Direct assimilation of satellite radiance data in GRAPES variational assimilation system

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.     

Scientific design and preliminary results of three-dimensional variational data assimilation system of GRAPES

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.     

The program structure designing and optimizing tests of GRAPES physics

According to the modularization and standardization of program structure in Global/Regional Assimilation and Prediction System （GRAPES）, the plug-compatible and transplantable regional meso-scale and global middle-range physics software package is established. The package＇s component integrality is comparative with the other advanced models physics. A three-level structure of connecting GRAPES physics and dynamic frame has been constructed. The friendly interface is designed for users to plug in their own physics packages. Phenomenon of grid-point storm rainfall in numerical prediction is analyzed with the numerical tests. The scheme of air vertical velocity calculation is improved. Opti- mizing tests of physics schemes are performed with the correlative parameters adjusting. The results show that the false grid-point storm rainfall is removed by precipitation scheme improving. Then the score of precipitation forecast is enhanced.     

A new-generation sand and dust storm forecasting system GRAPES_CUACE/Dust: Model development,verification and numerical simulation

Based on the new-generation Global/Regional Assimilation and PrEdiction System(GRAPES) developed by the Numerical Prediction Research Center,China Meteorological Administration and the Chinese Unified Atmospheric Chemistry Environment for Dust Atmospheric Chemistry Module(CUACE/Dust) developed by the Centre for Atmosphere Watch and Services(CAWAS) of the Chinese Academy of Meteorological Sciences(CAMS) ,the China sand and dust storm forecasting system GRAPES /CUACE-Dust model has been established.The latest...     

瑞利波泄漏模式的模拟研究

瑞利导波相速度频散曲线有时会出现截止或截断现象,此时必须考虑泄漏模式波的存在,如何快速求取泄漏模式波的相速度大小是研究的核心问题．采用添加附加层的方法,使瑞利波实频散方程求根的范围包含所有的层速度区域,从而可用Abo—zena,Menke和Bixing Zhang等学者研究过的传递矩阵理论,利用二分法求解相速度大小,即用导波来模拟计算泄漏模式波相速度大小．从模拟计算结果来看,附加层法不仅能模拟出原模型的实数导波,而且还能计算出泄漏模式波的变化．由此可见,用附加层法来计算瑞利波的泄漏模式是可行的;同时,若将该方法应用于瑞利波勘探的反演,它不会增加未知数的个数。     

砂岩表面zeta电位与渗流过程的关系

目的 研究储油砂岩表面的zeta电位对油水渗流过程的影响。方法用电渗法测量砂岩表面的zeta电位，用岩心驱替法测渗流过程。结果加入季铵盐型阳离子表面活性剂对砂岩表面的电性具有较大的影响，随着阳离子表面活性剂浓度的增加，砂岩表面的负电性逐渐减弱至不带电，最后变为正电。十八烷基三甲基氯化铵驱油实验证明：zeta电位与渗流过程关系密切，零电位时，油的渗流最好，有利于残余油的驱出。结论zeta电位影响着渗流过程，零电位对渗流过程最有利．驱油剂对砂岩表面电性的影响较大。     

New generation of multi-scale NWP system （GRAPES）： general scientific design

A new generation of numerical prediction system GRAPES （a short form of Global/Regional Assimilation and PrEdiction System） was set up in China Meteorological Administration （CMA）. This paper fo- cuses on the scientific design and preliminary results of the numerical prediction model in GRAPES, including basic idea and strategy of the general scientific design, multi-scale dynamic core, physical package configuration, architecture and parallelization of the codes. A series of numerical experiments using the real data with horizontal resolutions from 10 to 280 km and idealized experiments with very high resolution up to 100 m are conducted, giving encouraging results supporting the multi-scale application of GRAPES. The results of operational implementation of GRAPES model in some NWP centers are also presented with stress at evaluations of the capability to predict the main features of precipitation in China. Finally the issues to be dealt with for further development are discussed.