Directional Standard deviation and Directional Spreading Index of Ocean Waves

Hello all
Do anyone know how to find Directional standard deviation or Directional spreading index for a Mean wave direction dataset?

-Regards
Praveenkhanna

Hi,

If you have the data for Peak wave period, Tp, then Directional spreading index would be the whole number of it. For Example if Peak wave period is 10.44sec then Spreading index is 10.

Also, you can refer to MIKE 21 SW user manual to know the directional standard deviation. There is a table provided from which you can correlate the standard deviation using spreading index values.

Thank for your reply. I want to know, what can be done if you dont have peak wave period data?