喀斯特石漠化信息遥感提取的不确定性

我国西南喀斯特地区以石漠化为特征的生态环境退化严重,遥感是快速、大面积石漠化定性评价、关健指标定量提取必不可少的手段.在简述喀斯特生态地质背景复杂性的基础上,系统分析了目前喀斯特石澳化信息遥感提取在遥感数据源、提取方法、、精度验证、不确定性源等方面的问题,并提出未来石漠化遥感监测的重点研究内容.     

全球变化下地表反照率研究进展

地表反照率表征地球表面对太阳辐射的反射能力,决定着地表与大气之间辐射能量的分配过程,是影响地球气候系统的关键变量。在全球变化日益突出的今天,地表反照率与全球变化的相互影响机制已经成为地球科学研究领域的热点问题之一。地表反照率的细微变化,会影响到地气系统的能量收支平衡,进而引起区域以至全球气候变化。详细介绍地表反照率影响...     

Airborne imagery of a disintegrating Sargassum drift line

Airborne hyperspectral and thermal infrared imagery collected over the Florida Current provide a view of the disintegration of a Sargassum drift line in 5 m s⁻¹ winds. The drift line consists mostly of rafts 20-80 m² in size, though aggregations larger than 1000 m² also occur. Rafts tend to be elongated, curved in the upwind direction, and 0.1-0.5 °C warmer than the surrounding ocean surface. Long weed ‘trails’ extending upwind from the rafts are evidence of plants dropping out and being left behind more rapidly drifting rafts. The raft line may be a remnant of an earlier Sargassum frontal band, which is detectible as an upwind thermal front and areas of submerged weed. Issues are identified that require future field measurements.     

全球尺度下遥感与地理信息系统一体化软件平台研建进展

地理信息科学与技术在全球变化和地球系统科学研究中,正发挥越来越重要的作用.而在全球尺度下开展分析,必须发展用基于3维坐标进行分析,而且要具备全球尺度上的地表信息提取能力,并支持全球尺度的空间分析与应用的软件.介绍了在Google Earth基础上,开发的遥感和地理信息系统一体化软件平台:全球制图者(Global Map...     

赤水河流域生态环境状况遥感监测分析

利用多源卫星遥感数据,对贵州赤水河流域2021年生态环境状况进行监测,定量评估赤水河流域的生态环境状况。结果表明：1）赤水河流域生态环境状况EI指数为68.15,生态环境状况综合评价为良;2）赤水河流域贵州段的土地利用类型主要以林地和耕地为主,流域监测区内生境质量为I级,生物多样性丰富;3）流域NDVI平均值0.42,植被覆盖度高,固土护坡、水源涵养能力较强;4）流域雨水充沛,河网密布,水网密度高达6.8;5）流域土地坡度起伏大,监测区内中度以上土地侵蚀强度的土地面积约占49%。相比,流域污染负荷指数较低,生态环境治理成效持续显现。     

神经网络敏感性分析及其在遥感影像分类中的应用

针对基于连接权的神经网络敏感性分析方法中求取敏感性系数的不稳定性,提出一种优化连接权的神经网络敏感性分析方法。首先采用遗传算法根据误差最小化原则对神经网络进行优化,在优化的神经网络模型上进行基于连接权的敏感性分析。以1个数值模拟实例和华盛顿广场地区的遥感图像地物分类为例,验证所提方法的有效性。实验结果表明,所提方法求取输入变量的敏感性系数是稳定有效的,能有效筛选出遥感图像中对分类贡献较大的特征波段,达到降维的同时提高分类精度。     

阜新市海州露天矿区开采对空气质量的影响

利用遥感技术可快速、准确、大范围地监测矿山开发状况和了解矿区生态环境现状。以Landsat TM和CBERS卫星影像为主要数据来源,采用栅格数据、遥感数据与统计数据相结合的内业处理与外业调查相结合的技术路线,通过目视解译、人机交互解译、计算机自动识别等遥感信息提取技术和遥感影像处理,分析近20 a阜新市海州露天矿矿区面积变化趋势及近5a来对当地空气质量的影响。结果表明:阜新市海州露天矿矿区面积逐年减小,当地空气质量逐年优化。由此可见,露天矿矿区面积的减小对于当地空气质量的改善起到了一定的推动作用。     

A land surface data assimilation framework using the land information system: Description and applications

The Land Information System (LIS) is an established land surface modeling framework that integrates various community land surface models, ground measurements, satellite-based observations, high performance computing and data management tools. The use of advanced software engineering principles in LIS allows interoperability of individual system components and thus enables assessment and prediction of hydrologic conditions at various spatial and temporal scales. In this work, we describe a sequential data assimilation extension of LIS that incorporates multiple observational sources, land surface models and assimilation algorithms. These capabilities are demonstrated here in a suite of experiments that use the ensemble Kalman filter (EnKF) and assimilation through direct insertion. In a soil moisture experiment, we discuss the impact of differences in modeling approaches on assimilation performance. Provided careful choice of model error parameters, we find that two entirely different hydrological modeling approaches offer comparable assimilation results. In a snow assimilation experiment, we investigate the relative merits of assimilating different types of observations (snow cover area and snow water equivalent). The experiments show that data assimilation enhancements in LIS are uniquely suited to compare the assimilation of various data types into different land surface models within a single framework. The high performance infrastructure provides adequate support for efficient data assimilation integrations of high computational granularity.