资源环境科技发展态势分析平台

Recent composite analysis of landfalling tropical cyclones (TCs) suggests a rain rate peak in the early morning, which contradicts the typically observed peak in convective precipitation over land seen in the late afternoon to early evening. We conducted a set of idealized simulations of TCs and analyzed observational data from TC Bebinca (2018), which stalled near the shoreline of southern China. We show a distinct land-sea contrast in the diurnal variation of TC precipitation and an 8-12 hr offset between the peak precipitation time over land compared with that over the sea in a TC that stalls at the shoreline. The highest land surface temperature and maximum low-level buoyancy during the afternoon led to peak precipitation over land at this time. However, the peak precipitation over the sea in the early morning was generated by the increase in relative humidity caused by nighttime radiative cooling and enhanced instability.