影响面波勘探精度的因素探讨   总被引：4，自引：0，他引：4  

胡家富  段永康 《地震研究》2000,23(3):333-338

分析了影响面波勘探精度的主要因素,针对计算面波相速度的精度问题,讨论了常用测量台间以相速度方法的优缺点及其适用范围,并提出通过测量台间格林函数进行相位校正,以得到两台之间的精解相位。以合成的高频理论地震图作为记录信号,并在理论地震图上叠加了２０％的随机噪声,利用这些方法分析理论信号,数字实验表明：在相干频率范围内,格林函数方法能够精确测量台间相速度,而互相关法和窄带通滤波互相关法所得结果较为离散。  相似文献   

浙江椒江山溪性强潮河口的若干特征   总被引：7，自引：0，他引：7  

祝永康 《地理研究》1986,5(1):21-31

本文从椒江河口的径流、潮流变化,泥沙运移和沉积结构以及河床演变和河口的发育过程探讨了山溪性强潮河口若干特征。  相似文献   

Active Tectonic Research for Seismic Safety Evaluation of Long-Line Engineering Sites in China     

Ran Yongkang 《中国地震研究》2005,19(3):317-326

INTRODUCTIONAlong-line engineering site refers to the one that is linearly distributed such as the oil or gaspipelines,water conveyance pipeline,railways and high-grade highways,etc.The Chinese Code forSeismic Safety Evaluation of Engineering Site,GB17741…  相似文献   

Middle Devonian Picrites of the Southern Margin of Altay Orogenic Belt and Implications for the Tectonic Setting and Petrogenesis   总被引：1，自引：0，他引：1  

ZHANG Zhaochong  YAN Shenghao  CHEN Bailin  Zhou Gang  He Yongkang  Chai Fengmei  He Lixin 《中国地质大学学报(英文版)》2005,16(2):95-103

INTRODUCTION Inrecentyears,greatprogressonthegeologic tec tonicevolutionandmineralresourcesofXinjianghas beenachieved.However,manyissuesarestilldebated, suchasancienttectonicpatternsandtheclosuretimeof theancientoceanicbasin(LiandXu,2004).Theseis sueshavelimitedourknowledgeoftheformationande volutionofAsiancontinents,aswellastheexploration anddevelopmentofmineralresources. Recently,theHilaketehalasuporphyrycopperde positwasdiscoveredinthestrataoftheMiddleDevoni anBeitashanFormatio…  相似文献   

用1.35厘米波长地面微波辐射计探测大气中水汽总量及分布   总被引：2，自引：0，他引：2  

魏重  薛永康  朱晓明 《大气科学》1984,8(4):418-426

用1.35厘米波长地面微波辐射计进行了全年四个季节的观测.采用蒙特卡洛法对资料进行了反演.七十多份资料的统计结果表明:水汽总量的相对误差为5.3％,低层水汽廓线(750毫巴以下)的相对误差在20％以下,对水汽总量及廓线随时间的演变与天气背景的关系亦作了初步分析.  相似文献   

青海南部高寒草地土壤冻融交替期水热特征分析   总被引：2，自引：0，他引：2  

韩炳宏  周秉荣  吴让  颜玉倩  牛得草  傅华 《气象科技》2018,46(2):361-368

为进一步了解高寒草地土壤冻融交替过程及其对水热因子的响应机制,通过2014年8月1日至2015年8月1日不同土层土壤温度和水分观测资料的对比分析,较为系统地探讨了青南高寒草地土壤冻融期不同深度土层土壤温度和水分的变化特征。结果表明,青南高寒草地土壤冻融阶段大体可分为初冻期、稳定冻结中期、稳定冻结后期和消融期4个时期;不同土层土壤温度随气温的变化呈周期性波动,且随着土层的加深变幅减小;不同冻融期表层和亚表层土壤温度和水分波动幅度较大,下层土壤对水热因子的敏感性较小;土壤完全冻结的天数达44~115d,日冻融交替过程主要发生在表层和亚表层土壤。土壤冻融交替增强了土壤的保水性,对该区草地植被提前返青和初级生产力的提高具有促进作用。  相似文献   

Validating a regional climate model’s downscaling ability for East Asian summer monsoonal interannual variability     

Tomonori Sato  Yongkang Xue 《Climate Dynamics》2013,41(9-10):2411-2426

Performance of a regional climate model (RCM), WRF, for downscaling East Asian summer season climate is investigated based on 11-summer integrations associated with different climate conditions with reanalysis data as the lateral boundary conditions. It is found that while the RCM is essentially unable to improve large-scale circulation patterns in the upper troposphere for most years, it is able to simulate better lower-level meridional moisture transport in the East Asian summer monsoon. For precipitation downscaling, the RCM produces more realistic magnitude of the interannual variation in most areas of East Asia than that in the reanalysis. Furthermore, the RCM significantly improves the spatial pattern of summer rainfall over dry inland areas and mountainous areas, such as Mongolia and the Tibetan Plateau. Meanwhile, it reduces the wet bias over southeast China. Over Mongolia, however, the performance of precipitation downscaling strongly depends on the year: the WRF is skillful for normal and wet years, but not for dry years, which suggests that land surface processes play an important role in downscaling ability. Over the dry area of North China, the WRF shows the worst performance. Additional sensitivity experiments testing land effects in downscaling suggest the initial soil moisture condition and representation of land surface processes with different schemes are sources of uncertainty for precipitation downscaling. Correction of initial soil moisture using the climatology dataset from GSWP-2 is a useful approach to robustly reducing wet bias in inland areas as well as to improve spatial distribution of precipitation. Despite the improvement on RCM downscaling, regional analyses reveal that accurate simulation of precipitation over East China, where the precipitation pattern is strongly influenced by the activity of the Meiyu/Baiu rainfall band, is difficult. Since the location of the rainfall band is closely associated with both lower-level meridional moisture transport and upper-level circulation structures, it is necessary to have realistic upper-air circulation patterns in the RCM as well as lower-level moisture transport in order to improve the circulation-associated convective rainfall band in East Asia.  相似文献   

1977－2020年额济纳胡杨林植被变化特征及其影响因子分析          下载免费PDF全文

汤永康  郭春燕  孙小龙  王佳  韩旭日  刘洋 《沙漠与绿洲气象(新疆气象)》2023,17(4):152-159

基于1977－2020年Landsat影像，采用监督分类和归一化植被指数（NDVI），并结合气象、水文数据，对近44年额济纳绿洲胡杨林面积时空动态、植被状况，以及对其有影响的主要环境因素进行综合分析。结果表明：（1）2020年研究区胡杨林面积为2.99万 hm2，较1977年，胡杨林面积增长了1.62倍，东河西岸三角洲恢复面积较大。研究期内，胡杨林经历了衰落期和恢复期，最小面积为1990年的1.03万 hm2。（2）2001年实施生态调水后，研究区NDVI值增速达0.027/10 a (p<0.01)，是研究时段NDVI值增速的2倍，调水前NDVI值增速的45倍。（3）虽然月NDVI值与月均温相关系数为0.463 (p<0.01),但年NDVI值与气候因素相关性并不明显，而与正义峡径流量显著正相关（相关系数为0.437，p<0.05），并且实施黑河调水与胡杨林景观生态功能改善的时间段同步。生态调水后，研究区NDVI值升高了0.011，裸地面积减少0.17万 hm2。  相似文献   

扬子地块东北缘中元古代的大地构造   总被引：3，自引：0，他引：3  

张永康  刘聪 《江苏地质》1996,20(2):65-71

扬子地块东北缘存在四条主要的中元古代变质带，自南向北依次为江南变质带，沿江变质带，云台－张八岭变质带和连云港－泗阳变质带。它们分别为中元古代的古弧后盆地，火山岛弧，裂谷及弧前盆地。扬子地块东北缘中元古代为活动大陆边缘构造体系，苏胶变质造山带应解体，其中一部分属扬子大陆边缘体系。  相似文献