IWAC2022 Program & Abstracts
Day 3 (Thursday, 27 October) 14:30 - 16:30, Hall C

Technical Session 13

Space Weather

T13-1-A
Anomalous Long-range Propagation of VHF NAV signals by the sporadic E

Keisuke Hosokawa (University of Electro-Communications), Susumu Saito (Electric Navigation ResearchInstitute, MPAT), Shumpei Tabuchi, Jun Sakai, Ichiro Tomizawa (University of Electro-Communications),
Michi Nishioka, Takuya Tsugawa, Mamoru Ishii (National Institute of Information and Communications
Technology)
The sporadic E (Es) layer is a layer in the ionospheric E region with a dense electron density and thin altitudinalthickness at altitudes around 100 km. It has been pointed out by International Civil Aviation Organization (ICAO) that
the Es layer has a potential to introduce anomalous long-range propagation in the frequency band of aeronauticalnavigation and communication (EsAP: Es Anomalous Propagation). In order to reveal the detailed characteristics ofEsAP, we have constructed a network of instruments for continuously monitoring the intensities of radio waves ofvarious VOR and ILS LOC stations in Japan. In this paper, we introduce the following latest results obtained using datafrom this monitoring observation: 1) derivation of statistical characteristics (seasonal/local time dependence) of EsAP
occurrence probability, 2) mapping of the spatial structure of Es in 2D by combining EsAP observations with GPS-TEC
ROTI data, and 3) detailed investigation of the long-range propagation of ILS-LOC signal from Taiwan. We also discuss
the possibility for using the anomalous propagation of VHF NAV signal for studies of equatorial plasma bubbles, adifferent phenomenon in the ionospheric F region.

T13-2-I
DFMC GBAS testbed at Ishigaki, Japan

Susumu Saito, Takayuki Yoshihara (Electronic Navigation Research Institute, , MPAT)
This paper introduces the dual-frequency and multi-frequency (DFMC) ground-based augmentation system (GBAS)
testbed developed by the Electronic Navigation Research Institute and installed at the New Ishigaki Airport. The testbed
can receive most of the signals of all the major GNSS constellations. It can generate two kinds of GBAS messages
corresponding to the two architectures proposed. The first data collection campaign was conducted from 8 to 10
March 2022. More flight campaigns are planned in October 2022 and March 2023.

T13-3-I
Recent domestic activities and NICT’s efforts toward the advancement of space weather
forecast
Takuya Tsugawa (National Institute of Information and Communications Technology)

In recent years, the use of space has been rapidly advancing in the business sector, such as precise GNSS navigation,commercial small satellite constellations, and commercial space travel, while solar activity has been gradually increasing,with the first X-class solar flare in Solar Cycle 25 occurring in July 2021. Under these cir-cumstances, various countries
and international organizations have been studying the impact of space weather phenomena on social infrastructureand how to respond to them. The Ministry of Internal Affairs and Commu-nications (MIC) "Council for the advancementof space weather forecast" has been held in Japan since January 2022, and its report was released in June. The WG on
space weather alert criteria, which was established under the council, has been discussing new alert types and criteria,
and the first Japanese worst-case scenario of ex-treme space weather phenomena”. In this presentation, an overview ofthis report and related efforts by NICT will be reported.

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