Impacts of Soil Moisture on the Numerical Simulation of a Post-Landfall Storm
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Surface heat and moisture fluxes are important to the evolution of a tropical storm after its landfall. Soil moisture is one of the essential components that influence surface heating and moisture fluxes. In this study, the impact of soil moisture on a pre-landfall numerical simulation of Tropical Storm Bill (2015), which had a much longer lifespan over land, is investigated by using the research version of the NCEP Hurricane Weather Research and Forecasting (HWRF) model. It is found that increased soil moisture with SLAB scheme before storm’s landfall tends to produce a weaker storm after landfall and has negative impacts on storm track simulation. Further diagnoses with different land surface schemes and sensitivity experiments indicate that the increase in soil moisture inside the storm corresponds to a strengthened vertical mixing within the storm boundary layer, which is conducive to the decay of storm and has negative impacts on storm evolution. In addition, surface diabatic heating effects over the storm environment are also found to be an important positive contribution to the storm evolution over land, but their impacts are not so substantial as boundary layer vertical mixing inside the storm. The overall results highlight the importance and uncertainty of soil moisture in numerical model simulations of landfalling hurricanes and their further evolution over land.
Key wordssoil moisture tropical storm tropical cyclone landfall land surface numerical simulation
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This study is initially conducted when the first author (FZ) visited the University of Utah. The research was supported by National Science Foundation Award #AGS-1243027 (ZP and FZ). High-performance computing support from Yellowstone (ark:/85065/d7wd3xhc), provided by NCAR’s Computational and Information Systems Laboratory (CISL) and the Center for High-Performance Computing (CHPC) at the University of Utah, is greatly appreciated. Authors also thank the Development Testbed Center (DTC) at the National Center for Atmospheric Research (NCAR) for their efforts to make the community research version of the HWRF model available on a public website. The first and third authors (FZ and CW) were also supported by the National Natural Science Foundation of China (41805032), and the Fundamental Research Funds of the Central Universities (lzujbky-2017-71).
Two anonymous reviewers are appreciated for their constructive comments that are very helpful for improving the manuscript.
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