Long-term comparisons of net radiation calculation schemes   总被引：1，自引：0，他引：1  

J. H. Kjaersgaard  R. H. Cuenca  F. L. Plauborg  S. Hansen 《Boundary-Layer Meteorology》2007,123(3):417-431

Six commonly used models for calculating daily net radiation were tested against measured net radiation. Meteorological data from 32 and 7 consecutive years obtained at two temperate sites were used. The extensive duration of the datasets ensured that all weather conditions and extreme events were captured. A set of statistical procedures was used to evaluate the performance of the models. The mean bias errors ranged from 0.0 W m⁻² to 24.8 W m⁻² and 0.1–24.7 W m⁻² and root mean square error from 11.0 W m⁻² to 28.1 W m⁻² and 10.0–27.9 W m⁻² at the two sites respectively, for days without snow cover on the ground. The best agreement was found when locally calibrated model coefficients were used. Only negligible differences in model performances were found between the two sites and the differences were lower than the inaccuracies of the net radiation instruments used. Including days with snow cover in the analysis lead to a slight increase in the bias and scatter of the predictions. Model performances were in general better during summertime than wintertime. Altered albedo values during winter caused by generally low sun angles were likely the cause of this. Analysis showed that at least 5 years of data were needed to obtain stable calibration coefficients for local calibration of the models. Based on the results from this study, and due to their physical background, two physical based models were recommended for calculating daily values of net radiation under temperate climate regimes. A simple adjustment of the calibration coefficients based on climate regime was suggested for these models.  相似文献   

大亚湾网箱养殖区生物-化学特性与营养状况的周日变化     

黄洪辉  王寓平 《广东海洋大学学报》2001,21(2):35-43

根据1998年11月对大亚湾大鹏澳网箱养殖区进行的定点24h连续水质监测资料,分析并讨论了该养殖区海水生物-化学各要素的垂直分布和周日变化规律,并用单项指标评价法和改进的营养状态质量指数(NQI)法,参照营养指数(E)对该网箱养殖区海水的营养状况进行了评价和研究.结果表明,各项要素的平均值大都是表层＞中层＞底层;周日变化主要受潮汐运动和海水中生物的节律性生理活动的综合影响;表层海水的富营养化率明显高于中层海水,其各单项指标处于中度一富营养状态,而中层和底层海水则分别处于贫一中度和贫-富营养状态;PO4-P相对较贫乏,为养殖区富营养化的最关键限制因素.  相似文献   

Electron density distribution and bond critical point properties for forsterite, Mg2 SiO4, determined with synchrotron single crystal X-ray diffraction data     

A. Kirfel  T. Lippmann  P. Blaha  K. Schwarz  D. F. Cox  K. M. Rosso  G. V. Gibbs 《Physics and Chemistry of Minerals》2005,32(4):301-313

A generalized X-ray scattering factor model experimental electron density distribution has been generated for the orthosilicate forsterite, using an essentially extinction and absorption free set of single crystal diffraction data recorded with intense, high energy synchrotron X-ray radiation (E=100.6 keV). A refinement of the model converged with an R(F)=0.0061. An evaluation of the bond critical point, bcp, properties of the distribution at the (3, –1) stationary points for the SiO and MgO bonded interactions, yielded values that agree typically within ~5%, on average, with theoretical values generated with quantum chemical computational strategies, using relatively robust basis sets. On the basis of this result, the modeling of the experimental distribution is considered to be adequate. As the bcp properties increase in magnitude, the MgO and SiO bonds decrease in length as calculated for a number of rock forming silicates. As asserted by Coppens (X-ray charge densities and chemical bonding. Oxford University Press, Oxford, 1997), large negative ²(r_c) values, characteristic of shared interactions involving first row atoms, may not be characteristic of closed shell covalent bonded interactions involving second row Si, P and S atoms bonded to O. This study adds new evidence to the overall relatively good agreement between theoretical bcp properties generated with computational quantum strategies, on the one hand, and experimental properties generated with single crystal high energy synchrotron diffraction data on the other. The similarity of results not only provides a basis for using computational strategies for studying and modeling structures, defects and the reactivity of representative structures, but it also provides a basis for improving our understanding of the crystal chemistry of earth materials and the character of the SiO bonded interaction.  相似文献   

地震信息资源的开发利用     

梁凯利  赵小倩 《高原地震》2000,12(4):64-67

探索了网络环境下地震信息的开发利用,提出了加快发展的对策。  相似文献   

中国不同气候带各类型森林的生物量和净第一性生产力   总被引：27，自引：0，他引：27  

李高飞  任海 《热带地理》2004,24(4):306-310

根据<中国植被>的区划,将收集的全国984个样点的森林数据归并到5种气候带类型中,计算了各类型森林以及同一类型森林(分人工林和天然林)的生物量和净第一性生产力,还计算了不同气候带森林各器官的平均生物量和净第一性生产力.结果表明,从寒温带到热带各类型森林的生物量和净第一性生产力逐渐增加,天然林的生物量大于人工林生物量;除热带林外,人工林的净第一性生产力大于天然林净第一性生产力.  相似文献   

Production and respiration control the marine microbial metabolic balance in the eastern North Atlantic subtropical gyre     

María Aranguren-Gassis  Pablo SerretEmilio Fernández  Juan L. HerreraJose F. Domínguez  Valesca PérezJose Escanez 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(7):768-775

Two main contrasted hypotheses have arisen during the last decades about the factors controlling the planktonic net metabolic balance in oligotrophic waters: gross primary production controls net community production vs. variability of net community production is also influenced by changes in microbial respiration. This work discusses both hypotheses analyzing the variability of metabolic rates along a gradient from the margin to the centre of the North Atlantic oligotrophic gyre, i.e. from relatively productive to more oligotrophic conditions. Net community production (NCP) was close to zero (between −3.34 and −11.77 mmol O₂ m⁻² d⁻¹) at the margin of the gyre and tended towards net heterotrophy (−44.03 mmol O₂ m⁻² d⁻¹) to the centre of the gyre as both gross primary production (GPP) and community respiration (CR) decreased. The strong relationships found between nutrient availability and both NCP and GPP suggest that factors controlling GPP are prevalent in determining NCP variability in this biogeographic region. However implementation of existing models to predict NCP from the measured GPP indicates that the precise estimation of NCP in different oligotrophic systems requires consideration of the magnitude and variability of microbial respiration rates.  相似文献   

影响春季热带太平洋地区海温变化的动力热力作用分析     

赵鹤  颉卫华  吴统文  刘向文 《大气科学》2020,44(3):519-532

厄尔尼诺—南方涛动（ENSO）春季预报障碍是ENSO预测的一个难点问题,弄清影响春季热带太平洋地区海表温度（SST）变化的动力和热力作用对于理解ENSO关键区SST的异常变化及ENSO春季预报障碍成因非常重要。本文利用BCC-CSM2-MR数值模式,模拟产生一套1986～2017年间相互协调的逐月海表风应力、感热、潜热、长波和短波净辐射能量、海洋流场等观测代用数据。利用这些数据对影响海温变化的动力和热力作用及其相对重要性进行了诊断分析,结果表明:（1）与其他季节相比,春季Ni?o3.4区海洋表层温度（后文中用T_S表示）呈现出独特的先增暖后趋冷的不对称季节性转换特征,这一变化主要是由于影响T_S的大气风应力、海流以及能量净通量在春季均表现出明显的季节性转换过程。进一步的分析表明,热力作用对局地海温的季节性变化影响最为重要,水平平流输送以反向作用为主,其中经向平流输送起到了反向作用,不利于该区域T_S的季节性转变,纬向平流输送仅在春季转为弱的正贡献,浅层垂直平流输送对春季T_S变化的影响很小。（2）动力热力作用与T_S异常的变化倾向相关关系也表明,春季Ni?o3.4区热力作用与T_S异常变化呈现显著的正相关,纬向海流异常的输送项也表现为正相关,而经向海流输送项展现出由负相关向正相关转化的特征。（3）对Ni?o3.4区T_S变化的方差贡献分析结果表明,春季热力作用对T_S的异常变化的贡献达50%以上,相关系数超0.7,其次是纬向、经向平流项贡献,各占10%～20%左右,但两者作用相反,其他项贡献较小。  相似文献   

一种网元管理系统的设计     

张鼎兴  张波云  唐文胜  王树林 《广东海洋大学学报》2004,24(3):56-60

根据电信管理网络 (TMN)思想 ,提出一种网元管理系统的设计 ,该系统包含系统监测、性能分析、操作支持、故障管理、访问接口 5个功能。通过合理设计系统结构 ,利用网元管理器与网元Agent间的通信 ,旨在建立一个检测、控制和管理网元及为管理员提供一个友好的界面的系统 ,以提高网络管理水平。  相似文献   

基于ArcGIS Engine钻孔综合柱状图的实现     

张建永  刘朋涛  何冀华  谢迎春  梁春利 《测绘与空间地理信息》2015,(3):148-150

论述了基于ArcGIS Engine组件实现钻孔综合柱状图的自动生成和图形整饰的技术方法。图件包括文档及点、线、面三类要素,内容有表头、钻孔信息、伽玛曲线、地质描述、地层符号等。本文从图件自动创建过程中涉及的创建矢量文件、图形渲染、标注、MXD文档编辑等方面介绍了相应功能设计思路及实现过程。  相似文献   

平均热点参考基准的建立和岩石圈西向漂移的研究          下载免费PDF全文

朱新慧  孙付平  王刃 《地球物理学报》2013,56(8):2603-2612

对于大地测量应用来说,目前IERS机构在定义地球参考系时推荐采用岩石圈无整体旋转(No-Net-Rotation-NNR)约束条件,然而对于地球物理应用来说,相对于NNR参考基准的绝对板块运动数据可能会对地幔对流等研究结果产生误导.考虑到热点的运动,提出建立平均热点(MHS-Medial HotSpot)参考基准的方法,给出建立该基准的约束准则,分别以地学模型NNR-NUVEL1A和实测模型ITRF2005VEL为基础,建立了平均热点参考基准MHS-NUVEL1A和MHS-ITRF2005,并与其它基于热点的绝对板块运动模型进行了比较和分析;讨论了岩石圈的西向漂移,给出了岩石圈相对于下地幔整体旋转的更精确的定量估计,即基于实测的热点参考架MHS-ITRF2005和地学模型NNR-NUVEL1A之间的整体旋转为0.26°/Ma,旋转极在(50°S, 62°E),这与由板块的受力模型给出的岩石圈的整体旋转的旋转极很接近,旋转速率大致快了10%.  相似文献