The sea state forecast system of ARPA-SIM

The “sea state” is the description of the properties of the sea surface waves at a given time and location. This might be given in terms of wave spectrum or more simply in terms of significant wave height, wave direction, mean and peak period; this information can be obtained by means of numerical models. The sea state operational forecast system, daily running at the Hydro-Meteorological Service of ARPA Emilia-Romagna (ARPA-SIM), now covers different geographical domains, from the Mediterranean Sea to the coast of the Emilia Romagna region. The peculiarity of this system is due to the accurate wind field forcing coming from the high resolution (at present 7 kilometres) of the limited area model operating at ARPA-SIM and available with a high temporal frequency (1 hour). Data output are stored in GRIB format in the service database and today, an almost decennial data set is available; daily outputs are published each day in a graphical format on the public web site. This paper aims at describing how the forecast system has been developed during these years and which are the perspectives of ARPA-SIM in this field.