Q: How can I represent a Pierson-Moskowitz or Bretschneider spectrum?
REV 5.08

A: All the various spectral types can be described with one general equation. For instance, a JONSWAP spectrum with a gamma of 1.0 is the same as an ISSC spectrum. To represent a Pierson-Moskowitz spectrum, use an ISSC spectrum with a mean period that gives a wave steepness of 23.27. This steepness is what the Pierson-Moskowitz spectrum assumes. Therefore, one needs to choose the proper mean period:

       Hs/(gT^2/2pi) = 1/23.27

so

       T = sqrt(23.27*Hs*2pi/g).