Space-time soil wetness variations monitoring by a multi-temporal microwave satellite records analysis     

T. Lacava  E.V. Di Leo  V. Tramutoli 《Physics and Chemistry of the Earth》2006,31(18):1274-1283

In the last few years, remote sensing observations have become a useful tool for providing hydrological information, including the quantification of the main physical characteristics of the catchment, such as topography and land use, and of its variables, like soil moisture or snow cover. Moreover, satellite data have also been largely used in the framework of hydro-meteorological risk mitigation.Recently, an innovative Soil Wetness Variation Index (SWVI) has been proposed, using data acquired by the microwave radiometer AMSU (Advanced Microwave Sounding Unit) which flies aboard NOAA (National Oceanic and Atmospheric Administration) satellites.SWVI is based on a general approach for multi-temporal satellite data analysis (RAT - Robust AVHRR Techniques). This approach exploits the analysis of long-term multi-temporal satellite records in order to obtain a former characterization of the measured signal, in term of expected value and natural variability, providing a further identification of signal anomalies by an automatic, unsupervised change-detection step. Such an approach has already demonstrated, in several studies carried out on extreme flooding events which occurred in Europe in the past few years, its capability in reducing spurious effects generated by natural/observational noise. In this paper, the proposed approach is applied to the analysis of the flooding event which occurred in Europe (primarily in NW Spain) in June 2000. Results obtained, in terms of reliability as well as efficiency in space-time monitoring of soil wetness variation, are presented. Future prospects, in terms of exportability of the methodology on the new dedicated satellite missions, like ESA-SMOS and NASA-HYDROS, are also discussed.  相似文献   

水文资料在水土保持中的应用研究     

胡续礼  杨树江  吴迪  潘剑君 《水文》2006,26(5):45-47

本文简要分析了我国水文资料的基本特点及其在水土保持中的应用情况,并结合水文资料在水土保持中的研究实例,探讨了加强水文资料在水土保持中应用范围与价值,在新一轮的站网调整建设中应与水土保持监测站网建设结合起来,避免重复建设,加强水文站网功能,发挥现有水文站网作用。  相似文献   

Urban texture analysis with image processing techniques: winds and dispersion   总被引：1，自引：0，他引：1  

C. Ratti  S. Di Sabatino  R. Britter 《Theoretical and Applied Climatology》2006,84(1-3):77-90

Summary The focus is the analysis of urban Digital Elevation Models (DEMs) with image processing techniques. A brief review of existing methods to derive sky view factors, building energy consumption and space syntax shows how well established parameters that relate to airflow and dispersion (such as the height-to-width of urban canyons and the aerodynamic roughness length) can be calculated. Other measures of urban directionality and periodicity, inspired by traditional image processing, are also introduced, such as the Radon, Hough and Fourier transforms and the variance plot. Analyses of three case study sites in London, Toulouse and Berlin are compared, showing considerable variation in the chosen parameters. Results suggest that the DEM format is an extremely versatile tool to investigate the urban intermediate scale, allowing analyses that would be very difficult or impossible to carry out using traditional vectorial models.  相似文献   

Impact of increased vertical resolution on simulation of tropical climate   总被引：1，自引：0，他引：1  

P. M. Ruti  D. Di Rocco  S. Gualdi 《Theoretical and Applied Climatology》2006,85(1-2):61-80

Summary The aim of this study is to describe the behaviour of tropical dynamics in the ECHAM4 model when increased vertical resolution around the tropopause and in the planetary boundary layer is used. In this work we perform experiments with the ECHAM4 model using T30 horizontal resolution and 19 and 42 vertical levels. The impact of the increased vertical resolution on the simulation of tropical clouds and precipitation has been investigated. Therefore, the dynamic fields related to tropical convection have been analyzed. The results suggest a beneficial effect of the increased number of vertical levels on the convective scheme performance and on the related dynamic fields over the Tropics. The improvement of the rainfall climatologies in the 42-level model has been explained via the impact of vertical resolution on the cloud structure. In the cloud spectrum of the L42 simulation, a third peak appears around 600 hPa, revealing that when using higher vertical resolution the convective parametrization starts to represent cumulus congestus clouds.  相似文献   

An EPR and SQUID magnetometry study of bornite     

M. Borgheresi  F. Di Benedetto  A. Caneschi  G. Pratesi  M. Romanelli  L. Sorace 《Physics and Chemistry of Minerals》2007,34(9):609-619

A magnetic and spectroscopic characterisation has been performed on a natural bornite sample from the Natural History Museum of the University of Florence. The combination of magnetic measurements and continuous-wave electron paramagnetic resonance (cw-EPR) spectroscopy at different temperatures and frequencies provided information about the distribution and valence states of Cu and Fe in bornite. The studied sample was found to obey the Curie–Weiss law with a transition from a paramagnetic to an antiferromagnetic phase at 64 K; its possible attribution to a disordered spin glass phase was ruled out by ac susceptibility measurements. Q- and X-band cw-EPR measurements confirmed the presence of Fe(III) as fundamental valence state in bornite: the single EPR line registered in the temperature range from 300 to 65 K can be assigned, in fact, to the Fe(III) single ions. Some Cu(II) signals were revealed in the low temperature EPR spectra and attributed to an early stage of the surface alteration. The width of the Fe(III) EPR spectrum, which hinders any characteristic spectral structure, can be ascribed to the exchange interaction. The pure antiferromagnetic character of the magnetic transition confirms the ordering between Fe and Cu in the bornite structure, at least at low temperature (≤70 K). Moreover, the relatively high Nèel temperature suggests the accepted model of Collins et al.’s (Can J Phys 59:535–539, 1981) to conveniently explain the overall magnetic properties in the range 298–4 K. Despite the increasing of the susceptibility in the paramagnetic range, in fact, the integrated EPR line area decreases by lowering the temperature, thus suggesting a progressive rising of the antiferromagnetic interactions among next-nearest-neighbouring paramagnetic centres.  相似文献   

城市垃圾填埋场粘土基防渗浆材的实验研究   总被引：4，自引：0，他引：4  

靖向党  于波  马戈  谢俊革  彭第 《水文地质工程地质》2007,34(5):94-97,101

文章研制了一种低渗透系数并对污染物有一定吸附阻滞作用的浆材,即膨润土-粉煤灰-水泥(BFS)浆材,用于垃圾填埋场以防治渗沥液渗漏污染周围地下水和土壤。通过正交试验优选出了以膨润土为主的配方:膨润土22%~25%、粉煤灰20%~23%、水泥15%~18%、纯碱1.2%~1.4%、稀释剂TMH加量0.3%~0.45%。该浆材结实率大于99.6%,固结体28d渗透系数小于0.8×10-7cm/s,无侧限抗压强度小于2.0MPa,渗透系数比一般水泥粘土浆材降低约2个数量级。通过采自长春某垃圾填埋场的渗沥液进行固结体的渗透试验,该浆材的固结体对CODCr、氨氮和磷的吸附阻滞率均达到了82%以上。文章的创新点在于浆材配方的选材不但考虑了降低固结体渗透系数,使其符合规范要求,而且考虑了材料成分对渗沥液中污染物的吸附阻滞作用,同时降低了固结体的抗压强度和脆性,使其有一定的塑性和韧性,以适应填埋场的地基变形。  相似文献   

典型振动信号时-频分析方法研究     

徐国栋  周锡元  郭明珠  董娣 《世界地震工程》2007,23(2):26-36

首先对比较简单的单分量信号和多分量信号进行时-频分析,对比了不同时-频分析方法(STFT、WD、Hilbert时-频谱分析、连续小波分析)的分析精度。结果表明对单分量信号和可以分解为若干单分量信号叠加的多分量信号,Hilbert时-频谱分析精度最好,WD和STFT次之,连续小波变换的精度最差;由于Hilbert时-频谱分析和WD方法要求信号为单分量信号或可以分解为若干单分量的信号,故其不适用于复杂信号的时-频分析;对多分量信号,STFT时-频谱较连续小波时-频谱精度高些。需要指出的是,当使用STFT方法时,取不同的窗参数,STFT的时-频分析精度相差很大,必须使用合适的窗参数,以取得较好的分析效果。此外还对El Centro波的两水平分量和人工合成的地震动进行了时-频分析,虽然STFT的时间分辨率和频率分辨率存在矛盾,但它对信号的适应性最强,对复杂信号的时-频分析精度一般可以满足需要,而连续小波变换进行信号的时-频分析时,时-频分辨精度最差,且对于大于30Hz的频率分量,随频率的增加,时-频分析的效果和精度迅速变差,说明小波变换并不适合于做时-频分析,尤其对于高频信号,用连续小波变换得到的时-频谱图看起来很粗糙,而且很难准确解释。进一步对比了真实地震动和人工地震动的时-频分布,认为用胡聿贤教授合成人工地震动的方法合成的地震动在时-频域上的分布和真实地震动相似。  相似文献   

Magmatic History of Somma-Vesuvius on the Basis of New Geochemical and Isotopic Data from a Deep Borehole (Camaldoli della Torre)   总被引：3，自引：0，他引：3  

Di Renzo  V.; Di Vito  M. A.; Arienzo  I.; Carandente  A.; Civetta  L.; D'antonio  M.; Giordano  F.; Orsi  G.; Tonarini  S. 《Journal of Petrology》2007,48(4):753-784

A continuous-coring borehole recently drilled at Camaldoli dellaTorre on the southern slopes of Somma–Vesuvius providesconstraints on the volcanic and magmatic history of the Vesuvianvolcanic area since c. 126 ka BP. The cored sequence includesvolcanic units, defined on stratigraphical, sedimentological,petrological and geochemical grounds, emitted from both localand distal vents. Some of these units are of known age, suchas one Phlegraean pre-Campanian Ignimbrite, Campanian Ignimbrite(39 ka), Neapolitan Yellow Tuff (14· 9 ka) and VesuvianPlinian deposits, which helps to constrain the relative ageof the other units. The main rock types encountered are shoshonite,phonotephrite, latite, trachyte and phonolite. The sequenceincludes, from the base upwards: a thick succession of pyroclasticunits emplaced between 126 and 39 ka, most of them attributedto eruptions that occurred in the Phlegraean area; the CampanianIgnimbrite; the products of a local tuff cone formed between39 ka and the deposition of the products of the earliest activityof the Mt. Somma volcano; the products of the Somma–Vesuviusvolcano, which include from the base upwards a thick sequenceof lavas, pyroclastic rocks and the products of a local spattercone dated between 3· 7 ka and AD 79. The data obtainedfrom the study of the borehole show that, before the CampanianIgnimbrite eruption, low-energy explosive volcanism took placein the Vesuvian area, whereas mostly high-energy explosive eruptionscharacterized the Campi Flegrei activity. In the Vesuvian area,Campanian Ignimbrite deposition was followed by the eruptionof a local tuff cone and a long repose time, which predatedthe formation of the Mt. Somma edifice. Since 18· 3 ka(Pomici di Base eruption) the activity of Somma–Vesuviusbecame mostly explosive with rare lava effusions. The shallowestcored deposits belong to the Camaldoli della Torre cone, formedbetween the Pomici di Avellino and Pomici di Pompei eruptions(3· 7 ka–AD 79). New geochemical and Sr–Nd–Pb–B-isotopicdata on samples from the drilled core, together with those availablefrom the literature, allow us to further distinguish the volcanicrocks as a function of both their provenance (i.e. Phlegraeanor Vesuvian areas) and age, and to identify different magmaticprocesses acting through time in the Vesuvian mantle source(s)and during magma ascent towards the surface. Isotopically distinctmagmas, rising from a mantle source variably contaminated byslab-derived components, stagnated at mid-crustal depths (8–10km below sea level) where magmas differentiated and were probablycontaminated. Contamination occurred either with Hercynian continentalcrust, mostly during the oldest stages of Vesuvian activity(from 39 to 16 ka), or with Mesozoic limestone, mostly duringrecent Vesuvian activity. Energy constrained assimilation andfractional crystallization (EC-AFC) modelling results show thatcontamination with Hercynian crust probably occurred duringdifferentiation from shoshonite to latite. Contamination withlimestone, which is not well constrained with the availabledata, might have occurred only during the transition from shoshoniteto tephrite. From the ‘deep’ reservoir, magmas rosetowards a series of shallow reservoirs, in which they differentiatedfurther, mixed, and fed volcanic activity. KEY WORDS: Somma–Vesuvius; crustal contamination; source heterogeneity; radiogenic and stable isotopes; magmatic system  相似文献   

QuikSCAT洋面风资料及其在热带气旋分析中的应用   总被引：1，自引：0，他引：1  

方翔  咸迪  李小龙  王新 《气象》2007,33(3):33-39

QuikSCAT洋面风场资料可以提供海面上10米的风场信息，为热带气旋的进一步监测与分析提供帮助。通过对QuikSCAT洋面风轨道资料再处理和精度检验，国家卫星气象中心生成了更高分辨率的格点风场数据。通过洋面风资料对近年编号热带气旋的辅助分析实验，分析总结了洋面风资料在热带气旋定位、定强、发展趋势以及大风分析中的一些应用方法。结果表明：尽管存在一定误差，QuikSCAT洋面风场资料可以有效校正海上热带气旋特别是弱热带气旋的定位和定强偏差，反映热带气旋大风区的分布和低层环境流场，为进一步推断热带气旋的发展和移动趋势提供帮助。  相似文献   

大兴安岭南段晚中生代侵入岩时空分布及主脊与东坡岩体特征对比     

王迪  赵国春  苏尚国  李宏星 《现代地质》2020,34(3):466-482

通过岩相学、地球化学、锆石U-Pb年代学对位于大兴安岭主脊上的马勒根坝岩体、朝阳沟岩体和大兴安岭东坡区域的野猪沟岩体、布敦化岩体的4个不同花岗岩岩体的岩石类型、主量和微量元素特征、年代学及构造背景进行对比分析,讨论了研究区在晚侏罗世—早白垩世的岩浆活动及地质背景。LA-ICP-MS锆石U-Pb年龄显示:主脊朝阳沟岩体和东坡布敦化岩体年龄分别为(154±1) Ma和(154.1±1.6) Ma,属于晚侏罗世岩体,主脊马勒根坝岩体和东坡野猪沟岩体年龄分别为(144.62±0.74) Ma和(140.2±2.7) Ma,属于早白垩世岩体。岩相学和地球化学特征显示:主脊岩体为高钾钙碱性-准铝质-过铝质花岗岩岩体,东坡岩体为钙碱性-高钾钙碱性-准铝质-弱过铝质TTG型岩体;主脊比东坡岩体更加亏损Ba、Nb、Sr、P、Ti、Eu元素,为高分异I型花岗岩,东坡岩体为正常的I型花岗岩。结合区域地质资料分析,认为在晚侏罗世—早白垩世伊泽奈崎板块NNW向俯冲和蒙古—鄂霍次克洋闭合共同作用于大兴安岭南段地区,在大兴安岭主脊形成断裂带,导致幔源岩浆上涌底侵下地壳而形成沿断裂带分布的花岗岩体;主脊处于碰撞向伸展环境过渡的时期,东坡区域此时应处于俯冲时期。  相似文献