Abstract:
The plasma frequency profiles derived from the Constellation of Observing System for Meteorology,
Ionosphere and Climate (COSMIC) radio occultation measurements are compared with ground-based ionosonde
data during the year 2013. Equatorial and midlatitude five stations located in the Northern and Southern
Hemisphere are considered: Jicamarca, Jeju, Darwin, Learmonth, and Juliusruh. The aim is to validate the
COSMIC-derived data with ground-based measurements and to estimate the difference in plasma frequency
(which represents electron density) and height of F2 layer peak during the daytime/nighttime and during
different seasons by comparing the two data sets. Analysis showed that the nighttime data are better correlated
than the daytime, and the maximum difference occurs at the equatorial ionospheric anomaly (EIA) station as
compared to lower and midlatitude stations during the equinox months. The difference between daytime and
nighttime correlations becomes insignificant at midlatitude stations. The statistical analysis of computed errors in
foF2 (hmF2) showed Gaussian nature with the most probable error range of ±15% (±10%) at the equatorial and EIA
stations, ±9% (±7%) outside the EIA region which reduced to ±8% (±6%) at midlatitude stations. The reduction in
error at midlatitudes is attributed to the decrease in latitudinal electron density gradients. Comparing the
analyzed data during the three geomagnetic storms and quiet days of the same months, it is observed that the
differences are significantly enhanced during storm periods and the magnitude of difference in foF2 increases
with the intensity of geomagnetic storm.
