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

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.     

Pinpointing source of Mekong and measuring its length through analysis of satellite imagery and field investigations

For centuries, explorers and scientists from different countries had made their own conclusions on the source of the Mekong. However, the geographic source of the Mekong is still arguable because of the complexity of the Mekong source water system, inaccessible environment and the varied technologies used by those explorers and scientists. The satellite remote sensing technology has been used to pinpoint the source of the Mekong, associated with the on-the-spot investigations made by the authors in June 1999 and September 2002. The actual length of the Mekong has also been calculated.     

无锡着装气象指数研究

本文统计分析了无锡市温、湿、风的变化规律，并探讨其对着装厚度的影响，得出了计算着装厚度的经验公式以及与着装厚度相对应的着装建议，提出了增减衣气象指数。文中提出的增减衣气象指数与着装厚度气象指数的联合运用，提高了服务的针对性和准确性。气象指数应用软件可利用中尺度数值预报产品自动生成着装气象指数，方便地应用于预报服务。     

Pinpointing Source of Mekong and Measuring Its Length Through Analysis of Satellite Imagery and Field Investigations

For centuries, explorers and scientists from different countries had made their own conclusions on the source of the Mekong. However, the geographic source of the Mekong is still arguable because of the complexity of the Mekong source water system, inaccessible environment and the varied technologies used by those explorers and scientists. The satellite remote sensing technology has been used to pinpoint the source of the Mekong, associated with the on-the-spot investigations made by the authors in June 1999 and September 2002. The actual length of the Mekong has also been calculated.     

The study on the bottom friction and the breaking coefficient for typhoon waves in radial sand ridges--the Lanshayang Channel as an example

Owing to the interactions among the complex terrain, bottom materials, and the complicate hydrodynam-ics, typhoon waves show special characteristics as big waves appeared at the high water level (HWL) ...     

陕西省田市镇及其周边地区地下水功能区划分

为实现对陕西省田市镇及其周边地区地下水的合理开发利用、科学管理和有效保护,以全国地下水功能区划分技术大纲为基本依据,结合该地区地下水资源的分布特点、水文地质条件、地下水开发利用现状及生态环境保护需求,构建了该区地下水功能区划分指标体系。采用综合指数模型,利用MapGIS技术,将研究区地下水功能区划分为适宜开采区、适度开采区及禁止开采区。研究成果可为田市镇及周边地区制定和实施地下水系统的保护方案、指导地下水资源合理开发利用提供科学依据。     

RJP工法钻机的液压系统设计与应用

根据RJP工法的施工工艺,设计了XLT[CD*2]230型高压旋喷钻机的液压系统,主要有：动力头回转回路,能够实现正反转连续切换,满足RJP工法摆喷施工要求;动力头提升下降回路,能够实现动力头快速提升下降和慢速提升下降,实现间歇步进提升功能;钻机行走回路,要求行走稳定,不跑偏;辅助动作回路,保证辅助动作稳定可靠。现场施工试验表明,该钻机液压系统设计合理,可靠性高,系统节能效果好,完全能够满足RJP工法的施工要求。     

Microseismic Full Waveform Modeling in Anisotropic Media with Moment Tensor Implementation

Seismic anisotropy which is common in shale and fractured rocks will cause travel-time and amplitude discrepancy in different propagation directions. For microseismic monitoring which is often implemented in shale or fractured rocks, seismic anisotropy needs to be carefully accounted for in source location and mechanism determination. We have developed an efficient finite-difference full waveform modeling tool with an arbitrary moment tensor source. The modeling tool is suitable for simulating wave propagation in anisotropic media for microseismic monitoring. As both dislocation and non-double-couple source are often observed in microseismic monitoring, an arbitrary moment tensor source is implemented in our forward modeling tool. The increments of shear stress are equally distributed on the staggered grid to implement an accurate and symmetric moment tensor source. Our modeling tool provides an efficient way to obtain the Green’s function in anisotropic media, which is the key of anisotropic moment tensor inversion and source mechanism characterization in microseismic monitoring. In our research, wavefields in anisotropic media have been carefully simulated and analyzed in both surface array and downhole array. The variation characteristics of travel-time and amplitude of direct P- and S-wave in vertical transverse isotropic media and horizontal transverse isotropic media are distinct, thus providing a feasible way to distinguish and identify the anisotropic type of the subsurface. Analyzing the travel-times and amplitudes of the microseismic data is a feasible way to estimate the orientation and density of the induced cracks in hydraulic fracturing. Our anisotropic modeling tool can be used to generate and analyze microseismic full wavefield with full moment tensor source in anisotropic media, which can help promote the anisotropic interpretation and inversion of field data.     

中国地理学会与《地理学报》的发展

中国地理学会前身是1909年在天津成立的中国地学会。1934年3月中国地理学会的成立与同年9月《地理学报》的创办,不仅是中国地理学科史上的大事,也是中国教育史乃至科学史上的亮点。这是新文化运动中所提倡“赛先生”,即科学观念不断在近代中国传播的重要节点。中国地理学会的成立,清晰地将近代地理学与传统舆地学分离开来,以独立学科的形态出现在中国历史舞台上。《地理学报》的创刊,则使中外地理学家们在中国开始享有高水准的专业学术窗口。这是中国地理学界仁人志士对“科学救国”“科技兴国”等思潮的实践。在中国地理学会的组织和推动下,老一代地理学家艰苦奋斗,将一系列重要的研究成果刊登在《地理学报》,中国地理学家在当时的国家顶层设计中占有了一席之地。虽然,当时对地理科学的重要性认知还主要停留在权力高层与专业学术圈内,但为后来中国地理科学的蓬勃发展播下了火种,也为唤醒普通民众的地理科学意识打下了坚实的科学基础。回顾历史,中国地理学会的成立与《地理学报》的创办可谓是中国地理科学的发轫,自此成为中国地理科学发展的推动者和见证者。值此中国地理学会创立110周年、《地理学报》创刊85周年之际,深入领会“不忘初心、牢记使命”,回顾中国地理学会与《地理学报》发展,以继承和发扬老一辈地理学家的精神,进一步推动地理科学发展,使之成为可持续发展的基础学科,更好地服务于国家建设,服务于人类命运共同体建设。