Bilitza, D.: International Reference Ionosphere 2000, Radio Sci., 36,
261–275, https://doi.org/10.1029/2000RS002432, 2001.
Bilitza, D.: The International Reference Ionosphere-Status 2013, Adv. Space
Res., 5, 1914–1927, https://doi.org/10.1016/j.asr.2014.07.032,
2015.
Bilitza, D. and Reinisch, B. W.: International Reference Ionosphere 2007:
Improvements and new parameters, Adv. Space Res., 42, 599–609,
https://doi.org/10.1016/j.asr.2007.07.048, 2008.
Bilitza, D., Watanabe, S., Truhlik, V., and Altadill, D.: IRI-2016:
Description and Introduction, 41st COSPAR Scientific
Assembly, July, Istanbul, Turkey, 2016.
Bilitza, D., Altadill, D., Truhlik, V., Shubin, V., Galkin, I., Reinisch,
B., and Huang, X.: International Reference Ionosphere 2016: from ionospheric
climate to real-time weather predictions, Space Weather, 15, 418–429, 2017.
Bouya, Z., Terkildsen, M., Francis, M., and Neudegg, D.: EOF Analysis
applied to Australian Regional Ionospheric TEC modelling, AOSWA, 22–24 February 2012, Chiang Mai, Thailand, 2012.
CCMC: Solar activity data, available at:
https://omniweb.gsfc.nasa.gov/, last access: 21 April 2019.
CDDIS: GIM-TEC data, available at:
ftp://cddis.gsfc.nasa.gov/, last
access: 10 April 2019.
COSPAR and URSI: Fortran source code of IRI-2016, available at:
http://irimodel.org/, last access: 12 March 2019.
Chang, X., Zou, B., Guo, J., Zhu, G., Li, W., and Li, W.: One sliding PCA
method to detect ionospheric anomalies before strong Earthquakes: Cases
study of Qinghai, Honshu, Hotan and Nepal earthquakes, Adv. Space Res., 59,
2058–2070, https://doi.org/10.1016/j.asr.2017.02.007, 2017.
Chauhan, V. and Singh, O. P.: A morphological study of GPS-TEC data at Agra
and their comparison with the IRI model, Adv. Space Res., 46, 280–290,
https://doi.org/10.1016/j.asr.2010.03.018, 2010.
Dabbakuti, J. R. K. K. and Ratnam, D. V.: Characterization of ionospheric
variability in TEC using EOF and wavelets over low-latitude GNSS stations,
Adv. Space Res., 57, 2427–2443, https://doi.org/10.1016/j.asr.2016.03.029,
2016.
Dabbakuti, J. R. K. K. and Ratnam, D. V.: Modeling and analysis of GPS-TEC
low latitude climatology during the 24th solar cycle using empirical
orthogonal functions, Adv. Space Res., 60, 1751–1764, https://doi.org/10.1016/j.asr.2017.06.048, 2017.
Feltens, J., Angling, M., Jackson-Booth, N., Jakowski, N., Hoque, M.,
HernándezPajares, M., Aragón, Á., María, Á., and
Orús-Pérez, R.: Comparative testing of four ionospheric models
driven with GPS measurements, Radio Sci., 46, RS0D12,
https://doi.org/10.1029/2010RS004584, 2011.
Jiang, H., Liu, J., Wang, Z., An, J., Ou, J., Liu, S., and Wang, N.:
Assessment of spatial and temporal TEC variations derived from ionospheric
models over the polar regions, J. Geodesy, 93, 455–471,
https://doi.org/10.1007/s00190-018-1175-6, 2019.
Kenpankho, P., Supnithi, P., and Nagatsuma, T.: Comparison of observed TEC
values with IRI-2007 TEC and IRI-2007 TEC with optional
foF2 measurements
predictions at an equatorial region, Chumphon, Thailand, Adv. Space Res.,
52, 1820–1826, https://doi.org/10.1016/j.asr.2013.08.012, 2013.
Li, S., Li, L., and Peng, J.: Variability of Ionospheric TEC and the
Performance of the IRI-2012 Model at the BJFS Station, China, Acta Geophys.,
64, 1970–1987, 2016.
Li, S., Zhou, H., Xu, J., Wang, Z., Li, L., and Zheng, Y.: Modeling and
analysis of ionosphere TEC over China and adjacent areas based on EOF
method, Adv. Space Res., 64, 400–414, https://doi.org/10.1016/j.asr.2019.04.018, 2019.
Maltseva, O. A., Mozhaeva, N. S., Poltavsky, O. S., and Zhbankov, G. A.: Use
of TEC global maps and the IRI model to study ionospheric response to
geomagnetic disturbances, Adv. Space Res., 49, 1076–1087,
https://doi.org/10.1016/j.asr.2012.01.005, 2012.
Mao, T., Wan, W., Yue, X., Sun, L., Zhao, B., and Guo, J.: An empirical
orthogonal function model of total electron content over China, Radio Sci.,
43, RS2009, https://doi.org/10.1029/2007RS003629, 2008.
Okoh, D., McKinnell, L., Cilliers, P., and Okeke, P.: Using GPS-TEC data to
calibrate VTEC computed with the IRI model over Nigeria, Adv. Space Res.,
52, 1791–1797, https://doi.org/10.1016/j.asr.2012.11.013, 2013.
Pearson, K.: On lines and planes of closest fit to systems of points in
space, Philos. Mag., 2, 559–572, 1901.
Rawer, K., Ramakrishnan, S., and Bilitza, D.: International Reference
Ionosphere 1978. International Union of Radio Science, URSI Special Report,
75 pp., Bruxelles, Belgium, 1978.
Scidá, L. A., Ezquer, R. G., Cabrera, M. A., Mosert, M., Brunini, C.,
and Buresova, D.: On the IRI 2007 performance as a TEC predictor for the
South American sector, J. Atmos. Sol.-Terr. Phy., 81–82, 50–58,
https://doi.org/10.1016/j.jastp.2012.04.001, 2012.
Sharma, S. K., Ansari, K., and Panda, S. K.: Analysis of Ionospheric TEC
Variation over Manama, Bahrain, and Comparison with IRI-2012 and IRI-2016
Models, Arab. J. Sci. Eng., 43, 3823–3830, 2018.
Shreedevi, P. R., Choudhary, R. K., Yadav, S., Thampi, S., and Ajesh,
A.: Variation of the TEC at a dip equatorial station, Trivandrum and a mid
latitude station, Hanle during the descending phase of the solar cycle
24 (2014–2016), J. Atmos. Sol.-Terr. Phy., 179, 425–434, 2018.
Shubin, V. N.: Global median model of the F2-layer peak height based on
ionospheric radio-occultation and ground-based Digisonde observations, Adv.
Space Res., 56, 916–928, https://doi.org/10.1016/j.asr.2015.05.029, 2015.
Talaat, E. R. and Zhu, X.: Spatial and temporal variation of total electron content as revealed by principal component analysis, Ann. Geophys., 34, 1109–1117, https://doi.org/10.5194/angeo-34-1109-2016, 2016.
Tariku, Y. A.: Assessment of improvement of the IRI model over Ethiopia for
the modeling of the variability of TEC during the period 2013–2016, Adv.
Space Res., 63, 1634–1645, https://doi.org/10.1016/j.asr.2018.11.014, 2018.
Uwamahoro, J. and Habarulema, J. B.: Modelling total electron content during
geomagnetic storm conditions using empirical orthogonal functions and neural
networks, J. Geophys. Res.-Space, 120, 11000–11012, https://doi.org/10.1002/2015JA021961, 2015.
Yao, Y., Liu, L., Kong, J., and Zhai, C.: Global Ionospheric Modeling Based on
Multi-GNSS, Satellite Altimetry and Formosat-3/COSMIC Data, GPS Solut., 22,
104, https://doi.org/10.1007/s10291-018-0770-6, 2018.
Zakharenkova, I. E., Cherniak, Iu. V., Krankowski, A., and Shagimuratov, I.
I.: Vertical TEC representation by IRI 2012 and IRI Plas models for European
mid latitudes, Adv. Space Res., 55, 2070–2076, https://doi.org/10.1016/j.asr.2014.07.027, 2015.
Zhang, S., Foster, J. C., Coster, A. J., and Erickson, P. J.: East–West
Coast differences in total electron content over the continental US,
Geophys. Res. Lett., 38, L19101, https://doi.org/10.1029/2011GL049116, 2011.
Zhang, S., Chen, Z., Coster, A. J., Erickson, P. J., and Foster, J. C.:
Ionospheric symmetry caused by geomagnetic declination over North America,
Geophys. Res. Lett., 40, 5350–5354, https://doi.org/10.1002/2013GL057933,
2013.
Zhao, B., Wan, W., Liu, L., Yue, X., and Venkatraman, S.: Statistical characteristics of the total ion density in the topside ionosphere during the period 1996–2004 using empirical orthogonal function (EOF) analysis, Ann. Geophys., 23, 3615–3631, https://doi.org/10.5194/angeo-23-3615-2005, 2005.
