C4.1 Global and Regional Representation of Ionospheric Peak parameters for Space Weather Applications

 

Report, Dieter Bilitza

 

The session on “Global and Regional Representation of Ionospheric Peak parameters for Space Weather Applications” was held during the 39th COSPAR Scientific Assembly that took place in Mysore, India from July 14 to 22, 2012. It was organized by the COSPAR/URSI Working Group on the International Reference Ionosphere and was held on Sunday and Monday of the conference week. The session was divided into 6 subsections entitled: Topside and TEC in IRI, F Peak Modeling, Variation during Ionospheric Storms, Representing Solar Minimum Conditions, Improving IRI, and New Inputs for IRI. The session was well attended (40-60) and consisted of 27 talks and two posters with presenters from Austria, Czech Republic, India, Iran, Italy, Japan, Poland, Russia, South Africa, Uganda, Ukraine, and USA.  A business meeting of the IRI Working Group was held on the day after the session and was attended by 18 participants.

 

Topside and TEC

 

Work continues on the Vary-Chap model for the topside electron density profile. Latest results were presented by Reinisch et al. (U Mass Lowell, USA) based on ISIS topside sounder data. Several papers presented comparisons of IRI-TEC predictions with GPS-TEC measurements from the Indian subcontinent. Of special interest are the comparative studies in the equatorial anomaly region which found good agreement with the exception of the sunrise time period (Surat station: Karia et al., S V National Institute of Technology; Palehua station: Devi et al., Mar Thoma College, Kerala). A study with Korean GPS-TEC data showed that the winter anomaly appears in the GPS TEC only during the solar maximum period, in contrast to the IRI estimations in which it shows up regardless of the solar activity. Kakinami et al. (Hokkaido University, Japan) constructed empirical models of the topside electron density and temperature measurements by the DEMETER satellite. But they also point out that DEMETER densities are systematically lower and temperatures higher than measurements by other satellites and also than IRI predictions and recommend using relative variations instead of absolute values. Truhlik et al. (Institute of Atmospheric Physics, Czech Republic) discussed ways to improve the current IRI ion composition and electron temperature models in the topside ionosphere based on newer data and with special regard to low solar activity and to the extension to  the plasmasphere.

 

F Peak Parameters

Ratovsky et al. (Institute of Solar-Terrestrial Physics, Irkutsk, Russia) presented local empirical models for the peak parameters foF2 and hmF2 based on validated ionogram data recorded by Digisondes in Norilsk, Irkutsk, and Hainan (China). Nagatsuma et al. (National Institute of Information and Communications Technology, Japan) described the status and data of the NICT network of ionosondes (Wakkanai, Kokubunji, Yamagawa, Okinawa and the South-East Asia Low-Latitude IOnospheric Network, SEALION). These data extending from low to middle latitudes with a multi-year data record are a valuable data source for improvements of the F peak models for IRI. Ionospheric behavior during storm recovery phase was discussed by Buresova et al. (Institute of Atmospheric Physics, Czech Republic) and compared with the predictions by IRI and other models pointing to significant deficiencies particularly for the peak height hmF2. McKinnell et al. (South Africa National Space Agency, South Africa) reported on the continued efforts by her group on the planned inclusion of their NeuralNetwork models for the F peak parameters in IRI. COSMIC and GPS data were used by Irina Zakharenkova (IZMIRAN, Kaliningrad, Russia) to study the global variations of the F peak parameters and the plasmaspheric electron content with special emphasis on time periods and regions where shortcomings of the IRI model are found. The performance of the IRI model during the recent highly unusual solar minimum was discussed in several presentations during this session. Araujo-Pradere et al. (University of Colorado, USA; presented by Fuller-Rowell) showed that IRI overestimated the F peak density and height as well as the TEC during this very low and extended minimum. Bilitza et al. (George Mason University, USA) presented comparisons with ionosonde and C/NOFS measurements and investigated the possible causes and remedies for the overestimation by IRI.

 

General

 

The IRI Working Group submitted a proposal for a session during the 2014 COSPAR General Assembly in Moscow, Russia entitled “Improved representation of the ionosphere in real-time and retrospective mode”. The 2013 IRI Workshop will be held at the University of Warmia and Mazury in Olzstyn, Poland from June 24 to 28. The Main Organizer is Andrzej Krankowski and the special topic will be GNSS inputs for IRI.  Selected papers from the 2009 IRI Workshop in Kagoshima, Japan have been published in two dedicated issues of Earth, Planets, and Space. Papers from the 2010 IRI session during the COSPAR General Assembly in Bremen, Germany will soon be published in a special issue of Advances in Space Research. Another special IRI issue of ASR with papers from the 2011 IRI Workshop in Hermnaus, South Africa is now in the reviewing stage.

 

The IRI business meeting on July 17 was attended by 15 Participants. Several improvements to the IRI model were discussed based on the presentations at this meeting and prior workshops. A primary focus is the height of the F peak, hmF2, which in IRI is represented through its relationship to the propagation factor M(3000)F2. New models were proposed by Altadill et al. (Ebro, Spain) and by Gulyaeva et al. (IZMIRAN, Russia) and will be included as new options in the next version of IRI-2012. It was also found that the current hmF2-M(3000)F2 model predict unrealistically low values during the extreme 2008/2009 solar minimum, because data for such conditions were not available when the model was developed.  Efforts are underway to improve the model for very low solar activities. It was also pointed out that ITU and HF users of IRI are still very interested in a representation of not only hmF2 but also M(3000)F2 because it can be directly applied to some of their applications. John Bosco Habarulema (Uganda) was proposed and accepted as a new member for the IRI Working Group. He has worked extensively on TEC and IRI related research and was one of the organizers of the 2011 IRI Workshop in Hermanus and is co-editor of the ASR issue with papers from the Hermanus meeting. His main field of interest is in improving the predictability of TEC using neural networks under all conditions, and as this is of increasing interest to the IRI group will bring this expertise to the group. There are no plans for a dedicated issue with papers from this meeting. Papers can be either submitted as standard ASR papers or can be considered for our next special issue, which is planned for the papers from the 2013 IRI Workshop. This Workshop will be held at the University of Warmia and Mazury in Olsztyn, Poland from June 24 to 28, 2013 (MSO: Andrzej Krankowski). The IRI homepage is at http://IRI.gsfc.nasa.gov/ .