WAVES: details

The operative model WAVES daily produces five days of hourly forecasts of the Mediterranean Sea waves.

Forecasting is made of two consecutive steps:

  1. The WAM model processes the whole basin at 1/32° resolution, that is about 3 km.
  2. The SWAN zooms into ten interesting areas at 1/200° resolution, that is about 800 m.

The whole Mediterranean basin is made of 1333 x 501 surface points, and the Sardinia area (which is the largest of the ten zoomed zones) is made of 159 x 511 surface points. Since both models represent each geographic point with a 32 x 36 matrix of spectral values, we have WAM makes its computations on about 769 million points. and, for the Sardinia zoom, SWAN makes its computations on about 93 million points. Both models executes 120 times over each geographic point to cover the period of 5 days with a time step of one hour.

  • WAM uses explicit mpich parallelism. WAM is compiled using Intel Fortran Compiler and it is linked with Intel MPI Library
  • SWAN uses openmpi parallelism. SWAN is compiled using the "-parallel" switch of the Intel Fortran Compiler

SGI Our UV2000 has 256 cores and 1024Gb RAM.
32 cores are given to users for their normal work. A cpuset with the remaining 96 cores is shielded from the system and dedicated to the execution of WAVES. WAM is started soon after the preliminary steps (getting input data from an ftp site in Greece and preprocessing it) and it uses all 96 cores of the cpuset. At the end are started ten executions of SWAN, each on a zoomed area, in such a number of cores and order to maximize the usage of the 96 cores while minimizing the wall clock time.

  • WAM, using 96 cores at 100%, takes about one hour to produce its 120 forecasts.
  • SWAN, using 48 cores at 100%, takes about 40 minutes to produce its 120 forecasts for Sardinia, which is the largest zoomed zone.

Data daily produced is about 25Gb by WAM and 1.5Gb by SWAN for Sardinia

After WAM and all ten runs of SWAN are finished, is then executed a plotting procedure which produces all images and movies that are made available in the images page.

The last WAVES step is the production of webgis coverages that are made available on web gis page.