1. Wind and density driven flow along the Texas-Louisiana continental shelf Rob Hetland Zhaoru Zhang Martino Marta-Almeida Xiaoqian Zhang

2. The Gulf of Mexico has a number of environmental problems: Karenia brevis Photo credit: Florida Fish and Wildlife Conservation Commission NASA MODIS May 24, 2010 Harmful algal blooms Oil spills Bottom hypoxia LUMCON - July 24-27, 2012 And the list goes on....

3. Series of Models: Wind-driven surface current predictions for entire gulf – focused on TX shelf Louisiana shelf wind/buoyancy driven flow TX/LA shelf wind/buoyancy driven flow NEXT TALK

5. Animation courtesy Chris Barker (NOAA R&R)Surface currents provided by Rob Hetland and Steve Baum, TAMUFunding by the Texas General Land Office TABS program

6. B D F J K N R V W

7. ~3 hr lag ~12 hr lag

8. Four examples of non-summer convergent events

9. WindCurrents

10. No river case

11. Wind Obs. Model 2009200610 year mean

12. Climatological winds over the Texas-Louisiana shelf

13. Non-summer mean Summer mean Cho et al. (JGR, 1998) Seasonal surface currents from LATEX moorings

15. JFM mean density cross-section JFM mean along-shore currents Thermal wind balance currents u | z=h =0 Along-shore currents are nearly in thermal-wind balance

17. Meade et al. (1995) USGS Circular 1133

20. Low flow year

21. Medium flow year

22. High flow year

23. Every third grid point shown HYCOMIASNFS (subset) NGOM

24. Parent modelsNested modelsCLMDataset Model salinity skill Red = good (within 10% of max skill)

25. Parent modelsNested modelsCLMDataset Model skill Red = good (within 10% of max skill) 19/4621/46 10/215/21

26. where

27. Perturbed simulations (±5% wind and rivers)

28. Noise at a point on the shelf Domain average noise

29. Conclusions: Nesting improves model skill, but it does not appear to matter which model is used*. Although there is significant unpredictable, small-scale eddies at the submesoscale, the large scale plume structure is reproducible in a model without data assimilation. *For salinity, anyways...

30. July 25, 2002 Cross-shelf transect Oxygen (colors) Salinity (contours) 92.75˚W (i-line) Data from N. Rabalais

31. Measured areal extent, 1993 Different respiration formulations represent hypotheses about the processes that deplete oxygen. The combination of respiration and flow field determines where hypoxia is most often found. Hetland and DiMarco (2008)