MODIS_LST与AMSR-E_BT的相关性及地表温度反演     

时洪涛  宋冬梅  单新建  崔建勇  臧琳  沈晨  屈春燕  任鹏  邵红梅  盛辉  吴会胜  宋先月 《地球信息科学学报》2016,18(4):564-574

本文以2007年和2008年MODIS每日地表温度（LST）数据及AMSR-E地表亮温（BT）数据为研究对象,结合土地覆盖类型数据,统计分析MODIS_LST与AMSR-E_BT在不同土地覆盖类型、频率和极化方式条件下的相关性。结果表明,频率在18.7、23.8和36.5 GHz的AMSR-E-BT与MODIS_LST的相关性较大,且在垂直极化通道上的相关性较在水平极化上大;不同土地覆盖类型,与MODIS_LST相关性较大所对应的AMSR-E微波通道不同。同时,考虑混合像元问题对相关性的影响,对25种不同地物类型组合下MODIS_LST与AMSR-E-BT的相关性进行统计分析,发现混合像元中地物类型越多,则二者相关性越小。最后,采用多元线性回归分析法,根据不同土地覆盖类型建立反演回归模型,对部分研究区域MODIS-LST进行反演,误差平均在±3.15 K以内,与不考虑下垫面覆盖的模型比较,反演MODIS_LST精度平均提高了1.5 K。  相似文献   

基于链接分析的网页文本核心地名提取方法     

钟翔  高勇  邬伦 《地球信息科学学报》2016,18(4):435-442

本文围绕互联网中网页文本蕴含的丰富地理空间信息,抽取网页文本中蕴含的地名实体,提出了一种地名共现网络模型,该模型综合考虑网页中地名的频次信息,表达网页文本中地名的共现及联系传递特征。在此基础上,提出一种基于链接分析的网页文本核心地名的提取方法,通过PageRank算法计算每个地名在共现网络中的链接权重,对网页文本构建的共现地名网络进行核心地名的提取,从而在庞大的网络资源中发现具有显著的焦点特征或导航枢纽特征的重要地名。最后,采用人民日报与新浪新闻体育版2份语料进行实验验证,证明了该方法的有效性。  相似文献   

Equipartitioning is not sufficient for Green's function extraction          下载免费PDF全文

Roel Snieder  Yuanzhong Fan  Evert Slob  Kees Wapenaar 《地震科学（英文版）》2010,23(5):403-415

The extraction of the Earth's Green's function from field fluctuations is a rapidly growing area of research.The principle of Green's function extraction is often related to the requirement of equipartitioning,which stipulates that the energy of field fluctuations is distributed evenly in some sense.We show the meaning of equipartitioning for a variety of different formulations for Green's function retrieval.We show that equipartitioning is not a sufficient condition,and provide several examples that illustrate this point.We discuss the implications of lack of equipartitioning for various schemes for the reconstruction of the Green's function in seismology.The theory for Green's function extraction is usually based on a statistical theory that relies on ensemble averages.Since there is only one Earth,one usually replaces the ensemble average with a time average.We show that such a replacement only makes sense when attenuation is taken into account,and show how the theory for Green's function extraction for oscillating systems can be extended to incorporate attenuation.  相似文献   

Retrieving soil water contents from soil temperature measurements by using linear regression     

Qin XU  Binbin ZHOU 《大气科学进展》2003,20(6):849-858

A simple linear regression method is developed to retrieve daily averaged soil water content from diurnal variations of soil temperature measured at three or more depths. The method is applied to Oklahoma Mesonet soil temperature data collected at the depths of 5, 10, and 30 cm during 11-20 June 1995. The retrieved bulk soil water contents are compared with direct measurements for one pair of nearly collocated Mesonet and ARM stations and also compared with the retrievals of a previous method at 14 enhanced Oklahoma Mesonet stations. The results show that the current method gives more persistent retrievals than the previous method. The method is also applied to Oklahoma Mesonet soil temperature data collected at the depths of 5, 25, 60, and 75 cm from the Norman site during 20-30 July 1998 and 1-31 July 2000. The retrieved soil water contents are verified by collocated soil water content measurements with rms differences smaller than the soil water observation error (0.05m~3 m~(-3)). The retrievals are  相似文献   

《大气、水灾害科技文献目录》检索系统     

贺盛瑜  易正亨 《成都信息工程学院学报》1996,(3)

论述了《大气、水灾害科技文献目录》检索系统的数据来源、研制方式、文献分类和著录及社会效益  相似文献   

Analysis of changes in the Arctic polynya based on AMSR-E remote-sensing data          下载免费PDF全文

Xie Xiaolei  Wei Yongliang  Zhang Yu 《极地研究》1988,31(2):179

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基于多进制小波变换的渐进式纹理图像检索     

程起敏  杨崇俊  邵振峰 《武汉大学学报(信息科学版)》2005,30(6):521-524

提出了一种基于多进制小波变换的渐进式纹理图像检索方法，纹理图像的特征通过多进制小波分解结果来描述，用低频子图小波系数标准方差和多进制小波直方图结合相应的相似性距离函数，实现目标图像数据库由粗到精的渐进式检索。通过Bordatz和USC纹理图像数据库来检验本方法的精度和效率，获得了较理想的试验结果。  相似文献   

双多普勒天气雷达反演大气三维风场的个例研究   总被引：7，自引：3，他引：7  

古金霞  顾松山  陈钟荣  裴宇杰 《南京气象学院学报》2005,28(6):833-839

根据笛卡尔坐标系下双多普勒天气雷达反演大气三维风场的理论，以2003年7月5日发生在安徽省的一次强降水过程为例，反演大气三维风场。结果表明：利用双多普勒天气雷达反演大气风场能够更加详细地反映出大气风场的三维结构。  相似文献   

A Study on Retrieving Atmospheric Profiles from EOS/AIRS Observations   总被引：5，自引：0，他引：5  

GUAN Li  ALLEN Huang  LI Jun 《Acta Meteorologica Sinica》2005,19(1):112-119

1. IntroductionThe development of global climate and weathermodels requires accurate monitoring of atmospherictemperature and moisture profiles, as well as the con-tents of trace gases and aerosols. It is quite difficultto monitor continuously these parameters on a globalscale.Until recently. AIRS (Atmospheric InfraredSounder) offers a new opportunity to improve globalmonitoring of temperature, moisture, and ozone distri-butions and changes therein. The high spectral resolu-tion (v/Δv ? 12…  相似文献   

Dynamical and Microphysical Retrieval from Simulated Doppler Radar Observations Using the 4DVAR Assimilation Technique   总被引：3，自引：0，他引：3  

XU Xiaoyong  LIU Liping  ZHENG Guoguang 《Acta Meteorologica Sinica》2005,19(2):160-173

Based on a cloud model and the four-dimensional variational (4DVAR) data assimilation method developed by Sun and Crook (1997), simulated experiments of dynamical and microphysical retrieval from Doppler radar data were performed. The 4DVAR data assimilation technique was applied to a cloud scale model with a warm rain parameterization scheme. The 3D wind, thermodynamical, and microphysical fields were determined by minimizing a cost function, defined by the difference between both radar observed radial velocities and reflectivities and their model predictions. The adjoint of the numerical model was used to provide the gradient of the cost function with respect to the control variables. Experiments have demonstrated that the 4DVAR assimilation method is able to retrieve the detailed structure of wind, thermodynamics, and microphysics by using either dual-Doppler or single-Doppler information. The quality of retrieval depends strongly on the magnitude of constraint with respect to the variables. Retrieving the temperature field, cloud water and water vapor is more difficult than the recovery of the wind field and rainwater. Accurate thermodynamic retrieval requires a longer assimilation period. The inclusion of a background term, even mean fields from a single sounding, helped reduce the retrieval errors. Less accurate velocity fields were obtained when single-Doppler data were used. It was found that the retrieved velocity is sensitive to the location of the retrieval domain relative to the radars while the other fields have very little changes. Two radar volumetric scans are generally adequate for providing the evolution, although the use of additional volumes improves the retrieval. As the amount of the observations decreases, the performance of the retrieval is degraded. However, the missing observations can be compensated by adding a background term to the cost function. The technique is robust to random errors in radial velocity and calibration errors in reflectivity. The boundary conditions from the dual-Doppler synthesized winds are sufficient for the retrieval. When the retrieval is mainly controlled by the observations in the regions away from the boundaries, the simple boundary conditions from velocity azimuth display (VAD) analysis are also available. The microphysical retrieval is sensitive to model errors.  相似文献