Abstract
The ionosphere F2 layer is principally used for the reflection of radio waves in high-frequency communication and broadcasting. The ionosphere is used as a propagation medium for HF propagation. Global models like the IRI model may not define variation in the ionosphere of a specific area exactly. Several studies have found significant differences between the ionospheric parameters forecasted by the IRI model and observed data. Regional models provide more accurate data of ionospheric parameters, which can serve to update IRI in Pakistan. Variations in the ionosphere from low to mid-latitude in the F region of Pakistan will be studied. This study will help with navigation and HF communication. A comprehensive study about variation in the ionosphere will help to operate space communication smoothly in this region. It is our aim to construct regional models of ionospheric parameter, foF2, by using empirical orthogonal analysis combined with linear regression method for Karachi (geographic 24.95°N, 67.14°E), Islamabad (geographic 33.75°N, 72.87°E), and Multan (geographic 30.18°N, 71.48°E) stations by using the data from the years 1986–1996. In this study, parameter \({F}_{10.7}\) with a known significant impact on foF2 was used. To evaluate ionospheric response, base functions and their associated coefficients features will be investigated. \({E}_{\mathrm{k }}(h)\) k-the base function represents the diurnal variation of foF2 and corresponding principal components coefficients \({A}_{\mathrm{k}}(d)\) denote the long-term variation such as solar cycle and seasonal variations. \({A}_{1}\), \({A}_{2}\), and \({A}_{3}\) first three EOF coefficients are characterized by the solar cycle, annual, and semi-yearly variation. \({A}_{1}\) represents a long-term trend which shows variation in solar activity. \({E}_{1}\) represents the diurnal variation in foF2. Diurnal variation in foF2 is caused by the ionization and recombination process. The model can reproduce the whole variability of the ionosphere by only the first three components of EOF. To evaluate the model accuracy, results will be compared with observed data and with the IRI model.
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References
Aa E, Ridley A, Huang W, Zou S, Liu S, Coster AJ, Zhang S (2018) An ionosphere specification technique based on data ingestion algorithm and empirical orthogonal function analysis method. Space Weather 16(9):1410–1423
Adeniyi JO, Radicella SM, Adimula IA, Willoughby AA, Oladipo OA, Olawepo O (2007) Signature of the 29 March 2006 eclipse on the ionosphere over an equatorial station. J Geophys Res: Space Phys 112(A6)
Ataç T, Özgüç A, Pektaş R (2009) The variability of foF2 in different phases of solar cycle 23. J Atmos Solar Terr Phys 71(5):583–588
Bilitza D (1990) International Reference Ionosphere 1990, Rep. NSSDC/WDC-R&S 90–22, World Data for Rockets and Satell. Nat Space Sci Data Cent Greenbelt, Md
Bilitza D (2001a) International Reference Ionosphere 2000. Radio Sci 36:261–275. https://doi.org/10.1029/2000rs002432
Bilitza D (2002) Ionospheric models for radio propagation studies, in The Review of Radio Sci. 1999 – 2002, edited by W. R. Stone, pp. 625 – 679, IEEE Press, Piscataway, N. J
Bilitza D (2001b) International Reference Ionosphere 2000. Radio Sci 36(2):261–275. https://doi.org/10.1029/2000RS002432
Diabaté A, Ouattara F, Zerbo JL (2018) Annual and diurnal variabilities in the critical frequency (foF2) during geomagnetic fluctuating activity over solar cycles 21 and 22 at Ouagadougou. Atmos Clim Sci 8(4):435–445
Dvinskikh NI (1988) Expansion of ionospheric characteristics fields in empirical orthogonal functions. Adv Space Res 8(4):179–187
Feng J, Wang Z, Jiang W, Zhao Z, Zhang B (2016) A new regional total electron content empirical model in northeast China. Adv Space Res 58(7):1155–1167
Holt JM, Zhang SR, Buonsanto MJ (2002) Regional and local ionospheric models based on Millstone Hill incoherent scatter radar data. Geophys Res Lett 29(8):48–51
Liu JY, Chen YI, Lin JS (2003) Statistical investigation of the saturation effect in the ionospheric foF2 versus sunspot, solar radio noise, and solar EUV radiation. J Geophys Res: Space Phys 108(A2)
Lin J, Yue X, Zeng Z, Lou Y, Shen X, Wu Y, … Kuo YH (2014) Empirical orthogonal function analysis and modeling of the ionospheric peak height during the years 2002–2011. J Geophys Res Space Physics 119(5):3915–3929
Liu L, Wan W, Chen Y, Le H (2011) Solar activity effects of the ionosphere: a brief review. Chin Sci Bull 56(12):1202–1211
Liu L, Wan W, Ning B (2004) Statistical modeling of ionospheric foF2 over Wuhan. Radio Sci 39:RS2013, https://doi.org/10.1029/2003RS003005
Li W, Zhao D, He C, Hu A, Zhang K (2020a) Advanced machine learning optimized by the genetic algorithm in ionospheric models using long-term multi-instrument observations. Remote Sens 12(5):866
Li H, Wang JS, Chen Z, Xie L, Li F, Zheng T (2020b) The contribution of geomagnetic activity to ionospheric foF2 trends at different phases of the solar cycle by SWM. Atmosphere 11(6):616
Mikhailov AV, Mikhailov VV (1995) A new ionospheric index MF2. Adv Space Res 15(2):93–97
Rishbeth H, Mendillo M (2001) Patterns of F2-layer variability. J Atmos Solar-Terr Phys 63(15):1661–1680
Murtaza G, Iqbal S, Ameen MA, Iqbal A (2008) Comparing IRI and regional model with ionosonde measurements in Pakistan. Adv Space Res. (pp. 682–690). IEEE
Pearson K (1901) On lines and planes of closest fit to systems of points in space. Phil Mag 2:559–572
Seyoum A, Gopalswamy N, Nigussie M, Mezgebe N (2019) The impact of CMEs on the critical frequency of F2-layer ionosphere (foF2). Proc Int Astron Union 15(S356):400–402
Schunk R, Nagy A (2009) Ionospheres: physics, plasma physics, and chemistry. Cambridge University Press
Sapundjiev D, Stankov SM (2016) Statistical analysis and modeling of the local ionospheric critical frequency: a mid-latitude single-station model for use in forecasting. Acta Geophys 64(3):810–824
Wang J, Bai H, Huang X, Cao Y, Chen Q, Ma J (2019) Simplified regional prediction model of long-term trend for critical frequency of ionospheric F2 region over East Asia. Appl Sci 9(16):3219
Xu T, Wu ZS, Wu J, Wu J (2008) Solar cycle variation of the monthly median foF2 at Chongqing station, China. Adv Space Res 42(1):213–218
Zhang ML, Shi JK, Wang X, Wu SZ, Zhang SR (2004) Comparative study of ionospheric characteristic parameters obtained by DPS-4 digisonde with IRI2000 for low latitude station in China. Adv Space Res 33(6):869–873
Zhang DH, Xiao Z, Hao YQ, Ridley AJ, Moldwin M (2011) Modeling ionospheric foF2 by using empirical orthogonal function analysis. In Annales Geophysicae (Vol. 29, No. 8, pp. 1501–1515). Copernicus GmbH
Zhao Z, Feng J, Han B, Wang Z (2018) A single-station empirical TEC model based on long-time recorded GPS data for estimating ionospheric delay. J Space Weather Space Clim 8:A59
Acknowledgements
The \({F}_{10.7}\) index data is downloaded from the OmniWeb and ionospheric foF2 data is obtained from Suparco (Pakistan Space and Upper Atmosphere Research Commission) for stations Karachi, Islamabad, and Multan. Special thanks to Madam Madiha Talha for their help and guidance.
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Communicated by Zhihua Zhang.
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Ashraf, U., Hanif, F. & Ashraf, S. Regional model of foF2 for Pakistan using empirical orthogonal function technique. Arab J Geosci 15, 568 (2022). https://doi.org/10.1007/s12517-022-09435-2
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DOI: https://doi.org/10.1007/s12517-022-09435-2