Abstract:In this study,the Lamb-Jenkinson circulation type classification system is applied to obtain circulation information in China on daily basis.For that purpose,the NCEP daily mean sea-level pressure reanalysis data from 1 January 1948 to 31 December 2004 are used to derive daily six circulation indices and corresponding 27 circulation types for 16 sub-regions in China.The frequency of circulation types over different sub-regions and seasons is computed and described.Results show that Lamb-Jenkinson classification system is applicable for most of China,although in the west of China where might exist some errors in sea-level pressure due to high elevation.Linear tendencies of three major indices(zonal wind,meridional wind and vorticity) from 1958 to 2004 has been analyzed.Since 1958,all of three indices have obviously decreased over North China,Hetao and central-western Nei Mengolia,which indicates that high value systems have increased and quasi-eostrophic southwest wind has decreased over these regions.It is possibly an important circulation background for droughts over above regions.For the wintertime,zonal wind index has distinctively increased over Northeast China,North China and the north of Xinjiang,suggesting that the westerly in the ground layer has strengthened over the north of China,which is closely related with remarkable warming over above areas in winter.

Abstract:Characteristics of the urban heat island(UHI) effect of Nanjing and its cause are investigated by using the MODIS data in April 2004.The surface parameters from the MODIS data include surface temperature(t_s),albedo(α),and normalized difference vegetation index(NDVI).Their heterogeneities over urban and rural area are analyzed based on land cover classification,and their relations are also presented in order to explain the UHI effect.The results show that there exists obvious UHI effect.t_s over urban areas are 10.83% higher than those over rural areas,and NDVI and α over urban areas are by 62% and 18.75% less than those over rural areas,respectively.Surface temperature has significantly negative correlation with NDVI and their correlation coefficient is-0.73.Correlation between NDVI and albedo depends on spectrum of light.Difference in vegetation cover is the primary cause for UHI effect.

Abstract:Based on the proposed concept of "Meiyu Period" precipitation in Pudong of Shanghai,the multi-scale time-frequency characteristics and abrupt change of the precipitation are studied by wavelet transform.The results show that the precipitation series from June 1 to July 10 in Pudong is able to represent more accurately and objectively the actual precipitation in this particular "Meiyu" season;the "Meiyu Period" precipitation has the major oscillation periods of quasi-2 years and quasi-10—20 years;and the time series reconstrcuted using the inverse wavelet transform can better reflect the main oscillating characteristics and trend of the "Meiyu Period" precipitation than the original Meiyu rainfall series at Shanghai station.

Abstract:Based on the air pollution data and meteorological data from 2002 to 2004,the air pollution characters and trend in Zibo City were analyzed.The atmospheric environment capacity of pollutants was estimated using the A-P method.Investigation indicates that the key air pollutants are inhalable particle matter(PM10) and sulfur dioxide(SO₂),and their emissions have both exceeded the atmospheric environment capacity.In addition,the possible origins of air masses from pheripheral areas on heavy air pollution days were calculated using the NOAA HYSPLIT4 backward trajectory model,and results suggest that non-local origin pollutants were mainly transported by the northerly flow from Northeast China and eastern Inner Mongolia and the westerly flow from central Mongolia.All these findings provide a scientific basis for making plans of city’s development as well as for bring air pollution under control in the future.

Abstract:The NCEP/NCAR globally tropospheric 1°×1° reanalysis data have been employed to select six landfall typhoon cases in order to diagnose variations of typhoon warm sectors in atmospheric boundary layer during their whole life periods.Results show that typhoons had different characters of boundary layer temperature and vorticity fields at different life stages,and the intensity of typhoons was inversely proportional to the distance between warm center and maximum positive vorticity center,that is to say,the smaller the distance,the stronger the typhoon.

Abstract:Based on the level 1 and relevant ancillary data of the Moderate-resolution Imaging Spectro-radiometer(TERRA/MODIS),the aerosol optical depth over the East China Sea is retrieved by International MODIS/ARIS Processing Package(IMAPP),and the inverse method validated with Aerosol Robtic Network(AERONET) solar direct radiance measurements.The distributive characteristics of aerosol optical depth and ?ngstrm exponent(which symbolizes the width of particle spectrum) over the East China Sea during October—November 2002 are studied,and the backward trajectories analysis of air mass and the background information of geographical environment applied to discussing the applicability of aerosol algorithm and the error source of the aerosol optical parameters retrieved from satellite.The results indicate that the aerosol optical depth obtained by IMAPP over the East China Sea and the open sea area south of Japan are basically in consistent with the result from AERONET.However,the aerosol optical depth is a bit high along the coastal area of Bohai Sea and Yellow Sea due to the influence of Case 2 water.

Abstract:Activity of blocking high over Eurasia continent is examined according to data of 500 hPa geopotential height and zonal winds for the period 1950—2004,which are provided by NCEP/NCAR.Results show that blockings in Eurasia posses distinct seasonal variations and geographic diversities.In spring blockings occurred frequently over the Ural Mts.In summer blockings occurred frequently over four regions,namely the Ural Mts,West of the Lake Baikal,East of the Lake Baikal,and the Sea of Okhotsk.Much fewer blockings occurred in autumn.In winter most blockings occurred over around the Ural Mts.The occurrence frequency of blockings over the Lake Baikal in summer accounts for 69 percent of its annual total.There is an intraseasonal variation of the occurrence frequency of blocking in Eurasia with a significant period of 30—60 days as well as eastward propagation of the blocking high centers in summer.In addition,blocking activities have significant interannual variations,which behave differently in various areas.

Abstract:The analysis of persistent heavy rain in South China is performed using the daily precipitation data of 45 stations in South China and the NCEP/NCAR reanalysis daily data from 1958 to 2004.157 persistent heavy rains in South China are divided into three categories according to water vapor transfer,unstable energy and lifting condition,and their formation mechanism are discussed.

Abstract:Land surface temperature derived from brightness temperatures and NDVI from MODIS data are used to calculate TCI and VCI,respectively with which a dryness index(DI) is then constructed.The temporal-spatial distribution of drought in central Guangxi from September to November in 2004 and 2005 is studied by using the DI.DI’s temporal-spatial pattern is compared with the real drought condition from the observatories around Guangxi,thus DI’s validity in evaluating drought is verified.Afterward,the correlation coefficients of DI with TCI,VCI,LST and NDVI are evaluated.The results show that TCI and VCI have closer relation with drought than LST and NDVI,suggesting that dryness indexes based on TCI and VCI in this paper are reasonable for Guangxi central arid area.

Abstract:Based on the data of fog from 9 weather stations in the central coastal plain of Hebei Province during 1971—2000.The formative characteristics and it’s decadal change of fog are analyzed.The results show:1)Fog is one of disastrous weathers of highest frequency in winter and autumn in the central seaside plain;2)In addition to low visibility,continuous occurence,long duration and large range are also the formative characteristics of fogs,which have disastrous impacts,and can not be neglected;3)After the 1990s,the annual number of heavy fog day has evidently increased in comparision with the 1980s and 1990s;4)The main reason for increase in fog days is the changes in weather and climate condition,and it is also closely related to human activities which lead to the development of city economy and the excerbation of air pollution.

Abstract:This paper focused on the regional scale rice mapping using multi-temporal Advance Synthetic Aperture Radar(ASAR) Wide-Swath Mode(WSM) data.Taking the middle and north regions of Jiangsu Province as a test site,temporal changes of VV polarization backscatter for the rice paddy in this area was analyzed.The backscattering signature of rice paddy changes at the different rice growth stages and its temporal behavior shows significant distinction from those of other land surface objects.Therefore,a threshold classification method was developed in this paper to retrieve rice growth areas from the ASAR WSM images.Validation was conducted using rice GPS samples.The results show that the accuracy of rice paddy identification is 73.68%.

Abstract:Using the DEM(digital elevation model) data as input and giving an all-sided consideration on terrain factors influencing diffuse solar radiation(DSR),with topography openness model improved on,establishing monthly diffuse coefficient model,a distributed model for calculating DSR over rugged terrains is developed,and monthly DSR with the resolution of 1 km×1 km for the rugged terrains of China is generated.Results suggest that:(1)the topographical factors have relatively obvious effect on the spatial distribution of DSR;(2)the proposed model is proved to be able to treat volumes of data and is applicable to satellite image processing platform or GIS.

Abstract:Using the GPS analysis software GAMIT and combined with the surface temperatures and pressures,the precipitable water vapor(W_P) at a timal resolution of two hours has been retrieved from the GPS observations in Beijing from July 2004 to July 2005.Compared with the records of the radiometer and the water vapor radiometer,the results show a good agreement with the rms 3.05 mm and 3.29 mm respectively.Further,the seasonal variation of W_P and the relationship between W_P and rainfall in Beijing are also discussed in this paper,which are beneficial to the weather study and weather forecast.

Abstract:Palmer Moisture Anomaly Index is based on the water balance equation.Based on a hydrological budget month-to-month for one area,the CAFEC(Climatically Appropriate for Existing Condition) quantities for evapotraspiration,recharge,runoff,water loss and precipitation can be computed,and the water departure can be obtained.As a water anomaly index,the water departure is not able to reflect the extent of drought or wetness.For this reason,Palmer put forward K(the weight factor reflecting climate characteristic).Using this method,the monthly Palmer Moisture Anomaly Index from 1961 to 2000 for Xi’an are computed and dryness/wetness grades for different month are evaluated year by year.Comparative results indicate that the Palmer Moisture Anomaly Index is more suitable for the semi-arid area in the east of Northwest China.

Abstract:Even though MCC was seldom reported in high-latitudes according to the statistics,it occurred in the north part of Heilongjiang Province i.e.Heihe,Yichun,Qiqihar at the night of May 16,2005 and the severe convective weather phenomena including tornado,hailstone,gust,and heavy rainfall were observed.The MCC was analyzed using the satellite data of FY-2 and other relevant data,the comparative research was conducted with the other severe convections in the same area and the MCCs in other regions to faciliate the disastrous weather forecast in high-latitudes.

Abstract:The snow cover data with the confidence information in Northeast China during 2000—2005 winters are extracted from the Terra MODIS products in this paper.The results can be used as the input in some hydrological models,and can be also used to study the feedback of regional snow-cover to climate.The intensity of cold air activities in winter and the snow-melting status in the next spring in 2000—2005 over Northeast China are analyzed using the snow-cover data set obtained in this paper.

Abstract:The aerosol data sampled with an airborne PMS(Particle Measuring System) in six flights under different atmospheric conditions during August to September of 2003 over Beijing and its peripheral areas were analyzed.The results show that due to different atmospheric conditions,the distribution of aerosol particle concentration over Beijing and its peripheral areas is rather different.The maximum of mean number concentration of aerosol particles was 3.46×10²cm^-3,while the maximum number concentration of particles was 5.26×10³cm^-3,therefore the latter is one order of magnitude larger than the former.The maximum of mean diameter of particles was 1.392 μm,and the maximum diameter of particles was 2.75 μm.The minimum of mean concentration of particles was 25.7 cm^-3.In the fog condition,aerosol particle number concentration decreased with increasing height near the surface,and change in aerosol particle diameter was complicated.The number concentration and diameter of aerosol particles increased in the overcast and rainy condition.In addition,a distinct accumulation zone of aerosol particles could be found under the weak inversion layers,where were vertically distinct different distributions of aerosol particles.The aerosol particles showed an unimodal distribution below the 0 ℃ layer,and a bimodal distribution above.Cloud droplets exhibited a multimodal distribution with the peak diameters at 3.5 μm,12.5 μm,and 23.5 μm,respectively.

Abstract:Mesoscale numerical model MM5(V3) is used to simulate the heavy rain process in Qidong,Jiangsu Province during 15th to 16th August 2002.Simulated results show that the genesis,development and rain gush of the mesoscale system are well described.The mesoscale vortex,and local circulation are analyzed,and the analysis results demonstrate that the mesoscale vortex played an import role in the occurrence of the heavy rain,and the presence of local circulation also favored the heavy rain.

Abstract:With research results concerned with mesocyclone for reference,especially the related content of MDA(Mesocyclone Detection Algorithm) from NSSL(National Severe Storm Laboratory),we present an improved MDA and the mesocyclone identification module in the Doppler Weather Radar Second Production software.Using the Doppler data of 27th May 2002 in Anhui Province,we compare our results with the mesocyclone products produced by Build 10.8 of METSTAR.The results show that our products have the same warning effect as Build 10.8.

Abstract:We discuss the problem of consistence arose from data enlargement in this paper.Let data as the objects of concept lattice,we deal with the consistency of data enlargement when the data basic set is given and the data hypothetically have a certain character,and give the decision theorems of data enlargement consistency.

Abstract:The influence of observational error on statistical inference is discussed and the method to diminish the impact of stochastic error is given.