Coastal seafloor observatory at Xiaoqushan in the East China Sea

The seafloor observation system is becoming an important infrastructure for marine research because it is transforming oceanic research from temporal investigation to long term observation.The East China Sea coastal seafloor observatory,located between 30°31′44″N,122°15′12″E and 30°31′34″N,122°14′40″E,is constructed near the Xiaoqushan Island outside the Hangzhou Bay on the inner continental shelf of the East China Sea.The observatory is connected by a submarine optical fiber composite power cable that is more than one kilometer long and consists of a special junction box that transmits power and communication signals to different instruments.The special junction box has a variety of waterproof plugs and connects to three different instruments installed in a trawl preventer.The submarine optical fiber composite power cable is landed on the platform by The East China Sea Branch,State Oceanic Administration and the power is continuously supplied by the solar panels and solar battery on the top of the platform.The real time data are directly sent through the cable to the platform and are transmitted by CDMA wireless to the receiver at the State Key Laboratory of Marine Geology of Tongji University.Measurements at the observatory have been taken since April 20,2009 after installation and the results have been interpreted.The characteristics of the near bottom boundary are constrained by a sediment suspension model using portion of the observed data.In particular,discussion is provided on the sea surface height anomaly at Xiaoqushan Island influenced by the tsunami driven by the 2010 Earthquake in Chile.The successful establishment of the coastal seafloor observatory is the first step toward future development of seafloor observation systems in China.It not only accumulates experiences in technology and engineering,but also paves the way for performing important oceanic research using the long term continuous observation platform.     

Seismology: speed and size of the Sumatra earthquake

Our seismological results reveal that Indonesia's devastating Sumatra-Andaman earthquake on 26 December 2004 was 2.5 times larger than initial reports suggested--second only to the 1960 Chilean earthquake in recorded magnitude. They indicate that it slowly released its energy by slip along a 1,200-km fault, generating a long rupture that contributed to the subsequent tsunami. Now that the entire rupture zone has slipped, the strain accumulated from the subduction of the Indian plate beneath the Burma microplate has been released, and there is no immediate danger of a similar tsunami being generated on this part of the plate boundary, although large earthquakes on segments to the south still present a threat.     

海底观测网络数据管理系统设计

针对海底观测网数据管理的需求，建立了数据管理系统的功能模型，设计了数据通信、设备管理、故障诊断及数据质量控制等关键技术的相关实现算法。综合运用Socket网络编程、MySQL数据库技术，依据模块化的设计思想，开发了海底观测网数据管理系统。海试结果表明，该系统实现了对海底观测网的实时数据采集、状态监控、数据分类存储和数据共享等功能，具有长期运行稳定可靠、可扩展性强的优点。     

SeisComP3地震监测软件系统及其在海啸预警系统建设中的应用

 SeisComP3 软件系统是近些年发展起来的一款免费的、部分开源的地震实时监测与自动处理系统。根据地震监测、大地震海啸预警等工作需求,本研究组应用SeisComP3 系统提供的实用工具进行辅助功能开发,实现地震数据的实时汇集、共享与自动处理,为大地震海啸预警提供及时、可靠的地震基本参数。同时,基于SeisComP3 系统地震自动定位结果和实时波形数据,应用W 震相方法快速反演海啸强震震源机制解,为海啸数据模拟程序提供实际发震断层面参数解,提高后续海啸数值预报的准确性。实际应用表明：SeisComP3 软件系统为海啸业务提供了重要的数据保障和科技支撑,促进了海啸预警预报工作的发展。     

Role of atmospheric heat source/sink over the Qinghai-Xizang Plateau in quasi-4-year oscillation of atmosphere-land-ocean interaction

Using 1961—1995 monthly atmospheric apparent heat source/sink <Q₁> over the Qinghai-Xizang Plateau (QXP) and reanalysis data of NCEP/NCAR, and 1961—1994 monthly SST of UK/GISST2, the statistical study is undertaken on the QXP heat source/sink in relation to both atmospheric circulation in Asia and El Niño/La Niña events. It is discovered that there exists noticeable interaction in a quasi-4-year period among the <Q₁> of the QXP, low-level meridional winds east of the QXP, low-level zonal winds in the equatorial Pacific, SST in the equatorial eastern Pacific, and the circulation at mid and high latitudes north of the QXP. They have difference in phase. The cold source intensity of the QXP in winter favours a low-level meridional wind anomaly to prevail in the mainland of China and its coast east of the QXP and to last until the subsequent autumn. The wind anomaly can induce a low-level zonal wind anomaly of the tropic Pacific that finally affects an El Niño/La Niña event in the autumn and subsequent winter. The event in autumn/winter has effect on the deep trough position and cold air track of East Asia in next winter that influences the intensity of the QXP winter cold source.     

海水层静校正的综合解决方案研究

大面积的海上三维地震勘探经常需要数月的采集周期,采集期间的海水层潮汐现象及物性变化会产生诸如潮汐校正和冷水校正等严重的静校正问题。现论述了一种综合的水层静校正方法来解决上述问题。该方法是通过在CDP道集上拾取水底、反演水底时间求取水速、水底倾角和方位角,根据拾取的水底时间和测算的水速度求取并应用冷水校正,然后用求取的零偏移距到达时间与参考时间的差值计算并应用潮汐校正。该方法在某深水区三维地震资料的应用上取得了明显的效果。     

基于张衡一号电磁卫星数据对印尼Ms 7.4地震的研究

以2018年9月28日印尼Ms 7.4地震为背景, 利用张衡一号电磁卫星观测的ULF磁场X, Y和Z三分量数据, 采用滑动四分位(IQR)算法、滑动主成分分析算法(PCA)和短时傅里叶变换算法(STFT), 对震中范围的时空电磁数据进行分析, 结果显示 3 种算法都能有效地提取到震前异常。1) X,Y和Z分量均值震前7天开始出现异常, 随着发震时间临近, Y和Z分量的异常程度逐渐增加, 震前2天达到峰值, Y分量最大异常达到0.7 nT, 震后异常慢慢消失; 2) 震前5天主成分出现异常, 第一主成分占比急剧下降, 下降幅度超过15%, 第二、第三主成分占比急剧上升, 异常持续3天; 3) 震前9天, 13和25 Hz功率谱密度占比同时出现大幅异常, 13 Hz占比上升35%, 25 Hz占比下降超过40%, 13 Hz占比出现正异常, 最大正异常达到0.1, 25 Hz占比出现负异常, 最大负异常达到?0.15, 震后异常消失。结合同时段的太阳地磁活动情况, 认为上述电磁异常可以作为印尼地震的前兆。     

海光缆远程供电系统可靠性研究

设计了一种基于电能分支单元的海光缆远供系统.通过计算海缆的电感、电容及电阻量,将海缆和电力设备等效电路模型编入仿真程序,建立远供系统模型,归纳出远供系统的5种故障类型,并利用专业仿真软件对系统可靠性进行仿真.结果显示,在多种不同故障下系统均能保持串联恒流供电特性,且工作稳定,说明基于电能分支单元的海光缆远程供电系统具有较高的可靠性,能够实际应用于海底观测网络.
     

Analysis of ionospheric anomalies before the 2011 <Emphasis Type="Italic">M</Emphasis><Subscript>w</Subscript> 9.0 Japan earthquake

On March 11, 2011, a large earthquake of Mw=9.0 occurred near the east coast of Honshu, Japan. This paper investigates preearthquake ionospheric anomalies during the earthquake period, using data from global navigation satellite systems and ionosonde stations near the epicenter. A clear anomaly that occurred on March 8 lasted 6 hours. Eliminating ionospheric anomalies that may have been caused by solar activities and magnetic storms, we believe that a positive anomaly on March 8 was very possibly an ionospheric precursor. The affected ionospheric area on March 8, which is evident on a vertical total electron content distribution map, extended to 50° in longitude and 20° in latitude, with length ratio approximately 3:1. The anomaly peak arose from 15:00-19:00 LT, and its location did not coincide with the vertical projection of the epicenter, but was instead to its south. Corresponding ionospheric anomalies are also observed in the magnetically conjugated region. There were no obvious ionospheric anomalies in other parts of the world. To analyze changes in the ionospheric anomaly, computerized ionospheric tomography technology was used to invert the spatial and temporal distribution of electron density in the ionosphere. The ionospheric anomaly on March 8, 2011 is suggested to be an ionospheric precursor of the March 11 earthquake in Japan.     

2010年智利强震引发的海啸对台湾周边海域的影响

2010年2月27日南美洲智利中部近岸发生强震并引发海啸.利用海啸期间台湾周边海域验潮站的潮位资料,分析了此次海啸对台湾周边海域的影响,海啸波通过太平洋于震后25.5h到达台湾周边海域,最大波高达44 cm.进而从理论上讨论了海啸传播时间和波高变化的简单计算方法,并引入了波高衰减因子.结果表明,该简单计算方法能快速且较准确地计算出海啸波的传播时间,引入的波高衰减因子,可在一定程度上为台湾周边海域海啸的方便快捷的预警提供参考.     

南海潜在海啸源危险性的定量分析

利用COMCOT模型, 分析马尼拉海沟一个潜在海啸源的危险性。通过改变震级和震源深度两个海啸初始场信息, 揭示海啸登陆中国沿海地区时的首波波幅与二者的定量关系。结果表明: 震源深度对首波波幅的影响幅度可以达到50%, 地震震级不同, 震源深度对首波波幅的影响趋势也不同; 海啸登陆时的首波波幅基本上随着震级的增加而加大, 但由于海啸波会与近岸的反射波互相叠加, 可能导致在海啸传播至近岸过程中首波登陆波幅异常减小; 震级达到Mw 8.6时, 海啸等级为1级, 部分沿海地区会遭受海啸威胁。     

基于深海锚系潜标的潮汐特征计算方法

针对深海潮汐特征难以获取的困难,基于深海锚系潜标压力传感器所测资料,利用线性近似的方法,建立了海面水位变化计算模型,并对该模型进行计算误差分析,提供了模型计算精度判别方法。基于该模型,利用南海中部海区深海锚系实测压力资料获取了锚系点的海面水位数据,并采用T-TIDE潮汐调和分析函数处理水位数据,获取了该海区的潮汐调和常数,对该海区的潮汐特征进行了验证与分析。所得潮汐类型为不规则日潮,主要(半)日分潮K1、O1、M2的振幅和迟角,均与前人利用卫星高度计资料和数值模拟分析结果基本一致。     

海南岛东北海域海流和余流特征分析

【目的】研究海南岛东北海域的潮流、余流特征和分布规律。【方法】依据2017年6月在海南岛东北海域调查的夏季大潮实测海流数据,采用准调和分析方法分析实测数据,并根据该分析所得的一些参数分析研究区域的潮流性质、潮流运动形式、M2分潮潮流椭圆、潮流的垂直分布及夏季的余流分布。【结果】海南岛东北海域的潮流以不正规半日潮流为主;各站点潮流椭圆旋转率都较小,潮流运动形式以往复流为主,方向为NW—SE;除S4站以外,其余各站海流均为略带旋转的往复流,往复流的方向为NW—SE,旋转流的旋转方向为顺时针;研究海域表层余流大于中底层,近岸余流较弱,琼州海峡附近的站点余流最强;各站表、中、底层余流流向较一致,表层余流主要受风场的影响作用,底层余流主要受到底地形的影响。【结论】对调查区域的潮流、余流特性有了一个较为全面的认识。     

Hodrick-prescott滤子在中国经济增长周期分析中的运用

根据建国以来的GDP数据，利用HP滤子结合传统的时间序列分解方法提取增长趋势，分离并且平滑出经济增长的中短周期，分析了我国经济周期的基本特点，并且提出了相关的预测和宏观经济政策建议。     

潮汐应力与云南及邻区的地震

提出了潮汐应力对发震断层的力学模式,描述了附加潮汐应力对发震断层的促滑作用方式,并将该模式应用于云南及邻区的地震,计算了173个地震震源处沿主压应力P轴和主张应力T轴方向的附加潮汐应力分量,分析了这睦量对发震断层的作用方式以及受潮汐应力促滑作用的发震断层类型,结果表明,所研究的云南及邻区发生的173个地震中,64％的地震发震断层受到潮汐应力的促滑作用,其中,受减压型促滑作用的发震断层数比例略大于受增压型促滑作用的发动层数比例;在受到潮汐应力促滑作用的111个发震断层中,走滑型发震断层占67％,倾滑斜滑型发震断层占33％,说明云南及邻区的走滑型地震较易受到潮汐应力的触发作用。     

1998年张北地震前的大气增温异常

 地震前的热异常已有许多研究,大多研究得出的异常区域面积过大或者远离震中以至于难以判断震中。用温度相减法研究张北地震前的温度变化,发现震前13天张北附近出现了孤立的增温区,张北站增温5.8℃,是当天整个中国东部地区的最大增温值。增温区长轴为北东向,区内分布有北东向尚义-多伦断裂。震前1天沿北西向张北—渤海断裂带张北的增温也达到最大值,张北地震即发生在这两组断裂汇而不交的部位。将增温区中心预测为震中,误差大概为80km,这一数值结果比目前大多数热异常的研究结果好,显示出气象数据在地震研究中有一定应用价值。同时,气象数据的观测和加工有全国统一的规范,处理起来简单方便,本文提出的温度相减法,简便易行,由于使用的是温度的相对变化,避免了各地小气候不同导致的温度差异。如果结合地震台网观测数据,在地震预测研究中能发挥更好的效果。     

基于钦州湾验潮站2008-2020年潮位序列的潮汐特征研究

潮汐是钦州湾的主要海洋动力,对物质输运、海洋工程、海洋生态环境等都有重要影响。本研究基于钦州湾验潮站2008-2020年共13年的水位观测资料,利用潮汐调和分析、偏度计算和线性回归等方法,分析钦州湾长时间的潮汐变化、潮不对称性特征及海平面变化趋势。结果表明,钦州湾验潮站潮汐以O₁、K₁分潮占优,属于规则全日潮。主要分潮振幅有显著的年际变化,2008年为最小值,O₁为95.82 cm, K₁为88.18 cm, M₂为39.53 cm; 2016年达到最大值,O₁为104.27 cm, K₁为95.15 cm, M₂为46.16 cm,这一变化与月赤纬角的变化有关。钦州湾潮不对称现象显著,涨潮历时比落潮历时多2-3 h,造成该现象的主要原因是受到半日分潮和全日分潮之间相互作用的影响,其中主要贡献来源于O₁、K₁、M₂之间的相互作用,占总潮汐偏度的80...     

国产HJ小卫星遥感影像多特征融合用于日本海啸灾情快速监测

 针对特大地震和海啸灾害的特点与灾情监测的需求,设计和构建了一种基于多特征决策级融合的灾情快速变化检测方法,首先利用遥感影像中提取的NDVI、主成分变换分量、独立成分变换分量等特征分别提取变化信息,然后对多种变化信息进行决策级融合,获得具有更高可靠性的变化图,用于灾情分析。将所设计的方法用于国产环境与灾害监测预报小卫星HJ-1A/B数据处理分析,对日本东部沿海区域海啸灾害前后进行变化检测与灾情信息提取试验,有效地检测了海啸灾害后的海水倒灌区域、陆地积水区、植被淹没区以及建筑受损区等变化区域。研究表明,基于多源特征融合的非监督变化检测流程可以快速、有效地提取海啸受灾区域,为灾害应急响应与灾情评估提供支持。     

Drifter trajectory tracking experiment and analysis with multi-frequency HFSWR in the East China Sea

We conducted the drifter trajectory tracking experiment for two drifters in the East China Sea,in which the currents were detected by two multi-frequency HFSWRs using the Lagrange-tracking method.The tracking drifter trajectory shows good agreement with the GPS records by qualitative and quantitative analysis that indicates that drifter tracking by HFSWR is valid.In the 12-hour tracking for drifters P1 and P2,the average errors are 1.84 km,1.73 km,and the maximum errors are 3.52 km and 3.12 km,respectively.The current measurement is evaluated by an acoustic Doppler current profilers(ADCP) in-situ observation,and it is the first multi-frequency HFSWR ocean surface monitoring experiment in China.In addition,the main aspects(HFSWR current measurement error,wind,and wave) influencing the tracking accuracy are discussed,and especially the wind factor’s impact is analyzed through the wind filed data.