Abstract:The two flights aerosol data sampled with Passive Cavity Aerosol Spectrometer Pr obe PCASP100X probes of an airborne Particle Measurement System ( PMS ) in Apr il 2 and April 17, 2005 over Beijing were analyzed. The result shows that the ma ximum of number concentrations of aerosol in those two days were 1422.7cm-3  and 2142.1cm-3. The mean diameters were 0.22μm and 0.25μm, re spectively. There were a strong gradient of number concentration of aerosol over Shahe Airport. Temperature inversion and other meteorological factors, such as the planet boundary layer, had important influence on the number concentration o f aerosol and mean diameter. Location also has an important impact on aerosol.

Abstract:By using daily precipitation data of Hebei Province, from 1961 to 2005 and the e xtreme precipitation indices developed by WMO/CCL and CLIVAR, the temporal and s p atial characteristics of change of extreme precipitation events in the province were analyzed. Results show that the average maximum oneday precipitation unde rgoes a decreasing trend, especially in the south of Hebei Plain, with 1980 bein g the abrupt year; Days with intensive precipitation as defined by R95%  and heav y precipitation as defined by RM日 more or less remain unchanged over the perio d analyzed, in spite of the fact that the stations of northern Hebei Plateau gen erally witness an increase, and those of the south a decrease; An obvious upward trend of days with intensive and heavy precipitation exists in late 1990s.The results indicate that average maxi mum oneday precipitation, days with precipitation and annual precipitation amo unt experience similar trends of decrease, but extreme precipitation events incl uding days with intensive and heavy precipitation see no significant change. The se imply that the proportion of the extreme precipitation events in the total pr ecipitation days, and probably the proportion of extreme precipitation amount in the total annual precipitation, might increase over period 1961-2005 in the pro vince. The increase dominantly occurs after mid 1990s.

Abstract:The intensive observations of automatic weather station, Tianjin MM5 m odel products, the NCEP 1°×1° of 6 hours analyzed data as well as conventiona l Doppler radar information are used in the weather diagnosis and mesoscale analys is for the process of a heavy rainstorm on the August 26, 2007 in the eastern re gion of Tianjin. The results show that heavy rains occurred in the largescale circulation to the zonal adjustment period. The affecting systems are the troug h on 500 hPa, the shear line on 700 hPa and 850 hPa and ground mesoscale convect ive line. The main reason of the uneven heavy rainfall distribution is obvious s cale in various physical characteristics. Ramps were formed over air flow of the storm zone which led to stable development of a strong thunderstorm cloud, at the same time the easterly storm on ground transmitted a lot of water vapor. The existence and maintenance of the groundmesoscale convergence line not only enhance he convergence uplift, but also cause the current to the largescale s torm in the system and trigger conditions. The obvious train effects in Doppler radar map, as well as correspondence between extended height of heavy echo and i ntraday zero height are the main reasons for the heavy rainfall.

Abstract:Based on the characteristics of hailing, characteristics of atmospheric circulat ion, physical quantity conditions, storm source and characteristics of radar ech o, five hailing processes in Zhangjiajie in 2005 were analyzed by using the NCE P reanalysis data, conventional data and ECMWF forecast products. The result sho ws that the hailing areas are distributed respectively in spots, lines and plane s, and the direct economical losses caused by different types of hailing processes have a significant positive correlation with the disaster stricken ar ea and disaster stricken population amount. The five hailing processes occur un der the typical upper air trough and northeast vortex hailing circulation backgr ound respectively, whereas those hails occurred in the upper air trough circu lation influence a larger area with greater destruction. Favorable hydrometeor c onditions, convective instability conditions and strong vertical wind shear prom ote the generation and development of strong convection synoptic processes. All the five storms occur in the location with a large gradient of topography, an d concentrate around mountains and the windward slopes in south of the mountain ous area, which means that the thermodynamic effect and landform play a critical role in the generation of storms and the development into hail cloud. All the h ailing processes have the characteristics of typical hail cloud radar echo, and the large hails with a diameter of about 2cm are generated during the four hai ling processes with the storm body VIL density of more than 4g?m-3, which means that VIL density has a significant indicating function for large hails.

Abstract:On April 20,2005, a mesoscale deformation field structure in cold vertex was fou nd in the Doppler velocity picture which showed a symmetrical structure. Frontog enesis was usually caused in the deformation field which could be found timely i n radar observation with high spatialtemporal resolution. By using the realti me radar data, satellite image and conventional data. the synoptic process was a n alyzed. It indicated that the deformation field played an important role in the course of development of the cold vortex.

Abstract:The spatial and temporal features and circulation characteristics of summer prec ipitation anomaly in Sanjiangyuan are investigated on the basis of the monthly r ainfall data at 14 stations from 1961 to 2005. The results show that the spatial distribution of summer precipitation has a good coherence in Sanjiangyuan, and on the whole has decreasing trend in the last 45 years. In addition, Morlet wave let analysis indicates that there were quasitwoyear, quasifourtosixy ear periodi c oscillations in the summer precipitation, and three sudden changes in the year s of 1968, 1979 and 1986 respectively. The above results indicate that the wet/d ry years of climate in Sanjiangyuan are closly related with the height field, temperature field, and w ind field, the relations can obviously be as factors for precipitation’s foreca st.

Abstract:In order to understand how urban development changes the variation of wind speed s,using the data of upper air and surface wind speed observed from Xingtai, Zhan gjiakou and Laoting, Hebei Province, from 1971-2006, the characteristics o f variation of wind speeds at altitudes of 10m (surface), 300m, 600m and 900m are analyzed. The similarities and differences of wind speed changes between the dif ferent altitudes of boundary layer are compared. Results indicate that annual an d seasonal mean wind speeds of the three stations all increase with height; The maximum wind speed vertical increasing rate appears between 10m and 300m; Monthl y mean wind speeds at different altitudes for each station have the obvious char a cteristics of seasonal variation, with the largest wind speed occurring in sprin gtime, and the smallest one in summertime; Surface annual and seasonal mean wind speeds for the 3station average undergo a significant decreasing trend during the past 36 years; Wind speeds at altitudes from 300m to 900m also see a decrea sing trend generally, but the trend is mostly insignificant statistically. Combi ned with the metadata of observational settings, it seems that the obvious diffe rence of wind speed change between the different altitudes is attributable to th e fast urbanization and the change of observational environment, which cause the slowdown of surface wind speed at the three stations. However, the change in at mospheric circulation might also contribute to the significant decrease of surfa ce wind speed, because the wind speed at altitudes of 300m to 900m experiences t he weakening trends during the same time period, in spite of the fact that the u pperlayer trends are generally insignificant.

Abstract:Based on the meteorological tower data obtained from Jiangsu and Jilin in 2005-2 006, the characteristics of average wind profile are analyzed， and a new method for estimating mean wind energy density in different height is investigated. Th e results show that the average relative error of this method is 4.4%， while th e largest relative error is 13.3%, so this method for estimating the variation o f wind energy with height is usable.

Abstract:Based on the 677 stations daily observation data（1954—2003）of frost in China as long and new as possible, which were processed by the National Meteorology In formation Center, the distribution of the frost days in China is analyzed, the s patialtemporal trend of regional frost days and the interdecadal variation f eatures are obtained, and the response of frost to global warming is further dis cus sed. The results indicate an obvious reduction trend of frost days in the whole China, especially in 1990s. We can also find that the earlier last frost day and the later first frost day are related with the rising daily minimum temperature and ground temperature, which will possibly cause the reduction of frost season .

Abstract:The data of minidish evaporation in eastern Xinjiang from 1961 to 2001 and the meteorological factors which influence on the evaporation were analyzed. The re sult shows that evaporation is in decrease trend in eastern Xinjiang, increasing from 1970s to early 1980s and decreasing from middle 1980s to 2001 are abrupt c hange. The determinations of six kind of meteor ological factors to evaporation orderly are relative humidity, vapor pressure, t em perature, wind speed, sunshine hours, net earth surface radiation, the synerg ism of wind speed and sunshine hours, relative humidity and vapor pressure, tem perature and vapor pressure, temperature and relative humidity are also affects on the evaporation intensively. Relative humidity increases evidently in recent ly years, this is the main reason which leads to the evaporation reduction yearl y.

Abstract:Based on available observation data from 721 meteor ological stations for the period from 1961 to 2007, the temporal and spatial distribution characte ristics of hazes in China were analyzed. Preliminary results show that haze s occurred mainly in eastern China (east of 100°E) and southern China (south of 42°N), with some obvious highincidence centers called generally as “muddy isla nd”. Hazes occurred frequently in winter, and not inclined to happen in sum mer. In the past 47 years, hazes in China on the whole increased with a linear t endency of 3.19 days per decade and two abrupt change points, respectively i n th e mid 1970s and after the year of 2000. During 1961-1975, hazes in China were l ess than the average, keeping negative phase, then fluctuated in weak positive p hase from 1976 to 2000. In recent 5 years, 〖JP2〗hazes were increasing quickly. The correlation coefficients, interannual scale, between hazes and t wo wind force indices (i. e. the number of days with wind force f≥5 m/s and f≥ 10 m/s) are -0.809 and -0.734 respectively. These significant negative corre lations explain that the change of wind dilute ability for air pollution does ex ert obvious influence on tendency of hazes.

Abstract:By using the conventional meteorological data of 125 stations and dividing 5 dur ations from 1959 to 2005, the drought risk assessment in Yunnan Province was con ducted with the fuzzy information theory and overlimit probability principle. The establishment of synthetic drought index was mainly based on the Thornthwait e drought index and supplemented by selfdefined effective precipitation index. The results showed as follows: the most drought risk period is in January to Ma rch every year; the probability of drought in most area is 60%～100%; the heavy drought probability is 20%～60% with some area of 90%. The drought risk in Nove mber to December is in the second place. The drought probability in most area is 30% ～60%; the heavy drought probability is 20%～60%. There is mostly no drought ris k in June to August. The drought probability is less than 5% in September to Oct ober and there is no heavy drought at all. The drought probability is 10%～20% i n April to the first ten days of June in about half area of Yunnan, 20%～40% in the area of 29%, 40%～80% in the area of 21% and the heavy drought risk is less than 5%.

Abstract:Based on the NCEP data (1°×1°) and conventional observation data, a utomatic meteorological observing station and Doppler radar data, the forecast o f the transformation between the rain and the snow as well as the cause of phase transformation in precipitation in one of strong cold waves happened during the early spring in Hebei Province is analyzed. As a result, the easterly wind brou ght by the Mongolia high and the JiangHuai cyclones below 850hPa make the temp erature of the lower atmosphere decrease, when the height of the 0℃ atmospheric layer is lower than that of the 950hPa, the character of precipitation will cha nge from rain to snow. Also when the wind directions at both the high and low levels turn from northeast to north west along with the JiangHuai cyclones moving into the sea and the temperature at the low level around the east of Taihang Mountain becomes rising slowly with the 0℃ atmospheric layer going upper, the snow will turn to be rainfall. According to the echo characteristics of Doppler radar , when the height of the 0℃ layer bright band decreases quickly, the snow will change into rainfall. While the temperature of the 1000 hPa layer goes down to 2 ℃ and the temperature of the 925 hPa layer goes down to -2℃, the precipitation will change from rain to snow.

Abstract:The causes of geological hazards are rather complex due to many influence factor s, but they are mainly triggered by the change of weather conditions and affecte d by geological and geomorphic conditions. Taking Jinhua area as an example, on the basis of investigation about the geological and geomorphic conditions especi ally in the disaster zone, four gridregions with different geological hazards hiddenrisk level are plotted out. The finegrid forecast model of geological hazards is tested to be reliable, which is based on BP neutral network and rain fall data from mesoscale observation system. The method is proved to fit in with scientific rule and can contribute to increase the forecast precis ion. The forecast model will provide a tool for reducing the damage of hazards i n this area.

Abstract:The identification, tracking and earlywarning system for thunderstorm cloud clusters based on Doppler weather radar measurements is one of the most i mportant weather prediction techniques in weather nowcasting service. A newly de veloped automatic tracking and recognition system for thunderstorm cloudcluste rs (TRACER) presented in this study is based on pattern recognitions of cloudc lusters to identify and topoloze their borderlines to establish their lifecycles , and then to make shortterm predictions of their movements. This system incl udes three primary components: (1) identification of thunderstorm cloud clusters based on their bor derlines; (2) establishment of the ancestry of each thunderstorm cloud cluster using six distinct indices: quad tree, overlap, size, external re ctangle covering the cloud, pattern similarity, partial pattern similarity; and (3) linear extrapolation prediction of their propagation, speed, size, maximum e cho center and status (e.g., strengthening or weakening, and expending or shrink ing). Preliminary results demonstrate that this system can accurately identify and predict thunderstorm cloud clusters. In cooperated with a GIS system, TRACE R can display the geolocation, trajectory, evolution of any targeted cloud clu ster and its predicted status. In addition, this system could be used to quanti tatively analyze and evaluate the predictions of any cloud clusters.

Abstract:Being a kind of highly effective information, weather forecast has a h ighly valuable application in society; its dimension becomes more and more exten sive, with more and more media and connection. Government and the public pay mor e attention to weather forecast nowadays. As TV being the leading media form in o ur daily life, plus public channels broadcasting weather forecast and weather in formation with highly frequency, weather information welcomes a much higher expo sure than ever before. Programs about the weather always get the highest audienc e rating. The panmedia age brings a challenge to weather program, for the distributed ef fect of focus media and multimedia. Thus, rethinking, exploring the directio nal information of weather program, optimizing the broadcasting effect of the sp ecific media, and improving the program’s harmony with audience, becomes a task we have to face in our practice.