Progress in ocean wave forecasting at ECMWF.

Progress in ocean wave forecasting at ECMWF.
Technical memorandum
Date Published
Secondary Title
ECMWF Technical Memoranda
Peter Janssen,
Saleh Abdalla,
Hans Hersbach,
AbstractProgress in ocean wave forecasting during the past 10 years is discussed. It will be shown that during this period there have been substantial improvements in the quality of the forecast surface wind field and as a consequence also in the quality of the forecast wave height field. This follows from comparisons with the verifying analysis, in-situ buoy data and altimeter data. The reasons for these large improvements are detailed in the paper; the improvements mainly come from the introduction of 4DVAR, increases in atmospheric resolution, improvements of the physics of the atmospheric model and the two-way interaction of wind and waves. In addition, a number of new developments are outlined. An important element of severe weather forecasting over the oceans is the prediction of freak waves. Here, we describe the steps that led to the introduction of the first operational freak wave prediction system. The sea state is affected by ocean currents, tides and storm surges. Here, we discuss first results regarding the impact of ocean currents on the significant wave height field on a global scale. It is argued that for sea state forecasting in the coastal zone, an area of important economic significance, knowledge of the (ocean) current and the mean sea level is important. Therefore, a proper modelling of the sea state in the coastal zone will require the introduction of a coupled storm-surge, ocean wave prediction system.