Milking the Weather - June 2010 Edition
Australia’s Climate Forecast Model
POAMA: Predictive Ocean Atmosphere Model for Australia
What is POAMA?
POAMA is the Predictive Ocean Atmosphere Model for Australia. It is a seasonal forecast system based on models of the ocean and atmosphere.
How does POAMA generate a forecast?
POAMA combines current and historical ocean and atmospheric observations from ships, satellites and weather stations. Historical relationships and mathematical equations representing the laws of physics, forecast how the state of the ocean and atmosphere is evolving.
What does POAMA forecast?
POAMA produces an eight-month forecast every day. Currently POAMA has most skill in forecasting sea surface temperature in the Pacific Ocean (NINO 3.4 region - see below in green) and the occurrence of El Niño and La Niña.
Nino 3.4: Area of the pacific that POAMA uses to generate long range forecast
POAMA is a coupled model combining ocean and atmospheric conditions.
Coupled (ocean and atmospheric) models are relatively new and unlike former statistical forecasts are not limited to historical trends as new climatic conditions can be forecast. For example, POAMA can predict how the impacts of one El Niño may be different to those of another.
Forecast skill.
Compared to weather forecasting, coupled model seasonal forecasting is still in its early stages but with progressive research and computer technology, forecast skill will improve.
POAMA is just one model surveyed by The Fast Break newsletter, which provides a monthly summary of a selected group of forecast models.
What is POAMA forecasting now?
The graph below represents POAMA’s last 30 daily forecasts of possible sea surface temperatures in the central/eastern equatorial Pacific Ocean in the NINO3.4 region.
Each individual line gives a nine-month forecast for the average NINO3.4 index (temperature anomaly, which means a deviation from average). In general, the closer the lines lie together, the greater the certainty in the prediction. The spread amongst these lines gives an indication of the uncertainty in the forecasts, much of which comes from the uncertainties in the observations that are used to start the forecasts.
The 15 most recent forecasts are blue and the 15 previous forecasts are red. Warm (El Niño like) NINO3 sea surface temperature conditions are those exceeding +0.8ºC, while cool (La Niña like) NINO3 sea surface temperature conditions fall below -0.8ºC.
Currently 93 per cent of POAMA forecasts suggest cool NINO3.4 sea surface temperatures (below -0.8ºC) for July. Cool seas in this area increase the likelihood of a La Niña occurring.
Above: POAMA model forecast of the central equatorial Pacific sea surface temperatures (SST’s) for the next nine months. Solid blue line indicates average SST temperature for Nino3.4.
Seasonal model forecast for Victoria
Output from the Fast Break Current outlook - 9 June, 2010
http://www.dpi.vic.gov.au/climaterisk
Summary of seasonal model forecasts for Victoria over the next three months:
PACIFIC OCEAN: Slightly neutral to cool
INDIAN OCEAN: Neutral to slightly warm
RAINFALL: Mixed (some models slightly wetter for Victoria)
TEMPERATURE: Slightly warmer to warmer
