| dc.description.abstract | This study develops a dynamical vortex initialization for a global variable-resolution model (MPAS) in application to simulations of westbound typhoons approaching Taiwan. The MPAS employs 60-15-3 km variable-resolution with 3-km resolution in the vicinity of Taiwan. Seven westbound typhoons are investigated including Soudelor (2015), Megi (2016), Nesat (2017), Maria (2018), Mangkhut (2018), Mitag(2019), Lekima(2019) with different tracks and intensities. Dynamical vortex initialization schemes have been proposed and presented in literatures for regional models with uniform grids. In this study, the dynamical vortex initialization scheme conducts a real-case vortex (in a radius of 600 km of the typhoon center) as downscaled from the initial global operational analysis and then implants the generated vortex into the observed location in several tens of 1-h cycling model integration in 3-km resolution of hexagonal grids. In each 1-h cycle, the model re-generated vortex can be relocated and artificially amplified according to the best-track observations.
In this study, the mothed of the relocation in scalars is use Distance Weighted Interpolation method and vectors is use projection method. We will use different physics suites, initial strength, and model resolution to discuss the tracks and intensities in different typhoons, and we also conduct the situation when the vortex near the terrain, and we have to add some limit in vortex to make the influences of terrain minimize.
From the results, the vortex can be intensified to reach observation by the DVI scheme and can give a better structure and intensity than initial condition. The improvement of tracks error in mesoscalse reference physics suite is better than convection permitting physics suite, and v-match is slightly better than p-match. The improvement of intensities error in convection permitting physics suite is better than mesoscalse reference physics suite, and v-match is slightly better than p-match. For the most case, the intensities error can be improved, especially initial intensities error, but the tracks error is only improved in some case.
| en_US |