共查询到20条相似文献,搜索用时 125 毫秒
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基于中国国家气象中心T213模式、德国气象局业务模式和日本气象厅业务模式2 m高温度预报, 利用神经网络方法中的BP网络建立了我国600多个站的温度集成预报系统, 该预报系统的预报时效为72 h, 间隔为3 h。通过对2004年1—5月的预报结果检验, 表明:集成的温度预报结果明显优于3个模式单独的预报结果, 72 h内预报的平均绝对误差在3 ℃以内, 并且不存在明显的系统误差, 预报达到了一定的精度, 可以为预报员提供定时、定点精细的客观温度预报参考。分区的检验结果表明:不同区域预报误差存在差别, 新疆和西藏误差比较大, 而长江流域和华南地区误差很小, 并且不同区域系统误差的情况也不相同。从总体情况看, 预报误差还存在日变化, 一般来讲, 夜间的预报误差小于白天。 相似文献
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为满足长江上游流域梯级水利枢纽的运行生产对精细化气象服务的需求,设计研发了长江上游流域数值预报产品误差分析与订正系统。该系统实现了长江上游流域内T639、欧洲、日本等数值模式预报产品及实况的实时收集处理和误差统计对比分析,提供了降水和数值预报天气形势场的自动客观订正产品,同时通过图形化界面的预报产品主观订正平台,实现了长江上游降水预报产品的制作输出以及各类误差分析数据的统计查询、对比显示,为综合有效的利用多种预报产品开展流域高质量、精细化的预报业务提供了支撑。该系统已在三峡梯调通信中心投入业务运行,运行情况表明该系统运行稳定、操作方便,具有较好的订正效果,在流域强降水天气过程的预报服务中发挥了重要作用。 相似文献
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临沂中尺度数值预报系统及应用 总被引:5,自引:1,他引:4
介绍了临沂中尺度数值预报系统及预报产品的释用和模式系统应用雷达资料情况,并对2005年6~10月的业务运行结果进行了检验,对小雨和中雨预报效果较好,TS评分较高,对夜间温度预报平均值绝对误差在1.52~2.52℃之间,平均均方根误差在2.01~2.93℃之间。该系统降水预报质量较高,气温预报误差小,准确率高,对定时、定点、定量的精细化预报具有较高的参考价值。应用自主开发的SDAF软件包,对系统的预报产品进行释用,研制了暴雨、空气质量、极端气温、干热风等预报方法。将多普勒雷达回波强度加入模式,改变模式水汽场,明显改进了预报。对径向速度反演降水系统内部风场进入中尺度模式进行了初步试验,得出了一些有益结论。 相似文献
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Construction, observation site and instrumentation are described of an 80-m meteorological observation tower, erected in Vlaardingen, The Netherlands, for studies in connection with air pollution problems along the Nieuwe Waterweg. From measurements made regularly in the period April 1967–April 1968 summaries are given of wind profile parameters and gustiness averages. Case histories are presented of an air pollution episode lasting several days, and of an hourly average wind direction difference of 120 ° over 70 m. 相似文献
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Xander Olsthoorn Peter van der Werff Laurens M. Bouwer Dave Huitema 《Climatic change》2008,91(1-2):103-122
What could happen to the Netherlands if, in 2030, the sea level starts to rise and eventually, after 100 years, a sea level of 5 m above current level would be reached? This question is addressed by studying literature, by interviewing experts in widely differing fields, and by holding an expert workshop on this question. Although most experts believe that geomorphology and current engineering skills would enable the country to largely maintain its territorial integrity, there are reasons to assume that this is not likely to happen. Social processes that precede important political decisions – such as the growth of the belief in the reality of sea level rise and the framing of such decisions in a proper political context (policy window) – evolve slowly. A flood disaster would speed up the decision-making process. The shared opinion of the experts surveyed is that eventually part of the Netherlands would be abandoned. 相似文献
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From the architectural point of view, the vertical distribution of strong gusts over large cities is very important. Although special instrumentation for very strong winds is required, the available recording devices are generally not adequate. Only rather recently have telemetric techniques advanced sufficiently to ensure a practical system for measuring very strong gusts. Records from fast-response anemometers for each minute (sixty measurements per hour) may clarify the physical processes in the atmospheric boundary layer in the lowest 250-m layer over the city of Tokyo. The new system can be considered practical since it was operated from May 1968 to July 1969 under a variety of climatic conditions, especially under strong gusty conditions. 相似文献
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本文基于K理论和北京325m铁塔湍流观测资料直接计算了城市污染条件下的湍流热扩散系数H.KH具有明显的日变化特征,其垂直分布随个例和时间而变化.负KH较高发生频率对应高度在日出后逐渐升高,在中午达到峰值,在日落附近下降,而在夜间大部分时间集中在140 m左右.和传输和清除阶段相比,污染物累积阶段的KH大小和波动程度均较... 相似文献
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针对离散站点资料格点化的业务需求及 Cressman 方法在地形复杂区域客观分析存在的问 题,利用山东及周边省自动气象站观测的 2 m气温和 ECMWF预报的海上 2 m气温,结合山东省中尺度数值预报位温递减率、90 m分辨率 SRTM高程数据,采用统一高度 Cressman 方法对山东省地面2 m气温进行客观分析,生成了逐 1 h、0.01°×0.01°高分辨率的地面 2 m气温格点产品。结果表明,统一高度 Cressman 方法的客观分析格点产品在地形复杂区域的分析更合理,月平均误差基本在±1 ℃以内,鲁中山区地形高度较高区域月平均误差略大于鲁西北、鲁西南、鲁东南和山东半岛等地的平原地区,气温偏低的10、11、12月温度准确率均略低于 5、6、7、8、9 月;2020 年 5—12 月平均误差为-0.0039 ℃,平均绝对误差为 0.1469 ℃,均方根误差为 0.3597 ℃,2 ℃以内准确率为 99.64%,1 ℃以内准确率为 98.24%,各项检验指标均较优。总体上统一高度 Cressman 客观分析格点产品质量接近中国气象局陆面数据同化系统( HRCLDAS )高分辨率格点实况产品。 相似文献
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The impact of the simulated large-scale atmospheric circulation on the regional climate is examined using the Weather Research and Forecasting (WRF) model as a regional climate model. The purpose is to understand the potential need for interior grid nudging for dynamical downscaling of global climate model (GCM) output for air quality applications under a changing climate. In this study we downscale the NCEP-Department of Energy Atmospheric Model Intercomparison Project (AMIP-II) Reanalysis using three continuous 20-year WRF simulations: one simulation without interior grid nudging and two using different interior grid nudging methods. The biases in 2-m temperature and precipitation for the simulation without interior grid nudging are unreasonably large with respect to the North American Regional Reanalysis (NARR) over the eastern half of the contiguous United States (CONUS) during the summer when air quality concerns are most relevant. This study examines how these differences arise from errors in predicting the large-scale atmospheric circulation. It is demonstrated that the Bermuda high, which strongly influences the regional climate for much of the eastern half of the CONUS during the summer, is poorly simulated without interior grid nudging. In particular, two summers when the Bermuda high was west (1993) and east (2003) of its climatological position are chosen to illustrate problems in the large-scale atmospheric circulation anomalies. For both summers, WRF without interior grid nudging fails to simulate the placement of the upper-level anticyclonic (1993) and cyclonic (2003) circulation anomalies. The displacement of the large-scale circulation impacts the lower atmosphere moisture transport and precipitable water, affecting the convective environment and precipitation. Using interior grid nudging improves the large-scale circulation aloft and moisture transport/precipitable water anomalies, thereby improving the simulated 2-m temperature and precipitation. The results demonstrate that constraining the RCM to the large-scale features in the driving fields improves the overall accuracy of the simulated regional climate, and suggest that in the absence of such a constraint, the RCM will likely misrepresent important large-scale shifts in the atmospheric circulation under a future climate. 相似文献
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Multi-model ensemble forecasting of 10-m wind speed over eastern China based on machine learning optimization 下载免费PDF全文
风对人类活动和电力运行有重大影响,准确预报短期风速具有深远的社会和经济意义.基于中国东部100个站点,本研究首先评估了5个业务模式对10米风速的预报能力,日本气象厅JMA模式在减少预报误差方面表现最好.进一步,利用5种数值模式和多种机器学习方法,将动力和统计相结合,对每个站点分别进行了特征工程和机器学习算法优选,建立了10米风速多模式集成预报模型.针对24至96小时预报时长,将该方法的预报性能与基于岭回归的多模式集成和JMA单模式进行比较.结果表明,基于机器学习优选的多模型集成方法可以将JMA模式的预报误差降低39%以上,预报效果的提升在11月最明显.此外,该方法优于基于岭回归的多模式集成方法. 相似文献
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The Beijing 325-m Meteorological Tower (325MT) is used to observe the vertical variation of solar radiation. Results of the experiments indicate that the automatic radiation monitoring system, including a sun tracker and data collection system, works well and all the specifications meet WMO observation standards. The measurement data show that there is a significant radiation decrease from 320m to the surface, where the difference is only about 30Wm^-2 on light air-pollution days, while the maximum reaches about 110Wm^-2 when heavy pollution appears near the ground. The global UV radiation decreases on heavy air-pollution days and under poor visibility conditions, and the difference between 300m and 8m is larger than on clear days. 相似文献