Ionospheric Doppler measurements by means of HF-radar techniques

Studies of the dynamics of the ionosphere and its related phenomena are mainly based on Doppler Drift measurements. The time variation (ionisation/recombination) of plasma density, thermospheric wind and others can be observed by means of HF-radars. The technique of Doppler Drift measurements is a quite complex technique that is now affordable by means of an advanced ionospheric sounder. The combination of vertical sounding and interferometric Doppler detection discloses the Doppler sources. The echo signal contains the Doppler shift in frequency imposed on the wave carrier by each point source where the signal is reflected. Other phenomena like environmental noise and the intrinsic error of the measurements that, together with the change in time of the refractive index, affect the measurements in various ways impeding to better quantify the results

The 22-year cycle in the geomagnetic 27-day recurrences reflecting on the F2-layer ionization

Solar cycle variations of the amplitudes of the 27-day solar rotation period reflected in the geomagnetic activity index <i>A<sub>p</sub></i>, solar radio flux F10.7cm and critical frequency <i>fo</i>F2 for mid-latitude ionosonde station Moscow from the maximum of sunspot cycle 18 to the maximum of cycle 23 are examined. The analysis shows that there are distinct enhancements of the 27-day amplitudes for <i>fo</i>F2 and <i>A<sub>p</sub></i> in the late declining phase of each solar cycle while the amplitudes for F10.7cm decrease gradually, and the <i> fo</i>F2 and <i>A<sub>p</sub></i> amplitude peaks are much larger for even-numbered solar cycles than for the odd ones. Additionally, we found the same even-high and odd-low pattern of <i>fo</i>F2 for other mid-latitude ionosonde stations in Northern and Southern Hemispheres. This property suggests that there exists a 22-year cycle in the F2-layer variability coupled with the 22-year cycle in the 27-day recurrence of geomagnetic activity.<br><br> <b>Key words.</b> Ionosphere (mid-latitude ionosphere; ionosphere- magnetosphere interactions) – Magnetospheric physics (solar wind-magnetosphere interactions

Daytime Electron Density At the F1-Region in Europe During Geomagnetic Storms

This study attempts to demonstrate changes in the ionospheric F1-region daytime ionization during geomagnetic storms. The F1-region is explored using available data from several European middle latitude and lower latitude observatories and a set of geomagnetic storms encompassing a range of seasons and solar activity levels. The results of analysis suggest systematic seasonal and partly latitudinal differences in the F1-region response to geomagnetic storm. The pattern of the response of the F1-region at higher middle latitudes, a decrease in electron density, does not depend on the type of response of the F2-region and on solar activity. A brief interpretation of these findings is presented

Improvement of IRI B0, B1 and D1 at mid-latitude using MARP

Comparative analysis of predicted parameters B0, B1 and D1 by IRI-2001model (International Reference Ionosphere) and those obtained from the Monthly Averaged Representative Profiles (MARP) at mid-latitude station shows significant disagreement. The linear coefficient of determination between the model-predicted and expected (MARP) values are about R 2 ∼ 0.45, 0.22, and 0.15 for B0, B1 and D1, respectively. A Local Model (LM) created using a general least-square fit to a harmonic function of these parameters obtained by MARP simulating the diurnal, semidiurnal and seasonal variations improves the linear coefficient of determination between the expected and IRI-predicted parameters by factor of two. The coefficients obtained from this model could be implemented into the IRI software to improve calculations of the parameters B0, B1 and D1.Fil: Blanch, E.. Universitat Ramon Llull; EspañaFil: Arrazola, D.. Universitat Ramon Llull; EspañaFil: Altadill, D.. Universitat Ramon Llull; EspañaFil: Buresova, D.. Academy Of Sciences Of The Czech Republic. Institute Of Atmospheric Physics; República ChecaFil: 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"; Argentin

Long-term comparison of the ionospheric F2 layer electron density peak derived from ionosonde data and Formosat-3/COSMIC occultations

Electron density profiles (EDPs) derived from GNSS radio occultation (RO) measurements provide valuable information on the vertical electron density structure of the ionosphere and, among others, allow the extraction of key parameters such as the maximum electron density NmF2 and the corresponding peak height hmF2 of the F2 layer. An efficient electron density retrieval method, developed at the UPC (Barcelona, Spain), has been applied in this work to assess the accuracy of NmF2and hmF2 as determined from Formosat-3/COSMIC (F-3/C) radio occultation measurements for a period of more than half a solar cycle between 2006 and 2014. Ionosonde measurements of the Space Physics Interactive Data Resource (SPIDR) network serve as a reference. Investigations on the global trend as well as comparisons of the F2 layer electron density peaks derived from both occultations and ionosonde measurements are carried out. The studies are performed in the global domain and with the distinction of different latitude sectors around the magnetic equator ±[0°, 20°], ±]20°, 60°] and ±]60°, 90°]) and local times (LT) accounting for different ionospheric conditions at night (02:00 LT ± 2 h), dawn (08:00 LT ± 2 h), and day (14:00 LT ± 2 h). The mean differences of F2 layer electron density peaks observed by F-3/C and ionosondes are found to be insignificant. Relative variations of the peak differences are determined in the range of 22%–30% for NmF2 and 10%–15% for hmF2. The consistency of observations is generally high for the equatorial and mid-latitude sectors at daytime and dawn whereas degradations have been detected in the polar regions and during night. It is shown, that the global averages of NmF2 and hmF2 derived from F-3/C occultations appear as excellent indicators for the solar activity.JRC.G.5-Security technology assessmen

Planetary and gravity wave signatures in the F-region ionosphere with impacton radio propagation predictionsand variability

The aim of this work within the WP 3.1 of the COST 271 Action is the characterization of the variability introduced in the F-region ionosphere by -Planetary Wave Signatures- (PWS) and -Gravity Wave Signatures- (GWS). Typical patterns of percentage of time occurrence and time duration of PWS, their climatology and main drivers, as well as their vertical and longitudinal structure have been obtained. Despite the above characterization, the spectral distribution of event duration is too broad to allow for a reasonable prediction of PWS from ionospheric measurements themselves. GWS with a regular morning/evening wave bursts and specific GWS events whose arising can be predicted have been evaluated. As above, their typical pattern of occurrence and time duration, and their vertical structure have been obtained. The latter events remain in the ionospheric variability during disturbed days while additional wave enhancements of auroral origin occur. However, both types of disturbances can be distinguished

Plasmaspheric Electron Content contribution inferred from ground and radio occultation derived Total Electron Content

The FORMOSAT-3/COSMIC satellite constellation has become an important source of remote sensing data globally distributed for the sounding of the atmosphere of the Earth and, in particular, the ionosphere. In this study, electron density profiles derived using the Improved Abel transform inversion in Radio Occultation (RO) scenarios are used as input data to derive some features regarding the topside and outside ionospheric contribution, hence, the plasmasphere in great extend, by means of the analysis of the integral values of the shape functions corresponding to each density profile. The novelty presented in this paper, with respect to previous works, is the use of experimental data from the FORMOSAT-3/COSMIC RO-derived electron densities to infer global characterizations and distribution of the Total Electron Content (TEC) into its main components: ionospheric TEC and plasmaspheric TEC, both contributing to TEC. The results show agreement with earlier modeled and observational data from previous local studies of the plasmaspheric contribution. The main conclusion of this research is that the plasmasphere contributes significantly to TEC and the ratio between plasmaspheric TEC and TEC has been climatologically analyzed for the whole year 2007 confirming that the major relative impact of the plasmasphere is during night time. The added value of this study is that the results obtained are globally distributed and can help to infer a proxy for the plasmaspheric contribution at any location over the globe thanks to the FORMOSAT-3/COSMIC coverage.Peer ReviewedPostprint (published version