OBSERVATIONAL VALIDATION OF AVIAN RADAR SYSTEMS

1. Wendell Bunch Edwin Herricks, PhD OBSERVATIONAL VALIDATION OF AVIAN RADAR SYSTEMS

2. Introduction • Existing airport surveillance radars • Designed for air and ground traffic control • Not readily adaptable for wildlife purposes • Avian radar systems • Digital processing added to COTS marine radar and optimized for bird detection • X-band and S-band • New technology w/few users and no airport experience

3. CEAT Performance Assessment • Multiple year program assessing avian radar systems at civil airports • Initial efforts intended to understand radar physics/system abilities • A critical issue is validation of capabilities of avian target detection and tracking • Visual observation of birds

4. CEAT Validation Efforts • Address ground-truth issues • Validate in airport settings • Use target rich environment of Whidbey Island to conduct long term observations • Coordinate with IVAR efforts • Evaluate methods

5. Issues identified in ground-truth efforts and • validation studies • observers challenge radar detection • radars challenge observers and methods • visualizing the beam coverage (height and • width) • locating specific targets • judging distance and altitude

6. Location: NAS Whidbey Island WA

7. Primary sensor X-band radar 3cm wave length

8. Method of visual observation • 30X spotting scope aligned to true north • radar computer and watch synced ± 1 sec • data collected in high and low clutter areas • viewing angles separated by 20 degrees • two view samples at each angle, high/low • 20 second sample periods • data collected: date/time, family or specie, number of birds, general direction of travel, bearing target observed • time stamp when target on vertical center of spotting scope

9. Findings • Detection Issues: • Aspect/RCS • Aspect -relation of the target to radar beam • RCS - effective target area, changes with aspect • RCS must exceed level of clutter

10. Clutter: Ground and Sea • Undesirable radar returns • Sea clutter – tracks short high speed • Wind speed/direction determined effect

11. Ground and Sea Clutter

12. Effects of sea clutter on tracking

13. Detection Issues: cont. • Position Relative to Clutter • gulls: >20, <20, <5 • Large sea ducks: CEAT and IVAR • RCS? • Flight Behavior • constant heading = consistent tracking • un-predictable flight challenges all radar • shadowing in flocks • Duration of Flight • must be long enough

14. Detection Issues: cont. • Weather • rain/snow hinders detection and tracking • can generate large numbers of detections and tracks • tracks of short duration with speeds similar to birds

15. Observation Issues • weather conditions hindered use of spotting scope in strong winds/rain • range to targets difficult to estimate • limited to daylight hours

16. Validation Methods • Requirements to validate target time, direction of travel, bearing, within beam dimensions for the bearing • archived radar data replayed • two examples

17. Surf scoter - 305

18. Bonaparte’s Gull - 601

19. Conclusions • Avian radar capable of tracking bird sized targets • Researchers have shown radar can track movement over larger areas than visual observations • Research needed: potential to monitor bird activities while evaluating limitations of location and radar physics • NAS Whidbey research has shown limitations with the current technology

20. Conclusion cont. • Factors Compromising Detection • target aspect • target size • flight behavior • target position relative to clutter • overall clutter environment • weather

21. Conclusions cont. • Use of Avian Radar Systems • careful evaluation of clutter levels to ensure tracking in desired area • will require some level of validation • more complex environments = more validation

22. QUESTIONS?