Abstract:The current in Cloud-to-Groud (CG) flash return strokes is an important feature of lightning. It’s important for improving the technology of lightning protection. Nowadays more and more data are obtained by many observing methods, including short towers, tall towers, triggered-lightning and far field-current relations. It indicates that the mean of negative first return stroke currents is 30kA, the mean of negative subsequent return stroke currents is 12kA. And the mean of positive first return stroke currents is 35kA, the value of that sometimes can be hundreds. There are some differences for the mean of return stroke currents in different regions. Measurement using short towers or tall towers is the dominating method for the direct measurement of lightning currents. Both peak values and wave shapes are different at different height. The measurements of the subsequent return stroke current for nature-lightning and triggered-lightning are similar. The indirect estimation is more and more important with the development of lightning return strokes models.

Abstract:Based on the PSU/NACR Mesoscale Model version MM5, mesoscale ensemble prediction system in the upper reach of Changjiang River is constructed by using different physics schemes. Ensemble prediction experiments and verifications for precipitation are made during 16 August to 30 September of 2004. The results show that the ensemble prediction can increase prediction accuracy of precipitation over 25mm. The experiment results of a heavy rainfall case occurring on 3 September indicate that the ensemble precipitation prediction mean might give a good clue to the starting, duration, and ending of heavy rainfall process, especially precipitation probability distribution more-than-50mm. The rainfall prediction has better guidance for area of heavy rainfall.

Abstract:The circulation patterns of the heavy rain process in Huabei area on August 1996 was analyzed. The results show that the gradient between the subtropic high and typhoon is so strong that broad southerly jet continuously transports the water vapor and the energy to the north. The Mount Taihang was just located in convergence area, so it formed the advantageous weather situation for rainstorm. Based on MM5 numerical model, in term of the synoptic principle and the potential vorticity theory, the rain process of 4-5,August 1996 was simulated and its stability was analyzed. The main results are as follows: (1) MM5 model has a good performance to simulate the typhoon rainstorm physical process. (2)In this rain process, the instability stratification in South is higher than that in North, and there are symmetry instability and convection instability simultaneously. In addition, the conditional symmetric instability not only causes the circulation acceleration, but also increases the precipitation.

Abstract:Using MM5V3.5 mesoscale non-hydrostatic model, torrential rain occurring in the Shannxi Province during 8 to 9 June,2002 was simulated and analyzed. The main results are as follows: (1) Under the advantageous macroscale weather situation, the mesoscale-β system by developing along low-level-jet triggered by mesoscale-shear is the main influence system causing the heavy rainfall.(2)Furthermore,there are obvious dynamic-thermodynamic structural features in the developing phase of the mesoscale-β system. That is ,strong divergence column and intensive vorticity column are coupling developed,the intensive ascendant motion is intercoupled with saturated air column,there is a lot of accumulation of instable energy during the development of ascendant motion.MM5 model has the better performence to simulate the mesoscale systems and the torrential rainfall.So these conclusions will be helpful and provide references for the forecast of mesoscale storm rainfall.

Abstract:Based on the data of intensity fields of 714CD Radar and Doppler velocity fields and rainfall stations net established in villages and towns of Henan Province in 2005 and the data of auto-weather stations of Henan, the heavy rainfall in Henan influenced by the Typhoon “Haitang” is analyzed. The main conclusions are as follows: (1) The appearance of the heavy precipitation echoes is earlier about one hour than the mesoscale rain cluster, but the mesoscale rain cluster weakens and disappears earlier than the radar echoes of the heavy precipitation, and steady radar echoes of heavy precipitation are benefit for the form and development of the mesoscale rain cluster;(2) On the Doppler velocity fields, the existence of mesoscale system makes for the development and maintenance of heavy precipitation radar echoes ;(3)The area, influenced continually by the heavy precipitation radar echoes about 45 dBz, can produce“train effect”and lead to rainstorm even heavy rainstorm process. For the large-scale echoes of precipitation, according to the movement rules of the mesoscale rain cluster in village-town rainfall chart, the mesoscale systems in the Doppler velocity fields, such as the adverse wind area, the convergence region, the strong wind zone(low-level jet),can be analyzed to forecast correctly the heavy rainfall area and issue warning signal of the heavy rain.

Abstract:Based on the self-recording wind and Doppler radar data from May to August in 2005, a statistic analysis about the relation among the damage wind, gust fronts and convective precipitation is made. It shows that a gust front is associated with the line or arc shape echo in the reflectivity products, and convergence line in the velocity products, and the damage wind near the surface. Its moving direction and speed foreshow the convective echoes’ spread direction, strength, and temporal-spatial distribution of the damage wind. It provides a reference for the short range forecasting and the nowcasting.

Abstract:Based on the data of 20 meteorological stations from 1990 to 2004 in Beijing, the characteristics and the variations of the urban heat island effect over Beijing are analyzed, and the relationship among the air temperature, the urban heat island effect, the ground temperature and the urban-rural ground temperature difference are also analyzed. The results show that strong UHI occurred in the night, but in the daytime UHI is not obvious. As a whole, UHI intensify year by year in the night, but in the daytime it is not obvious. In the night, the higher the surface temperature is, the stronger UHI becomes, and the greater the difference in urban-rural ground temperature becomes, the higher the ground temperature is, But in the daytime, all these relations are not so obvious as those in the night. The results can be used as scientific references to the development planning of Beijing city and the protection from high air temperature disasters of Beijing city.

Abstract:Time synchronization is an important factor for operational running of meteorological satellite ground stations. time standards consist of Universal Time (UT), Atomic Time (AT) and Universal Time Coordinated (UTC). Time services could be done by short-wave radio, GPS satellite and other special instruments. Time error could lead the system running in a disharmony way, and might make the task failure partially or completely. Firstly, time transmission way and time standards used in the operational system is introduced. Secondly, time service by GPS satellite, which can be adopted to achieve the time synchronization, is also introduced. Finally, the error of the above discussed time service is analyzed. The project has been applied to operational ground system of meteorological satellite successfully and will benefit to other applications, such as radar network systems, automatic meteorological network stations and so on.

Abstract:In order to carry out the effect evaluation in drought-resistant artificial precipitation enhancement operation in time, Using the data of the artificial precipitation enhancement experiment base of the Yangtse River and the Huai River area, the effects of two artificial precipitation enhancement operations on 9th June and 3rd August,2005 are analyzed by means of the methods of area rainfall comparison analysis, regression analysis of the surface precipitation enhancement and physical testing method of precipitation enhancement effect.The results show that ideal positive effects are obtained in both the two drought-resistant operations, which added the rainfall from 120% to 140%.

Abstract:In order to improve the effect of artificial rain enhancement, an aircraft equipped with the Particle Measuring System (PMS) probed the spring precipitable stratiform clouds over Northwest China on May 28,2001. The micro-structure characteristics of the cloud system are analyzed by means of micro-physical data from the aircraft measurement,satellite cloud picture and synoptic background data, etc. The main results are as follows:(1) The super-cooled water occurred in a wide temperature range, which is favorable for artificial rain enhancement. (2)In this case, the average particle diameter is about 10～20μm, the average particle concentration is 18.3cm^-3 ,and the average liquid water content is 0.036 g·m^-3 , which is similar to the value of Xinjiang, Hebei, and Shandong Provience, etc. (3) From the 2D image we can see that the coagulation and sublimation are the main processes for ice crystal growing.

Abstract:A stepwise regression method with tropical cyclone intensity change as the dependent variable is developed on the basis of the climatology and persistence (CLIPER) forecast scheme. The predictors are involved in climatology persistence,synoptic predictors,infrared satellite data. Regression is performed on 24-,48-,72-hour forecasts for three different sea areas in Northwest Pacific. The climatology persistence predictors as important factors are chosen in regression equations, another predictors are some synoptic predictors with the dynamical forcing effect and the maximum potential intensity (MPI) which is calculated by sea surface temperature. The independence test by a jackknife procedure shows an improvement over CLIPER scheme. Infrared satellite predictors could improve the prediction accuracy on some forecast interval.

Abstract:Based on the objective rainfall verification methods, the forecasting abilities of the numerical precipitation products of T213 were analyzed and verified using numerical precipitation forecast products of T213 and rainfall observation data of 400 stations. The results show that obvious temporal-spatial characteristics exist in threat score(TS) and bias score(B) of the rainfall forecast. The light rain′s TS is the largest and its B value is the smallest. The TS and the B value in summer is better than that in the other seasons. The highest TS and the lowest B value of the moderate and the heavy rain are both in the middle and lower reaches of the Changjiang River, and then in South China. T213 rainfall forecast shows a good performance in heavy rain(snow) in Northeast and North China in spring, and in Meiyu period in the Yangtze River,and also in the autumn rainfall forecast in West China.

Abstract:Based on the analysis of spatial and temporal charactristics, the division of rainfall regions is conducted in Jiaozuo, Henan Province.The precipitation systems(trough line,shear line,etc.) are recognized with computer in T213’s wind forecasting fields, and the systems strength index of 7 forecasting stations are confirmed on their opposite location. By combining predictors, the judging equations are established for giving the rainfall scale in 0—12 hours and 12—24 hours periods.The results show that the method is capable of forecasting rainfall regions.

Abstract:Using 850hPa mean monthly wind data, as well as data of 500hPa height, date of the Western Pacific Subtropical High ridge jumping northward to 25°N and precipitation data from June to July at 25 representative weather stations in Fujian, the criteria for the anomalous date of the subtropical high jumping northward to 25°N are defined and the anomalous years are found, the general characteristics of 850hPa wind field in June of the anomalous years are analyzed with the composite analytical method, and the effects of intensity of the Somali cross-equatorial flow on the subtropical high northward jumping to 25°N are discussed. The results are as follows: The Somali cross-equatorial flow with above-normal (below-normal) intensity in June contributes to the subtropical high jumping northward to 25°N earlier (later). The correlative coefficients between intensity of the Somali cross-equatorial flow from May to June and 500hPa heights in mid latitudes over the region from East Asia to the western Pacific are positive. The favorable circulation for the subtropical high northward jumping to 25°N earlier (later) is the higher (lower) heights in the region. Intensity of the Somali cross-equatorial flow could be a signal for predicting the time when the subtropical high jumps northward to 25°N. Based on the above results, the date of the subtropical high jumping northward to 25°N is diagnosed. It shows that the diagnosed result is correct.

Abstract:According to the meteorological observatory actual service need, it is necessary to summarize the track of typhoon going northward in all previous years and analyze the relation between the typhoon and temperature field (or thickness field) of the upper troposphere. The goal is to find out the solution of forecasting the track of typhoon going northward and make the test on typhoon Matsa in 2005, proposing that the typhoon′s hastening the warm movement is caused by the phenomenon of getting warmer in the t upper troposphere, pointing out that the extreme value curve of the upper troposphere′s hastening the warm is the track of typhoon in the future.

Abstract:Based on the evaporation data of Hotan weather station from 1961 to 2000, the Climate changes, such as annual, seasonal, monthly and the inter-decadal changes, sudden changes and so on, of the evaporation are completely analyzed. The results indicate that the seasonal and monthly evaporation present different up-trend in recent 40 years, but annual evaporation is increasing at the trend rate of 48.52mm/10a, and the increases mainly occur in spring and autumn, especially in May. in 1960s, total annual evaporation is relatively less and more in 1980s. Total annual evaporation is tested using the methods of standard Morlet wavelet analysis and accumulative anomaly curve. It indicates that there is a sudden change in 1978. There are about 4 to 6-year, 11-year or 22-year of the periods in the evaporation changes.

Abstract:Based on the computer and the general scanner, adopting the technology of picture disposure of computer, the Auto GPR1.0 system is developed to increase the measuring precision of the area of leaves. This system can pick up the noting curves according to the differences between the colore of auto-writing paper background and that of noting curves of temperature or humidity, then the computer can obtain continuous data from the values of temperature and humidity noted in auto-writing paper. In system calculation, the absolute error of temperature is less than 0.2℃, and that of humidity is less than 0.2%.

Abstract:Based on the requirement of the meteorological service of real-time monitoring drought,a calculation scheme of drought index, the drought index of the dynamic monitoring in Chongqing, is designed in consideration of three conditions including precipitation in recent time,soil moisture(preceding precipitation)and air temperature, with real-time weather informance. The index is based on the main three factors resulting the drought, which is continuous less of rainfall, higher daily maximum temperature, and less rainfall in the prior period. The operating system of the real-time drought monitoring was established based on the index, and it did well in the daily dynamic monitoring of the drought in Chongqing in the midsummer of 2004.

Abstract:Based on the meteorological data and the grass, data from 1987 to 1996 in Tiebujia, Qinghai Province, the influence of the rainfall, soil humidity,evaporation capacity on the height and yield of five dominant species of natural grass is investigated in the Tiebujia grassland, near the Qinghai Lake. The result shows that the yield ratio of Stipa purpurea,Poa crymophila, Carex aridula, Artemisia scoparia, Leymus tianschanicum and miscellaneous is 8∶15∶15∶16∶18∶28.The drought-resistance from high to low of 5 species of natural grass is Leymus tianschanicum,Carex aridula,Artemisia scoparia,Stipa purpurea , Poa crymophila. The most of grass′s critical period of water requirement is in June. It is important for the drought-resistance.

Abstract:Using the data of temperature and rainfall in Zhalantun area from 1971 to 2000, the change of active accumulated temperatures more than or equal to 0℃, 10℃, 15℃, 20℃ and the precipitation in every critical temperature continuous period are analyzed. It is found that they appear the rising tendency. Based on the method of 10-year moving average, the data of crops output in zhalantun area is disposed to separate the tendency output and the meteorological output, and calculate the correlation between various meteorological factors and the meteorological output in order to analyze the influence of the meteorological factors on output. The corn and the soybean output have well relationship to the accumulated temperature, the increasing of the accumulated temperature make the output increase. On the other hand, the correlation between potato and wheat output and the rainfall is obvious, the precipitation increasing can cause the less output.