts are as old as the observations. Nevertheless, 32 years after their discovery, Jicamarca radar observations showed that none of the theories that had been put forward could explain them completely. The observations showed that irregularities were detected at altitudes that were stable according to the mechanisms proposed. A breakthrough came a few years later, again from Jicamarca, by showing that some of the "stable" regions had become unstable by the non-linear propagation of the irregularities from the unstable to the stable region of the ionosphere in the form of bubbles of low density plasma. A problem remained, however; the primary instability mechanism proposed, an extended (generalized Rayleigh-Taylor instability, was too slow to explain the rapid development seen by the observations. Gravity waves in the neutral background have been proposed as a seeding mechanism to

  12. Response of the Ionospheric F-region in the Latin American Sector During the Intense Geomagnetic Storm of 21-22 January 2005

    Science.gov (United States)

    Sahai, Y.; Fagundes, P. R.; de Jesus, R.; de Abreu, A. J.; Crowley, G.; Pillat, V. G.; Guarnieri, F. L.; Abalde, J. R.; Bittencourt, J. A.

    2009-12-01

    Ionospheric storms are closely associated with geomagnetic storms and are an extreme example of space weather events. The response of the ionosphere to storms is rather complicated. In the present investigation, we have studied the response of the ionospheric F-region in the Latin American sector during the intense geomagnetic storm of 21-22 January 2005 (with storm sudden commencement (SSC) at 1712 UT on 21 January). This geomagnetic storm is anomalous (minimum Dst reached -105 nT at 0700 UT on 22 January) because the main phase occurred during the northward excursion of the Bz component of interplanetary magnetic fields (IMFs). The monthly mean F10.7 solar flux for the month of January 2005 was 99.0 sfu. The ionospheric F-region parameters observed at Ramey (18.5 N, 67.1 W; RAM), Puerto Rico, Jicamarca (12.0 S, 76.8 W; JIC), Peru, Manaus (2.9 S, 60.0 W; MAN), and São José dos Campos (23.2 S, 45.9 W; SJC), Brazil, during 21-22 January (geomagnetically disturbed) and 25 January (geomagnetically quiet) have been analyzed. Both JIC and MAN, the equatorial stations, show unusually rapid uplifting of the F-region peak heights(hpF2/hmF2) and a decrease in the NmF2 coincident with the time of SSC. At both RAM and SJC an uplifting of the F-region peak height is observed at about 2000 UT. The low-latitude station SJC shows a coincident decrease in NmF2 with the uplifting, whereas the mid-latitude station RAM shows a decrease in NmF2 earlier than the uplifting. Also, the observed variations in the F-region ionospheric parameters are compared with the TIMEGCM model run for 21-22 January and the model results show both similarities and differences from the observed results. Average GPS-TEC (21-22 and 25 January) and phase fluctuations (21, 22, 25, 26 January) observed at Belem (1.5 S, 48.5 W; BELE), Brasilia (15.9 S, 47.9 W; BRAZ), Presidente Prudente (22.3o S, 51.4 W; UEPP), and Porto Alegre (30.1 S, 51.1 W; POAL), Brazil, are also presented. These GPS stations belong to

  13. Geomagnetic storm under laboratory conditions: randomized experiment

    Science.gov (United States)

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

    2017-10-01

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

  14. Geomagnetic storm under laboratory conditions: randomized experiment.

    Science.gov (United States)

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

    2018-04-01

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

  15. Electrical Storm: Incidence, Prognosis and Therapy.

    Science.gov (United States)

    Sagone, Antonio

    2015-12-01

    The term "electrical storm" indicates a life-threatening clinical condition characterized by the recurrence of hemodynamically unstable ventricular tachycardia and/or ventricular fibrillation, in particular in patients with ICD implanted for primary or secondary prevention. Although there isn't a shared definition of electrical storm, nowadays the most accepted definition refers to three or more separate arrhythmia episodes leading to ICD therapies including antitachycardia pacing or shock occurring over a single 24 hours' time period. Clinical presentation can be dramatic and triggering mechanism are not clear at all yet, but electrical storm is associated with high mortality rates and low patients quality of life, both in the acute phase and in the long term. The first line therapy is based on antiarrhythmic drugs to suppress electrical storm, but in refractory patients, interventions such as catheter ablation or in some cases surgical cardiac sympathetic denervation might be helpful. Anyhow, earlier interventional management can lead to better outcomes than persisting with antiarrhythmic pharmacologic therapy and, when available, an early interventional approach should be preferred.

  16. The Effect of Storm Driver and Intensity on Magnetospheric Ion Temperatures

    Science.gov (United States)

    Keesee, Amy M.; Katus, Roxanne M.; Scime, Earl E.

    2017-09-01

    Energy deposited in the magnetosphere during geomagnetic storms drives ion heating and convection. Ions are also heated and transported via internal processes throughout the magnetosphere. Injection of the plasma sheet ions to the inner magnetosphere drives the ring current and, thus, the storm intensity. Understanding the ion dynamics is important to improving our ability to predict storm evolution. In this study, we perform superposed epoch analyses of ion temperatures during storms, comparing ion temperature evolution by storm driver and storm intensity. The ion temperatures are calculated using energetic neutral atom measurements from the Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS) mission. The global view of these measurements provide both spatial and temporal information. We find that storms driven by coronal mass ejections (CMEs) tend to have higher ion temperatures throughout the main phase than storms driven by corotating interaction regions (CIRs) but that the temperatures increase during the recovery phase of CIR-driven storms. Ion temperatures during intense CME-driven storms have brief intervals of higher ion temperatures than those during moderate CME-driven storms but have otherwise comparable ion temperatures. The highest temperatures during CIR-driven storms are centered at 18 magnetic local time and occur on the dayside for moderate CME-driven storms. During the second half of the main phase, ion temperatures tend to decrease in the postmidnight to dawn sector for CIR storms, but an increase is observed for CME storms. This increase begins with a sharp peak in ion temperatures for intense CME storms, likely a signature of substorm activity that drives the increased ring current.

  17. Understanding the Unique Equatorial Density Irregularities

    Science.gov (United States)

    2015-04-01

    research, 55, 184-198, 2015. • Tesema, F., B. Damtie, M. Nigussie, The response of the ionosphere to intense geomagnetic storms in 2012 using GPS-TEC...Approved for public release; distribution is unlimited. fountain effect between 1000 to 1500 UT, which could be due to strong pre- reversal enhancement of...investigate different ionospheric phenomena such as the effect of the geomagnetic disturbance on the distribution of the low latitude ionospheric electron

  18. Structure of the subauroral ionosphere during the magnetospheric storm according to the data of the ''Interkosmos-19'' satellite

    International Nuclear Information System (INIS)

    Deminov, M.G.; Karpachev, A.T.; Kushnerevskij, Yu.V.; Shmilauehr, Ya.

    1985-01-01

    Variations of electron density and electron temperature in the subauroral ionosphere during the magnetospheric storm on April 3-4, 1979 are analyzed according to the data of the ''Interkosmos-19'' satellite. The sharpest displacement of a middle latitude fall-through to the equator is primarily caused by the turn-over of Bsub(z)-component of the interplanetary magnetic field (IMF) to the South. This displacement has taken place immediately after the turn-over of IMF Bsub(z)-component to the South in the day-time with a approximately 2 h delay in the night-time. and a approximately 40 min delay in around midnight. The general amplitude of fall-trhrough displacement is approximately 18. 20 and 17 deg for the day- and night-time and around midnight. The minimum latitude of the fall-through equals 56, 48 and 43 deg in the day- and night-time and midnight respectively. The saturation in IMF equatorial displacement is observed in the dark time of the day near the maximum of IMF Bsub(z)-component and Ksub(p) index

  19. Seeding and layering of equatorial spread F by gravity waves

    International Nuclear Information System (INIS)

    Hysell, D.L.; Kelley, M.C.; Swartz, W.E.; Woodman, R.F.

    1990-01-01

    Studies dating back more than 15 years have presented evidence that atmospheric gravity waves play a role in initiating nighttime equatorial F region instabilities. This paper analyzes a spectabular spread F event that for the first time demonstrates a layering which, the authors argue, is controlled by a gravity wave effect. The 50-km vertical wavelength of a gravity wave which they have found is related theoretically to a plasma layering irregularity that originated at low altitudes and then was convected, intact, to higher altitudes. Gravity waves also seem to have determined bottomside intermediate scale undulations, although this fact is not as clear in the data. The neutral wind dynamo effect yields wave number conditions on the gravity wave's ability to modulate the Rayleigh-Taylor instaiblity process. Finally, after evaluating the gravity wave dispersion relation and spatial resonance conditions, we estimate the properties of the seeding wave

  20. Combined radar observations of equatorial electrojet irregularities at Jicamarca

    Directory of Open Access Journals (Sweden)

    D. L. Hysell

    2007-03-01

    Full Text Available Daytime equatorial electrojet plasma irregularities were investigated using five distinct radar diagnostics at Jicamarca including range-time-intensity (RTI mapping, Faraday rotation, radar imaging, oblique scattering, and multiple-frequency scattering using the new AMISR prototype UHF radar. Data suggest the existence of plasma density striations separated by 3–5 km and propagating slowly downward. The striations may be caused by neutral atmospheric turbulence, and a possible scenario for their formation is discussed. The Doppler shifts of type 1 echoes observed at VHF and UHF frequencies are compared and interpreted in light of a model of Farley Buneman waves based on kinetic ions and fluid electrons with thermal effects included. Finally, the up-down and east-west asymmetries evident in the radar observations are described and quantified.

  1. Relationship between substorms and storms

    International Nuclear Information System (INIS)

    Kamide, Y.

    1980-01-01

    In an attempt to deduce a plausible working model of the relationship between magnetospheric substorms and storms, recent relevant studies of various processes occurring during disturbed periods are integrated along with some theoretical suggestions. It has been shown that the main phase of geomagnetic storms is associated with the successive occurrence of intense substorms and with the sustained southward component of the interplanetary magnetic field (IMF). However, these relations are only qualitatively understood, and thus basic questions remain unanswered involving the hypothesis whether a magnetic storm is a non-linear (or linear) superposition of intense substorms, each of which constitutes an elementary storm, or the main phase of magnetic storms occurs as a result of the intense southward IMF which enhances magnetospheric convection and increases occurrence probability of substorms. (Auth.)

  2. Thyroid storm: an updated review.

    Science.gov (United States)

    Chiha, Maguy; Samarasinghe, Shanika; Kabaker, Adam S

    2015-03-01

    Thyroid storm, an endocrine emergency first described in 1926, remains a diagnostic and therapeutic challenge. No laboratory abnormalities are specific to thyroid storm, and the available scoring system is based on the clinical criteria. The exact mechanisms underlying the development of thyroid storm from uncomplicated hyperthyroidism are not well understood. A heightened response to thyroid hormone is often incriminated along with increased or abrupt availability of free hormones. Patients exhibit exaggerated signs and symptoms of hyperthyroidism and varying degrees of organ decompensation. Treatment should be initiated promptly targeting all steps of thyroid hormone formation, release, and action. Patients who fail medical therapy should be treated with therapeutic plasma exchange or thyroidectomy. The mortality of thyroid storm is currently reported at 10%. Patients who have survived thyroid storm should receive definite therapy for their underlying hyperthyroidism to avoid any recurrence of this potentially fatal condition. © The Author(s) 2013.

  3. The D1 parameter for the equatorial F1 region

    International Nuclear Information System (INIS)

    Adeniyi, J.O.; Radicella, S.M.

    2002-01-01

    This work is a contribution to the effort at improving the representation of the F1 equatorial ionospheric region in the International Reference Ionosphere (IRI) model. The D1 parameter has been proposed for describing the F1 layer. We have therefore produced a maiden table of D1 parameter for an equatorial station. Diurnal and seasonal effects were considered. (author)

  4. A Generalized Equatorial Model for the Accelerating Solar Wind

    Science.gov (United States)

    Tasnim, S.; Cairns, Iver H.; Wheatland, M. S.

    2018-02-01

    A new theoretical model for the solar wind is developed that includes the wind's acceleration, conservation of angular momentum, deviations from corotation, and nonradial velocity and magnetic field components from an inner boundary (corresponding to the onset of the solar wind) to beyond 1 AU. The model uses a solution of the time-steady isothermal equation of motion to describe the acceleration and analytically predicts the Alfvénic critical radius. We fit the model to near-Earth observations of the Wind spacecraft during the solar rotation period of 1-27 August 2010. The resulting data-driven model demonstrates the existence of noncorotating, nonradial flows and fields from the inner boundary (r = rs) outward and predicts the magnetic field B = (Br,Bϕ), velocity v = (vr,vϕ), and density n(r,ϕ,t), which vary with heliocentric distance r, heliolatitude ϕ, and time t in a Sun-centered standard inertial plane. The description applies formally only in the equatorial plane. In a frame corotating with the Sun, the transformed velocity v' and a field B' are not parallel, resulting in an electric field with a component Ez' along the z axis. The resulting E'×B'=E'×B drift lies in the equatorial plane, while the ∇B and curvature drifts are out of the plane. Together these may lead to enhanced scattering/heating of sufficiently energetic particles. The model predicts that deviations δvϕ from corotation at the inner boundary are common, with δvϕ(rs,ϕs,ts) comparable to the transverse velocities due to granulation and supergranulation motions. Abrupt changes in δvϕ(rs,ϕs,ts) are interpreted in terms of converging and diverging flows at the cell boundaries and centers, respectively. Large-scale variations in the predicted angular momentum demonstrate that the solar wind can drive vorticity and turbulence from near the Sun to 1 AU and beyond.

  5. Observations of EMIC Triggered Emissions off the Magnetic Equatorial Plane

    Science.gov (United States)

    Grison, B.; Breuillard, H.; Santolik, O.; Cornilleau-Wehrlin, N.

    2016-12-01

    On 19/08/2005 Cluster spacecraft had their perigee close to the dayside of the Earth magnetic equatorial plane, at about 14 hours Magnetic Local Time. The spacecraft crossed the equator from the southern hemisphere toward the northern hemisphere. In the Southern hemisphere, at about -23° magnetic latitude (MLAT) and at distance of 5.25 Earth Radii from Earth, Cluster 3 observes an EMIC triggered emission between the He+ and the proton local gyrofrequencies. The magnetic waveform (STAFF instrument data) is transformed into the Fourier space for a study based on single value decomposition (SVD) analysis. The emission lasts about 30s. The emission frequency rises from 1Hz up to 1.9Hz. The emission polarization is left-hand, its coherence value is high and the propagation angle is field aligned (lower than 30º). The Poynting flux orientation could not be established. Based on previous study results, these properties are indicative of an observation in vicinity of the source region of the triggered emission. From our knowledge this is the first time that EMIC triggered emission are observed off the magnetic equator. In order to identify the source region we study two possibilities: a source region at higher latitudes than the observations (and particles orbiting in "Shabansky" orbits) and a source region close to the magnetic equatorial plane, as reported in previous studies. We propose to identify the source region from ray tracing analysis and to compare the observed propagation angle in several frequency ranges to the ray tracing results.

  6. F-region ionospheric perturbations in the low-latitude ionosphere during the geomagnetic storm of 25-27 August 1987

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    2004-11-01

    Full Text Available We have presented a comparison between the modeled NmF2 and hmF2, and NmF2 and hmF2 which were observed at the equatorial anomaly crest and close to the geomagnetic equator simultaneously by the Akita, Kokubunji, Yamagawa, Okinawa, Manila, Vanimo, and Darwin ionospheric sounders and by the middle and upper atmosphere (MU radar (34.85° N, 136.10° E during the 25-27 August 1987 geomagnetically storm-time period at low solar activity near 201°, geomagnetic longitude. A comparison between the electron and ion temperatures measured by the MU radar and those produced by the model of the ionosphere and plasmasphere is presented. The corrections of the storm-time zonal electric field, EΛ, from 16:30 UT to 21:00 UT on 25 August bring the modeled and measured hmF2 into reasonable agreement. In both hemispheres, the meridional neutral wind, W, taken from the HWW90 wind model and the NRLMSISE-00 neutral temperature, Tn, and densities are corrected so that the model results agree with the ionospheric sounders and MU radar observations. The geomagnetic latitude variations in NmF2 on 26 August differ significantly from those on 25 and 27 August. The equatorial plasma fountain undergoes significant inhibition on 26 August. This suppression of the equatorial anomaly on 26 August is not due to a reduction in the meridional component of the plasma drift perpendicular to the geomagnetic field direction, but is due to the action of storm-time changes in neutral winds and densities on the plasma fountain process. The asymmetry in W determines most of the north-south asymmetry in hmF2 and NmF2 on 25 and 27 August between about 01:00-01:30 UT and about 14:00 UT when the equatorial anomaly exists in the ionosphere, while asymmetries in W, Tn, and neutral densities relative to the geomagnetic equator are responsible for the north-south asymmetry in NmF2 and hmF2 on 26 August. A theory of the primary mechanisms causing the morning and evening peaks in the electron

  7. Equatorial electrojet and its response to external electromagnetic effects

    Science.gov (United States)

    Bespalov, P. A.; Savina, O. N.

    2012-09-01

    In the quiet low-latitude Earth's ionosphere, a sufficiently developed current system that is responsible for the Sq magnetic-field variations is formed in quiet Sun days under the action of tidal streams. The density of the corresponding currents is maximum in the midday hours at the equatorial latitudes, where the so-called equatorial electrojet is formed. In this work, we discuss the nature of the equatorial electrojet. This paper studies the value of its response to external effects. First of all, it is concerned with estimating the possibility of using the equatorial electrojet for generating low-frequency electromagnetic signals during periodic heating of the ionosphere by the heating-facility radiation. The equatorial electrojet can also produce electrodynamic response to the natural atmospheric processes, e.g., an acoustic-gravity wave.

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

    International Nuclear Information System (INIS)

    Kurihara, Masahiro

    1975-01-01

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

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

    Directory of Open Access Journals (Sweden)

    H. Lundstedt

    2015-01-01

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

  10. Horizontal and vertical winds and temperatures in the equatorial thermosphere: measurements from Natal, Brazil during August-September 1982

    International Nuclear Information System (INIS)

    Biondi, M.A.

    1985-01-01

    Fabry-Perot interferometer measurements of Doppler shifts and widths of the 630.0 nm nightglow line have been used to determine the neutral winds and temperatures in the equatorial thermosphere over Natal, Brazil during August-September 1982. During this period, in the early night (2130 U.T.) the average value of the horizontal wind vector was 95 m s -1 at 100 0 azimuth, and the temperature varied from a low of 950 K during geomagnetically quiet conditions to a high of approx. 1400 K during a storm (6 September). The meridional winds were small, -1 , and the eastward zonal winds reached a maximum value 1-3 h after sunset, in qualitative agreement with TGCM predictions. On 26 August, an observed persistent convergence in the horizontal meridional flow was accompanied by a downward vertical velocity and an increase in the thermospheric temperature measured overhead. Oscillations with periods of 40-45 min in both the zonal and vertical wind velocities were observed during the geomagnetic storm of 6 September, suggesting gravity wave modulation of the equatorial thermospheric flow. (author)

  11. West African equatorial ionospheric parameters climatology based on Ouagadougou ionosonde station data from June 1966 to February 1998

    Directory of Open Access Journals (Sweden)

    F. Ouattara

    2009-06-01

    Full Text Available This study is the first which gives the climatology of West African equatorial ionosphere by using Ouagadougou station through three solar cycles. It has permitted to show the complete morphology of ionosphere parameters by analyzing yearly variation, solar cycle and geomagnetic activity, seasonal evolution and diurnal development. This work shows that almost all ionospheric parameters have 11-year solar cycle evolution. Seasonal variation shows that only foF2 exhibits annual, winter and semiannual anomaly. foF2 seasonal variation has permitted us to identify and characterize solar events effects on F2 layer in this area. In fact (1 during quiet geomagnetic condition foF2 presents winter and semiannual anomalies asymmetric peaks in March/April and October. (2 The absence of winter anomaly and the presence of equinoctial peaks are the most visible effects of fluctuating activity in foF2 seasonal time profiles. (3 Solar wind shock activity does not modify the profile of foF2 but increases ionization. (4 The absence of asymmetry peaks, the location of the peaks in March and October and the increase of ionization characterize recurrent storm activity. F1 layers shows increasing trend from cycle 20 to cycle 21. Moreover, E layer parameters seasonal variations exhibit complex structure. It seems impossible to detect fluctuating activity effect in E layer parameters seasonal variations but shock activity and wind stream activity act to decrease E layer ionization. It can be seen from Es layer parameters seasonal variations that wind stream activity effect is fairly independent of solar cycle. E and Es layers critical frequencies and virtual heights diurnal variations let us see the effects of the greenhouse gases in these layers.

  12. Observations of energetic helium ions in the Earth's radiation belts during a sequence of geomagnetic storms

    International Nuclear Information System (INIS)

    Spjeldvik, W.N.; Fritz, T.A.

    1981-01-01

    Every year a significant number of magnetic storms disturb the earth's magnetosphere and the trapped particle populations. In this paper, we present observations of energetic (MeV) helium ions made with Explorer 45 during a sequence of magnetic storms during June through December of 1972. The first of these storms started on June 17 and had a Dst index excursion to approx.190 gamma, and the MeV helium ions were perturbed primarily beyond 3 earth radii in the equatorial radiation belts with a typical flux increase of an order of magnitude at L = 4. The second storm period took place during August and was associated with very major solar flare activity. Although the Dst extremum was at best 35 gamma less than the June storm, this period can be characterized as irregular (or multi-storm) with strong compression of the magnetosphere and very large (order of magnitude) MeV helium ion flux enhancements down to Lapprox.2. Following this injection the trapped helium ion fluxes showed positive spectral slope with the peak beyond 3.15 MeV at L = 2.5; and at the lowest observable L shells (Lapprox.2--3) little flux decay (tau>100 days) was seen during the rest of the year. Any effects of two subsequent major magnetic storms in September and November were essentially undetectable in the prolonged after-effect of the August solar flare associated MeV helium ion injection. The helium ion radial profile of the phase space density showed a significant negative slope during this period, and we infer that radial diffusion constitutes a significant loss of helium ions on L shells above Lapprox. =4 during the aftermath of the August 1972 magnetic storm

  13. Long wavelength irregularities in the equatorial electrojet

    International Nuclear Information System (INIS)

    Kudeki, E.; Farley, D.T.; Fejer, B.G.

    1982-01-01

    We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach or exceed the ion-acoustic velocity even though the horizontal phase velocity of the wave is considerably smaller. A straightforward extension to the long wavelength regime of the usual linear theory of the electrojet instability explains this and several other observed features of these dominant primary waves

  14. Linear theory of equatorial spread F

    International Nuclear Information System (INIS)

    Hudson, M.K.; Kennel, C.F.

    1975-01-01

    A fluid dispersion relation for the drift and interchange (Rayleigh-Taylor) modes in a collisional plasma forms the basis for a linear theory of equatorial spread F. The collisional drift mode growth rate will exceed the growth rate of the Rayleigh-Taylor mode at short perpendicular wavelengths and density gradient scale lengths, and the drift mode can grow on top side as well as on bottom side density gradients. However, below the F peak, where spread F predominates, it is concluded that both the drift and the Rayleigh-Taylor modes contribute to the total spread F spectrum, the Rayleigh-Taylor mode dominating at long and the drift mode at short perpendicular wavelengths above the ion Larmor radius

  15. Equatorial circular motion in Kerr spacetime

    International Nuclear Information System (INIS)

    Pugliese, Daniela; Quevedo, Hernando; Ruffini, Remo

    2011-01-01

    We analyze the properties of circular orbits of test particles on the equatorial plane of a rotating central mass whose gravitational field is described by the Kerr spacetime. For rotating black holes and naked singularities we explore all the spatial regions where circular orbits can exist and analyze the behavior of the energy and the angular momentum of the corresponding test particles. In particular, we find all the radii at which a test particle can have zero angular momentum due to the repulsive gravity effects generated by naked singularities. We classify all the stability zones of circular orbits. It is shown that the geometric structure of the stability zones of black holes is completely different from that of naked singularities.

  16. Storm Prediction Center Today's Storm Reports

    Science.gov (United States)

    . (GRR) 2012 100 2 SSW BENNETT CEDAR IA 4171 9099 (DVN) 2014 100 FERRIS HANCOCK IL 4047 9117 (DVN) 2017 . TIME IS APPROXIMATE. (GRR) 2014 100 FERRIS HANCOCK IL 4047 9117 (DVN) 2017 175 5 WNW BUFORD ALBANY WY

  17. Thromboembolic complications of thyroid storm.

    Science.gov (United States)

    Min, T; Benjamin, S; Cozma, L

    2014-01-01

    Thyroid storm is a rare but potentially life-threatening complication of hyperthyroidism. Early recognition and prompt treatment are essential. Atrial fibrillation can occur in up to 40% of patients with thyroid storm. Studies have shown that hyperthyroidism increases the risk of thromboembolic events. There is no consensus with regard to the initiation of anticoagulation for atrial fibrillation in severe thyrotoxicosis. Anticoagulation is not routinely initiated if the risk is low on a CHADS2 score; however, this should be considered in patients with thyroid storm or severe thyrotoxicosis with impending storm irrespective of the CHADS2 risk, as it appears to increase the risk of thromboembolic episodes. Herein, we describe a case of thyroid storm complicated by massive pulmonary embolism. Diagnosis of thyroid storm is based on clinical findings. Early recognition and prompt treatment could lead to a favourable outcome.Hypercoagulable state is a recognised complication of thyrotoxicosis.Atrial fibrillation is strongly associated with hyperthyroidism and thyroid storm.Anticoagulation should be considered for patients with severe thyrotoxicosis and atrial fibrillation irrespective of the CHADS2 score.Patients with severe thyrotoxicosis and clinical evidence of thrombosis should be immediately anticoagulated until hyperthyroidism is under control.

  18. Modeling the ocean effect of geomagnetic storms

    DEFF Research Database (Denmark)

    Olsen, Nils; Kuvshinov, A.

    2004-01-01

    At coastal sites, geomagnetic variations for periods shorter than a few days are strongly distorted by the conductivity of the nearby sea-water. This phenomena, known as the ocean (or coast) effect, is strongest in the magnetic vertical component. We demonstrate the ability to predict the ocean...... if the oceans are considered. Our analysis also indicates a significant local time asymmetry (i.e., contributions from spherical harmonics other than P-I(0)), especially during the main phase of the storm....

  19. AI techniques in geomagnetic storm forecasting

    Science.gov (United States)

    Lundstedt, Henrik

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

  20. Observing Storm Surges from Space: A New Opportunity

    Science.gov (United States)

    Han, Guoqi; Ma, Zhimin; Chen, Dake; de Young, Brad; Chen, Nancy

    2013-04-01

    Coastal tide gauges can be used to monitor variations of a storm surge along the coast, but not in the cross-shelf direction. As a result, the cross-shelf structure of a storm surge has rarely been observed. In this study we focus on Hurricane Igor-induced storm surge off Newfoundland, Canada. Altimetric observations at about 2:30, September 22, 2010 UTC (hours after the passage of Hurricane Igor) reveal prominent cross-shelf variation of sea surface height during the storm passage, including a large nearshore slope and a mid-shelf depression. A significant coastal surge of 1 m derived from satellite altimetry is found to be consistent with tide-gauge measurements at nearby St. John's station. The post-storm sea level variations at St. John's and Argentia are argued to be associated with free equatorward-propagating continental shelf waves (with phase speeds of 11-13 m/s), generated along the northeast Newfoundland coast hours after the storm moved away from St. John's. The cross-shelf e-folding scale of the shelf wave was estimated to be ~100 km. We further show approximate agreement of altimetric and tide-gauge observations in the Gulf of Mexico during Hurricane Katrina (2005) and Isaac (2012). The study for the first time in the literature shows the robustness of satellite altimetry to observe storm surges, complementing tide-gauge observations for the analysis of storm surge characteristics and for the validation and improvement of storm surge models.

  1. Properties and origin of energetic particles at the duskside of the Earth's magnetosheath throughout a great storm

    Directory of Open Access Journals (Sweden)

    D. V. Sarafopoulos

    1999-09-01

    Full Text Available We study an interval of 56 h on January 16 to 18, 1995, during which the GEOTAIL spacecraft traversed the duskside magnetosheath from  X @ -15 to -40 RE and the EPIC/ICS and EPIC/STICS sensors sporadically detected tens of energetic particle bursts. This interval coincides with the expansion and growth of a great geomagnetic storm. The flux bursts are strongly dependent on the magnetic field orientation. They switch on whenever the Bz component approaches zero (Bz @ 0 nT. We strongly suggest a magnetospheric origin for the energetic ions and electrons streaming along these "exodus channels". The time profiles for energetic protons and "tracer" O+ ions are nearly identical, which suggests a common source. We suggest that the particles leak out of the magnetosphere all the time and that when the magnetosheath magnetic field connects the spacecraft to the magnetotail, they stream away to be observed by the GEOTAIL sensors. The energetic electron fluxes are not observed as commonly as the ions, indicating that their source is more limited in extent. In one case study the magnetosheath magnetic field lines are draped around the magnetopause within the YZ plane and a dispersed structure for peak fluxes of different species is detected and interpreted as evidence for energetic electrons leaking out from the dawn LLBL and then being channelled along the draped magnetic field lines over the magnetopause. Protons leak from the equatorial dusk LLBL and this spatial differentiation between electron and proton sources results in the observed dispersion. A gradient of energetic proton intensities toward the ZGSM = 0 plane is inferred. There is a permanent layer of energetic particles adjacent to the magnetosheath during this interval in which the dominant component of the magnetic field was Bz.Key words. Magnetospheric physics (magnetosheath; magnetotail boundary layers; storms and substorms

  2. US Weather Bureau Storm Reports

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weather Bureau and US Army Corps and other reports of storms from 1886-1955. Hourly precipitation from recording rain gauges captured during heavy rain, snow,...

  3. Relative outflow enhancements during major geomagnetic storms – Cluster observations

    Directory of Open Access Journals (Sweden)

    A. Schillings

    2017-12-01

    Full Text Available The rate of ion outflow from the polar ionosphere is known to vary by orders of magnitude, depending on the geomagnetic activity. However, the upper limit of the outflow rate during the largest geomagnetic storms is not well constrained due to poor spatial coverage during storm events. In this paper, we analyse six major geomagnetic storms between 2001 and 2004 using Cluster data. The six major storms fulfil the criteria of Dst  < −100 nT or Kp  > 7+. Since the shape of the magnetospheric regions (plasma mantle, lobe and inner magnetosphere are distorted during large magnetic storms, we use both plasma beta (β and ion characteristics to define a spatial box where the upward O+ flux scaled to an ionospheric reference altitude for the extreme event is observed. The relative enhancement of the scaled outflow in the spatial boxes as compared to the data from the full year when the storm occurred is estimated. Only O+ data were used because H+ may have a solar wind origin. The storm time data for most cases showed up as a clearly distinguishable separate peak in the distribution toward the largest fluxes observed. The relative enhancement in the outflow region during storm time is 1 to 2 orders of magnitude higher compared to less disturbed time. The largest relative scaled outflow enhancement is 83 (7 November 2004 and the highest scaled O+ outflow observed is 2  ×  1014 m−2 s−1 (29 October 2003.

  4. [Thyroid Storm and Myxedema Coma].

    Science.gov (United States)

    Milkau, Malte; Sayk, Friedhelm

    2018-03-01

    Thyroid storm and myxedema coma are the most severe clinical forms of thyroid dysfunction. While both hyper- and hypothyroidsm are common diseases, thyroid storm and myxedema coma are rare. Due to their unspecific signs and symptoms they are often difficult to diagnose. Both disorders are medical emergencies, which still show a significant mortality. The following article summarizes diagnostic tools and treatment options for these disorders. © Georg Thieme Verlag KG Stuttgart · New York.

  5. Upright in the storm of time. The physicist James Franck 1882-1964; Aufrecht im Sturm der Zeit. Der Physiker James Franck 1882-1964

    Energy Technology Data Exchange (ETDEWEB)

    Lemmerich, J.

    2007-07-01

    For the 125th birth day of James Franck in the year 2007 for the first time a scientific biography is presented. Born in Hamburg Franck dedicated himself to the exploration of the atom. Together with Gustav Hertz he succeeded in exciting of bound electrons by collision, whereby the atomic model of Bohr was confirmed. For this both got the Nobel price for the year 1925. Starting from 1921 Franck founded together with Max Born and Robert Pohl the world-wide reputation of Goettingen as a center of physical research. 1933 Franck resigned because of protest against the antisemitic policy of the Nazis and imigrated to the USA. There he dedicated himself to the exploration of the foundation of the photosynthesis. To the request to contribute the the construction of the atomic bomb the Hitler opponent not denied, but wrote after the German capitulation the Franck report in May 1945, in which he described impressively the arguments against the application of the bomb and warned for a nuclear armament race. Although he was because of the great crime of the Nazi regime very critical against the Germans soon after the war he stood up - very to the indignation of his friend Einstein - for the reconcilement and visited Germany and his friends there still several times. 1964 he died at a visit in Goettingen.

  6. Nonlinear chaotic model for predicting storm surges

    Directory of Open Access Journals (Sweden)

    M. Siek

    2010-09-01

    Full Text Available This paper addresses the use of the methods of nonlinear dynamics and chaos theory for building a predictive chaotic model from time series. The chaotic model predictions are made by the adaptive local models based on the dynamical neighbors found in the reconstructed phase space of the observables. We implemented the univariate and multivariate chaotic models with direct and multi-steps prediction techniques and optimized these models using an exhaustive search method. The built models were tested for predicting storm surge dynamics for different stormy conditions in the North Sea, and are compared to neural network models. The results show that the chaotic models can generally provide reliable and accurate short-term storm surge predictions.

  7. Overview of the ARkStorm scenario

    Science.gov (United States)

    Porter, Keith; Wein, Anne; Alpers, Charles N.; Baez, Allan; Barnard, Patrick L.; Carter, James; Corsi, Alessandra; Costner, James; Cox, Dale; Das, Tapash; Dettinger, Mike; Done, James; Eadie, Charles; Eymann, Marcia; Ferris, Justin; Gunturi, Prasad; Hughes, Mimi; Jarrett, Robert; Johnson, Laurie; Le-Griffin, Hanh Dam; Mitchell, David; Morman, Suzette; Neiman, Paul; Olsen, Anna; Perry, Suzanne; Plumlee, Geoffrey; Ralph, Martin; Reynolds, David; Rose, Adam; Schaefer, Kathleen; Serakos, Julie; Siembieda, William; Stock, Jonathan; Strong, David; Wing, Ian Sue; Tang, Alex; Thomas, Pete; Topping, Ken; Wills, Chris; Jones, Lucile

    2011-01-01

    coastal communities. Windspeeds in some places reach 125 miles per hour, hurricane-force winds. Across wider areas of the state, winds reach 60 miles per hour. Hundreds of landslides damage roads, highways, and homes. Property damage exceeds $300 billion, most from flooding. Demand surge (an increase in labor rates and other repair costs after major natural disasters) could increase property losses by 20 percent. Agricultural losses and other costs to repair lifelines, dewater (drain) flooded islands, and repair damage from landslides, brings the total direct property loss to nearly $400 billion, of which $20 to $30 billion would be recoverable through public and commercial insurance. Power, water, sewer, and other lifelines experience damage that takes weeks or months to restore. Flooding evacuation could involve 1.5 million residents in the inland region and delta counties. Business interruption costs reach $325 billion in addition to the $400 property repair costs, meaning that an ARkStorm could cost on the order of $725 billion, which is nearly 3 times the loss deemed to be realistic by the ShakeOut authors for a severe southern California earthquake, an event with roughly the same annual occurrence probability. The ARkStorm has several public policy implications: (1) An ARkStorm raises serious questions about the ability of existing federal, state, and local disaster planning to handle a disaster of this magnitude. (2) A core policy issue raised is whether to pay now to mitigate, or pay a lot more later for recovery. (3) Innovative financing solutions are likely to be needed to avoid fiscal crisis and adequately fund response and recovery costs from a similar, real, disaster. (4) Responders and government managers at all levels could be encouraged to conduct risk assessments, and devise the full spectrum of exercises, to exercise ability of their plans to address a similar event. (5) ARkStorm can be a reference point for application of Federal Emergency Ma

  8. Coastal Storm Surge Analysis: Storm Forcing. Report 3. Intermediate Submission No. 1.3

    Science.gov (United States)

    2013-07-01

    The storm surge study considers both tropical storms and extratropical cyclones for determination of return period storm surge elevations. The...Appendix B: Extratropical Cyclone Selection in Support of FEMA Region III Storm Surge Modeling...stations applied in the storm selection process. ............................................. 56  Table B2. Extratropical cyclones selected from the

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

    International Nuclear Information System (INIS)

    Ochabova, P.; Psenakova, M.

    1977-01-01

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

  10. Modeling of the outer electron belt during magnetic storms

    International Nuclear Information System (INIS)

    Desorgher, L.; Buehler, P.; Zehnder, A.; Daly, E.; Adams, L.

    1999-01-01

    The flux dropout of relativistic electrons in the earth's outer radiation belt, during the main phase of the 26 March 1995 magnetic storm is examined. Outer belt measurements by the Radiation Environment Monitor, REM aboard the STRV-1b satellite are presented to characterize this dropout. In order to simulate the dynamics of the electron belt during the storm main phase a particle tracing code was developed which allows to trace the trajectories of equatorially mirroring electrons in a dynamic magnetospheric electromagnetic field. Two simulations were performed in a non-stationary magnetic field, one taking only the induced electric field into account (fully adiabatic motion), and one with an additional non-stationary convection electric field. The simulations show, that adiabatic deceleration can produce the observed count rate decrease and also the observed inward motion of the count rate peak. The convection electric field causes diffusion, which can take particles from low L values out to the magnetopause and contribute to an additional loss of particles, which is suggested by the observations

  11. Ionosphere and thermosphere responses during August 1972 storms - a review

    International Nuclear Information System (INIS)

    Matsushita, S.

    1976-01-01

    Various reports of ionospheric responses during the August 1972 storm events are reviewed with respect to the phenomena in three major world sectors, N-S America, Afro-Europe, and Austro-Asia, in order to have a global picture. Emphasized highlights are (1) extensive investigation of the sudden increase of the total electron content estimated from Faraday-rotation measurements of satellite signals; (2) a dramatic upward surge above 300 km latitude, soon after a flare, measured by the Millstone Hill incoherent scatter radar; (3) electron density profiles, electric fields and conductivities, and neutral winds, at the time of the geomagnetic storm sudden commencement and during the succeeding storms, measured by the Chatanika incoherent scatter radar; and, (4) approximately 2.5-h oscillatory F2 density variations in Eastern Asia during the F2 storm main phase. To show temporal variations of the latitudinal distributions of storm-time F2 electron densities, in three longitudinal sectors separated about 60 0 longitude each, newly investigated results of the F2 hourly data at 35 stations in the Asia-Australia-Pacific sector are then exhibited. Finally, current theories or at least theoretical ideas of ionospheric storm mechanisms are briefly introduced, and a few remarks on the August events in the light of those theories are presented. (Auth.)

  12. Observation of low energy particle precipitation at low altitude in the equatorial zone

    International Nuclear Information System (INIS)

    Miah, M.A.

    1989-01-01

    Precipitation of protons (∼ 1 MeV) in the equatorial zone was investigated by the Phoenix-1 experiment on board the S81-1 mission from May-November, 1982. The protons show a precipitation peak along the line of minimum magnetic field strength with a full width at half maximum (FWHM) of 13 0 . The index of equatorial pitch angle distribution is q ∼ 19. The peak proton flux shows a fifth-power altitude dependence, and the proton flux shows approximately a factor of 3 times increase in 1982 compared to that in 1969 due, possibly, to the stronger (∼ 1.2 times) solar maximum conditions of 10.7 cm radiation in 1982. (author)

  13. Equatorial wave activity during 2007 over Gadanki, a tropical station

    Indian Academy of Sciences (India)

    been used to investigate the wave activity in the troposphere and lower stratosphere. Waves in the ...... Oltmans S J 2001 Water vapor control at the tropopause by equatorial Kelvin .... observed in UARS microwave limb sounder temperature.

  14. An overview on the equatorial electrojet theoretical grounds

    International Nuclear Information System (INIS)

    Zamlutti, C.J.; Sobral, J.H.A.; Abdu, M.A.

    1988-01-01

    The grounds on which the equatorial electrojet theory is based are reexamined in a way as to suggest specific additional implementations in the existing electrodynamical modeling of this phenomena, making use of now existing improved computer processing speeds. (author) [pt

  15. ITER L 6 equatorial maintenance duct remote handling study

    International Nuclear Information System (INIS)

    Millard, J.

    1996-09-01

    The status and conclusions of a preliminary study of equatorial maintenance duct remote handling is reported. Due to issues with the original duct design a significant portion of the study had to be refocused on equatorial duct layout studies. The study gives an overview of some of the options for design of these ducts and the impact of the design on the equipment to work in the duct. To develop a remote handling concept for creating access through the ducts the following design tasks should be performed: define the operations sequences for equatorial maintenance duct opening and closing; review the remote handling requirements for equatorial maintenance duct opening and closing; design concept for door and pipe handling equipment and to propose preliminary procedures for material handling outsides the duct. 35 figs

  16. Modelling the development of mixing height in near equatorial region

    Energy Technology Data Exchange (ETDEWEB)

    Samah, A.A. [Univ. of Malaya, Air Pollution Research Unit, Kuala Lumpur (Malaysia)

    1997-10-01

    Most current air pollution models were developed for mid-latitude conditions and as such many of the empirical parameters used were based on observations taken in the mid-latitude boundary layer which is physically different from that of the equatorial boundary layer. In the equatorial boundary layer the Coriolis parameter f is small or zero and moisture plays a more important role in the control of stability and the surface energy balance. Therefore air pollution models such as the OMLMULTI or the ADMS which were basically developed for mid-latitude conditions must be applied with some caution and would need some adaptation to properly simulate the properties of equatorial boundary layer. This work elucidates some of the problems of modelling the evolution of mixing height in the equatorial region. The mixing height estimates were compared with routine observations taken during a severe air pollution episodes in Malaysia. (au)

  17. An equatorial temperature and wind anomaly (ETWA)

    International Nuclear Information System (INIS)

    Raghavarao, R.; Wharton, L.E.; Mayr, H.G.; Brace, L.H.; Spencer, N.W.

    1991-01-01

    Data obtained from the WATS (Wind and Temperature Spectrometer) and LP (Langmuir Probe) experiments on board DE-2 (Dynamic Explorer) during high solar activity show evidence of anomalous latitudinal variations in the zonal winds and temperature at low latitudes. The zonal winds exhibit a broad maximum centered around the dip equator, flanked by minima on either side around 25 degrees; while the temperature exhibits a pronounced bowl-shaped minimum at the dip equator which is flanked by maxima. The two minima in the zonal winds and the corresponding maxima in the temperature are nearly collocated with the crests of the well known Equatorial Ionization Anomaly (EIA). The maximum in the zonal winds and the minimum in the gas temperature are collected with the trough of the EIA. The differences between the maxima and minima in temperature and zonal winds, on many occasions, are observed to exceed 100 K and 100 m/s, respectively. The characteristics of this new phenomenon have eluded present day empirical models of thermospheric temperature and winds. The connection among these variables can be understood from the ion-neutral drag effect on the motions of the neutrals that in turn affect their energy balance

  18. Condor equatorial electrojet campaign: Radar results

    International Nuclear Information System (INIS)

    Kudeki, E.; Fejer, B.G.; Farley, D.T.; Hanuise, C.

    1987-01-01

    A review of the experimental and theoretical background to the Condor equatorial electrojet compaign is followed by the presentation and discussion of VHF radar interferometer and HF radar backscatter data taken concurrently with two rocket in situ experiments reported in companion papers (Pfaff et al., this issue (a, b). Both experiments were conducted in strongly driven periods with the on-line radar interferometer displaying signatures of what has been interpreted in earlier radar work (Kudeki et al., 1982) as kilometer scale gradient drift waves. Low-frequency density fluctuations detected by in situ rocket sensors confirm the earlier interpretation. VHF radar/rocket data comparisons also indicate the existence of a turbulent layer in the upper portion of the daytime electrojet at about 108 km altitude driven purely by the two-stream instability. Nonlinear mode coupling of linearly growing two-stream waves to linearly damped 3-m vertical modes could account for the radar echoes scattered from this layer, which showed no indication of large-scale gradient drift waves. Nonlinear mode coupling may therefore compete with the wave-induced anomalous diffusion mechanism proposed recently by Sudan (1983) for the saturation of directly excited two-stream waves. Nighttime radar data show a bifurcated layer with the two parts having comparable echo strength but oppositely directed zonal drift velocities. The lower layer shows narrow backscatter spectra; the upper layer is characterized by kilometer scale waves and vertically propagating type 1 waves

  19. Radiation protection in hospitals of Equatorial Guinea

    International Nuclear Information System (INIS)

    Rabat Macambo, P.

    2001-01-01

    With a population of four hundred thousand (400.000) inhabitants and distributed in a territory of 28 thousand (28.000) km 2 , the use of ionizing radiations for medical practice in Equatorial Guinea is few and decreasing. It is used for diagnostic practices in the main hospitals of the country, where the work burden is not over 20 patients per day. The political, social and economical embryonic development of the country until recently had a negative influence on indicators and health organisations, so that even now the country does not have any radiological protection law, this shortness, in addition with the old architectural structure that x ray tools is lodging, as well as dosimetrical lack of employed staff, put this staff under risk of electromagnetic energy. This is to show the present survey of medical activities with ionizing radiation and to request technical support for implementing suitably the basic standards of radiation protection which will help us as basis for the elaboration outline law, on radiological protection in accordance with the new guidelines of the International Atomic Energy Agency. (author)

  20. Analytical approach to the investigation of Rayleigh-Taylor structures of the equatorial F region

    International Nuclear Information System (INIS)

    Komarov, V.N.; Sazonov, S.V.

    1991-01-01

    On the basis of approximation of a strong vertical extension the nonlinear dynamics of Rayleigh-Taylor structures in the equatorial F region is analytically studied. The successive approximation method, proposed herein, is true for structures having longitudinal symmetry. Using this method it is managed to describe the mushroom-shaped bubble with a shock wave profile in its head part. The nonlinearity leads to bubble formation under conditions with aggravation, limiting the growth of positive disturbances at the same time

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

    Directory of Open Access Journals (Sweden)

    G. Balasis

    2006-12-01

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

  2. Intraseasonal vertical velocity variation caused by the equatorial wave in the central equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Horii, T.; Masumoto, Y.; Ueki, I.; PrasannaKumar, S.; Mizuno, K.

    to the theoretical solution of the equatorial waves [Matsuno, 1966] and the phase speed of the baroclinic mode, the wave that has meridional current on the equator with a quasi-biweekly period is the anti-symmetric mixed Rossby-gravity wave. In the wave... and conclusions are given in section 5. 2. Field Experiment, Data, and Methods 2.1. MISMO Ocean Observation [8] The goal of MISMO was to observe atmospheric conditions and variability associated with intraseasonal disturbances and resulting ocean responses...

  3. The Effect of Neutral Winds on Simulated Inner Magnetospheric Electric Fields During the 17 March 2013 Storm

    Science.gov (United States)

    Chen, M.; Lemon, C.; Walterscheid, R. L.; Hecht, J. H.; Sazykin, S. Y.; Wolf, R.

    2017-12-01

    We investigate how neutral winds and particle precipitation affect the simulated development of electric fields including Sub-Auroral Polarization Streams (SAPS) during the 17 March 2013 storm. Our approach is to use the magnetically and electrically self-consistent Rice Convection Model - Equilibrium (RCM-E) to simulate the inner magnetospheric electric field. We use parameterized rates of whistler-generated electron pitch-angle scattering from Orlova and Shprits [JGR, 2014] that depend on equatorial radial distance, magnetic activity (Kp), and magnetic local time (MLT) outside the simulated plasmasphere. Inside the plasmasphere, parameterized scattering rates due to hiss [Orlova et al., GRL, 2014] are used. Ions are scattered at a fraction of strong pitch-angle scattering where the fraction is scaled by epsilon, the ratio of the gyroradius to the field-line radius of curvature, when epsilon is greater than 0.1. The electron and proton contributions to the auroral conductance in the RCM-E are calculated using the empirical Robinson et al. [JGR, 1987] and Galand and Richmond [JGR, 2001] equations, respectively. The "background" ionospheric conductance is based on parameters from the International Reference Ionosphere [Bilitza and Reinisch, JASR, 2008] but modified to include the effect of specified ionospheric troughs. Neutral winds are modeled by the empirical Horizontal Wind Model (HWM07) in the RCM-E. We compare simulated precipitating particle energy flux, E x B velocities with DMSP observations during the 17 March 2013 storm with and without the inclusion of neutral winds. Discrepancies between the simulations and observations will aid us in assessing needed improvements in the model.

  4. Comparisons of Simulated and Observed Sub-Auroral Polarization Stream (SAPS) during the 17 March 2013 Storm

    Science.gov (United States)

    Chen, M.; Lemon, C.; Sazykin, S. Y.; Wolf, R.; Anderson, P. C.

    2016-12-01

    Sub-Auroral Polarization Streams (SAPS), characterized by large subauroral E x B velocities that span from dusk to the early morning sector for high magnetic activity, result from strong magnetosphere-ionosphere coupling. We investigate how electron and ion precipitation and the ionospheric conductance affect the simulated development of the SAPS electric field for the 17 March 2013 storm. Our approach is to use the magnetically and electrically self-consistent Rice Convection Model - Equilibrium (RCM-E) of the inner magnetosphere to simulate the SAPS. We use parameterized rates of whistler-generated electron pitch-angle scattering from Orlova and Shprits [JGR, 2014] that depend on equatorial radial distance, magnetic activity (Kp), and magnetic local time (MLT) outside the simulated plasmasphere. Inside the plasmasphere, parameterized scattering rates due to hiss [Orlova et al., GRL, 2014] are used. Ions are scattered at a fraction of strong pitch-angle scattering where the fraction is scaled by epsilon, the ratio of the gyroradius to the field-line radius of curvature, when epsilon is greater than 0.1. The electron and proton contributions to the auroral conductance in the RCM-E are calculated using the empirical Robinson et al. [JGR, 1987] and Galand and Richmond [JGR, 2001] equations, respectively. The "background" ionospheric conductance is based on parameters from the International Reference Ionosphere [Bilitza and Reinisch, JASR, 2008] but modified to include the effect of specified ionospheric troughs. Parameterized simulations will aid in understanding the underlying physical process. We compare simulated precipitating particle energy flux and E x B velocities with DMSP observations where SAPS are observed during the 17 March 2013 storm. Analysis of discerpancies between the simulation results and data will aid us in assessing needed improvements in the model.

  5. Plasmaspheric noise radiation during geomagnetic storms

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  6. Performance evaluation of GPS receiver under equatorial scintillation

    Directory of Open Access Journals (Sweden)

    Alison de Oliveira Moraes

    2009-06-01

    Full Text Available Equatorial scintillation is a phenomenon that occurs daily in the equatorial region after the sunset and affects radio signals that propagate through the ionosphere. Depending on the temporal and spatial situation, equatorial scintillation can represent a problem in the availability and precision of the Global Positioning System (GPS. This work is concerned with evaluating the impact of equatorial scintillation on the performance of GPS receivers. First, the morphology and statistical model of equatorial scintillation is briefly presented. A numerical model that generates synthetic scintillation data to simulate the effects of equatorial scintillation is presented. An overview of the main theoretical principles on GPS receivers is presented. The analytical models that describe the effects of scintillation at receiver level are presented and compared with numerical simulations using a radio software receiver and synthetic data. The results achieved by simulation agreed quite well with those predicted by the analytical models. The only exception is for links with extreme levels of scintillation and when weak signals are received.

  7. Event storm detection and identification in communication systems

    International Nuclear Information System (INIS)

    Albaghdadi, Mouayad; Briley, Bruce; Evens, Martha

    2006-01-01

    Event storms are the manifestation of an important class of abnormal behaviors in communication systems. They occur when a large number of nodes throughout the system generate a set of events within a small period of time. It is essential for network management systems to detect every event storm and identify its cause, in order to prevent and repair potential system faults. This paper presents a set of techniques for the effective detection and identification of event storms in communication systems. First, we introduce a new algorithm to synchronize events to a single node in the system. Second, the system's event log is modeled as a normally distributed random process. This is achieved by using data analysis techniques to explore and then model the statistical behavior of the event log. Third, event storm detection is proposed using a simple test statistic combined with an exponential smoothing technique to overcome the non-stationary behavior of event logs. Fourth, the system is divided into non-overlapping regions to locate the main contributing regions of a storm. We show that this technique provides us with a method for event storm identification. Finally, experimental results from a commercially deployed multimedia communication system that uses these techniques demonstrate their effectiveness

  8. Coastal emergency managers' preferences for storm surge forecast communication.

    Science.gov (United States)

    Morrow, Betty Hearn; Lazo, Jeffrey K

    2014-01-01

    Storm surge, the most deadly hazard associated with tropical and extratropical cyclones, is the basis for most evacuation decisions by authorities. One factor believed to be associated with evacuation noncompliance is a lack of understanding of storm surge. To address this problem, federal agencies responsible for cyclone forecasts are seeking more effective ways of communicating storm surge threat. To inform this process, they are engaging various partners in the forecast and warning process.This project focuses on emergency managers. Fifty-three emergency managers (EMs) from the Gulf and lower Atlantic coasts were surveyed to elicit their experience with, sources of, and preferences for storm surge information. The emergency managers-who are well seasoned in hurricane response and generally rate the surge risk in their coastal areas above average or extremely high-listed storm surge as their major concern with respect to hurricanes. They reported a general lack of public awareness about surge. Overall they support new ways to convey the potential danger to the public, including the issuance of separate storm surge watches and warnings, and the expression of surge heights using feet above ground level. These EMs would like more maps, graphics, and visual materials for use in communicating with the public. An important concern is the timing of surge forecasts-whether they receive them early enough to be useful in their evacuation decisions.

  9. Magnetic storm effects on the mid-latitude plasmasphere

    International Nuclear Information System (INIS)

    Smith, A.J.; Clilverd, M.A.

    1991-01-01

    Whistler mode group delays observed at Faraday, Antarctica (65 o S,64 0 W) decrease after the onset of magnetic storms, and slowly recover to normal levels in 1 or 2 days. This is interpreted as a decrease (typically of ∼50%) and recovery of the plasmaspheric electron density at L = 2.5. Within 1 day of the main phase of storms with K p (max) between 6 and 8, the number of observed whistler ducts increases by a factor of 2 or 3, recovering in a few days. During the most intense storms (K p > 8) the duct number decreases. The frequency of occurrence of observed whistler mode signals increases during storms, due probably to enhanced ionospheric propagation of the signals; the storm time dependence implies that there is no link with the apparent increase in duct numbers. The amplitudes of received whistler mode signals are increased by up to a factor of 10 during storms: this is interpreted in terms of magnetospheric amplification through wave-particle interactions, though the evidence suggests that amplification is not necessarily the mechanism by which increased duct numbers are observed. There appears to be a real increase in the duct formation rate, consistent with Walker's (1978) theory in which ring current penetration of the plasmasphere creates a preferential region for duct formation 1.5 R E inside the plasmapause. (author)

  10. Developing Local Scale, High Resolution, Data to Interface with Numerical Storm Models

    Science.gov (United States)

    Witkop, R.; Becker, A.; Stempel, P.

    2017-12-01

    High resolution, physical storm models that can rapidly predict storm surge, inundation, rainfall, wind velocity and wave height at the intra-facility scale for any storm affecting Rhode Island have been developed by Researchers at the University of Rhode Island's (URI's) Graduate School of Oceanography (GSO) (Ginis et al., 2017). At the same time, URI's Marine Affairs Department has developed methods that inhere individual geographic points into GSO's models and enable the models to accurately incorporate local scale, high resolution data (Stempel et al., 2017). This combination allows URI's storm models to predict any storm's impacts on individual Rhode Island facilities in near real time. The research presented here determines how a coastal Rhode Island town's critical facility managers (FMs) perceive their assets as being vulnerable to quantifiable hurricane-related forces at the individual facility scale and explores methods to elicit this information from FMs in a format usable for incorporation into URI's storm models.

  11. Tormenta tiroidea Thyroid storm

    Directory of Open Access Journals (Sweden)

    Lisette Leal Curí

    2012-12-01

    Full Text Available La tormenta tiroidea es una de las situaciones más críticas entre las emergencias endocrinas y tiene una significativa mortalidad. La etiología más común de tirotoxicosis es la enfermedad de Graves y el factor precipitante que predomina es la infección. Clínicamente se caracteriza por la disfunción de varios sistemas (termorregulador, nervioso central, gastrointestinal y cardiovascular, con niveles de hormonas tiroideas libres o totales por encima de los valores normales. El tratamiento debe tener un enfoque multidisciplinario, e incluye medidas de soporte en unidades de cuidados intensivos, normalización de la temperatura corporal, reducción de la producción y liberación de hormonas tiroideas, con antitiroideos de síntesis y yodo respectivamente, bloqueo de los efectos periféricos mediante la administración de beta-bloqueadores, y corrección del factor desencadenante. Una vez que el paciente se encuentra estable es necesario planificar una terapia definitiva que impida la recurrencia futura de la crisis tirotóxica.The thyroid storm is one of the most critical situations in the endocrine emergencies and exhibits a significant mortality rate. The most common etiology of thyrotoxicosis is Graves' disease and the predominant precipitating factor is infection. The clinical characteristics are dysfunction of several systems (heat-regulator, central nervous, gastrointestinal and cardiovascular, and levels of total or free thyroid hormones that exceed the normal values. The treatment must be multidisciplinary and include support measures in intensive care units, normalization of body temperature, reduction of the production and the release of thyroid hormones by using synthesis and iodine anti-thyroid products respectively, blockade of the peripheral effects through administration of Beta-blockers and correction of the unleashing factor. Once the patients are stabilized, it is necessary to plan the final therapy that will prevent the

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

    Directory of Open Access Journals (Sweden)

    Ga-Hee Moon

    2011-06-01

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

  13. The ionospheric response in the Brazilian sector during the super geomagnetic storm on 20 November 2003

    Directory of Open Access Journals (Sweden)

    F. Becker-Guedes

    2007-05-01

    Full Text Available A very intense geomagnetic storm (superstorm began with storm sudden commencement (SSC at 08:03 UT on 20 November 2003, as a result of the coronal mass ejection (CME by sunspot 484 hurled into space on 18 November 2003. The geomagnetic storm attained |Dst|max=472 nT at 20:00 UT (20 November. In this paper we present the simultaneous ionospheric sounding observations, using the Canadian Advanced Digital Ionosondes (CADIs, carried out from Palmas (PAL; 10.2° S, 48.2° W; dip latitude 5.5° S; a near equatorial station and São José dos Campos (SJC; 23.2° S, 45.9° W; dip latitude 17.6° S; station located under the crest of equatorial ionospheric anomaly, Brazil. In addition, total electron content (TEC measurements from several GPS receiving stations in the Brazilian sector during this storm are presented. The simultaneous ionospheric sounding observations carried out at SJC and PAL, and TEC observations on 3 consecutive days viz., 19 November (quiet, 20 November (disturbed and 21 November (recovery phase are presented. Salient features from the ionospheric observations in the Brazilian sector during the superstorm are discussed. The difference in the observed ionospheric response at the two stations (PAL and SJC is considerable. This is not surprising given that PAL is close to the magnetic equator and SJC is near the crest of the equatorial ionospheric anomaly (EIA. It should be pointed out that soon after the SSC (about 4 h later, the F-region critical frequency (foF2, the F-region peak height (hpF2, and variations of virtual heights at different frequencies (iso-frequency plots all show wavelike oscillations of the F-region during daytime at both the ionospheric sounding stations. Unusual rapid uplifting of F-region at PAL was observed during both the main and recovery phases of the storm.

  14. Penetration of ELF currents and electromagnetic fields into the Earth's equatorial ionosphere

    Science.gov (United States)

    Eliasson, B.; Papadopoulos, K.

    2009-10-01

    The penetration of extremely low frequency (ELF) transient electromagnetic fields and associated currents in the Earth's equatorial E-region plasma is studied theoretically and numerically. In the low-frequency regime, the plasma dynamics of the E-region is characterized by helicon waves since the ions are viscously coupled to neutrals while the electrons remain mobile. For typical equatorial E-region parameters, the plasma is magnetically insulated from penetration of very long timescale magnetic fields by a thin diffusive sheath. Wave penetration driven by a vertically incident pulse localized in space and time leads to both vertical penetration and the triggering of ELF helicon/whistler waves that carry currents obliquely to the magnetic field lines. The study presented here may have relevance for ELF wave generation by lightning discharges and seismic activity and can lead to new concepts in ELF/ULF injection in the earth-ionosphere waveguide.

  15. Asymptotic approach for the nonlinear equatorial long wave interactions

    International Nuclear Information System (INIS)

    Ramirez Gutierrez, Enver; Silva Dias, Pedro L; Raupp, Carlos

    2011-01-01

    In the present work we use an asymptotic approach to obtain the long wave equations. The shallow water equation is put as a function of an external parameter that is a measure of both the spatial scales anisotropy and the fast to slow time ratio. The values given to the external parameters are consistent with those computed using typical values of the perturbations in tropical dynamics. Asymptotically, the model converge toward the long wave model. Thus, it is possible to go toward the long wave approximation through intermediate realizable states. With this approach, the resonant nonlinear wave interactions are studied. To simplify, the reduced dynamics of a single resonant triad is used for some selected equatorial trios. It was verified by both theoretical and numerical results that the nonlinear energy exchange period increases smoothly as we move toward the long wave approach. The magnitude of the energy exchanges is also modified, but in this case depends on the particular triad used and also on the initial energy partition among the triad components. Some implications of the results for the tropical dynamics are discussed. In particular, we discuss the implications of the results for El Nino and the Madden-Julian in connection with other scales of time and spatial variability.

  16. Ionospheric variations during the 13 September 1967 storm

    International Nuclear Information System (INIS)

    Goel, M.K.; Rao, B.C.N.

    1980-01-01

    The storm time variations in N sub(e), T sub(e), and ion drifts are studied for a mid-latitude station, St. Santin (44.11 0 N, 2.3 0 E) using incoherent scatter radar data. It is observed that there is an increase in N sub(e) with a corresponding decrease in T sub(e) at 350 km and the drifts are upward when compared with the quiet time drifts. These drifts are shown to be related to changes in magnetic field and hence they may be due to an electrodynamic effect. It is established from the N sub(e) and T sub(e) profile changes that the differences in the ionospheric effects at different times reported earlier by the authors for the same storm are due to the storm-time effect and not due to a longitude effect. (author)

  17. The Locations of Ring Current Pressure Peaks: Comparison of TWINS Measurements and CIMI Simulations for the 7-10 September 2015 CIR Storm

    Science.gov (United States)

    Hill, S. C.; Edmond, J. A.; Xu, H.; Perez, J. D.; Fok, M. C. H.; Goldstein, J.; McComas, D. J.; Valek, P. W.

    2017-12-01

    The characteristics of a four day 7-10 September 2015 co-rotating interaction region (CIR) storm (min. SYM/H ≤ -110 nT) are categorized by storm phase. Ion distributions of trapped particles in the ring current as measured by the Two Wide-Angle Imaging Neutral Atom Spectrometers (TWINS) are compared with the simulated ion distributions of the Comprehensive Inner Magnetosphere-Ionosphere Model (CIMI). The energetic neutral atom (ENA) images obtained by TWINS are deconvolved to extract equatorial pitch angle, energy spectra, ion pressure intensity, and ion pressure anisotropy distributions in the inner magnetosphere. CIMI, using either a self-consistent electric field or a semi-empirical electric field, simulates comparable distributions. There is good agreement between the data measured by TWINS and the different distributions produced by the self-consistent electric field and the semi-empirical electric field of CIMI. Throughout the storm the pitch angle distribution (PAD) is mostly perpendicular in both CIMI and TWINS and there is agreement between the anisotropy distributions. The locations of the ion pressure peaks seen by TWINS and by the self-consistent and semi empirical electric field parameters in CIMI are usually between dusk and midnight. On average, the self-consistent electric field in CIMI reveals ion pressure peaks closer to Earth than its semi empirical counterpart, while TWINS reports somewhat larger radial values for the ion pressure peak locations. There are also notable events throughout the storm during which the simulated observations show some characteristics that differ from those measured by TWINS. At times, there are ion pressure peaks with magnetic local time on the dayside and in the midnight to dawn region. We discuss these events in light of substorm injections indicated by fluctuating peaks in the AE index and a positive By component in the solar wind. There are also times in which there are multiple ion pressure peaks. This may

  18. Authigenic Uranium in Eastern Equatorial Pacific Sediments

    Science.gov (United States)

    Marcantonio, F.; Lyle, M. W.; Loveley, M. R.; Ibrahim, R.

    2014-12-01

    Authigenic U concentrations have been used as an indicator of redox state in marine sediments. Soluble U(VI) in porewaters is reduced to insoluble U(IV) under suboxic conditions setting up a diffusion gradient through which U in bottom waters is supplied to reducing sediments. Researchers have used sedimentary redox enrichment of U as a tool to identify past redox changes, which may be caused by changes in organic carbon rain rates and/or bottom water oxygen levels. Differentiating between these two explanations is important, as the former is tied to the use of authigenic U as a paleoproductivity proxy. We examined sediments from 4 sediment cores retrieved from two different localities in the Panama Basin in the eastern equatorial Pacific. Two cores were retrieved from the northern Panama basin at the Cocos Ridge, (4JC at 5° 44.7'N 85° 45.5' W, 1730 m depth; 8JC at 6° 14.0'N 86° 2.6' W, 1993 m depth), and two were retrieved from the south at the Carnegie Ridge, (11JC at 0° 41.6'S 85° 20.0' W, 2452 m depth; 17JC at 0° 10.8'S 85° 52.0' W, 2846 m depth). Using 230Th systematics and seismic profiling at each of the sites, we've identified significant sediment winnowing (4JC and 11JC) and focusing (8JC and 17JC). At all sites, we believe that changes in age-model-derived sand (i.e., >63µm) mass accumulation rates (MAR) best represent changes in rain rates. Glacial rain rates are higher than those in the Holocene by a factor of 2-3 at both sites. Peak Mn levels (>1%), the brown-to-green color transition (which likely represents the oxic/post-oxic boundary), and peak U concentrations all appear in the same order with increasing depth down core. At the Carnegie sites, where MARs are greater than those at the Cocos sites, increases in authigenic U (up to 4 ppm) occur during the mid- to late Holocene at depths of 10-15 cm. At the Cocos sites, increases in authigenic U (up to 12 ppm) occur lower in the sediment column (25-30 cm) during the late glacial. The decrease

  19. Observations and global numerical modelling of the St. Patrick's Day 2015 geomagnetic storm event

    Science.gov (United States)

    Foerster, M.; Prokhorov, B. E.; Doornbos, E.; Astafieva, E.; Zakharenkova, I.

    2017-12-01

    With a sudden storm commencement (SSC) at 04:45 UT on St. Patrick's day 2015 started the most severe geomagnetic storm in solar cycle 24. It appeared as a two-stage geomagnetic storm with a minimum SYM-H value of -233 nT. In the response to the storm commencement in the first activation, a short-term positive effect in the ionospheric vertical electron content (VTEC) occurred at low- and mid-latitudes on the dayside. The second phase commencing around 12:30 UT lasted longer and caused significant and complex storm-time changes around the globe with hemispherical different ionospheric storm reactions in different longitudinal ranges. Swarm-C observations of the neutral mass density variation along the orbital path as well as Langmuir probe plasma and magnetometer measurements of all three Swarm satellites and global TEC records are used for physical interpretations and modelling of the positive/negative storm scenario. These observations pose a challenge for the global numerical modelling of thermosphere-ionosphere storm processes as the storm, which occurred around spring equinox, obviously signify the existence of other impact factors than seasonal dependence for hemispheric asymmetries to occur. Numerical simulation trials using the Potsdam version of the Upper Atmosphere Model (UAM-P) are presented to explain these peculiar M-I-T storm processes.

  20. Using Satellite Altimetry to Calibrate the Simulation of Typhoon Seth Storm Surge off Southeast China

    Directory of Open Access Journals (Sweden)

    Xiaohui Li

    2018-04-01

    Full Text Available Satellite altimeters can capture storm surges generated by typhoons and tropical storms, if the satellite flies over at the right time. In this study, we show TOPEX/Poseidon altimeter-observed storm surge features off Southeast China on 10 October 1994 during Typhoon Seth. We then use a three-dimensional, barotropic, finite-volume community ocean model (FVCOM to simulate storm surges. An innovative aspect is that satellite data are used to calibrate the storm surge model to improve model performance, by adjusting model wind forcing fields (the National Center for Environment Prediction (NCEP reanalysis product in reference to the typhoon best-track data. The calibration reduces the along-track root-mean-square (RMS difference between model and altimetric data from 0.15 to 0.10 m. It also reduces the RMS temporal difference from 0.21 to 0.18 m between the model results and independent tide-gauge data at Xiamen. In particular, the calibrated model produces a peak storm surge of 1.01 m at 6:00 10 October 1994 at Xiamen, agreeing with tide-gauge data; while the peak storm surge with the NCEP forcing is 0.71 m only. We further show that the interaction between storm surges and astronomical tides contributes to the peak storm surge by 34% and that the storm surge propagates southwestward as a coastally-trapped Kelvin wave.

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

    Directory of Open Access Journals (Sweden)

    D. V. Blagoveshchensky

    2008-06-01

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

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

    Directory of Open Access Journals (Sweden)

    D. V. Blagoveshchensky

    2008-06-01

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

  3. Deciphering Equatorial Pacific Deep Sea Sediment Transport Regimes by Core-Log-Seismic Integration

    Science.gov (United States)

    Ortiz, E.; Tominaga, M.; Marcantonio, F.

    2017-12-01

    Investigating deep-sea sediment transportation and deposition regimes is a key to accurately understand implications from geological information recorded by pelagic sediments, e.g. climate signals. However, except for physical oceanographic particle trap experiments, geochemical analyses of in situsediments, and theoretical modeling of the relation between the bottom currents and sediment particle flux, it has remained a challenging task to document the movement of deep sea sediments, that takes place over time. We utilized high-resolution, multichannel reflection seismic data from the eastern equatorial Pacific region with drilling and logging results from two Integrated Ocean Drilling Program (IODP) sites, the Pacific Equatorial Age Transect (PEAT) 7 (Site U1337) and 8 (Site U1338), to characterize sediment transportation regimes on 18-24 Ma oceanic crust. Site U1337, constructed by a series of distinct abyssal hills and abyssal basins; Site U1338, located 570 km SE from Site U1337 site and constructed by a series of ridges, seamounts, and abyssal hills. These sites are of particular interest due to their proximity to the equatorial productivity zone, areas with high sedimentation rates and preservation of carbonate-bearing sediment that provide invaluable insights on equatorial Pacific ecosystems and carbon cycle. We integrate downhole geophysical logging data as well as geochemistry and physical properties measurements on recovered cores from IODP Sites U1337 and U1338 to comprehensively examine the mobility of deep-sea sediments and sediment diagenesis over times in a quasi-3D manner. We also examine 1100 km of high resolution underway seismic surveys from site survey lines in between PEAT 7 and 8 in order to investigate changes in sediment transportation between both sites. Integrating detailed seismic interpretations, high resolution core data, and 230Th flux measurements we aim to create a detailed chronological sedimentation and sediment diagenesis history

  4. The Genesis of Tropical Cyclone Bilis (2000) Associated with Cross-equatorial Surges

    Institute of Scientific and Technical Information of China (English)

    XU Yamei

    2011-01-01

    The purpose of this paper is to explore how a tropical cyclone forms from a pre-existing large-scale depression which has been observed and associated with cross-equatorial surges in the western North Pacific. Tropical cyclone Bilis (2000) was selected as the case to study. The research data used are from the results of the non-hydrostatic mesoscale model (MM5), which has successfully simulated the transformation of a pre-existing weak large-scale tropical depression into a strong tropical storm. The scale separation technique is used to separate the synoptic-scale and sub-synoptic-scale fields from the model output fields. The scale-separated fields show that the pre-existing synoptic-scale tropical depression and the subsynoptic scale tropical cyclone formed later were different scale systems from beginning to end. It is also shown that the pre-existing synoptic-scale tropical depression did not contract to become the tropical cyclone. A series of weak, sub-synoptic-scale low and high pressure systems appeared and disappeared in the synopticscale depression, with one of the low systems near the center of the synoptic-scale depression having deepened to become the tropical cyclone. The roles of the synoptic-scale flow and the sub-synoptic scale disturbances in the formation of the tropical cyclone are investigated by diagnoses of the scale-separated vertical vorticity equation. The results show that the early development of the sub-synoptic scale vortex was fundamentally dependent on the strengthening synoptic-scale environmental depression. The depression was strengthened by cross-equatorial surges, which increased the convergence of the synoptic-scale depression at low levels and triggered the formation of the tropical cyclone.

  5. Nonlinear bounce resonances between magnetosonic waves and equatorially mirroring electrons

    Science.gov (United States)

    Chen, Lunjin; Maldonado, Armando; Bortnik, Jacob; Thorne, Richard M.; Li, Jinxing; Dai, Lei; Zhan, Xiaoya

    2015-08-01

    Equatorially mirroring energetic electrons pose an interesting scientific problem, since they generally cannot resonate with any known plasma waves and hence cannot be scattered down to lower pitch angles. Observationally it is well known that the flux of these equatorial particles does not simply continue to build up indefinitely, and so a mechanism must necessarily exist that transports these particles from an equatorial pitch angle of 90° down to lower values. However, this mechanism has not been uniquely identified yet. Here we investigate the mechanism of bounce resonance with equatorial noise (or fast magnetosonic waves). A test particle simulation is used to examine the effects of monochromatic magnetosonic waves on the equatorially mirroring energetic electrons, with a special interest in characterizing the effectiveness of bounce resonances. Our analysis shows that bounce resonances can occur at the first three harmonics of the bounce frequency (nωb, n = 1, 2, and 3) and can effectively reduce the equatorial pitch angle to values where resonant scattering by whistler mode waves becomes possible. We demonstrate that the nature of bounce resonance is nonlinear, and we propose a nonlinear oscillation model for characterizing bounce resonances using two key parameters, effective wave amplitude à and normalized wave number k~z. The threshold for higher harmonic resonance is more strict, favoring higher à and k~z, and the change in equatorial pitch angle is strongly controlled by k~z. We also investigate the dependence of bounce resonance effects on various physical parameters, including wave amplitude, frequency, wave normal angle and initial phase, plasma density, and electron energy. It is found that the effect of bounce resonance is sensitive to the wave normal angle. We suggest that the bounce resonant interaction might lead to an observed pitch angle distribution with a minimum at 90°.

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

    Science.gov (United States)

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

    2016-07-01

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

  7. Developing an early warning system for storm surge inundation in the Philippines

    Science.gov (United States)

    Tablazon, J.; Caro, C. V.; Lagmay, A. M. F.; Briones, J. B. L.; Dasallas, L.; Lapidez, J. P.; Santiago, J.; Suarez, J. K.; Ladiero, C.; Gonzalo, L. A.; Mungcal, M. T. F.; Malano, V.

    2014-10-01

    A storm surge is the sudden rise of sea water generated by an approaching storm, over and above the astronomical tides. This event imposes a major threat in the Philippine coastal areas, as manifested by Typhoon Haiyan on 8 November 2013 where more than 6000 people lost their lives. It has become evident that the need to develop an early warning system for storm surges is of utmost importance. To provide forecasts of the possible storm surge heights of an approaching typhoon, the Nationwide Operational Assessment of Hazards under the Department of Science and Technology (DOST-Project NOAH) simulated historical tropical cyclones that entered the Philippine Area of Responsibility. Bathymetric data, storm track, central atmospheric pressure, and maximum wind speed were used as parameters for the Japan Meteorological Agency Storm Surge Model. The researchers calculated the frequency distribution of maximum storm surge heights of all typhoons under a specific Public Storm Warning Signal (PSWS) that passed through a particular coastal area. This determines the storm surge height corresponding to a given probability of occurrence. The storm surge heights from the model were added to the maximum astronomical tide data from WXTide software. The team then created maps of probable area inundation and flood levels of storm surges along coastal areas for a specific PSWS using the results of the frequency distribution. These maps were developed from the time series data of the storm tide at 10 min intervals of all observation points in the Philippines. This information will be beneficial in developing early warnings systems, static maps, disaster mitigation and preparedness plans, vulnerability assessments, risk-sensitive land use plans, shoreline defense efforts, and coastal protection measures. Moreover, these will support the local government units' mandate to raise public awareness, disseminate information about storm surge hazards, and implement appropriate counter

  8. Space storms as natural hazards

    Directory of Open Access Journals (Sweden)

    L. I. Dorman

    2008-04-01

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

  9. Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21–22 January 2005

    Directory of Open Access Journals (Sweden)

    Y. Sahai

    2011-05-01

    Full Text Available In the present investigation, we have studied the response of the ionospheric F-region in the Latin American sector during the intense geomagnetic storm of 21–22 January 2005. This geomagnetic storm has been considered "anomalous" (minimum Dst reached −105 nT at 07:00 UT on 22 January because the main storm phase occurred during the northward excursion of the Bz component of interplanetary magnetic fields (IMFs. The monthly mean F10.7 solar flux for the month of January 2005 was 99.0 sfu. The F-region parameters observed by ionosondes at Ramey (RAM; 18.5° N, 67.1° W, Puerto Rico, Jicamarca (JIC; 12.0° S, 76.8° W, Peru, Manaus (MAN; 2.9° S, 60.0° W, and São José dos Campos (SJC; 23.2° S, 45.9° W, Brazil, during 21–22 January (geomagnetically disturbed and 25 January (geomagnetically quiet have been analyzed. Both JIC and MAN, the equatorial stations, show unusually rapid uplifting of the F-region peak heights (hpF2/hmF2 and a decrease in the NmF2 coincident with the time of storm sudden commencement (SSC. The observed variations in the F-region ionospheric parameters are compared with the TIMEGCM model run for 21–22 January and the model results show both similarities and differences from the observed results. Average GPS-TEC (21, 22 and 25 January and phase fluctuations (21, 22, 25, 26 January observed at Belem (BELE; 1.5° S, 48.5° W, Brasilia (BRAZ; 15.9° S, 47.9° W, Presidente Prudente (UEPP; 22.3° S, 51.4° W, and Porto Alegre (POAL; 30.1° S, 51.1° W, Brazil, are also presented. These GPS stations belong to the RBMC/IBGE network of Brazil. A few hours after the onset of the storm, large enhancements in the VTEC and NmF2 between about 20:00 and 24:00 UT on 21 January were observed at all the stations. However, the increase in VTEC was greatest at the near equatorial station (BELE and enhancements in VTEC decreased with latitude. It should be pointed out that no phase fluctuations or spread-F were observed in the Latin

  10. Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21-22 January 2005

    Science.gov (United States)

    Sahai, Y.; Fagundes, P. R.; de Jesus, R.; de Abreu, A. J.; Crowley, G.; Kikuchi, T.; Huang, C.-S.; Pillat, V. G.; Guarnieri, F. L.; Abalde, J. R.; Bittencourt, J. A.

    2011-05-01

    In the present investigation, we have studied the response of the ionospheric F-region in the Latin American sector during the intense geomagnetic storm of 21-22 January 2005. This geomagnetic storm has been considered "anomalous" (minimum Dst reached -105 nT at 07:00 UT on 22 January) because the main storm phase occurred during the northward excursion of the Bz component of interplanetary magnetic fields (IMFs). The monthly mean F10.7 solar flux for the month of January 2005 was 99.0 sfu. The F-region parameters observed by ionosondes at Ramey (RAM; 18.5° N, 67.1° W), Puerto Rico, Jicamarca (JIC; 12.0° S, 76.8° W), Peru, Manaus (MAN; 2.9° S, 60.0° W), and São José dos Campos (SJC; 23.2° S, 45.9° W), Brazil, during 21-22 January (geomagnetically disturbed) and 25 January (geomagnetically quiet) have been analyzed. Both JIC and MAN, the equatorial stations, show unusually rapid uplifting of the F-region peak heights (hpF2/hmF2) and a decrease in the NmF2 coincident with the time of storm sudden commencement (SSC). The observed variations in the F-region ionospheric parameters are compared with the TIMEGCM model run for 21-22 January and the model results show both similarities and differences from the observed results. Average GPS-TEC (21, 22 and 25 January) and phase fluctuations (21, 22, 25, 26 January) observed at Belem (BELE; 1.5° S, 48.5° W), Brasilia (BRAZ; 15.9° S, 47.9° W), Presidente Prudente (UEPP; 22.3° S, 51.4° W), and Porto Alegre (POAL; 30.1° S, 51.1° W), Brazil, are also presented. These GPS stations belong to the RBMC/IBGE network of Brazil. A few hours after the onset of the storm, large enhancements in the VTEC and NmF2 between about 20:00 and 24:00 UT on 21 January were observed at all the stations. However, the increase in VTEC was greatest at the near equatorial station (BELE) and enhancements in VTEC decreased with latitude. It should be pointed out that no phase fluctuations or spread-F were observed in the Latin American

  11. Adaptive optics stochastic optical reconstruction microscopy (AO-STORM) by particle swarm optimization.

    Science.gov (United States)

    Tehrani, Kayvan F; Zhang, Yiwen; Shen, Ping; Kner, Peter

    2017-11-01

    Stochastic optical reconstruction microscopy (STORM) can achieve resolutions of better than 20nm imaging single fluorescently labeled cells. However, when optical aberrations induced by larger biological samples degrade the point spread function (PSF), the localization accuracy and number of localizations are both reduced, destroying the resolution of STORM. Adaptive optics (AO) can be used to correct the wavefront, restoring the high resolution of STORM. A challenge for AO-STORM microscopy is the development of robust optimization algorithms which can efficiently correct the wavefront from stochastic raw STORM images. Here we present the implementation of a particle swarm optimization (PSO) approach with a Fourier metric for real-time correction of wavefront aberrations during STORM acquisition. We apply our approach to imaging boutons 100 μm deep inside the central nervous system (CNS) of Drosophila melanogaster larvae achieving a resolution of 146 nm.

  12. Impacts on coralligenous outcrop biodiversity of a dramatic coastal storm.

    Directory of Open Access Journals (Sweden)

    Núria Teixidó

    Full Text Available Extreme events are rare, stochastic perturbations that can cause abrupt and dramatic ecological change within a short period of time relative to the lifespan of organisms. Studies over time provide exceptional opportunities to detect the effects of extreme climatic events and to measure their impacts by quantifying rates of change at population and community levels. In this study, we show how an extreme storm event affected the dynamics of benthic coralligenous outcrops in the NW Mediterranean Sea using data acquired before (2006-2008 and after the impact (2009-2010 at four different sites. Storms of comparable severity have been documented to occur occasionally within periods of 50 years in the Mediterranean Sea. We assessed the effects derived from the storm comparing changes in benthic community composition at sites exposed to and sheltered from this extreme event. The sites analyzed showed different damage from severe to negligible. The most exposed and impacted site experienced a major shift immediately after the storm, represented by changes in the species richness and beta diversity of benthic species. This site also showed higher compositional variability immediately after the storm and over the following year. The loss of cover of benthic species resulted between 22% and 58%. The damage across these species (e.g. calcareous algae, sponges, anthozoans, bryozoans, tunicates was uneven, and those with fragile forms were the most impacted, showing cover losses up to 50 to 100%. Interestingly, small patches survived after the storm and began to grow slightly during the following year. In contrast, sheltered sites showed no significant changes in all the studied parameters, indicating no variations due to the storm. This study provides new insights into the responses to large and rare extreme events of Mediterranean communities with low dynamics and long-lived species, which are among the most threatened by the effects of global change.

  13. Seasonal influence of ENSO on the Atlantic ITCZ and equatorial South America

    Science.gov (United States)

    Münnich, M.; Neelin, J. D.

    2005-11-01

    In late boreal spring, especially May, a strong relationship exists in observations among precipitation anomalies over equatorial South America and the Atlantic intertropical convergence zone (ITCZ), and eastern equatorial Pacific and central equatorial Atlantic sea surface temperature anomalies (SSTA). A chain of correlations of equatorial Pacific SSTA, western equatorial Atlantic wind stress (WEA), equatorial Atlantic SSTA, sea surface height, and precipitation supports a causal chain in which El Niño/Southern Oscillation (ENSO) induces WEA stress anomalies, which in turn affect Atlantic equatorial ocean dynamics. These correlations show strong seasonality, apparently arising within the atmospheric links of the chain. This pathway and the influence of equatorial Atlantic SSTA on South American rainfall in May appear independent of that of the northern tropical Atlantic. Brazil's Nordeste is affected by the northern tropical Atlantic. The equatorial influence lies further to the north over the eastern Amazon and the Guiana Highlands.

  14. Patterns of Storm Injury and Tree Response

    Science.gov (United States)

    Kevin Smith; Walter Shortle; Kenneth Dudzik

    2001-01-01

    The ice storm of January 1998 in the northeastern United States and adjacent Canada was an extreme example of severe weather that injures trees every year. Broken branches, split branch forks, and snapped stems are all examples of storm injury.

  15. Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, L.; Landi, E., E-mail: lzh@umich.edu [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48105 (United States)

    2014-02-01

    Fast solar wind can be accelerated from at least two different sources: polar coronal holes and equatorial coronal holes. Little is known about the relationship between the wind coming from these two different latitudes and whether these two subcategories of fast wind evolve in the same way during the solar cycle. Nineteen years of Ulysses observations, from 1990 to 2009, combined with ACE observations from 1998 to the present provide us with in situ measurements of solar wind properties that span two entire solar cycles. These missions provide an ideal data set to study the properties and evolution of the fast solar wind originating from equatorial and polar holes. In this work, we focus on these two types of fast solar wind during the minima between solar cycles 22 and 23 and 23 and 24. We use data from SWICS, SWOOPS, and VHM/FGM on board Ulysses and SWICS, SWEPAM, and MAG on board ACE to analyze the proton kinetic, thermal, and dynamic characteristics, heavy ion composition, and magnetic field properties of these two fast winds. The comparison shows that: (1) their kinetic, thermal, compositional, and magnetic properties are significantly different at any time during the two minima and (2) they respond differently to the changes in solar activity from cycle 23 to 24. These results indicate that equatorial and polar fast solar wind are two separate subcategories of fast wind. We discuss the implications of these results and relate them to remote-sensing measurements of the properties of polar and equatorial coronal holes carried out in the inner corona during these two solar minima.

  16. Investigation of Jupiter's Equatorial Hotspots and Plumes Using Cassini ISS Observations

    Science.gov (United States)

    Choi, David S.; Showman, A. P.; Vasavada, A. R.; Simon-Miller, A. A.

    2012-01-01

    We present updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the ISS onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial 5-micron hot spots and their interactions with adjacent latitudes. Hot spots are quasi-stable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but a diffuse western edge serving as a nebulous boundary with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-iike 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. This raises the possibility that the plumes and fast-moving clouds are at higher altitudes, because their speed does not match previously published zonal wind profiles. Most profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby waves controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed. Instead, our expanded data set demonstrating the rapid flow of these scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. This research was supported by a NASA JDAP grant and the NASA Postdoctoral Program.

  17. Deglacial Western Equatorial Pacific pCO2 Reconstruction Using Boron Isotopes of Planktonic Foraminiferas

    Science.gov (United States)

    Kubota, K.; Yokoyama, Y.; Ishikawa, T.; Sagawa, T.; Ikehara, M.; Yamazaki, T.

    2017-12-01

    During the last deglaciation (ca. 19 - 11 ka), partial pressure of CO2 (pCO2) of the atmosphere increased by 80 μatm. Many paleoceanographers point out that the ocean had played an important role in atmospheric CO2 rise, since the ocean have 60 times larger capacity to store carbon compared to the atmosphere. However, evidence on where carbon was transferred from the ocean to the atmosphere is still lacking, hampering our understanding of global carbon cycles in glacial-interglacial timescales. Boron isotope of skeletons of marine calcifying organisms such as corals and foraminiferas can pin down where CO2 source/sink existed, because boron isotopes of marine calcium carbonates is dependent on seawater pH, from which pCO2 of the past seawater can be reconstructed. In previous studies using the boron isotope teqnique, Martinez-Boti et al. (2015, Nature) and Kubota et al. (2014, Scientific Reports) revealed that central and eastern parts of the equatorial Pacific acted as a CO2 source (i.e., CO2 emission) during the last deglaciation, suggesting the equatorial Pacific's contribution to atmospheric CO2 rise. However, some conflicting results have been confirmed in a marine sediment record from the western part of the equatorial Pacific (Palmer & Pearson, 2003, Science), making the conclusion elusive. In this presentation, we will show new results of Mg/Ca, oxygen isotope, and boron isotope measurements during the last 35 ka on two species of surface dwelling foraminiferas (Globigerinoides ruber and G. sacculifer) which was hand-picked separatedly from a well-dated marine sediment core recovered from the West Caroline Basin (KR05-15 PC01) (Yamazaki et al., 2008, GRL). From the new records, we will discuss how the equatorial Pacific behaved during the last deglaciation and how it related to the global carbon cycles.

  18. ENSO-driven nutrient variability recorded by central equatorial Pacific corals

    Science.gov (United States)

    LaVigne, M.; Nurhati, I. S.; Cobb, K. M.; McGregor, H. V.; Sinclair, D. J.; Sherrell, R. M.

    2012-12-01

    Recent evidence for shifts in global ocean primary productivity suggests that surface ocean nutrient availability is a key link between global climate and ocean carbon cycling. Time-series records from satellite, in situ buoy sensors, and bottle sampling have documented the impact of the El Niño Southern Oscillation (ENSO) on equatorial Pacific hydrography and broad changes in biogeochemistry since the late 1990's, however, data are sparse prior to this. Here we use a new paleoceanographic nutrient proxy, coral P/Ca, to explore the impact of ENSO on nutrient availability in the central equatorial Pacific at higher-resolution than available from in situ nutrient data. Corals from Christmas (157°W 2°N) and Fanning (159°W 4°N) Islands recorded a well-documented decrease in equatorial upwelling as a ~40% decrease in P/Ca during the 1997-98 ENSO cycle, validating the application of this proxy to Pacific Porites corals. We compare the biogeochemical shifts observed through the 1997-98 event with two pre-TOGA-TAO ENSO cycles (1982-83 and 1986-87) reconstructed from a longer Christmas Island core. All three corals revealed ~30-40% P/Ca depletions during ENSO warming as a result of decreased regional wind stress, thermocline depth, and equatorial upwelling velocity. However, at the termination of each El Niño event, surface nutrients did not return to pre-ENSO levels for ~4-12 months after, SST as a result of increased biological draw down of surface nutrients. These records demonstrate the utility of high-resolution coral nutrient archives for understanding the impact of tropical Pacific climate on the nutrient and carbon cycling of this key region.

  19. Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona

    International Nuclear Information System (INIS)

    Zhao, L.; Landi, E.

    2014-01-01

    Fast solar wind can be accelerated from at least two different sources: polar coronal holes and equatorial coronal holes. Little is known about the relationship between the wind coming from these two different latitudes and whether these two subcategories of fast wind evolve in the same way during the solar cycle. Nineteen years of Ulysses observations, from 1990 to 2009, combined with ACE observations from 1998 to the present provide us with in situ measurements of solar wind properties that span two entire solar cycles. These missions provide an ideal data set to study the properties and evolution of the fast solar wind originating from equatorial and polar holes. In this work, we focus on these two types of fast solar wind during the minima between solar cycles 22 and 23 and 23 and 24. We use data from SWICS, SWOOPS, and VHM/FGM on board Ulysses and SWICS, SWEPAM, and MAG on board ACE to analyze the proton kinetic, thermal, and dynamic characteristics, heavy ion composition, and magnetic field properties of these two fast winds. The comparison shows that: (1) their kinetic, thermal, compositional, and magnetic properties are significantly different at any time during the two minima and (2) they respond differently to the changes in solar activity from cycle 23 to 24. These results indicate that equatorial and polar fast solar wind are two separate subcategories of fast wind. We discuss the implications of these results and relate them to remote-sensing measurements of the properties of polar and equatorial coronal holes carried out in the inner corona during these two solar minima.

  20. Equatorial Scintillation Study at Ilorin and Nsukka, Nigeria during Year 2011-2012

    Science.gov (United States)

    Akala, A.

    2017-12-01

    This study presents GNSS scintillations over Ilorin (8.48 oN, 4.54 oE, and mag lat: 1.83oS) and Nsukka (6.84 oN, 7.37 oE, and mag lat: 2.94oS), Nigeria during year 2011-2012. The two stations are located within the inner flank of the equatorial ionization anomaly. Firstly, we investigated the climatology of equatorial scintillations at the two stations. We suppressed multipath effects on the data by imposing a 300 elevation masking on the data. In addition, we investigated scintillation occurrences at the two locations on a satellite-by-satellite basis at varying elevation angles. The source of scintillation records at low-elevation angle is attributed to multipath, while that at high-elevation angle is attributed to ionospheric irregularities. Seasonally, scintillations recorded highest occurrences during March equinox, and the least during June solstice. The trend of scintillations, at both low- and high-elevation angles at the two stations were almost the same. EGNOS satellites signals scintillated at the two locations during the time intervals when GPS satellites signals experienced scintillations. These results could support the development of scintillation models for equatorial Africa, and could also be of benefit to GPS and EGNOS service providers and designers, with a view to providing robust services for GNSS user community in Africa.

  1. Observations in equatorial anomaly region of total electron content enhancements and depletions

    Directory of Open Access Journals (Sweden)

    N. Dashora

    2005-10-01

    Full Text Available A GSV 4004A GPS receiver has been operational near the crest of the equatorial anomaly at Udaipur, India for some time now. The receiver provides the line-of-sight total electron content (TEC, the phase and amplitude scintillation index, σφ and S4, respectively. This paper presents the first results on the nighttime TEC depletions associated with the equatorial spread F in the Indian zone. The TEC depletions are found to be very well correlated with the increased S4 index. A new feature of low-latitude TEC is also reported, concerning the observation of isolated and localized TEC enhancements in the nighttime low-latitude ionosphere. The TEC enhancements are not correlated with the S4 index. The TEC enhancements have also been observed along with the TEC depletions. The TEC enhancements have been interpreted as the manifestation of the plasma density enhancements reported by Le et al. (2003.

    Keywords. Ionosphere (Equatorial ionosphere; Ionospheric irregularities

  2. Survival probability of precipitations and rain attenuation in tropical and equatorial regions

    Science.gov (United States)

    Mohebbi Nia, Masoud; Din, Jafri; Panagopoulos, Athanasios D.; Lam, Hong Yin

    2015-08-01

    This contribution presents a stochastic model useful for the generation of a long-term tropospheric rain attenuation time series for Earth space or a terrestrial radio link in tropical and equatorial heavy rain regions based on the well-known Cox-Ingersoll-Ross model previously employed in research in the fields of finance and economics. This model assumes typical gamma distribution for rain attenuation in heavy rain climatic regions and utilises the temporal dynamic of precipitation collected in equatorial Johor, Malaysia. Different formations of survival probability are also discussed. Furthermore, the correlation between these probabilities and the Markov process is determined, and information on the variance and autocorrelation function of rain events with respect to the particular characteristics of precipitation in this area is presented. The proposed technique proved to preserve the peculiarities of precipitation for an equatorial region and reproduce fairly good statistics of the rain attenuation correlation function that could help to improve the prediction of dynamic characteristics of rain fade events.

  3. Storm Water Management Model (SWMM)

    Science.gov (United States)

    Stormwater discharges continue to cause impairment of our Nation’s waterbodies. Regulations that require the retention and/or treatment of frequent, small storms that dominate runoff volumes and pollutant loads are becoming more common. The U.S. Environmental Protection Agency (E...

  4. Stochastic Optical Reconstruction Microscopy (STORM).

    Science.gov (United States)

    Xu, Jianquan; Ma, Hongqiang; Liu, Yang

    2017-07-05

    Super-resolution (SR) fluorescence microscopy, a class of optical microscopy techniques at a spatial resolution below the diffraction limit, has revolutionized the way we study biology, as recognized by the Nobel Prize in Chemistry in 2014. Stochastic optical reconstruction microscopy (STORM), a widely used SR technique, is based on the principle of single molecule localization. STORM routinely achieves a spatial resolution of 20 to 30 nm, a ten-fold improvement compared to conventional optical microscopy. Among all SR techniques, STORM offers a high spatial resolution with simple optical instrumentation and standard organic fluorescent dyes, but it is also prone to image artifacts and degraded image resolution due to improper sample preparation or imaging conditions. It requires careful optimization of all three aspects-sample preparation, image acquisition, and image reconstruction-to ensure a high-quality STORM image, which will be extensively discussed in this unit. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

  5. Measuring storm tide and high-water marks caused by Hurricane Sandy in New York: Chapter 2

    Science.gov (United States)

    Simonson, Amy E.; Behrens, Riley

    2015-01-01

    In response to Hurricane Sandy, personnel from the U.S. Geological Survey (USGS) deployed a temporary network of storm-tide sensors from Virginia to Maine. During the storm, real-time water levels were available from tide gages and rapid-deployment gages (RDGs). After the storm, USGS scientists retrieved the storm-tide sensors and RDGs and surveyed high-water marks. These data demonstrate that the timing of peak storm surge relative to astronomical tide was extremely important in southeastern New York. For example, along the south shores of New York City and western Suffolk County, the peak storm surge of 6–9 ft generally coincided with the astronomical high tide, which resulted in substantial coastal flooding. In the Peconic Estuary and northern Nassau County, however, the peak storm surge of 9 ft and nearly 12 ft, respectively, nearly coincided with normal low tide, which helped spare these communities from more severe coastal flooding.

  6. Shoreline resilience to individual storms and storm clusters on a meso-macrotidal barred beach

    NARCIS (Netherlands)

    Angnuureng, Donatus Bapentire; Almar, Rafael; Senechal, Nadia; Castelle, Bruno; Addo, Kwasi Appeaning; Marieu, Vincent; Ranasinghe, Roshanka

    2017-01-01

    This study investigates the impact of individual storms and storm clusters on shoreline recovery for the meso-to macrotidal, barred Biscarrosse beach in SW France, using 6 years of daily video observations. While the study area experienced 60 storms during the 6-year study period, only 36 storms

  7. Space Weather Monitoring for ISS Geomagnetic Storm Studies

    Science.gov (United States)

    Minow, Joseph I.; Parker, Linda Neergaard

    2013-01-01

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

  8. 46 CFR 108.221 - Storm rails.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Storm rails. 108.221 Section 108.221 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the following...

  9. 46 CFR 169.329 - Storm rails.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must be...

  10. Er Storm P. en hardcore vagabond?

    DEFF Research Database (Denmark)

    Sortkær, Allan

    2002-01-01

    Den vagabond, som vi kender som Storm P.s, er ikke en figur, der kom fra en guddommelig inspiration eller deslige. Den var en allerede velkendt figur, før Storm P. tog den til sig, og figuren gennemgik radikale forandringer gennem Storm P.s liv: Krads social satire, hypervoldelig eller hyggelig...

  11. 46 CFR 116.920 - Storm rails.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Storm rails. 116.920 Section 116.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE THAN 150... and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must be installed where necessary...

  12. 46 CFR 177.920 - Storm rails.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Storm rails. 177.920 Section 177.920 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must be...

  13. 46 CFR 127.320 - Storm rails.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Storm rails. 127.320 Section 127.320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in each passageway and at...

  14. Development of VLF noise storm and its relation to dynamics of magnetosphere during geomagnetic storms

    International Nuclear Information System (INIS)

    Fedyakina, N.I.; Khorosheva, O.V.

    1989-01-01

    Dependence between the development of geomagnetic storm and VLF noise storm is studied. Two conditions should be met for the development of noise storm in VLF-hiss (f ≅ 0.5-10 kHz): a) threshold intensity of electron fluxes with E e > 40 keV in plasma layers; b) the presence of substorms resulting to widening of electron belt and its collision with cold plasma of plasmasphere. The noise storm at the fixed longitude begins about midnight independently of the phase of magnetic storm; Noise storm duration is connected with geomagnetic storm intensity by direct linear relationship

  15. Energetic neutral atom precipitation during magnetic storms: optical emission, ionization, and energy deposition at low and middle latitudes

    International Nuclear Information System (INIS)

    Tinsley, B.A.

    1979-01-01

    Observations of hydrogen Balmer β and He + 4686-A emission made at Huancayo, Peru, during two magnetic storms are consistent with the expectations of energetic neutral atom precipitation resulting from charge exchange loss of ring current ions and support the view that charge exchange is the major loss process for larger geomagnetic storms. The intensities are consistent with previous satellite observations of the emission (called the equatorial aurora) and when translated into ionization rates for the upper E region give production rates in order of magnitude larger than normal nighttime levels. Such ionization enhancements have previously been measured by ionosondes and incoherent scatter at low latitudes and attributed to electron precipitation. New calculations of the latitude variation correct earlier work and show that for a ring current with pitch angle distribution isotropic to the loss cone, located on shells of L value 2 to 6, the maximum influx rate of precipitating neutrals is found at magnetic latitudes 25 0 to 50 0 . Most of the energetic neutrals are lost to interplanetary space, and the fraction impacting the thermosphere has been recalculated to range from 11 to 2.2% for L values 2 to 6. For a typical magnetic storm with energy loss rate due to charge exchange, the equivalent to a Dst rate of change of 20 n T/h, the energy input into the thermosphere at the latitude of maximum is calculated to be 0.15 to 0.05 mW/m 2 from L shells 2 to 6. The ionization production can be of the order of 10 ions cm 3 s 1 at 140 km, and optical emission, of the order of 1 rayleigh (R), both varying according to the species and energy of the impacting neutrals (i.e., the former ring current ions). The latitude distribution shrinks toward the equator after injection has ceased, as the magnetospheric pitch angle distribution evolves toward 90 0 , on a time scale (for protons <30 keV at L=3) of the order of 2 hours

  16. Multivariate Hybrid Modelling of Future Wave-Storms at the Northwestern Black Sea

    Directory of Open Access Journals (Sweden)

    Jue Lin-Ye

    2018-02-01

    Full Text Available The characterization of future wave-storms and their relationship to large-scale climate can provide useful information for environmental or urban planning at coastal areas. A hybrid methodology (process-based and statistical was used to characterize the extreme wave-climate at the northwestern Black Sea. The Simulating WAve Nearshore spectral wave-model was employed to produce wave-climate projections, forced with wind-fields projections for two climate change scenarios: Representative Concentration Pathways (RCPs 4.5 and 8.5. A non-stationary multivariate statistical model was built, considering significant wave-height and peak-wave-period at the peak of the wave-storm, as well as storm total energy and storm-duration. The climate indices of the North Atlantic Oscillation, East Atlantic Pattern, and Scandinavian Pattern have been used as covariates to link to storminess, wave-storm threshold, and wave-storm components in the statistical model. The results show that, first, under both RCP scenarios, the mean values of significant wave-height and peak-wave-period at the peak of the wave-storm remain fairly constant over the 21st century. Second, the mean value of storm total energy is more markedly increasing in the RCP4.5 scenario than in the RCP8.5 scenario. Third, the mean value of storm-duration is increasing in the RCP4.5 scenario, as opposed to the constant trend in the RCP8.5 scenario. The variance of each wave-storm component increases when the corresponding mean value increases under both RCP scenarios. During the 21st century, the East Atlantic Pattern and changes in its pattern have a special influence on wave-storm conditions. Apart from the individual characteristics of each wave-storm component, wave-storms with both extreme energy and duration can be expected in the 21st century. The dependence between all the wave-storm components is moderate, but grows with time and, in general, the severe emission scenario of RCP8.5 presents

  17. Large enhancements in low latitude total electron content during 15 May 2005 geomagnetic storm in Indian zone

    Directory of Open Access Journals (Sweden)

    N. Dashora

    2009-05-01

    Full Text Available Results pertaining to the response of the equatorial and low latitude ionosphere to a major geomagnetic storm that occurred on 15 May 2005 are presented. These results are also the first from the Indian zone in terms of (i GPS derived total electron content (TEC variations following the storm (ii Local low latitude electrodynamics response to penetration of high latitude convection electric field (iii effect of storm induced traveling atmospheric disturbances (TAD's on GPS-TEC in equatorial ionization anomaly (EIA zone. Data set comprising of ionospheric TEC obtained from GPS measurements, ionograms from an EIA zone station, New Delhi (Geog. Lat. 28.42° N, Geog. Long. 77.21° E, ground based magnetometers in equatorial and low latitude stations and solar wind data obtained from Advanced Composition Explorer (ACE has been used in the present study. GPS receivers located at Udaipur (Geog. Lat. 24.73° N, Geog. Long. 73.73° E and Hyderabad (Geog. Lat. 17.33° N, Geog. Long. 78.47° E have been used for wider spatial coverage in the Indian zone. Storm induced features in vertical TEC (VTEC have been obtained comparing them with the mean VTEC of quiet days. Variations in solar wind parameters, as obtained from ACE and in the SYM-H index, indicate that the storm commenced on 15 May 2005 at 02:39 UT. The main phase of the storm commenced at 06:00 UT on 15 May with a sudden southward turning of the Z-component of interplanetary magnetic field (IMF-Bz and subsequent decrease in SYM-H index. The dawn-to-dusk convection electric field of high latitude origin penetrated to low and equatorial latitudes simultaneously as corroborated by the magnetometer data from the Indian zone. Subsequent northward turning of the IMF-Bz, and the penetration of the dusk-to-dawn electric field over the dip equator is also discernible. Response of the low latitude ionosphere to this storm may be characterized in terms of (i enhanced background level of VTEC as compared to

  18. Large enhancements in low latitude total electron content during 15 May 2005 geomagnetic storm in Indian zone

    Directory of Open Access Journals (Sweden)

    N. Dashora

    2009-05-01

    Full Text Available Results pertaining to the response of the equatorial and low latitude ionosphere to a major geomagnetic storm that occurred on 15 May 2005 are presented. These results are also the first from the Indian zone in terms of (i GPS derived total electron content (TEC variations following the storm (ii Local low latitude electrodynamics response to penetration of high latitude convection electric field (iii effect of storm induced traveling atmospheric disturbances (TAD's on GPS-TEC in equatorial ionization anomaly (EIA zone.

    Data set comprising of ionospheric TEC obtained from GPS measurements, ionograms from an EIA zone station, New Delhi (Geog. Lat. 28.42° N, Geog. Long. 77.21° E, ground based magnetometers in equatorial and low latitude stations and solar wind data obtained from Advanced Composition Explorer (ACE has been used in the present study. GPS receivers located at Udaipur (Geog. Lat. 24.73° N, Geog. Long. 73.73° E and Hyderabad (Geog. Lat. 17.33° N, Geog. Long. 78.47° E have been used for wider spatial coverage in the Indian zone. Storm induced features in vertical TEC (VTEC have been obtained comparing them with the mean VTEC of quiet days. Variations in solar wind parameters, as obtained from ACE and in the SYM-H index, indicate that the storm commenced on 15 May 2005 at 02:39 UT. The main phase of the storm commenced at 06:00 UT on 15 May with a sudden southward turning of the Z-component of interplanetary magnetic field (IMF-Bz and subsequent decrease in SYM-H index. The dawn-to-dusk convection electric field of high latitude origin penetrated to low and equatorial latitudes simultaneously as corroborated by the magnetometer data from the Indian zone. Subsequent northward turning of the IMF-Bz, and the penetration of the dusk-to-dawn electric field over the dip equator is also discernible. Response of the low latitude ionosphere to this storm may be characterized in terms of (i

  19. Effect of magnetic activity on plasma bubbles over equatorial and low-latitude regions in East Asia

    Directory of Open Access Journals (Sweden)

    G. Li

    2009-01-01

    Full Text Available The dependence of plasma bubble occurrence in the eveningside ionosphere, with magnetic activity during the period years 2001–2004, is studied here based on the TEC observations gathered by ground-based GPS receivers which are located in the equatorial and low-latitude regions in East Asia. The observed plasma bubbles consist of the plasma-bubble events in the equatorial (stations GUAM, PIMO and KAYT, and low-latitude regions (stations WUHN, DAEJ and SHAO. It is shown that most equatorial plasma-bubble events commence at 20:00 LT, and may last for >60 min. The magnetic activity appears to suppress the generation of equatorial plasma bubbles with a time delay of more than 3 h (4–9 h. While in the low-latitude regions, most plasma-bubble events commence at about 23:00 LT and last for <45 min. The best correlation between Kp and low-latitude plasma-bubble occurrence is found with an 8–9 h delay, a weak correlation exists for time delays of 6–7 h. This probably indicates that over 3 h delayed disturbance dynamo electric fields obviously inhibit the development of plasma bubbles in the pre-midnight sector.

  20. Molecular characterization of Cryptosporidium isolates from humans in Equatorial Guinea.

    Science.gov (United States)

    Blanco, María Alejandra; Iborra, Asunción; Vargas, Antonio; Nsie, Eugenia; Mbá, Luciano; Fuentes, Isabel

    2009-12-01

    The aim of the study was to perform a molecular characterization of clinical isolates of Cryptosporidium species from Equatorial Guinea. Standard laboratory methods were used to identify 35 cryptosporidiosis cases among 185 patients. PCR-RFLP successfully identified 34 Cryptosporidium species from these 35 cases, comprising C. parvum (52.9%), C. hominis (44.1%) and C. meleagridis (2.9%); over 90% of the species were isolated from HIV-positive patients. This is the first report of the molecular characterization of Cryptosporidium species isolated from humans in Equatorial Guinea and shows that zoonotic and anthroponotic transmission is present in this country.

  1. Storm surge in the Bay of Bengal and Arabian Sea: The problem and its prediction

    Digital Repository Service at National Institute of Oceanography (India)

    Dube, S.K.; Rao, A.D.; Sinha, P.C.; Murty, T.S.; Bahulayan, N.

    to annual economic losses in these countries. Thus, the real time monitoring and warning of storm surge is of great concern for this region. The goal of this paper is to provide an overview of major aspects of the storm surge problem in the Bay of Bengal...

  2. Data Assimilation within the Advanced Circulation (ADCIRC) Modeling Framework for Hurricane Storm Surge Forecasting

    KAUST Repository

    Butler, T.; Altaf, Muhammad; Dawson, C.; Hoteit, Ibrahim; Luo, X.; Mayo, T.

    2012-01-01

    levels, and wave heights—during these extreme events. This type of data, if available in real time, could be used in a data assimilation framework to improve hurricane storm surge forecasts. In this paper a data assimilation methodology for storm surge

  3. Response of wave-dominated and mixed-energy barriers to storms

    NARCIS (Netherlands)

    Masselink, G.; Heteren, S. van

    2014-01-01

    Wave-dominated and mixed-energy barriers are extremely dynamic landforms, responding to processes operating over a spectrum of time scales, ranging from daily-to-monthly fluctuations related to storm and post-storm conditions, to century-to-millennium-scale evolution driven by relative sea-level

  4. Mars atmospheric phenomena during major dust storms, as measured at surface

    International Nuclear Information System (INIS)

    Ryan, J.A.; Henry, R.M.

    1979-01-01

    Meteorological instrumentation aboard the Viking Mars Landers measures wind, temperature, and pressure. Two global dust storms occurred during northern autumn and winter, observed both by the orbiters and by the landers. The meteorological data from the landers has been analyzed for the period just before first storm arrival to just after second storm arrival, with the objectives being definition of meteorological phenomena during the storm period, determination of those associated with storm and dust arrival, and evaluation of effects on synoptic conditions and the general circulation. Times of dust arrival over the sites could be defined fairly closely from optical and pressure (solar tide) data, and dust arrival was also accompanied by changes in diurnal temperature range, temperature maxima, and temperature minima. The arrivals of the storms at VL-1 were accompanied by significant increase in wind speed and pressure. No such changes were observed at VL-2. It is possible that surface material could have been raised locally at VL-1. Throughout the period except following the second dust storm synoptic picture at VL-2 was one of eastward moving cyclonic and anticyclonic systems. These disappeared following the second storm, a phenomenon which may be related to the storm

  5. Toward a new paradigm for boulder dislodgement during storms

    Science.gov (United States)

    Weiss, Robert; Sheremet, Alex

    2017-07-01

    Boulders are an important coastal hazard event deposit because they can only be moved by tsunamis and energetic storms effects of storms. Storms and tsunami are competing processes for coastal change along many shorelines. Therefore, distinguishing the boulders that were moved during a storm from those moved by a tsunami is important. In this contribution, we present the results of a parameter study based on the TRIADS model for wave shoaling on mildly sloping beaches, coupled with a boulder-dislodgement model that is based on Newton's Second Law of Motion. The results show how smaller slopes expose the waves longer to the nonlinear processes, thus increasing the energy in the infragravity wave band. More energy in the infragravity wave band means that there are more energy wave lengths that can dislodge larger boulders. At the same time, a steeper slope lowers the threshold for boulder dislodgement (critical angle of dislodgement), making it more likely for larger boulders to be dislodged on a steeper slope. The competition between these two processes govern boulder dislodgement during storms and is investigated inhere.

  6. Next-generation storm tracking for minimizing service interruption

    Energy Technology Data Exchange (ETDEWEB)

    Sznaider, R. [Meteorlogix, Minneapolis, MN (United States)

    2002-08-01

    Several technological changes have taken place in the field of weather radar since its discovery during World War II. A wide variety of industries have benefited over the years from conventional weather radar displays, providing assistance in forecasting and estimating the potential severity of storms. The characteristics of individual storm cells can now be derived from the next-generation of weather radar systems (NEXRAD). The determination of which storm cells possess distinct features such as large hail or developing tornadoes was made possible through the fusing of various pieces of information with radar pictures. To exactly determine when and where a storm will hit, this data can be combined and overlaid into a display that includes the geographical physical landmarks of a specific region. Combining Geographic Information Systems (GIS) and storm tracking provides a more complete, timely and accurate forecast, which clearly benefits the electric utilities industries. The generation and production of energy are dependent on how hot or cold it will be today and tomorrow. The author described each major feature of this next-generation weather radar system. 9 figs.

  7. Nitrate Removal Rates in Denitrifying Bioreactors During Storm Flows

    Science.gov (United States)

    Pluer, W.; Walter, T.

    2017-12-01

    Field denitrifying bioreactors are designed to reduce excess nitrate (NO3-) pollution in runoff from agricultural fields. Field bioreactors saturate organic matter to create conditions that facilitate microbial denitrification. Prior studies using steady flow in lab-scale bioreactors showed that a hydraulic retention time (HRT) between 4 and 10 hours was optimal for reducing NO3- loads. However, during storm-induced events, flow rate and actual HRT fluctuate. These fluctuations have the potential to disrupt the system in significant ways that are not captured by the idealized steady-flow HRT models. The goal of this study was to investigate removal rate during dynamic storm flows of variable rates and durations. Our results indicate that storm peak flow and duration were not significant controlling variables. Instead, we found high correlations (p=0.004) in average removal rates between bioreactors displaying a predominantly uniform flow pattern compared with bioreactors that exhibited preferential flow (24.4 and 21.4 g N m-3 d-1, respectively). This suggests that the internal flow patterns are a more significant driver of removal rate than external factors of the storm hydrograph. Designing for flow patterns in addition to theoretical HRT will facilitate complete mixing within the bioreactors. This will help maximize excess NO3- removal during large storm-induced runoff events.

  8. Storm/substorm signatures in the outer belt

    International Nuclear Information System (INIS)

    Korth, A.; Friedel, R.H.W.; Mouikis, C.; Fennell, J.F.

    1998-01-01

    The response of the ring current region is compared for periods of storm and substorm activity, with an attempt to isolate the contributions of both processes. The authors investigate CRRES particle data in an overview format that allows the display of long-term variations of the outer radiation belt. They compare the evolution of the ring current population to indicators of storm (Dst) and substorm (AE) activity and examine compositional changes. Substorm activity leads to the intensification of the ring current at higher L (L ∼ 6) and lower ring current energies compared to storms (L ∼ 4). The O + /H + ratio during substorms remains low, near 10%, but is much enhanced during storms (can exceed 100%). They conclude that repeated substorms with an AE ∼ 900 nT lead to a ΔDst of ∼ 30 nT, but do not contribute to Dst during storm main phase as substorm injections do not form a symmetric ring current during such disturbed times

  9. Storm runoff analysis using environmental isotopes and major ions

    International Nuclear Information System (INIS)

    Fritz, P.; Cherry, J.A.; Sklash, M.; Weyer, K.U.

    1976-01-01

    At a given locality the oxygen-18 content of rainwater varies from storm to storm but within broad seasonal trends. Very frequently, especially during heavy summer storms, the stable isotope composition of rainwater differs from that of the groundwater in the area. This isotopic difference can be used to differentiate between 'prestorm' and 'rain' components in storm runoff. This approach to the use of natural 18 O was applied in four hydrogeologically very different basins in Canada. Their surface areas range from less than 2km 2 to more than 700km 2 . Before, during and after the storm events samples of stream water, groundwater and rain were analysed for 18 O and in some cases for deuterium, major ions and electrical conductance. The 18 O hydrograph separations show that groundwater was a major component of the runoff in each of the basins, and usually exceeded 50% of the total water discharged. Even at peak stream flow most of discharge was subsurface water. The identification of geographic sources rather than time sources appears possible if isotope techniques are used in conjunction with chemical analyses, hydrological data - such as flow measurements - and visual observations. (author)

  10. [Diagnosis and treatment of thyroid storm].

    Science.gov (United States)

    Akamizu, Takashi

    2012-11-01

    Thyrotoxic storm is a life-threatening condition requiring emergency treatment. Neither its epidemiological data nor diagnostic criteria have been fully established. We clarified the clinical and epidemiological characteristics of thyroid storm using nationwide surveys and then formulate diagnostic criteria for thyroid storm. To perform the nationwide survey on thyroid storm, we first developed tentative diagnostic criteria for thyroid storm, mainly based upon the literature (the first edition). We analyzed the relationship of the major features of thyroid storm to mortality and to certain other features. Finally, based upon the findings of these surveys, we revised the diagnostic criteria. Thyrotoxic storm is still a life-threatening disorder with over 10% mortality in Japan.

  11. Thermospheric storms and related ionospheric effects

    International Nuclear Information System (INIS)

    Chandra, S.; Spencer, N.W.

    1976-01-01

    A comparative study of thermospheric storms for the equinox and winter conditions is presented based on the neutral composition measurements from the Aeros-A Nate (Neutral Atmosphere Temperature Experiment) experiment. The main features of the two storms as inferred from the changes in N 2 , Ar, He, and O are described, and their implications to current theories of thermospheric storms are discussed. On the basis of the study of the F region critical frequency measured from a chain of ground-based ionospheric stations during the two storm periods, the general characteristics of the ionospheric storms and the traveling ionospheric disturbances are described. It is suggested that the positive and negative phases of ionospheric storms are the various manifestations of thermospheric storms

  12. Thyroid storm precipitated by duodenal ulcer perforation.

    Science.gov (United States)

    Natsuda, Shoko; Nakashima, Yomi; Horie, Ichiro; Ando, Takao; Kawakami, Atsushi

    2015-01-01

    Thyroid storm is a rare and life-threatening complication of thyrotoxicosis that requires prompt treatment. Thyroid storm is also known to be associated with precipitating events. The simultaneous treatment of thyroid storm and its precipitant, when they are recognized, in a patient is recommended; otherwise such disorders, including thyroid storm, can exacerbate each other. Here we report the case of a thyroid storm patient (a 55-year-old Japanese male) complicated with a perforated duodenal ulcer. The patient was successfully treated with intensive treatment for thyroid storm and a prompt operation. Although it is believed that peptic ulcer rarely coexists with hyperthyroidism, among patients with thyroid storm, perforation of a peptic ulcer has been reported as one of the causes of fatal outcome. We determined that surgical intervention was required in this patient, reported despite ongoing severe thyrotoxicosis, and reported herein a successful outcome.

  13. Thyroid Storm Precipitated by Duodenal Ulcer Perforation

    Directory of Open Access Journals (Sweden)

    Shoko Natsuda

    2015-01-01

    Full Text Available Thyroid storm is a rare and life-threatening complication of thyrotoxicosis that requires prompt treatment. Thyroid storm is also known to be associated with precipitating events. The simultaneous treatment of thyroid storm and its precipitant, when they are recognized, in a patient is recommended; otherwise such disorders, including thyroid storm, can exacerbate each other. Here we report the case of a thyroid storm patient (a 55-year-old Japanese male complicated with a perforated duodenal ulcer. The patient was successfully treated with intensive treatment for thyroid storm and a prompt operation. Although it is believed that peptic ulcer rarely coexists with hyperthyroidism, among patients with thyroid storm, perforation of a peptic ulcer has been reported as one of the causes of fatal outcome. We determined that surgical intervention was required in this patient, reported despite ongoing severe thyrotoxicosis, and reported herein a successful outcome.

  14. Magnetic storms on Mars

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne

    2011-01-01

    and typical time profile of such periods is investigated and compared to solar wind measurements at Earth. Typical durations of the events are 20–40h, and there is a tendency for large events to last longer, but a large spread in duration and intensity are found. The large and medium intensity events at Mars......Based on data from the Mars Global Surveyor magnetometer we examine periods of significantly enhanced magnetic disturbances in the martian space environment. Using almost seven years of observations during the maximum and early declining phase of the previous solar cycle the occurrence pattern...... are found to occur predominantly in association with interplanetary sector boundaries, with solar wind dynamic pressure enhancements being the most likely interplanetary driver. In addition it is found that, on time scales of months to several years, the dominant cause of global variability of the magnetic...

  15. Navigating the storm: report and recommendations from the Atlantic Storm exercise.

    Science.gov (United States)

    Smith, Bradley T; Inglesby, Thomas V; Brimmer, Esther; Borio, Luciana; Franco, Crystal; Gronvall, Gigi Kwik; Kramer, Bradley; Maldin, Beth; Nuzzo, Jennifer B; Schuler, Ari; Stern, Scott; Henderson, Donald A; Larsen, Randall J; Hamilton, Daniel S; O'Toole, Tara

    2005-01-01

    Atlantic Storm was a tabletop exercise simulating a series of bioterrorism attacks on the transatlantic community. The exercise occurred on January 14, 2005, in Washington, DC, and was organized and convened by the Center for Biosecurity of UPMC, the Center for Transatlantic Relations of Johns Hopkins University, and the Transatlantic Biosecurity Network. Atlantic Storm portrayed a summit meeting of presidents, prime ministers, and other international leaders from both sides of the Atlantic Ocean in which they responded to a campaign of bioterrorist attacks in several countries. The summit principals, who were all current or former senior government leaders, were challenged to address issues such as attaining situational awareness in the wake of a bioattack, coping with scarcity of critical medical resources such as vaccine, deciding how to manage the movement of people across borders, and communicating with their publics. Atlantic Storm illustrated that much might be done in advance to minimize the illness and death, as well as the social, economic, and political disruption, that could be caused by an international epidemic, be it natural or the result of a bioterrorist attack. These lessons are especially timely given the growing concerns over the possibility of an avian influenza pandemic that would require an international response. However, international leaders cannot create the necessary response systems in the midst of a crisis. Medical, public health, and diplomatic response systems and critical medical resources (e.g., medicines and vaccines) must be in place before a bioattack occurs or a pandemic emerges.

  16. Cloud and Wind Variability in Saturn's Equatorial Jet prior to the Cassini orbital tour

    Science.gov (United States)

    Sánchez-Lavega, A.; Pérez-Hoyos, S.; Hueso, R.; Rojas, J. F.; French, R. G.

    2004-11-01

    We use ground-based observations (going back to 1876), Pioneer-11 data (1979), Voyager 1 and 2 encounter images in 1980 and 1981, and HST 1990-2004 images, to study the changes that occurred in the vertical cloud structure and morphology and motions, in Saturn's Equatorial Region (approximately the band between latitudes 40 deg North and South). We compare ``calm periods" with ``stormy periods" i. e. those that occur during the development of the phenomenon known as the ``Great White Spots." We discuss different interpretations of the mechanisms that can be involved in the observed changes: vertical wind shears, waves, storm - mean flow interaction and changes in atmospheric angular momentum. Acknowledgements: This work was supported by the Spanish MCYT AYA 2003-03216. SPH acknowledges a PhD fellowship from the Spanish MECD and RH a post-doc fellowship from Gobierno Vasco. RGF was supported in part by NASA's Planetary Geology and Geophysics Program NAG5-10197 and STSCI Grant GO-08660.01A.

  17. Upper ocean circulation modulation by phytoplankton concentration in the Equatorial Pacific and the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nakamoto, S.; PrasannaKumar, S.; Oberhuber, J.M.; Sammarco, P.; Muneyama, K.; Sato, T.; AjoyKumar, A.; Frouin, R.

    gradient in the upper ocean. This strengthens the geostrophically balanced westward currents in both side of the equatorial wave-guide (within 5 degree bands). Once these currents reach the western Pacific coast, they feed the Equatorial undercurrent (EUC...

  18. Coastal wave measurements during passage of tropical storm Amy

    Science.gov (United States)

    Morris, W. D.

    1977-01-01

    Aerial photographic and laser profilometer data of waves generated by tropical storm Amy are presented. The data mission consisted primarily of two legs, one in the direction of the wind waves, and the second along the direction of swell propagation, using Jennette's Pier at Nags Head, North Carolina, as a focal point. At flight time, Amy's center was 512 nmi from shore and had maximum winds of 60 knots. The storm's history is presented, along with a satellite photograph, showing the extent of the storm on the day of the flight. Flight ground tracks are presented along with sample aerial photographs of the wave conditions showing approximate wavelength and direction. Sample wave energy spectra are presented both from the laser profilometer onboard the aircraft, and from the Corps of Engineers Research Center (CERC) shore gauge at Nags Head, North Carolina.

  19. Changing statistics of storms in the North Atlantic?

    International Nuclear Information System (INIS)

    Storch, H. von; Guddal, J.; Iden, K.A.; Jonsson, T.; Perlwitz, J.; Reistad, M.; Ronde, J. de; Schmidt, H.; Zorita, E.

    1993-01-01

    Problems in the present discussion about increasing storminess in the North Atlantic area are discusesd. Observational data so far available do not indicate a change in the storm statistics. Output from climate models points to an itensified storm track in the North Atlantic, but because of the limited skill of present-day climate models in simulating high-frequency variability and regional details any such 'forecast' has to be considered with caution. A downscaling procedure which relates large-scale time-mean aspects of the state of the atmosphere and ocean to the local statistics of storms is proposed to reconstruct past variations of high-frequency variability in the atmosphere (storminess) and in the sea state (wave statistics). First results are presented. (orig.)

  20. Magnetospheric storm dynamics in terms of energy output rate

    International Nuclear Information System (INIS)

    Prigancova, A.; Feldstein, Ya.I.

    1992-01-01

    Using hourly values of both the global magnetospheric disturbance characteristic DR, and AE index of auroral ionospheric currents during magnetic storm intervals, the energy output rate dynamics is evaluated for a magnetic storm main/recovery phase and a whole storm interval. The magnetospheric response to the solar wind energy input rate under varying interplanetary and magnetospheric conditions is considered from the temporal variability point of view. The peculiarities of the response are traced separately. As far as quantitative characteristics of energy output rate are concerned, the time dependence pattern of the ring current decay parameter is emphasized to be fairly important. It is pointed out that more insight into the plasma processes, especially at L = 3 - 5, is needed for adequate evidence of the dependence. (Author)

  1. Using forecast information for storm ride-through control

    DEFF Research Database (Denmark)

    Barahona Garzón, Braulio; Trombe, Pierre-Julien; Vincent, Claire Louise

    2013-01-01

    Using probabilistic forecast information in control algorithms can improve the performance of wind farms during periods of extreme winds. This work presents a wind farm supervisor control concept that uses probabilistic forecast information to ride-through a storm with softer ramps of power. Wind...... speed forecasts are generated with a statistical approach (i.e. time series models). The supervisor control is based on a set of logical rules that consider point forecasts and predictive densities to ramp-down the power of the wind farm before the storm hits. The potential of this supervisor control...

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

    Directory of Open Access Journals (Sweden)

    L. R. Cander

    2005-06-01

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

  3. A New 50 MHz Phased-Array Radar on Pohnpei: A Fresh Perspective on Equatorial Plasma Bubbles

    Science.gov (United States)

    Tsunoda, R. T.

    2014-12-01

    A new, phased-array antenna-steering capability has recently been added to an existing 50-MHz radar on Pohnpei, Federated States of Micronesia, in the central Pacific region. This radar, which we refer to as PAR-50, is capable of scanning in the vertical east-west plane, ±60° about the zenith. The alignment in the magnetic east-west direction allows detection of radar backscatter from small-scale irregularities that develop in the equatorial ionosphere, including those associated with equatorial plasma bubbles (EPBs). The coverage, about ±800 km in zonal distance, at an altitude of 500 km, is essentially identical to that provided by ALTAIR, a fully-steerable incoherent-scatter radar, which has been used in a number of studies of EPBs. Unlike ALTAIR, which has only been operated for several hours on a handful of selected nights, the PAR-50 has already been operated continuously, while performing repeated scans, since April 2014. In this presentation, we describe the PAR-50, then, compare it to ALTAIR and the Equatorial Atmospheric Radar (EAR); the latter is the only other phased-array system in use for equatorial studies. We then assess what we have learned about EPBs from backscatter radar measurements, and discuss how the PAR-50 can provide a fresh perspective to our understanding. Clearly, the ability to sort out the space-time ambiguities in EPB development from sequences of spatial maps of EPBs is crucial to our understanding of how EPBs develop.

  4. Shelter From the Storm

    Directory of Open Access Journals (Sweden)

    Leah Hamilton

    2015-02-01

    Full Text Available A growing body of literature suggests that asset limits in public assistance are associated with low savings rates among low-income families. Several states have begun eliminating or significantly increasing asset limits in an attempt to address potential disincentives. The primary concern for other states, however, appears to be the possibility that caseloads would increase to unsustainable levels, especially in times of economic recession. Five states that eliminated or increased asset limits during the Great Recession were analyzed for changes in caseload size after the rule change. Results suggest that there is no significant relationship between asset limits and caseload size.

  5. Studying Peculiarities of Ionospheric Response to the 2015 March 17-19 Geomagnetic Storm in East Asia: Observations and Simulation

    Science.gov (United States)

    Romanova, Elena; Zherebtsov, Gelii; Polekh, Nelya; Wang, Xiao; Wang, Guojun; Zolotukhina, Nina; Shi, Jiankui

    2016-07-01

    We report results of the research into effects of the strong geomagnetic storm in the ionosphere of high, middle, and low latitudes on March 17-19, 2015. The research relies on measurements made at the network of ionospheric stations located near the 120°E meridian. The analysis of experimental data has revealed that at the beginning of the main storm phase the equatorial wall of the main ionospheric trough (MIT) shifted towards geographic latitudes 58-60°N, which caused negative disturbances in subauroral latitudes and positive disturbances in middle latitudes. Further displacement of the MIT equatorial wall towards a geographic latitude of 52° N led to a decrease in the F2-layer critical frequency (foF2) up to 2 MHz in middle latitudes during evening and night hours, and to the appearance of sporadic layers in these latitudes due to energetic particle precipitation. Such phenomena are largely specific to the subauroral ionosphere. During the recovery storm phase on March 18, 2015 during daylight hours, negative disturbances were recorded at all the stations. Since prolonged negative disturbances are usually associated with a reduction in the ratio of concentrations of atomic oxygen and molecular nitrogen [O]/[N2] which is transported by disturbed thermospheric wind from auroral latitudes to middle and low ones, we analyzed measurements of [O]/[N2], made by GUVI (Global Ultraviolet Imager, http://guvi.jhuapl.edu/site/gallery/guvi-galleryl3on2.shtml), during this storm. The storm appeared to be characterized by very low values of [O]/[N2] which were recorded in the longitude sector 60 - 150°E up to 15°N on March 18. The discovered peculiarities of the ionospheric response to the storm were interpreted using a theoretical model of ionosphere-plasmosphere coupling developed at ISTP SB RAS. The simulation showed that the displacement of MIT equatorial wall resulted in foF2 variations similar to those observed during the main storm phase in subauroral and middle

  6. Ocean dynamics, not dust, have controlled equatorial Pacific productivity over the past 500,000 years

    OpenAIRE

    Winckler, Gisela; Anderson, Robert F.; Jaccard, Samuel L.; Marcantonio, Franco

    2016-01-01

    Biological productivity in the equatorial Pacific is relatively high compared with other low latitude regimes especially east of the dateline where divergence driven by the trade winds brings nutrient rich waters of the Equatorial Undercurrent to the surface. The equatorial Pacific is one of the three principal high nutrient low chlorophyll ocean regimes where biological utilization of nitrate and phosphate is limited in part by the availability of iron. Throughout most of the equatorial Paci...

  7. nuSTORM Costing document

    Energy Technology Data Exchange (ETDEWEB)

    Bross, Alan D. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2013-10-01

    Detailed costing of the nuSTORM conventional facilities has been done by the Fermilab Facilities Engineering Services Section (FESS) and is reported on in the nuSTORM Project Definition Report (PDR) 6-13-1. Estimates for outfitting the primary proton beam line, the target station, the pion capture/transport line and decay ring are based on either experience from existing Fermilab infrastructure (NuMI) or is based on the detailed costing exercises for DOE CD-1 approval for future experiments (mu2e and LBNE). The detector costing utilized the Euronu costing for the Neutrino Factory Magnetized Iron Neutrino Detector (MIND), extrapolations from MINOS as-built costs and from recent vendor quotes. Costs included all manpower and are fully burdened (FY2013 dollars). The costs are not escalated, however, beyond the 5-year project timeline, since a project start for nuSTORM is unknown. Escalation can be estimated from various models (see Figure 1). LBNE has used the Jacob’s model to determine their cost escalation.

  8. Iron sources and pathways into the Pacific Equatorial Undercurrent

    NARCIS (Netherlands)

    Qin, Xuerong; Menviel, Laurie; Sen Gupta, Alex; van Sebille, Erik

    2016-01-01

    Using a novel observationally constrained Lagrangian iron model forced by outputs from an eddy-resolving biogeochemical ocean model, we examine the sensitivity of the Equatorial Undercurrent (EUC) iron distribution to EUC source region iron concentrations. We find that elevated iron concentrations

  9. Climate regulation of fire emissions and deforestation in equatorial Asia

    NARCIS (Netherlands)

    van der Werf, G. R.; Dempewolf, J.; Trigg, S. N.; Randerson, J. T.; Kasibhatla, P. S.; Giglio, L.; Murdiyarso, D.; Peters, W.; Morton, D. C.; Collatz, G. J.; Dolman, A. J.; Defries, R. S.

    2008-01-01

    Drainage of peatlands and deforestation have led to large-scale fires in equatorial Asia, affecting regional air quality and global concentrations of greenhouse gases. Here we used several sources of satellite data with biogeochemical and atmospheric modeling to better understand and constrain fire

  10. Backscatter measurements of 11-cm equatorial spread-F irregularities

    International Nuclear Information System (INIS)

    Tsunoda, R.T.

    1980-01-01

    In the equatorial F-region ionosphere, a turbulent cascade process has been found to exist that extends from irregularity spatial wavelengths longer than tens of kilometers down to wavelengths as short as 36 cm. To investigate the small-scale regime of wavelengths less than 36 cm, an equatorial radar experiment was conducted using a frequency of 1320 MHz that corresponds to an irregularity wavelength of 11 cm. The first observations of radar backscatter from 11-cm field-aligned irregularities (FAI) are described. These measurements extend the spatial wavelength regime of F-region FAI to lengths that approach both electron gyroradius and the Debye length. Agreement of these results with the theory of high-frequency drift waves suggests that these observations may be unique to the equatorial ionosphere. That is, the requirement of low electron densities for which the theroy calls may preclude the existence of 11-cm FAI elsewhere in the F-region ionosphere, except in equatorial plasma bubbles

  11. Characterisation of tectonic lineaments in the Central Equatorial ...

    African Journals Online (AJOL)

    Characterisation of tectonic lineaments in the Central Equatorial Atlantic region of Africa using Bouguer anomaly gravity data. ... Ife Journal of Science ... 3-D standard Euler deconvolution analysis was carried out on Bouguer anomaly gravity data for configuration definition and approximate depth estimate of tectonic ...

  12. Planktonic foraminifera from core tops of western equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.; Guptha, M.V.S.

    distributional pattern showing upward trend in its abundance from 38 per cent at 21 degrees S latitude to 0.8 per cent at 6 degrees N latitude. Sub-tropical fauna is sparsely distributed in the Equatorial Indian Ocean. Based on these studies it is interpreted...

  13. Swashed away? Storm impacts on sandy beach macrofaunal communities

    Science.gov (United States)

    Harris, Linda; Nel, Ronel; Smale, Malcolm; Schoeman, David

    2011-09-01

    Storms can have a large impact on sandy shores, with powerful waves eroding large volumes of sand off the beach. Resulting damage to the physical environment has been well-studied but the ecological implications of these natural phenomena are less known. Since climate change predictions suggest an increase in storminess in the near future, understanding these ecological implications is vital if sandy shores are to be proactively managed for resilience. Here, we report on an opportunistic experiment that tests the a priori expectation that storms impact beach macrofaunal communities by modifying natural patterns of beach morphodynamics. Two sites at Sardinia Bay, South Africa, were sampled for macrofauna and physical descriptors following standard sampling methods. This sampling took place five times at three- to four-month intervals between April 2008 and August 2009. The second and last sampling events were undertaken after unusually large storms, the first of which was sufficiently large to transform one site from a sandy beach into a mixed shore for the first time in living memory. A range of univariate (linear mixed-effects models) and multivariate (e.g. non-metric multidimensional scaling, PERMANOVA) methods were employed to describe trends in the time series, and to explore the likelihood of possible explanatory mechanisms. Macrofaunal communities at the dune-backed beach (Site 2) withstood the effects of the first storm but were altered significantly by the second storm. In contrast, macrofauna communities at Site 1, where the supralittoral had been anthropogenically modified so that exchange of sediments with the beach was limited, were strongly affected by the first storm and showed little recovery over the study period. In line with predictions from ecological theory, beach morphodynamics was found to be a strong driver of temporal patterns in the macrofaunal community structure, with the storm events also identified as a significant factor, likely

  14. Coral settlement on a highly disturbed equatorial reef system.

    Science.gov (United States)

    Bauman, Andrew G; Guest, James R; Dunshea, Glenn; Low, Jeffery; Todd, Peter A; Steinberg, Peter D

    2015-01-01

    Processes occurring early in the life stages of corals can greatly influence the demography of coral populations, and successful settlement of coral larvae that leads to recruitment is a critical life history stage for coral reef ecosystems. Although corals in Singapore persist in one the world's most anthropogenically impacted reef systems, our understanding of the role of coral settlement in the persistence of coral communities in Singapore remains limited. Spatial and temporal patterns of coral settlement were examined at 7 sites in the southern islands of Singapore, using settlement tiles deployed and collected every 3 months from 2011 to 2013. Settlement occurred year round, but varied significantly across time and space. Annual coral settlement was low (~54.72 spat m(-2) yr(-1)) relative to other equatorial regions, but there was evidence of temporal variation in settlement rates. Peak settlement occurred between March-May and September-November, coinciding with annual coral spawning periods (March-April and October), while the lowest settlement occurred from December-February during the northeast monsoon. A period of high settlement was also observed between June and August in the first year (2011/12), possibly due to some species spawning outside predicted spawning periods, larvae settling from other locations or extended larval settlement competency periods. Settlement rates varied significantly among sites, but spatial variation was relatively consistent between years, suggesting the strong effects of local coral assemblages or environmental conditions. Pocilloporidae were the most abundant coral spat (83.6%), while Poritidae comprised only 6% of the spat, and Acroporidae coral spat. These results indicate that current settlement patterns are reinforcing the local adult assemblage structure ('others'; i.e. sediment-tolerant coral taxa) in Singapore, but that the replenishment capacity of Singapore's reefs appears relatively constrained, which could lead

  15. Magnetospheric conditions near the equatorial footpoints of proton isotropy boundaries

    Directory of Open Access Journals (Sweden)

    V. A. Sergeev

    2015-12-01

    Full Text Available Data from a cluster of three THEMIS (Time History of Events and Macroscale Interactions during Substorms spacecraft during February–March 2009 frequently provide an opportunity to construct local data-adaptive magnetospheric models, which are suitable for the accurate mapping along the magnetic field lines at distances of 6–9 Re in the nightside magnetosphere. This allows us to map the isotropy boundaries (IBs of 30 and 80 keV protons observed by low-altitude NOAA POES (Polar Orbiting Environmental Satellites to the equatorial magnetosphere (to find the projected isotropy boundary, PIB and study the magnetospheric conditions, particularly to evaluate the ratio KIB (Rc/rc; the magnetic field curvature radius to the particle gyroradius in the neutral sheet at that point. Special care is taken to control the factors which influence the accuracy of the adaptive models and mapping. Data indicate that better accuracy of an adaptive model is achieved when the PIB distance from the closest spacecraft is as small as 1–2 Re. For this group of most accurate predictions, the spread of KIB values is still large (from 4 to 32, with the median value KIB ~13 being larger than the critical value Kcr ~ 8 expected at the inner boundary of nonadiabatic angular scattering in the current sheet. It appears that two different mechanisms may contribute to form the isotropy boundary. The group with K ~ [4,12] is most likely formed by current sheet scattering, whereas the group having KIB ~ [12,32] could be formed by the resonant scattering of low-energy protons by the electromagnetic ion-cyclotron (EMIC waves. The energy dependence of the upper K limit and close proximity of the latter event to the plasmapause locations support this conclusion. We also discuss other reasons why the K ~ 8 criterion for isotropization may fail to work, as well as a possible relationship between the two scattering mechanisms.

  16. Network Intrusion Detection System using Apache Storm

    Directory of Open Access Journals (Sweden)

    Muhammad Asif Manzoor

    2017-06-01

    Full Text Available Network security implements various strategies for the identification and prevention of security breaches. Network intrusion detection is a critical component of network management for security, quality of service and other purposes. These systems allow early detection of network intrusion and malicious activities; so that the Network Security infrastructure can react to mitigate these threats. Various systems are proposed to enhance the network security. We are proposing to use anomaly based network intrusion detection system in this work. Anomaly based intrusion detection system can identify the new network threats. We also propose to use Real-time Big Data Stream Processing Framework, Apache Storm, for the implementation of network intrusion detection system. Apache Storm can help to manage the network traffic which is generated at enormous speed and size and the network traffic speed and size is constantly increasing. We have used Support Vector Machine in this work. We use Knowledge Discovery and Data Mining 1999 (KDD’99 dataset to test and evaluate our proposed solution.

  17. Solar Wind Charge Exchange During Geomagnetic Storms

    Science.gov (United States)

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

    2012-01-01

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

  18. Lagrangian mixed layer modeling of the western equatorial Pacific

    Science.gov (United States)

    Shinoda, Toshiaki; Lukas, Roger

    1995-01-01

    Processes that control the upper ocean thermohaline structure in the western equatorial Pacific are examined using a Lagrangian mixed layer model. The one-dimensional bulk mixed layer model of Garwood (1977) is integrated along the trajectories derived from a nonlinear 1 1/2 layer reduced gravity model forced with actual wind fields. The Global Precipitation Climatology Project (GPCP) data are used to estimate surface freshwater fluxes for the mixed layer model. The wind stress data which forced the 1 1/2 layer model are used for the mixed layer model. The model was run for the period 1987-1988. This simple model is able to simulate the isothermal layer below the mixed layer in the western Pacific warm pool and its variation. The subduction mechanism hypothesized by Lukas and Lindstrom (1991) is evident in the model results. During periods of strong South Equatorial Current, the warm and salty mixed layer waters in the central Pacific are subducted below the fresh shallow mixed layer in the western Pacific. However, this subduction mechanism is not evident when upwelling Rossby waves reach the western equatorial Pacific or when a prominent deepening of the mixed layer occurs in the western equatorial Pacific or when a prominent deepening of the mixed layer occurs in the western equatorial Pacific due to episodes of strong wind and light precipitation associated with the El Nino-Southern Oscillation. Comparison of the results between the Lagrangian mixed layer model and a locally forced Eulerian mixed layer model indicated that horizontal advection of salty waters from the central Pacific strongly affects the upper ocean salinity variation in the western Pacific, and that this advection is necessary to maintain the upper ocean thermohaline structure in this region.

  19. Interaction of ice storms and management practices on current carbon sequestration in forests with potential mitigation under future CO2 atmosphere

    Science.gov (United States)

    Heather R. McCarthy; Ram Oren; Hyun-Seok Kim; Kurt H. Johnsen; Chris Maier; Seth G. Pritchard; Michael A. Davis

    2006-01-01

    Ice storms are disturbance events with potential impacts on carbon sequestration. Common forest management practices, such as fertilization and thinning, can change wood and stand properties and thus may change vulnerability to ice storm damage. At the same time, increasing atmospheric CO2 levels may also influence ice storm vulnerability. Here...

  20. Ocean Color and the Equatorial Annual Cycle in the Pacific

    Science.gov (United States)

    Hammann, A. C.; Gnanadesikan, A.

    2012-12-01

    The presence of chlorophyll, colored dissolved organic matter (CDOM) and other scatterers in ocean surface waters affect the flux divergence of solar radiation and thus the vertical distribution of radiant heating of the ocean. While this may directly alter the local mixed-layer depth and temperature (Martin 1985; Strutton & Chavez 2004), non-local changes are propagated through advection (Manizza et al. 2005; Murtugudde et al. 2002; Nakamoto et al. 2001; Sweeny et al. 2005). In and coupled feedbacks (Lengaigne et al. 2007; Marzeion & Timmermann 2005). Anderson et al. (2007), Anderson et al. (2009) and Gnanadesikan & Anderson (2009) have performed a series of experiments with a fully coupled climate model which parameterizes the e-folding depth of solar irradiance in terms of surface chlorophyll-a concentration. The results have so far been discussed with respect to the climatic mean state and ENSO variability in the tropical Pacific. We extend the discussion here to the Pacific equatorial annual cycle. The focus of the coupled experiments has been the sensitivity of the coupled system to regional differences in chlorophyll concentration. While runs have been completed with realistic SeaWiFS-derived monthly composite chlorophyll ('green') and with a globally chlorophyll-free ocean ('blue'), the concentrations in two additional runs have been selectively set to zero in specific regions: the oligotrophic subtropical gyres ('gyre') in one case and the mesotrophic gyre margins ('margin') in the other. The annual cycle of ocean temperatures exhibits distinctly reduced amplitudes in the 'blue' and 'margin' experiments, and a slight reduction in 'gyre' (while ENSO variability almost vanishes in 'blue' and 'gyre', but amplifies in 'margin' - thus the frequently quoted inverse correlation between ENSO and annual amplitudes holds only for the 'green' / 'margin' comparison). It is well-known that on annual time scales, the anomalous divergence of surface currents and vertical

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

    Czech Academy of Sciences Publication Activity Database

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

    2016-01-01

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

  2. The method of characteristic for nonlinear generalized Rayleigh-Taylor instability associated with equatorial spread F: An analytical approach

    International Nuclear Information System (INIS)

    Sekar, R.; Kherani, E.A.

    2002-01-01

    An analytical method is presented for the nonlinear generalized Rayleigh-Taylor instability occurring over the night-time equatorial F region of the terrestrial ionosphere. The time and spatial domain characteristic methods are adopted to describe the evolutions of plasma density and particle flux, respectively. The analysis efficiently describes the known nonlinear features of instability as suggested by many numerical simulations. The existence of shock or steepened structures and their dynamics are discussed by studying the evolution of the characteristics

  3. Mapping and Visualization of Storm-Surge Dynamics for Hurricane Katrina and Hurricane Rita

    Science.gov (United States)

    Gesch, Dean B.

    2009-01-01

    The damages caused by the storm surges from Hurricane Katrina and Hurricane Rita were significant and occurred over broad areas. Storm-surge maps are among the most useful geospatial datasets for hurricane recovery, impact assessments, and mitigation planning for future storms. Surveyed high-water marks were used to generate a maximum storm-surge surface for Hurricane Katrina extending from eastern Louisiana to Mobile Bay, Alabama. The interpolated surface was intersected with high-resolution lidar elevation data covering the study area to produce a highly detailed digital storm-surge inundation map. The storm-surge dataset and related data are available for display and query in a Web-based viewer application. A unique water-level dataset from a network of portable pressure sensors deployed in the days just prior to Hurricane Rita's landfall captured the hurricane's storm surge. The recorded sensor data provided water-level measurements with a very high temporal resolution at surveyed point locations. The resulting dataset was used to generate a time series of storm-surge surfaces that documents the surge dynamics in a new, spatially explicit way. The temporal information contained in the multiple storm-surge surfaces can be visualized in a number of ways to portray how the surge interacted with and was affected by land surface features. Spatially explicit storm-surge products can be useful for a variety of hurricane impact assessments, especially studies of wetland and land changes where knowledge of the extent and magnitude of storm-surge flooding is critical.

  4. Dependence on zenith angle of the strength of 3-meter equatorial electrojet irregularities

    International Nuclear Information System (INIS)

    Ierkic, H.M.; Fejer, B.G.; Farley, D.T.

    1980-01-01

    Radar measurements in Peru were used to deduce the zenith angle dependence of the scattering cross section of plasma irregularities generated by instabilities in the equatorial electrojet. The irregularities probed by the 50 MHz Jicamarca radar had a wavelength of 3m. The cross section for the type 2 irregularities was isotopic in the plane perpendicular to the magnetic field, while the cross section for the stronger type 1 irregularities varied with zenith angle at a rate of approximately 0.3 dB/degree; the horizontally traveling waves were more than 100 times stronger than those traveling vertically

  5. Blow-up of solutions to the rotation b-family system modeling equatorial water waves

    Directory of Open Access Journals (Sweden)

    Min Zhu

    2018-03-01

    Full Text Available We consider the blow-up mechanism to the periodic generalized rotation b-family system (R-b-family system. This model can be derived from the f-plane governing equations for the geographical water waves with a constant underlying current in the equatorial water waves with effect of the Coriolis force. When b=2, it is a rotation two-component Camassa-Holm (R2CH system. We consider the periodic R2CH system when linear dispersion is absent (which model is called r2CH system and derive two finite-time blow-up results.

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

    Science.gov (United States)

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

    2014-12-01

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

  7. Magnetic storm effects on the tropical ultraviolet airglow

    International Nuclear Information System (INIS)

    Gerard, J.; Anderson, D.N.; Matsushita, S.

    1977-01-01

    The intensity and latitudinal distribution of the O I 1304- and 1356-A nighttime emissions associated with the equatorial anomaly have been observed by the ultraviolet spectrometer on board the Ogo 4 satellite. Conspicuous effects, apparently related to magnetic activity, have been noticed during the geomagnetic storm of October 29 to November 4, 1968. These effects include (1) large latitudinal variations of the 1304/1356-A intensity ratio, (2) large interhemispheric asymmetries in the 1356-A intensity, and (3) a pronounced longitude dependence in the airglow intensity during the recovery phase. The results of model calculations allowing for changes in the vertical E x B drift velocity, the meridional and zonal wind velocity, and neutral composition are discussed. The variations of the 1304/1356-A ratio can be accounted for by changes in the altitude of the F layer due to neutral wind and E x B drift. Zonal wind speeds approaching 300 m/s explain the interhemispheric asymmetries observed in the Pacific sector, and both drift velocity and composition changes can explain the longitudinal differences observed during the recovery phase. In addition, it is found that the ratio 1304/1356 A=6 maps out H/sub max/(F 2 ) extremely well, independent of which E x B drift or neutral wind model is used

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

    Science.gov (United States)

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

    2017-11-01

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

  9. Extreme Geomagnetic Storms – 1868–2010

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  10. Evidence of late Palaeocene-early Eocene equatorial rain forest refugia in southern Western Ghats, India.

    Science.gov (United States)

    Prasad, V; Farooqui, A; Tripathi, S K M; Garg, R; Thakur, B

    2009-11-01

    Equatorial rain forests that maintain a balance between speciation and extinction are hot-spots for studies of biodiversity. Western Ghats in southern India have gained attention due to high tropical biodiversity and endemism in their southern most area. We attempted to track the affinities of the pollen fl ora of the endemic plants of Western Ghat area within the fossil palynoflora of late Palaeocene-early Eocene (approximately 55-50 Ma) sedimentary deposits of western and northeastern Indian region. The study shows striking similarity of extant pollen with twenty eight most common fossil pollen taxa of the early Palaeogene. Widespread occurrences of coal and lignite deposits during early Palaeogene provide evidence of existence of well diversified rain forest community and swampy vegetation in the coastal low lying areas all along the western and northeastern margins of the Indian subcontinent. Prevalence of excessive humid climate during this period has been seen as a result of equatorial positioning of Indian subcontinent, superimposed by a long term global warming phase (PETM and EECO) during the early Palaeogene. The study presents clear evidence that highly diversifi ed equatorial rain forest vegetation once widespread in the Indian subcontinent during early Palaeogene times, are now restricted in a small area as a refugia in the southernmost part of the Western Ghat area. High precipitation and shorter periods of dry months seem to have provided suitable environment to sustain lineages of ancient tropical vegetation in this area of Western Ghats in spite of dramatic climatic changes subsequent to the post India-Asia collision and during the Quaternary and Recent times.

  11. Strong convective storm nowcasting using a hybrid approach of convolutional neural network and hidden Markov model

    Science.gov (United States)

    Zhang, Wei; Jiang, Ling; Han, Lei

    2018-04-01

    Convective storm nowcasting refers to the prediction of the convective weather initiation, development, and decay in a very short term (typically 0 2 h) .Despite marked progress over the past years, severe convective storm nowcasting still remains a challenge. With the boom of machine learning, it has been well applied in various fields, especially convolutional neural network (CNN). In this paper, we build a servere convective weather nowcasting system based on CNN and hidden Markov model (HMM) using reanalysis meteorological data. The goal of convective storm nowcasting is to predict if there is a convective storm in 30min. In this paper, we compress the VDRAS reanalysis data to low-dimensional data by CNN as the observation vector of HMM, then obtain the development trend of strong convective weather in the form of time series. It shows that, our method can extract robust features without any artificial selection of features, and can capture the development trend of strong convective storm.

  12. Responses of Hail and Storm Days to Climate Change in the Tibetan Plateau

    Science.gov (United States)

    Zou, Tian; Zhang, Qinghong; Li, Wenhong; Li, Jihong

    2018-05-01

    There is increasing concern that local severe storm occurrence may be changing as a result of climate change. The Tibetan Plateau (TP), one of the world's most sensitive areas to climate change, became significantly warmer during recent decades. Since 1960 (1980), storm (hail) days have been decreasing by 6.2%/decade (18.3%/decade) in the region. However, what caused the frequency changes of storm and hail in the TP is largely unknown. Based on 53-year continuous weather records at 48 TP stations and reanalysis data, we show here for the first time that the consistent decline of storm days is strongly related to a drier midtroposphere since 1960. Further analysis demonstrated that fewer hail days are driven by an elevation of the melting level (thermodynamically) and a weaker wind shear (dynamically) in a warming climate. These results imply that less storm and hail may occur over TP when climate warms.

  13. Alternative salvage technique during postcardiotomy electrical storm.

    Science.gov (United States)

    Ryu, Y G; Baek, M J; Kim, H J

    2010-08-01

    Cardiac electrical storm is generally treated with antiarrhythmic drugs, electrical cardioversion, or catheter ablation. However, these conservative treatment modalities are considered neither curative nor preventive with regard to recurrent arrhythmias in postoperative electrical storm after open heart surgery. We present a case of surgical ventricular assist device placement for postcardiotomy electrical storm in a 38-year-old patient. Copyright (c) Georg Thieme Verlag KG Stuttgart-New York.

  14. New storm water regulations impact industry

    International Nuclear Information System (INIS)

    Gemar, C.

    1991-01-01

    In November 1990, new Environmental Protection Agency (EPA) regulations aimed at governing the discharge of storm water from industrial facilities became effective. Because some industrial runoff contains toxics and other pollutants, the EPA considers storm water a major source of water contamination. The new regulations will have a profound impact on the National Pollutant Discharge Elimination System (NPDES) permit requirements for industry. This paper summarizes the new storm water regulations, focusing on the requirements for industrial facilities. It also presents suggestions for compliance

  15. Coastal Storm Hazards from Virginia to Maine

    Science.gov (United States)

    2015-11-01

    secondary terms • integration of joint probability of storm responses, including extratropical events. A diagram summarizing the JPM methodology is... Extratropical Cyclones. The GPD- based approach defined above was used to compute the final storm response statistics for XCs. ERDC/CHL TR-15-5 39...from the numerical modeling of all storms , tropical and extratropical . As discussed in Section 2.1.2, JPM methodology generally consists of the

  16. Validation of Storm Water Management Model Storm Control Measures Modules

    Science.gov (United States)

    Simon, M. A.; Platz, M. C.

    2017-12-01

    EPA's Storm Water Management Model (SWMM) is a computational code heavily relied upon by industry for the simulation of wastewater and stormwater infrastructure performance. Many municipalities are relying on SWMM results to design multi-billion-dollar, multi-decade infrastructure upgrades. Since the 1970's, EPA and others have developed five major releases, the most recent ones containing storm control measures modules for green infrastructure. The main objective of this study was to quantify the accuracy with which SWMM v5.1.10 simulates the hydrologic activity of previously monitored low impact developments. Model performance was evaluated with a mathematical comparison of outflow hydrographs and total outflow volumes, using empirical data and a multi-event, multi-objective calibration method. The calibration methodology utilized PEST++ Version 3, a parameter estimation tool, which aided in the selection of unmeasured hydrologic parameters. From the validation study and sensitivity analysis, several model improvements were identified to advance SWMM LID Module performance for permeable pavements, infiltration units and green roofs, and these were performed and reported herein. Overall, it was determined that SWMM can successfully simulate low impact development controls given accurate model confirmation, parameter measurement, and model calibration.

  17. Ice storm 1998 : lessons learned

    Energy Technology Data Exchange (ETDEWEB)

    McCready, J. [Eastern Ontario Model Forest, Kemptville, ON (Canada)

    2006-07-01

    This paper presented details of a partnership formed in response to the ice storm of 1998, which caused extensive damage to trees in woodlots and urban settings in eastern Ontario and western Quebec. The aim of the Ice Storm Forest Recovery Group was to assist in the recovery of eastern forests, collect information on the extent of the damage to trees as well as contribute to the development of assistance programs for woodlot owners and municipalities. In response to the group's request, an initial aerial survey was conducted by the Ontario Ministry of Natural Resources to map the extent of the damage in eastern Ontario, which was followed by a more scientific survey with the Canadian Forest Service through the development of a flying grid pattern to observe the status of trees, followed by extensive ground checks. Damage was variable, depending on tree species, stand age and composition, management practices, wind direction, topography and ice deposition patterns. A summary of the severity of damage indicated that conifers suffered less than hardwoods. Consultants were hired to prepare news releases and extension notes to the public in order to provide information for the caring of trees. Various educational workshops were held which attracted large numbers of landowners and homeowners. A literature review was undertaken to produce a summary of current published knowledge covering the effects of storms and ice damage to trees and forests. Science efforts were published in a series of papers, and financial assistance programs were then organized by governmental agencies. It was concluded that cooperation between all agencies, groups and levels of government is needed in order to coordinate effective emergency strategies. 7 refs., 1 tab., 1 fig.

  18. Synoptic Storms in the North Atlantic in the Atmospheric Reanalysis and Scatterometer-Based Wind Products