1991年江淮早梅及其与过赤道气流异常的关系

讨论了1991年江淮早梅现象及其形成机制。结果表明:5月第4候西太平洋副热带高压脊线出现第一次北跳,夏季风影响到江南,江淮地区入梅,比常年早二十多天;这与120—130°E间异常地出现较强的过赤道气流有关。     

Fluid inclusion evidence for an anticlockwise metamorphic P-T path in central Massachusetts

Acadian (Late Silurian to Early Devonian) metamorphism in the Central Maine Terrane (CMT) in central Massachusetts is characterized by an early low-P, high-T (Buchan-type) metamorphism followed by thickening at high temperature (>650d? C) and then by cooling to 100-200d? C below peak recorded temperatures before eventual unroofing. Mineralogical and textural evidence for this path includes sillimanite pseudomorphs after early andalusite, abundant cordierite in pelitic lithologies, replacement of low-P cordierite-bearing assemblages by high-P garnet-bearing assemblages, and recrystallization of mylonites associated with late shear zones to form lower-T and higher-P assemblages. Peak conditions in the highest grade rocks were 685-780d? C and 5-6 kbar; the cooling path passed through 550d? C at about 6.5 kbar. The well-constrained P-T path documented from geological and mineralogical evidence for the CMT offers an unusual opportunity to examine characteristics of fluid inclusions that have experienced a long-lived metamorphic event spanning a broad range of P-T conditions. Fluid inclusion data from the CMT document a range of fluid compositions (CO₂-rich, mixed CO₂-N₂-rich, N₂-rich and H₂O-rich) and densities during metamorphism. Densities of CO₂ fluid inclusions range from 0.20 to 1.03 g cm^-3. Medium-density CO₂ fluid inclusions are contained in quartz inclusions within garnets in partial melt leucosomes, and in quartz grains within migmatites. Fluid inclusions within the quartz inclusions indicate trapping conditions of 650-700d? C at pressures below 5 kbar. Other CO₂ fluid inclusions from matrix quartz yield isochores which pass through 700d? C and 5.2 kbar. The highest density inclusions associated with rocks containing the late high-P assemblages have isochores which pass below the estimated P-T conditions for recrystallization of the mylonite. Fluid inclusion evidence suggests an early low-P heating event, followed by thickening at high temperature, and then by nearly isobaric cooling to about 500d? C with later decompression. This interpretation is also consistent with previously published petrological models and supports an anticlockwise P-T path for the CMT of south-central Massachusetts.     

CINRAD/SA雷达闪码故障分析和排查方法

天线伺服系统是CINRAD/SA天气雷达的重要组成部分,大部分组件长期处于机械运转中,且线路复杂,是雷达系统中故障率较高的部分,其中,闪码故障发生概率较大。本文对2007—2013年全国CINRAD/SA雷达站收集的68个闪码故障案例进行统计分析,结果表明,电机、旋转变压器、汇流环、轴角编码盒、光纤链路、数字控制单元等环节均有可能导致闪码。结合CINRAD/SA雷达伺服系统天线角码信号流程和关键点的参数特征,对可能导致雷达闪码故障的所有环节逐个进行分析,归纳总结出CINRAD/SA雷达出现此类故障的排查方法,并从收集的案例中选取5个典型个例展开分析。通过统计样本案例的故障归属,提出轴角闪码时检测部件的先后顺序,为各台站快速排除雷达闪码故障提供了思路,对解决其他天线伺服系统故障也有一定的借鉴意义。     

青藏高原与中国其他地区气候突变时间的比较

基于1961～2006年中国地面观测气温和降水资料,对青藏高原地区以及中国其他6个地区地表气温、降水的变化趋势和突变时间进行了检测和比较。结果发现,(1)地表气温:1961～2006年青藏高原地区年和四季的地表气温都呈增加趋势。年平均地表气温在20世纪80年代中期开始变暖,但显著快速增暖的突变发生在90年代中期,该时间比东北、华北、西北和淮河地区晚,与长江中下游和华南地区接近,不同季节青藏高原地区与其他地区变暖突变时间的差别也各有不同,但所有季节快速变暖突变的时间都比东北地区晚,中国东部陆地地区年和冬季平均地表气温表现出北早南晚的经向差异;(2)降水:1961～2006年青藏高原地区年降水量没有检测到显著的变化趋势,冬春降水量显著增加,而夏季降水有微弱的减少,秋季降水显著减少。降水突变的信号明显比温度突变的信号弱,年降水量和春季降水都没有检测到突变的发生,降水突变方向(增或减)和突变时间在区域与区域之间以及不同季节之间都存在较大差异。由上可见,青藏高原气候的显著快速变化比中国东部长江以北地区有明显的滞后现象,尤其是冬春温度变化,这可能是由于青藏高原地区积雪增加导致的反照率增加和冰川融化吸热对青藏高原变暖的减弱作用所致。     

弹脆性圆形煤巷应力跃升及冲击地压预测模型

为预测煤巷冲击地压灾害,将强冲击倾向煤视作理想弹脆性材料,建立圆形煤巷力学模型,分析煤巷围岩的应力和变形能密度分布特征,进而建立煤巷冲击地压预测模型,利用该模型预测冲击地压灾害风险。研究结果表明：弹脆性煤巷围岩的切向应力和变形能密度在弹性区与破坏区界面处发生跃升;煤体强度损伤度和地应力增大,煤巷破坏区半径增大,煤巷围岩切向应力和变形能密度跃升高度增大;切向应力跃升为煤巷失稳破坏提供了力源,变形能密度跃升为冲击地压发生提供了能量源;切向应力和变形能密度跃升高度越大,煤巷越容易失稳和冲击;基于切向应力和变形能密度跃升,建立了煤巷冲击地压解析预测模型,预测结果与现场冲击地压实际情况一致,从而为脆性煤巷冲击地压预测提供了一种新的方法。     

1961-2003年间鄱阳湖流域气候变化趋势及突变分析

本文利用1961-2003年间鄱阳湖流域14个气象站的气温、降水量、蒸发量等观测数据和8个主要水文站的流量数据,研究该时段内鄱阳湖流域的气候变化趋势、突变及其空间分布的差异．研究表明,鄱阳潮流域气温和降水均在1990年发生突变,继而呈现显著的上升趋势;在季节变化上,冬季平均气温在1986年发生突变,增温显著;夏季降水量和夏季暴雨频率均在1992年发生突变增加,暴雨频率增加是夏季降水量增加的主要原因;蒸发皿蒸发量和参照蒸散量均呈现显著下降趋势,该变化在夏季尤为明显．上述变化趋势均以1990s最为显著,这与长江流域气候变化趋势基本一致．在空间分布上,饶河水系、信江水系和赣江下游等气候变化更为显著．笔者认为,鄱阳湖流域气候变化在长江流域中比较突出．该流域1990s暖湿气候在加强;气温的升高、降水量和暴雨频率的增加以及蒸发量的下降强化了五河流量的增加趋势,由此可大致判定鄱阳湖流域气候变化与洪涝灾害之间可能存在的关系,这可为理解气候变化在该流域的响应和预测该流域未来可能的洪涝灾害提供依据．     

The Study on the Group Delay Jumping of CE-4 VLBI System

The phase delay software is a key component of VLBI (Very Long Baseline Interferometry) orbit determination system in CE-4 mission, which is critical to deep space exploration. When processing X-band DOR (Differential One-way Ranging) signals of probes in the past, the group delay jumping occasionally occurred in the observed scan. This paper consists of two parts. First, according to the VLBI station signal reception and VLBI center data processing steps, we analyzed the frequency, phase, power, and self-correlation spectrum of the signal, and located the influencing factor at the abnormal analog signal of Kunming (KM) station. Second, the group delay jumping was revised by the post-correction method, which was based on the analysis of the abnormal unwrap phase. We used the corrected phase to get the new group delay, and used orbit determination software to verify the effectiveness of the post-correction method, which upgraded the phase delay processing software.     

腾冲地震台数字化水温观测数据异常分析

腾冲地震台数字化水温记录多次出现数据突跳,影响观测资料质量。引入1套相同型号的水温仪进行对比观测,对可能引起原水温仪数据突跳的因素(静电干扰、供电电压、仪器探头故障等)进行一一排查,结果表明,水温仪主机数据转换模块工作不正常是引起水温数据突跳、阶变的主要原因,仪器供电电压不稳、雷电因素对数据突跳的产生有促进作用。消除水温数据突跳干扰的有效解决办法是更换1套水温观测仪器。     

嫦娥四号VLBI群时延跳变研究

相时延处理软件是嫦娥四号(CE-4)任务甚长基线干涉测量(Very Long Baseline Interferometry,VLBI)测轨分系统软件配置项之一,利用其处理着陆巡视器X波段DOR(Differential One-way Ranging)信号时,观测弧段(scan)内偶尔存在残余群时延跳变问题.论文主要分为两部分:一是根据VLBI信号接收和数据处理流程,从相关相位、频率、幅度和功率方面进行分析,最终将影响因素定位在昆明测站模拟信号异常;二是以scan内时延跳变影响因素分析为基础,通过修正异常基线相关相位,研究残余群时延跳变事后改正方法,并利用定轨软件验证其有效性,升级了相时延处理软件.     

ＰＲＥＣＩＳ模式对陕西气候模拟能力验证

利用常规气象观测及卫星、雷达、闪电定位、自动站等资料对这次过程的成因进行了分析。结果表明：过程前期的持续性高温为暴雨的产生积累了能量,副热带高压（以下简称副高）的突然北跳及其西北边缘的西南暖湿气流为暴雨的产生提供了源源不断的水汽和不稳定能量;弱冷空气和中低层切变线触发了这次强对流暴雨天气过程;卫星云图上,副高边缘不断有对流云泡生成、向北输送并发展,促进了中尺度强对流系统的生成与发展,对提前预报有一定的指导意义;地闪主要出现在5880gpm与5840gpm线覆盖的范围,在5880gpm与5840gpm线之间,地闪密度的空间分布与降水量的空间分布有较好的对应关系,负地闪主要出现在5880gpm线一侧,正地闪靠近5840gpm线;地闪频数峰值超前降水量峰值0～2h,这对单站l临近强降水预报很有意义。