Comparison of Tide Gauges

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ESEAS-RI Task 4.1 Comparison of tide
gauges Task leader P6 (Puertos del
Estado)Participants P6, P5 (Spanish Institute
of Oceanography), P3 (POL) Madrid, February
2004
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Milestones

• M4.1 Pilot station established (1mon)
• (Villagarcía station 1.5 mon, number of sensors
  increasing along the year)
• M4.2 Selection of sensor for upgrading on the
  basis of assessment of tide gauge sensors (14
  months)

(delayed)
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Deliverable

• assessment of accuracy and operational properties
  of different tide gauges (13 months)
• situation first results already available
  Villagarcía station will go on working for
  several months

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Contributions to Task 4.1

• P6 (PE) Test site at Villagarcía de Arosa (NW
  Spain), 8 tide gauges, first results available
• P3 (POL) Test site at Liverpool (UK), 2 tide
  gauges. Results already available
• P5 (IEO) Installation of a radar sensor at
  Santander (North Spain), 3 tide gauges. First
  results now available

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P6 Villagarcía station

• SRD permanent station from PE (REDMAR network)
• Equipments acquired by PE and borrowed from
  several companies and institutions
• Maximum tidal range 4.2 m

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P6 Villagarcía station

• 8 tide gauges
• 2 Acoustic AQUATRAK (NOAA)/ SRD (REDMAR)
• 4 Radar MIROS / RADAC / SEBA / VEGA (Geonica)
• 1 Pressure SEABIRD
• 1 Bubbler gauge (POL)

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P6 Villagarcía station

• Status
• First year different installation dates, not
  long simultaneous series
• First results presented selecting two different
  periods (5 min data) show a problem with the
  Aquatrak and good agreement for the rest of the
  sensors (between 0.7 and 2.6 cm RMS)
• Operation of the station will go on

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P6 Villagarcía station

• Additional studies performed since last meeting
• Comparison of higher frequency data (1 s) between
  some of the sensors already made
• Influence of meteorological conditions
• Comparison of evolution of mean sea levels with
  longer time series

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P6 Villagarcía station

• Future work
• Harmonic analysis and comparison of
  meteorological residuals
• Detailed study of maintenance and calibration
  requirements
• Incorporation of the bubbler gauge from POL

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P5 Santander station

• Santander is a permanent station of both the
  REDMAR network (P6) and the IEO network (P5), in
  the North coast of Spain.
• Two permanent gauges installed a float gauge
  with OWK-16 encoder (P5) and a SRD acoustic gauge
  (P6).
• P5 installed a SEBA radar sensor (Nov 2002).
• 3 sensors inside the same stilling well.

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P5 Santander station
First comparisons made between radar sensor and
float gauge (P5)
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P5 Santander station

• Problems in data from the float gauge due to
  works performed in the station and old
  counterweight system until November 2003

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P5 Santander station

• Best results for the period November
  2003-December 2003 differences dependent on the
  tidal range

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P5 Santander station

• Future work
• Comparisons with the REDMAR SRD gauge, operating
  in the same well for the whole period
• More detailed analysis of previous differences

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P3 Liverpool station

• Voluntary contribution from an experiment of
  comparison of a bubbler gauge and an OTT Kalesto
  radar gauge at Liverpool (Phil Woodworth, David
  E. Smith).
• Both sensors have been operated for one year.
• Tide range of almost 10 m at some spring tides.

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P3 Liverpool station

• Period March 2002- April 2003.

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P3 Liverpool station

• 15 min-interval (mean value)
• Comparison of both 15-min values and hourly
  values for the year
• Harmonic analysis
• Comparison of residuals

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P3 Liverpool station

• Results
• rms from 15 min (whole year) 1.5 cm
• rms from hourly values (1 year) 1.41 cm
• power of high-frequency non-tidal residuals
  similar in both sensors
• Conclusion each instrument could provide a time
  series precision of 1 cm (GLOSS standards)