排序方式: 共有52条查询结果,搜索用时 125 毫秒
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使用参数化初猜测谱算法提取VV极化Sentinel-1 SAR图像的海浪要素并与ECMWF再分析数据以及浮标数据进行验证对比 总被引:2,自引:1,他引:1
The purpose is to study the accuracy of ocean wave parameters retrieved from C-band VV-polarization Sentinel-1Synthetic Aperture Radar(SAR) images, including both significant wave height(SWH) and mean wave period(MWP), which are both calculated from a SAR-derived wave spectrum. The wind direction from in situ buoys is used and then the wind speed is retrieved by using a new C-band geophysical model function(GMF) model,denoted as C-SARMOD. Continuously, an algorithm parameterized first-guess spectra method(PFSM) is employed to retrieve the SWH and the MWP by using the SAR-derived wind speed. Forty–five VV-polarization Sentinel-1 SAR images are collected, which cover the in situ buoys around US coastal waters. A total of 52 subscenes are selected from those images. The retrieval results are compared with the measurements from in situ buoys. The comparison performs good for a wind retrieval, showing a 1.6 m/s standard deviation(STD) of the wind speed, while a 0.54 m STD of the SWH and a 2.14 s STD of the MWP are exhibited with an acceptable error.Additional 50 images taken in China's seas were also implemented by using the algorithm PFSM, showing a 0.67 m STD of the SWH and a 2.21 s STD of the MWP compared with European Centre for Medium-range Weather Forecasts(ECMWF) reanalysis grids wave data. The results indicate that the algorithm PFSM works for the wave retrieval from VV-polarization Sentinel-1 SAR image through SAR-derived wind speed by using the new GMF C-SARMOD. 相似文献
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【研究目的】 本文以准噶尔盆地乌伦古坳陷至乌伦古北隆起带为研究区,研究石炭纪地层沉积、分布特征,为该区地质结构研究和油气勘查工作提供了依据和参考。【研究方法】 采集大地电磁测深数据,结合以往重磁电震资料,采用二维共轭梯度反演、最优化电性分层等技术获取石炭纪地层、断裂构造展布特征,为火成岩覆盖区研究石炭纪地层提供了有效的方法。【研究结果】 利用大地电磁测深技术结合重磁电震资料开展综合处理分析,获得研究区石炭系厚度图、石炭系埋深图,初步确定了上下石炭统的分界面,查明了石炭纪地层的分布特征,索索泉凹陷、福海坳陷和扎河坝坳陷为3个石炭纪地层沉降中心,具有较好的油气勘查前景。【结论】 在火成岩覆盖区,采用大地电磁测深、重磁电震综合处理解释技术为石炭纪地层研究提供了有效的技术支撑。 相似文献
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目前国内外对目标层埋深仅有几十米(甚至十几米)的超浅层地震勘探经验不多,理论研究也不够深入。本文从城市活断层探测的角度出发,利用地质学、地球物理学及数学等学科中的相关理论和方法,探讨超浅层地震勘探在青岛复杂地质构造背景下取得有效探测结果的前提条件,并对青岛市主要活断层的典型剖面进行重点研究,力求在城市活断层超浅层地震勘探数据采集技术、数据处理等方面有所进展,为青岛及类似地质构造背景的地区开展活动断层超浅层地震探测提供参考。研究表明超浅层地震反射波法可以获取深度仅有十几米的地层反射信号,且大部分反射剖面都可较清楚地揭示出超浅部断层位置和断层特征。 相似文献
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以淮南煤矿区泥河小流域1987、1994、2000、2006、2009、2013、2017年7期多源遥感影像为数据源,结合纹理和光谱特征,利用支持向量机(SVM)对遥感影像进行分类,在此基础上分析了煤炭开采对泥河小流域近30年土地利用和景观格局变化的影响。结果表明:煤炭开采影响下流域的土地利用变化最显著的特征是耕地和建设用地的相互转变及耕地向塌陷水体的转变,30年间塌陷水体和建设用地分别增加了2 281.05、14 741.73 hm2,耕地减少了15 044.67 hm2。采煤驱动下,流域景观格局变化特征体现在以2006年为转折点,前期呈现破碎化、不规则化、异质化和低连通性变化的特征,之后呈现连续化、规则化、均衡化及高连通性变化的特征。建设用地、耕地和塌陷水体经历了不断破碎化到景观逐渐完善的过程;耕地、建设用地和自然水体斑块形状较为复杂;耕地优势性逐渐减弱,最大斑块指数由79.706 0降为38.745 5,塌陷水体和建设用地的优势性增强。 相似文献
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Lina Cai Minrui Zhou Xiaojun Yan Jianqiang Liu Qiyan Ji Yuxiang Chen Juncheng Zuo 《海洋学报(英文版)》2022,41(11):126-138
The impacts of the Hong Kong-Zhuhai-Macao Bridge (HKZMB) on suspended sediment content (SSC) were analysed in the Zhujiang River Estuary based on data from HY-1C, which was launched in September 2018 in China, carrying Coastal Zone Imager (CZI) and Chinese Ocean Color and Temperature Scanner on it. A new SSC inversion model was established based on the relationship between in-situ SSC and the remote sensing reflectance in red and near-infrared bands of CZI image. HY-1C satellite data obtained from October to December 2019 were applied to retrieve SSC in the Zhujiang River Estuary. The results show that SSC around the HKZMB is ranging from 20 mg/L to 95 mg/L. SSC change obviously on two sides of the bridge. During flooding and ebbing period, SSC increases obviously downstream of the bridge. SSC difference between upstream and downstream is ranging from 5 mg/L to 20 mg/L. Currents flowing across the HKZMB, the change trend of SSC in most places upstream and downstream is almost the same that SSC downstream of the bridge is higher than SSC upstream. The tidal currents interact with bridge piers, inducing vortexes downstream, leading the sediment to re-suspend downstream of the bridge piers. Other factors, including seafloor topography and wind, can also contribute to the distribution of SSC in the Zhujiang River Estuary. 相似文献
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ZHANG Guosheng XU Qing GONG Zheng CHENG Yongcun WANG Lei and JI Qiyan 《中国海洋大学学报(英文版)》2014,13(2):191-197
To investigate the annual and interannual variability of ocean surface wind over the South China Sea (SCS), the vector empirical orthogonal function (VEOF) method and the Hilbert-Huang transform (HHT) method were employed to analyze a set of combined satellite scatterometer wind data during the period from December 1992 to October 2009. The merged wind data were generated from European Remote Sensing Satellite (ERS)-1/2 Scatterometer, NASA Scatterometer (NSCAT) and NASA’s Quick Scatterometer (QuikSCAT) wind products. The first VEOF mode corresponds to a winter-summer mode which accounts for 87.3% of the total variance and represents the East Asian monsoon features. The second mode of VEOF corresponds to a spring-autumn oscillation which accounts for 8.3% of the total variance. To analyze the interannual variability, the annual signal was removed from the wind data set and the VEOFs of the residuals were calculated. The temporal mode of the first interannual VEOF is correlated with the Southern Oscillation Index (SOI) with a four-month lag. The second temporal interannual VEOF mode is correlated with the SOI with no time lag. The time series of the two interannual VEOFs were decomposed using the HHT method and the results also show a correlation between the interannual variability and El Niño-Southern Oscillation (ENSO) events. 相似文献
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The effects of sea surface temperature(SST) data assimilation in two regional ocean modeling systems were examined for the Yellow Sea(YS). The SST data from the Operational Sea Surface Temperature and Sea Ice Analysis(OSTIA) were assimilated. The National Marine Environmental Forecasting Center(NMEFC) modeling system uses the ensemble optimal interpolation method for ocean data assimilation and the Kunsan National University(KNU) modeling system uses the ensemble Kalman filter. Without data assimilation, the NMEFC modeling system was better in simulating the subsurface temperature while the KNU modeling system was better in simulating SST. The disparity between both modeling systems might be related to differences in calculating the surface heat flux, horizontal grid spacing, and atmospheric forcing data. The data assimilation reduced the root mean square error(RMSE) of the SST from 1.78°C(1.46°C) to 1.30°C(1.21°C) for the NMEFC(KNU) modeling system when the simulated temperature was compared to Optimum Interpolation Sea Surface Temperature(OISST) SST dataset. A comparison with the buoy SST data indicated a 41%(31%) decrease in the SST error for the NMEFC(KNU) modeling system by the data assimilation. In both data assimilative systems, the RMSE of the temperature was less than 1.5°C in the upper 20 m and approximately 3.1°C in the lower layer in October. In contrast, it was less than 1.0°C throughout the water column in February. This study suggests that assimilations of the observed temperature profiles are necessary in order to correct the lower layer temperature during the stratified season and an ocean modeling system with small grid spacing and optimal data assimilation method is preferable to ensure accurate predictions of the coastal ocean in the YS. 相似文献