Table 9-5 



Averaged Zero Offsets for Supertank Deployment 





Sensor Pair 



A 



B 



C 



D 



BASS 1 



0003 (3) 



0000 (0) 



FFFFH) 



0000 (0) 



BASS II 



0001 (1) 



0000 (0) 



FFFE (-2) 



0001 (1) 



BASS III 



0000 (0) 



0003 (3) 



FFFF (-1) 



0000 (0) 



BASS IV 



FFFE (-2) 



FFFD (-3) 



FFFC (-4) 



0002 (2) 



A,B,C,D = integer velocity data values from the four sensor pairs 



of each BASS array 

 A , B , C , D = zero offset values corresponding to A,B,C,D 



In the above, the constant multiplier is due to trigonometric conversion as well 

 as the value of velocity in cm/sec per bit of integer data. 



As with the ACP data, it is possible to arrange the velocity data into aver- 

 aged profiles or time series over the 15-min time period. Both of these yield 

 a different kind of information; a time series trace of velocity components 

 reflects the instantaneous wave characteristics and an average profile shows 

 net fluid motion during the period. Because not all velocity data for each 

 15-min period are intact (there may only be two out of four points in a 

 particular profile), the velocity data which are intact will be presented as a 

 time trace. An example of the interpreted velocity data for the w-velocity 

 component, which is along the channel and positive offshore, at a depth 

 parallel to the sampling point of the third BASS sensor down from the top of 

 the instrument mounting, is shown in Figure 9-11. 



Pressure sensor. Each 1-sec ACP data record contains 2-Hz pressure data 

 which is stored in 2-byte places within the first 17 bytes of the record 

 (Equation 9-1). The conversion of the data to units of pressure is easy, due to 

 the linearity of the instrument. Thus the integer-valued data, represented as 

 hexadecimal digits from 00 to FF, are converted by multiplying by a constant. 

 The value is 0.0125 psi (0.086 kPa) per bit or 0.88 cm of water per bit. The 

 data can be stored in a separate data file as a time trace, and a sample of data 

 is shown in Figure 9-12 for wave run A0608A and the same 15-min period 

 used for average ACP concentration and BASS velocity values. 



Summary of data characteristics 



Eight wave run data files have been selected as representative sample files 

 collected by OSU at SUPERTANK. These files comprise at least one of each 

 type of wave run spectra, i.e., one each of broad-banded random waves, 

 narrow-banded random waves, and monochromatic waves. There are two 



Chapter 9 The Ohio State University Measurements 



177 



