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Abstract:
Tropical cyclone (TC) track forecasts have considerably improved during past decades, while TC intensity forecasts still remain challenging. In this study, the orthogonal nonlinear forcing singular vectors (O-NFSVs) for emulating the impact of model uncertainties is used for conducting TC ensemble forecasting experiments with the Weather Research and Forecasting (WRF) model , with a focus on improving TC intensity forecasting skill. The O-NFSVs approach is compared with the traditional stochastic kinetic energy backscatter (SKEB) and stochastically perturbed parameterization tendencies (SPPT) schemes. The results demonstrate that the O-NFSVs ensembles generally provide a better representation of the model uncertainties affecting TC intensification, with much better deterministic and probabilistic skills. These results also extend to the forecasting skill for TC track although the perturbations were not optimized for that specific purpose. The O-NFSVs are therefore appropriate perturbation structures to describe the uncertainties for the TC intensity and track, also favorable for recognizing its rapid intensification process in forecasts.
