VIIRS/DNB夜间灯光月度产品插补方法对比——以北京为例     

陈慕琳  蔡红艳 《地理科学进展》2019,38(1):126-138

新一代VIIRS/DNB(Visible Infrared Imaging Radiometer Suite Day/Night Band)夜间灯光数据因其具备更精细的时空分辨率、数据不存在饱和现象、不同年份数据可比性强等优点而迅速代替DMSP/OLS(Defense Meteorological Satellite Program's Operational Linescan System)夜间灯光数据成为新的研究热点。但由于杂散光的污染,VIIRS/DNB夏季数据数值缺失严重,致使数据在空间和时间上不连续,因此,插补缺失数据成为后续应用的前提。鉴于此,论文从插补结果异常值、与参照值对比、计算性能三个方面,系统比较了三次样条插值(样条)、三次Hermite插值(Hermite)、灰色预测模型(GM)、三次指数平滑法(指数)4种插补方法的适用性,以期为插补VIIRS/DNB夜间灯光数据提供方法选择的依据。研究结果表明：①异常值比较方面,Hermite法未出现异常值,另外3种算法仅出现少量异常值(0.02%~1.34%);②与参照值的对比方面,Hermite法与参考值接近程度最高,GM接近程度最低,样条法和指数法介于两者中间;③算法性能比较方面,4种方法都具备计算简单、容易编程的特点,但指数法的算法时长是另外3种方法的10倍以上。因此,综合多方表现,当插补月份前后两侧均有足够长的原始数据时,插补效果好、计算速度快、不会出现过冲现象的Hermite法最适宜,样条法次之;当插补月份仅单侧有足够长的数据时,适宜采用指数法(插补效果好、计算速度较慢)或GM(插补效果偏低、计算速度快)进行插补。  相似文献   

复杂地形景区三维导览图的设计与实现     

吴思锴  李百寿  郭家豪  李雪  张卫平 《北京测绘》2020,(1):38-43

为满足复杂地形景区对三维地图导览的需求,构建更为清晰的三维地图模型,提供良好的三维导览地图设计方案显得尤为重要。为了更好地与卫星影像进行贴合,DEM数据的采样密度要与卫星影像的分辨率一致。本文通过对比当下常用的四种空间插值方法的适用范围与运用特点,设置相关阈值及权重,直观比较了四种插值方法产生的插值结果,选择更适合复杂景区DEM插值的插值方法并对其进行精度提升,以此得到符合精度要求的DEM数据。最后利用相应地区的卫星影像进行地图投影及影像贴图,两种数据结合构建复杂景区的三维地图模型,给游客带来更为精确直观的定位信息和空间要素信息。  相似文献   

Environmental determinants of species turnover of aquatic Heteroptera in freshwater ecosystems of the Western Ghats,India     

《Limnologica》2020

Partitioning beta diversity into its two components of spatial turnover and nestedness is a more robust method for checking spatial variability in biological communities than calculating the total beta diversity alone. The relative contribution of spatial turnover and nestedness has been used to test the effects of climatic, environmental, spatial and temporal variables on community composition. In this study, we tested the effects of environmental factors and microhabitat features on total beta diversity and its spatial turnover and nestedness components using a comprehensive dataset of aquatic Heteroptera collected from four types of permanent freshwater habitats (i.e. streams, ponds, rock tanks and reservoirs) in the Western Ghats of India. We observed that communities in all four types of habitats were predominantly shaped by dissimilarity caused due to spatial turnover (>85 %). Each type of habitat showed the presence of one or more species uniquely associated with it, which might contribute to the turnover between communities. The abiotic environment (climatic factors, topological factors, soil characteristics and microhabitat features) as well as assemblage structure differed significantly between habitat types. Communities in each type of habitat were affected by different environmental factors, such as precipitation and temperature patterns for streams, altitude and rocky substrate for rock tanks, and soil characteristics and the presence of aquatic macrophytes for ponds and reservoirs. Assemblages observed in the four types of permanent habitats are thus compositionally distinct due to species replacements between local communities, which in turn are strongly influenced by environmental variables. Similar to previous studies, our results show that spatial turnover largely measures the same phenomenon as total beta diversity on a regional scale.  相似文献   

多重加密格网内插法坐标转换   总被引：1，自引：0，他引：1  

李旺民  李秀龙  王东阁  马德富  陈文相  刘亚楠 《测绘通报》2020,(10):118-122

我国CGCS2000坐标系启用后，各地均面临着大批量、多类型、多坐标系成果数据坐标转换的需求，而国家大地坐标系、地心坐标系及独立坐标系之间的转换参数属于绝密级别，保密要求高，因此给实际应用带来了困难。顾及与参数法坐标转换成果的一致性及数据的安全要求，本文提出了多重加密格网内插坐标转换方法，研制了适用于多种数据格式的二/三维格网坐标转换软件，并将该算法应用于CORS服务，通过实例验证了该方法的可靠性与实用性。  相似文献   

How do machine learning techniques help in increasing accuracy of landslide susceptibility maps?     

《地学前缘(英文版)》2020,11(3):871-883

Landslides are abundant in mountainous regions.They are responsible for substantial damages and losses in those areas.The A1 Highway,which is an important road in Algeria,was sometimes constructed in mountainous and/or semi-mountainous areas.Previous studies of landslide susceptibility mapping conducted near this road using statistical and expert methods have yielded ordinary results.In this research,we are interested in how do machine learning techniques help in increasing accuracy of landslide susceptibility maps in the vicinity of the A1 Highway corridor.To do this,an important section at Ain Bouziane(NE,Algeria) is chosen as a case study to evaluate the landslide susceptibility using three different machine learning methods,namely,random forest(RF),support vector machine(SVM),and boosted regression tree(BRT).First,an inventory map and nine input factors were prepared for landslide susceptibility mapping(LSM) analyses.The three models were constructed to find the most susceptible areas to this phenomenon.The results were assessed by calculating the receiver operating characteristic(ROC) curve,the standard error(Std.error),and the confidence interval(CI) at 95%.The RF model reached the highest predictive accuracy(AUC=97.2%) comparatively to the other models.The outcomes of this research proved that the obtained machine learning models had the ability to predict future landslide locations in this important road section.In addition,their application gives an improvement of the accuracy of LSMs near the road corridor.The machine learning models may become an important prediction tool that will identify landslide alleviation actions.  相似文献   

基于回声探测监测沉水植物盖度的插值方法研究:以杭州西湖沉水植物盖度监测为例     

彭雪  张璐  黄素珍  蔺庆伟  刘碧云  张义  吴振斌 《湖泊科学》2020,32(2):472-482

沉水植物作为水生态系统的重要组成成分,在水生态系统物质循环和能量流动中发挥着重要作用,其覆盖度和生物量是评价湖泊等浅水水体系统稳定性的关键参数随着高效和无损伤监测的回声探测仪在沉水植物盖度监测中的应用,其精确度算法也受到了越来越多的关注本研究以成功恢复沉水植物的浅水湖泊杭州西湖为研究对象,利用BioSonics便携型回声探测仪——MX采集沉水植物回声样本同时结合人工样方设置,采集与回声探测对应位点的沉水植物样本,验证回声探测结果的精确性通过建立回归模型分析回声探测得到的沉水植物体积百分比(PVI)与人工样方获得的对应平均鲜重关系,结果表明二者具有较好的相关性分别采用普通克里金法、反距离权重法、径向基函数法3种插值方法对同一季节的不同湖泊和同一湖泊的不同季节未采集区域沉水植物的盖度数据进行插值分析,并对插值结果进行交叉验证,以确定方法的精确度交叉验证结果表明,插值精确度反距离权重法径向基函数法普通克里金法研究结果为回声探测与插值分析方法结合在大尺度浅水水体中沉水植物监测应用提供了技术支撑.  相似文献   

新疆和田地区耕地面源污染生态风险评价          下载免费PDF全文

田丰收  刘新平  原伟鹏 《干旱区地理》2019,42(2):295-304

随着化肥、农膜等在农业生产中的过量投入，耕地面源污染的程度随之加重。文章选取塔里木河流域上游和田地区为研究区域，依据P-S-R框架理论，构建和田地区耕地面源污染生态风险评价指标体系，加入土壤理化数据，使用生态风险评价模型对和田地区1980 年及2016 年耕地面源污染状况进行生态风险评价，运用耕地生态风险模型、生态风险转移矩阵、Arcgis分析和田地区耕地面源污染时空分异状况。研究结论如下：和田地区1980 年耕地生态风险等级均为II级或III级，呈“中间高，两侧低”分布；2016 年耕地生态风险等级上升至IV级或V级，呈“倒W型”分布，各县耕地面源污染程度较1980 年均有较大幅度的上升，其中墨玉县和于田县在2016 年耕地生态风险等级达到最高的V级，而民丰县因自身生态环境的强脆弱性，同样需要提高关注。根据面源污染“从源头治理”的原则，应切实推进和田地区耕地生态环境保护与治理，提高政府重视程度，增强技术指导，开展试点工作，改善和田地区耕地面源污染现状。  相似文献   

中国耕地土壤相对湿度时空分异   总被引：4，自引：1，他引：3  

潘汉雄  朱国锋  张昱  郭慧文  雍磊磊  万巧卓  马惠莹  李森 《地理学报》2019,74(1):117-130

以全国653个农业气象站1993-2013年耕地的土壤相对湿度数据为基础,运用地统计方法,分析中国耕地土壤相对湿度时空分异特征与规律。结果表明：自1993年以来全国耕地的土壤相对湿度呈现波动上升趋势。全国耕地的土壤相对湿度普遍大于60%,分布区域自4月中旬开始随夏季风推移不断向北向西扩大,自10月下旬开始向东、南方向缩小。耕地土壤相对湿度值随土壤深度的增加而增加。年际尺度上,耕地的土壤相对湿度在夏秋季上升速度最快,变化幅度随土层深度增加而变小。土壤相对湿度与降水量存在较强的正相关关系,与潜在蒸发量、气温普遍存在较强的负相关关系。土壤相对湿度与各气象要素的相关性随深度加深而减弱。春、夏、秋季气象因素对旱地土壤相对湿度影响较大,冬季气象因素对水田影响更大。  相似文献   

The roles of flowering,overwinter survival and sea surface temperature in the long-term population dynamics of Zostera marina around the Isles of Scilly,UK     

Maria Potouroglou  Emma J. Kenyon  Angie Gall  Kevan J. Cook  James C. Bull 《Marine pollution bulletin》2014

Interaction between biotic and abiotic drivers of dynamics is an important topic in ecology. Despite numerous short-term studies, there is a paucity of evidence about how environmental structure modifies dynamics in marine systems. We quantified Zostera marina flowering and non-flowering shoot density annually from 1996 to 2012 around the Isles of Scilly, UK, parameterizing a population dynamic model. Flowering is structured in time and space, with temperature and flowering positively associated at some locations only. We found no evidence that flower production contributes to seagrass density but ‘patchiness’ was positively associated with flowering in the previous year. With evidence of substantial overwinter survival, findings support the hypothesis that local populations are maintained largely through vegetative reproduction but sexual reproduction may contribute to colonisation of vacant habitat. This long-term study (1) tests validity of shorter-term investigations, (2) quantifies interaction between biotic and abiotic factors and (3) promotes seagrass as a model ecosystem.  相似文献   

Symmetric matrix-valued transmitting boundary formulation in the time-domain for soil–structure interaction problems     

《Soil Dynamics and Earthquake Engineering》2014

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