Experiments on the ocean sequestration of fossil fuel CO₂: pH measurements and hydrate formation     

Peter G. Brewer  Edward T. Peltzer  Gernot Friederich  Izuo Aya  Kenji Yamane 《Marine Chemistry》2000,72(2-4)

We have carried out a series of in situ experiments to investigate the formation of a CO₂ hydrate (CO₂:5.75 H₂O) for the purpose of evaluating scenarios for ocean fossil fuel CO₂ disposal with a solid hydrate as the sequestered form. The experiments were carried out with a remotely operated vehicle in Monterey Bay at a depth of 619 m. pH measurements made in close proximity to the hydrate–seawater interface showed a wide range of values, depending upon the method of injection and the surface area of the hydrate formed. Rapid injection of liquid CO₂ into an inverted beaker to form a flocculant mass of hydrate resulted in pH initially as low as 4.5 within a few centimeters of the interface, decaying slowly over 1–2 h towards normal seawater values as dense CO₂ rich brine drained from the hydrate mass. In a second experiment, slower injection of the liquid CO₂ to produce a simple two-layer system with a near planar interface of liquid CO₂ with a thin hydrate film yielded pH values indistinguishable from the in situ ocean background level of 7.6. Both field and laboratory results now show that the dissolution rate of a mass of CO₂ hydrate in seawater is slow but finite.  相似文献   

Micrometer measurements of visual double stars at Calar Alto     

J. F. Ling  V. Lanchares 《Astronomische Nachrichten》1993,314(4):303-305

We present 93 micrometer measurements of 55 double stars observed with the 152 cm telescope at the Spanish observatory at Calar Alto (Almeria, Spain).  相似文献   

一种优化模糊度搜索方法的研究   总被引：1，自引：0，他引：1  

刘立龙  文鸿雁  唐诗华 《海洋测绘》2006,26(1):37-39,53

对于高精度测量和导航,GPS载波相位整周模糊度的快速求解仍然是一个难点,尤其对于单频接收机。提出一种快速求解整周模糊度的方法,其基本思想采用分步求解,首先应用最小二乘模糊去耦调节法(LAMBDA)搜索出来的模糊度作为初始值,然后应用卫星分组方法降低搜索维数,并应用极大似然准则,构造搜索函数,最后应用最优化原理,搜索出最优的模糊度参数,并从三个方面对其进行检验,即RATIO检验,OVT检验,多项式拟合残差检验。为验证该算法,我们用单频GPS接收机进行了实验,利用本文方法在11 S以内正确确定了模糊度,其基线长误差小于3MM,表明该方法不但可以改进模糊度的搜索速度,而且可以进一步提高其可靠性和成功率。该方法可广泛应用于定向及姿态测量。  相似文献   

IN SITU MEASUREMENTS OF BASAL WATER QUALITY AND PRESSURE AS AN INDICATOR OF THE CHARACTER OF SUBGLACIAL DRAINAGE SYSTEMS     

DAN B. STONE  GARRY K. C. CLARKE 《水文研究》1996,10(4):615-628

Continuous subglacial measurements of turbidity and electrical conductivity — two indicators of basal water quality — can be used to help characterize subglacial drainage systems. These indicators of water quality yield information that complements that provided by water pressure measurements. Quantitative attributes of subglacial drainage systems, such as water velocity and subglacial residence time, as well as qualitative behaviour — for example, spatial and temporal variations in system morphology — can be deduced using water quality measurements. Interpretation is complicated by the many potential influences on turbidity and electrical conductivity, but when these complications are appreciated a richer interpretation results. To demonstrate the utility of basal water quality measurements, observations from Trapridge Glacier, Yukon Territory, Canada were examined. The data reveal complex behaviour of the drainage system, but constraints imposed by basal water quality measurements help to clarify the nature of the subglacial flow system. The measurement and interpretation methods described and demonstrated are applicable to other glaciers. As such, they should prove useful for characterizing different subglacial drainage configurations and behaviours, thereby improving our general understanding of the hydrology and dynamics of wet-based glaciers.  相似文献   

Design of high precision horizontal control network for large-scale hydropower project     

ZHANG Zhenglu LUO Changlin DENG Yong XIE Niansheng 《地球空间信息科学学报》2006,9(4):235-239

IntroductionThe design of high precision horizontal controlnetwork for large-scale hydropower project toconstruct control network and measure deforma-tion of monitoring network.It can be also divid-ed into horizontal control network and verticalcontrol ne…  相似文献   

Determination of the degree 120 time-variable gravity field in the Sichuan-Yunnan region using Slepian functions and terrestrial measurements          下载免费PDF全文

Jiancheng Han  Shi Chen  Zhaohui Chen  Hongyan Lu  Weimin Xu 《地震科学（英文版）》2021,34(3):211-221

The terrestrial time-variable gravity measurements are characterized by a high signal-to-noise ratio and sensitivity to the sources of mass change in the Earth's crust. These gravity data have many applications, such as surface deformation, groundwater storage changes, and mass migration before and after earthquakes. Based on repeated terrestrial gravity measurements at 198 gravity stations in the Sichuan-Yunnan region (SYR) from 2015 to 2017, we determine a time series of degree 120 gravity fields using the localized spherical harmonic (Slepian) basis functions. Our results show that adopting the first 6 Slepian basis functions is sufficient for effective localized Slepian modeling in the SYR. The differences between two gravity campaigns at the same time of year show an obvious correlation with tectonic features. The degree 120 timevariable gravity models presented in this paper will benefit the study of the regional mass migration inside the crust of the SYR and supplement the existing geophysical models for the China Seismic Experimental Site.  相似文献   

Analysis and results of cooperative magnetographic measurements III. Vertical gradients of the magnetic field in the sunspot photosphere     

A. Hofmann  J. Rendtel 《Astronomische Nachrichten》1989,310(1):61-65

We compare vertical gradients of sunspot magnetic fields which were derived for the first time from nearly simultaneous vector magnetograms. The measurements were obtained in the photospheric lines Fe I 5250 and Fe I 5253 by the vector magnetographs of the Sayan-Observatory (Irkutsk) and the Solar Observatory “Einsteinturm”. The gradients derived from the different measurements show a good correspondence with respect to the numerical values as well as to the morphological structure of the distributions in the magnetograph's field of view. In the umbral region of the spot the vertical gradients amount to about 0.32 Gkm^-1 indicating that the umbral field can extend with strong field strengths into chromosphere and corona. A circle-like area with opposite sign to the umbral gradient was found on the boundary between penumbra and surrounding photosphere. The physical significance of this area should be the goal of further observations and interpretations. Wir vergleichen Vertikalgradienten des Magnetfeldes von Sonnenflecken, die erstmals aus fast simultan aufgenommenen Vektormagnetogrammen abgeleitet wurden. Die Messungen erfolgten unter Verwendung der photosphärischen Linien Fe I 5250 Å und Fe I 5253 Å mit den Vektormagnetografen des Sayan-Observatoriums (Irkutsk) und des Sonnenobservatoriums “Einsteinturm”. Die aus den verschiedenen Messungen ermittelten Gradienten zeigen sowohl hinsichtlich der numerischen Werte als auch bezüglich der morphologischen Struktur ihrer Verteilung im Bildfeld der Magnetografen eine gute Übereinstimmung. Im Kern des Flecks erreicht der Vertikalgradient 0,32 g kin^-1. Das weist darauf hin, daß sich das umbrale Feld mit hoher Feldstärke bis in die Chromosphäre und Korona erstrecken kann. Ein kreisförmiges Gebiet mit entgegengesetztem Vorzeichen zum umbralen Gradienten ist an der Grenze zwischen Penumbra und umgebender Photosphäre zu finden. Die physikalische Bedeutung dieses Gebietes soll durch weitere Beobachtungen und Auswertungen geklärt werden.  相似文献   

青岛沿海24种鱼类耳石秤量特征与鱼体大小关系     

王英俊  吴莹莹  邹琰  刘童  刘洪军  宋爱环 《海洋科学》2018,42(8):48-55

研究中经常会用测量耳石称量特征推算饵料鱼类的形态参数,而青岛沿海鱼类相关的研究较少,因此作者根据2015年3、5、8月3个航次在青岛近海的拖网调查数据,分析了捕获的24种共1002尾鱼的耳石秤量特征(耳石长、耳石宽和耳石质量)和鱼体大小(体长、体质量)的关系。结果表明,渔获24种鱼类分属5个目、14个科、24种鱼类的体长体质量呈显著幂函数相关,相关系数R~2的范围为0.779～0.997,幂指数b的范围为2.376～3.591,平均值为3.048±0.327,其中黄鲫(Setipinna taty)等11种鱼类的b值均大于3(P0.05),为正异速生长,其余13种鱼类的b值小于3(P0.05),呈负异速增长。耳石宽-鱼体长的相关性比耳石长-鱼体长的相关性要好,仅有3种鱼(饰鳍斜棘鱼衔(Repomucenus ornatipinnis)、矛尾虾虎鱼(Chaeturichthys stigmatias)和焦氏舌鳎Cynoglossus lighti)未呈现显著相关关系。在耳石质量-鱼体质量的相关关系中,9种鱼(如皮氏叫姑(Johnius belengerii)、扁斜棘?(Repomucenus planus)、石鲽(Kareius bicoloratus)呈显著相关(只是列举了一部分), 5种鱼(锦鳚(Pholis nebulosus)、矛尾虾虎鱼(Chaeturichthys stigmatias)、斑尾刺虾虎鱼(Synechogobius ommaturus)、焦氏舌鳎(Cynoglossus lighti))在现有样品情况下未呈现显著相关关系。  相似文献   

涉密矢量数字地图中敏感要素几何信息量的测度方法     

李安波  陈楹  姚蒙蒙  吴赛松 《地球信息科学学报》2018,20(1):7-16

涉密矢量数字地图中敏感要素几何信息的定量测度,是实现定量化密级评定的基础和前提。如何进行敏感要素几何信息量的计算,目前尚缺乏相关研究。在现有地图信息论研究成果的基础上,论文主要开展了3方面的研究工作：首先,从地理对象的敏感性入手,探讨了地图要素敏感性的定义与要素集合的敏感性表征指标;然后,基于任意发生元的Voronoi构建方法,实现了对点要素集、线要素集、部分覆盖面要素集及综合要素集的信息单元自动化剖分;最后,基于长度系数、面积系数和角度系数,提出了线、面要素图形复杂度的计算方法,并在此基础上形成了涉密矢量数字地图中敏感几何信息量的测度方法。实验表明,该方法的计算结果遵循了信息量的非负性、连续性、可加性等特点,较为合理地反映了相关因素（地图比例尺、要素空间分布、要素图形复杂度、要素敏感系数等）对计算结果的影响。相关成果将支持矢量数字地图的定量化密级评定,并有助于完善地理信息安全监管的理论和方法体系。  相似文献   

Storm surge induced flux through multiple tidal passes of Lake Pontchartrain estuary during Hurricanes Gustav and Ike     

Chunyan Li  Eddie Weeks  Brian W. Blanchard 《Estuarine, Coastal and Shelf Science》2010

In September 2008, Hurricanes Gustav and Ike generated major storm surges which impacted the Lake Pontchartrain estuary in Louisiana. This paper presents analyses of in situ measurements acquired during these storm events. The main data used in the analyses were from three bottom mounted moorings equipped with conductivity, temperature, and depth sensors, acoustic Doppler current profilers (ADCPs), and a semi-permanent laterally mounted horizontal acoustic Doppler profiler (ADP). These moorings were deployed in the three major tidal channels that connect Lake Pontchartrain with the coastal ocean. A process similar to tidal straining was observed: the vertical shear of the horizontal velocity was negligible during the inundation stage, but a shear of 0.8 m/s over a less than 5 m water column was recorded during the receding stage, 2–3 times the normal tidal oscillations. The surge reached its peak in the Industrial Canal 1.4–2.1 h before those in the other two channels. The inward flux of water lasted for a shorter time period than that of the outward flux. The inward flux was also observed to have much smaller magnitude than the outward flux (∼960–1200 vs. 2100–3100 million m³). The imbalance was believed to have been caused by the additional water into Lake Pontchartrain through some small rivers and inundation over the land plus rainfall from the hurricanes. The flux through the Industrial Canal was 8–12%, while the flux through the other two tidal passes ranged between 17% and 70% of the total, but mostly split roughly half-half of the remaining (∼88–92% of the total).  相似文献