Coastal and shelf circulation in the vicinity of Camamu Bay (14°S), Eastern Brazilian Shelf

The Camamu Bay (CMB) is located on the narrowest shelf along the South American coastline and close to the formation of two major Western Boundary Currents (WBC), the Brazil/North Brazil Current (BC/NBC). These WBC flow close to the shelf break/slope region and are expected to interact with the shelf currents due to the narrowness of the shelf. The shelf circulation is investigated in terms of current variability based on an original data set covering the 2002-2003 austral summer and the 2003 austral autumn. The Results show that the currents at the shelf are mainly wind driven, experiencing a complete reversal between seasons due to a similar change in the wind field. Currents at the inner-shelf have a polarized nature, with the alongshore velocity mostly driven by forcings at the sub-inertial frequency band and the cross-shore velocity mainly supra-inertially forced, with the tidal currents playing an important role at this direction. The contribution of the forcing mechanisms at the mid-shelf changes between seasons. During the summer, forcings in the two frequency bands are important to drive the currents with a similar contribution of the tidal currents. On the other hand, during the autumn season, the alongshore velocity is mostly driven by sub-inertial forcings and tidally driven currents still remain important in both directions. Moreover, during the autumn when the stratification is weaker, the response of the shelf currents to the wind forcing presents a barotropic signature. The meso-scale processes related to the WBC flowing at the shelf/slope region also affect the circulation within the shelf, which contribute to cause significant current reversals during the autumn season. Currents at the shelf-estuary connection are clearly supra-inertially forced with the tidal currents playing a key role in the generation of the along-channel velocities. The sub-inertial forcings at this location act mainly to drive the weak ebb currents which were highly correlated with both local and remote wind forcing during the summer season.     

Annual lamination and its sedimentary implications in the Yangtze River delta inferred from High-resolution biogenic silica and sensitive grain-size records

Annual sedimentary layers in core A from the Yangtze River (Changjiang) subaqueous delta were identified based on high-resolution biogenic silica (BSi) and grain-size records. The contents of BSi, the sediment grain-size and the sensitive grain-size fractions of <13.14 μm and 13.14-250 μm illustrated steady coincident fluctuations with the depth profile of core A. These fluctuations were inferred to reflect seasonal changes in physical and biological processes. For example, variations in the content of BSi likely represent changes in primary production in flood versus dry seasons. It in flood seasons was several times higher than that in dry seasons. The amounts of <13.14 and 13.14-250 μm fractions were complimentary to each other and co-varied with the BSi amount. Therefore, the BSi, grain-size and sensitive fractions can be used as proxies for the annual sedimentation. From 1992 to 2005, the estimated sedimentary rate based on the annual layer varied from 1.0 to 3.5  cm/a (mean of 2.07  cm/a), and these values varies with the annual sediment discharge from the Yangtze River to the sea. The significant seasonal variations in the water discharge, sediment load, ocean hydrodynamics and primary production, which are common in the area affected by the East Asian monsoon, are likely responsible for the formation of the annual sedimentary lamination.     

电子测量仪器自动记录数据格式转换程序设计

电子测量仪器的广泛应用加快了测量速度,提高了测量内外业的工作效率.但是目前的数据格式和数据标准存在不统一,给内业处理和测绘软件的开发带来了许多麻烦.为解决原始测量数据与内业后处理软件匹配问题,本文选取了几种常用数据格式,包括LEICA TC1800原始观测数据格式(*GSI)、LEICA DNA2原始观测数据格式(*m...     

基于VBA的AutoCAD图形和Word表格的数据转换

简要介绍了AutoCAD和Word的对象模型,并通过实例详细阐述了由AutoCAD图形数据自动生成Word格式数据报表的技术原理。最后,结合实际代码验证了该方法的实用性和有效性。     

基于ArcGIS Engine的数据文件到Shapefile转换方法及其实现

地理数据的多源性导致存储格式的多样性,使其难以在同一GIS平台下实现互操作与空间分析,这有碍于信息的共享.为此,以ArcGIS为基础平台,采用ArcGIS Engine组件进行集成二次开发,通过对数据文件进行访问和空间参考的定义、空间与属性信息的转换来实现Excel型数据文件至Shapefile型矢量文件的转换,以初步...     

平坦地区GPS高程转换方法的研究

分析了GPS测量中高程系统转换的实质,介绍了四种GPS高程转换方法的基本原理,然后结合实际算例对四种方法拟合的结果进行了精度分析,总结了各种方法的优缺点,得出一些参考性的结论.     

山西发展低碳经济的SWOT分析

山西作为我国能源大省,＂富煤、富气、少油＂是本省能源结构的典型特征,从而导致其二氧化碳排放量一直位居我国前列,如何实现从＂高碳＂到＂低碳＂的过渡,是山西省目前面临的最严峻挑战。运用SWOT模型分析评价了山西发展低碳经济的优劣势及其机遇和挑战,并构建了SWOT矩阵,对山西省走可持续发展之路有着重要的指导意义。     

军测矢量数据到国测矢量数据转换方法探讨

本文基于1∶5万军测矢量建库数据到国测矢量数据的转换项目,分析了军测数据和国测矢量数据的数据结构的异同,利用GEOWAY,4DMAPPER软件进行数据转换的流程,并对转换过程中的关键性的技术问题进行了详细说明,总结出了军测数据到国测数据的转换方法,为以后的军测数据到国测数据转换提供作业思路,积累了宝贵经验。     

地形图从CAD到MapInfo的转换方法研究

目前大多数现有的地形图都是基于CAD格式绘制、存储的,但是CAD格式在数据分析、管理和处理上受到限制,需要转换成GIS格式。本文对地形图从AutoCAD(.dwg)数据格式转换为MapInfo(mid/mif)GIS数据,从图层组织、数据要素管理和背景图形方面对各种方法进行了分析研究。     

总体最小二乘法在坐标转换中的应用

在测量数据处理中,最为经典的处理方法是最小二乘法,认为误差只是包含在观测向量当中,系数矩阵中不包含误差。实际上由于模型等因素,系数矩阵中经常存在着误差。为了平差的严密性和精确性,采用一种可以同时顾及观测向量误差和系数矩阵误差的总体最小二乘方法,应用于测量数据处理和坐标转换中,得到更符合实际的平差处理,获得更准确的坐标转换参数。