http://hdl.handle.net/2122/98 2013-06-19T15:11:53Z http://hdl.handle.net/2122/8573 Title: Monitoring, tracking and forecasting ionospheric perturbations using GNSS techniques Authors: Jakowski, N.; German Aerospace Center, Institute of Communications and Navigation, Neustrelitz, Germany; Béniguel, Y.; IEEA, Paris, Courbevoie, France; De Franceschi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pajares, M. H.; Universitat Politecnica de Catalunya, Res. group of Astronomy and Geomatics, Barcelona, Spain; Jacobsen, K. S.; Norwegian Mapping Authority, Geodetic Institute, Hønefoss, Norway; Stanislawska, I.; Space Research Center PAS, Warsaw, Poland; Tomasik, L.; Space Research Center PAS, Warsaw, Poland; Warnant, R.; University of Liege, Unit of Geomatics – Geodesy and GNSS, Belgium; Wautelet, G.; University of Liege, Unit of Geomatics – Geodesy and GNSS, Belgium Abstract: The paper reviews the current state of GNSS-based detection, monitoring and forecasting of ionospheric perturbations in Europe in relation to the COST action ES0803 ‘‘Developing Space Weather Products and Services in Europe’’. Space weather research and related ionospheric studies require broad international collaboration in sharing databases, developing analysis software and models and providing services. Reviewed is the European GNSS data basis including ionospheric services providing derived data products such as the Total Electron Content (TEC) and radio scintillation indices. Fundamental ionospheric perturbation phenomena covering quite different scales in time and space are discussed in the light of recent achievements in GNSS-based ionospheric monitoring. Thus, large-scale perturbation processes characterized by moving ionization fronts, wave-like travelling ionospheric disturbances and finally small-scale irregularities causing radio scintillations are considered. Whereas ground and space-based GNSS monitoring techniques are well developed, forecasting of ionospheric perturbations needs much more work to become attractive for users who might be interested in condensed information on the perturbation degree of the ionosphere by robust indices. Finally, we have briefly presented a few samples illustrating the space weather impact on GNSS applications thus encouraging the scientific community to enhance space weather research in upcoming years. 2012-12-19T23:00:00Z http://hdl.handle.net/2122/8164 Title: Assimilation of SLA along track observations in the Mediterranean with an oceanographic model forced by atmospheric pressure Authors: Dobricic, S.; CMCC; Dufau, C.; CLS; Oddo, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Pinardi, N.; UniBo; Pujol, I.; CLS; Rio, M. H.; CLS Abstract: A large number of SLA observations at a high along track horizontal resolution are an important ingredient of the data assimilation in the Mediterranean Forecasting System (MFS). Recently, new higher-frequency SLA products have become available, and the atmospheric pressure forcing has been implemented in the numerical model used in the MFS data assimilation system. In a set of numerical experiments, we show that, in order to obtain the most accurate analyses, the ocean model should include the atmospheric pressure forcing and the observations should contain the atmospheric pressure signal. When the model is not forced by the atmospheric pressure, the high-frequency filtering of SLA observations, however, improves the quality of the SLA analyses. It is further shown by comparing the power density spectra of the model fields and observations that the model is able to extract the correct information from noisy observations even without their filtering during the pre-processing. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/7723 Title: A short-term ionospheric forecasting empirical regional model (IFERM) to predict the critical frequency of the F2 layer during moderate, disturbed, and very disturbed geomagnetic conditions over the European area Authors: Pietrella, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: A short-term ionospheric forecasting empirical regional model (IFERM) has been developed to predict the state of the critical frequency of the F2 layer (foF2) under different geomagnetic conditions. IFERM is based on 13 short term ionospheric forecasting empirical local models (IFELM) developed to predict foF2 at 13 ionospheric observatories scattered around the European area. The forecasting procedures were developed by taking into account, hourly measurements of foF2, hourly quiettime reference values of foF2 (foF2QT), and the hourly timeweighted accumulation series derived from the geomagnetic planetary index ap, (ap(τ )), for each observatory. Under the assumption that the ionospheric disturbance index ln(foF2/foF2QT) is correlated to the integrated geomagnetic disturbance index ap(τ ), a set of statistically significant regression coefficients were established for each observatory, over 12 months, over 24 h, and under 3 different ranges of geomagnetic activity. This data was then used as input to compute short-term ionospheric forecasting of foF2 at the 13 local stations under consideration. The empirical storm-time ionospheric correction model (STORM) was used to predict foF2 in two different ways: scaling both the hourly median prediction provided by IRI (STORM foF2MED,IRI model), and the foF2QT values (STORM foF2QT model) from each local station. The comparison between the performance of STORM foF2MED,IRI, STORM foF2QT, IFELM, and the foF2QT values, was made on the basis of root mean square deviation (r.m.s.) for a large number of periods characterized by moderate, disturbed, and very disturbed geomagnetic activity. The results showed that the 13 IFELM perform much better than STORM foF2MED,IRI and STORM foF2QT especially in the eastern part of the European area during the summer months (May, June, July, and August) and equinoctial months (March, April, September, and October) under disturbed and very disturbed geomagnetic conditions, respectively. The performance of IFELM is also very good in the western and central part of the Europe during the summer months under disturbed geomagnetic conditions. STORM foF2MED,IRI performs particularly well in central Europe during the equinoctial months under moderate geomagnetic conditions and during the summer months under very disturbed geomagnetic conditions. The forecasting maps generated by IFERM on the basis of the results provided by the 13 IFELM, show very large areas located at middle-high and high latitudes where the foF2 predictions quite faithfully match the foF2 measurements, and consequently IFERM can be used for generating short-term forecasting maps of foF2 (up to 3 h ahead) over the European area. 2012-02-07T23:00:00Z http://hdl.handle.net/2122/7152 Title: Assimilation of autoscaled data and regional and local ionospheric models as input source for a real-time 3-D IRI modeling 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; Pignatelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Zolesi, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cander, L. R.; Rutherford Appleton Laboratory Abstract: This paper describes how the joint utilization of autoscaled data such as the F2 peak critical frequency foF2, the propagation factor M(3000)F2 and the electron density profile, coming from two reference ionospheric stations (Rome and Gibilmanna), the regional (SIRMUP) and global (IRI) ionospheric models, can provide a valid tool for obtaining a real-time three-dimensional (3-D) electron density mapping of the ionosphere. Preliminary results of the proposed 3-D model are shown by comparing the electron density profiles given by the model with the ones measured at three testing ionospheric stations (Athens, Roquetes and S.Vito). 2011-09-20T22:00:00Z http://hdl.handle.net/2122/6672 Title: Monitoring and modeling of ionospheric characteristics in the framework of European COST 296 Action MIERS Authors: Stanislawska, I.; Space Research Centre, PAS, Warsaw, Poland.; Lastovicka, J.; Institute of Atmospheric Physics, Prague, Czech Republic.; Bourdillon, A.; IETR, University of Rennes 1, Rennes, France.; Zolesi, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cander, Lj. R.; Rutherford Appleton Laboratory, Didcot, UK. Abstract: The Mitigation of Ionospheric Effects on Radio Systems COST 296 Action is devoted to the mitigation of ionospheric effects on radio systems. It creates a platform for sharing of data, algorithms, models, and jointly developed advanced technologies, the processing chain from measurements, through algorithms, to operational knowledge. This initiative creates a unique possibility for national groups to consolidate the design of a product required for their own activity and for European assessments in the ionosphere and telecommunication area. An important part of the action is to stimulate and integrate many national and international activities which provide tools for global and regional ionospheric monitoring and modeling. The work includes the near-Earth space plasma monitoring, modeling and forecasting, and a study of the upper atmosphere climate. Well-defined terms of reference include developing ground-based and space-borne monitoring techniques and parameters describing the state of ionospheric plasma, maintaining and extending the flow of real-time and retrospective ionospheric monitoring data to databases. To obtain adequate, high-quality information, special attention is paid to the data ingestion and assimilation in constructing ionospheric models of different spatial and time scale perturbations, as well as storms, small variations, and irregularities. The physical origin of atmospheric/ionospheric effects and their signatures and parameters are investigated. Identification criteria are studied and formulated. 2010-02-19T23:00:00Z http://hdl.handle.net/2122/6450 Title: COST 296 action results for space weather ionospheric monitoring and modelling Authors: Bourdillon, A.; IETR – Universite´ de Rennes1, Rennes, Baˆt 11D, Campus de Beaulieu, 35042 Rennes Cedex, France; Zolesi, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cander, L. R.; STFC, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK Abstract: COST 296 Action refers to the project on Mitigation of Ionospheric Effects on Radio Systems (MIERS) in the framework of European Cooperation in Science and Technology (COST), which is one of the longest-running European instruments supporting cooperation among scientists and researchers across Europe. The main objective of the MIERS project has been to develop an increased knowledge of the effects imposed by the ionosphere on practical radio systems, and for the development and implementation of techniques to mitigate the harmful effects of the ionosphere on such systems. This paper highlights COST 296 Action results that have been achieved during its lifetime period of February 2005–February 2009 with emphasis on space weather ionospheric monitoring and modelling 2010-05-02T22:00:00Z http://hdl.handle.net/2122/6449 Title: DIAS Effective Sunspot Number as an Indicator of the Ionospheric Activity Level over Europe Authors: Tsagouri, I.; National Observatory of Athens, Institute for Space Applications and Remote Sensing, Athens, Greece, e-mails: tsagouri@space.noa.gr; Zolesi, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Cander, L. R.; STFC, Rutherford Appleton Laboratory, Chilton, United Kingdom e-mail: l.cander@rl.ac.uk; Belehaki, A.; National Observatory of Athens, Institute for Space Applications and Remote Sensing, Athens, Greece, belehaki@space.noa.gr Abstract: DIAS (European Digital Upper Atmosphere Server) effective sunspot number – R12eff was recently introduced as a proxy of the ionospheric conditions over Europe for regional ionospheric mapping purposes. Although a pre-processing step for the real-time update of the Simplified Ionospheric Regional Model (SIRM) to real-time conditions, R12eff is available in real time by DIAS system (http://dias.space.noa.gr) for independent operational use. In this paper we discuss the efficiency of R12eff to specify ionospheric conditions over Europe. For this purpose, the diurnal R12eff’s reference pattern was determined on monthly basis and for different solar cycle phases. The deviation of the real-time R12eff estimates from the reference values, ΔR12eff was found to be highly correlated with the foF2 storm-time disturbances, especially during large scale effects indicating that DIAS-R12eff can provide a reliable estimator of the ionospheric activity level over a substantial part of Europe and a powerful tool for ionospheric specification applications. 2010-05-31T22:00:00Z http://hdl.handle.net/2122/6299 Title: A Statistical Approach to Evaluate the Tephra Deposit and Ash Concentration from Puff Model Forecasts Authors: Scollo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Prestifilippo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Coltelli, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Peterson, R. A.; Mechanical Engineering, Univ. Alaska, Fairbanks, USA; Spata, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: In this paper we present a new statistical approach able to provide tephra deposit load and ash concentration using PUFF, a lagrangian model widely used to forecast volcanic ash dispersal during volcanic crisis. We perform a parametric study in order to analyze the influence of each input parameter on model outputs. For this test, we simulate two eruptive scenarios like to the 2001 (Scenario 1) and 1998 (Scenario 2) Etna eruptions using high resolution weather data and a domain of 170 x 170 km. Results show that for both scenarios, we are able to calculate the tephra deposit load and ash concentration but the use of millions of particles is required. Specifically, up to 33 and 220 millions of particles were necessary to accurately predict the tephra deposit and ash concentration in air, respectively. This is approximately two orders of magnitude larger than values typically considered running PUFF. The parametric study shows that the horizontal diffusion coefficient, the time step of the simulations, the topography and the standard deviation of the particle distribution greatly affect the model outputs. We also validate the model by best fit procedures. Results show a good comparison between field data of the 2001 Etna eruption and PUFF simulations, being inside 5 and 1/5 times the observed data, comparable with results of Eulerian models. This work will allow to reliably outlining the areas of contaminated airspace using PUFF or any other lagrangian model in order to define the No Fly Zone and ensure the safety to aviation operations as required after the Eyjafjallajökull eruption. 2010-12-01T23:00:00Z http://hdl.handle.net/2122/5754 Title: Correlation of Static Stress Changes and Earthquake Occurrence in Authors: Rhoades, D. A.; GNS Science, Lower Hutt, New Zealand; Papadimitriou, E. E.; Geophysics Department, University of Thessaloniki, GR54124 Thessaloniki, Greece; Karakostas, V. G.; Geophysics Department, University of Thessaloniki, GR54124 Thessaloniki, Greece; Console, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Murru, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: A systematic analysis is made of static Coulomb stress changes and earthquake occurrence in the area of the North Aegean Sea, Greece, in order to assess the prospect of using static stress changes to construct a regional earthquake likelihood model. The earthquake data set comprises all events of magnitude M ≥ 5.2 which have occurred since 1964. This is compared to the evolving stress field due to constant tectonic loading and perturbations due to coseismic slip associated with major earthquakes (M ≥ 6.4) over the same period. The stress was resolved for sixteen fault orientation classes, covering the observed focal mechanisms of all earthquakes in the region. Analysis using error diagrams shows that earthquake occurrence is better correlated with the constant tectonic loading component of the stress field than with the total stress field changes since 1964, and that little, if any, information on earthquake occurrence is lost if only the maximum of the tectonic loading over the fault orientation classes is considered. Moreover, the information on earthquake occurrence is actually increased by taking the maximum of the evolving stress field since 1964, and of its coseismic–slip component, over the fault orientation classes. The maximum, over fault orientation classes, of linear combinations of the tectonic loading and the evolving stress field is insignificantly better correlated with earthquake occurrence than the maximum of the tectonic loading by itself. A composite stress–change variable is constructed from ordering of the maximum tectonic loading component and the maximum coseismic–slip component, in order to optimize the correlation with earthquake occurrence. The results indicate that it would be difficult to construct a time–varying earthquake likelihood model from the evolving stress field that is more informative than a time–invariant model based on the constant tectonic loading. Description: A systematic analysis is made of static Coulomb stress changes and earthquake occurrence in the area of the North Aegean Sea, Greece, in order to assess the prospect of using static stress changes to construct a regional earthquake likelihood model. 2008-12-31T23:00:00Z http://hdl.handle.net/2122/5751 Title: Retrospective forecasting of M≥4.0 earthquakes in New Zealand Authors: Console, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Murru, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Falcone, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: We have applied a variation of the ETAS model, which is a stochastic triggering epidemic model incorporating short-term clustering, to data collected by the New Zealand Seismological Observatory-Wellington (Geonet) for forecasting earthquakes of moderate and large magnitude in the New Zealand region. The model uses earthquake data only, with no explicit use of tectonic, geologic, or geodetic information. In this epidemic-type model every earthquake is regarded, at the same time, as being triggered by previous events and triggering following earthquakes. A maximum likelihood estimate of the model parameters has been performed on the learning period from 1960 to 2005 for earthquakes of magnitude 4.0 and larger. Forecast verification procedures have been carried out in forward-retrospective way on the January 2006-April 2008 data set, making use of statistical tools as the log-likelihood ratio, the Relative Operating Characteristics (ROC) diagrams, the Molchan error diagrams, the probability gain and the R-score. These procedures show that the clustering epidemic model achieves a log-likelihood ratio per event of the order of some units, and a probability gain up to several hundred times larger than a time-independent spatially uniform random forecasting hypothesis. The results show also that a significant component of the probability gain is linked to the time-independent spatial distribution of the seismicity used in the model. Description: We have applied a variation of the ETAS model, which is a stochastic triggering epidemic model incorporating short-term clustering, to data collected by the New Zealand Seismological Observatory-Wellington (Geonet) for forecasting earthquakes of moderate and large magnitude in the New Zealand region. 2008-12-31T23:00:00Z