2013/07/19 by Neil T. Sanger, Neil Thomas Sanger, Michael T. Montgomery +2 · 65 citations
Earth and Planetary Sciences · Environmental Science · #African easterly jet #Atmospheric sciences #Boundary layer #Climate variability and models #Climatology #Cyclone (programming language) #Dropsonde #Environmental science #Eye #Geography #Geology #Maximum sustained wind #Mechanics #Meteorology #Ocean Waves and Remote Sensing #Physics #Storm #Tropical and Extratropical Cyclones Research #Tropical cyclogenesis #Tropical cyclone #Tropical wave #Wind gradient #Wind shear #Wind speed
paper · pdf · doi:10.1175/mwr-d-12-00306.1
published in Monthly Weather Review 142(1), 3-28 (American Meteorological Society)
openalex publication_date 2013/07/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/26
Abstract An observational study of tropical cyclone intensification is performed using dropsondes, in situ flight-level data, satellite imagery, and Electra Doppler Radar (ELDORA) during the spinup of Tropical Storm Jangmi (2008) in the western North Pacific. This event was observed with research aircraft during the Tropical Cyclone Structure 2008 (TCS08) field experiment over the course of 3 days as Jangmi intensified rapidly from a tropical storm to a supertyphoon. The dropsonde analysis indicates that the peak azimuthally averaged storm-relative tangential wind speed occurs persistently within the boundary layer throughout the spinup period and suggests that significant supergradient winds are present near and just within the radius of maximum tangential winds. An examination of the ELDORA data in Tropical Storm Jangmi reveals multiple rotating updrafts near the developing eye beneath cold cloud top temperatures ≤−65°C. In particular, there is a 12-km-wide, upright updraft with a peak velocity of 9 m s−1 with collocated strong low-level (z < 2 km) convergence of 2 × 10−3 s−1 and intense relative vorticity of 4 × 10−3 s−1. The analysis of the corresponding infrared satellite imagery suggests that vortical updrafts are common before and during rapid intensification. The findings of this study support a recent paradigm of tropical cyclone intensification in which rotating convective clouds are important elements in the spinup process. In a system-scale view of this process, the maximum tangential wind is found within the boundary layer, where the tangential wind becomes supergradient before the air ascends into the eyewall updraft.