The Response of Tropical Cyclone Characteristics to Projected Climate Change in Northeast Australia through WRF simulations and Pseudo Global Warming Technique

Speaker:

Chelsea Parker, Institute at Brown for Environment and Society, Brown University, U.S.A.
 

Abstract:

The relationship between climate change and the intensity and frequency of tropical cyclones in the south Pacific is highly contested, particularly in the context surrounding the future of the El Niño Southern Oscillation. However, during the last two decades, the northeast coastal regions of Australia have experienced significantly increased total rainfall, more frequent heavy rainfall, and intense tropical cyclone events.

Together with rising sea levels, ocean warming, and ocean acidification, tropical cyclone activity and associated coastal flooding present the potential for increasing negative consequences for coral reef environments even with no change in frequency or intensity. Any possible future changes to tropical cyclone activity could exacerbate the impacts on reef and coastal environments.

This study employs a numerical modelling approach to diagnose the response of tropical cyclone characteristics and associated coral reef damage potential in the context of projected climate change.

Using the regional National Center for Atmospheric Research Weather Research and Forecasting model (NCAR WRF) and high resolution initial conditions, we simulate three intense tropical cyclone events that have affected the Queensland coastline during the last five years (Yasi 2011, Ita 2014 and Marcia 2015) under current and projected future (2070–2100) conditions.

The boundary conditions for the future scenario are created through a dynamical downscaling and pseudo global warming technique where the global climate is provided by an NCAR Community Earth System Model (CESM) RCP8.5 realisation. In response to this scenario, the tropical cyclone events increase in wind speed around 20%, and central pressure is reduced by ~10hPa and critically this intensity is maintained longer in the life cycle, up to landfall. The future scenarios also result in precipitation increases of 15–45% on average and altered trajectories. Depending on the case study, we have also found a size increase response of ~40% and a translation speed increase of ~25% on average.

The response of the tropical cyclone characteristics, under future climatic conditions, suggest that a potentially wider extent of the Great Barrier Reef and coastal environment is at risk from amplified tropical cyclone damage when events occur, including locations that may be unaffected by intense storms in the current environment. 
 

Biography:

Chelsea is interested in ocean-atmosphere interactions. Originally from London, U.K., she received her BSc in Physical Geography from the University of Bristol, U.K. in 2010 where she focused on climate change and ocean acidification over reef environments. 

Chelsea is now a senior graduate student working with Professor Amanda Lynch in the department of Earth, Environmental, and Planetary Sciences and the Institute at Brown for Environment and Society at Brown University, Providence, R.I. U.S.A.

She is preparing to defend her PhD in early 2017. Her dissertation research explores the complex relationship between tropical cyclones and the coral reef ecosystems of the Great Barrier Reef, Australia in a changing climate. 

Chelsea uses remote sensing techniques to estimate damage to the reef area after tropical storms, and regional, numerical weather modelling to understand tropical cyclone dynamics in the region. She uses these interdisciplinary tools and analyses to predict changes to tropical cyclone characteristics with climate change and thus future consequences to the reef ecosystems. Her dissertation research has also led her to visit Queensland for research collaborations and diving over the Great Barrier Reef.