Regional model of foF2 for Pakistan using empirical orthogonal function technique

• Published in: Arabian journal of geosciences Vol. 15; no. 7
• Main Authors: Ashraf, Uzma, Hanif, Fozia, Ashraf, Saima
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-04-2022; Springer Nature B.V
• Subjects: Coefficient of variation; Coefficients; Communication; Components; Diurnal variations; Earth and Environmental Science; Earth science; Earth Sciences; Empirical analysis; F 2 region; F region; Ionization; Ionosphere; Ionospheric propagation; Mathematical models; Model accuracy; Navigation; Original Paper; Orthogonal functions; Parameters; Radio broadcasting; Radio waves; Recombination; Seasonal variation; Seasonal variations; Solar activity; Solar cycle; Space communication; Wave reflection; Pakistan; solar flux; EOF (empirical orthogonal function technique); Ionosphere; IRI model (International Reference Ionosphere); foF2 (critical frequency of F2 layer)
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-022-09435-2

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
k
(
h
)
k
-the base function represents the diurnal variation of foF2 and corresponding principal components coefficients
A
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.