A New Method to Combine Coastal Sea Surface Height Estimates from Multiple Retrackers by Using the Dijkstra Algorithm
Abstract
:1. Introduction
2. Data and Study Region
2.1. Altimeter Data
2.2. Tide Gauge Records
2.3. Study Region
3. Methodology
- (1)
- To optimize the range and geophysical corrections in the study area. The along-track SSH estimates are obtained as follows,
- (2)
- To calculate the temporal-averaged MSS at each along-track point (Section 3.1). The SSH estimates from all repeat cycles are referenced to the Topex ellipsoid and reduced to the nominal points of each reference track by using the nearest neighborhood approach. The reduced SSH estimates are then used to calculate the temporal-averaged MSS at each along-track point following the method in [4]. The along-track MSS can be used to remove the SSH outliers (see Section 3.4).
- (3)
- To determine and remove the bias of SSH estimates from different retrackers. The SSH bias is estimated with respect to the WLS3 (SAMOSA+) retracker for Jason-3 and Saral missions (Sentinel-3A mission) by the method introduced in Section 3.2.
- (4)
- To derive the most appropriate along-track SSH profile using the Dijkstra algorithm. This assumes that the high-rate SSH estimates vary insignificantly along the ground track (see Section 3.3). The along-track SLA profile is finally derived as the difference between the along-track SSH and MSS.
3.1. Regional Corrections and MSS
3.2. Removing SSH Bias
3.3. Combining SSH Estimates by Dijkstra Algorithm
3.4. Assessing the Performance of SCMR Strategy
4. Results
4.1. SSH Bias between Different Retrackers
4.2. Data Availability and Precision
4.3. Validation against Tide Gauge Records
5. Discussions
6. Conclusions
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Missions | Jason-3 | Saral | Sentinel-3A | |
---|---|---|---|---|
Corrections | ||||
DTC | ECMWF | ERA | ECMWF | |
WTC | GPD+ [27] | ECMWF | ||
Ionospheric correction | GIM | |||
Sea state bias | Peng and Deng [19] | |||
Geocentric ocean tide | FES2014 | |||
DAC | MOG2D | |||
Solid earth tide | Cartwright and Taylor [28] Cartwright and Taylor [29] | |||
Pole tide | Desai et al. [30] | |||
Mean sea surface | Along-track MSS [4] |
Missions | Jason-3 | Saral | Sentinel-3A | ||||
---|---|---|---|---|---|---|---|
Retrackers | |||||||
SGDR MLE4 | −0.0558 | 16.9 | −0.0778 | 3.7 | / | / | |
ALES | −0.0676 | −17.1 | −0.0722 | −9.6 | / | / | |
MB4 | −0.0866 | −2.2 | −0.0993 | −7.3 | / | / | |
SAM | / | / | / | / | 0.0136 | 5.3 |
Missions | Jason-3 | Saral | Sentinel-3A | ||||
---|---|---|---|---|---|---|---|
Retrackers | Before | After | Before | After | Before | After | |
SGDR MLE4 | 22.9 | 0.6 | 6.0 | 0.2 | / | / | |
ALES | −18.6 | −2.6 | −6.4 | −0.4 | / | / | |
MB4 | −7.0 | −3.0 | −7.8 | −0.8 | / | / | |
SAM | / | / | / | / | 6.8 | 0.5 |
Missions | Jason-3 | Saral | Sentinel-3A | ||||
---|---|---|---|---|---|---|---|
Retrackers | Before | After | Before | After | Before | After | |
SGDR MLE4 | 57.4 | 28.7 | 45.9 | 42.7 | / | / | |
ALES | 43.2 | 35.5 | 37.4 | 33.6 | / | / | |
MB4 | 36.2 | 30.5 | 36.2 | 32.3 | / | / | |
SAM | / | / | / | / | 63.0 | 62.5 |
Missions | Jason-3 | Saral | Sentinel-3A | ||||
---|---|---|---|---|---|---|---|
Retrackers | 0–20 km | 20–100 km | 0–20 km | 20–100 km | 0–20 km | 20–100 km | |
SCMR vs. MLE4 | 13.90 | 10.48 | 15.60 | 14.07 | / | / | |
SCMR vs. ALES | 24.32 | 14.67 | 20.67 | 14.26 | / | / | |
SCMR vs. WLS3 | 16.54 | 10.24 | 11.74 | 8.35 | / | / | |
SCMR vs. MB4 | 21.97 | 12.69 | 17.54 | 12.03 | / | / | |
SCMR vs. SAM | / | / | / | / | 25.07 | 25.07 | |
SCMR vs. SAM+ | / | / | / | / | 21.18 | 19.68 |
Missions | Jason-3 | Saral | Sentinel-3A | |
---|---|---|---|---|
Retrackers | ||||
SGDR MLE4 | 6.18 | 4.41 | / | |
ALES | 6.61 | 4.97 | / | |
WLS3 | 6.34 | 4.70 | / | |
MB4 | 6.71 | 4.57 | / | |
SAM | / | / | 5.32 | |
SAM+ | / | / | 5.04 | |
SCMR | 4.65 | 3.05 | 3.42 |
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Share and Cite
Peng, F.; Deng, X.; Jiang, M.; Dinardo, S.; Shen, Y. A New Method to Combine Coastal Sea Surface Height Estimates from Multiple Retrackers by Using the Dijkstra Algorithm. Remote Sens. 2023, 15, 2329. https://doi.org/10.3390/rs15092329
Peng F, Deng X, Jiang M, Dinardo S, Shen Y. A New Method to Combine Coastal Sea Surface Height Estimates from Multiple Retrackers by Using the Dijkstra Algorithm. Remote Sensing. 2023; 15(9):2329. https://doi.org/10.3390/rs15092329
Chicago/Turabian StylePeng, Fukai, Xiaoli Deng, Maofei Jiang, Salvatore Dinardo, and Yunzhong Shen. 2023. "A New Method to Combine Coastal Sea Surface Height Estimates from Multiple Retrackers by Using the Dijkstra Algorithm" Remote Sensing 15, no. 9: 2329. https://doi.org/10.3390/rs15092329