Numerical modelling techniques for waves, surges and currents have reached a level of accuracy which for most purposes make hindcast data (i.e. data obtained by running models to represent past events), superior to measured data for purposes of extreme value estimation and climate definition. Hindcast data can cover long time periods and wide geographical areas, in contrast with the presently available intermittent and sparse measured of design environmental conditions in any sea area. The measured data cab, however, be used for validations purposes, thus extending their value beyond their limited duration and importance for the estimation of environmental conditions, by resolving of in-situ measurements of waves and currents. For example, by correct physical modelling it is possible to detect the effects of topographic variation in a manner impossible to match without very large numbers of instruments in a widespread networks.

The Project

The North European Storm Study (NESS) is a major computer hindcast study, designed to generate a database from which an accurate assessment can be made of environmental conditions on the European Shelf and in adjacent waters. The project is sponsored by a group of oil companies and European governmental organisations. In order to obtain a hincast database which would be generally acceptable within the European operating are, it has been necessary to gather a broadly based international team of experienced modellers, drawn from governmental agencies and scientific institutes with much experience in the running of hindcast studies and operational (real time) services. The wind modelling tasks are being performed by the United Kingdom Meteorological Office (MO) and the Norwegian Meteorological Institute (DNMI), using well established techniques for pressure field and wind field analysis. The wave modelling task is under the direction of experienced modellers of the Danish Hydraulics Institute (DHI) and the GKSS Forschungszentrum, Geesthacht GMBH (in the Federal Republic of Germany), who will tailor an existing wave model of high scientific merit (the HYPA-S model) into a system best adapted for the project. Two well known hydraulics institutes, DHI and the Delft Hydraulics (DH), are jointly responsible for the surge and current hindcast task, using a versatile and much used system from DHI (the System 21) The Royal Netherlands Meteorological Institute(KNMI) is highly experienced in the gathering and mterpretation of wave data, and hence IS qualified to perform the validation assessment of the project wavemodel. DH are again involved, being responsible for the statistical processing of the resultant database The entire project is to be managed by a small team (MO as leader, assisted by DHI and DH), backed by the joint experience and scientific knowledge of all the key personnel.

The objective of the project is to prepare a database of hindcast winds, waves, surge elevations and depth integrated currents over the entire North European operating area, and to use these data to develop a uniform and sound basis for design and operational criteria m that area. The hindcast tune period will initially include the winter seasons of 1961/8662 to 1985/86.

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