Abstract:A heavy rain event in Oct.2000 of Hainan Island is simulated with numerical model MM5. The result indicates that the event occured at the stream convergence area of South China Sea depression and north cold air. The length of convergence area is about 800km from west to east. The convergence of warm and cold air produced the strong ascending motion, then derived the heavy rain in the large area. The precipitation in Hainan Island is a part of the event. Furthermore, the convergence area possesses the characteristics of the weak cold front.

Abstract:The characteristics of geographical distribution and season change of clouds over Northwest of China are analyzed based on the International Satellite Cloud Climatology Project(ISCCP) mean monthly data from July 1983 to December 1993. It is shown that the cloud amount distribution over Northwest of China is coherent with orographic distribution. There is the least cloud amount over the Tarim Basin, where the dominant clouds are relatively thinner in cloud layer, such as cumulus and high level clouds. There are the extremum regions of the cloud amount over the Tianshan Mountains, the Kunlun Mountains, and the Qilian Mountains, where the dominant clouds are relatively thicker in cloud layer, and relatively greater in vapor amount, such as stratus, nimbostratus, and deep convective cloud.What is worth noting is that the spatial and temporal distributions of cloud have distinguished stability and local features, which benefits to the artificial rain enhancement.

Abstract:Using the wind/temperature gradient data from the Tianjin meteorological tower, the statistical characteristics and diurnal variability of average wind and temperature profiles are analysed. Especially the wind and temperature profile characteristics under condition of stable stratification are examined. Some typical case analyses in the structure of lower atmosphere are introduced.

Abstract:Sugar solution and cooled glass slide are usually used to collect ice crystals in cloud chamber. The ice crystal counting numbers by using these two methods are compared in a small mixed cloud chamber. The results show that ice crystal number detected by glass slice is several times higher than by sugar solution. The upper and lower detecting limit of two methods are estimated. The merits and demerits, and the applied range of them are also discussed.

Abstract:The structural prediction method is introduced to the heavy rainfall forecast.The forecast of the heavy rainfall on 20 September 2001 in Chengdu City shows that the V-3θ chart provides a reliable forecast method.

Abstract:The operational conditions and effect of the artificial precipitation enhancement in Wuping County of Fujian Province is investigated by using the Doppler Radar (CINRAD) data and the routine weather analysis on 10 May 2002. The result indicates: Combined the CINDAR data with general meteorological observations, the artificial precipitation enhancement effect can be improved, and increased by 1.1×10⁸m³.

Abstract:To overcome the data problems in the Inner Mongolia area, such as the sparse and non uniform geographic distribution of observation stations as well as the discontinuous data transmission, a simple monitoring system of heavy snow related disasters has developed based on a combination of routine station reported snow depth data with satellite derived snow coverage rate. This method has mainly taken account of the influences of the snow depth and the days with accumulated snow cover over the different types of grassland.

Abstract:Base on the domestic AWS network and the computer network used in meteorological department,a solution to design real time system which can monitor the AWS network is developed and a method how to programme the real time monitorring software is introduced.For the sake of real time process needed,Winsock is used to establish TCP point to point connection which can fasten the data transmission and multithread technology is used to process concurrent events.

Abstract:Based on the observations and extremes of temperature and relative humidity of automatic weather station type 2(AWS Ⅱ) and conventional observation station during January 2001 through April 2002, their statistical results are given. It is shown that owing to systematical error of observed instrument and time difference in observation, mean daily temperature of automatic weather station is 0 2℃ lower than that of conventional observation station, mean daily relative humidity is 2% higher than that. The difference of extremes of temperature and relative humidity exists nonlinear variation. Monthly minimum temperature exists positive value change for minimum temperature being over 8℃,exists negative value change for that below 8℃. Most of the difference of extremes of monthly maximum temperature exists negative value change, which in summer is more obviously than that in other seasons. The difference of minimum monthly relative humidity with <35% appears instability but positive value change with ≥35%.

Abstract:A new sea surface temperature (SST) climatological normals during the 1971-2000 is introduced with reconstructed SST and optimum interpolation (OI) SST from Reynolds and Smith. The new climatological normals will be put into operational use for National Climate Center in 2003. The changes in the SST anomalies and seven SST indices caused by the climatology are analyzed. Furthermore, ENSO episodes since 1950 are defined by NINO3 index derived from Reynolds climatological normals .

Abstract:Med range forecast section of Central Meteorological Observatory will use new climatological normals of the period 1971-2000 from on January 1st, 2003 according to the requests by WMO. The results of normals change show the dekad precipitation of South China increases very obviously in summer (from June to August) and the dekad mean temperature of most observation stations ascends in winter (from October to April). The change of dekad mean temperature results in the abnormals descent and influences the confirmation of cold air processes.

Abstract:An composite abnormal index for the extremely heavy rain events in Guangxi area is given. It includes 4 sub indices:range of daily heavy rainfall process,duration of process,intensity of heavy rainfall,and range of extremely heavy rainfall.The events of extremely heavy rainfall during April through October are selected respectively based on the indices.

Abstract:A snowfall process, caused by a dry and cold northeast vortex southward on December 24 2001es the vortex strengthen, and offers abundant vapour. Meantime, its coastline and surrounding special topography makes great contribution to the event. This is a typical case of mesoscale system superimposed with local microscale system.

Abstract:How to use OpenMP compiler option to realize Multi threads (parallel processing) run of MM5 under Linux is introduced.The problem which may be presented when using OpenMP is discusses. The advantage of using OpenMP is also presented.