共查询到20条相似文献,搜索用时 15 毫秒
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分别采用非差无电离层组合模型与非差非组合模型进行批量静态定位解算,对比两者的定位精度以及ZPD估计精度。设计并实现两种模型的并行解算方法,提高非差模型的计算效率。大网数据实验结果表明,两种模型定位精度基本一致,非差非组合ENU的3个方向平均偏差为(4.2,2.8,6.6)mm,组合模型的平均偏差为(4.0,2.8,6.3)mm,但非差非组合模型的解算更加耗时,约是组合模型计算时间的1.4倍。多核环境下,两种模型的并行解算效率均比传统串行模型得到了提高。结果表明,双核并行和四核并行的计算效率比单核串行计算均分别提高了40%和60%以上。 相似文献
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Sea level in the vicinity of Miami, Florida, is from three separate time series: Miami Beach (1932–1980), Haulover Pier (1982–1992), and Virginia Key (1994-present). In order to calculate the ensemble trend in Miami mean sea level (MSL), the three records must be merged with respect to the North American Vertical Datum of 1988. Because NAVD88 minus accepted MSL varies for the stations, the differences are treated as datum shifts, and are corrected accordingly. Thus adjusted, Merged Miami Sea Level (1932–2013) has a linear trend of 23.4 ± 1.3 cm/century, and along with logarithmic and polynomial least-squares fits, all three having a variance explained (r2 × 100) of 82.4%. 相似文献
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利用GAMIT/GLOBK软件处理2011年特种监测网的观测数据,将IGS站的选取分10种方案进行试验,计算结果从基线长度变化、测站坐标、NRMS、基线重复率等方面进行了比较。得出利用GAMIT/GLOBK软件处理该特种监测网时的几点建议:建议选取IGS站为GPS网提供参考框架;IGS站选取的数量不一定最多,但空间上应尽量均匀分布;选取7个IGS站时得到较高精度的结果。在日后处理此类型的特种监测网时对IGS站选取具有一定的参考价值。 相似文献
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Precision of high-resolution multibeam echo sounding coupled with high-accuracy positioning in a shallow water coastal environment 总被引:2,自引:1,他引:2
Verner B. Ernstsen Riko Noormets Dierk Hebbeln Alex Bartholomä Burg W. Flemming 《Geo-Marine Letters》2006,26(3):141-149
Over 4 years, repetitive bathymetric measurements of a shipwreck in the Grådyb tidal inlet channel in the Danish Wadden Sea were carried out using a state-of-the-art high-resolution multibeam echosounder (MBES) coupled with a real-time long range kinematic (LRK?) global positioning system. Seven measurements during a single survey in 2003 (n=7) revealed a horizontal and vertical precision of the MBES system of ±20 and ±2 cm, respectively, at a 95% confidence level. By contrast, four annual surveys from 2002 to 2005 (n=4) yielded a horizontal and vertical precision (at 95% confidence level) of only ±30 and ±8 cm, respectively. This difference in precision can be explained by three main factors: (1) the dismounting of the system between the annual surveys, (2) rougher sea conditions during the survey in 2004 and (3) the limited number of annual surveys. In general, the precision achieved here did not correspond to the full potential of the MBES system, as this could certainly have been improved by an increase in coverage density (soundings/m2), achievable by reducing the survey speed of the vessel. Nevertheless, precision was higher than that reported to date for earlier offshore test surveys using comparable equipment. 相似文献
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海底观测网因其实时、长期、连续、高精度时钟同步及原位等优势而逐渐成为人类研究海洋的新型平台,建设规模和应用水深都在不断扩大。海底观测网系统建设中,深水设备的精准定点布放及湿插拔作业是施工的难点。针对国内海底观测网精准定位布放作业存在的困难和问题,结合国内现有施工条件,提出一种大深度海底设备精准定点布放安装方法,实现南海深海海底观测网试验系统深水设备精准定位布放与ROV湿插拔作业,对未来大规模海底观测网及其它深水工程中设备的精准定点布放和安装,具有参考和借鉴意义。 相似文献
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Y. Gao 《Marine Geodesy》2013,36(4):279-288
Global positioning system (GPS) has found applications in various areas including marine geodesy. GPS positioning accuracy, however, is greatly degraded by GPS ephemeris and clock errors, particularly errors due to Selective Availability (SA). Thus, it is crucial to use precise ephemeris and clock corrections for users who require high position accuracy. Presently, precise ephemeris and clock corrections are available only in post‐mission. This paper investigates the generation of precise real‐time ephemeris and clock corrections and the positioning accuracy using them. In this research, precise real‐time ephemeris is generated from accurate dynamic orbit prediction and clock corrections are calculated using instantaneous GPS measurements. Numerical analysis using data from an actual GPS tracking network is performed that indicates use of precise ephemeris and clock corrections can improve the positioning accuracy to the one meter level. This accuracy is attainable in real‐time as the precise real‐time ephemeris and clock corrections become available in the future. 相似文献
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One amazing heritage of the current altimetry missions, Jason-2, CryoSat-2 (without mentioning their predecessors TOPEX-Poseidon, ERS, Jason-1, and EnviSat) is that DORIS using DIODE On-Board Orbit Determination software calculate orbits in real-time with accuracy. For example, accuracy has been improved to 2.7 cm RMS on board DORIS/Jason-2 compared with the final Precise Orbit Ephemerides (POE) orbit, generally known to have less than 1 cm accuracy on the radial component. Simultaneously, an efficient integrity team on-ground continually monitors the health of the DORIS system.In February 2013, SARAL/AltiKa was launched hosting a DORIS DGXX receiver with the latest LV11 software as previously used in Jason-2 and CryoSat-2. DORIS on-board SARAL has since been permanently producing results efficiently every ten seconds without exception, including during manoeuvring phases. Spacecraft, ground-system, and users are provided with real-time information on the satellite position: the accuracy is approximately 3.0 cm RMS on the radial component, which is a major break-through for Near Real-Time (NRT) processing. These results are detailed in the paper. Future DORIS/DIODE versions will be used on-board Jason-3 and Sentinel-3. 相似文献
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2011年3月11日日本宫城县以东太平洋海域发生Mw9.0级特大地震,造成了地表的严重错位并引发海啸。文中利用位于日本及周边国家的IGS站和国家海洋局GPS业务站观测数据,采用作者研制的精密单点定位(PPP)软件UniP,对此次地震的GPS数据响应进行了研究。结果表明:(1)GPS观测数据能清晰、连续地记录震时地表形变的过程,我国CHAN,NCST等站点水平方向的震时最大位移在10 cm以内,高程方向的震时最大位移在15 cm以内,且形变以可恢复性的弹性形变为主。(2)我国距震中较远,受此次日本地震的影响较小,且大部分站点是在东坐标方向出现不同程度的震后永久性位移。其中CHAN站点的震后位移最为明显,东向形变量为(1.8±0.11)cm;NCST、NLHT站点次之,东向形变量分别为(1.1±0.26)cm和(1.0±0.18)cm。(3)地震波传输到国家海洋局GPS业务站NCST、NLHT等的时间约为10 min,比海啸在深海的传播速度快约14倍,可为海啸预警提供所需的时间差。这些结果显示出GPS能够为地震监测和动力学特征研究提供有价值的基础资料,也表明中国沿海GPS业务观测系统在海底地震监测、海啸预警服务中的应用潜力。 相似文献
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ABSTRACT Macrofaunal communities of the Central Indian Basin (CIB) were sampled with a spade before (June 1997), and immediately after (August 1997), and 44 months (April 2001) after a simulated benthic disturbance for polymetallic nodule mining. The average density recorded down to a sediment depth of 40 cm ranged from 89 to 799 ind·m?2 (mean: 373 ± 221 SD; n = 12) and 178–1066 ind·m?2 (mean: 507 ± 489 SD; n = 3) in the test and reference area, respectively. Most of the macrobenthic animals (64%) were concentrated in the upper 0 to 2 cm sediment layers, whereas, sizeable fauna (6%) inhabited the 20–40 cm sediment section and the deepest 5 cm section from 35–40 cm contributed only about 2% to the total population density. The fauna, comprised of 12 groups, were dominated by the nematodes, which constituted 54% of the total population. The macrofaunal density in the test site showed a significant increase (x:400 ind·m?2) in the 44 months postdisturbance sampling (x:320 ind·m?2). The population of nematodes and oligochaetes was nearly restored after 44 months, but the polychaetes and crustaceans did not reach the baseline populations measured in June 1997. The top 0–2 cm sediment layer was severely affected by the disturber, and the study suggests that physically disturbed deep-sea macrofauna may require a longer period for restoration and resettlement than normally believed. 相似文献
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为实现多频多模GNSS浮标在远距离海洋潮汐测量中的应用,基于精密单点定位(precision pointing positioning,PPP)数据处理策略获取潮位信息,以压力验潮仪为参考,对GNSS浮标测量海面高进行经验模态分解(empirical mode decomposition,EMD),滤去高频波浪和噪声,获取潮位进行精度分析。结果表明:多系统可以提高PPP解算潮位精度。GPS/GLONASS双系统和GPS/GLONASS/Bei Dou三系统PPP提取潮位与验潮仪潮位差值的最大误差均小于18cm,RMSE小于6. 5cm。因此,多系统PPP解算GNSS浮标海面高可以实现远离海岸的潮位获取与监测,能够提高海上潮位测量的效率。 相似文献
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Ryoko Nakata Shin’ichi Miyazaki Mamoru Hyodo Takane Hori 《Marine Geophysical Researches》2014,35(3):311-317
The Hyuga-nada region of southwest Japan, which is located off the east coast of Kyushu Island, may have the potential to generate great interplate earthquakes along the Nankai trough in the future. In this area, thrust earthquakes of M = 6.7–7.2 have occurred with recurrence intervals of approximately 30 years. In association with these earthquakes, possible local heterogeneities of plate coupling may be expected within 100 km from the coast in the Hyuga-nada region. We investigate numerical experiments to determine the spatial and temporal resolution of slip on the plate interface beneath the Hyuga-nada offshore region. For this purpose, we calculated synthetic displacement data from the result of numerical simulation conducted for the afterslip following an Mw 6.8 earthquake, for existing global positioning system stations on land and planned ocean floor seismic network stations. The spatial and temporal distribution of fault slip is then estimated using a Kalman filter-based inversion. The slip distribution estimated by using ocean floor stations demonstrates that the heterogeneity of plate coupling is resolved approximately within 50 km from the coastal area. This heterogeneity corresponds to the coseismic area of an Mw 6.8 earthquake with a radius of 10 km. Our study quantitatively evaluates the spatial resolution of aseismic slip in the Hyuga-nada region. Analysis based on continuous ocean floor data is useful for resolving the spatial variations of heterogeneities in plate couplings. 相似文献
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To better monitor the vertical crustal movements and sea level changes around Greenland, multiple data sources were used in this paper, including global positioning system(GPS), tide gauge, satellite gravimetry, satellite altimetry, glacial isostatic adjustment(GIA). First, the observations of more than 50 GPS stations from the international GNSS service(IGS) and Greenland network(GNET) in 2007–2018 were processed and the common mode error(CME) was eliminated with using the principal component analysis(PCA). The results show that all GPS stations show an uplift trend and the stations in southern Greenland have a higher vertical speed. Second, by deducting the influence of GIA, the impact of current Gr IS mass changes on GPS stations was analysed, and the GIA-corrected vertical velocity of the GPS is in good agreement with the vertical velocity obtained by gravity recovery and climate experiment(GRACE). Third, the absolute sea level change around Greenland at 4 gauge stations was obtained by combining relative sea level derived from tide gauge observations and crustal uplift rates derived from GPS observations, and was validated by sea level products of satellite altimetry. The results show that although the mass loss of Gr IS can cause considerable global sea level rise, eustatic movements along the coasts of Greenland are quite complex under different mechanisms of sea level changes. 相似文献