Wu, Y.-J., Y.-C. Liou, Y.-C. Lo, S.-L. Tai, S.-F. Chang, and J. Sun, 2021: Precipitation processes of a thunderstorm occurred on 19 August 2014 in northern Taiwan documented by using a high resolution 4DVar data assimilation system. J. Meteor. Soc. Japan, 99,
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The evolution of a heavy rainfall event occurred on 19 August 2014 in northern Taiwan is investigated with observed data and analyses from a newly-developed 4DVar data assimilation system named IBM_VDRAS. This event possesses different precipitating processes and track from those frequently observed in that region. The kinematic, thermodynamic, and microphysical fields of the convective cells are analyzed in details to explain the mechanisms which help to maintain the structure of the convective system and lead to heavy precipitation.
- The mechanisms leading to this event and its maintenance involve the interactions among sea breeze, cold air outflow, cell merging, and terrain. A correct description of the interactions among these factors in a numerical model is a key to the improvement of the forecast.
- Sensitivity experiments of quantitative precipitation forecast (QPF) show that the terrains prevent the location of major rainfall from shifting outside of Taipei Basin.
- By assimilating surface data, the model can better predict the position of the rainfall.