Glacial paleoceanography off the mouth of the Mekong River, southern South China Sea, during the last 500 ka     

Qianyu Li  Fan Zheng  Muhong Chen  Rong Xiang  Peijun Qiao  Lei Shao  Xinrong Cheng 《Quaternary Research》2010,73(3):563-572

We have analyzed core MD01-2392, ∼ 360 km east of the Mekong River mouth in the South China Sea (SCS). Over the past 500 ka, planktonic foraminiferal oxygen-isotopic values are consistently lighter than northern SCS and open-ocean records by up to 0.5‰, indicating the influence of run-off from the Mekong River during both glacial and interglacial periods. Carbonate content is higher during interglacials; sedimentation rates were higher during glacials. Increased sedimentation rates since 30 ka imply increased run-off during the last glacial maximum and Holocene Period. Contrary to general experience, in which it is classed as a warm species for temperature estimates, the thermocline-dwelling species Pulleniatina obliquiloculata increased its numbers during glacial periods. This implies an estuarine circulation and even brackish-water caps during glacial periods, reinforcing the sense of strong run-off. In an overall decline of warm water, the thermocline shoaled stepwise, with rapid rises across the glacial terminations. We infer that the southern SCS was opened to an influx of Indian Ocean waters through southern passages at those times of rising sea levels.  相似文献   

鄂尔多斯盆地柳林地区下奥陶统冶里组竹叶状石灰岩的沉积环境和成因机制          下载免费PDF全文

王千遥  冯乔  贾凌云  刘阵  赵伟  周书昌 《沉积与特提斯地质》2010,30(4):55-59

鄂尔多斯盆地柳林地区早奥陶世冶里期沉积以浅灰色中薄层泥质白云岩为主,发育大量竹叶状碳酸盐岩。不同类型的竹叶状碎屑反映了不同的沉积环境。笔者对研究区剖面内的竹叶状碎屑进行分析和研究后认为,竹叶状石灰岩的形成可以分为早期沉积物的形成和早期沉积物的破碎、搬运和再沉积两个阶段。  相似文献   

FIO-ESM v2.0 CORE2-forced experiment for the CMIP6 Ocean Model Intercomparison Project     

Qi Shu  Zhenya Song  Ying Bao  Xiaodan Yang  Yajuan Song  Xinfang Li  Meng Wei  Fangli Qiao 《海洋学报(英文版)》2022,41(10):22-31

We introduced the Coupled Model Intercomparison Project Phase 6 (CMIP6) Ocean Model Intercomparison Project CORE2-forced (OMIP-1) experiment by using the First Institute of Oceanography Earth System Model version 2.0 (FIO-ESM v2.0), and comprehensively evaluated the simulation results. Unlike other OMIP models, FIO-ESM v2.0 includes a coupled ocean surface wave component model that takes into account non-breaking surface wave-induced vertical mixing in the ocean and effect of surface wave Stokes drift on air-sea momentum and heat fluxes in the climate system. A sub-layer sea surface temperature (SST) diurnal cycle parameterization was also employed to take into account effect of SST diurnal cycle on air-sea heat ?uxes to improve simulations of air-sea interactions. Evaluations show that mean values and long-term trends of significant wave height were adequately reproduced in the FIO-ESM v2.0 OMIP-1 simulations, and there is a reasonable fit between the SST diurnal cycle obtained from in situ observations and that parameterized by FIO-ESM v2.0. Evaluations of model drift, temperature, salinity, mixed layer depth, and the Atlantic Meridional Overturning Circulation show that the model performs well in the FIO-ESM v2.0 OMIP-1 simulation. However, the summer sea ice extent of the Arctic and Antarctic is underestimated.  相似文献   

Light mode and dark mode: Which one is suitable when using public-facing web maps? An experimental evaluation using eye-tracking     

Lige Qiao  Mingguang Wu 《Transactions in GIS》2023,27(2):516-540

Dark maps, which are also called dark modes or dark themes, have gained popularity, but their usability has not been experimentally evaluated. This article presents a user experiment that uses eye-tracking to assess the usability of dark and light maps. Here, two widely used web maps, Google Maps and Gaode Maps, are selected at the street and city scales. Eight map-use tasks are designed and cover four operations (identify, compare, rank, and associate) with space-alone and attributes-in-space distinctions. Four pairs of map-use tasks (light-during-the-day, dark-during-the-day, dark-at-night, and light-at-night) are examined from three aspects: effectiveness, efficiency, and cognitive load. The results provide preliminary evidence that the light-during-the-day performance is generally the best in most cases, followed by the dark-at-night performance; the dark-during-the-day performance is the worst in all cases, followed by the light-at-night performance, which suggests that aligning the map design with the environment (i.e., lighting environment) is critical for better communication. The light-during-the-day performance is the best for space-alone tasks, and the dark-at-night performance is the best for attributes-in-space tasks. Our investigation also indicates that dark maps are far less favored in practice, which suggests that users' preference for using the dark mode of public-facing web maps needs to be shaped. Since light and dark maps are associated with photopic and scotopic vision, respectively, the results indicate the need for future studies on how to leverage scotopic vision to design better dark maps.  相似文献   

降雨径流与洪水淹没模型耦合的应用研究     

沈泽宇  丁永生  孔乔 《地球信息科学学报》2021,23(8):1473-1483

洪水研究包括径流与淹没两种模式。为了探究流域降雨产汇流与淹没情况、提高洪水预报精度,本研究在传统流域水文模型的基础上耦合二维水动力学模型,建立水文-水动力耦合模型。以我国吉林温德河流域为研究实例,模拟了2017年“7·13”洪水在下游口前镇所处子流域洪水淹没过程。首先对基础数据进行预处理,建立HEC-HMS水文模型并进行参数优化后,最终获得流量过程水文结果作为水动力学模型边界条件,之后建立HEC-RAS二维水动力学模型对重要子流域进行淹没模拟。耦合模型计算结果显示,水文模型经多参数优化流量模拟的NSE系数为0.988,水动力计算最大淹没水深达9.3 m相对误差为-5.2%。从泛洪模拟结果来看,子流域上游部分的农田大量被淹,淹没水深范围在0.5~2.0 m,平均流速基本在1 m/s以下。下游口前镇内最大淹没水深接近1 m,水流速度0.2 m/s至1.5 m/s,与实际的淹没情况相吻合。研究表明,所建水文水动力耦合模型模拟计算的结果准确率较高,对具有复杂水文、水力条件的流域的洪水预报具有重要的指导意义。  相似文献   

深圳产业演进规律及空间分布格局   总被引：1，自引：0，他引：1  

章文  吴洪  乔纪纲 《地域研究与开发》2014,(5)

根据1979—2012年深圳企业数据,以ADF方法进行单位根检验,发现企业时序变量为1阶单整序列,继而进行协整检验和Granger检验,结合VAR和VEC模型计量结果,探讨了深圳第二产业和第三产业企业在演进过程中的长期均衡关系、短期因果关系和动态冲击影响,并基于企业区位熵法对产业演进结果的空间表现形态进行了分析,发现深圳产业发展过程中存在协整关系,第三产业企业增长是第二产业企业出现的Granger原因,脉冲响应函数反映两者相互的动态影响,产业协同演进结果空间分布上存在着分异现象。在研究结果的基础上提出相应的政策建议,以期促进城市产业合理演进。  相似文献   

基于价值变化的城乡不动产征收博弈分析研究     

陈龙高  乔小雨  杨小艳  闫军 《地域研究与开发》2014,(6)

不动产征收前后价值变化研究对于不动产征收主体博弈分析具有重要的意义,也为不动产征收补偿价格评估提供了理论支持。主要通过城乡不动产征收前后价值变化以及被征收人利益损害的分析,探讨了不同目的下的中国不动产征收主体博弈模型及行为选择。研究认为:(1)基于预期收益原则的不动产征收价格评估为不动产征收补偿与征收增值收益分配提供了理论依据;(2)基于公共目的性征收分析表明被征收人的权益保护很大程度上依赖于政府的角色定位,基于非公共目的性征收分析表明由于增值利益分配的零和博弈冲突以及政府的惯性强势思维,对现有政策体制不可避免地带来一系列冲突;(3)基于公共目的性划分的不动产征收与国家收购两种类型有利于区别制定不动产征收政策,从而促进土地资源的合理流动与优化配置。  相似文献   

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陈俊华  陈正松  蒋玲霞  吴海波  乔岳强  贾治革 《大地测量与地球动力学》2014,34(3):10-14

?????????????е??о??????????Ms5.1????????????????????????Ρ?????????????????????????????NEE????????????????????????????????????????5~7 km??????????λ????????????????????????о?????ж?,???Ms5.1??????????λ??????????????????????????????????????  相似文献   

渤海莱州湾地区晚更新世以来有孔虫特征反映的古环境变化     

姚菁  于洪军  徐兴永  易亮  陈广泉  苏乔 《海洋学报(英文版)》2014,33(10):10-18

Controlled by climate changes, there were three large-scale transgressions and regressions around the Bohai Sea during the late Quaternary, which were accepted by most geologists. However, a big controversy still exists about the time when the transgressions occurred separately. In order to find out the process of the paleoenvironmental changes around the Bohai Sea in the late Quaternary, the foraminifera assemblages from a new borehole Lz908 in the southern coast of the Laizhou Bay were studied, and then the transgressive strata were indentified. Combined with accelerator mass spectrometry radiocarbon 14C（AMS14C） and optically stimulated luminescence（OSL） ages, the occurrence time of these transgressions were re-determined. The result showed that three major large-scale transgressions occurred separately at the beginning of marine isotopic stage 7（MIS7）, the last interglacial period（MIS5） and the Holocene. In addition, a small-scale transgression occurred in the mid-MIS6, and the corresponding transgressive stratum was deposited. The transgressive deposition of MIS3 was also discovered in this study. However, the characteristics of the foraminifera indicated the environment during this period was colder than that in the MIS5. By comparison with the global sea-level changes, the paleoenvironmental changes around the Bohai Sea in the late Quaternary can be consistent with the global climate changes.  相似文献   

基于卫星高度计的北极海冰厚度变化研究   总被引：5，自引：3，他引：2  

毕海波  黄海军  苏乔  严立文  刘艳霞  徐秀丽 《海洋学报(英文版)》2014,33(11):134-140

A modified algorithm taking into account the first year(FY) and multiyear(MY) ice densities is used to derive a sea ice thickness from freeboard measurements acquired by satellite altimetry ICESat(2003–2008). Estimates agree with various independent in situ measurements within 0.21 m. Both the fall and winter campaigns see a dramatic extent retreat of thicker MY ice that survives at least one summer melting season. There were strong seasonal and interannual variabilities with regard to the mean thickness. Seasonal increases of 0.53 m for FY the ice and 0.29 m for the MY ice between the autumn and the winter ICESat campaigns, roughly 4–5 month separation, were found. Interannually, the significant MY ice thickness declines over the consecutive four ICESat winter campaigns(2005–2008) leads to a pronounced thickness drop of 0.8 m in MY sea ice zones. No clear trend was identified from the averaged thickness of thinner, FY ice that emerges in autumn and winter and melts in summer. Uncertainty estimates for our calculated thickness, caused by the standard deviations of multiple input parameters including freeboard, ice density, snow density, snow depth, show large errors more than 0.5 m in thicker MY ice zones and relatively small standard deviations under 0.5 m elsewhere. Moreover, a sensitivity analysis is implemented to determine the separate impact on the thickness estimate in the dependence of an individual input variable as mentioned above. The results show systematic bias of the estimated ice thickness appears to be mainly caused by the variations of freeboard as well as the ice density whereas the snow density and depth brings about relatively insignificant errors.  相似文献