数值模式预报调整趋势分析

对不同时效预报的调整趋势进行分析,是预估预报误差和对预报进行订正的一种思路。为了系统性检验这一思路的有效性,本文定义了西风槽强度和位置指数,以及西北太平洋副热带高压(简称副高)强度和位置等指数,运用2011年4月以来的500 hPa位势高度场预报资料,研究对比了ECMWF(简称EC)和T639模式对副高和我国不同区域西风槽的位置和强度,72 h时效内对同一时刻不同时效的预报,随预报时效的临近,预报调整趋势之间的相关性和一致性。研究结果显示,EC和T639模式对副高的预报,都存在西脊点偏东、范围偏小、强度偏弱和北界偏南的系统性偏差,且时效越长偏差越大,T639模式的偏差明显大于EC模式,但相关性分析和方差分析表明,不同时效的调整趋势之间并不存在较为显著的相关性,即不同时效的预报并没有较为明显的、一致的调整趋势。另外,副高的预报误差与西脊点所处的经度有关,从东印度洋到菲律宾以东洋面,西脊点越往东,预报误差和系统偏差越小,但西脊点位于不同的经度区间时,不同时效的调整趋势之间同样没有明显的相关性,且整体上以负的协方差为主。对于西风槽,两家模式北方槽的误差都明显大于南方槽的误差,强度的误差较小,且T639的误差明显大于EC模式,相邻时效的调整趋势之间以负的协方差为主,说明随时效的临近,槽的位置并没有较为一致的调整趋势。同时不同时期预报调整趋势之间的相关性分析显示,模式版本的升级,并没有改变调整趋势之间几乎无一致性的特征。     

Experimental Study on Displacement Field of Strata Overlying Goaf with Sloping Coal Seam

To study the displacement caused by underground mining, the displacement field in the strata overlying the mine was simulated in nine similar-material models with coal seam dip angles of 0°–80°. Digital close-range photogrammetry was employed to observe the displacement in these models and produce displacement vector diagrams of observation points set on the model surfaces. The movement boundary of the rock mass was extracted and determined. According to the displacement vectors’ direction, the displacement field within the movement boundary was divided into five zones: two zones with displacement vectors pointing towards the goaf center, two zones with vectors pointing towards the coal pillar, and one zone with displacement vectors pointing vertically downward. A symmetry index was defined to analyze the symmetry of the displacement field, and the results show that as the coal seam dip angle increased from 0° to 80°, the displacement field in the strata changed according to the following pattern: symmetric → asymmetric → nearly symmetric, with a transition angle of about 45°. The percentage of the area of the above-defined five zones relative to the displacement field’s total area also changed, showing a regular pattern. This study also revealed that the movement boundary inside the overlaying rock layers is not a straight line, but an S-shaped curve. These findings can enhance our understanding of the internal mechanism of ground subsidence and contribute to more effective prediction of the deformation occurring inside a given rock mass.     

南祁连化隆地区镁铁-超镁铁质侵入岩地质、地球化学特征与铜镍成矿

南祁连化隆地区的镁铁-超镁铁质侵入岩带是青海省重要的含镍矿岩带,铁质系列良好的岩相分异及较高的Ni、Cu、Co元素含量表现出了很好的成矿条件与找矿潜力。通过对区内裕龙沟、亚曲、阿什贡及下什堂等岩体地质特征、岩石地球化学特征及区域对比分析研究,表明稀土元素的球粒陨石和微量元素的原始地幔蛛网图表现出轻稀土元素相对富集的右倾模式,并且富集大离子亲石元素(Sr、Rb、Ba)、相对亏损高场强元素(Nb、Ta、Hf、Zr)。γOs值表现为大的正值且变化范围较大(+80~+1183),连同普遍存在的Nb、Ta亏损,进一步说明可能也与地壳同化混染密切相关。这些表明带内岩体的母岩浆来自一个曾被交代富集的地幔源区,其εNd(t)=-7.74~+8.36,这些共同表明其岩浆源区应该位于软流圈地幔,并混有一部分被俯冲板片交代的地幔楔物质。而这种交代富集事件可能与祁连、柴北缘在早古生代期间大规模的板片俯冲有关。化隆群富硅地层为硫化物的不混溶创造了同化混染的条件,并最终导致富硅物质的加入,致使岩浆中硫化物的不混溶作用发生,从而可形成不同品位不同类型的岩浆铜镍硫化物矿床。     

青海省化隆地区镁铁-超镁铁质侵入岩含矿特点与成矿规律

铁质系列的镁铁-超镁铁质侵入岩具有镍矿成矿专属性,但并非所有的类似侵入岩都含矿,根据镁铁-超镁铁质侵入岩含矿特点可总结成矿规律,有效指导区域找矿实践。青海省化隆地区发育114个镁铁-超镁铁质侵入岩体,其含矿性特点与成矿规律是制约该岩带找矿突破的关键因素。本文通过对区内裕龙沟、亚曲、阿什贡及下什堂等岩体地质特征、年代学、岩石地球化学特征及区域对比分析研究,发现这些岩体具有相近的成岩时代,集中于436~449 Ma,可能是同一构造背景的产物。S同位素、Re-Os同位素及Sr-Nd同位素共同揭示了岩体的母岩浆来自一个曾被交代富集的地幔源区,其εNd(t)=-7.74~+8.36,初步表明其岩浆源区应该位于软流圈地幔,并混有一部分被俯冲板片交代的地幔楔物质。而这种交代富集事件可能与祁连、柴北缘在早古生代期间大规模的俯冲有关,是弧岩浆作用的成矿表现。化隆群富硅地层S的混入为硫化物的不混溶创造了条件,致使岩浆中熔离出的硫化物液滴聚集,侵位到理想空间形成不同品位不同类型的铜镍矿体。岩相分异充分、橄榄石富集、基性程度较高的侵入岩体相对易形成镍矿体,对青海省化隆地区镁铁-超镁铁质岩体的含矿性评价具有重要指示作用。     

COMPARATIVE ANALYSIS OF THE INTENSIFYING AND WEAKENING LANDFALL TROPICAL CYCLONES DURING EXTRATROPICAL TRANSITION OVER CHINA

Based on the Tropical Cyclone(TC) Yearbooks data and JRA-25 reanalysis data from the Japan Meteorological Agency(JMA) during 1979-2008, dynamic composite analysis and computation of kinetic energy budget are used to study the intensifying and weakening TCs during Extratropical Transition over China. The TCI shows strong upper-level divergence, strengthened low-level convergence and significantly enhanced upward motion under the influence of strong upper-level troughs and high-level jets. The TCI is correspondingly intensified after Extratropical Transition(ET); TCW exhibits strong upper-level divergence, subdued low-level convergence and slightly enhanced upward motion under the influence of weak upper-level troughs and high-level jets. It then weakens after ET. The increase(decrease) of the generation of kinetic energy by divergence wind in TCI(TCW) at low level is one of the major reasons for TCI’s intensification(TCW’s weakening) after transformation. The generation of kinetic energy by divergence wind is closely related to the development of a low-level baroclinic frontal zone. The growth of the generation of kinetic energy by rotational wind in TCI at upper level is favorable for TCI’s maintenance, which is affected by strong upper-level troughs. The dissipation of the generation of kinetic energy by rotational wind in TCW at upper level is unfavorable for TCW’s maintenance, which is affected by weak upper-level troughs.     

伶仃洋河口横向环流

横向环流存在于大多数河口中,在河口的动量平衡和物质输运过程中起着重要的作用,其形成的机制众多。本文利用三维水动力模型EFDC(Environmental Fluid Dynamics Code),结合1989年和2002年的实测数据对伶仃洋河口进行研究,得到了伶仃洋河口在洪季和枯季时期不同的水动力和盐度分布结构。在文中选取了具有代表性的两个断面,针对洪枯季、大小潮以及涨落潮等不同时期的横向流结构和盐度剖面分布特点进行比较和分析。结果显示,受局地的径、潮流条件和地形约束影响,横向环流结构并不能充分形成,在不同的区域表现出截然不同的结构特点。伶仃洋河口横向环流主要是在径、潮流与地形三者之间的相互作用下形成的,不同的区域的形成机制存在差异。综合分析后,本文认为伶仃洋河口的横向环流在该区域的动力过程中相对较为次要。     

海水中无机混合元素标准样品的研制

对海水中无机混合元素标准样品进行了研究和制备。样品采用高纯试剂重量法制备,以人工海水为样品介质,用原子吸收法和原子荧光法对样品进行均匀性和稳定性研究;多家实验室协作分析定值后数理统计确定标准值,并进行不确定度评估。结果表明,海水中无机混合元素标准样品的均匀性和稳定性良好;可用于海水污染监测的仪器较准、分析方法的评价与验证、实验分析的质量控制和能力验证等方面。     

A Possible Cause of the Diminished Solar Wind During the Solar Cycle 23 – 24 Minimum

Interplanetary magnetic field and solar wind plasma density observed at 1 AU during Solar Cycle 23?–?24 (SC-23/24) minimum were significantly smaller than those during its previous solar cycle (SC-22/23) minimum. Because the Earth’s orbit is embedded in the slow wind during solar minimum, changes in the geometry and/or content of the slow wind region (SWR) can have a direct influence on the solar wind parameters near the Earth. In this study, we analyze solar wind plasma and magnetic field data of hourly values acquired by Ulysses. It is found that the solar wind, when averaging over the first (1995.6?–?1995.8) and third (2006.9?–?2008.2) Ulysses’ perihelion (\({\sim}\,1.4~\mbox{AU}\)) crossings, was about the same speed, but significantly less dense (\({\sim}\,34~\%\)) and cooler (\({\sim}\,20~\%\)), and the total magnetic field was \({\sim}\,30~\%\) weaker during the third compared to the first crossing. It is also found that the SWR was \({\sim}\,50~\%\) wider in the third (\({\sim}\,68.5^{\circ}\) in heliographic latitude) than in the first (\({\sim}\,44.8^{\circ}\)) solar orbit. The observed latitudinal increase in the SWR is sufficient to explain the excessive decline in the near-Earth solar wind density during the recent solar minimum without speculating that the total solar output may have been decreasing. The observed SWR inflation is also consistent with a cooler solar wind in the SC-23/24 than in the SC-22/23 minimum. Furthermore, the ratio of the high-to-low latitude photospheric magnetic field (or equatorward magnetic pressure force), as observed by the Mountain Wilson Observatory, is smaller during the third than the first Ulysses’ perihelion orbit. These findings suggest that the smaller equatorward magnetic pressure at the Sun may have led to the latitudinally-wider SRW observed by Ulysses in SC-23/24 minimum.     

云南耿马县勐简铅锌银矿特征及成矿规律

勐简铅锌银矿近矿围岩为古生界孟定街群(Pzmb),矿体呈似层状、脉状赋存于北东东向断裂破碎带中,为中—低温热液充填型矿床。