基于兴趣区域的无参考型影像质量评价研究

针对现阶段无参考型算法主观一致性差的问题,提出了一种基于兴趣区域的无参考型影像质量评价算法(NROI),在德克萨斯大学的Live影像库中与经典算法:峰值信噪比(PSNR)、结构相似度(SSIM)、自然场景统计模型(NIQE)法,进行大量实验对比。结果表明,NROI的表现优于NIQE,PSNR与SSIM相当,适用于数字影像的质量评价。     

岷江上游槽谷曲流段大型古滑坡成因与复活性分析——以松潘县元坝子古滑坡为例

岷江上游靠近分水岭部位的槽谷曲流河段,由于地壳抬升缓慢,河谷宽、岸坡缓,降雨量相对偏少,通常被认为发生大型滑坡的可能性较小。但通过笔者近年来的调查发现,在岷江上游红桥关至西宁关的槽谷曲流段两岸大型滑坡密集发育,且大多具有地震滑坡的特征,同时个别滑坡受后期江水冲刷、工程开挖等因素影响复活。文章选取其中较为典型的元坝子滑坡为例进行解剖,元坝子滑坡位于岷江曲流凹岸,长780 m,宽480 m,体积293×104 m3。通过地质分析、测年鉴定和数值模拟,认为该滑坡是历史地震引发的大型岩质古滑坡,其发展经历了斜坡裂缝、地震滑坡、河流下切和前缘复活等阶段。稳定性计算结果显示,目前滑坡整体天然工况下稳定性好,极端暴雨工况下欠稳定,受江水冲刷、降雨、融雪等因素影响,出现局部变形复活。建议应加强滑坡变形监测,避免整体滑动造成堵江、威胁成兰铁路安全。     

Formation by silicate–fluoride + phosphate melt immiscibility of REE-rich globular segregations within aplite dikes

Aplite dikes intruding the Proterozoic 1.42(±?3) Ga Longs Peak-St. Vrain Silver Plume-type peraluminous granite near Jamestown, Colorado, contain F, P, and rare earth element (REE)-rich globular segregations, with 40–46% REE, 3.7–4.8 wt% P₂O₅, and 5–8 wt% F. A combination of textural features and geochemical data suggest that the aplite and REE-rich globular segregations co-existed as two co-genetic liquids prior to their crystallization, and we propose that they are formed by silicate–fluoride?+?phosphate (+?S?+?CO₂) melt immiscibility following ascent, cooling, and decompression of what was initially a single homogeneous magma that intruded the granite. The REE distribution coefficients between the silica-rich aplites and REE-rich segregations are in good agreement with experimentally determined distribution coefficients for immiscible silicate–fluoride?+?phosphate melts. Although monazite-(Ce) and uraninite U–Th–Pb microprobe ages for the segregations yield 1.420(±?25) and 1.442(±?8) Ga, respectively, thus suggesting a co-genetic relationship with their host granite, ε_Nd1.42Ga values for the granites and related granitic pegmatites range from ??3.3 to ??4.7 (average ??3.9), and differ from the values for both the aplites and REE-rich segregations, which range from ??1.0 to ??2.2 (average ??1.6). Furthermore, the granites and pegmatites have (La/Yb)_N <50 with significant negative Eu anomalies, which contrast with higher (La/Yb)_N >100 and absence of an Eu anomaly in both the aplites and segregations. These data are consistent with the aplite dikes and the REE-rich segregations they contain being co-genetic, but derived from a source different from that of the granite. The higher ε_Nd1.42Ga values for the aplites and REE-rich segregations suggest that the magma from which they separated had a more mafic and deeper, dryer and hotter source in the lower crust or upper mantle compared to the quartzo-feldspathic upper crustal source proposed for the Longs Peak-St. Vrain granite.     

Semantic and syntactic interoperability in online processing of big Earth observation data

ABSTRACT

The challenge of enabling syntactic and semantic interoperability for comprehensive and reproducible online processing of big Earth observation (EO) data is still unsolved. Supporting both types of interoperability is one of the requirements to efficiently extract valuable information from the large amount of available multi-temporal gridded data sets. The proposed system wraps world models, (semantic interoperability) into OGC Web Processing Services (syntactic interoperability) for semantic online analyses. World models describe spatio-temporal entities and their relationships in a formal way. The proposed system serves as enabler for (1) technical interoperability using a standardised interface to be used by all types of clients and (2) allowing experts from different domains to develop complex analyses together as collaborative effort. Users are connecting the world models online to the data, which are maintained in a centralised storage as 3D spatio-temporal data cubes. It allows also non-experts to extract valuable information from EO data because data management, low-level interactions or specific software issues can be ignored. We discuss the concept of the proposed system, provide a technical implementation example and describe three use cases for extracting changes from EO images and demonstrate the usability also for non-EO, gridded, multi-temporal data sets (CORINE land cover).     

塔里木盆地顺北地区11号走滑断裂带变形及其活动特征

塔里木盆地顺北地区发育大量走滑断裂带,并对油气的运聚成藏有重要控制作用。以顺北西部地区地震资料为基础,对顺北11号走滑断裂带的几何变形特征、活动性、活动期次及其形成机制等进行了分析。顺北11号走滑断裂带整体呈NNW走向延伸,具有垂向分层性和平面分段性。断裂带北段主体为压扭和张扭交互段,中段为两条次级断层控制的拉分地堑,南段由数条分支断层构成马尾状构造。顺北11号断裂带整体活动性由北向南减弱,运动学标志显示是一条右旋走滑断层。顺北11号断裂带主要经历了晚奥陶世和晚志留世-中泥盆世两期活动,部分地区的活动持续到石炭纪。顺北11号走滑断裂带的活动性和运动学特征与塔北地区NNW走向的走滑断裂体系比较相似,而不同于塔中地区的NE向左行走滑断裂体系。顺北11号走滑断裂带的形成主要受控于塔里木盆地北部天山洋多期俯冲挤压而产生的自北向南的挤压应力,断裂自北向南扩展延伸,类似于顺北5号走滑断裂带的北段。     

基于ERA5的快速辐射传输模式与FY-4A成像仪观测结果的偏差分析

2016年12月发射升空的FY-4A是中国第二代静止轨道气象卫星,该星上搭载了可提供东半球近实时高分辨率卫星观测数据的扫描辐射成像仪——AGRI（Advanced Geostationary Radiation Imager）。在其观测数据应用于大气参数反演或同化前,数据偏差的定量化分析是一个必要环节。采用快速辐射传输模式RTTOV（Radiative Transfer for the TIROS Operational Vertical Sounder）,基于欧洲中期天气预报中心（ECMWF）第5个全球再分析数据产品（ERA5）对AGRI的7个红外通道（通道08—14）进行了模拟,并利用MODIS云检测产品对模拟结果进行了晴空筛选,以期得到一些对AGRI的定量应用有价值的偏差分析结果。观测-模拟（O-B）的偏差分析结果显示:海洋和陆地上,通道10（7.1 μm）存在明显大于其他红外通道的系统性偏差,这很可能来源于ERA5在对流层中层对水汽的高估。通道08为近红外短波通道,地表反射作用影响强烈,陆地上存在较大的平均偏差,而海洋上平均偏差小于0.4 K。通道14在ERA5近地层气温偏高及定标偏差的影响下,海洋存在接近1 K的平均偏差;陆地上存在2 K左右的平均偏差。其余各红外通道在海洋和陆地上的平均偏差分别在0.6和1.3 K以下。偏差影响因子分析结果显示:地表海拔高度、观测天顶角对偏差也存在一定程度的影响;海洋上偏差分布存在季节变化可能来源于再分析资料中海表温度估算的季节性误差。