m 



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v_^ 





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1 1 



FIGURE 16 Power spectra of six 90-minute microbarogroph records — 

 Spectra are corrected for instrument response. 



oscillations could be generated by vertical wind shear in a horizontal 

 atmospheric duct bounded on the bottom by the ground and on the top by a 

 temperature discontinuity. Such ducts occur frequently in the Arctic; 

 however, the period of this generating mechanism has a theoretical lower 

 limit of about 10 minutes. 



In any event 10- to 100~second micropressure waves exist in the 

 Arctic. As will be shown later, these micropressure waves have sufficient 

 energy to bend the ice and generate water waves. It has been assumed that 

 micropressure waves propagate in the same direction as the wind. The nature 

 of these waves in an area for much further study. 



c. Gravimeter Records 



Low resolution power spectra for the five wave records taken during 

 5 and 6 July were computed, corrected for instrument response, and plotted 

 on the same set of coordinates (figure 1?) • 



Dispersion of long-period waves traveling from a distant source and 

 local generation of short-period waves are clearly displayed in this figure. 



(l) The effects of wave dispersion are seen for periods longer than 

 l6 seconds. Long-period energy (6o or more seconds) in the 17^5 to 1915^ 

 record increases 6 to 7 times in magnitude 5 hours later in the 2237 to 0007Z 



30 



