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Integration Tide Gauge and Satellite Altimetry for Storm Surge and Sea Level change prediction.

Integration Tide Gauge and Satellite Altimetry for Storm Surge and Sea Level change prediction. Ole B. Andersen and Y. Cheng (DTU, Denmark) Xiaoli Deng, M. Steward, N Idris, and Zahra Gharineiat (Uni NewCastle, Australia). Overview. Why use satellite altimetry

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Integration Tide Gauge and Satellite Altimetry for Storm Surge and Sea Level change prediction.

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  1. Integration Tide Gauge and Satellite Altimetry for Storm Surge and Sea Level change prediction. Ole B. Andersen and Y. Cheng (DTU, Denmark) Xiaoli Deng, M. Steward, N Idris, and Zahra Gharineiat (Uni NewCastle, Australia)

  2. Overview Why use satellite altimetry Crital issues: Spatio-temporal sampling vs surge/cyclone Availability and accuracy Accuracy degradation (Coastal and rain). Reliability of surge capturing Importance of residual range corr errors: Ocean tide correction Merging with tide gauges (spatial temporal correlation) Hindcast / forecast modelling Test region: North European Shelf Great Barrier Reef (Cyclone Helen and Larry) Conclusions. Queenland surge

  3. Satellite altimetry is well Esablished for linear sea level change

  4. Sea Level and Storm Surges Critial issues: Spatio-temporal sampling vs surge/cyclone Availability and accuracy Accuracy degradation (Coastal and rain). Reliability of surge capturing Importance of residual range corr errors: Ocean tide correction Merging with tide gauges (spatial temporal correlation) Hindcast / forecast modelling

  5. Typical Surges / Cyclones North sea has mainly external surges generated by wind forcing. GBR has numerous cyclones (near seasonal) = Water level recorders

  6. Correlations, Water level recorders Autocorrelation Crosscorrelation Timescales, ~10-60 h Counterclockwise propagation of sea level anomalies Curtesy of J. Hoyer

  7. ObservationsSampling: 3-4 ongoing missions JASON-2 Cryosat-2 (SAR) AltiKa (French-India)** HY-2 (China) Sentinel-3 (SAR) Near Real time data J2+C2: 4-6 hours Accurcy: 4-6 cm

  8. Sea Level and Storm Surges Critial issues: √ Spatio-temporal sampling vs surge/cyclone √ Availability and accuracy Accuracy degradation (Coastal and rain). Reliability of surge capturing Importance of residual range corr errors: Ocean tide correction Merging with tide gauges (spatial temporal correlation) Hindcast / forecast modelling

  9. Heavy Rain can be problematic

  10. Sea Level and Storm Surges Critial issues: √ Spatio-temporal sampling vs surge/cyclone √ Availability and accuracy √ Accuracy degradation (Coastal and rain). Reliability of surge capturing Importance of residual range corr errors: Ocean tide correction Merging with tide gauges (spatial temporal correlation) Hindcast / forecast modelling

  11. Last devastating storm surge in Britain – 1953 ”Data for validation?”

  12. High Water in Hvide Sande Simple 2 and 3 std. deviation test on ”high water”

  13. Satellite Obs One versus two satellite (TOPEX/ENVISAT) Degradation not an issue

  14. Great Barrier Reef – Summer Cyclones • Helen (January, 04, 2008) Larry (March 19th, 2006)

  15. Sea Level and Storm Surges Critial issues: √ Spatio-temporal sampling vs surge/cyclone √ Availability and accuracy Accuracy degradation (Coastal and rain). Reliability of surge capturing Importance of residual range corr errors: Ocean tide correction Merging with tide gauges (spatial temporal correlation) Hindcast / forecast modelling

  16. Tide Correction Models Remove residual tidal signal using the ”pointwise tide model. This enhances The spatial correlation between tide gauge and

  17. Spatio-temporal Correlation • TOPEX / JASON (17 years) ERS / ENVISAT (12 years)

  18. Temporal Correlation at Newlyn After Detiding – temporal correlation = 0.93 (0.89 FES 2004 / GOT4.7)

  19. Sea Level prediction • CAN WE PREDICT/WARN ABOUT INCREASED SEA LEVEL • ”STORM SURGES” FROM SATELLITE ALTIMETRY????? Main issues: • Sampling (fixed tracks, sampling 9 / 17 or 35 days • Availability of ACCURATE real time data (1-6 hours) • Capture the Surge by the altimeter • Merging Tide gauge and Altimetry (observe the same signal) Establish warning – ”hindcast” high water.

  20. Combing Tide gauges and Altimetry Small time scale, Large spatial scales, high correlation T/P + Gauges Regression Model Least squares fit in every T/P observation

  21. Integrating using Neural Network Test on using 4 gauges along coast of Norway. Training using one T/P time series Predicting other satellite points. Higher temporal correlation using Neural Network than regression method.

  22. Conclusions • Satellite altimetry delivers: • Sea surface height • Wave height • Wind Speed • predefined tracks+sampling • Satellite altimetry has high temporal/spatial correlation with tide gauges • Huge potential for ”high water forecasting” • with tide gauges offers huge potential for improved warning in the future Comming satellites (Cryosat + Sentinel-3) might offer even better prediction in the future (higher resolution + across track coverage) Having vacation in Venice this summer…….

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