Meterological Instruments 



Anemometer 



40. Winds were measured using a Weather Service Model F420C anemometer 

 consisting of a cup rotor and spread- tail wind vane. Through mid-September, 

 the anemometer was located 58 m behind the dune, with the cups 6.4 m above 

 NGVD. In late September, the instrument was relocated to the top of the labo- 

 ratory building at an elevation of 19.1 m (Figure 2). The accuracy of the 

 speed transmitter and indicator assemblies was (a) 1 percent up to 100 m/sec 

 and (b) 2 percent over 100 m/sec. The wind direction transmitter and indicator 

 assemblies were accurate to ±5 deg at an air speed of 0.26 m/s or greater. 



41. In September, after installation on the laboratory roof, NOAA/ 

 National Weather Service (NWS) personnel calibrated the speed cups and set the 

 direction reference to true north. The speeds were found to be approximately 

 5 percent faster than actual, and the instrument was reset. The anemometer 

 had been last calibrated in the spring of 1979 at which time, it is believed, 

 the zero offset was incorrectly set; consequently, the data before September 

 should be corrected by reducing the value indicated by 5 percent. 



42. The wind speed and direction were recorded on a battery-powered 

 Esterline-Angus recorder. Problems with the recorder's clock and tape advance 

 mechanism and the pen actuator (for indicating direction) were frequently 

 found, and the unit required day-to-day maintenance. 



43. Maintenance of the anemometers consisted of troubleshooting the 

 records and resetting the instrument based on the calibration results. 

 Microbarograph 



44. This recording instrument, an aneroid sensor used to measure atmo- 

 spheric pressure, responded to pressure changes on the order of 0.169 mb. The 

 microbarograph was manufactured by the Belfort Instrument Company, Baltimore, 

 Maryland, and was located inside the office trailer, 6 m above NGVD, until June 

 when it was moved inside the laboratory building, 9 m above NGVD (Figure 2). 



45. Daily, the microbarograph was compared to an NWS aneroid barometer; 

 adjustments, although infrequent, were made as necessary. The microbarograph 

 required very little maintenance except that required to ink the pen and wind 

 the clock every 3 days when the chart paper was changed. 

 Maximum/minimum thermometers 



46. NWS maximum and minimum thermometers were used to determine the 



22 



