Total Electron Content Observations by Dense Regional and Worldwide International Networks of GNSS
Takuya Tsugawa*1,†, Michi Nishioka*1, Mamoru Ishii*1, Kornyanat Hozumi*1, Susumu Saito*2, Atsuki Shinbori*3, Yuichi Otsuka*3, Akinori Saito*4, Suhaila M. Buhari*5, Mardina Abdullah*6, and Pornchai Supnithi*7
*1Applied Electromagnetic Research Institute, National Institute of Information and Communications Technology
4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan
*2Electronic Navigation Research Institute, National Institute of Maritime, Port, and Aviation Technology, Tokyo, Japan
*3Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
*4Graduate School of Science, Kyoto University, Kyoto, Japan
*5Geomatic Information Research Group, Faculty of Science, Universiti Teknologi Malaysia, Johor, Malaysia
*6Space Science Centre (ANGKASA) & Department of Electrical, Electronic & Systems Engineering, Universiti Kebangsaan Malaysia, Selangor, Malaysia
*7Telecommunications Engineering Department, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, Thailand
Two-dimensional ionospheric total electron content (TEC) maps have been derived from ground-based Global Navigation Satellite System (GNSS) receiver networks and applied to studies of various ionospheric disturbances since the mid-1990s. For the purpose of monitoring and researching ionospheric conditions and ionospheric space weather phenomena, we have developed TEC maps of areas over Japan using the dense GNSS network, GNSS Earth Observation NETwork (GEONET), which consists of about 1300 stations and is operated by the Geospatial Information Authority of Japan (GSI). Currently, we are providing high-resolution, two-dimensional maps of absolute TEC, detrended TEC, rate of TEC change index (ROTI), and loss-of-lock on GPS signal over Japan on a real-time basis. Such high-resolution TEC maps using dense GNSS receiver networks are one of the most effective ways to observe, on a scale of several 100 km to 1000 km, ionospheric variations caused by traveling ionospheric disturbances and/or equatorial plasma bubbles, which can degrade single-frequency and differential GNSS positioning/navigation. We have collected all the available GNSS receiver data in the world to expand the TEC observation area. Currently, however, dense GNSS receiver networks are available in only limited areas, such as Japan, North America, and Europe. To expand the two-dimensional TEC observation with high resolution, we have conducted the Dense Regional and Worldwide International GNSS TEC observation (DRAWING-TEC) project, which is engaged in three activities: (1) standardizing GNSS-TEC data, (2) developing a new high-resolution TEC mapping technique, and (3) sharing the standardized TEC data or the information of GNSS receiver network. We have developed a new standardized TEC format, GNSS-TEC EXchange (GTEX), which is included in the Formatted Tables of ITU-R SG 3 Databanks related to Recommendation ITU-R P.311. Sharing the GTEX TEC data would be easier than sharing the GPS/GNSS data among those in the international ionospheric researcher community. The DRAWING-TEC project would promote studies of medium-scale ionospheric variations and their effect on GNSS.
-  M. Hernández-Pajares, J. M. Juan, J. Sanz, R. Orus, A. Garcia-Rigo, J. Feltens, A. Komjathy, S. C. Schaer, and A. Krankowski, “The IGS VTEC maps: a reliable source of ionospheric information since 1998,” J. of Geod., Vol.83, pp. 263-275, doi:10.1007/s00190-008-0266-1, 2009.
-  Y. Otsuka, T. Ogawa, A. Saito, T. Tsugawa, S. Fukao, and S. Miyazaki, “A New technique for mapping of total electron content using GPS network in Japan,” Earth Planets and Space, Vol.54, pp. 63-70, 2002.
-  A. Saito, S. Fukao, and S. Miyazaki, “High resolution mapping of TEC perturbations with the GSI GPS network over Japan,” Geophys. Res. Lett., Vol.25, pp. 3079-3082, 1998.
-  T. Tsugawa, N. Kotake, Y. Otsuka, and A. Saito, “Medium-scale traveling ionospheric disturbances observed by GPS receiver network in Japan: a short review,” GPS Solut, Vol.11, pp. 39-144, doi:10.1007/s10291-006-0045-5, 2007.
-  G. Ma and T. Maruyama, “A super bubble detected by dense GPS network at east Asian longitudes,” Geophys. Res. Lett., Vol.33, L21103, doi:10.1029/2006GL027512, 2006.
-  T. L. Beach and P. M. Kintner, “Simultaneous Global Positioning System observations of equatorial scintillations and total electron content fluctuations,” J. of Geophys. Res., Vol.104, Issue A10, pp. 22553-22565, 1999.
-  M. Nishioka, A. Saito, and T. Tsugawa, “Occurrence characteristics of plasma bubble derived from global groundbased GPS receiver networks,” J. of Geophys. Res., Vol.113, A05301, doi:10.1029/2007JA012605, 2008.
-  B. G. Fejer and M. C. Kelley, “Ionospheric irregularities,” Rev. of Geophys., Vol.18, pp. 401-454, 1980.
-  S. M. Buhari, M. Abdullah, T. Yokoyama, Y. Otsuka, M. Nishioka, A. M. Hasbi, S. A. Bahari, and T. Tsugawa, “Climatology of successive equatorial plasma bubbles observed by GPS ROTI over Malaysia,” J. of Geophys. Res.: Space Physics, Vol.122, doi:10.1002/2016JA023202, 2017.
-  T. Tsugawa, A. Saito, Y. Otsuka, M. Nishioka, T. Maruyama, H. Kato, T. Nagatsuma, and K. T. Murata, “Ionospheric disturbances detected by GPS total electron content observation after the 2011 off the Pacific coast of Tohoku Earthquake,” Earth Planets and Space, Vol.63, pp. 875-879, 2011.
-  U. S. Geological Survey, http://earthquake.usgs.gov/ [accessed March 14, 2011]
-  Y. Fujii, K. Satake, S. Sakai, M. Shinohara, and T. Kanazawa, “Tsunami source of the 2011 off the Pacific coast of Tohoku Earthquake,” Earth Planets and Space, Vol.63, pp. 815-820, 2011.
-  Japan Meteorological Agency, http://www.jma.go.jp/ [accessed November 27, 2017]
-  T. Tsugawa, Y. Otsuka, A. J. Coster, and A. Saito, “Medium-scale traveling ionospheric disturbances detected with dense and wide TEC maps over North America,” Geophys. Res. Lett., Vol.34, L22101, doi:10.1029/2007GL031663, 2007.
-  Y. Otsuka, K. Suzuki, S. Nakagawa, M. Nishioka, K. Shiokawa, and T. Tsugawa, “GPS Observations of Medium-Scale Traveling Ionospheric Disturbances over Europe,” Annales Geophysicae, Vol.31, pp. 163-172, doi:10.5194/angeo-31-163-2013, 2013.
-  M. Nishioka, T. Tsugawa, M. Kubota, and M. Ishii, “Concentric waves and short-period oscillations observed in the ionosphere after the 2013 Moore EF5 tornado,” Geophys. Res. Lett., Vol.40, pp. 5581-5586, doi:10.1002/2013GL057963, 2013.
-  C. O. Hines, “Internal atmospheric gravity waves at ionospheric heights,” Can. J. of Phys., Vol.38, pp. 1441-1481, 1960.
-  Y. Otsuka, F. Onoma, K. Shiokawa, T. Ogawa, M. Yamamoto, and S. Fukao, “Simultaneous observations of nighttime medium-scale traveling ionospheric disturbances and E-region field-aligned irregularities at midlatitude,” J. of Geophys. Res., Vol.112, A06317, doi:10.1029/2005JA011548, 2007.
-  T. Yokoyama and D. L. Hysell, “A new midlatitude ionosphere electrodynamics coupling model (MIECO): latitudinal dependence and propagation of mediumscale traveling ionospheric disturbances,” Geophys. Res. Lett., Vol.37, L08105, doi:10.1029/2010GL042598, 2010.
-  Recommendation ITU-R P.311-16, ITU-R, 2016.
-  S. Saito, S. Sunda, J. Lee, S. Pullen, S. Supriadi, T. Yoshihara, M. Terkildsen, F. Lecat, and ICAO APAPPIRG Ionospheric Studies Task Force, “Ionospheric delay gradient model for GBAS in the Asia-Pacific region,” GPS Solut., Vol.21, pp. 1937-1947, doi:10.1007/s/10291-017-0662-1, 2017.
-  AOSWA, http://aoswa.nict.go.jp/ [accessed November 27, 2017]
-  S. M. Buhari, M. Abdullah, A. M. Hasbi, Y. Otsuka, T. Yokoyama, M. Nishioka, and T. Tsugawa, “Continuous generation and two-dimensional structure of equatorial plasma bubbles observed by high-density GPS receivers in Southeast Asia,” J. of Geophys. Res.: Space Physics, Vol.119, doi:10.1002/2014JA020433, 2014.
-  K. Watthanasangmechai, M. Yamamoto, A. Saito, R. Tsunoda, T. Yokoyama, P. Supnithi, M. Ishii, and C. Yatini, “Predawn plasma bubble cluster observed in Southeast Asia,” J. of Geophys. Res.: Space Physics, Vol.121, pp. 5868-5879, doi:10.1002/2015JA022069, 2016.
-  Real-Time NOWPHAS, http://www.mlit.go.jp/kowan/nowphas/index_eng.html [accessed November 27, 2017]
-  T. Kato, et al., J. Disaster Res. in this volume, 2018.
This article is published under a Creative Commons Attribution-NoDerivatives 4.0 Internationa License.