风廓线雷达探测降水过程的初步研究

为利用风廓线雷达 (WPR) 开展降水研究, 分析了2006年8月25-26日北京延庆WPR探测降水个例。降水前高空出现持续时间长达10h以上的水平风垂直切变; 在信噪比 (SNR) 时间序列资料中出现比较清晰的SNR极值层, SNR极值层所处高度与水平风垂直切变高度相吻合。降水期间及前后, 水平风探测高度明显增高2km以上。随地面降水的临近, 下降速度所处高度逐渐降低, 从高空一直延伸到低空, 持续时间长达10h。资料分析表明:国产WPR可以在降水天气工作, 其探测资料能及时反映大尺度流场的变化。通过WPR提供的功率谱密度、SNR、水平速度、垂直速度等多种资料, 可从多种角度了解降水过程; 特别是WPR可以同时探测垂直气流速度、粒子落速及其高度分布, 进而可以估计降水粒子尺度谱及其高度分布, 便于开展更深层次的降水物理过程研究。     

微型生态系统中鲢、鳙下行影响的实验研究——1.浮游生物群落和初级生产力

在营养物供给量较大的实验条件下,鲢、鳙放养明显地改变了微型生态系统的群落结构、代谢和理化环境,以致实验后期鳙单养和鲢、鳙混养系统出现不同程度的富营养化。微型生态系统中浮游植物密度的增长不完全由营养级联效应所致,但初级生产力的组间差异可大致依据营养级联假说来解释。实验结果认为,以提高鱼产量为目标的鲢、鳙高密度放养,对加速营养物来源丰富的天然水域的富营养化起着重要的作用。     

ANALYSIS OF Cu, Cd, Co AND Ni IN SURFACE WATER OF THE KUROSHIO AREA IN THE EAST CHINA SEA

Study of 1986 and 1987 heavy metal distribution in surface water of the Kuroshio area in the East China Sea showed regional and slight seasonal variations in distribution and concentration . Heavy metal levels in Taiwan Strait, the sea area north of Taiwan and the continental shelf are higher than those in the main axis of the Kuroshio . Dissolved Cu in summer and winter decreases with the increase of salinity , but dissolved Cd has no obvious change with salinity .     

Quantitative detection of mass concentration of sand-dust storms via wind-profiling radar and analysis of <Emphasis Type="Italic">Z</Emphasis>-<Emphasis Type="Italic">M</Emphasis> relationship

With the aim to achieve quantitative monitoring of sand-dust storms in real time, wind-profiling radar is applied to monitor and study the process of four sand-dust storms in the Tazhong area of the Taklimakan Desert. Through evaluation and analysis of the spatial-temporal distribution of reflectivity factor, it is found that reflectivity factor ranges from 2 to 18 dBz under sand-dust storm weather. Using echo power spectrum of radar vertical beams, sand-dust particle spectrum and sand-dust mass concentration at the altitude of 600 ～ 1500 m are retrieved. This study shows that sand-dust mass concentration reaches 700?μg/m³ under blowing sand weather, 2000?μg/m³ under sand-dust storm weather, and 400?μg/m³ under floating dust weather. The following equations are established to represent the relationship between the reflectivity factor and sand-dust mass concentration: Z?=?20713.5?M ^0.995 under floating dust weather, Z?=?22988.3?M ^1.006 under blowing sand weather, and Z?=?24584.2?M ^1.013 under sand-dust storm weather. The retrieval results from this paper are almost consistent with previous monitoring results achieved by former researchers; thus, it is implied that wind-profiling radar can be used as a new reference device to quantitatively monitor sand-dust storms.     

上地幔各向异性研究综述及在川滇地区的研究思路

简要介绍了地球介质各向异性研究的发展历程,重点介绍了国内外有关上地幔各向异性的研究工作及成果;阐述了上地幔各向异性的起源及其地球动力学意义;较详细地分析了上地幔各向异性研究的各种方法及其优缺点;论述了川滇地区各向异性研究的意义和目的,并提出了整个研究工作的内容和步骤.     

Scour development around submarine pipelines due to current based on the maximum entropy theory

This paper presents the results from laboratory experiments and theoretical analysis to investigate the development of scour around submarine pipeline under steady current conditions. Experiments show that the scour process takes place in two stages: the initial rapid scour and the subsequent gradual scour development stage. An empirical formula for calculating the equilibrium scour depth (the maximum scour depth) is developed by using the regression method. This formula together with the maximum entropy theory can be applied to establish a formula to predict the scour process for given water depth, diameter of pipeline and flow velocity. Good agreement between the predicted and measured scour depth is obtained.     

A rock fall of the north Zhongtiao Shan fault and the Yongji earthquake in 793, Shanxi Province,North China

Earthquake is the main driving factor of landslides, and a large number of empirical formulas for seismic parameters have been proposed. This article studies a rock avalanche triggered by a paleoearthquake and two trial trenches in Yongji, Shanxi Province. Six quartz samples were collected from different parts on the top of the boulder, and the youngest ¹⁰Be exposure age is 1173 ± 123 years, which is considered as the occurrence time of the rock fall. The trenches excavated near the boulder infer that there was an earthquake between 2000 ± 110 and 465 ± 45 cal a bp in the north Zhongtiao Shan (NZS) fault with a maximum vertical displacement of 1.5 m and the surface rupture length (SRL) of ~35 km corresponding to a magnitude (M _S) of 6.70 ± 0.12 based on the displacement. Taking into account the occurrence time and minimum magnitude triggering the rock fall, the latest paleoearthquake revealed by trenches may be the forcing factor. Furthermore, according to historical records of Yongji, the earthquake of magnitude 6 in ad 793 is in consistency with the occurrence time and magnitude of the earthquake triggering the landslide. Therefore, the rock fall is related to the paleoearthquake revealed by the trenches, which may be the 793 Yongji earthquake.     

台湾海峡海域表观耗氧量之研究

台湾海峡海域1983－1988年多次调查资料表明，该海域夏季表现耗氧量（AOU）变化幅度较大，其分布特征呈近岸、底层高，向上层、外海递减，诸上升流是其主要控制因素。各上升流区AOU与温度、盐度、诸营养盐呈显著相关关系。PO4／AOU与NO3／AOU比值平均分别为0.0058和0.076。上升流海域夏季初始营养盐[PO4,pre和[NO3,pre较低，而再生营养盐高，是现场营养盐的主要部分。有机物质分解耗氧对AOU的贡献比浮游动物等呼吸耗氧更重要。