学术论文

      不同随机物理扰动方案在一次暴雨集合预报中的对比研究

      Comparison of Different Stochastic Physics Perturbation Schemes on a Storm-Scale Ensemble Forecast in a Heavy Rain Event

      摘要:
      天气预报系统对模式本身的误差非常敏感,尤其是次网格物理参数化过程的不确定性对天气预报系统的准确性具有重要影响.由于风暴尺度系统时间尺度较小、发展剧烈以及高度非线性,传统的中期集合预报方法不再适用.本文将随机物理扰动方案(Stochastic Perturbed Parameterization Tendenciesscheme,SPPT)、随机动能补偿方案(Stochastic Kinetic-Energy Backscatter scheme,SKEB)以及混合模式扰动方案(SKEB+SPPT)引入风暴尺度集合预报系统,对2014年5月31日安徽的一次强对流天气过程进行数值模拟,并评估集合预报效果和分析扰动特征及能量变化特征.结果表明:适用于本次天气过程的SPPT方案的时空尺度分别为3h和60 km;混合模式扰动方案提高了SPPT方案和SKEB方案的集合预报离散度,减小了预报误差,且提高了预报的准确性;混合模式扰动方案减少了SPPT方案和SKEB方案对降水的空报和漏报;混合模式扰动方案的扰动空间分布在预报初期与SPPT方案类似,随着预报时间的推移,其扰动空间形态分布转换为与SKEB方案类似;混合模式扰动方案的扰动动能在所有尺度上都要明显大于其他两种方案,表明两种随机物理扰动方案的结合可以有效弥补两者在不同尺度上的能量缺失.
      Abstract:
      A weather forecast system is very sensitive to the model error.Particularly,the uncertainty in sub-grid parametrization process has the essential effect on the accuracy of weather forecast system.Due to small time scale,fast and strong nonlinear development of the storm-scale system,the traditional medium-range ensemble forecast method is obsolete.Stochastic Perturbed Parameterization Tendencies (SPPT) scheme,Stochastic Kinetic-Energy Backscatter (SKEB) scheme and mixed model perturbation (SKEB+SPPT) scheme are added to the storm-scale ensemble forecast system,in order to simulate a severe convection weather process in Anhui province on 31 May 2014.This paper evaluates the performance of ensemble forecast and analyses the characteristics of stochastic perturbation and kinetic energy evolvement.Results shows that the 60 km length scale and 3 h decorrelation time scale in SPPT are best in this case.The mixed model perturbation scheme increases (reduces) the spread and accuracy (the forecast error) of SPPT scheme only or SKEB scheme only,and decreases the mistaking and missing forecast of precipitation.The perturbation spatial distribution of the mixed model perturbation scheme is similar to that of the SPPT scheme at the beginning of forecast.As forecast time goes on,the perturbation spatial distribution is transformed and is similar to that of SKEB.The kinetic energy perturbation of the mixed model perturbation scheme is obviously bigger than that of SPPT only or SKEB only in all scales,indicating that the combination of the two stochastic perturbation schemes can efficiently complement the missing energy in different scales.
      作者单位: 南京信息工程大学气象灾害预报预警与评估协同创新中心,南京210044;气象灾害教育部重点实验室/南京信息工程大学,南京210044
      刊 名: 高原气象 ISTICPKU
      Journal: Plateau Meteorology
      年,卷(期): 2017, 36(2)
      分类号: P456.7
      在线出版日期: 2017年6月20日
      基金项目: 国家自然科学基金项目