Tropical Cyclone Simulation Using a Solution-Adaptive Grid Model

The Operational Multiscale Environment model with Grid Adaptivity (OMEGA) is a fully nonhydrostatic numerical weather prediction model that is based on an adaptive, unstructured triangular prism grid. The model's grid is unstructured in the horizontal dimension and structured in the vertical dimension and may be configured as either a limited area or global domain. The horizontal grid resolution can be adapted to static features (e.g., underlying terrain gradients, coastal boundaries) or to the evolving weather (e.g., typhoon circulation). This capability permits the addition of grid elements at any point in space or time, facilitating a continuously varying horizontal resolution that is naturally scale-spanning.

During the 2005 typhoon season, three storms, Haiting, Talim, and Longwang, made landfall on Taiwan at nearly the same location on the eastern side of the island. Haiting and Longwang were sampled during two Dropsonde Observations for Typhoon Surveillance near the TAiwan Region (DOTSTAR) surveillance missions in which dropwindsondes were released around the periphery of each storm at two intervals 24 hours apart. Early observations suggest that Typhoon Haiting's convection decreased markedly between the two observation times, resulting in decreased intensity. Typhoon Longwang appeared to have completed an eyewall replacement between observation times, also resulting in decreased intensity. Nonetheless, both storms impacted Taiwan with heavy wind and rain with Haiting displaying short-term changes in track due to terrain interaction.

OMEGA simulation results will be presented for these storms, highlighting the impact of DOTSTAR data and adaptive grid configurations on track, wind, and rainfall.