热带气旋“Malakas”与中纬度系统的相互作用及其结构变化     

刘凡  陈华 《气象科学》2019,39(5):666-674

本文利用中尺度数值模式WRF和LAGRANTO轨迹模式对2010年变性台风"Malakas"进行数值模拟和轨迹分析,分析了Malakas在变性过程中与中纬度系统的相互作用,以及在相互作用过程中Malakas的结构变化特征。结果表明:Malakas变性过程经历了三个阶段:(1)高层扰动加强期,高层的正位涡产生的气旋性环流使低层Malakas中心北部的斜压带西侧产生负的温度平流,表现为冷空气的入侵;(2)Malakas和中纬度系统相互作用时期,台风北上导致斜压带出现,深对流的爆发使低层暖湿气流沿着斜压带上升,快速上升气流中的潜热释放导致低PV空气向对流层上部净输送,在其北部高层重新构建出一个脊;(3)Malakas变性成温带气旋,残存的台风内核与斜压带逐渐合并,负的位涡平流带着非绝热外出流驱动了下游最初脊的构建,加速并且固定了中纬度急流,并整体放大了上层Rossby波模式。  相似文献   

中国地区集合预报产品自适应递减平均偏差订正法的改进研究     

肖瑶  史一丛  王耸  王新伟 《气象与环境学报》2019,(2):9-14

基于中国地区T213集合预报产品2 m温度预报数据,采用卡尔曼滤波类型的自适应递减平均法进行偏差订正处理,原方案在剧烈降温天气订正效果表现不理想。通过对递减平均参数w的重新构建得到改进的订正方案w(i,p)(i为站点信息,p为天气过程信息),在此基础上进一步优化对历史信息的有效提取,得到改进的方案w(i,p)相似法和w(i,p)统计法,并进行效果检验。结果表明:改进为包含空间和天气过程信息的函数w(i,p)后方案的订正效果得到不同程度的提高,其中24 h剧烈降温预报各成员预报均方根误差平均减小了0. 15℃;而进一步改进的w(i,p)统计法在当前几种剧烈降温预报中订正效果最优,其集合平均偏差与w(i,p)方案相比减小2. 54℃。  相似文献   

基于数值预报模式的乡镇温度预报方法研究     

吴春英  刘多文  钟博  蒋婷婷  于蕙箐  陈佳美  高燕 《气象与环境学报》2019,(1):108-112

利用2015年8月至2017年7月长兴岛站和交流岛站日最高气温、日最低气温实况资料,对ECMWF细网格2 m温度预报值和日本FSFE02(24 h地面形势场预报)、FSFE03(36 h地面形势场预报)进行了检验。结果表明:根据历史回归统计检验,ECMWF细网格模式24 h的2 m最高气温、最低气温预报效果显著,通过了0. 05信度显著性检验。对各月做相关分析,相关性均较好。利用前一日ECMWF细网格2 m温度预报值与长兴岛站实况差值,根据统计的ECMWF细网格2 m温度预报订正值,做出长兴岛站未来24 h的气温预报。交流岛站温度预报是在长兴岛站温度预报的基础上订正做出,经统计分析,交流岛站和长兴岛站的气温差值与地面形势场和风场有较好的对应关系,根据不同类型的地面形势场和风场订正值,做出交流岛站的温度预报。应用Matlab计算机语言的开发功能,提取ECMWF细网格2 m温度预报的最高、最低气温值,并录入当日长兴岛站和交流岛站最高、最低气温实况值,自动预报各站未来24 h最高气温、最低气温。创建可视化预报工作界面,实现乡镇温度预报自动化。  相似文献   

一次沿海局地特大暴雨的集合敏感性分析     

陈伟斌  翟舒楠  韩慎友  陈见 《气象研究与应用》2019,40(1):11-15

利用常规观测资料和EC集合预报资料,基于集合敏感性方法 ,首先分析了2018年10月21日广西沿海局地特大暴雨过程的降水影响天气系统及关键区,并进一步分析了集合预报效果,得到不同层次气压场及风场的降水敏感特征以及集合预报降水预报偏差的可能主要原因,所得结论可供预报参考。  相似文献   

基于卡尔曼滤波的中国区域气温和降水的多模式集成预报          下载免费PDF全文

智协飞  黄闻 《大气科学学报》2019,42(2):197-206

利用TIGGE资料集下欧洲中期天气预报中心(ECMWF)、日本气象厅(JMA)、美国国家环境预报中心(NCEP)、中国气象局(CMA)和英国气象局(UKMO)5个模式预报的结果,对基于卡尔曼滤波的气温和降水的多模式集成预报进行研究。结果表明,卡尔曼滤波方法的预报效果优于消除偏差集合平均(BREM)和单模式的预报,但是对于地面气温和降水,其预报效果也存在一定的差异。在中国区域2 m气温的预报中,卡尔曼滤波的预报结果最优。而对于24 h累积降水预报,尽管卡尔曼滤波在所有量级下的TS评分均优于BREM,但随着预报时效增加,其在大雨及以上量级的TS评分跟最佳单模式UKMO预报相当,改进效果不明显。卡尔曼滤波在地面气温和24 h累积降水每个预报时效下的均方根误差均最优,预报效果更佳且稳定。  相似文献   

广西城镇天气预报质量分析评估     

陆小玉  李佳颖  陈伟斌 《气象研究与应用》2019,40(1):99-103

根据全国城镇天气预报产品质量评估报告,从预报准确率和预报技巧评分上对2013-2017年广西城镇天气预报质量进行分析评估。结果表明:广西城镇天气预报24-72h最低温度预报准确率逐年提高,24-72h最高温度预报准确率稳步提升,24-72h晴雨预报和一般性降水预报准确率明显提升,24-72h暴雨和暴雨以上预报准确率保持稳定。24h晴雨、最低温度预报技巧评分较高,24h最高温度、一般性降水预报技巧评分波动较大,暴雨以上预报技巧评分较低。  相似文献   

云凝结核浓度对南京地区一次冰雹云过程影响的数值研究          下载免费PDF全文

刘晓莉  朱煜  孟翠丽  屈家安 《大气科学学报》2019,42(6):936-943

采用WRF模式与包含了云凝结核(Cloud Condensation Nuclei,CCN)浓度和霰雹密度预报的NSSL(National Severe Storm Laboratory,国家强风暴实验室)微物理方案,模拟不同CCN初始浓度条件下南京地区的一次冰雹云过程,分析不同CCN初始浓度影响下冰雹云过程的宏微观演变特征,以及对流发展不同阶段的水凝物粒子及流场、温度场的垂直分布特征。研究发现:1)较大的CCN初始浓度虽然抑制了前期对流降水,但对后期对流降水的产生有促进作用;2)CCN初始浓度的增加使得模拟雷达回波的强回波区域(大于40 dBz)缩小,中等强度区域(小于40 dBz)扩张。3)CCN初始浓度增大不利于对流发展初期云雨自动转化过程的发生,但是促进了冰晶与雪的产生,使得冰雹含量峰值出现的时间推迟。4)CCN浓度增大抑制了雨水产生,间接使得霰粒子更倾向于干增长,平均密度更小;5)较大的CCN浓度促使冰雹云单体的发展时间增长。  相似文献   

A Numerical Investigation on Microphysical Properties of Clouds and Precipitation over the Tibetan Plateau in Summer 2014     

Jie TANG  Xueliang GUO  Yi CHANG 《Journal of Meteorological Research》2019,(3):463-477

In order to improve our understanding of microphysical properties of clouds and precipitation over the Tibetan Plateau (TP), six cloud and precipitation processes with different intensities during the Third Tibetan Plateau Atmospheric Science Experiment (TIPEX-Ⅲ) from 3 July to 25 July 2014 in Naqu region of the TP are investigated by using the high-resolution mesoscale Weather Research and Forecasting (WRF) model. The results show unique properties of summertime clouds and precipitation processes over the TP. The initiation process of clouds is closely associated with strong solar radiative heating in the daytime, and summertime clouds and precipitation show an obvious diurnal variation. Generally, convective clouds would transform into stratiform clouds with an obvious bright band and often produce strong rainfall in midnight. The maximum cloud top can reach more than 15 km above sea level and the velocity of updraft ranges from 10 to 40 m s-1. The simulations show high amount of supercooled water content primarily located between 0 and -20℃ layer in all the six cases. Ice crystals mainly form above the level of -20℃ and even appear above the level of -40℃ within strong convective clouds. Rainwater mostly appears below the melting layer, indicating that its formation mainly depends on the melting process of precipitable ice particles. Snow and graupel particles have the characteristics of high content and deep vertical distribution, showing that the ice phase process is very active in the development of clouds and precipitation. The conversion and formation of hydrometeors and precipitation over the plateau exhibit obvious characteristics. Surface precipitation is mainly formed by the melting of graupel particles. Although the warm cloud microphysical process has less direct contribution to the formation of surface precipitation, it is important for the formation of supercooled raindrops, which are essential for the formation of graupel embryos through heterogeneous freezing process. The growth of graupel particles mainly relies on the riming process with supercooled cloud water and aggregation of snow particles.  相似文献   

The Relationship between Deterministic and Ensemble Mean Forecast Errors Revealed by Global and Local Attractor Radii     

Jie FENG  Jianping LI  Jing ZHANG  Deqiang LIU  Ruiqiang DING 《大气科学进展》2019,36(3):271-278

It has been demonstrated that ensemble mean forecasts, in the context of the sample mean, have higher forecasting skill than deterministic(or single) forecasts. However, few studies have focused on quantifying the relationship between their forecast errors, especially in individual prediction cases. Clarification of the characteristics of deterministic and ensemble mean forecasts from the perspective of attractors of dynamical systems has also rarely been involved. In this paper, two attractor statistics—namely, the global and local attractor radii(GAR and LAR, respectively)—are applied to reveal the relationship between deterministic and ensemble mean forecast errors. The practical forecast experiments are implemented in a perfect model scenario with the Lorenz96 model as the numerical results for verification. The sample mean errors of deterministic and ensemble mean forecasts can be expressed by GAR and LAR, respectively, and their ratio is found to approach2~(1/2) with lead time. Meanwhile, the LAR can provide the expected ratio of the ensemble mean and deterministic forecast errors in individual cases.  相似文献   

Sub-seasonal to Seasonal Hindcasts of Stratospheric Sudden Warming by BCC_CSM1.1(m):A Comparison with ECMWF     

Jian RAO  Rongcai REN  Haishan CHEN  Xiangwen LIU  Yueyue YU  Yang YANG 《大气科学进展》2019,36(5):479-494

This study focuses on model predictive skill with respect to stratospheric sudden warming(SSW) events by comparing the hindcast results of BCC_CSM1.1(m) with those of the ECMWF's model under the sub-seasonal to seasonal prediction project of the World Weather Research Program and World Climate Research Program. When the hindcasts are initiated less than two weeks before SSW onset, BCC_CSM and ECMWF show comparable predictive skill in terms of the temporal evolution of the stratospheric circumpolar westerlies and polar temperature up to 30 days after SSW onset. However, with earlier hindcast initialization, the predictive skill of BCC_CSM gradually decreases, and the reproduced maximum circulation anomalies in the hindcasts initiated four weeks before SSW onset replicate only 10% of the circulation anomaly intensities in observations. The earliest successful prediction of the breakdown of the stratospheric polar vortex accompanying SSW onset for BCC_CSM(ECMWF) is the hindcast initiated two(three) weeks earlier. The predictive skills of both models during SSW winters are always higher than that during non-SSW winters, in relation to the successfully captured tropospheric precursors and the associated upward propagation of planetary waves by the model initializations. To narrow the gap in SSW predictive skill between BCC_CSM and ECMWF, ensemble forecasts and error corrections are performed with BCC_CSM. The SSW predictive skill in the ensemble hindcasts and the error corrections are improved compared with the previous control forecasts.  相似文献