Comparisons of drought variability between central High Asia and monsoonal Asia: Inferred from tree rings

Severe drought is a serious natural disaster that frequently strikes East Asia, highlighting the need to understanding its drought regime and the associations with Asian monsoon. Tree-ring-based drought reconstructions provide invaluable paleoclimatic archives for detecting regional and large-scale drought variability and their potential forcings. We herein reviewed many drought reconstructions from central High Asia and monsoonal Asia and compared their similarities and differences, as well as their linkages to Asia monsoon. We compared the decadal-scale variability of six drought reconstructions for the central High Asia, where differing drought variations were found between the western and eastern portions. Seven drought reconstructions were reviewed for monsoonal Asia, from which a difference in drought variability was observed between the northern and southern parts. Therefore, we compared the drought variations of the four sub-regions of western and eastern parts of central High Asia, as well as northern and southern portions of monsoonal Asia. ENSO activity and sea surface temperature of western Pacific and northern Indian Oceans, coupled with Asian monsoon, play an important role in modulating drought variability of much area of the East Asia. An improved denser multi-index tree-ring network of longer length for East Asia is necessary for the establishment of more reliable large-scale drought reconstruction.     

Sea surface temperature and salinity reconstruction based on stable isotopes and Mg/Ca of planktonic foraminifera in the western Pacific Warm Pool during the last 155 ka

Changes in sea surface temperature(SST), seawater oxygen isotope(δ 18 O sw), and local salinity proxy(δ 18 O sw-ss) in the past 155 ka were studied using a sediment core(MD06-3052) from the northern edge of the western Pacifi c Warm Pool(WPWP), within the fl ow path of the bifurcation of the North Equatorial Current. Our records reveal a lead-lag relationship between paired Mg/Ca-SST and δ 18 O during Termination II and the last interglacial period. Similarity in SST between our site and the Antarctic temperature proxy and in CO 2 profi le showed a close connection between the WPWP and the Antarctic. Values of δ 18 O sw exhibited very similar variations to those of mean ocean δ 18 O sw, owing to the past sea-level changes on glacial-interglacial timescale. Calculated values of δ 18 O sw-ss refl ect a more saline condition during high local summer insolation(SI) periods. Such correspondence between δ 18 O sw-ss and local SI in the WPWP may refl ect complex interaction between ENSO and monsoon, which was stimulated by changes in solar irradiance and their infl uence on the local hydrologic cycle. This then caused a striking reorganization of atmospheric circulation over the WPWP.     

基于潜标测量的海洋环境噪声谱特性分析

利用海洋环境噪声测量潜标系统对南海典型海域开展了为期3个月的海洋环境噪声测量,16通道海洋环境噪声测量系统每小时测量两分钟噪声信号。数据处理结果表明,800~5 000Hz范围内,噪声谱与风速相关性最好,且风速越大相关性越好,噪声谱与风速的相关性好于与浪高的相关性。风关噪声谱级在海水中部基本不随接收深度发生变化,但由于测量水听器阵长度未能覆盖整个水深,因此未给出海面和海底处谱级变化规律。在400Hz以上的高频段整个风速范围内噪声谱级都随风速发生变化,且噪声谱级与对数风速具有很好的线性关系。     

模糊综合评判模型在宝坻水源地地下水水质评价中的应用

运用模糊综合评判模型,对中石化天津分公司宝坻水源地奥陶系灰岩地下水水质行综合评价。评价结果表明,研究区采样点水质总体评判级别为I级,说明该区地下水水质较好,而氟离子含量超标是由于地区背景值造成的,这一结论与该区其它研究成果评价结果一致。说明模糊综合评判模型是一种较实用的地下水水质评判方法。     

水源热泵井群布置方案对地下水流场影响分析

以某地下水源热泵系统工程为例,依据工程场地实际抽水-回灌试验数据,建立研究区地下水流数值模拟模型,分析该地区适宜的井群布置方案,并定量研究不同井群布置方案对地下水流场的影响范围与程度,为确定合理的井群布置方案提供技术支撑。研究表明：对于同一含水层回灌,随着抽水-回灌时间的延长,就有利于抽水-回灌能力及尽量减小对周边地下水开采的影响而言,抽水井、回灌井交叉布置,部分回灌井集中布置的方案较为合理。     

Impact of impoundment on groundwater seepage in the Three Gorges Dam in China based on CFCs and stable isotopes

It is a common concern that the groundwater flow field caused by the Three Gorges Dam changes the regional seismic activity and environment. The changes in the seepage region could be effectively reflected through the analysis of the groundwater age using chlorofluorocarbons (CFC)-based techniques. In this study, the influences of the reservoir water on groundwater and the seepage region boundary of the reservoir were investigated using CFCs, stable isotopes, and water level in groundwater, reservoir water, and spring water during the water storage process of the Three Gorges Reservoir. The results show that the water supplied by the groundwater is older, whereas the water supplied by the reservoir and the springs is younger. With an increase in the water level of the reservoir, the water in well W3, which is located at the vice dam of the head region, becomes older due to the reservoir loading effect, whereas the water in well W4 become younger due to the lateral seepage of reservoir water. This finding indicates that the groundwater seepage regions in wells W3 and W4, which are located at upstream of the reservoir, are all influenced by the Three Gorges Reservoir. In contrast, the sampling points in the northern section of the Xiannvshan fault zone, which is farther from the dam, did not exhibit any direct hydraulic connection between the groundwater and the reservoir water; thus, the reservoir seepage effects may not affect the northern part of the Xiannvshan fault zone. These research results provide important reference data that can be used to analyze the effects of the Three Gorges reservoir storage on the regional environment.     

厦门GPS基准站建设与试运行

全面叙述中国地壳运动观测网络中25个基准站之一——福建GPS基准站的设计、选址、建造和仪器安装等建设过程及试运行至今的情况和有关参数。其中对某些防护措施如防雷措施有较详细说明。为今后GPS基准站的建设提供了系统性的经验。     

高分辨率遥感卫星颤振探测的相位相关分析法

平台颤振是影响高分辨率卫星影像几何和辐射质量的关键因素。为提高从影像反演平台颤振特性的可行性和可信度,本文提出基于局部频率分析相位相关的智能化视差法颤振探测方法。通过结合结构影像表达和相位相关,并充分利用影像的局部和全局相位信息,减少了辐射变化和噪声等干扰因素对亚像素偏移值估计的影响,同时融入视差法颤振探测框架,保证精确稳健的密集匹配,从而实现高效的平台颤振精密探测。通过采用实际辐射变化数据集的算法对比及采用资源三号卫星影像的颤振探测试验验证了本文方法的有效性。结果表明,局部频率分析相位相关算法在辐射差异和噪声等情况下效果优于其他主流相位相关算法,匹配精度达到0.05个像素,本文颤振探测方法有效估计了资源三号卫星的颤振信息。     

中国小冰期气候研究综述

通过对小冰期研究文献进行综述,并对已发表的小冰期温度和降水数据进行综合对比分析,探讨小冰期时期中国气候特征的区域性.结果表明,小冰期在中国地区不同区域代用指标记录中均存在,但是小冰期的起讫及持续时间具有区域差异性,温湿配置也不尽相同.小冰期的起始时间主要呈现出由西向东推移的趋势,即青藏高原最早,华北地区次之而东部地区最晚.温湿配置的差异主要体现在东部季风区小冰期时期总体上是冷干的气候环境,而西部地区气候变化则呈现冷湿的气候特征.