Development of an integrated vertical-slantwise convective parameterization scheme and its associated numerical experiments

An integrated vertical-slantwise convective parameterization scheme, based on the vertical Kuo-Anthes and the slantwise Nordeng convective parameterization schemes, is introduced into the MM5 model. By employing the MM5 model with the proposed scheme, numerical simulations of a snowstorm event that occurred over southern China on 28-29 January 2008 and of Typhoon Haitang (2005) are conducted. The results indicate that during the snowstorm event, the atmosphere was convectively stable in the vertical directi...     

IAP AGCM4.0模式对热带大气季节内振荡的模拟评估

基于中国科学院大气物理所大气环流模式IAP AGCM4.0总共30年(1979~2008年)的模拟结果,评估了IAP AGCM4.0模式对热带大气季节内振荡的模拟能力。分析结果表明IAP AGCM4.0模式可以在一定程度上模拟出热带大气季节内振荡的主要时空谱结构特征,在周期30~80天处存在明显的谱能量中心;模式模拟的季节内振荡东传的主要特征与观测基本一致,东移波的能量远大于西移波。基于RMM指数(All-season Real-time Multivariate MJO Index)的分析表明,模式模拟的850 h Pa和200 h Pa季节内尺度风场和对流活动在赤道地区的空间分布与观测基本一致。但与观测相比,模式模拟的热带大气季节内振荡的周期较短,东传速度快于观测,虚假的西传特征过强,对流活跃区域范围较小、强度较弱。就非绝热加热而言,模式模拟结果与再分析资料比较接近,但最大加热在印度洋和西太平洋地区出现的位相较晚。进一步分析表明,模式中影响对流触发的相对湿度阈值(RHc)的不同取值(RHc分别取为85%、90%、95%和100%),可以显著影响热带大气非绝热加热垂直廓线,从而影响模式对热带大气季节内振荡的模拟;当对流触发相对湿度阈值取为90%时,IAP AGCM4.0模式对热带大气季节内振荡模拟的能力相对最好,非绝热加热垂直廓线在不同位相的分布特征也与再分析资料最为接近。这说明模式对流参数化方案中不同参数的合适选取,可以改进模式对热带大气季节内振荡的模拟能力。     

Comparison between TVD-MacCormack and ADI-type solvers of the shallow water equations

A total variation diminishing (TVD) modification of the MacCormack scheme is developed for simulating shallow water dynamics on a uniform Cartesian grid. Results obtained using conventional and deviatoric forms of the conservative non-linear shallow water equations (SWEs) are compared for cases where the bed has a varying topography. The comparisons demonstrate that the deviatoric form of the SWEs gives more accurate results than the conventional form, in the absence of numerical balancing of the flux-gradient and source terms. A further comparison is undertaken between the TVD-MacCormack model and an alternating direction implicit (ADI) model for cases involving steep-fronted shallow flows. It is demonstrated that the ADI model is unable to predict trans-critical flows correctly, and artificial viscosity has to be introduced to remove spurious oscillations. The TVD-MacCormack model reproduces all flow regimes accurately. Finally, the TVD-MacCormack model is used to predict a laboratory-scale dyke break undertaken at Delft University of Technology. The predictions agree closely with the experimental data, and are in excellent agreement with results from an alternative Godunov-type model.     

Optimization and rationalization of karst groundwater resource in Feicheng Basin,China

Feicheng Basin is an important energy base in Shandong Province, China. The Ordovician limestone is the main aquifer for water supply in the basin. As a result of the current practice in which individual water users control the exploitation of the karst water, the regional groundwater level has dropped more than 30 m over the last 20 years. The groundwater is overdrawn in approximately 300 km² because of the poor management from 1981. A numerical model with distributed parameters is developed for the karst aquifer to help properly manage the water resource and sustain its utilization. The responding matrix method is used to couple the prediction model and the management model. The objective of the modeling exercises is to obtain the maximum amount of water while keeping the water level drawdown within an acceptable level. The optimum management scheme is selected among two proposed designs. The recommended measures from this study include (1) improvement of water use efficiency in industries, (2) comprehensive utilization of the water pumped from the mines, and (3) improvement of the irrigation practice. When the domestic water supply and corporates water demand take the top priorities, the numerical modeling provides a useful tool to help with the rational distribution of the karst water resources among different water users.     

关于矩阵A~(-1)B的一个注记

本文讨论了对求解差分方程有用的矩阵A~(-1)B的范数。胡家赣曾于1983年给出一个关于‖A~(-1)B‖的估计的定理。然而,这里给出一个比原来的证明更为简单的新的证明。     

Response Surface Designs for Scenario Management and Uncertainty Quantification in Reservoir Production

Response surface experimental designs provide a framework for evaluating sensitivities and assessing uncertainties in reservoir-production forecasts for continuous parameters (i.e. permeability, flow rate, etc.). In this paper, the method is extended in order to integrate both continuous and discrete parameters (i.e. fault status: open/close, injection scheme: SWAG/WAG, etc.). This paper presents an appropriate experimental designs approach, notably the regression models associated with, and the statistical interpretation (sensitivity study, Monte Carlo simulations, etc.). The method has been successfully applied to a reservoir oil-production simulation problem. The objective was to define the best production scheme by optimizing the well-completion level. This application has highlighted the advantages of this new approach, both in terms of decreasing simulation cost and improving the interpretation quality.     

小尺度深凹地形PBL结构的数值模拟研究

本大建立了一个针对小尺度深凹地形（深凹露天矿）使用的三维非静力的诊断模式。模式中采用能量（E－）闭合方案，取细网络，具有甚高的空间分辨率。利用该模式充分分析了露天矿边界层的结构特征。数值试验的结果表明．初始地面风速，初始的风速垂直切变，露天矿的采深及边坡用的大小等因素对复环流有较大影响。     

三维过渡等参单元在岩土工程有限元分析中的应用

土石坝等复杂土工结构物有限元三维建模中多采用精度较高的六面体单元辅以部分过渡用的退化单元,而退化单元由于形态不好,会导致有限元计算精度较差。解决该问题的途径之一是采用过渡性的等参元。总结了几种常遇到的过渡等参单元（楔形体、四面体、金字塔）的插值函数和高斯积分局部坐标和权重,并编入了有限元程序。通过比较六面体单元和金字塔单元剖分理想土石坝的有限元计算结果,说明所引入的金字塔单元是满足精度要求的。将各种过渡单元应用于实际土石坝工程的有限元计算,结果表明,使用过渡等参单元是可以在一定程度上提高计算精度的。最后讨论了二次单元在弹塑性有限元动力计算中的应用。二次单元的使用,可以改善动力计算中的超静孔压分布,提高计算精度。     

Quantifying ice storage in upper Indus river basin using ground-penetrating radar measurements and glacier bed topography model version 2

Ice reserve estimates is a fundamental prerequisite for water resources management. We selected the UIB (upper Indus river basin) as study area because it contains the most abundant mid-latitude glaciers outside the polar region, however, the ice reserve estimates remain unclear due to the harsh topography. In this study, we validated the parameters of the GlabTop2 model (Glacier Bed Topography version 2) using the ice thickness measured by GPR (ground-penetrating radar) and compared the “GPR-measured ice thickness and ice bed elevation” versus “the estimated results obtained from GlabTop2.” Integrated with IDW (inverse distance weighted) interpolated results of glaciers of various sizes, a reasonable parametric scheme (τ = 120 kPa and f = 0.8) of GlabTop2 was applied on vast amounts of glaciers in the UIB region. The GlabTop2 estimates indicated that the ice thickness of the UIB varied from 0 to 736.0 ± 110.0 m, with an average value of 74.5 ± 11.2 m. A significant spatial heterogeneity exists in the sub-basins. The Shyok, Shigar and Hunza that contain the most abundant ice reserve. Lesser quantities are stored in the Western Himalaya and Hindu Kush ranges, which account for 11.3 % and 6.7 % of the total ice reserve in the UIB, respectively. A total volume of 1162.4 ± 175.1 km³ of glacier can be converted to 1046.2 ± 157.6 Gt ice reserve; this is 13.6 times the annual average discharge obtained from the outlet of the Besham hydrological station. We aim to present estimates that can provide the baseline information for glaciology study of the Indus river.     

输出道成像方式的共反射面元叠加方法I——理论

共反射面元（Common Reflection Surface）叠加是一种独立于宏观速度模型的零偏移距成像方法,该方法属于典型的克希霍夫型成像方法. 根据成像方式的不同,克希霍夫型成像方法可以分为两大类：输出道成像方式和输入道成像方式. 考察共反射面元叠加方法,它属于输入道成像方式. 本文基于理论模型数据,实现了输出道成缘方式的CRS叠加方法. 相比传统的输入道成像方式,它具有能够保证大偏移距反射信息的成像精度和计算效率较高的优点,而且更加容易推广到三维情形.