HF RADAR APPLICATIONS FOR OPERATIONAL FORECASTINGOF COASTAL REGIONS*

摘要

High-Frequency (HF) radars are operated in the HF band of the radio wave spectrum,I.e. between 5 MHz and 30 MHz. Due to the physics involved, these radarsare able to look behind the horizon. Signals backscattered from the ocean’s surfacecontain information about currents, ocean wave spectra and wind. Depending onthe radar frequency, working ranges up to 150 km can be achieved. As for optimumperformance, these radars should be installed at the shore, the term ’Coastal Radar’is often used in this context. Combining HF radar remote sensed data with highresolutionnumerical models by data assimilation brings together the advantages ofboth technologies: The HF radar can provide accurate forcing and boundary conditionsto the model and keep the model nowcast ’close to nature’, the model can thanbe used to supply high quality forecasts. For highly variable oceanographic processes,such as mesoscale eddies and fronts, this approach might be the only way to providereliable now- and forecasts. This leads to a better understanding of the dynamicsof coastal processes. The operational forecasting system described above has beenset-up and tested within the EU funded project EuroROSE. Comparisons of an HFradar aided model to a free running model showed an increase in correlation for the4-hour forecast from 0.27 to 0.77 due to data assimilation.