PART II: DATA COLLECTION 



5. The general requirements and schedule for each task in the program 

 were prescribed in the Management Plan for the Model Enhancement Program. 

 Data collection was divided into three subtasks: tidal, in situ current, and 

 current profile data. Data were collected for varying intervals between 



10 June and 14 October 1987 (Table 1) . Measurement intervals for each subtask 

 varied, but deployment times were nested to provide a period of simultaneous 

 data from all three elements from 6 to 14 August 1987. Requirements for the 

 final data sets and the instrumentation and techniques used to obtain them are 

 discussed in this section. 



Tidal Data 



Requirements 



6. The requirement of the tidal data subtask was to obtain time series 

 of water surface elevations at two outside and two inside locations for a min- 

 imum of 90 days. Each data set was to be a continuous record of elevations 

 relative to a Mean Lower Low Water (MLLW) datum at 6-min intervals with an 

 accuracy of at least 0.05 ft.* 



7. Figure 2 shows the positions of the tidal measurement sites; geo- 

 graphic coordinates and depth of each measurement site are listed in Table 1. 

 Method 



8. For the offshore sites, potential cable runs of several miles made 

 hard wiring of power and signal to shore uneconomical. Erecting structures in 

 water depths of 60 to 100 ft would be very expensive, and proximity to the 

 shipping lanes and the heavy traffic volume precluded platforms and buoys 

 because of the risk of collision. The remaining option was bottom-mounted 

 pressure transducers with self-contained power and data storage capability. 

 This option allowed a wide latitude in positioning and reduced the risk of 

 unintentional and deliberate interference. The same approach was used at 

 sites in the harbor for consistency of deployment/recovery techniques and data 

 format . 



* A table of factors for converting non-SI units of measurement to SI 

 units is presented on page 4. 



