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Stare Velocities: the Importance of Off-orthogonality and Ion Moti...

By: S. Nozawa; P. Janhunen; A. Koustov; R. Pellinen; D. Danskin; M. Uspensky

Description: Finnish Meteorological Institute, Geophisycal Research, P.O. Box 503, FIN-00101, Helsinki, Finland. A 3.5-h morning event of joint EISCAT/STARE observations is considered and the differences between the observed STARE velocities and the electron drift components (EISCAT) are studied. We find that the STARE-Finland radar velocity was larger than the EISCAT convec-tion component for a prolonged period of time. In addition, a moderate 5–20° offset bet...

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Identification of Magnetosheath Mirror Modes in Equator-s Magnetic...

By: M. W. Dunlop; E. Georgescu; A. Balogh; P. Cargill; G. Haerendel; W. Baumjohann; E. A. Lucek; G.-h. Fornacon

Description: The Blackett Laboratory, Imperial College, London SW7 2BZ, UK. Between December 1997 and March 1998 Equator-S made a number of excursions into the dawn-side magnetosheath, over a range of local times between 6:00 and 10:40 LT. Clear mirror-like structures, characterised by compressive fluctuations in |B| on occasion lasting for up to 5 h, were observed during a significant fraction of these orbits. During most of these passes the satellite appear...

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A Statistical Study of Diurnal, Seasonal and Solar Cycle Variation...

By: C. Foster; M. Lester; J. A. Davies

Description: Radio and Space Plasma Physics Group, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK. A statistical analysis of F-region and topside auroral ion upflow events is presented. The study is based on observations from EISCAT Common Programmes (CP) 1 and 2 made between 1984 and 1996, and Common Programme 7 observations taken between 1990 and 1995. The occurrence frequency of ion upflow events (IUEs) is exa...

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Observations of an Auroral Streamer in a Double Oval Configuration...

By: C. J. Owen; K. Kauristie; T. Takada; R. Nakamura; H. U. Frey; O. Amm; A. Aikio; R. Kuula

Description: Finnish Meteorological Institute, Arctic research unit, P.O. Box 503, 00101 Helsinki, Finland. During the late evening and night of 14 September 2004, the nightside auroral oval shows a distinct double oval configuration for several hours after a substorm onset at ~18:45 UT. This structure is observed both by the IMAGE satellite optical instruments focusing on the Southern Hemisphere, and by the MIRACLE ground-based instrument network in Scandinavia. At...

Amm, O. and Kauristie, K.: Ionospheric signatures of bursty bulk flows, Surv. Geophys., 23, 1–32, 2002.; Amm, O. and Viljanen, A.: Ionospheric disturbance magnetic field continuation from the ground to the ionosphere using spherical elementary current systems, Earth, Planets Space, 51, 431– , 1999.; Amm, O., Pajunpää, A., and Brandström, U.: Spatial distribution of conductances and currents associated with a north-south auroral form during a multiple-substorm period, Ann...

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Low Frequency Geomagnetic Field Fluctuations at Low Latitude Durin...

By: U. Villante; P. Francia

Description: Dipartimento di Fisica, Universita' dell'Aquila, L'Aquila, Italy. The passage of a higher pressure solar wind region at the Earth's orbit marked the onset of low latitude (L=1.6) fluctuations in the frequency range (0.8–5.5 mHz) for both the horizontal geomagnetic field components. Spectral peaks mostly occur at the same frequencies as the spectral enhancements which appeared in the long term analysis of experimental measurements from the same st...

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The Cusp: a Window for Particle Exchange Between the Radiation Bel...

By: T. A. Fritz; J.-b. Cao; Z. Y. Pu; X.-z. Zhou; Q.-g. Zong; Y.-q. Hao

Description: Institute of Space Physics and Applied Technology, Peking University, Beijing 100871, China. The study focuses on a single particle dynamics in the cusp region. The topology of the cusp region in terms of magnetic field iso-B contours has been studied using the Tsyganenko 96 model (T96) as an example, to show the importance of an off-equatorial minimum on particle trapping. We carry out test particle simulations to demonstrate the bounce and drift motio...

Antonova, A E. and Shabansky, V P.: Structure of the geomagnetic field at great distance from the Earth, Geomagn. Aeron., 8, 801–811, 1968.; Antonova, A E., Gubar, Y I., and Kropotkim, A P.: Energetic particle population in the high-latitude geomagnetosphere, Phys. Chem. Earth, 25, 47–50, 1999.; Cargill, P J., Lavraud, B., Owen, C J., Grison, B., Dunlop, M W., Cornilleau-Wehrlin, N., Escoubet, C P., Paschmann, G., Phan, T D., Rezeau, L., Bogdanova, Y., and Nykyri, K.: Cl...

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Analysis of the Effect of the Coastal Discontinuity on Near-surfac...

By: R. J. Barthelmie; S. C. Pryor

Description: Climate and Meteorology Program, Department of Geography, Indiana University, Bloomington, IN 47405, USA
Fax: +1 812 855 1661; e-mail: spryor@indiana.edu. Conditional sampling is used herein to examine the effect of fetch, stability, and surface roughness changes on wind speeds in the coastal zone. Using data from an offshore wind farm it is shown that at a distance of 1.2–1.7 km from the coast, up to a height of 20 m above the surface, differences ...

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Gravity Wave Penetration Into the Thermosphere: Sensitivity to Sol...

By: S. L. Vadas; D. C. Fritts

Description: NorthWest Research Associates, CoRA Division, 3380 Mitchell Lane, Boulder, CO 80301, USA. We previously considered various aspects of gravity wave penetration and effects at mesospheric and thermospheric altitudes, including propagation, viscous effects on wave structure, characteristics, and damping, local body forcing, responses to solar cycle temperature variations, and filtering by mean winds. Several of these efforts focused on gravity waves arising...

Bishop, R., Aponte, N., Earle, G. D., Sulzer, M., Larsen, M. F., and Peng, G.: Arecibo observations of ionospheric perturbations associated with the passage of tropical storm Odette, J. Geophys. Res., 111, A11320, doi:10.1029/2006JA011668, 2006.; Abdu, M., Kherani, E., Batista, I., et al.: Gravity wave influences on plasma instability growth rates based on observations during the Spread F Experiment (SpreadFEx), Ann. Geophys., in review, 2008. %angeo-2008-0028; Alexander...

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Drifter Observations of the Hebrides Slope Current and Nearby Circ...

By: S. A. Thorpe; M. Burrows

Description: Department of Oceanography, Southampton Oceanography Centre, European Way, Southampton, SO14 3ZH, UK. The mean flow at and around the Hebrides and Shetland Shelf slope is measured with ARGOS tracked drifters. Forty-two drifters drogued at 50 m were deployed in three circles over the Hebrides slope at 56.15°N in two releases, one on 5th December, 1995 and the second on 5-9th May, 1996. The circles span a distance of some 20 km from water depths of 200 m t...

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In Situ Observations of Meteor Smoke Particles (Msp) During the Ge...

By: J. Hedin; B. Strelnikov; G. Stober; S. Ernst; M. Rapp; M. Friedrich; J. M. C. Plane; U.-p. Hoppe

Description: Leibniz-Institute of Atmospheric Physics, Kühlungsborn, Germany. We present in situ observations of meteoric smoke particles (MSP) obtained during three sounding rocket flights in December 2010 in the frame of the final campaign of the Norwegian-German ECOMA project (ECOMA = Existence and Charge state Of meteoric smoke particles in the Middle Atmosphere). The flights were conducted before, at the maximum activity, and after the decline of the Geminids w...

Amyx, K., Sternovsky, Z., Knappmiller, S., Robertson, S., Hor{á}nyi, M., and Gumbel, J.: In-situ measurement of smoke particles in the wintertime polar mesosphere between 80 and 85 km altitude, J. Atmos. Sol. Terr. Phys., 70, 61–70, 2008.; Bardeen, C. G., Toon, O. B., Jensen, E. J., Marsh, D. R., and Harvey, V. L.: Numerical simulations of the three dimensional distribution of meteoric dust in the mesosphere and upper stratosphere, J. Geophys. Res., 113, D17202,

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Identification of the Sources of Inertia-gravity Waves in the Ande...

By: A. Spiga; V. Zeitlin; H. Teitelbaum

Description: Laboratoire de Météorologie Dynamique, École Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France. Four major sources of inertia-gravity waves are known in the Earth atmosphere: upper-tropospheric jet-streams, lower-tropospheric fronts, convection and topography. The Andes Cordillera region is an area where all of these major sources are potentially present. By combining ECMWF and NCEP-NCAR reanalysis, satellite and radiosoundings data and m...

Press,~W H., Flannery,~B P., Teukolsky,~S A., and Vetterling,~W T.:~Numerical Recipes in C: The Art of Scientific Computing, Cambridge University Press,~1992.; Fritts,~D C. and Nastrom,~G D.:~Sources of Mesoscale Variability of Gravity Waves. Part II: Frontal, Convective, and Jet Stream Excitation, J. Atmos. Sci., 49, 111–127,~1992.; Gossard,~E E. and Hooke,~W H.:~Waves in the atmosphere. Elsevier Scientific Publishing,~1975.; Alexander,~M J. and Pfister,~L.:~Gravity wav...

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A Case Study of a Radially Polarized Pc4 Event Observed by the Equ...

By: W. Baumjohann; C. Othmer; K. H. Fornacon; K. H. Glassmeier; H. U. Auster; R. Cramm; E. Georgescu

Description: Institut für Geophysik und Meteorologie, Technische Universität, Mendelssohnstr. 3, D-38106 Braunschweig, Germany. A 16 mHz Pc4 pulsation was recorded on March 17, 1998, in the prenoon sector of the Earth's magnetosphere by the Equator-S satellite. The event is strongly localized in radial direction at approximately L = 5 and exhibits properties of a field line resonance such as an ellipticity change as seen by applying the method of the analytica...

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Solar Flux Dependence of Coherence Scales in Scintillation Pattern...

By: K. Jeeva; A. Bhattacharyya; K. U. Nair; B. Engavale

Description: Indian Institute of Geomagnetism, Kalamboli Highway, Kalamboli - 410 218 New Panvel, India. The coherence scale length, defined as the 50% decorrelation scale length along the magnetic east-west direction, in the ground scintillation pattern obtained at a dip equatorial location, due to scattering of VHF radio waves by equatorial spread F (ESF) irregularities, is calculated, using amplitude scintillation data recorded by two spaced receivers. The averag...

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A Study of Tropical Tropopause Using Mst Radar : Volume 23, Issue ...

By: K. Satheesan; B. V. Krishna Murthy

Description: Department of Atmospheric Sciences, Cochin University of Science and Technology, Cochin, India. Using the MST radar data of vertical wind, the characteristics of the tropical tropopause, following four different definitions, depending on 1) temperature lapse rate, 2) cold point, 3) convective outflow and 4) potential temperature lapse rate minimum, are studied. From the vertical wind data of the radar, the altitude profiles of temperature and horizontal...

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Simultaneous Double Star and Cluster Ftes Observations on the Dawn...

By: P.-a. Lindqvist; A. Balogh; M. W. Dunlop; R. C. Fear; A. N. Fazakerley; H. Rème; A. Marchaudon; A. D. Lahiff; J.-m. Bosqued; C. J. Owen; C. Carr

Description: Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, RH5 6NT, UK. We present Cluster and Double Star-1 (TC-1) observations from a close magnetic conjunction on 8 May 2004. The five spacecraft were on the dawnside flank of the magnetosphere, with TC-1 located near the equatorial plane and Cluster at higher geographic latitudes in the Southern Hemisphere. TC-1, at its apogee, skimmed the magnetopause for almost 8h (betwee...

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Swmf Simulation of Field-aligned Currents for a Varying Northward ...

By: H. Lühr; A. J. Ridley; H. Wang

Description: Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI-48109, USA. This study concentrates on the FACs distribution for the varying northward and duskward interplanetary magnetic field (IMF) conditions when the dipole tilt is nonzero. A global MHD simulation (the Space Weather Modeling Framework, SWMF) has been used to perform this study. Hemispheric asymmetry of the time evolution of northward IMF Bz...

Mei, Y., Crooker, N U., and Siscoe, G L.: Cusp current modeling: A systematic approach, J. Geophys. Res., 99, 4027–4038, 1994.; Burke, W J., Kelley, M C., Sagalyn, R C., Smiddy, M., and Lai, S T.: Polar cap electric field structures with a northward interplanetary magnetic field, Geophys. Res. Lett., 6, 21–24, 1979.; Clauer, C R. and Friis-Christensen, E.: High-latitude dayside electric fields and currents during strong northward interplanetary magnetic field – Observati...

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Ion Drift Simulation of Sudden Appearance of Sub-kev Structured Io...

By: Y. Ebihara; I. Dandouras; H. Nilsson; M. Yamauchi

Description: Swedish Institute of Space Physics (IRF), Box 812, 98128 Kiruna, Sweden. Energy–latitude dispersed structured sub-keV ions in the inner magnetosphere often show significant development or intensification (by more than factor of 3) within 1–2 h near noon or afternoon where the azimuthal ion drift velocity at the sub-keV range is expected to be near zero. To examine whether such sudden appearances in the dayside can be explained by the drift motion of ion...

Angelopoulos, V., Temerin, M., Roth, I., Mozer, F. S., Weimer, D., and Hairston, M. R.: Testing global storm-time electric field models using particle spectra on multiple spacecraft, J. Geophys. Res., 107, doi:10.1029/2001JA900174, 2002.; Ebihara, Y., Yamauchi, M., Nilsson, H., Lundin, R., and Ejiri, M.: Wedge-like dispersion of sub-keV ions in the dayside magnetosphere: Particle simulation and Viking observation, J. Geo...

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Comment on Concerning the Generation of Geomagnetic Giant Pulsatio...

By: G. Chisham; I. R. Mann

Description: Department of Physics, University of York, York, UK. Not available.

Key words: Magnetospheric physics (energetic particles, trapped; MHD waves and instabilities) - Space plasma physics (wave-particle interactions)

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Plasma Convection Across the Polar Cap, Plasma Mantle and Cusp: Cl...

By: J. M. Quinn; G. Paschmann; S. E. Haaland; M. Förster; B. Klecker; H. Rème; R. B. Torbert; P. A. Puhl-quinn; H. Vaith; E. Georgescu; C. A. Kletzing

Description: Max-Planck-Institut für extraterrestrische Physik, 85748 Garching, Germany. In this paper we report measurements of the convection obtained with the Electron Drift Instrument (EDI) on Cluster. We use 20 passes that cross the between its dayside and nightside boundaries (or vice versa) at geocentric distances ranging from about 5 to about 13RE, and at interspacecraft separations (transverse to the ambient magnetic field) between a few k...

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Equatorial Electrojet as Part of the Global Circuit: a Case-study ...

By: J. Vassal; C. Amory-mazaudier; H. Lühr; J. M. Do; E. Houngninou; A. T. Kobea; E. Blanc; J. J. Curto

Description: U. F. R. SSMT / Laboratoire de Physique de l'Atmosphère, 22 B.P. 582 Abidjan 22, Côte d'Ivoire Tel: 225 44 49 82; Fax: 225 44 49 82/44 38 47; e-mail: kobeat@syfed.ci.refer.org. 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...

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