[A-AS05] From Weather Predictability to Controllability

[AAS05-03] Multi-scale Interaction and Variability of the Tropical Cyclone Intensification Onset

*Masashi Minamide¹ (1.The University of Tokyo)

Keywords:Tropical cyclones, Numerical weather prediction

Predicting tropical cyclone intensity changes, especially the onset of rapid intensification, has been a more challenging topic than tropical cyclone tracking because of its chaotic nature in multi-scale physical process with significant contributions from convective-scale phenomena. Before intensification onset, tropical cyclones experience precession process, in which tilted vortices rotate counterclockwise around the center of circulation, and develop an axisymmetric structure. The forecast uncertainty in precession process limits the predictability of early-stage development and intensification of TCs.
In this study, we have explored the impacts of individual moist convective activity to the predictability and variability of TC intensification onset through the precession process. We conducted sensitivity experiments to explore the contributions of specific convective activities within the inner-core of early-stage TCs to the intensification onset using convection-permitting Weather Research and Forecasting model (WRF-ARW). We that the spatiotemporal variability of convective activity can even govern whether early-stage vortex completes precession and initiates RI. Given the strong nonlinearity of the onset process of RI, the results indicate the potential existence of effective forcing to suppress TC development with butterfly effect.