Global and Regional Consistency of VTECs Inversed by IPM and GNSS

The ionospheric photometer (IPM) onboard the Fengyun-3D satellite is the first optical remote sensing payload in China designed for space-based surveillance of the ionosphere and capable of inversing the Vertical Total Electron Content (VTEC) at night with high sensitivity. Using the VTECs inversed by IPM, along with other sources of ionospheric observations, such as the ground-based Global Satellite Navigation System (GNSS) VTECs, ionospheric modeling can be established based on multi-source space observation techniques and is expected to improve the modeling accuracy in marine areas. Before the ionospheric modeling using multi-source data, the consistency between different sources of VTECs should be analyzed. However, the consistency between the IPM-VTEC and GNSS-VTEC has not been adequately investigated. The authors employ the Global Ionospheric Map (GIM) products from the International GNSS Service to assess the global-scale consistency between them, and the analysis reveals a generally high global-scale consistency, yet the IPM-VTEC values in specific regions are too large due to the influence of auroras and ionospheric equatorial anomalies.