PART III: DATA ANALYSIS 



Tidal Data 



50. Raw data from the recovered tide gages were processed using 

 SEA11.F0R, a program which converts raw ASCII data into tide, time, and wave 

 record files. The wave data records were not used in this study but were ar- 

 chived for future reference. The tide file at this stage is a time series of 

 pressure values in pounds per square inch, absolute (PSIA) . To convert raw 

 tide pressure files into a time series of tidal elevation, several steps must 

 be performed. Error checking of pressures and time values (editing) will be 

 described, and the reduced data presented in time series plots. 

 Conversion of time data 



51. Time files of each data set are in decimal hours relative to the 

 individual gage reset time. To be of use in a numerical model, all data sets 

 must have a common time origin. The decimal hour equivalent of individual 

 reset times relative to 1 January 1987 was added to each time word in respec- 

 tive time files. All data used in this study are in decimal hours relative to 

 1 January 1987. 



Conversion of PSIA data to depth data 



52. Conversion of the raw pressure files to hydrostatic pressure 

 requires the removal of the atmospheric pressure component. Rather than 

 assuming atmospheric pressure to be constant during the sampling period, 

 observed atmospheric pressure over the deployment interval was obtained from 

 the NWS daily logs for Long Beach Airport. Pressure, in inches of mercury, 

 was recorded on an hourly basis from 0500 to 2300. Pressure was considered 

 constant over the hourly interval between observations, except for the 6-hr 

 intervals when no hourly observations were made. During these periods, 

 linearly interpolated pressures were assigned on an hourly basis. The conver- 

 sion factor used to convert from inches of mercury to pounds per square inch 

 was 0.489525. 



53. Each raw pressure word has a time word associated with it. Using 

 these time words, hourly time intervals corresponding to the observed or 

 linearly interpolated atmospheric pressures were located. Atmospheric 

 pressure in pounds per square inch was removed from raw pressure words whose 

 time words fell within the appropriate time intervals. The pressure data time 



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