http://hdl.handle.net/2122/95 Search the Channel search http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/4058 Title: Morphology of F-region vertical E×B drifts in the African sector using ionosonde measurements <br/> <br/>Authors: Oyekola, O. S.; Department of Physics, College of Science and Technology, Covenant University, Canaanland, Ota, Ogun State, Nigeria; Oluwafemi, C. C.; Department of Physics, College of Science and Technology, Covenant University, Canaanland, Ota, Ogun State, Nigeria <br/> <br/>Abstract: F-region vertical velocities are derived from the ground-based ionosonde data for Ibadan (7.4°N, 3.9°E; dip 6°S: an equatorial station in the African zone), to study the general characteristics of electrodynamics of equatorial ionosphere, such as their variation with season, solar cycle, and magnetic activity at different local time sectors. The results show profound seasonal and geomagnetic effects. Except for equinoctial period, there is an excellent consistency in the magnitudes (nearly 20 m/s) and patterns of upward daytime F-region drifts at low and high solar activity periods. Evening F-region exhibits strong motion with absolute mean value for quiet-time (15 m/s) greater than on disturbed-time (10 m/s). The average downward quiet midnight-early morning hours sector value is well below than 10 m/s. The evening reversal time is earliest and latest during solstitial periods. Prereversal peak is season dependent and varies strongly with magnetic activity. We show that prereversal peak, daytime, and nighttime maximum drifts saturate at particular values of F10.7 cm solar radio flux index, effects not noticed with corresponding sunspot number. Our observations confirm several previous results from other equatorial sites utilizing different experimental techniques. Fri, 28 Sep 2007 22:58:59 GMT http://hdl.handle.net/2122/4034 Title: Interobl: An interactive software tool for displaying and scaling oblique ionograms <br/> <br/>Authors: Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia <br/> <br/>Abstract: By analyzing an oblique ionogram several characteristics, such as LOF, MOF, FMUF, FHLOF, FLLOF, and 2FMOF, can be found. These characteristics are important both for ionospheric studies and for terrestrial communication purposes, as they give information about the sky wave communication conditions in the High Frequency (HF) radio spectrum. A RCS-5B sweeping HF receiver for oblique sounding was installed at Chania (Crete, Greece, 35.71N, 24.01E) in April 2005 to perform a radio link with Inskip (UK, 53.51N, 2.51W). The receiver, able to record the sounding only as a binary file, was not equipped with a tool to display and scale the recorded trace. This work describes software that is able to do this, consequently increasing the speed of the scaling phase performed by the operator. The usefulness of this software for validating FMUF prediction models is also shown. Fri, 08 Aug 2008 22:58:59 GMT http://hdl.handle.net/2122/3763 Title: Dynamics of high-latitude patches 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.; University of Nottingham; Dodson, A.; University of Nottingham; Mitchell, C. N.; University of Bath; Spencer, P.; University of Bath; Wernik, A. W.; SRC-PAS <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. Thu, 28 Jun 2007 22:58:59 GMT http://hdl.handle.net/2122/3704 Title: A method for automatic scaling of F1 critical frequencies from ionograms <br/> <br/>Authors: Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia <br/> <br/>Abstract: This work describes a method that has been developed to automatically assess whether the F1 layer is present or not on an ionogram trace, and, if present, to scale the F1 critical frequency foF1. The ionograms in which the information related to the F1 trace is insufficient are identified and considered separately. In order to test the performance of this method and the conditions in relation to which it could be improved, a data set of ionograms recorded from September 2005 to June 2006 by the AIS-INGV ionosonde installed at Rome was used. The values obtained automatically by Autoscala, with the addition of this new F1 layer routine, were compared with those obtained by the standard manual method. Fri, 21 Mar 2008 22:58:59 GMT