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  • 1
    Electronic Resource
    Electronic Resource
    Conjugate observations of the day-side reconnection electric field: A GEM boundary layer campaign (1999)
    Springer
    Annales geophysicae 17 (1999), S. 443-454 
    Details
    ISSN: 0992-7689
    Keywords: Ionosphere (plasma convection ; polar ionosphere) ⋅ Magnetospheric physics (magnetosphere-ionosphere interactions).
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Data from HF-radars are used to make the first simultaneous conjugate measurements of the day-side reconnection electric field. A period of 4 h around local magnetic noon are studied during a geospace environment modeling (GEM) boundary layer campaign. The interplanetary magnetic field (IMF) was southward whilst the eastward component (By) was variable. The flow patterns derived from the radar data show the expected conjugate asymmetries associated with IMF |By| ≥ 0. High-time resolution data (50 and 100 s) enable the flow of plasma across the open/closed field line boundary (the separatrix) to be studied in greater detail than in previous work. The latitude of the separatrix follows the same general trend in both hemispheres but shows a hemispherical difference of 4°, with the summer cusp at higher latitude, as expected from dipole tilt considerations. However, the short-time scale motion of the separatrix cannot be satisfactorily resolved within the best resolution (300 m s−1) of the experiment. The orientation of the separatrix with respect to magnetic latitude is found to follow the same trend in both hemispheres and qualitatively fits that predicted by a model auroral oval. It shows no correlation with IMF By. However, the degree of tilt in the Northern (summer) Hemisphere is found to be significantly greater than that given by the model oval. The convection pattern data show that the meridian at which throat flow occurs is different in the two hemispheres and is controlled by IMF By, in agreement with empirically derived convection patterns and theoretical models. The day-side reconnection electric field values are largest when the radar’s meridian is in the throat flow or early afternoon flow regions. In the morning or afternoon convection cells, the reconnection electric field tends to zero away from the throat flow region. The reconnection electric field observed in the throat flow region is bursty in nature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-999-0443-4
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Simultaneous two hemisphere observations of the presence of polar patches in the nightside ionosphere (1994)
    Springer
    Annales geophysicae 12 (1994), S. 642-648 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The presence of polar patches as observed simultaneously in the same magnetic meridian of opposite nightside ionospheres by coherent and incoherent scatter radars are described. The patches appear to be related to variations either in the Bz or By component of the interplanetary magnetic field which cause transient merging on the dayside magnetopause. The passage and characteristics of polar patches as they traverse the polar cap into the nightside auroral oval are not significantly affected by the occurrence of small substroms. This study illustrates how the observations of polar patches in the nightside high-latitude ionosphere could be of great value in determining their formation process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-994-0642-y
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    High spatial and temporal resolution observations of the ionospheric cusp (1995)
    Springer
    Annales geophysicae 13 (1995), S. 919-925 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The Halley PACE HF radar has been operated in a new mode to provide very high time (10 s) and space (15 km) resolution measurements of the iono-spheric signatures of the cusp and the low-latitude boundary layer. The first data show that the iono-spheric signature of flux transfer events occur up to 300 km equatorward of regions showing the HF characteristics of the ionospheric cusp. Whilst larger flux transfer events are seen, on average, every 7 min, many much smaller and short-duration events have been identified. On one occasion DMSP data have been used to show that at least four flux transfer events are occurring simultaneously at the edge of the cusp over 2 h of MLT. There is strong, but not conclusive evidence, that reconnection at the magnetopause is both intermittent and patchy. These data also suggest that flux transfer events can be a significant contributor to the cross-polar cap potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-995-0919-9
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    DARN/SuperDARN (1995)
    Springer
    Space science reviews 71 (1995), S. 761-796 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Dual Auroral Radar Network (DARN) is a global-scale network of HF and VHF radars capable of sensing backscatter from ionospheric irregularities in the E and F-regions of the high-latitude ionosphere. Currently, the network consists of the STARE VHF radar system in northern Scandinavia, a northern-hemisphere, longitudinal chain of HF radars that is funded to extend from Saskatoon, Canada to central Finland, and a southern-hemisphere chain that is funded to include Halley Station, SANAE and Syowa Station in Antarctica. When all of the HF radars have been completed they will operate in pairs with common viewing areas so that the Doppler information contained in the backscattered signals may be combined to yield maps of high-latitude plasma convection and the convection electric field. In this paper, the evolution of DARN and particularly the development of its SuperDARN HF radar element is discussed. The DARN/SupperDARN network is particularly suited to studies of large-scale dynamical processes in the magnetosphere-ionosphere system, such as the evolution of the global configuration of the convection electric field under changing IMF conditions and the development and global extent of large-scale MHD waves in the magnetosphere-ionosphere cavity. A description of the HF radars within SuperDARN is given along with an overview of their existing and intended locations, intended start of operations, Principal Investigators, and sponsoring agencies. Finally, the operation of the DARN experiment within ISTP/GGS, the availability of data, and the form and availability of the Key Parameter files is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00751350
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    Paper (German National Licenses)
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