Infiltration at the Tai rain forest (Ivory Coast): Measurements and modelling

Infiltration experiments have been performed at three sites along a well-known catena under virgin tropical rain forest using a portable sprinkling infiltrometer. Experimentally determined infiltration curves are presented. Infiltration curves are also simulated on the basis of the Mein-Larson equation. The parameters for this model have been obtained from the infiltration curves (saturated conductivity) and simple soil moisture determinations (fillable porosity). The agreement between experimentally determined and modelled infiltration is reasonable, provided (a) saturated conductivity as derived from the experimental data is corrected, (b) a storage parameter, also derived from the experimental data, is added to the Mein-Larson model, and (c) the decline in soil porosity with depth is either small or occurs abruptly at shallow depth. Comparison of observed infiltration rates with rainfall intensity shows that Horton Overland Flow has to occur naturally at least on the middle and lower section of the catena. Despite the fact that most parameters can be estimated in principle from basic soil data, it remains advisable to obtain sprinkling infiltrometer field measurements, because of soil variability due to dynamic surface conditions, macroporosity, air entrapment, and irregularity of the wetting front.     

Atmospheric forcing of the eastern tropical Pacific: A review

The increase in marine, land surface, atmospheric and satellite data during recent decades has led to an improved understanding of the air–sea interaction processes in the eastern tropical Pacific. This is also thanks to extensive diagnoses from conceptual and coupled ocean–atmosphere numerical models. In this paper, mean fields of atmospheric variables, such as incoming solar radiation, sea level pressure, winds, wind stress curl, precipitation, evaporation, and surface energy fluxes, are derived from global atmospheric data sets in order to examine the dominant features of the low level atmospheric circulations of the region. The seasonal march of the atmospheric circulations is presented to depict the role of radiative forcing on atmospheric perturbations, especially those dominating the atmosphere at low levels.In the tropics, the trade winds constitute an important north–south energy and moisture exchange mechanism (as part of the low level branch of the Hadley circulation), that determines to a large extent the precipitation distribution in the region, i.e., that associated with the Inter-Tropical Convergence Zone (ITCZ). Monsoonal circulations also play an important role in determining the warm season precipitation distribution over the eastern tropical Pacific through a large variety of air–sea–land interaction mechanisms. Westward traveling waves, tropical cyclones, low latitude cold air intrusions, and other synoptic and mesoscale perturbations associated with the ITCZ are also important elements that modulate the annual rainfall cycle. The low-level jets of the Gulf of California, the Intra-Americas Sea (Gulf of Mexico and Caribbean Sea) and Chocó, Colombia are prominent features of the eastern tropical Pacific low-level circulations related to sub-regional and regional scale precipitation patterns. Observations show that the Intra-Americas Low-Level Jet intensity varies with El Niño/Southern Oscillation (ENSO) phases, however its origin and role in the westward propagation and development of disturbances that may hit the eastern tropical Pacific, such as easterly waves and tropical cyclones, are still unclear. Changes in the intensity of the trade winds in the Caribbean Sea and the Gulf of Mexico (associated with eastern tropical Pacific wind jets) exert an important control on precipitation by means of wind–topography interactions. Gaps in the mountains of southern Mexico and Central America allow strong wind jets to pass over the continent imprinting a unique signal in sea surface temperatures and ocean dynamics of the eastern tropical Pacific.The warm pools of the Americas constitute an important source of moisture for the North American Monsoon System. The northeastern tropical Pacific is a region of intense cyclogenetic activity, just west of the coast of Mesoamerica. Over the oceanic regions, large-scale properties of key variables such as precipitation, moisture, surface energy fluxes and wind stress curl are still uncertain, which inhibits a more comprehensive view of the region and stresses the importance of regional field experiments. Progress has been substantial in the understanding of the ocean and atmospheric dynamics of the eastern tropical Pacific, however, recent observational evidence such as that of a shallow meridional circulation cell in that region, in contrast to the classic concept of the Hadley-type deep meridional circulation, suggests that more in situ observations to validate theories are still necessary.This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific Ocean.     

热带地区流场异常与江淮特大暴雨成因的研究

本文通过计算和对比分析，得到１９９１年春、夏江淮地区特大暴雨形成的五个基本特征：西北太平洋上副高显著偏西、偏北；较弱的西南季风与东南气流汇合成强西南气流伸向江淮地区；偏东风与强西南风形成的辐合带在江淮地区维持；江淮地区对流层中下部为强上升运动、上部为辐散；１３０°Ｅ附近南半球向北半球的较强越赤道气流持续。     

Validation of Jason and Envisat Altimeter Dual Frequency Rain Flags

New rain flags based on the dual frequency capabilities of the new Jason Poseidon-2 and Envisat RA2 altimeters have been tested, developed and adopted for the operational processing of the altimeter data. Their validation conducted during the calibration/validation phases of the satellites is presented here. The Jason flag is validated by comparison with the TOPEX one, using the Tandem mission. The results show a very good agreement between the two sensors and the two rain flags The Envisat flag is validated by comparison with both Jason and TOPEX using global and collocated data sets. The results show similar performances for the three sensors. The f relations estimated during the calibration-validation period and presented here have been given to the altimeter ground processing facilities for operational use.     

合浦珠母贝卵子电击脉冲参数的初步研究

运用电脉冲转基因仪对合浦珠母贝卵子进行电脉冲处理以优化电穿孔法转基因的电击参数。实验中调制百分比：100％；脉冲间隔：1．0s：电极距离：2mm；脉冲个数：5个，参数保持不变。用不同的电脉冲参数组合（脉冲电压100-400V、脉冲持续时间0．5～3．0ms、脉冲频率10～50kHz，共28个组合）对卵子电击，然后加入精子进行授精，统计各组受精率和孵化率，以受精率和孵化率达到50％以上为衡量指标。结果表明，合浦珠母贝卵子对低脉冲频率和高电压非常敏感，当频率低于20kHz或脉冲电压高于400V时对卵子损伤较大。脉冲持续时间对其影响不大，适应范围较宽。优化的转基因电击脉冲参教组合为：脉冲电压1.0kV／cm，脉冲持续时间20ms，脉冲频率50kHz，或者脉冲电压1．5kV／cm，脉冲持续时间1．5ms，脉冲频率50kHz。     

液体中光声信号吸收衰减的研究

研究水的声吸收所引起的光声脉冲幅度的变化。脉冲声波由激光通过光击穿机制产生。文中给出了光声脉冲峰值声压与传播距离和声吸收系数之间的理论关系式。实验测量结果和理论曲线所描述的变化规律相符合。     

酸雨的研究进展及厦门酸雨研究的趋势

本文综述了国内外酸雨的研究现状；包括酸雨的来源、成因、模式、影响及防治对策；介绍了酸雨的研究趋势；并着重就厦门地区今后酸雨的研究方向提出也作者的看法。     

基于时刻独立脉冲耦合神经网络的高空间分辨率摇感影像分割

高空间分辨率遥感影像中地物目标内部光谱信息复杂性的增强,使得传统基于光谱特征值的数据处理方法效果不再显著,影像分割为解决这一问题提供了一种思路,成为当前高空间分辨率遥感影像处理的研究焦点.时刻独立脉冲耦合神经网络具有状态相近、空间相邻神经元相互耦合同步脉冲激发和区域之间神经元脉冲激发时刻独立两大特点,已被应用于非遥感影像分割中,并取得较好效果.本文结合高空间分辨率遥感影像特点,通过对网络参数进行实验和分析,提出一个基于时刻独立脉冲耦合神经网络的高空间分辨率遥感影像分割方法,并利用空间分辨率0.3m的航空影像进行了数据试验,将分割结果进行讨论并与现有时刻独立脉冲耦合神经网络方法和ISODATA方法分割结果进行对比分析.结果表明:时刻独立脉冲耦合神经网络在高空间分辨率遥感影像分割处理中具有很好的应用前景.     

成都经济区天降水与下渗水元素地球化学特征及土壤元素输入输出通量

论文研究了成都经济区天降水和下渗水中元素含量、在农田耕层中的输入输出通量及其影响因素.研究表明,研究区雨水中含有大量SO2-4、NO-3等酸性物质,雨水中SO2-4 >NO-3>Cl-.雨水中Ca2 和NH 4含量最高,且NH 4>Ca2 >K >Na >Mg2 .雨水的pH与阴、阳离子摩尔浓度差值具有显著相关性.下渗水中以Ca2 为主要阳离子,且Ca2 >Na >Mg2 >K >NH 4;HCO-3为主要阴离子,且HCO-3>NO-3>SO2-4>Cl->F-,下渗水pH与阳、阴离子摩尔浓度差值具有显著相关性.不同地区雨水中Pb>As>Cd>Se>Hg,下渗水中Pb>As>Se>Cd>Hg,因此,Cd、Pb、Se和Hg等元素累积在耕层中,而As则被下渗水携带迁移出耕层进入地下水.由降雨输入土壤中的Cd通量均大于下渗水输出Cd的通量,局部地区As下渗通量高于雨水输入通量的5.45～13.16倍.土壤中元素的下渗比与土壤质地、pH有关.     

Preserved paleo-oceanic plateaus in accretionary complexes: Implications for the contributions of the Pacific superplume to global environmental change

We have reinvestigated the mid-Cretaceous plume pulse in relation to paleo-oceanic plateaus from accretionary prisms in the circum-Pacific region, and we have correlated the Pacific superplume activity with catastrophic environmental changes since the Neoproterozoic. The Paleo-oceanic plateaus are dated at 75–150 Ma; they were generated in the Pacific superplume region and are preserved in accretionary prisms. The volcanic edifice composed of both modern and paleo-oceanic plateaus is up to 10.7 × 10⁶ km² in area and 19.1 × 10⁷ km³ in volume. The degassing rate of CO₂ (0.82 − 1.1 × 10¹⁸ mol/m.y.) suggests a significant impact on Cretaceous global warming. The synchronous occurrence of paleo-oceanic plateaus in accretionary complexes indicates that Pacific superplume pulse activities roughly coincided at the Permo-Triassic boundary and the Vendian–Cambrian boundary interval. The CO₂ expelled by the Pacific superplume probably contributed to environmental catastrophes. The initiation of the Pacific superplume contributed to the snowball Earth event near the Vendian–Cambrian boundary; this was one of the most dramatic events in Earth's history. The scale of the Pacific superplume activity roughly corresponds to the scale of drastic environmental change.