NOAA Use of Submersible Pressure Tide Gauge Technology in Alaska

1. NOAA Use of Submersible Pressure Tide Gauge Technology in Alaska Recent Activities and Proof of Concept CO-OPS October 2012

2. NOAA Use of Submersible Pressure Tide Gauge Technology in Alaska • Used for offshore deployments for tidal zoning • Used where combination of high range of tide, shallow bathymetry and lack of infrastructure limit use of acoustic, MWWL, and bubbler pressure gauge sensors. • Used for measuring tides under the ice • Requires ancillary measurements of water density and barometric pressure to convert pressure data to water level • Nearshore deployments use “staff shot to the waters edge” procedure to transfer gauge readings to the tidal bench marks.

3. NOAA Use of Submersible Pressure Tide Gauge Technology in Alaska • CO-OPS experience with offshore submersible pressure gauges dates back to 1970’s • Recent experience includes successful use in AK contract hydrographic surveys • Long-term deployment completed offshore Barrow, AK results in 2-year continuous time series.

4. Kuskokwim Bay, AK Hydrographic Survey Pressure Gauge Deployment Sensor locations

5. Quinhagak, AK Submersible Pressure Gauge Configuration

6. Quinhagak, AK Submersible Pressure Gauge Staff Shots Staff Shots : High Tide Staff Shots: Low Tide

7. Quinhagak, Kuskokwim Bay, AK – two separate deployments in Summer 2010 and Summer 2011

8. Quinhagak, Kuskokwim Bay, AK Accepted Datums

9. Barrow, AK Pressure Gauge Deployment

10. Pt. Barrow, AK Environmental and Logistics Challenges Winter Summer Staff shots are periodically made to the waters edge using a level backsight to a bench mark and a foresight to the elevation of the water. Simulraneous staff to gauge differences are accumulated and averaged to obtain a constant to transfer gauge elevations to land elevations. Daily staff shots are logistically difficult, so each intermittent “session” contains a sequence (burst sample) of staff-shots over a 1 – 2 hour period.

11. Barrow, AK Deployment Configuration

12. Barrow AK Deployment Vessels 14 ‘ JOA Cataraft Bowhead Trans, 150’ landing craft Note: This configuration can be deployed and retrieved using small vessels. Crawford Patkotak’s 26’

13. Staff Shots used with Submersible Pressure Gauges – Leveling to the Waters Edge Staff shots are periodically made to the waters edge using a level backsight to a bench mark and a foresight to the elevation of the water. Simultaneous staff to gauge Differences are accumulated and averaged to obtain a constant to transfer gauge elevations to land elevations. Daily staff shots are logistically difficult, so each intermittent “session” contains a sequence (burst sample) of staff-shots over a 1 – 2 hour period.

14. GPS Water Elevation Shots and Acoustic Modem Data Download GPS Staff Measures through Drill Hole Acoustic Modem Lowered through Drill Hole

15. Barrow, AK Deployments – Two years of Continuous Data 8/2008 – 8/2010

16. Published Tidal Datums for Barrow Submersible Gauge Deployments

17. NOAA Use of Submersible Pressure Tide Gauge Technology in Alaska • Proof of concept has been successful • Successful deployments have been completed both for hydrographic survey short-term deployments and long-term NWLON applications • Accepted tidal data, tidal datums, and published tidal bench mark elevations have been issued for both