中国全新世高温期中的气候突变事件及其对人类的影响

本文通过孢粉、闪芯和古湖泊等研究，确定了高温期起迄时间为８．５－３ＫｂＢ．Ｐ．，恢复了高温期的气候与环境的基本特征，作者发现在高温期仍在有７．８，５．３和４ｋａＢ．Ｐ．等三次具有普遍意义的气候突变事件，其降温幅度甚至可达３－４℃。这些突变事件对人类文明和环境变化起很重要的作用，尤其是与它位伴随出现的各种严重自然灾害阻碍和限制了古文明的发展，有时甚至是毁灭性的打击。     

东海DC-1, DC-2孔古地磁研究

本文报道了东海DC-1,DC-2孔古地磁研究结果,表明DC-l孔26.9m岩芯及DC-2孔61.0m岩芯段均以正极性为主,属布容正极性世 (Brunhcs)。其中DC-l孔18.86-19.18m的反向磁化带(倾角为—49.29°),经~(14)C测年为距今115lO土570a;DC-2孔29.95—30.54m处反向磁化带(倾角为—40.5°),经~(14)C测年为距今10250±lOOa。可与哥德堡事件(Gǒthcnburg)对比。对比地磁年表,DC-2孔37.80—38.0m为反极性事件与蒙哥事件(Mungo event)相当,7l.20—74.44m划为布莱克事件(B1akc event)。据此计算全新世沉积速率为2.12—2.84m/1000a,晚更新世沉积速率为O.65一O.69m/1000a。     

越南红河三角洲近五千年来的几个降温事件

根据对越南红河三角洲的2个钻孔的孢粉分析结果，结合沉积特征和高精度的AMS^14C测年数据，恢复了近五千年来百年一千年尺度的气候变化，发现了3个分别开始于4530cal．aBP，2100cal．aBP和620cal．aBP的明显降温事件，其中4530cal．aBP和620cal．aBP降温事件可与全球全新世气候变冷事件中的“新冰期(Neoglacial)”和“小冰期(Little Ice Age)”相对应，可能与由北大西洋地区几个短期变冷事件的全球气候响应机制有关。3340cal．aBP以来，人类干扰性植物成分的增加，表明人类活动对自然植被的影响改造作用增强，因此，本研究中气候的降温事件不排除人类影响的因素，仍需要进一步深入研究。     

手机端地震预警研究进展与展望

传统地震预警方法通过在地震频发区域部署高密度地震监测台网,进而构建区域地震预警系统。但此方法所需投资较高,同时还需要政府和不同行业间的密切合作,使得大部分位于地震频发区域的国家和地区无力支撑地震预警系统的建设与运维。随着微机电系统技术的发展以及智能手机的普及,地震预警技术出现了新的研究方向,利用智能手机开展地震预警具有巨大的发展潜力。迄今为止,国内外已研发完成多款诸如MyShake、i-jishin之类的手机端APP地震预警软件。本文详细描述了利用手机端内嵌MEMS芯片开展地震预警的研究进展,较为系统地总结了在手机端进行地震预警时所涉及的处理流程以及相关算法。     

Analysis of the sediment sources of flood driven erosion and deposition in the river channel of the Fu River Basin

Studying the characteristics of runoff and sediment processes and revealing the sources of sediment provide key guidance for the scientific formulation of relevant soil erosion protection measures and water conservancy development plans. In the current study, the flow and sediment data of five hydrological stations on the main stream of the Fu River Basin (FRB) from 2007 to 2018 were selected to identify flood events, explore the variation of sediment transport along the FRB, and clarify the sediment sources. The results found that the Jiangyou–Fujiangqiao section is the main source of sediment in the FRB during the flood season. The runoff volume and sediment load during flood events in the Jiangyou–Fujiangqiao section accounted for 35% and 145% respectively of that of Xiaoheba station. These results combined with the change of the sediment load before and after the 2008 Wenchuan Earthquake (May 12) show that the sediment in this section mainly comes from the Fu River tributary–the Tongkou River watershed. The calculation results for the sediment carrying capacity of the Fu River show that the main stream was in a state of erosion in theory. However, according to the calculation results for the interval sediment yield during flood events, the sediment load at the Xiaoheba station was smaller than that at the Shehong station upstream. The analysis indicates that this was not because of sediment deposition in the river channel, but because of sand mining in the river channel and sediment interception by water conservancy projects. If heavy rainfall occurs in the FRB, the sediment accumulated upstream will move downstream with the resulting flood, and the sediment yield in the FRB may further increase. These research conclusions can provide reference information for improving the prediction and management ability of soil and water loss in the FRB and scientific regulation of the Three Gorges Reservoir.     

Short-term offshore extension of Brahmaputra-Ganges and Irrawaddy freshwater plumes to the central northern Bay of Bengal based on in situ and satellite observations

In this study, the short-term offshore extension of Brahmaputra-Ganges(BG) and Irrawaddy freshwater plumes to the central northern Bay of Bengal(BoB) was investigated based on in situ and satellite observations. In the summer and winter of 2015, two significant freshening events with periods of weeks were observed from a moored buoy at 15°N, 90°E in the BoB. Soil Moisture Active Passive(SMAP) satellite sea surface salinity compares well with the in situ data and shows that these freshening events are directly related to the short-term offshore extension of the BG and Irrawaddy freshwater, respectively. These data combined with the altimeter sea level anomaly data show that the offshore extending plumes result from freshwater modulated by eddies. During summer, the BG freshwater is modulated by a combination of three closely located eddies: a large anticyclonic eddy(ACE) off the northwestern BoB coast and two cyclonic eddies in the northern BoB. Consequently, the freshwater extends offshore from the river mouth and forms a long and narrow tongue-shaped plume extending southwestward to the central BoB. During winter, the Irrawaddy freshwater is modulated by two continuous ACEs evolved from Rossby wave propagating westward from the Irrawaddy Delta off Myanmar, forming a tongueshaped plume extending to the central BoB. Strong salinity fronts are formed along the boundaries of these tongue-shaped plumes. These findings confirm good capability of the SMAP data to investigate the short-term offshore extension of the BG and Irrawaddy freshwater. This study provides direct evidences of the pathways of the offshore extension of the BG and Irrawaddy freshwater and highlights the role of eddies in the northern BoB freshwater plume variability.     

强风事件识别及预报订正方法研究

以如东海上风电场升压站激光雷达测风资料为基础,提出了一种强风事件识别方法,设计并比较了三种预报强风事件识别方案。基于决策树和一元线性回归方法,分别开展了针对强风事件的订正方法研究。结果发现:三种预报强风事件识别方案中,等分位阈值方案明显更优,事件命中率达到76.1%,匹配时长命中率达到87.6%;采用消偏阈值方案和等分位阈值方案预报的强风事件时长会更接近观测强风事件时长;等分位阈值方案识别的事件基本可以覆盖到各次观测强风事件的全程;两个订正模型相对于模式预报都有一定提升与改进,其中决策树比一元线性回归模型更优,其平均绝对误差、相对误差和均方根误差明显更小。     

2017年精河6.6级地震异常变化数据跟踪分析

利用数据跟踪分析信息库,提取2017年8月9日精河6.6级地震前3个月,距震中500 km范围内的观测数据跟踪分析记录,对与地震相关的不明原因事件进行分析讨论。结果表明：精河地震发生前,温泉地震台水平摆、精河地震台水平摆、博乐32井水位出现不明原因的疑似前兆异常变化,地震结束后逐渐恢复正常。巴仑台地震台分量应变在此次地震前也出现不明原因变化,但地震结束后异常持续变化,需后续重点跟踪分析。     

基于闪电双极性窄脉冲事件波形观测日出日落电离层D层变化

利用闪电作为辐射源来探测电离层D层是近年来国外学者研究的热点.本文基于江淮流域六站同步闪电观测站网,实现了一种利用闪电双极性窄脉冲事件（Narrow Bipolar Events,NBE）来探测电离层D层等效高度的方法.基于此方法,对两次分别发生在日出和日落阶段的雷暴分析结果显示,上述两个阶段D层反射高度变化特征呈现显著的不对称性：日出期间D层反射高度随时间线性降低速率为5.9 km/h;而日落期间D层反射高度随时间线性递增速率为8.6 km/h.综合日间太阳耀斑期间D层反射高度剧烈波动的观测事实,与日出、日落期间D层特征变化,结果表明太阳辐射电离中性大气分子的电子生成机制在日间D层电子密度变化中占主导地位.本文结果展现了利用NBE事件监测电离层D层变化特征的可行性,这一方法与基于地闪回击波形的D层探测方法结合在一起,有望把现有具有闪电事件定位和电磁波波形记录能力的闪电观测站网扩展为实时对电离层D层时空变化监测的网络.     

大岗山水库地震台网水库诱发地震常规定位方法对比

采用MSDP软件中的单纯型、HypoSat和LocSat定位方法,从震源深度及残差等方面,对比分析2014年大岗山水库区域内123次M_L≥2.0地震的定位结果,选择适用于水库诱发地震的最佳定位方法,并以库区17次定点爆破事件为例,验证最佳定位方法的可靠性。结果认为,LocSat定位方法更适用于水库诱发地震。