Abstract
With the widespread availability of ground and space-based global navigation satellite system (GNSS) observables, continuous and long-term explorations of ionospheric variations have been made possible worldwide or on regional basis with improved accuracy. The Formosa Satellite Mission#3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC) mission has a huge database of radio occultation (RO) soundings at regional and global scales with a high vertical resolution. Comparative studies between radio occultation, incoherent scatter radar and ionosonde observations indicate that COSMIC profiles agree well with ground measurements. The present paper investigates the ionospheric profiles over Africa using COSMIC data for the period from 2006 to 2017, representing almost a solar cycle year of study. The spatiotemporal variation of electron density confirms a hemispheric asymmetry among the equinoctial seasons and the solstice seasons during both low and moderate solar activity. Seasonal/winter anomaly manifestation is also clearly noticed in our observations with relatively high electron density during the winter solstice than the summer solstice. Moreover, the electron density over the region show apparent spatial and temporal variations identical to earlier ground-based ionospheric monitoring results over the African region. The outcomes from this study would strengthen the understanding of the ionospheric alterations and modelling activities in Africa, especially the areas with inadequate ground-based measuring instruments, hence, our results may complement the progress in global ionospheric modelling.
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References
Chauhan, V., Singh, O.P., Singh, B.: Diurnal and seasonal variation of GPS-TEC during a low solar activity period as observed at a low latitude station Agra. Indian J. Radio Space Phys. 40, 26–36 (2011)
Christian, Z., Frederic, O., Fleury, R., Amory-Mazaudier, C., Patrick, L.: Seasonal TEC variability in West Africa equatorial anomaly region. Eur. J. Sci. Res. 77, 309–319 (2012)
Dabbakuti, J.R.K.K., Mallika, Y., Venugopala Rao, M., Raghava Rao, K., Venkata Ratnam, D.: Modeling of GPS-TEC using QR-decomposition over the low latitude sector during disturbed geomagnetic conditions. Adv. Space Res. 64, 2088–2103 (2019). https://doi.org/10.1016/j.asr.2019.08.020
Fytterer, T., Arras, C., Hoffmann, P., Jacobi, C.: Global distribution of the migrating terdiurnal tide seen in sporadic E occurrence frequencies obtained from GPS radio occultations. Earth Planets Sp. 66–79 (2014). https://doi.org/10.1186/1880-5981-66-79
Gobiet, A., Kirchengast, G.: Advancements of Global Navigation Satellite System radio occultation retrieval in the upper stratosphere for optimal climate monitoring utility. J. Geophys. Res. 109, 1–11 (2004). https://doi.org/10.1029/2004jd005117
Gulyaeva, T.L.: Variations of the half-width of the topside ionosphere according to the observations by space ionosondes ISIS 1, ISIS 2, and IK 19. Geomagn. Aeron. 4, 201–207 (2003)
Jensen, A.S., Lohmann, M.S., Benzon, H.H., Nielsen, A.S.: Full spectrum inversion of radio occultation signals. J. Radio Sci. 38, 1040 (2003). https://doi.org/10.1029/2002RS002763
Jin, S., Komjathy, A.: GNSS Reflectometry and Remote Sensing: New Objectives and Results. Adv. Sp. Res. 46(2), 111–117 (2010)
Kumar, S., Singh, A.K., Lee, J.: Equatorial Ionospheric Anomaly (EIA) and comparison with IRI of solar activity model during descending phase (2005–2009). Adv. Space Res. 53, 724–733 (2014). https://doi.org/10.1016/j.asr.2013.12.019.
Kuo, Y.H., Wee, T.K., Sokolovskij, S., Rocken, C., Schreiner, W.S., Hunt, D., Anthes, R.A.: Inversion and error estimation of GPS radio occultation data. J. Meteorol. Soc. Jpn. 82, 507–531 (2004)
Lackner, B.C., Steiner, A.K., Hegerl, G.C., Kirchengast, G.: Atmospheric climate change detection by radio occultation data using a fingerprinting method. J. Climate 24, 5275–5291 (2011). https://doi.org/10.1175/2011JCLI3966.1
Lei, J.H., Syndergaard, S., Burns, A.G., Solomon, S.C., Wang, W.B., Zeng, Z., Roble, R.G., Wu, Q., Kuo, Y.H., Holt, J.: Comparison of COSMIC ionospheric measurements with ground-based observations and model predictions: preliminary results. J. Geophys. Res. 112, A07308 (2007)
Leroy, S.S., Dykema, J.A., Anderson, J.G.: Climate Benchmarking Using GNSS Occultation. Springer, Berlin, Heidelberg (2006)
Lin, C.H., Liu, J.Y., Hsiao, C.C., Liu, C.H., Cheng, C.Z., Chang, P.Y., Hsu, M.L.: Global ionospheric structure imaged by FORMOSAT-3/COS MIC: early results. Terr. Atmos. Ocean. Sci. 20, 171–179 (2009). https://doi.org/10.3319/TAO.2008.01.18.01(F3C)
Liu, L., Le, H., Chen, Y., He, M., Wan, W., Yue, X.: Features of the middle and low latitude ionosphere during solar minimum as revealed from COSMIC radio occultation measurements. J. Geophys. Res. 116, A09307 (2011). https://doi.org/10.1029/2011JA016691
Panda, S.K., Haralambous, H.: Variability of the bottomside B0 and B1 parameters of ionospheric electron density profile over Cyprus and comparison with IRI-2012 model. Adv. Space Res. 60, 317–328 (2017). https://doi.org/10.1016/j.asr.2016.08.025
Panda, S.K., Haralambous, H., Kavutarapu, V.: Global longitudinal behavior of IRI bottomside profile parameters from FORMOSAT-3/COSMIC ionospheric occultations. J. Geophys. Res. Space Phys. 123, 7011–7028 (2018). https://doi.org/10.1029/2018JA025246
Panda, S.K., Gedam, S.S.: Evaluation of GPS standard point positioning with various ionospheric error mitigation techniques. J. Appl. Geod. 10(4), 211–221 (2016). https://doi.org/10.1515/jag-2016-0019.
Panda, S.K., Gedam, S.S., Rajaram, G., Sripathi, S., Bhaskar, A.: Impact of the 15 January 2010 annular solar eclipse on the equatorial and low latitude ionosphere over the Indian region. J. Atmos. Sol.-Terr. Phys. 135, 181–191 (2015). https://doi.org/10.1016/j.jastp.2015.11.004
Pelliccia, F., Bonafoni, S., Basili, P., Ciotti, P., Pierdicca, N.: Atmospheric profiling in the inter-tropical ocean area based on neural network approach using GPS radio occultations. Open Atmos. Sci. J. 24, 202–209 (2010)
Potula, B.S., Chu, Y.H., Uma, G., Hsia, H.P.: A global comparative study on the ionospheric measurements between COSMIC radio occultation technique and IRI model. J. Geophys. Res., Atmos. 116, 1–24 (2011). https://doi.org/10.1029/2010JA015814
Prasad, S.N.V.S., Rama Rao, P.V.S., Prasad, D.S.V., Venkatesh, K., Niranjan, K.: On the variabilities of the Total Electron Content (TEC) over the Indian low latitude sector. Adv. Space Res. 49, 898–913 (2012)
Rocken, C., Kuo, Y.H., Schreiner, W.S., Hunt, D., Sokolovskiy, S., McCormick C.: COSMIC system description. Terr. Atmos. Ocean. Sci. 11, 21–52 (2000)
Scherllin-Pirscher, B., Kirchengast, G., Steiner, A.K., Kuo, Y.H., Foelsche, U.: Quantifying uncertainty in climatological fields from GPS radio occultation: an empirical-analytical error model. Atmos. Meas. Tech. 4, 2019–2034 (2011). https://doi.org/10.5194/amt-4-2019-2011
Schroeder, T., S., L., M., S.: Validating the microwave sounding unit stratospheric record using GPS occultation. Geophys. Res. Lett. 30 (2003). https://doi.org/10.1029/2003GL017588
Shimeis, A., Amory-Mazaudier, C., Fleury, R., Mahrous, A.M., Hassan, A.F.: Transient variations of vertical total electron content over some African stations from 2002 to 2012. Adv. Space Res. 54, 2159–2171 (2014)
Space.skyrocket.de: FORMOSAT 7/COSMIC-2. https://space.skyrocket.de/doc_sdat/formosat-7-cosmic-2.htm
Stankov, S.M., Stegen, K., Muhtarov, P., Warnant, R.: Local ionospheric electron density profile reconstruction in real time from simultaneous ground-based GNSS and ionosonde measurements. Adv. Space Res. 47, 1172–1180 (2010). https://doi.org/10.1016/j.asr.2010.11.039
Steiner, A.K., Kirchengast, G., Foelsche, U., Kornblueh, L., Manzini, E., Bengtsson, L.: GNSS occultation sounding for climate monitoring. Phys. Chem. Earth, Part A, Solid Earth Geod. 26, 113–124 (2001)
Syndergaard, S., Schreiner, W.S., Rocken, C., Hunt, D.C., Dymond, K.F.: Preparing for COSMIC: inversion and analysis of ionospheric data products. In: Atmosphere and Climate: Studies by Occultation Methods. Springer, New York (2006)
Yamazaki, Y., Stolle, C., Matzka, J., Liu, H., Tao, C.: Interannual variability of the daytime equatorial ionospheric electric field. J. Geophys. Res. 123, 4241–4256 (2018). https://doi.org/10.1029/2017JA025165
Yue, X., Schreiner, W.S., Kuo, Y.: GNSS Radio Occultation Observations as a Data Source for Ionospheric Assimilation: COSMIC-1 & COSMIC-2. 52, 2275753 (2014). https://doi.org/10.1029/2012JA017968
Yue, X., Schreiner, W.S., Kuo, Y., Hunt, D.C., Rocken, C.: GNSS radio occultation technique and space weather monitoring. In: Proceedings of the 26th International Technical Meeting of the ION Satellite Division, Nashville, Tennessee (2013)
Zakharenkova, I.E., Krankowski, A., Shagimuratov, I.I., Cherniak, Y.V., Krypiak-Gregorczyk, A., Wielgosz, P., Lagovsky, A.: Observation of the ionospheric storm of October 11, 2008 using FORMOSAT-3/COSMIC data. Earth Planets Space 64, 505–512 (2012). https://doi.org/10.5047/eps.2011.06.046
Zhang, K., Fu, E., Silcock, D., Wang, Y., Kuleshov, Y.: An investigation of atmospheric temperature profiles in the Australian region using collocated GPS radio occultation and radiosonde data. Atmos. Meas. Tech. 4, 2087–2092 (2011). https://doi.org/10.5194/amt-4-2087-2011
Acknowledgements
The authors extend their appreciation to the Deanship of Scientific Research at Majmaah University for funding this work under project number (RGP-2019-25). The authors wish to acknowledge the University Corporation for Atmospheric Research (UCAR) and the Taiwan’s National Space Organization (NSPO) for freely making available the COSMIC ionospheric profiles.
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Moses, M., Panda, S.K., Sharma, S.K. et al. Ionospheric electron density characteristics over Africa from FORMOSAT-3/COSMIC radio occultation. Astrophys Space Sci 365, 116 (2020). https://doi.org/10.1007/s10509-020-03833-2
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DOI: https://doi.org/10.1007/s10509-020-03833-2