沙尘输送模式的不确定性分析

利用一个远距离输送的沙尘模式估计了由于参数化过程 (干沉降速度) 和输入资料 (源强和水平风场) 的误差造成沙尘模拟的不确定性。通过对以上参数分别进行敏感性试验, 分析了模式对2002年3月15～24日期间中国东部地区两次主要沙尘过程模拟的不确定性。结果显示, 源区的潜在源强和气象水平风场的不确定性对模拟结果的影响最大, 而干沉降速度的影响相对较小。同时, 对不同区域 ［西部 (＜95°E)、中部 (95°E～110°E) 和东部 (＞110°E)］ 的潜在源强和干沉降速度参数进行敏感性试验发现, 中部区域的参数设置对模拟结果的影响最大, 而西部和东部区域的参数变化对模拟结果的影响很小。此外, 不同高度的风场影响也不一样: 地面风速影响最大, 中层的影响较小, 而高层 (约6 km高度以上) 的风场几乎没有影响。     

杆状病毒感染越冬亲虾(Penaeus chenesis)的研究——越冬亲虾感染及其垂直传播的可能性

在中国对虾越冬亲虾中检出杆状病毒。经对病虾鳃、前中肠、卵巢组织进行电镜观察，在这些组织中发现大量有囊膜的杆状病毒。病毒粒子大小约为３６７ｎｍ×１２８ｎｍ，核衣壳为３２４ｎｍ×９２ｎｍ。病毒在细胞内不形成包涵体，在核内或在细胞质的发生基质中装配。从病毒的形态特征、感染组织以及典型的发病症状和病理变化，初步认为亲虾感染的病毒与近年广泛报道的造成养殖对虾大规模流行病的主要原因——中国对虾杆状病毒为同一种。卵巢组织也是病毒的主要靶器官之一，亲虾卵巢组织的被感染暗示着该病毒有可能通过生殖细胞而垂直传播     

Electrical properties of dry polycrystalline olivine mixed with various chromite contents: Implications for the high conductivity anomalies in subduction zones

Chromite,a crucial high-conductivity mineral phase of peridotite in ophiolite suites,has a significant effect on the ele ctrical structure of subduction zones.The electrical conductivities of sintered polycrystalline olivine containing various volume percents of chromite(0,4,7,10,13,16,18,21,23,100 vol.%) were measured using a complex impedance spectroscopic technique in the frequency range of 10~(-1)-10~6 Hz under the conditions of1.0-3.0 GPa and 873-1223 K.The relationship between the conductivities of the chromite-bearing olivine aggregate s and temperatures conformed to the Arrhenius equation.The positive effect of pressure on the conductivities of the olivine-chromite systems was much weaker than that of temperature.The chromite content had an important effect on the conductivities of the olivine-chromite systems,and the bulk conductivities increased with increasing volume fraction of chromite to a certain extent.The inclusion of 16 vol.% chromite s dramatically enhanced the bulk conductivity,implying that the percolation thre shold of interconnectivity of chromite in the olivine-chromite systems is ～16 vol%.The fitted activation enthalpies for pure polycrystalline olivine,polycrystalline olivine with isolated chromite,polycrystalline olivine with interconnected chromites,and pure polycrystalline chromite were 1.2 5,0.78-0.8 7,0.48-0.54,and 0.47 eV, respectively.Based on the chemical compositions and activation enthalpies,small polaron conduction was proposed to be the dominant conduction mechanism for polycrystalline olivine with various chromite contents.Furthermore,the conductivities of polycrystalline olivine with interconnected chromite(10~(-1-5)-10~(0.5) S/m) provides a reasonable explanation for the high conductivity anomalies in subduction-related tectonic environments.     

Catastrophe of Coronal Magnetic Flux Ropes Caused by Photospheric Motions

Using a 2.5-D, time-dependent ideal MHD model in Cartesian coordinates, we carried out numerical simulations to investigate the equilibrium and evolution properties of a magnetic configuration that consists of a coronal magnetic flux rope and a partly open photospheric background field, which is equivalent to that produced by a two-patch magnetic source on the photospheric surface. The axial and annular magnetic fluxes of the flux rope are given and fixed. The global magnetic configuration evolves in response to three types of changes of the background field: decreasing of the distance between the two sources, shrinking of the size of each source, and increasing of the shear in the closed component of the background field. As a result, the geometrical parameters of the flux rope, i.e. the height of the rope axis, the half-width of the rope and the length of the vertical current sheet below the rope, change due to the variation of the background field. It is shown that for a given coronal magnetic flux rope in a partly open background field, the variation of the geometrical parameters of the flux rope displays a catastrophic behavior, namely, there exists a critical point for each case, at which an infinitesimal change of the background field leads to a loss of equilibrium, and thus a jump of the flux rope. The implication of such a catastrophe in solar active phenomena is briefly discussed.     

基于虚拟化云平台的气象终端集约化管理

气象终端的集约化管理是气象业务系统和气象服务需求发展到一定阶段后的必然趋势和结果。从气象终端管理的现状和需求、虚拟化云平台的技术体现和应用部署中,体现基于虚拟化云平台的气象终端集约化管理的应用特点和实施效果:提供虚拟防护、桌面管理及行为控制等的策略管理和策略服务,提升气象现代化支撑和保障气象用户个性化需求的能力,为气象平台建设、信息共享、应用服务的终端管理提出了全新概念,是集"应用"、"集成"、"运维"、"安全"到"成本控制"的解决方案。     

多窗谱分析方法及其在全球变暖研究中的应用

多窗谱分析方法是一种低方差、高分辨的谱分析方法 ,尤其适合于非线性气候系统中高噪声背景下弱信号、时频演变信号的诊断分析。文中简要地介绍了多窗谱分析方法的基本原理 ,并将其用于近 1 5 0 a来全球及南、北半球温度变化的研究。结果表明 :(1 )在温度呈线性变暖的背景趋势下 ,北半球、全球年平均温度还具有显著的 40～ 70 a的准周期低频振荡 ,它们与变暖过程中的波动性密切相关 ;(2 )年代际振荡信号在北半球温度序列中也相当明显 ,南半球则存在多种低于 5 a尺度的显著振荡周期 ,半球或全球 ENSO振荡分量、QBO周期信号的振幅都具有缓变包络的特性 ;(3 )与传统功率谱估计、最大熵谱估计结果的对比表明 ,多窗谱分析方法方法得到的谱估计分辨力高 ,稳定性强。     

Hybrid continuum–discrete simulation of granular impact dynamics

Acta Geotechnica - Granular impact—the dynamic intrusion of solid objects into granular media—is widespread across scientific and engineering applications including geotechnics....     

Improved Priority‐Flood method for depression filling by redundant calculation optimization in local micro‐relief areas

Depression filling is a critical step in distributed hydrological modeling using digital elevation models (DEMs). The traditional Priority‐Flood (PF) approach is widely used due to its relatively high efficiency when dealing with a small‐sized DEM. However, it seems inadequate and inefficient when dealing with large high‐resolution DEMs. In this work, we examined the relationship between the PF algorithm calculation process and the topographical characteristics of depressions, and found significant redundant calculations in the local micro‐relief areas in the conventional PF algorithm. As such calculations require more time when dealing with large DEMs, we thus propose a new variant of the PF algorithm, wherein redundant points and calculations are recognized and eliminated based on the local micro‐relief water‐flow characteristics of the depression‐filling process. In addition, depressions and flatlands were optimally processed by a quick queue to improve the efficiency of the process. The proposed method was applied and validated in eight case areas using the Shuttle Radar Topography Mission digital elevation model (SRTM‐DEM) with 1 arc‐second resolution. These selected areas have different data sizes. A comparative analysis among the proposed method, the Wang and Liu‐based PF, the improved Barnes‐based PF, the improved Zhou‐based PF, and the Planchon and Darboux (P&D) algorithms was conducted to evaluate the accuracy and efficiency of the proposed algorithm. The results showed that the proposed algorithm is 43.2% (maximum) faster than Wang and Liu's variant of the PF method, with an average of 31.8%. In addition, the proposed algorithm achieved similar performance to the improved Zhou‐based PF algorithm, though our algorithm has the advantage of being simpler. The optimal strategies using the proposed algorithm can be employed in various landforms with high efficiency. The proposed method can also achieve good depression filling, even with large amounts of DEM data.     

思茅境内澜沧江径流变化量与云南气候变化的关系

以思茅澜沧江流域下游思茅境内水文站1960年1月～2001年12月的逐月径流量和云南的月雨量(气温)场格点资料为基础,用相关分析的方法,研究了思茅境内澜沧江流域的东西部径流量变化及其与云南气候变化的关系。结论为:思茅境内澜沧江下游流域的径流量变化与滇西南的降水量变化有显著的相关关系,其季节特征为春夏季较好,秋冬季次之;与元江河谷一带的气温变化也有显著的反相关关系,其中西部流域还与滇南的气温变化有显著的相关关系,其季节特征则为冬春季较好,夏秋季不显著。20世纪80年代以来,该流域的气温变化呈上升趋势,且西部升温的上升趋势更显著,气温上升对径流量的变化起减小的作用;20世纪90年代以来,该流域的东西部降水量变化出现了显著的差异,其东部的降水量明显增多,与此相一致,其东部径流量变化的增幅也明显大于其西部。     

一种公平技术评分方法在台风业务预报评估中的应用

将离散变量分级预报的公平技术评分方法引入台风路径业务的预报评估中，对１９８９－１９９１年的台风业务预报作评估试验，结果表明，该方法量客观，不但可用于台风分类预报评估，也可对台风移向移速预报进行客观评估。