Sediment transport in the Luanhe River delta: grain size trend analysis

Sediment grain size in the deltaic environment of the Luanhe River(LR), Liaoning, China,contains sediment transport pathway information useful in elucidating the shoreline change and fluvialmarine interaction. In this study, we utilized numerical partitioning of the sedimentary components and geostatistical grain size trend analysis(GSTA) to define the sediment transport pattern in the Luanhe River delta(LRD) and interpolated the sediment transport pattern using content changes of end numbers(EM).EM1(the mean grain size 7.12 Φ, fine silt), EM2(2.37 Φ, fine sand), and EM3(1.27 Φ, medium sand)components were identified by the numerical partitioning by GSTA. Kriging interpolation method was used to interpolate the parameters of the grain size for the regular grid, and the interpolation radius was 0.015 decimal degree. We chose 0.09 decimal degree as the characteristic distance for GSTA in the semivariogram model using the geostatistical method. The FB(-) case(finer, better sorted and more negatively skewed) was adopted in GSTA for its satisfaction in the Global Moran's I test. The result of the GSTA shows that the sediments in the south barriers(SBs) were transported to the southwest of the study area. The sediments in the north, in the SE direction of sediment transport trend from the river mouth, indicated that the sediments in the north of the study area were transported from the LR to the northern beaches, and to the south and east of the study area. The sediment transport trend that simplified by GSTA as the FB(-) case was approved by the content changes of sedimentary components(i.e. EM1, EM2, and EM3). In addition, the turbulent jet diffusion pattern indicated that the coarse sediments(EM3) were delivered by LR during the flood season, and the EM2 and EM1 were from wave and tide, respectively.     

现代黄河三角洲钓口叶瓣体沉积相及其沉积动力环境特征

The Huanghe River captures the Diaokou River in 1964 and forms a deltaic lobe in the subsequent 12 a. The progradational process of the Diaokou lobe is in associated with complicated evolution of riverine sheet flooding,merging, and swinging. On the basis of 11 borehole cores and 210 km high resolution seismic reflection data set,the sedimentary sequence and dynamic environment of the Diaokou lobe(one subdelta lobe of the modern Huanghe River Delta) are studied. The stratigraphy of the lobe is characterized by an upward-coarsening ternary structure and forms a progradational deltaic clinoform. Totally six seismic surfaces are identifiable in seismic profiles, bounded six seismic units(SUs). These SUs correspond to six depositional units(DUs) in the borehole cores, and among them, SUs 4–6(DUs D to F) consist of the modern Diaokou lobe. Lithological and seismic evidences indicate that the delta plain part of the Diaokou lobe is comprised primarily by fluvial lag sediments together with sediments from sidebanks, overbanks, fluvial flood plains and levees, while the delta front part is a combination of river mouth bar sands(majority) and distal bar and deltaic margin sediments(minority). As a result of the high sedimentation rate and weak hydrodynamic regime in the Huanghe River Delta, the sediments in the delta front are dominated by fine-grained materials. The grain size analysis indicates the Huanghe River hyperpycnal-concentrated flow shows the suspension, transportation and sedimentation characteristics of gravity flow, and the sediment transportation is primarily dominated by graded suspension, while uniform suspension and hydrostatic suspension are also observed in places. The strength of the hydrodynamic regime weakens gradually offshore from riverbed, river mouth bar, sidebank, distal bar subfacies to delta lateral margin and flooding plain subfacies.     

OSMAR-S型高频地波雷达在南海北部遥测海表面流的数据检验

为掌握OSMAR-S型高频地波雷达在南海北部遥测海表面流的误差分布情况,首先分析该型雷达测流的空间分布情况,发现在雷达连线中间区域存在盲区。将雷达测流数据与ADCP测流数据进行比对,中间区域流速误差小于其他区域。为得到更为全面的分析,对雷达测流数据进行潮流调和分析,计算得到潮流和余流,并分别与预报系统的潮流数据、气象站风场数据进行比对,在计算中采用快速Fourier变换进行数据滤波处理。结果显示在雷达电磁波覆盖的向外海一侧中间区域,特别是在与两雷达站夹角接近90°的区域,测流精度高于其他区域,并基于以上结论给出了雷达使用中的建议。     

水稻光敏核不育系的育性气象模型及其机理

光敏核不育水稻的育性转换主要是抽穗前５￣２０天的光温条件综合影响的结果。其数量关系可由结实率量化模型表达。温敏型不育系的育性由温度主控；光敏型不育系的育性在日长大于最适日长时由日长主控，日长短于最适日长时由温度主控。温光对育性的影响存在互补效应，在最适温度以下，不育临界日长随温度升高延长；在最适温度以上，不育临界日长随温度升高缩短。温光当量可作为比较温度和日长对育性影响大小的具体量值。根据结实率量     

FY-3C VIRR大气可降水产品生成和检验

风云三号C星(FY-3C)可见光红外扫描辐射计(VIRR)两个红外分裂窗通道数据生成的晴空大气可降水(TPW)产品已投入业务使用。本文介绍了该产品的生成方法,并从产品精度和稳定性两个方面评价产品质量。与MODIS Terra TPW的月平均数据对比,FY-3C VIRR TPW能正确反应大气可降水的全球分布。与2015年3月—4月的全球探空数据对比,FY-3C VIRR TPW均方根误差为5.36 mm,相对误差在水汽值大于30 mm时在20%以内,并且夜间产品精度优于白天。相比于MODIS红外TPW产品与探空数据的误差,FY-3C TPW精度略好。计算2015年1月至2016年7月FY-3C VIRR TPW产品相对探空数据的月均方根误差,19个月均方根误差的标准差是0.54 mm,小于同期MODIS Terra TPW均方根误差的标准差,说明FY-3C VIRR TPW产品在检验时期内更稳定。FY-3C VIRR TPW产品精度较高且质量稳定,具备广泛应用能力。     

Spatio-temporal variations in ecological spaces and their ecological carrying status in China’s mega-urban agglomerations

Journal of Geographical Sciences - The rapid expansion of China’s urban agglomerations in recent decades has resulted in over-occupied ecological spaces and increased ecological pressure that...     

伊洛河流域土地利用/覆被变化格局分析

科学认识流域土地利用变化及其特征可以为流域水文变化、水环境变化、气候变化等研究提供基础。以1970—2010年伊洛河流域5期遥感影像数据为基础,利用GIS信息技术与空间分析技术,得到不同时期伊洛河流域土地利用/覆被特征,选取土地利用变化率指数、土地利用综合指数和土地利用动态度模型3个指标,分析了近40a来研究区的土地利用/覆被变化特征。结果表明,伊洛河流域土地利用以耕地为主,其次为林地。研究区土地利用处于发展期且土地利用变化处于快速变化水平,随着城镇化面积的逐年增加,流域耕地面积从1990年以后逐年减少,城镇工矿居民用地不断增加,其他如林地、草地和未利用面积变化基本保持不变。从不同的发展阶段来看,1970—1990年间,土地利用/覆被变化不太显著;1990—2000年流域土地利用变化以城镇工矿居民用地增加为主要特征;2000—2005年流域土地利用变化以耕地减少为主要特征;2005—2010年土地利用变化程度较2000—2005年有减缓趋势,但仍然呈现耕地减少、城镇工矿居民用地增加的特征。从不同的高程带来看,洼地和丘陵地带土地变化较剧烈,变化的主要特征为耕地减少、城镇工矿居民用地增加,而中山和高山地带,因为人类活动影响较小,土地利用情况变化很小。     

风云气象卫星“一带一路”热带气旋监测能力与最新进展

面向风云卫星服务“一带一路”倡议,我国风云气象卫星在轨运行的静止和极轨两个系列6颗卫星,已经联合组成了服务“一带一路”星座布局,建立了风云卫星应急减灾数据服务机制。本文对利用FY-2H、FY-4A和FY-3C/D开展的“一带一路”热带气旋监测方法以及最新进展进行了概述,列举了2018年和2019年影响力较大的连续致灾热带气旋、跨海域热带气旋,以及双/三/四个热带气旋共存的典型个例。结果显示在基于风云卫星开展的“一带一路”热带气旋监测业务中,将热带气旋发生演变的原理与气象卫星不同仪器观测原理相结合,在热带气旋生命史不同阶段根据所关注的不同侧重点,分别对应应用风云气象卫星不同观测仪器,对于热带气旋全生命史监测预报有重要意义。     

FY-3A陆表温度反演及高温天气过程动态监测

采用FY-3A/VIRR数据,利用Becker局地分裂窗改进算法反演得到逐日陆表温度 (LST), 对2009年一次高温天气过程进行动态监测, 并分析不同下垫面的热环境变化。结果显示:此过程中可见光红外扫描辐射计 (VIRR) 陆表温度产品在敦煌辐射校正场地两次验证的误差为-0.17 K和1.77 K,与同时间过境的MODIS产品均方根误差为2.64 K,直方图对比陆表温度的频数分布基本一致;对高温天气过程监测发现,此次出现以华北的石家庄、郑州、北京等地和西北地区东部的西安等地为中心的两个陆表温度高值区, 部分地区达到了320.2 K以上;城市剖面资料证实城市热岛现象存在,并发现工矿用地的热岛效应不容忽视,主要是大面积的工矿用地周围植被破坏严重,地表增温更为显著。