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1.
耦合京津冀气溶胶模式的HJ-1卫星CCD数据大气校正   总被引:1,自引:0,他引:1  
针对目前HJ-1CCD大气校正没有考虑中国地区气溶胶模式的问题,提出一种耦合中国地区局部气溶胶模式的大气校正方法。以京津冀地区作为研究区域,该方法对地基北京城区和香河站点反演的气溶胶模式参数进行聚类,得到京津冀地区具有代表性的四类气溶胶模式,并根据四类气溶胶模式来建立查找表进行气溶胶光学厚度的反演。HJ-1CCD数据没有短波红外波段(2.12μm),无法采用MODIS的气溶胶算法中获得地表反射率的方法来计算蓝红波段的反射率,本文在气溶胶光学厚度的反演中采用HJ-1卫星的蓝色(0.43~0.52μm)和红色(0.63~0.69μm)波段的反射率比值作为误差方程的依据,不需要输入地表目标的反射率。基于反演后的光学厚度对HJ-1CCD数据进行大气校正,并与ASD光谱辐射计测量数据以及MODIS地表产品数据(MOD09)进行对比。结果表明,该方法得到的大气校正结果与ASD测量结果接近,并与MOD09有较强的相关性,红色波段的平均相关系数达到了0.8以上,受气溶胶影响最大的蓝色波段平均的相关系数也达到了0.75左右。  相似文献   

2.
基于环境一号卫星的霾监测应用   总被引:3,自引:0,他引:3  
随着我国城市的发展,霾已经成为大气污染的重要形式。从霾的物理性质出发,利用米理论和RT3计算了霾的光学性质和反射特性,表明环境一号(HJ-1)卫星CCD相机的第一和第二波段最适宜霾的反演。然后,利用深蓝算法,基于MODIS地表反射率产品建立地表反射率库,实现霾的反演。最后,以北京为试验区进行了2009年全年的反演试验,结合地面观测结果的验证表明,HJ-1监测结果与地面结果有着较好的相关性(相关系数大于0.9),但整体大于地面监测结果。讨论表明,地表反射率库的误差对区分霾影响较小(带来的霾光学厚度误差小于0.1),HJ-1的CCD传感器的辐射分辨率尚不能完全满足霾监测需求。  相似文献   

3.
在陆地上空气溶胶遥感中,地表多样性会导致地表反射率计算误差增加,降低地气解耦精度,进而影响气溶胶反演精度。多角度、多光谱和偏振观测数据的引入有利于解决地气解耦精度和气溶胶参数的提取精度受限的问题。基于多角度偏振辐射计(AMPR)航空多光谱遥感数据,结合气溶胶散射和地表偏振反射规律,提出了在1 640 nm波段对AMPR观测偏振反射率进行连续大气辐射校正,实现地气解耦的方法。在此基础上,构建了陆地上空气溶胶偏振反演算法。运算过程中使用665和865 nm波段观测数据进行气溶胶参数提取,使用1 640 nm波段观测数据结合提取的气溶胶参数进行大气偏振辐射校正,重新获取地表偏振反射率。在反演过程中引入迭代,逐步逼近大气与地表真实辐射值,实现地气解耦,并利用查找表的方法实现气溶胶光学厚度反演。通过AMPR在京津唐地区5个架次的航空观测实验数据对反演算法进行了验证,结果与地基CE318观测数据一致性较好,在气溶胶光学厚度小于0.5的情况下,反演平均误差为约0.03。  相似文献   

4.
基于HJ-1-CCD数据的地表反射率反演与验证   总被引:4,自引:0,他引:4  
环境一号卫星OCD相机(HJ-1-CCD)30m的空间分辨率在地物识别中具有潜在优势,然而由于缺少短波红外通道,利用暗像元法反演地表反射率较为困难.基于北京与珠三角地区的地物光谱试验,获得暗像元的植被指数与红、蓝波段反射率比值,构建基于辐射传输模型的大气校正算法.为了验证算法精度,将北京地区卫星反演值与实测的草坪、水体...  相似文献   

5.
资源三号卫星多光谱数据的大气校正研究   总被引:2,自引:0,他引:2  
资源三号卫星多光谱数据空间分辨率达到5.8m,能够很好的应用于地物分类和识别,由于其缺乏短波红外波段,无法采用暗目标法进行大气校正,因此,提出通过6S辐射传输模型构建大气校正系数查找表,结合MODIS数据反演的气溶胶光学厚度参数的大气校正方法,对ZY-3卫星多光谱(MUX)数据进行大气校正。采用敦煌地区星地同步测量的石膏矿、戈壁两种地物光谱对大气校正结果进行了验证,并比较了大气校正前后归一化植被指数(NDVI)。结果表明:大气校正后的地面反射率与石膏矿、戈壁两种地物实测光谱数据相对误差不超过6%;大气校正增大了植被的NDVI与其他地物的NDVI的差值,突出在植被监测方面的应用能力。  相似文献   

6.
基于改进暗目标法山区HJ CCD影像气溶胶光学厚度反演   总被引:2,自引:0,他引:2  
国产HJ CCD影像在环境与灾害监测预报方面具有巨大的应用潜力,但其缺少中红外波段无法直接应用传统暗目标法反演气溶胶光学厚度,尤其山区受地形影响,气溶胶时空分布变化显著,影响了HJ CCD影像的大气校正精度。基于山区森林植被分布广的特点引入红波段直方图阈值法自动提取山区浓密植被暗像元,构建红蓝波段地表反射率间的线性关系,利用6S辐射传输模型建立查找表反演暗像元的气溶胶光学厚度,并通过空间插值推演到整幅影像。HJ CCD影像反演结果与MODIS气溶胶产品的空间分布趋势一致性非常好,且前者具有更高的空间分辨率特性,更适合山区气溶胶的遥感监测。二者的散点图拟合曲线为y=0.828 6x-0.001,R2达到0.984 3,表明改进暗目标法能有效地反演山区HJ CCD影像气溶胶光学厚度。工作中对传统暗目标法的改进有效地解决了HJ CCD影像只有可见光、近红外波段,在求解辐射传输方程时信息不足的问题,同时,改进方法中充分考虑了山区复杂地形环境的影响,为山区HJ CCD影像进行逐点大气校正奠定了基础,并为其自动化处理提供了可能。分析还显示,红波段直方图阈值法提取浓密森林暗像元比NDVI阈值法具有明显的优势;查找表建立和暗像元红、蓝波段地表反射率关系都会显著的影响气溶胶光学厚度的反演精度,是进一步改善算法、提高反演精度的重要研究方向。  相似文献   

7.
大气气溶胶是影响城市环境空气质量的重要因素,同时对人类健康具有重要影响。传统的气溶胶遥感反演方法多适用于海洋及植被等地表反射率较低的区域,对于城市等高亮地表区域,地表反射率较高且难以确定,气溶胶反演面临巨大挑战。针对该问题,提出一种新的地表反射率的确定方法,将下垫面划分为暗地表和亮地表两种类型,分别使用可见光与短波红外的线性关系和利用长时间序列MODIS表现反射率数据使用最小值合成技术构建先验数据集的方法,确定其地表反射率,然后基于辐射传输方程理论利用查找表方法,进行气溶胶光学厚度反演。选择下垫面复杂、空气污染问题严重的北京市作为研究区,应用MODIS数据进行气溶胶反演实验,最后使用北京站、香河站、北京CAMS站和北京RADI站4个AERONET气溶胶地基观测数据和MODIS气溶胶产品对反演结果进行对比验证。结果表明该算法气溶胶反演结果与地基观测数据具有较高的一致性(R2=0.902),能以较高精度实现城市等高反射率地区的气溶胶反演,反演精度与空间连续性上较MOD04有显著提高。  相似文献   

8.
Xu H  Gu XF  Li ZQ  Li L  Chen XF 《光谱学与光谱分析》2011,31(10):2798-2803
水体大气校正问题是开展我国环境一号卫星水色遥感定量化应用的关键。针对环境卫星CCD相机的特点,以水气耦合的辐射传输模型构建大气校正参数查找表,研究以地面气象数据辅助的逐像元水体大气校正方法,实现水体离水反射率和遥感反射比的反演。以现场测量数据和MODIS数据为参考进行水体大气校正效果验证,研究发现CCD相机的反演结果在蓝、绿波段的精度较高而红、近红的反演结果系统偏大。研究结果还表明气溶胶模型是影响水体大气校正精度的重要因素。  相似文献   

9.
针对基于多光谱数据有限光谱信息重建地表反射率光谱的病态求解难题,提出一种基于冠层辐射传输物理机理并充分考虑像元异质性的地表反射率光谱重建方法,该方法假设混合像元由植被和土壤两种地物类型组成,利用冠层辐射传输模型构造端元光谱查找表,进而通过组分比例因子估算实现基于多光谱图像的高光谱地表反射率模拟。以Landsat ETM+多光谱图像为例的地表反射率超光谱重建验证实验结果表明,模拟的反射率光谱能够较好的反映不同地物特征信息。进一步地,利用模拟的地表反射率拟合Landsat ETM+图像和MODIS图像,各波段模拟图像与实际观测图像之间具有较高的相关系数(Landsat:0.90~0.99,MODIS:0.74~0.85),进一步验证了该方法的可行性。  相似文献   

10.
基于清洁水体像元法的环境-1A卫星CCD水体图像大气校正   总被引:1,自引:0,他引:1  
环境卫星(HJ-1A/B)的CCD图像数据在内陆水环境遥感监测中具有很大的潜力,但它的大气校正的精度是影响其定量化应用的重要因素.文章以上海淀山湖地区HJ-1A卫星搭载的CCD1多光谱数据为应用实例,首先实现了瑞利散射的精确计算,在气溶胶散射的计算中,由于内陆湖泊Ⅱ类水体的光学特性,致使环境星CCD数据的近红外波段的离...  相似文献   

11.
Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.  相似文献   

12.
A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.  相似文献   

13.
The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.  相似文献   

14.
15.
A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.  相似文献   

16.
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.  相似文献   

17.
A transient suppression method for piezoelectric ceramic transducer is presented. By adding some special pedestal pulses to the original transmitted signal, the transient effects in the output of the transducer can be just precisely transmission by use of a narrowband transducer. canceled, thereby achieving the broadband The experimental results show that the transient responses of the sinusoid pulses and coded signals are suppressed successfully and the acoustic waveforms radiated into the surrounding water are improved significantly.  相似文献   

18.
We experimentally demonstrate amplitude squeezed soliton utilizing intensity-dependent self-phase modulation in an asymmetric Sagnac interferometer.The system.whose components are connected via ferrule connector/physical connection(FC/PC)fiber connectors,constitutes all-fiber configuration to generate squeezed soliton.Soliton amplitude reduction measured by homodyne detection is near 4.0 dB below the shot-noise level.Optimal squeezing fields in both simple and compact all-fiber configuration are obtained.  相似文献   

19.
The(2 1)-dimensional nonlinear Schr(o)dinger(NLS)equation with spatially inhomogeneous nonlinearities is investigated,which describes propagation of light in(2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities.New types of optical modes and nonlinear effects in optical media are presented numerically.The results reveal that the regular split of beam can be obtained in (2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities,by adjusting the guiding parameter.Furthermore,the stability of beam regular split is discussed numerically,and the results reveal that the beam regular split is stable to the finite initial perturbations.  相似文献   

20.
In the real-world application of face recognition system, owing to the difficulties of collecting samples or storage space of systems, only one sample image per person is stored in the system, which is so-called one sample per person problem. Moreover, pose and illumination have impact on recognition performance. We propose a novel pose and illumination robust algorithm for face recognition with a single training image per person to solve the above limitations. Experimental results show that the proposed algorithm is an efficient and practical approach for face recognition.  相似文献   

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