航空气象数据转发(Aircraft Meteorological Data Relay,AMDAR)资料具有采样频度高、探测层次密集等特点,能够有效补充高空资料时空分辨率的不足。利用2020年3月1日至5月31日(春季)国家气象信息中心提供的中国区域AMDAR资料和美国国家...航空气象数据转发(Aircraft Meteorological Data Relay,AMDAR)资料具有采样频度高、探测层次密集等特点,能够有效补充高空资料时空分辨率的不足。利用2020年3月1日至5月31日(春季)国家气象信息中心提供的中国区域AMDAR资料和美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)提供的全球预报模式(Global Forecast System,GFS)资料,对不同高度的AMDAR观测资料进行质量分析和控制,通过两周循环同化对比试验检验同化质量控制后的AMDAR资料对分析场和预报场的影响。结果表明:AMDAR资料风速与GFS资料的均方根误差(Root Mean Square Error,RMSE)呈明显的随高度增加而增大趋势,风速、温度的偏差(Bias)也存在随高度增加而增大趋势。对不同高度的AMDAR资料进行质量控制后,AMDAR与GFS资料的RMSE和Bias都有所改进,且AMDAR资料和GFS资料的差值(Observation Minus Background,OMB)更加符合高斯分布。同化质量控制后的AMDAR资料对风、温度和位势高度分析场有一定的改进作用,并且改进可以影响到12 h甚至24 h预报场。同化质量控制后的AMDAR资料能一定程度上提高降水预报技巧,其中中等量级降水预报改进效果明显。展开更多
This study examines the spatio-temporal characteristics of heavy precipitation forecasts in eastern China from the European Centre for Medium-Range Weather Forecasts(ECMWF) using the time-domain version of the Method ...This study examines the spatio-temporal characteristics of heavy precipitation forecasts in eastern China from the European Centre for Medium-Range Weather Forecasts(ECMWF) using the time-domain version of the Method for Object-based Diagnostic Evaluation(MODE-TD). A total of 23 heavy rainfall cases occurring between 2018 and 2021 are selected for analysis. Using Typhoon “Rumbia” as a case study, the paper illustrates how the MODE-TD method assesses the overall simulation capability of models for the life history of precipitation systems. The results of multiple tests with different parameter configurations reveal that the model underestimates the number of objects’ forecasted precipitation tracks, particularly at smaller radii. Additionally, the analysis based on centroid offset and area ratio tests for different classified precipitation objects indicates that the model performs better in predicting large-area, fast-moving, and longlifespan precipitation objects. Conversely, it tends to have less accurate predictions for small-area, slow-moving, and shortlifespan precipitation objects. In terms of temporal characteristics, the model overestimates the forecasted movement speed for precipitation objects with small-area, slow movement, or both long and short lifespans while underestimating it for precipitation with fast movement. In terms of temporal characteristics, the model tends to overestimate the forecasted movement speed for precipitation objects with small-area, slow movement, or both long and short lifespans while underestimating it for precipitation with fast movement. Overall, the model provides more accurate predictions for the duration and dissipation of precipitation objects with large-area or long-lifespan(such as typhoon precipitation) while having large prediction errors for precipitation objects with small-area or short-lifespan. Furthermore, the model’s simulation results regarding the generation of precipitation objects show that it performs relatively well in simulating the generation of large-area and fast-moving precipitation objects. However, there are significant differences in the forecasted generation of small-area and slow-moving precipitation objects after 9 hours.展开更多
对流尺度集合预报(Convection-allowingEnsemblePrediction,CAEP)是提高强对流天气预报能力的重要手段,构造合理的初始扰动是CAEP的关键问题。本文开展基于观测扰动初值法(Perturbed-observation,PO)的CAEP在内蒙古地区的试验,并以动力...对流尺度集合预报(Convection-allowingEnsemblePrediction,CAEP)是提高强对流天气预报能力的重要手段,构造合理的初始扰动是CAEP的关键问题。本文开展基于观测扰动初值法(Perturbed-observation,PO)的CAEP在内蒙古地区的试验,并以动力降尺度(Downscaling,DOWN)方法作为对比,分析PO方法在内蒙古地区CAEP的预报效果,以期为内蒙古地区CAEP的构建提供技术参考。结果表明:(1)PO方法构造的初始扰动能引入内蒙古地区观测资料从而减少背景场的不确定性,且扰动具有充分的增长能力。(2)与DOWN方法相比,PO方法可以显著减少CAEP的短时预报误差,高空和地面要素的RMSE分别减小4%~43%和3%~9%,集合离散度略有减少。高空要素的CRPS评分最大可减少约53%,地面要素的CRPS评分平均减少6%,整体提高了对流尺度集合预报质量。(3)PO方法能够提高短时降水的预报能力,0.1mm、4 mm和13 mm 3个量级的TS评分分别提升了0.015、0.003和0.0015。且降水个例表明,PO方法对降水的落区和量级预报更准确。展开更多
云贵—华南准静止锋使其以北地区成为研究冬季雨雪过渡区内不同降水相态的理想平台。通过对2018年1月25—27日南方凝冻天气过程中天气学和云微物理参数的分析,定性探讨了次冻结层的温度与冰核活化温度对不同降水相态形成的影响,进而利...云贵—华南准静止锋使其以北地区成为研究冬季雨雪过渡区内不同降水相态的理想平台。通过对2018年1月25—27日南方凝冻天气过程中天气学和云微物理参数的分析,定性探讨了次冻结层的温度与冰核活化温度对不同降水相态形成的影响,进而利用耦合BTC降水相态诊断方案(简称“BTC方案”)的WRF(Weather Research and Forecasting)模式,对本次凝冻天气的降水相态、冻雨发生区域与冻雨量进行数值模拟。结果表明:横贯云贵高原和南岭地区的准静止锋导致的锋前“冷—暖—冷”的温度垂直结构有利于多相态降水的形成。耦合BTC方案的WRF模式可模拟出不同降水相态落区的空间分布,其模拟冻雨落区时空分布与观测基本一致,但冰粒的空报率非常高。分析WRF模式模拟的多相态降水时温度、相对湿度和水成物的垂直分布特征,云内水成物初始相态为液态,在高空逆温层存在的前提下,次冻结层中冰核活化温度是区分冻雨和冰粒的临界指标且具有明确的物理机制。利用次冻结层中的冰核活化温度来代替BTC方案中有关冻雨和冰粒的判据后,冻雨落区预报准确率较BTC方案提高了13%,表明直接利用次冻结层的冰核活化温度判断冻雨可行。展开更多
基于准对称混合滑动训练期方法,对近两年来中国气象局陆面同化分析系统(CMA Land Data Assimilation System,CLDAS)输出的日最高气温、日最低气温网格实况分析产品进行订正,以期提高该产品在重庆地区的适用性。结果表明:订正前,2021年CL...基于准对称混合滑动训练期方法,对近两年来中国气象局陆面同化分析系统(CMA Land Data Assimilation System,CLDAS)输出的日最高气温、日最低气温网格实况分析产品进行订正,以期提高该产品在重庆地区的适用性。结果表明:订正前,2021年CLDAS日最高气温产品的平均误差为0.63℃,平均绝对误差为1.14℃,订正后平均误差减小至-0.03℃,平均绝对误差减小至0.64℃,误差小于或等于1℃的准确率由约64%提高到约90%,明显改善了该产品在重庆西部和东南部地区的适用性;订正前,2021年CLDAS日最低气温的平均误差为-0.22℃,平均绝对误差为0.75℃,订正后平均误差减小至-0.03℃,平均绝对误差减小至0.55℃,误差小于或等于1℃的准确率由约91%提高到约93%,改善了该产品在重庆中部地区的适用性。展开更多
文摘航空气象数据转发(Aircraft Meteorological Data Relay,AMDAR)资料具有采样频度高、探测层次密集等特点,能够有效补充高空资料时空分辨率的不足。利用2020年3月1日至5月31日(春季)国家气象信息中心提供的中国区域AMDAR资料和美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)提供的全球预报模式(Global Forecast System,GFS)资料,对不同高度的AMDAR观测资料进行质量分析和控制,通过两周循环同化对比试验检验同化质量控制后的AMDAR资料对分析场和预报场的影响。结果表明:AMDAR资料风速与GFS资料的均方根误差(Root Mean Square Error,RMSE)呈明显的随高度增加而增大趋势,风速、温度的偏差(Bias)也存在随高度增加而增大趋势。对不同高度的AMDAR资料进行质量控制后,AMDAR与GFS资料的RMSE和Bias都有所改进,且AMDAR资料和GFS资料的差值(Observation Minus Background,OMB)更加符合高斯分布。同化质量控制后的AMDAR资料对风、温度和位势高度分析场有一定的改进作用,并且改进可以影响到12 h甚至24 h预报场。同化质量控制后的AMDAR资料能一定程度上提高降水预报技巧,其中中等量级降水预报改进效果明显。
基金National Key Research and Development Program of China (2021YFC3000802)National Natural Science Foundation of China (41875059)The Open Research Program of the State Key Laboratory of Severe Weather (2021LASW-A04)。
文摘This study examines the spatio-temporal characteristics of heavy precipitation forecasts in eastern China from the European Centre for Medium-Range Weather Forecasts(ECMWF) using the time-domain version of the Method for Object-based Diagnostic Evaluation(MODE-TD). A total of 23 heavy rainfall cases occurring between 2018 and 2021 are selected for analysis. Using Typhoon “Rumbia” as a case study, the paper illustrates how the MODE-TD method assesses the overall simulation capability of models for the life history of precipitation systems. The results of multiple tests with different parameter configurations reveal that the model underestimates the number of objects’ forecasted precipitation tracks, particularly at smaller radii. Additionally, the analysis based on centroid offset and area ratio tests for different classified precipitation objects indicates that the model performs better in predicting large-area, fast-moving, and longlifespan precipitation objects. Conversely, it tends to have less accurate predictions for small-area, slow-moving, and shortlifespan precipitation objects. In terms of temporal characteristics, the model overestimates the forecasted movement speed for precipitation objects with small-area, slow movement, or both long and short lifespans while underestimating it for precipitation with fast movement. In terms of temporal characteristics, the model tends to overestimate the forecasted movement speed for precipitation objects with small-area, slow movement, or both long and short lifespans while underestimating it for precipitation with fast movement. Overall, the model provides more accurate predictions for the duration and dissipation of precipitation objects with large-area or long-lifespan(such as typhoon precipitation) while having large prediction errors for precipitation objects with small-area or short-lifespan. Furthermore, the model’s simulation results regarding the generation of precipitation objects show that it performs relatively well in simulating the generation of large-area and fast-moving precipitation objects. However, there are significant differences in the forecasted generation of small-area and slow-moving precipitation objects after 9 hours.
文摘对流尺度集合预报(Convection-allowingEnsemblePrediction,CAEP)是提高强对流天气预报能力的重要手段,构造合理的初始扰动是CAEP的关键问题。本文开展基于观测扰动初值法(Perturbed-observation,PO)的CAEP在内蒙古地区的试验,并以动力降尺度(Downscaling,DOWN)方法作为对比,分析PO方法在内蒙古地区CAEP的预报效果,以期为内蒙古地区CAEP的构建提供技术参考。结果表明:(1)PO方法构造的初始扰动能引入内蒙古地区观测资料从而减少背景场的不确定性,且扰动具有充分的增长能力。(2)与DOWN方法相比,PO方法可以显著减少CAEP的短时预报误差,高空和地面要素的RMSE分别减小4%~43%和3%~9%,集合离散度略有减少。高空要素的CRPS评分最大可减少约53%,地面要素的CRPS评分平均减少6%,整体提高了对流尺度集合预报质量。(3)PO方法能够提高短时降水的预报能力,0.1mm、4 mm和13 mm 3个量级的TS评分分别提升了0.015、0.003和0.0015。且降水个例表明,PO方法对降水的落区和量级预报更准确。
文摘云贵—华南准静止锋使其以北地区成为研究冬季雨雪过渡区内不同降水相态的理想平台。通过对2018年1月25—27日南方凝冻天气过程中天气学和云微物理参数的分析,定性探讨了次冻结层的温度与冰核活化温度对不同降水相态形成的影响,进而利用耦合BTC降水相态诊断方案(简称“BTC方案”)的WRF(Weather Research and Forecasting)模式,对本次凝冻天气的降水相态、冻雨发生区域与冻雨量进行数值模拟。结果表明:横贯云贵高原和南岭地区的准静止锋导致的锋前“冷—暖—冷”的温度垂直结构有利于多相态降水的形成。耦合BTC方案的WRF模式可模拟出不同降水相态落区的空间分布,其模拟冻雨落区时空分布与观测基本一致,但冰粒的空报率非常高。分析WRF模式模拟的多相态降水时温度、相对湿度和水成物的垂直分布特征,云内水成物初始相态为液态,在高空逆温层存在的前提下,次冻结层中冰核活化温度是区分冻雨和冰粒的临界指标且具有明确的物理机制。利用次冻结层中的冰核活化温度来代替BTC方案中有关冻雨和冰粒的判据后,冻雨落区预报准确率较BTC方案提高了13%,表明直接利用次冻结层的冰核活化温度判断冻雨可行。
文摘基于准对称混合滑动训练期方法,对近两年来中国气象局陆面同化分析系统(CMA Land Data Assimilation System,CLDAS)输出的日最高气温、日最低气温网格实况分析产品进行订正,以期提高该产品在重庆地区的适用性。结果表明:订正前,2021年CLDAS日最高气温产品的平均误差为0.63℃,平均绝对误差为1.14℃,订正后平均误差减小至-0.03℃,平均绝对误差减小至0.64℃,误差小于或等于1℃的准确率由约64%提高到约90%,明显改善了该产品在重庆西部和东南部地区的适用性;订正前,2021年CLDAS日最低气温的平均误差为-0.22℃,平均绝对误差为0.75℃,订正后平均误差减小至-0.03℃,平均绝对误差减小至0.55℃,误差小于或等于1℃的准确率由约91%提高到约93%,改善了该产品在重庆中部地区的适用性。
