ATON System Workshop ATON System: Real-time current measurements from Coast Guard navigation buoys in ports, bays and the coastal ocean Aid-to-Navigation = ATON
ATON System Workshop Outline: Overview of the ATON System Coast Guard approved mounting system Real-time telemetry systems Data quality evaluation
ATON System Motivation Motivation: Shipping safety Search & rescue Spill response Resource management Recreational boaters Before ATON System, current measurements were limited to cable length and not available in navigation channels
Underwater Cable Difficulties NOAA PORTS: Narragansett 2 cables (1 mile) Houston 5 cables (3 miles) Delaware Bay 4 cables (4 miles) San Francisco 14 cables (11 miles)
ATON Overview ) ) Boston Harbor NOAA PORTS Data sent to office
The ATON System Electronics Box Antenna ATON Clamparatus Aquadopp Profiler
The Clamparatus Developed by Ocean Science in collaboration with NOAA & NortekUSA Not to Interfere Requirements: Deployed/recovered with buoy on station Removed prior to ATON Service Similar metals & coloration Minimal alteration of buoy profile & characteristics
The Clamparatus Clamparatus Features: Package weighs ~200 lbs Deployable from small boat Collect data in navigation channels No divers required No underwater cable required
The Challenge: Compass Calibration ATON buoy is large magnetic mass At-sea calibration means tilt & roll
The Tests: Compass Calibration Use steel pipe to approximate ATON magnetic field Test calibration routine Uncalibrated Calibrated
Compass Calibration The Solution: New compass calibration routine for soft & hard iron Reads real-time tilt and roll data Software gives estimated error value after calibration Uncalibrated Calibrated NEW Cal
Options & Applications External Analog Sensors Turbidity Fluorescence Dissolved Oxygen CTD Other External Sensors Oil Slick Detector Harmful Algal Bloom Fecal Coliform Bacteria Underwater Acoustic Modems Data telemetry Wave gauges Tidal Height GPS Water Level Acoustic Depth Sounding Acoustic Modem
Telemetry Options 2-way Communications/Minimal Power Options: Line of sight radios (900 MHz and 2.4 GHz) o Pros No service fee o Limitations Local base station; secondary comms relay IP Modems (CDMA cell network) o Pros Static IP address o Limitations Monthly service fee; limited coverage Iridium (satellite) o Pros Stand-alone system; global coverage o Limitations Monthly service fee GlobalStar (satellite) o Pros Stand-alone system; coastal coverage o Limitations Monthly service fee
Data Quality Evaluation ATON surface buoy compared with bottom mounted profiler Comparisons in Chesapeake Bay and Gulf of Mexico Analysis by Dr. Kate Bosley - NOAA
Speed Comparison Speeds compare very well, with no obvious bias Mean difference ~ 3 cm/s (0.06 knots)
Speed Comparison Speeds compare very well, with no obvious bias Mean difference ~ 3 cm/s (0.06 knots)
Direction Comparison Flood and ebb occur together, with similar time & direction characteristics. Largest differences occur at the change of tide when the currents are weak and variable. black = Bottom Mount red = ATON blue = difference
Direction Comparison As with speed differences, there is no obvious bias.
Direction Comparison Difference in direction between the Bottom Mount and ATON clearly decreases with increasing current speed Speed > ½ knot Mean dir diff = 9 deg
Direction Comparison Difference in direction between the Bottom Mount and ATON clearly decreases with increasing current speed Speed > ½ knot Mean dir diff = 9 deg Speed > ¼ knot Mean dir diff = 11 deg Comparable to measurements from non-magnetic surface buoy
ATON Locations Chesapeake Bay, VA (NOAA PORTS) Northern Gulf of Mexico (NOAA PORTS) Freeport, TX (Pilots association) San Francisco Bay, CA (SFMX) NY Harbor, NY (Stevens Institute) How can the ATON System meet your research and operational needs?