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Relations between hourly monthly median values of foF2 and some geophysical indices. Their application to an ionospheric single station model

100%

Sole J.

Acta Geophysica Polonica

1998

tom Vol. 46, nr 1

77-88

A set of empirical relations between the hourly monthly median values of the critical frequency of ionospheric layer F2 (foF2) and geophysical indices has been considered in order to determine which relation and which index should be used as a single station model. An application to the forecast is also shown.

Comparison of GPS/Galileo single frequency ionospheric models with vertical TEC maps

80%

Farah A. M. A.

Artificial Satellites : Journal of Planetary Geodesy

2008

tom Vol. 43, No. 2

75--90

The ionospheric delay is the major current source of potential range delay for single-frequency GNSS users (Kunches and Klobuchar, 2001). Single-frequency GNSS users are in most need of an ionospheric model to eliminate the ionospheric delay to a high degree of accuracy. GPS system uses the Klobuchar model for this task, which its coefficients are sent through the GPS navigation message to GPS users. Klobuchar model uses the Ionospheric Corrections Algorithm (ICA) (Klobuchar, 1987) designed to account for approximately 50% (rms) of the ionospheric range delay. NeQuick model is a model of the electron concentration profile that has been developed in the framework of the European Commission COST action 251. NeQuick model is being proposed for single-frequency operation in the European Galileo GNSS system (Radicella et al., 2003). A comparison study between the behaviour of the GPS Single-frequency ionospheric modelling (Klobuchar model) and the Galileo proposed approach for this task (NeQuick model) will be presented in this paper. The range delay correction by the two models has been assessed using the IGSGlobal Ionospheric Maps for three different-latitude stations to reflect different geographic ionospheric activity states. The study was carried out over three different months that each of them reflects a different state of solar activity, which is a major indication for the ionospheric development state.

Comparison of various foF2 single station models for European area

80%

Alberca L. , Juchnikowski G. , Stanisławska I. , Kouris S. , Mikhailov A. , Mikhailov V. , Miro G. , Morena B. , Mukhtarov P. , Pancheva D. , Villanueva L.

Acta Geophysica Polonica

1999

tom Vol. 47, nr 1

77-91

Five Single Station Models (SSM's) for hourly monthly median values of the critical frequency of the ionospheric F2 layer (foF2) obtained from vertical-incidence sounding and global IRI-95 and PRIME/CCIR models have been compared using data from 22 European ionospheric stations. The stations are conveniently distributed to cover the COST 251 area (10 degrees W-60 degrees E, 35 degrees N-70 degrees N). The SSM's have been developed within the frame of COST 238 and COST 251 European Projects. The accuracy of the models has been discussed in terms of standard deviation and average percentage deviation. The Kolmogorov-Smirnov test has been also applied. The results show that all Single Station Models (SSM's) give better accuracy than global models and they can provide a remarkable advantage in mapping techniques.

Local Ionospheric Modeling Using the Localized Global Ionospheric Map and Terrestrial GPS

70%

Sharifi M. A. , Farzaneh S.

Acta Geophysica

2016

tom Vol. 64, no. 1

237--252

Global ionosphere maps are generated on a daily basis at CODE using data from about 200 GPS/GLONASS sites of the IGS and other institutions. The vertical total electron content is modeled in a solargeomagnetic reference frame using a spherical harmonics expansion up to degree and order 15. The spherical Slepian basis is a set of bandlimited functions which have the majority of their energy concentrated by optimization inside an arbitrarily defined region, yet remain orthogonal within the spatial region of interest. Hence, they are suitable for decomposing the spherical harmonic models into the portions that have significant strength only in the selected areas. In this study, the converted spherical harmonics to the Slepian bases were updated by the terrestrial GPS observations by use of the least-squares estimation with weighted parameters for local ionospheric modeling. Validations show that the approach adopted in this study is highly capable of yielding reliable results.

Mid-Latitude Single Station F region Storm Morphology and Forecast

60%

Cander L. R.

Acta Geophysica

2016

tom Vol. 64, no. 2

541--566

This paper describes certain aspects of the F region storm morphology based on vertical incidence measurements at single ionosonde station Chilton (51°.60′N, 358°.70′E). The topics discussed include requirements for better understanding of the ionospheric F region morphology and its forecasting under geomagnetically quiet and disturbed conditions. A few common storms during the years of low (1996 and 1997) and high (2000 and 2001) solar activity are considered as well as the Short-Term Ionospheric Forecasting (STIF) method by using two representative examples. The merits are stressed of near-real-time use of data to provide more accurate specification of the geomagnetically disturbed ionosphere and forecast its structure few hours in advance.