Surface evaporation is an important factor in the hydrological cycle. It is unknown however how much the recycling of surface precipitation contributes to rainfall in a landfalling tropical cyclone. In this study, ensemble simulations were performed using the Weather Research and Forecasting model to quantify the contribution of re‐evaporation of surface precipitation to rainfall in Typhoon Utor (2013) during and after its landfall over South China. Two sets of ensemble simulations were conducted, one with all default model settings (CTRL) and the other with the surface precipitation rate in the land surface model being set to zero within a radius of 500 km from the storm center so that the re‐evaporation of surface precipitation was removed. Results show that the re‐evaporation of surface precipitation contributed about 15–20% to the total rainfall in the inner core within a 100‐km radius from the storm center after landfall. It is found that the removal of surface precipitation in the land surface model reduced soil moisture and thus surface latent heat flux, which led to a slightly weaker storm, thus the weaker boundary layer inflow and reduced inward moisture transport into the inner‐core region of the storm. The results demonstrate that the reduced surface evaporation and inward moisture transport contributed about 30–40 and 60–70%, respectively, to the decrease in precipitation in the inner‐core region in the experiment with the re‐evaporation of surface precipitation removed.

Tropical cyclones (TCs) can exert destructive potential and impact on human activities, causing substantial damage after their landfalls, particularly in well-populated areas with high economic development. The disaster potential caused by strong winds, torrential rainfall, and storm surge is largely related to the TC intensity during and after landfall. Once TCs move over land, they often weaken due to the loss of moisture supply and the increase in surface roughness (Tuleya, 1994;Tuleya & Kurihara, 1978), which is different from the intensity change over the open ocean.Because numerical models have limited skills in predicting TC intensity change due to the complex multiscale dynamic and thermodynamic processes, empirical decay models have often been used to predict TC weakening after landfall (

This study examines whether there are significant differences in intensity and destructiveness of landfalling tropical cyclones (TCs) over China in central Pacific warm (CPW), eastern Pacific warm (EPW) and La Niña (LA) years. By analyzing different seasons and locations of TCs making landfall over China, it was found that TCs in LA years generally had a larger power dissipation index (PDI) and may cause more disasters in China, while TCs in EPW years had a larger PDI over South China in autumn. A larger PDI of TCSC (landing location in Southern China) usually occurred in EPW years and a larger PDI of TCEC (landing location in Eastern China) occurred in LA years, compared with CPW years. The TCs in LA years were generally stronger, more frequent, and of longer duration over China, because of the positive relative humidity (RH) anomalies, the significant anomalous cyclone that occupied the South China Sea (SCS), and the easterly wind anomalies providing a beneficial steering flow for TCs making landfall. In EPW years, although TCs were less frequent, they had stronger intensity when making landfall and a longer lifetime over land which was mainly caused by a broad band of anomalous westerlies over the SCS giving rise to a belt of positive relative vorticity anomalies, as well as the slow translation speed of TCs before landfall supplying more energy for TCs to survive over land. Overall, we conclude that greater caution is warranted when TCs occur in LA and EPW years, as they may result in more serious disasters in China.

This study analyzes the spatiotemporal distributions and climate trends of tropical cyclone (TC)-induced extreme hourly precipitation (EXHP) in the warm season (May–September) during 1975–2018 over China and the involved mechanisms. Each TC is classified as a high-, mid-, and low-EXHP TC according to the total amount of EXHP it produces over China during its lifetime. Results show that low-EXHP TCs have a greater contribution to the total TC-induced EXHP over southern and southwestern China, whereas high-EXHP TCs make greater contributions over eastern and northeastern China as they tend to move northwestward after making landfall. It is shown that, although the total frequency of EXHP-producing TCs displays a decreasing trend, the total frequency of TC-induced EXHP over China shows a significant increasing trend, which is largely contributed by the high-EXHP TCs. To explore the possible mechanisms responsible for the different characteristics in EXHP-producing TC groups, we further analyze the large-scale environmental conditions with respect to three groups by composite analysis. The cooperation of large-scale environmental fields between high and low levels provides favorable conditions for the intensification of TCs and the enhancement of the TC-induced precipitation for the high-EXHP group, such as stronger divergence at high levels, weaker vertical wind shear, more sufficient water vapor, and more conducive steering airflow over the southeastern and eastern area of mainland China. The westward and northward movement of western North Pacific subtropical high is conducive to the northward shift of TC tracks, thus contributing to the high frequency of TC-induced EXHP over the eastern area of mainland China.