Construction and Validation of an Urban Area Flow and Dispersion Model on Building Scales

This paper presents a numerical model that simulates the wind fields, turbulence fields, and dispersion of gaseous substances in urban areas on building to city block scales. A Computational Fluid Dynamics（CFD） approach using the steady-state, Reynolds-Averaged Navier-Stokes（RANS） equations with the standard k-ε turbulence model within control volumes of non-uniform cuboid shapes has been employed. Dispersion field is computed by solving an unsteady transport equation of passive scalar. Another approach based on Gaussian plume model is used to correct the turbulent Schmidt number of tracer, in order to improve the dispersion simulation. The experimental data from a wind tunnel under neutral conditions are used to validate the numerical results of velocity, turbulence, and dispersion fields. The numerical results show a reasonable agreement with the wind tunnel data. The deviation of concentration between the simulation with corrected turbulent Schmidt number and the wind tunnel experiments may arise from 1） imperfect point sources, 2） heterogeneous turbulent difusivity, and 3） the constant turbulent Schmidt assumption used in the model.     

Uncertainty in Dust Budget over East Asia Simulated by WRF/Chem with Six Different Dust Emission Schemes

In this study, the dependence of dust budgets on dust emission schemes is investigated through the simulation of dust storm events, which occurred during 14–25 March 2002, over East Asia, by the Weather Research and Forecasting with Chemistry（WRF/Chem） model coupled with six dust emission schemes. Generally, this model can reasonably reproduce the spatial distribution of surface dust concentration; however, the simulated total dust budget differs significantly with different emission schemes. Moreover, uncertainties in the simulated dust budget vary among regions. It is suggested that the dust emission scheme affects the regional dust budget directly through its impact on the total emitted dust amount; however, the inflow and outflow of dust aerosols simulated by different schemes within a region also depend on the geographical location of the dust emission region. Furthermore, the size distribution of dust particles for a specific dust emission scheme has proven to be important for dust budget calculation due to the dependence of dust deposition amount on dust size distribution.     

Intra-Annual Variability of Diurnal Cycle Precipitation over China from 1960–2000

Characteristics of diurnal cycle precipitation over China are investigated using twice-daily observations by the China Meteorological Administration during 1960–2000. Characteristics investigated include nighttime/daytime precipitation amount（PA）, intensity, and frequency. Geographically, the region is separated into western and eastern China by the 110°E longitude. Our analysis shows that there generally is more night-time than daytime precipitation in western China, particularly in the Sichuan Basin. Over eastern China, the opposite holds true, particularly along the southeast coast. Regional average monthly daytime and night-time precipitation peaks in the same month for both western and eastern China. Over western China, monthly night-time precipitation is always greater than that during daytime, but the night-time precipitation frequency（PF） is only greater in non-summer（June–August） months. Over eastern China, daytime precipitation is greater than that in the night-time during the warm season（May–August） in both amount and frequency. The night-day difference（night-time minus daytime） in PA over western China is mainly influenced by precipitation intensity, while over eastern China the night-day difference in rainfall amount is mostly driven by PF.     

Intercomparison of Surface Radiative Fluxes in the Arctic Ocean

Recent satellite data analysis has provided improved data sets relevant to the surface energy budget in the Arctic Ocean. In this paper, surface radiation properties in the Arctic Ocean obtained from the Surface Radiation Budget（SRB3.0） and the International Satellite Cloud Climatology Project（ISCCP-FD） during 1984– 2007 are analyzed and compared. Our analysis suggests that these datasets show encouraging agreement in basin-wide averaged seasonal cycle and spatial distribution of surface albedo; net surface shortwave and all-wave radiative fluxes; and shortwave, longwave, and all-wave cloud radiative forcings. However, a systematic large discrepancy is detected for the net surface longwave radiative flux between the two data sets at a magnitude of ~ 23 W m–2, which is primarily attributed to significant differences in surface temperature, particularly from April to June. Moreover, the largest difference in surface shortwave and all-wave cloud radiative forcings between the two data sets is apparent in early June at a magnitude of 30 W m–2.     

气象服务文档的自动化生成

1 气象服务文档自动化生成的设计思路 目前大部分的气象信息文档以Word进行编辑和处理,并且Office软件支持各种编程语言的再开发,尤其是其自带了一套寄生式的语言VBA（Visual Basic Application）,这给编程带来了极大的便利。但是VBA功能很弱,不能脱离所依附的宿主程序环境,不能被编译为独立的可执行文件,给程序运行带来了很大的不便利。相比之下,     

Microphysical Responses to Catalysis During a Stratocumulus Aircraft Seeding Experiment over the Sanjiangyuan Region of China

This study explores the microphysical responses to a cloud seeding operation in the Sanjiangyuan region, China. The cloud seeding was performed using a zigzag flight pattern, while the detection phase was accomplished using a back-and-forth flight pattern through the top of a stratocumulus layer. Global Position System（GPS） and Particle Measuring System（PMS） data obtained during the operation are used to determine the efective cloud area before and after the operation, diferentiate the phase states of cloud particles, and analyze changes in the concentrations of liquid cloud particles and ice crystals, the evolution of the cloud particle spectrum, and the content of supercooled water. The median diameter of liquid cloud particles in the area of the cloud-seeding operation was 3.5–18.5 μm, most cloud particles observed in the 21.5–45.5-μm size regime were ice crystals, while all particles of size 50 μm and above were in the ice phase. Changes in the concentration and typical diameter of cloud particles within 36 km downwind of the cloudseeding operation did not exceed natural fluctuations in the cloud area before the operation; however, the concentration of liquid cloud particles decreased substantially in areas with high concentrations of supercooled water（concentrations of supercooled water exceeding 0.01 g m 3）. The concentration of ice crystals within the measuring range of the Forward Scattering Spectrometer Probe（FSSP） increased substantially, the water content of ice-phase particles increased, and the average supercooled water content in the cloud decreased from（68.3± 23.1）% before the operation to（34.2± 12.4）%. The efects of cloud seeding were more pronounced in parts of the cloud where the content of supercooled water was higher. Little to no efects were observed in parts of the cloud with low concentrations of supercooled water.     

重读《四十五年来我参加之中国观象事业》之后

蒋丙然老前辈是中国近代气象事业的先行者,也是主要奠基人之一。他在75岁高龄时（1957年）撰写的《四十五年来我参加之中国观象事业》一文（以下简称“蒋文”）,可以认为是一篇高度概括了他一生科学事业（主要是气象事业）的自传。它是欲知中国早期近代气象事业发展过程的人,不可不熟习的重要文献。但似有某些不足之处。     

重覆冰区30 m标准避雷铁塔荷载计算

<正>贵州地处云贵高原,介于103°37′～109°35′E、24°37′～29°13′N之间,地势西高东低,自中部向北、东、南三面倾斜,平均海拔1100 m左右,以高原山地居多。受大气环流及地形等影响,贵州省成为我国出现覆冰现象较重的地区之一。资料显示,1972     

档案证明竺老是公正的

1935年,国立中央研究院第一届“聘任评议员”蒋丙然老前辈的落选,曾引起了蒋氏父子以及某些不明真相人士的愤慨。半个世纪以后1985年11月25日蒋老的哲嗣蒋君宏先生曾在台湾写了一封7页的长信,内中有一段回忆了此事的经过,现照录于下：     

SL3 1型双翻斗式雨量传感器故障分析及排除方法

1 SL3-1型双翻斗式雨量传感器工作原理SL3-1型双翻斗式雨量传感器由上海气象仪器厂生产,用以测量液体降水量。传感器安装在室外,主要由承水器、上翻斗、汇集漏斗、计量翻斗、计数翻斗和干簧管等组成[1]。采集器安放在室内,两者用导线连接,用来自动遥测并连续采集液体降水。有     

1946年圣诞节上海空难与天气预报服务

航空天气报告和航空天气预报是飞行正常和安全的重要保证。在民航重大飞行事故中,天气因素所占的比重相当大。上海龙华机场中航（中国航空公司的简称,下同）气象台自从抗日战争胜利后重建之日起到1949年暮春中航总公司撤离上海时为止的大约三年半中,由于航空天气预报失误而致中航飞机失事的情况还没有出现过。但是,因为驾驶员处理失当致航机在执行任务时,由于天气原因而遭致重大事故,却有多起。     

新一代天气雷达发射机速调管失效判断

1 故障现象及诊断分析处理 2008年2月5日,大连新一代天气雷达（CINRAD／SC）出现无回波现象,重启雷达仍无回波,天线转动正常,可以体扫,但无探测信息。     

追述1953年一个引起暴雨的小低气压

20世纪50年代初,已经认识到冷空气的参与是长江中下游雨季（特别是梅雨季节）降水过程的必要条件。而对冷空气的来源有两种不同的看法：一种比较早的意见认为,鄂霍次克海及其附近海面来的极地海洋变性气团（mPk）,是梅雨季节降水的冷空气主要来源;因而认为梅雨锋系是极地海洋变性气团（mPk）与热带海洋变性气团（mTw）或赤道海洋变性气团（mew）交绥的结果。第二种看法,也就是后来几年的看法,认为大陆来的极地大陆变性气团（cPk）才是梅雨季节冷空气的主要来源。     

一次雷击火灾事故个例调研与分析

<正>1"6.3"乙烯厂雷击火灾事故概况2008年6月3日18:20左右,茂名地区开始转为雷暴雨天气。18:56,茂名石化乙烯厂裂解车间2号装置发生火灾,火势于当日20:30基本被控制,于21:50彻底被扑灭。火势烧毁装置的部分管线和设备,无人员伤亡,没有造成环境污染,茂名乙烯厂的     

On Prediction of Record-Breaking Daily Temperature Events

The daily maximum/minimum temperature data at 740 stations in China from 1960 to 2005 were ana-lyzed to reveal the statistical characteristics of record-breaking（RB）daily extreme temperature events in the past 46 yr.It is verified that the observational daily extreme temperatures obey the Gaussian distribution. The expected values of RB extreme temperatures were obtained based on both the Gaussian distribution model and the initial condition of observed historical RB high/low temperature events after tedious the-oretical derivation.The results were then compared with those obtained by the iteration computation of the pure theoretical model.The comparison suggests that the results from the former are more consistent with the observations than those from the latter.Based on the above analyses,prediction of future possible RB high/low temperature events is made,and the spatial distributions of maximum/minimum theoretical values of their intensities are also given.It is indicated that the change amplitudes of future extreme temperatures differ evidently from place to place,showing a remarkable regional feature：the future extremely high temperature events will have a strong rising intensity in Southwest China,and a relatively weak rising intensity in western China;while the largest decrease of the future extremely low temperature events will appear in Northeast China and the north of Northwest China,and the decrease will be maintained relatively stable in space in Central China and Southwest China,in comparison with the historical low temperature pattern.Features in the occurrence time of the future RB temperature events are also illustrated.     

The Large Scale Circulation of the Snow Disaster in Southern China in the Beginning of 2008

This study analyzed the heaviest snowfalls or icy-rainfalls occurring in southern China from January to the beginning of February 2008.The results are summarized as follows：the disaster was induced by the persistent front of warm/cold air masses in southern China,which displayed an interaction between the weather systems in higher and lower latitudes.There was an adjustment for circulation at hemisphere scale during mid January by a variation of sign of the Arctic Oscillation（AO）index from negative to positive.The long lasting precipitation well coincided with a blocking situation centered near 80°E from mid January to the beginning of February.A diagnostic analysis indicates that stationary waves with an energy dispersion accompanying the blocking high propagated from upstream region in high latitudes to the south of the Yangtze River,which formed a maintaining energy source for the cyclonic circulation in situ.This resulted in that the large mass of cold air in high latitudes could not easily invade into the south but slowly shifted southward.On the other hand,the sea surface temperature（SST）over the warm pool of the western Pacific increased with a new history record due to the effect of the strong La Nina episode,which also blocked the cold air mass from the north.The blocking high collapsed around 30 January and the energy source for the local cyclonic circulation was cut off.Thus,the precipitation in southern China ceased after 1 February.     

Effects of the Physical Process Ensemble Technique on Simulation of Summer Precipitation over China

The effects of the physical process ensemble technique on simulation of summer precipitation over China have been studied by using a p-σregional climate model with 9 vertical levels（pσ-RCM9）.The results show that there are obvious differences among simulations of summer precipitation over China from different individual ensemble members.The simulated precipitation over China is sensitive to different cumulus convection,radiative transfer,and land surface process parameterizations.These differences lead to large uncertainties in the simulation results.The standard deviation of the simulated summer precipitation departure percentage over West China is larger than that over East China,signifying that the simulated precipitation over East China has higher reliability and consistency than that over West China.The Talagr and diagram shows that the ensemble system has reasonable dispersion in the simulated summer mean precipitation over East China.The summer ensemble mean precipitation over East China evaluated by various indices is better than most single simulations.The physical process ensemble technique reduces the uncertainties of the model physics in precipitation and improves the simulation results as a whole.Further, adopting the optimized ensemble mean method can obviously improve the performance of the pσ-RCM9 model in simulation of summer precipitation over East China.     

Numerical Simulation of the Influence of Drop Size Distribution Shape on Cloud and Precipitation

At present,parameterization methods to describe cloud and precipitation processes are widely used in cloud and mesoscale models,but with different drop size distributions.When precipitation formation mechanism,weather modification technique,and mechanism of hail suppression with seeding are studied by using these models,a question that needs to be addressed is：what is the influence of different drop size distributions and related parameters on cloud and precipitation？In this paper,by using a three-dimensional hail cloud numerical model developed by the Institutes of Atmospheric Physics,Chinese Academy of Sciences, we performed numerical experiments with varied drop size distribution parameters for two hail storms,and analyzed the influence of shape parameters（ar,ai,and ag）of raindrops,ice crystal,and graupel size distributions on rainfall,hail amount,and microphysical processes in clouds.The results show that the variation of ar has no effect on precipitation formation on the whole,but affects directly the production rates for the physical processes related to raindrop.The ag variation has a less obvious effect on rainfall amount,but has a significant effect on hail amount,hailfall rate,and rainfall intensity.It impacts noticeably on the generation rate of the number and mass of ice crystal,graupel,and hail,and also to various degrees on all the microphysical processes in clouds.The ag variation also influences the growing process of the hydrometeors.The effects of the ai variation on part of the generation and growing processes of all the hydrometeors are significant,and even dramatic,such as the collection process of cloud water to rain through melting ice crystal（T CLcir）.However,for clouds located in different geographic regions,the variation of ai has different effects on precipitation,which reflects the complexity of the impact of drop size distribution on cloud and precipitation.At last,some issues about the application of cloud models are also discussed.     

Land-Sea Contrast in the Lightning Diurnal Variation as Observed by the WWLLN and LIS/OTD Data

Data from the World Wide Lightning Location Network (WWLLN) for the period 2005-2011 and data composite of the Lightning Imaging Sensor/Optical Transient Detector (LIS/OTD) for 1995-2010 are used to analyze the lightning activity and its diurnal variation over land and ocean of the globe. The Congo basin shows a peak mean annual flash density of 160.7 fl km-2 yr-1 according to the LIS/OTD. The annual mean land to ocean flash ratio is 9.6:1, which confirms the result from Christian et al. in 2003 based on only 5-yr OTD data. The lightning density detected by the WWLLN is in general one order of magnitude lower than that of the LIS/OTD. The diurnal cycle of the lightning activity over land shows a single peak, with the maximum activity occurring around 1400-1900 LT (Local Time) and a minimum in the morning from both datasets. The oceanic diurnal variation has two peaks: the early morning peak between 0100 and 0300 LT and the afternoon peak with a stronger intensity between 1100 and 1400 LT over the Pacific Ocean, as revealed from the WWLLN dataset; whereas the diurnal variation over ocean in the LIS/OTD dataset shows a large fluctuation.     

Integration of Multi-source Measurements to Monitor Dust over North China：A Case Study

The aerosol optical depth （AOD） data from the Moderate Resolution Imaging Spectroradiometer （MODIS） aboard Satellite Aqua, along with the altitude-resolved aerosol subtypes product from the Cloud-Aerosol LIdar with Orthogonal Polarization （CALIOP）, as well as surface PM 10 measurements, were utilized to investigate the dust activities common in springtime of northern China. Specifically, a dust storm episode that occurred over the North China Plain （NCP） during 17-21 March 2010 was identified. The PM 10 concentration at Beijing （39.8 °N, 116.47 °E） reached the peak value of 283 μgm -3 on 20 March 2010 from the background value of 15 μg m-3 measured on 17 March 2010, then dropped to 176 μgm-3 on 21 March 2010. Analysis of the CALIOP aerosol subtypes product showed that numerous large dust plumes floated over northern China, downwind of main desert source regions, and were lifted to altitudes as high as 3.5 km during this time period. The MODIS AOD data provided spatial distributions of dust load, broadly consistent with ground-level PM 10 , especially in cloud free areas. However, inconsistency between the MODIS AOD and surface PM 10 measurements under cloudy conditions did exist, further highlighting the unique capability of the CALIOP lidar. CALIOP can penetrate the cloud layer to give unambiguous and altitude-resolved dust measurements, albeit a relatively long revisit period （16 days） and narrower swath （90 m）. A back trajectory simulation using the Hybrid Single-Particle Lagrangian Integrated Trajectory （HYSPLIT） model was performed, and it was found that the sand-dust storm originated from the Gobi Desert on 18 March 2010 travelled approxi-mately 1200-1500 km day-1 eastward and passed over the NCP on 19 March 2010, in good agreement with previous findings. In addition, the multi-sensor measurements integrated with the HYSPLIT model output formed a three-dimensional view of the transport pathway for this dust episode, indicating that this episode was largely associated with the desert source regions to the northwest of the NCP. The results imply the importance of integration of multi-sensor measurements for clarifying the overall structure of dust events over northern China.