一种优化的对流层天顶延迟融合模型FZTD

对流层延迟是影响全球卫星导航系统(GNSS)定位精度的主要误差源之一,模型修正法是目前削弱对流层延迟影响的主要方法. 以简单易用的角度为切入点,综合UNB3模型的简易性和GPT2w模型的高精度特点,构建一种简易且精度较高的对流层天顶延迟融合模型(FZTD). 并利用多年的国际GNSS服务(IGS) 对流层天顶延迟(ZTD)数据对该模型精度进行了验证. 结果表明FZTD模型的均方根(RMS)与平均偏差(bias)值分别为4.4 cm和?0.3 cm,均小于传统模型UNB3m(RMS:5.1 cm,bias:1.1 cm)和EGNOS(RMS:5.1 cm,bias:0.3 cm),定位精度提高了14%,而且在南半球提高尤为明显,特别在南极地区,精度提高了近3倍,弥补了传统模型在南北半球精度差异大的不足. 新模型总气象参数仅为120个比GPT2w模型急剧减少,与传统模型相当,为GNSS实时导航定位终端的预定义对流层延迟改正提供了更优的选择.      

地形因子对反距离加权插值方法(IDW)最优距离指数的影响分析

反距离加权插值方法（Inverse Distance Weighted, IDW）是生成数字高程模型（Digital Elevation Model,DEM）的常用内插手段之一,不同的地形应使用合适的IDW距离指数进行插值。本文选取了平原、丘陵、小起伏山地、中起伏山地和大起伏山地5种地形,设计了2组试验,从地形宏观形态和地形微观形态2个方面研究了地形对IDW插值中最优距离指数（Optimal order of distances,OOD）的影响。首先使用狼群算法（Wolf pack algorithm,WPA）计算不同地形区下IDW插值的OOD,分析不同地形之间OOD的分布差异;其次选取坡度、坡向、曲率3个地形因子,计算各采样点的OOD,分析不同地形因子对采样点OOD的影响。结果表明,从平原地区到大起伏山地地区,随着区域内地形起伏度的增加,OOD减小。采样点的OOD在高值区的占比随坡度增大而减小;OOD随坡向变化差异不大;随着地形曲率的增大,OOD在高值区的占比增加,在低值区的占比减小。在较为平坦的地区,例如平原地区,丘陵地区建议使用OOD在3≤a≤4范围内取值进行IDW插值,而在小起...     

南极气象资料处理查询与统计系统的建立与应用

中国南极长城站自1985年成立至今,已经积累了近30年的气象观测数据,这些数据是研究南极和全球气候变化的重要依据。基于多种原因,数据中存在的不规范和错误,影响了其使用价值。在第29次南极长城站考察期间,建立气象资料审核纠错、查询统计等多功能南极气象资料处理系统,应用该系统对长城站的历史气象数据进行处理,实现了南极气象资料的共享。     

Variation of surface temperature during the last millennium in a simulation with the FGOALS-gl climate system model

A reasonable past millennial climate simulation relies heavily on the specified external forcings, including both natural and anthropogenic forcing agents. In this paper, we examine the surface temperature responses to specified external forcing agents in a millennium-scale transient climate simulation with the fast version of LASG IAP Flexible Global Ocean-Atmosphere-Land System model (FGOALS-gl) developed in the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP). The model presents a reasonable performance in comparison with reconstructions of surface temperature. Differentiated from significant changes in the 20th century at the global scale, changes during the natural-forcing-dominant period are mainly manifested in the Northern Hemisphere. Seasonally, modeled significant changes are more pronounced during the wintertime at higher latitudes. This may be a manifestation of polar amplification associated with sea-ice-temperature positive feedback. The climate responses to total external forcings can explain about half of the climate variance during the whole millennium period, especially at decadal timescales. Surface temperature in the Antarctic shows heterogeneous and insignificant changes during the preindustrial period and the climate response to external forcings is undetectable due to the strong internal variability. The model response to specified external forcings is modulated by cloud radiative forcing (CRF). The CRF acts against the fluctuations of external forcings. Effects of clouds are manifested in shortwave radiation by changes in cloud water during the natural-forcing-dominant period, but mainly in longwave radiation by a decrease in cloud amount in the anthropogenic-forcing-dominant period.     

Asymmetry of surface climate change under RCP2.6 projections from the CMIP5 models

The multi-model ensemble (MME) of 20 models from the Coupled Model Intercomparison Project Phase Five (CMIP5) was used to analyze surface climate change in the 21st century under the representative concentration pathway RCP2.6, to reflect emission mitigation efforts. The maximum increase of surface air temperature (SAT) is 1.86°C relative to the pre-industrial level, achieving the target to limit the global warming to 2°C. Associated with the “increase-peak-decline” greenhouse gases (GHGs) concentration pathway of RCP2.6, the global mean SAT of MME shows opposite trends during two time periods: warming during 2006–55 and cooling during 2056–2100. Our results indicate that spatial distribution of the linear trend of SAT during the warming period exhibited asymmetrical features compared to that during the cooling period. The warming during 2006–55 is distributed globally, while the cooling during 2056–2100 mainly occurred in the NH, the South Indian Ocean, and the tropical South Atlantic Ocean. Different dominant roles of heat flux in the two time periods partly explain the asymmetry. During the warming period, the latent heat flux and shortwave radiation both play major roles in heating the surface air. During the cooling period, the increase of net longwave radiation partly explains the cooling in the tropics and subtropics, which is associated with the decrease of total cloud amount. The decrease of the shortwave radiation accounts for the prominent cooling in the high latitudes of the NH. The surface sensible heat flux, latent heat flux, and shortwave radiation collectively contribute to the especial warming phenomenon in the high-latitude of the SH during the cooling period.     

流域人地关系地域系统研究进展

随着人类对流域内各种资源开发强度的增大,流域内人地矛盾日益突出,对流域人地系统的研究成为焦点问题,系统总结了当前国内外流域人地系统研究在理论、观点、方法与实践等方面取得的最新进展,指出了当前该领域研究的薄弱环节,并展望了未来主要的研究方向.研究认为,国际学者普遍关注流域发展规划与管理的研究,研究内容涉及流域发展规划和管...     

沂源县大力提高土地节约集约利用水平

为落实国家节约集约用地的有关规定，沂源县国土资源局在建设用地审批工作中，严格按照《山东省禁止、限制供地项目目录及建设用地集约利用控制标准》和沂源县《严格工业项目建设用地集约利用控制标准和提高土地使用效益的通知》要求，加强用地预审，严格控制各类建设用地增量，积极盘活存量，把节约集约用地放在首位，[第一段]     

Development on management and sharing of data collected in Chinese Antarctic and Arctic Research Expeditions

Combined with the current status of Antarctic data management and the characteristics of polar science data resulted from Chinese Antarctic and Arctic Research Expeditions, the Chinese Polar Science Database System(CPSDS) has been designed and established in 2002. The infrastructure, technical standard, mechanism of sharing data of this system are reviewed in this article. Meanwhile, the development of Chinese polar data management is summarized. As the metadata is the powerful and useful tool for managing and disseminating scientific data, the metadata is also used as “search engine“ of CPSDS. Besides, the trend of data management and sharing is also discussed.     

赣南地区土壤硒元素地球化学特征及其影响因素研究：以青塘—梅窖地区为例

以赣南青塘—梅窖地区为典型区开展详细的调查研究工作,共采集了表层(0~20 cm)土壤样品889件,农作物样品72件。系统地分析了土壤及农作物中硒元素含量的空间分布特征及其与成土母质、土地利用类型和土壤理化性质的关系。结果表明：研究区土壤硒平均含量为044 mg·kg-1,其中面积比例为4859%的土壤硒含量处于足硒状态,面积比例为4286%的土壤硒含量处于富硒状态。在空间分布上,缺硒和潜在硒不足土壤仅呈零星分布。表层土壤硒含量在一定程度上继承了成土母质硒的含量,不同的土地利用类型土壤中硒含量也存在一定的差异。土壤有机质含量与硒含量呈显著正相关关系,与土壤pH值没有相关性。花生和水稻富硒率较高,其中花生和早稻含量均符合国家食品安全标准,仅晚稻存在一定的重金属超标现象。通过对比富硒土壤和不富硒土壤中晚稻重金属含量的超标率、硒的富集系数和含量,发现在富硒区晚稻中重金属的超标率远远低于非富硒区,说明土壤硒元素会在一定程度上降低晚稻中重金属元素的富集效应。     

海底地震仪(OBS)主动源转换横波的应用

横波（S波）为偏振波,具有不同于纵波（P波）的特性,对于地震探测具有特殊的意义.在被动源地震探测中已得到广泛的应用,如接收函数、S波分裂等.在主动源（气枪）海底地震（OBS）探测中,震源在水中,S波为地层转换波,其应用还不多.本文在介绍转换S波的产生、模式、处理和识别的基础上,以实例为切入点简述其具体应用.这些应用主要是基于1D/2D转换S波,用于揭示海底岩石类型、推断地壳性质、共轭陆缘问题、判定地幔蛇纹石化、估算天然气水合物的饱和度和预测流体等.目前在南海已获得了大量的2D和3D的OBS转换S波数据,可将转换S波的研究逐步从2D发展到3D研究,同时结合其他地球物理资料进行共同分析.利用转换S波的研究,有利于揭示南海扩张停止后形成的海山下不同地层的岩性和判定上地幔低速的性质等.