Mesoscale dynamics and its application in torrential rainfall systems in China

Progress over the past decade in understanding moisture-driven dynamics and torrential rain storms in China is reviewed in this paper. First, advances in incorporating moisture effects more realistically into theory are described, including the development of a new parameter, generalized moist potential vorticity(GMPV) and an improved moist ageostrophic Q vector(Qum). Advances in vorticity dynamics are also described, including the adoption of a "parcel dynamic" approach to investigate the development of the vertical vorticity of an air parcel; a novel theory of slantwise vorticity development, proposed because vorticity develops easily near steep isentropic surfaces; and the development of the convective vorticity vector(CVV)as an effective new tool. The significant progress in both frontal dynamics and wave dynamics is also summarized, including the geostrophic adjustment of initial unbalanced flow and the dual role of boundary layer friction in frontogenesis, as well as the interaction between topography and fronts, which indicate that topographic perturbations alter both frontogenesis and frontal structure. For atmospheric vortices, mixed wave/vortex dynamics has been extended to explain the propagation of spiral rainbands and the development of dynamical instability in tropical cyclones. Finally, we review wave and basic flow interaction in torrential rainfall, for which it was necessary to extend existing theory from large-scale flows to mesoscale fields, enriching our knowledge of mesoscale atmospheric dynamics.     

THE LIMITATION OF CLOUD-BASE MASS FLUX IN CUMULUS PARAMETERIZATION AND ITS APPLICATION IN A HIGH-RESOLUTION MODEL

A large area of unrealized precipitation is produced with the standard convective parameterization scheme in a high-resolution model, while subgrid-scale convection that cannot be explicitly resolved is omitted without convective parameterization. A modified version of the convection scheme with limited mass flux at cloud base is introduced into a south-China regional high-resolution model to alleviate these problems. A strong convection case and a weak convection case are selected to analyze the influence of limited cloud-base mass flux on precipitation forecast. The sensitivity of different limitation on mass flux at cloud base is also discussed. It is found that using instability energy closure for Simplified Arakawa- Schubert Scheme will produce better precipitation forecast than the primary closure based on quasi-equilibrium assumption. The influence of the convection scheme is dependent on the upper limit of mass flux at cloud base. The total rain amount is not so sensitive to the limitation of mass flux in the strong convection case as in the weak one. From the comparison of two different methods for limiting the cloud-base mass flux, it is found that shutting down the cumulus parameterization scheme completely when the cloud-base mass flux exceeds a given limitation is more suitable for the forecast of precipitation.     

Land use change and its ecological effect in Qian'an County of Jilin Province

Based on GIS and statistical methods, with the help of searching historical literatures and calculating the landscape indices, the land use changes of Qian'an County in both spatial and temporal aspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changes and their ecological effects are discussed too. The main findings of this study are as follows: (1) Land use changed greatly in Qian'an during 1945-1996, characterized by a decrease in grassland, wetland and water bodies, and an increase in cultivated land, saline-alkali land, and the land for housing and other construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by 102,137.23 ha over the half century. Accordingly, the main landscape type changed from a steppe landscape to a managed agricultural ecosystem. (2) Results of correlation analysis show that the land use change in the study area was mainly driven by the socioeconomic factors.　(3) The ecological effects of land use change in the area are characterized by serious salinization, degression of soil fertility and the weakening of landscape suitability.     

卫星跟踪卫星模式中轨道参数需求分析

首次基于半解析法利用GRACE(Gravity Recovery and Climate Experiment)双星K波段星间速度误差、GPS接收机轨道误差和加速度计非保守力误差影响累计大地水准面精度的联合模型开展了卫星跟踪卫星模式中轨道参数的需求分析.建议我国将来首颗重力卫星的平均轨道高度设计为400 km和平均星间距离设计为220 km较优.此研究不仅为我国将来卫星重力测量计划中轨道参数的优化选取以及全球重力场精度的有效和快速估计提供了理论基础和计算保证,同时对将来国际GRACE Follow-On地球重力测量计划和GRAIL(Gravity Recovery and Interior Laboratory)月球重力探测计划的发展方向具有一定的指导意义.     

内蒙古雅布赖盆地红柳沟中侏罗统沉积相及沉积环境研究

野外考察发现,雅布赖盆地红柳沟发育一套较完整的中侏罗统扇三角洲沉积地层。其中沉积亚相有扇三角洲平原、扇三角洲前缘及前扇三角洲亚相;沉积微相包括辫状河道、天然堤、决口、沼泽、水下分流河道、水下分流河道间、河口坝、席状砂等沉积微相。从沉积构造特征分析可以看出,河道沉积发育于水动力条件较强的沉积环境,扇三角洲前缘河口坝沉积发育于强与弱水动力条件交替出现的沉积环境,而前扇三角洲则在比较稳定的水动力条件下沉积。对野外6个泥岩样品的微量元素化验结果用蜘蛛图解分析处理,得到样品所含微量元素V、Sr、Rb、B相对富集,而Zr、Cr、Ni相对亏损。通过对该地区样品w（Fe^2＋）/w（Fe^3＋）及气候指数计算表明,当时为弱氧化、半干旱的沉积环境。     

我国西南地区斑岩矿床区域成矿环境

本文对我国西南地区斑岩Cu(-Mo-Au)矿床形成的区域成矿环境进行了总结研究。我国西南地区斑岩矿床,构造上位于全球特提斯斑岩成矿带东段,与青藏高原演化密切相关,形成于青藏高原演化不同阶段。我国西南地区斑岩矿床形成时代为晚三叠世、早白垩世、古近纪和中新世等4个时期。斑岩矿床形成的区域成矿环境具有多样性,包括俯冲造山岛弧、同碰撞、后碰撞和大陆转换板块边界等四类构造环境。根据斑岩矿床成岩成矿时代和成矿环境,我国西南地区斑岩矿床可划分为义敦-中甸印支期斑岩成矿带、玉龙-马拉松多古近纪斑岩成矿带、丽江-金平古近纪斑岩成矿带、冈底斯古近纪-新近纪斑岩成矿带和班公湖-怒江燕山期斑岩成矿带等五个成矿带。与世界上多数斑岩矿床一样,我国西南地区斑岩矿床与区域深大走滑断裂存在着明显的空间分布关系。     

基于改进的双线性旅行时插值的三维射线追踪

旅行时射线追踪的精度和效率一直是影响地震层析成像质量和效果的关键因素。这里在三维近地表速度结构层析成像应用中,结合旅行时插值算法与最短路径算法,提出了一种三维初至波射线追踪算法。通过对双线性旅行时插值算法进行改进,并运用判定条件与简化插值计算公式进行快速计算,减少了插值次数,降低了运算量,同时也保证了较高的射线精度,有效地解决了三维射线追踪算法的计算低效率,射线精度不高的问题。     

基于微分对策理论的多沙河流水库调度

水库的排沙问题一直是多沙河流水库调度研究的重点之一。由于大部分多沙河流的来水来沙主要集中于汛期,因此水库汛期的蓄水兴利与泄水排沙的矛盾十分突出,具有典型的博弈关系,该关系可以利用博弈的相关理论进行描述。基于微分对策理论,将多沙河流水库汛期的供水兴利与泄水排沙看作博弈的双方,建立起以排沙和供水的综合效益作为性能指标函数的多沙河流水库汛期调度模型,研究了多沙河流水库汛期的调度问题,并通过陕西黑河某水库的实测资料对该模型进行了验证计算。计算结果表明,建立的调度模型能够较好地反映多沙河流水库汛期调度中的主要矛盾,实现对供水与排沙综合效益的优化。     

虚拟地理环境研究进展与理论框架

阐述虚拟地理环境的形成、发展与研究现状,并从"虚拟现实技术"与"虚拟现实"的相互关系探讨虚拟地理环境基本概念.从基本思想、系统结构、在线参与者社会组织水平、与GIS/数字地球的关系等角度,分析虚拟地理环境的特征.从数据、模型、表现以及协同4个方面,讨论了虚拟地理环境系统建设的关键技术与研究前沿.尝试建立了一个虚拟地理环境基本理论初步研究框架,认为在地理哲学思想层次应该重点研究复杂性人地系统、地理虚/实关系论、地理/遥感信息本体论,在地理/地理信息科学层次需要重点研究地理认知与思维、地理相似原理、地理计算模拟;同时讨论虚拟地理环境与面向"人"的地理信息科学、基于虚拟地理环境地理科学方法论,以及可计算人地关系的相关理论问题.     

浅析深水沉积理论

深水沉积理论的深入研究发现,传统的浊流沉积理论如鲍玛序列、浊积扇、浊积岩相等可能需要重新解释,对浊流理论的质疑推动着深水沉积理论的发展。通过对浊流沉积研究历史及当前研究现状的梳理,探讨了浊流及相关重力流沉积理论的新观点。