SkyTEM at the extended Test site

1. Validating SkyTEM Data Against Ground-based TEM Data at the Danish National Test Site by Upward Continuation • Nikolaj Foged*, A.V. Christiansen**, and Esben Auken**HydroGeophysics Group, Department of Earth Sciences, Aarhus University, Denmark • **Geological Survey of Denmark and Greenland - GEUS

2. SkyTEM at the extended Test site instrumentation • Super low moment (SLM), 45 000 Am2 • High moment (HM),180 000 Am2 • SLM + HM is applied sequential z-receiver coil x-receiver coil inclinometers,pitch and roll Laser altimeters z-receiver Transmitter frame

3. 1 km SkyTEM, extended Test site - dataset • Altitudes: 15 m, 25 m, 35 m • Four repetitions per line and altitude. Total of 12 repetitions per line • Standard processing and inversion is applied • Sounding/model spacing: 20 m • Independent LCI-inversion of each line repetitions

4. Validation of SkyTEM - model space

5. Validation of SkyTEM - model space • Repeated line, altitude 15 m Line1A Line 1B

6. Validation of SkyTEM - model space • Repeated line, altitude 15 m Line1A Line 1B • Background: SkyTEM, Line 1A • Front bars: SkyTEM, Line 1B

7. Validation of SkyTEM - model space • Repeated line, altitude 15 m and 35 m 15 m 35 m

8. Validation of SkyTEM - model space • Repeated line, altitude 15 m and 35 m 15 m 35 m • Background: Altitude 15 m • Front bars: Altitude 35 m

9. Validation of SkyTEM - model space • Comparison with ground based TEM: Altitude 15 m SkyTEM Ground TEM

10. Validation of SkyTEM - model space • Comparison with ground based TEM: Altitude 15 m • Background: SkyTEM, altitude 15 m • Front bars: Ground based TEM

11. Validation of SkyTEM - model space • Comparison with ground based TEM: Altitude 15 m, 35 m 15 m 35 m • Background: Altitude 35 m • Front bars: Altitude 15 m • Background: SkyTEM, altitude 15 m, 35 m • Front bars: Ground based TEM

12. Validation of SkyTEM - data space

13. 115 ms Repeatability, 15 m, data space Altitude ~15 m Raw data

14. Repeatability, 15 m, data space Altitude ~15 m 115 ms Raw data

15. Repeatability, 15 m, data space Altitude ~15 m 115 ms Raw data

16. Repeatability, altitude 15 m Altitude ~15 m 115 ms Raw data

17. Data, 23.1 m Upward continuation to a nominal height • How ? Calculate correction factor per time gate Model Data, 25 m Forward 23.1 m, 25 m Inversion Apply correction factor to data

18. Upward continuation of ground based TEM • To compare/evaluate the SkyTEM system with the ground based TEM in data space • How ? SkyTEM refe-rence responce Ground TEM Reference model Forward, SkyTEM system, 25 m Inversion

19. Repeatability, nomial altitude 15 m Nominal altitude 115 ms Raw data

20. 14 ms 115 ms Repeatability, nomial altitude 15 m 3.6 ms

21. Repeatability, nomial altitude 15, 25, 35 m 115 ms

22. Match to reference section, 15, 25, 35 m Reference response 115 ms Reference response Reference response

23. 14 ms 115 ms 3.6 ms Match to reference section, 15 m Reference response Reference response Reference response

24. Conclusion • Calibration on the National test site insures consistence mapping results • Validation of the SkyTEM system • Repeatability - same altitude • Repeatability - different altitudes • Match to ground based TEM / reference section • Also validation of: • the detailed and carefull processing scheme • the high precision inversion code (em1dinv) • Validation is demanded for any TEM-system to participate in the Danish groundwater mapping campaign

25. All data to nominal height of 25 m