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991.
Compared to hydrograph recession analysis, which is widely applied in engineering hydrology, the quantitative assessment of stream salinity with time (i.e. the salinograph) has received significantly less attention. In particular, while in many previous hydrological studies an inverse relationship between hydrograph and salinograph responses is apparent, the concept of salinity accession (the inversely related salinity counterpart to hydrograph recession) has not been introduced nor quantitatively evaluated in previous literature. In this study, we conduct a mathematical analysis of salinograph accession, and determine new quantitative relationships between salinity accession and hydrograph recession parameters. An equation is formulated that reproduces the general trend in salinity accession. A salinity accession parameter kc is then introduced and is shown to be the ratio of direct runoff to total stream flow recession parameters: kr/k. The groundwater recession parameter kg was estimated using a simple and rapid method that uses both salinograph and hydrograph data. Salinity accession type‐curves illustrate that under certain conditions, the relative steepness of individual salinographs is dependent upon the ratio of groundwater salinity to direct runoff salinity: Cg/Cr. The salinity accession algorithms are applied to two contrasting field settings: Scott Creek, South Australia and Sandy Creek, northern Queensland, Australia. It was found that kg > k during periods of obvious stream flow recession, for the events analysed. Salinograph accession behaviour was fairly similar for both sites, despite contrasting environments. Using assumed end‐member salinities for groundwater and direct runoff based upon field observations, the behaviour of kc from the Scott Creek site was approximately reproduced by varying the initial groundwater to runoff flow ratio: Qg0/Qr0, within reasonable parameter ranges. The use of salinograph information when used in addition to standard hydrograph analyses provided useful information on recession characteristics of stream components. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
992.
Peter Wilson Michael J. Bentley Christoph Schnabel Richard Clark Sheng Xu 《第四纪科学杂志》2008,23(5):461-473
Cosmogenic isotope (10Be and 26Al) surface exposure dating has been applied to valley‐axis and hillslope stone runs (relict periglacial block streams) and their source outcrops in the Falkland Islands, South Atlantic. The data indicate that stone runs are considerably older landforms than previously envisaged and afford no evidence that they are a product of the Last Glacial Maximum; the samples range in apparent 10Be age from 42k to 731k yr BP, but some of these are minima. The results indicate that valley‐axis stone runs may be up to 700–800k yr old, have simple exposure histories and are composite landforms that developed over several cold stages. Analyses of some hillslope and outcrop samples also demonstrate simple exposure histories with 10Be ages from 42k to 658k yr BP. In contrast, isotopic ratios from other hillslope and outcrop samples reveal they have had a complex exposure history involving periods of burial or shielding; the samples range in 10Be age from 59k to 569k yr BP and these are regarded as minimum age estimates. Larger stone runs may be older than smaller runs and there is a possibility that stone runs older than 800k yr exist in other parts of the Falklands. The assertion that glaciation in the Falklands was restricted to the highest uplands is supported by the data, and the potential for age determination of other boulder‐strewn and bedrock landforms, using cosmogenic isotope analysis, in order to extend the geochronology of Quaternary events and processes is noted. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
993.
Evaporation (E) rate and precipitation (P) rate are two significant meteorological elements required in the ocean baroclinic
modeling as external forcings. However, there are some uncertainties in the currently used E/P rates datasets, especially
in terms of the data quality. In this study, we collected E/P rates data from ERA-40, NCEP/NCAR Reanalysis, HOAPS for the
Bohai Sea and nine routine stations around Laizhou Bay, and made comparisons among them. It was found that the differences
in E/P rates between land and sea are remarkable, which was due to the difference in underlying surfaces. Therefore, the traditional
way of using E/P rates acquired on land directly at sea is not correct. Since no final conclusion has been reached concerning
the net water transport between the Bohai Sea and the Yellow Sea, it is unfeasible to judge the adequacy of the four kinds
of data by using the water budget equation. However, the E/P rates at ERA-40 sea points were considered to be the optimal
in terms of temporal/spatial coverage and resolution for the hindcast of salinity variation in the Bohai Sea. Besides, using
the 3-D hydrodynamic model HAMSOM (HAMburg Shelf Ocean Model), we performed numerical experiments with different E/P datasets
and found that the E/P rates at sea points from ERA-40 dataset are better than those from NCEP/NCAR Reanalysis dataset. If
NCEP/NCAR Reanalysis E/P rates are to be used, they need to be adjusted and tested prior to simulation so that more close-to-reality
salinity values can be reproduced. 相似文献
994.
利用机载GNSS反射信号反演海面风速的研究 总被引:2,自引:0,他引:2
全球卫星导航定位系统的反射信号(GNSS-R)遥感技术作为一种新型的、低成本的、高机动性的海面微波遥感测风技术,与其他测风手段优势互补,可以增加测风手段的多样性,弥补局部测风手段不足的状况。研究了接收机在机载高度时,GPS反射信号功率理论模型四部分函数的性质,在此基础之上,数值模拟了机载高度下理论相关功率波形,基于海面风速对波形峰值与后沿的影响,提出了一种能够兼顾所有理论波形信息的二维插值风速反演方法。利用该方法,结合实测机载数据对海面风速进行反演,反演的风速均值与附近测站风速均值相差为1.4 m/s,与浮标数据相一致。 相似文献
995.
N. J. Anderson 《Journal of Paleolimnology》1990,4(1):43-59
The variability of diatom distribution in an acidified, upland wind-stressed lake (Loch Fleet, Galloway, S. W. Scotland) was assessed by analysis of 28 surface sediment samples and 11 cores. Correspondence analysis (CA) and cluster analysis were used to illustrate the variability of the surface sediment and core samples. There was reasonable uniformity of taxa in most of the surface sediment samples, although 7 samples, as indicated by both CA and cluster analyses were atypical. Most cores recorded clearly the acidification of the lake, although percentages of individual taxa varied up to 20% between cores. Two cores had old, preacidification diatom assemblages (of indeterminate age) close to the sediment surface. These old sediments were probably the source of the re-worked diatoms found in the atypical surface sediment assemblages. Diatom trends, as CA ordinations and pH profiles, were less variable than the surface sediment assemblages. It is argued that non-uniform sediment accumulation rates and diatom deposition cause variability in surface sediment diatom samples. This variability may be reduced in core profiles by homogenization during further resuspension/deposition cycles and burial. Cores, and the associated time component they offer, may be useful in assessing the variability of surface sediment assemblages. 相似文献
996.
利用南极走航观测评估卫星遥感海表面温度 总被引:3,自引:1,他引:2
利用1989-2005年间南极走航观测的海表面温度,对目前3个主要的卫星反演的SST产品AVHRR(Advanced Very High Resolution Radiometer),TMI(TRMM Microwave Imager)和AMSR-E(Advanced Microwave Scanning Radiometer for the Earth Observing System)进行了较为系统的评估,并着重检验了它们在南大洋的准确性.结果表明,AVHRR SST比观测数据偏冷,白天的偏差为-0.12℃,夜晚的偏差为-0.04℃,而且南大洋的冷偏差更为显著.TMI SST比观测数据明显偏暖,白天的偏差为0.48℃,夜晚的偏差为0.57℃,其温差ΔT受37GHz风速影响,在强风速(>6m/s)下这种影响仍然存在.AMSR-ESST比观测数据偏暖,白天的偏差为0.34℃,夜晚的偏差为0.27℃,而且南大洋的暖偏差相对较大.AMSR-E SST温差受水汽影响,并在南大洋随着水汽的增加而增加.通过进一步比较微波(AMSR-E和TMI)和红外(AVHRR)遥感的SST在2004年北半球冬季(即南半球夏季)的差别,发现微波遥感在热带(15°S-15°N)和南大洋区域(45°S以南)比红外遥感偏暖,而且在南大洋区域的偏差相对较大,相反在北半球中纬度区域(15°~40°N)偏冷.AMSR-E与AVHRR SST的温差,从白天到夜晚有减小的趋势,而TMI与AVHRR SST的温差无明显的变化. 相似文献
997.
998.
利用LINUX操作系统下的进程通讯(IPC)技术将中尺度大气模式MM5(V3)与第三代海浪模式WW3进行双向耦合,建立考虑大气-海浪相互作用的风浪耦合模式,在耦合模式中引入3种海表粗糙度参数化方案,通过对一次热带气旋过程的模拟,研究大气-海浪相互作用对热带气旋系统的影响及耦合模式对海表粗糙度参数化方案的敏感性。结果表明:LINUX系统下的进程通讯技术可以方便有效地实现大气和海浪模式的双向耦合,模式运行稳定;耦合模式能够较好的模拟热带气旋的发展和演变过程及其影响下海浪场的分布和演变,模拟结果对海表粗糙度参数化方案较敏感;海浪的反馈作用同时影响了海气间的动力和热力作用过程,不同的海表粗糙度参数化方案下,海浪对两种作用过程不同的影响程度决定了其对气旋系统强度的影响。 相似文献
999.
2006年9月南海北部表层温盐场的走航观测 总被引:1,自引:0,他引:1
通过2006年9月南海北部开放航次的走航观测,得到了该海区多个断面的表层温度、盐度分布曲线.QuikScat海面风场资料显示观测期间处于西南季风向东北季风的转换阶段,走航观测所得的温、盐资料显示出在这一季风转换的特殊阶段该海区表层的水文特征.珠江口冲淡水的扩散范围在季风转向前后有显著的变化,低盐的冲淡水在西南季风阶段向珠江口外海区的东南方延伸较远,而在东北季风阶段则受珠江径流量、南海北部表层环流等因素的影响收缩至珠江口附近.闽南近岸和台湾浅滩南部表层具有低温高盐特征,但CTD资料表明台湾浅滩区域存在上升流,结合风场资料,可证实观测期间此处的上升流由海流-地形因素所造成. 相似文献
1000.
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