http://hdl.handle.net/2122/97 Search the Channel search http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/3858 Title: Dynamics of high-latitude pathches and associated small-scale irregularities during the October and November 2003 storms <br/> <br/>Authors: De Franceschi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Alfonsi, Lu.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Romano, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Aquino, M.; IESSG, The University of Nottingham, University Park, Nottingham NG7 2RD, UK; Dodson, A.; IESSG, The University of Nottingham, University Park, Nottingham NG7 2RD, UK; Mitchell, C. N.; Electronic and Electrical Engineering, University of Bath, Bath, UK; Spencer, P.; Electronic and Electrical Engineering, University of Bath, Bath, UK; Wernik, A. W.; Space Research Center, Polish Academy of Sciences, Warsaw, Poland <br/> <br/>Abstract: Observations from a network of specially equipped GPS scintillation receivers in Northern Europe are used to investigate the dynamics of ionospheric plasma during the storm events of 30 October and 20 November 2003. The total electron content (TEC) and scintillation data, combined with ionospheric tomography produced by the multi-instrument data analysis system (MIDAS), reveal strong enhancements and steep gradients in TEC during nighttime under a prevailing negative Bz component of the interplanetary magnetic field (IMF). Amplitude and phase scintillation maxima are often co-located with the TEC gradients at the edge of plasma patches, revealing the presence of small-scale irregularities and suggesting association with a tongue of ionization (TOI) convecting in an anti-sunward direction from the American sector across the polar cap. Similarities and differences between the ionospheric response to the two storms are investigated. The 30 October event reveals a quite complex scenario showing two phases of plasma dynamics: the former reflects the expected convection pattern for IMF Bz southward and the latter possibly indicates a sort of TEC plasma stagnation signature of the more complex convection patterns during several positive/negative excursions of IMF Bz. http://hdl.handle.net/2122/1865 Title: Results from Swedish oblique soundings campaigns <br/> <br/>Authors: Broms, M.; National Defence Research Establishment, Linkoping, Sweden; Lundhorg, B.; Swedish Institute of Space Physics, Uppsala Division, Uppsala, Sweden <br/> <br/>Abstract: In the context of the COST 238, PRIME project, two campaigns of oblique soundings with the Chirpsounder receiver at Linkoping, Sweden were made in parallel with vertical sounding campaigns. One campaign was made in June, 1992, when transmissions from Southern Spain were monitored, the other in December, 1992 when a transmitter at Chelveston, U.K, was monitored. The scaled values of F2MOF, 2-hop F2MOF and LOF give information on the variation of these parameters on short time scales and from day to day. High correlations between 2-hop F2MOF and F2MOF are found. Good agreement was found between the 2-hop MOF and MUF(1400)F2 calculated from vertical soundings at St. Peter Ording, Germany. http://hdl.handle.net/2122/1695 Title: Mid-latitude ionosphere during two great geomagnetic storms <br/> <br/>Authors: Vasiljevic, I. M.; Geomagnetic Institute, Grocka, Belgrade, Yugoslavia; Cander, L. R.; Geomagnetic Institute, Grocka, Belgrade, Yugoslavia <br/> <br/>Abstract: The ionospheric disturbances observed at many European ionosonde stations in association with the severe geomagnetic storms occurring on 19-20 December 1980 and 11-12 April 1981 were investigated by using the available ionospheric and geomagnetic data. During these storms the ionospheric F region underwent major changes at all mid-latitudes. However, the variations from storm to storm were much larger at lower mid-latitudes. These results support the view that even in assessing the response of the mid-latitude ionosphere to severe geomagnetic storms it is necessary to distinguish carefully between global, regional and local behaviour. http://hdl.handle.net/2122/1694 Title: Assessment of the solar-cycle dependence of f0F2 1157 <br/> <br/>Authors: Xenos, T. D.; Department of Electrical Engineering, University of Thessaloniki, Greece; Kouris, S. S.; Department of Electrical Engineering, University of Thessaloniki, Greece; Zolesi, B.; Istituto Nazionale di Geofisica, Roma, Italy <br/> <br/>Abstract: Comparisons between observed hourly monthly-median values of f0F2 at Slough and Rome, and calculated f0F2 values using as an index of solar activity R12 or T12, demonstrate that there is practically no difference in the results when a solar (e.g., R12) or ionospheric index (e.g., T12) is used. The choice of the index should be based on other criteria. It is also shown that there is a slight degree of favourability for a quadratic law between f0F2 and each index of solar activity. Therefore, in mapping F-layer characteristics a second-degree relation should be adopted independently of rising or falling solar-cycle. Saturation and hysteresis effects could be then minimised.