Abstract:Utilizing the Changsha and Changde Doppler weather radars data and other conventional meteorological data,the supercell storm occurred on 29 April 2004 associated with 10cm-diameter hail in Anxian town of Hunan has been analyzed.The supercell storm took place in the intersection of a southwest upper-level-jet and a south-southwest low-level jet,where strong thermal potential instability and vertical wind shear favored the genesis of supercell.The supercell storm had a classical hook-shape echo at its right rear extending from the low level upwards to 6km-height,and also a TBSS(three-body scattering spike) indicative of large hails.In the mature stage of the supercell storm the mesocyclone was very strong with a maximum rotational velocity of 24m·s^-1 and a vertical vorticity of 1.6×10^-2s^-1.The vertical section of reflectivity factors reveals that the supercell storm had a large BWER extending over 10km in the horizontal and 4km in the vertical.Above the BWER,there was a reflectivity core region over 70dBZ centered at 9km.This is a structure of classical strong supercell storm.The supercell storm underwent three splittings during the whole evolution.

Abstract:Using a two-dimensional spectral resolving cloud model,the effects of mineral dust particles,produced under different weather conditions,on development of cloud microphysical and optical properties and precipitation are simulated and compared with the results obtained under background aerosol conditions.The results show that dust particles raised during duststorms increase the amount of large and giant cloud condensation nuclei in the atmosphere,lead to more large droplets activated at the early stage of cloud formation,accelerate the formation of precipitation,and increase the amount of precipitation in both warm and cold clouds,while the influence of increasing in giant cloud condensation nuclei on the cloud optical properties and albedo can be neglected.The results also indicate that when sand dust acts as both cloud condensation nuclei and ice nuclei,increasing the initial concentration of ice nuclei results in a decrease in the effective radii of cloud particles,and inhibits precipitation formation.The increasing amount of ice nuclei enhances the cloud optical depth and albedo.

Abstract:A mesoscale analysis for the heavy rain at night on 12 June 2006 in Guizhou Province is performed using the surface intensified observation,rainfall of automatic weather stations,FY-2C satellite tbb,etc.Results indicate that the mesoscale convective cloud clusters and their slowly moving are the direct reason for the heavy rain.Rich water vapour transport and the accumulation of CAPE(Convective Available Potential Energy) in the mid-and low-levels provide the favorable environmental conditions for the occurrence of the heavy rain,which is probably triggered by the lifting of warm and humid airflow forced by the intrusion of weak cold air from high-and mid-levels,and the formation of mesoscale low and mesoscale convergence line.Mesoscale weather systems have the features of convergence in the low level and divergence in the high level and the vertical structure of mesoscale secondary circulations.

Abstract:In this study,the characteristics of TM images for Beijing study area are analyzed to find the spectral separability of TM’s bands for different objects,such as water,farmland,forest,grassland,concrete,cloud and shadow.An Normalized Difference Cloud Index(NDCI) is proposed to construct a simple decision tree mode with the Normalized Difference Vegetation Index(NDVI),Normalized Difference Built-up Index(NDBI),Modified Normalized Difference Water body Index(MNDWI) and slope.This model is then used to derive the information of ground objects,cloud and shadow,and the precision of results is evaluated subsequently.The areas of water body,forest,grassland and farmland are calculated under the support of GIS technology.Finally,the indexes of water body density and vegetation-cover in the autumn of 2005 in Beijing area are calculated.Results indicate that the selection of thresholds for this model is very simple and effective and the precision of model can satisfy the requirement to calculate the indexes of water body density and vegetation-cover.The results also indicate that the remote sensing technology can be used effectively in evaluating the quality of ecological meteorology.

Abstract:A 3-D convective cloud SBM model has been developed on the basis of the IAP 3-D hailstorm numerical model and the 2-D slab-symmetric model with spectral bin microphysics(SBM),and the real supercell storm case occurred on 29 June 2000 in Kansas simulated.Simulation results with the 3-D convective cloud SBM model are compared with those with the IAP 3-D hailstorm numerical model,which indicates that the updraft velocity obtained from the SBM model depicts the two observed updrafts well;and the strength,height,and width of radar echo simulated by the SBM model are closer to the observations than the IAP 3-D hailstorm numerical model.

Abstract:The predictors are the surface temperature over the Eurasian continent,500hPa heights over the Northern Hemisphere,SST(sea surface temperature)over the tropical Indian Ocean and SST over the North Pacific.The canonical correlation analysis(CCA) prediction is used to establish forecasting relation.Then the ensemble canonical correlation prediction(ECC) method is used to predict winter temperature over China.The forecast skill is analyzed and independent samples test is also performed.The results show that different predictors have different forecast skills in various regions.Using the sea surface temperature over the North Pacific as a predictor,the skill is higher.But the ECC gives better performance,and its skill is higher than any CCA forecast of single predictor.Under the condition of the same predictors the regression ensemble forecast is better than the simple equal ensemble forecast.

Abstract:TRMM(Tropical Rainfall Measuring Mission)satellite observations 3B42RT and 3G68 averaged over 8 years(1998—2005)in summer(JJA)are used to investigate diurnal variations of rainfall over the Indo-China peninsula.Conclusions are as follows:maximum rainfall and daily-rainfall variance occur on the west coast of Indo-China peninsula and on the windward slope of the Annam Cordillera during the whole summer.Precipitations over the flat land of Indo-China Peninsula and offshore reach their peaks in 16—19LST while in 07—10LST over the coastal areas.Rainfall peaks migrate from coastal areas to the inland and offshore,respectively,in the daytime,and migration from offshore to coastal areas in the nighttime is found,but from inland to coastal areas is not found.The south and north of the windward side of the Annam Cordillera show great difference in the diurnal variation of rainfall,which is related to migration of rainfall.Rainfall over coastal areas of the Thailand Gulf in 01—04LST migrates to inland northeastwards and then heavy rainfall occurs over areas southwest of the Annam Cordillera in 16—19LST,after that heavy rainfall migrates northwestward along the Annam Cordillera to areas northwest of the Annam Cordillera in 01—04LST in the next day.The migration of rainfall results in different characteristics of diurnal variation on the windward side of Annam Cordillera.

Abstract:Dust storm in Korea on March 21—22,2002 is studied using the satellite remote sensing data,weather charts and NCEP/NCAR reanalysis data.Results show that Mongolia was the initial source of the dust storm influencing Korea,where it occurred between high pressure and cold front.The dust storm occurred in central Mongolia on March 19—20 and affected Korea on March 21.The maximum concentrations of PM10 were 2778.2 μg/m³ in Korea,but strong wind made it rapidmy pass away.

Abstract:The three-dimensional structure of two landfalling typhoon,Jelawat and Bilis(2000),during their formations is discussed based on the NCEP/NCAR global tropospheric 1°×1°analysis,using tangential average wind profile,vertical velocity and potential vorticity.The results show that during the typhoons’ formation,the radius of maximum wind decreased with increase in maximum wind velocity,and the vertical motion initially developed in the mid-troposphere gradually enhanced and expanded to the upper and lower levels,simultaneously.On the other hand,the positive potential vorticity gathered gradually over the typhoon center,and the physical variables changed more obvious at 850hPa and 500hPa than 300hPa.

Abstract:In order to find out what might be the mechanism to drive the inter-decadal oscillation of the climate system,the spatial features of unstable coupled waves in the mid-latitude air-sea system are investigated on the basis of the simple air-sea coupled model which includes the deep ocean effects.Results show that: for the unstable coupled waves in the air-sea system,the air disturbance wave goes ahead of the sea disturbance wave by 0 to π/2 in the phase,and especially when the phase difference is π/4,this special spatial structure can cause the most unstable air-sea interaction;in the coupled system,the amplitude relation between the air and sea disturbance waves is determined by the relative size of wind stress and ocean heating coefficients.The amplitude of air disturbance may be larger or smaller than that of sea disturbance;and the deep ocean coefficient brings little change to the spatial structure of the air-sea couple waves.

Abstract:Based on the British Meteorological Office global SST,NCEP/NCAR reanalysis data and 160 stations temperature data in China,by using the EOF,composite and singular value decomposition(SVD) methods,the effect of the Indian Ocean(IO) SSTA on East Asia atmospheric circulation and temperature has been studied in the present article.Results show that the IO SSTA arose anomalous atmospheric circulation,influenced the East Asian winter monsoon thus the temperature anomaly in China.When the autumn SST in the Indian Ocean is wormer(cool),winter temperature in China is also higher(lower).When the Indian Ocean Dipole is positive,temperature is high in the Northeast China and low in Southwest China;and the East Asian winter monsoon is weaker.

Abstract:Using the NCEP/NCAR reanalysis data,the quasi-geostrophic vector Q and moist potential vorticity analyses for the heavy rainstorm in September 2004 in Sichuan and Chongqing are performed,and the distributions of quasi-geostrophic Q-vector’s divergence,vorticity and the frontogenesis function,as well as their temporal/spatial relations with the heavy rain revealed.It is found out that there are close relationship between Q-vector divergence and vertical motion.The Q-vector convergence in the low level was of benefit to the development and maintenance of vertical motion and the rainstorm’s occurrence.Conditional symmetry instability and convective instability in the mid-low level played important role in the rainstorm and therefore are probably one of important conditions to the genesis and development of the mesoscale convective system.

Abstract:Singular value decomposition(SVD) is conducted for the sea ice concentration over the ocean east of Greenland and 500hPa filtered potential height variance of 45 storm-tracks regions.The results show that the first couple of mode obtained from SVD depicts the effect of sea ice over the ocean to the east of Greenland on the variability of Pacific storm-tracks.Furthermore,composite analysis indicates that winter sea ice anomaly gives rise to changes in general circulation,pressure gradient,the jet stream,850hPa meridional eddy heat flux,850hPa vertical eddy heat flux and baroclinicity,accordingly,influencing the vigor and center migration of Pacific storm-tracks.

Abstract:In this paper,we study the existence and uniqueness of positive stationary solutions for a class of reaction-diffusion system by means of calculating the indices of fixed points of compact maps in cones,the maximum principles and the decoupling method.The process indicates that the decoupling method for the class of differential equations is similar to the elimination of unknowns in algebra.

Abstract:In this paper,the mathematical description of these techniques involves all estimation of parameters such as median,pseudo-standard deviation,weighted mean,weighted standard deviation.Their statistical estimation performances such as consistency,unbiasedness and validity are assessed.The results show that these order statistics are consistent and unbiased.The validity is under the traditional statistics for normal distribution,nears or exceeds for skewed distribution.The validity of weighted mean and weighted standard deviation exceeds median and pseudo-standard deviation,and is close to traditional statistics.The simulation and example both prove that order statistics are suprior as compared with the traditional statistics when outliers are presented in data.

Abstract:Using the wind speed data of Jiangsu 460 automatic and intensive observation stations from 2005 to 2006,the high wind process of Jiangsu from winter 2005 to spring 2006 are analyzed,results show that the coastal gales in the winter and spring were induced by strong cold air intrusion,and had certain intermittence,duration and burst and gusty characters.Characteristics of a typical gust process from 2nd to 4th December 2005 are emphatically analyzed.It is found that the intrusion of cold surges promoted the development of ground wind,the changes of u,v components of gale were close correlated with rotation coefficient,i.e.Hourly rotation coefficient was positively correlated with v component variation and negatively correlated with u component variation;and such a correlation were maintained throughout around the cold air intrusion.

Abstract:Based on the meteorological data collected from 616 weather stations in China during 1975—2004,daily,monthly and annual reference crop evapotranspiration(E_T0) were calculated by using the Penman-Monteith equation recommended by FAO.As for the long range annual averages,E_T0 ranged from 800 to 1100mm,with the maximum in Northwest China and the minimum in Northeast China.For temporal variation,it reached the maximum value in 1978 and the minimum in 1993.The inter-annual fluctuations were small in the east of the Qinghai-Tibet Plateau and Notheast China and large in Northwest China.The annual variability varied between-30—30mm·(10yr)^-1,dramatically declining in Western China and the Yangtze River basin,and rising in the East coastal area,the middle and upper reaches of the Huanghe River and Northeast China.Main factors leading to the temporal trend of E_T0 declining-first-then-rising were sunshine duration and saturation deficit.

Abstract:The removals of CHCl₃,CCl₄ and CHBrCl₂,with very low initial concentrations in the chlorinated drinking water under ultrasonic irradiation at different conditions were investigated.It is observed that the removal efficiencies and the sonolysis rate constants of three halomethanes after 1h ultrasonic irradiation fitted the following increasing order:CHCl₃< CHBrCl₂<CCl₄,and the degradation of halomethanes studied followed the pseudo-first-order kinetics model,respectively.Meanwhile,molecular hydrophobicity was found to be a crucial factor in controlling the sonodegradation of halomethane mixtures.Additionally,acoustic intensity also remarkably influenced the sonodegradation of halomethanes,a higher acoustic intensity led to a better removal efficiency of halomethanes.A slight decrease in pH values of drinking water during the sonodegradation processes further demonstrates that ultrasonic technology is practical in the treatment of chlorinated drinking water.It is also concluded that the ultrasonic stirring and degradation coexisted when the halomethanes were irradiated in the unsealed vessel.Based on the ultrasonic cavitation theory,a possible mechanism of the ultrasonic stirring is put forward.

Abstract:Using the monthly precipitation data at 33 stations around the Qilian Mountains and NCEP/NCAR reanalysis data from 1961 to 2002,we analyzed the relation between precipitation and changes in meridional wind in the Qilian Mountains area over the past 42 years.The results reveal that precipitation in the principal part of the Qilian Mountain is more than in the surrounding areas,and precipitation mainly concentrates in May to September in the west part,in April to October in the east part.Precipitation in the East of the Qilian Mountains is more stable than in the West.The northerly dominates in the West while the southerly mainly appears in the East of the Qilian Mountain area.The yearly climatic boundary between the 700hPa northerly and southerly lies south of 37°N in an "east-west" direction.From winter to summer,the southerly expands from the south towards the north,and the northerly dominates over the whole Qilian Mountain from November to March,the southerly gradually moves northwards from April to September and reaches its north boundary—the central Qilian Mountain.The difference between vector winds for dry year and wet year of the Qilian Mountains is large.The vector wind is convergent in wet years while divergent in dry years.

Abstract:This paper presents the method for calculating the energy loss rate of high energy primary electrons which belong to the same energy band in metal emitter,then the energy loss rate of high energy primary electrons which belong to two energy bands in gold emitter is calculated with experimental results,the energy loss rate of high energy primary electrons which belong to the same energy band in aluminum is also calculated with experimental results.The results are discussed in this paper and the conclusion is drawn that the new calculating method of energy loss rate of high energy primary electrons in metal emitter is right.