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Forest mapping:a comparison between hyperspectral and multispectral images and technologies

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Journal of Forestry Research 2018年第5期29卷 1395-1405页

作者： Mohamad M.Awad remote sensing center National Council for Scientific Research

Mapping forests is an important process in managing natural *** present,due to spectral resolution limitations,multispectral images do not give a complete separation between different forest *** contrast,advances in remote sensing technologies have provided hyperspectral tools and images as a solution for the determination of *** this study,spectral signatures for stone pine（Pinus pinea L.） forests were collected using an advanced spectroradiometer ＂ASD FieldSpec 4 Hi-Res＂ with an accuracy of 1 *** spectral signatures are used to compare between different multispectral and hyperspectral satellite *** comparison is based on processing satellite images： hyperspectral Hyperion,hyperspectral CHRIS-Proba,Advanced Land Imager（ALI）,and Landsat *** and classification methods for hyperspectral and multispectral images are investigated and *** addition,a well-known hyperspectral image classification algorithm,spectral angle mapper（SAM）,has been improved to perform the classification process efficiently based on collected spectral *** results show that the modified SAM is 9% more accurate than the conventional *** addition,experiments indicate that the CHRIS-Proba image is more accurate than Landsat 8（overall accuracy 82%,precision 93%,and Kappa coefficient 0.43 compared to 60,67%,and 0.035,respectively）.Similarly,Hyperion is better than ALI in mapping stone pine（overall accuracy 92%,precision 97%,and Kappa coefficient 0.74 compared to 52,56%,and -0.032,respectively）.

关键词： Classification Economy Hyperspectral Multispectral Spectral signatures Stone pine

A Climatological Investigation of the Activity of Summer Subtropical Vortices

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Acta meteorologica Sinica 2008年第1期22卷 1-7页

作者：罗哲贤代刊 School of remote sensing NUIST national Meteorological center

By applying a new vortex detection method to the ECMWF 40-yr reanalysis （ERA40） data from 1985 to 2002, the climatology of summer vortices has been investigated in five subtropical regions, i.e., the northwestern Pacific, northeastern Pacific, northwestern Atlantic, northeastern Atlantic, and Australia- South Pacific, followed by validation with NCEP/NCAR reanalysis data. Results are as follows：（1） The spatial distributions of ERA40 vortex activities （VAC） were well consistent with those of NCEP/NCAR reanalysis （NRA） results in all regions, especially in northwestern Pacific. （2） Because of different model resolutions, both the number and intensity of vortices obtained from NRA were significantly weaker than ERA40＇s. （3） Vortices mainly cruised in coasts and the adjacent seas, from where to the land or the open sea vortex activities were gradually decreased. （4） There were two active centers in the northwestern Pacific： one was located in South China Sea and the other, as the largest center of the five regions, spread from the east side of the Philippines to Japan. （5） Over the northwestern Atlantic, most vortices occurred in Panama and its west-side offshore. （6） The spatial distributions of vortices were alike between the northeastern Pacific and northeastern Atlantic, both spreading from coasts to the west-side sea at 5°-20°N. （7） In the Australia-South Pacific, vortices were not as active as those in the other four regions, and mostly took place in the equator-side of near ocean areas. （8） Except the northwestern Pacific and northwestern Atlantic, the VAC interannual variations in the other three regions were different between ERA40 and NRA data. （9） In the northwestern Pacific and northwestern Atlantic, the VAC interannual variation could be separated to several distinct stages. （10） Since the mid 1980s, mean vortex intensity was getting increased in the northwestern Pacific, which was most significant in the subtropical areas on a global basis. In the western

关键词： subtropics vortex climatology vortex intensity vortex detection

Retrieval of sea surface winds under hurricane conditions from GNSS-R observations

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Acta Oceanologica Sinica 2016年第9期35卷 91-97页

作者： JING Cheng YANG Xiaofeng MA Wentao YU Yang DONG Di LI Ziwei XU Cong State Key Laboratory of remote sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of Sciences national Engineering center for Geoinformatics Institute of Remote Sensing and Digital EarthChinese Academy of Sciences

Reflected signals from global navigation satellite systems（GNSSs） have been widely acknowledged as an important remote sensing tool for retrieving sea surface wind *** power of GNSS reflectometry（GNSS-R）signals can be mapped in delay chips and Doppler frequency space to generate delay Doppler power maps（DDMs）,whose characteristics are related to sea surface roughness and can be used to retrieve wind ***,the bistatic radar cross section（BRCS）,which is strongly related to the sea surface roughness,is extensively used in ***,a bistatic radar cross section（BRCS） map with a modified BRCS equation in a GNSS-R application is *** the BRCS map,three observables are proposed to represent the sea surface roughness to establish a relationship with the sea surface wind *** Hurricane Dennis（2005） GNSS-R data are then *** than 16 000 BRCS maps are generated to establish GMFs of the three ***,the proposed model and classic one-dimensional delay waveform（DW） matching methods are compared,and the proposed model demonstrates a better performance for the high wind speed retrievals.

关键词： global navigation satellite system-reflectometry Hurricane Dennis delay doppler maps bistatic radar cross section map sea surface wind speed

Scale effect of Planck's law over nonisothermal blackbody surface

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Science China(Technological Sciences) 1999年第6期42卷 652-656页

作者：李小文王锦地 A. H. Strahler Research center for remote sensing and GIS Beijing Normal University Department of Geography and center for remote sensing

Many physical laws, principles, models, measurement methods, etc., are applicable only to either a point on surface or a homogeneous surface. However, remote sensing deals with pixels which may range from meters to kilometers. Therefore scale effects of these laws and measurements are inevitable problems which must be faced. As an example, the spatial scale effect of Planck Law over nonisothermal blackbody surface is considered.

关键词： scale effect Planck’s law reciprocity.

Comparison of SO_2 column retrievals from BRD and DOAS algorithms

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Science China Earth Sciences 2017年第9期60卷 1694-1706页

作者： YAN HuanHuan LI XiaoJing WANG WeiHe ZHANG XingYing CHEN LiangFu HAN Dong YU Chao GAO Ling national Satellite Meteorological center China Meteorological Administration State Key Laboratory of the Science of remote sensing Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences Normal College Qingdao University

Atmospheric SO_2 has a significant impact on the urban environment and global climate. Band Residual Difference Algorithm(BRD) and Differential Optical Absorption Spectroscopy(DOAS) were used respectively by NASA and ESA science team to derive SO_2 columns from satellite observations, but there are few studies on the comparison and validation of BRD and DOAS SO_2 retrievals under the same observation conditions. In this study, the radiative transfer model SCIATRAN was firstly used to validate the accuracies of BRD and DOAS SO_2 retrievals, and analyse the uncertainty of SO_2 retrieval caused by band selection,O_3 absorption, aerosol, surface reflectance, solar and viewing zenith angle. Finally, BRD and DOAS algorithms were applied to the same radiances from satellite observations, and comparisons of BRD and DOAS SO_2 retrievals were conducted over volcanic eruption and North China. Results show that, for the case with low SO_2 columns, BRD SO_2 retrievals have higher retrieval accuracy than DOAS, but typical seasonal variation with high SO_2 column in winter and low in summer can be more clearly discernible in DOAS SO_2 retrievals than BRD from satellite observations. For the case with high SO_2 columns, the differences between BRD(310.8–314.4 nm) and DOAS(315–327 nm) retrievals are large, and the value and accuracy of BRD(310.8–314.4 nm) SO_2 retrievals are lower than those of DOAS(315–327 nm) retrievals. Compared with the SO_2 inputs in forward model, both BRD(310.8–314.4 nm) and DOAS(315–327 nm) SO_2 retrievals are underestimated for the case with high SO_2 columns. The selection of wavelength range can significantly affect the accuracy of SO_2 retrieval. The error of BRD SO_2 retrieval from 310.8–314.4 nm is lower than other bands in the ultraviolet spectral region(306–327 nm). The increase of wavelength in the ultraviolet spectral region306–330 nm can reduce the underestimation of DOAS SO_2 retrievals in the case of high SO_2 column, but slight overestimation o

关键词： SO2 DOAS BRD Comparison

Analysis of the dynamics of land use change and its prediction based on the integration of remotely sensed data and CA-Markov model,in the upstream Citarum Watershed,West Java,Indonesia

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International Journal of Digital Earth 2019年第10期12卷 1151-1176页

作者： Fajar Yulianto Taufik Maulana Muhammad Rokhis Khomarudin remote sensing Application center Indonesian National Institute of Aeronautics and Space(LAPAN)JakartaIndonesia

In this research,the integration of remotely sensed data and Cellular Automata-Markov model(CA-Markov)have been used to analyze the dynamics of land use change and its prediction for the next *** phase for the CA-Markov model has been created based on the input pair of land use,which is the result of land use mapping using Maximum Likelihood(ML)***-map comparison has been used to evaluate process accuracy assessment of the training phase for the CA-Markov ***,the simulation phase for the CAMarkov model can be used to predict land use map for the next *** analyze of the dynamics of land use change and its prediction during the period 1990 to 2050 can be obtained that the land serves as a water absorbent surfaces such as primary forest,secondary forest and the mixed garden area continued to ***,on build land area that can lead to reduced surface water absorbing tends to increase from year to *** results of this research can be used as input for the next research,which aims to determine the impact of land use changes in hydrological conditions against flooding in the research area.

关键词： Multi-temporal remotely sensed data CA-Markov model dynamics land use change

Tailoring Light–Matter Interactions in Overcoupled Resonator for Biomolecule Recognition and Detection

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Nano-Micro Letters 2025年第1期17卷 262-280页

作者： Dongxiao Li Hong Zhou Zhihao Ren Cheng Xu Chengkuo Lee Department of Electrical and Computer Engineering National University of SingaporeSingapore 117583Singapore center for Intelligent Sensors and MEMS(CISM) National University of SingaporeSingapore 117608Singapore

Plasmonic nanoantennas provide unique opportunities for precise control of light–matter coupling in surface-enhanced infrared absorption(SEIRA)spectroscopy,but most of the resonant systems realized so far suffer from the obstacles of low sensitivity,narrow bandwidth,and asymmetric Fano resonance ***,we demonstrated an overcoupled resonator with a high plasmon-molecule coupling coefficient(μ)(OC-Hμresonator)by precisely controlling the radiation loss channel,the resonator-oscillator coupling channel,and the frequency detuning *** observed a strong dependence of the sensing performance on the coupling state,and demonstrated that OC-Hμresonator has excellent sensing properties of ultra-sensitive(7.25%nm^(−1)),ultra-broadband(3–10μm),and immune asymmetric Fano *** characteristics represent a breakthrough in SEIRA technology and lay the foundation for specific recognition of biomolecules,trace detection,and protein secondary structure analysis using a single array(array size is 100×100μm^(2)).In addition,with the assistance of machine learning,mixture classification,concentration prediction and spectral reconstruction were achieved with the highest accuracy of 100%.Finally,we demonstrated the potential of OC-Hμresonator for SARS-CoV-2 *** findings will promote the wider application of SEIRA technology,while providing new ideas for other enhanced spectroscopy technologies,quantum photonics and studying light–matter interactions.

关键词： Plasmonic nanoantennas Light-matter interaction Surface-enhanced infrared absorption Overcoupled Biosensing

Forest canopy height mapping over China using GLAS and MODIS data

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Science China Earth Sciences 2015年第1期58卷 96-105页

作者： YANG Ting WANG Cheng LI GuiCai LUO SheZhou XI XiaoHuan GAO Shuai ZENG HongCheng Key Laboratory of Digital Earth Science Institute of Remote Sensing and Digital EarthChinese Academy of Sciences University of Chinese Academy of Sciences national Satellite Meteorological center China Meteorological Administration national Key Laboratory of remote sensing Institute of Remote Sensing and Digital EarthChinese Academy of Sciences Faculty of Forestry University of Toronto

The Geoscience Laser Altimeter System(GLAS)accurately detects the vertical structural information of a target within its laser spot and is a promising system for the inversion of structural features and other biophysical parameters of forest *** the GLAS footprints are discontinuously distributed with a relativity low density,continuous vegetation height distributions cannot be mapped with a high accuracy using GLAS data *** MODIS BRDF product provides more forest structural information than other optical remote sensing *** study aimed to map forest canopy heights over China from the GLAS and MODIS BRDF ***,the waveform characteristic parameters were extracted from the GLAS data by the method of wavelet analysis,and the terrain index was calculated using the ASTER GDEM ***,the model reducing the topographic influence was constructed from the waveform characteristic parameters and terrain ***,the final canopy height estimation model was constructed from the neural network combining the canopy height estimated with the GLAS point and the MODIS BRDF data,and applied to get the continuous canopy height map over ***,the map was validated by the measured data and the airborne Li DAR data,and the validation results indicated that forest canopy heights can be estimated with high accuracy from combined GLAS and MODIS data.

关键词： GLAS waveform decomposition terrain index canopy height model

Apparent reciprocity failure in directional reflectance of structured surfaces

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Progress in Natural Science:Materials International 1999年第10期9卷 28-33页

作者：李小文,王锦地,Alan H.STRAHLER Research center for remote sensing Beijing Normal University Beijing 100875 China center for remote sensing and Department of Geography Boston University MA 02215 USA Research center for remote sensing Beijing Normal University Beijing 100875 China center for remote sensing and Department of Geography Boston University MA 02215 USA

Whether the reciprocity principle can be applied to the field or satellite observations of directional reflectance of land surface has been a question important to both theory and practice of land surface remote sensing. Under the assumption that every point on ground follows reciprocity, this paper explains why the heterogeneity of land surface can still yield apparent failure of the principle at the scale of remote sensing pixel.

关键词： reciprocity structure BRDF