Laurentia crustal motion observed using TOPEX/POSEIDON radar altimetry over land   总被引：1，自引：0，他引：1  

Hyongki Lee  C.K. Shum  Yuchan Yi  Alexander Braun  Chung-Yen Kuo 《Journal of Geodynamics》2008,46(3-5):182

A new method to estimate the vertical crustal motion from satellite altimetry over land was developed. The method was tested around Hudson Bay, where the observed vertical motion is largely caused by the incomplete glacial isostatic adjustment (GIA) as a result of the Laurentide ice sheet deglaciation since the last glacial maximum (LGM). Decadal (1992–2003) TOPEX/POSEIDON radar altimetry data over land surfaces were used. The results presented here are improved compared to a previous study (Lee, H., Shum, C.K., Kuo, C.Y., Yi, Y., Braun, A., 2008. Application of TOPEX altimetry for solid Earth deformation studies. Terr. Atmos. Ocean. Sci. 19, 37–46. doi:10.3319/TAO.2008.19.1-2.37(SA).) which estimated vertical motion only over relatively flat land surfaces (standard deviation of the height variation <40 cm). In this study, we extended the concept of traditional 1-Hz (one-per-frame) radar altimeter ocean stackfiles to build 10-Hz (10-per-frame) land stackfiles over Hudson Bay land regions, and succeeded in obtaining vertical motion estimates over much rougher surfaces (standard deviation of the height variation <2 m). 90-m C-band Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) is used as a reference surface to select an optimal waveform retracker, to correct surface gradient errors, and to calculate land surface anomalies. Here, we developed an alternative retracker, called the modified threshold retracker, resulting in decadal vertical motion time series over a 1500 km by 1000 km region covering northern Ontario, northeastern Manitoba, and the Great Lakes region which is at the margin of the former Laurentide ice sheet. The average of the estimated uncertainties for the vertical motion is 2.9 mm/year which is comparable to 2.1 mm/year of recent GPS solutions. The estimated vertical motion is compared with other geodetic observations from GPS, tide gauge/altimetry, GRACE, and several GIA models. The data agree best with the laterally varying 3D GIA model, RF3S20 (β = 0.4) whereas the combination of land altimetry solution with other measurements match best with the models RF3S20 (β = 0.0) or RF3S20 (β = 0.2) in terms of mean and standard deviation of the differences. It is anticipated that this innovative technique could potentially be used to provide additional constraints for GIA model improvement, and be applied to other geodynamics studies.  相似文献   

用改性粘土去除赤潮生物的优化条件研究   总被引：5，自引：0，他引：5  

李全生  俞志明  张波  张永山  马锡年 《海洋与湖沼》1998,29(3):313-317

自１９９５年５月９日－８月２９日,每周量次采集了青岛城阳区上马镇对虾养殖池的水样并进行生物鉴定。结果表明,７月４日和７月１１日该养殖场的北场３号小池水中浮游植物总量已达到赤潮密度,其优势藻种分别为三角褐指藻（Ｐｈａｅｏｄａｃｔｙｌｕｍ ｔｒｉｃｏｎｕｔｕｍ）、裸甲藻（Ｇｙｍｎｉｏｄｉｎｉｕｍ ｓｐ．）（７月４日）和三角褐指藻（Ｐｈａｅｏｄａｃｔｙｌｕｍ ｔｒｉｃｏｎｕｔｕｍ）、新月菱形藻（Ｎｉｔｚ  相似文献   

Time‐phase amplitude spectra based on a modified short‐time Fourier transform          下载免费PDF全文

Gulan Zhang 《Geophysical Prospecting》2018,66(1):34-46

  相似文献   

基于改进BP算法的Elman网络在软基沉降预测中的应用   总被引：2，自引：2，他引：0  

陈述存  高正夏 《工程地质学报》2006,14(3):394-397

E lm an网络具有动态特性好,逼近速度快,精度高等特点,本文结合软基沉降的基本特征,建立了E lm an网络软基沉降预测模型。考虑到经典BP算法的缺陷,采用改进BP算法对网络进行训练学习。实例分析表明,本文所建立的E lm an网络模型具有一定的可靠性和实用性。  相似文献   

柳州新一代天气雷达通风系统的改进措施     

罗廷斌 《气象科技》2008,36(1):127-128

通过对1994年8月4日与2004年9月16日若尔盖湿地TM影像1～5波段和7波段数据以及归一化植被指数(INDVI)、归一化水指数(INDWI)、归一化水分指数(INDMI)和改进的归一化水指数(IMNDWI)的分析,选择通道7、4、3合成假彩色图作为若尔盖湿地的目视解译图,确定了湿地的TM影像标志.分析结果表明,第7波段能较好地将沙地与其它地物区分,改进的归一化水指数与归一化植被指数之差是非常有效的水体提取因子.还制定了若尔盖湿地主要地物的自动判识流程.判识结果与目视解译结果非常吻合,1994年比1984年湖泊面积,沼泽湿地面积明显减小,而沙化地面积扩大.  相似文献   

利用GPS时间传递数据修正接收机天线坐标     

郑曼黎  罗定昌 《时间频率学报》1994,(Z1)

在采用ＧＰＳ进行共视时问比对过程中，当两站位置相隔不大长（小于１０００ｋｍ）时，由于卫星轨道误差、电离层和对流层延迟修正的误差可减少至只有几纳秒，可以主为接收天线位置的误差是其主要误差来源．利用ＧＰＳ本身的时间比对数据，不必增加别的数据来源和设备，采用相对定位的方法可提高定位精度，从而提高时间比对的精度．本文利用日本（ＣＲＬ）和北京天文台（ＢＡＯ）之间五天的共视时间比对数据，对（ＢＡＯ）的天线坐标进行修正．在水平方向和高程方向的修正偏差分别为２．９ｍ和５．６ｍ．如果试验数据足够，修正６４效果会更好．  相似文献   

基于集合经验模态分解的土壤重金属Cd定量反演     

郭云开  曹骁  谢晓峰  张思爱  谢琼 《测绘通报》2022,(1):44-49

针对高光谱定量反演土壤重金属含量的模型精度不足的问题,本文从时频空间的角度引入时频分析法——集合经验模态分解（EEMD）。采用EEMD法分解土壤高光谱,获得不同频率的本征模态（IMF）分量,通过分析IMF分量与重金属含量的相关性,提取特征光谱,构建EEMD-SVM定量反演模型。研究结果表明,通过EEMD法分解土壤光谱,可有效地提取土壤光谱中的微弱信息;构建EEMD-SVM模型可较好地反演土壤重金属Cd含量,模型的决定系数R²为0.920 3,明显高于基于一阶微分处理光谱数据后构建的SVM模型的R²（0.786 6）。即说明在土壤重金属定量反演领域,EEMD可作为一种新的光谱处理方法。  相似文献   

Removal of Heavy Metals from Synthetic Mixture as well as Pharmaceutical Sample Via Cation Exchange Resin Modified with Rhodamine B: Its Thermodynamic and Kinetic Studies     

Syed A. Nabi  Mohammad Shahadat  Abid H. Shalla  Amjad M. T. Khan 《洁净——土壤、空气、水》2011,39(12):1120-1128

A new sorbent was prepared by loading rhodamine B on Amberlite IR‐120. Various physico‐chemical parameters such as effects of adsorbate concentration, contact time, pH, and temperature on the sorption of the dye have been studied. Thermodynamic parameters (ΔH° and ΔS°) were also evaluated for the sorption of dye. Kinetic studies revealed that the sorption of the dye was best fit for pseudo‐second‐order kinetic. The metal ion uptake in different solvent systems has been explored through column studies. On the basis of distribution coefficient (K_d), some heavy metal ions of analytical interest from binary mixtures have been separated. The limit of detection (LOD) for the Ni²⁺ and Fe³⁺ metal ions was 0.81 and 0.60 µg L^?1, and the limit of quantification (LOQ) was found to be 2.72 and 2.0 µg L^?1. This sorbent has also been successfully applied in the analysis of multivitamin formulation. The applicability of the modified resin in the separation of heavy metals constituting real and synthetic samples has been explored.  相似文献   

三维复杂层状介质中多震相走时联合反演成像   总被引：8，自引：5，他引：3       下载免费PDF全文

白超英  黄国娇  李忠生 《地球物理学报》2011,54(1):182-192

采用新近提出的改进型不规则最短路径多次波射线追踪正演技术,结合共轭梯度法求解带约束的阻尼最小二乘最优化反演问题,讨论了三维复杂层状模型中利用多震相走时资料进行联合反演成像的技术方法.考虑到不同震相种类走时的拾取误差不同,反演算法中引入了不同震相种类数据的权系数;另外,考虑到同时反演速度模型和反射界面起伏中不同参数变化对...  相似文献   

Numerical analysis of an embankment on soft soils considering large displacements     

Paulo J. Venda Oliveira  Luís J.L. Lemos 《Computers and Geotechnics》2011

The behaviour of an embankment built on a Portuguese soft soil is analysed considering the material and geometric non-linearity associated with a coupled soil–water formulation. The numerical predictions are compared with the field data in terms of settlements, horizontal displacements and excess pore water pressures. The repercussions of including the large displacements formulation are also studied. It is found that the analysis considering large displacements results in a decrease in settlements and an increase in the rate of excess pore pressure dissipation, both of which are related to the reduction of the thickness of a deformable layer.  相似文献