一个新的季风指数及其年际变化和与雨量的关系

作者按曾庆存等所定义的标准化风场季节变率(和利用新的资料重新作了计算,为与国外传统的和至今大多数学者的定义一致,取δ*=δ-2＞0(即冬、夏风向差大于π/2)作为季风区,结果涵盖了迄今国内外所指出的全球所有季风区(但比曾庆存等算得的区域略为小些),尤其是热带季风区正处于冬季和夏季赤道幅合带(ITCZ)位置所夹的范围内.其后,用李建平和曾庆存建议的动态风场标准化季节变率δ*m=δm-2(δm形式上与δ相似,但依赖于年份m)作为各年季风指数,计算了各主要季风区区域平均的δ*m的年际变化,得到南亚夏季风和东亚夏季风自20世纪70年代中期起、南海夏季风自20世纪80年代起和西非夏季风自1967年起都有不同程度的长期减弱趋势,尤其以西非夏季风减弱最明显.西非夏季风指数和南亚夏季风指数与当地夏季雨量呈显著正相关,东亚夏季风指数与中国和东亚夏季雨量的空间分布有一定的统计相关结构,而南海夏季风指数则与全球各海区夏季降水和海平面气压异常有较好的大范围统计相关.     

地面高精度磁测在红旗岭镍矿资源接替勘查中的应用

本文简要介绍了吉林省红旗岭镍矿区地质背景,较为详细地论述了1/1万地面高精度磁测方法在矿区继续找矿方面的应用。同时对取得的磁测数据成果进行了化极、上延等处理。在此基础上对矿区构造、基性-超基性岩体成因进行了探讨,指出矿区成矿系华力西早期基性-超基性岩浆伊始于F01断裂构造深部,最终贯入至其它断裂成岩、成矿的过程。     

Intermediately complex models for the hydrological interactions in the atmosphere-vegetation-soil system

This paper investigates the hydrological interactions in the atmosphere-evegetation-soil system by using the bucket model and several new simplified intermediately complex models. The results of mathematical analysis and numerical simulations show that these models, despite their simplicity, can very clearly reveal the essential features of the rather complex hydrological system of atmosphere-ecosystem-soil. For given atmospheric variables, these models clearly demonstrate multiple timescales, the “red shift” of response spectra, multi-equilibria and limit cycles, bifurcation, abrupt change, self-organization, recovery, “desertification”, and chaos. Most of these agree with observations. Especially, the weakening of “shading effect” of living canopy and the wilted biomass might be a major mechanism leading to the desertification in a relatively short period due to overgrazing, and the desertification in a relatively long period or in climate of change might be due to both Charney’s mechanism and the shading effect. These ideas could be validated with further numerical simulations. In the paper, some methods for improving the estimation of timescales in the soil water evolution responding to the forcing are also proposed.     

Design of content-based retrieval system in remote sensing image database

IntroductionContent-based i mage retrieval ( CBIR)[1 ,2]technology was proposedin 1990s andit is a i m-age retrieval technology using i mage vision con-tents such as color ,texture ,shape ,spatial rela-tionship ,not usingi mage notationto searchi ma-ges .…     

中国中部农区农民工多阶流动及影响因素研究——以河南省6个村为例

基于田野调查深度访谈数据,采用统计分析和逐次二元Logistic方法,对农民工空间流动随时间变化的规律进行研究,提出并验证农民工多阶流动假说。研究认为,农民工对务工地的选择是一个趋于优化的动态过程,随着流动次数的增加,务工地逐渐趋于稳定,区位务工时间延长,村落附近的城镇渐成主要务工地选项,流动动因中的主观动因强化,被动动因弱化,逐次流动模型中务工年限、务工地域类型、务工者年龄、家庭人口规模、家庭耕地面积、村地形、村务工人数比例、村区位等主要因子的显著性程度和方向也发生相应变化。经过多次流动,务工地愈加符合务工者预期。     

河西走廊边界层高度与风沙强度的关系

以中国风沙高发区河西走廊为研究对象,应用河西走廊敦煌、酒泉、张掖和民勤4站2006—2017年逐日19：00每50 m加密高空资料和07：00规定层、特性层高空资料,分别采用平滑位温法、T-LnP法,统计分析了该区边界层高度的变化特征及其影响因子、边界层高度与风沙强度的关系,得出边界层高度与风沙强度成正比。进一步从地面风速、相对湿度、地气温差日变化得到春季午后风沙天气多发和强发的主要成因,得到了沙尘暴不同环流形势下的边界层高度持征,以及高空风速≥15 m·s^-1的最低高度与风沙强度的关系,从而为风沙天气预报提供技术帮助。结果表明：河西走廊年均边界层高度1 700~2 200 m,4—6月较高,在3 000 m以上,敦煌4—5月在3 500 m以上。边界层高度与最高气温、最低气温和0 cm最高地温较密切,与最高气温、极大风速成正比。边界层高度随着风沙强度的增强而增高,4月强沙尘暴和大风的边界层高度均大于3 100 m。春季风速随着风沙强度的增强而增大,最大风速集中时间在12：00—18：00,春季13：00—14：00风速最大、相对湿度最小、地气温差最大,因而也是风沙天气出现最多和强度最强的时段。沙尘暴持续时间越短,边界层越高,4—6月下午的沙尘暴较高,为2 800~3 100 m。沙尘暴不同环流形势的边界层高度中西风槽型整体较低;平直西风型4、6月和8月较高,均达3 100 m以上,8月为3 580 m;而西北气流型高于西风槽型,5—6月大于3 200 m。不同风沙强度高空风速≥15 m·s^-1的最低高度,冬春季较低,夏秋季高;浮尘较高为4 884 m,大风伴沙尘最低为2 471 m,大风沙尘暴07：00较19：00高600 m左右,明显较边界层高1 000~2 000 m。     

The Relationship between Propagation Time and Sound Velocity Profile for Positioning Seafloor Reference Points

This paper focuses on the relationship between the propagation time and the integral of the sound velocity profile (SVP) with respect to depth (SVP area for short) for positioning seafloor reference points. We proved a linear relationship between the propagation time and the SVP area and defined its mathematical expression (ST law). We showed in three simulations of possible variations in SVPs (random errors, internal waves, or a combination of both) that this ST law is verified. Using this new law in a simulated experiment, the ranging residuals due to sound velocity change through time are significantly improved. With this method, monitoring the SVP while acquiring travel times to a submerged transponder can significantly reduce the positioning errors of the transponder.     

南海北部a波和b波的生成与传播特征的数值研究

本文基于真实地形、潮汐的高分辨率三维MITgcm海洋环流模式,对南海北部a波（大振幅波列形式）和b波（孤立子形式）的生成与传播特征进行了数值研究。首先,我们总结和分析了这些波动的生成与传播特征。然后我们计算了吕宋海峡的能量收支。能量的生成在一天内有三个极大值,其中最大值对应a波的生成。吕宋海峡西边界的能通量一天内有两个极大值,较大的那个对应a波的生成而另一个对应b波的生成。我们设计了敏感性试验来探究吕宋海峡东西海脊对a、b波的生成和传播造成的影响。通过对比敏感性实验和标准试验的结果,发现对于a波的生成东海脊必不可少,但西海脊几乎没有影响。西海脊削弱了a波的振幅但未对a波波速造成明显的影响。b波来自于从东海脊生成的扰动信号。西海脊加强了这个扰动信号但减慢了它的传播速度。     

Spirulina cultivation in China

This paper reviews and discusses the development and many problems ofSpirulina cultivation in China, points out the advantages and disadvantages of open photobioreactor system, and predicts that seawaterSpirulina cultivation will be a new trend to be strengthened and emphasized due to its special physiological characteristics, easier management, lower fertilizer cost, and higher resistance to contaminants and rare pollution of chemicals.

     

Submarine landslides on the north continental slope of the South China Sea

Recent and paleo-submarine landslides are widely distributed within strata in deep-water areas along continental slopes, uplifts, and carbonate platforms on the north continental margin of the South China Sea (SCS). In this paper, high-resolution 3D seismic data and multibeam data based on seismic sedimentology and geomorphology are employed to assist in identifying submarine landslides. In addition, deposition models are proposed that are based on specific geological structures and features, and which illustrate the local stress field over entire submarine landslides in deep-water areas of the SCS. The SCS is one of the largest fluvial sediment sinks in enclosed or semi-enclosed marginal seas worldwide. It therefore provides a set of preconditions for the formation of submarine landslides, including rapid sediment accumulation, formation of gas hydrates, and fluid overpressure. A new concept involving temporal and spatial analyses is tested to construct a relationship between submarine landslides and different time scale trigger mechanisms, and three mechanisms are discussed in the context of spatial scale and temporal frequency: evolution of slope gradient and overpressure, global environmental changes, and tectonic events. Submarine landslides that are triggered by tectonic events are the largest but occur less frequently, while submarine landslides triggered by the combination of slope gradient and over-pressure evolution are the smallest but most frequently occurring events. In summary, analysis shows that the formation of submarine landslides is a complex process involving the operation of different factors on various time scales.