西部地区特大地震活动特征及其对大华北地震趋势的影响

在分析 190 0年以来中国大陆西部特大地震 (MS≥ 7 5 )的时空分布特征的基础上 ,进一步研究了大陆西部特大地震与大华北地区强震 (MS≥ 6 0 )活动的相关特征 ,结果表明 :地震构造对西部的强震活动显示出很强的控制力 ;大华北强震与西部特大地震具有同步活动特点 ,但滞后于西部的地震活动 ;西部特大地震第 3活跃时段已经开始 ,但大华北地区出现 6级以上地震的连发还为时尚早     

应用灰色聚类分析作降水趋势预报的探讨

文章首次利用前期的预报因子进行计算，使灰色聚类分析具有了预报功能，其思路是把预报量和前期预报因子分为不同的等级，根据预报量计算等级与实际等级的历史拟合率达到最大的原则，在计算过程中，反复调整各因子的计算参数，最后得到历史拟合率最大时预报系统的等级分界值，并据此进行预报。其依据是相似的前期预报因子组合一航会出现相似的降水趋势，实例表明，其预报结果是比较好的。     

昆仑山口西8.1级地震后的强震趋势研讨

对我国大陆及邻区与西部地区1895年以来各地震期中地震能量主释放段分别进行了分析，各时期地震能量的主释放段的时长，均为7－8年；并利用各地震期累计地震频度的指数型分布模型分区拟合，得到各时期增长率；分析了2001年11月14日昆仑山口西8.1级地震后在川、滇地区发生强震的几率，最后对强震趋势和了预测研讨。     

历史地震序列类型的划分及其应用刍议

作者对我国历史地震记载特点进行了分析，探索了历史地震序列类型划分的建议方案，即根据历史地震序列的记载特点，将其分为“安全类”和“危险类”两种类型。在此基础上以山东地区为例，对山东及邻区历史地震序列分类。结果表明，区内历史地震序列中安全类约占83.9%，危险类约占16.1%，这一结果与本区现代地震序列类型划分结果大体一致，但与全国现代地震序列类型统计结果有一定差异。由于受地震史料记载详略因素的限制，上述结果是粗略的、初步的，但仍是对于现代地震序列类型信息的一种补充。所得结果可在震后早期趋势快速判定中参考。     

盖层研究现状及发展趋势

从盖层分类、封闭机理和盖层评价等三个方面对国内外盖层的研究现状进行了综述，指出了其发展趋势，即日趋综合化、动态化和定量化。     

吉林省地下流体多年趋势变化分析

通过对吉林省地下流体多年动态观测数据进行全时域的计算机扫描，系统研究其变化规律和特点，分析各种影响因素，重点分析了气象要素与水位变化的相关性，发现相关的节律性和差异性，同时确定吉林省下流体趋势异常指标，进而对吉林省近期地震趋势进行预测。     

东南沿海地区旱涝气侯准周期振荡特征及其变化趋势

本文提出干旱指数与洪涝指数二分序列，讨论了东南沿海地区1470～1993年时间序列上旱、涝气候准周期振荡特征．结果表明，旱的周期振动与涝的周期振动存在着差异，在不同的时间尺度上都有所反映，作周期分析时有必要分别寻求旱与涝各自的周期振动分量．结果还表明，太阳活动11年周期，22年磁周期和日月地相对运动19年周期，都与该区旱涝长期变化存在着较强的统计对应关系，并且太阳活动强弱世纪周期对其长期变化也有一定的影响。     

A Seasonal Comparison of the Ozone Photochemistry in Clean and Polluted Air Masses at Mace Head, Ireland

Measurements of the sum of peroxy radicals [HO₂ + RO₂],NO_x (NO + NO₂) and NO_y (the sum of oxidisednitrogen species) made at Mace Head, on the Atlantic coast of Ireland in summer 1996 and spring 1997 are presented. Together with a suite of ancillary measurements, including the photolysis frequencies of O₃ O(¹D)(j(O¹D)) and NO₂ (j(NO₂)), the measured peroxy radicals are used to calculate meandailyozone tendency (defined as the difference of the in-situphotochemical ozone production and loss rates); these values are compared with values derived from the photochemical stationary state (PSS) expression. Although the correlation between the two sets of values is good, the PSS values are found to be significantly larger than those derived from the peroxy radical measurements, on average, in line with previous published work. Possible sources of error in these calculations are discussed in detail. The data are further divided up into five wind sectors, according to the instantaneous wind direction measured at the research station. Calculation of mean ozone tendencies by wind sector shows that ozone productivity was higher during spring (April–May) 1997 than during summer (July–August) 1996across all airmasses, suggesting that tropospheric photochemistry plays an important role in the widely-reported spring ozone maximum in the Northern Hemisphere. Ozone tendencies were close to zero for the relatively unpolluted south-west, west and north-west wind sectors in the summer campaign, whereas ozone productivity was greatest in the polluted south-east sector for both campaigns. Daytime weighted average ozone tendencies were +(0.3± 0.1) ppbv h^–1 for summer 1996 and +(1.0± 0.5) ppbvh^–1 for spring 1997. These figures reflect the higher mixing ratios of ozone precursors in spring overall, as well as the higher proportion of polluted air masses from the south-east arriving at the site during the spring campaign. The ozone compensation point, where photochemical ozone destruction and production processes are in balance, is calculated to be ca. 14 pptv NO for both campaigns.     

区域经济地理学发展回顾与展望

区域经济地理学作为既古老又年轻的地理学分支,经历了萌芽、形成与发展过程。受到实践领域、认知领域、方法技术领域和相邻学科发展的影响,其理论、方法和实践都经历全面而深刻的变革,在世纪之交已显示出面向区域经济可持续发展,运用系统思维方法和信息技术手段,建设完善而开放的学科理论体系的发展趋势。     

Unusual Behavior of the Kuroshio Current System from Winter 1996 to Summer 1997 Revealed by ADEOS-OCTS and Other Data (Continued): A Study from Broad External Conditions with Bottom Topography

In the previous paper (Toba and Murakami, 1998) we reported on an unusual path of the Kuroshio Current System, which occurred in April 1997 (April 1997 event), using the Ocean Color and Temperature Scanner (OCTS) data of the Advanced Earth Observing Satellite (ADEOS). The April 1997 event was characterized by the flow of the Kuroshio along the western slope (northward) and the eastern slope (southward) of the Izu-Ogasawara Ridge, a very southerly turning point at about 32°N, followed by a straight northward path up to 37°N of the Kuroshio Extension along the eastern flank of the Izu-Ogasawara and the Japan Trenches. Overlaying of depth contours on ADEOS-OCTS chlorophyll-a images at the April 1997 event demonstrates the bottom topography effects on the current paths. A new finding based on TOPEX/Poseidon altimeter data is that the sea-surface gradient across the Kuroshio/Kuroshio Extension diminished greatly in the sea area southeast of the central Japan, as a very temporary phenomenon prior to this event. This temporary diminishing of the upper-ocean current velocity might have caused a stronger bottom effect along the Izu-Ogasawara Ridge, and over the Izu-Ogasawara Trench disclosed a weak background, barotropic trench-flank current pattern, which existed otherwise independently of the Kuroshio Extension. The very southerly path of the Kuroshio Extension from winter 1996 to autumn 1998 corresponded, with a time lag of about 1.5 years, to the previous La Niña tendency with weaker North Equatorial Current. The April 1997 event occurred in accordance with its extreme condition.