Title: Vertical Shear and Turbulent Mixing in Partially Mixed Estuaries

Working title:  effects of wind and tidal mixing and straining on near bottom and water column stresses in partially mixed estuaries

I.     Introduction - York River Synthesis

a.      Physical setting and properties of the York River

b.     Insights from past experiments – published

                                          i.     Early work

1.     Kiley (1973) (wind and current in the York River)

2.     Haas (1977) (spring-neap cycle and stratification)

3.     Hayward (1982) (horizontal salinity reversals and destratification)

                                        ii.     Later studies

1.     Huzzey and Brubaker (1988) (lateral differences)

2.     Sharples, Simpson and Brubaker (1994) (periodic stratification)

                                      iii.     Recent work

1.     Simpson et. al. (2005)

2.     Brasseur et. al. (2005) (Isabel)

3.     Scully and Friedrichs (2005)

c.      Additional information from past continuing and unpublished data sets

                                          i.     Acrobat surveys (2003-2004)

                                        ii.     CBNERR data (since 1990's)

                                      iii.     MS 502 data (since 2001)

                                      iv.     Gloucester Point surveys (March 2005)

II.     A method for estimating eddy viscosity/diffusivity using ADCP backscatter

a.      Calculating and calibrating ADCP backscatter to suspended sediment

                                          i.     Using only the absorption/scattering properties of water

                                        ii.     Using an iterative method to include the absorption due to sediment as well.

                                      iii.     At what sediment levels does the second method return appreciably better calibrations?

b.     Method for determining eddy diffusivity from backscatter using a first order approximation of the conservation of mass equation.

c.      Results from Chesapeake Bay ETM experiment (BITMAX) 2001-2002

d.     Problems with method and a discussion of settling velocities (Sanford et al., 2005)

III.     A comparison of turbulent parameters with an emphasis on different techniques using the ADCP

a.      The variance method used to determine eddy viscosity from a moored ADCP (Monismith and Stacey (1999) Simpson et. al.(2005), Williams and Simpson (2003)

                                          i.     Validation of the method against a bottom mounted ADV (Simpson et. al. (2005) York River 2002)

                                        ii.     Comparisons of 600kHz and 1200 kHz ADCP data from March 2002 York River considering the tradeoff between bin size and noise.  At what vertical bin size are the bins larger than the measurable eddies and the method becomes invalid?

                                      iii.     Use of the variance method on longer term data sets from Gloucester Point, 2006 and additional validation using a bottom mounted Nortek Vector ADV.

b.     Estimating eddy diffusivity from ADCP's

                                          i.     Using the backscatter method on data from both shipboard and fixed ADCP's from the March 2002 York River experiment.

                                        ii.     Using the backscatter method to find spring-neap differences in eddy diffusivity at Gloucester Point, spring and summer 2006

c.      Combining the eddy viscosity and eddy diffusivity measurements to determine settling velocity

                                               i.     Validate settling velocities using information from the Owen tube and LISST data

                                             ii.     Using calculated settling velocities, find a linear relationship between eddy viscosity and eddy diffusivity. 

                                           iii.     Assuming a 1:1 relationship between the two, calculate settling velocities in the bottom boundary layer.

IV.     The effect of wind on vertical turbulence and horizontal currents in a partially mixed estuary

a.      Intensive study days from the March 2002 VIMS/Wales experiment.

                                               i.     Examining short term wind effects using data from SCAMP, shipboard ADCP, and moored ADCP's during the 2002 York River Clay Bank experiment.

b.     Overall wind effects from time series data at fixed ADCPs

                                               i.     During the 2002 York River Clay Bank experiment, combining ADCP based measurements with additional stratification and vertical and horizontal density gradient information

                                             ii.     Use of wind, wave and current data from Clay Bank and Gloucester Point to determine the fetch and speed necessary for wind mixing through waves to overcome any straining effect the wind might have.

                                           iii.     The feasibility of measuring waves and turbulence concurrently using a single RDI ADCP.

                                            iv.     Considerations of short time scale wind effects and steady state vs. non steady state conditions.

V.     Modeling tidally varying vertical structure of velocities and stresses in the water column using GOTM

a.      Using the variance method measured TKE from the Gloucester Point 2006 study, examine the turbulence stability functions and closure schemes for the 1-D GOTM model.

b.     Using only low or no wind time periods, the measured TKE will be simulated using GOTM.  The model can then used to investigate different conditions of wind and current flow regimes and compare these with observations under varying conditions of wind, current, riverflow and waves.