试谈大区系统500kV电网远景结构

500kV电压是国内多数大区系统的最高电压等级,500kV电网的安全和短路电流是大区系统规划中的2个重要课题。文中从500kV电网结构出发,提出一些对大区系统安全可靠供电有帮助的看法和2种500kV电网结构模式,以供规划参考。以利近期电网与远期目标电网相结合,形成一个能进一步提高500 kV电网供电可靠性和有利于限制短路电流的目标网架。

大区互联系统稳定计算中负荷模型研究

针对我国大区电网互联后稳定计算中出现的新情况,通过采用不同负荷模型对我国3个大区互联系统重要输电断面稳定极限的计算比较,详细分析稳定计算中马达挂在不同电压等级、配电网不同模拟方法对马达特性及稳定计算结果的影响,指出我国有些网调长期采用的马达模型存在定子漏抗过大的问题,建议现阶段采用IEEE-6马达模型,或者采用国内提出并计算出的稳定特性和稳定水平与之比较接近的研究马达模型或综稳Ⅲ型马达模型。

An Ocean Reanalysis System for the Joining Area of Asia and Indian-Pacific Ocean

An ocean reanalysis system for the joining area of Asia and Indian-Pacific Ocean (AIPO) has been developed and is currently delivering reanalysis data sets for study on the air-sea interaction over AIPO and its climate variation over China in the inter-annual time scale.This system consists of a nested ocean model forced by atmospheric reanalysis,an ensemble-based multivariate ocean data assimilation system and various ocean observations.The following report describes the main components of the data assimilation system in detail.The system adopts an ensemble optimal interpolation scheme that uses a seasonal update from a free running model to estimate the background error covariance matrix.In view of the systematic biases in some observation systems,some treatments were performed on the observations before the assimilation.A coarse resolution reanalysis dataset from the system is preliminarily evaluated to demonstrate the performance of the system for the period 1992 to 2006 by comparing this dataset with other observations or reanalysis data.

Simulated seasonal variations in nitrogen wet deposition over East Asia

The regional air quality modeling system Regional Atmospheric Modeling System–Community Multiscale Air Quality was applied to estimate the spatial distribution and seasonal variation in nitrogen wet deposition over East Asia in 2010. The simulated results were evaluated by comparing modeled precipitation rates and ion concentrations, such as ammonium（NH_4~＋）, nitrate（NO_3^-）, and sulfate, in rainwater, against observations obtained from Acid Deposition Monitoring Network in East Asia and meteorological stations in China. Comparison of simulated and observed precipitation showed that the modeling system can reproduce seasonal precipitation patterns reasonably well. For major ion species, the simulated results in most cases were in good agreement with those observed. Analysis of the modeled wet deposition distributions indicated that China experiences noticeable variation in wet deposition patterns throughout the year. Nitrogen wet deposition（NH_4~＋ ＋ NO_3^-） during summer and spring accounted for 71% of the annual total（3.9 Tg N yr^（-1））, including 42.7% in summer. Precipitation plays a larger role in the seasonal variation of wet deposition; whereas, aerosol concentrations affect its distribution patterns. In China, the amount of annual nitrogen wet deposition ranged from 1 to 18 kg N ha^（-1）. Nitrogen in wet deposition was mainly in the form of NH_4~＋, accounting for 65.76% of the total amount, and the molar ratio of NH_4~＋∕NO_3^- was mostly more than 1, indicating a relatively larger effect from agricultural activities.

Modeling Hydrothermal Transfer Processes in Permafrost Regions of Qinghai-Tibet Plateau in China

Hydrothermal processes are key components in permafrost dynamics; these processes are integral to global wanning. In this study the coupled heat and mass transfer model for （CoupModel） the soil-plant-atmosphere-system is applied in high-altitude permafrost regions and to model hydrothermal transfer processes in freeze-thaw cycles. Measured meteorological forcing and soil and vegetation properties are used in the CoupModel for the period from January 1, 2009 to December 31, 2012 at the Tanggula observation site in the Qinghai-Tibet Plateau. A 24-h time step is used in the model simulation. The results show that the simulated soil temperature and water content, as well as the frozen depth compare well with the measured data. The coefficient of determination （R2） is 0.97 for the mean soil temperature and 0.73 for the mean soil water content, respectively. The simulated soil heat flux at a depth of 0-20 cm is also consistent with the monitored data. An analysis is performed on the simulated hydrothermal transfer processes from the deep soil layer to the upper one during the freezing and thawing period. At the beginning of the freezing period, the water in the deep soil layer moves upward to the freezing front and releases heat during the freezing process. When the soil layer is completely frozen, there are no vertical water ex- changes between the soil layers, and the heat exchange process is controlled by the vertical soil temperature gradient. During the thaw- ing period, the downward heat process becomes more active due to increased incoming shortwave radiation at the ground surface. The melt water is quickly dissolved in the soil, and the soil water movement only changes in the shallow soil layer. Subsequently, the model was used to provide an evaluation of the potential response of the active layer to different scenarios of initial water content and climate warming at the Tanggula site. The results reveal that the soil water content and the organic layer provide protection against active layer deepening in summer, so climate warming will cause the permafrost active layer to become deeoer and permafrost degradation.

Numerical Simulation of CO_2 Concentrations in East Asia with RAMS-CMAQ

The regional air quality modeling system RAMS-CMAQ(Regional Atmospheric Modeling System and Models-3 Community Multi-scale Air Quality) was developed by incorporating a vegetation photosynthesis and respiration module(VPRM) and used to simulate temporal-spatial variations in atmospheric CO2 concentrations in East Asia,with prescribed surface CO2 fluxes(i.e.,fossil fuel emission,biomass burning,sea-air CO2 exchange,and terrestrial biosphere CO2 flux).Comparison of modeled CO2 mixing ratios with eight ground-based in-situ measurements demonstrated that the model was able to capture most observed CO2 temporal-spatial features.Simulated CO2 concentrations were generally in good agreement with observed concentrations.Results indicated that the accumulated impacts of anthropogenic emissions contributed more to increased CO2 concentrations in urban regions relative to remote locations.Moreover,RAMS-CMAQ analysis demonstrates that surface CO2 concentrations in East Asia are strongly influenced by terrestrial ecosystems.

Advances in the Study of Black Carbon Effects on Climate

Black carbon （BC） aerosols can strongly absorb solar radiation in very broad spectral wavebands, from the visible to the infrared. As a potential factor contributing to global warming, BC aerosols not only directly change the radiation balance of the earth-atmosphere system, but also indirectly affect global or regional climate by acting as cloud conden- sation nuclei or ice nuclei to alter cloud mierophysical properties. Here, recent progresses in the studies of radiative forcing due to BC and its climate effects are reviewed. The uncertainties in current researches are discussed and some suggestions are provided for future investigations.

Development of RAMS-CMAQ to Simulate Aerosol Optical Depth and Aerosol Direct Radiative Forcing and Its Application to East Asia

The air quality modeling system RAMS (Regional Atmospheric Modeling System)-CMAQ (Models-3 Community Multi-scale Air Quality) is developed to simulate the aerosol optical depth (AOD) and aerosol direct forcing (DF). The aerosol-specific extinction, single scattering albedo, and asymmetry factor are parameterized based on Mie theory taking into account the aerosol size distribution, composition, refractive index, and water uptake of solution particles. A two-stream solar radiative model considers all gaseous molecular absorption, Rayleigh scattering, and aerosols and clouds. RAMSCMAQ is applied to simulate all major aerosol concentrations (e.g., sulfate, nitrate, ammonium, organic carbon, black carbon, fine soil, and sea salt) and AOD and DF over East Asia in 2005. To evaluate its performance, the simulated AOD values were compared with ground-based in situ measurements. The comparison shows that RAMSCMAQ performed well in most of the model domain and generally captured the observed variations. High AOD values (0.2 1.0) mainly appear in the Sichuan Basin as well as in central and southeastern China. The geographic distribution of DF generally follows the AOD distribution patterns, and the DF at the top-of-the-atmosphere is less than 25 and 20 W m 2 in clear-sky and all-sky over the Sichuan Basin. Both AOD and DF exhibit seasonal variations with lower values in July and higher ones in January The DF could obviously be impacted by high cloud fractions.

Comparison Study Between Observation and Simulation for Sea Fog over the Yellow Sea in May 2009

In this paper, almost all available observational data and the latest 6.0 version of Regional Atmospheric Modeling System (RAMS) model were employed to investigate a heavy sea fog event occurring over the Yellow Sea from 2 to 5 May 2009. The evolutionary process of this event was documented by using Multifunctional Transport Satellites-1 (MTSAT-1) visible satellite imagery. The synoptic situation, sounding profiles at two selected stations were analyzed. The difference between the air temperature and sea surface temperature during the sea fog event over the entire sea region was also analyzed. In order to better understand this event, an RAMS modeling with a 15 km×15 km resolution was performed. The model successfully reproduced the main characteristics of this sea fog event. The simulated height of fog top and the area of lower atmospheric visibility derived from the RAMS modeling results showed good agreement with the sea fog area identified from the satellite imagery. Examinations of both observational data and RAMS modeling results suggested that advection cooling seemed to play an important role in the formation of this sea fog event.

Assessment of Individual Direct Radiative Effects of Major Aerosol Species in East Asia

To assess individual direct radiative effects of diverse aerosol species on a regional scale, the air quality modeling system RAMS-CMAQ （Regional Atmospheric Modeling System and Community Multiscale Air Quality） coupled with an aerosol optical properties/radiative transfer module was used to simulate the temporal and spatial distributions of their optical and radiative properties over East Asia throughout 2005. Annual and seasonal averaged aerosol direct radiative forcing （ADRF） of all important aerosols and individual components, such as sulfate, nitrate, ammonium, black carbon （BC）, organic carbon （OC）, and dust at top-of-atmosphere （TOA） in clear sky are analyzed. Analysis of the model results shows that the annual average ADRF of all important aerosols was in the range of 0 to -18 W m-z, with the maximum values mainly distributed over the Sichuan Basin. The direct radiative effects of sulfate, nitrate, and ammonium make up most of the total ADRF in East Asia, being concentrated mainly over North and Southeast China. The model domain is also divided into seven regions based on different administrative regions or countries to investigate detailed information about regional ADRF variations over East Asia. The model results show that the ADRFs of sulfate, ammonium, BC, and OC were stronger in summer and weaker in winter over most regions of East Asia, except over Southeast Asia. The seasonal variation in the ADRF of nitrate exhibited the opposite trend. A strong ADRF of dust mainly appeared in spring over Northwest China and Mongolia.

GIS Applications for Building 3D Campus, Utilities and Implementation Mapping Aspects for University Planning Purposes

In city planning managing, the third dimension is becoming a necessity. Using 3D GIS modeling offers a flexible interactive system while providing one of the best visual interpretation of data which supports planning and decision processes for city planners. As a result, 3D GIS model expresses terrain features in an intuitive way which enhances the management and analysis of a proposed project through 3D visualization. This paper discusses the concept of 3D GIS modeling techniques using a simple procedure to generate a university campus model （real 3D GIS model） which will show the effectiveness of this approach. The 3D GIS model provides access to mapping data to support planning, design and data management. Intelligent GIS models and GIS tools help community planning and apply regional and discipline-specific standards. Integration of GIS spatial data with campus organization helps to improve quality, productivity and asset management. The following study built 3D GIS map and all utility information for AI al-Bayt University campus as an example. The primary objective is to improve data management （e.g., maps, plans, usage of facilities and services） and to develop methods using 3D spatial analysis for specific applications at the university.

The effects of giant cloud condensation nuclei on the structure of precipitation in hailstorm clouds

The Regional Atmospheric Modeling System (RAMS) has been used to investigate the effects of varied giant cloud condensation nuclei (GCCN) concentrations on precipitation characteristics of the spring hailstorms in a semi-arid region. The simulation result shows that this variation has significant effects on the storm microphysical processes as well as on the surface precipitation. The coverage of hail and hail mixing ratio maxima in cloud increases with greater GCCN concentrations. The accumulation zone structure benefits the growth of hail particles. Higher GCCN concentrations lead to more supercooled rain water and cloud water available for freezing. This simulation also shows that increasing GCCN concentrations may produce more rainfall on the surface but less hail precipitation, and the total accumulated precipitation increases while the ice phase precipitation decreases. This effect is stronger in polluted air than in clean air. The surface flow field changes with different GCCN concentrations. The identification index of spring hailstorm is different from that of summer hailstorm with a different aerosol background.