integration tide gauge and satellite altimetry for storm surge and sea level change prediction. ole...

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)

http://www.newcastle.edu.au/

IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July, 2013

2 DTU Space, Technical University of Denmark

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 correctionMerging with tide gauges (spatial temporal correlation) Hindcast / forecast modelling

Test region: North European ShelfGreat Barrier Reef (Cyclone Helen and Larry)

Conclusions.

Queenland surge



Satellite altimetry is well

Esablished for linear

sea level change



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



Typical Surges / Cyclones

North sea has mainly external surges generated by wind forcing.

GBR has numerous cyclones (near seasonal)

= Water level recorders



Correlations, Water level recorders

Timescales, ~10-60 h

Counterclockwise propagation of sea level anomalies

Autocorrelation Crosscorrelation

Curtesy of J. Hoyer



ObservationsSampling:

SatelliteRepeat Period

Track spacing

InclinationCoverage

CryoSat-2 369 8 km 92°(+/-88°)

AltiKa 35 days 80 km 98°(+/-82°)

TOPEX/JASON 10 days 315 km 66.5°

3-4 ongoing missionsJASON-2

Cryosat-2 (SAR)AltiKa (French-India)**HY-2 (China)Sentinel-3 (SAR)

Near Real time data J2+C2: 4-6 hoursAccurcy: 4-6 cm




Critial issues:

√ Spatio-temporal sampling vs surge/cyclone

√ Availability and accuracy









Heavy Rain can be problematic




Critial issues:



√ Accuracy degradation (Coastal and rain).








Last devastating storm

surge in Britain – 1953

”Data for validation?”



High Water in Hvide Sande

Simple 2 and 3 std. deviation test on ”high water”



Satellite Obs

One versus two satellite (TOPEX/ENVISAT)

Degradation not an issue



Great Barrier Reef – Summer Cyclones

• Helen (January, 04, 2008) Larry (March 19th, 2006)




Critial issues:











Tide Correction Models

Remove residual tidal signal using the ”pointwise tide model. This enhances

The spatial correlation between tide gauge and



Spatio-temporal Correlation

• TOPEX / JASON (17 years) ERS / ENVISAT (12 years)



Temporal Correlation at Newlyn

After Detiding – temporal correlation = 0.93 (0.89 FES 2004 / GOT4.7)



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.



Combing Tide gauges and Altimetry

Small time scale, Large spatial scales, high correlation T/P + Gauges

)()()()( 33221 tsshtsshtsshtTP

Least squares fit in every T/P observation

Regression Model



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.



• 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…….

Conclusions

integration tide gauge and satellite altimetry for storm surge and sea level change prediction. ole...

Documents

dtu space

iaspei assembly

modelling slide

linear sea level change

australia slide

hoyer slide

problematic slide

cheng dtu