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Development of improved seasonal climate forecast systems

Nicholls, N. Dr; Ph: (03) 9669 4407; Fax: (03) 9669 4660; nnn@bom.gov.au

Research organisations:

Bureau of Meteorology, GPO Box 1289K, Melbourne Vic 3001; Queensland Department of Primary Industries, GPO Box 46, Brisbane Qld 4001; Agriculture Western Australia, 3 Baron-Hay Court, South Perth WA 6151.

Sponsor: LWRRDC, Land and Water Resources Research and Development Corporation

Objectives:

1. To develop a statistical seasonal climate prediction system, using observed global sea surface temperatures as predictors;

2. To test the use of the Bureau of Meteorology Research Centre atmospheric general model in seasonal climate prediction;

3. To investigate the implications of intra-seasonal oscillations for seasonal climate predictions;

4. To conduct studies to facilitate the development and application of improved seasonal predictions to rural industry at the regional level.

Methodology:

1. Conduct studies relating observed sea surface temperatures to Australian rainfall. Develop statistical methods to use such relationships for predicting rainfall;

2. Test the effect of observed sea surface temperatures on model-simulated Australian rainfall, and compare this with observed rainfall;

3. Examine the most effective ways to deliver seasonal climate predictions, areas for which forecasts should be issued and the necessary frequency of issue.

Progress:

The statistical analysis demonstrated that increased skill in seasonal rainfall prediction is obtainable using Indian Ocean and Pacific Ocean sea surface temperatures (SSTs) as predictors, in place of, or as well as, the Southern Oscillation Index (SOI). An operational system based on a combination of the SOI and an Index of Indian Ocean SST has been developed, tested and is now used operationally by the Bureau of Meteorology.

This project has also shown that atmospheric climate models (AGCMs), when forced with the observed SSTs, show reasonable success in the Australian region, largely reproducing the observed relationships between rainfall, the SOI and global SSTs. The models are particularly good at reproducing the SOI time series and thus capturing the large scale circulation of the atmosphere and its variability due to changes in the lower boundary, or SST, forcing.

Discussions and workshops with rural producers and advisers identified problems and possibilities for seasonal climate prediction. In particular, the presentation and content of climate forecasts requires care, if forecasts are to be used correctly. Forecasts therefore have to be matched to the needs of users.

Period: starting date 1993-04; completion date 1997-12

Status: completed

Keywords: seasonal climate forecasts, Southern Oscillation Index, sea surface temperatures, climate models

Publications:

Elliott, G. and Foster, I. (1994). Requirements for seasonal climate forecasts by agricultural producers in Western Australia (Milestone report to LWRRDC)

Nicholls, N. (1997). Developments in climatology in Australia: 1994-1996. Australian Meteorological Magazine 46, 127-135.

Stone, R.C. and Marcussen, T. (1994). Queensland producer requirements from seasonal climate forecasts systems (Milestone report to LWRRDC)

 

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