Abstract:The complex Empirical Orthogonal Function (CEOF) analysis has been extensively used in the meteorological and oceanic fields, and the key part of this method is to extract eigenvalues, eigenvectors, and complex principal components from a Hermite matrix. In previous studies, however, no one explores statistical and physical significances of the resolution of a Hermite Matrix. It is demonstrated that the eigenvalues of a complex Hermite Matrix represent variance contribution or anomalous energy, and eigenvectors have clear statistical significances and no apparent physical significances. In contrast, a complex principal component has a clear physical significance, and their real and imaginary parts are related to each other. Thus, the dimensional linear regression method can be used to extract predominant modes of vector variability.

Abstract:Aiming at the needs for highresolution daily weather data, taking Liaoning Province as an example, the spatial interpolation methods of daily weather data from January to December are studied using the ordinary Kriging, Inverse Distance Weighting (IDW), the IDW with weighting of Gradient Inverse Distance Weighting (GIDW), and spline function methods. The statistic analysis for interpolated values and estimated values are made. The results indicate that for temperature, the precision of the estimated values is the highest, and the spacedistributing trend of the interpolated result is the closest to the actual data byusing GIDW method. For precipitation, the precision of the estimated values with the IDW method is higher than those with the other methods, which is more fit for the interpolation of daily precipitation.

Abstract:A composite sounding flight was made during a shearline precipitation process in Jilin Province on 1 July 2004. The microphysical structure, precipitation mechanisms of this precipitation process are analyzed by means of the airborne Particle Measuring System (PMS) data, and the microphysical structure characteristics of the shearline precipitation cloud system and the physical mechanisms of rainfall formation are analyzed compositely. The results show that this shearline rainfall clouds mainly consist of altostratus, nimbostratus, and fractus; the average cloud droplet concentration and average cloud droplet diameter are different in three kinds of clouds; the cloud water content is distributed unevenly with increasing height; and the different parts of the clouds have different cloud water contents. The precipitation cloud system measured by PMS conforms to the concept of Bergeron seederfeeder cloud mechanism. The comprehensive analysis of cloud pictures and other sounding data shows that ice crystals mainly appeared in the upper part of altostratus or resulted from the spreading of ice crystals in cirrostratus, and feeder clouds are the central and lower parts of altostratus and nimbostratus.

Abstract:The spatial distribution characteristics of flood season precipitation are analyzed with EOF by means of the data of flood season precipitation measured by 36 meteorological stations in Shaanxi Province from 1959 to 2003. According to the distribution of eigenvectors, the precipitation distribution patterns during flood season in Shaanxi Province can be divided into three types: consistent distribution, southnorth oscillation, and more/less〖CD*2〗less/more〖CD*2〗more/less from north to south. Several good indicators for forecasting flood season precipitation are obtained through correlation analysis of the first three time coefficients of EOF and the factors such as SSTA of key areas and variation of atmosphere general circulation. These factors proved useful in predicting the spatial distribution of precipitation in flood season in Shaanxi Province.

Abstract:The climate characteristics of thunderstorms at 18 stations in Hainan from 1966 to 2005 are analyzed using the EOF (Empirical Orthogonal Function) method. The results indicate that there was a decreasing tendency in the thunderstorm frequency in Hainan from 1966 to 2005; there occurred less thunderstorms in the south coastal area and more in the north inland areas; thunderstorm days were mainly concentrated in the period from April to October with the peak between May and September; in abnormal thunderstorm years, an obvious negative anomaly existed in low latitude areas at 500 hPa from May to September; the subtropical high is relatively weak and farther east in active thunderstorm years, and vice verse in less active thunderstorm years. Kindex and TTindex are also analyzed,and the results show that they have certain prediction ability for thunderstorms.

Abstract:A analysis is made of climate change in recent 45 years by means of the temperature and precipitation data from 1961 to 2005 of the Jinghong meteorological station. The results indicate that the precipitation showed a decreasing trend (－20.72 mm per 10 years); summer precipitation decreased obviously (－24.28 mm per 10 years); spring precipitation had an increasing trend (11.18 mm per 10 years); annual mean temperature showed an inreasing trend (0.262 ℃ per 10 years), especially in winter (0.483 ℃ per 10 years). The increasing trend of annual extreme low temperature (0.545 ℃ per 10 years) is more obvious than the decreasing trend of annual extreme high temperature (－0.088 ℃ per 10 years). The recent 45 years in Xishuanbanna can be divided into cold and warm periods.

Abstract:There appeared some abnormal climatic phenomena such as extra long summer time and short autumn, less rain in Meiyu season, more high temperature days and continuous drought from summer to autumn in the Hangjiahu plain in 2006. Through analyzing the atmospheric circulation, it is found out that the subtropical high was stronger and more westward persistently in the West Pacific; the polar vortex was weaker than normal in the Northern Hemisphere; cold air activities were more northward and the zonal circulation prevailed in Asia in 2006. The regional abnormal climate relates to the abnormal season transition of atmosphere circulation. The abnormal atmosphere circulation can attribute to the early abnormal circulation. The continuously stronger subtropical high in the summer of 2006 is related to the stronger meridional circulation and continuously stronger subtropical high in the previous winter and spring, and the abnormal spring circulation led to the quick season transition from autumn to winter. The result of eddy height analysis shows that the abnormal westward movement of the positive eddy height center in the troposphere in May, the two positive centers generated in the stratosphere from June to July, and the abnormal stronger positive center in September altogether indicated and promoted the abnormal development of the lowerlevel atmospheric circulation in summer; therefore, the summer was longer and the transition from summer to autumn was put off; and the abnormal stronger, southward cold low and the sudden weakening of the warm high in November of 2005 led to quick transition from autumn to winter and short autumn.

Abstract:A severe local heavy rain occurred in the southern Shandong Province on 2 September 2004 was simulated by use of the next generation mesoscale nonhydrostatic model WRF. The causes of the heavy rain are analyzed with the reasonable simulation results. The results show that the highhumidity area in the inverted trough of a typhoon is vapor sources. The mesoscale convergence line in the lower stratosphere played a very important role. The smallscale vortex near the front is the direct cause of the heavy rain. Terrain is a trigger mechanism and the interaction between typhoon inverted trough and front enhanced the precipitation.

Abstract:The continuative fog event lasted from 29 November to 4 December 2004 is analyzed. The results indicate that the northwestern airflow and the warm and humid airflow from southwest at upper levels are important factors of the continuative fog event; the surface relative humidity was up to 94% and North China was controlled by the stable Continental High and a saddleshaped field, so there was abundant water vapor, stable stratification, and very small wind speed at lower levels, leading to the fact that water vapor could not diffuse timely; the upperlevel sinking air and lowerlevel rising air led jointly to the stable stratification, so heavy fogs occurred.

Abstract:A review is made of the main methods for observing root systems, with emphasis on the minirhizotron method used widely, and the relative merits are discussed. It is pointed out that from the needs of weather forecasting, root system observation can be used to correct the errors in land surface models resulted from the lack of the essential parameters of land processes, to improve the accuracy of regional microclimate prediction, study airground interaction, and grasp the regularity of weather variation. The research achievements at home and abroad are reviewed, and it is pointed that while selecting observation methods, the purposes and scope of a study should be considered fully, and any method has its own limitations. Before making a decision, it is necessary to understand the applicable conditions of a method, and made comparison carefully. Maybe the optimum solution is to use more than one methods.

Abstract:For identifying the influences of soil moisture on transpiration rate, comparison between calculated and observed transpiration rates, responding to different soil moisture treatment, is carried out. The results show: (1) the calculation errors of transpiration rate in scarce water supply are higher than those in sufficient water supply; (2) the modified coefficients of transpiration rate are higher in scarce water supply than in sufficient water supply; (3) the calculation errors of transpiration rate decrease sharply after the modified coefficient taking into account. Meanwhile, the modified coefficient is statistically significant.

Abstract:The yield estimate equation of winter wheat considering different growth stages is established in the multiple linear regression method by means of such meteorological and ecological factors as sunlight and heat, moisture during the essential growth period of winter wheat, which are crucial to the yield formation of winter wheat in the loess plateau area of the eastern Gansu Province, as well as growth potential, a quantitative factor indicative of growing condition. It has an accuracy of over 92% in trial use. Unlike the traditional method of using single meteorological element to predict grain yields, the new method considered ecological factors and moisture, and gained satisfactory results.

Abstract:The Overseas Crop Yield Forecast System was developed with the tools of Microsoft Visual Basic 6.0 under the Windows 9x/2000/NT platform. The system consists of such modules as data management, data processing, data calculation and analysis, average unit yield forecasting, planting area estimation, total production forecasting, etc. It can analyze the agrometeorological average unit yield, estimate planting areas, and forecast the total productions of American wheat, American corn, American soybean, Indian wheat, Indian rice, Brazilian soybean, Chinese rice, Chinese wheat, and Chinese corn. The system has a reasonable architecture and is easy to use and highly automatized. Taking American corn as an example, a description is made to this system. The biggest error of the total production forecasting of American corn from 2001 to 2004 is 8.4% (absolute value), and the average error is 2.4%. The forecasting is totally accurate for 2005. The average forecasting accuracy of the system is above 90% and it can meet the current demands of agrometeorological service.

Abstract:An analysis is made of yield components, correlation between 30year yield per unit and meteorological factors in summer (May to September) in Heilongjiang Province by means of 50year grain production data of Heilongjiang Province. The results show that the fluctuation of the total grain yield is attributed to the fluctuation of average total grain yield per unit and the structural adjustment of planting structure. Since 1949, the proportions of corn and soybean yields to total grain yield have been almost kept unchanged, and the rice yield has been increasing year by year. The spring wheat yield presented a gradually increasing trend from 1949 to 1990, but sharply decreased since 1991. The yield per unit of rice was the highest, that of corn the second, spring wheat the third, and soybean the lowest. Comparison of grain yield per unit shows that there was a gradually increasing trend for various crops. The sunshine and temperature were major meteorological factors that influence grain yields in Heilongjiang Province.

Abstract:According to the historical temperature statistical data from 1976 to 2005 in 9 counties over the eastern Fujian Province, an analysis is made of the temperature variation characteristics and the studied area is divided into several temperature types. Considering the needs of various growth periods for temperature conditions for certain edible funguses, the critical temperatures and dates (first and last dates) suitable for the growth of the edible funguses are determined, and the natural producible period for each type of edible fungus is calculated. The advantages and disadvantages in producing various edible funguses in different temperaturetype areas are analyzed in detail so to help arrange production seasons, reduce production costs, and increase the income of producers.

Abstract:Taking Cangzhon of Hebie Province as an example, based on the meteorological data from 1970 to 2005, an analysis is made of meteorological factors affecting greenhouse vegetables in winter, such as extreme minimum air temperature, winter average temperature, severe temperature drop, fog, scant sunlight, gale, heavy snow and so on. The results show that extreme low temperature and winter average temperature had an increasing trend; fog had a fluctuational decreasing trend; gale decreased obviously. These are beneficial to greenhouse vegetables. The scant sunlight exhibited an increased tend, especially after the 1990s, which is unfavorable to greenhouse vegetables. Severe temperature drop and heavy snow tended to change abnormally. In view of these variation characteristics of meteorological factors, some suggestions are presented, such as increasing light intensity, preserving heat, and strengthening capability to defense against extreme weather and climate events.

Abstract:Based on the analysis of 13year acid rain data from four monitoring spots in Jiangsu, it is concluded that the annual mean number of acid rain days, the occurrence frequency of acid rain events, and the annual mean amount of acid rainfall in Jiangsu tend to increase gradually from north to south. The frequency and amount of acid rainfall show obvious annual and seasonal variation characteristics. The number of acid rain days and the monthly variation of acid rainfall exhibit a parabolashape distribution. According to the parallel analysis of pollutant concentration and meteorological factors before acid rains, the variation regularities of pollutant concentrations and meteorological factors during acid rains in Nanjing are studied, and the favorable conditions for acid rains are summed up that the preceding pollutant concentration: NO2≥0.04 mg/m3，PM10+NO2≥0.085 mg/m3，SO2+NO2≥0.08 mg/m3; at 850 hPa, southwest winds prevail and southeast winds take the secondary place; wind velocities are less than or equals 12 m/s; there exists an inversion layer under 900 hPa. Base on these findings, the method of acid rain potential forecast in Nanjing is presented and forecast verification is conducted.

Abstract:The AgI seeding experiments using seeding aircraft were carried out to enhance precipitation at the upriver catchments of Miyun Reservoir from May to September. The regular and continuous measurements were conducted at two sampling spots located at the entrance of the Baihe River and the the reservoir, and by using of the monitoring data, an analysis is made of the temporal and spatial characteristics of water quality in the reservoir from June 2004 to December 2006. The measurements show the same chemical composition and variation trend at two sampling spots. The Ag variation characteristics of water in the reservoir were studied, and the results show that the monthly Ag concentrations changed more greatly during the seeding period; the average Ag concentrations during the seeding period were lower than those during nonseeding period; and there was a decrease tendency year after year. The chemical features are not obviously different at two sampling spots. The negative ion concentration of SO42－ in the reservoir is the highest, then Cl－；Ca and Mg have the highest concentrations in alkali metals. The results suggest that precipitation enhancement does not affect the water quality of Miyun Reservoir.

Abstract:An observational experiment was conducted on the impact of air temperature and humidity variation on soil resistivity and earthing resistance with different structures by selecting three typical soil conditions to set three varistructure lightning protecting earthing bodies in Ningxia for one year. By means of comparative and regression analysis, the impacts of different soil conditions on soil resistivity at different temperatures and humidity in different seasons, and the variation characteristics and regularities of the lightning protecting earthing bodies with different structures are studied, and accordingly the optimal requirements for the layout and structure of lightning protecting earthing bodies are presented.

Abstract:Based on the daily data of PM10, NO2, and SO2 and 08:00 synchronous synoptic data at 850 hPa from 2002 to 2006 in Fuzhou, Fujian Province, the general status of air quality, temporal and spatial distribution characteristics of pollutants, and the influence of different weather systems on pollutant concentration changes during the five years in Fuzhou are synthetically analyzed with the statistic and climate classification methods. The results show that the air quality conditions are generally good in Fuzhou and the concentration of PM10 is becoming better year by year while there is a rising trend in the annual variation of NO2 concentration. The concentrations of NO2 and SO2 over the major traffic lines of the urban area are the highest, and the concentrations of various pollutants in mountain stations are generally lower than in the urban area. Under the control of the subtropical high and the inverted trough, there will not occur pollution events in Fuzhou. The weather systems that will cause slight pollution with the probability of over 5% include the cold trough, warmzone convergence, and continental high. Under the weather condition of warmzone convergence, the occurrence probability of good air quality is the highest compared to other kinds of weather systems, while affected by a low pressure or inverted trough, the occurrence probability of excellent air quality is higher than that of good air quality.

Abstract:On the basis of the experiences and examples from thunder and lightning protection practice, the characteristics of lightning protection earthing electrodes are analyzed. The results show that reducing earth resistance is mainly through reducing the contact resistance of earthing electrodes and dispersed resistances; increasing the encircled area of a earthing electrode is advantageous to the reduction of earthing resistance; the shapes of compound earthing electrodes and the influence of screening effect in the earthing grid on earth resistance should be fully considered; the soil resistivity is affected by the soil property around the earthing body, the burying depth of earthing electrodes，and seasonal variation. The earthing electrodes are arranged along the edges of the earthing grid, and the electrodes are distributed sparsely in the grid with different earthing electrode lengths. Generally, the burying depth of a commonused earth body is between 1.5 m and 3.5 m, below the frozen earth level in North China. The frictionreducing agents with stable performance and the soil with low soil resistivity can be used around earth bodies so to reduce costs while filling the requirement for earth resistance.

Abstract:The solar energy resources of the eastern Guangdong Province and their spatialtemporal distribution characteristics are analyzed in aspects of global solar radiation, temperature, sky state and so on. The results indicate that the eastern Guangdong Province has good natural climatic conditions such as high global solar radiation, high temperature, fine sky, i.e., rich solar energy resources and superior thermal conditions, and solar energy utilization shows great potentials.

Abstract:In order to study the connection of microwave brightness temperature and precipitation, a new statistical retrieval algorithm is built by the stepwise regression method with wellmatched precipitation radar (PR) data and TMI brightness temperatures data. The results show that for the precipitation of 0.1 to 3 mm/h and 3 to 6 mm/h, the retrieved results correlate well with the retrieved precipitation from PR radar; for precipitation of 6 to 10 mm/h, the correlation is poor; and for precipitation over 10 mm/h, the correlation is well, but the rootmeansquare error is big, which means that the method can be used to predict strong rainfall centers with smaller retrieved values. With the method, the heavy rainfall process happened on 18 July 2004 is successfully retrieved. The results show that the spatial distribution of the rain belt and the location of the strong rainfall center are consistent with the retrieved precipitation from PR radar and Doppler radar.

Abstract:In order to ensure the comparability of AWS pressure sensors for insite calibration and understand the temperature characteristics of standard pressure measuring instruments, experiments were conducted at different environmental temperatures and normal pressure. Based on the calibration data in Shandong Province from 2005 to 2007, the tendency of pressure calibration errors is analyzed with the contrast method. The results show that regardless of increase or decrease of the temperature, the display values exhibited a growing trend, with the additive errors being 0.10 to 0.28 hPa, resulting in misjudgment on the performance of pressure sensors. The new calibration method proved practical in practice and can reduce or eliminate the impact of additive errors in pressure calibration results.

Abstract:Considering the relatively poor automation level of meteorological metrology management of various provinces, a new provinciallevel management server system of meteorological metrology based on the modes of Client/Server and Browser/Server was developed by using technologies such as Microsoft SQL Server Database, Microsoft Visual Basic 6.0 and ASP.NET. The management server system not only realizes information sharing and operational network management on the countrywide meteorological network, but also provides comprehensive and accurate information service for various users through the Internet. The system proved satisfactory, practical and operational.

Abstract:An intensive observation network consisting of 60 Automatic Weather Stations (AWS) with extended temperature and precipitation monitoring was completed in Zhangjiakou in 2005, and it has been worked since then during rainy seasons. In order to use the large amount of data effectively to meet the needs of various users, the system is designed to be able to deal with data query, statistics, precipitation contour drawing, data output, working status monitoring, and emergency alarm. The realization of these functions is described in detail. The system is practical, fast, and stable, can provide highquality charts, and is applicable to basiclevel stations.

Abstract:A detailed analysis is made of a prefecturelevel monitoring system of meteorological emergency service, taking the Liaocheng (Shandong Province) mobile weather station as an example, in three aspects: equipment selecting and matching, communication networking and video conferences, and construction of forecasting service platform. Meanwhile the application of the system to the fast acquisition of emergent meteorological disaster information and the effectiveness evaluation of airborne water resources utilization is discussed, so to provide useful references for improving prefecturelevel meteorological emergency service.