Improved climate prediction during El Niño events

Wright, W.J. Dr; ph: (03) 9669 4781; fax: (03) 9669 4678; w.wright@bom.gov.au

Beard, G.S. Mr; ph: (03) 9669 4527; fax: (03) 9669 4527; g.beard@bom.gov.au

Walland, D.J. Dr; ph: (03) 9669 4068; fax: (03) 9669 4678; d.walland@bom.gov.au

Research Organisation: National Climate Centre, Bureau of Meteorology, GPO Box 1289K, Melbourne, 3001

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

Objectives:

1. Describe the overall synoptic patterns, and sequences of events, associated with El Niño episodes, and how these, along with ocean temperature and tropical rainfall patterns, differ between (i) events that produce widespread drought, and (ii) those that produce useful rains in some areas that would normally expect El Niño-related rainfall deficiencies.

2. Investigate synoptic and oceanic precursors to the two different types of events, and to the breakdown of El Niño influences on Australian rainfall late in the El Niño cycle.

3. Produce a historical database of the synoptic patterns attending previous significant El Niño events, and their influence on Australian rainfall.

Methodology:

Examine 40 years of NCEP (National Climate Environment Program) re-analyses for systematic differences between El Niño events that result in widespread drought and those that produce useful rains. The 40 years should contain 5-6 events that fall within each category. Initial analysis will consist of composites to highlight any significant differences, but other techniques (e.g. stratification according to QBO (Quasi-Biennial Oscillation) phase or low frequency ocean patterns, etc.) will be applied as appropriate. If time allows, events from earlier in the Century will also be investigated using more restricted data-sets.

The project will also consider similarities and differences between El Niño years and 'normal' years that are associated with major Australian droughts, e.g. 1967.

Progress: In planning stage: data-set acquisition; recruitment, etc.

Period: starting date: 1999-07; completion date: 2000-06

Status: Preliminary planning

Keywords: El Niño, Synoptic patterns, Australian rainfall anomalies, sea surface temperatures, tropical convection, drought episodes.

Publications: None as yet.