石城断裂性质与活动情况简介     

李怀永  郭东晓 《城市地质》2010,5(2):45-46

本文简单总结与介绍了怀柔—密云境内,石城断裂的规模、性质与活动性。初步认为该断裂属脆韧性剪切带,与云蒙山岩体上侵有关,早期压性,晚期显张性,属非全新世活动断裂,对工程影响程度低。  相似文献   

Field-observation for an anticyclonic mesoscale eddy consisted of twelve gliders and sixty-two expendable probes in the northern South China Sea during summer 2017     

Yeqiang SHU  Ju CHEN  Shuo LI  Qiang WANG  Jiancheng YU  Dongxiao WANG 《中国科学:地球科学(英文版)》2019,(2)

An intensive field observation experiment using 12 Chinese gliders equipped with conductivity-temperature-depth (CTD) sensors and 62 expendable CTD probes (XCTDs) was performed to investigate the 3-D structure and time evolution of an anticyclonic eddy in the northern South China Sea (NSCS). The observed results showed that the anticyclonic eddy had a horizontal radius of about 80 km at surface and a vertical depth of impact of more than 1000 m. The largest temperature and salinity anomalies compared with the averaged values of the temperature and salinity profiles were 3.5°C and 0.4 psu at 120 m depth, respectively. Combined analysis of altimeter sea level and water mass properties indicated that the anticyclonic eddy was shed from the Kuroshio loop current. The vertical axis of the anticyclonic eddy tilted from surface to the observed maximum depth (1000 m) along its translation direction against the 2000 m isobath. The center of the anticyclonic eddy remained in the region east of Dongsha Island for more than half a month. During this time, the long axis direction of the eddy changed from across the slope to along the slope. Then, the eddy moved southward along the 2000 m isobaths. Both the geostrophic current and temperature distribution revealed that the eddy intensity weakened during the observation period gradually. These observations indicated strong interaction between the anticyclonic eddy and the slope topography of Dongsha Island.  相似文献   

太平洋中的主要起伏模态     

彭启华  黄瑞新  王卫强  王东晓 《热带海洋学报》2020,39(2):1-10

对海洋中起伏运动(heaving)信号的时空分布研究能够帮助我们更好地了解气候系统中的年际和年代际变率。文章通过再分析资料和模式对太平洋区域的heaving主要模态进行了研究。研究结果表明: 太平洋区域主要存在两种heaving模态: 第一模态主要表现为赤道东西两侧的温跃层异常信号反位相; 第二模态表现为赤道区域和副热带区域的温跃层异常信号呈现反位相变化的规律。本文对这两个主要heaving模态所涉及的物理过程进行详细讨论, 结果表明: 东西反位相模态主要是受赤道波动调节的结果; 而经向结构模态则主要是由赤道地区的波动和副热带区域的风应力旋度异常作用共同导致。此外, 我们还讨论了heaving模态可以通过海洋波动以及Ekman输送等过程对海盆尺度的热输送(振幅约为5×10¹⁴W)以及海洋热含量(振幅约为1.5×10²⁰J)的再分配起到了关键的调制作用, 进一步表明heaving模态对全球气候变化有着重要的作用。  相似文献   

Role of wind forcing and eddy activity in the intraseasonal variability of the barrier layer in the South China Sea     

Zhanlin Liang  Qiang Xie  Lili Zeng  Dongxiao Wang 《Ocean Dynamics》2018,68(3):363-375

In addition to widely discussed seasonal variability, the barrier layer (BL) of the South China Sea (SCS) also exhibits significant intraseasonal variability (ISV) and plays an important role in the upper heat and salt balances. The characteristics and mechanisms of spatiotemporal variations in the BL are investigated using an eddy-resolving ocean model OFES (OGCM For the Earth Simulator) ouput and related atmospheric and oceanic processes. The active intraseasonal BL variability in the SCS occurs mainly during the late summer/autumn and winter and exhibits remarkable differences between these two periods. The BL ISV in late summer/autumn occurs in the southern basin, while in winter, it is limited to the northwestern basin. To further discuss the evolution and driving thermodynamic mechanisms, we quantify the processes that control the variability of intraseasonal BL. Different mechanisms for the intraseasonal BL variability for these two active periods are investigated based on the case study and composite analysis. During late summer/autumn, the active BL in the southern basin is generated by advected and local freshwater, and then decays rapidly with the enhanced wind. In winter, anticyclonic eddy activity is associated with the evolution of the BL by affecting the thermocline and halocline variations, while wind stress and wind stress curl have no obvious influence on BL.  相似文献   

A three-dimensional modeling study on eddy-mean flow interaction between a Gaussian-type anticyclonic eddy and Kuroshio   总被引：1，自引：0，他引：1  

Wu Geng  Qiang Xie  Gengxin Chen  Qinyan Liu  Dongxiao Wang 《Journal of Oceanography》2018,74(1):23-37

The Princeton ocean model is employed to study the energy balance of a fast-moving anticyclonic eddy (AE) during eddy-mean flow interaction. The AE is initialized with an axisymmetric Gaussian-type temperature profile and is placed to the east of the Philippine Islands. An energy analysis suggests that the advection term, pressure work and friction term play dominant roles in the initial eddy decay. During the strong interaction stage, barotropic instability (BTI) becomes the main force for the eddy kinetic energy (EKE) production, with the largest positive BTI in the interaction zone, which means that the eddy always obtains kinetic energy from the Kuroshio during this stage. Most of the EKE dissipation, the large conversion from the eddy available potential energy to the EKE and that from the mean kinetic energy to the EKE all occur at the upper layer during the strong interaction stage. When the AE interacts with the mean flow on the eastern side of the Kuroshio, whether the AE gains kinetic energy from the Kuroshio or loses kinetic energy to the Kuroshio is mainly determined by its shape in the interaction zone.  相似文献   

印度洋-太平洋海温的年际、年代际异常及其对亚洲季风的影响   总被引：26，自引：5，他引：26  

徐建军  王东晓 《海洋学报》2000,22(3):34-43

运用EOF分析方法,对近50a的印度洋-太平洋SST的年际、年代际变化特征进行了分析,并在此基础上进行了数值试验.研究表明:在近50a中,SST的第一气候模态与年代际尺度变化相对应,并经历了两次气候突变,分别在1956年和1976年前后.第二气候模态与ENSO事件相对应,其空间分布反映了厄尔尼诺发生时SST的异常分布.中国东部降水以及亚洲季风异常不仅与ENSO事件有关,而且受到年代际气候背景场的影响.诊断和模拟结果具有较好的一致性.  相似文献   

南海表层水温年际变化的大尺度特征   总被引：22，自引：2，他引：22  

王卫强  王东晓  齐义泉 《海洋学报》2000,22(4):8-16

通过对COADS海洋气象资料的分析,得出南海表层水温(SST)年际变化的若干大尺度特征.结果表明:南海SST年际具有一定的准周期性,其显著周期为24～30个月;南海SST年际变化与年循环之间有着一种锁相关系,关键位相在于北半球冬春季节;南海典型冷暖年份合成SST距平场的时空结构十分相似;在年际时间尺度上,南海SST和南方涛动指数有反相关系,与经向风海面热收支之间有同位相关系;南海暖池面积指数的年际变化与南海SST年际变化一致.  相似文献   

A case study of near-inertial oscillation in the South China Sea using mooring observations and satellite altimeter data   总被引：9，自引：0，他引：9  

Lu Sun  Quanan Zheng  Dongxiao Wang  Jianyu Hu  Chang-Kuo Tai  Zhenyu Sun 《Journal of Oceanography》2011,67(6):677-687

A near-inertial oscillation (NIO) burst event in the west South China Sea (SCS) was observed by an upward-looking mooring Acoustic Doppler Current Profiler (ADCP) in summer 2004. The mooring station was located at 13.99°N, 110.52°E. The spectral analysis reveals that typhoon Chanchu is a major mechanism in triggering the NIO burst event. Before typhoon Chanchu passed over, the NIO signals were quite weak. The NIO band becomes the most energetic constituent of the circulation during the typhoon-wake period. The average peak power density (PD) reaches (5.3 ± 2.6) × 10² cm² s⁻² (cycles per hour, cph)⁻¹ with a maximum value of 9.0 × 10² cm² s⁻² cph⁻¹, i.e., 3.1 times higher than that of diurnal tide (DT), (1.7 ± 0.5) × 10² cm² s⁻² cph⁻¹. At the upper (80 m) and sub-upper (208 m) layers, the central frequency of the NIO band is 0.022 cph with a blueshift of about 9% above the inertial frequency f (0.02015 cph). At the lower layer (400 m), the central frequency of the NIO band is 0.021 cph with a blueshift of about 4% above the inertial frequency. The blueshifts are explained partially by the Doppler shift induced by the vorticity of mesoscale eddies. During the after-typhoon period, a resonance-like process between NIO and DT is observed in the upper layer. As the NIO frequency approaches the DT subharmonic frequency (0.5K₁), the PD of the NIO band rises sharply accompanied by a sharp drop of the PD of the DT band. The PD ratio of the two bands increases from 4.5 during the typhoon-wake period to 8 during the after-typhoon period, indicating the effect of the parametric subharmonic instability (PSI) mechanism.  相似文献   

The characteristic differences of tropical cyclones forming over the western North Pacific and the South China Sea   总被引：5，自引：1，他引：4  

YUAN Jinnan  WANG Dongxiao  LIU Chunxi  HUANG Jian  HUANG Huijun 《海洋学报(英文版)》2007,26(4):29-43

The best track dataset of tropical cyclones in the western North Pacific (WNP) and the South China Sea (SCS) from 1977 to 2005 during the satellite era, the NCEP/NCAR reanalysis dataset and the extended reconstructed sea surface temperature dataset are employed in this study. The main climatological characteristics of tropical cyclone formation over the WNP and the SCS are compared. It is found that there is obviously different for the locations of tropical cyclone origins, achieving the lowest central pressure and termination points between over the WNP and over the SCS. The annual number of tropical cyclones forming over the SCS is obviously less than over the WNP, and there is a significant negative correlation with the correlation coefficient being -0.36 at the 5% significance level between over the WNP and over the SCS. The mean speed of tropical cyclone moving is 6.5 m /s over the WNP and 4.6 m /s over the SCS. The mean lowest central pressure of tropical cyclones is obviously weaker over the SCS than over the WNP. The tropical cyclone days per year, mean total distance and total displacement of tropical cyclone traveled over the WNP are all obviously longer than those over the SCS. Tropical cyclone may intensify to Saffir-Simpson hurricane scale 5 over the WNP, but no tropical cyclone can intensify to Saffir-Simpson hurricane scale 3 over the SCS. The changing ranges of the radii(R15,R16) of the 15.4 m /s winds them and the 25.7 m /s winds over the WNP are obviously wider than those over the SCS, and the median values of the radii over the WNP are also larger than those over the SCS. For the same intensity of tropical cyclones, both radii have larger medians over the WNP than over the SCS. The correlations of annual mean tropical cyclone size parameters between over the WNP and over the SCS are not significant. At the same time, the asymmetric radii of tropical cyclones over the WNP are different from those over the SCS.  相似文献