近20年美国龙卷探测研究进展——对我国龙卷风研究的启示     

李峰  李柏  唐晓文  张林  李瑞义 《气象》2020,46(2):245-256

对美国近20年龙卷探测雷达技术和观测研究进行了文献调研,文献表明美国龙卷探测雷达研制目标主要为实现快速扫描、获取高时空分辨率和高精度的资料,目的基本达到,雷达体扫时间达到10秒级更新,在雷达近距离范围内分辨率可达到10 m,甚至更低,这些都使得采集龙卷精细化结构和细致连续演变过程成为可能。美国雷达发展采用多种技术体制和扫描策略并进,双极化、相控阵、大气成像等技术方面不断改进与应用,效果良好。基于先进雷达,美国进行了大量的龙卷观测试验,取得了丰富成果,对龙卷的结构和演变规律刻画得越来越精细和准确。许多成果已经转化为概念模型,形成重要的龙卷监测与预报指标、预警信号,并在业务中实施,提高了龙卷预警能力。高频次高精度的龙卷雷达探测资料的数值模式应用也明显缩短了资料同化周期,同时提高了对龙卷等对流尺度系统的模拟能力。参照美国的成功经验,我国应汲取其技术成果,尽快选定雷达发展技术体制,加快业务雷达技术升级和高性能龙卷探测雷达研制,组织龙卷科学观测试验,采集龙卷精细数据,开展科学研究,探索中国的龙卷结构和活动规律,为构建龙卷监测预警业务提供基础的科学支撑。  相似文献   

应用改进模式从FY2H卫星数据估算OLR     

张婉春  吴晓  白文广  曹广真  孙凌  张鹏 《气象与环境科学》2020,43(3):1-8

射出长波辐射(OLR)是大气科学研究领域的关键参量,并在辐射相互作用、气候变化和灾害监测等方面发挥重要作用。2018年6月5日静止气象卫星FY2H成功发射,OLR产品是FY2H的业务产品之一。在原有FY2系列OLR反演算法基础上,参考国际上NOAA/HIRS OLR反演算法,结合FY2H/VISSR 3个红外通道设置,建立适合FY2H的OLR反演算法。利用该算法处理FY2H/VISSR的L1级观测数据,生成实时及日、旬、月平均的OLR产品。FY2H的OLR产品与CERES均匀性下垫面的瞬时视场OLR产品对比,RMSE=3.38 W/m~2,R=0.99,Bias=0.77 W/m~2;与CDR日平均OLR产品对比,RMSE为5～7 W/m~2,R为0.97～0.98,Bias为-2.2～1.9 W/m~2;与CDR旬平均OLR产品对比,RMSE为3～5 W/m~2,R=0.99,Bias为-1.1～0.4 W/m~2;与CDR月平均OLR产品对比,RMSE为2～4 W/m~2,R=0.99,Bias为-1.1～0.4 W/m~2。这表明FY2H OLR改进算法达到了较高的精度,可满足卫星设计和应用研究精度需求。  相似文献   

利用雨雪分寸重建福州前汛期雨季起始日期的方法研究   总被引：3，自引：0，他引：3  

葛全胜  丁玲玲  郑景云  郝志新 《地球科学进展》2011,26(11):1200-1207

阐述清代福州雨雪分寸记录的特点;并利用福州1961-2010年器测降水记录,分析福州3～7月降水特征,提出辨识福州前汛期雨季开始日期的指标。在此基础上,根据清代福州雨雪分寸记录的内容和形式,分类构建利用雨雪分寸辨识福州前汛期雨季起始日期的方法;依据日降雨分寸、降雨日期和强度、时段的降水日期（或时段起止日期）及降水日（次...  相似文献   

珠江源区生态地质环境安全体系构建研究     

白海霞  王嘉学  普荣 《地质灾害与环境保护》2011,22(1):76-79

珠江源区森林生态系统严重退化,湿地遭到破坏,导致石漠化和水土流失严重,水旱灾害频繁。生态地质环境问题制约了该区经济和社会的发展,影响了整个珠江流域。应在加强全民教育的基础上,坚持科技引导,推进制度建设,以退耕还林为切入点,调整产业结构,改善农村能源结构,建立生态地质环境监测网,以此构建一个珠江源区生态地质环境安全体系。  相似文献   

Seasonal variations in sulfur isotopic composition of dissolved SO<Subscript>4</Subscript><Superscript>2−</Superscript> in the Aha Lake,Guiyang and their implications     

Liuting Song  Congqiang Liu  Zhongliang Wang  Yanguo Teng  Jinsheng Wang  Lili Liang  Li Bai 《中国地球化学学报》2011,30(4):444-452

The Aha Lake is a seasonal anoxic water system in the southwest of Guiyang City, Guizhou Province, China. Seasonal variations in SO42- concentrations and their isotopic compositions in lake water as well as in the tributaries were investigated in this study. The results showed that sulfate concentrations in river water range from 0.94 to 6.52 mmol/L and their δ34S values range from -14.9‰ and 0.9‰, while lake water has sulfate concentrations ranging from 1.91 to 2.79 mmol/L, and δ34S values from -9.8‰ to -5.9‰. It is suggested that coal mining drainage is the major source of SO42- in the Aha Lake. Rainfall, sewage discharge, sulfide oxidation and gypsum dissolution have made only limited contributions. Different depth-dependent distributions of dissolved SO42- and δ34S were de-veloped for both DB and LJK in summer and winter. Due to water overturn, δ34S values display homogenous vertical distributions in winter and spring. While in summer and autumn, significant positive shifts of δ34S were clearly ob-served in epilimnion and bottom strata as a result of water stratification. High δ34S values in epilimnion may result from the retention of rainwater during water stratification. Dissimilatory sulfate reduction by bacteria was thought to be responsible for the increase of δ34S value in hypolimnion.  相似文献   

大兴安岭—小兴安岭地区中生代岩浆-构造-钼成矿地质事件序列的初步框架   总被引：9，自引：1，他引：8       下载免费PDF全文

刘翠  邓晋福  许立权  张昱  赵寒冬  孔维琼  李宁  罗照华  白立兵  赵国春  苏尚国 《地学前缘》2011,18(3):166-178

兴蒙造山带是中国一条重要的成矿带.通过近几年的调查研究,以及大量人力、物力和资金投入,在该区发现了一批大、中型钼矿床,但是钼矿产出的区域地质背景还不是很清楚.对该区中生代A型花岗岩类、地质图分析以及钼矿的研究得知:(1)研究区印支期和燕山期是两个独立的造山旋回,印支期造山在220～200Ma左右结束,以区域上发育一套碱...  相似文献   

Crustal structure of the Paleozoic Kunlun orogeny from an active-source seismic profile between Moba and Guide in East Tibet, China   总被引：13，自引：0，他引：13  

Zhongjie Zhang  Simon Klemperer  Zhiming Bai  Yun Chen  Jiwen Teng 《Gondwana Research》2011,19(4):994-1007

We herein present a new seismic refraction/wide-angle reflection profile that crosses the Songpan–Ganzi terrane, the Animaqing suture zone and the eastern Kunlun mountains (comprised of the South Kunlun and Middle Kunlun blocks separated by the Middle Kunlun fault). The profile is 380 km long and extends from Moba to Guide in eastern Tibet. The crustal thickness is about 62 km under the Songpan–Ganzi terrane, 62–64 km under the South Kunlun, and 60 km under the Middle Kunlun block. The Songpan–Ganzi flysch seems to be present up to a depth of 15 km south of the Animaqing suture zone, and up to a depth of 10 km in the Middle Kunlun block, with thicknesses elsewhere that depend on assumptions about the likely lithologies. The profile exhibits clear lateral variations both in the upper and lower crust, which are indicative of different crustal blocks juxtaposed by the Kunlun fault system. Whether or not the Songpan–Ganzi flysch was originally deposited on oceanic crust, at the longitude of our profile (100°E) it is now underlain by continental crust, and the presence of continental crust beneath the Songpan–Ganzi terrane and of a continental arc under the South Kunlun block suggest Paleozoic continent–continent arc collision in the eastern Kunlun Mountains. Comparison of crustal velocity columns from all wide-angle seismic profiles across the eastern Kunlun mountains indicates a remarkable west-to-east change in the Moho topography across the Kunlun fault system (15–20 km Moho step at 95°E, but only 2–5 km along our profile at 100°E). Lower-crustal thickness of the Kunlun terranes is rather uniform, about 35 km, from 80°–95°E, which suggests that similar thrust-thickening processes have played a role where the Qaidam Basin abuts the Kunlun fault, but thins to 20–25 km at 100°E, east of the Qaidam Basin. The increased crustal thickness from 93° to 98°E compared to that at 100°E may be due to the differences in the thickness of the crust of the two plates before their collision, and/or largely achieved by thickening of the lower crust, perhaps indicating a crustal flow mechanism operating more strongly in the western region.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987111000569   总被引：3，自引：0，他引：3  

Xuejing Xie  Yinxiu Lu  Wensheng Yao  Jinfeng Bai 《地学前缘(英文版)》2011,2(3):303-311

A study of deep penetrating geochemistry-the surface exploration techniques for finding concealed mineral deposits-was carried out over the Spence porphyry copper deposit in Chile by Australian,Canadian and Chinese laboratories using selective weak leach methods and is briefly reviewed here.Erratic and weak copper anomalies were obtained above the Spence deposit,which is concealed below a thick piedmont gravel cover.In the literature,such patterns are common in most of the weak selective leach studies carried out over known buried deposits.During exploration in unknown area,such weak leach techniques lead to some success and many dry holes.In this paper,stronger selective leaching methods are developed for oxides and sulfides,which may be the stable end products transformed and accumulated by a mobile precursor phase carried upward through the overburden by gas or water through long spans of geological time.The data obtained by the methods developed in this paper produced more significant and consistent anomalous data than previous efforts.Consequently,the leach approaches described here may increase the effectiveness of deep penetrating geochemistry in exploration for concealed ore deposits.  相似文献   

GIS-based rare events logistic regression for landslide-susceptibility mapping of Lianyungang,China   总被引：6，自引：2，他引：4  

Shibiao Bai  Guonian Lü  Jian Wang  Pinggen Zhou  Liang Ding 《Environmental Earth Sciences》2011,62(1):139-149

Landslides have had a huge effect on human life, the environment and local economic development, and therefore they need to be well understood. In this study, we presented an approach for the analysis and modeling of landslide data using rare events logistic regression and applied the approach to an area in Lianyungang, China. Digital orthophotomaps, digital elevation models of the region, geological maps and different GIS layers including settlement, road net and rivers were collected and applied in the analysis. Landslides were identified by monoscopic manual interpretation and validated during the field investigation. To validate the quality of mapping, the data from the study area were divided into a training set and validation set. The result map showed that 4.26% of the study area was identified as having very high susceptibility to landslides, whereas the others were classified as having very low susceptibility (47.2%), low susceptibility (22.21%), medium susceptibility (14.39%) and high susceptibility (11.93%). The quality of the landslide-susceptibility map produced in this paper was validated, and it can be used for planning protective and mitigation measures. The landslide-susceptibility map is a fundamental part of the Lianyungang city landslide risk assessment.  相似文献   

喀斯特地区土地利用变化研究——以贵州省为例   总被引：2，自引：0，他引：2  

李正  王军  白中科  郭义强  邱杰 《地域研究与开发》2011,30(2)

分析贵州省1996-2008年土地利用变化情况,揭示土地利用变化差异状况及驱动因子.基于贵州省1996-2008年土地利用变更调查数据,利用土地利用结构信息熵和均衡度、土地利用类型年均变化幅度、年均变化率与相对变化率5个指数,分析土地利用变化情况.结果表明:(1)13年间,贵州省土地利用变化主要以耕地和林地的变化为主,土地利用结构变化表现出林地、园地、居民点及工矿用地、水域、交通用地明显增加,耕地、牧草地和未利用地减少.(2)贵州省土地利用结构信息熵和均衡度呈现"上升--下降--上升"的过程,总体呈增长趋势.(3)8类土地利用类型中,园地的区域变化差异较大,牧草地区域变化差异较小;贵州省西部地区的土地利用类型变化较东部地区显著.贵州省土地利用结构变化的主要驱动力是生态退耕政策的实施和经济社会的发展.  相似文献