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GPS-Cellular Drifter Technology for Coastal Ocean Observing Systems Carter Ohlmann University of California, Santa Barbara Andy Sybrandy Pacific Gyre Inc.

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Presentation on theme: "GPS-Cellular Drifter Technology for Coastal Ocean Observing Systems Carter Ohlmann University of California, Santa Barbara Andy Sybrandy Pacific Gyre Inc."— Presentation transcript:

1 GPS-Cellular Drifter Technology for Coastal Ocean Observing Systems Carter Ohlmann University of California, Santa Barbara Andy Sybrandy Pacific Gyre Inc. drifter descriptive summary of data importance in coastal ocean observing systems

2 Argos: 100 m spatial resolution Position ~5 times each day communications costs: ~$300 drifter-month Typical Open Ocean Drifter

3 High-Resolution, Recoverable “Microstar” (mfg. by Pacific Gyre Inc.) GPS position accurate to ~5 m position updates as often as every minute (variable) data transmitted via Mobitex™ digital, data-only, cellular network near real-time data and thus recoverable communications costs: O($10) drifter-month range limitations (~50 km from coast)

4 drag-area-ratio = 41.3 known slip (< ~2 cm s -1 )

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6 Matlab based near real-time tracking software to facilitate drifter management and retrieval.

7 site of large natural hydrocarbon seep

8 ~20 days ~10 drifters/day ~300 tracks inconsistent with wind forcing onshore nearshore Mean Wind: 2.4 cm/s

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10 Drifter data show a variety of small-scale processes in the coastal ocean Validation of HF radar data with current meter observations are inaccurate due to consideration of disparate scales How should HF radar data be interpreted?

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12 Comparison of drifter and HF radar velocities

13 Drifter vs. HF radar velocities over the SBC inner-shelf HF radar data: - hourly - 1 or 2 km grid - 10 cm/s accuracy Much of the quoted discrepancy in HF radar is due to differences in resolution

14 Total separation: 0.5 km after 2 hrs (7 cm/s) 1.5 km after 4 hrs (10 cm/s) HF radar - drifter trajectories

15 drifter-HF radar drifter-drifter

16 Summary: new drifter technology for coastal regions provides economical high-resolution (meters, minutes) data instrument error and sub-grid-scale information in HF radar data separation rate between drifters and HF radar trajectories is near 10 cm/s (relative dispersion is 4 cm/s) and directional biases exist Routine drifter releases for interpretation of HF radar data should be part of coastal ocean observing systems www.drifterdata.com


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