Ionogram inversion F1-layer treatment effect in raytracing

This paper shows the importance of the F1-layer shape in the electron density profiles obtained from ionograms with different inversion techniques when the profiles are used in ray tracing. This layer often controls the propagation on the path with ranges less than about 2000 km, particularly for spring and summer periods. Ionograms from two different stations, Hainan (19.4N, 109E) and El Arenosillo (37.1N, -6.7E), obtained during the month of July 2002 (average sunspot number: 99.6) during geomagnetic quiet conditions (Ap-index between 9 and 15) are analyzed. The profiles obtained with two different inversion techniques with different options are used together with the ray tracing program of the Proplab-Pro software. This program calculates the features of the received signal as angle of arrival, path length, height of reflection and range for each given profile assumed to define a spherically symmetric ionosphere in the region along the path. For each ionospheric condition (location, day, hour) the difference between range values obtained with Proplab-Pro program using profiles from the two techniques and the different options (POLAN no valley, POLAN valley, POLAN1-layer and NHPC) are considered

Validation of a method for ionospheric electron density reconstruction by means of vertical incidence data during quiet and storm periods

A preliminary validation of the technique developed using the NeQuick ionospheric model and the «effective ionization parameter» Az, based on vertical total electron content data ingestion, was carried out in a previous study. The current study was performed to extend the analyzed conditions and confirm the results. The method to validate this technique is based on a comparison between hourly F2 peak values measured with Vertical Incidence (VI) soundings and those calculated with the new technique. Data corresponding to different hours and seasons (equinox, summer solstice, and winter solstice) during the period 2000-2003 (high and medium solar activity conditions) were compared for all available ionosonde stations. The results show a good agreement between foF2 and hmF2 values obtained with the new technique and measurements from vertical incidence soundings during quiet and storms conditions

A model assisted ionospheric electron density reconstruction method based on vertical TEC data ingestion

A technique to reconstruct the electron density of the ionosphere starting from total electron content values has been developed using the NeQuick ionospheric electron density model driven by its effective ionization parameter Az. The technique is based on the computation of Az values for a suitable worldwide grid of points. A simple way to obtain relevant Az grids is to use global vertical Total Electron Content (TEC) maps to define for each grid point as Az value, the one that minimizes the difference between the experimental and the modeled vertical TEC. Having a global grid of Az values it is possible to compute the electron density at any point in the ionosphere using NeQuick. As a consequence, slant TEC values for specific ground station to satellite links or ionosphere peak parameter values at any location can be calculated. The results of the comparisons between experimental and reconstructed slant TEC as well as experimental and reconstructed peak parameters values indicate that the proposed reconstruction method can be used to reproduce the observed ionosphere in a realistic way

Longitudinal Differences Observed in the Ionospheric F-Region During the Major Geomagnetic Storm of March 31, 2001

A new ionospheric sounding station using a Canadian Advanced Digital Ionosonde (CADI) was established for routine measurements by the “Universidade do Vale do Paraiba (UNIVAP)” at S˜ao Jos´e dos Campos (23.2_ S, 45.9_ W), Brazil, in August 2000. A major geomagnetic storm with gradual commencement at about 01:00 UT was observed on 31 March 2001. In this paper, we present and discuss salient features from the ionospheric sounding measurements carried out at S. J. Campos on the three consecutive UT days 30 March (quiet), 31 March (disturbed) and 1 April (recovery) 2001. During most of the storm period, the foF2 values showed negative phase, whereas during the two storm-time peaks, large F-region height variations were observed. In order to study the longitudinal differences observed in the F-region during the storm, the simultaneous ionospheric sounding measurements carried out at S. J. Campos, El Arenosillo (37.1_ N, 6.7_W), Spain, Okinawa (26.3_ N, 127.8_ E), Japan and Wakkanai (45.5_ N, 141.7_ E), Japan, during the period 30 March–1 April 2001, have been analyzed. A comparison of the observed ionospheric parameters (h0F and foF2) in the two longitudinal zones (1. Japanese and 2. Brazilian-Spanish) shows both similarities and differences associated with the geomagnetic disturbances. Some latitudinal differences are also observed in the two longitudinal zones. In addition, global ionospheric TEC maps from the worldwide network of GPS receivers are presented, showing widespread TEC changes during both the main and recovery phases of the storm. The ionospheric sounding measurements are compared with the ASPEN-TIMEGCM model runs appropriate for the storm conditions. The model results produce better agreement during the quiet period. During the disturbed period, some of the observed F-region height variations are well reproduced by the model results. The model foF2 and TEC results differ considerably during the recovery period and indicate much stronger negative phase at all the stations, particularly at the low-latitude ones

Ionogram inversion F1-layer treatment effect in raytracing

This paper shows the importance of the F1-layer shape in the electron density profiles obtained from ionograms
 with different inversion techniques when the profiles are used in ray tracing. This layer often controls the propagation
 on the path with ranges less than about 2000 km, particularly for spring and summer periods. Ionograms
 from two different stations, Hainan (19.4N, 109E) and El Arenosillo (37.1N, -6.7E), obtained during the month
 of July 2002 (average sunspot number: 99.6) during geomagnetic quiet conditions (Ap-index between 9 and 15)
 are analyzed. The profiles obtained with two different inversion techniques with different options are used together
 with the ray tracing program of the Proplab-Pro software. This program calculates the features of the received signal
 as angle of arrival, path length, height of reflection and range for each given profile assumed to define a spherically
 symmetric ionosphere in the region along the path. For each ionospheric condition (location, day, hour) the
 difference between range values obtained with Proplab-Pro program using profiles from the two techniques and
 the different options (POLAN no valley, POLAN valley, POLAN1-layer and NHPC) are considered

Validation of a method for ionospheric electron density reconstruction by means of vertical incidence data during quiet and storm periods

A preliminary validation of the technique developed using the NeQuick ionospheric model and the «effective ionization parameter» Az, based on vertical total electron content data ingestion, was carried out in a previous study. The current study was performed to extend the analyzed conditions and confirm the results. The method to validate this technique is based on a comparison between hourly F2 peak values measured with Vertical Incidence (VI) soundings and those calculated with the new technique. Data corresponding to different hours and seasons (equinox, summer solstice, and winter solstice) during the period 2000-2003 (high and medium solar activity conditions) were compared for all available ionosonde stations. The results show a good agreement between foF2 and hmF2 values obtained with the new technique and measurements from vertical incidence soundings during quiet and storms conditions. European Community Fifth Framework Programm

A model assisted ionospheric electron density reconstruction method based on vertical TEC data ingestion

A technique to reconstruct the electron density of the ionosphere starting from total electron content values has
 been developed using the NeQuick ionospheric electron density model driven by its effective ionization parameter
 Az. The technique is based on the computation of Az values for a suitable worldwide grid of points. A simple
 way to obtain relevant Az grids is to use global vertical Total Electron Content (TEC) maps to define for each
 grid point as Az value, the one that minimizes the difference between the experimental and the modeled vertical
 TEC. Having a global grid of Az values it is possible to compute the electron density at any point in the ionosphere
 using NeQuick. As a consequence, slant TEC values for specific ground station to satellite links or ionosphere
 peak parameter values at any location can be calculated. The results of the comparisons between experimental
 and reconstructed slant TEC as well as experimental and reconstructed peak parameters values indicate
 that the proposed reconstruction method can be used to reproduce the observed ionosphere in a realistic way

Day-to-day changes in experimental electron density profiles and their implications to IRI model

The electron density variability at fixed heights is studied for use in the International Reference Ionosphere IRI model. Monthly median, upper and lower quartile values were obtained f o F2, hmF2, B0 and B1 as deduced from ionograms. The IRI electron density profiles established with these values were then compared with the median and quartiles at fixed heights. Results are shown for the three ionospheric stations E1 Arenosillo (37.1 N, 353.3 E), Tucuman (26.9 S, 294.6 E) and San Juan (31.5 S, 290.4 E) as a function of solar activity, season and local time. As found by other authors the height of maximum variability, hvmax, is located below the peak electron density height (hmF2) in all the cases. Values of differences between hmF2 and hvmax. are analized. Variability defined as the interquartile difference and hvmax results are calculated from experimental electron density profiles measured at the three stations.Fil: Amarante, G. Miró. Centro Internacional Abdus Salam de Física Teórica​; ItaliaFil: Santamaría, M. Cueto. Universidad Complutense de Madrid; EspañaFil: Mosert, Marta Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "El Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "El Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "El Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "El Leoncito"; ArgentinaFil: Radicella, Sandro María. Centro Internacional Abdus Salam de Física Teórica​; ItaliaFil: Ezquer, Rodolfo Gerardo. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Ionósfera; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentin