Chih, Cheng-Hsiang, Graduate Institute of Earth
Science/Atmospheric Science, Chinese Culture University, China and Kun-Hsuan
Chou, Chinese Culture University
Typhoon Sinlaku (2008)
had the most observational data which conducted by the T-PARC field campaign
and it reintensified after passing Taiwan. In this study, a series of numerical
simulations are conducted using the advanced research version of the Weather
Research and Forecasting model (V3.2) to examine the impact of different
terrain conditions and vortex structures on the eyewall evolution when Sinlaku
crossing Taiwan.
For the simulation
results in the experiment with the implanted bogused vortex as well as full
terrain, the eyewall evolutions are well simulated, i.e., the eyewall contract
before landfall, break down over land, and reorganize after landfall. However,
the eyewall maintain well structure during the entire simulation period in both
the without terrain and flat terrain with 1-m height experiment. These results
indicate that the reorganization of the eyewall could not be simulated in these
two experiments.
On the other hand,
through the sensitivity experiments of different vortex structure, it is shown
that the storm with larger strength or eyewall radius tends to induce stronger
wind and rainfall at the outer part of storm when it crossing terrain. This
result indicates that the vortex contained larger angular momentum is much
favorable to reform a new eyewall from the contraction of the outer rainband
after it was affected by terrain. Based on these sensitivity experiments, it is
suggested that the topography and the structure of the tropical cyclone play
important roles for trigger and modulation the unique eyewall evolutions which
induced for the tropical cyclone passing the island.