PART V: ANALYSIS OF MEASURED WIND DATA 



NWS Data 



34. The NWS anemometer is located at the Coast Guard Station within 

 Womens Bay. The anemometer is approximately 100 yd from the water line at 

 mean sea level, elevation 10 m. Prior to 1973, a Navy anemometer was at the 

 same location, but at an elevation of 5 m. The NWS/Navy anemometer provided 

 hourly data from November 1945 through December 1982. 



Data adjustment 



35. Using the method presented in the Coastal Engineering Technical 

 Note CETN-I-5, "Method of Determining Adjusted Windspeed, U^ , for Wave 

 Forecasting," WES personnel adjusted the data. The adjustments included the 

 following: 



a. Correction to 10-m level for data prior to 1973. 



b. Correction to hourly averages from 5-min averages every hour. 



c. Adjustment of overland readings to overwater readings. 



d. Correction for nonconstant coefficient of drag. 



e. Correction for instability due to air-sea temperature differ- 

 ences for directions where the fetch is greater than 10 miles 

 (an unstable condition was assumed, since no temperature data 

 were available) . 



These corrections were made so that the wind data could be applied directly to 



wave forecasting curves. 



Wind summary 



36. A computer program was developed to produce summaries of the hourly 

 winds and of the 3-, 6-, 8-, and 1 0-hour ly winds. The summaries relate wind 

 speed and duration to recurrence probability for 16 directional sectors. The 

 maximum annual wind was also found for use in an extremal analysis to be pre- 

 sented later. 



37. The procedure to compute the N-hour average wind was as follows: 



a. Delete bad observations (less than 1 percent of the 

 325,050 observations were bad). 



b. Compute arithmetic average of all wind speeds in consecutive 

 N-hour intervals to estimate wind speed (calm values were 

 counted as zero wind speeds). 



c. Compute vector sum of all noncalm observations in the N-hour 

 interval. 



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