“纳沙”台风期间广西白龙尾近岸海域余流特征及产生机制

【目的】研究"纳沙"台风影响期间广西白龙尾近岸海域余流特征及产生机制,为探讨台风作用下近岸余流的变形和强化提供理论依据。【方法】根据"纳沙"台风期间,广西白龙尾近岸一定点S1站的高分辨率连续实测海流剖面资料,对该观测点各层实测流速流向特征和余流流动特点进行研究。【结果】在无台风期间,观测点各层的余流流速一般小于10cm/s,表层的余流流速平均值为5.7cm/s,中层为3.5cm/s,底层为3.1cm/s。最大余流流速,表层为16.3cm/s、中层为14.2cm/s、底层为12.0cm/s。在台风登陆期间,观测点表、中、底层最大余流流速分别为39.7cm/s、32.4cm/s和20.7cm/s,最大流速值可达60.9cm/s,超出正常值3倍以上。随着水深深度的增加,风应力对水体的作用迅速减小,底层低频流流速最大值仅为31.1cm/s。从余流流向分级图可以看出:无台风期间,表层余流流向为WSW向,中层以下流向为NE向,台风登陆期间,余流流向为SW向。【结论】余流流速大小与方向的变化与风、补偿流、地形有密切关系。     

North China sub-craton lithospheric structure elucidated through coal mine blasting

We present a super-range seismic observation along the >1300-km-long profile passing through the Yinchuan basin and the Ordos block from the blasting point towards the southeast triggered by a large-(dynamite) scale coal blast in the Ningxia Hui Autonomous Region’s Helan Mountain (yielded a profile). The seismic wave information from the uppermost mantle reflecting different depths was obtained by the China continental seismic survey. Pn refracted waves from the uppermost mantle were effectively traced up t...     

Crustal P-wave velocity structure in Lower Yangtze region： Reinterpretation of Fuliji-Fengxian deep seismic sounding profile

A deep seismic sounding profile in this paper, from Fuliji in Anhui Province to Fengxian of Shanghai City, is located at eastern China (Fig. 1). The field work was jointly accomplished by the Chinese Geological and Mineral Bureau, the China Seismological …     

A deep seismic sounding profile across the Tianshan Mountains

The deep seismic sounding profile across the Tianshan Mountains revealed a two-layer crustal structure in the Tianshregion, namely the lower and upper crusts. Lateral variations of layer velocity and thickness are evidently shown. Low-velocity layers spread discontinuously at the bottom of the upper crust. The Moho depth is 47 km in the Kuytun area and 50 km in the Xayar area. In the Tianshan Mountains, the Moho becomes deeper with the maximum depth of 62 km around the boundary between the southern and northern Tianshan Mountains. The average velocity ranges from 6.1 to 6.3 km/s in the crust and 8.15 km/s at the top of the upper mantle. Two groups of reliable reflective seismic phases of the Moho (Pm1 and Pm2) are recognized on the shot record section of the Kuytun area. A staked and offset region, 20-30 km long, is displayed within a shot-geophone distance of 190-210 km in Pm1 and Pm2. Calculation shows that the Moho is offset by 10 km in the northern Tianshan region, 62 km deep in the south while 52 km deep in the north, and plunges northwards. In comparison with typical collisional orogenic belts, the structure of the Moho beneath the Tianshan Mountains presents a similar pattern. This can be used to explain the subduction of the Tarim plate towards the Tianshan Mountains. This intracontinental subduction is considered the dynamic mechanism of the Cenozoic uplifting of the Tianshan Mountains. The discovery of seismic phases Pm1 and Pm2 serves as the seismological evidence for the northward subduction of the Tarim plate.     

2012年7月4-5日河南省驻马店暴雨过程分析

利用MICAPS常规资料、NECP再分析资料、雷达回波资料,对2012年7月4-5日河南省驻马店暴雨过程进行诊断分析,资料表明：此次暴雨过程是受副热带高压边缘西南气流和中低层切变线的共同影响,高空槽后带来的冷空气与西南暖湿气流在淮河流域上空交汇,促使不稳定能量爆发,从而产生中小尺度强降水.在新一代天气雷达上,则表现为对流性降水回波,回波呈块状结构,强度大,中心强度为59 dBZ,对流高度12 km .从回波连续演变来看,整个回波云系随着低槽的东移南压,移速25 km/h .径向速度图上,最大负速度入流为-39 m/s,最大正速度出流为24 m/s,入流绝对值远大于出流绝对值,表明测站附近为气流辐合.垂直风廓线图上,最大风速高度6．7 km,最大风速风向198 deg,最大风速18．0 m/s,表明高层有西南气流加入,在4．6 km高度附近有一个明显的垂直切变线.     

Deep crustal structure of Baiyun Sag,northern South China Sea revealed from deep seismic reflection profile

This paper discusses deep crustal architecture of the Baiyun Sag of the Pearl River Mouth Basin, northern South China Sea based on velocity analysis, time-depth conversion and seismic interpretation of the deep seismic reflection profile DSRP-2002. The profile was acquired and processed to 14 S TWT by the China National Offshore Oil Corp. (CNOOC) in 2002. It extends across the Baiyun Sag of the Pearl River Mouth Basin, from the northern continental shelf of the SCS to the deepwater province. As the first deep seismic reflection profile in the Pearl River Mouth Basin, this profile reveals seismic phases from basement down to upper most mantle. The Moho surface appears in the profile as an undulating layer of varying thickness of 1-3 km. It is not a single reflector interface, but a velocity gradient or interconversion layer. The crust thins stepwisely from the shelf to the continental slope and the abyssal plain (from north to south), and also thins under depocenters. The crustal thickness is only 7 km in the depocenter of the main Baiyun Sag, which corresponds to a Moho upwelling mirroring the basement topography. In the lower slope and the ocean-continental transition zone of the southernmost portion of the profile, three sub-parallel, NW-dipping strong reflectors found at depths around 10--21 km are interpreted as indications of a subducted Mesozoic oceanic crust. Crustal faults exist in the northern and southern boundaries of the Baiyun Sag. The intense and persistent subsidence of the Baiyun Sag might be related to the long-term activity of the crustal faults.     

Distribution and identification of the low-velocity layer in the northern South China Sea

The low-velocity layer (LVL), closely related with tectonic activities and dynamic settings, has always been a hot topic in the deep crustal structure studies. The deep seismic (OBS/OBH) and onshore-offshore experiments have been extensively implemented in the northern South China Sea (SCS) since the 1990s. Six seismic profiles were finished on the northern margin of SCS by domestic and international cooperations. The features of crustal structures were revealed and five velocity-inversion layers were discovered. Among them three LVLs with 3.0—3. 5 km·s-1 velocity are located in the sedimentary structure (2.0—6.0 km in depth and 2.0—4. 6 km in thickness) of the Yinggehai Basin and Pearl River Mouth Basin. They were identified by the reflective and refractive phases for their shallow depth. The other two LVLs with 5.5—6.0 km·s-1 velocity generally existed in the middle crust (7.0—18.0 km in depth) with an about 2.5—6.0 km thickness in the transitional crustal structure of the northeastern and northwestern SCS. They were detected by the refractive phase from their overlain and underlying layers. We explored the possible tectonic formation mechanisms combining with previously reported results, which provided evidence for the formation and evolution of SCS.     

长江口外羽状流水体中的垂向混合与层化的观测与分析

摘要：
2002年9月17日17：00至18日17：00,在长江口外E4站位 (122°40′8″E, 30°59′17″N),采用300 kHz声学多普勒流速剖面仪(ADCP)和温盐深仪(CTD)测得连续的水位、流速大小、流向、电导(盐度)和温度等水文资料.基于这些资料,通过文献中相应的公式,估算出水体的密度(ρ)、浮力频率(N)和梯度Richardson数(Ri),并绘制成水流流速分量、盐度、温度、ρ、N和Ri的垂线分布,从而对该站位羽状流水体中的垂向混合与层化进行了研究.结果表明：① 东西向流速分量大小范围为-0.36~0.61 m/s,南北向流速大小范围为-0.59~0.39 m/s.涨急、落急和落憩,流速分量在垂向上变化均不大;涨憩时,表、中、底层流速存在显著差异.② 涨急、涨憩,从表层至底层,盐度随着水深的增加而增大,温度随着水深的增加而减小;落憩,温度在中层达到最大;落急,水体出现显著的密度跃层.③ 该站位表层水体的N均较小,基本在10-3 s-1量级,水体垂向混合较好;中、下层水体的N出现10-2 s-1量级,混合相对较弱.④ 该站位水体垂向混合强度呈现涨、落潮周期变化：涨急、涨憩,Ri范围在10-2 ~101量级,混合较好;落急,Ri在中下层水体出现102量级,水体出现显著层化;落憩,整个水体的Ri大部分都小于临界值0.25,水体混合最充分.
关键词：
长江口外; 羽状流; 浮力频率; 梯度 Richardson数; 混合; 层化
中图分类号： P 731.26
文献标志码： A     

Lithospheric thermal-rheological structures of the continental margin in the northern South China Sea

Thermal structures of three deep seismic profiles in the continental margin in the northern South China Sea are calculated, their "thermal" lithospheric thicknesses are evaluated based on the basalt dry solidus, and their rheological structures are evaluated with linear frictional failure criterion and power-law creep equation. "Thermal" lithosphere is about 90 km in thickness in shelf area, and thins toward the slope, lowers to 60-65 km in the lower slope, ocean crust and Xisha Trough. In the mid-west of the studied area, the lithospheric rheological structure in shelf area and Xisha Islands is of four layers: brittle, ductile, brittle and ductile. Because of uprising of heat mantle and thinning of crust and lithosphere in Xisha Trough, the bottom of the upper brittle layer is only buried at 16 km. In the eastern area, the bottom of the upper brittle layer in the north is buried at 20 km or so, while in lower slope and ocean crust, the rheological structure is of two layers of brittle and ductile, and crust and uppermost mantle form one whole brittle layer whose bottom is buried at 30-32 km. Analyses show that the characteristics of rheological structure accord with the seismic result observed. The character of rheological stratification implies that before the extension of the continent margin, there likely was a ductile layer in mid-lower crust. The influence of the existence of ductile layer to the evolution of the continent margin and the different extensions of ductile layer and brittle layer should not be overlooked. Its thickness, depth and extent in influencing continent margin's extension and evolution should be well evaluated in building a dynamic model for the area.     

The vertical profile of winds on Titan

One of Titan's most intriguing attributes is its copious but featureless atmosphere. The Voyager 1 fly-by and occultation in 1980 provided the first radial survey of Titan's atmospheric pressure and temperature and evidence for the presence of strong zonal winds. It was realized that the motion of an atmospheric probe could be used to study the winds, which led to the inclusion of the Doppler Wind Experiment on the Huygens probe. Here we report a high resolution vertical profile of Titan's winds, with an estimated accuracy of better than 1 m s(-1). The zonal winds were prograde during most of the atmospheric descent, providing in situ confirmation of superrotation on Titan. A layer with surprisingly slow wind, where the velocity decreased to near zero, was detected at altitudes between 60 and 100 km. Generally weak winds (approximately 1 m s(-1)) were seen in the lowest 5 km of descent.     

Deep structure at northern margin of Tarim Basin

In this paper, a 2D velocity structure of the crust and the upper mantle of the northern margin of the Tarim Basin （TB） has been obtained by ray tracing and theoretical seismogram calculation under the condition of 2D lateral inhomogeneous medium using the data of seismic wide angle reflection/refraction profile from Baicheng to Da Qaidam crossing the Kuqa Depression （KD） and Tabei Uplift （TU）. And along the Baicheng to Da Qaidam profile, 4 of the 10 shot points are located in the northern margin of the TB. The results show that the character of the crust is uniform on the whole between the KD and TU, but the depth of the layers, thickness of the crust and the velocity obviously vary along the profile. Thereinto, the variation of the crust thickness mainly occurs in the middle and lower crust. The Moho has an uplifting trend near the Baicheng shot point in KD and Luntai shot point in TU, and the thickness of the crust reduces to 42 km and 47 km in these two areas, respectively. The transition zone between the KD and TU has a thickest crust, up to 52 km. In this transition zone, there are high velocity anoma- lies in the upper crust, and low velocity anomalies in the lower crust, these velocity anomalies zone is near vertical, and the sediment above them is thicker than the other areas. According to the velocity distributions, the profile can be divided into three sections： KD, TU and transition zone between them. Each section has a special velocity structural feature, the form of the crystalline basement and the relationship between the deep structure and the shallow one. The differences of velocity and tectonic between eastern and western profile in the northern margin of the Tarim Basin （NMTB） may suggest different speed and intensity of the subduction from the Tarim basin to the Tianshan orogenic belt （TOB）.     

Ti—TiC激光熔覆层的形成及其表征

为分析激光熔覆法制备TiC／Ti复合材料显微形貌的成因,对功率密度为21．2kW／cm^2、扫描速度15mm／s的CO2激光作用下的Ti-6A1—4V合金表面进行了Ti＋TiC激光熔覆实验,并对其熔覆层温度波动进行了分析。采用XRD、SEM对Ti-4-TiC熔覆层进行表征,并测定熔覆层的显微维氏硬度。分析表明：用激光熔覆制备TiC／Ti复合材料时,熔覆层在数毫秒内熔化,并以约10^4℃／s速率初始冷却。熔覆层的维氏硬度高达10．8GPa,Ti填充杂乱的TiC枝晶间。熔覆层与基体具有良好的冶金结合,且热影响区厚度与经验计算值相近。     

磨刀门水道枯季底边界层的泥沙交换过程

河口底边界层细颗粒泥沙运动往往受边界层内多种尺度的动力过程影响而变得十分复杂。由此,基于座底支架上的ADV与OBS,于2010年枯季在珠江磨刀门水道分别进行大、中、小潮的底边界层观测,对磨刀门水道底边界层湍流动力特征与小尺度泥沙交换过程进行研究。结果表明:悬沙有效沉速、床面切应力与底床侵蚀率的变化范围随着潮差的增大而增大;底床侵蚀率与平均流速变化规律相似,当流速小于0.3 m/s时,侵蚀率基本保持在0.002 kg/m2左右,流速超过此临界值时,床面泥沙发生再悬浮。悬沙和床沙交换过程随着潮差增大而增强,且落潮时段强于涨潮时段。     

九寨沟九寨天堂泥石流沟特征分析与模拟预测

本文通过现场勘查、数值模拟、遥感影像解译查流域内地质灾害数目、物源特征和成因机理等。基于无人机测量数据选取Massflow软件中的Voellmy模型进行数值模拟,模拟泥石流10年一遇物源量、流速和堆积范围,根据模拟参数预测50年和100年一遇泥石流特征。模拟结果表明：10年一遇平均速度6.5 m/s,堆积范围0.103 km2,实际堆积面积0.096 km2。研究结论：流域下伏地层岩石破碎,容易形成松散堆积体,表层松散颗粒极易被雨水带入沟域内形成泥石流;河流改道致使沟谷对岸岸坡坡脚受泥石流侵蚀现象严重,岸坡整体稳定性下降可能性增大,局部有崩滑现象,严重威胁对岸301省道的通行安全。     

Evidence for fault weakness and fluid flow within an active low-angle normal fault.

Determining the composition and physical properties of shallow-dipping, active normal faults (dips < 35 degrees with respect to the horizontal) is important for understanding how such faults slip under low resolved shear stress and accommodate significant extension of the crust and lithosphere. Seismic reflection images and earthquake source parameters show that a magnitude 6.2 earthquake occurred at about 5 km depth on or close to a normal fault with a dip of 25-30 degrees located ahead of a propagating spreading centre in the Woodlark basin. Here we present results from a genetic algorithm inversion of seismic reflection data, which shows that the fault at 4-5 km depth contains a 33-m-thick layer with seismic velocities of about 4.3 km s(-1), which we interpret to be composed of serpentinite fault gouge. Isolated zones exhibit velocities as low as approximately 1.7 km s(-1) with high porosities, which we suggest are maintained by high fluid pressures. We propose that hydrothermal fluid flow, possibly driven by a deep magmatic heat source, and high extensional stresses ahead of the ridge tip have created conditions for fault weakness and strain localization on the low-angle normal fault.     

Zero outward flow velocity for plasma in a heliosheath transition layer

Voyager 1 has been in the reservoir of energetic ions and electrons that constitutes the heliosheath since it crossed the solar wind termination shock on 16 December 2004 at a distance from the Sun of 94 astronomical units (1?AU = 1.5?×?10(8)?km). It is now ～22?AU past the termination shock crossing. The bulk velocity of the plasma in the radial-transverse plane has been determined using measurements of the anisotropy of the convected energetic ion distribution. Here we report that the radial component of the velocity has been decreasing almost linearly over the past three years, from ～70?km?s(-1) to ～0?km?s(-1), where it has remained for the past eight months. It now seems that Voyager 1 has entered a finite transition layer of zero-radial-velocity plasma flow, indicating that the spacecraft may be close to the heliopause, the border between the heliosheath and the interstellar plasma. The existence of a flow transition layer in the heliosheath contradicts current predictions--generally assumed by conceptual models--of a sharp discontinuity at the heliopause.     

Variable diffusion boundary layer and diffusion flux at sediment-water interface in response to dynamic forcing over an intertidal mudflat

The diffusion boundary layer (DBL) significantly limits the exchange between sediment and overlying water and therefore becomes a bottleneck of diffusive vertical flux at the sediment-water interface (SWI). Variable DBL thickness and diffusion flux in response to dynamic forcing may influence replenishment of nutrients and secondary pollution in coastal waters. In situ measurements of velocity in the bottom boundary layer (BBL) and oxygen concentration in the DBL were made over an intertidal mudflat, using an acoustic Doppler current and mini profiler. A linear distributed zone in the oxygen profile, the profile slope discontinuity and variance of concentration can be used to derive accurate DBL thickness. Diffusion fluxes calculated from the water column and sediment are identical, and their bias is less than 6%. A numerical model PROFILE is used to simulate the in situ dissolved oxygen profile, and layered dissolved oxygen consumption rates in the sediment are calculated. The DBL thickness (0.10-0.35 mm) and diffusion flux (15.4-53.6 mmol m 2 d 1) vary with a factor of 3.5 during a tidal period. Over an intertidal mudflat, DBL thickness is controlled by flow speed U in the BBL, according to δDBL=1686.1DU 1+0.1 (D is the molecular diffusion coefficient). That is, the DBL thickness δDBL increases with decreasing flow speed U. Changes of diffusion flux at the SWI are caused by variations in the water above the sediment and the turbulent mixing intensity. The diffusion flux is positively related to the turbulent dissipation rate, friction velocity and turbulent energy. Under the influence of dynamics in the BBL, DBL thickness and flux vary significantly.     

加速度不对称波浪作用下的底部边界层动力特性

为了研究加速度不对称波浪对底部边界层的影响,建立加速度不对称波浪作用下的底部边界层数学模型,复演物理模型试验中的流速剖面、紊动强度和床面剪切应力,在此基础上探讨加速度不对称波浪边界层的动力特性。结果表明,波峰半周期内正向加速阶段的加速度比较大,引起较快的边界层发育、较大的流速梯度和较大的紊动能量,产生了正向的周期平均床面剪切应力;这些现象随加速度不对称系数的增大而更加明显;在振荡水槽中,加速度不对称波浪边界层内存在底部反向和顶部正向的时均流动,加速度不对称系数的增大会增强底部反向流速;在开敞水域中,时均流速在整个边界层内都是正向的,底部出现"流速外突"的现象,顶部流速趋于均匀分布,加速度不对称系数的增大会减弱底部正向流速。     

鄂尔多斯志丹地区延长组高分辨率层序地层模式探讨

根据岩心、野外露头、测井、录井岩性等资料,在高分辨率层序地层学理论体系的指导下,按照适合陆相盆地层序特征的研究思路,对鄂尔多斯盆地陕北斜坡带志丹地区延长组地层特征进行了研究。对志丹地区延长组不同相带、不同旋回中岩性组合特征进行分析,总结出了该地区延长组层序界面的类型和识别特征;并对延长组基准面旋回特征进行讨论和长期基准面旋回的划分。最后在此基础上提出志丹地区延长组长10—长4+5时期的高分辨率层序地层模式。认为延长组从下至上可以划分为四个长期基准面旋回,其中LSC1对应长10和长9油组;LSC2对应长8和长7油组;LSC3对应长6和长4+5油组;LSC4对应长3、长2和长1油组。LSC3生储盖组合配置良好,且处于油气运移的有利指向上,是志丹地区主要的产油层段。     

陶瓷纤维增强混凝土高温损伤的超声特性

通过超声波检测和抗压强度试验对高温后陶瓷纤维增强混凝土（CFRC）的损伤特性进行了研究,分析了加热温度和冷却方式对抗压强度、纵波波速和主频带来的影响。分析表明,随着温度的升高,CFRC性能不断劣化,抗压强度、纵波波速及主频总体呈下降趋势;400 ℃为CFRC性能突变的临界温度,400 ℃之前,其劣化程度较小,且抗压强度与主频在400 ℃时有所回升,400 ℃之后,劣化速率明显增大,结构性能急剧下降;同自然冷却情况相比,浇水冷却后CFRC各项性能指标下降更为严重;纵波波速在1.0～3.5 km/s内与抗压强度具有正相关性,在3.5～4.5 km/s内两者相关性不确定。利用纵波波速定义的损伤变量能较好地反映高温后CFRC内部损伤的演化规律。