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神经网络在卫星钟差短期预报中的应用研究 总被引:2,自引:0,他引:2
本文针对卫星钟差的特点,提出了基于神经网络的卫星钟差短期预报模型,给出了基于径向基函数(RBF)网络进行卫星钟差预测的基本思想、预测模型和实施步骤,并对比分析了神经网络模型与灰色系统理论模型的区别.为验证本文提出的预报模型的可行性和有效性,利用GPS卫星钟差数据进行钟差预报精度分析,并与灰色系统模型进行对比分析.仿真结... 相似文献
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Nitrogen dioxide (NO2) is known to act as an environmental trigger for many respiratory illnesses. As a pollutant it is difficult to map accurately, as concentrations can vary greatly over small distances. In this study three geostatistical techniques were compared, producing maps of NO2 concentrations in the United Kingdom (UK). The primary data source for each technique was NO2 point data, generated from background automatic monitoring and background diffusion tubes, which are analysed by different laboratories on behalf of local councils and authorities in the UK. The techniques used were simple kriging (SK), ordinary kriging (OK) and simple kriging with a locally varying mean (SKlm). SK and OK make use of the primary variable only. SKlm differs in that it utilises additional data to inform prediction, and hence potentially reduces uncertainty. The secondary data source was oxides of nitrogen (NOx) derived from dispersion modelling outputs, at 1 km × 1 km resolution for the UK. These data were used to define the locally varying mean in SKlm, using two regression approaches: (i) global regression (GR) and (ii) geographically weighted regression (GWR). Based upon summary statistics and cross-validation prediction errors, SKlm using GWR derived local means produced the most accurate predictions. Therefore, using GWR to inform SKlm was beneficial in this study. 相似文献
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在分析鄂州市生态环境矛盾和生态服务需求的基础上,根据生态红线原理和目标,提出较为完整的生态红线划定方法,保障生态系统完整性及连续性,维护区域生态系统安全。从生态环境敏感性评价、生态服务功能重要性评价、生态灾害危险评价等3方面构建生态适宜性评价体系,展开生态适宜性分析。在GIS与RS支持下,创建了鄂州市网格空间属性数据库,采用层次分析法确定指标权重,运用叠加分析、空间分析等技术方法最终完成生态适宜性评价,将鄂州市划分为红线、黄线、蓝线、绿线等4个区域,同时,叠加整合已有的重要生态功能区,并将红线区划分为一级管控区和二级管控区,明确重点保护方向,确定生态红线管控体系。 相似文献
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针对稀疏采样难以准确估测区域土壤重金属综合污染情况和迁移变化规律的问题,提出基于GIS的多属性决策组合赋权灰色综合评价模型。首先采用GIS技术揭示土壤重金属空间变异和污染分布格局;然后利用最大化熵理论集成主客观因素,架构优化组合赋权的土壤重金属污染灰色综合评价体系;最后以试验区土壤中8种(铜、锌、铅、镉、砷、铬、汞、镍)重金属的综合污染情况为例,检验该方法应用效果。结果表明:最优组合权重的灰色综合分析方法兼顾主观偏好和客观属性,其评价结果具有更高的可信度和风险辨识度,提高了综合评价的合理性与有效性,可为土壤重金属污染监测提供方案参考。 相似文献
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随着社会的不断发展,人们对自然生态环境质量越来越重视.本文主要利用遥感技术手段,以哈尔滨市延寿县为研究区,选取2019年的Sentinel-2A影像和Landsat-8影像,利用绿度、湿度、干度、温度等生态因子指标构建遥感生态指数(RSEI)模型,对延寿县生态环境状况进行综合评价.研究结果表明:延寿县RSEI空间分布的... 相似文献
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地理国情监测是获取国情国力信息的重要手段,是掌握自然资源、生态环境以及人类活动基本情况的综合性、基础性工作。地理国情监测的实施将为生态河南建设提供动态、实时的自然、人文要素信息,林业、水资源监测信息以及环境综合整治、环境保护以及环保基础设施信息。本文着重研究地理国情监测的技术体系、生态省建设中的地理国情监测内容体系、开展地理国情监测的措施,并结合河南省地理国情监测试点项目对生态河南建设中的地理国情监测进行系统的研究。 相似文献
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GPS观测数据中的仪器偏差对确定电离层延迟的影响及处理方法 总被引:48,自引:5,他引:43
本文通过设计不同的计算方案详细分析了GPS观测中的仪器偏差对确定电离层延迟的影响,利用多天实测数据,结合仪器偏差与电离层延迟的分离方法,探讨了仪器偏差的稳定性,并提出了一种静态确定电离层延迟的方案。算例表明它能有效克服仪器偏差影响。 相似文献
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Parameterization of air temperature in high temporal and spatial resolution from a combination of the SEVIRI and MODIS instruments 总被引:2,自引:0,他引:2
Klemen Zakek Marion Schroedter-Homscheidt 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(4):414-421
Some applications, e.g. from traffic or energy management, require air temperature data in high spatial and temporal resolution at two metres height above the ground (T2m), sometimes in near-real-time. Thus, a parameterization based on boundary layer physical principles was developed that determines the air temperature from remote sensing data (SEVIRI data aboard the MSG and MODIS data aboard Terra and Aqua satellites). The method consists of two parts. First, a downscaling procedure from the SEVIRI pixel resolution of several kilometres to a one kilometre spatial resolution is performed using a regression analysis between the land surface temperature (LST) and the normalized differential vegetation index (NDVI) acquired by the MODIS instrument. Second, the lapse rate between the LST and T2m is removed using an empirical parameterization that requires albedo, down-welling surface short-wave flux, relief characteristics and NDVI data. The method was successfully tested for Slovenia, the French region Franche-Comté and southern Germany for the period from May to December 2005, indicating that the parameterization is valid for Central Europe. This parameterization results in a root mean square deviation RMSD of 2.0 K during the daytime with a bias of −0.01 K and a correlation coefficient of 0.95. This is promising, especially considering the high temporal (30 min) and spatial resolution (1000 m) of the results. 相似文献
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利用主成分分析法耦合4个生态评价指标(绿度、湿度、干度和热度)构建遥感生态指数(RSEI),对干旱区绿洲城市武威市凉州区2000年~2016年的生态环境质量进行评价。结果表明:基于主成分分析的遥感生态指数能客观定量揭示区域生态变化,RSEI均值由从0.447提高到0.458,整体提高了2.46%;武威市凉州区生态环境质量整体稍有改善但变化不大,生态环境质量等级由中等向两极化发展,东北荒漠区大面积开垦耕地使得生态环境有所改善,中部地区城市扩展和新区建设使生态环境质量下降,西南部山区受人为扰动少,生态状况基本不变。 相似文献
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遥感因为其具有大面积的同步观测、时效性、数据的综合性和可比性的特点,在城市生态环境评价与监测方面得到了广泛应用。通过选取贵阳市花溪区1997年、2005年和2013年3个时相的Landsat系列卫星影像,提取湿度、干度、绿度、热度4个评价指标,经过主成分分析后组成新型的遥感生态指数(RESI)来研究贵阳市花溪区16年间的生态环境变化。研究发现花溪区的生态环境逐渐变好,自1997年到2013年RESI均值从0.439 039上升到0.597 317,RESI均值上升了约36%,增幅较大。其中NDVI的荷载值逐年增加,呈现了与RESI很好的对应关系,表明了植被覆盖度是影响生态环境的关键性因素。 相似文献
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电荷耦合器件(CCD)是卫星应用的主流成像器件,其受空间辐射环境影响易产生辐射效应,导致卫星成像性能退化,因此CCD的在轨辐射效应分析对卫星在轨风险评估、在轨维护具有重要意义。针对空间碎片探测试验卫星成像CCD在轨出现的辐射效应,通过在轨图像数据计算,对辐射作用于CCD导致的瞬时效应、热像素、电离总剂量效应和位移损伤进行了估算。分析认为瞬时效应主要源于南大西洋异常区内高能质子入射器件导致的瞬间电离作用;热像素源于质子辐射导致的单个像素位移损伤,且数量随着在轨时间的累积不断增加,与瞬时效应无明显的相关性;在轨初期累积的电离总剂量效应和位移损伤并不突出;热像素是影响探测器光电探测性能的主要问题,在较低粒子注量时就比较显著。上述工作为卫星在轨风险评估与运行管理收集了数据依据,并初步形成了针对在轨运行光电探测载荷辐射效应分析方法,可为天基目标探测卫星成像器件的在轨辐射效应分析、抗辐射设计提供参考。 相似文献
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典型小流域土地利用景观生态评价方法及其应用研究--以浙江仙居县永安溪为例 总被引:8,自引:0,他引:8
通过对浙江省东部仙居县永安溪流域选取位于上、中、下游地段的3个乡镇,分别进行景观生态评价研究,主要是对各类斑块的面积、分维数、伸长指数、最小距离指数等计算,发现从上游到下游的土地利用方式发生了较大变化,如耕地所占比例有所增加,而乔木林地所占比例则相应降低。此外,人工干扰形成的耕地、居民点的平均斑块面积从上游到下游逐渐增加,表明居民的聚居程度逐渐增强。土地垦殖和耕作水平也发生了变化。在3个乡镇中,人工景观如耕地、园地、居民点的最小距离指数均小于人工干扰较少的景观(乔木林地、未利用地等)。在3个乡镇中分别选取居民点面积最大的3个斑块,并以这3个斑块为中心,分别建立了距离为1000m和2000m的缓冲区(缓冲区A和B),均发现在中游地段的破碎度最大,下游次之,上游最小。除缓冲区A外,在缓冲区B和乡镇范围内,随着人为干扰的增强,多样性指数增大,优势度降低。 相似文献
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在对黑龙江省内自然资源利用与管理、生态环境监管、生态保护职责落实等部门的调研基础上,探索生态文明制度建设中生态环境监管对测绘地理信息技术和成果的需求。 相似文献
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ABSTRACTRapid economic growth, a high degree of urbanization and the proximity of a large number of desert and semidesert landscapes can have a significant impact on the atmosphere of adjacent territories, leading to high levels of atmospheric pollution. Therefore, identifying possible sources of atmospheric pollution is one of the main tasks. In this study, we carried out an analysis of spatial and temporal characteristics of five main atmospheric pollutants (PM2.5, PM10, SO2, NO2, and CO) near potential source of natural aerosols, affecting seven cities (Wuhai, Alashan, Wuzhong, Zhongwei, Wuwei, Jinchang, Zhangye), located in immediate proximity to the South Gobi deserts. The results, obtained for the period from 1 January 2016 to 31 December 2018, demonstrate total concentrations of PM2.5 and PM10 are 38.2 ± 19.5 and 101 ± 80.7 μg/m3 exceeding the same established by the Chinese National Ambient Air Quality Standard (CNAAQS), being 35 and 70 μg/m3, respectively. Based on the data from Moderate Resolution Imaging Spectroradiometer (MODIS) for the whole period, Clean Сontinental (71.49%) and Mixed (22.29%) types of aerosols prevail in the region. In the spring and winter seasons maximum concentrations of pollutants and high values of Aerosol Optical Depth (AOD) in the region atmosphere are observed. PM2.5 and PM10 ratio shows the presence of coarse aerosols in the total content with value 0.43. The highest concentrations of pollutants were in the period of dust storms activity, when PM2.5 and PM10 content exceeded 200 and 1000 µg/m3, and AOD value exceeded 1. UV Aerosol Index (UVAI), Aerosol Absorbing Optical Depth (AAOD), and Single Scattering Albedo (SSA), obtained from Ozone Monitoring Instrument (OMI), demonstrate the high content of dust aerosols in the period of sandstorms. Analysis of backward trajectories shows that dust air masses moved from North to Northwest China, affecting large deserts such as Taklamakan, Gurbantunggut, Badain Jaran, Tengger, and Ulan Buh deserts. 相似文献