Abstract:Concerning the empty in the ensemble based data assimilation in domestic research field, the background, theory, advantages and existing problems of ensemble Kalman Filter data assimilation method is described briefly. Meanwhile, main achievement and research status in international EnKF field are introduced. The possible developing direction of EnKF in the near future is summarized as well.

Abstract:The characteristics of cloud cluster which brought the heavy rainfall in Beijing on June 24th 2002 is studied by use of satellites and radar data. The results show that during the weakening of meso-α convective systems, they may go through the evolution of meso-β scale convective cloud cluster systems which directly led to the heavy rainfall in the west of Beijing. Numerical simulation is done on the base of observational data analysis. Low-level eastern wind converged and rose on the eastern slope of Taihang Mountain where the low-level eastern wind moving westward from the Loess Plateau also rose slantwise by effects of topographic forcing, so strong vertical ascending motion generated on the Taihang Mountain and its eastern slope a secondary vertical circulation appeared. At the same time, low-level southern wind was ascending along the south slope of Yan Mountain where the cold air brought by northern wind was subsiding on the hillside, the forthcoming of this secondary vertical circulation was the main physical mechanism leading and maintaining the heavy precipitation on the west mountainous region of Beijing.

Abstract:Based on Artificial Neuron Network (ANN) and Fuzzy theory, an efficient method of short-term load forecasting is put forward. In it, the influences of meteorological factors on load forecasting are also concerned. The method applies eight meteorological factors day by day in nine cities and corresponding load value day by day of Shaanxi Province from 1999 to 2001 to train and forecast load of Shaanxi Province. The results show that the new method can largely improve the precision of load forecasting.

Abstract:On the basis of the simulating results of the heavy rain occurred from July 29th to 30th, 1998 in the middle and lower reaches of the Yangtze River by means of MM5, the motion field structures of adjacent rainmasses are analyzed. The effect of the interaction of rainmasses of Meiyu front on their motion field structures is revealed. Due to the generation of new rainmass, and the anaflow structure of the adjacent one's changes from one kind of asymmetry to another type. The mesoscale vortex tube is wave-shaped not only in height, but also in the horizontal plane. Its wave shape in horizontal plane is associated with the location of rainmasses and the areas of strong and weak rainfall.

Abstract:The severest flood ever since 1991 stuck Huaihe valley in the summer of 2003, causing severe damages. In order to provide a better description of Huaihe valley flood's historical scenario, analysis of Huaihe valley flood's variation from 1470 to 2002 is made using precipitation data reconstructed from historical data during the pre-observational period together with the observational precipitation data. According to Huaihe valley flood's pattern compared with the allover precipitation distribution of China, especially its relationship with precipitation in Yangtze River valley and Yellow River valley, the floods of Huaihe valley can be classified to 2 main types. The first type is heavy precipitation in Yangtze River valley and Huaihe valley, rain belt mainly covers Yangtze River valley and extends to Huaihe valley. The second type is heavy precipitation in Yellow River valley and HuaiHe valley. At last the analysis of the 500hPa height fields of the 2 precipitation types is made.

Abstract:The influence to the city climate is researched quantitatively through the meteorological log in recent 70 years by the method of comparison between the urban and the suburban's. And the principle components (high, low temperature components) of air temperature are extracted by the method of the principle component analysis. The influence of the urbanization to the city air temperature in Lanzhou is analyzed quantitatively. Certainly, the cause of the air temperature change is not only by the influence of human but also by the change of the more large-scale climatic background. So, before analyzing the change of the city climate, the trend of the large-scale area climate by T-test is discussed and the variation of the region climate has the characteristic of 11-years cycle is obtained.

Abstract:Some obvious characters of Doppler radial velocity are found when Doppler radar detected the northeast cold vortex. It is simulated with the Rankine model. The result shows that the numerical model image of the northeast cold vortex is very similar to that of the Doppler radar. It is useful for forecaster that the center of the northeast cold vortex and its moving pathway will be identified according to the Doppler velocity.

Abstract:Using the tropical cyclone (TC) yearbook data from 1949 to 2000, the climatic characteristics of TC landing from the Yellow Sea or Bohai Sea are analyzed. They include the annual and seasonal distribution, evolution of intensity, tracks, genesis locations and extratropical transition (ET) of these TCs. Some facts of these TCs are almost intense, most of their ET processes occur in land and after ET the reintensified ones of them have longer maintaining periods than others. The region from north Yellow Sea to the boundary between China and North Korea as a location where these TCs' ET occurs most frequently is found.

Abstract:By using of all subjective and objective model track prediction products from different countries in operational tropical cyclone forecasting in the National Meteorological Center, verification of subjective and objective track prediction of tropical cyclones in 2002 is made. The results show that in total the subjective predictions are better than the objective, but the prediction capacity of the objective products has closed to the subjective, and is better than the subjective sometime, especially for 48-72h predictions. The results show that global models are better than typhoon models among the objective products. The results also indicate that the use of numeric tropical cyclone track prediction is helpful to improve the operational tropical cyclone forecasting.

Abstract:Based on the meteorological data of 11 years, the meteorological conditions of mud-rock flow landslip occurrence in Sichuan Basin are analyzed, and a forecasting model of mud-rock flow landslip in Sichuan basin is developed. By interpreting and applying η numerical model, a heavy rain forecasting method is studied in Sichuan basin. And a mud-rock flow landslip and η numerical model interpretation system in Sichuan basin is developed. The result is good through the operational forecast in 2003.

Abstract:A K-Neighborhood Frequency method is used to preprocess the Doppler weather radar data and its effect is analyzed, some significant conclusions are educed. In addition, the method is modified according to practical need, so its applied effect is better.

Abstract:Based on the observation data of temperature and relative humidity of 17 stations and the temperature data of 8 automatic weather stations in Shijiazhuang, by means of EOF technique, the high temperature and muggy weather distribution characteristic is analyzed. The results show that high temperature and muggy field can be composed of climatic and the first and the second characteristic fields. Cumulative variance contribution of the first two characteristic field is as much as 80%. The first characteristic field reflects the actions of latitude and height above sea level and landform, and the impact of urban heat island effects. The coefficient of the first two characteristic field are day-to-day variable, and closely correlated with wind, temperature and baric difference of latitude and longitude. They can be worked out based on weather factors from single station by regression equation. So, the method predicting high temperature and muggy distribution is developed with EOF, it is satisfactory by statistical and fitting test and trial calculation, and can be operated by actual weather forecast.

Abstract:With 37 days of high temperature and several new historical records, high temperature weather of Jiaxing in 2003 could be encountered once every 50 years no matter in duration or intensity. It shows that this resulted from remarkably strong west-Pacific Subtropic High in Jul. and Aug. and comparatively weak eddy intensity and west-wind circulation index. It's also a certain result of the climate warming. Outcome of wavelet analysis: high temp. has main periods of respectively 16- and 8- year and there was a quasi-2- year surge since 2001.

Abstract:Based on the data of monthly mean temperature from National Climate Center and NCEP/NCAR reanalysis etc, the anomalous climatic change of South China temperature is studied. Accordingly, a further study on high temperature weather in July 2003 is made. Results show that the circulation over Eurasia is remarkable difference between in high and low temperature years. The East Asian summer monsoon over tropical region is weaker(stronger) during high(low) temperature years. The temperature anomaly of South China in July bears close connection with last winter and summer SST in South China Sea, East China Sea and the central and eastern Pacific and typhoon activity in South China Sea and the Northwest Pacific.

Abstract:A large area heavy rainfall event in East China on 7 May 2003 is analyzed. Results show that the event is produced by the development and the interaction of the multi-scale weather systems under the certain large-scale circulation.

Abstract:The objective function "water ecology-economy combined index"(WEECI) is applied to linear programming to regulate the agriculture in 5 provinces in North China(Shaanxi, Shanxi, Ningxia, Gansu and Nei Mongol) based on the actual conditions in 2000. The results indicate that WEECI increased after the regulation, which effectively ameliorate the water resource shortage and improve the ecological and economical benefit.

Abstract:The water demand and supply condition of main crops, such as spring wheat, winter wheat, spring maize, summer maize, and cotton, and grassland in the growth stage in the plentiful and coarse sandy area in the Loess Plateau is evaluated with the potential evapotranspiration, actual crop evapotranspiration, water profit and loss, and water correction coefficient. It indicates that the water demand decreases by winter wheat, cotton, spring maize, spring wheat, and summer maize. And the water correction coefficient decreases by spring maize, summer maize, cotton, spring wheat, and winter wheat. Whereas the water demand in the grassland is 350-450mm, and the water correction coefficient is over 0 95, which show that the confliction of water demand and supply in the grassland is lower. Returning farmland to grassland in the region is an effective measure that can ameliorate the water resource shortage and improve the ecological environment.

Abstract:The present state of ecological environment is evaluated in the area of plentiful and coarse sand on the Loess Plateau in China with water and soil conservation effect coefficient, the difference between rainfall and evaporation and primary production capacity as the evaluation Factors. At the same time, based on regularity of climatic change for last 40 years, and the forecasting result of air temperature and rainfall for next 50 years with GCM Model of National Climatic Center, the future ecological condition in the zone is viewed. It put forward a proposal of ecological environment construction, adjusting agricultural structure: planting trees where to be good for growing trees, planting grass where to be good for growing grass and developing sand production where to be not good for growing plant. These proposals are effective ways to change the current condition on the frailty of ecological environment, lower production level, resources of unreasonable use and undeveloped potential production.