b. Barometric Pressure , Barometric pressure was measured with a 

 Danforth Marine Barometer. Periodic checks were made with the National 

 Ocean Survey (NOS) Merrimack River Station to maintain the instrument 

 calibration. Mean barometric pressure readings for the summer and winter 

 periods were 29.75 and 29.88 inches. Maximum and minimum readings for 

 both periods reflect the passage of high- and low-pressure systems, 



c. Air and Water Temperature . Measurements of air and water tem- 

 perature were taken bihourly throughout both study periods. Air tempera- 

 tures were taken from thermometers mounted adjacent to the instrument 

 shelters. The thermometers were placed to shield them from direct sun- 

 light and wind. Mean temperatures were 72.5° and 28.2° Fahrenheit for 

 the summer and winter periods. Water temperatures were measured by 

 attaching a swimming pool thermometer on a line to the waist of a 

 swimmer as breaker height and depth were measured. Summer water tem- 

 perature readings varied between 47° and 68° Fahrenheit with a mean of 

 57.3° Fahrenheit. Minimum and maximum water temperature readings during 

 the winter period were 28° and 45° Fahrenheit, with a mean of 37° Fahren- 

 heit. 



5. Beach Profile Techniques . 



Beach profiles were run daily at low tide for each of the 12 profile 

 locations (PL-0 to PL- 11). 



The profiling technique used was modified after the technique of 

 K.O. Emery (1961) which required the use of two 300- centimeter profile 

 rods and a 200-centimeter spacing rod. The observer sights the horizon 

 with the top of the seawardmost post and determines where the two levels 

 line up on the landwardmost post. This difference in elevation is 

 recorded as a decrease in centimeters per "standard interval" (300 cen- 

 timeters). Where profiles cross significant breaks in slope, smaller 

 surveying intervals are used. Traverses across ridges located on the low 

 tide terrace require lining up the landwardmost post with the horizon and 

 sighting off of the seawardmost post. These measurements are recorded 

 as a certain rise in centimeters per 3- meter interval. 



During periods of reduced visibility, an Abney Level was attached to 

 the horizontal spacing rod and elevation changes were determined by level- 

 ing the spacing rod between the two upright posts and recording the eleva- 

 tion difference. 



Initially, each of the 12 base stakes, including the backup stakes, 

 was surveyed in relation to profile PL-0 by using a Theodolite and stadia 

 rod. A series of 8-foot metal fenceposts was placed along the PL-0 pro- 

 file line for tide-measuring stakes. Tide measurements for the study 

 period were used to calculate MLW. This datum was then related to the 

 elevation at stake PL-0 and thence to PL-1 to PL-11. 



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