ACCESS-rAM3 sensitivity simulations of thunderstorms over the Tiwi Islands
Chris Chambers
Results from ACCESS-rAM3 simulations of an afternoon thunderstorm complex over the Tiwi Islands known as “Hector” are presented. Hector is a consistent convective feature that develops over the islands on most afternoons in the Northern Territory pre-monsoon season (October to December). It provides a unique natural laboratory for studying the mechanisms of diurnal convection, sea-breeze convergence, and tropical thunderstorm dynamics.
Initial results from the 1 km high-resolution simulations are encouraging, with the simulation generating converging afternoon sea-breeze boundaries that trigger vigorous thunderstorm development over the islands in the afternoon - closely resembling observed behaviour. A case study from 12 December 2016 is compared with a time-lapse using 3D plotting to study the timing of initiation and the updraft intensity. Using different initialisations we are testing the sensitivity of the thunderstorm to environmental conditions, including atmospheric temperature, moisture, and wind profiles. Preliminary experiments suggest a contraction of the thunderstorm complex when sea surface temperatures are reduced, indicating potential links between ocean surface forcing and convective development.
These experiments have the potential to serve as a testbed for evaluating high-resolution regional models in their ability to simulate complex land-sea interactions and mesoscale convection in tropical environments.
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