利用Terra和Aqua卫星地表温度探索汶川地震同震热响应

如何从卫星热红外遥感影像中提取出可靠的、能够验证的、与构造活动有关的热信息,是利用热红外信息研究构造现今活动亟待完善的问题之一.从信息提取的角度看,地震前后所对应的物理变化最为强烈,同震热响应可能是利用热信息探索现今构造活动潜在的突破点.本文以MODIS/Terra和MODIS/Aqua两颗卫星的地表温度为基础,探索汶川地震同震热响应.首先,去除了由地形等静态因素和太阳年周期组成的稳定背景;其次,去除大气环流的影响,获得由本地因素产生的原地温度场.最后,在原地温度场中,发现了汶川地震的同震温度响应.经过检验,上述温度响应的空间展布形态与发震断层的活动方式产生的力学效应吻合.从应力变化与温度响应的关系看,本文相当于借助热信息获得了汶川地震同震拉张或卸载区的空间展布情况.     

Quantifying the impact of urban area expansion on groundwater recharge and surface runoff

ABSTRACT

In this surface water modelling study, a new spatial evaluation for assessing the impact of urbanization was applied for the semi-arid watersheds intersecting with the Gaza coastal aquifer. The SWAT model was calibrated and validated in a semi-automated approach for streamflow in the main watersheds. The results show that the model could simulate water budget components adequately within the complex semi-arid watersheds. Linear relationships between the change in urban area and the corresponding change in surface runoff or percolation were concluded for the urbanized sub-basins. The urban-surface runoff index (USI) and the urban-percolation index (UPI) were developed to represent a micro-level evaluation of different urban change scenarios in the sub-basins. The global urban-surface runoff index (GUSI) and the global urban-percolation index (GUPI) were derived as macro-level factors reflecting the influence on the overall Gaza coastal aquifer due to urban area expansion.

Editor D. Koutsoyiannis Associate editor E. Rozos     

Temporal variability in hydrological response within a small catchment with badland areas,central Pyrenees

Abstract

The lower Araguás catchment, central Pyrenees, is characterized by extensive badlands (25% of the total catchment), whereas the upper catchment is covered by dense plantation forest. The catchment (45 ha) has been monitored since October 2005 with the aim of studying its hydrological response. The 44 floods recorded over this period were analysed to identify the factors that control the rainfall—runoff relationship. The first relevant feature of the catchment was its responsiveness. The catchment reacted to all rainfall events, but the irregular nature of the hydrological response was the most characteristic feature of the response. No single variable could explain the response of the Araguás catchment. It was found that stormflow coefficients mainly depend on the combination of rainfall volume and antecedent baseflow. A significant correlation was observed between maximum rainfall intensity and peak flow values. The shapes of the different hydrographs are very similar, regardless of the peak flow magnitude; they show a short time lag, relatively narrow peak flow, and steep recession limb. This indicates a large contribution by overland flow, resulting mainly from the generation of infiltration excess runoff in badland areas.     

On natural and laboratory generated dose response curves for quartz of different grain sizes from Romanian loess

One of the most important foundations of luminescence dating is the assumption that the growth of the luminescence signal in nature can be reproduced under laboratory conditions by performing irradiations with a calibrated beta or gamma source. When optically stimulated luminescence (OSL) of quartz with a dominant fast component is measured using the single aliquot regenerative dose (SAR) protocol, laboratory dose response curves that display continuing growth at high doses are increasingly reported in literature. In this study we investigate fine (4–11 μm) and coarse (63–90 μm) quartz extracted from 25 samples taken from L1, S1 and L2 units from the loess-palaeosol section at Costineşti in Romania. Our results indicate that the growth of the OSL signal in nature does not correspond to the laboratory generated laboratory dose response curve. The growth of the signal in nature is consistent with a single saturating exponential function, with the signal of coarse grains starting to saturate at 100–200 Gy, and for fine grains at 200–300 Gy, respectively. Laboratory dose response curves continue to grow for high doses (>300 Gy) for both quartz fractions. The differences observed between the natural and the laboratory dose response for the two quartz fractions are believed to be a cause for the different chronologies previously reported using the two grain sizes of quartz on Romanian loess. In addition, we have applied the single aliquot regeneration and added dose (SARA) procedure to both fine and coarse grains from the youngest sample. Our findings question the reliability of obtaining high equivalent doses for quartz samples displaying laboratory dose response curves obtained by the SAR protocol for which a single saturating exponential model does not describe the data.     

Autumn NDVI contributes more and more to vegetation improvement in the growing season across the Tibetan Plateau

ABSTRACT

Detecting changes in vegetation, distinguishing the persistence of changes, and seeking their causes during multiple periods are important to gaining a deeper understanding of vegetation dynamics. Using the Global Inventory Modeling and Mapping Studies Normalized Difference Vegetation Index (NDVI) version NDVI_3g dataset in the Tibetan Plateau, the trends in the seasonal components of NDVI and their linkage with climatic factors were analyzed over 14 asymptotic periods of 18–31 years since 1982. Dynamic trends in vegetation experienced an obvious increase at regional scale, but the increases of vegetation activity mostly tended to stall or slow down as the studied time period was extended. At pixel scale, areas with significant browning significantly expanded over 14 periods for all seasons, but for significant greening significantly increased only in autumn. The changes of vegetation activity in spring were the most drastic among three seasons. Increased increments of NDVI in summer, spring, and autumn took turns being the main reason for the enhanced vegetation activity in the growing season in the nested 14 periods. Vegetation activity was mainly regulated by a thermal factor, and the dominant climatic drivers of vegetation growth varied across different seasons and regions. We speculate that the increase of NDVI will continue but the increments will decline in all seasons except autumn.     

Intermediate disturbance and patterns of species richness

Abstract

The intermediate disturbance hypothesis (IDH) predicts highest species diversity in environments experiencing intermediate intensity disturbance, after an intermediate timespan. Because many landscapes comprise mosaics with complex disturbance histories, the theory implies that each patch in those mosaics should have a distinct level of diversity reflecting the magnitude of disturbance and the time since it occurred. We model changing patterns of species richness across a landscape experiencing varied scenarios of simulated disturbance in order to predict first the variation of richness through time in individual patches, based on their disturbance histories, and then the changing patterns of richness across the landscape through time, representing the cumulative impact of changing richness within the individual patches. Model outputs show that individual landscape patches have highly variable species richness through time, with the trajectory reflecting the timing, intensity and sequence of disturbances. When the results are mapped across the landscape, the resulting temporal and spatial complexity reveals a distribution of biodiversity that is strikingly contingent on the details of disturbance history. These results illustrate the danger of generalization (in either data interpretation or management decisions), as IDH actually imposes a highly variable pattern of diversity.     

Introducing sensor spectral response into the classification process

Many sensors have their bands overlapped and therefore do not set a normal space. If a spectral distance is measured, as in first-order statistical classifiers, the direct consequence is that the result will not be the most accurate. Image classification processes are independent of the spectral response function of the sensor, so this overlap is usually ignored during image processing. This paper presents a methodology that introduces the spectral response function of sensors into the classification process to increase its accuracy. This process takes place in two steps: first, incident energy values of the sensors are reconstructed; second, the energy of the bands is set in an orthonormal space using a matrix singular value decomposition. Sensors with and without overlapping spectral bands were simulated to evaluate the reconstruction of energy values. The whole process was implemented on three types of images with medium, high and very high spatial resolution obtained with the sensors ASTER, IKONOS and DMC camera, respectively. These images were classified by ISODATA and minimum distance algorithms. The ISODATA classifier showed well-defined features in the processed images, while the results were less clear in the original images. At the same time, the minimum distance classifier showed that overall accuracy of the processed images increased as the maximum tolerance distance decreased compared to the original images.     

巷道地质编录三维空间数字化及投影变换算法

本文以提高矿山地、测、采计算机管理与辅助设计质量和效率为基本目标,根据矿山地测数据处理的一般流程,从巷道地质编录图件出发,建立基于井下测量数据的巷道地质编录三维空间数字化及投影变换算法;在此基础上,研制了一套符合矿山生产实际的地质编录智能分析系统,实现了巷道地质编录图件的数字化及自动成图。     

Monitoring disasters with a constellation of satellites – type examples from the International Charter ‘Space and Major Disasters’

In the case of a major disaster, information derived from satellite observation is not only highly useful, it may at times be indispensable because of the damage caused by the disaster to ground infrastructure. The International Charter ‘Space and Major Disasters’ (‘the Charter’) has been one of the primary sources of satellite data for the past 11 years to cover events like floods, fires, tsunamis, ocean storms, earthquakes, volcanic eruptions and oil spills. With the growing membership of the Charter, an increasingly large number of sensors are now available, which can be planned with the required temporal frequency and spectral range to cover a disaster event. Some of the type Charter activation cases are reported in this article to demonstrate the innovative use of multi-satellite imagery for disaster response.     

福建宁化下伊锡矿地质特征及成因探讨

宁化下伊锡矿产于晚白垩世花岗斑岩内外接触带附近,受北东向、北北东向断裂控制。目前已发现锡矿体6个,各矿体呈脉状、长透镜状产出,锡石贮存于硅化、黄铁矿化、云英岩化蚀变岩中,属中-高温热液脉状型矿床。