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Cluster Survey of the Mid-altitude Cusp: 1. Size, Location, and Dy...

By: C. P. Escoubet; B. Klecker; H. Rème; F. Pitout

Description: Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85741 Garching, Germany. We present a statistical study of four years of Cluster crossings of the mid-altitude cusp. In this first part of the study, we start by introducing the method we have used a) to define the cusp properties, b) to sort the interplanetary magnetic field (IMF) conditions or behaviors into classes, c) to determine the proper time delay between the solar wind monit...

Balogh, A., Carr, C. M., AcuÑa, M. H., Dunlop, M. W., Beek, T. J., Brown, P., Fornacon, K.-H., Georgescu, E., Glassmeier, K.-H., Harris, J., Musmann, G., Oddy, T., and Schwingenschuh, K.: The Cluster Magnetic Field Investigation: overview of in-flight performance and initial results, Ann. Geophys., 19, 1207–1217, 2001.; Bobra, M. G., Petrinec, S. M., Fuselier, S. A., Claflin, E. S., and Spence, H. E.: On the solar wind control of the cusp aurora during northward IMF, Geo...

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Motion of the Dayside Polar Cap Boundary During Substorm Cycles: I...

By: J. Moen; A. P. Van Eyken; I. W. McCrea; J. A. Davies; M. Lockwood; K. Oksavik

Description: Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK. Using data from the EISCAT (European Incoherent Scatter) VHF radar and DMSP (Defense Meteorological Satellite Program) spacecraft passes, we study the motion of the dayside open-closed field line boundary during two substorm cycles. The satellite data show that the motions of ion and electron temperature boundaries in EISCAT data, as reported by Moen et al. (2004), are not localised aro...

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On the Relationship Between Aspect Sensitivity, Wave Activity, And...

By: M. Zecha; P. Hoffmann; J.-s. Chen; J. Röttger

Description: Department of Electronic Engineering, Chienkuo Institute of Technology, Changhua 500, Taiwan. A mesosphere-summer-echo layer, observed by the OSWIN VHF radar (54.1°N, 11.8°E) with vertical and 7° oblique radar beams, was examined using the method of coherent radar imaging (CRI). We disclosed the echo events having multiple scattering centers (MSC) in the radar volume by means of the high angular resolution of the CRI technique and found that the MSC even...

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Evidence of Standing Waves During a Pi2 Pulsation Event Observed o...

By: L. G. Blomberg; P. R. Sutcliffe; A. B. Collier; A. R. W. Hughes

Description: School of Physics, University of KwaZulu-Natal, Durban, South Africa. Observations of Pi2 pulsations at middle and low latitudes have been explained in terms of cavity mode resonances, whereas transients associated with field-aligned currents appear to be responsible for the high latitude Pi2 signature.

Data from Cluster are used to study a Pi2 event observed at 18:09 UTC on 21 January 2003, when three of the satellites were within the plasmasphe...

Saito, T., Sakurai, T., and Koyama, Y.: Mechanism of association between Pi2 pulsation and magnetospheric substorm, J. Atmos. Terr. Phys., 38, 1265–1277, 1976.; Sakurai, T. and McPherron, R. L.: Satellite Observations of Pi 2 Activity at Synchronous Orbit, J. Geophys. Res., 88, 7015–7027, 1983.; Akasofu, S.-I.: Polar and Magnetospheric Substorms, vol. 11 of Astrophysics and Space Science Library\/, D. Reidel, Dordrecht, Holland, 1968.; Akasofu, S.-I. (Ed.): Dynamics of t...

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Cloudsat Observations of Cloud-type Distribution Over the Indian S...

By: K. K. Kumar; K. V. Subrahmanyam

Description: Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram, Kerala, India. The three-dimensional distribution of various cloud types over the Indian summer monsoon (ISM) region using five years (2006–2010) of CloudSat observations during June-July-August-September months is discussed for the first time. As the radiative properties, latent heat released and microphysical properties of clouds differ largely depending on the cloud type, it ...

Behrangi, A., Casey, S. P. F., and Lambrigtsen, B. H.: Three-dimensional distribution of cloud types over the USA and surrounding areas observed by CloudSat, Int. J. Remote Sens., 33, 4856–4870, 2012.; Chen, T., Rossow, W. B., and Zhang, Y.: Radiative effects of cloud-type variations, J. Climate, 13, 264–286, 2000.; Gadgil, S.: The Indian Monsoon and its variability, Annu. Rev. Earth Planet. Sci., 31, 429–467, 2003.; Grossman, R. and Garcia, O.: The distribution of deep ...

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Decameter Mid-latitude Sporadic-e Irregularities in Relation with ...

By: E. Lefur; Y. Le Roux; C. Haldoupis; J. Delloue; A. Bourdillon; J. Ménard

Description: Laboratoire Structures Rayonnautes, UPRES-4 CNRS 6095, Université de Rennes 1, Rennes, France. HF radar observations of mid-latitude spo- radic-E irregularities carried out with the Valensole radar in South France are compared with simultaneous ionosonde measurements underneath the irregularity zones. In a previous study of Valensole radar data, it has been shown that HF backscatter from the night-time mid-latitude E region is usually associated with l...

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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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Preconditions to Ground Based Gps Water Vapour Tomography : Volume...

By: A. Raabe; M. Bender

Description: Institut für Meteorologie, Universität Leipzig, Stephanstrasse 3, 04103 Leipzig, Germany. The GPS water vapour tomography is a new technique which provides spatially resolved water vapour distributions in the atmosphere under all weather conditions. This work investigates the information contained in a given set of GPS signals as a precondition to an optimal tomographic reconstruction. The spatial distribution of the geometric intersection points between...

Aoyama, Y., Shoji, Y., Mousa, A., Tsuda, T., and Nakamura, H.: Temperature and Water Vapor Profiles Derived from Downward-Looking GPS Occultation Data, J. Meteor. Soc. Japan, 82, 433–440, 2004.; Bastin, S., Champollion, C., Bock, O., Drobinski, P., and Masson, F.: On the use of GPS tomography to investigate water vapour variability during a Mistral/sea breeze event in southeastern France, Geophys. Res. Lett., 32, L05 808, doi:10.1029/2004GL021907, 2005.; Bevis, M., Busin...

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Fast Computation of the Geoelectric Field Using the Method of Elem...

By: Bear Working Group; O. Amm; R. Pirjola; A. Pulkkinen; T. Korja; A. Viljanen

Description: Finnish Meteorological Institute, Geophysical Research Division, P.O.B. 503, FIN-00101 Helsinki, Finland. The method of spherical elementary current systems provides an accurate modelling of the horizontal component of the geomagnetic variation field. The interpolated magnetic field is used as input to calculate the horizontal geoelectric field. We use planar layered (1-D) models of the Earth's conductivity, and assume that the electric field is related ...

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Geomagnetic Activity Forcing of the Northern Annular Mode Via the ...

By: D. R. Palamara; E. A. Bryant

Description: University of Wollongong, School of Geosciences, NSW 2522, Australia. We consider various aspects of the link between solar-modulated geomagnetic activity and the Northern Annular Mode (NAM). Our results indicate that the geomagnetic forcing of atmospheric circulation in the Northern Hemisphere is temporally and seasonally restricted, modulated by the Quasi-Biennial Oscillation (QBO), and reliant on stratosphere-troposphere coupling. When the data are re...

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The Relationship of Thermospheric Density Anomaly with Electron Te...

By: G. N. Kervalishvili; H. Lühr

Description: Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany. We present in a statistical study a comparison of thermospheric mass density enhancements (Ρrel) with electron temperature (Te), small-scale field-aligned currents (SSFACs), and vertical ion velocity (Vz) at high latitudes around noon magnetic local time (MLT). Satellite data from CHAMP (CHAllenging ...

Friis-Christensen, E., Lühr, H., Knudsen, D., and Haagmans, R.: Swarm – An Earth Observation Mission investigating Geospace, Adv. Space Res., 41, 210–216, 2008.; Bruinsma, S., Forbes, J. M., Nerem, R. S., and Zhang, X.: Thermospheric density response to the 20–21 November 2003 solar and geomagnetic storm from CHAMP and GRACE accelerometer data, J. Geophys. Res., 111, A06303, doi:10.1029/2005JA011284, 2006.; Burchill, J. ...

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The Role Played by Thermal Feedback in Heated Farley-buneman Waves...

By: J.-p. St.-maurice; R. S. Kissack

Description: Department of Physics and Astronomy, The University of Western Ontario, London, Ontario N6A 3K7, Canada. It is becoming increasingly clear that electron thermal effects have to be taken into account when dealing with the theory of ionospheric instabilities in the high-latitude ionosphere. Unfortunately, the mathematical complexity often hides the physical processes at work. We follow the limiting cases of a complex but systematic generalized fluid appro...

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Accuracy of Multi-point Boundary Crossing Time Analysis : Volume 2...

By: G. Paschmann; S. Haaland; J. Vogt

Description: School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany. Recent multi-spacecraft studies of solar wind discontinuity crossings using the timing (boundary plane triangulation) method gave boundary parameter estimates that are significantly different from those of the well-established single-spacecraft minimum variance analysis (MVA) technique. A large survey of directional discontinuities in Cluster data turned ou...

Burlaga, L. F. and Ness, N. F.: Tangential Discontinuities in the Solar Wind, Sol. Phys., 9, 467–477, doi:10.1007/BF02391672, 1969.; Chanteur, G.: Spatial Interpolation for Four Spacecraft: Theory, in: Analysis Methods for Multi-Spacecraft Data, edited by: Paschmann, G. and Daly, P., pp. 371–393, ISSI/ESA, 1998.; Chanteur, G.: Accuracy of field gradient estimations by Cluster: Explanation of its dependency upon elongation ...

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Significance of Dungey-cycle Flows in Jupiter's and Saturn's Magne...

By: S. W. H. Cowley; S. V. Badman

Description: Department of Physics & Astronomy, University of Leicester, Leicester LE1 7RH, UK. We consider the contribution of the solar wind-driven Dungey-cycle to flux transport in Jupiter's and Saturn's magnetospheres, the associated voltages being based on estimates of the magnetopause reconnection rates recently derived from observations of the interplanetary medium in the vicinity of the corresponding planetary orbits. At Jupiter, the reconnection voltages ar...

Badman, S. V., Cowley, S. W. H., Gérard, J.-C., and Grodent, D.: A statistical analysis of the location and width of Saturn's southern auroras, Ann. Geophys., 24, 3533–3545, 2006.; AcuÑa,~M. H., Behannon,~K. W., and Connerney,~J. E. P.: Jupiter's magnetic field and magnetosphere, in: Physics of the Jovian Magnetosphere, edited by: Dessler,~A. J., Cambridge Univ. Press, Cambridge, U.K., p 1–50, 1983.; Arridge, C. S., Achilleos, N., Dougherty,~M. K., Khurana,~K. K., and Ru...

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Ionospheric Response to Variable Electric Fields in Small-scale Au...

By: K. U. Kaila; M. H. Rees; K. J. F. Sedgemore; J. R. Palmer; B. S. Lanchester; H. U. Frey

Description: Department of Physics, University of Southampton, Southampton, SO17 1BJ, UK
Fax: +44 1703 593910; e-mail: bsl@phys.soton.ac.uk. High time and space resolution optical and radar measurements have revealed the influence of electric fields on E-region electron density profiles in small-scale auroral structures. Large electric fields are present adjacent to auroral filaments produced by monoenergetic electron fluxes. The ionisation profiles measured withi...

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Tropospheric Forcing of the Boreal Polar Vortex Splitting in Janua...

By: N. Tsvetkova; A. Gabriel; P. Vargin; D. H. W. Peters; V. Yushkov

Description: Leibniz Institute for Atmospheric Physics at the University of Rostock, Kühlungsborn, Mecklenburg, Germany. The dynamical evolution of the relatively warm stratospheric winter season 2002–2003 in the Northern Hemisphere was studied and compared with the cold winter 2004–2005 based on NCEP-Reanalyses. Record low temperatures were observed in the lower and middle stratosphere over the Arctic region only at the beginning of the 2002–2003 winter. Six sudden ...

Andrews, D. G., Holton, J. R., and Leovy, C. B.: Middle Atmospheric Dynamics, Academic Press, 489 pp., 1987.; Baldwin, M. P. and Dunkerton, T. J.: Stratospheric harbingers of anomalous weather regimes, Science, 294, 581–584, 2001.; Castanheira, J. M., Liberato, L. R., Marques, C. A. F., and Graf, H.-F.: Bridging the annular mode and the North Atlantic ocscillation paradigms, J. Geophys. Res., 112, D19103, doi:10.1029/2007JD008477, 2007.; Chang, E.: Downstream development...

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Letter to the EditorA Statistical Study of the Location and Motion...

By: K. A. McWilliams; P. G. Hanlon; T. K. Yeoman

Description: Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK. The large-scale and continuous monitoring of the ionospheric cusp region offered by HF radars has been exploited in order to examine the statistical location and motion of the equatorward edge of the HF radar cusp as a function of the upstream IMF BZ component. Although a considerable scatter is seen, both parameters have a clear...

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Secular Trends in Storm-level Geomagnetic Activity : Volume 29, Is...

By: J. J. Love

Description: Geomagnetism Program, US Geological Survey, Denver, CO, USA. Analysis is made of K-index data from groups of ground-based geomagnetic observatories in Germany, Britain, and Australia, 1868.0–2009.0, solar cycles 11–23. Methods include nonparametric measures of trends and statistical significance used by the hydrological and climatological research communities. Among the three observatory groups, German K data systematically record the highest dis...

Bartels, J.: Terrestrial-magnetic activity and its relations to solar phenomena, Terr. Magn. Atmos. Electr., 37, 1–52, 1932.; Bartels, J.: Discussion of time-variations of geomagnetic activity indices \it Kp and \it Ap, 1932–1961, Ann. Geophys., 19, 1–20, 1963.; Bartels, J., Heck, N. H., and Johnston, H. F.: The three-hour range index measuring geomagnetic activity, Terr. Magn. Atmos. Electr., 44, 411–454, 1939.; Bartels, J., Heck, N. H., and Johnston, H. F.: Geomagnetic...

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Modelling of N21P Emission Rates in Aurora Using Various Cross Sec...

By: D. Lummerzheim; N. Ivchenko; M. Ashrafi; O. Jokiaho; B. S. Lanchester

Description: School of Physics and Astronomy, University of Southampton, UK. Measurements of N21P auroral emissions from the (4,1) and (5,2) bands have been made at high temporal and spatial resolution in the region of the magnetic zenith. The instrument used was the auroral imager ASK, situated at Ramfjordmoen, Norway (69.6 N, 19.2 E) on 22 October 2006. Measurements from the European Incoherent Scatter Radar (EISCAT) have been combined with the optical...

Brunger, M J. and Buckman, S J.: Electron – Molecule Scattering Cross Sections I: diatomic molecules, Phys. Rep., 357, 215–458, 2002.; Brunger, M J. and Teubner, P. J O.: Differential cross sections for electron-impact excitation of the electronic states of $\rm N_2$, Phys. Rev. A, 41, 1413–1426, 1990.; Brunger, M J., Buckman, S., and Elford, M.: Photon and Electron Interactions with Atoms, Molecules and Ions, Landolt-Börnstein Volume I/17C, Springer-Verlag, Berlin, 2003...

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