西藏地区气象自动站夏季逐时降水资料特征分析   总被引：1，自引：0，他引：1  

列杰班宗  罗布  王伟 《高原山地气象研究》2012,32(2):77-80

本文选用2008、2009年西藏地区具有代表性的5个自动站夏季逐时降水资料分析了两年间逐小时降水出现的频数和降水比率。结果表明:(1)各站的夏季逐时降水频率特征不尽相同但也有规律可循,既处在河谷地区的站点多夜雨,在相对平缓地区的站点逐时降水频率较为分散;(2)各站的夏季逐时降水比率呈短时集中现象,表现出高原地区多短时强对流天气的特征;(3)在有降水发生时次地面温度跟逐时降水频次和降水比率呈良好的负相关,相关系数分别为-0.58、-0.44;相对湿度跟逐时降水频次和降水比率呈良好的正相关,相关系数分别为0.56、0.46。   相似文献   

1980-2009年西藏地区水汽输送的气候特征   总被引：1，自引：0，他引：1  

卓嘎  罗布  周长艳 《冰川冻土》2012,34(4):783-794

利用1980-2009年NCEP/NCAR月平均再分析格点资料, 分析了近30 a来西藏地区水汽输送的气候特征. 结果表明: 1)西边界和南边界为水汽流入边界, 北边界和东边界为水汽流出边界; 夏季水汽总输入量最大, 冬季最小且季节差异显著; 春季水汽总输出量最大, 冬季最小且季节差异不明显; 春、 冬季为净水汽支出, 夏、 秋季为净水汽收入; 2)无论是年还是不同季节平均, 近30 a来西边界水汽输入量、 北边界水汽输出量基本呈现增加趋势或弱的减少趋势, 东边界水汽输出量、 南边界水汽输入量基本呈现减少趋势; 总水汽输入、 输出量均呈现减少趋势; 年、 夏季、 秋季净收入量呈现减少趋势, 春季、 冬季净支出量呈现增加趋势; 3)西藏地区冬、 春、 秋季的水汽主要来自中纬度西风带水汽输送, 夏季水汽主要来自阿拉伯海、 孟加拉湾、 南海和西太平洋地区, 夏季南边界的水汽输送状况对西藏地区降水起着决定性作用.  相似文献   

Elemental sulfur in northern South China Sea sediments and its significance   总被引：2，自引：0，他引：2  

Qi Lin  JiaSheng Wang  ShaoYing Fu  HongFeng Lu  QingTao Bu  RongXiao Lin  Fei Sun 《中国科学:地球科学(英文版)》2015,58(12):2271-2278

Elemental sulfur(ES) is one of the intermediates in the inorganic sulfur cycle and thus plays a key role in the fractionation of stable sulfur isotopes in different reservoirs and the marine environment. In this study, solid ES is discovered in sediments near the Jiulong Methane Reef in the northern South China Sea by scanning electron microscopy and Raman spectroscopy. Combining the morphology and distribution of ES, pyrite concentrations, and sulfur isotopes, we conclude that:(1) solid ES coexists with pyrite microcrystals and sulfide(oxyhydr)oxides as well as clay minerals, and they are mainly distributed on the surface of mineral aggregates;(2) ES mainly occurs within and near the sulfate-methane transition zone(SMTZ) despite little morphological diversity;(3) ES formation might be related to hydrogen sulfide oxidation and is therefore linked with fluctuations in the SMTZ. Within the SMTZ, hydrogen sulfide is produced and pyrite precipitates because of enhanced anaerobic oxidation of methane coupled with dissimilatory sulfate reduction. This enhances the efficiency of the inorganic sulfur cycle and provides favorable conditions for ES formation. The discovery of solid ES in sediments near the Jiulong Methane Reef suggests an important relationship with SMTZ fluctuations that could have implications for the evolution of methane hydrate in the South China Sea.  相似文献   

基于裂步DSR的最小二乘偏移方法   总被引：1，自引：0，他引：1  

黄建平  薛志广  步长城  李振春  王常波  高国超  曹晓莉  李国磊 《吉林大学学报(地球科学版)》2014,44(1):369

为适应复杂构造和岩性油气藏勘探开发对地震处理精度的需求,一种源于反演思想的最小二乘偏移算法应运而生。基于最小二乘偏移基本理论,推导了互为共轭的正传播和反传播算子,实现了基于裂步DSR的最小二乘偏移算法。在算法优化的基础上,将算法分别应用于水平层状和Marmousi模型进行偏移试算,结果证实了LSM不仅适用于复杂地质构造成像,且经过多次迭代后的成像质量在局部区域要优于常规偏移方法,具体表现为：1）成像分辨率有一定提高;2）中深层能量得到有效补偿。  相似文献   

Cyclic performance and simplified pushover analyses of precast segmental concrete bridge columns with circular section     

Zhanyu Bu  Jian Guo  Rongyue Zheng  Jianwei Song  George C. Lee 《地震工程与工程振动(英文版)》2016,15(2):297-312

In recent years, precast segmental concrete bridge columns became prevalent because of the benefits of accelerated construction, low environmental impact, high quality and low life cycle costs. The lack of a detailed configuration and appropriate design procedure to ensure a comparable performance with monolithic construction has impeded this structural system from being widely used in areas of high seismicity. In this study, precast segmental bridge column cyclic loading tests were conducted to investigate the performance of unbonded post-tensioned segmental bridge columns. One monolithic and two precast segmental columns were tested. The precast segmental column exhibited minor damage and small residual displacement after the maximum 7% cyclic drift; energy dissipation (ED) can be enhanced byadding ED bars. The experimental results were modeled by a simplified pushover method (SPOM), as well as a fiber model (FIBM) finite element method. Forty-five cases of columns with different aspect ratios, axial load ratios and ED bar ratios were analyzed with the SPOM and FIBM, respectively. Using these parametric results, a simplified design method was suggested by regressive analysis. Satisfactory correlation was found between the experimental results and the simplified design method for precast segmental columns with different design parameters.  相似文献   

西藏地区GPS水汽资料与降水量之间的对比分析   总被引：1，自引：0，他引：1  

罗布  杨秀海  央金 《高原山地气象研究》2010,30(1):54-57

利用2008年7月份西藏地区地基GPS遥感大气水汽总量的观测资料,研究了大气水汽总量与日平均温度、相对湿度和降水量的关系。研究结果表明:1海拔高度对站点上空水汽总量的影响比较明显,一般情况下海拔越高水汽总量越低;其次高原上某地的降水转化率高低与该地所处的长期天气背景有关2.水汽总量值与实际降水量的大小之间并不是一种简单的正比关系,水汽梯度值和水汽源源不断地输送对降水量的大小有重要影响。3.日平均温度和GPS大气可降水量跟相对湿度之间呈反相关;降水往往出现在高温高湿后面,这种现象可以用湿旋转效应解释;最低温度跟GPS大气可降水量之间有良好的正相关。   相似文献   

中国古代军事地理研究     

王树连  卜毅博 《测绘科学与工程》2007,27(2):25-29

军事地理是军事谋划的基本要素。中国古代纷繁的战争实践促进了军事地理研究的不断深入。《孙子兵法》中有关军事地形的系统论述是先秦军事地理研究的丰硕成果。南宋开始出现军事地理专著。明清时期，边患日重，有关边防、海防地区的军事地理研究之风盛行，成果颇多。兵要地志、军用地图是军事地理研究的基本成果。实地考察与考证地理典籍是军事地理研究的基本方法。中国古代军事地理研究中对战略要地、古代战场与战例、御敌方略的记述与研判，对今天的国防筹划仍然具有借鉴意义。  相似文献   

Preparation and Certification of Biogeochemical Reference Materials     

Changyi Shi  Tiexin Gu  Wei Bu  Weidong Yan  Mei Liu  Mingcai Yan 《Geostandards and Geoanalytical Research》2008,32(3):337-345

The Institute of Geophysical and Geochemical Exploration in China recently prepared ten biogeochemical certified reference samples GSB1‐10 (CRMs). The samples are primary agricultural products such as rice, wheat, corn, soybean, cabbage, spinach, tea, powder, chicken and apple. Lyophilisation technology and a high‐alumina ball mill were used to process the samples. Fourteen laboratories and hundreds analysts in China participated in the certification analysis. Over ten reliable analytical methods, predominately ICP‐MS, ICP‐AES and INAA, were used for analysing the samples for fifty‐nine elements. A total of 22477 determinations led to 5136 average data sets. Certified values of fifty‐four elements were assigned.  相似文献   

杭州城市多级通风廊道体系构建初探     

俞布  贺晓冬  危良华  陈亮  周雯 《气象科学》2018,38(5):625-636

随着小城镇建设及城市总体规划修编的实施,基于城市通风廊道构建的生态环境效应成为当前城市生态规划研究的热点。以杭州为例,研究构建了集合城市气候观测、多尺度数值模拟、城市形态控制为一体的城市多级通风廊道系统,综合考虑能够表达或影响城市通风环境的多源评价指标,如分区风玫瑰、近地面风流场、城市风功能区及风流通潜力等。结论表明:杭州城市主导风空间差异明显,可划分为15个截然不同的风玫瑰分区。利用区域边界层模式(RBLM)耦合多层城市冠层模型提取多种地面风流场信息,并结合主导风观测综合划定杭州城市一级通风廊道。结合建筑覆盖率、迎风面系数和地表粗糙度综合评价城市风流通潜力,并将其作为杭州城市二、三级风道划定的辅助依据。同时,利用RNGκ-ε湍流模型验证风道对局部通风环境改善的有效性。最终,基于多源信息的空间叠置分析,综合构建了由6条一级风道、11条二级风道和12条三级城市绿廊构成的杭州城市多级通风廊道体系,为其他城市开展通风廊道研究提供了通用的技术方法,从而科学有效的服务于城市生态规划及管理。  相似文献   

Machine learning-based methods for sea surface rainfall detection from CYGNSS delay-doppler maps     

Bu  Jinwei  Yu  Kegen  Ni  Jun  Yan  Qingyun  Han  Shuai  Wang  Jin  Wang  Changyang 《GPS Solutions》2022,26(4):1-13

GPS Solutions - Accurate secular trend estimates and their uncertainties of GNSS coordinate time series is imperative for its geophysical applications. However, trend estimates would be...  相似文献