Formation mechanism of the cold-water belt formed off the soya warm current

The cold-water belt (CWB) is frequently formed off the Soya Warm Current (SWC) during summer and autumn. The detailed distribution of the flow and temperature fields observed by the R/V Sinyo-maru in the summer of 2001 captured the structures of the SWC and the CWB. The temperature and density distributions showed that the vertical distribution of the CWB is associated with the upwelling formed off the SWC. Numerical experiments using a two-layer model with realistic bottom topography have been performed to understand the formation mechanism of CWB and the upwelling structure off the current. In the experiment, the sea level difference between the Japan Sea and the Okhotsk Sea, and baroclinic flow assuming the Tsushima Warm Current were given along the open boundary. The numerical model well reproduces the current system of the SWC and upwelling region off it. The upwelling region is formed at the Soya Strait first, and then it spreads on the offshore side along the SWC as a developing current system. Analysis of the model data indicated that the geostrophic balance mainly dominates in the current system, while convergence of the bottom Ekman transport due to the SWC forms the upwelling region as the secondary circulation. In addition, the advection effect due to the SWC is found to strengthen the upwelling.     

Numerical Study of the Generation and Propagation of Trigger Meanders of the Kuroshio South of Japan

We examine the processes underlying the generation and propagation of the small meander of the Kuroshio south of Japan which occurs prior to the transition from the non-large meander path to the large meander path. The study proceeds numerically by using a two-layer, flat-bottom, quasi-geostrophic inflow-outflow model which takes account of the coastal geometries of Kyushu, Nansei Islands, part of the East China Sea, and the Izu Ridge. The model successfully reproduces the observed generation and propagation features of what is called "trigger meander" until it passes by Cape Shiono-misaki; presumably because of the absence of the bottom topography, the applicability of the present numerical model becomes questionable after the trigger meander passes by Cape Shiono-misaki. The generation of the trigger meander off the south-eastern coast of Kyushu is shown to be associated with the increase in the supply of cyclonic vorticity by the enhanced current velocity in the upper layer along the southern coast of Kyushu where the no-slip boundary condition is employed. Thereafter, the trigger meander propagates eastward while inducing an anticyclone-cyclone-cyclone pair in the lower layer. The lower-layer cyclone induced in this way, in particular, plays a crucial role in intensifying the trigger meander trough via cross-stream advection in the upper layer; the intensified trigger meander trough then further amplifies the lower-layer cyclone. This joint evolution of the upper-layer meander trough and the lower-layer cyclone indicates that baroclinic instability is the dominant mechanism underlying the rapid amplification of the eastward propagating trigger meander.     

Summer and winter drought in a cold desert ecosystem (Colorado Plateau) part I: effects on soil water and plant water uptake

We investigated the effects of winter and summer drought on plants of the Colorado Plateau in western North America. This winter-cold, summer-hot desert region receives both winter and summer precipitation. Droughts were imposed for two consecutive years using rainout shelters. Here, we examine drought effects on the hydrologic interactions between plants and soil. We chose three perennial species for this study, representing different rooting patterns and responsiveness to precipitation pulses: Oryzopsis hymenoides, a perennial bunch grass with shallow roots; Gutierrezia sarothrae, a subshrub with dimorphic roots; and Ceratoides lanata, a predominantly deep-rooted woody shrub. Drought effects on plant water status were qualitatively similar among species, despite morphological differences. Summer drought affected the water status of all species more negatively than winter drought. Isotopic analysis of stem water revealed that all three species took up deeper soil water under drought conditions and shallow soil water after a large rainfall event in summer. Thus all three species appeared to use the same water sources most of the time. However, after a particularly dry summer, only the deepest-rooted species continued to take up soil water, while the more shallow-rooted species were either dead or dormant. Our study suggests therefore that increased occurrence of summer drought could favor the most deep-rooted species in ecosystem.     

成都市多目标地球化学调查和双层采样的效果

成都平原多目标地球化学调查在元素基准值及分布特征，构造、农业、环境污染的研究，天然气的预测，pH值的计算等方面都取得了进展。调查中所采的深层样对于研究深部元素分布、构造、根深作物发育、天然气预测；浅层样对于浅层元素分布、农业地质、环境污染等方面有着特殊的作用。多目标地球化学调查及其双层采样方法可以推广。     

移动荷载下黏弹性半空间体上双层板的动力响应

采用黏弹性半空间体上无限大双层板模型模拟路面结构,通过三重Fourier积分变换得到单位脉冲荷载作用下路面动力响应的Green函数。根据线性系统的叠加原理,利用广义Duhamel积分推导出移动荷载作用下路面动力响应的解析解。采用自适应Simpson法编制了计算奇异、振荡函数的广义积分计算程序,完成了路面动力响应从波数-频率域到时间-空间域的转换。结合算例,对移动荷载作用下路面的振动规律进行研究,讨论上、下层板厚度和板材料的弹性模量对路面动力响应的影响,明确了路面结构的振动特性,研究结果可为路面结构的设计、施工提供理论指导。     

内孤立波作用下顶部张紧式立管动力特性

基于内孤立波mKdV理论,采用考虑内流的细长杆动力学方程,结合改进的Morison公式,研究两层流体中内孤立波与顶张立管的相互作用问题。针对东沙群岛南部海域附近某实测内孤立波特征参数,计算分析在该内孤立波作用下某顶张立管的内孤立波载荷与运动响应,以及立管横截面弯矩及其应力的变化特性。研究表明,内孤立波不仅会对顶张立管产生突发性的冲击载荷以及大幅度水平变形,而且还会使其横截面弯矩及其应力显著增大。因此在深海立管的设计与应用中,内孤立波的影响是不可忽视的。     

Nocturnal basin low-level jets: an integrated study

Low-level jets (LLJs) are a very common feature in the nocturnal stably stratified boundary layer. Many factors can intervene in their generation, linked basically to effects of baroclinity. A special kind of low-level jets is composed by the nocturnal katabatic and basin flows, generated over terrain slopes. A study of observed LLJs in the Duero Basin is shown here, combining observational data and modelling experiments. Normalized in respect to the maximum wind height, the dynamic characteristics of the jets are similar: a two-layer system, with a stably stratified layer below the jet maximum and a near neutral layer above, with a very stable layer separating them at the level of the wind maximum. There is vertical mixing above and below the jet, and the connection between these layers takes place occasionally in a very turbulent manner.     

遥感反演土壤蒸发/植被蒸腾二层模型在华北地区的应用

利用一种可操作的地表蒸散遥感反演二层模型,以我国华北平原为研究区,选择2004年的3月至6月华北地区主要农作物冬小麦的生长季节作为研究时段,利用MODIS遥感卫星数据,结合地面130多个气象台站的空气温湿度实测数据,实现了土壤蒸发和植被蒸腾的反演。采用国家生态网络禹城综合试验站利用涡度相关系统观测的地表总蒸散半小时平均的数据进行了模型验证,结果表明模型估算的地表可利用能量与地面实测数据的相关系数可以达到0.92,均方差为30.4w.m^-2;模型估算的地表总蒸散值与地面实测数据的相关系数为0.85,均方差为21.3 w.m^-2,由此证明了模型的可用性。     

蜜网系统的研究与设计

深入研究了蜜网系统，构建了一个基于二层网关技术的蜜网，并对其中的关键技术做了分析，给出了具体的解决方案。     

An operational two-layer remote sensing model to estimate surface flux in regional scale: Physical background

Based on the improved interaction mechanism of two-layer model, this paper proposed Pixel Component Arranging and Comparing Algorithm (PCACA) and theoretically positioning algorithm, estimated the true temperature of mixed pixel in four extreme points in combination with the measurements of dry and wet points in calibration fields and improved the reliability of positioning dry and wet line. A new two-layer energy-separation algorithm was proposed,which was simple and direct without resistance network parameters for each pixel. We also proposed a new thought about the effect of advection. The albedo of mixed pixel was also separated with PCACA. In combination with two-layer energy-separation algorithm, the net radiation of mixed pixel was separated to overcome the uncertainty of conventional energy-separation algorithm using Beer's Law. Through the validation of retrieval result, this method is proved to be feasible and operational. At the same time, the uncertainty of this algorithm was objectively analyzed.