MM5在上海区域气象中心数值预报中的改进和应用

以国家气象中心数值预报产品为依托, 根据上海区域气象中心计算机资源配置情况, 用NCAR-PSU/MM5V2作为动力框架, 确定了侧边界嵌套方案、积云参数化方案和边界层参数化方案, 研制了资料分析同化方法和预报结果后处理方法及产品显示软件, 建立了上海区域气象中心第五代数值预报业务系统, 可提供华东地区138个城市每3 h一次的地面要素预报.半年多准业务运行表明, 预报效果较好, 对区域内气象台站的业务预报有良好的参考价值.     

江面平流雾的数值研究

本文利用二维平流雾模式研究了海上暖湿空气平流到长江冷水面上形成平流雾的过程,对影响平流雾形成的两个主要因子(水面温度水平梯度和平流风速)与平流雾区的关系进行了数值研究,为江面平流雾的预报提供了思路.     

RETRIEVAL OF HORIZONTAL WIND PERTURBATION FIELDS FROM SIMULATED SINGLE DOPPLER RADAR OBSERVATIONS*

The application of the single Doppler radar dataset analysis is usually confined to the assumption that the actual wind is linearly distributed or uniform locally.Following some dynamic features of convective weather,a conceptual model of moderate complexity is constructed,wherewith a horizontal wind perturbation field is retrieved directly from the single Doppler radar measurements.The numerical experiments are based on a 3-D cloud model-generated convective cell,whose radial velocity component is taken as the radar observations that are put into the closed equations based on the conceptual model to retrieve the horizontal wind perturbation field.After the initial field is properly treated,the retrieval equation is solved in terms of the 2-D FFT technique and the sensitivity to noise is examined.Finally,contrast analysis is done of the retrieved and the cloud model output wind fields,indicating the usefulness of the approach proposed in this paper.     

基于GIS的浙江省高速公路大雾灾害风险区划

大雾是影响高速公路交通安全与运营效率的最主要的灾害天气之一。基于2004—2013年浙江省68个气象站大雾观测资料、基础地理信息数据以及高速公路历史灾情数据,开展浙江省高速公路大雾灾害风险区划研究。依据自然灾害风险分析原理,构建高速公路大雾灾害风险区划指标体系,以浙江省大雾出现的频次和持续时间作为大雾灾害的危险性评价指标;以因大雾导致的高速公路交通事故率、高速公路封路频次和持续时间作为脆弱性评价指标;以高速公路客运量和货运量作为暴露性评价指标。在ArcGIS的空间信息技术支持下,采用层次分析法和综合评价方法,建立了高速公路大雾灾害风险评估模型,最终完成浙江省高速公路大雾灾害风险区划图。区划结果表明,高风险区路段占全省路段总长的15.13%,主要分布在申嘉湖高速南浔段以及嘉善段、杭州湾环线高速萧山至越城段、杭州绕城西线高速、常台高速上虞至嵊州段、诸永高速诸暨至磐安段、沪昆高速诸暨段以及柯城段。     

珠江三角洲城市群污染综合指数预报的模式方法

应用全二阶矩表示的商斯烟团模式,重点引入烟团的合并与分解及各种清除过程,并利用广州热带模式（GZTM）所提供的华南地区细网格的三维数字化流场,来计算污染物浓度的长期变化。具体先模拟计算SO2、NOx、TSP的地面浓度日变化,通过求平均得到每种污染物的日均浓度,并和对应的污染物的日均浓度二级标准比较,得到每种污染物的污染指数Pi,最后求和得出污染综合指数P,从而对珠江三角洲地区的污染综合指数作出预报。     

NUMERICAL STUDY ON THE EFFECTS OF SEA SURFACE TEMPERATURE ON TROPICAL CYCLONE INTENSITY-PART I:NUMERICAL EXPERIMENT OF THE TROPICAL CYCLONE INTENSITY RELATED TO SST Duan Yihong;Qin Zenghao;Gu dianfeng;Li Yongping, Shanghai Typhoon Institute.Shangh

In the context of a model of tropical cyclone intensity based on an improved meso-scaleatmospheric model, numerical simulation is performed of the track and intensity variation oftropical cyclones (TC) arising from sea surface temperature (SST) variation over a specified searegion. Evidence suggests that the model is capable of modeling quite welt the track and intensityof TC: SST variation leads to an abrupt change in the cyclone intensity: the response of thecyclone to the abrupt SST change lasts 8—12 h.     

夏季西太平洋副热带高压北抬过程动能变化分析

本文利用ECMWF/WMO2.5°×2.5°网格点资料,对1982年7月西太平洋副热带高压一次明显北抬过程的动能及其收支进行了诊断分析。结果表明西太平洋副高北抬过程中动能和动能收支具有明显的特征,并指出了副高北抬的可能机制及预报副高北抬的着眼点。      

Nonlinear oscillations of semigeostrophic Eady waves in the presence of diffusivity

Analyses are performed to examine the physical processes involved in nonlinear oscillations of Eady baxoclinic waves obtained from viscous semigeostrophic models with two types of boundary conditions (free-slip and non-slip). By comparing with previous studies for the case of the free-slip boundary condition, it is shown that the nonlinear oscillations are produced mainly by the interaction between the baroclinic wave and zonal-mean state (total zonal-mean flow velocity and buoyancy stratification) but the timescale of the nonlinear oscillations is largely controlled by the diffusivity. When the boundary condition is non-slip, the nonlinear oscillations are further damped and slowed by the diffusive process. Since the free-slip (non-slip) boundary condition is the zero drag (infinite drag) limit of the more realistic drag boundary condition,the nonlinear oscillations obtained with the two types of boundary conditions are two extremes for more realistic nonlinear oscillations.     

Cirrus cloud horizontal and vertical inhomogeneity effects in a GCM

Summary A set of the inhomogeneity factor for high-level clouds derived from the ISCCP D1 dataset averaged over a five-year period has been incorporated in the UCLA atmospheric GCM to investigate the effect of cirrus cloud inhomogeneity on climate simulation. The inclusion of this inhomogeneous factor improves the global mean planetary albedo by about 4% simulated from the model. It also produces changes in solar fluxes and OLRs associated with changes in cloud fields, revealing that the cloud inhomogeneity not only affects cloud albedo directly, but also modifies cloud and radiation fields. The corresponding difference in the geographic distribution of precipitation is as large as 7 mm day⁻¹. Using the climatology cloud inhomogeneity factor also produces a warmer troposphere related to changes in the cloudiness and the corresponding radiative heating, which, to some extent, corrects the cold bias in the UCLA AGCM. The region around 14 km, however, is cooler associated with increase in the reflected solar flux that leads to a warmer region above. An interactive parameterization for mean effective ice crystal size based on ice water content and temperature has also been developed and incorporated in the UCLA AGCM. The inclusion of the new parameterization produces substantial differences in the zonal mean temperature and the geographic distribution of precipitation, radiative fluxes, and cloud cover with respect to the control run. The vertical distribution of ice crystal size appears to be an important factor controlling the radiative heating rate and the consequence of circulation patterns, and hence must be included in the cloud-radiation parameterization in climate models to account for realistic cloud processes in the atmosphere.     

“2007.4.1”四川盆地强寒潮天气过程分析

利用T2131°×1°和欧洲中心实时资料,对2007年4月1～3日四川盆地区域性寒潮天气过程的环流背景及影响系统进行了分析,结果表明:500hPa乌拉尔山到贝加尔湖以东为宽广深厚的低压带,地面上巴湖附近为冷高压,此冷高压在500hPa脊前西北气流的引导下东移南压,是造成此次寒潮大风天气的主要原因;而且低空急流也对降温有一定的作用。