Baseflow water chemistry in New Zealand rivers 1. Characterisation     

Murray E. Close  Robert J. Davies‐Colley 《新西兰海洋与淡水研究杂志》2013,47(3):319-341

In late summer to autumn 1987, 96 rivers throughout New Zealand were sampled in baseflow (< median flow) conditions, usually on three separate occasions. A wide range of water quality determinands were analysed to characterise water quality comprehensively at lower than median flows. River waters in New Zealand range widely in composition, particularly plant nutrients, but tend to be more dilute than world average freshwater (WAFW) because run‐off (specific yield) of water is generally high. Sodium and calcium are the most important cations in New Zealand rivers which can be described as “calcium‐sodium bicarbonate waters”, whereas WAFW is calcium bicarbonate water. Almost all river sites met existing guidelines and standards for drinking water, ecological protection, and freshwater fisheries.  相似文献   

水位波动对临海重力式挡墙基坑稳定性的影响   总被引：1，自引：0，他引：1  

应宏伟  聂文峰  王啟铜  程勇 《海洋工程》2013,31(4):48-54

近年来临海(江)建设的地下工程逐渐增多,与常规静水补给条件下的基坑工程相比,受波浪、潮汐等动水作用影响的基坑可能展现出不同的性状,对该类水力条件下基坑响应问题的研究具有重要的工程意义。依托港珠澳大桥珠海连接线拱北隧道海域段基坑工程,采用PLAXIS软件对波浪、潮汐作用下重力式挡墙两侧的水土压力、基坑的稳定性进行了探讨分析。结果表明,对于均质砂质地基上的重力式挡墙,当基坑距防波堤一定距离时,波浪对其稳定性的影响可以忽略不计;潮汐在海床和基坑中的传播有滞后效应,当潮汐为最高潮位时,基坑并非处于最危险状态;潮汐作用下临海重力式挡墙基坑的稳定性可以通过拟静水位法近似分析。  相似文献   

低频数据体的属性提取在储层预测中的应用     

党丹  李金泉 《海洋地质前沿》2013,(12):65-70

在利用地震属性进行储层预测的过程中,由于地震数据受地下断裂或裂缝的影响,高频信息部分振幅损失严重,使得储层预测结果经常不能与真实储层的发育情况相吻合。提出利用地震数据的低频部分提取属性来预测储层,无论是在理论数据的试算还是在实际地震资料的应用中,都取得了较好的效果。证明了该方法的有效性,指导了地震解释工作的顺利进行。  相似文献   

Textural Characteristics of Surface and Core Sediments of Ilmenite-Enriched Coasts of Southwest,India     

Babu Nallusamy  Sinirani Babu  D. S. Suresh Babu 《Marine Georesources & Geotechnology》2013,31(6):521-531

Sediment samples from the foreshore and backshore regions between Thottappally and Kayamkulam, (Thottappally – Trikkunnapuzha = Northern; Trikkunnapuzha – Arattupuzha = Central; Arattupuzha – Kayamkulam = Southern), which are enriched with heavy minerals, were subjected to detailed textural evaluation. Through frequency curves, bivariate and CM pattern, the textual characteristics of black sand deposits have been brought out and their provenance has been discussed. Beach sands of the study area mainly comprise fine sand, moderately well- to well-sorted, with near symmetrical skewness in all three sectors. Kurtosis is platykurtic in the northern sector, whereas mesokuritic sediments in the central and southern sectors show a characteristic playtkuritc nature. In the Trikkunnapuzha – Arattupuzha and Aratupuzha – Kayamkulam sectors, sediments are mesokurtic to platykurtic, which shows that low energy conditions and high wave energy conditions must have prevailed. Sediment transportation is mainly by saltation. The bivariate textural plots indicate beach and inland involvement for these sediments. The CM pattern also indicates that the sources for the sediment deposition in the study area were beach with the influence of fluvial and high-energy waves.  相似文献   

Validation of Jason and Envisat Altimeter Dual Frequency Rain Flags     

JEAN TOURNADRE 《Marine Geodesy》2013,36(1-2):153-169

New rain flags based on the dual frequency capabilities of the new Jason Poseidon-2 and Envisat RA2 altimeters have been tested, developed and adopted for the operational processing of the altimeter data. Their validation conducted during the calibration/validation phases of the satellites is presented here. The Jason flag is validated by comparison with the TOPEX one, using the Tandem mission. The results show a very good agreement between the two sensors and the two rain flags The Envisat flag is validated by comparison with both Jason and TOPEX using global and collocated data sets. The results show similar performances for the three sensors. The f relations estimated during the calibration-validation period and presented here have been given to the altimeter ground processing facilities for operational use.  相似文献   

Ocean tides for satellite geodesy     

S. R. Dickman 《Marine Geodesy》2013,36(1):21-56

Abstract

Spherical harmonic tidal solutions have been obtained at the frequencies of the 32 largest luni‐solar tides using prior theory of the author. That theory was developed for turbulent, nonglobal, self‐gravitating, and loading oceans possessing realistic bathymetry and linearized bottom friction; the oceans satisfy no‐flow boundary conditions at coastlines. In this theory the eddy viscosity and bottom drag coefficients are treated as spatially uniform. Comparison of the predicted degree‐2 components of the Mf, PI, and M2 tides with those from numerical and satellite‐based tide models allows the ocean friction parameters to be estimated at long and short periods. Using the 32 tide solutions, the frequency dependence of tidal admittance is investigated, and the validity of sideband tide models used in satellite orbit analysis is examined. The implications of admittance variability for oceanic resonances are also explored. By extending the theory to include a second constraint derived from tide observations or data‐constrained tide models, it is possible to assess those models from a fluid dynamic perspective. One general conclusion from such exercises is that the large higher‐degree admittances of current short‐period tide models are dynamically incompatible with their degree‐2 admittances. Eventually it may prove possible to produce dynamically sound, observationally consistent tide models by combining the author's tide theory with satellite orbit determination.  相似文献   

西北太平洋台风频数异常及其与海气通量的关系   总被引：1，自引：1，他引：0  

郑浩阳  武亮  温之平  王同美 《海洋学报》2013,35(3):47-55

利用1984-2002年联合台风预警中心(JTWC)最佳路径台风资料、全球海洋客观分析海气通量(OAFluxes)资料和NCAR/NCEP-2再分析资料,使用SVD等统计方法,对西北太平洋台风频数与低层大气环流及海气通量异常之间的关系进行了研究,结果发现150°E以东的低纬海区是台风频数年际异常变化最显著的区域,台风频数与低层大气环流异常、潜热通量和短波辐射通量变化有着密切的联系:当副热带高压强度减弱(增强)、脊线偏北(南)、主体东移(西伸)时,季风槽加深东进至160°E(西退至140°E),低纬的纬向西风加强(减弱),海洋输送给大气较多(少)潜热通量,盛行的纬向西风携带着季风槽南侧的暖湿水汽与副热带高压南缘偏东气流的水汽输送在150°E以东(以西)的低纬海区辐合,150°E以东辐合上升的暖湿气团吸收的短波辐射偏多(少),有利于(不利于)形成高温高湿的不稳定结构,台风能量不断(不易)积累,在低层强(弱)辐合、高层强(弱)辐散的环境场作用下,有利于(不利于)台风在150°E以东的低纬海区的生成。  相似文献   

太平洋不同海水层结条件下的内波波致声场起伏研究     

李佳讯  张韧  金宝刚  陈奕德 《海洋学报》2013,35(3):78-86

基于Argo资料对太平洋海域海水层结进行分类区划,利用内波动力学方法对内波致声起伏进行数值求解,对不同层结状况下的内波致声起伏进行模拟试验。结果表明:垂直方向海水层结的不均匀和跃层的存在,使海洋内波斜压模态受到了歪曲变形。层结峰的个数和深度与声速起伏存在很好的对应关系。有内波的声传播特征总体上与没有内波时的相似。不同层结情况下,声场对内波扰动的响应不一致。  相似文献   

由斑点图重建天文图像的方法     

霍卓玺  周建锋 《天文学进展》2010,28(1)

首先介绍了斑点图形成机制以及获取方法,并借助计算机模拟了斑点图的生成。然后重点描述斑点图的图像重建方法,包括频率域和空间域重建方法。在频率域重建方法部分依次详细叙述了用于复原模信息的斑点干涉法和用于复原相位信息的由模复原相位法、Knox-Thompson法、斑点掩模法;空间域重建方法部分介绍了典型的LWH法和迭代位移叠加法;另外,盲消卷积法也为斑点图重建提供了新的思路,文章对此方法也做了介绍;特别地,还对国内在该领域的相关工作做了介绍;关于斑点图重建方法在天文学、天体物理学等领域的应用,文章做了有针对性的介绍;最后一章是斑点图图像重建方法的总结。  相似文献   

基于AD9956的任意频率合成器研制     

樊战友  樊西青  张首刚 《时间频率学报》2010,33(2)

为满足精密时间测量和高性能星载原子钟等国家重要研究课题的实验应用需求,研制了主要由AD9956芯片和8位高性能单片机构成的一种DDS(直接数字合成)任意频率合成器。在分析DDS的基本原理和特点的基础上,从硬、软件等方面较为详细地介绍了该频率合成器的设计,对同时完成的专用于控制该合成器工作的计算机应用软件也作了介绍。实际使用结果表明:研制的合成器符合实验使用要求,并对促进课题的研究完成发挥了积极作用。  相似文献