Measuring Currents from Aids-to-Navigation Buoys

Transcription

1 Measuring Currents from Aids-to-Navigation Buoys Recent Design Improvements Bob Heitsenrether Kate Bosley, PhD Kasey Hall

2 Overview CO-OPS Background NOAA s Physical Oceanographic Real-time System (PORTS ) Measuring Currents from USGS ATON s Challenges & Lessons Learned Mooring Interference System Enhancements Summary & Continuing Work

3 CO-OPS in NOAA s Ocean Service Mission CO-OPS is an authoritative source for accurate and timely tides, water levels, currents and other oceanographic information. Our data, products and services support: safe and efficient navigation, sound ecosystem stewardship, coastal hazards preparedness and response, and the understanding of climate change.

4 PORTS

5 PORTS Locations

6 Measuring Currents from ATON Buoys Navigators need real-time currents where they work Cable length & instrument safety limited deployments Unique ATON ADCP system developed with a "clamparatus to attached Nortek Aquadopp and electronics box to the ATON buoy NOS entered partnership with U.S. Coast Guard to place current measurement systems on existing Aids-TO-Navigation (ATON) buoys

7 ATON ADCP System Overview

8 Package relatively light, ~ 200 lbs Deployable from small boat Data to shore via s-spectrum radio ~ 6 months of battery operation

9 >> release VERIFIED data if verified data exist Challenges Smaller Buoy 15 Aug Sep 2007, 45 day simultaneous deployment of: o Nortek 1000 khz mounted on 6x20 ATON o Bottom-mounted RDI 1200 khz ADCP (300 m SW) o Bottom-mounted Nortek 400 khz (300 m SW) Bolivar Roads Anomalous observationspossible evidence of mooring interference

10 Bottom Mounted, Upward looking ADCP ATON Mounted, Downward looking ADCP Summary of J. Boon Results Anomalies - Current veering and speed reduction U, V scatter plots show anomalies persists over depth and time Anomalies are largely restricted to peak flood *from report by Dr. John D. Boon, Marine Consultant, LLC

11 Mooring Interference? Current and Sensor Motion Measurement Records Correlation between sensor position and bad data Relation between sensor pitch-roll and depth change Characteristics of 6x20 ATON buoy Orientation of clamparatus bails w.r.t mooring bridal Orientation of buoy w.r.t current direction Characteristics of clamparatus and Aquadopp Sensor Beam orientation and sensor platform coordinates Pitch, roll and depth changes

12 Sensor Position During Periods of Anomalous Data Avg sensor position data, pitch, roll, depth, & heading during flood tide Scatter plots indicate correlation between bad data and sensor position/orientation

13 Depth Changes Heitsenrether 2008 Nortek User s Symposium Geometric analysis of sensor s motion indicates Aquadopp not configured optimally during Galveston Bay test During times of anomalous data sensor was most likely upstream and rolled into a position of possible mooring interference

14 Top View of Buoy 6x20 ATON Components Line connecting 2 mooring lines always 90 relative to clamparatus bail Bridal connecting mooring chains can be on either side of bottom weight Bridal most likely to be up stream of current Buoy roll relative to current direction can vary

15 Orientation of Mooring Bridal Bridal connecting mooring chains can be on either side of bottom weight

16 Orientation of ATON Relative to Currents F wind F top + F wind > Current Direction F bottom F chain F top F bottom > F top + F wind F bottom Depending on balance of forces, buoy roll relative to current direction can vary

17 Potential for Mooring Interference in Beam Path USCG Portsmouth Buoy Yard Observations of 6x20 s to understand geometry and possible range of motion of mooring components

18 Based on geometry of setup, mooring interference in beam path is possible for multiple configurations when transducer is on the same side as bridal. 2 1 X Y 2 Y 1 X

19 Short Term Fix for Mooring Interference Mooring interfering with beams is highly unlikely if ADCP on opposite side of mooring bridal On 6x20 ATON, clamparatus modified to allow deployment on either lifting eye; corner angled to fit around structures on opposite side Modified clamparaus used for 2 successful PORTS deployment in Gulfport, MS, May 2008

20 Underwater camera mounted on pole determined position of ATON mooring bridle.

21 Mooring Chain Successful in varying optical conditions Chesapeake Bay and Gulf of Mexico Base of ATON Buoy

22 Long Term Fix for Avoiding Mooring Interference Standard Transducer Head Custom Slant-Beam Transducer Head

23 Summary and Continuing Work Addition of ATON ADCP systems to NOAA PORTS provides current info in navigation channels System is unique and easily deployed, complies with USGS requirements. Many successfully deployments completed, however, some issues have led to development of system improvements. Short-term fix for mooring interference - under water camera recon and modified clamparatus Long term fix - development of custom slant beam transducer head Test unit recently acquired; tow tank and boat tow testing in Jul 09 Improved communications methodologies for ATON ADCP currently in-work data telemetry via GOES, Iridium