An algorithm for determination of aerosol opticalthickness from AVHRR imagery over oceans

Summary The uncertainty in aerosol size distributions is a main source of errors in aerosol optical thickness determined from satellite measurements. To reduce the errors resulting from the uncertainty in aerosol size distributions, we have performed sensitivity analyses. It is found the errors resulting from the uncertainty in aerosol size distribution can be considerably reduced by using the Junge power law to approximate the aerosol size distribution in an actual atmosphere, if the exponent value is determined at the same time. An iterative algorithm is then developed for the simultaneous determination of aerosol optical thickness and the exponent of the Junge power law over ocean areas from the upwelling radiances measured in AVHRR visible and near infrared channels. A number of numerical experiments are carried out to investigate the validity of the Junge power law approximation by assuming the aerosol size distributions in an actual atmosphere are bimodal with different mode parameters, and by using the actual aerosol size distributions determined at several places by Kaufman et al. (1994). The results show that the errors in determined aerosol optical thickness resulting from the Junge power law approach are significantly reduced. The iterative algorithm is investigated further by comparing the aerosol optical thickness deduced from satellite measurement with that observed by a sun photometer. Received October 10, 2001 Revised December 28, 2001     

科技论文英文部分的书写规范化探讨

为方便与国际交流，许多科技期刊都要求论文的题名、摘要、关键词等翻译成英文。本文对科技论文英文部分的规范化进行了一些探讨。     

阿尔金地区构造应力场及其对金属矿产分布的控制作用

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海拉尔盆地含油气系统

海拉尔盆地为中－新生代的断陷－坳陷型盆地，其发育演化主要经历了地壳隆起、断陷、坳陷、萎缩四个阶段。根据对成藏要素分析，确定出以凹陷为单元的三类含油气系统，各含油气系统都有各自的形成和分布规律。按其空间展布，又可划分为同期并列式、同期交叉式、异期叠合式三种组合形式。这些形式的有效组合，构成了海拉尔盆地内有利的油气聚集带。     

隔震及超高层建筑的地震反应观测

2001年5月24日和6月20日分别发生了宜良4.2级和呈南3.6级两次地震，架设在云南省抗震培训中心隔震大楼和昆明佳华广场的结构强震观测台阵记录了这两栋建筑物对这两次地震反应。本介绍了获取的记录，并分析了两栋建筑物的地震反应情况。     

液化场地桩-土-桥梁结构动力相互作用振动台试验研究进展

本文在全面归纳与总结液化场地桩－土－桥梁结构动力相互作用振动台试验及与之相关领域的国内外研究进展基础上，直接针对我国桥梁工程中的主要震害问题，提出在我国开展液化场地桩－土－桥梁结构动力相互作用振动台试验研究的必要性，并阐述作者对液化场地桩－土－张桥梁结构动力相互作用振动台试验中若干问题的认识。     

基于Exchange Server 5.0前兆网络邮件系统的建立

各省地震局 95 - 0 1- 0 2地震信息网络项目采用的邮件系统是基于 IRIX 6 .5操作系统的Netscape Mail Server2 .0 ,由于其应用与管理有局限性 ,笔者进行了基于 NT系统的 ExchangeServer5 .0邮件系统的应用研究 ,详细论述了基于 Exchange Server5 .0的黑龙江省地震前兆信息网络邮件系统的安装及配置过程 ,得出该网络邮件系统有管理方便、功能强大的结论     

区域经济空间集中化的产业成因分析——兼析海南省经济空间集中化问题

经济空间集中化起因于产业经济活动在一定空间内聚集并形成大规模的专业化生产，它以区域城市为增长中心，与区域产业结构转变有着密切的关系。经济空间集中化过程大致可以划分为三个与区域产业结构转变有关的经济增长阶段：初级阶段——均衡低速增长；中级阶段——集中快速增长；高级阶段——稳定增长。     

Velocity profile of a sand cloud blowing over a gravel surface

Particle dynamic analyzer (PDA) measurement technology was used to study the turbulent characteristics and the variation with height of the mean horizontal (in the downwind direction) and vertical (in the upward direction) particle velocity of a sand cloud blowing over a gravel surface. The results show that the mean horizontal particle velocity of the cloud increases with height, while the mean vertical velocity decreases with height. The variation of the mean horizontal velocity with height is, to some extent, similar to the wind profile that increases logarithmically with height in the turbulent boundary layer. The variation of the mean vertical velocity with height is much more complex than that of the mean horizontal velocity. The increase of the resultant mean velocity with height can be expressed by a modified power function. Particle turbulence in the downwind direction decreases with height, while that in the vertical direction is complex. For fine sands (0.2–0.3 mm and 0.3–0.4 mm), there is a tendency for the particle turbulence to increase with height. In the very near-surface layer (<4 mm), the movement of blown sand particles is very complex due to the rebound of particles on the bed and the interparticle collisions in the air. Wind starts to accelerate particle movement about 4 mm from the surface. The initial rebound on the bed and the interparticle collisions in the air have a profound effect on particle movement below that height, where particle concentration is very high and wind velocity is very low.     

Dynamic processes of a simple linear dune—a study in the Taklimakan Sand Sea, China

Samples of dune sands, surveys of the morphology and field measurements of wind velocity and direction of a simple linear dune in Taklimakan Sand Sea show that the airflow and sand flux vary with the change of wind direction on the dune surface. Decrease of the airflow stress on the lee flank does not result in much decrease of the sand flux because of the low threshold shear velocities and the airflow conditions. There are no significant relations between the sand flux on the lee flank and the angle of incidence of the airflow. The low threshold shear velocities and the maintenance of the sand flux at the lee flank are the main mechanisms keeping the linear shape of the dunes. Measurements of the sand flux shows that it reaches a maximum on the crest of the dune. The grain size of the transported sands has some differences compared to that of the dune surface. The sands transported are finer than that on the dune surface, but better sorted under the influence of the medium to low wind activity. The field experiment results exhibit that it is possible for the dunes to be shaped as linear dunes during the processes of accumulation and elongation.