Gravity topographic corrections computed from a square grid of height points

Summary Computation of terrain corrections from a map with a square grid of mean height points

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Application of the BME approach to soil texture mapping

In order to derive accurate space/time maps of soil properties, soil scientists need tools that combine the usually scarce hard data sets with the more easily accessible soft data sets. In the field of modern geostatistics, the Bayesian maximum entropy (BME) approach provides new and powerful means for incorporating various forms of physical knowledge (including hard and soft data, soil classification charts, land cover data from satellite pictures, and digital elevation models) into the space/time mapping process. BME produces the complete probability distribution at each estimation point, thus allowing the calculation of elaborate statistics (even when the distribution is not Gaussian). It also offers a more rigorous and systematic method than kriging for integrating uncertain information into space/time mapping. In this work, BME is used to estimate the three textural fractions involved in a texture map. The first case study focuses on the estimation of the clay fraction, whereas the second one considers the three textural fractions (sand, silt and clay) simultaneously. The BME maps obtained are informative (important soil characteristics are identified, natural variations are well reproduced, etc.). Furthermore, in both case studies, the estimates obtained by BME were more accurate than the simple kriging (SK) estimates, thus offering a better picture of soil reality. In the multivariate case, classification error rate analysis in terms of BME performs considerably better than in terms of kriging. Analysis in terms of BME can offer valuable information to be used in sampling design, in optimizing the hard to soft data ratio, etc.     

Application of singularity index mapping technique to gravity/magnetic data analysis in southeastern Yunnan mineral district,China

The fractal/multifractal based singularity index mapping technique efficient in characterizing singular physical or chemical properties is applied for the analysis of gravity and aeromagnetic data in southeastern Yunnan mineral district, China. As follow-up after the introduction of singularity theory to geochemical and geological mapping scenarios, this study extends its application to delineate geophysical potential fields. Based on low gravity and low magnetic properties of granitic intrusions in the study area, singularity mapping technique is used as a high-pass filter to emphasize the geophysical anomalies caused by granitic intrusions in support of future mineral exploration. Comparing with the traditionally used band-pass filtering method, it is shown that the new technique provides an improved and simplified approach in geophysical data analysis with the advantage of scale independence.     

The INSAR technique: its principle and applications to mapping the deformation field of earthquakes

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蒸散发时间尺度转换在日降雨径流过程模拟中的应用

针对目前研究蒸散发时间尺度转换方面的不足,构建了月蒸散发时间尺度转换模型,对淮河史灌河流域黄泥庄小流域1982-1987年月蒸散发能力进行逐栅格解集,并与改进后的AFFDEF分布式水文模型耦合进行日径流过程模拟.结果显示:解集产生的日蒸散发能力随时间在平均值附近波动变化,能很好地体现日蒸发量的时间变异特点;模拟的日径流过程的精度较高,平均Nash效率系数在80%以上,径流深相对误差都在10%以内,平均泊松相关系数为0.912,模拟流量过程曲线与实测值匹配的较好;经与采用平均解集模式的模拟结果对比发现,耦合蒸散发时间尺度转换模型后的模拟精度与前者大体相当,部分指标略优于前者.蒸散发时间尺度转换模型解集产生的日蒸散发量序列能够反映日蒸发量的时间变异特点,更能满足区域日降雨径流过程模拟的需要,可为解决资料匮乏区域水文模拟提供一个新途径.     

Makkink's equation for evapotranspiration applied to unstressed maize

The crop factor method is applied to unstressed maize, in which grass is the reference crop, and the evapotranspiration of the latter is determined with the simplified equation of Makkink as proposed by De Bruin (1987). Using the crop factor published by Feddes (1987), a good agreement is found with measurements collected during the growing season of 1985 at the Sinderhoeve (51° 59′ N, 5° 45′ E) near Renkum in The Netherlands. It appears that Makkink's method yields slightly better results than the Penman–Monteith equation using surface resistances fitted to the data set itself. © 1998 John Wiley & Sons, Ltd.     

Intercomparison of evapotranspiration estimates

Abstract

Five methods of computing reference evapotranspiration from a reference crop (Penman, radiation, Blaney-Criddle, Hargreaves and pan evaporation) have been studied for their applicability under different climatic conditions. The Penman method was taken as the standard and the other four methods were compared against this method. Good correlation was obtained between the values estimated by the four methods and the Penman method although differences in magnitude were found. Regression equations were developed to correct those differences in magnitude. The method suitable for the estimation of reference evapotranspiration for each climatic condition is also suggested.     

平面网格位场数据的空间域非线性曲率滤波方法

剖面测线位场数据的空间域非线性曲率涯波方法能够较好地分离提取剖面到线位场的趋势和剩余异常，本文首次将该方法推广应用到平面网格位场数据情况，为平面网格位场的趋势和剩余异常的分离提取提供了一种新的实用方法。在新疆某地区的实例计算表明，本文提出的平面网格位场数据的空间域非线性曲率滤波方法的应用效果好、计算速度快。     

Elevation-dependent changes in reference evapotranspiration due to climate change

The Food and Agriculture Organizations' (FAO) Penman–Monteith reference evapotranspiration (ET₀) is a crucial index in the research of water and energy balance. Temporal and spatial variations in ET₀ from 1981–2017 were investigated in the Hengduan Mountains, China_. The results showed a change point around the year 2000 in ET₀ series. ET₀ decreased and increased significantly by +3.200 mm/year (p < 0.01) from 1981–2000 and by +4.109 mm/year (p < 0.01) from 2001–2017, respectively. The contribution analysis shows that the positive significant contribution of air temperature (TA) was offset by negative effects of decreases in downward shortwave radiation (R_s) and wind speed (WS) and an increase in actual vapour pressure (e_a), causing the decrease in ET₀ from 1981 to 2000. WS was the largest contributing factor for the decrease in ET₀ from 1981 to 2000 during spring, winter and annually, while R_s and e_a were the largest negative contributors in summer and autumn, respectively. An increase in TA was responsible for the increase in ET₀ in all seasons except winter and the annual scale in 2001–2017. The sensitivity analysis shows that ET₀ was most sensitive to TA, and WS was the least sensitive variable. The trends of ET₀ increased with elevation; we denote this as the elevation-dependence of ET₀ changes. The elevation-dependence was also noted for the trends of WS and e_a, with higher elevations showing larger changes in WS and lower changes in e_a. Besides, the sensitivities of TA, R_s and e_a decreased with elevation, while that of WS increased slightly with elevation. A comprehensive investigation into the trends of climatic drivers and their sensitivities revealed complex trends of the contributions of climatic variables on ET₀ with elevation, with no uniform trend existed in seasons. The results will contribute to our understanding of the response of ET₀ to climate change in a mountainous area, and provide a guideline for the water resources management under climate change.     

Sensitivity of the Penman-Monteith reference evapotranspiration to sunshine duration in the Upper Mekong River Basin

Sensitivity analysis is important in understanding the relationship between sunshine duration (SD) and reference evapotranspiration (ET_ref). This study was developed in the Lancang-Mekong River Basin using a non-dimensional relative sensitivity coefficient (S_N) relating ET_ref to SD. The S_N for January and July for each station were calculated. The results indicate that (a) the SD and S_N change in similar ways, where January and July are selected as two representative time slices; (b) the spatial distributions of the long-term averaged S_N for January and July are the reverse of each other; (c) the most abrupt changes in climate occur in the 1980s and the middle region is sensitive to climate change; and (d) periodicities of 2–4 and 14–16 years are detected in the basin generally. The significant increase of inter-decadal filter variance indicates changes in the long-term memory of the local climate system.

EDITOR Z.W. Kundzewicz

ASSOCIATE EDITOR not assigned     

Application of pyrolysis gas chromatography technique to evaluation of coal-generated hydrocarbon

Based on kerogen-generated hydrocarbon model, a new method to calculate hydrocarbon yields for coals and coaly samples was put forward by means of pyrolysis technique. At the same time, the empirical criteria suggested by Powell were revised. The threshold value was preliminarily defined as HC yields >30 mg HC per gram TOC for effective gas source rocks and >60 mg HC per gram TOC for effective oil source rocks. Additionally, it was also confirmed that the relative compositions of the three ranges of C1-C5 total hydrocarbons, C6-C14n-alkanes plusn-alkenes and C15⁺ n-alkanes plusn-alkenes from pyrolysates can be effectively used to distinguish the coal-generated hydrocarbon types.     

Application of microcosm experiments for quantifying lateral flow and evapotranspiration on recovering bog ecotypes

The importance of characterizing the ecohydrological interactions in natural, damaged/drained, and restored bogs is underscored by the importance of peatlands to global climate change and the growing need for peatland restoration. An understudied aspect of peatland ecohydrology is how shallow lateral flow impacts local hydrological conditions and water balance, which are critical for peatland restoration success. A novel method is presented using microcosms installed in the field to understand the dynamics of shallow lateral flow. Analysis of the difference in water table fluctuation inside and outside the microcosm experimental areas allowed the water balance to be constrained and the calculation of lateral flow and evapotranspiration. As an initial demonstration of this method, a series of four microcosm experiments were set up in locations with differing ecological quality and land management histories, on a raised bog complex in the midlands of Ireland. The timing and magnitude of the lateral flow differed considerably between locations with differing ecological conditions, indicating that shallow lateral flow is an important determining factor in the ecohydrological trajectory of a recovering bog system. For locations where Sphagnum spp. moss layer was present, a slow continuous net lateral input of water from the upstream catchment area supported the water table during drought periods, which was not observed in locations lacking Sphagnum. Consistent with other studies, evapotranspiration was greater in locations with a Spaghnum moss layer than in locations with a surface of peat soil.     

我国高分辨率遥感技术在地震研究中的应用

本文概述了我国高分辨率遥感技术在地震监测预报、灾害预防和应急救援防震减灾三大业务体系中的应用现状,重点介绍了“高分遥感地震监测与应急应用示范”项目的进展.该项目针对防震减灾业务体系发展的应用需求,在整合地震行业现有技术和资源的基础上,突破了高分辨率对地观测系统卫星遥感数据在地震构造调查、地震监测和地震应急救援等方面应用的关键技术,制定行业应用规范,建设高分遥感地震业务应用示范系统,并开展应用示范.该项目的成功实施,使得我国高分辨率遥感技术在地震中的应用从以往分散的科学研究提升到一个业务化应用的状态,从而能更加有效地服务于防震减灾工作.      

三维AVO解释技术在洪泽地区岩性油藏勘探中的应用

洪泽地区由于沉积的特点，储层横向变化快，油藏受构造、岩性、油源多因素控制。在对该区三维AVO属性体解释中，利用多元回归方法求取了横波曲线，分岩性和含油气性统计了纵、横波、泊松比参数分布规律，建立了本区的含油砂岩的正演模型，从而降低了AVO解释的多解性。通过井-震结合对四种AVO属性数据体进行了标定，并确定了各属性体应用范围，进而进行了储层和含油气检测。实践表明，该方法能有效地利用AVO属性数据体进行储层预测及油气检测，具有一定的推广价值。     

居里等温面深度的探测方法

地壳居里等温面的研究对确定深部磁体结构和了解深部热状态及结构有重要意义.本文对探测居里等温面深度的方法进行了科学地总结,分类和评估,并主要介绍了各种方法的基本原理.较直接的探测居里等温面的方法是根据大地热流值,地温\|深度关系或岩石矿物实验来确定,但是这种方法在实际中并不常用.最常用的方法是应用航磁和卫星磁数据.根据所研究的目标的不同,磁法又可以被分为两大类：单体磁异常法和组合磁异常法.这两大类下又可以有各种不同的应用技术,其中功率谱分析方法最为流行.虽然没有任何一种方法是完美的,针对组合磁异常的统计功率谱分析方法被认为是较成熟的一项技术,并得到了很多的应用及讨论.组合磁异常的功率谱分析方法的理论基础是Spector\|Grant 统计模型,这个统计模型很适用于对区域磁异常组合的分析.为了提高分辨率,无论单体磁异常法或组合磁异常法都需要考虑很大的一片研究区域,这样的结果会降低所获得的居里等温面的横向分辨率,由此所获得的居里等温面深度通常只是某一区域平均居里点深度的一级近似.一项比较特别的技术是Mayhew的最初为分析卫星磁数据而建立起来的等层模型方法.这一方法的基本原理是,根据一些校准点,将一等厚度层上所观测到的不同的磁场强度转换为等磁场强度的深度差异.这一技术与功率谱分析方法的一个重要差别在于它不需要对磁体顶部和底部所引起的功率谱进行区分,而这种区分是功率谱分析方法中所必需的.由于对居里等温面深度的探测是一种反演技术并包含了反演中的非唯一性和数学上的不稳定性,在各种方法的应用中应采取谨慎的态度.近年来,自相似和分形理论的应用为这一领域的研究提供了很多崭新的研究机会和科学思想.自相似和分形模型是对Spector\|Grant统计模型的完善和发展,因为自相似模型考虑了更真实的磁场强度差异的分形分布.另外,这一新理论也揭示了以前很多种方法中的局限性.     

远程通讯技术在地震电磁波监测系统中的应用

对远程地震电磁波监测通信系统的方案、系统的组成、硬件的配置、软件设计、工作原理、功能,以及技术性能进行了论述。该系统通过下位机（MCU）,经MODEM模块与上位机（PC机）通讯,工作人员通过上位机实现远程控制和数据传输。