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81.
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南黄海辐射沙洲主要潮沟的变迁 总被引:6,自引:1,他引:6
黄海军 《海洋地质与第四纪地质》2004,24(2):1-8
利用1966年和1977年海图、1995年和2000年合成孔径雷达影像,结合1980年以来的陆地卫星影像和2000年的岸滩实测剖面资料对南黄海辐射沙洲区主要潮沟的位置进行了解译与分析,得出上述4个时期研究区内主要潮沟深泓线位置图。对不同时期潮沟深泓线位置图进行几何校准与叠加,对比潮沟深泓线的迁移。结果表明:潮沟具有往返周期性摆动的特点,短期摆动速度明显快于长期摆动,主沟槽最大变动速度达127m/a,而支沟槽变动速度更大。潮沟摆动与沙洲变化有明显的相关性,但两者间的关系较为复杂。辐射沙洲目前处于破碎、萎缩阶段,除沙洲中心及陆岸岸滩仍有淤积外,大部分沙洲处于侵蚀状况,同时沙洲有整体向陆迁移的趋势。 相似文献
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GPS大气掩星探测技术可以获得全球大气折射率、气压、密度、温度和水汽压等气象参数,该技术基本原理是基于几何光学近似的Abel积分反演.地球扁率、电离层传播时间延迟、大气大尺度水平梯度、多路径传播现象等因素在某些高度范围影响大气反演的精度.本文采用模拟的方法,分析其中地球扁率及电离层对反演结果的影响,并讨论局部圆弧修正及电离层修正的效果.利用CHAMP掩星实测轨道数据和有关电离层和大气经验模式、采用三维射线追踪方法模拟计算几种情形下的GPS掩星观测附加相位数据,对模拟数据进行反演,将反演气象参量剖面与模拟时给定模式剖面进行比较,得到了0~60 km高度范围内的反演误差.误差统计分析结果表明,局部圆弧中心的修正以及电离层修正,对于高精度的GPS掩星反演是非常重要的;电离层修正残差仍是制约30~60 km高度范围内反演精度的重要因素,进一步完善和优化大气掩星反演需要发展新的电离层修正算法. 相似文献
85.
HY-2 A (Haiyang-2 A) satellite was launched on August 16, 2011 and radar altimeter is one of its main payloads. We reprocessed two years of HY-2 A altimeter sensor geophysical dataset records (SGDR) data. This paper presents the main results in terms of reprocessed HY-2 A altimeter data quality: verification of data availability and validity, monitoring several relevant altimeter parameters, and assessment of the HY-2 A altimeter system performances. A cross-calibration analysis of reprocessed HY-2 A altimeter data with Jason-2 was conducted. The reprocessed HY-2 A altimeter data show good quality and have a low level of noise with respect to Jason-2. The same geophysical correction methods were used to calculate the sea surface height (SSH) for the two missions. The mean standard deviations of the crossover differences for HY-2 A and Jason-2 are 5.24 cm and 5.34 cm, respectively. The mean standard deviation of the crossover differences between HY-2 A and Jason-2 is 5.37 cm. These show that HY-2 A can provide SSH measurements at almost the same level of accuracy as Jason-2. The relative SSH bias between HY-2 A and Jason-2 due to the Ultra Stable Oscillator (USO) drift is obviously observed, and it can affect the calculation of mean sea level and should be further studied and corrected. 相似文献
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Optical buffers are critical for optical signal processing in future optical packet-switched networks. In this paper, a theoretical study as well as an experimental demonstration on a new optical buffer with large dynamical delay time is carried out based on cascaded double loop optical buffers (DLOBs). It is found that pulse distortion can be restrained by a negative optical control mode when the optical packet is in the loop. Noise analysis indicates that it is feasible to realise a large variable delay range by cascaded DLOBs. These conclusions are validated by the experiment system with 4-stage cascaded DLOBs. Both the theoretical simulations and the experimental results indicate that a large delay range of 1--9999 times the basic delay unit and a fine granularity of 25 ns can be achieved by the cascaded DLOBs. The performance of the cascaded DLOBs is suitable for the all optical networks. 相似文献
88.
With the global wanning and sea level rising, it is widely recognized that there is an increasing tendency of typhoon occurrence frequency and intensity. The defenses code against typhoon attacks for nuclear power plant should be calibrated because of the increasing threat of typhoon disaster and severe consequences. This paper discusses the probabilistic approach of definitions about "probable maximum typhoon" and "probable maximum storm surge" in nuclear safety regulations of China and has made some design code calibrations by use of a newly proposed Double Layer Nested Multi-objective Probability Model (DLNMPM). 相似文献
89.
Abstract The Blaney-Criddle (BC) temperature-based equation is used in areas where the complete weather data to estimate reference evapotranspiration (ET0) by the Penman-Monteith FAO-56 (PMF-56) standard model is complex. In this study, the BC equation was first tested and calibrated against the ET0 values computed by the PMF-56 method using data from 17 weather stations in arid regions of Iran. Then, geographical information systems (GIS)-based spatially-distributed maps of ET0 were prepared by means of geographic/topographic factors derived from a digital elevation model (DEM) for all months, separately. The results indicate that the original BC equation overestimated PMF-56 ET0 by 4% at the study sites. The BC equation produced closer ET0 estimates to the PMF-56 method after it was calibrated. The error rate of <3% for the spatial modelling approach suggests that the developed ET0 maps are reliable. Editor D. Koutsoyiannis; Associate editor D. Yang Citation Tabari, H., Hosseinzadeh Talaee, P., and Shifteh Some'e, B., 2013. Spatial modelling of reference evapotranspiration using adjusted Blaney-Criddle equation in an arid environment. Hydrological Sciences Journal, 58 (2), 408–420. 相似文献
90.
一些新的稀释装置已用于原子发射光谱法和原子吸收分光光度法中,改变了以往预先配制浓度依次变化的标准系列的习惯做法。Ko(?)cielniak提出的一种非连续稀释方法,所配制溶液的浓度与稀释次数成指数关系。本文采用了这种技术对稀释装置作了改进,只需要一个小锥形瓶,添加或稀释同一个原始溶液便可制备出一系列标准溶液。设备简单、操作方便,用于原子吸收分光光度法测定钾长石中的钠、钾并与常规法对照结果满意。 相似文献