International Reference Ionosphere (IRI) 2013 Workshop

Meeting Report, Dieter Bilitza

The 2013 Workshop of the International Reference Ionosphere (IRI) project was held at the University of Mazury and Warmia in Olsztyn, Poland from June 24 to 28. IRI is a joint undertaking by the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) with the goal of developing and improving an international standard for the parameters in Earth’s ionosphere. This endeavor was originally triggered by the need for an ionosphere model for the satellite/experiment design and satellite data analysis (COSPAR) and for radio propagation studies (URSI) but has meanwhile found a much broader range of users with space weather concerns. As requested by these international unions IRI was built as an empirical model representing the syntheses of all (or most) of the available ground and space measurements of ionospheric characteristics. IRI workshops bring together scientists from different countries representing different measurement and modeling techniques with the goal of improving the IRI model in a collaborative effort. This was again nicely illustrated by the brought spectrum of participants attending the 2013 Workshop and the main collaborative studies presented during the week-long meeting. The meeting was attended by close to 70 scientists representing 20 countries (Poland, USA, South Africa, Nigeria, Zambia, Uganda, Russia, China, Taiwan, Spain, Czech Republic, Italy, Turkey, Japan, Thailand, Sweden, Belgium, Argentina, Ukraine, Malaysia) and presenting 56 oral and 20 poster presentations. The meeting was divided into 9 sessions dealing with “Improvement if IRI with GNSS Data”, “Real-Time IRI and the Representation of Storm Effects”, “GNSS Monitoring of Ionosphere (TEC, Fluctuation and Scintillation)”, “Modeling of the High-Latitude Ionosphere”, “New Inputs for IRI”, “Mapping of Ionospheric Peak Parameters”, “The Ionosphere and IRI During the Recent Solar Cycle”, “IRI Applications”, and “Posters”. Prof. Andrzej Krankowski and his Local Organizing Committee worked around the clock and did a splendid job in hosting and organizing the workshop. The IRI team gratefully acknowledges financial support received for the meeting from COSPAR, URSI, the University of Warmia and Mazury, Leica Geosystems Poland, the National Space Organization (NSPO) in Taiwan, and INS Ltd. Poland.

Scientific Results and Future Plans

In line with the main topic of the workshop many of the presentations involved GNSS measurements. TEC comparisons with IRI (Oyeyemi et al., Nigeria; Bhoo Pathy et al., Malaysia; Wang et al., China; Habarulema et al., South Africa) showed generally good to fair agreement with shortcomings in describing solar cycle changes and variations at dawn and dusk. Tomographic and other techniques are being used to obtain the electron density profile and foF2 from GNSS measurements (Sessanga and McKinnell, South Africa; Sibanda et al., Zambia). Combining different GNSS data sets Zakharenkova et al. (WestIZMIRAN, Russia) are able to deduce information about the variability of the ionosphere and plasmasphere parts of the TEC. Krankowski (UMW, Poland) reviewed the activities of the IGS IONO group and highlighted their new plans for higher time resolution (from now 2 hours to 15 min) and additional products like the irregularity index ROTI. Other GNSS services and products reviewed during this meeting included the IONOLAB-TEC (Arikan et al., Turkey), gAGE/UPC (Garcia-Rigo et al., Spain), DRAWING-TEC (Tsugawa et al., Japan), NICT products (Ishii et al., Japan), and COSMIC products and research (Liu et al., Taiwan). The ingest of TEC data into IRI was discussed by Migoya-Orue et al. (ICTP, Italy).

In the topside IRI modeling is progressing with promising new results for the Vary-Chap approach for the electron density presented by Reinisch et al. (LDI-UML, EDU). Of benefit will also be the study of Verhulst and Stankov (Belgium) that showed that for optimal results different mathematical functions should be used for different conditions. Truhlik et al. (IAP, Czech Republic) improved the IRI topside ion composition model by including a more accurate description of solar activity variations. Watanabe et al. (U. Hokkaido, Japan) used satellite in situ data to study the correlation between electron temperature and density in the F-region and topside with the goal of including this relationship in IRI. IRI currently includes three options for the topside density (NeQuick, IRI-2001corr, and IRI-2001). As a fourth option the topside model of Gulyaeva (IZMIRAN, Russia) will be added in the next IRI release. This model uses the half-F-peak-density (0.5*NmF2) height h0.5 as anchor point for an extension of IRI to the plasmasphere and was developed with ISIS and Alouette topside sounder data.

There are exciting new developments regarding the representation of the F-peak height, hmF2, in IRI. So fare IRI has relied on the anti-correlation between hmF2 and the propagation factor M(3000)F2 and the CCIR models for this factor. This is because M(3000)F2 is easily obtainable from ionograms while a much more involved analysis is required for getting hmF2. This modeling approach did well in reproducing the average global and temporal variation patterns but did not succeed in describing short period variations like the evening peak at equatorial latitudes. It was also found that this formalism produced too high hmF2 values during the past solar minimum indicating a breakdown of the simple anti-correlation between the two parameters. Three groups are involved in developing models directly for hmF2. Altadill et al. (Ebro, Spain) use a spherical harmonics representation of hmF2 data from a set of globally distributed ionosonde stations. The model of Gulyaeva et al. (IZMIRAN, Russia) is based on Alouette and ISIS topside sounder data and uses the correlation between hmF2 and NmF2. Karpachev et al. (SibIZMIRAN, Russia) base their model on carefully selected COSMIC radio occultation data. It is planned to include these models as different options in IRI.

Two efforts are underway to provide IRI users with more information than just the monthly averages as they are given now: (1) A quantitative description of the monthly average of ionospheric variability and (2) the real-time IRI based on assimilating real-time data into IRI. A description of the standard deviation from the monthly mean has long been a goal and progress made during several IRI Task Force Activity meetings at the International Centre for Theoretical Physics (ICTP, Radicella) is now being picked up by the Argentinian Network for Atmospheric Research (RAPEAS) project. First results were presented at this meeting. Bilitza et al. (GMU, USA) studying topside sounder data found that ionospheric relative variability reaches a maximum in the topside (500 to 700 km). Mosert et al. (CONICET, Argentina) presented a first table of representative values for the foF2 variability based on global ionosonde measurements. Good progress is being made in producing a real-time IRI. The IRI Real-Time Assimilative Mapping (IRTAM) of foF2 by Galkin et al. (UML, USA) updates the CCIR spherical harmonics maps with global data from the Global Ionospheric Radio Observatory (GIRO) network of digisondes. They also discussed the use of IRTAM for studying the effects of Sudden Stratospheric Warmings on the ionosphere. Altadill et al. (Ebro, Spain) presented a prediction of hmF2 storm-time changes based on IMF Bz measurements by the ACE satellite.

Publications, Meetings, and New Members

The refereed and accepted papers from the 2010 COSPAR session on the “Representation of the Auroral and Polar Ionosphere in IRI” were published in a dedicated issue of Advances in Space Research (Volume 51, Issue 4, 15 February 2013) with D. Bilitza and B. Reinisch as guest editors. Editing is in the final stages for a special Advances in Space Research issue with papers from the 2011 IRI workshop that was held in Hermanus, South Africa and that was focused on Improvements of IRI over the African Region. The 14 papers finally accepted for this issue give a good overview over ionospheric activities on the African Continent.

The year 2014 will see several meetings of interest to the IRI team and community. Considerable progress is expected with regard to the development of the Real-Time IRI through two meetings organized by the IRI team in 2014. A 1-day session during the Digisonde/GIRO Forum in Lowell, USA, May 19-21 (which is following the Ionospheric Effects Symposium held in Alexandria near Washington, DC) and a session entitled “Improved Representation of the Ionosphere in Real Time and Retrospective Mode” during the COSPAR Scientific Assembly in Moscow, Russia, August 2-10, 2014. The URSI General Assembly will be held in Beijing, China, August 16-23, 2014 and will include a session on “Ionosphere and Plasmasphere Electron Density Profiles” with L.-A. McKinnell as the main organizer. For the 2015 IRI Workshop the IRI Working Group accepted an invitation by Prof. Pornchai Supnithi to host the meeting in Bangkok, Thailand. The meeting focus will be on scintillations and spread-F.

Irina Zkharenkova (Russia) was elected as a new member of the IRI team. Irina is a researcher from the West Department of IZMIRAN in Kaliningrad, Russia, who is currently working at the Geodynamics Research Laboratory of the University of Warmia and Mazury in Olsztyn, Poland. Irina has made important contributions to determining the plasmaspheric electron content (PEC) from GNSS measurements and to studying the variability of the PEC. As a member of the Local Organizing Committee for the 2013 IRI Workshop she helped to make this a very successful and productive meeting.