基于多源探测资料的一次广州局地强对流垂直结构分析

基于X波段相控阵雷达、S波段双偏振雷达、微波辐射计、风廓线雷达、毫米波云雷达等多源高时空分辨率新型遥感探测资料,对广州后汛期一次局地强对流过程的大气热力、动力及云物理结构变化特征进行了综合分析。结果表明：(1)强对流前8小时前,局地LI、CAPE、SI等对流参数就达到并远远超过了短时强降水的阈值;临近降水大气层结仍向不稳定发展,水汽条件向有利的方向发展;(2)午后局地风形成辐合,上升气流加强,近地层出现弱垂直风切变和低空急流脉动,对强对流的发生发展有一定的指示意义;(3) CINRAD/SA-D雷达CR、DBZM HT、TOPS、VIL等变化与强降水和地面大风的发展有很好的对应关系,同时低层风场观测到阵风锋特征;XPAR-D雷达更高时空分辨率的探测可清晰显示对流发展旺盛阶段的Z_DR弧、K_DP柱、Z_DR柱、V型缺口等特征,为判断雷暴云团的发展程度和预警提供重要信息。     

水源热泵系统中地下水流贯通及其对温度场的影响

利用含水层储能的一般特点,提出流贯通;分析流贯通和热贯通的相互作用、相互影响及对工程实际的意义;并基于地下水水热运移的基本原理,建立地下水流动和热量输运的耦合数值模型。在此基础上对沈阳某场地水源热泵工程的运行进行流场及温度场的数值模拟分析,给出产生流贯通的依据,即利用水力坡度定量的判断流贯通发生与否;当水力坡度变化非常小、可忽略不计时,认为含水层出现流贯通;进而研究抽、灌量对流贯通的影响,发现抽、灌量越大,则出现流贯通时间越短;而大量的抽、灌量更容易发生流贯通,进而会引起热贯通的发生。在实际工程中可降低抽、灌水量,在条件许可的情况下可提高抽、灌井的间距,并可在抽、灌井运行一个周期后调整抽灌井位置,以减少热贯通的发生。     

Precise temperature monitoring in boreholes: evidence for oscillatory convection? Part II: theory and interpretation

In the previous part of this work (Cermak, Safanda and Bodri, this volume p.MMM) we have described experimental data and quantified the heterogeneity features of the microtemperature time series. The spectral analysis and the local growth of the second moment technique revealed scaling structure of all observed time series generally similar and suggested the presence of two temperature forming processes. The longer-scale part can be attributed to the heat conduction in compositional and structural heterogeneous solid rocks, further affected by various local conditions. Short-scale temperature oscillations are produced by the intra-hole fluid convection due to inherent instability of water column filling the hole. Here we present how the observational evidence is supported by the results of the computer simulations. The exact modes of intra-hole convection may be different, ranging from quasi-periodic (“quiescent”) state to close of turbulence. As demonstrated by numerical modeling and referred on laboratory experiments, at higher Rayleigh numbers the periodic character of oscillation characteristic for “quiescent” regime is superseded by stochastic features. This so called “oscillatory” convection occurs due to instability within the horizontal boundary layers between the individual convectional cells. In spite of the fact that the basic convective cell motion is maintained and convection is characterized by slow motion, the oscillatory intra-hole flow and corresponding temperature patterns exhibit typical features of turbulence. The idea of boundary layer instability as a source of stochastic temperature fluctuations could explain many distinct features of borehole temperatures that previously cannot be interpreted.     

Interactive visualization of 3D mantle convection

The current availability of thousands of processors at many high performance computing centers has made it feasible to carry out, in near real time, interactive visualization of 3D mantle convection temperature fields, using grid configurations having 10–100 million unknowns. We will describe the technical details involved in carrying out this endeavor, using the facilities available at the Laboratory of Computational Science and Engineering (LCSE) at the University of Minnesota. These technical details involve the modification of a parallel mantle convection program, ACuTEMan; the usage of client–server socket based programs to transfer upwards of a terabyte of time series scientific model data using a local network; a rendering system containing multiple nodes; a high resolution PowerWall display, and the interactive visualization software, DSCVR. We have found that working in an interactive visualizastion mode allows for fast and efficient analysis of mantle convection results. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

大陆岩石圈对扩张机制的响应——辽蒙地质走廊中—新生代火山活动的时空分布

选择以辽西为中心,近东西向延伸800km的辽蒙地质走廊为研究区,通过年代学研究,确认130Ma以来的中、新生代火山活动对称分布的时空格局具有“中间老、两侧新”的特点,而且随着时间的推移,软流圈来源的岩浆向东西两侧侧向流动,岩浆来源不断加深。在此基础上提出“软流圈底辟体上涌和水平侧向流动”的模式。     

Plagioclase in the Skaergaard intrusion. Part 1: Core and rim compositions in the layered series

The anorthite content of plagioclase grains (X_An) in 12 rocks from the layered series of the Skaergaard intrusion has been studied by electron microprobe (typically ∼30 core and ∼70 rim analyses per thin section). Mean core compositions vary continuously from An₆₆ at the base of the layered series (LZa) to An_32–30 at the top. On the other hand, crystal rims are of approximately constant composition (An_{50 ± 1}) from the LZa to the lower Middle Zone (MZ). Above the MZ, core and rim compositions generally overlap. Profiles across individual plagioclase grains from the lower zone show that most crystals have an external zone buffered at X_An ∼50 ± 1. The simplest explanation for these features is that during postcumulus crystallization in the lower zone, interstitial liquids passed through a density maximum. This interpretation is consistent with proposed liquid lines of descent that predict silica enrichment of the liquid associated with the appearance of cumulus magnetite.     

Time dependent structural architecture of subsidiary fracturing and stress pattern in the tip region of an extensional growth fault system, Tarquinia basin, Italy

Fault tip regions, relay ramps and accommodation zones in between major segments of extensional fault systems provide zones of additional structural and stratigraphic complexities and also significantly affect their hydraulic behaviour. The great interest for both academic and industrial purposes encouraged specific studies of fault tip regions that, in some cases, produced controversial results. We approached the study of fault tip regions by integrating structural, AMS and stratigraphic analyses of the tip of an extensional growth fault system in the Tarquinia basin, on the Tyrrhenian side of the Northern Apennines. Detailed structural mapping indicates the occurrence of systematic relationships between the orientation of the main subsidiary fault zones, the orientation and position of the two main joint sets developed in the fault damage zones, and the overprinting relationships between the two main joint sets themselves. Microstructural analysis of fault core rocks indicates a progression of deformation from soft-sediment to brittle conditions. The AMS study supports the evolution of deformation under a constantly oriented stress field. By combining this multidisciplinary information we propose an evolutionary model for the tip of the extensional growth fault system that accounts for the progressively changing sediment rheological properties, and for the time dependent subsidiary deformation pattern by invoking the interplay between the regional stress field and the local, kinematically-derived one by fault activity. We also speculate on the overall implications for fluid flow of the proposed evolutionary model.     

2017年6月大气环流和天气分析

2017年6月大气环流的主要特征是极涡偏强且呈单极型分布,中高纬环流呈多波型,西太平洋副热带高压强度较常年偏弱。6月全国平均气温20.3℃,较常年同期偏高0.3℃;全国平均降水量112.3 mm,比常年同期(99.3 mm)偏多13%,长江流域入梅时间较常年偏早。我国南方地区有6次区域性暴雨过程,部分地区暴雨洪涝重;与此同时,东北、华北等地少雨高温,干旱持续时间较长;月内今年第2号台风苗柏在广东深圳登陆;全国19个省（区、市）遭受风雹灾害。     

秦皇岛一次飑线冰雹天气分析

利用常规探测资料、自动站观测资料、多普勒天气雷达资料等对2014年6月26日发生在秦皇岛市的一次飑线冰雹天气过程大尺度环流背景、雷达回波特征及灾害性冰雹大风形成原因进行了分析。结果表明:本次飑线过程是受高空冷涡后部冷空气、低层暖切变共同作用的结果;飑线过境前后,气象要素变化比较明显,风向突变、风力猛增、气压涌升、气温急降、相对湿度上升;本次强风暴影响系统尺度为中α尺度,"弓"形回波结构明显,同时有雷暴出流边界;速度图上的风速大值区、后侧入流、中低层径向辐合及垂直风廓线图中低层风的转变信息等对大风的预警有明显的预示作用,且从雷达四维变分分析可知850 h Pa辐合上升运动较强,中层有干冷空气入侵;回波垂直剖面图上飑线前沿低层存在有界弱回波区,中高层有回波悬垂。     

喜马拉雅山南坡冬季暴雪对高原南部冰芯中稳定同位素记录的影响

聂拉木气象站降水中 δ18O的变化表明 ,夏季降水中 δ18O为一低值阶段 ;冬季降水中 δ18O总的来说为一高值阶段 ,但冬季暴风雪中δ18O的值和夏季强的季风活动中降水的δ18O一样很低。由于该地区冬季降水十分活跃 ,冬季降水中 δ18O的变化对该地区冰芯记录将产生重要的影响。首先是用δ18O的季节变化来对冰芯定年产生一定的困难 ,其次喜马拉雅山中段冰芯中的δ18O记录不仅包括了夏季季风活动的强弱信息 ,而且冬季强的暴风雪过程也记录在内。