国产资源三号测绘卫星DSM数据质量评价--以高海拔山区为例

为了评价国产资源三号测绘卫星DSM数据精度,在顾及地貌类型的情况下,以涵盖平原、台地、丘陵等地貌的高海拔山区为研究案例,并以1∶1万实测地形图DEM为假定真值,以90m分辨率SRTM DEM为评价参照,从高程精度和地形描述精度两个方面,对15m分辨率ZY-3DSM进行精度评价分析。研究结果表明:ZY-3DSM高程精度优于SRTM DEM,前者高程中误差仅为后者的1/6;就地形描述精度来讲,ZY-3DSM与SRTM DEM相比,其地形描述精度更接近理论值,前者RMS Et实际值仅为理论值0.99倍,而后者的实际值却是理论值5.13倍。由此看来,ZY-3DSM数据精度整体上高于SRTM DEM。     

气象卫星发展回顾与展望

回顾了国际气象卫星和中国风云气象卫星的发展,综述了气象卫星在图像解译、定量产品应用和数据同化方面的成就以及辐射校正技术的进步。围绕大气科学,特别是数值天气预报对天基观测的需求,展望了未来气象卫星的技术发展方向。     

利用广播星历确定BDS卫星飞行区域

针对北斗卫星导航系统(BDS)采用异构星座,其GEO、IGSO卫星飞行区域并非全球覆盖,传统监测站覆盖性能分析方法不宜直接应用以及导航卫星在轨运行时受到多种摄动影响,其实际运行区域与设计区域有别等问题,提出采用实测数据界定BDS导航卫星飞行区域的方法,并以BDS试验评估系统国内跟踪站网及GPS/BDS测试评估系统跟踪站网为例,分析了监测网的覆盖性能。实验证明本文提出的方法可较为合理、能够较准确地描述BDS地面跟踪站网的监测覆盖性能。     

高分一号多光谱影像正射精度验证与分析

为了验证和分析高分一号卫星影像的正射精度,填补相关研究的空白,该文采用有理函数模型对高分一号卫星PMS传感器多光谱影像进行正射校正,采集检查点检验多光谱影像的几何正射精度。实验结果表明,高分一号卫星PMS相机多光谱影像正射精度能够满足1:25 000比例尺地形图的更新要求,为相关研究提供参考。     

Episodic Events: Their Relevance to Ecology and Evolution

Abstract. An episodic event can be one of the many "episodes" forming a normal flow of related events. But it can also be an "incident" interrupting a trend and initiating a new one. Appreciation of contrasting meanings of apparently identical categories of phenomena is familiar to evolutionary biologists who, for instance, envisage evolution as the result of both gradual and punctuated events. Seasonal plankton blooms (both normal and noxious), species outbreaks, mass mortalities, and human predation are taken as examples of "episodes" that can influence and/or modify what we perceive as "normality". Recruitment is another example of an episodic event heavily conditioning both community structure and function, as recently highlighted by the so-called supply-side ecology. The reductionistic study of ecology. more linked to thermodynamics than to history, allowed the formulation of general ecological laws which, however, stem from the laws of thermodynamics. The totalizing value of such laws blurs appreciation of heterogeneity and change, so that many ecologists tend to be rather conservative, using a concept like "conservation" as an absolute paradigm to follow and to consider "change" as an a priori negative phenomenon. Episodes can have a "conservative" or "innovative" meaning, and are the driving force of the history of life. Their importance is recognized mainly when dealing with the history of organisms (evolutionary biology), whereas the assemblages of organisms ( i.e ., communities) are too often described and interpreted in an ahistorical context or in a too narrow time frame. Recognition of the importance of history in ecology (evolutionary ecology) can lead to a better understanding of environmental dynamics, albeit restricting the supposed predictive strength of ecology, a science timely integrating the reductionistic-thermodynamic approach with the holistic-historical one.     

Quantification of the Total Suspended Matter Concentration around the Sea Breaking Zone from In Situ Measurements and Terra/Aster Data

Remote sensing techniques can be used to quantify the total suspended matter concentration (TSM). The main objective of this study is the quantification of the TSM concentration around the sea breaking zone for a particular area of the Portuguese coast, near Aveiro city. The methodology used was based on in situ measurements and on multispectral satellite image from TERRA/ASTER. In situ experimental techniques were used to determine a relationship between the TSM concentration and the seawater reflectance. Empirical relationships were established between TSM concentration and the equivalent reflectance values for TERRA/ASTER at visible and near infrared bands computed from the experimental data. The reflectance values had a very high correlation with the TSM concentration in the wavelength between 500 and 900 nm. The ASTER image was calibrated, atmospherically and geometric corrected. Equations of linear, polynomial, logarithmic, power and exponential models were applied. The best results were found with the linear and polynomial models, with a determination factor higher than 0.95. However, the differences in the TSM concentration calculated for the three bands indicate that we should not use the information of a single band to obtain the TSM concentration.     

青岛市城区演化及发展的卫星遥感分析

通过对1988、1997和2002年3个时相的Landsat卫星遥感数据分析，获得适合青岛市城区发展研究的遥感波段组合，获得了青岛近20多年来城区扩展的总体信息。从3个时相遥感影像的对比结果可以看出，1988年到1997年期间青岛市城区扩展较为显著，市南、市北、四方、李沧和崂山5区面积从89．5km^2发展到169．5km^2，1997年以后仅崂山区西部有小面积扩展。城阳和黄岛区的变化较大，1988年到1997年间分别以大约14倍和15倍的速度增长，1997年到2002年城阳城区面积从38．1km^2扩展到50．3km^2，黄岛城区面积翻番。从自然条件的角度来看，青岛市东部多山地发展空间小，城阳区大部分处于海拔100m以下，而城区面积不到总面积的1／6，黄岛区也存在近3倍于现今的城区面积的发展空间。可以看出在环胶州湾的发展带上，城区扩展存在着明显的不平衡现象，今后我们应该改善导致这种不平衡发展的因素，加强胶州湾沿岸交通网的建设，将下一步的发展重点放在胶州湾北岸、西南岸以及崂山东北部低地区域的建设上。