西北地区连阴雨天气分析

１９９５年初秋，西北地区出现持续１３天的连阴雨天气过程，降雨主要集中在１０５°Ｅ以西和陕南。５００ｈＰａ环流特征为乌拉尔山高压脊稳定，脊前西伯利亚维持宽广的大低压，西太平洋副热带高压南撤到３０°Ｎ后稳定，有几次东西振荡。正涡度中心的移动同降雨中心相吻合。正涡度主要在４２°Ｎ和３５°Ｎ附近东移，造成南北两个降雨中心。两个正涡度之间为负涡度区，对应相对少雨带。５００ｈＰａθｓｅ湿舌从青藏高原向北伸展，７００ｈΡａ湿舌从高原东侧伸向西北。中低层湿舌北上维持，降雨持续；湿舌减弱南退，降雨结束。     

CHARACTERISTICS OF MESOSCALE FLOOD-MAKING TORRENTIAL RAIN SYSTEM SIMULATED BY HIGH RESOLUTION LIMITED AREA MODEL—NUMERICAL SIMULATION OF A HEAVY RAIN PROCESS DURING MEIYU SEASON IN 1991

An experimental work on the transplant of high resolution limited area model(HIRLAM) isfirstly introduced into China.For the implementation,first of all is to adjust a new geographicalcoordination and to remove the instability caused by the Tibetan Plateau,the roof of the world.Then,we have applied this model to simulate a flood-making torrential rain process which occurredin the Changjiang-Huaihe River Valley in July 1991.That revealed the formation,development andmovement of a mesoseale heavy rain system which had made a disastrous flood event in the middleand lower reaches of Changjiang River Valley.The result encourages us to use the HIRLAM for the researches on the Meiyu belt,the salientfeature of precipitation of East Asia,and the numerical prediction of heavy rains in China.     

中期暴雨预报自动化系统

中期暴雨预报系统实现了从信息采集、预报制作到服务全过程自动化。中期暴雨预报方法主要有：环流分型相似预报、暴雨个例相似预报和中期暴雨预报专家系统，采用层次分析动态决策方法进行预报集成。该系统在业务预报中取得显著效果。     

华南地区MCC云图特征和成因分析

利用伪彩色数字化卫星云图资料，对１９９４年６月中旬造成华南地区特大洪涝的５次中尺度对流复合体的活动规律、形态特征进行了分析，对其在该地区不断衍生的原因作了初步探讨，得出它们的云图特征和成因。     

基于GIS的城市雨水管网优化设计模型研究

研究了ＧＩＳ技术在城市雨水管网设计中的应用问题，建立了雨水管网设计的相关模型，重点分析了两类直接影响雨水管网工程的计算模型——水力优化计算与指标再优化模型     

鄂尔多斯盆地夜暴雨多

该文用鄂尔多斯盆地及周围干旱、半干旱及沙漠地区３４个气象台站３７－４４年夜暴雨资料进行了研究，分析了鄂尔多斯盆地及周围地区暴雨的昼夜分布，给出了暴雨昼夜强度极值，重点讨论了地形对夜暴雨的作用。     

Acid Rain and Below-Cloud Scavenging in South-Western China

Major urban areas in south-western China exhibit unique air pollutionproblems due to increasing use of high sulphur-content fuels in an environmentof unfavourable topography and climate. Ambient levels of sulphur dioxideexceed the air quality objectives, and this gas is the major precursor of acidrain. Cloudwater chemistry studies are reported for urban, suburban andcountryside locations, during the period 1985–1989. Although cloudwateracidity was found to increase towards the cloud base, the acidity was muchgreater for rainwater samples collected simultaneously, and was morepronounced in urban rather than neighbouring suburban or countryside regions.The main contribution to the acidity arises from below-cloud scavenging of gasand aerosol and model calculations are able to simulate this behaviour.     

SOME REGULARITIES OF HEAVY RAIN IN XINJIANG,CHINA

The paper studied the distribution law of Xinjiang's heavy rain in time-area-depth bytheoretical expression deduced from the entropy maximum principle and found some regularities ofheavy rainfall in Xinjiang based on analyzing 32-year observational data from about 400hydrological and meteorological stations.It has practical significance for studying Xinjiang's heavyrainfall,designing water conservancy and reducing flood catastrophe caused by heavy rain.     

ON THE SENSITIVITY OF PRECIPITATION FORECASTS TO THE MOIST PHYSICS AND THE HORIZONTAL RESOLUTION OF NUMERICAL MODEL

The impacts of the enhanced model's moist physics and horizontal resolution upon the QPFs(quantitative precipitation forecasts)are investigated by applying the HIRLAM(high resolutionlimited area model)to the summer heavy-rain cases in China.The performance of the control run,for which a 0.5°×0.5°grid spacing and a traditional“grid-box supersaturation removal+Kuo typeconvective paramerization”are used as the moist physics,is compared with that of the sensitivityruns with an enhanced model's moist physics(Sundqvist scheme)and an increased horizontalresolution(0.25°×0.25°),respectively.The results show:(1)The enhanced moist physics scheme(Sundqvist scheme),by introducing the cloud watercontent as an additional prognostic variable and taking into account briefly of the microphysicsinvolved in the cloud-rain conversion,does bring improvements in the model's QPFs.Althoughthe deteriorated QPFs also occur occasionally,the improvements are found in the majority of thecases,indicating the great potential for the improvement of QPFs by enhancing the model's moistphysics.(2)By increasing the model's horizontal resolution from 0.5°×0.5°,which is already quitehigh compared with that of the conventional atmospheric soundings,to 0.25°×0.25°without thesimultaneous enhancement in model physics and objective analysis,the improvements in QPFs arevery limited.With higher resolution,although slight amelioration in locating the rainfall centersand in resolving some finer structures of precipitation pattern are made,the number of the mis-predicted fine structures in rainfall field increases with the enhanced model resolution as well.     

Wet removal of highly soluble gases

Partition, not kinetics, ultimately determines the concentration of highly soluble gases in cloud droplets. Partition equations are formulated and applied to idealized air-mass thunderclouds and precipitating stratus. Contribution to aqueous concentrations from sub-cloud scavenging of highly soluble gases is estimated at between 10 and 20% under relatively unpolluted conditions. Data indicate that evaporation can produce enhancements in concentration of as much as a factor of 3. The calculations give large-scale mean coefficients of wet removal of highly soluble gases of about 2.8×10^-6 s^-1 (4-day residence time) for air-mass thunderclouds and precipitating stratus. Removal is so effective that the mean scale heights of these gases should be decreased to 2 km or less. The criterion of high solubility in this paper is that K ^H (Henry's Law coefficient) > 10⁵ mol l^-1 atm^-1. Gases that are effectively highly soluble include HCl, HNO₃, H₂SO₄, H₂O₂, NH₃ in acid droplets, SO₂ in oxidizing droplets (and probably some light amines and sulfonic acids), but not SO₂ in the absence of oxidants, nor HCHO. A variation of removal coefficient and scale height with solubility is presented. A comparison of atmospheric NH₃ concentrations deduced from rain NH₄ ⁺ and measured directly gives reasonable agreement.