遥感反演蒸散发的日尺度扩展方法研究进展

遥感技术能够提供卫星过境时刻地表参量的瞬时值,进而通过模型构建可反演得到瞬时蒸散发。相对于瞬时蒸散发,日尺度蒸散发在实际生产生活中具有更重要的应用价值。本文系统地总结分析了遥感反演瞬时蒸散发的代表性日尺度扩展方法,包括蒸发比不变法、解耦因子不变法、辐射能量比不变法、参考蒸发比不变法、地表阻抗不变法和数据同化法,并对各方法的基本原理、估算精度、适用性等进行了对比分析。在此基础上,进一步综述了日尺度扩展方法存在的不确定性和主要问题,包括扩展方法本身误差、云覆盖、气象数据获取、夜间蒸散发估算、遥感反演同扩展误差累积及真实性检验等,并指出今后应从加强有云天及夜间蒸散发扩展机理和方法等方面的研究来提升瞬时蒸散发日尺度扩展精度。     

CHINA: A COUNTRY OF THE THIRD WORLD OR THE THIRD GREAT POWER?

l.TheRapidEcono1ulcDevelopmentofCho1aSinceeconoAncreformandopen-doorpolicy,Cltinahasgrownrapidly.GDPinl993is3.4tilllesasmuChasti1atinl978.Annualgrowtlrateis9.2percent.li1ti1isresped,itisworthwniletostudyWhereChinaislocatedinti1eecononticltistoryoftheworld,andwhatthetrendofcurrentdeveoPmentwillChangeinto.Indevelopedcountriesofh1eWest,whentherateofecononhcdevelopmotwasthelligheSt,itwasnotltigherti1anthatofCltina'seconol11icdevelopmentafterreforl11andopen-doorpolicy.U.K.,forexample,Whichh…     

巢湖快速变化风浪场及其环境效应

浅水湖泊风浪过程对于湖泊生态系统具有重要的意义.基于巢湖风场、风浪和水环境参数同步高频观测结果,详细分析了快速变化风场下的风浪快速变化特征及其对湖泊水环境的影响特征.浅水湖泊风浪的有效波高和平均波周期均随风速的快速变化有较好的同步响应规律.在风速快速衰减阶段,相较有效波高,波周期有更好的稳定性.湖泊水体pH、水温、溶解氧会快速响应风浪的变化,随着风浪强度增强,对水体浊度、总磷浓度以及藻密度和生物量的扰动影响逐渐呈现.强烈的风浪扰动引起水体浊度变化的滞后时间可达3 d.快速变化的风浪场下,风浪的强烈扰动会改变水体固有的理化参数分布特征,扰动藻类常规的水体分布规律,风浪强度是造成差异的主要因子.     

中国古代状元分布的文化背景

状元籍贯的时空变化,在历史上有自北向南推移的趋势。唐中期以前状元主要出身于北方,南方籍状元很少。唐中期以后,南方籍状元数额逐渐增加,至明清时期形成绝对优势。状元籍贯地的时空变化主要受经济发展影响,我国古代经济中心南移决定教育文化中心也由北向南转移。此外首都的位置、考试制度的沿革对状元分布也有影响。状元籍贯地理分布反映我国文化与人才的历史地理特征,对今天中国的社会经济发展有深远的烙印。     

基于小波变换的沿海滩涂LIDAR影像降噪研究

LIDAR 数据的精度受到多种因素影响,选择合适的模型优化LIDAR影像,分离LIDAR观测数据与噪声,可有效提高LIDAR数据精度.本文研究基于小波变换的LIDAR影像降噪模型,并将小渡降噪与各种常规方法进行对比分析,选择客观评价指标比较各方法的降噪效果,认为小波变换法更适合LIDAR影像降噪,能保留更多的有效信息.     

Advances in Study of Phytolith Carbon Sequestration in Terrestrial Ecosystems of China

Phytolith-Occluded Carbon (PhytOC), a relatively stable carbon fraction, plays an important role in biogeochemical carbon cycle and mitigation of global warming. The formation mechanisms of PhytOC, the influence factors of phytolith carbon sequestration, the advances in study of phytolith carbon sequestration, and the management for enhancing the potential of phytolith carbon sequestration in terrestrial ecosystems of China were summarized in this review. Finally, future researches on phytolith carbon sequestration in terrestrial ecosystems of China were prospected. Climates, vegetation types, soil circumstances, the chemical compositions of the phytoliths and other factors will directly or indirectly affect the potential of phytolith carbon sequestration. In China, the PhytOC production quantity in grassland, cropland, forest, wetland and shrub ecosystems is (0.6±0.1)×10⁶,(4.9±1.7)×10⁶,(1.9±0.4)×10⁶,(0.6±0.5)×10⁶ and (1.3±0.3)×10⁶ t CO₂/a, respectively. Application of silicon-containing fertilizer, cultivation of high-silicon plant, and traditional enhancement of the plant net primary productivity can significantly improve the potential of phytolith carbon sequestration in terrestrial ecosystems of China. Future studies should focus more on ①the mechanisms of phytolith formation in different plants, ②the phytolith carbon sequestration in underground parts of plants from different terrestrial ecosystems, ③the quantification of soil PhytOC in different terrestrial ecosystems. Furthermore, more comprehensive, economical and reasonable management practices of improving the potential of phytolith carbon sequestration should also be further studied in different terrestrial ecosystems.     

Bioavailability and Interaction of Si and P in a Coastal Saline Soil Amended with Pig Slurry

The effects of widely applied organic waste amendment on soil Si and P bioavailability and their interaction have rarely been investigated. The study examined bioavailability and interaction of Si and P in response to pig slurry (PS) amendment in a coastal saline (CS) soil. The final purposes of the study are to assess fertilizer Si and P needs and to ensure environmental quality. The results show that PS amendment can cause accumulation of bioavailable Si in surface soil (0–20 cm), and significantly improve both soil bioavailable P content and soil P lability through PS‐Si and P input, and by the input of PS‐organic matter (OM) and enhancing the complexation of OM with soil Si and P. As a result of the Si‐P competitive sorption, Si shows a more rapid increase in bioavailability than P at the preliminary stage of PS amendment. However, under the weakly alkaline conditions as a result of relatively long term PS amendment, the fixation capacity of Si by soil solid components increases causing a rapider decline of Si bioavailability than that of P.     

基于布谷鸟算法的遥感影像智能分类

提出了一种新的基于布谷鸟算法的智能式遥感分类方法。采用布谷鸟智能优化算法,自动搜索遥感影像各波段的最优阈值分割点,并定义各波段最优阈值分割点和影像分类目标类别的连线为布谷鸟的最佳解,构造以If-Then形式表达的遥感分类规则。将所提的基于布谷鸟算法的影像分类方法应用于ALOS影像分类中,并与蜂群智能遥感分类方法和See5.0决策树方法进行了对比分析。结果表明,布谷鸟智能遥感分类的总体精度和Kappa系数均比蜂群智能遥感分类和See5.0决策树方法更高,该智能遥感分类方法具有更好的分类效果。     

GIS空间数据水印信息隐藏与加密技术方法研究

提出了在GIS空间数据中隐藏标识数据生产单位版权以及用户使用权属的数字水印,并对其进行压缩、加密,以此来跟踪、抵制GIS空间数据产品的非法流通、非法复制,有效地保护数据生产单位的合法权益。运用本文方法已开发出了相应的应用软件,并已投入生产测试。