Temporal and spatial characteristics of the ionosphere in the Qinghai–Tibet Plateau

Abstract

The ionosphere characteristics are important for radio propagation and to monitor climate. At present, its research is confined to global scale or a single station. There are only few local area studies of ionosphere. In view of this situation, we will first verify the reliability of Global Ionosphere Map (GIM, IGS final products) in the Qinghai–Tibet Plateau, then implement low-power filtering and time series analysis to study the periodic, semiannual, and seasonal variation, the peak characteristic, and the “winter anomaly” phenomenon of the ionosphere. Finally, correlations between total electron content (TEC), solar activity indices, and geomagnetic indices are investigated, respectively, by executing quadratic polynomial fitting and establishing the relationship of TEC and F10.7p. The experimental results show that GIM is a reliable resource to research on the temporal and spatial characteristics of the ionosphere in the Qinghai–Tibet Plateau. The minimum TEC always occurs in autumn, whereas the maximum TEC occurs in spring or winter alternatively, which depends on the ascending or descending phase of solar activity. The “winter anomaly” phenomenon that existed for few years normally appears during the ascending phase of solar activity. The correlation coefficients of TEC with three solar activity indices, sunspot number, F10.7, and F10.7p are 0.79, 0.82, and 0.83, respectively, which show strong correlations between them. The correlation coefficients of TEC with three geomagnetic indices, Dst, Kp, and Ap are −0.48, 0.43, and 0.38, respectively, which show weak correlations between them. Quadratic polynomial regression of F10.7p and TEC is implemented. The regression line reflects that the ionosphere TEC in the Qinghai–Tibet Plateau has a saturated status.