大气科学2017，Vol.41Issue(1)：30-42,13.DOI:10.3878/j.issn.1006-9895.1605.15233
风暴尺度集合预报中的混合初始扰动方法及其在北京2012年“7.21”暴雨预报中的应用
A Blending Method for Storm-Scale Ensemble Forecast and Its Application to Beijing Extreme Precipitation Event on July 21, 2012
摘要
Abstract
In order to overcome the under-dispersive problem in the storm-scale ensemble forecast system (SSEFs),a new blending method to generate initial perturbation is designed and tested for the WRF SSEFs.This new scheme is based on the combination of the ETKF (Ensemble Transform Kalman Filter) and the Barnes filter for scale decomposition.This scheme is applied to the simulation of the Beijing extreme precipitation event on July 21,2012and the neighborhood methods is employed to verify the performance of this new scheme.Results indicate that the blending method can effectively solve the scale mismatch problem in the lateral boundary in storm-scale ensemble prediction system,in which ETKF80 (with wavelength scale of 180 km) and Down (Dynamical downscaling) show the best overall performance.The Dispersion Fractions Skill Score (DFSS) shows that the ETKF has a larger spread in small scales during the period of warm area precipitation while Down produces a larger spread at large scales during period of frontal precipitation.The experiments with initial perturbations generated by the blending method take advantage of both the ETKF and Down.The ETKF180 (with wavelength scale of 180 km) generates the most reasonable ensemble spreads.Results also indicate that in order to get better ensemble spread in SSEFs,not only the lateral scale mismatch but also some other elements (such as the interaction between different scales of initial perturbation) should be considered.The blending method ETKF180 also improves the precipitation probability forecast.关键词
风暴尺度集合预报系统/集合转换卡尔曼滤波/混合初始扰动/离散度/概率预报Key words
Storm-scale ensemble forecast system/Ensemble transform Kalman filter/Blending initial perturbation/Spread/Probability prediction分类
天文与地球科学引用本文复制引用
庄潇然,闵锦忠,王世璋,周凯,蔡沅辰..风暴尺度集合预报中的混合初始扰动方法及其在北京2012年“7.21”暴雨预报中的应用[J].大气科学,2017,41(1):30-42,13.基金项目
国家自然科学基金项目41430427、40975068 （）
National Natural Science Foundation of China (Grants 41430427 and 40975068) （Grants 41430427 and 40975068）
