基于遥感技术的煤炭勘查方法研究

随着煤炭资源的大量开发利用,其保有储量逐年降低,易于发现的露头矿、浅部矿日趋减少,尤其是经济发达的东部地区煤炭资源更为紧缺。当前找煤对象主要为地下隐伏矿床及盲矿体,找煤难度越来越大,因此探索如何发挥现代遥感及地理信息系统技术优势开展遥感找煤具有重要意义。本文从遥感找煤的理论基础出发,通过对以往中国遥感找煤实践的总结,系统阐述了遥感找煤的方法及存在的问题,提出了下一步遥感找煤的技术发展思路:即采用新型的多波段、多极化、多角度、多时相、多分辨率遥感数据,利用GIS工具对各种地理属性、地面属性、地球物理勘探、地球化学勘探、地质钻探成果、遥感影像数据进行空间综合分析,探索煤田地质背景和成矿规律,提取深层次煤田信息。     

青藏高原高寒草地净初级生产力(NPP)时空分异(英文)

Based on the GIMMS AVHRR NDVI data(8 km spatial resolution) for 1982–2000, the SPOT VEGETATION NDVI data(1 km spatial resolution) for 1998–2009, and observational plant biomass data, the CASA model was used to model changes in alpine grassland net primary production(NPP) on the Tibetan Plateau(TP). This study will help to evaluate the health conditions of the alpine grassland ecosystem, and is of great importance to the promotion of sustainable development of plateau pasture and to the understanding of the function of the national ecological security shelter on the TP. The spatio-temporal characteristics of NPP change were investigated using spatial statistical analysis, separately on the basis of physico-geographical factors(natural zone, altitude, latitude and longitude), river basin, and county-level administrative area. Data processing was carried out using an ENVI 4.8 platform, while an ArcGIS 9.3 and ANUSPLIN platform was used to conduct the spatial analysis and mapping. The primary results are as follows:(1) The NPP of alpine grassland on the TP gradually decreases from the southeast to the northwest, which corresponds to gradients in precipitation and temperature. From 1982 to 2009, the average annual total NPP in the TP alpine grassland was 177.2×1012gC yr-1(yr represents year), while the average annual NPP was 120.8 gC m-2yr-1.(2) The annual NPP in alpine grassland on the TP fluctuates from year to year but shows an overall positive trend ranging from 114.7 gC m-2yr-1in 1982 to 129.9 gC m-2yr-1in 2009, with an overall increase of 13.3%; 32.56% of the total alpine grassland on the TP showed a significant increase in NPP, while only 5.55% showed a significant decrease over this 28-year period.(3) Spatio-temporal characteristics are an important control on annual NPP in alpine grassland: a) NPP increased in most of the natural zones on the TP, only showing a slight decrease in the Ngari montane desert-steppe and desert zone. The positive trend in NPP in the high-cold shrub-meadow zone, high-cold meadow steppe zone and high-cold steppe zone is more significant than that of the high-cold desert zone; b) with increasing altitude, the percentage area with a positive trend in annual NPP follows a trend of"increasing-stable-decreasing", while the percentage area with a negative trend in annual NPP follows a trend of "decreasing-stable-increasing", with increasing altitude; c) the variation in annual NPP with latitude and longitude co-varies with the vegetation distribution; d) the variation in annual NPP within the major river basins has a generally positive trend, of which the growth in NPP in the Yellow River Basin is most significant. Results show that, based on changes in NPP trends, vegetation coverage and phonological phenomenon with time, NPP has been declining in certain places successively, while the overall health of the alpine grassland on the TP is improving.     

西藏自治区拉萨河流域湿地脆弱性评价与成因分析

构建了基于"敏感性—人为脆弱性"的脆弱性评价指标体系,运用ArcGIS的空间叠加分析和脆弱性评价模型,开展拉萨河流域湿地脆弱性评价,并运用障碍度计算方法,分析了影响脆弱性的主要因素。研究结果表明,拉萨河流域湿地脆弱性范围为0.115 3~0.742 7,可分为轻度脆弱、中度脆弱和重度脆弱3个等级,其中,中度脆弱面积最大,占湿地总面积的59.59%,集中分布在河谷区和高山盆地区,主要类型为藏北嵩草(Kobresia lit?tledalei)沼泽化草甸、杂类草湿草甸和河流;其次是轻度脆弱湿地,占湿地总面积的38.25%,主要分布于河源区的嘉黎县;重度脆弱湿地仅占2.16%,分布在河源区的那曲县和河谷区的桑日县。轻度和重度脆弱湿地的类型都以藏北嵩草沼泽化草甸、河流和湖泊为主。影响湿地脆弱性的主要因素有9个,其重要性从高到低依次为年降水量、污染源、牲畜密度、人均牧业产值、植被盖度、人均耕地面积、污水排放量、猪的密度和高程,其中,年降水量、放牧和植被盖度是普遍存在的最重要的影响因素。降低湿地脆弱性的关键在于保障水源供给、控制污染和限制过度放牧。     

郴州优势矿种可持续发展之路

郴州优势矿种开发利用水平较高,矿业经济特别是优势矿种开发在全市工业经济中地位明显。但是在矿业开发利用中也存在着诸多困难,如不及时解决,将制约郴州市矿业经济乃至整个经济社会的可持续发展。     

多层介质中利用sPn与Pn到时差确定震源深度的研究

为利用sPn与Pn波的走时差测定震源深度,进一步提高地震震源深度的测定精度,推导多层介质下sPn与Pn波的走时差与震源深度的关系,发现走时差与震中距无关,只与震源深度及区域地壳速度模型有关。震源在同一层中,走时差曲线的斜率不变,而当震源位于不同层中时,sPn-Pn走时差曲线的斜率不同,并呈分段直线的走时差曲线形态。地壳速度结构纵向越不均匀,多层和单层介质下利用sPn-Pn走时差计算的震源深度误差就越大,走时曲线的各分段直线斜率相差越大;探讨地壳中sPn与Pn波传播路径相同但波速不同的单层地壳速度模型,发现单层介质下波速越大,测定的震源深度越大;对于同一地区相同的地壳分层结构,测得的震源深度随着泊松比的增大而减小。基于前人给出的中国五个典型块体多层平均地壳模型,给出sPn-Pn走时差与震源深度计算公式速查表。     

主喜马拉雅逆冲带的震间与同震重力场变化

为对中国自主重力/重力梯度卫星在陆地地震研究中提供理论依据,本文选取了主喜马拉雅逆冲断层(MHT),模拟了断层在同震和震间滑移产生的大地水准面、重力变化和重力梯度变化。首先给出了大地测量数据反演断层滑动分布的马尔可夫链—蒙特卡洛方法,实际反演中,Markov链的总长度由4×10~7个模型组成,燃烧阶段和采样阶段的长度均为2×10~7个模型,重采样的间隔为1000,初始温度设为100,终止温度为0.1。再次给出了基于反向滑移模型估计震间断层的耦合度。利用GPS和InSAR数据,对2×10~4个重采样的模型取平均后,反演得到MHT的同震滑移和震间耦合分布,结果表明:2015年M_w 7.8尼泊尔地震同震破裂并未达到地表,最大滑移量约为6 m,地震矩为1.02×10~(21) Nm,相当于M_w 7.9,与其他手段得到的结果一致;MHT的震间耦合模型表明MHT在中上地壳以上部分在震间均处于闭锁状态,积累的能量相当于每年一个M 7地震。基于以上反演的断层滑移/滑移亏损模型,模拟了MHT同震和震间的重力场变化。变形地表面的同震重力变化呈南北两极分布,范围为–261—125μgal,理论上能够被陆地重力测量所检测到。长波长的震间空间重力/重力梯度变化信号难以被当前重力卫星观测到;对冰川等大尺度质量效应进行改正后的同震重力/重力梯度变化有望被提高测量精度的下一代重力卫星检测出。本研究成果对中国未来发射的自主重力卫星数据在地震发生和孕育方面的应用研究将提供有益的启示。     

登陆台风强度变化过程预报的影响试验研究

探索了基于WRF模式的集合卡尔曼滤波同化方法（WRF-EnKF,简称EnKF）在近海有可能达到更强台风连续循环同化中国大陆高时空分辨率多普勒天气雷达径向风观测资料的效果,同时检验台风Vicente（2012）的三维结构演变及其动力学特征。通过短期集合预报得到跟随当前流场变化着的背景误差协方差的台风涡旋和动力学结构。研究发现,EnKF同化预报系统能有效地同化高时空分辨率雷达径向速度观测资料,显著改善初始场中台风Vicente的中小尺度内核结构,同时提高对台风Vicente的路径和强度及其相伴随的短期强降水预报。在台风最强时刻同化雷达径向风观测能快速（1~2 h）得到真实的暖核台风结构,同时进一步提高台风路径和强度的预报。另外,EnKF同化雷达径向风观测资料还能有效提高短期降水预报,1 h和3 h累积降水的分布、降水中心以及降水随时间演变都能得到显著改善,这与改善台风路径、结构和强度有密切关系。因此,对中国东南沿海有可能达到较强的台风进行同化雷达径向风观测资料可改善登陆台风的预报水平,这为利用我国地基多普勒天气雷达观测资料改善模式的初始场从而提高台风预报提供一定的指示作用。      

一次华南海岸带台前飑线的结构特征与环境条件的观测研究

2007年8月8日,热带风暴“帕布”移动到华南近海,在珠江三角洲至湛江以西地区出现了一次强飑线天气过程。根据多普勒天气雷达、风廓线雷达和气象探空等观测数据,分析此次台前飑线的生成、演变过程、组织结构以及环境大气条件特征,并对热带风暴“帕布”与台前飑线环境大气的关系进行初步探讨。观测和分析结果显示:(1)此次台前飑线系统是由孤立的对流单体逐渐发展而成,陆风环流的抬升作用有可能对飑线的初始生成起到重要作用;(2)台前飑线移动路径和强度受海岸附近环境条件的影响;在海岸靠近陆地一侧的强度远比内陆和海洋上强,移动路径倾向于沿海岸线平行;(3)台前飑线在发展和成熟阶段,其水平结构具有典型的尾流层云降水特征;其冷池强度和垂直结构具有典型的热带飑线特征;(4)台前飑线发生在具有深厚水汽层、对流凝结高度较低的环境大气条件中,与热带飑线的环境大气条件类似;而对流不稳定能量和低层垂直风切变强度与中纬度飑线接近;(5)热带气旋外围大风一方面使低层风切变加强,同时为环境大气提供了高层的水汽。在下沉环流区内太阳辐射使陆地明显增温,一方面使位势不稳定能量增大,另一方面也使海陆温差增大、海风环流加强,导致低层风切变进一步加强,低层水汽输送增大。下沉逆温抑制了低层弱对流的发生,为强对流的发展积累了对流不稳定能量。      

OBSERVATIONAL STUDY ON THE PRE-TROPICAL CYCLONE SQUALL LINE OF 8 AUGUST 2007 OVER THE COAST OF SOUTH CHINA

A squall line in front of the tropical cyclone Pabuk occurred in the west of the Pearl River Delta to Zhanjiang on August 8th, 2007 when the storm approached South China. The development, structure and environmental conditions for this squall line were investigated in this study, with particular attention paid to the possible connection of this squall line with Pabuk. The observational data employed in this study are from soundings, Doppler weather radars and wind profile radars. The following six major conclusions are drawn by our observational analyses. (1) This squall line developed gradually from individual convective cells, and land breeze may be responsible for the onset of the squall line. (2) The path and intensity of the squall line were modulated by the environmental conditions. The squall line propagated along the coastline, and it was stronger on the landing side of the coastline compared with the surrounding in-land regions and oceanic regions. (3) The typical characteristics of tropical squall lines were seen in this squall line, including the cold-pool intensity, vertical structure and the wake flow stratiform precipitation at its developing and mature phases. (4) The environmental conditions of this squall line resemble those of tropical squall lines in terms of deep moist air and low convection condensation level. They also resemble mid-latitude squall lines in terms of the convective instable energy and vertical wind shear in the lower troposphere. (5) Two roles were played by the strong wind around Pabuk. On the one hand, it made the atmosphere more unstable via suppressed shallow convection and increased solar radiation. On the other hand, it enhanced the land-sea thermal contrast and therefore strengthened the sea breeze and the resultant water vapor transport. The sinking temperature inversion prevented the occurrence of low-layer weak convection and accumulated convection instability energy for the development of the strong convection.     

多时刻台风Bogus资料同化对台风"天鹅"的影响

基于GRAPES(Global/Regional Assimilation and Predition System)三维变分同化系统,设计在6小时内分别应用三小时一次和逐小时的台风定位和定强信息对台风进行多次BDA(Bogus Data Assimilation)同化,在多次BDA中只同化近似程度高的涡旋风分量而近似...