海洋中液-固界面作用的分形研究 Ⅱ.混合交换剂表面分维的加和性规律和非加和性规律研究

用SAXS方法验证了海洋化学液-固界面研究中一些混合交换剂体系的分维分别具有加和性和非加性规律。实验测得:针铁矿/蒙脱石、水锰矿/无定形氧化铁、δ-MnO_2/针铁矿、δ-MnO_2/无定形氧化铁等混合交换剂体系的表面分维对混合百分率具有线性加和性;而高岭石/无定形氧化铁、无定形氧化铁/蒙脱石、δ-MnO_2/蒙脱石、δ-MnO_2/氧化铁凝胶等混和交换剂具有非线性加和性。上述诸体系在海水介质中平衡一年后,SAXS测定的表面分维皆具有非线性加和性,或非线的程度有所增加。     

Regional Fluxes Of Momentum And Sensible Heat Over A Sub-Arctic Landscape During Late Winter

Based on measurements at Sodankylä Meteorological Observatory the regional (aggregated) momentum and sensible heat fluxes are estimated for two days over a site in Finnish Lapland during late winter. The forest covers 49% of the area. The study shows that the forest dominates and controls the regional fluxes of momentum and sensible heat in different ways. The regional momentum flux is found to be 10–20% smaller than the measured momentum flux over the forest, and the regional sensible heat flux is estimated to be 30–50% of the values measured over a coniferous forest.The regional momentum flux is determined in two ways, both based on blending height theory. One is a parameterised method, the other represents a numerical solution of an aggregation model. The regional sensible heat flux is determined from the theory of mixed-layer growth. At near neutral conditions the regional momentum flux can be determined independently of the regional sensible heat flux. At unstable conditions the two models become coupled.The information that is needed by the parameterised blending height method and by the mixed-layer evolution method in order to derive the regional fluxes of momentum and sensible heat can be obtained from radiosonde profiles of wind speed and temperature.     

Estimating tree canopy cover using harmonic regression coefficients derived from multitemporal Landsat data

The goal of this study was to evaluate whether harmonic regression coefficients derived using all available cloud-free observations in a given Landsat pixel for a three-year period can be used to estimate tree canopy cover (TCC), and whether models developed using harmonic regression coefficients as predictor variables are better than models developed using median composite predictor variables, the previous operational standard for the National Land Cover Database (NLCD). The two study areas in the conterminous USA were as follows: West (Oregon), bounded by Landsat Worldwide Reference System 2 (WRS-2) paths/rows 43/30, 44/30, and 45/30; and South (Georgia/South Carolina), bounded by WRS-2 paths/rows 16/37, 17/37, and 18/37. Plot-specific tree canopy cover (the response variable) was collected by experienced interpreters using a dot grid overlaid on 1 m spatial resolution National Agricultural Imagery Program (NAIP) images at two different times per region, circa 2010 and circa 2014. Random forest model comparisons (using 500 independent model runs for each comparison) revealed the following (1) harmonic regression coefficients (one harmonic) are better predictors for every time/region of TCC than median composite focal means and standard deviations (across times/regions, mean increase in pseudo R² of 6.7% and mean decrease in RMSE of 1.7% TCC) and (2) harmonic regression coefficients (one harmonic, from NDVI, SWIR1, and SWIR2), when added to the full suite of median composite and terrain variables used for the NLCD 2011 product, improve the quality of TCC models for every time/region (mean increase in pseudo R² of 3.6% and mean decrease in RMSE of 1.0% TCC). The harmonic regression NDVI constant was always one of the top four most important predictors across times/regions, and is more correlated with TCC than the NDVI median composite focal mean. Eigen analysis revealed that there is little to no additional information in the full suite of predictor variables (47 bands) when compared to the harmonic regression coefficients alone (using NDVI, SWIR1, and SWIR2; 9 bands), a finding echoed by both model fit statistics and the resulting maps. We conclude that harmonic regression coefficients derived from Landsat (or, by extension, other comparable earth resource satellite data) can be used to map TCC, either alone or in combination with other TCC-related variables.     

Forest change of China in recent 300 years

Based on historical documents, modern survey and statistics, as well as the result of predecessor studies, the trend and main process of forest dynamics are recognized. The forest area and forest coverage rates for each province of China from 1700 to 1949 are es-timated backward by every 50 years. Linking the result with modern National Forest Inventory data, the spatial-temporal dynamics of Chinese forest in recent 300 years (AD 1700–1998) is quantitatively analyzed. The study shows that in recent 300 years, the forest area in current territory of China has declined by 0.95×108 hm2 (or 9.2% of the coverage rate) in total, with a trend of decrease and recovery. Before the 1960s, there was a trend of accelerated de-scending. The forest area was reduced by 1.66×108 hm2 (or 17% of the coverage rate) in 260 years. While after the 1960s, there has been a rapid increase. The forest area increased by 0.7×108 hm2 (or 8% of the coverage rate) in 40 years. The study also shows that there is a significant spatial difference in the dynamics of forest. The amplitudes of increasing and de-creasing in western China are both smaller than the ones in eastern China. During the rapid declining period from 1700 to 1949, the most serious decrease appeared in the Northeast, the Southwest and the Southeast, where the coverage rate in most provinces dropped over 20%. In Heilongjiang Province, the coverage rate dropped by 50%. In Jilin Province, it dropped by 36%. In Sichuan Province and Chongqing Municipality, it dropped by 42%. In Yunnan Prov-ince, it dropped by 35%. During the recovery period 1949–1998, the western provinces, mu-nicipality and autonomous regions, including Ningxia, Gansu, Inner Mongolia, Si-chuan–Chongqing, Yunnan, Tibet, Xinjiang and Qinghai, etc, the increase rates are all below 5%, while the eastern provinces, municipality and autonomous regions (except Heilongjiang, Hubei, Jiangsu–Shanghai) have achieved an increase over 5%, among which the Guang-dong–Hainan, Guangxi, Anhui, Beijing–Tianjin–Hebei, Shandong, Henan, Zhejiang, and Fu-jian have an increase over 10%.     

时空混合调制型偏振干涉成像光谱仪数据处理研究

研究了基于Savart偏光镜的偏振干涉成像光谱仪在时空混合调制模式下图像形成、数据分布的特点,论证了视场补偿型偏振干涉成像光谱仪更适用于单色光条件下的时空混合调制工作模式,并提出了时空混合调制模式下数据采集与处理的基本原理及其需要注意的问题与解决方法.最后,应用这种方法对实验获取的干涉图进行了数据处理,并成功复原出了光谱.     

广西百色大王岭原始森林风景区气候条件分析

采用广西百色大王岭原始森林景区1976～1991年平均资料及2005-2008年该地自动气象监测站资料对景区旅游气象条件进行统计分析,结果表明：风景区气温适中,年温差振幅小,夏、冬温差5℃,夏季少有35℃以上的高温,年舒适指数等级在-1～1的最佳舒适期长达9个月;影响景区旅游活动的主要气象灾害有强降雨、寒害等。     

Timber production assessment of a plantation forest: An integrated framework with field-based inventory,multi-source remote sensing data and forest management history

Timber production is the purpose for managing plantation forests, and its spatial and quantitative information is critical for advising management strategies. Previous studies have focused on growing stock volume (GSV), which represents the current potential of timber production, yet few studies have investigated historical process-harvested timber. This resulted in a gap in a synthetical ecosystem service assessment of timber production. In this paper, we established a Management Process–based Timber production (MPT) framework to integrate the current GSV and the harvested timber derived from historical logging regimes, trying to synthetically assess timber production for a historical period. In the MPT framework, age-class and current GSV determine the times of historical thinning and the corresponding harvested timber, by using a “space-for-time” substitution. The total timber production can be estimated by the historical harvested timber in each thinning and the current GSV. To test this MPT framework, an empirical study on a larch plantation (LP) with area of 43,946 ha was conducted in North China for a period from 1962 to 2010. Field-based inventory data was integrated with ALOS PALSAR (Advanced Land-Observing Satellite Phased Array L-band Synthetic Aperture Radar) and Landsat-8 OLI (Operational Land Imager) data for estimating the age-class and current GSV of LP. The random forest model with PALSAR backscatter intensity channels and OLI bands as input predictive variables yielded an accuracy of 67.9% with a Kappa coefficient of 0.59 for age-class classification. The regression model using PALSAR data produced a root mean square error (RMSE) of 36.5 m³ ha⁻¹. The total timber production of LP was estimated to be 7.27 × 10⁶ m³, with 4.87 × 10⁶ m³ in current GSV and 2.40 × 10⁶ m³ in harvested timber through historical thinning. The historical process-harvested timber accounts to 33.0% of the total timber production, which component has been neglected in the assessments for current status of plantation forests. Synthetically considering the RMSE for predictive GSV and misclassification of age-class, the error in timber production were supposed to range from −55.2 to 56.3 m³ ha⁻¹. The MPT framework can be used to assess timber production of other tree species at a larger spatial scale, providing crucial information for a better understanding of forest ecosystem service.     

漳平市森林可燃物类型变化遥感动态监测

森林可燃物类型的空间分布是林火蔓延、灭火可视化建模与仿真中需要考虑的重要因素之一。在对森林可燃物类型划分的研究进行回顾的基础上,提出了考虑树种信息的分类方法。根据漳平市2003年小班图层中的优势树种信息,获得该市2003年四种森林可燃物类型即竹林、阔叶树、杉木林以及马尾松的空间分布专题图。在此基础上,采用面向对象分类技术,对ASTER影像进行分类,探测每种可燃物类型的内部变化和外部变化。该技术利用影像分割技术构建分类对象,使每个对象具有光谱信息的同时,具备大小、形状、拓扑关系、类别层次等诸多信息。对分类结果进行评价的结果表明,利用面向对象分类技术,充分利用了光谱特征以及类别相关特征,提高了分类精度,分类的面积精度达到89.3%。由于影像分割过程应用了专题图层,对象的边界不会超越专题图层的边界,使得对现有图层的更新尤为容易。最后,利用矢量格式的遥感分类结果对原森林小班图层进行更新,获得新的可燃物类型图层,作为林火可视化模型的输入图层。该研究不仅提供了现势性强的森林可燃物类型图层,而且在不破坏原小班边界的基础上,对发生变化的区域进行刻画。对于森林资源管理者,提供了实地调查过程的目标区域的信息。     

Stormflow generation in two headwater catchments in eastern Amazonia,Brazil

Throughout the tropics, and the Amazon region in particular, only a few experimental studies have identified the main hydrological pathways and response to storm events. This study identifies the hydrological response patterns and quantifies the main runoff generating processes for two headwater catchments in eastern Amazonia, an area of low relief. Over an 18 month study period, 245 and 55 rainfall–runoff events at the respective headwater catchments were analysed. The rainfall‐runoff regression lines for both catchments revealed a remarkably strong linear correlation between event rain total and runoff volume. The area contributing to stormflow was proven to be constant in extent at approximately 0·6% of the catchment and to coincide with the exact extent of the riparian wetland zone. The soils of the surrounding hillslopes were found to be highly permeable oxisols. Indications of secondary permeability due to the deep root system of the secondary vegetation were also found. Copyright © 2007 John Wiley & Sons, Ltd.