典型东海黑潮锋环境下的声场分布异常分析

东海黑潮锋作为中国近海的一类特殊海洋学现象,对水声传播产生的复杂影响已受到关注,但对其影响机制的认识还较为欠缺.应用BELLHOP水声学数值模型分析了典型东海黑潮锋环境下的声场特性,结果表明:穿过锋面时声线干涉伴随的声能强弱空间分布出现明显偏移,同时波导中泄漏的声能对锋面非均匀环境引起的传播损失进行了补偿,使波导区域之外的声能变化小于5dB(声波频率为1 kHz).相比之下,从外海暖水混合层向近海传播时表面声道的瓦解可使传播损失突然增大10 ～ 15 dB(声波频率为1 kHz).东海黑潮锋环境下的声场能量异常分布体现了海底地形和水文环境的共同影响,地形条件对声场样式起支配性作用,而锋面引起的非均匀水文环境则是使声能空间分布出现异常变化的关键调制性因素.     

浙江沿海中尺度辐合线对飑线发展影响的数值试验

利用Weather Research and Forecasting (WRF) 中尺度数值模式, 结合常规观测资料、地面加密自动气象站资料、云迹风等资料较好地模拟了2006年6月10日严重影响浙江的一次强飑线演变过程, 得到了与实况比较接近的飑线中尺度特征, 结果表明: 强对流活动与边界层内的中尺度辐合有密切联系, 除了雷暴出流在其前沿形成的阵风锋外, 还模拟得到了宁波东部地区的中尺度气流辐合线 (简称宁东辐合线); 宁东辐合线呈现出明显的西干东湿、东侧上湿下干和弱的稳定层结特征, 其存在阻挡了边界层顶强不稳定的东传; 在宁东辐合线东侧的山谷地带, 近地面形成一个尺度仅为10～20 km的中尺度垂直闭合环流, 该环流导致地面弱的东风气流又反过来加强了宁东辐合线。当之前已存在的雷暴出流形成的阵风锋辐合线与宁东局地辐合线相遇时, 形成一条新的阵风锋, 边界层之上的湿度显著增强, 强不稳定得到逐步释放, 加剧了对流的爆发, 天气现象进一步加重。     

Wave-Modified Flux and Plume Dispersion in the Stable Boundary Layer

The effects of a pressure jump and a following internal gravity wave on turbulence and plume diffusion in the stable planetary boundary layer are examined. The pressure jump was accompanied by a sudden increase in turbulence and plume dispersion. The effects of wave perturbations on turbulence statistics are analysed by calculating fluxes and variances with and without the wave signal for averaging times ranging from 1 to 30 min. The wave signals are obtained using a band-pass filter. It is shown that second-order turbulence quantities calculated without first subtracting the wave perturbations from the time are greater than those calculated when the wave signal is separated from the turbulence. Estimates of the vertical dispersion of an elevated tracer plume in the stable boundary layer are made using an elastic backscatter lidar. Plume dispersion observed 25 m downwind of the source increases rapidly with the arrival of the flow disturbances. Measured plume dispersion and plume centreline height correlate with the standard deviation of the vertical velocity but not with the wave signal.     

地幔柱假说及其发展

Ｍｏｒｇａｎ提出的地幔柱假说之后，基于流体力学基本方程组的定常地幔柱模式研究，认为地幔柱是地幔对流的一个组合部分。组分差异驱动的地幔柱模拟实验结果，限制了地幔柱在地球动力学中的应用。热浮力驱动的模拟实验结果得到了新的动态地幔柱模式。     

油田开发后期扇三角洲前缘微相分析及应用

储层的微相砂体类型、几何规模特征及分布规律是分析地下油水运动规律和调整注采井网的基础。充分利用密闭取心、密井网等资料 ,精细剖析了双河油田扇三角洲前缘储层沉积微相及其分布。在扇三角洲前缘主要发育水下分流河道、河口坝、前缘席状砂体、重力流砂体、水下溢岸砂体 5种微相砂体。微相砂体形状、规模及空间分布决定了注采井网对油层的控制程度和完善程度 ,微相类型及其分布控制着油水井的产液及吸水能力 ,控制着注入水的地下运动方式 ,因此利用沉积微相的研究成果 ,找准剩余油富集区 ,调整和部署注采井网 ,可以在生产中取得较好的效果     

Drought is the major limiting factor for tree-ring growth of high-altitude Canary Island pines on Tenerife

This is a detailed study of 50 wood cores sampled from 25 Canary Island pines ( Pinus canariensis ) growing in a subtropical climate close to the tree limit (at Lomo de Retamar, 2000–2100 m a.s.l.) on the southern, leeward side of Tenerife.
The Canary Island pines form tree-rings and, similarly to temperate pines, earlywood is formed during spring. But many pines fail to form tree-rings every year and one purpose for this paper has been to find a way to overcome this problem. Another purpose has been to see what correlations, if any, exist between the ring widths and meteorological data. Meteorological data have been collected since 1916 at the nearby Izaña meteorological observatory. It was also important to find the limiting factor for growth of Canary Island pines close to the tree limit.
Through cross-dating, missing rings were found to be typical for younger parts of older trees; in the same years younger trees instead had low growth. Some trees lacked more than 20 rings in a century. This study shows that it is possible to compensate for missing rings, at least when the number of missing rings is less than 10%.
Correlation studies showed that the growth of the tree rings was mainly due to the precipitation factor, particularly the annual precipitation one year before the ring formation, but also due to temperature. Strangely enough, multiple linear regression gave the highest correlation coefficient (0.50) for a combination of annual precipitation one year earlier and temperature four years earlier.     

多单体冰雹云降雹过程特征

１９９５年６月１４日辽宁省中南部一次多单体冰雹云降雹形成于冷锋系统，先后在４个地区降雹。当冰雹云在ＰＰＩ上回波强度大于６０ｄＢｚ，回波顶部出现Ｖ形并且在ＲＨＩ上回波宽度大于２０ｋｍ时，将出现降雹。     

陆面特征对初夏华南冷锋过程影响的数值研究

利用ＲＡＭＳ模式，对１９７９年６月一次冷锋过程进行了数值模拟，讨论了不同陆面对冷锋南下变性过程的影响，几组异常试验的结果表明，地形因素对华南地区降水有较大的影响，去掉南岭地形的动力作用后，华南到东南沿海一带低层气旋性涡度明显减小，降水量减少，而青藏高原东部和华东地区受地气交换过程和下垫面热力状况影响较显著。     

Wave front construction in smooth media for prestack depth migration

We implemented a wave front construction algorithm specifically designed for smooth media for application to prestack depth migration. The highest priority was given to maximum computational speed to allow an extension of the techniques to 3D media. A simple grid-based model representation in combination with fast bilinear interpolation is used. It is shown that this procedure has no distorting effects on the ray tracing results for smooth media. In our implementation, wave front construction (WFC) has proven to be as fast as some of the recently developed methods for travel time computations. WFC has advantages over these methods, since amplitudes and other ray theoretical quantities are available, and it is not restricted to the calculation of only first arrivals. Thus, it meets the requirements for migration in complex media. Furthermore, WFC allows for introduction of a perturbation scheme for computing travel times for slightly varying models simultaneously. This has applications for, e.g., prestack velocity estimation techniques. The importance of later arrivals for migration in complex media is demonstrated by prestack images of the Marmousi data set.     

渤海第三纪裂谷扩张的地球物理分析

根据重磁计算的结果，对渤海第三纪裂谷扩张问题做了分析。在研究中还注意参考了渤海地热流和地壳上地幔电性高导层抬升的研究成果。认为由于深部岩浆的上涌，在渤海及其相邻的陆地共有渤中、渤海湾、庙西、辽东湾和垦利５个较大的地幔柱拱起，它们在华北新生代拗陷区形成了一个走向明显、形态独特、规模较大而又相对集中的地幔柱群