A rapid response nowcast/forecast system using multiply nested ocean models and distributed data systems

Logistics and results of a real-time modeling effort, which took place in fall 2000 in the waters between Corsica and Italy in the Mediterranean Sea, are presented. The major objective was to nest a high-resolution local version of the Harvard Ocean Prediction System (HOPS) into a coarse resolution Colorado University Princeton Ocean Model (CUPOM) covering the northern part of the Western Mediterranean. Due to the different designs of CUPOM and HOPS, traditional nesting methods were not successful. Therefore, a new method was developed that assimilated the CUPOM prognostic fields into HOPS instead of prescribing them only along the open boundaries. Another objective of the effort was to set up and test a data distribution system, providing Internet-based rapid data transfer among the project partners being partly at sea and partly on land in different continents. It is shown that such a system works, enabling turnaround times of less than a day from the time when measurements are taken to the release of the model forecast.