Objectives Global navigation satellite system-interferometric reflectometry (GNSS-IR) technology has become one of the effective methods to retrieve tide levels by utilizing multipath information in signal-to-noise ratio (SNR) data. However, it is usually necessary to limit the elevation range, resulting in less usable data and insufficient time resolution. To solve the above problems, a preprocessing data quality control method is proposed.
Methods First, the significant difference between usable and unusable data is obtained through comparative analysis. Based on this difference, a GNSS-IR data quality control method is proposed to classify SNR data and screen out unusable data by data reconstruction and building a Transformer model. Second, appropriate data sets are selected to verify and evaluate the effectiveness and generalization ability of the method.
Results The results show that there are significant differences in amplitude characteristics between usable and unusable data, and the proportion of usable SNR data for 5°-30° elevation is significantly improved by the proposed method, thus extending the elevation range of usable data to 5°-30° at the inversion site.
Conclusions The proposed method significantly improves the amount of usable data and the time resolution of the GNSS-IR tide level retrieval method, which is of great significance for the application of GNSS-IR technology in real-time monitoring of tsunami and storm surge, as well as marine studies such as long-term sea level changes. Moreover, the method is a preprocessing data quality control method, which can identify and screen unusable data before tidal level retrieval, to break through the limitation that the post-processing method needs to accumulate SNR data for a long time. Therefore, it is better applicable to a scene where the tidal level changes dramatically in a short time, such as a tsunami.
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