基于多尺度注意残差网络的地震波形分类研究

选用2010年2月—2016年12月发生在北京顺义及河北三河等首都圈邻近区域的117个地震事件(包括54个天然地震事件和63个非天然地震事件——爆炸事件)作为研究对象,利用文章所提出的多尺度注意残差网络对其中的天然地震事件和爆炸事件波形进行二分类。首先,对原始地震波形进行简单预处理并截取成相同长度的地震时序数据,直接将其作为网络模型的输入;其次,选用含有残差模块的深度神经网络作为基础网络,利用深度神经网络对特征的自动提取能力,省略了传统波形分类需要提前提取时域波形的特征作为分类算法输入的步骤;然后,融合通道注意力机制(ECA)并对其进行改进,将空间维度的信息融入通道信息,优化了网络对关键信息的关注,更好地聚焦重要特征;最后,使用空间金字塔池化代替最大池化进行多尺度特征融合,得到更多的特征信息,构成多尺度注意残差网络。实验结果表明,最高分类准确率为97.11%,平均分类准确率为96.53%,证明了多尺度注意残差网络在地震波形分类任务中的有效性,为震源类型识别工作提供了一种新的方法。     

中国海湾沉积物重金属比较分析

随着沿海城市工业、养殖业及船舶运输业的发展,大量的重金属进入到海湾并迁移到沉积物中,海湾沉积物重金属污染已经成为一项突出的海洋环境问题。重金属污染不仅会对海洋沉积环境造成严重的破坏,还会随着食物链富集并危害人类健康。文章比较分析了中国海湾沉积物重金属的含量、时空分布特征、赋存形态、来源以及污染评价,以期全面了解海湾沉积物重金属污染现状与发展趋势,为海湾重金属污染防治及生态修复提供方向。     

城市失地农民"家"的重构与协商——以鄂尔多斯为例

随着中国城镇化进程的推进,离乡进城的失地农民期盼在城市中营建“新家”并渴望扎根于城市。援引批判“家”的地理学理论,以典型资源型城市鄂尔多斯市的移民社区为例,分析失地农民重构后“新家”的状态与面临的问题。研究表明:在民间借贷危机与被动城市化压力下,失地农民的“新家”处于一种复杂的“不确定性”之中。在这种不确定性的束缚下失地农民通过日常生活积极主动地争取物质的富足与生活的意义。“家”的营建给了失地农民积极面对全新城市生活的理由与动力,但营建“家”的努力仍然无法让他们逃脱在城市中最真实的社会体验,并面临着在城市“新家”中多重且边缘的身份境遇。     

Land use transition and rural spatial governance: Mechanism,framework and perspectives

Journal of Geographical Sciences - The pattern for utilization of rural space is closely related to rural transformation development (RTD). The problem of rural space utilization is an important...     

基于WRF模拟的晋江市海陆风特征分析

随着沿海城市的快速发展,城市气候环境恶化,研究弱大气环流背景下的海陆风对改善城市环境具有重要意义。以晋江市为例,利用站点风要素观测数据,结合海陆风判别条件,提取并分析了两个典型海陆风日海陆风的基本特征;采用WRF与Noah陆面过程模式耦合,选用BEP多层城市冠层模型,对典型日进行了风场模拟。从模拟结果中分解出局地风,在验证海陆风现象的基础上,分析了海陆风特征的空间分布规律。结果显示:WRF模拟的逐小时局地风向时序与实测情况吻合较好,通过了信度为0.05的显著性检验,但局地风速模拟值与实测值存在显著差异,平均达到1 m/s。从WRF模拟结果提取的海、陆风起始和终止时间、持续时间与实际情况存在一定差别。两者持续时间在空间上的变化与各自起始时间的空间变化一致,且未明显出现随离岸距离增加,海陆风减弱的现象。上述结果表明,WRF能够较好地模拟海陆风日的风场特征,尽管对海、陆风速的模拟还存在一定的不确定性,但所得结论对晋江市城市规划和微环境改善有参考意义。     

光强和盐度对龙须菜生长及光合特性的影响

持续降雨会引起光照强度和海水表层盐度的变化。近年来,受梅雨影响,福建省龙须菜(Gracilariopsis lemaneiformis)栽培产量波动明显。为揭示其原因,本实验设置3个盐度梯度(低盐：16,中盐：24,高盐：32)和两个光强水平[低光：30μmol/(m²·s),高光：120μmol/(m²·s)],共6个不同处理组合,研究其对龙须菜生长和光合特性的影响。结果发现：(1)盐度、光照强度和二者交互作用对龙须菜的相对生长速率和净光合速率均具有显著影响(P<0.05),适当降低盐度、增加光照有利于提高藻体相对生长速率和净光合速率,同时盐度适当降低条件下藻体呼吸速率被显著抑制;(2)光照强度和盐度对龙须菜有效光合量子产率、最大相对电子传递速率、光能利用效率均具有显著影响(P<0.05),在光照增加条件下有效光合量子产率和最大相对电子传递速率随盐度增加呈先增加后降低的趋势,光照强度和盐度的交互作用仅对光能利用效率影响不显著(P>0.05);(3)盐度对龙须菜的光合色素含量具有显著影响(P<0.05),在同一光强条件...     

2022年西北太平洋和南海台风预报精度评定

评定2022年西北太平洋和南海台风业务定位定强、路径和强度预报精度,结果表明：2022年,官方台风预报机构的定位误差与台风强度等级呈负相关;中国气象局中央气象台在各强度等级的定位平均误差最小,全年定位平均误差（15.4km）较2021年（19.7km）减小21.8%,定强平均绝对误差（1.3m·s-1）较2021年（1.4m·s-1）略减小。主观预报和客观预报方法的路径预报平均误差较2021年普遍有所减小,而强度预报平均绝对误差较2021年普遍有所增大。SSTC、CMA-TRAMS和ECMWF-IFS路径预报技巧评分相对较高。NCEP-GFS、JMA-GSM、CMA-TRAMS和CMA-TYM强度预报系统性偏差不明显,NCEP-GFS、HWRF和CMA-TRAMS强度预报技巧评分相对较高。     

北斗系统电离层模型参数改正精度分析

本文讨论了电离层垂直电子总含量比较法和单频单点定位法两种电离层模型参数改正精度评估方法,介绍了北斗系统发播的电离层模型参数的使用方法,基于欧州定轨中心提供的全球电离层数据评估北斗系统发播的电离层模型参数精度,分析结果表明：北斗系统发播的Klobuchar电离层模型参数在西安地区的改正比例,白天为80％左右,夜间为75％左右。     

The vulnerability evolution and simulation of social-ecological systems in a semi-arid area: A case study of Yulin City,China

Taking the semi-arid area of Yulin City as an example, this study improves the vulnerability assessment methods and techniques at the county scale using the VSD (Vulnerability Scoping Diagram) assessment framework, integrates the VSD framework and the SERV (Spatially Explicit Resilience-Vulnerability) model, and decomposes the system vulnerability into three dimensions, i.e., exposure, sensitivity and adaptive capacity. Firstly, with the full understanding of the background and exposure risk source of the research area, the vulnerability indexes were screened by the SERV model, and the index system was constructed to assess the characteristics of the local eco-environment. Secondly, with the aid of RS and GIS, this study measured the spatial differentiation and evolution of the social-ecological systems in Yulin City during 2000–2015 and explored intrinsic reasons for the spatial-temporal evolution of vulnerability. The results are as follows: (1) The spatial pattern of Yulin City’s SESs vulnerability is “high in northwest and southeast and low along the Great Wall”. Although the degree of system vulnerability decreased significantly during the study period and the system development trend improved, there is a sharp spatial difference between the system vulnerability and exposure risk. (2) The evolution of system vulnerability is influenced by the risk factors of exposure, and the regional vulnerability and the spatial heterogeneity of exposure risk are affected by the social sensitivity, economic adaptive capacity and other factors. Finally, according to the uncertainty of decision makers, the future scenarios of regional vulnerability are simulated under different decision risks by taking advantage of the OWA multi-criteria algorithm, and the vulnerability of the regional system under different development directions was predicted based on the decision makers' rational risk interval.     

Strengthened influence of the East Asian trough on spring extreme precipitation variability over eastern Southwest China after the late 1980s

The relationship between variations in the East Asian trough (EAT) intensity and spring extreme precipitation over Southwest China (SWC) during 1961–2020 is investigated. The results indicate that there is an interdecadal increase in the relationship between the EAT and spring extreme precipitation over eastern SWC around the late 1980s. During the latter period, the weak (strong) EAT corresponds to a strong and large-scale anomalous anticyclone (cyclone) over the East Asia–Northwest Pacific region. The EAT-related anomalous southerlies (northerlies) dominate eastern SWC, leading to significant upward (downward) motion and moisture convergence (divergence) over the region, providing favorable (unfavorable) dynamic and moisture conditions for extreme precipitation over eastern SWC. In contrast, during the former period, the EAT-related circulation anomalies are weak and cover a relatively smaller region, which cannot significantly affect the moisture and dynamic conditions over eastern SWC; therefore, the response in extreme precipitation over eastern SWC to EAT is weak over the period. The interdecadal change in the relationship between eastern SWC spring extreme precipitation and the EAT could be related to the interdecadal change in the EAT variability. The large (small) variability of the EAT is associated with significant (insignificant) changes in spring extreme precipitation over eastern SWC during the latter (former) period.摘要本文研究表明东亚大槽强度与中国西南地区东部春季极端降水的关系在20世纪80年代末后显著增强, 这可能与东亚大槽自身变率的年代际变化有关. 在80年代末之后, 东亚大槽的变率显著增强, 其对应的大气环流异常也偏强, 范围偏大, 可以显著影响西南地区东部的水汽和动力条件, 从而引起该地区春季极端降水的显著变化. 而在80年代末之前, 东亚大槽的变率偏弱, 其对应的大气环流异常也偏弱, 范围偏小, 因此不能对西南地区东部春季极端降水的变化产生显著影响.