천문우주과학과

일시:  2019년 10월 22일 목요일 세미나실(기2514호)

연사:  Dieter Bilitza 박사님(George Mason University, NASA GSFC)

제목: IRI the International Standard for the Ionosphere

초록:  

 This presentation will give an overview of the International Reference Ionosphere (IRI) project and model. IRI is recognized as the official standard for the ionosphere by the International Standardization Organization (ISO), the International Union of Radio Science (URSI), the Committee on Space Research (COSPAR), and the European Cooperation for Space Standardization (ECCS). I will briefly review the history of the IRI project, its current status and report on some of the future plans for this project that is jointly sponsored by URSI and COSPAR. The presentation will introduce the latest version of the model (IRI-2016; Bilitza et al., Space Weather, 15, 418–429, doi:10.1002/2016SW0015932017) and discuss some of its successes and areas were future improvement are needed. Of special importance is a better description of IRI densities and temperatures at very low solar activities in view of the discrepancies found during the last unusually low and extended solar minimum (2007-2009) and because the current solar cycle may reach again very low solar activities. The topside electron density, in particular, has been shown to be overestimated by IRI in comparisons with C/NOFS, CHAMP, and GRACE satellite measurements. High priority is also given to the better use of solar ionosphere-effective indices or potentially the development of new ones. This is of particular urgency because of the recent revision of the sunspot number index that was the index of choice for many of the older sub-models used in IRI. We will discuss potential solutions to this problem and short-term fixes currently applied in IRI. The extension into the plasmasphere is another area where more work and data are needed to come up with a standard model. An exciting new direction is the development of the Real-Time IRI based on an assimilation of real-time data into the IRI background model. For example, the effort of Galkin et al. (2012) using worldwide digisonde data from the Global Ionospheric Radio Observatory (GIRO) network. Other data sources of interest for assimilation into the Real-Time IRI are data from the Global Navigation Satellite Systems (GNSS). I will end with a discussion of validation and usage of the IRI model.