2. Water Level Data . 



a. Data Collection . The water level information was obtained from two 

 NOS tide gages, each of which produces a digital paper tape of instantaneous 

 water levels sampled continuously at 6-minute intervals. At the end of each 

 month, the paper-tape records are removed from the recorders and mailed to NOS 

 in Kockville, Maryland, for analysis. 



The FRF tide gages are checked daily for (1) the correctness of time, 

 (2) the proper operation of the punch mechanism, and (3) the accuracy of the 

 water level information obtained. The accuracy is determined by comparing the 

 gage level reading to a level read from a reference electric-tape gage. 



b. Data Analysis . The digital paper-tape records of tide heights taken 

 every 6 minutes were analyzed by the NOS Tides Analysis Branch. A Mitron 

 interpreter created a digital magnetic computer tape from the punched paper 

 tape. This tape was then processed on a Univac 732 computer. First, a 

 listing of the instantaneous tidal height values is obtained for a manual 

 check. If errors are encountered, the computer program can fill in or re- 

 create a maximum of 3 consecutive days of bad data using correct values from 

 the nearest tide station and accounting for known timelags and elevation 

 anomalies. The data are plotted and a new listing is generated and 

 rechecked. When the validity of the data is confirmed, monthly tabulations of 

 daily highs and lows, hourly heights (instantaneous height selected on the 

 hour), and various extreme or mean water level statistics are generated. The 

 MSL reported is the average of the hourly heights throughout the month; the 

 mean tide level (MTL) is midway between MHW and MLW. 



3. Weather and Visual Observations . 



a. Meteorological Data . Each instrument that is used for monitoring the 

 meteorological conditions at the FRF is read and inspected daily. The instru- 

 ments with analog chart recording capabilities are checked as follows : the 

 chart pen is zeroed; the chart time is checked and corrected if necessary; a 

 daily reading is marked on the chart for reference; the starting and ending 

 chart times are recorded as necessary; and new charts are installed when 

 needed. Sample chart records for the barograph (atmospheric pressure), rain 

 gage, and pyranograph (solar radiation) are presented in Figure 3. Daily 

 readings are taken from all instruments except the pyranograph. Visual 

 observations of weather information such as cloud cover, visibility, and 

 predominant weather conditions are obtained concurrently with the instrument 

 readings. 



The meteorological data summaries in this report were prepared from daily 

 observations obtained at about 0700 e.s.t. These summaries do not represent 

 daily or hourly averages; therefore, caution should be exercised when inter- 

 preting the results. 



The NWS anemometer was calibrated annually. The anemometer output was 

 coupled to dial wind speed and direction indicators, which were read daily 

 (estimated averages of a 1-minute observation of the dials). 



17 



