Characterization of seasonal variation of forest canopy in a temperate deciduous broadleaf forest, using daily MODIS data

In this paper, we present an improved procedure for collecting no or little atmosphere- and snow-contaminated observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. The resultant time series of daily MODIS data of a temperate deciduous broadleaf forest (the Bartlett Experimental Forest) in 2004 show strong seasonal dynamics of surface reflectance of green, near infrared and shortwave infrared bands, and clearly delineate leaf phenology and length of plant growing season. We also estimate the fractions of photosynthetically active radiation (PAR) absorbed by vegetation canopy (FAPAR_canopy), leaf (FAPAR_leaf), and chlorophyll (FAPAR_chl), respectively, using a coupled leaf-canopy radiative transfer model (PROSAIL-2) and daily MODIS data. The Markov Chain Monte Carlo (MCMC) method (the Metropolis algorithm) is used for model inversion, which provides probability distributions of the retrieved variables. A two-step procedure is used to estimate the fractions of absorbed PAR: (1) to retrieve biophysical and biochemical variables from MODIS images using the PROSAIL-2 model; and (2) to calculate the fractions with the estimated model variables from the first step. Inversion and forward simulations of the PROSAIL-2 model are carried out for the temperate deciduous broadleaf forest during day of year (DOY) 184 to 201 in 2005. The reproduced reflectance values from the PROSAIL-2 model agree well with the observed MODIS reflectance for the five spectral bands (green, red, NIR₁, NIR₂, and SWIR₁). The estimated leaf area index, leaf dry matter, leaf chlorophyll content and FAPAR_canopy values are close to field measurements at the site. The results also showed significant differences between FAPAR_canopy and FAPAR_chl at the site. Our results show that MODIS imagery provides important information on biophysical and biochemical variables at both leaf and canopy levels.     

MODIS遥感数据产品处理流程与大气数据获取

MODIS是美国NASA的ESE计划中最重要的传感器。它具有36个通道，空间分辨率为250～1000m，是新一代的图谱合一的遥感仪器。它的数据在地球长期观测、地球环境监测、自然灾害监测方面具有广泛的应用前景和重大意义。本首先对EOS计划和MODIS仪器的特性进行概述，然后对MODIS的数据产品进行了介绍，再以大气为主，描述了MODIS原始数据到0级数据、1级、2级及更高级产品的处理流程和算法。重点介绍了由0级数据到2级数据的处理过程和IMAPP及其处理结果，并简要的把IMAPP的处理过程与DAAC的进行对比，最后对IMAPP的大气产品进行了详细说明。     

创新思维在英语课堂教学中的尝试

文章从三个方面阐释创新思维在英语教学中的尝试:以语感带动听说读写活动技能;通过多种思维训练,增强创新思维的能力;变"个人竞争"为"小组合作",创造有利于创新思维的发展的空间。     

城市名片——由水墨西湖而感

在日益城市化进程的中国,探索如何打造好城市特色名片,对开启城市学思考与研究具有十分重要的意义。该文针对城市规划专业学生,如何有系统、有步骤、有条理地进行积累、分析、学习和设计、研究有重要的启发作用。     

工业化生产高品质清远鸡白切鸡

在总结传统加工工艺的基础上，对工业化生产高品质清远鸡白切鸡的工艺路线、基本技术参数、关键设备及工作原理进行了描述。并探讨了规模生产清远鸡白切鸡的技术要点及存在的问题。     

网带式电阻炉中控制气氛的配置

在网带式电阻炉的设计中,气氛的配置是否合理,气氛的配比和入口位置的选择,直接影响炉内气氛的合理性和工件的质量。基于10多年的电阻炉调试经验,介绍在电阻炉的设计中控制气氛的合理配置。     

微波斜径传播对流层大气湍流结构常数模型

在微波遥感和卫星通信领域内，对流层湍流大气引起的信号闪烁现象的研究是至关重要的一个问题。引起接收信号闪烁的大气折射率起伏一般由大气结构常数(Cn^2来度量。根据ITU—R光波波段的Cn^2模型及ITU—R幅度闪烁标准偏差σχ的经验模型讨论了在微波波段影响Cn^2的主要因素；建立了微波波段的Cn^2模型。其优点是考虑了大气温度和湿度随高度的变化。根据湍流的幅度闪烁理论，在频率分别为12GHz，20GHz和30GHz时，用该Cn^2模型计算了σχ，并与ITU—R和Ortgies模型的预测结果进行了比较，结果表明一致性较好，说明该Cn^2模型是实用的。     

机载海洋激光雷达的试验研究

通过对我国首次机载激光水下目标探测试验数据的分析和处理，并辅之以必要的蒙特卡模拟实验，就有效衰减系数，大气，风速，海水分层，目标倾斜等因素对雷达系统性能的影响进行了研究，首次总结出适合工程设计使用的近似估算公式和曲线，阐述了试验中出现的异常现象，并给出了合理的解释，最后还提出了一些需要进一步深入研究的关键问题。     

艺境空间 后期创造

本文就家居装修应如何营造艺术氛围,提出了家装前期简单、后期深入的概念。     

Peculiarities of chemical elements accumulation by epiphytic moss Pylaisia polyantha (Hedw.) B.S.G. in varying natural environments of West Siberia

This study explores the influence of natural environment on the content of chemical elements in the epiphytic moss Pylaisia polyantha, picked from six areas remote from industrial centres in Siberia. The neutron activation analysis determined concentrations of 25 chemical elements (mostly heavy metals). According to correlation analysis, none of the climatic variables (i.e. temperature, precipitation and airflow direction) is separately significant for the accumulation of the examined chemical elements by the moss. The concentrations of chemical elements in mosses picked in different plant subzones or belts definitely vary. This means that the environment characteristic of plant subzones or belts and phytocenosis types influence the accumulation of chemical elements in the moss. The sample selection area belongs to a certain plant subzone or belt and this reflects the overall influence of climatic and other ecological factors. However, phytocenosis properties (i.e. stand thickness, canopy density degree, etc.) impact the concentration of chemical elements in the epiphytic moss primarily due to the sunshade effect.