To address challenges of assessing space weather modeling capabilities, the Community Coordinated Modeling Center is leading a newly established International Forum for Space Weather Modeling Capabilities Assessment. This paper presents preliminary results of validation of modeled foF2 (F 2 layer critical frequency) and TEC (total electron content) during the first selected 2013 March storm event (17 March 2013). In this study, we used eight ionospheric models ranging from empirical to physics-based, coupled ionosphere-thermosphere and data assimilation models. The quantities we considered are TEC and foF2 changes and percentage changes compared to quiet time background, and the maximum and minimum percentage changes. In addition, we considered normalized percentage changes of TEC. We compared the modeled quantities with ground-based observations of vertical Global Navigation Satellite System TEC (provided by Massachusetts Institute of Technology Haystack Observatory) and foF2 data (provided by Global Ionospheric Radio Observatory) at the 12 locations selected in middle latitudes of the American and European-African longitude sectors. To quantitatively evaluate the models' performance, we calculated skill scores including correlation coefficient, root-mean square error (RMSE), ratio of the modeled to observed maximum percentage changes (yield), and timing error. Our study indicates that average RMSEs of foF2 range from about 1 MHz to 1.5 MHz. The average RMSEs of TEC are between~5 and~10 TECU (1 TEC Unit = 10 16 el/m 2 ). dfoF2[%] RMSEs are between 15% and 25%, which is smaller than RMSE of dTEC[%] ranging from 30% to 60%. The performance of the models varies with the location and metrics considered.To address the needs and challenge of assessment of our current knowledge about space weather effects on IT system and current state of IT modeling capabilities, the Community Coordinated Modeling Center (CCMC) has been supporting community-wide model validation projects, including Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) and Geospace Environment Modeling (GEM)-CEDAR modeling challenges. The CCMC initiated the CEDAR electrodynamics thermosphere ionosphere challenge in 2009 focusing on the evaluation of basic IT system parameters modeled, such as electron and neutral densities, the ionospheric F 2 layer peak electron density (NmF2) and peak height (hmF2), and vertical drift (Shim Key Points: • foF2/TEC and foF2/TEC changes during a storm predicted by eight ionosphere models were compared with GIRO foF2 and GPS TEC measurements • Skill scores (e.g., correlation coefficient, RMSE, yield, and timing error) were calculated • Model performance strongly depends on the quantities considered, the type of metrics used, and the location considered Supporting Information: • Supporting Information S1 Correspondence to: J. S. Shim, jasoon.shim@nasa.gov Citation: Shim, J. S., Tsagouri, I., Goncharenko, L., Rastaetter, L., Kuznetsova, M., Bilitza, D., et al. (2018). Validation of ionospheric specifications du...
Abstract. This paper provides the overview of an integrated, multi-disciplinary effort to study the effects of the 29 March 2006 total solar eclipse on the environment, with special focus on the atmosphere. The eclipse has been visible over the Eastern Mediterranean, and on this occasion several research and academic institutes organised co-ordinated experimental campaigns, at different distances from eclipse totality and at various environments in terms of air quality. Detailed results and findings are presented in a number of component scientific papers included in a Special Issue of Atmospheric Chemistry and Physics. The effects of the eclipse on meteorological parameters, though very clear, were shown to be controlled by local factors rather than the eclipse magnitudes, and the turbulence activity near surface was suppressed causing a decrease in the Planetary Boundary Layer. In addition to the above, the decrease in solar radiation has caused change to the photochemistry of the atmosphere, with night time chemistry dominating. The abrupt "switch off" of the sun, induced changes also in the ionosphere (140 up to 220 km) and the stratosphere. In the ionosphere, both photochemistry and dynamics resulted to changes in the reflection heights and the electron concentrations. Among the most important scientific findings from the experiments undertaken has been the experimental proof of eclipse induced thermal fluctuations in the ozone layer (Gravity Waves), due to the supersonic movement of the moon's shadow, for the first time with simultaneous measurements at three altitudes namely the troposphere, the stratosphere and the ionosphere.Correspondence to: E. Gerasopoulos (egera@meteo.noa.gr)Within the challenging topics of the experiments has been the investigation of eclipse impacts on ecosystems (field crops and marine plankton). The rare event of a total solar eclipse provided the opportunity to evaluate 1 dimensional (1-D) and three dimensional (3-D) radiative transfer (in the atmosphere and underwater), mesoscale meteorological, regional air quality and photochemical box models, against measurements.
[1] A method for mapping of ionospheric conditions over Europe, suitable to be used in real time for operational applications, is described in this paper. The method is based on the Simplified Ionospheric Regional Model (SIRM), a regional model of the standard vertical incidence monthly median ionospheric characteristics that has been updated with real-time (automatic scaled) ionospheric observations to produce nowcasting maps over Europe. As substantial fluctuations from a monthly median regional ionospheric description occur on day-to-day basis, the SIRM results oversimplified a number of the ionospheric phenomena of real significance for radio communications applications. Therefore a rapid conversion of real-time data from four European digisondes (Digital Portable Sounders) to the driving parameters of the Simplified Ionospheric Regional Model is introduced as the real-time SIRM updating (SIRMUP). In this approach, values of the ionospheric characteristics from first-guess model parameters at measurement points are combined with real-time measurements. To assess the qualitative improvements achieved with the real-time SIRM update method, observations of foF2 parameter with SIRMUP predictions were compared for various ionospheric conditions. The simulation shows that the SIRMUP prediction results are much improved comparing to SIRM predictions, especially during large-scale ionospheric disturbances, as well as during quiet conditions, while there was a marginal improvement during localized ionospheric disturbances. In general, the results clearly demonstrate that the proposed procedure of updating SIRM with automatic scaling ionospheric parameters from the four European digisondes has the potential to be used in real time for nowcasting the standard ionospheric characteristics over Europe for operational applications.
The paper describes results of the studies devoted to the solar activity impact on the Earth's upper atmosphere and ionosphere, conducted within the frame of COST ES0803 Action. Aim: The aim of the paper is to represent results coming from different research groups in a unified form, aligning their specific topics into the general context of the subject. Methods: The methods used in the paper are based on data-driven analysis. Specific databases are used for spectrum analysis, empirical modeling, electron density profile reconstruction, and forecasting techniques. Results: Results are grouped in three sections: Medium-and long-term ionospheric response to the changes in solar and geomagnetic activity, storm-time ionospheric response to the solar and geomagnetic forcing, and modeling and forecasting techniques. Section 1 contains five subsections with results on 27-day response of low-latitude ionosphere to solar extreme-ultraviolet (EUV) radiation, response to the recurrent geomagnetic storms, long-term trends in the upper atmosphere, latitudinal dependence of total electron content on EUV changes, and statistical analysis of ionospheric behavior during prolonged period of solar activity. Section 2 contains a study of ionospheric variations induced by recurrent CIR-driven storm, a case-study of polar cap absorption due to an intense CME, and a statistical study of geographic distribution of so-called E-layer dominated ionosphere. Section 3 comprises empirical models for describing and forecasting TEC, the F-layer critical frequency foF2, and the height of maximum plasma density. A study evaluates the usefulness of effective sunspot number in specifying the ionosphere state. An original method is presented, which retrieves the basic thermospheric parameters from ionospheric sounding data.
Abstract. The morphology of middle latitude ionospheric disturbances in response to geomagnetic storms has been investigated to determine the phenomenological differences between positive and negative ionospheric storm effects, using foF2 observations from azimuthal chain of stations. To better organize the disturbance signatures, two ionospheric indices were introduced to describe the maximum positive (Dfuindex) and negative (Dr-index) deviation observed during an ionospheric storm. A systematic appearance of nighttime positive effects was determined with a 24-hour recurrence.The thermospheric-ionospheric view associated with positive and negative storm effects proposed by Prolss (1993) was extended to encompass our observations. This test clearly demonstrates that such a model can capture most of the basic aspects of ionospheric storms, nevertheless the prominent feature of large nighttime enhancements in the ionization density have yet to be explained.
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