Research Program

Australian Node:

The node is based at the School of Earth Sciences, The University of Melbourne and will work closely with the Centre for Australian Weather and Climate Research (CAWCR, see Appendix), and Bureau of Meteorology (also in Melbourne). The focus of this node will be the effect of air-wave-sea coupling on intensity prediction for severe weather events of tropical and extratropical cyclones and the related prediction of impacts on the marine environment. Over the five years of funding, the principal objective will be to explore the impact of coupling to the predictability of intensity of these events, and the role of ocean heat content, on the likelihood and severity of the events. This work will then form the basis from which to evaluate simulated changed climates for changes in likelihood and risk.

The postdoctoral research over the five years would be organized in two phases: Phase I will focus on the so-called east coast "bombs" in the Tasman Sea and Phase II will focus on tropical cyclones over the Timor Sea, Northwest Shelf and Coral Sea. The east coast of Australia is frequented by rapidly intensifying east coast cyclones that develop severe winds and coastal seas that impact the environment, property and operations. The most recent severe event occurred in 2007 and struck the Australian city of Newcastle causing flash flooding resulting in property damage and several fatalities. In addition, the storm induced severe coastal seas that damaged the rudder of a commercial ship, the "Pasha Bulker", and resulted in its beaching for several days. A characteristic of the east coast is the East Australian Current (EAC) one of the world's western boundary currents which transports warm Coral Sea water masses into the Tasman Sea. The EAC has significant seasonal and interannual variability that changes the available heat content during the Austral winter. The postdoctoral research would apply high resolution coupled models to hindcasts of east coast cyclones utilizing atmospheric reanalyses (e.g., ERA-interim or NCEP) and ocean reanalyses (e.g., BLUElink ocean ReANalysis (BRAN)) to explore the impact of coupling to the predictability of genesis, intensification and deintensification of these events. The primary goal is to determine the relationship of the EAC and atmospheric variability to the likelihood and intensity of East Coast Cyclone events. This will provide a basis from which the impacts of a changed climate can be interpreted for future risks from these events.

During the tropical cyclone phase of the project, an existing fine-resolution tropical cyclone forecast model will be further improved and used to examine the effect of climate change on tropical cyclone occurrence and intensity. The low-resolution storms generated by climate models will be re-simulated by the tropical cyclone forecast model to simulate a realistic climate distribution of tropical cyclone wind speeds, a task that has not yet been accomplished in the Australian region. Once this has been done, the same method can be applied to climate model simulations of a warmer world, thus giving a realistic estimate of the effects of climate change on tropical cyclone wind speeds in this region. Therefore, producing a better estimate of the effects of climate change on tropical cyclones using this method requires an improved tropical cyclone numerical weather prediction model. This effort would link well with the similar project proposed by the Central node on the impact of climate change on the probability distribution of extremes.

Strong collaborations are anticipated with the Central node in the general area of coupled atmospherewave-ocean-ice modeling. The ice modeling expertise in particular will be complementary to the activities of BLUElink. Within the period of the proposal, researchers from the Australian node plan to implement a global eddy resolving ocean model and prediction system over the next several years. The first research products are expected in 2011 and will be followed by a global reanalysis and an operational ocean forecasting system over subsequent years. This will strengthen collaborations between the nodes in two main ways: (i) an assessment can be made of the impact of deep ocean conditions on the forecast skill of models of extreme currents in the offshore petroleum fields offshore of Brazil; (ii) the Canadian node has experience in developing and testing forecast models of the North Atlantic and will be able to contribute to, and benefit from, the global ocean model and prediction system being developed by the Australian node. The Bureau of Meteorology has existing responsibilities for issuing forecasts of storm surge and coastal sea level hazards. The Australian node has interests in evaluating the quality of total coastal sea level warning systems derived from the BLUElink system and will take an interest in the UK Node. The extension of the BLUElink system to a global prediction system would permit extensions to the warning systems to other regions to be explored. The lead scientist for the Australian node is Dr. Gary Brassington.