Traditional gravity wave drag parameterizations produce wind stresses that are insensitive to changing horizontal resolution in numerical weather prediction (NWP), partly due to the idealized elliptical assumption. This study employs the modified subgrid-scale orography scheme based on the Fourier transform into gravity wave drag scheme of the China Meteorological Administration Global Forecast System (CMA-GFS) to assess its impacts on simulating precipitation during the slow-moving period of Typhoon In-Fa after its landfall in Zhejiang Province, China. The simulation with the updated scheme can effectively reduce the accumulated precipitation bias of the control one and improve the simulation of precipitation distribution and intensity, especially in the hourly precipitation simulation. The improved scheme primarily influences the wind field of the low-level troposphere and also changes the convergence of the integrated water vapor transport and ascending motions related to the reduced precipitation biases. The modified scheme enhances the tendencies of the horizontal winds caused by the varying horizontal resolutions in the model, strengthening the sensitivity of the gravity wave drag across the horizontal scales. Results from medium-range forecasts indicate the modified scheme benefits the statistics scores of precipitation over China and also reduces root-mean-square errors of 2 m temperature and 10 m winds.

The developing history of GRAPES global middle-range numerical weather prediction system (GRAPES GFS)of China Meteorological Administration is reviewed.Important progresses in recent years are summarized and their contributions to GRAPES GFS operation are introduced. From the aspect of dynamic frame aspect,an algorithm for vertical advection of temperature and the polar filter scheme are improved.New algorithms are introduced,including terrain filtering algorithm, scalar advection scheme with conservation and high accuracy,w-damping noise suppression algorithm,and Rayleigh friction in the stratosphere,etc.Besides,horizontal and vertical resolutions are enhanced.These improvements significantly improve the stability,accuracy and mass conservation of the dynamic core. From the aspect of physical process,the RRTMG radiation program is upgraded,the CoLM land sur-face process scheme is introduced,the cumulus convective scheme and boundary layer scheme are im-proved,and a two-parameter cloud physics scheme is developed.On these basis,the prediction cloud scheme is further developed,the interface between dynamic and physics is adjusted,the calculation of sea ice and surface albedo are also optimized.These improvements and optimizations improve the prediction ability of the physical package. From the aspect of global three-dimensional variational assimilation (3DVar),the model space 3DVar is developed to avoid the interpolation error of the analysis space to the model space,fine quality control and deviation correction techniques are developed to achieve high quality observation data assimilation,and more satellite data assimilation techniques are adopted especially using satellite hyperspectral infrared de-tector as the focus. At the same time,the prediction ability of GRAPES GFS2.0 is being evaluated based on results of two-year assimilation forecast cycle test,and compared with T639.Generally speaking,the forecast indi-cators of the system are fully beyond the GRAPES GFS 1.0 version.Model outputs of isobaric elements in the troposphere forecast,including precipitation and 2 m temperature,have obvious advantages comparing with T639.

The initial tendency approach is used to diagnose systematic errors in global GRAPES（Global/Regional Assimilation Prediction System）, including overly strong westerlies in the northern midlatitudes, cold/warm bias dipoles in the vicinity of the tropopause, and excessively strong southerlies in downstream regions of the Tibetan Plateau. This approach, involving the use of the assimilation system, focuses on the first few time steps of numerical weather forecasts to identify the deficiencies in diabatic forcing. The results show that there is insufficient diabatic dissipation in the upper troposphere and lower stratosphere of the northern midlatitudes and the lower troposphere of most latitudes, which results from the absence of a parameterization of subgrid orographic drag in global GRAPES. A scheme to parameterize the effects of these drags is therefore tested and the experiments indicate that the newly introduced scheme reduces zonal momentum budget residuals, weakens the northern midlatitude westerlies and southerlies in the downstream regions of the Tibetan Plateau, decreases the cold/warm bias dipoles, and leads to improved objective verification scores.

Cumulus convection is a key linkage between hydrological cycle and large-scale atmospheric circulation.Cumulus parameterization scheme is an important component in numerical weather and climate modeling studies.In the Global/Regional Assimilation and Prediction Enhanced System（GRAPES）,turbulent mixing and diffusion approach is applied in its shallow convection scheme.This method overestimates the vertical transport of heat and moisture fluxes but underestimates cloud water mixing ratio over the region of stratocumulus clouds.As a result,the simulated low stratocumulus clouds are less than observations.To overcome this problem,a mass flux method is employed in the shallow convection scheme to replace the original one.Meanwhile,the deep convection scheme is adjusted correspondingly.This modification is similar to that in the US NCEP Global Forecast System（GFS）,which uses the simplified Arakawa Schubert Scheme（SAS）.The planetary boundary layer scheme（PBL） is also revised by considering the coupling between the PBL and stratocumulus clouds.With the modification of both the cumulus and PBL schemes,the GRAPES simulation of shallow convective heating rate becomes more reasonable;total amounts of stratocumulus clouds simulated over the eastern Pacific and their vertical structure are more consistent with observations;the underestimation of stratocumulus clouds simulated by original schemes is less severe with the revised schemes.Precipitation distribution in the tropics becomes more reasonable and spurious precipitation is effectively suppressed.The westward extension and northward movement of the western Pacific subtropical high simulated with the revised schemes are more consistent with Final Operational Global Analysis（FNL） than that simulated with the original schemes.The statistical scores for the global GRAPES forecast are generally improved with the revised schemes,especially for the simulation of geopotential height in the Northern Hemisphere and winds in the tropics.Root mean square errors（RMSEs） decrease in the lower and upper troposphere with the revised schemes.The above results indicate that with the revised cumulus and PBL schemes,model biases in the tropics decrease and the global GRAPES performance is greatly improved.

A new mesoscale coupled air-sea model was developed based on the Global/Regional Assimilation and Prediction System(GRAPES) with the improved Mellor-Yamada type Ocean Mixed Layer Model(OMLM) employed.Using this GRAPES_OMLM model,Typhoon Chanchu(2006) was simulated to test the ability of the GRAPES_OMLM in typhoon research and investigate the impact of local air-sea interaction on typhoon.The results show that the GRAPES_OMLM is able to catch the main physical processes of the typhoon weather.The simulated minimum surface pressure,maximum wind near the typhoon center and the typhoon's track in the coupled model where the air-sea interaction is included are better consistent with the observation than those in the uncoupled model.Furthermore,compared to the experiment Ctrl_1 with unchanged SST condition,the results of the Ctrl_2 in which daily mean SST is adopted have a bit improvement as well.The SST simulated in the coupled model is also very close to the observation with the maximum SST cooling of more than 4.0℃,which is located at the right of Chanchu's track.There is an inverse correlation between the change of SST and the surface wind stress,and the increasing of wind stress will induce TKE's rise with wind-inducing mixing as the main reason for the SST cooling.Moreover,SST cooling can weaken the typhoon's intensity and change the typhoon's circulation structure through reducing the heat flux from the ocean,as well as change the WN-1 structure of the Potential Vorticity Tendency which affects the typhoon's track.

Using the latest version of SAMIL (Spectral Atmosphere Model of IAP LASG) developed by LASG/IAP,we evaluate the model performance by analyzing rainfall,latent heating structure and other basic fields with two different convective parameterization schemes:Manabe Scheme and Tiedtke Scheme.Results show that convective precipitation is excessively overestimated while stratiform precipitation is underestimated by Tiedtke scheme,thus causing less stratiform rainfall proportion compared with TRMM observation.In contrast,for Manabe scheme stratiform rainfall belt is well simulated,although precipitation center near Bay of Bengal (BOB) spreads eastward and northward associated with unrealistic strong rainfall downstream of the Tibet Plateau.The simulated latent heating structure indicates that Tiedtke scheme has an advantage over Manabe scheme,as the maximum convective latent heating near middle of troposphere is well reproduced.Moreover,the stratiform latent heating structure is also well simulated by Tiedtke scheme with warming above freezing level and cooling beneath freezing level.As for Manabe scheme,the simulated maximum convective latent heating lies near 700 hPa,lower than the observation.Additionally,the warming due to stratiform latent heating extends to the whole vertical levels,which is unreasonable compared with observation.Taylor diagram further indicates that Tiedtke scheme is superior to Manabe scheme as higher correlation between model output and observation data is achieved when Tiedtke scheme is employed,especially for the temperature near 200 hPa.Finally,a possible explanation is addressed for the unrealistic stratiform rainfall by Tiedtke scheme,which is due to the neglect of detrained cloud water and cloud ice during convective process.The speculation is verified through an established sensitivity experiment.

In general there exists double ITCZ bias either in coupled models or in atmospheric general circulation models; so does in the new version of the LASG/IAP (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics, Chinese Academy of Sciences) spectral atmospheric model SAMIL_R42L26: there is less rainfall near the equator while more rainfall on both the north and south sides. This bias can affect the tropical circulations and global energy balance. However, the bias can be weakened through the modified Tiedtke cumulus convective parameterization scheme. The new scheme can affect the distribution of temperature in the lower troposphere, even on the surface, and the associated wind and divergence fields are also changed, which in turn create conditions for the further development of convection, forming a positive feedback. Finally the eastward extension of precipitation bias along the SPCZ (Southern Pacific Convergence Zone) can be effectively restrained, and at the same time, the insufficient rainfall over the tropical warm pool is increased.

中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室所发展的高分辨率全球大气环流谱模式SAMIL,自从发展成R42L26新版本之后,显示出对全球气候基本态的模拟能力,但模式对流层低层以及热带地区整层偏干,且对热带地区的降水模拟存在"双赤道辐合带"这一普遍误差,在赤道地区以及北半球中纬度降水偏少,而在拉丁美洲降水偏多。敏感性试验表明这些误差是相互联系的。通过将700 hPa以下的相对湿度趋近于"观测资料"的试验显示模拟的降水误差减小了。据此,对Tiedtke积云对流参数化方案中的浅对流部分进行修改,增加了浅对流的侧向混合的卷入以及卷出率,并减小了对流方案中的云水-雨水的转换率,将其耦合到模式中。积分结果表明,修改后的方案明显改进了湿度和温度场的模拟,对降水的模拟能力有了很大的提高,基本消除了"双赤道辐合带"现象。

The main aspects of the multi-agent system(MAS) were agent-oriented, combined with formal program language Visual C++. A functional model of traffic system was constructed based on MAS, and on the basis of MFC library of Visual C++, the agent class that has the basic functions of cooperation, communication and autonomy is also designed.

The paper presents the design of a servo driver which can control different kinds of motors.This kind of driver uses advanced 16 bits CPU 80C196KC as its control kernel.It can control induced motor、synchronous motor or two DC servo motors.It can change control modes through the software with the same hardware platform. The paper emphasizes the hardware structure and software control mode for three kinds of motor.