1. WORKSHOP ON HYPOXIA IN NARRAGANSETT BAY OCTOBER 2, 2006 - FIELDWORK IN SUPPORT OF HYDRODYNAMIC MODELS 1)Large Scale CTD Surveys - Deacutis, Murray, Prell 2)Moored + Vessel-based Circulation Studies – Kincaid, Bergondo 3)Towed Undulator Surveys - Ullman 4)Moored Vertical Profilers – Vaudrey, Kremer

2. “The Day Trippers” – Large Scale CTD Surveys 2006 Survey Dates : Neap Tide Surveys : 6/6/06, 7/6/06, 8/3/06,8/31/06 Spring Survey : 8/11/06

7. PRS 07 PRN 1 http://www.geo.brown.edu/georesearch/ insomniacs/

11. Deanna Bergondo & Chris Kincaid – Bottom Mounted ADCP Sites

12. Providence River Bottom Mounted ADCPs Influenced by wind

13. Providence River Bottom Mounted ADCPs Outflow Inflow

14. Providence River Bottom Mounted ADCPs Outflow Inflow

15. Providence River Bottom Mounted ADCPs

16. Summary Bottom Mounted Results EYC shallows – average surface flow to North Influenced by prevailing winds Two layer flow in EYC and Conimicut channels Southward winds enhance return flow Northward winds stall return flow

17. Physics: Observations & Modeling Acoustic Doppler Current Profilers - C Kincaid Bottom mountedShip mounted Data coverage: Excellent temporal Poor Spatial Data coverage: Good spatial Poor Temporal

18. Results: Providence River Prevailing outflow - shallow, western side shipping channel Prevailing inflow - deep, eastern side shipping channel Series of weak, recirculation eddies in shallow edges Strong wind-induced water column response/reorientation Physics: Goal to characterize circulation, mixing, flushing, transport, etc Methods are Observations & Modeling

19. Bay Circulation Data Summary: Model boundary conditions 18 underway surveys: summer vs winter

20. Bay Circulation Data Summary: Model boundary conditions 1.5 years of BM-ADCP data 18 underway surveys: summer vs winter

21. Bay Circulation Data Summary: Model boundary conditions Summer: strong long-shore flow bottom surface

22. Bay Circulation Data Summary: Model boundary conditions Summer: strong long-shore flow Summer: prevailing (depth-averaged) counter-clockwise flow

23. Bay Circulation Data Summary: Model boundary conditions Summer: strong long-shore flow Summer: prevailing (depth-averaged) counter-clockwise flow (CCF) Dominant exchange through mouth

24. Bay Circulation Data Summary: Model boundary conditions Strong wind-induced exchanges

25. Bay Circulation Data Summary: Model boundary conditions Strong wind-induced exchanges SE winds enhance CCF, trigger RIS intrusion Wind Extent of counter

26. Bay Circulation Data Summary: Model boundary conditions Strong wind-induced exchanges SE winds enhance CCF, trigger RIS intrusion Wind ? ? Extent of counter Spatial extend of CCF

27. Bay Circulation Data Summary: Model boundary conditions Winter: Strong 2-layer flow RIS water from southwest Extent of counter

28. Bay Circulation Data Summary: Model boundary conditions Extent of counter Mt. Hope Bay circulation/exchange /mixing study. ADCP, tide gauges (Deleo, 2001) Bay-RIS exchange study (98-02)

29. Bay Circulation Data Summary: Model boundary conditions Extent of counter Mt. Hope Bay circulation/exchange /mixing study. ADCP, tide gauges (Deleo, 2001) Bay-RIS exchange study (98-02) Narragansett Bay Commission: Providence & Seekonk Rivers

30. This project: Mid-Bay focus Extent of counter Mt. Hope Bay circulation/exchange /mixing study. ADCP, tide gauges (Deleo, 2001) Bay-RIS exchange study (98-02) Narragansett Bay Commission: Providence & Seekonk Rivers Summer, 07: 4 month deployment (Outflow pathways)

31. This project: Mid-Bay focus Extent of counter Mt. Hope Bay circulation/exchange /mixing study. ADCP, tide gauges (Deleo, 2001) Bay-RIS exchange study (98-02) Narragansett Bay Commission: Providence & Seekonk Rivers Summer, 08: Deep return flow processes Outflow, inflow, exchange between Bay sub-regions

32. High-Resolution Surveys of Hydrography, Currents, and Vertical Mixing Dave Ullman (GSO) Objectives: Provide high resolution sections of physical and biological parameters for assessment and calibration of hydrodynamic and ecological models. Estimate vertical turbulent mixing rates. Methodology: Towed undulating vehicle measuring hydrographic parameters and turbulent microstructure. Shipboard ADCP measuring currents.

33. Towed vehicle sensors: Temperature Conductivity Pressure Oxygen concentration Chlorophyll fluorescence Nitrate concentration Microscale conductivity (turbulent mixing) Towed Undulating Vehicle Acrobat Microstructure Sensors. Ship-mounted ADCP: Velocity profiles

34. Along-channel sections suggest dynamical importance of the “narrows” at Conimicut Conimicut Rapid variability in depth of thermocline, halocline over short distances.

35. Intensive Sampling, Conimicut Region Conimicut Pt. Coordinate origin Carried out repeated tows over approximately a full tidal cycle along black line shown on bathymetry map: August 11, 2005 (Neap): 18 lines August 18, 2005 (Spring): 20 lines

36. Flood Tide Eddies Aug. 11, 2005 early flood Clockwise eddy in near-surface current (blue vectors) Extends down to ~7 m depth. East Component (m/s) North Component (m/s) Commonly observed just south of narrows at Conimicut on flood tide. Cause as yet unknown. Potential to be an important horizontal dispersal mechanism. Conimicut south

37. Signature of Eddies in Hydrographic Fields? East Component (m/s) North Component (m/s) T S O2O2 Chl-a NO 3 Doming of isolines in upper water column in eddy region. ADCP Acrobat Eddy

38. Vertical Mixing Estimates Micro-conductivity Sensor on Acrobat: Measures conductivity at scales of O(1cm). Sampled at 1024 Hz. Methodology: Compute variance of conductivity gradient. Apply corrections for salinity contributions and sensor response to get temperature gradient variance. Dissipation rate of temperature gradient fluctuations (  T ) is proportional to variance. Estimate vertical temperature gradient ( ) from CTD sensors on acrobat. Turbulent thermal eddy diffusivity computed from  T and gradient:

39. Example Vertical Diffusivity Section Colors: log 10 (K T ) (m 2 /s) Lines:  t (kg/m 3 ) From a single tow on Aug. 18, 2005. Spring tide conditions, ebb flow. Conimicut narrows: K T ~10 -4 - 10 -3 m 2 /s (strong vertical mixing) south

40. Tidally Averaged Vertical Turbulent Diffusivity Aug. 11 (neap)Aug. 18 (spring) Turbulent mixing appears to be enhanced in the Conimicut area. Colors: log 10 (K T ) (m 2 /s) Lines:  t (kg/m 3 ) Slightly stronger mixing on spring tides: Neap average = 2.9x10 -5 m 2 /s. Spring average = 3.5x10 -5 m 2 /s.

41. Future Interaction with Modelers Compare observations to ROMS model output: Tidal eddies  Present in model?  If so, what is the mechanism by which they form? (Examine model momentum balance)  How do they affect horizontal property transport? Vertical mixing  How does magnitude of model vertical mixing (computed by turbulence closure submodel) compare with observed mixing rates?  Can observations be used to tune model turbulence parameterizations? Stratification  Is model vertical stratification of similar magnitude as observed?

42. Profiling Units 4 Locations Field’s Point Bullocks Reach Buoy east of Conimicut Point Light Warwick Neck Sampling Set-Up sample every 15cm in the vertical 1 profile every 3 hours deployed for ~ 2 weeks 3 Deployments June, July, September J. Kremer & J. Vaudrey

44. depth off the bottom (m) Temperature Salinity Dissolved Oxygen oCoC ppt mg/L day of deployment (day 1 = 8/31/06) east of Conimicut Light

46. depth off the bottom (m) Temperature Salinity Dissolved Oxygen oCoC ppt mg/L day of deployment (day 1 = 6/27/06; day 16 = 7/13/06) Warwick Neck

48. END

50. Grid Resolution: 100 m Grid Size: 1024 x 512 Vertical Layers: 20 River Flow: USGS Winds: NCDC Tidal Forcing: ADCIRC Open Boundary Hydrodynamic Model

51. DYE_08 DYE_02 DYE_03 DYE 05 DYE_01 DYE_09 DYE_07 DYE_06 DYE 04 Modeling Exchange Between Biological Model Grids

52. Dye Experiment

55. Model-Data Comparison Salinity - Phillipsdale Salinity (ppt) Time (days) Model Data

56. Model-Data Comparison

57. Seekonk River Bottom Mounted ADCPs

58. Goal: Understand chemistry, biology and physics of the Bay, at all points in the Bay, for all time

59. Goal: Understand chemistry, biology and physics of the Bay, at all points in the Bay, for all time Goal 2: Understand coupled processes given any combination of external forcing conditions

60. Initial Conditions Forcing Conditions Output Equations Momentum balance x & y directions:  u + v  u – fv =  + F u + D u  t  x  v + v  v + fu =  + F v + D v  t  y Potential temperature and salinity :  T + v  T = F T + D T  t  S + v  S = F S + D S  t The equation of state:  =  (T, S, P) Vertical momentum:  = -  g  z  o Continuity equation:  u +  v +  w = 0  x  y  z Numerical Model ROMS Model Regional Ocean Modeling System

61. Narragansett Bay Commission: Providence & Seekonk Rivers 3 month BM-ADCPs

62. Narragansett Bay Commission: Providence & Seekonk Rivers 3 month BM-ADCPs Underway ADCPs