CALIOP对一次秸秆焚烧后气溶胶光学特性的探测分析

采用星载激光雷达(Cloud - Aerosol LIdar with Orthogonal Polarization,CALIOP)资料研究了2008年6月2日华东秸秆焚烧排放气溶胶的光学特性,并与2006～2008年统计结果进行了对比.结果表明:1)CALIOP能够有效探测到气溶胶层,探测结果符合生物质燃烧气溶胶的...     

GPS控制网起算点精度的检核方法

结合实际经验,阐述了起算点精度对GPS控制网兼容的重要性,介绍了几种检核起算点精度的有效方法。     

探析土地整理的问题及对策

土地作为生产和生活的载体,因其自然和社会属性成为经济增长和社会进步的支撑和支持条件,土地整理对土地资源的合理配置和可持续利用有重要意义。从土地整理的现状和存在的问题出发,通过分析产生诸多问题的原因,提出解决土地整理过程中出现的诸如权属调整等问题的对策,以及作出一些有益的探索。     

基于数字正射影像的影像匹配更新及精度探讨

探讨了以已有数字正射影像成果为像片控制基础,与新的航空影像/卫星影像自动配准、匹配、区域网平差,获取像片控制点及纠正点成果,结合已有数字高程模型进行影像纠正,快速生成新的数字正射影像的技术方法,并对无野外控制条件下不同分辨率的影像所能达到的精度进行了验证分析。     

基于色貌效应预测的HDR图像显示研究

在基于iCAM的HDR图像显示过程中加入亨特效应和史蒂文斯效应的预测模型。针对不同的评价目的(图像偏好性和场景再现准确性评价),通过实验确定了亨特效应和史蒂文斯效应预测模型中调制参数c和m的最佳取值,并将最终得到的两个完整的预测模型用于算法流程中。通过图像偏好性实验和场景再现准确性实验发现,改进后算法在图像偏好性上优于商业软件PhotoShop CS4中的4种算法和改进前的iCAM算法;在场景再现准确性上优于改进前的iCAM算法,并与PhotoShop的算法相当;最后通过离散快速傅立叶变换和降采样技术,提高了算法的计算速度。     

GPS拟合高程在山地1:10000像控测量中的应用

介绍了测量中常用的高程系统概念,GPS高程拟合的方法和适用范围,通过实例分析和探讨在高程异常变化剧烈的地区GPS拟合高程满足1:10 000像控测量精度要求的一些方法.     

Evolution of a bifurcation in a meandering river with adjustable channel widths,Rhine delta apex,The Netherlands

Rivers may dramatically change course on a fluvial plain. Such an avulsion temporarily leads to two active channels connected at a bifurcation. Here we study the effect of dynamic meandering at the bifurcation and the effect of channel width adjustment to changing discharge in both downstream branches on the evolution of a bifurcation and coexisting channels. As an example, we reconstructed the last major avulsion at the Rhine delta apex. We combined historical and geological data to reconstruct a slowly developing avulsion process spanning 2000 years and involving channel width adjustment and meandering at the bifurcation. Based on earlier idealised models, we developed a one‐dimensional model for long‐term morphodynamic prediction of upstream channel and bifurcates connected at the bifurcation node. The model predicts flow and sediment partitioning at the node, including the effect of migrating meanders at the bifurcation and channel width adjustment. Bifurcate channel width adaptation to changing discharge partitioning dramatically slows the pacing of bifurcation evolution because the sediment balance for width adjustment and bed evolution are coupled. The model further shows that meandering at the bifurcation modulates channel abandonment or enlargement periodically. This explains hitherto unrecognised reactivation signals in the sedimentary record of the studied bifurcation meander belts, newly identified in our geological reconstruction. Historical maps show that bifurcation migration due to meander bend dynamics increases the bifurcation angle, which increases the rate of closure of one bifurcate. The combination of model and reconstruction identifies the relevant timescales for bifurcation evolution and avulsion duration. These are the time required to fill one downstream channel over one backwater length, the time to translate one meander wavelength downstream and, for strong river banks, the adaptation timescale to adjust channel width. The findings have relevance for all avulsions where channel width can adjust to changing discharge and where meandering occurs. Copyright © 2011 John Wiley & Sons, Ltd.     

http://www.sciencedirect.com/science/article/pii/S1674987112001302

We present relative sea level （RSL） curves in Antarctica derived from glacial isostatic adjustment （GIA）predictions based on the melting scenarios of the Antarctic ice sheet since the Last Glacial Maximum （LGM）given in previous works.Simultaneously,Holocene-age RSL observations obtained at the raised beaches along the coast of Antarctica are shown to be in agreement with the GIA predictions.The differences from previously published ice-loading models regarding the spatial distribution and total mass change of the melted ice are significant.These models were also derived from GIA modelling; the variations can be attributed to the lack of geological and geographical evidence regarding the history of crustal movement due to ice sheet evolution.Next,we summarise the previously published ice load models and demonstrate the RSL curves based on combinations of different ice and earth models.The RSL curves calculated by GIA models indicate that the model dependence of both the ice and earth models is significantly large at several sites where RSL observations were obtained.In particular,GIA predictions based on the thin lithospheric thickness show the spatial distributions that are dependent on the melted ice thickness at each sites.These characteristics result from the short-wavelength deformation of the Earth.However,our predictions strongly suggest that it is possible to find the average ice model despite the use of the different models of lithospheric thickness.By sea level and crustal movement observations,we can deduce the geometry of the post-LGM ice sheets in detail and remove the GIA contribution from the crustal deformation and gravity change observed by space geodetic techniques,such as GPS and GRACE,for the estimation of the Antarctic ice mass change associated with recent global warming.     

High resolution oxygen isotope and grayscale records of a medieval fossil giant clam (Tridacna gigas) in the South China Sea：physiological and paleoclimatic implications

Mollusks are well known for their detailed recording of paleoenvironmental and paleoclimatic changes in their carbonate shells. In this study, we constructed 18-year blue color intensity and oxygen isotope profiles of a 14 C dated(AD 990±40) fossil giant clam, Tridacna gigas, from Shidao Island, South China Sea. The δ18O profile of the T. gigas specimen displayed regular annual cycles and was probably controlled by seasonal variations of the climatic parameters. The blue color intensity profile showed good agreement with the δ18O series, and both had 18 clear annual cycles in accordance with the 18 visually identified annual growth bands. The annual shell growth rate determined from the blue color intensity and oxygen isotope profiles indicated that the annual shell increment of the Tridacna specimen was stable after the onset of sexual maturity. Spectral analysis of the δ18O and blue color intensity time series suggested that the El Nio–Southern Oscillation(ENSO) period observed in the instrumental temperature and precipitation records of the South China Sea during the past 50 years also existed in medieval times. Our results showed that fossil giant clams could provide a good archive of historical intra-seasonal to decadal climate variations.     

Phytoplankton community characteristics in the coastal waters of the southeastern Arabian Sea

Remote sensing applications are important in the fisheries sector and efforts were on to improve the predictions of potential fishing zones using ocean color. The present study was aimed to investigate the phytoplankton dynamics and their absorption properties in the coastal waters of the southeastern Arabian Sea in different seasons during the year 2010 to 2011. The region exhibited 73 genera of phytoplankton from 19 orders and 41 families. The numerical abundance of phytoplankton varied from 14.235×103 to 55.075×106 cells/L. Centric diatoms dominated in the region and the largest family identified was Thalassiosiraceae with main genera as Skeletonema spp., Planktionella spp. and Thalassiosira spp. Annual variations in abundance of phytoplankton showed a typical one-peak cycle, with the highest recorded during premonsoon season and the lowest during monsoon season. The species diversity index of phytoplankton exhibited low diversity during monsoon season. Phytoplankton with pigments Chlorophyll a, Chlorophyll b, Chlorophyll c, peridinin, diadinoxanthin, fucoxanthin, β-carotene and phycoerythrobilin dominated in these waters. The knowledge on phytoplankton dynamics in coastal waters of the southeastern Arabian Sea forms a key parameter in bio-optical models of pigments and productivity and for the interpretation of remotely sensed ocean color data.