Long-term trend analysis of wave characteristics in the Bohai Sea based on interpolated ERA5 wave reanalysis from 1950 to 2020     

Jichao Wang  Peidong Sun  Zhihong Liao  Fan Bi  Guiyan Liu 《海洋学报(英文版)》2022,41(7):97-112

Reasonably understanding of the long-term wave characteristics is very crucial for the ocean engineering. A feedforward neural network is operated for interpolating ERA5 wave reanalysis in this study, which embodies a detailed record from 1950 onwards. The spatiotemporal variability of wave parameters in the Bohai Sea, especially the significant wave height (SWH), is presented in terms of combined wave, wind wave and swell by employing the 71 years (1950–2020) of interpolated ERA5 reanalysis. Annual mean SWH decreases at ?0.12 cm/a estimated by Theil-Sen estimator and 95th percentile SWH reflecting serve sea states decreases at ?0.20 cm/a. Inter-seasonal analysis shows SWH of wind wave has steeper decreasing trend with higher slopes than that of swell, especially in summer and winter, showing the major decrease may attribute to the weakening of monsoon. The inner Bohai Sea reveals a general decreasing trend while the intersection connecting with the Yellow Sea has the lower significance derived by Mann-Kendall test. Meanwhile, 95th percentile SWH decreases at a higher rate while with a lower significance in comparison with the mean state. The frequencies of mean wave directions in sub-sector are statistically calculated to find the seasonal prevailing directions. Generally, the dominant directions in summer and winter are south and north. A similar variation concerning to SWH, the trend of the mean wave period is provided, which also shows a decrease for decades.  相似文献   

Traj2Traj: A road network constrained spatiotemporal interpolation model for traffic trajectory restoration     

Lyuchao Liao  Yuyuan Lin  Weifeng Li  Fumin Zou  Linsen Luo 《Transactions in GIS》2023,27(4):1021-1042

In transportation, the trajectory data generated by various mobile vehicles equipped with GPS modules are essential for traffic information mining. However, collecting trajectory data is susceptible to various factors, resulting in the lack and even error of the data. Missing trajectory data could not correctly reflect the actual situation and also affect the subsequent research work related to the trajectory. Although increasing efforts are paid to restore missing trajectory data, it still faces many challenges: (1) the difficulty of data restoration because traffic trajectories are unstructured spatiotemporal data and show complex patterns; and (2) the difficulty of improving trajectory restoration efficiency because traditional trajectory interpolation is computationally arduous. To address these issues, a novel road network constrained spatiotemporal interpolation model, namely Traj2Traj, is proposed in this work to restore the missing traffic trajectory data. The model is constructed with a seq2seq network and integrates a potential factor module to extend environmental factors. Significantly, the model uses a spatiotemporal attention mechanism with the road network constraint to mine the latent information in time and space dimensions from massive trajectory data. The Traj2Traj model completes the road-level restoration according to the entire trajectory information. We present the first attempt to omit the map-matching task when the trajectory is restored to solve the time-consuming problem of map matching. Extensive experiments conducted on the provincial vehicle GPS data sets from April 2018 to June 2018 provided by the Fujian Provincial Department of Transportation show that the Traj2Traj model outperforms the state-of-the-art models.  相似文献   

柴达木盆地西南缘新月形沙丘移动特征及其影响因素     

邹桐  杨转玲  韦锦芝  廖应英  邢学刚  钱广强  梁晓磊 《中国沙漠》2023,43(1):212-221

柴达木盆地西南缘新月形沙丘连片分布、数量丰富、大小各异、形态多样,是开展沙丘动态演化研究的理想区域。基于2013年和2021年两期高分一号卫星影像和气象资料,分析了柴达木盆地西南缘沙丘区537个新月形沙丘移动、形态和区域风况特征,探讨了沙丘移动的影响因素。结果表明：(1)该区域新月形沙丘移动速率1.43～22.37 m·a^-1,平均移动速率7.23 m·a^-1,沙丘移动方向109.22°～171.28°,平均移动方向142.86°,整体呈NW-SE方向移动。(2)受低风能环境和西北偏西风的影响,该区域新月形沙丘移动速率相对其他沙漠较慢,移动方向与盛行风向基本一致。(3)受沙丘尺度的影响,该区域新月形沙丘越大,移动越慢,呈幂函数递减的关系。(4)该区域新月形沙丘分布密度、植被状况、地形起伏等在一定程度上影响沙丘移动速率。  相似文献   

Interactive generalization on large-scale topographical map supported by a database platform     

Cai Zhongliang  Wu Hehal  Du Qingyun  Liao Chujiang 《地球空间信息科学学报》2013,16(4):17-26

This paper makes a study on the interactive digital generalization, where map generalization can be divided into intellective reasoning procedure and operational procedure, which are done by human and computer, respectively. And an interactive map generalization environment for large scale topographic map is then designed and realized. This research focuses on: ¹ the significance of researching an interactive map generalization environment, ² the features of large scale topographic map and interactive map generalization, ³ the construction of map generalization-oriented database platform.  相似文献   

NOSQL技术在档案检索中的应用探索     

付世娇  吴传  廖小莉 《国土资源信息化》2013,(4):69-72

随着国土房管数据量的递增,用户对检索性能的要求越来越高,本文将非关系型数据库引入档案检索中,利用它来提高系统的搜索性能。文章首先介绍基于传统关系型数据库的应用现状及其逐渐呈现出来的问题,然后阐述NOSQL技术在档案检索中体现出来的意义,最后通过与关系型数据库在检索性能上的实验对比,来检验NOSQL技术在档案检索应用中的优良性能。  相似文献   

Geographical Detectors‐Based Health Risk Assessment and its Application in the Neural Tube Defects Study of the Heshun Region,China     

Jin‐Feng Wang  Xin‐Hu Li  George Christakos  Yi‐Lan Liao  Tin Zhang  Xue Gu 《International journal of geographical information science》2013,27(1):107-127

Physical environment, man‐made pollution, nutrition and their mutual interactions can be major causes of human diseases. These disease determinants have distinct spatial distributions across geographical units, so that their adequate study involves the investigation of the associated geographical strata. We propose four geographical detectors based on spatial variation analysis of the geographical strata to assess the environmental risks of health: the risk detector indicates where the risk areas are; the factor detector identifies factors that are responsible for the risk; the ecological detector discloses relative importance between the factors; and the interaction detector reveals whether the risk factors interact or lead to disease independently. In a real‐world study, the primary physical environment (watershed, lithozone and soil) was found to strongly control the neural tube defects (NTD) occurrences in the Heshun region (China). Basic nutrition (food) was found to be more important than man‐made pollution (chemical fertilizer) in the control of the spatial NTD pattern. Ancient materials released from geological faults and subsequently spread along slopes dramatically increase the NTD risk. These findings constitute valuable input to disease intervention strategies in the region of interest.  相似文献   

A study on the hydro-geologic factors that affect streamflow depletion     

Bing-Dong Li  Prasanna V Sampath  Huasheng Liao 《水文科学杂志》2013,58(11):2133-2143

ABSTRACT

Evaluation of streamflow depletion induced by groundwater pumping is important for watershed management. Many analytical and numerical solutions exist for estimating depletion for various hydro-geologic scenarios. Numerical models are time consuming and require significant data input, and moreover, are problem-specific. Analytical models are convenient because of their ease of use, minimum data requirements, and instantaneous solutions, but are only applicable for idealistic scenarios. In many cases, analytical models are used for decision making on water-withdrawal permits, because they are assumed to offer conservative estimates of depletion. However, a systematic study of the applicability of these analytical models has not been done. In this research, we critically evaluate the performance of the analytical models in complex hydro-geologic settings, and list the factors that most significantly impact depletions. On the basis of this study, we find that the analytical models perform satisfactorily as a screening-level tool, though there are some situations when they perform poorly. The factors that most significantly impact streamflow depletion are spatial variability in hydraulic conductivity and the presence of other sources of water, such as lakes and wetlands. The analytical models do make conservative predictions of streamflow depletion especially for the most vulnerable streams.