Scientists have built a weather and climate model for Australia using earth system modelling.
Modelling the Earth system is complex
Coupled earth system models seamlessly link together models of the oceans, atmosphere, sea-ice, land surface, global carbon cycle and chemistry, and aerosols, to simulate changes in the Earth's climate systems with ever-increasing precision.
These models enable scientists not only to project major changes in the Earth's climate in the longer term, but to make short and medium-range weather forecasts and seasonal predictions for particular regions.
Skill and reliability on one time scale engenders confidence for other time scales (such as climate change), and vice versa.
Investing in modelling Australia's own Earth system model
Scientists at The Collaboration for Australian Weather and Climate Research, a partnership between CSIRO and the Bureau of Meteorology, have developed Australia's next generation climate model: the Australian Community Climate and Earth System Simulator (ACCESS).
ACCESS is a fully coupled earth system model being developed with several Australian universities on the nation's most powerful supercomputers operated by the National Computational Infrastructure and the Bureau of Meteorology.
It embodies a national approach to climate and weather prediction modelling that will give CSIRO and the Bureau of Meteorology the best possible scientific tools for climate impact and adaptation analysis, and weather forecasting.
ACCESS will also help Australian scientists contribute to major international climate modelling and prediction projects, and will provide Australia's major input to the sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC) on the world's climate future.
ACCESS represents a huge advance over earlier, simpler climate models, and is tested and fed by data from earth-observing satellites and other climate sensors.
Supporting decisions made by governments, industry and the general community
Australia's investment in ACCESS is already paying off, as it supports decisions made by governments, industry and the general community.
One of the major achievements of ACCESS is the improvement of weather forecasts. It is now possible to forecast the weather three days ahead with the same level of accuracy as for two-day forecasts previously. This makes for greater certainty in planning and responding to weather events.
In the last eight years, there has been up to a 30 percent improvement in forecasting tropical cyclone tracks, allowing for better planning of emergency events and decision making—for example, average 24-hour forecast errors of cyclone tracks are now about 90 km, compared with 125 km eight years ago. ACCESS was used to predict the path of tropical cyclone Yasi, which crossed the coast of North Queensland in 2011. This allowed the community, industry and emergency management agencies to make decisions and plan several days ahead of the event.
Fire weather forecasting
Four-day weather forecasts today are as accurate as one-day forecasts provided in the early 1990s. ACCESS simulations now provide unprecedented detail about fire weather danger and real-time conditions to support planning and deployment of fire crews, and emergency management. The critical weather factor for the Victorian bushfires in February 2014 was a period of very hot dry northerlies followed by a strong cool change. ACCESS provided several days of advance warning of this extreme event, which was associated with the worst fire weather in Victoria since Black Saturday in 2009.
Since the early 1980s, flood warning detection has seen a four-fold improvement, while accuracy has had a three-fold improvement. In March 2011, ACCESS forecast a heavy rain event in the Bega Valley in New South Wales that resulted in the highest major flood in the region since 1971. The flood watch issued as a result of this forecast gave communities time to prepare and emergency services time to deploy their resources.
ACCESS simulations rank in the upper level of international climate model simulations and are particularly skilful over Australia, based on simulations of historical climate. ACCESS provided Australia's major input to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). This included simulations of the climate of the 20th century, and projections for the 21st century for a range of future greenhouse gas and aerosol concentration scenarios. The model output fields from these simulations have been placed on a data distribution system known as the Earth System Grid based at Australia’s National Computational Infrastructure, where it is being accessed by the research community.
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