Abstract:The daily stational rainfall and temperature dataset from National Meteorological Information Center of China Meteorological Administration as well as the NCEP/NCAR monthly reanalysis data are used to analyze the characteristics and trends of climate rainfall events in Northeast China for the period 1956-2008. The center of precipitation is located in the windward direction of Changbai Mountains. The large and heavy rain events also happen in the same area frequently. This is in association with the terrain and the push of the northward flow of the East Asia summer monsoon. Secondly, the trace rain events are observed as morelessmore in the zonal direction, and the other rainfall events occur more in east than that of west. In the meridianal direction, more trace, light and small rainfall events occur in north whereas fewer large and heavy rain events in north. Thirdly, the decreasing of water vapor transport crossing the west and south boundary causes the decreasing of seasonal rainfall during May to September in Northeast China. Finally, the decreasing trends of trace, light and small rainfall events are significant. As the increasing of rainfall grades, the decreasing trends get less obviously. Decreasingincreasingdecreasing trends of heavy rain events are evidently shown in the periods 1956-1976, 1976-1994 and 1994-2008 respectively.

Abstract:Based on the NCEP/NCAR reanalysis data and the 30year average precipitation data from National Meteorological Information Center, in terms of the dynamic diagnosis and analysis, the heavy rainfall during June-July 2007 in the Huaihe Valley has been analyzed. The results are as follows: the vertical structure of the circulation pattern corresponded well with the precipitation in the Huaihe Valley. During the heavy rainfall, the double blocking highs, which were located in the Okhotsk Sea and Ural Mountain respectively, provided the favorable condition for the consistent rainfall. The divergence was positive in the upper level (200 hPa) and negative in the lower lever (850 hPa) of the South Asia high. The pumping of the intense field was in favor of the heavy rainfall. The South Asia high and the 500 hPa West Pacific subtropical anticyclone moved toward each other. The potential vorticity (PV) could explain the activity of the cold air clearly. Before the occurrence of the heavy rainfall, there were obvious positivePV anomalies extending from the high latitude to the low latitude. Heating revealed that the large centers of the apparent heat source and moist sink corresponded well with the heavy rainfall center of the same period of the time.

Abstract:In general, the subtropical high severe convection can be easily misforecasted. For this reason, the 19 samples of subtropical high severe convection from 1 July to 30 September during 2001-2005 in Shanghai area were analyzed and compared to the samples without severe convection when Shanghai area was dominated by subtropical high aloft. The results have shown that subtropical high severe convection occurred more frequently in the north part of subtropical high and time period mainly from noon to evening. Subtropical high severe convection happened in the condition of strong instability and strong lifting such as boundarylayer mesoscale convergence line nearby Shanghai.

Abstract:This paper has investigated the characteristics of extreme temperature change in Hebei Province for the period of 1961-2008 by using the daily temperature data from 60 stations. The results show that the extreme maximum temperature linear trend is not obvious, but with a noticeable interdecadal variation. The extreme minimum temperature has a significantly linear increased trend. The extreme cold days below -30 ℃ are in a linearly decreased trend, and the extreme hot days above 40 ℃ not in the linear change trend, but with the characteristics of interdecadal variation. The days for low temperature below -10 ℃ show a decreased trend, and days occurring in 20-30 ℃ have a significant increased trend. Apparently, the days for high temperature in -30-0 ℃ have a significantly reduced trend. In Hebei Province, frostfree period and nonfrozen period show a significant extended trend, extending 4.5 days and 4.6 days averaged for every ten years respectively. The annual averaged high, low and mean temperature are all in a significant linear increased trend, rising 0.21 ℃, 0.45 ℃， and 0.30 ℃ averaged for every ten years respectively. The increasing rate of low temperature is significantly greater than that of high temperature. The low temperature has a significant increased trend in whole Hebei Province area, while the high temperature increased mainly in the northcentral and eastern coastal parts, not obvious in the southern regions.

Abstract:At the night of July 16, 2005, the synoptic process of mesoscale convective complex (MCC) occurred in the north part of Heilongjiang Province. The severe convective weather phenomena including thunderstorm, tornado, hailstone, gust and heavy rainfall were observed. Two tornados occurred in the north part of Qiqihar within 70 minutes. The MCC is analyzed by using the Dopple radar data, the satellite data of FY2 and other relevant data. The difference is analyzed between MCC and other general heavy rainfall processes in highlatitudes. The result shows that the obvious mesocyclone can be found in the radar echoes of velocity for MCC. The tornado is generated in the developing stage of MCC. The characteristics of physical quantities show that the conditons for vapor and dynamical factors are required to be more critical for MCC than others. The terrain commonly plays an important role in the generation process of MCC in highlatitudes. At the same synoptic situation, the system evolution occurs at the lee side of the mountains.

Abstract:The 2002-2007 radar data and observations from Jiangxi were examined statistically to determine the correspondence between surface hail and the threebody scatter spike (TBSS). We have discussed its operational use as a large hail (≥19 mm) warning criterion in Jiangxi. The result indicated that TBSS as large hail indicator is of very good application significance. The probability of detection (POD) using the TBSS is 0.818. The false alarm ratio (FAR) is 0.182 for large hail. And the critical success index (CSI) is 0.692. As in the previous studies, the TBSS is an echo region aligned radially downrange from an intense reflectivity core and is usually characterized by low reflectivity and nearzero or weak inbound velocities. Spectrum widths are very broad and often noiselike. It is found almost exclusively aloft in the midlevels (4-9 km) and then to descend with hail descent. A distinct advantage of the TBSS as a warning criterion is a leadtime of up to 77 minutes. The TBSS has various appearances and occurs at different elevation with the distance changing. In brief, the TBSS is an effective large hail criterion.

Abstract:By using radar data of Longyan CINRAD/SA from 2003 to 2007, the mesocyclone products were statistically analyzed.The characteristics of mesocyclones determined by person and the persistent three volume scannings and corresponding storm are mainly analyzed. The analysis shows that the mesocyclone which has more than three volumes scanings is well related with strong weather phenomena such as hail,thunderstorm, shorttime strong rainfall and so on. Based on the analysis of the typical strong weather processes, we can conclude the variation rules of the mesocyclone height and the largest shear’s height, and the correspondence relationship among the shear, the strong or weak mesocyclone and different types of strong weather. Therefore, the above conclusins will provide references for forecasters to predict shorttime strong rainfall, hail, thunderstorm timely and accurately.

Abstract:Two new techniques of dynamical weight blending and trend evolving superimposing have been proposed based on radar extrapolation, coordinating with numerical weather prediction as environment field. In dynamical weight blending, three ways to calculate weight are used: sine weight, hyperbolic tangent weight and realtime scrolling weight. A convective process of Shanghai and surrounding areas on 21 June, 2009 has been used as an example to analyze and examine. The result shows that after blending, the prediction results are both improved compared to radar extrapolation and numerical weather prediction. The blending results of sine weight and hyperbolic tangent weight in dynamical weight blending are more close to observations. It shows that dynamical weight blending and trend evolving superimposing are effective and feasible and of great value to the study of shortterm forecast and nowcasting.

Abstract:Based on the CINRADSB radar data of Guilin and the NCEP data, the event including series torrential rain occurring in north region and series hail storm and tornado occurring in south region between 9 to 11 November 2004 is analyzed. The results show that the flash flood occurring in Guilin City was led by an HP with bow echo. The series torrential rain occurring in north region of Guilin was led by the effect of series LEWP. There were FFNs ahead of bow echo and LEWP, which showed that there was strong southwest wind intruding into the upward current. There was RIN behind the bow echo and the LEWP, which showed that there were strong downdraft winds and the rear northerly wind. The bow echo can be used to issue flash flooding warning ahead of 20 to 33 minutes. The hail storm and tornado events which occurred in south region of Guilin lasting for two days were led by the isolated γscale supercells moving rightly. The TBSS feature can be used to issue big hailstorm warning ahead of 15 to 22 minutes. The convective cell developing to tornado was followed by cyclone divergence feature of downburst, it was very close to the time that the damage wind occurred.

Abstract:Using the sounding data of Beijing meteorological station (station ID: 54511) in the summer of 2008(1 June to 31 August) as the observed data, the sounding forecasting performances of Beijing rapid update cycle of assimilation forecast system (BJRUC) were analyzed in detail from the aspects of different levels, elements and forecast range. The results showed that the meteorological elements of the BJRUC system have a very good consistency with the real sounding results. The forecast results have better performance in the midlayer than the higher and lower layers. For different meteorological elements, the forecasting capability to the temperature and wind is superior over other elements, and the performance of the humidity is the worst. The forecasting results of the temperature, humidity and southerly wind are too big, but results of the westerly wind are too small. The forecasting performance becomes worse with the increasing of the forecast range, and the results within 12 hours initialed from 12 UTC is better especially. The forecast results of temperature and dew point temperature of midlower layer can be revised with system errors. In general, the forecasting sounding information of BJRUC has a superior performance within 12 hours, which is very useful to the veryshort range weather forecast.

Abstract:Large-area power transmission line icecoating accidents occurred in Zhejiang Province early 2008. And the upper air sounding data are used due to the lack of representative icecoating observations. The configuration of temperature and humidity factors at various altitudes in the lower atmosphere is also obtained. It reveals that combination of continuously low temperature and corresponding high humidity fits the investigation of transmission line incidents so well that it can be regarded as a basic criterion for icecoating prediction and early diagnosis. The evaluation indicates that, from middle January to early February in 2008, the continuous occurrence of low temperature accompanied by high humidity was the main factor of power transmission line icecoating accidents. In such severe air conditions, the correlation between intensity of icecoating and altitude is proved to be positive in the lower boundary layer. Comparisons with the similar historic weather records point out that, the unprecedented severe meteorological conditions resulted in the extremely severe ice-coating accidents in early 2008.

Abstract:Application of static closed chamber/GC technique to studying fluxes of CO2 and CH4 of terrestrial ecosystems can provide the necessary basis for exploring the sources and sinks of greenhouse gases in the atmosphere. Therefore, using the consistent analysis-quality control-calibration procedures and methods between the flux observation system and the atmospheric background concentration observation system is crucial. In the research, firstly, the air bags storing samples were detected and deled, including the structure analysis of airbags, testing the influence of airbags on the concentrations of CO2 and CH4 storing in the airbags in a certain period of time etc. In accordance with the testing results, some adjustments were applied in the sampling and transportation to minimize pollution of the samples; Secondly, rigorous procedures and methods that were consistent with that of analyzing and correcting the concentration of atmospheric background greenhouse gases were used to analyze the samples, ensuring the data obtained by using the two different observing methods could be accuracy compared; Finally, the optimized processes and methods in this study have been applied to greenhouse gase flux observing experiment on grazed grassland and fenced grassland at Mt.Waliguan during July 2007-July 2008. Highquality observing data of fluxes of CO2 and CH4 were obtained and a preliminary analysis of CO2 and CH4 fluxes was carried out.

Abstract:It has being more and more noticed by people that aerosol impact on city environment. On the basis of sensitivity test to the aerosol made for the planetary albedo of red, blue and nearinfrared channel of MODIS data, the aerosol optical depth over three cities, Fuzhou, Xiamen, and Quanzhou of Fujian Province is retrieved based on 6S model and dark target method by using MODIS data during 2001-2007, the precision of aerosol optical depth (AOD) retrieved from MODIS data is verified with the station observed data of air environment over Fuzhou urban during 2001-2007, the spatiotemporal distribution and change characteristics of AOD over the three cities are analyzed. The results showed that the red and blue channel data of MODIS is sensitive to the AOD, although the sensitivity of different season is variational. The relationship index between AOD retrieved from MODIS and PM10 observed from station is 0.604. It is the same that distribution of high value area of AOD is consistent with the distribution of urban, and the value of AOD in autumn and winter seasons is higher than other seasons. The remote sensing retrieval of AOD over three cities of Fujian based on MODIS data is credible, and the retrieved AOD can truly describe the spatiotemporal distribution and change characteristics over the study region.

Abstract:On the basis of sounding data at 11 stations from 1987 to 2006 in Chongqing and its surrounding areas, the spatial and temporal distribution characteristics of water vapor resources in Chongqing areas are analyzed. The results show that the water vapor content in the air is the most in summer but the least in winter. There is more water vapor content in southern and western parts of Chongqing and less in northern and eastern parts of Chongqing. The most of water vapor content is under 500 hPa level of the troposphere. The water vapor transportation is coming mainly from the west and westsouth. There is a convergence of water vapor transport in Chongqing, especially in western Chongqing. There is a great potential to the artificial rainfall enhancement in this area, especially the western Chongqing.

Abstract:In order to improve the ability to use the products of T639, the synoptic verification on its mediumrange forecasting in 2010 spring is made in comparison with the NWP of ECMWF and Japan models. The results show that the three models have good performances in the aspect of predicting the largescale circulation evolution and adjustment in Asian middle and high latitude areas. As a whole, the ECMWF model is the best in forecasting most weather systems compared with the T639 and Japan models. Taking the sandstorm process during the period of 19-22 March as a case, it is found that Japan model is more effective than the other two models in the mediumrange forecasting of strong surface wind, which causes this sand and dust weather process.

Abstract:The following are the main characteristics of the general circulation of atmosphere in May 2010. There are two polar vortex centers in the Northern Hemisphere. The circulation presents a fivewave pattern in middlehigh latitudes. The intensity of three major deep troughs are weaker than their average conditions. The subtropical high shows a belt figure. The western ridge spot of the high extends to the Indian Ocean. The monthly mean temperature (16.0 ℃) is 0.4 ℃ higher than the same period of normal years and the national mean precipitation (80.1mm) is 13.4 mm more than the same period of normal years. There are three cold air processes and three sand and dust processes in the month.

Abstract:The polarimetric radar is a useful remote sensing tool for the study of hydrometeor classification and rainfall measurement which is sensitive to the types, shapes, and size distribution of rain drops. Xband radars have additional advantages that make them a convenient tool and an appropriate choice for some practical applications. They are well suited to uses where transportability and finescale observations are important, such as in hydrometeorological studies across moderately sized complex terrain watersheds and urban basins. Anhui SunCreate Electronics Limited Company has developed a stateofthescience Xband polarimetric doppler radar on wheel based on the alternative transmission and simultaneous receiving of horizontal and vertical polarization wavelength technology in 2005, termed XPDRW. It provides such measurements as the radar reflectivity ZH, velocity (V), spectrum width (W), differential reflectivity ZDR, propagation differential phase shift ΦDP, specific differential phase shift KDP, correlation coefficient ρhv(0), and linear depolarization LDR , which are useful for the research of cloud and precipitation physics as well as the mechanism and development of disastrous weathers. This paper report: 1) the technical status and data processing system; 2) the data quality and its detection ability of XPDRW; and 3) the ability of rainfall measurement and hydrometeor classification of XPDRW. Applications are put on data collected during a series of experiments which were conducted from spring of 2006 until summer 2008. 　　 The results show that: 1) XPDRW is an actual multiparameter radar, which will provide a new kind of equipment for the development and application of polarization radar in China; 2) the features of radar observations after corrected are similar to those from foreign polarimetric radars, indicating that the XPDRW observations are reasonable and suitable for future study; 3) rainfall measurement algorithm based on XPDRW data can overestimate the heavy rain versus the traditional ZR relations, which has an advantage in practical operation; (4) fuzzy logic method based on XPDRW data can be used in hydrometeor classification, and the results are basically reasonable based on case studies. It can reveal the development course of weather system， and classify hydrometeor types, but still need to be further studied.

Abstract:The major advanced features and performances of Shanghai imported mobile Xband dualpolarized Doppler weather radar system have been described in this paper. Detailed analysis and comparisons of the radar specifications and the technical measures adopted between the imported mobile radar and the same domestic type have also been conducted in order to indicate that these super specifications and technical measures realized already in the import one are necessary and important for obtaining better qualitybased dualpolarized parameters, such as ZDR, KDP,ΦDP, ρHV etc. All those mentioned above in the imported weather radar include 200 kW peak power output, over 40 dB averaging ground clutter suppression in the IF coherence system, 95 dB to 100 dB receiver linear dynamic range and ≤-112 dBm receiver sensitivity (1 μs pulse width), with the finest 31.25m range bin resolution, innovated and patented antenna mounted receiver (AMR) technique, as well as integrated EDGE5.0 software package providing varieties of radar products. It has also illustrated some images acquired by this mobile radar from the field observation. The paper indicated finally that all the advanced aspects achieved in this imported mobile radar are worthy to be learned and followed by domestic weather radar manufacturers.

Abstract:Through the analysis of the radar data sources of clutter and the research results of radar data quality control at home and abroad, the processing method of radar data quality control has been tested and investigated. The results show that: (1) Doppler radar data quality control should use the transversal method to deal with different layer of data clutter, with the technical route of close distance transformation, long distance fold, algorithm to filter, and data complementation; (2) the identification feature is obtained from precipitation echo to ground clutter; (3) the isolated and scattering radar clutter in long distance is dealt with comprehensive methods such as mutation rate from statistics, overlying analysis of twolayer elevation angles, and improved median filter algorithm, to eliminate data clutter. However, the close radar clutter is dealt with an alternation method of polyelevation angles to wipe off; (4) introduce the data complementary conception by using data of “radar pair”, radar production data and other ones including satellite image, automatic rainfall station.