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Search Results: 1 - 10 of 13736 matches for " JiShan Xue "
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Progresses of Researches on Numerical Weather Prediction in China: 1999-2002
Progresses of Researches on Numerical Weather Prediction in China: 1999-2002

XUE Jishan,
XUE
,Jishan

大气科学进展 , 2004,
Abstract: The recent progresses in the research and development of (NWP) in China are reviewed in this paper. The most impressive achievements are the development of direct assimilation of satellite irradiances with a 3DVAR (three-dimentional variational) data assimilation system and a non-hydrostatic model with a semi-Lagrangian semi-implicit scheme. Progresses have also been made in model physics and model application to precipitation and environmental forecasts. Some scientific issues of great importance for further development are discussed.
Numerical Weather Prediction in China in the New Century ---Progress, Problems and Prospects
Numerical Weather Prediction in China in the New Century ——Progress, Problems and Prospects

XUE Jishan,LIU Yan,
XUE Jishan
,LIU Yan

大气科学进展 , 2007,
Abstract: This paper summarizes the recent progress of numerical weather prediction(NWP)research since the last review Was published.The new generation NWP system named GRAPES (the Global and Regional Assimilation and Prediction System),which consists of variational or sequential data assimilation and nonhydrostatic prediction model with options of configuration for either global or regional domains,is briefly introduced,with stress on their scientific design and preliminary results during pre-operational implementation.In addition to the development of GRAPES.the achievements in new methodologies of data assimilation,new improvements of model physics such as parameterization of clouds and planetary boundary layer,mesoscale ensemble prediction system and numerical prediction of air quality are presented.The scientific issues which should be emphasized for the future are discussed finally.
Radar Data Assimilation of the GRAPES Model and Experimental Results in a Typhoon Case

LIU Hongy,XUE Jishan,GU Jianfeng,XU Haiming,

大气科学进展 , 2012,
Abstract: Constructing β-mesoscale weather systems in initial fields remains a challenging problem in a mesoscale numerical weather prediction (NWP) model. Without vertical velocity matching the β-mesoscale weather system, convection activities would be suppressed by downdraft and cooling caused by precipitating hydrometeors. In this study, a method, basing on the three-dimensional variational (3DVAR) assimilation technique, was developed to obtain reasonable structures of β-mesoscale weather systems by assimilating radar data in a next-generation NWP system named GRAPES (the Global and Regional Assimilation and Prediction System) of China. Single-point testing indicated that assimilating radial wind significantly improved the horizontal wind but had little effect on the vertical velocity, while assimilating the retrieved vertical velocity (taking Richardson’s equation as the observational operator) can greatly improve the vertical motion. Experiments on a typhoon show that assimilation of the radial wind data can greatly improve the prediction of the typhoon track, and can ameliorate precipitation to some extent. Assimilating the retrieved vertical velocity and rainwater mixing ratio, and adjusting water vapor and cloud water mixing ratio in the initial fields simultaneously, can significantly improve the tropical cyclone rainfall forecast but has little effect on typhoon path. Joint assimilating these three kinds of radar data gets the best results. Taking into account the scale of different weather systems and representation of observational data, data quality control, error setting of background field and observation data are still requiring further in-depth study.
斜压大气中飑线的非线性过程与K-dV方程
李麦村 Li Maicun,薛纪善 Xue Jishan
大气科学 , 1984, DOI: 10.3878/j.issn.1006-9895.1984.02.04
Abstract: 本文从理论上证明斜压非静力平衡大气中飑线的形成与演变和正压大气中一样可以归结为一类由K-dV方程所描述的大气孤波.讨论了在具有垂直切变的基本气流中这类孤波的结构特征,并与观测事实作了对比.当沿着低空急流出现有限宽度的初始扰动时,这种孤波可以被激发出来.当扰动的强度与宽度达到一定值时,还将形成一种孤波队列.这正是大气中所观测到的飑线或雷雨列队现象.
热带风场与气压场的客观分析
薛纪善 Xue Jishan,王康玲 Wang kangling
大气科学 , 1992, DOI: 10.3878/j.issn.1006-9895.1992.02.04
Abstract: 本文着重讨论了为恰当定义热带风场的辐散分量,客观分析方案所应具备的基本条件,指出过去通行的分析方案在这方面的严重缺陷,并提出了一个改进方案.理想与实测资料的分析结果都表明,新的分析方案在保留分析流场的辐散分量与减小分析误差方面都有明显的效果.同时新的分析方案还提供了低纬度实施多变量分析的可能性,从而部分地缓解了低纬度观测资料不完整所造成的困难.
Application of Direct Assimilation of ATOVS Microwave Radiances to Typhoon Track Prediction
ZHANG Hu,XUE Jishan,ZHU Guofu,ZHUANG Shiyu,WU Xuebao,ZHANG Fengying,
ZHANG Hu
,XUE Jishan,ZHU Guofu,ZHUANG Shiyu,WU Xuebao,ZHANG Fengying

大气科学进展 , 2004,
Abstract: In order to solve the difficult problem of typhoon track prediction due to the sparsity of conventional data over the tropical ocean, in this paper, the No. 0205 typhoon Rammasun of 4-6 July 2002 is studied and an experiment of the typhoon track prediction is made with the direct use of the Advanced TIROS-N Operational Vertical Sounder (ATOVS) microwave radiance data in three-dimensional variational data assimilation. The prediction result shows that the experiment with the ATOVS microwave radiance data can not only successfully predict the observed fact that typhoon Rammasun moves northward and turns right, but can also simulate the action of the fast movement of the typhoon, which cannot be simulated with only conventional radiosonde data. The skill of the typhoon track prediction with the ATOVS microwave radiance data is much better than that without the ATOVS data. The typhoon track prediction of the former scheme is consistent in time and in location with the observation. The direct assimilation of ATOVS microwave radiance data is an available way to solve the problem of the sparse observation data over the tropical ocean, and has great potential in being applied to typhoon track prediction.
Scientific design and preliminary results of three-dimensional variational data assimilation system of GRAPES
JiShan Xue,ShiYu Zhuang,GuoFu Zhu,Hua Zhang,ZhiQuan Liu,Yan Liu,ZhaoRong Zhuang
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0416-0
Abstract: The scientific design and preliminary results of the data assimilation component of the Global-Regional Prediction and Assimilation System (GRAPES) recently developed in China Meteorological Administration (CMA) are presented in this paper. This is a three-dimensional variational (3DVar) assimilation system set up on global and regional grid meshes favorable for direct assimilation of the space-based remote sensing data and matching the frame work of the prediction model GRAPES. The state variables are assumed to decompose balanced and unbalanced components. By introducing a simple transformation from the state variables to the control variables with a recursive or spectral filter, the convergence rate of iteration for minimization of the cost function in 3DVar is greatly accelerated. The definition of dynamical balance depends on the characteristic scale of the circulation considered. The ratio of the balanced to the unbalanced parts is controlled by the prescribed statistics of background errors. Idealized trials produce the same results as the analytic solution. The results of real data case studies show the capability of the system to improve analysis compared to the traditional schemes. Finally, further development of the system is discussed.
Direct assimilation of satellite radiance data in GRAPES variational assimilation system
GuoFu Zhu,JiShan Xue,Hua Zhang,ZhiQuan Liu,ShiYu Zhuang,LiPing Huang,PeiMing Dong
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0419-x
Abstract: Variational method is capable of dealing with observations that have a complicated nonlinear relation with model variables representative of the atmospheric state, and so make it possible to directly assimilate such measured variables as satellite radiance, which have a nonlinear relation with the model variables. Assimilation of any type of observations requires a corresponding observation operator, which establishes a specific mapping from the space of the model state to the space of observation. This paper presents in detail how the direct assimilation of real satellite radiance data is implemented in the GRAPES-3DVar analysis system. It focuses on all the components of the observation operator for direct assimilation of real satellite radiance data, including a spatial interpolation operator that transforms variables from model grid points to observation locations, a physical transformation from model variables to observed elements with different choices of model variables, and a data quality control. Assimilation experiments, using satellite radiances such as NOAA17 AMSU-A and AMSU-B (Advanced Microwave Sounding Unit), are carried out with two different schemes. The results from these experiments can be physically understood and clearly reflect a rational effect of direct assimilation of satellite radiance data in GRAPES-3DVar analysis system.
Initialization of Limited Area Model Based on the Principle of Nonlinear Normal Mode Initialization
非线性正规模初值化原则在有限区模式的实现

Xue Jishan,Li Canji,Wang Zhiming,
薛纪善
,李璨玑,王志明

大气科学 , 1992,
Abstract: Two general conditions of initialization for limited area model and their corresponding iterative computational formulae are derived in this paper. These conditions are equivalent to those of nonlinear normal mode initialization, but totally expressed in terms of the model variables. The fact that the normal modes of the model do not appear in those formulae makes it easy to perform in any regional model, of which the normal modes are usually difficult to derive. This proposed initialization scheme is applied to the two numerical prediction models. The results have proven that this scheme can effectively suppress the unwanted high frequency gravitational oscillation due to imbalance existing in the initial data .
Economical Explicit Integration of High Resolution Regional Numerical Prediction Models
高分辨有限区数值预报模式的省时显式积分

Xue Jishan,Lin Junjie,Wang Kangling,
薛纪善
,林俊杰,王康玲

大气科学 , 1995,
Abstract: In this paper, an economical explicit scheme is used to integrate two high resolution numerial prediction models. It is shown that this new scheme for time integration effectively saves the computer resources without notable changes in the forecast fields. The problems of lateral boundary treatment needed When this scheme is applied to the limited area model are also discussed. A new boundary filter equivalent to that of leap frog scheme is proposed.
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