Tropical Cyclone Characteristics in the High-Resolution Community Atmosphere Model

As high-resolution general circulation models (GCMs) become a tool of choice for the evaluation of tropical cyclones in current and future climate conditions, many questions concerning the reliability of GCMs for tropical cyclone assessments remain. Tropical cyclones are mostly unresolved at high GCM resolutions of about 30-60 km, and still challenged at the highest resolutions between 12-30 km. In this study we investigate individual storm characteristics of both idealized and decadal climate simulations using the NCAR supported Community Atmosphere Model CAM 5.1. In particular, the hydrostatic finite-volume (FV) version of CAM 5.1 is used at the horizontal equatorial grid spacing of approximately 25 km. The idealized simulations consist of the evolution of single vortex seed that is initially in gradient-wind and hydrostatic balance and intensifies over a 10-day period. For these tests the model is configured in aqua-planet mode with constant sea surface temperatures (SSTs). The decadal climate simulations are configured in a manner similar to the Atmospheric Model Intercomparison Project (AMIP) with prescribed SSTs, and select individual storms are chosen for this analysis. The investigation sheds light on the tropical cyclone size, structure and intensity differences between the idealized and full decadal simulations. Furthermore, an additional comparison to observations is presented.