摘要 :
The ionospheric thickness (B0) and shape (B1) are bottomside profile parameters introduced by the International Reference Ionosphere (IRI) model. We have validated these parameters with the latest version of the IRI-2012 model and...
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The ionospheric thickness (B0) and shape (B1) are bottomside profile parameters introduced by the International Reference Ionosphere (IRI) model. We have validated these parameters with the latest version of the IRI-2012 model and compared them with the solar quiet of geomagnetic H-component (SqH). The B0, B1 and SqH are calculated from the measurements obtained from digisonde DPS-4 sounder and the Magnetic Data Acquisition System (MAGDAS) magnetometer, respectively at Ilorin (geo latitude 8.50°N, geo longitude 4.68°E, and Magnetic dip 4.1°S) an equatorial station in the African sector. The study was for the year 2010, a year of low solar activity (with 27-day averaged solar index, F10.7 = 80 sfu). The results show that B0 for the entire months was higher during the daytime than during the night time. On the other hand, the magnitude of B1during the daytime period is lower than nighttime values and exhibit oscillatory pattern. By comparing the experimental observations of the profile parameters with the IRI-2012 model prediction, we found that B0 was fairly represented by the IRI model options during the nighttime period while discrepancies exist between the model estimates and the experimental values during the morning till midday. A close agreement exists between the observed B1 values and IRI model options. We observed a positive and significant correlation coefficient between B0 and SqH indicating a plausible relationship between these parameters while a weak and negative correlation coefficient between B1 and SqH was observed. We concluded that the difference in the relationship of SqH and the profile parameters B0 and B1 observed can be attributed to their sensitivity to the electric field which is responsible for the E × B drift which in turn modulate the height of the F2.
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摘要 :
The study presents a simultaneous variation of equatorial electrojet (EEJ) current and the ionospheric F2-layer maximum electron density (NmF2) during geomagnetic quiet days and moderate solar conditions (solar radio flux, 饾惞10....
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The study presents a simultaneous variation of equatorial electrojet (EEJ) current and the ionospheric F2-layer maximum electron density (NmF2) during geomagnetic quiet days and moderate solar conditions (solar radio flux, 饾惞10.7 魛祹 120 sfu). The geomagnetic measurements at Kotatobang (KTB) and Langkawi (LKW) stations have been used to estimate the magnetic daily variation in H-component and in deriving EEJ. The NmF2 data set is from Frequency Modulation Continuous Wave (FM-CW), an analogue ionosonde located at the KTB station. The study examines both the diurnal and seasonal variation in EEJ and the corresponding effect on the measured NmF2. The results obtained show that the derived EEJ at LKW shows a daytime peak which coincides with the period NmF2 measurement at KTB station depleted to a daytime low value. The role of EEJ at the LKW station correlates poorly with the NmF2 at KTB in which their correlation coefficient (r) is in the range of 0.02 to 0.04 for equinox, summer and winter, respectively. However, an r-value of 0.33 was observed when the whole data set for the year 2012 was considered. The poor correlation coefficient between derived EEJ and NmF2 measured at KTB during the moderate solar condition suggest that EEJ has little or no influence on the prevailing ionospheric condition at a low latitude station located outside the EEJ strip.
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