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The CSS projects

Australia

P2 - ROAM/ROAM II

Project name
Relocatable Ocean and Atmosphere Model (ROAM)

Domain
Nominally 90°E-180°E, 60°S-10°N, but focussed on the coastal regions of Australasia and Indonesia

Objectives
To provide an automated, relocatable, high-resolution, model-based forecasting system for the ocean and atmosphere with the following characteristics:

  • The system to be driven from a graphical interface, requiring input only of the spatial domain, the spatial resolution and the forecast period
  • The models to be nested inside global forecasting models. For the ocean, the global model is the GODAE model OFAM (Ocean Forecasting Australia Model), with 10-km resolution in the Australian region. ROAM provides resolution down to 2 km, and forecasts up to 7 days.

 

Operational objectives:
To provide the Royal Australian Navy with a forecast system for ocean thermal structure, for planning acoustic strategies.

Downscaling strategy
The global OFAM system is to be run operationally by the Australian Bureau of Meteorology, with updates every 3 days, and forecasts out to 7 days. The ocean forecasts will complement their existing atmospheric forecasting. The ROAM system will reside on user computers, in particular those of the Royal Australian Navy. Once the user has initiated a run for a specified domain (typically a region of order 100 km x 100 km), ROAM will automatically download the global data and execute the nested atmospheric and ocean model runs.

The nested models are the Colorado State University atmospheric code RAMS, and an in-house coastal-ocean model (called SHOC). Coupling between the two models is one-way, from the atmosphere to the ocean. The models have been configured for robustness, so that they run stably every time. In particular, the ocean model uses only sponge conditions at the open boundaries, but includes the addition of tide height (derived from an independent global tidal model) along these boundaries. Model robustness has been verified by many test runs within the working region. Model accuracy has been tested against data for 3 specific, and well-studied regions on the Australian shelf. However, the accuracy tests were done before the availabilty of the OFAM data stream. The nested ocean model has proved to be very sensitive to the conditions specified at the open boundary.

 

Project status
The ROAM system is in its final stages of development, and due to become operational on 1 January 2007. This date coincides with the scheduled initialisation of the OFAM operational data stream by the Bureau of Meteorolgy. ROAM has been in development since July 2003.

In July 2006, ROAM II, a second phase of the ROAM development was initiated. ROAM II will incorporate the following enhancements:

  • Local data assimilation, in particular of CTD profiles collected on-site by Naval vessels
  • Coastal freshwater runoff, which is also to be incorporated into OFAM
  • Surface waves
  • More complex atmosphere-ocean coupling, depending on the outcome of sensitivity tests

ROAM II is due for completion in July 2010.

(Last Updated: 11-02-2008)