Assessment of Wet Season Precipitation in the Central United States by the Regional Climate Simulation of the WRFG Member in NARCCAP and Its Relationship with Large-Scale Circulation Biases

Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss possible causes of biases in a WRF-based RCM with a grid spacing of 50 km,named WRFG,from the North American Regional Climate Change Assessment Program(NARCCAP)in simulating wet season precipitation over the Central United States for a period when observational data are available.The RCM reproduces key features of the precipitation distribution characteristics during late spring to early summer,although it tends to underestimate the magnitude of precipitation.This dry bias is partially due to the model’s lack of skill in simulating nocturnal precipitation related to the lack of eastward propagating convective systems in the simulation.Inaccuracy in reproducing large-scale circulation and environmental conditions is another contributing factor.The too weak simulated pressure gradient between the Rocky Mountains and the Gulf of Mexico results in weaker southerly winds in between,leading to a reduction of warm moist air transport from the Gulf to the Central Great Plains.The simulated low-level horizontal convergence fields are less favorable for upward motion than in the NARR and hence,for the development of moist convection as well.Therefore,a careful examination of an RCM’s deficiencies and the identification of the source of errors are important when using the RCM to project precipitation changes in future climate scenarios.

Large-scale gas accumulation mechanisms and reservoir-forming geological effects in sandstones of Central and Western China

Large-scale gas accumulation areas in large oil-gas basins in central and Western China have multiple special accumulation mechanisms and different accumulation effects.Based on the geological theory and method of natural gas reservoir formation,this study examined the regional geological and structural background,formation burial evolution,basic characteristics of gas reservoirs,and fluid geology and geochemistry of typical petroliferous basins.The results show that the geological processes such as structural pumping,mudstone water absorption,water-soluble gas degasification and fluid sequestration caused by uplift and denudation since Himalayan stage all can form large-scale gas accumulation and different geological effects of gas accumulation.For example,the large-scale structural pumping effect and fluid sequestration effect are conducive to the occurrence of regional ultra-high pressure fluid and the formation of large-scale ultra-high pressure gas field;mudstone water absorption effect in the formation with low thickness ratio of sandstone to formation is conducive to the development of regional low-pressure and water free gas reservoir;the water-soluble gas degasification effect in large-scale thick sandstone can not only form large-scale natural gas accumulation;moreover,the degasification of water-soluble gas produced by the lateral migration of formation water will produce regional and regular isotopic fractionation effect of natural gas,that is,the farther the migration distance of water-soluble gas is,the heavier the carbon isotopic composition of methane formed by the accumulation.

A new classification of large-scale climate regimes around the Tibetan Plateau based on seasonal circulation patterns

This study aims to develop a large-scale climate classification for investigating the characteristics of the climate regimes around the Tibetan Plateau based on seasonal precipitation, moisture transport and moisture divergence using in situ observations and ERA40 reanalysis data. The results indicate that the climate can be attributed to four regimes around the Plateau. They situate in East Asia, South Asia, Central Asia and the semi-arid zone in northern Central Asia throughout the dryland of northwestern China, in addition to the K?oppen climate classification. There are different collocations of seasonal temperature and precipitation: 1) in phase for the East and South Asia monsoon regimes, 2) anti-phase for theCentral Asia regime, 3) out-of-phase for the westerly regime. The seasonal precipitation concentrations are coupled with moisture divergence, i.e., moisture convergence coincides with the Asian monsoon zone and divergence appears over the Mediterranean-like arid climate region and westerly controlled area in the warm season, while it reverses course in the cold season. In addition, moisture divergence is associated with meridional moisture transport. The northward/southward moisture transport corresponds to moisture convergence/divergence, indicating that the wet and dry seasons are, to a great extent, dominated by meridional moisture transport in these regions. The climate mean southward transport results in the dry-cold season of the Asian monsoon zone and the dry-warm season, leading to desertification or land degradation in Central Asia and the westerly regime zone. The mean-wind moisture transport (MMT) is the major contributor to total moisture transport, while persistent northward transient eddy moisture transport (TEMT) plays a key role in dry season precipitation, especially in the Asian monsoon zone. The persistent TEMT divergence is an additional mechanism of the out-of-phase collocation in the westerly regime zone. In addition, the climatemean MMTand TEMTare associated with the atmospheric stationary wave and storm track, which results from the uplift of orography and landsea thermal contrast. Therefore, the paleoclimate changes in mid-latitude arid-semi-arid regions are linked to the different phases of uplift of mountains and plate motion tied to the evolution of the Mediterranean.

Research on large-scale dispatchable grid-connected PV systems

This paper describes the research on a largescale dispatchable grid-connected photovoltaic(PV)system for supplying power to the grid for dispatch instead of supplying the electricity to a local load.In order to maximise the value of the solar energy,a hybrid electricity storage consisting of batteries and supercapacitors is used with the PV system.This paper proposes a control strategy focusing on theDCpower at theDClink rather than at the grid-connected inverter.Two typical sets of real data,collected from existing sites,are used to demonstrate the practicality of the system.Finally,the simulation results are used to demonstrate the good performance and feasibility of the proposed system together with the proposed control strategy.

Mean Flow–Storm Track Relationship and Rossby Wave Breaking in Two Types of El-Nino

The features of large-scale circulation, storm tracks and the dynamical relationship between them were examined by investigating Rossby wave breaking （RWB） processes associated with Eastern Pacific （EP） and Central Pacific （CP） E1-Nifio. During EP E1-Nino, the geopotential height anomaly at 500 hPa （Z500） exhibits a Pacific-North America （PNA） pattern. During CP EI-Nifio, the Z500 anomaly shows a north positive-south negative pattern over the North Pacific. The anomalous distributions of baroclinicity and storm track are consistent with those of upper-level zonal wind for both EP and CP EI-Nino, suggesting impacts of mean flow on storm track variability. Anticyclonic wave breaking （AWB） oczurs less frequently in EP EI-Nino years, while cyclonic wave breaking （CWB） occurs more frequently in CP EI-Nino years over the North Pacific sector. Outside the North Pacific, more CWB events occur over North America during EP Ei-NiNo. When AWB events occur less frequently over the North Pacific during EP EI-Nino, Z500 decreases locally and the zonal wind is strengthened （weakened） to the south （north）. This is because AWB events reflect a monopoie high anomaly at the centroid of breaking events. When CWB events occur more frequently over the North Pacific under CP EI-Nino conditions, and over North America under EP EI-Nino condition, Z500 increases （decreases） to the northeast （southwest）, since CWB events are related to a northeast-southwest dipole Z500 anomaly. The anomalous RWB events act to invigorate and reinforce the circulation anomalies over the North Pacific-North America region linked with the two types of EI-Nino.

城市污水处理厂中央控制系统的建设与管理

随着污水处理厂对管理要求的日益提高,自动化管理在污水处理厂中的应用越来越普及,中央控制系统能够全面反映污水处理厂的运行情况,便于污水处理厂的运行维护管理,同时也便于污水处理厂的运行监督。一个完善的中央控制系统不仅需要依照相关原则建设,同时需要采用正确科学的方法进行管理。介绍了污水处理厂中央控制系统建设的必要性,分析了中央控制系统的建设原则、步骤及其管理,以供参考。

基于物联网的分布式污水厂智能化集中监控的探索

基于创新"互联网+水务"的水务运营新模式,以及"智慧城市"在水处理行业的延伸,创建智慧型水务公司是响应国家战略的新探索。采用物联网先进技术,以数据为核心,针对跨省多地区分布式中小城镇污水处理厂,在实现各级厂站智能化、透明化改造与建设的基础上,逐步建设大数据远程智能化集中监控平台。实践表明,通过数据的分析、比对、挖掘、处理,能够有效促进集群化污水处理厂的节能降耗及精细化管控,进而为污水厂的可持续运营和节能减排作出贡献。

武汉北湖污水处理厂设计关键节点分析及组合流程的应用

武汉北湖污水处理厂近期设计规模为80×10^(4)m3/d,远期将达到150×10^(4)m^3/d。本次工程按80×10^(4)m^3/d一次建成,建成后将是国内最大的一次性建成的集中式市政污水处理厂。北湖污水处理厂设计出水水质优于一级A标准,为确保后期运行安全可靠,根据技术经济分析,设计采用了双工艺技术路线:40×10^(4)m^3/d采用改良AAO+深度处理工艺,40×10^(4)m^(3)/d采用AAO+MBR工艺,其中MBR工艺预留尾水再生回用条件。结合北湖厂方案设计,重点剖析了进出水水质和污水处理工艺等关键节点的设计,可为大型污水处理厂的设计与优化提供参考。