http://hdl.handle.net/2122/94 Search the Channel search http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/4165 Title: EFFECTS OF ENERGETIC SOLAR PARTICLES ON OZONE AND MINOR ATMOSPHERIC COMPONENTS INSIDE THE POLAR REGIONS <br/> <br/>Authors: Damiani, A.; INAF-IFSI <br/> <br/>Abstract: Solar activity influences the Earth’s environment, in particular the atmospheric ozone, by the direct output of the e.m. radiation or through the variability of the incoming cosmic ray flux (solar and galactic particles). Especially energetic particles, arising from huge explosions on the Sun’s surface, travel in the interplanetary medium and, if the circumstances were favorable, they could enter the terrestrial atmosphere (driven by the geomagnetic field lines of our planet) and reach the polar cap regions (geomagnetic latitude > 60°). There, they provide additional external energy and are able to produce ionizations, dissociations, dissociative ionizations and excitations phenomena by interacting with the minor constituents. The induced changes are not confined to the ion chemistry but also to the neutral components. In this way a rise of the concentration of HOx and NOx species and the triggering of catalytic cycles which lead to short (hours) and medium (days) term ozone destruction occur. Finally, also no-reactive reservoir species (e.g., HNO3, HCl, HOCl) are involved in these processes and endure large variations. The present thesis highlights the chemical variability of the middle atmosphere during and after some Solar Energetic Particle (SEP) events recorded during the current solar cycle. Special attention has been paid to the relationship between ozone and HOx data (retrieved from the Microwave Limb Sounder of EOS AURA satellite) for four events referred to 2005. The HOx data, recorded for the first time during the intense ionization caused by the SEP flux, have pointed out some features related to these phenomena not wholly captured by the current theoretical models. In addition, they have highlighted that the HOx rise is able to destroy the so-called third ozone peak at the polar latitudes of the winter hemisphere and it occurs also during medium intensity events. Besides, the analyses of January 2005 SEP events have shown that the changes on the hydrogen species leaded to variability in the concentration and partitioning of chlorine family, not discernible in the summer hemisphere. Further, the use of data coming from the HALOE instrument, referred to SEP events occurred in July 2000 and April 2002, has in short confirmed past experimental results. Finally, the study of a little SEP event occurred during May 2003 has pointed out that SEP events are not the unique ionization source inside the polar latitudes during the winter. http://hdl.handle.net/2122/4079 Title: The New AIS-INGV Ionosonde at Italian Antarctic Observatory <br/> <br/>Authors: Romano, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baskaradas, J. A.; TRIL-International Centre for Theoretical Physics, Trieste, Italy; Doumaz, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Pezzopane, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Sciacca, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Zuccheretti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia <br/> <br/>Abstract: The Italian Ionospheric Antarctic Observatory of Terra Nova Bay (74.70S, 164.11E) was recently equipped with the AIS-INGV ionosonde developed at the Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, (Italy). This paper aims to describe briefly which are the main characteristics of the instrument and show the good quality and reliability of the recorded ionograms. http://hdl.handle.net/2122/4075 Title: foF2 prediction in Rome observatory <br/> <br/>Authors: Perrone, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zolesi, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Malagnini, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia <br/> <br/>Editors: U.R.S.I.; International Union of Radio Science <br/> <br/>Abstract: A prediction procedure of the hourly values of the critical frequency of the F2 ionospheric layer, foF2, based on the local geomagnetic index ak, is presented. The geomagnetic index utilised is the time-weighted accumulation magnetic index ak(τ) based on recent past history of the index ak. It is utilised an empirical relationship between the log(NmF2(t)/ NmF2M), where NmF2(t) is the hourly maximum electron density at the F2 peak layer and NmF2M is its 'quiet' value, and the time weighted magnetic index. The prediction of foF2 is calculated during periods of severe magnetic activity in the current solar cycle 23 in Rome observatory. 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.