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RMAPS-RISE降水实况分析产品在北京区域的检验评估

Quality Assessment of the Precipitation Analysis Products from RMAPS-RISE in Beijing

  • 摘要: 采取非独立和独立检验两种方式,利用北京地区2022年528个地面自动气象站质控后逐小时观测降水数据作为“真值”,对睿思(RMAPS-RISE)1 h累积降水量分析产品在北京地区的适用性进行评估,并重点检验评估2022年汛期降水分析产品的质量,首次采用欧洲空间局(European Space Agency, ESA)土地覆盖数据评估汛期降水分析产品在不同下垫面区域的误差情况,并选取3次不同强度降水过程进行个例检验。结果表明,两种检验方式中降水分析产品与站点观测之间的误差均较小、相关性高,在北京具有很好的适用性,汛期均方根误差和平均绝对误差明显大于非汛期,非独立检验的误差整体优于独立检验。汛期降水分析产品在北京市16个区的相关系数均在0.93以上,平均绝对误差小于0.04 mm/h,均方根误差除通州区外均在0.4 mm/h以下,平均绝对误差和均方根误差较大的站是分布于通州、延庆、昌平和顺义四区的独立检验站,并且独立检验站高估明显。非独立检验和独立检验检验这两种检验方式中,RMAPS-RISE降水分析产品在林地、草地、农田、建筑区和裸地这五种不同下垫面的误差相差不大,并且下垫面区域是草地时相关系数最高。从汛期降水分级检验结果来看,均方根误差随着降水量级增加逐渐增大,小雨为0.45 mm/h,大暴雨增长到9.02 mm/h,各降水量级的TS评分均在0.91以上,而独立检验站的TS评分稍差,仅在小雨和中雨量级表现稍好。对2022年汛期分散性阵雨、中雨和暴雨3次不同的降水过程,独立检验降水分析产品与观测值的相关系数均超过0.9,降水趋势与观测基本一致,均能准确反映出降水峰值,也能刻画出累计降水量大于100.0 mm的局地强降雨。

     

    Abstract: Based on precipitation measurements after quality control obtained from 528 automatic stations during 2022 in Beijing, we assessed the performance of the 1-hour accumulated precipitation analysis product of RMAPS-RISE through non-independent and independent validation, and the quality of the precipitation analysis product during the flood period of 2022 was specifically assessed. We also evaluated the error of this precipitation analysis product in different underlying surface regions using European Space Agency (ESA) land cover data, and three precipitation events with different intensities were selected for inspection. The results showed that the precipitation analysis products had good correlation (COR), mean error, Mean Absolute Error (MAE), Root-Mean-Square error (RMSE), and bias with observations from automatic stations, and the applicability in Beijing was good. There were more independent validation errors than non-independent validation errors. The RMSE and MAE during the flood period, May to September 2022, were significantly larger than those during the non-flood period. In the flood period of 2022, the COR of the precipitation analysis product in 16 areas of Beijing was above 0.93, the MAE less than 0.04 mm/h, and the RMSE below 0.4 mm/h, except for the Tongzhou area; while automatic stations with large MAE and RMSE in the independent validation were distributed in the Tongzhou, Yanqing, Changping, and Shunyi areas, and precipitation from these stations was significantly overestimated. Errors of precipitation analysis products in tree cover, grassland, cropland, built-up, and bare areas were not significant, and the correlation coefficient was the highest for the underlying surface area in grassland during the flood period of 2022. Evaluation results for precipitation levels in the flood period of 2022, showed that the RMSE increased with an increase in precipitation: the RMSE was 0.45 mm/h in light rain and 9.02 mm/h in downpour; while the TS score remained above 0.91 at different precipitation levels. However, TS score is not good enough for independent validation, performing better only for light and torrential rain. For the three selected precipitation events occurring in Beijing from May to September in 2022, the COR of the precipitation analysis product was above 0.9 in independent validation; while the tendency of the precipitation analysis product appeared consistent with that of observations by automatic stations, the precipitation peak was reflected, and local heavy rainfall was accurately depicted when accumulated precipitation was greater than 100.0 mm.

     

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