Factors Affecting the Trajectory and Intensification of Tropical Cyclone Yasi
This study ran an ensemble of simulations with different physics options with the National Center for Atmospheric Research (NCAR) Weather Research and Forecasting (WRF) Model v.3.4.1 to simulate this TC event. The ensemble revealed the difficulties in capturing both the intensity and track of an event of this size and magnitude and the simulated TC's sensitivity physics parameters, especially the cumulus parameterization. The ensemble was able to present the most appropriate model set up and the boundary and initial condition data required to accurately simulate the extreme event based on a criterion of: track, timing and intensity. Further simulations with altered sea surface temperatures (SSTs) demonstrate that a warming along the coastline, analogous to a warmer East Australian Current acts to maintain and increase TC intensification up to landfall as Yasi did. Increasing SSTs over the whole South Pacific acts to greatly increase TC intensity and push the track of the storm further southwards.
This modeling work is combined with analysis and quantification of changes to SST; nutrient and sediment loading; and chlorophyll a concentrations in surface waters along the coastline over the Great Barrier Reef from before to after TC Yasi with remotely sensed data sets such as from MODIS. The data validates the wide spread interaction that TC Yasi and events of this size and intensity have with the ocean surface and the negative and long term impacts they can have on coastal and marine ecosystems. The modeling work and the remote sensing analysis suggest that increasing SSTs have the potential to increase TC intensity and the extent of the negative impacts to coastal ecosystems.