黄淮地区副高边缘型降水数值预报精细化检验

Refined Verification of Numerical Forecast of Subtropical High Edge Precipitation in Huanghuai Region

  • 摘要: 以2020—2021年5—10月副高边缘型明显降水过程作为研究对象,针对黄淮地区太行山南麓、伏牛山东麓、东部平原3个典型区域,采用多种检验方法对CMA-MESO,CMA-SH9两模式降水日变化预报性能进行评估。结果表明:在山区,CMA-MESO预报有效降水时次占比与降水强度均偏小,CMA-SH9则相反,两模式分别在伏牛山东麓的04:00—10:00(北京时,下同)和太行山南麓的10:00—16:00预报有效降水时次占比偏小(大)更为显著;在平原,CMA-MESO对03:00—07:00和17:00—20:00有效降水时次占比显著低估,CMA-SH9对于17:00—20:00降水量的高估则主要来源于降水强度预报明显偏大。FSS(fractional skill score)评分结果显示:CMA-MESO对于伏牛山东麓15:00—17:00及21:00—22:00、东部平原02:00—04:00等时段10 mm·h-1以上降水预报能力优于CMA-SH9,在太行山南麓17:00—23:00则相反。基于STFSS(spatial temporal fractional skill score)评分的评估表明:CMA-SH9对于太行山南麓前一日14:00—当日02:00的降水预报较实况显著偏晚,CMA-MESO对于伏牛山东麓02:00—08:00及平原地区08:00—14:00的降水预报均表现出较实况偏早的特征。

     

    Abstract: Taking precipitation processes at the edge of subtropical high as target objects, three typical sub-regions including the southern foothills of Taihang Mountains, the eastern foothills of Funiu Mountains, and the eastern plains in Huanghuai Region are investigated, according to the topography and precipitation distribution characteristics. On this basis, using multi-source fusion precipitation data of National Meteorological Information Center, the precipitation refinement verification index, FSS (fractional skill score) and STFSS (spatial temporal fractional skill score) that adds the temporal neighborhood are used to evaluate the forecasting performance of the precipitation diurnal variation of CMA-MESO and CMA-SH9. The results show that the precipitation frequency and intensity by CMA-MESO in mountainous areas are smaller than observations, leading to significant underestimation, while results by CMA-SH9 are both stronger. The deviation of precipitation amount forecast of CMA-MESO in plain area mainly comes from the deviation of precipitation frequency. The precipitation intensity forecast by CMA-SH9 is stronger than observations in the southern foothills of Taihang Mountains, and the forecast precipitation frequency in the afternoon is significantly larger. For the early morning to morning period in the eastern foothills of Funiu Mountains, the frequency of precipitation by CMA-MESO is significantly lower than observations, while the diurnal variation of precipitation intensity is better than that of CMA-SH9. For the eastern plains, the overestimation of precipitation in early evening by CMA-SH9 mainly comes from the significantly larger precipitation intensity, while CMA-MESO significantly underestimates the frequency of precipitation in early evening and early morning. Based on the analysis of FSS, CMA-MESO is superior to CMA-SH9 in hourly precipitation forecast of more than 10 mm during afternoon to mid-night in the eastern foothills of Funiu Mountains and 0200 BT to 0400 BT in the night in the eastern plains, but the conclusion is opposite in the southern foothills of Taihang Mountains in the nighttime. STFSS can better evaluate the temporal and spatial uncertainty of hourly precipitation forecasts. Precipitation forecasts of CMA-SH9 in southern foothills of Taihang Mountains from the afternoon to the first half of the night significantly lag behind observations, but its spatial-deviation-scale and performance is better than CMA-MESO. The precipitation forecast of CMA-MESO from 0200 BT to 0800 BT in the eastern foothills of Funiu Mountains is significantly ahead of observations, and the advance time is more obvious in the eastern plains in the morning.

     

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