Hi,

Our standard instrument for measuring wave directional properties at sea is the directional Waverider buoy. From the three-dimensional x, y and z displacements(calculated from the measured raw data accelerations) we produce a quasi 2D ocean wave spectrum, in which at each frequency the mean wave direction, as well as the directional spreading, the skewness and kurtosis of the directional distribution of wave energy is derived. Our standard software package is called the Standard Wave Analysis Package (SWAP). If so desired, I could send you more information about this approach.

Best wishes from the Netherlands,

Herman.

Thank you Mr.Alberto Alberello and Mr.Hermen Peters.

Mr. Hermen Peters, Could you please share something more about this?

Please see the attached PDF file for more information about our wave processing approach.

Probabaly, for you the part concerning wave directional properties will be the most relevant. I hope it is of some benefit to you.

Regards,

Herman.

Thank you Mr.Hermen Peters

This link can help you:

http://rspa.royalsocietypublishing.org/content/465/2111/3361

There are several waves to compute the spread, the most common uses the first moments a1 and b1 of the directional spectrum ( see e.g. Kuik et al. JPO 1988).

This is comonly used also in numerical wave models. So you will find spread output for example here:

ftp://ftp.ifremer.fr/ifremer/ww3/HINDCAST/GLOBAL_NEW/2016_ECMWF/spr/

and it is easy to recompute it from the directional spectrum . You can find many spectra here

ftp://ftp.ifremer.fr/ifremer/ww3/HINDCAST/GLOBAL_NEW/2015_ECMWF/

Thank you Fabrice Ardhuin and Nguyen Thanh Luan...