Coral Bleaching

From 3 November 2011, the Bureau is upgrading the POAMA model to POAMA-2. This upgrade will result in forecasts being updated every 2 weeks. The Operations Bulletin provides detailed information on the change.

These pages provide information on sea surface temperatures for monitoring coral bleaching events in the Great Barrier Reef, Australia.

The Predictive Ocean Atmosphere Model for Australia

The Predictive Ocean Atmosphere Model for Australia (POAMA) is a state-of-the-art seasonal to inter-annual seasonal forecast system based on a coupled ocean/atmosphere model and ocean/atmosphere/land observation assimilation systems. POAMA has been running operationally since 2002 and the current version since 28 October 2011.

The coupled model in POAMA (version 2; P2.4) consists of the Australian Bureau of Meteorology atmospheric model (BAM 3.0) and the CMAR Australian Community Ocean Model V.2 (ACOM2), coupled using the Ocean Atmosphere Sea Ice Soil (OASIS) coupling software. The atmospheric model component has a horizontal spectral resolution of T47 and 17 vertical levels. The ocean model grid spacing is 2 degrees in the zonal direction and 0.5-1.5 degrees in the meridional direction, with 25 vertical levels, of which 12 are in the upper 185 m.

Atmosphere initial conditions are provided by an Atmosphere Land Initialisation (ALI) scheme, where a BAM3.0 atmosphere-only integration forced with observed SST, is nudged towards the real-time Australian Community Climate and Earth-System Simulator (ACCESS)-G (global) analyses. The ocean model is initialised using an ocean data assimilation scheme based on the the POAMA Ensemble Ocean Data Assimilation System (PEODAS; Yin et al. 2011).

The real-time forecast system of POAMA-2 is similar to that of POAMA-1.5, but instead of the single version of the forecast model used in POAMA-1.5, there are three versions of the model with different configurations implemented in POAMA-2. Each version of the forecast model produces an ensemble of 10 members, and the forecasts from the 3 models are combined to form a 30 member multi-model ensemble. The forecasts are generated twice per month using initial conditions that are valid on the 1st and 15th of the month. The forecasts and updated products will be available by around the 3rd and 17th of each month.

A hind-cast is a retrospective forecast which can be used to measure model performance by assessing the skill of the model in predicting past events. The hindcasts in the POAMA-2 system were generated in the same way as the real-time forecasts, using the same ensemble generation technique and initialized by PEODAS and ALI run in the same way. A hindcast set was produced from 1960-2010. Initialised on the 1st day of each calendar month, a 10 member, 9-month forecast has been generated for each of three model configurations of POAMA-2. Each member's initial conditions differ only in the ocean state (the atmosphere is the same for all ensemble members) by taking the 10 different initial conditions from the PEODAS assimilation scheme. An ensemble gives an indication of the potential spread in forecast skill by allowing the stochastic component of the model to evolve differently in each member and reduce the effects of uncertainties in model initial conditions.

Lead-time is defined as the time elapsed between the model start date and the forecast date, i.e. if the model start month is January, the forecasts at lead-times 0, 1, 2 and 3 months are for January, February, March and April respectively.

Further reading

  • Spillman C.M., 2011: Operational real-time seasonal forecasts for coral reef management. J. Oper. Oceanog., 4, 13-22.
  • Spillman C.M., 2011: Real-time predictions of coral bleaching risk for the Great Barrier Reef: Summer 2010/2011. CAWCR Res. Lett., 6, 34-39.
  • Spillman C. and Alves O., 2009: Dynamical seasonal prediction of summer sea surface temperatures in the Great Barrier Reef. Coral Reefs, 28, 197-206.
  • Spillman C.M., Alves O., and Hudson D.A., 2010: Real-time seasonal SST predictions for the Great Barrier Reef during the summer of 2009/2010. CAWCR Res. Lett., 4, 11-19.
  • Spillman C.M., Alves O., Hudson D.A. and Charles A.N., 2009: POAMA SST predictions for the Great Barrier Reef: Summer 2008/2009. CAWCR Res. Lett., 2, 30-34.

For further information visit POAMA group.

Please be aware that all POAMA forecasts are subject to the Bureau of Meteorology's copyright and disclaimer.