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A rainfall that occurred during 0200–1400 Beijing Standard Time(BST)25 August 2008 shows the rapid development of a convective system,a short life span,and a record rate of 117.5 mm h-1for Xujiahui station since 1872.To study this torrential rainfall process,the partitioning method of Q vector is developed,in which a moist Q vector is first separated into a dry ageostrophic Q vector(DQ)and a diabatic-heating component.The dry ageostrophic Q vector is further partitioned along isothermal lines in the natural... 相似文献
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中法海洋卫星(Chinese-French Oceanography Satellite,CFOSAT)搭载的微波散射计(CFOSAT Scatterometer,CSCAT)采用 Ku 波段扇形波束旋转扫描体制,具有观测几何信息丰富、观测样本数多的特点,是一种新型的海面风场遥感仪器。CSCAT 的原始空间分辨率可达10 km×12-5 km,是目前空间分辨率最高的微波散射计,为开发高质量的近海岸高分辨率海面风场产品提供了可能性。首先,回顾了 CSCAT 近海岸风场遥感的原理,并利用辅助数据验证了这种新的科学产品的有效性。 然后,利用 CSCAT 近海岸风场开展了台风灾害监测研究。与标准 25 km 分辨率的产品相比, CSCAT 近海岸风场可以更细致地描绘台风结构,能够为气象和海洋防灾减灾提供更精准的信息支持与决策服务。 相似文献
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针对北斗3种不同类型卫星轨道在静态及动态环境下相位历元差与卫星高度角和采样率之间的关系,构建适用于不同轨道卫星GF组合自适应阈值模型的BDS周跳探测方法。结果表明,本文方法可适用于北斗各类轨道卫星高度角较低及电离层活跃等不利观测环境下的周跳探测,尽可能地避免各采样率情况下的错判及漏判现象,显著提高采样率较低及多路径误差较大时的探测准确率。 相似文献
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基于马尔科夫随机场(Markov Random Field,MRF)模型下的遥感图像变化检测因固定组合能量函数导致的边缘分割模糊问题,提出了一种改进的变权重MRF遥感图像变化检测方法。该方法首先通过模糊C均值(Fuzzy C-means,FCM)算法对差值图像进行聚类分割,并依此分割结果作为变权重MRF的初始分割条件进行最终的分割;最后对分割结果进行掩膜处理,得到最终的变化检测结果。采用真实遥感影像进行对比实验,结果表明所提方法变化检测精度更高,边缘检测更加平滑,区域一致性更好。 相似文献
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Ping ZHAO Yueqing LI Xueliang GUO Xiangde XU Yimin LIU Shihao TANG Wenming XIAO Chunxiang SHI Yaoming MA Xing YU Huizhi LIU La JIA Yun CHEN Yanju LIU Jian LI Dabiao LUO Yunchang CAO Xiangdong ZHENG Junming CHEN An XIAO Fang YUAN Donghui CHEN Yang PANG Zhiqun HU Shengjun ZHANG Lixin DONG Juyang HU Shuai HAN Xiuji ZHOU 《Journal of Meteorological Research》2019,(3):375-399
The Tibetan Plateau(TP) is a key area affecting forecasts of weather and climate in China and occurrences of extreme weather and climate events over the world. The China Meteorological Administration, the National Natural Science Foundation of China, and the Chinese Academy of Sciences jointly initiated the Third Tibetan Plateau Atmospheric Science Experiment(TIPEX-Ⅲ) in 2013, with an 8–10-yr implementation plan. Since its preliminary field measurements conducted in 2013, routine automatic sounding systems have been deployed at Shiquanhe, Gaize, and Shenzha stations in western TP, where no routine sounding observations were available previously. The observational networks for soil temperature and soil moisture in the central and western TP have also been established. Meanwhile, the plateau-scale and regional-scale boundary layer observations, cloud–precipitation microphysical observations with multiple radars and aircraft campaigns, and tropospheric–stratospheric air composition observations at multiple sites, were performed. The results so far show that the turbulent heat exchange coefficient and sensible heat flux are remarkably lower than the earlier estimations at grassland, meadow, and bare soil surfaces of the central and western TP. Climatologically, cumulus clouds over the main body of the TP might develop locally instead of originating from the cumulus clouds that propagate northward from South Asia. The TIPEX-Ⅲ observations up to now also reveal diurnal variations, macro-and microphysical characteristics, and water-phase transition mechanisms, of cumulus clouds at Naqu station. Moreover, TIPEX-Ⅲ related studies have proposed a maintenance mechanism responsible for the Asian "atmospheric water tower" and demonstrated the effects of the TP heating anomalies on African, Asian, and North American climates. Additionally, numerical modeling studies show that the Γ distribution of raindrop size is more suitable for depicting the TP raindrop characteristics compared to the M–P distribution, the overestimation of sensible heat flux can be reduced via modifying the heat transfer parameterization over the TP, and considering climatic signals in some key areas of the TP can improve the skill for rainfall forecast in the central and eastern parts of China. Furthermore, the TIPEX-Ⅲ has been promoting the technology in processing surface observations, soundings, and radar observations, improving the quality of satellite retrieved soil moisture and atmospheric water vapor content products as well as high-resolution gauge–radar–satellite merged rainfall products, and facilitating the meteorological monitoring, forecasting, and data sharing operations. 相似文献