1. SBI-2005 1/13 Vagarities of Velocity Variations Andreas Muenchow Graduate College of Marine Studies University of Delaware http://newark.cms.udel.edu/~sbi Chris Linder, WHOI

2. SBI-2005 2/13 transmits sound then listens for echoes sound interacts with ~ 2-cm particles (zooplankton) backscattered sound received by transducers Velocity: Radar + Sonar Radar send and receive electromagnetic waves (radio, police) Sonar send and receives acoustic waves (sound, whales) Same physics. 75-kHz transducers:

3. SBI-2005 3/13 Zooplankton diel vertical migrations? ADCP backscatter Beaufort slope Oct.-2004 ~10 m/hr ~0.28 cm/s

4. SBI-2005 4/13 Aagaard (1984) 

5. SBI-2005 5/13    cm/s Beaufort Slope Currents 2003

6. SBI-2005 6/13 Beaufort Slope Currents 2004  

7. SBI-2005 7/13    t0t0 t 0 +16 hrs eastwest L Barrow Canyon, Sept. 1993 Synoptic velocity observation in Barrow Canyon, Alaska (view is to the south): The flow scales with the internal deformation radius, L~5-km. Münchow and Carmack (1996)

8. SBI-2005 8/13 Barrow Canyon 2004  BarrowChukchi

9. SBI-2005 9/13  Coastal Circulation off Wainwright, Sept.-12, 2004 as measured by75-kHz acoustic Doppler current profiler Flow is in the opposite direction from what is the canonical view of fresh Bering Sea water entering the Arctic via Barrow Canyon

10. SBI-2005 10/13 I II III Eddies in the Arctic Sept.-22, 2004 IIIIII USCGC Healy 75-kHz ADCP L D

11. SBI-2005 11/13 The only real SBI-ADCP Survey, Sept.-22/24, 2004 55-m100-m red dots are XBT drops (Pickart and Kosro) Chukchi shelf Chukchi shelf

12. SBI-2005 12/13 Warm, fresh water flows northward against gale force winds in channel while cooler and saltier waters flow southward with the winds. Central Channel Chukchi Shelf 8-m temperature 8-m salinity

13. SBI-2005 13/13 How to best distribute ADCP data? How to best “explore” ADCP data? file:///Users/a2/0309_pro/os75/www0309/index.html Conclusions: ADCP velocity data challenges conventional perceptions of Arctic shelf and slope circulations (strong vs. weak local forcing); SBI did not resolve velocity and physical property fields properly in time-space domain (with the exception of WHOI moored array) Questions:

14. SBI-2005 14/13 ADCP Processing: Sorting and Screening Single Ping Data water track relative to ship (true East, unsorted) water track relative to ship (true North, unsorted) water track relative to bottom (true North, sorted) water track relative to bottom (true East, sorted) Ensemble average Ensemble

15. SBI-2005 15/13 ADCP Calibration-1: Comparing Velocity Components … looks good, but can’t tell how good … Transducer misalignment in x-y plane: 44.1 deg. x-z plane: 1.17 deg. y-z plane: -1.10 deg. Scaling by 1.021158

16. SBI-2005 16/13 ADCP Calibrations-2: Difference of ADCP-GPS Velocity Components North East HistogramIntegrated Histogram

17. SBI-2005 17/13 Barotropic Tidal Currents 5-km data assimilation 8 constituents, 2-week rms from Erofeeva et al. (2004)