Performance assessment of a GCM land surface scheme using a fine‐scale calibrated hydrological model: an evaluation of MOSES for the Nile Basin     

Mohamed Ezzat Elshamy  Howard S. Wheater 《水文研究》2009,23(11):1548-1564

Land surface schemes (LSSs) represent the interface between land surface and the atmosphere in general circulation models (GCMs). Errors in LSS‐simulated heat and moisture fluxes can result from inadequate representation of hydrological features and the derivation of effective surface parameters for large heterogeneous GCM gridboxes from small‐scale observations. Previous assessments of LSS performance have generally compared simulated heat and moisture fluxes to observations over a defined experimental domain for a limited period. A different approach has been evaluated in this study, which uses a fine‐resolution calibrated hydrological model of the study basin to provide a quasi‐observed runoff series for direct comparison with simulated runoff from a selected LSS at GCM scale. The approach is tested on two GCM gridboxes covering two contrasting regions within the Nile Basin. Performance is mixed; output from the LSS is generally compatible with that of the fine‐resolution model for one gridbox while it cannot reproduce the runoff dynamics for the other. The results also demonstrate the high sensitivity of runoff and evapotranspiration to radiation and precipitation inputs and show the importance of subtle issues such as temporal disaggregation of climatic inputs. We conclude that the use of a fine‐resolution calibrated model to evaluate a LSS has several advantages, can be generalized to other areas to improve the performance of global models and provides useful data that can be used to constrain LSS parameterizations. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Hindcast of the wave conditions along the west Iberian coast     

L. Rusu  P. PilarC. Guedes Soares 《Coastal Engineering》2008

This paper describes the development of a wave prediction system for the west Iberian coast. The implemented wave prediction system is based on two state-of-the-art spectral wave models, WAM for the ocean area and SWAN for the nearshore. However, because of its extended geographical space the SWAN model will include some generation effects in the coarse SWAN simulations, complemented by wave transformation effects near the coast. The system was validated by means of extended hindcast runs in various regions belonging to the continental Portuguese coastal environment, which were compared with buoy data, focusing on the extreme energetic events and both direct comparisons and statistical results are presented.  相似文献   

Comparative analysis of relationships between NLDAS‐2 forcings and model outputs     

Youlong Xia  Mike Ek  Helin Wei  Jesse Meng 《水文研究》2012,26(3):467-474

This study reports results from an analysis of the relationship between atmospheric forcing and model‐simulated water and energy fluxes for the North American Land Data Assimilation System Project Phase 2 (NLDAS‐2). The relationships between mean monthly precipitation and total runoff are stronger in the Sacramento (SAC) and variable infiltration capacity (VIC) models, which grew out of the hydrological community, than in the Noah and Mosaic models, which grew out of the soil‐vegetation‐atmosphere transfer (SVAT) community. The reverse is true for the relationship between mean monthly precipitation and evapotranspiration. In addition, surface energy fluxes in VIC are less sensitive to model forcing (except for air temperature) than those in the Noah and Mosaic model. Notwithstanding these general conclusions, the relationships between forcings and model‐simulated water and energy fluxes for all models vary for different seasons, variables, and regions. These findings will ultimately inspire a combination of SVAT‐type model energy components with hydrological model water components to develop a SVAT‐hydrology model to improve both evapotranspiration and total runoff simulations. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Spatial proximity of age-0 walleye pollock (Theragra chalcogramma) to zooplankton near the Pribilof Islands, Bering Sea, Alaska     

Swartzman  G.; Brodeur  R.; Napp  J.; Hunt  G.; Demer  D.; Hewitt  R. 《ICES Journal of Marine Science》1999,56(4):545-560

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华北晚古生代成煤环境与成煤模式多样性研究   总被引：23，自引：2，他引：23  

桑树勋  陈世悦  刘焕杰 《地质科学》2001,36(2):212-221

华北晚古生代聚煤盆地存在活动体系成煤环境和废弃体系成煤环境。前者的海相成煤环境主要为泻湖泥炭坪,陆相成煤环境以三角洲平原沼泽意义最大。晚石炭世至晚二叠世,海相为主的成煤环境逐渐被陆相为主的成煤环境所取代,由盆缘到盆内成煤环境总体呈环带状展布。成煤环境差异性影响了成煤特点,这些成煤特点成为识别海、陆相煤层的显著相标志。华北晚古生代聚煤盆地在时间上和空间上存在成煤模式的多样性,以陆表海滨岸成煤模式、废弃碎屑体系成煤模式和浅水三角洲成煤模式为主。  相似文献   

Which Models for Collocated Cokriging?   总被引：1，自引：0，他引：1  

Jacques Rivoirard 《Mathematical Geology》2001,33(2):117-131

When a target variable is sparsely sampled, compared to a densely sampled auxiliary variable, cokriging requires simplifications. In its strict sense, collocated cokriging makes use of the auxiliary variable only at the current point where the target variable is to be estimated; in the multicollocated form, it also makes use of the auxiliary variable at all points where the target variable is available. This paper looks for the models that support these collocated cokrigings, i.e., the models in which the simplification resulting from the collocated forms does not result in any loss of information. In these models, the cross-structure between the two variables is shown to be proportional to the structure of the auxiliary variable, not to the structure of the target variable as is often assumed (except, of course, when all structures are proportional). The target variable depends on the auxiliary variable and on a spatially uncorrelated residual. Collocated cokriging simplifies to the simple method, which consists in kriging this residual. The strictly collocated cokriging corresponds to the particular case where the residual has a pure nugget structure, but it is then reduced to the single regression at the target point. Except for this trivial case, there are no models in which strictly collocated cokriging is exactly a cokriging.  相似文献   

利用EOF相空间分析东亚梅雨旱涝长期过程的初步研究   总被引：11，自引：1，他引：11  

朱抱真  张瑞雪  林学椿 《大气科学》2001,25(6):817-826

利用非线性动力学中的相空间概念,分析了梅雨旱涝3～5年循环的长期过程.对全球热带850hPa的纬向风场距平所作的EOF,第1特征向量显示了Walker环流异常在赤道球圈上的分布;第2特征向量主要显示热带-副热带之间的环流异常的经向分布.在第1时间系数和第2时间系数所定义的2维相空间中,由相轨线分析,得到梅雨涝年主要集中于第2象限,而旱年则相对多在第4象限.说明梅雨旱涝年际变异的主导模态和热带大气环流的主要特征向量有着密切的关联.它们显示了以3～5年时间尺度的大气环流演变的长期特征性过程.  相似文献   

资源与环境模型标准文档库及其与GIS集成   总被引：20，自引：1，他引：20  

岳天祥 《地理学报》2001,56(1):107-112

论述了中国资源与环境模型标准文档库的结构和内容。通过研究总结数学模型及其研究现状发现，中国资源与环境模型标准文档库建设需要完善尚有缺陷的数学模型、创建尚缺少的数学模型；通过归纳现有数学模型与地理信息系统的现有集成方法发现，目前的集成方法不能满足区域可持续发展集成模型的需要，据此讨论了数学模型与地理信息系统有效集成需要深入研究的内容。最后，提出了通过大量案例研究，形成区域可持续发展集成模型和中国资源与环境模型标准文档库2个软件包的可行研究思路。  相似文献   

利用EOF作相空间拓展与有限区域大气系统混沌吸引子维数的确定     

朱育峰  彭永清等 《南京气象学院学报》1995,18(1):52-56

提出用自然正交函数分解的方法来开拓相空间，从而研究有限区域上大气系统的混沌性质。与利用时间滞后作漂移来开拓相空间方法相比较，前者充分保证了相空间各基矢量的正交性，弥补了后者只能对单点资料进行计算的不足。文中利用欧洲中期数值天气预报中心1980－1986年北半球亚洲地区的500hPa位势高度场逐日格点资料进行了EOF分解并计算得到了该地区大气系统的分维数为D＝6．2，从而表明，为支撑该地区大气系统的混沌吸引子至少应取7维系统或以7个变量才能作出描述。  相似文献   

地震学中非线性预测方法的初步研究   总被引：2，自引：0，他引：2  

石特临  郭大庆 《地球科学进展》1995,10(3):273-277

介绍了近年来地震预测学中非线性理论和非线性方法的研究趋势和最新研究进展。在非线性数学模型的研究中，较为成功地将非线性门限模型，指数模型、具有长程关联自回归模型等应用于地震的中期预测上，在分形研究上，明确地取代了以往的一些经验结果，使对地震的活动的经验统计关系上升到分形的理论，在研究地震的动力学机制中，以多滑块－弹簧模型为代表，模拟地壳上地震断层运动机制和事实，建立了粘滑摩擦情况下的参数动力学方程。  相似文献