套网格预报中几种边界条件的试验

采用国家气象中心五层原始方程业务模式，用单向自嵌套方法，对常用的几种侧边界条件进行了对比试验。结果表明：加密网络可以改善预报效果，在试验的几种边界处理方案中，以Ｄａｖｉｅｓ方案的效果最好，不需要采用其他技术处理，就能使边界附近不产生扰动，分析的等值线光滑，计算稳定性好，可以使业务预报更加可靠，效果更加理想。     

双重套网格数值模式对一次暴雨系统模拟的比较试验

本文以自嵌套方式，将一个有限区域暴雨数值模式编制成单向和双向的套网格模式，同时又将这两个套网格模式分别与Ｔ４２Ｌ９模式进行了单向嵌套。形成了单向，双向两个双重套网格模式。运用这两个模式对１９９１年７月江淮流域的一次特大暴雨过程进行了数值试验。     

动力数值模式侧边界强迫的改进试验

通过修正嵌套模式侧边界缓冲区温度强迫项的计算方法,使区域气候模式所刻画的温度日变化信息与不同下垫面区域的天气变化规律相符合.进而利用数值模式ASRegCM研究了侧边界缓冲区温度强迫的改进处理对嵌套模式模拟效果的影响,并讨论了其对模拟结果改进的可能机制.数值试验结果表明,该侧边界缓冲区强迫的改进对地面气温和降水距平分布的...     

区域气候模式中侧边界地形缓冲区作用的数值试验

利用区域环境系统集成模式以1998年夏季为例,通过数值试验研究了侧边界地形缓冲区对区域气候模拟结果的影响。结果表明,设置侧边界地形缓冲区使模拟场和观测的均方根误差都有所减小,区域平均中尺度动能也减小,从而有利于维持区域模式长期积分的稳定性。设置地形缓冲区并不改变模拟降水分布格局,但对主要降水区各降水时段降水强度的模拟有不同程度的改进。     

中尺度数值模式的自适应网格设计

引进了自适应网格设计的方法。自适应网要生成行技术基础变分原理,所生成的网格具有光滑性、一定程度的正交性和机调节网格疏密程度的优点,这种新技术可任意加密局地网格,从而达到以较小的计算量获得较高的计算精度的目的。将自适应网格技术应用于ＭＭ４中,并用来模拟１９２年６月１４日这次大范围暴雨过程。结果表明,采用自适应网格后计算稳定,２４ｈ降水预报得到明显改善。     

一个人造台风方案及其在移动套网格模式中的应用

发展了一个用于台风路径预报的初始场人造台风方案。该方案除包含对称台风环流外,也考虑了非对称凤的作用。使用双向移动套网格模式作的试验预报结果表明,初始场中引入人造台风后能明显提高路径预报的水平。      

在细网格模式中引入总体边界层参数化方案的数值试验

本文把MM4模式中的总体边界层参数化方案引入到十一层细同治原始方程数值模式中去，用它与仅考虑简单边界层国擦的细网格模式对一典型江淮气旋天气过程分别作了24小时对比模拟试验；初步试验结果表明：边界层总体参数化方案的引入是可行的，对模式的预报效果在某些方面有显著改进．     

THE DETERMINATION OF COMPUTATIONAL PARAMETERS IN TYPHOON NUMERICAL MODELS

Optimal computational parameters are determined through comparisons of typhoon track for similarity relevant to vdrious sets of computational parameters using a simple quasi-geostrophic barotropic vorticity equations model. The result: the Poisson equation is solved for numerical solutions at an iterative accuracy of 1.0 × 10^-4 and a time step of 20 min.     

冬季乌拉尔山月平均阻塞形势的统计分析和数值试验

根据冬季（１２，１，２月）乌拉尔山地区月平均阻塞形势集中出现的范围和强度定义了一个阻塞指数。相关分析表明：乌拉尔山月平均阻塞与中国月平均气温有较大的负相关关系；它和全球海表温度之间存在三个明显的高相关海区；北太平洋热带东部海区，北大西洋热带和中纬度海区以及阿留申群岛西南方的海区。应用两层原始方程谱模式，在以上３个海区上空加入理想的非绝热孤立热源强迫分别做数值试验。结果表明：３个海区上空的非绝热孤立     

A REVIEW OF THE ANALYSIS OF MOISTURE VARIABLES AND THE APPLICATION IN NUMERICAL MODELS

The application of the explicit microphysical process in the high-resolution mesoscale numerical models makes it necessary to analyze the moisture variables such as the cloud water, cloud ice and rain water to initialize the explicit predicted fields. While the inclusion of moisture variables in initial fields can influence the whole performance of the model significantly, it can also reduce the spin-up time and increase the short-term forecasting ability of the model since the dynamical fields become more accordant with the thermodynamic fields. Now the increase of the observing ability and the abundance of the data promote the development of ways to analyze the moisture variables. A review of some methods to analyze the moisture variables is presented, and the situation and problems of the application in the numerical models are also discussed in this paper.     

极冰气候效应的数值试验

利用一个大气环流模式（ＡＧＣＭ）和一个全球耦合海气模式（ＣＯＡＧＣＭ）,模拟了北极海冰边界范围的变化对月平均气候的影响。结果表明,极冰边缘的异常完全可以改变中高纬度某些地区的局地气候。受冷源的影响,北半球中高纬度冷高压加强,低纬度暖高压减弱。同时利用一个全球三维大气环流模式,作了海冰反照率参数化的数值试验,用两种不同的海冰反照率参数化方案,检验对地表面温度、海平面气压、极地表面对太阳辐射吸收的影响。模拟试验表明了冰雪圈反照率的反馈作用,对气候变化的影响十分重要。     

NUMERICAL EXPERIMENTS IN SYMMETRIC AND ASYMMETRIC MOTIONS IN THE BAROTROPIC PRIMITIVE EQUATION MODEL ATMOSPHERE

Three numerical experiments have been carried out by using a spectral barotropic primitive equation mo-del.It is found that the results obtained are quite similar to those with the barotropic filtered model.Themain results read as follows:(1)In the case with symmetric orography or without orography,if the motion is symmetric(with re-spect to the equator,the same is true hereafter)at the initial instant,then it would be symmetric afterwards.(2)The antisymmetric orography distribution could cause antisymmetric motion,and the original sym-metric motion might become asymmetric.In order to explain the above results,it has been proved that they are theoretically valid.And it is foundthat if the motion is antisymmetric at the initial instant,then it would become asymmetric.Therefore,nopure antisymmetric motion could be maintained.     

NUMERICAL EXPERIMENTS FOR THE EFFECTS OF TWO MODEL INITIALIZATION SCHEMES ON RAINFALL FORECAST IN THE 2008 FLOODING SEASON

In this paper, based on heavy rain numerical forecast model AREM （Advanced Regional Eta Model）, two different initialization schemes, LAPS and GRAPES-3DVAR, are used to run assimilation experiments of AREM-LAPS and AREM-3DVAR with the same data source （NCEP forecast field, surface data and radio-soundings） during the period from 21 May to 30 July 2008 to investigate the effect of the two initialization schemes on the rainfall simulation. The result suggests that： （1） the forecast TS score by the AREM-LAPS is higher than that by the AREM-3DVAR for rainfall in different areas, at different valid time and with different intensity, especially for the heavy rain, rainstorm and extremely heavy rain; （2） the AREM-3DVAR can generally simulate the average rainfall distribution, but the forecast area is smaller and rainfall intensity is weaker than the observation, while the AREM-LAPS significantly improves the forecast; （3） the AREM-LAPS gives a better forecast for the south-north shift of rainfall bands and the rainfall intensity variation than the AREM-3DVAR; （4） the AREM-LAPS can give a better reproduction for the daily change in the mean-rainfall-rate of the main rain band, and rainfall intensity changes in the eastern part of Southwest China, the coastal area in South China, the middle-lower valleys of Yangtze river, the Valleys of Huaihe river, and Shandong peninsula, with the rainfall intensity roughly close to the observation, while the rainfall intensity simulated by the AREM-3DVAR is clearly weaker than the observation, especially in the eastern part of Southwest China; and （5） the comparison verification between the AREM-LAPS and AREM-3DVAR for more than 10 typical rainfall processes in the summer of 2008 indicates that the AREM-LAPS gives a much better forecast than AREM-3DVAR in rain-band area, rainfall location and intensity, and in particular, the rainfall intensity forecast is improved obviously.     

EXPERIMENTS ON ASSIMILATION OF INITIAL VALUES IN NUMERICAL PREDICTION OF A WARM-SECTOR PRECIPITATION IN SOUTH CHINA

In order to understand the impact of initial conditions upon prediction accuracy of short-term forecast and nowcast of precipitation in South China, four experiments i.e. a control, an assimilation of conventional sounding and surface data, testing with nudging rainwater data and the assimilation of radar-derived radial wind, are respectively conducted to simulate a case of warm-sector heavy rainfall that occurred over South China, by using the GRAPES_MESO model. The results show that (1) assimilating conventional surface and sounding observations helps improve the 24-h rainfall forecast in both the area and order of magnitude; (2) nudging rainwater contributes to a significant improvement of nowcast, and (3) the assimilation of radar-derived radial winds distinctly improves the 24-h rainfall forecast in both the area and order of magnitude. These results serve as significant technical reference for the study on short-term forecast and nowcast of precipitation over South China in the future.     

华南暖区降水数值预报的初值同化试验

为了了解初值场对华南短时临近降水预报的影响,文中利用GRAPES区域中尺度模式,针对华南一次暖区暴雨过程分别进行控制试验、同化地面探空资料、nudging雨水资料和同化雷达径向风等四个模拟试验。分析结果表明：(1) 同化地面探空资料有助于改善24小时的降水落区及其量级;(2) nudging雨水资料对临近降水预报有积极影响;(3) 同化雷达径向风能使24小时的降水落区、量级得到明显的提升。这些结论为下一步的华南地区短时临近降水预报研究提供了重要的技术参考。