基于CBERS-02B星数据的土地利用/覆被类型监测应用研究的应用研究

研究了基于CBERS-02B星数据的土地利用/覆被类型监测方法,综合评价了基于像素分类法和面向对象法的应用精度和效果。结果表明,基于像素分类法和面向对象分类法分类精度基本可满足土地宏观监测精度精度,在保证影像质量和训练样本质量情况下,分类精度可达到 80% 以上,研究成果可为土地利用宏观监测提供技术参考。     

Application of the 3D magnetotelluric inversion code in a geologically complex area

The WSINV3DMT code makes the implementation of 3D inversion of magnetotelluric data feasible using a single PC. Audio‐magnetotelluric data were collected along two profiles in a Cu‐Ni mining area in Xinjiang, China, where the apparent resistivity and phase curves, the phase tensors and the magnetic induction vectors indicate a complex 3D conductivity structure. 3D inversions were carried out to reveal the electrical structure of the area. The final 3D model is selected from the inversion results using different initial Lagrange values and steps. The relatively low root‐mean‐square (rms) misfit and model norm indicate a reliable electrical model. The final model includes four types of low resistivity areas, the first ones coincide with the known location of an orebody and further forward modelling indicates that they are not in full connectivity to form a low resistivity zone. The second ones are not controlled by magnetotelluric sites and embody little information of the observed data, they are considered as tedious structures. The third one is near to the regional Kangguer fault and should be treated carefully considering the effect of the fault. The last ones are isolated and existing at a limited level as the first ones, they should be paid more attention to.     

THE TEMPORAL AND SPATIAL VARIATION OF STABLE ISOTOPES IN PRECIPITATION ON THE TIBETAN PLATEAU AND ITS ADJACENT REGIONS*

The temporal and spatial variation on the stable isotopic compositions in precipitation and the relationship with temperature,precipitation and vapor sources are analyzed for the Tibetan Plateau and its adjacent regions.There is no temperature effect in the southern Tibetan Plateau and South Asia.Amount effect has been observed at a few sampling stations that account for about a half of the statistical stations.However,the seasonal variations on the stable isotopic compositions in precipitation at those stations are inconsistent with that of precipitation intensity.There is notable temperature effect in the middle and northern Tibetan Plateau and its adjacent Northwest China.It has been observed that the seasonal variations of the δ¹⁸O in precipitation are almost consistent with those of air temperature in these regions.Because vapor is directly originated from lowlatitude oceans,the relative heavy δ¹⁸O with small variation characterizes the rainfall in South Asia.A sharp depletion of the stable isotopic compositions in precipitation takes place from Kyangjin on the southern slop of the Himalayas to the Tanggula Mountains in the middle Plateau.The δ¹⁸O reaches minimum due to very strong rainout of the vapor from oceans as the vapor rises over the Himalayas.From the Tanggula Mountains to the northern Tibetan Plateau,the δ¹⁸O in precipitation increases with increasing latitude and the is otopic situation in the northern Plateau istransferred into Northwest China with little disruption.     

Ecohydrological change mechanism of a rainfed revegetation ecosystem at southeastern edge of Tengger desert,Northwest China

Study is made on a 45 km-long artificial ecosystem without irrigation in Tengger desert on the basis of long-term ecological monitoring and ecohydrological fundamentals. Changes in water allocation, utilization, cycle and balance patterns in more than 40-year evolution of the soil-plant system are analyzed. The formation of a drought horizon in shrub rhizosphere and its effect, ecohydrological function of the crust and its effect on the soil-plant system change are discussed. Driven by water self-regulation and water stress, the soil-plant system is going to develop towards the steppe desert to ensure more effective use and optimum collocation of water resource.     

计算机辅助区域地质调查野外工作系统研究进展

计算机辅助区域地质调查系统是近几年来在我国迅速发展的高新技术系统。其中野外工作系统是整个系统研究的瓶颈和关键之一,有针对性地综合探讨了国内外相关野外工作系统的发展现状和特点,并就其工作模式进行了对比研究,总结了系统研究开发的体系结构、途径和发展方向。国内外的实践证明,数字化填图系统的应用将显著提高传统区调工作的效率和精度,对于我国新一轮国土资源大调查和"数字国土"工程的建设有重要意义。     

Subseasonal Reversal of East Asian Surface Temperature Variability in Winter 2014/15

Although there has been a considerable amount of research conducted on the East Asian winter-mean climate, subseasonal surface air temperature(SAT) variability reversals in the early and late winter remain poorly understood. In this study,we focused on the recent winter of 2014/15, in which warmer anomalies dominated in January and February but colder conditions prevailed in December. Moreover, Arctic sea-ice cover(ASIC) in September–October 2014 was lower than normal,and warmer sea surface temperature(SST) anomalies occurred in the Ni ?no4 region in winter, together with a positive Pacific Decadal Oscillation(PDO|+) phase. Using observational data and CMIP5 historical simulations, we investigated the PDO|+ phase modulation upon the winter warm Ni ?no4 phase(autumn ASIC reduction) influence on the subseasonal SAT variability of East Asian winter. The results show that, under a PDO|+ phase modulation, warm Ni ?no4 SST anomalies are associated with a subseasonal delay of tropical surface heating and subsequent Hadley cell and Ferrel cell intensification in January–February, linking the tropical and midlatitude regions. Consistently, the East Asian jet stream(EAJS) is significantly decelerated in January–February and hence promotes the warm anomalies over East Asia. Under the PDO|+ phase,the decrease in ASIC is related to cold SST anomalies in the western North Pacific, which increase the meridional temperature gradient and generate an accelerated and westward-shifted EAJS in December. The westward extension of the EAJS is responsible for the eastward-propagating Rossby waves triggered by declining ASIC and thereby favors the connection between ASIC and cold conditions over East Asia.     

湖南湘中地区一次暴雨及大暴雨过程分析

利用NCEP的1°×1°再分析资料、FY2E卫星云图TBB资料、雷达资料、常规天气资料以及加密自动雨量站资料,对2010年5月13日湖南省湘中地区一次大暴雨天气过程的环流背景、物理量场、卫星雷达资料等进行了天气学诊断分析。结果表明:高空南支槽和中低层切变是这次大暴雨天气过程的主要影响系统,西南低空急流为大暴雨的产生提供了充沛的水汽条件;低层强辐合,高层强辐散的配置,使垂直上升运动得到了发展和加强,低层水汽迅速向上输送,同时引起热量、动量的垂直输送,为大暴雨的形成提供有利的动力和热力条件。     

四川宜宾地壳浅部三维S波速度结构及方位各向异性

利用四川宜宾及周边地区布设的30个临时台站连续44天的波形记录,采用背景噪声互相关方法提取了周期为1—15 s的瑞雷面波相速度频散曲线,然后使用基于面波射线路径追踪的瑞雷面波直接成像方法得到0—10 km深度范围内三维S波速度模型,最后利用该模型作为初始模型采用相同的反演框架得到该地区的方位各向异性结构.结果表明:浅层...     

对1989年1991年山西地区3次5级以上地震预报的回顾

1989、1991年，山西发生了大同－阳高6.1、忻州5.1和大同－阳高5.8级3次5级以上地震（不含余震），有对大同－阳高2次地震普提出明确的中期预报意见。山西省地震局在中期预报的基础上，对1991年1月29日忻州5.1级、3月26日大同－阳高5.8级地震分别做出了一定程度的短期或临震预报，本文对这3次地震的预报过程做了简要的回顾。     

运城震群序列特征

1986年11月至1987年1月在山西运城发一次较大震群活动。本文着重讨论了这次震群活动的序列特征和衰减特征