为提升区域数值预报系统2 m气温预报性能,利用土壤温度和土壤湿度站点观测资料,对中国气象局陆面数据同化系统(CMA Land Data Assimilation System,CLDAS)陆面资料在浙江地区的精度进行评估,并将其融合应用于浙江省数值预报业务系统。...为提升区域数值预报系统2 m气温预报性能,利用土壤温度和土壤湿度站点观测资料,对中国气象局陆面数据同化系统(CMA Land Data Assimilation System,CLDAS)陆面资料在浙江地区的精度进行评估,并将其融合应用于浙江省数值预报业务系统。结果表明:CLDAS土壤温度、土壤湿度产品相对于美国全球预报系统(Global Forecast System,GFS)分析场,与观测相比具有更小的均方根误差和更高的相关系数,在浙江省有较好的适用性。个例分析表明区域数值模式2 m气温预报对陆面资料变化较敏感,融合CLDAS地表温度、土壤温湿度实时分析产品的初始场,可持续影响到模式预报后期,主要通过地表感热、潜热通量直接影响气温变化。从均方根误差来看,与基于GFS分析场作为陆面初始场的区域模式预报相比,应用了CLDAS陆面资料的模式预报改进了13.6%。2021年7月阶段性应用结果显示,模式初始场融合CLDAS陆面资料后有效提高了浙江省2 m气温预报水平,融合后的预报改进效果夜间较白天明显,且晴热高温天气背景下较梅雨期、台风期改进更佳。高温天气预报评估进一步表明,CLDAS陆面资料的应用对浙江省高温事件预报有较好的改进,尤其对金衢盆地等高温区改进明显。展开更多
基于欧洲中期天气预报中心(European Center for Medium-range Weather Forecasts, ECMWF)集合预报资料及浙江全省自动站降水观测资料,采用贝叶斯模型平均(Bayesian Model Average, BMA)方法对2020年浙江超长梅汛期开展降水概率预报订...基于欧洲中期天气预报中心(European Center for Medium-range Weather Forecasts, ECMWF)集合预报资料及浙江全省自动站降水观测资料,采用贝叶斯模型平均(Bayesian Model Average, BMA)方法对2020年浙江超长梅汛期开展降水概率预报订正试验。采用平均绝对误差、连续等级概率评分、布莱尔评分B_S、Talagrand、概率积分变换(Probability Integral Transform, PIT)直方图及属性图检验方法对本次过程BMA订正前后的概率预报进行对比分析,结果表明:(1)50 d为适用于浙江梅汛期ECMWF集合预报订正的BMA最优训练期,经最优训练期的BMA订正后,预报离散度有所增加,预报误差有所下降;(2)BMA对0.1 mm、10.0 mm和25.0 mm阈值降水的订正效果显著,经BMA订正后3个阈值的降水预报B_S下降率分别为25.92%、19.29%、4.76%,但对超过50.0 mm的降水订正效果不明显,且随着降水阈值增加,BMA的订正效果减弱;(3)在强降水个例中,BMA能有效减少各阈值降水预报概率大值落区偏差,使订正后的降水预报概率大值区与观测落区更一致。展开更多
Initialization of tropical cyclones plays an important role in typhoon numerical prediction. This study applied a typhoon initialization scheme based on the incremental analysis updates (IAU) technique in a rapid refr...Initialization of tropical cyclones plays an important role in typhoon numerical prediction. This study applied a typhoon initialization scheme based on the incremental analysis updates (IAU) technique in a rapid refresh system to improve the prediction of Typhoon Lekima (2019). Two numerical sensitivity experiments with or without application of the IAU technique after performing vortex relocation and wind adjustment procedures were conducted for comparison with the control experiment, which did not involve a typhoon initialization scheme. Analysis of the initial fields indicated that the relocation procedure shifted the typhoon circulation to the observed typhoon region, and the wind speeds became closer to the observations following the wind adjustment procedure. Comparison of the results of the sensitivity and control experiments revealed that the vortex relocation and wind adjustment procedures could improve the prediction of typhoon track and intensity in the first 6-h period, and that these improvements were extended throughout the first 12-h period of the prediction by the IAU technique. The new typhoon initialization scheme also improved the simulated typhoon structure in terms of not only the wind speed and warm core prediction but also the organization of the eye of Typhoon Lekima. Diagnosis of the tendencies of variables showed that use of the IAU technique in a typhoon initialization scheme is efficacious in resolving the spurious high-frequency noise problem such that the model is able to reach equilibrium as soon as possible.展开更多
文摘为提升区域数值预报系统2 m气温预报性能,利用土壤温度和土壤湿度站点观测资料,对中国气象局陆面数据同化系统(CMA Land Data Assimilation System,CLDAS)陆面资料在浙江地区的精度进行评估,并将其融合应用于浙江省数值预报业务系统。结果表明:CLDAS土壤温度、土壤湿度产品相对于美国全球预报系统(Global Forecast System,GFS)分析场,与观测相比具有更小的均方根误差和更高的相关系数,在浙江省有较好的适用性。个例分析表明区域数值模式2 m气温预报对陆面资料变化较敏感,融合CLDAS地表温度、土壤温湿度实时分析产品的初始场,可持续影响到模式预报后期,主要通过地表感热、潜热通量直接影响气温变化。从均方根误差来看,与基于GFS分析场作为陆面初始场的区域模式预报相比,应用了CLDAS陆面资料的模式预报改进了13.6%。2021年7月阶段性应用结果显示,模式初始场融合CLDAS陆面资料后有效提高了浙江省2 m气温预报水平,融合后的预报改进效果夜间较白天明显,且晴热高温天气背景下较梅雨期、台风期改进更佳。高温天气预报评估进一步表明,CLDAS陆面资料的应用对浙江省高温事件预报有较好的改进,尤其对金衢盆地等高温区改进明显。
文摘基于欧洲中期天气预报中心(European Center for Medium-range Weather Forecasts, ECMWF)集合预报资料及浙江全省自动站降水观测资料,采用贝叶斯模型平均(Bayesian Model Average, BMA)方法对2020年浙江超长梅汛期开展降水概率预报订正试验。采用平均绝对误差、连续等级概率评分、布莱尔评分B_S、Talagrand、概率积分变换(Probability Integral Transform, PIT)直方图及属性图检验方法对本次过程BMA订正前后的概率预报进行对比分析,结果表明:(1)50 d为适用于浙江梅汛期ECMWF集合预报订正的BMA最优训练期,经最优训练期的BMA订正后,预报离散度有所增加,预报误差有所下降;(2)BMA对0.1 mm、10.0 mm和25.0 mm阈值降水的订正效果显著,经BMA订正后3个阈值的降水预报B_S下降率分别为25.92%、19.29%、4.76%,但对超过50.0 mm的降水订正效果不明显,且随着降水阈值增加,BMA的订正效果减弱;(3)在强降水个例中,BMA能有效减少各阈值降水预报概率大值落区偏差,使订正后的降水预报概率大值区与观测落区更一致。
基金Science and Technology Project of Zhejiang Province(LGF20D050001)East China Regional Meteorological Science and Technology Innovation Fund Cooperation Project(QYHZ201805)Meteorological Science and Technology Project of Zhejiang Meteorological Service(2018ZD01,2019ZD11)。
文摘Initialization of tropical cyclones plays an important role in typhoon numerical prediction. This study applied a typhoon initialization scheme based on the incremental analysis updates (IAU) technique in a rapid refresh system to improve the prediction of Typhoon Lekima (2019). Two numerical sensitivity experiments with or without application of the IAU technique after performing vortex relocation and wind adjustment procedures were conducted for comparison with the control experiment, which did not involve a typhoon initialization scheme. Analysis of the initial fields indicated that the relocation procedure shifted the typhoon circulation to the observed typhoon region, and the wind speeds became closer to the observations following the wind adjustment procedure. Comparison of the results of the sensitivity and control experiments revealed that the vortex relocation and wind adjustment procedures could improve the prediction of typhoon track and intensity in the first 6-h period, and that these improvements were extended throughout the first 12-h period of the prediction by the IAU technique. The new typhoon initialization scheme also improved the simulated typhoon structure in terms of not only the wind speed and warm core prediction but also the organization of the eye of Typhoon Lekima. Diagnosis of the tendencies of variables showed that use of the IAU technique in a typhoon initialization scheme is efficacious in resolving the spurious high-frequency noise problem such that the model is able to reach equilibrium as soon as possible.
