688 CARTWKIGHT [CHAP. 15 



The principal part of 62(0) occurs at low frequencies, where it can cause swell 

 superposed on a wind-wave system to be obscured. It should be remarked that 

 with a freely floating recorder of this type the second-order effects derived by 

 Tick for a fixed recorder (above) do not apply, and. are in fact considerably 

 reduced. Other types of spectra produced by non-linear instrumental response 

 are considered by Rice (1945). 



References 



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