Progress in Observation‐Based Ionospheric Modeling

Models for the ionospheric component of space weather are needed for a wide range of applications. For example, any remote sensing techniques that use radio waves traveling through the ionosphere, looking up from the ground or down from space, must correct for the retarding, refractive, and scintillation effects of the ionospheric plasma. Two types of models are used for this purpose: theoretical, physics-based models and empirical, observation-based models. Status and progress regarding the latter were reviewed during a workshop in Prague, Czech Republic, from 10 to 14 July 2007. The workshop, entitled “Ionosphere—Modelling, Forcing and Telecommunications, “ was organized jointly by the prime international and European cooperatives in observationbased ionospheric modeling: IRI and COST/MIERS. IRI, the International Reference Ionosphere (http://iri.gsfc.nasa.gov/), a project of the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI), has the goal of developing and improving an international standard for the specification of ionospheric densities, temperatures, and velocities. COST/MIERS, the European Cooperation in the Field of Scientific and Technical Research project for the Mitigation of Ionospheric Effects on Radio Systems (http:// www.cost296.rl.ac.uk), is a 5-year Europe-wide effort to improve data-based models for the European sector with special emphasis on Global Navigation Satellite System (GNSS) and telecommunications applications. The IRI model is currently undergoing registration with the International Organization for Standardization (ISO) as a technical specification (TS16457), and it is the ionospheric model recommended by the European Cooperation for Space Standardization (ECCS). Annual IRI meetings are the prime forum for discussions of model shortcomings, improvements, new model additions, applications, and other IRI-related topics. For its 2007 workshop, the IRI team joined forces with the European COST 296 project, which deals with similar modeling and application issues but is confined primarily to the European sector. The workshop was locally organized by the Czech Republic’s Institute of Atmospheric Physics and attracted 103 scientists from 27 countries from North and South America, Europe, Asia, and Africa. The meeting was financially supported by COSPAR, URSI, the International Association of Geomagnetism and Aeronomy (IAGA), the European Office of Aerospace Research and Development (EOARD) of the U.S. Air Force, the U.S. Office of Naval Research (ONR), and the Czech Academy of Sciences. Workshop presentations were grouped into sessions on ionospheric effects on radio systems, Global Positioning Systems (GPS) and total electron content (TEC), modeling of the topside and bottomside ionosphere, ionospheric storm effects, ionospheric sounding, and mapping the ionospheric F region. Closing sessions included a summary discussion and a management meeting for COST 296. All presentations are available on the workshop Web site at http://www.ufa. cas.cz/ html/conferences/IRICOST2007/. Papers and posters from the meeting will be considered for a special issue of COSPAR’s Advances in Space Research. The F layer, which extends from roughly 150 to 600 kilometer altitude, contains the F peak, typically at an altitude between 300 and 500 kilometers. The F peak is of special importance because it monitors the point of highest electron density and therefore the point of strongest impact on transionospheric radio waves. Increased accuracy of models for the F peak parameters is an important goal of both IRI and COST. COST is primarily focused on the European sector, while IRI deals with the whole globe. The International Radio Consultative Committee (CCIR) and URSI models for these parameters, often at the core of operational ionospheric models, date from the late 1960s and mid-1980s, respectively, and are urgently in need of an update. Several new modeling approaches were presented at this meeting, including neural networks (NN), genetic algorithms, eigenmode analysis, and others. The most advanced and prime candidates for inclusion in a future version of IRI are the NN peak models developed by Lee-Anne McKinnell and colleagues (Rhodes University, Grahamstown, South Africa) based on a large volume