Cumulus convection and lateral boundary conditions in a limited area model     

E N Rajagopal  S S Singh 《Journal of Earth System Science》1991,100(3):235-253

Three versions of Kuo's cumulus parameterization have been tested in a limited area model to investigate their comparative performances. Results show that the version of Anthes produces better forecasts than those produced by other versions. To identify a suitable scheme of lateral boundary conditions for the limited area model, impact of two time-invariant and two time-dependent boundary conditions have been examined. The forecasts suggest that the time-dependent tendency modification scheme, based on large-scale tendencies obtained from observed data, is a better boundary scheme for the model. Furthermore, the forecast produced with the revised version of the model incorporating improved versions of Kuo's scheme and lateral boundary conditions shows an overall improvement.  相似文献   

参数化的多次散射激光雷达方程和它的反演理论 Ⅰ:方程     

邱金桓  H.Quenzel  M.Wiegner 《大气科学》1992,(5)

本文提出了一个参数化的多次散射激光雷达方程,该方程基于本文引出的四个因子,即几何消光因子、消光分布因子、前向散射因子和后向散射因子.前两个因子表征多次散射成分对大气消光系数分布、激光的发散角和接收视场角以及接收孔径的依赖关系,后两个因子表征多次散射成分对散射相函数的依赖关系.这个参数化多次散射雷达方程在241个数值试验中得以检验,这些试验包含很宽的大气条件和雷达几何参数,包括14个大气散射相函数,均匀和不均匀的大气消光系数分布,0.5至1之间变化的一次散射反照率,地基和空间站激光雷达两种情形.数值试验表明,在小于4的光学厚度内参数化的解和Monte-Carlo解之间的标准偏差小于27％,而本模式的计算时间比Monte-Carlo方法偏小4个数量级左右.本模式不仅适合于研究多次散射对激光回波信号和激光大气遥感的效应,而且对于考虑多次散射的激光大气探测而言,是一个合适的应用模式.  相似文献   

辐射雾生消的数值研究(Ⅰ)——数值模式   总被引：12，自引：1，他引：12       下载免费PDF全文

尹球  许绍祖 《气象学报》1993,51(3):351-360

本文建立了一个描述辐射雾生消过程的数值模式,预报量包括风速、温度、比湿、雾含水量及雾滴浓度等。 采用了新的雾微物理过程参数化方法及湍流交换系数公式,构造了考虑水汽、水滴对红外辐射吸收和发射及水滴对短红外辐射散射的辐射参数化计算方案。 对具有代表性的实际雾过程模拟,结果表明,模式可行。  相似文献   

A THREE-DIMENSIONAL ELASTIC NESTED-GRID MESO-(β-γ)SCALE ATMOSPHERIC MODEL——PART Ⅰ:MODEL DESCRIPTION          下载免费PDF全文

Liu Yubao  Zhou Xiuji  Hu Zhijin 《Acta Meteorologica Sinica》1993,7(3):257-272

A three-dimensional elastic nonhydrostatic mesoscale(β-γ) model with nested-grid is presented.It uses a set of full equations in terrain-following coordinates as its basic dynamic frame,which is solved with a time-splitting algorithm for acoustic and gravity waves.The model physical parameterization includes a K-theory subgrid eddy mixing for cloud and free atmosphere,a bulk planetary boundary layer parameterization,and three types of sofisticated cloud microphysics schemes with double-parameters for hail-bearing clouds,warm clouds and snowing clouds respectively.The model is designed to be used flexibly for simulations of a variety of meso-and small-scale atmospheric processes,and can be improved as a regional and local operational NWP system in future.  相似文献   

PARAMETERIZATION OF SOLAR RADIATIVE FLUX CALCULATION IN THE ATMOSPHERE          下载免费PDF全文

Zhao Gaoxiang  Wang Hongqi 《Acta Meteorologica Sinica》1994,8(1):79-88

Based on the two-stream approximation a broad-band parameterization scheme for solar radiative flux calculationis presented.The whole solar spectral region from 0.2 to 3.58 μm is divided into three broad spectral intervals.The effec-tive broad-band optical depths and single scattering albedos in the atmosphere in each spectral interval can be obtainedusing parameterized formulae from known atmospheric parameters.The overlapping scattering and/or absorption ef-fects of two atmospheric constituents are considered properly.In the consideration of radiative effect of clouds in theatmosphere the single scattering albedos and backscattering parameters of clouds in each broad spectral interval are giv-en preliminarily and the cloud optical depths are determined according to the cloud liquid water content.  相似文献   

On the bulk parameterization of snow and its application to the quantitative studies of precipitation growth     

Wojciech W. Grabowski 《Pure and Applied Geophysics》1988,127(1):79-92

Appropriate formulation of bulk parameterization of snow growth and evaporation based on observational characteristics of snow particles is presented. The parameterization is compared to that of S. A. Rutledge and P. V. Hobbs and to detailed treatment in which snow particles are assumed to grow or evaporate in each size bin separately. On the contrary to bulk parameterization of rain, snow diffusional growth or evaporation is accurately represented in the suggested bulk formulation, but growth by riming is overpredicted. Integrations of water budget equations in a one-dimensional updraft have shown that quantitative results, e.g., precipitation intensity, cloudwater content, supersaturation with respect to ice, depend on the parameterization scheme employed, which suggests that comparisons of field measurements with parameterized model outputs is usually not straightforward.  相似文献   

伊宁春季层状云和混合云降水的雨滴谱统计特征分析     

张祖熠  杨莲梅 《沙漠与绿洲气象(新疆气象)》2018,12(5):16-22

利用设在伊宁的激光雨滴谱仪获取的2013年4月的降水资料,对层状云和混合云降水粒子谱的微物理参量平均值和Gamma函数拟合结果以及Z-I关系进行对比分析。计算结果表明,伊宁地区春季降水的微物理参量普遍偏小,小滴对降水浓度的贡献达到92%以上,即降水主要以小滴为主。层状云降水的雨强、雨滴数浓度、雨滴的各类微物理特征参量的平均值均大于混合云降水。函数拟合结果表明,混合云降水的雨滴谱宽大于层状云降水的雨滴谱宽,层状云和混合云降水的雨滴谱都比较符合Gamma分布,在小滴段Gamma分布对实际谱都有一定的低估,在大于1 mm的粒径段,拟合结果有一定的偏差。还讨论了雨滴大小因子Λ和形状因子μ之间的关系以及Z-I关系,Λ-μ关系与粒子尺度有关,根据拟合的二项式得到层状云降水粒子的平均直径大于混合云降水的平均直径。  相似文献   

不同边界层参数化方案对江苏地区一次平流雾过程的模拟影响   总被引：4，自引：1，他引：3  

崔驰潇  包云轩  袁成松  周林义  焦圣明  宗晨 《大气科学》2018,42(6):1344-1362

边界层参数化方案的选取在平流雾的预报准确度上起着决定性的作用。本文利用WRF模式对2013年3月18~19日发生在江苏地区的一次平流雾过程进行数值模拟试验,对耦合不同闭合方式边界层参数化方案的试验结果与实测气象数据进行对比分析,评估了他们对此次平流雾的模拟效果,探讨了边界层高度对此次平流雾的生成和发展的影响。研究结果表明:（1）耦合不同边界层方案的WRF模式对地面气象要素的模拟结果均呈现气温偏低、湿度和风速偏大的特征。（2）QNSE方案对气温的模拟能力最强;ACM2方案对相对湿度的模拟性能最好;YSU方案对风速的模拟效果最佳。不同边界层方案的模拟结果在垂直方向上的差别主要表现在低空相对湿度上:QNSE方案预报的湿度更大。（3）综合TS（Threat Score）和BS（Bias Score）两个评分指标来看,ACM2方案对雾区分布的模拟效果最好。三个边界层方案对此次平流雾的模拟结果在江苏沿海站点的预报评分较高,在距海较远站点的预报评分表现较差。YSU方案对东南沿海地区的雾区预报评分较高;QNSE方案对长江沿江区域的雾区预报评分较高;ACM2方案对沿海地区、尤其对沿海北部地区的有较好的预报效果。（4）QNSE方案对此次平流雾的生成时间、出现地点预报比较准确。（5）平流雾的生成与发展阶段模拟雾区覆盖范围与边界层高度关系十分紧密,适当强度的湍流混合作用有助于平流雾在地面的生成与发展;但是过强的湍流混合作用会导致大雾过早的消散。  相似文献   

Evaluating and Improving Wind Forecasts over South China: The Role of Orographic Parameterization in the GRAPES Model     

Shuixin ZHONG  Zitong CHEN  Daosheng XU  Yanxia ZHANG 《大气科学进展》2018,35(6):713-722

Unresolved small-scale orographic(SSO) drags are parameterized in a regional model based on the Global/Regional Assimilation and Prediction System for the Tropical Mesoscale Model(GRAPES TMM). The SSO drags are represented by adding a sink term in the momentum equations. The maximum height of the mountain within the grid box is adopted in the SSO parameterization(SSOP) scheme as compensation for the drag. The effects of the unresolved topography are parameterized as the feedbacks to the momentum tendencies on the first model level in planetary boundary layer(PBL)parameterization. The SSOP scheme has been implemented and coupled with the PBL parameterization scheme within the model physics package. A monthly simulation is designed to examine the performance of the SSOP scheme over the complex terrain areas located in the southwest of Guangdong. The verification results show that the surface wind speed bias has been much alleviated by adopting the SSOP scheme, in addition to reduction of the wind bias in the lower troposphere. The target verification over Xinyi shows that the simulations with the SSOP scheme provide improved wind estimation over the complex regions in the southwest of Guangdong.  相似文献   

The Importance of the Shape Parameter in a Bulk Parameterization Scheme to the Evolution of the Cloud Droplet Spectrum during Condensation     

Jun ZHANG  Jiming SUN  Wei DENG  Wenhao HU  Yongqing WANG 《大气科学进展》2023,40(1):155-167

The shape parameter of the Gamma size distribution plays a key role in the evolution of the cloud droplet spectrum in the bulk parameterization schemes. However, due to the inaccurate specification of the shape parameter in the commonly used bulk double-moment schemes, the cloud droplet spectra cannot reasonably be described during the condensation process. Therefore, a newly-developed triple-parameter condensation scheme with the shape parameter diagnosed through the number concentration, cloud...  相似文献