2009-18年西北太平洋区域海洋再分析CORA1.0产品研制及检验          下载免费PDF全文

Guofang Chao  Xinrong Wu  Lianxin Zhang  Hongli Fu  Kexiu Liu  Guijun Han 《大气和海洋科学快报》2021,14(5):37-41

在51年(1958-2008)西北太平洋区域海洋再分析CORA1.0产品的基础上,改进了模式配置和同化方法,研制了2009-18年的CORA产品并对其进行以下检验:(1)温盐和海表高度异常均方根误差分布检验;(2)35°N处温度断面分布检验;(3)再分析流场和表漂浮标轨迹对比检验.结果显示,2009-18年的CORA产品可以再现海洋要素长时间序列,时空多尺度的变化特征,为研究特征海洋现象和过程提供背景信息.  相似文献   

Biomarkers and environmental risk assessment: guiding principles from the human health field     

Owen R  Galloway TS  Hagger JA  Jones MB  Depledge MH 《Marine pollution bulletin》2008,56(4):613-619

Although the potential use of biomarkers within environmental risk assessment (ERA) has long been recognised their routine use is less advanced compared with clinical human health risk assessment, where a number of familiar biomarkers (such as blood pressure and serum cholesterol) are in common usage. We have examined how biomarkers are incorporated into human health risk assessment and have identified several 'required elements'. These include identification of the (clinical) assessment endpoint at the outset, rational selection of the biomarker(s) (the measurement endpoint), biomarker 'validation' (e.g. QA/QC) and biomarker 'qualification' (evidence linking the measurement and assessment endpoints). We discuss these elements in detail and propose that their adoption will facilitate the routine use of biomarkers in environmental risk assessment. Furthermore, our analysis highlights the need for cooperation between those working with biomarkers within human and environmental risk assessment to exchange best practice between common disciplines for mutual advantage.  相似文献   

中国MODIS地表温度产品验证   总被引：2，自引：1，他引：2  

高懋芳  覃志豪 《国土资源遥感》2006,17(3):15-18

分析了MODIS地表温度产品的误差来源，重点研究利用高分辨率遥感影像数据ASTER同步反演的验证方法。以2003年8月1日太 湖地区为例，用ASTER数据的反演结果与同时相的MODIS地表温度产品进行比较，分别在太湖水面、无锡城区及城郊农田3个典型地表 状况下选取感兴趣区域做线性拟合，取得了较好的结果，拟合的R2值可达0.966 6。  相似文献   

Human impacts and eutrophication patterns during the past ~200 years at Lago Grande di Avigliana (N. Italy)     

Walter Finsinger  Christian Bigler  Urs Krähenbühl  André F. Lotter  Brigitta Ammann 《Journal of Paleolimnology》2006,36(1):55-67

A short sediment core from Lago Grande di Avigliana (Piedmont, Italy), the second most eutrophied lake in Italy, was analysed for pollen and diatoms to reconstruct land-use changes and to estimate baseline conditions for total phosphorus (TP) in the water column. Varve counts on sediment thin-sections and ²¹⁰Pb, ²²⁶Ra, and ¹³⁷Cs dating provided a reliable chronology for the past ~200 years. The main pollen-inferred land-use changes showed a sharp decrease of hemp retting around AD 1900, as well as a gradual change to less intensive agriculture and increasing abundance of exotic plants since AD ~1970. Diatom-inferred TP reconstructions indicated stable TP concentrations until AD ~1950, revealing baseline mesotrophic conditions (TP <25 μg l⁻¹). After AD ~1950, TP values increased distinctly and continuously, culminating in the late 1960s with concentrations of 150 μg l⁻¹. Subsequently, diatoms implied a linear decrease of TP, with an inferred value of 40 μg l⁻¹ in the surface sediment sample. Comparison with instrumental TP measurements from the water column since AD 1980 showed a rapid recovery and allowed a direct validation of the diatom TP inference. However, although the TP concentration has decreased considerably, baseline conditions have not yet been reached. When compared to the limnological effects of sewage discharges on inferred-TP concentration, our results indicated that agricultural land use played a minor role in the lake’s eutrophication.  相似文献   

Evaluating hazard results for Switzerland and how not to do it: A discussion of “Problems in the application of the SSHAC probability method for assessing earthquake hazards at Swiss nuclear power plants” by J-U Klügel     

R.M.W. Musson  G.R. Toro  J.J. Bommer  H. Bungum  F. Scherbaum  N.A. Abrahamson 《Engineering Geology》2005,82(1):43-55

The PEGASOS project was a major international seismic hazard study, one of the largest ever conducted anywhere in the world, to assess seismic hazard at four nuclear power plant sites in Switzerland. Before the report of this project has become publicly available, a paper attacking both methodology and results has appeared. Since the general scientific readership may have difficulty in assessing this attack in the absence of the report being attacked, we supply a response in the present paper. The bulk of the attack, besides some misconceived arguments about the role of uncertainties in seismic hazard analysis, is carried by some exercises that purport to be validation exercises. In practice, they are no such thing; they are merely independent sets of hazard calculations based on varying assumptions and procedures, often rather questionable, which come up with various different answers which have no particular significance.  相似文献   

The comparison index: A tool for assessing the accuracy of image segmentation     

《International Journal of Applied Earth Observation and Geoinformation》2007,9(3):311-321

Segmentation algorithms applied to remote sensing data provide valuable information about the size, distribution and context of landscape objects at a range of scales. However, there is a need for well-defined and robust validation tools to assessing the reliability of segmentation results. Such tools are required to assess whether image segments are based on ‘real’ objects, such as field boundaries, or on artefacts of the image segmentation algorithm. These tools can be used to improve the reliability of any land-use/land-cover classifications or landscape analyses that is based on the image segments.The validation algorithm developed in this paper aims to: (a) localize and quantify segmentation inaccuracies; and (b) allow the assessment of segmentation results on the whole. The first aim is achieved using object metrics that enable the quantification of topological and geometric object differences. The second aim is achieved by combining these object metrics into a ‘Comparison Index’, which allows a relative comparison of different segmentation results. The approach demonstrates how the Comparison Index CI can be used to guide trial-and-error techniques, enabling the identification of a segmentation scale H that is close to optimal. Once this scale has been identified a more detailed examination of the CI–H- diagrams can be used to identify precisely what H value and associated parameter settings will yield the most accurate image segmentation results.The procedure is applied to segmented Landsat scenes in an agricultural area in Saxony-Anhalt, Germany. The segmentations were generated using the ‘Fractal Net Evolution Approach’, which is implemented in the eCognition software.  相似文献   

Chironomids as quantitative indicators of mean July air temperature: validation by comparison with century-long meteorological records from northern Sweden   总被引：4，自引：0，他引：4  

Isabelle Larocque  Roland I. Hall 《Journal of Paleolimnology》2003,29(4):475-493

This study evaluates the potential of using chironomid assemblages to estimate past temperature changes by comparing chironomid-inferred temperatures to meteorological data for the last 87 years. This comparison is made using high-resolution (i.e., sub-decadally resolved) short cores of four lakes along a gradient of altitude (Lake Njulla, 999 m a.s.l., Lake 850, 850 m a.s.l., Lake Alanen Laanijavri, 365 m a.s.l. and Lake Vuoskkujavri, 348 m a.s.l.), vegetation (pine forest to alpine tundra vegetation) and temperature (mean July temperature of 12.4 to 8.1°C). Patterns of chironomid-inferred changes in mean July air temperature were highly comparable to changes in the meteorological data. Moreover, instrumental data were almost always within the specific errors of the quantitative estimates using chironomids. These results indicate that chironomids can be used as a powerful tool to reconstruct temperatures and that chironomids are sensitive enough to record temperature changes of low magnitude such as those recorded during the Holocene. Although this relationship between temperature and chironomid community is strong for the last 87 years, we cannot assume that other environmental factors such as organic matter, changes of lake water depth or oxygen availability were not more significant over longer temporal scales of the Holocene, or longer.  相似文献   

Assessment of the prediction error in a large-scale application of a dynamic soil acidification model     

J. Kros  J. P. Mol-Dijkstra  E. J. Pebesma 《Stochastic Environmental Research and Risk Assessment (SERRA)》2002,16(4):279-306

 The prediction error of a relatively simple soil acidification model (SMART2) was assessed before and after calibration, focussing on the Al and NO₃ concentrations on a block scale. Although SMART2 is especially developed for application on a national to European scale, it still runs at a point support. A 5×5 km² grid was used for application on the European scale. Block characteristic values were obtained simply by taking the median value of the point support values within the corresponding grid cell. In order to increase confidence in model predictions on large spatial scales, the model was calibrated and validated for the Netherlands, using a resolution that is feasible for Europe as a whole. Because observations are available only at the point support, it was necessary to transfer them to the block support of the model results. For this purpose, about 250 point observations of soil solution concentrations in forest soils were upscaled to a 5×5 km² grid map, using multiple linear regression analysis combined with block kriging. The resulting map with upscaled observations was used for both validation and calibration. A comparison of the map with model predictions using nominal parameter values and the map with the upscaled observations showed that the model overestimated the predicted Al and NO₃ concentrations. The nominal model results were still in the 95% confidence interval of the upscaled observations, but calibration improved the model predictions and strongly reduced the model error. However, the model error after calibration remains rather large.  相似文献   

Area-based and location-based validation of classified image objects     

《International Journal of Applied Earth Observation and Geoinformation》2014

Geographic object-based image analysis (GEOBIA) produces results that have both thematic and geometric properties. Classified objects not only belong to particular classes but also have spatial properties such as location and shape. Therefore, any accuracy assessment where quantification of area is required must (but often does not) take into account both thematic and geometric properties of the classified objects. By using location-based and area-based measures to compare classified objects to corresponding reference objects, accuracy information for both thematic and geometric assessment is available. Our methods provide location-based and area-based measures with application to both a single-class feature detection and a multi-class object-based land cover analysis. In each case the classification was compared to a GIS layer of associated reference data using randomly selected sample areas. Error is able to be pin-pointed spatially on per-object, per class and per-sample area bases although there is no indication whether the errors exist in the classification product or the reference data. This work showcases the utility of the methods for assessing the accuracy of GEOBIA derived classifications provided the reference data is accurate and of comparable scale.  相似文献   

应用天宫一号高光谱红外谱段数据反演地表温度产品及验证     

于文凭  马明国 《遥感学报》2014,18(Z1):144-151

本文利用天宫一号获取的具有高空间分辨率的红外谱段数据,选择黑河中游作为反演区域,基于辐射传输模型和Planck定律进行地表温度反演.影像的反演结果表明使用天宫一号高空间分辨率的红外谱段反演得到的地表温度能更细致合理的刻画地表温度分布,这对地表温度异质性的研究具有重要意义.为了进一步验证反演精度,本文依托黑河流域已有观测平台和系统,选取黑河中游8个典型下垫面作为验证场地,开展地面同步观测实验.实验结果表明通过反演获得的地表温度与地面实测数据的平均偏差为-0.375℃,这也说明本文的反演过程能够较为精确的使用天宫一号红外谱段反演地表温度.  相似文献