Improving GNSS-IR Sea Surface Height Accuracy Based on a New Ionospheric Stratified Elevation Angle Correction Model
Abstract
:1. Introduction
2. Construction of the New Ionospheric Stratified Elevation Angle Correction Model
2.1. Ionosphere Layering Design
2.2. The Train of Thought for the New Ionospheric Stratified Elevation Angle Correction Model
2.3. Construction of the New Ionospheric Stratified Elevation Angle Correction Model
3. Validation and Application of the New Ionospheric Stratified Elevation Angle Correction Model
3.1. Experimental Data
3.2. Accuracy Assessment Criteria
3.3. Verification and Application of the New Ionospheric Stratified Elevation Angle Correction Model
4. Conclusions
- (1)
- A new ionospheric stratification elevation angle correction model has been developed to address the ionospheric refraction issues in current satellite altimetry. In this study, the uneven distribution of ionospheric electron density at different altitudes throughout the entire GNSS-IR sea surface height retrieval process results in varying degrees of elevation angle deviation in satellite signals due to refraction. Therefore, a stratified approach has been introduced to mitigate these effects. The IRI model is used to extract the electron content density at different times, latitudes and longitudes, and ionospheric corresponding layering heights, then the elevation angle correction is calculated by using the ray trace method, and finally, the purpose of improving the accuracy of GNSS-IR sea surface height inversion is achieved.
- (2)
- The feasibility of the proposed ISEACM was validated through comparative analysis with tide gauge station data. Four GNSS satellite stations, TAR0, GOM1, PTLD, and TPW2, were selected to correct the satellite altitude angle by using a new ionospheric stratified elevation angle correction model, and then the GNSS-IR sea surface height measurement results were calculated and compared with the tide gauge data. The results indicate a strong correlation exceeding 0.75 between GNSS-IR sea surface height measurements corrected using ISEACM and tide gauge station data. The root mean square error was maintained within 0.30 m. These results show that the proposed ISEACM has good accuracy and reliability in the estimation of sea surface height.
- (3)
- A comparative study was conducted between conventional GNSS-IR sea surface height measurements and those corrected using the ISEACM model, aiming to analyze the superiority of the ISEACM model. The comparative analysis reveals that the ISEACM model enhances the accuracy of GNSS-IR sea surface height retrieval by up to 20% at its peak and 7% at its minimum compared to traditional methods. On average, the ISEACM model achieves a Pearson correlation coefficient of 0.84, representing a 4% increase over traditional GNSS-IR sea surface height retrieval methods. Therefore, the ISEACM model has optimized, to some extent, the satellite elevation angle errors induced by ionospheric refraction, thereby enhancing the accuracy of sea surface height measurements.
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Station | Geographical Location | Sampling Interval (s) | Observation Duration (d) | Elevation Angle (°) | Azimuth Angle (°) | Tide Gauge Station | Distance (m) |
---|---|---|---|---|---|---|---|
TAR0 | Spain | 30 | 31 | 5–30 | 0–360 | Tarifa | 407.25 |
PTLD | Australia | 30 | 31 | 5–30 | 0–360 | Portland_AU | 189.41 |
GOM1 | Spain | 30 | 31 | 5–30 | 0–360 | LaGomera | 6.52 |
TPW2 | USA | 30 | 31 | 5–30 | 0–360 | ASTO | 209.39 |
Station | RMSE before Correction (m) | PCC before Correction | RMSE after Correction (m) | PCC after Correction |
---|---|---|---|---|
TAR0 | 0.1752 | 0.88 | 0.1493 | 0.90 |
PTLD | 0.2041 | 0.72 | 0.1732 | 0.76 |
GOM1 | 0.2654 | 0.82 | 0.2480 | 0.84 |
TPW2 | 0.2616 | 0.81 | 0.2178 | 0.83 |
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Zhu, J.; Zheng, W.; Shen, Y.; Xu, K.; Zhang, H. Improving GNSS-IR Sea Surface Height Accuracy Based on a New Ionospheric Stratified Elevation Angle Correction Model. Remote Sens. 2024, 16, 3270. https://doi.org/10.3390/rs16173270
Zhu J, Zheng W, Shen Y, Xu K, Zhang H. Improving GNSS-IR Sea Surface Height Accuracy Based on a New Ionospheric Stratified Elevation Angle Correction Model. Remote Sensing. 2024; 16(17):3270. https://doi.org/10.3390/rs16173270
Chicago/Turabian StyleZhu, Jiadi, Wei Zheng, Yifan Shen, Keke Xu, and Hebing Zhang. 2024. "Improving GNSS-IR Sea Surface Height Accuracy Based on a New Ionospheric Stratified Elevation Angle Correction Model" Remote Sensing 16, no. 17: 3270. https://doi.org/10.3390/rs16173270