Abstract:This study established local computing model of remote sensing water vapor by using groundbased GPS(global positioning system) in the region of SichuanChongqing,and developed computing software packages of GPS remote sensing water vapor.Then the experiment and operational application of remote sensing water vapor by using groundbased GPS in this local network was done,by which the high time resolution GPS precipitable water vapor(PWV) sequence of 30 min intervals was derived.This paper also gives the assessment of the retrieval accuracy,as well as the feasibility of meteorological operations application of GPS water vapor products.The major results of this study include developing the operations application system of remote sensing atmospheric water vapor by using groundbased GPS,which can be build on the MICAPS(meteorological information comprehensive analysis and process system) as an operational application system,and realizing the realtime transmission,data solution,deriving of PWV by a local groundbased GPS network and visualization of GPS water vapor products.This meteorological operations system played a unique role in the heavy rain,blizzard and other severe weather forecast in its trialrun.

Abstract:Based on precipitable water vapor received from groundbased GPS，data of dense surface automatical meteorological stations，and conventional sounding data in Shijiazhuang on August 2010，this paper studied the evolution tendency of GPS precipitable water vapor and potential pseudoequivalent temperature during a heavy rain induced by the advance and retreat of the west Pacific subtropical high.The results show:(1)Rainfall usually occurs when the GPS precipitable water vapor is higher than the average value，especially near its maximum value.The heavy rain period is corresponding to the maximum stage of GPS precipitable water vapor.Upperlevel trough is helpful to the occurrence of the convective heavy precipitation at the late period of GPS precipitable water vapor increasing.Weak precipitation will continue at the early period of GPS precipitable water vapor decreasing.(2)In the stability precipitation process，the GPS precipitable water vapor shows a multipeak wave shape，and its amplitude is relatively small.The heavy rain period is corresponding to the maximum stage of GPS precipitable water vapor.In the convective precipitation process，the GPS precipitable water vapor changes dramatically，and the peaks of GPS precipitable water vapor and actual precipitation are exactly corresponding.(3)Rainfall easily occurs when the deviation coefficient of GPS precipitable water vapor is positive，and the heavy rainfall generally happens while the deviation coefficient is higher than one.The deviation coefficient of convective thunderstorm or shower is slightly smaller than that of stability precipitation.(4)The prophase highenergy accumulation is a necessary condition of rainfall.The rainfall of subtropical high usually occurs in the rapid decline phase of potential pseudoequivalent temperature or its valley areas.The precipitation will be stronger when the potential pseudoequivalent temperature is at higher peak with more sharp movement and longer duration of high value.

Abstract:Based on the mass stream function scheme and EOF(empirical orthogonal function),the NCEP／NCAR reanalysis data were used to investigate the meridional circulation changes and their relations with SSTA(sea surface temperature anomaly) form 1979 to 2006.The conclusions are as follows:(1)The south Hadley cell emerges together with the boreal Hadley cell which is more intensive over 105—125°E in boreal summer.These two meridional circulations are named as the “Hadley cell pair”;(2)During the past 28 years,this pair of Hadley cells varies with periodicities of 2—4 and 4—6 years.The south Hadley cell tends to move southward while the intensity of boreal Hadley cell tends to stronger,especially before the mid 1990s;(3)Variations of Hadley cell pair is significantly correlated with IOD (Indian Ocean Dipole) and ENSO events.Lag and simultaneous correlations of the leading EOF mode for Hadley cells with SSTA is consistent with the SST pattern of El Nino developing or prevailing period over the Pacific.That the south Hadley cell is northward (southward) and that the boreal Hadley cell is weak (severe) are correlated with the development of El Nino(La Nina) in the coming winter.This can be a potential indicator in predicting ENSO events.The IOD SSTA is able to change the south Hadley cell.With negative IOD events,the south Hadley cell is weakened.However,with positive IOD events,there is no obvious opposite phenomenon.

Abstract:By using the NCEP／NCAR reanalysis data and the diagnosis analysis method of wavepacket propagation(WPD),the wavepacket propagation and accumulation characteristics of the heavy snowstorm on March 24—25,2005 in Tibet were analyzed.Results show that the characteristics of wavepacket were in better accordance with the snowfall area at 500 hPa.The perturbation energy accumulated and increased obviously during the heavy snowfall process.This process was mainly influenced by the low value system of the Indian Ocean and the Bay of Bengal,which transported sufficient vapor to Linzhi area.The cold air from high latitude area and the southwest airflow interacted with each other,which also promoted the occurrence of this heavy snowstorm process.

Abstract:By using the radiosonde data and the satellite retrieval and observation,the phenomenon that the homogeneous freezing latent heat warms the air in severe storms is revealed.It was found that the temperature can increase by as much as 50 ℃ within that layer in the severe convective storm because of homogeneous freezing.It is mainly because the updrafts are so strong that the cloud drops have no enough time to grow larger and the conversion of cloud drops to hydrometeors and the glaciation of the cloud are delayed to higher heights.Heterogeneous ice nucleation does not have time to deplete much of the cloud water before reaching the homogeneous glaciation level.Thus most cloud drops are carried to the height of homogenous freezing and are instantly frozen into ice crystals,which releases the latent and warm the ambient air.The phenomenon is also verified by the NOAA satellite observation that small ice particles formed by homogenous freezing on the cloud top and overshooting top.The warm effect of homogeneous freezing could be detected by the sounding when it is close to the storm and the tropopause is close to the height of homogeneous freezing.

Abstract:The occurrence regularity and formation/dissipation mechanism of fog on the Leizhou Peninsula have been statistically analyzed by using the meteorological data observed at three conventional weather stations of Zhanjiang (59 a),Leizhou (46 a) and Xuwen (42 a),which locate in the north,central and south part of the Leizhou Peninsula,respectively.The results show that the annual fog days over the three stations basically have the same variation trend in the pattern of “W”,and local maximum values increase significantly.The annual average of fog days at the three stations are 24.7 d,304 d and 210 d,respectively.Fog mainly occurs from December to next April and on the Leizhou Peninsula.The fog days is the most in March and the least in July.The frequency of night fog is up to 90% during the past decade,and fogs with short duration make up the majority,with 75% of which below the 4 hours.The synoptic situations favorable for the fog formation and development on the Leizhou Peninsula can be roughly divided into five classes:high pressure system,low pressure system,cold front,stationary front,saddle type pressure field or isobaric field.The advection fog,frontal fog and radiation fog are dominant types over Zhanjiang.The weather situations causing the dissipation of Zhanjiang fog are mainly the following:newborn cold air moving southward and surface wind speed increasing;drizzle formed due to collisioncoalescence and subsequent gravitational settling of fog droplets after fog development;fog droplets evaporating because of the increasing temperature at the near surface layer after sunrise.The statistical results of fog frequency at the three stations on Leizhou Peninsula from 2000 to 2009 show that the meteorological conditions of the biggest fogforming probability are:〖WTB1X〗T〖WTB1〗=15—25 ℃,〖WTB1X〗T〖WTB1〗〖WTB1X〗T〖WTB1〗d≤10 ℃,〖WTBZ〗Δ〖WTB1X〗p〖WTB1〗3=-35—-2 hPa and 15—25 hPa,wind direction of NNEESE and wind speed ≤5 m/s.The analysis of Lband radar sounding data shows that the temperature decreases with altitude in fog,with the fog top height at about 15 km.Relative humidity is above 92% in the fog layer,which decreases sharply from the height of 15 km until 3 km,and then remains unchanged above 3 km.The temperaturedewpoint spread is from 12 to 64 ℃,with 2—6 m/s wind speed near the ground surface.Wind direction rotates clockwisely with height,which indicates a warm advection in fog layer.

Abstract:Dominated by atmospheric temperature,pressure and water vapor pressure,the atmospheric refractivity affects both the propagation path of radar EMwaves and the echo phase of an object.This implies that the variation of atmospheric refractivity can be retrieved by calculating changes of echo phase measured by Doppler weather radar.Thus the relevant water vapor information can be obtained for the research of local convection or advection.This paper explains the principle and method of refractivity retrieved from Doppler weather radar.The experiment results showed that the atmospheric refractivity retrieved from the Sband Doppler radar of Jiangsu Meteorological Observatory was reliable and effective in the case of a local thunder storm.The work can supply not only the remotesensed data to the study on changes of water vapor and weather changes but also supporting data of water vapor field to numerical models,which is very promising in application.

Abstract:In order to examine the application capability of fourorder recursive filters on heavy rain forecast,by using GRAPES3D Var system，the paper numerically simulate the heavy rainfall in Sichuan Basin during July 16—19,2007.Three experiments were carried out in this study during different periods.The first experiment used oneorder recursive filter with one intrinsic scale;the second used fourorder recursive filters，which was synthesized from three fourorder recursive filters with different intrinsic scale respective;the last experiment used oneorder recursive filter，which was synthesized from three oneorder recursive filter with different intrinsic scale respective.The results show that the recursive filter with multiple intrinsic scales is better than the one with only one intrinsic scale.The heavy rain process is closer to the reality in the second experiment.The forecast of precipitation region and amplitude has been greatly improved.Its adjustment of vapor is more ideal.

Abstract:Based on the monthly precipitation data of 160 stations in China from January 1951 to October 2007,the 12month standardized precipitation index(ISP) was calculated.The statistics of the drought occurrence frequency in different decades was conducted according to the drought classification by ISP value.In addition,the interdecadal trend of the drought occurrence was analyzed by using MannKendall method.The results show that the drought occurred mainly in southern Xinjiang area in the 1950s and in the 1960s a high occurrence frequency center occurred in the area from northern part of Xinjiang to the upper reaches of the Yellow River as well as in Southeast China around the middle and lower reaches of the Yangtze River.In the 1970s,drought events mainly took place in Heilongjiang and Jilin Provinces and the middle reaches of the Yangtze River.In the 1980s,the droughts frequently occurred in two zonal belts which extend from Southwest to South China and from Northwest to North China respectively.In the 1990s,the droughts took place in the area between the Yangtze River and the middle reaches of the Yellow River.During the early 21st century,the drought mainly occurred in the northern part of North China and eastern Inner Mongolia.The MannKendall trend test shows there was an significant drought tendency in northern Xinjiang,eastern Inner Mongolia and the regions extending from the lower reaches of the Yangtze River to Southeast China during the period from the 1950s to 1960s.Northeast China became arid from the 1960s to 1970s.From the 1970s to 1980s,the drought tendency occurred in Shandong Province and the eastern part of Southwest China.The region between the middle reaches of the Yangtze River and the Yellow River became arid from the 1980s to 1990s.From the 1990s to the early 21st century,the drought tendency was significant in the northern part of North China,eastern Inner Mongolia and eastern Heilongjiang.In addition,an abrupt change of high occurrence frequency of droughts appeared around the 1980s.The drought mainly occurred in Northwest China,Northeast China,a region between the Yangtze River and Huaihe River,the middle and lower reaches of the Yangtze River as well as South China during the period from the 1950s to 1970s.However,since the 1980s the high occurrence frequency of droughts has moved to places with low drought occurrence frequency in previous decades.From the 1950s till now,the drought tendency has increased rapidly in eastern Jilin and Heilongjiang areas and a narrow strip which extends southwestward from Hebei to Guizhou,while the drought trend has decreased significantly in Xinjiang,Gansu and Qinghai.

Abstract:A heavy rainstorm occurring in the southern part of Jiangsu Province including ShanghaiNanjing Expressway on September 17th,2009 is simulated by using WRF22(Weather Research and Forecasting Model for version 22) and NCEP(National Center of Environment Predicting) reanalyzed meteorological data with 1°×1° grid.The verification of the observed data from the Automatic Weather Monitoring System on the ShanghaiNanjing Expressway displays that the results of the simulation on the rainstorm process are satisfactory and the simulations coincide with the observed values.Diagnoses are made based on the output data from the model.The results are shown as follows:(1)The development and movement of a meso〖WTBZ〗β〖WTB1〗scale low vortex in the middle and lower reaches of the Yangtze River play an important role in the enhancement and maintenance of the rainfall in the process;(2)The moisture convergence zone below 500 hPa is significant and it provides important vapor conditions for the unstable growth of convection and the maintaining of rainstorm by the forming of the deep and humid environment in the rainfall area;(3)There is strong vertical motion in the rainfall area and the vertical structure configuration of the vorticity field is consistent with that of the divergence field.As a result,the unstable energy in the atmosphere release and the strong convective weather forms;(4)The atmospheric stratification is neutral in the middle and upper of troposphere but potential instable in the lower atmosphere.So there is convection development in the whole layer of the atmosphere,which is conducive to the formation of the rainstorm.

Abstract:On the basis of the normality significance test of the annual and seasonal temperature and rainfall series at 160 stations in China from 1951 to 2008,the significance of the interdecadal anomaly components of temperature and rainfall series is statistically analyzed.The results show that:1)Temperature at most stations was normally distributed while rainfall was not,which was somewhat related to the regions.2) There was obvious difference in the significance of interdecadal components of temperature and rainfall series.The interdecadal component of temperature was significant at most stations while it was the case at only a few stations for rainfall.3) Since not all the annual and seasonal temperature and rainfall,especially the rainfall series,were normally distributed at the 160 stations in China from 1951 and 2008,the statistical significance should be tested by Monte Carlo scheme.

Abstract:We calculated the coefficient(A02) of cosine Spherical harmonics by using the NCEP／NCAR middle stratosphere(10—70 hPa) reanalyzed daily height field data from 1958 to 1997.Then we derived the transformation date of middle stratosphere circulation from cyclone to anticyclone on the basis of the date when A02 converted steadily from negative to positive.The result shows that:1)The 20 hPa circulation first transformed from cyclone to anticyclone (averagely on April 24) and then the same occurred at 70 hPa 54 days later,thus the whole middle stratosphere was in summer;2)There is notable interdecadal variation in the transformation date at 50 hPa and 70 hPa.Our study shows that there exists remarkable correlation relationship between the transition date of circulations at 50 hPa and 70 hPa and the quasibiennial oscillation(QBO) of the lowlatitude stratosphere zonal wind.

Abstract:Highresolution data from numerical model simulation are used to study the ageostrophic characteristics of shortterm process of East Asian subtropical westerly jet in summer.The results show that jet represents positive ageostrophic area,the maximum lies to the north of jet center region and negative areas mostly lie close to the entrance of jet stream.Ageostrophic wind shows anticyclonic shear to the south of jet and in the entrance area while cyclonic shear appears in the north of entrance and exit areas.Ageostrophic wind indicates the change of jet intensity and geostrophic deviation is closely related with shortterm change of jet strength.The change of maximum deviation wind occurs 6 h earlier than the change of horizontal wind.Distribution of ageostrophic vorticity takes on mesoscale characteristics while positive and negative values appear alternately.Mesoscale vorticity extremums mainly locates in 3 regions:Taihang Mountains,Changbai Mountains and Honshu Island(Japan),all of which correspond to mesoscale terrain over 1 000 m.Maximum areas of ageostrophic vorticity of upper air jet correspond to mesoscale terrain.Mesoscale rainfall areas correspond to dense extremum areas of ageostrophic vorticity.

Abstract:To reveal the influence of polluted aerosol on severe freezing weather,especially the freezing rain,we studied the freezing weather occurred during 18—21 January 2008 by using WRF.The results show that the polluted aerosol suppress regional precipitation,especially the process of severe freezing rain.The microphysical process shows that the formation of freezing rain in Guiyang is caused by supercooled cloud mechanism(warm cloud mechanism).The polluted aerosol increases the rainwater mixing ratio and ice particles concentration and reduces the content of supercooled rain,resulting in solid precipitation on the ground and suppressing freezing rain.

Abstract:The crop pollen autoacquisition sensor captured crop pollen with a slide on the sampling platform,which was controlled by the simple robotic arm under the ARM(advanced RISC machines) command.Then,the slide was put under biological microscope.By using the CMOS(complementary metaloxidesemiconductor) video sensor,the optical image was changed into digital image,which was to be processed and stored by the ARM.Field experiment data and standard medical blood count board were used to calibrate instrument geometric scale and slide film sampling.The instrument optical magnification F was 328 and the field realspace 〖WTB1X〗S〖WTB1〗 was 1516 mm2.When the sampling number 〖WTB1X〗N〖WTB1〗 was 50,the pollen density correlation coefficient was larger than 95％.With a certain sampling accuracy,when the pollen density was high,sample size could be reduced considerately.The rice pollen whose volume was relatively small needed 40 samples while the bigger corn pollen needed 80 samples.Because of the system geometric distortion,the optical magnification F changed with the radius,which caused the sampling error of the measure area to be as high as 1375％.

Abstract:With the solar wind data observed by ACE／WIND spacecraft and the geomagnetic storm 〖WTB1X〗D〖WTB1〗st index data during 2004—2006,the linear correlation between magnetopause standard off distance 〖WTB1X〗R〖WTB1〗0 and 〖WTB1X〗D〖WTB1〗st index,in which the grade of geomagnetic storm is characterized,is investigated in terms of 200 different graded storms.It is a fact that the time series of 〖WTB1X〗D〖WTB1〗st index lag about 3 h behind the time series of the magnetopause standard off distance 〖WTB1X〗R〖WTB1〗0 calculated by Chao Model under the extreme solar wind.After the time lag corrected,the linear correlation between magnetopause standard off distance 〖WTB1X〗R〖WTB1〗0 and geomagnetic storm 〖WTB1X〗D〖WTB1〗st index is revealed.The results show that the average linear correlation coefficients are 077,074 and 047,respectively,corresponding to the super,the big and the middle storms.Under different graded storms,the charts of 〖WTB1X〗R0D〖WTB1〗st fitted by the least square method are shown.