王璐璐,闵锦忠,刘畅. 2020. 基于WRF模式的对流尺度边界层方案参数随机扰动方法研究[J]. 气象学报, (0):-, doi:10.11676/qxxb2020.038
基于WRF模式的对流尺度边界层方案参数随机扰动方法研究
Research on Stochastic Perturbed Planetary Boundary Layer Scheme Parameters at Convective Scale Based on WRF Model
投稿时间:2019-09-17  修订日期:2020-01-31
DOI:10.11676/qxxb2020.038
中文关键词:  对流尺度集合预报,随机参数扰动,边界层参数化方案,雷暴过程
英文关键词:Convection-permitting  ensemble forecast, stochastic  parameter perturbation, planetary  boundary layer  parameterization scheme, thunderstorms
基金项目:国家重点基础研究发展计划
作者单位E-mail
王璐璐 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/气象灾害教育部重点实验室 wlulu0312@163.com 
闵锦忠 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/气象灾害教育部重点实验室 minjz@nuist.edu.cn 
刘畅 广东省气候中心 953660363@qq.com 
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中文摘要:
      边界层(PBL)参数化方案的准确性会影响模式对近地面变量和大气低层热动力结构的模拟,这对雷暴等强对流天气的预报非常重要。但PBL方案内在的不确定性使得单一预报具有局限性。随机参数扰动(Stochastic parameter perturbation, SPP)方案是一种针对物理参数化方案中不确定的参数进行扰动的集合预报方法,从根源上表征了预报不确定性。本文借助了常用的MYNN PBL方案,使用SPP方法扰动了方案中重要的三个不确定参数,探究了该方法在对流尺度集合预报中对北京一次雷暴过程的影响。同时调整了SPP方法的3个参量(去相关时间尺度、空间尺度和格点标准差)以探究在对流尺度中对MYNN方案中参数进行扰动的最优设置。结果表明:随机扰动MYNN边界层方案参数(SPPM)的方法可以有效提高近地面变量和700hPa以下低层变量的离散度,同时提高了此次短时强降水的位置和强度预报。对三个参量的试验说明去相关时间尺度增大为12h时集合离散度有明显提高。格点标准差增大为0.20时预报技巧也略有提高。去相关空间尺度维持在默认值700km较好,尺度过小(150km)技巧有明显降低。
英文摘要:
      The accuracy of the planetary boundary layer (PBL) parameterization scheme directly affects the forecast of near-surface meteorological variables and the simulation of lower-tropospheric thermodynamic and kinematic structures, which is very important for the forecast of strong convective weathers such as thunderstorms. However, the inherent uncertainties within the PBL schemes make the deterministic forecast obvious limitations. The stochastic parameter perturbation(SPP)scheme is an ensemble perturbation method that perturbs the uncertain parameters in the physical parameterization scheme, which expresses the forecast uncertainty at its source. In this paper, a common PBL scheme named the Mellor-Yamada-Nakanishi-Niino (MYNN) parameterization scheme was employed and three important uncertain parameters in the scheme were perturbed using the SPP method. Its influence on the forecast of a thunderstorm process happened in Beijing was explored in the convection-permitting ensemble prediction system (EPS). Considering the characteristics of the convection-permitting EPS, the three parameters (the decorrelation time scale, the decorrelation spatial length scale and the standard deviation in the grid point) of the SPP method were adjusted to explore the optimal pattern to perturb the parameters in the MYNN scheme. Results show that the stochastic perturbed parameters in the MYNN PBL scheme (SPPM) method effectively improves the spread of near-surface variables and low-level variables below 700hPa. The position and intensity prediction of the short-term heavy precipitation was also improved. The test of the three parameters shows that the ensemble spread was significantly improved when the decorrelation time scale was selected as 12h. The skill is also slightly improved when the standard deviation of the grid point is increased to 0.20. The decorrelation spatial length scale is recommended to maintain at a default value of 700 km. The skill is reduced when it is too small (150 km).
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