利用Landsat ETM+影像研究土地利用/覆盖与城市热环境的关系 --以福州市为例

如何更好地研究土地利用/覆盖与城市热环境的关系,将对城市规划、城市生态环境的改善产生积极的影响.本文利用Landsat ETM＋影像的热红外波段,研究城市热岛的分布规律,同时研究了不同土地利用类型的可见光、近红外、中红外与热红外波段的关系,以揭示土地利用/覆盖与城市热环境的关系.研究表明,在卫星影像上,城市建成区的可见光、近红外、中红外与热红外波段的相关性较为显著,通过对不同土地利用类型上可见光波段、近红外、中红外与热红外波段的分析,获取城市建成区上的热环境分布.     

基于热红外遥感的城市热场形成机制及特征分析--以成都市为例

利用LANDSAT5的TM6热红外数据和实时的地表温度，优选了一种方法进行成都市地面温度场反演，根据反演结果对成都市地表温度场分布特征进行了分析，同时定量分析了植被覆盖和水域廊道对地表温度场分布的影响，定量分析的结果对城市区域布局和规划有积极意义。     

草原露天矿区草地沙化的遥感分析--以霍林河矿区为例

研究了霍林河矿区1987—2003年的草地沙化情况；探讨了露天煤矿区草地沙化的影响因子；采用线性光谱混合分解模型(LSMM)完成了草地沙化信息的提取，对引发草地沙化的直接破坏信息则采用决策树和BP神经网络相结合的方法进行了提取．结果表明：随着累计原煤产量的增加，草地破坏面积和草地沙化面积在逐年扩大；矿区建设期内草地沙化速率远高于生产期；草地直接破坏面积与草地沙化面积具有明显的正相关关系，故可将草地直接破坏面积作为评价、预测该区煤炭开发对周围草地沙化影响的重要依据．     

利用遥感信息修正数字河网的研究

针对DEM本身存在的缺少关于平坦地区和洼地以及水库或湖泊水流路径的数据信息的缺陷,以及没有较高精度DEM的地区难以构建准确的数字河网的问题,提出利用遥感影像作为反输入修正数字河网的新思路,并尝试了利用遥感结合DEM提取河网水系的方法.应用分析表明该方法可以生成较符合实际的连续的数字河网,而且适用于没有较高精度的DEM的无资料地区。此方法值得进一步研究.     

Evapotranspiration on western U.S. rivers estimated using the Enhanced Vegetation Index from MODIS and data from eddy covariance and Bowen ratio flux towers

We combined remote sensing and in-situ measurements to estimate evapotranspiration (ET) from riparian vegetation over large reaches of western U.S. rivers and ET by individual plant types. ET measured from nine flux towers (eddy covariance and Bowen ratio) established in plant communities dominated by five major plant types on the Middle Rio Grande, Upper San Pedro River, and Lower Colorado River was strongly correlated with Enhanced Vegetation Index (EVI) values from the Moderate Resolution Imaging Spectrometer (MODIS) sensor on the NASA Terra satellite. The inclusion of maximum daily air temperatures (T_a) measured at the tower sites further improved this relationship. Sixteen-day composite values of EVI and T_a were combined to predict ET across species and tower sites (r² = 0.74); the regression equation was used to scale ET for 2000-2004 over large river reaches with T_a from meteorological stations. Measured and estimated ET values for these river segments were moderate when compared to historical, and often indirect, estimates and ranged from 851-874 mm yr^− 1. ET of individual plant communities ranged more widely. Cottonwood (Populus spp.) and willow (Salix spp.) stands generally had the highest annual ET rates (1100-1300 mm yr^− 1), while mesquite (Prosopis velutina) (400-1100 mm yr^− 1) and saltcedar (Tamarix ramosissima) (300-1300 mm yr^− 1) were intermediate, and giant sacaton (Sporobolus wrightii) (500-800 mm yr^− 1) and arrowweed (Pluchea sericea) (300-700 mm yr^− 1) were the lowest. ET rates estimated from the flux towers and by remote sensing in this study were much lower than values estimated for riparian water budgets using crop coefficient methods for the Middle Rio Grande and Lower Colorado River.     

An improved in-situ bio-optical data set for ocean color algorithm development and satellite data product validation

Global satellite ocean color instruments provide the scientific community a high-resolution means of studying the marine biosphere. Satellite data product validation and algorithm development activities both require the substantial accumulation of high-quality in-situ observations. The NASA Ocean Biology Processing Group maintains a local repository of in-situ marine bio-optical data, the SeaWiFS Bio-optical Archive and Storage System (SeaBASS), to facilitate their ocean color satellite validation analyses. Data were acquired from SeaBASS and used to compile a large set of coincident radiometric observations and phytoplankton pigment concentrations for use in bio-optical algorithm development. This new data set, the NASA bio-Optical Marine Algorithm Data set (NOMAD), includes over 3400 stations of spectral water-leaving radiances, surface irradiances, and diffuse downwelling attenuation coefficients, encompassing chlorophyll a concentrations ranging from 0.012 to 72.12 mg m^− 3. Metadata, such as the date, time, and location of data collection, and ancillary data, including sea surface temperatures and water depths, accompany each record. This paper describes the assembly and evaluation of NOMAD, and further illustrates the broad geophysical range of stations incorporated into NOMAD.     

Substrate age and precipitation effects on Hawaiian forest canopies from spaceborne imaging spectroscopy

We used spaceborne imaging spectroscopy provided by the Earth Observing-1 Hyperion sensor to quantify the relative importance of precipitation and substrate age that control ecosystem development and functioning in Metrosideros polymorpha rainforests of Hawaii. Four hyperspectral vegetation indices provided metrics of forest canopy structure, biochemistry and physiology to compare along gradients of annual rainfall (750 to > 6000 mm year^− 1) and substrate age (0 to 250,000 years). The canopy greenness index NDVI increased with annual precipitation and substrate age, but saturated in forests with rainfall of 3000 mm year^− 1. Precipitation and substrate age were roughly equal contributors to the observed greenness of the forests. A canopy water content index (NDWI) also increased with precipitation and substrate age, but did not reach a maximum until very wet (> 5000 mm year^− 1) forest conditions were encountered on the oldest substrates. The water index appears superior to the NDVI in capturing spatial and climate-substrate driven variations in canopy structure. The photochemical reflectance index (PRI) indicated highest light-use efficiency levels in canopies on the most developed substrates and at annual precipitation levels of 3-4500 mm year^− 1. A leaf carotenoid index (CRI) suggested a maximum canopy photosynthetic capacity at ∼ 4000 mm rainfall year^− 1 on the oldest substrates. These results quantify the sensitivity of rainforest canopies to changing precipitation and soil conditions, and they corroborate plot-scale analyses in native Hawaiian forests ecosystems. Structural and functional studies of remote rainforest regions are possible with spaceborne imaging spectroscopy, and could be used to understand the dynamics of rainforests with climate change.     

促进国家对地观测体系顺利发展的思考

介绍了我国对地观测体系已经开展的工作;提出了改进遥感数据质量是基础,扩大数据共享是关键,开展典型应用为国民经济服务是目的的发展战略.     

声表面波谐振型无源无线温度传感器硬件系统

介绍了一种基于声表面波谐振器的无源无线温度传感系统,系统采用一次变频的构成方式,解决了传统传感系统存在电路结构复杂和控制灵活性差的缺点,给出了系统的具体构成、工作原理和天线的设计。与传统系统构成相比,本系统的构成更简洁,操作性和灵活性更强。实验验证了本系统构成方式的可行性和天线设计的优点。