共查询到18条相似文献,搜索用时 140 毫秒
1.
廖洞贤 《南京气象学院学报》1996,19(3):267-275
设计了一个以均匀网格差分模式为基础的变网格差分模式,如证明:如前者满足一定条件并具有质量和能量守恒性质,以及与连续情况一致的动,位能之间的转换关系,则变网格模式也同样具有,而且,把前者改变为后者增加的运算量很小,也非常方便。 相似文献
2.
文章设计了一个以均匀网格差分模式为基础的全球变网格多层原始方程差分模式。还证明了如果前者满足了一定条件,从而具有质量与能量守恒性质以及与连续情况一致的动能、位能和表面位能之间的转换关系,则变网格模式也同样具有。而且,把前者改变为后者增加的运算量很小,也非常方便。 相似文献
3.
本文基于自适应网格的原理,发展了一套网格随时间变的自适应网格模式。该模式保持着 IAP 模式原有的整体积分性质,并具有在任何时刻可随意调整网格点的疏密程度及网格点与边界相重合的特点。可用于台风路径的数值预报等方面。 相似文献
4.
5.
在国家气象中心业务运行的有限区球面均匀网格模式的基础上设计了一个有限区变网格模式。使预报的窗口区设计为均匀细网格0.5°,而窗口区以外则以0.1°经纬度均匀向外递增。采用廖洞贤1995年提出的坐标变换方法,变网格中的模式方程可以在相应的均匀网格上进行计算。利用实际资料对绝热模式进行了变网格与全场均匀细网格0.5°的对比试验。3个个例的试验结果表明:对窗口区变网格模式预报几乎与全场均匀细网格模式预报水平相当。但由于窗口区外网格点数减少而所用计算机时(CPU)节省了一半以上。 相似文献
6.
球面上斜压原始方程组保持总有效能量守恒的差分格式 总被引:8,自引:9,他引:8
本文从标准层结近似下球面上的斜压原始方程组出发,针对两类常用的网格系统——C-网格和B-网格,分别设计出可以保持总动能、总有效位能和总有效表面位能之和守恒的差分格式.同时,讨论了定义在交错网格上的差分和平均算子的一些很有用的性质. 相似文献
7.
8.
9.
E网格变量分布下差分格式的性质 总被引:8,自引:5,他引:8
本文用线性化的浅水波方程系统地分析、讨论了E网格变量分布下差分计算的性质;指出了目前有关讨论E网格差分性质在方法上存在的问题;给出了一种解决E网格中两个C网格分离的方法;提出了一种E网格用于海洋计算时,海洋侧边界条件的处理方法。初步的数值试验证明了这些方法对抑制E网格中的计算躁声是有效的。 相似文献
10.
气候和天气数值预测本质上都需建立在离散空间的基础上,并要求有高精度的空间离散化计算方案。然而,解析性微分算子和离散性差分算子的差异却是造成数值计算的原始误差源。作根据约束性代价函数原理提出了能够使得截断误差最小化的中心差分优化算子。从最优化角度看,该算子本质上是以一种简单但却相当创新的方式尝试应用变分连续同化(VCA)技术来最小化大气模式中的空间截断误差。此外,该优化差分算子的设计不依赖于网格结构,即可应用在绝大多数Arakawa网格上,诸如非跳点网格(Arakawa-A)以及常规跳点网格(Arakawa-B,Arakawa-C,Arakawa-D)。但为了对优化差分算子精确性进行严格测定,该算子的基准试验结果是通过在截断误差最易被激发出来的非跳点网格上进行严格理论和实际数值模拟测试得到的。两的结果都表明该优化差分算子截断误差造成的数字噪音能被减小到最小量。 相似文献
11.
12.
13.
14.
15.
The purpose of this paper is to present a rigorous derivation of a model equation system for the mass and energy open precipitating atmosphere. The derivation is based on the treatment of the atmosphere in terms of three open thermodynamic subsystems consisting of cloudy air, rain water and snow, respectively. Each of the three subsystems moves with a different velocity as caused by the different fall velocities of rain and snow in comparison to the cloudy air.A basic assumption of the model consists in the neglect of the inertia terms in the momentum equation of the falling hydrometeors. It will be shown that this simplification yields additional source terms in the budget equations of the total momentum and the total kinetic energy of the system. However, the prognostic equations for the atmospheric wind field and the corresponding kinetic energy equation remain free of these source terms. The model equations strictly conserve the total mass and energy of the system. It is concluded that the combination of the barycentric velocity of the cloudy air and the total density of the system is the best choice to describe the time evolution of the atmospheric wind field. 相似文献
16.
Vegetation and climate variability: a GCM modelling study 总被引:1,自引:0,他引:1
Vegetation is known to interact with the other components of the climate system over a wide range of timescales. Some of these interactions are now being taken into account in models for climate prediction. This study is an attempt to describe and quantify the climate–vegetation coupling at the interannual timescale, simulated with a General Circulation Model (HadSM3) coupled to a dynamic global vegetation model (TRIFFID). Vegetation variability is generally strongest in semi-arid areas, where it is driven by precipitation variability. The impact of vegetation variability on climate is analysed by using multivariate regressions of boundary layer fluxes and properties, with respect to soil moisture and vegetation fraction. Dynamic vegetation is found to significantly increase the variance in the surface sensible and latent heat fluxes. Vegetation growth always causes evapotranspiration to increase, but its impact on sensible heat is less straightforward. The feedback of vegetation on sensible heat is positive in Australia, but negative in the Sahel and in India. The sign of the feedback depends on the competing influences, at the gridpoint scale, of the turbulent heat exchange coefficient and the surface (stomatal) water conductance, which both increase with vegetation growth. The impact of vegetation variability on boundary layer potential temperature and relative humidity are shown to be small, implying that precipitation persistence is not strongly modified by vegetation dynamics in this model. We discuss how these model results may improve our knowledge of vegetation–atmosphere interactions and help us to target future model developments. 相似文献
17.
Ruichao Li Jinbo Xie Zhenghui Xie Junqiang Gao Binghao Jia Peihua Qin Longhuan Wang Yan Wang Bin Liu Si Chen 《大气和海洋科学快报》2021,14(1):40-45
在气候变化背景下,活动层厚度的变化会对多年冻土区水文,生态,寒区工程等产生较大的影响.本研究利用中科院气候系统模式CAS-FGOALS-g3和陆面过程模式CAS-LSM模拟分析了活动层厚度的变化趋势和相对变化.结果表明:活动层厚度整体上呈现出增加的趋势.1979-2014年,多年冻土区活动层厚度的区域平均为1.08 m,变化趋势为0.33 cm yr-1,其变化趋势与2m气温变化趋势基本一致,相对变化范围为1%-58%,平均为10.9%.在未来四种不同的气候情景(SSP-2.6,SSP2-4.5,SSP3-7.0和SSP5-8.5)下,到2100年预计活动层厚度的相对变化分别为10.3%,14.6%,30.1%和51%. 相似文献
18.
The University of Oklahoma’s Advanced Regional Prediction System (ARPS) was used to examine the impacts of varying mean soil moisture and model resolution on the magnitude and frequency of precipitation events in the U.S. Central Plains and to determine whether modeled soil moisture and precipitation fields exhibit scale invariance using the statistical moments. It was found that high soil moisture resulted in greater precipitation amounts and a higher frequency of events, suggesting the occurrence of a positive soil moisture–precipitation feedback. The scaling analysis performed on cumulative precipitation determined that these fields did not exhibit signs of self-similarity and, therefore, statistical properties cannot be predicted at other resolutions. The scaling properties of soil moisture were highly variable in time which has important implications for the use of remotely sensed data, as scaling properties from 1 day cannot necessarily be applied to subsequent days. 相似文献