青藏高原区域地震波研究综述

区域地震波携带着大量的信息,可以很好地反映地壳和上地幔结构的变化.本文简要总结了青藏高原地区区域地震波的研究方法与进展;对青藏高原区域地震波研究的结论进行了总结,并探讨了它们的地质意义.最后分析了目前青藏高原区域地震波研究中存在的一些问题.     

南海北部海域叶绿素a浓度时空特征遥感分析

利用2007-2010年MODIS的L2级叶绿素a浓度产品作为数据基础, 对叶绿素a浓度年平均和月平均数据进行分级分区处理, 研究南海北部海域叶绿素a浓度时空分布特征及其与海洋环境因素的关系。初步研究结果表明:2007-2010年在南海北部海域叶绿素a浓度的高值区(>5.0 mg/m3)主要分布在广东省沿岸河流的入海口, 分布范围在夏季最大, 在春秋次之, 在冬季最小;叶绿素a浓度的次高值区(1.0～5.0 mg/m3)主要分布在海岸线到50 m等深线之间的海域, 分布范围夏冬较大, 能扩展到50 m等深线附近, 而春秋较小, 会退缩到50 m等深线以内;叶绿素a浓度的中值区(0.3～1.0 mg/m3)主要分布在50 m到100 m等深线之间的海域, 时空变化复杂;叶绿素a浓度的低值区(<0.3 mg/m3)主要分布在100 m等深线以外的海域, 其区域平均值夏季最低, 春秋次之, 冬季最高, 同时该区域叶绿素a浓度在春夏秋三季空间分布较均匀, 而冬季受季风和黑潮入侵影响空间分布较为复杂。南海北部海域海表叶绿素a浓度的时空变化特征与季风、沿岸河流、海流、海表温度等海洋环境因素的变化有关。     

Broad-scale distribution patterns of sardine and their predators in relation to remotely sensed environmental conditions during the KwaZulu-Natal sardine run

The annual movement of South African sardine Sardinops sagax up the east coast of South Africa, known as the ‘sardine run’, was investigated using data from aerial surveys for the period 1988–2005 and compared with remotely sensed sea surface temperature (SST) and chlorophyll a data. Sardine sighting rates were highest within the Waterfall Bluff Bight off the Eastern Cape Coast, where conditions appeared to be most favourable. Sardine and predator sightings decreased significantly northwards of Mdoni on the KwaZulu-Natal (KZN) coast, whereas the proportion of nearshore sightings increased. The causal mechanism for this inshore concentration is suggested to be the influx of warm Agulhas Current water from the Durban Eddy that forces sardine shoreward. Cape gannet Morus capensis, common dolphin Delphinus capensis and sardine distributions were associated, and there was an association between SST and sardine and predator distributions. There was a marked increase in bottlenose dolphin Tursiops aduncus sightings upon commencement of the sardine run, with these dolphins being consid-ered to be a ‘migratory’ stock that enters KZN waters every winter.     

银川平原土壤盐渍化与植被发育和地下水埋深关系

土壤盐渍化是制约银川平原内部植被生长最主要的生态环境地质问题,也是影响区域农业生产的第一障碍性问题。基于遥感数据,结合表层土壤含盐量及地下水位观测资料,对银川平原土壤盐渍化与植被和地下水的关系进行了定量研究。结果表明：随着表层土壤含盐量的增大,NDVI(归一化植被指数)逐渐减小,植被发育较好的区域土壤含盐量均小于3 g/kg;植被主要生长在没有盐渍化或轻微盐渍化的地区,在中度和重度盐渍化地区几乎没有植被发育;在枯水季节,研究区土壤盐渍化最严重的地下水位埋深为1.5 m,而土壤盐渍化较为严重的地下水位埋深范围为1~3 m。     

地震电磁辐射观测是短临预测重要手段之一

地震和火山活动是具有相同属性的自然现象,观测表明,在大地震及火山喷发之前的几天或几小时,均呈现有非常宽频谱的电磁辐射和电离层异常现象。本文重点描述了地震前后存在从零开始相当宽频谱的地震电磁辐射以及电离层异常等现象,并提出可利用电离层异常的观测和采用不同频段上地震电磁辐射的立体监测网,作为地震的短临预测、预报手段是现实、可行的。同时还提出了加强我国地震电磁辐射观测研究的建议。     

Comparison and validation of MODIS standard and new combination of Terra and Aqua snow cover products in northern Xinjiang,China

Taking northern Xinjiang, China, as an example, this study first compares the standard MODIS Terra and Aqua snow cover classifications, and then compares the accuracy of the standard MODIS daily and 8‐day snow cover products with the new daily and multi‐day snow cover combination of MODIS Terra and Aqua observations using in situ measurements. Under clear sky in both products, the agreement of land classification from MODIS Terra and Aqua daily and 8‐day snow cover products is close to 100% for a entire water year. In contrast, the agreement of snow classification from MODIS Terra and Aqua is high only in the winter months, decreasing in the rest of the period. The high agreement mainly concentrates in land or snow‐dominated areas, and major disagreements take place in the transitions zones from snow to land. The disagreement (mainly snow–land) in the 8‐day products is higher than that in the daily products. In addition, both MODIS Terra and Aqua cloud masks tend to map more areas in the transition zones as cloud. Under clear sky conditions, the three daily products have similar accuracy of snow and land classification, and the 8‐day standard products and the multi‐day combination product also have similar accuracy of snow and land classification. This further suggests that the algorithm in the combination of Terra and Aqua snow cover products is valid. Moreover, in the actual weather/cloud conditions, the combination products from Terra and Aqua reduce cloud blockage and improve snow classification accuracy against either MODIS Terra or Aqua (51% against 44% and 34% for daily and 92% against 87% and 78% for 8‐day, respectively), although Terra snow product (daily or 8‐day) has slightly better accuracy than the Aqua snow product. The new combination products can provide better mapping of spatiotemporal variation of snow cover/glacier and for snow‐melting modeling. Copyright © 2008 John Wiley & Sons, Ltd.     

特长公路隧道独立排烟道结构高温安全性研究

特长公路隧道的火灾安全尤其是火灾通风排烟问题日益受到特别的关注。苍岭隧道是一座长度超过7 km的公路隧道,根据多方咨询意见,其通风排烟系统采用带独立排烟道的纵向通风模式。为了判断排烟道顶隔板结构在火灾高温下的安全性,以火灾动态模拟软件FDS的分析结果为温度边界条件,通过ANSYS对火灾下与常温下顶隔板的内力及变形进行了对比分析,探讨了顶隔板在火灾下的破坏规律,得出了火灾下顶隔板的临界破坏温度及其沿隧道的纵向破坏范围。     

建立基于土地利用的交通发生量模型的研究

针对出行生成预测中变量众多以及多重相关性问题,以常州调查数据为样本,分别采用逐步回归分析方法和偏最小二乘回归（PLSR）方法,建立基于土地利用形态的交通发生量模型。并对两者建模方法进行分析比较．结果表明PLSR能有效地解决变量多重相关性问题,模型意义清晰,效果显著。     

应用物探方法检测钱塘江堤塘的初步实践

以笔者参与的钱塘江大堤某标准堤塘为例,针对其不同堤段存在的不均匀沉降、裂损以及沉降和回弹变形的某些规律性现象,通过工程特点和探测环境的具体分析,采用探地雷达、瑞雷波法和地震映像法基本查明了其原因,并对该堤段质量现状进行初步分析评价.