Physical oceanography of the Caroline M4 seamount in the tropical Western Pacific Ocean in summer 2017

Physical oceanography plays an important role in the formation of submarine sediments,and the distribution of nutriments and biocenoses in seamounts.The M4 seamount is located in the Caroline Island Ridge of the Western Pacific Ocean.The physical properties around M4 seamount are preliminarily analyzed based on the in-situ data obtained in summer 2017 in Caroline M4 seamount and open-sourced data.We found that the water in the upper 200 m is controlled by the westward North Equatorial Current(NEC),while the water between 300-1 000 m is dominated by the eastward North Equatorial Undercurrent(NEUC).The current direction fluctuates significantly below 300 m at upstream stations.At the same depth of the lee sides,the current direction changes with the distance from seamount.These are likely caused by the obstacle of M4 seamount.The calculation results show that there is an anticyclonic cap above M4 seamount caused by tidal rectification.Tidal currents in M4 seamount are squeezed by the topography and amplified,and the amplified tidal currents play a dominant role in M4 seamount.First,the circulation system generated by the interaction of the amplified tidal current and M4 seamount drives the upward/downward movement of the isotherms.Secondly,the thickness of the surface turbulent layer is changed with the tidal phase.Thirdly,high turbulent diffusivities are found in the bottom of M4 seamount,and these are most likely attributed to the turbulent mixing induced by the mutual effect between semidiurnal tidal currents and steep bathymetry.This article of physical oceanography provides scientific basis for further analysis of the distribution of biological community and deposition mechanism in M4 seamount.     

Control factors of DIC in the Y3 seamount waters of the Western Pacific Ocean

An investigation was carried out in the Y3 seamount area of the Western Pacific Ocean in December 2014,and the distribution of dissolved inorganic carbon(DIC) and its relationship with environmental factors in this area were explored.The results show that DIC concentration was higher in the adjacent waters of the Y3 seamount area,and the uplift of DIC isolines at the stations was close to the seamount.Meanwhile,interaction between the North Equatorial Current(NEC) and the Y3 seamount affected the DIC distribution i.e.,the upwelling in the same direction of the NEC was obvious,resulting in a decreasing trend of average concentration of DIC in the 200 m water column from the top to the two side s in this direction but in the cross direction.The DIC concentration increased with the water depth increase,and its distribution was affected by various environmental factors.In the surface water,high temperature was a decisive factor for the decrease of the DIC concentration,but the photosynthesis of phytoplankton showing only a weak influence.In the North Pacific Tropic Water(NPTW),DIC production rate from organic matter decomposition was higher than that of DIC consumption by phytoplankton photosynthesis,leading to a continual increase of DIC.In the North Pacific Intermediate Water(NPIW),organic matter decomposition played a leading role in the increase of DIC.In the deep water,decomposition of organic matter weakened,and the dissolution of CaCO_3 controlled the carbonate system,and DIC had the smallest variation range.     

Analysis of differences in nutrients chemistry in seamount seawaters in the Kocebu and M4 seamounts in Western Pacific Ocean

Comprehensive surveys were conducted in the Kocebu deep seamount and the M4 shallow seamount in the Western Pacific Ocean in March 2018 and May 2019,respectively.The distributions of nutrients in euphotic zone of the two seamount-areas were revealed,and the causative controlling factors were analyzed.Results show that the vertical distribution of nutrients in the two seamount-areas accorded with the general law of the oligotrophic ocean.The concentrations of NO_3-N,PO_4-P,and SiO_3-Si generally increased gradually with the increase of water depth,and they were extremely low in water layers within100 m.The area of high N02-N concentration well agreed with the Deep Chlorophyll Maximum Layer.On the other hand,the distribution of water masses and phytoplankton and hydrological conditions in the two seamount-areas were different,resulting in lower concentrations of NO_3-N,PO_4-P,and SiO_3-Si in the water layers below 100 m in the Kocebu seamount area than those in the M4 seamount area.In addition,N02-N was affected by the distribution of phytoplankton,and distributed mainly in the water layers of 150 and100 m.There was upwelling in the euphotic zone of M4 seamount area,causing accumulations of nutrients and phytoplankton around the seamount,forming a "seamount effect";however,no such an effect was found in Kocebu seamount area.Affected by the composition of biological community and the "seamount effect",the nitrogen limitation in the M4 seamount area was not significant,and the dissolved inorganic nitrogen(DIN):PO_4-P and SiO_3-Si:DIN were closer to the Redfield ratios.     

导航卫星非差精密定轨测站选取策略分析

推导了测站分布对定轨精度影响的公式,提出一种兼顾测站数量、观测数据质量以及测站地理分布的测站选取策略。利用IGS和iGMAS全球观测网数据,设计了3种不同的测站分布方案,进行GPS精密定轨实验。结果表明,使用30个全球均匀分布的测站,GPS三维定轨精度能达到6.0 cm左右|使用40个全球均匀分布的测站,GPS三维定轨精度能达到3.5 cm的水平|使用50个全球均匀分布的测站,GPS三维定轨精度能达到2.8 cm以内|超过50个的测站对GPS定轨精度提高基本上没有贡献。     

辽宁南部地区地壳剪切波分裂特征

利用辽宁区域数字地震台网2008-01?2018-12近场小地震波形资料,采用剪切波分裂(SAM)方法计算辽宁南部地区8个台站的快剪切波偏振方向和慢剪切波时间延迟,主要分析营口(YKO)台和盖县(GAX)台的剪切波分裂参数.分析结果表明:1)8个台站的快剪切波偏振优势方向以NE-NEE和NW两个方向为主,其中5个台站的...     

卫星导航定位基准站备案管理系统设计与实现

针对我国卫星导航定位基准站统一管理需求和信息共享交换不足的问题,利用信息化的手段构建了一套网络化的基准站建设备案管理系统。该系统以全国基准站摸排和核查结果信息为数据基础,利用集中在线式设计架构和数据库自动识别同步技术,提出了基于空间拓扑结构的基准站信息表单构建方法,实现了相关性信息唯一标识、动态关联以及基于主辅标识的基准站信息管理工作流。系统解决了数据库之间实时联动更新问题,实现了全国基准站的信息交互共享和统一规范管理,已成为全国基准站建设和应用高效管理的工具。     

绵阳站气温均一化检验及初步分析

为了对绵阳站气温序列进行细致的均一化检验,利用1961-2010年绵阳及周边共14个观测站的年平均气温观测资料,选取了与绵阳站水平距离近、海拔高度差异小、相关性高、气温序列完整并服从正态分布、无明显突变点的4个站点,通过差值法建立被检验序列,再采用标准正态检验方法对其进行均一性检验。结果表明：1961-2010年,绵阳站的年平均气温序列共有1962、1975、1992和2002年4个断点。其中1962年和2002年这2个断点均是由于绵阳站的迁站造成,1975年断点的产生可能是因其附近年份的每日定点观测次数由4次增加到5次,1992年断点则主要是由于该年1、2、3、6月的气温偏低所致。     

基于TIN网的全球选站研究及精密定轨应用

基于不规则三角网（TIN）拓扑关系选站方法,研究卫星精密定轨的精度、效率及测站饱和点的关系。实验表明,在全球布网的条件下,70个跟踪站可完成优于3 cm的精密定轨,且解算效率相比140个跟踪站提升2倍;跟踪站数达到90,精度提升放缓。     

中国地震前兆台网观测曲线动态展示

为了使对地震前兆信息的分析过程更加方便,使用JavaScript语言编制地震曲线图网页,所有网页均由C#程序自动生成,程序连接数据库,每30分钟自动搜索数据更新情况,实时对数据进行更新、绘图.网页包含了所有台站的前兆数据,并且将数据进行分类,在单击台站分布图上的台站热点时,该台站的近期前兆观测曲线图将以网页形式展现出来.同时,每个台站的各个观测分量值也以列表形式排列在台站分布图的下方,其中包含了该分量最近1天、2天、1周、2周、1月的观测曲线,以及近一个月的观测数据的下载.当用户鼠标置于曲线图的任意点上时,可显示出该点对应的坐标值.并且所有曲线图网页均可以保存到本地使用.     

接驳地铁站的共享单车时空均衡性分析与吸引区域优化

共享单车是接驳地铁出行的最有效选择之一,但共享单车的时空分布不均问题对使用者和管理者造成了很大的不便,尤其是早高峰期间出现这种问题更会大大降低2个交通系统的运行效率。因此,研究用于接驳地铁出行的共享单车的时空均衡性特点对提升早高峰期间的通勤效率有一定意义。为了了解接驳地铁骑行的时空均衡性特点,本文以厦门市作为实验区,将厦门市早高峰期间接驳地铁站的骑行作为主要研究对象,基于出行OD提出了新的地铁站吸引区域建立方法,基于出行特点提出了考虑地铁站点的单车聚类方法。本文还从潮汐比统计角度和吸引区域角度对各个地铁站的早高峰整体出行均衡性做了分析,从时空角度对早高峰中不同时段的地铁站接驳骑行的时空均衡性做了分析,通过分析得出了3种角度下各个地铁站点均衡性的相似点与不同点,结果表明：(1)根据潮汐比特点,地铁站对骑行的接驳职能可划分为4类,分别为起始型,均衡型,到达型和不适合接驳地铁出行型,反映了各地铁站点的总体接驳特征;(2)地铁站对接驳骑行的吸引区域与潮汐比特点有所差别,其主要影响因素为地铁站点的地理位置及周边土地利用类型;(3)对于时空均衡性分析结果而言,潮汐比对时空均衡性层面没有显著影响,其...     

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GPSλ?????в???????????????????б??????????????????仯?????????????????????????????????????, ???????????????????????????????????????????м?????п??幹??????????????з????????????????????????????????????????????GPS????е????仯???????????????????????????????Ч????????????????е???????????????????????     

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??????????????????????????ξ????????????2??UGIF???????????GNSS[JP2]???α????????????UGIF????????????÷??????赥????????????UGIF?????????????????μ???α??????????????o??????????й????????????????????????????????????????????????Ч???     

GNSS伪距随机模型估计的非差组合方法

基于非差观测值和无一阶电离层误差、无几何距离的组合准则导出2个UGIF组合,进而提出GNSS[JP2]非差伪距随机模型估计的UGIF非差组合方法。该方法仅需单站、单颗卫星的UGIF组合,适用于高低频情况下的非差伪距随机模型的实时或事后估计。利用中国矿业大学单基站连续运行站双模双频数据,验证方法的正确性与有效性。     

台站迁移对甘肃省气温记录均一性影响的检验

针对气象台站气温观测资料序列存在站址迁移可能造成的资料非均一性影响,利用环县等6个站址迁移气象站的逐年平均气温、平均最高气温、平均最低气温序列,采用SNHT(标准正态检验)客观分析方法,结合6个气象站的元数据及历史沿革资料等信息进行主观分析,对因迁站造成的气温序列不均一性进行检验,表明站址迁移对气温资料影响较大,并且因地理地形环境而有所差异。结果表明:台站迁移后造成新旧站址的地理环境差异显著且海拔高度差异过大,是引起气温序列非均一性的主要原因。地理环境、气候条件相似的台站迁移对气温资料的均一性无明显影响。     

基于测向测时差云闪定位精度分析及布局优化

针对多站雷电定位系统中的云闪定位问题,建立4站云闪辐射源定位模型。根据探测站探测的云闪电磁波到达的时间和角度信息,结合无源定位理论中的测向测时差定位法,给出云闪定位计算方法和精度评定。利用Maltab,仿真探测站不同布站方式下的云闪定位误差分布情况。通过对比研究,得出最优布站形式,并对最优布站形式的精度影响因素进行分析。结果表明,布站形式、基线长度、探测站高度等因素均可对云闪定位精度产生影响。     

北京对外交通枢纽乘客OD时空分布特征

对外交通枢纽对城市内部的客流交通有重大影响,研究其乘客在市内的OD分布对优化设计地面接驳线路、沿线站点等有重要意义。本文基于北京出租车GPS数据,选取具有代表性的3类对外交通枢纽（机场、火车站、汽车客运站）,采用标准差椭圆分析、核密度估计以及分时点统计等方法,研究了北京对外交通枢纽乘客OD时空分布特征。结果表明：（1）机场、火车站客流量远大于汽车客运站,其中首都国际机场与北京西站的对外出行客流量最大,南苑机场和北京北站的对外出行客流量较少;（2）机场乘客主要分布在四环以里大部分地区以及五环以里部分地区,时间上主要分布在除凌晨1-4时的各个时间段;火车站乘客主要分布在四环以里区域,时间上主要分布在6-21时;汽车客运站乘客主要分布在各客运站周边区域,时间上主要集中在6-17时;（3）北京南站与北京西站、北京站间的客流联系较多,可考虑开通北京南站与二者间的地面接驳专线。此外,抵离首都国际机场、南苑机场的乘客主要分布区域与新开通的机场往返市区的巴士线路站点较为一致,说明采用出租车数据进行乘客OD分析可为决策部门进行相关交通规划提供依据。     

Study on the distribution,abundance and growth condition of Antarctic Krill(Euphausia superba)in the Prydz Bay region,Antarctica during the Austral summer of 1999/2000

Antarctic krill (Euphausia superba) were collected from the Prydz Bay region during the austral summer of 1999/2000. The sample - collection was made at 15 sites in 3 longitudinal transects. Although krill were encountered at 14 sites, the abundance was comparatively low in general. The main component of the krill population was of post -larval stages. The mean numerical and weight density of krill integrated for all sampling stations in the survey area were 16. 17 ind. 1000 m -3and 12.02 g 1000 m -3 , respectively. In the survey area, stations with larger krill density are mainly located in the slope zone, except that the largest sample was collected in the open sea zone. No krill occurred in the only station of the shelf zone during our investigation. Krill collected from the slope zone were under better growth condition than those from the open sea zone, but when the survey area is considered as a whole, the growth condition is normal. The results of the comprehensive analysis of the environmental fa     

基于现代大地测量手段的青藏高原南缘地壳形变分析

基于2003~2013年GRACE卫星重力、GPS和绝对重力数据对青藏高原南缘地壳形变进行探讨分析。结果表明,拉萨测站1999~2015年垂向隆升速率为1.5 mm/a,显示出拉萨测站持续隆升的特点。结合南加州综合网络构建的远程连续GPS参考站,另外选择TPLJ、CHLM、JMSM测站数据进行分析。GPS结果表明,4个测站2003~2013年平均隆升速率为2.3±0.11 mm/a,GRACE垂向位移时间序列显示4个测站2003~2013年除季节性变化外也具有轻微上升趋势,平均速率为0.35 mm/a。联合绝对重力资料在考虑诸多因素(地壳隆升、侵蚀、GIA等)后得到拉萨测站近年重力变化约为-0.97 μGal/a,青藏高原拉萨测站地下地壳底部增厚速率约为4.4 cm/a,揭示了青藏高原南部地区的地壳形变特征--地壳隆升与底部增厚。     

基于零膨胀贝叶斯时空建模的精细尺度伪基站垃圾短信分析方法

伪基站垃圾短信活动存在显著的时空自相关和异质性现象,采用时空分析方法可以精准把握伪基站的移动规律和行为模式,为相关部门综合施策、探索长效管理机制提供科学的依据。然而,精细尺度下垃圾短信数据集中过多零数据导致的零膨胀问题,使当前的时空分析方法并不适用。为此,本文以2017年2月23日至2017年4月26日北京市色情服务类垃圾短信数据为例,构建零膨胀贝叶斯时空模型,不仅可以解决零膨胀问题,而且可以综合分析伪基站的空间、时间、时空效应以及外部影响因素,以识别伪基站活动的相对风险高值区、探究城市建成环境对其的影响。结果发现：在数据集中零值占比高达83.46%的情况下,基于零膨胀泊松分布的贝叶斯时空模型具有更好的拟合精度;色情服务类垃圾短信空间上的高风险区域主要聚集在北京市主城区的东部,风险值最高的区域属于朝阳区;周四、五、六风险趋势会相对增加,且18:00至次日02:00为高发时期;伪基站一般18:00从主城区的西南部开始向东北方向移动,凌晨01:00聚集在朝阳区西北部区域;商务住宅与住宿服务类城市环境与垃圾短信呈正相关,餐饮服务与派出所类城市环境呈负相关。研究表明,零膨胀贝叶斯时空模型为精细...     

非潮汐海洋负载效应对近海岸IGS测站坐标时间序列的影响

根据均匀分布在全球各大洲的IGS测站信息,选取105个数据质量良好的近海岸测站以及29个内陆测站,利用ECCO发布的海底压力数据计算得到由非潮汐海洋负载引起的IGS测站位置N、E、U方向上的位移。分析了由地理位置差异导致的测站受非潮汐海洋负载效应的影响存在的差异,并修正了SOPAC提供的IGS测站坐标时间序列,探讨了非潮汐海洋负载效应引起的测站位移对近海岸测站坐标时间序列的影响。结果表明,近海区域（<50 km）测站受到非潮汐海洋负载影响U方向平均量级为5 mm,远大于内陆（>500 km）测站U方向的影响;经过非潮汐海洋负载修正,71%的测站高程坐标时间序列RMS值得以减小,其中最大可使RMS值降低13%;大西洋、太平洋西海岸受其影响比东海岸大,考虑到其受非潮汐海洋负载效应影响显著,使用大西洋与太平洋西海岸地区测站坐标时间序列前必须进行非潮汐海洋负载修正。