MIROS is a microwave radar system for real-time measurement of directional ocean wave spectra and surface currents. MIROS is the only system of its kind available on a commercial basis. At the present time, several systems have been delivered and will be put into operation in the North Sea in the near future.
During the period from December 1984 until May 1985, one system has been operational from Esso's Odin platform in the Norwegian sector of the North Sea under contract with Esso Norga A A/S. One important aspect regarding this installation is that other wave and current measurement programs have taken place in the same period; thus data for inter-comparison studies will available.
This chapter starts with a brief description of the MIROS system which includes the most important characteristics of both hardware and software. The principles of operation are also reviewed.
The MIROS directional wave spectra contain amounts of information concerning the directional distribution of sea and swell as well as the unidirectional spectrum and total energy. A new ocean - wave model is being implemented at DNMI(the Norwegian Meteorological Institute). This model simulates the full two-dimensional (direction/frequency) wave spectrum, generated from successive windfields over the N.E. Atlantic, North Sea and Norwegian Sea. An interesting application of MIROS data is in verification and calibration of the wave model. The experience obtained investigating the applicability of MIROS data from the Odin installation for this purpose is the main subject of the chapter.
Availability of directional wave information is becoming increasingly more important in several fields related to offshore activities. The present applications involve both the need for statistical information as well as real-time data and forecasts. It is of course impossible to cover all ocean areas of interest with sensors, and therefore a complete maritime weather service system will incorporate both various types of sensors and a wave model, which can be run in both a hindcast and a forecast mode. DNMI (the Norwegian Meteorological Institute) has implemented the WINCH wave model. The windfields used as input are taken from the six-hourly routine wind analysis at DNMI.
A wave model does certainly not eliminate the need for measured date. A wave model must be adapted to a certain geographical area by tuning, and problems with correct windfield estimation render the assimilation of real-time measured wave data in the model necessary, to prevent accumulated errors. Measured data will also be necessary for model verification.
MIROS measures the directional wave spectrum as well as components of the surface current. Wave data from a MIROS system seem to be well suited for the applications described.
The chapter begins with a short review of the MIROS system. Then the application of MIROS data in the maritime weather service is discussed in general terms, followed by a short description of the DNMI wave model. During the winter of 1984/85 one MIROS system was operational from Esso's Odin platform in the North Sea. A short description of this installation is given.