Comprehensive evaluation of spaceborne and ground-based ionospheric observations and their application in data assimilation

The data volume of ionospheric observations has been dramatically enlarged these years by ground-based and spaceborne measuring techniques including global GNSS network, scientific and commercial plans of radio occultation, and satellite altimetry. Given the diverse observing geometries, vertical data coverages and intermission biases among different measurements, it is imperative to evaluate their absolute accuracies and estimate systematic biases to determine reasonable weights and error variances when integrating different sources of data. This research focus on the data assessment of several satellite missions launched in China such as MSS-1 and Yunyao constellation, and conducts comprehensive comparison among radio occultation, global ionospheric maps and satellite altimetry. The large amount of daily ionospheric radio occultation data from about 20 satellites and ground GNSS observations are devoted to the data assimilation system driven by Kalman filter. The observational accuracy provides essential information for determining error covariance and weight matrices in the total electron content assimilation model.