东风带扰动影响西太平洋副热带高压短期东西向移动的热力强迫分析

利用NCEP/NCAR 1 000～10 hPa 2.5 °×2.5 °日平均再分析资料,分析2003年6月22—25日热带对流层上空东风带扰动影响西太平洋副热带高压（简称西太副高,下同）短期东西进退的热力强迫过程,并探讨了相应机制。结果表明:东风带扰动附近非绝热效应分布和强度的变化影响着西太副高东西向的运动;西太副高短期东西向移动有趋“冷”的趋势,即西太副高向非绝热加热减弱或者非绝热冷却增强方向移动;在西太副高突然东退前后,东风带扰动东、西侧的非绝热加热效应出现明显的变化,主要体现为东风带扰动东侧非绝热冷却效应增强和东风带扰动西侧非绝热冷却效应减弱东退的特征,而且在对流层300 hPa高度附近表现最为明显;在非绝热加热效应影响因子中,垂直输送项最为重要,其次为局地变化项,水平平流效应最不显著,因此,垂直输送作用和局地变化作用引起的非绝热效应的变化是影响西太副高突然东退的主要原因。      

20世纪90年代初东亚夏季风的年代际转型

利用1979—2009年JRA-25和NCEP/NCAR再分析资料,通过复矢量经验正交方法揭示了东亚地区夏季850 hPa风场变率的优势模态。结果表明:两套再分析资料所揭示的东亚夏季风在20世纪90年代初均发生了年代际转型,与我国夏季降水的年代际转型时间一致。伴随着东亚夏季风的年代际转型,我国北方大部分地区夏季降水减少,尤其是我国东北北部和长江、黄河之间105°E附近区域显著减少,而华南地区和淮河流域降水显著增加。从动力上解释我国夏季降水年代际转型特征,夏季500 hPa高度场两个时段 (1993—2009年和1979—1992年) 的差值分布显示为欧亚大陆北部准纬向遥相关波列,夏季850 hPa风场差值分布表现为贝加尔湖东南侧和日本以南地区存在两个异常反气旋式环流,而我国南方地区和鄂霍次克海附近均为异常气旋式环流。夏季西北太平洋、北印度洋以及部分中高纬度海洋的海温和春季欧亚大陆积雪在20世纪90年代初出现显著变化,春季北极海冰的年代际转型发生在20世纪90年代初,都可能成为东亚夏季风年代际转型的原因。     

Phase Equilibria Constraints on Relations of Ore-bearing Intrusionswith Flood Basalts in the Panxi Region, Southwestern China

There are two types of temporally and spatially associated intrusions within the Emeishan large igneous province (LIP); namely, small uitramafic subvolcanic sills that host magmatic Cu-Ni-Platinum Group Element (PGE)-bearing sulfide deposits and large mafic layered intrusions that host giant Ti-V magnetite deposits in the Panxi region. However, except for their coeval ages, the genetic relations between the ore-bearing intrusions and extrusive rocks are poorly understood. Phase equilibria analysis (Q-PI-OI-Opx-Cpx system) has been carried out to elucidate whether ore-bearing Panzhihua, Xinjie and Limahe intrusions are co-magmatic with the picrites and flood basalts (including high-Ti, low-Ti and alkali basalts), respectively. In this system, the parental magma can be classified as silica-undersaturated olivine basalt and silica-saturated tholeiite. The equivalents of the parental magma of the Xinjie and Limahe peridotites and picrites and iow-Ti basalts are silica-undersaturated, whereas the Limahe gabbro-diorites and high-Ti basalts are silica-saturated. In contrast, the Panzhihua intrusion appears to be alkali character. Phase equilibria relations clearly show that the magmas that formed the Panzhihua intrusion and high-Ti basalts cannot be co-magmatic as there is no way to derive one liquid from another by fractional crystallization. On the other hand, the Panzhihua intrusion appears to be related to Permian alkali intrusions in the region, but does not appear to be related to the alkali basalts recognized in the Longzhoushan lava stratigraphy. Comparably, the Limabe intrusion appears to be a genetic relation to the picrites, whereas the Xinjie intrusion may be genetically related to be low-Ti basaits. Additionally, the gabbro-diorites and peridotites of the Limahe intrusion are not co-magmatic, and the former appears to be derived liquid from high-Ti basalts.     

Identification method of weak seismic phases on the basis of wavelet packet transform

This paper describes a sort of new method identifying seismic phase by the name of wavelet packet transform. Perfectness and development of the wavelet packet transform is based upon the idea of its multiscale analysis. The method of wavelet packet transform can depict the anomalous changes information of transient spectra of seismic wave onset, and come true the target of identifying seismic phase especially weak seismic phase. Then this paper presents discriminating examples of simulating digital signals and actual seismic phase. Compared with conventional seismic phase discrimination, studied results show that the wavelet packet transform method is an available tool of weak signal analyses, and have unexampled merits and attractive application foreground. This research gets hold of Higher School Doctor Scientific Research Foundation (No. 157 WJ0704 9435611) and supported by the National Natural Science Foundation (No. 49474211).     

南海东北部洋陆过渡区域地震折射波衰减特征

地震波衰减研究是了解岩石圈构造特征的有效方法.本文基于OBS2016-2测线的海底地震仪(OBS)数据, 首次对南海东北部洋陆过渡区域地震波衰减特征进行研究, 通过正演模拟获得该区域二维纵波衰减(Q_P)结构.结果表明, 下陆坡的上地壳存在一个宽约40 km, 厚度约为4~5 km的高衰减区, 其特征为低纵波和横波速度(V_P为5.5~6.3 km·s^-1和V_S为3.1~3.6 km·s^-1)以及较低的波速比(V_P/V_S为1.72~1.80), 对应较低的Q_P(280~410), 推测与断裂发育有关, 且受到火山活动的影响.洋陆过渡及洋壳区域的上地壳高衰减区具有低Q_P(300~400)和高V_P/V_S(1.90~1.96)特征, 可能对应较多的断裂发育及流体运移.洋陆过渡区域下地壳高速异常体表现为相对低的Q_P(550~600), 对应较高的V_P(7.0~7.8 km·s^-1)和V_S(3.5~3.8 km·s^-1)以及较高的V_P/V_S(1.85~1.96), 推测与蛇纹石化作用有关.蛇纹石化可能进一步增加岩石的孔隙度并导致更多的流体运移, 使得洋陆过渡及洋壳区域存在较高的地震波衰减.Q_P结构有助于我们分析南海大陆边缘的地震波衰减特征, 结合V_P、V_S以及V_P/V_S, 可以更好地了解该区域地质结构和岩石属性, 对进一步挖掘OBS数据信息有重要参考价值.

     

Spatial and temporal distribution patterns of deep‐sea mesozooplankton in the eastern Mediterranean – indications of a climatically induced shift?

Zooplankton samples from the eastern Mediterranean were collected in April/May 1999 with a multiple opening and closing net (mesh size 333 μm) to examine the distribution and taxonomic composition of mesozooplankton, mainly Calanoida (Copepoda), some years after the onset of the Eastern Mediterranean Transient (EMT), a climatically induced shift in hydrography. The samples from seven stations on a transect from the Ionian Sea to the eastern part of the Levantine Basin were collected at closely spaced vertical intervals from the surface to water depths of 4250 m. Data from January 1987, June 1993, January 1998 and October 2001 from the main site of investigation, south of Crete, were used to describe the temporal evolution before (1987), during (1993) and after (1998–2001) the EMT. The eastern Mediterranean mesozooplankton fauna is dominated by three Calanoida species along the west–east transect, with varying abundances in different depth‐zones: Haloptilus longicornis in the epipelagic zone, Eucalanus monachus in the mesopelagic zone, and Lucicutia longiserrata in the bathypelagic zone. A drastic change in mesozooplankton composition and abundance occurred at the main site during the EMT, whereupon increased abundances of Candacia elongata and L. longiserrata were observed in the bathypelagic zone in the following years; L. longiserrata accounted for 43% of the total mesozooplankton in this zone. The hypothesis is posed that the Mediterranean deep‐sea ecosystem is able to respond quickly to changes in the environment and memorizes these changes over time. We claim that the biological effects of climatically induced changes can be easily monitored in the deep eastern Mediterranean Sea using calanoid copepod key species due to the hydrographically extreme, but ‘simply structured’ ecosystem.     

伪近邻方法在ARMA系统阶数判别中的应用

从相空间重构的角度,提出利用伪近邻方法判别ＡＲＭＡ 系统的总阶数。该方法可在数据量较小和阈值固定的情况下判别ＡＲＭＡ 系统总阶数。数值计算表明,使用该方法判别线性ＡＲＭＡ系统总阶数,取得了比较满意的结果。     

Observations and modelling of the travel time delay and leading negative phase of the 16 September 2015 Illapel,Chile tsunami

The systematic discrepancies in both tsunami arrival time and leading negative phase (LNP) were identified for the recent transoceanic tsunami on 16 September 2015 in Illapel, Chile by examining the wave characteristics from the tsunami records at 21 Deep-ocean Assessment and Reporting of Tsunami (DART) sites and 29 coastal tide gauge stations. The results revealed systematic travel time delay of as much as 22 min (approximately 1.7％ of the total travel time) relative to the simulated long waves from the 2015 Chilean tsunami. The delay discrepancy was found to increase with travel time. It was difficult to identify the LNP from the near-shore observation system due to the strong background noise, but the initial negative phase feature became more obvious as the tsunami propagated away from the source area in the deep ocean. We determined that the LNP for the Chilean tsunami had an average duration of 33 min, which was close to the dominant period of the tsunami source. Most of the amplitude ratios to the first elevation phase were approximately 40％, with the largest equivalent to the first positive phase amplitude. We performed numerical analyses by applying the corrected long wave model, which accounted for the effects of seawater density stratification due to compressibility, self-attraction and loading (SAL) of the earth, and wave dispersion compared with observed tsunami waveforms. We attempted to accurately calculate the arrival time and LNP, and to understand how much of a role the physical mechanism played in the discrepancies for the moderate transoceanic tsunami event. The mainly focus of the study is to quantitatively evaluate the contribution of each secondary physical effect to the systematic discrepancies using the corrected shallow water model. Taking all of these effects into consideration, our results demonstrated good agreement between the observed and simulated waveforms. We can conclude that the corrected shallow water model can reduce the tsunami propagation speed and reproduce the LNP, which is observed for tsunamis that have propagated over long distances frequently. The travel time delay between the observed and corrected simulated waveforms is reduced to <8 min and the amplitude discrepancy between them was also markedly diminished. The incorporated effects amounted to approximately 78％ of the travel time delay correction, with seawater density stratification, SAL, and Boussinesq dispersion contributing approximately 39％, 21％, and 18％, respectively. The simulated results showed that the elastic loading and Boussinesq dispersion not only affected travel time but also changed the simulated waveforms for this event. In contrast, the seawater stratification only reduced the tsunami speed, whereas the earth's elasticity loading was responsible for LNP due to the depression of the seafloor surrounding additional tsunami loading at far-field stations. This study revealed that the traditional shallow water model has inherent defects in estimating tsunami arrival, and the leading negative phase of a tsunami is a typical recognizable feature of a moderately strong transoceanic tsunami. These results also support previous theory and can help to explain the observed discrepancies.     

Unconventional geometric phase gate and multiqubit entanglement for hot ions with a frequency-modulated field

We present an alternative scheme for implementing the unconventional geometric two-qubit phase gate and preparing multiqubit entanglement by using a frequency-modulated laser field to simultaneously illuminate all ions. Selecting the index of modulation yields selective mechanisms for coupling and decoupling between the internal and the external states of the ions. By the selective mechanisms, we obtain the unconventional geometric two-qubit phase gate, multiparticle Greenberger--Horne--Zeilinger states and highly entangled cluster states. Our scheme is insensitive to the thermal motion of the ions.     

基于数字全息显微的海洋浮游生物三维形貌快速重建方法研究

针对海洋浮游生物实时探测中,三维形貌特征难以快速获取的问题,本文提出了一种海洋浮游生物三维形貌快速重建的方法。基于离轴菲涅尔数字全息显微系统,通过改进相位恢复方法预消除相位畸变,直接得到正确的相位信息,进而对浮游生物三维形貌重建。该方法不需要进行后期复杂的相位补偿计算,就可以对浮游生物三维形貌进行快速重建,有利于对动态、微小尺寸的浮游生物进行实时探测及分析。论文对青岛近海岸浮游生物桡足类和夜光虫进行了三维形貌重建,分辨率可达到3.5μm。实验结果为离轴菲涅尔数字全息显微系统用于海洋浮游生物原位、实时探测的可行性提供了依据。