Evaluation of reanalysis surface wind products with quality-assured buoy wind measurements along the north coast of the South China Sea     

Jing Cha  Xinyu Lin  Xiaogang Guo  Xiaofang Wan  Dawei You 《海洋学报(英文版)》2021,40(3):58-69

Three archived reanalysis wind vectors at 10 m height in the wind speed range of 2–15 m/s, namely, the second version of the National Centres for Environmental Prediction(NCEP) Climate Forecast System Reanalysis(CFSv2), European Centre for Medium-Range Weather Forecasting Interim Reanalysis(ERA-I) and NCEPDepartment of Energy(DOE) Reanalysis 2(NCEP-2) products, are evaluated by a comparison with the winds measured by moored buoys in coastal regions of the South China Sea(SCS). The buoy data are first quality controlled by extensive techniques that help eliminate degraded measurements. The evaluation results reveal that the CFSv2 wind vectors are most consistent with the buoy winds(with average biases of 0.01 m/s and 1.76°). The ERA-I winds significantly underestimate the buoy wind speed(with an average bias of –1.57 m/s), while the statistical errors in the NCEP-2 wind direction have the largest magnitude. The diagnosis of the reanalysis wind errors shows the residuals of all three reanalysis wind speeds(reanalysis-buoy) decrease with increasing buoy wind speed, suggesting a narrower wind speed range than that of the observations. Moreover, wind direction errors are examined to depend on the magnitude of the wind speed and the wind speed biases. In general, the evaluation of three reanalysis wind products demonstrates that CFSv2 wind vectors are the closest to the winds along the north coast of the SCS and are sufficiently accurate to be used in numerical models.  相似文献   

孟加拉湾晚第四纪浮游有孔虫及其古海洋学意义   总被引：7，自引：1，他引：6  

丁旋  方念乔 《现代地质》1999,13(1):37-42

对北印度洋孟加拉深海扇远源区水深约３８００ｍ的ＭＤ７７１９０岩心进行了有孔虫定量统计,ＣａＣＯ３质量分数分析和敏纳圆幅虫壳体氧、碳同位素分析,结果表明,该区近１３０ｋａ来的浮游有孔虫组合面貌、表层海水古温度、ＣａＣＯ３质量分数变化的总体趋势与各大洋资料可以对比。ＣａＣＯ３质量分数曲线表现为间冰期升高而冰期降低,反映了研究区陆源碎屑物质对ＣａＣＯ３浓度具有明显的稀释效应。溶解度曲线也表现出相同的变化趋势,同样与陆源物质输入量的变化有关。研究区氧同位素３期各种沉积特征与北印度洋区的季风活动有关,表现出明显的高频气候旋回变化特点。  相似文献   

新疆萨勒布尔-萨吾尔山地区乌吐布拉克组地层归属问题探讨   总被引：2，自引：0，他引：2  

查仁荣  汪立今 《地质与勘探》1999,35(1):23-25

应用元素丰度、点异常概率和Q型聚类分析对乌吐布拉克组的归属问题进行研究,认为乌吐布拉克组划归为上志留统克克雄库都克组第五段比较合适。  相似文献   

Dynamic response simulation of a heavy cargo suspended by a floating crane based on multibody system dynamics     

Ju-Hwan Cha  Myung-Il Roh  Kyu-Yeul Lee 《Ocean Engineering》2010,37(14-15):1273-1291

In this paper, the dynamic response simulation of heavy cargo suspended by a floating crane is performed. The dynamic equations of the motions of the floating crane and the heavy cargo must be considered by the coupled equations because the floating crane and the heavy cargo are connected by wire ropes and provide force and a moment for each other. Hence, the dynamic equations of motion are set up for considering the 6-degrees-of-freedom floating crane and the 6-degrees-of-freedom cargo based on multibody system dynamics. The nonlinear terms in the equations of motion are considered. In addition, the nonlinear hydrostatic force, the linear hydrodynamic force, the wire rope force, and the mooring force are considered as the external forces. Finally, we estimate the motion of the floating crane and the heavy cargo and also calculate the tension of the wire rope between the two.  相似文献   

Erratum to: 2-D Frequency-domain Waveform Inversion of Coupled Acoustic-Elastic Media with an Irregular Interface     

Myung Hoon Kim  Yunseok Choi  Young Ho Cha  Changsoo Shin 《Pure and Applied Geophysics》2011,168(5):961-961

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Characteristics of the changes in tropical cyclones influencing the South Korean region over the recent 10 years (2001–2010)     

Yumi Cha  Ki-Seon Choi  Ki-Ho Chang  Ji-Yeon Lee  Do-Shick Shin 《Natural Hazards》2014,74(3):1729-1741

Through the investigation of tropical cyclone (TC) characteristics related to climate change, this study found that the frequency of TCs occurring over the Western North Pacific has recently decreased slightly, while their average intensity has increased. The number of overall TCs that passed within the vicinity of South Korea has also been reduced, but the number of strong typhoons in the area, those with maximum wind speeds of more than 44 m/s, has significantly increased. These changes are closely related to the following phenomena. (1) The average genesis region of TCs that influence South Korea has moved eastward. Accordingly, the TCs tend to strengthen as they move westward for long distances along the Intertropical Convergence Zone (ITCZ) trade easterlies and the southern boundary of the North Pacific Subtropical High (NPSH). (2) The NPSH and Asia Monsoon trough, which are known to affect TC tracks, have extended to the northwest and southeast. This has caused TCs that travel to higher latitudes and curve back toward the Korean Peninsula to become more frequent. (3) TCs have approached the Korean Peninsula without hitting land. In addition, the sea surface temperature became higher than it was before. These factors have caused TCs to maintain their strength or become stronger than before.  相似文献   

A Periodicity Analysis of the Light Curve of 3C 454.3   总被引：2，自引：0，他引：2  

Huai-Zhen Li  Guang-Zhong Xie  Shu-Bai Zhou  Hong-Tao Liu  Guang-Wei Cha  Li Ma  Li-Sheng Mao National Astronomical Observatories / Yunnan Observatory  Chinese Academy of Sciences  Kunming  Graduate School of Chinese Academy of Sciences  Beijing Yunnan Astronomical Center  Yunnan University  Kunming Physics Department  Yunnan University  Kunming Physics Department  Yunnan Normal College  Kunming 《中国天文和天体物理学报》2006,6(4):421-429

We analyzed the radio light curves of 3C 454.3 at frequencies 22 and 37 GHz taken from the database of Metsahovi Radio Observatory, and found evidence of quasi-periodic activity. The light curves show great activity with very complicated non-sinusoidal variations. Two possible periods, a very weak one of 1.57±0.12 yr and a very strong one of 6.15±0.50 yr were consistently identified by two methods, the Jurkevich method and power spectrum estimation. The period of 6.15±0.50 yr is consistent with results previously reported by Ciaramella et al. and Webb et al. Applying the binary black hole model to the central structure we found black hole masses of 1.53×109M⊙and 1.86×108M⊙, and predicted that the next radio outburst is to take place in 2006 March and April.  相似文献   

The formation and fragmentation of the ring appearing in the collapse of a rotating cloud     

S.-H. Cha †  A. P. Whitworth 《Monthly notices of the Royal Astronomical Society》2003,340(1):91-104

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Spatial distribution of stream sediment pollution by toxic trace elements at Tourtit and Ichoumellal abandoned mining areas (central Morocco)     

Chaïma Ahmedat  Sanaa Dabi  Mohamed Zahraoui  Iz-Eddine El Amrani El Hassani 《Arabian Journal of Geosciences》2018,11(3):55

This study presents a diagnostic of the current state of 114 stream sediment samples by their elemental concentrations (Sb, Cd, Pb, As, Cu, Zn, Ni, Cr, and Hg), collected from Ighardayane upstream on an area of 15 km² located at the SE part of central Morocco where Tourtit and Ichoumellal, two abandoned mining sites of Stibnite, are located. Several approaches were used to model the analysis (i) enrichment factor (EF), (ii) sediment pollution index (IPS), (iii) probable effect concentration-quotients (PEC-Qs), and (iv) potential ecological risk index (PERI). Results show highly contaminated areas around the old mining sites by Sb As, Pb, and Cd. Cadmium and lead show 86.9 and 12.29% (respectively) of trace element pollution according to sediment pollution index. Twenty-eight percent of the sampled area is potentially highly toxic because of the presence of Hg, Pb, and Cd. The very similar distribution of pollution and toxicity of most analyzed trace elements may originate from the same source, which corresponds to mining wastes where we recorded the highest pollution and toxicity degrees. This environmental issue represents the combination of Tourtit and Ichoumellal anthropic sources responsible of Sb, As, Pb, and Cd release and a probable natural source of Hg “that needs a further study,” which contribute in the degradation of an aquatic ecosystem of the same area. Therefore, both ecotoxicological analysis and stream sediment quality management should be carried out to control this aquatic ecosystem toxication.  相似文献   

基于PMCS图像数据的雨滴微物理特征研究          下载免费PDF全文

胡云涛  刘西川  高太长  许平平  江晓华  杨查 《气象与减灾研究》2018,41(4):285-292

基于2015年降水微物理特征测量仪(PMCS)在南京地区获得的3次降水过程的雨滴图像资料,利用图像处理算法得到雨滴形状、尺度、轴比、倾斜角、垂直速度等特征参量,研究了雨滴的微物理特征空间分布规律。结果表明:直径较小的雨滴轮廓呈圆环状,随着粒子直径增加,雨滴轮廓呈现出椭圆形和底部扁平顶部凸起状。PMCS测得的雨滴轴比—直径拟合关系同经验模型相比误差较小,雨滴轴比概率分布呈现高斯分布特征。雨滴倾斜角分布于0°两侧,方差为15.9°,小雨滴倾斜角受湍流影响较大,摆动范围较大。雨滴垂直速度随直径增大而增大,垂直速度拟合曲线同Atlas速度经验模型分布较为一致。  相似文献