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The formation of Typhoon Durian (2001) was simulated well by the Weather Research and Forecasting model. The vorticity field was separated into three scales: small scale (L 120 km), where L is wavelength. During the formation, small-scale vorticity anomalies, associated with convection, aggregated radially inward and rotated anticlockwise. The system-scale vorticity field presented a distinct mid-level vortex before genesis, and then a well-organized low-level vortex. The spectral power of the low-level vorticity at the small scale barely changed, while that at the system scale continued to grow steadily. The vorticity growth or spin-up of the near-surface tropical cyclone embryo was mainly due to the convergence of vertical vorticity flux at the planetary boundary layer. The positive (negative) effect of vorticity flux convergence at lower (middle-to-upper) levels appears to cause the shift of system-scale vorticity center from the middle to lower troposphere.

In July 2013, an extreme precipitation event occurred in Sichuan, China, causing severe flooding, debris flows, and substantial losses. Moisture sources and transport of this event and quantification of the contribution from moisture sources were studied using the Lagrangian method. The results show that the vast majority of particles influencing this event originated from the relatively lower troposphere south of the precipitation region and can be traced back to the Arabian Sea. Moreover, the total moisture from the source regions accounts for more than 80% of the precipitation; moisture originating from the India Peninsula–Bay of Bengal–Indo-China Peninsula region had the highest contribution.