Testing the three-dimensional IRI-SIRMUP-P mapping of the ionosphere for disturbed periods

This paper describes the three-dimensional (3-D) electron density mapping of the ionosphere given as output by the assimilative IRI-SIRMUP-P (ISP) model for three different geomagnetic storms. Results of the 3-D model are shown by comparing the electron density profiles given by the model with the ones measured at two testing ionospheric stations: Roquetes (40.8°N, 0.5°E), Spain, and San Vito (40.6°N, 17.8°E), Italy. The reference ionospheric stations from which the autoscaled foF2 and M(3000)F2 data as well as the real-time vertical electron density profiles are assimilated by the ISP model are those of El Arenosillo (37.1°N, 353.3°E), Spain, Rome (41.8°N, 12.5°E), and Gibilmanna (37.9°N, 14.0°E), Italy. Overall, the representation of the ionosphere made by the ISP model is better than the climatological representation made by only the IRI-URSI and the IRI-CCIR models. However, there are few cases for which the assimilation of the autoscaled data from the reference stations causes either a strong underestimation or a strong overestimation of the real conditions of the ionosphere, which is in these cases better represented by only the IRI-URSI model. This ISP misrepresentation is mainly due to the fact that the reference ionospheric stations covering the region mapped by the model turn out to be few, especially for disturbed periods when the ionosphere is very variable both in time and in space and hence a larger number of stations would be required. The inclusion of new additional reference ionospheric stations could surely smooth out this concern.     

Science rational for MIERS/IRI collaboration

In this paper, we will shortly highlight some of the aspects that COST Action 296 on Mitigation of Ionospheric Effects on Radio Systems (MIERS) and International Reference Ionosphere (IRI) have in common in an attempt to define science rationale for collaboration between these two international projects.     

COST 296 action results for space weather ionospheric monitoring and modelling

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.     

A simple algorithm for regional mid-latitude ionospheric modelling

A simplified model of the key vertical-incidence ionospheric characteristics such as f₀ F2, M(3000) F2, h'F, f₀F1, and f₀E that are used for prediction of operational parameters of HF telecommunication system in restricted area has been developed. The model is based upon the Fourier analysis of the monthly median values of these characteristics from seven ionospheric stations in Europe. It is shown that only 12 dominant Fourier coefficeints, expressed as function of local time, solar activity and geographic latitude are sufficient to reproduce the main features of the diurnal, seasonal and solar cycle behaviour of the mid-latitude ionosphere under median conditions.     

Oblique-incidence ionospheric soundings over Central Europe and their application for testing now casting and long term prediction models

After a first oblique-incidence ionospheric sounding campaign over Central Europe performed during the period 2003–2004 over the radio links between Inskip (UK, 53.5°N, 2.5°W) and Rome (Italy, 41.8°N, 12.5°E) and between Inskip and Chania (Crete, 35.7°N, 24.0°E), new and more extensive analysis of systematic MUF measurements from January 2005 to December 2006 have been performed. MUF measurements collected during moderately disturbed days (17 ? Ap ? 32), disturbed days (32 < Ap ? 50) and very disturbed days (Ap > 50), have been used to test the long term prediction models (ASAPS, ICEPAC and SIRM&LKW), and the now casting models (SIRMUP&LKW and ISWIRM&LKW). The performances of the different prediction methods in terms of r.m.s are shown for selected range of geomagnetic activity and for each season.     

On the importance of total electron content enhancements during the extreme solar minimum

Observations of ionospheric vertical total electron content (vTEC) from European ground-based Global Navigation Satellite Systems (GNSS) receivers during the period January 2008–January 2010 are used to investigate, for the first time, vTEC sensitivity to weak geomagnetic disturbances under extreme solar minimum conditions. This study shows a significant number of events for the period in question, all of which exhibited some form of exceptionally large values of vTEC during small-magnitude geomagnetic disturbances. To illustrate our point on the importance of vTEC enhancements during the extreme solar minimum and its relevance for the current GNSS and future Galileo applications, we present in this paper the results associated with two significant events that both occurred in equinoctial months. The 10–12 October 2009 event of anomalous TEC enhancement at two distant mid-latitude locations HERS (0.3 E; 50.9 N) and NICO (33.4 E, 35.1 N) is discussed in the context of strong vTEC variations during the well established ionospheric storm on 11 October 2008. We conclude with a short summary of the new findings and their consequences on ionospheric monitoring and modelling for operational communication and navigation systems.