Abstract:Impacts of vegetation coverage changes on land surface conditions are investigated through numerical simulation by using the NCAR Community Land Model(CLM3.0).Results show that the evident anomalies in land surface conditions,such as energy balance and hydrological cycle,are induced by anomalous changes in vegetation leaf area index(LAI).(1)The anomalous change in LAI alters the partitioning of the solar radiation reaching at ground surface between vegetation and soil surface,as well as the sensible and latent heat fluxes of ground surface.Larger LAI increases the solar radiation absorbed by the vegetation,but decreases that arriving at the soil surface.Meanwhile,it also induces increase in the latent heat flux related to the vegetation evaporation and transpiration,together with decrease in ground surface latent heat and sensible heat fluxes.(2) The increase of LAI leads to a larger precipitation interception,leaf evaporation and transpiration.In the tropics,larger LAI leads to smaller soil evaporation and land surface runoff,but larger soil moisture in all seasons.However,in the middle-high latitudes of Northern Hemisphere increase in LAI reduces the soil evaporation mainly in summer,and also results in deeper snow cover in winter,thus causing an evident increase in land surface runoff in late spring and early summer.(3)Larger LAI tends to reduce both leaf temperature and ground temperature,but only by relatively small values.Such a conclusion will provide some clues for further investigation on the climatic feedbacks of the vegetation coverage change.

Abstract:Using the Boussinesq approximation equations for meso-scale disturbances in zonally linear and non-linear shear flows a study is undertaken of the unstable features and wave properties of two typical meso-scale unstable disturbances（i.e.symmetric and transversal instabilities. Results suggest that:1）for symmetric disturbances with its iso-phase plane parallel to the basic flow,the instability of the disturbance is actually the instability of the internal inertial gravity wave propagating in a direction perpendicular to the basic flow.The second-order shear of the basic flow represents an instable factor for the symmetric disturbance,and drives the unstable mesoscale disturbance to travel in the meridional direction;2) for traversal disturbance with its iso-phase plane perpendicular to the basic flow no vortex Rossby wave exists at all when the basic flow is constant or only linearly sheared and the instability of the traversal disturbance is actually the instability of the internal inertial gravity wave propagating simultaneously in two opposite directions with respect to the basic flow.With a second-order or nonlinear vertical shear of the basic flow taken into account,a new kind of wave（vortex Rossby wave） occurs and it propagates in one direction with respect to basic flow₀ and originates physically in the second-order shear of windspeed (β_*=_zz≠0).In fact,the instability of the traversal disturbance may be the instability of mixed vortex Rossby ——gravity wave.In the real atmosphere vortex Rossby wave is crucial to the genesis,development and evolution of meso-β convective cloud nucleus and rain cores.

Abstract:The relations of the diurnal peak of photochemical ozone and its occurring time to the ozone precursors（NMHC,NO_x）and the ratio of NMHC/NO_x are researched by using an atmospheric photochemical box model.Results show that the most important factor on the peak ozone(φ_O3max) ridge’s slope of EKMA graph is compositions of NMHC.The diurnal peak ozone occurring time(τ_O3max) is dependent on the ratio of NMHC/NOx and compositions of NMHC,but independent on concentrations of NMHC and NOx.The reason of the advancing trend of τ_O3max in Beijing in recent 20 years is explained by the model results.

Abstract:Polycyclic aromatic hydrocarbons（PAHs） contamination in soil is an increasing problem in many countries,including China.An extensive and systematic survey has been undertaken to evaluate the PAHs contamination of urban soils and foliage at different sites in Beijing.Soil samples and plant leaves collected from campuses of universities,schools and kindergartens,public squares,fallow land and roadsides,were analyzed for 16 PAHs by a GC-MS.The foliage PAHs concentrations ranged from less than（0.080×10^-6to2.786×10^-6.The highest contaminated soil sample came from roadside.Total organic carbon（TOC） played major roles in the distribution of PAHs.There was a significantly close relationship between ∑PAHs concentrations of soil and foliage samples at each site.

Abstract:The paper retrieves atmospheric temperature and moisture profiles and surface skin temperature from the high-spectral-resolution Atmospheric Infrared Sounder(AIRS) observations with a statistical technique based on principal component analysis.The synthetic regression coefficients for the statistical retrieval are obtained by using a fast radiative transfer model with atmospheric characteristics taken from a dataset of global radiosondes of atmospheric temperature and moisture profiles.Retrievals are evaluated by comparison with radiosonde observations and European Center of Medium-range Weather Forecasts(ECMWF) analyses.AIRS retrievals of temperature and moisture are in general agreement with the distributions from ECMWF analysis fields and radiosonde observations,but the AIRS depicts more detailed structure due to its high spectral resolution(hence,high vertical spatial resolution).

Abstract:Based on the 1950—1999 data of Hadley Center monthly global SST,NCEP/NCAR reanalysis and rainfall over 160 stations in China,investigation is undertaken for the difference in autumn rainfall in China between years of Indian Ocean Dipole(IOD) only and IOD and ENSO concurrence,so as to study effects of ENSO on the relationship between IOD and autumn precipitation in China.It’s shown that the autumn rainfall will be more than normal in Southwest China and the Yellow River basin in the positive phase IOD year,however,in the positive phase IOD and ENSO concurrence year,the excessive rainfall area in Southwest China will expand eastward,while the Yellow River basin will suffer from deficit rainfall.The circulation cause is also examined for the influence of ENSO on the relationship between IOD and autumn rainfall in China.

Abstract:In order to investigate the effect of meso-scale topography on vortex self-organization,five numerical experiments,whose integral time is 72 hours,are performed using a ƒ-plane quasi-geostrophic barotropic vorticity equation model with a topographic term.Results show that:without the topographic term,the quasi-final structure is a typhoon-like vortex with spiral bands;with the topographic term,the quasi-final structure is a quasi-circlar vortex without spiral bands,but with two low vorticity areas inside.The two quasi-final vortex centers may be above 100km apart.

Abstract:By using the direct solar radiation data measured by a CE-318 sun photometer in Inner Mongolia during the period between June 2002 and May 2003,the aerosol optical thickness(AOT) and size distribution were retrieved by extinction method.Results show that there were significant variations in temporal-spacial distributions of AOT.The largest mean AOT appeared in spring[AOT(λ=440nm)=0.78] with the least in winter[AOT(λ=440nm)=0.13].AOT was always largest in Ejin Qi and least in Dongsheng.There were four patterns of day-time variations:(1)AOT is high in the morning and low in the evening;(2)AOT is low in the morning and high in the evening;(3)AOT peaks at noon;(4)AOT varies gently.This is mainly associated with dust weather,turbulence of boundary layer and human activities.The aerosol size distribution basically satisfied the Junge distribution and appeared an obvious peaks at r =(0.3μm),0.6μm,and 1.0μm.However,it shows a significant discrepancy under different weather conditions.Large dust particles and giant dust particles remarkably increased in dust weather.The aerosol number concentration in dust weather was about one order of magnitude larger than that in clean weather.And it was also larger in spring than that in winter,but the both were still within the same order of magnitude.

Abstract:The dynamic-wave equation derived from the Manning equation was proposed to estimate run-off in BATS,which introduces surface slope and roughness to take into account the interaction between grid physical variables.The modified BATS was then coupled into the RegCM2.By using the T106 data in June to August 1998 as the boundary field,simulations of runoff were performed for eastern China.Simulations show that the runoff of the modified model reaches 80—500mm in the June to August,more closer to the observed values(50—500mm) than the value of the original(30—80mm) model.Therefore the modified BATS better manifests the large scale advection effect of runoff.From comparison of simulations by the modified model and original model at Wuhan station,it is found that the error of simulated average temperature by the modified model and the observed data reduces 0.66℃.The simulated precipitation by the modified model also agrees better with the observed than the original model.The paper also analysed the temperature,precipitation,soil water,evaporation,etc.

Abstract:Modification of upstream water vapor flux of a rainstorm in July 2005 was simulated to change the intensity of downstream precipitation by using the IAP 3-dimension cloud model,and the conditions and means of weather modification were analyzed.Results show that the seeding rate has close relationship with the effect of precipitation enhancement: the effect can not be seen only when the seeding rate is below 0.07g/s.At the same time,it is also found that the best effect appears when the super-cooled water reaches the maximum value and the seeding rate of AgI is 0.05g/s.Seeding makes the ice and snow crystal in the natural cloud appear earlier,and the content increase evidently.

Abstract:Based on the point of view of the interaction between ozone formation/destruction and solar UV energy,3 key factors of UV radiation,the absorption of UV by the substances in chemical and photochemical reactions,and the scattering of UV by aerosols etc are considered.After analyzing the observational data of ozone,solar radiation and meteorological parameters during 1990 to 1992,an empirical model for calculating total ozone amount was constructed.The calculating results agree well with observed values,and the advantage of the model is that all the data can be obtained from meteorological observation station.The monthly ozone amount from January 1979 to June 1996 in the Beijing area were calculated using this model,the calculated results are also consistent with the observed,and the maximum,minimum and averaged relative deviations between them are 15.2%,0.05% and 4.9%,respectively.The relative deviations within ±10% account for 91.4% of the total.So,this empirical model is reasonable and feasible.The decrease of ozone in the Beijing area after 1991 was related to the influence of the Pinatubo volcanic aerosols.

Abstract:Using the Micaps regular date,correlation and statistical analyses between sandstorm days and the upper level jet stream between 30～50°N during 2000—2004 are carried out in this study.The results show that the sandstorms accompanied by the upper level jets can be divided into 2 kinds:single jet stream pattern and double jet stream pattern.For single upper level jet patterns,sandstorm is likely to occur beneath the left side and right rear side of the upper level SW or NW jet stream;and for double(a NW plus a SW) jet streams patterns,sandstorm is likely to takes place beneath the left front side of the NW jet and the left rear side of the SW jet,or beneath the right front side of the NW jet and the left rear side of the SW jet.Dynamic analyses on the vertical distributions of wind filed structure and the vertical structure of circulation field for selected typical sandstorm cases are also carried out.The analysis results suggest that the upper level jet associated with sandstorms includes single jet pattern,double jet pattern and even trijet pattern;generally the height of the north branch upper level jet is lower,at 300 hPa,and the south branch jet is higher,at 200 hPa;the maximum wind speed of the south branch is greater than that of the north branch;the north branch jet tilts to the south with height,while the south branch leans northwards with height.Sandstorms for single jet pattern mostly occur beneath the south side of the descending leg of the secondary circulation of the north branch jet,and sandstorms for double jet pattern are likely to occur beneath the merged descending leg of the two jets,sandstorms could occur either in the desceing area of upper level jet or in the ascending area:in the ascending area,the suction resulted from the low level convegence and the upper level divergence induces the low level strong winds and sandstorms,and in the descending area,the downward transfer of upper level momentum is in favor of the genesis of sandstorm.Between the north and south branch jet streams there always is a vertical circulation cell,which facilitates the genesis of sandstorm,therefore both the north branch jet and the south branch jet jointly impact the genesis and development of surface sandstorms.

Abstract:Transmission intensity of vertical polarized incident light under different artificial fog concentrations was experimentally measured,and based on the experimental data,changes in relative vertical and parallel transmission intensity were analyzed.Results show that the parallel transmission intensity approximately shows an exponentially decline distribution while the vertical one displays a rising-then-declining trend.Using the degree of depolarization,cause of depolarization was discussed,and the droplet can be viewed as a sphericity in the lighter fog.Based on the characteristic of polarized light,transmission intensity and scattering intensity were calculated.The experiment is valuable in study of the light transmission in fog and in analyzing the effect of fog on laser radiation polarization in the atmosphere.

Abstract:Possible connections are statistically analysed between landfalling typhoon number over China and precipitation over North China during rainy seasons(from June to September) using the datasets of the monthly landfalling typhoon number,104 stations rainfall in North China,and NCEP/NCAR sea level pressure,850 hPa streamline fields,and 500 hPa geopotential height fields from 1957 to 2002.Results show that the significantly positive correlations exist in the central and east areas of North China during rainy season with the highest correlation area situated in Raoyang and Baoding.In years with notably more landfalling typhoons,summer rainfall is enhanced over the central and east of North China,but decreased over the south,and in years with the notably less landfalling typhoons,the precipitation shows an opsite picture.Monthly analysis indicates that the most significant correlation exists in August over the central and east areas of North China too.The features of sea level pressure,850 hPa streamline anomaly,and 500 hPa geopotential height anomaly fields as well as cold air tracks in years of more(less) typhoon activity are all similar with those in yeas of more(less) summer rainfall over the center and east areas of North China.

Abstract:With the meso-scale non-hydrostatic model MM5,a heavy rainstorm in the Jiangnan area in the Meiyu peroid of 2003 has been simulated and the formation mechanism of the rainstorm analyzed.Result shows that the rainstorm belonged to a shearline-causing rainstorm.There were an energy front zone in the low level,and some inertial instable areas in the upper level of troposphere during the torrential heavy rain,and heavy rain took place on the left front side of a low level jet stream,and the right front side of an upper level jet stream.By analyzing the changes of physical quantities with time and height at the rainfall center,it can be seen that the cyclonic vorticity and convergence at the low level,the anticyclonic vorticity and divergence at the upper level,deep upward motion,the lifting of the isolines of equivalent temperature,the magnitude of negative ξ_mpv,ξ_mpv1 and ξ_mpv2 becoming larger were all favorable conditions to the heavy rain.When the rain weakened,almost all these physical quantities went to the opposite.The direct influencing weather systems showed the spatial and temporal features on meso-scale.It was clear that during the heavy rain there existed obvious inertial instability in the upper levels and convective instability in the lower levels.

Abstract:Using the measured dry-leaf biochemistry and hyperspectral reflectance data,a new thinking clue of leaf biochemical retrieval is developed based on the 1st derivative extremum of area-nomalized hyperspectral position variables.Research results indicate that this method can be employed to effectively extract the concentration of foliar total nitrogen,cellulose,lignin and starch.Especially the retrieval precision of cellulose,lignin and starch contents is better than the research available.Moreover,the ultimate application direction of vegetation remote sensing is the its canopy level.The investigation suggests that this technique can effectively remove soil influence on the extraction of total nitrogen,cellulose and lignin content,but the retrival result of starch is still not satisfactory.

Abstract:Based on the solar radiation observations from CE-318 sun-photometer's 936 nm channel and the relation of water vapor amount and transmissivity,the instantaneous technique is used to retrieve the atmospheric column water vapor amount on the west coast of the Bohai sea gulf.The results show that,using sun-photometer's 936 nm channel observations to retrieve atmospheric water vapor amount is feasible,but only on clear days.Atmospheric water vapor amount on the west coast of the Bohai sea gulf showed complicated temporal variations throughout a year with different diurnal variation patterns on clear days in defferent saesons.

Abstract:Х.П.ПОООъгоplotted a global 10 hPa geopotential height field averaged from June to August. After wards,this figure was widely cited by a lot of domestic teaching materials. But the figure has an obviously analytic error. In this paper,the error is pointed out and the NCEP/NCAR 40 a reanalysis dataset is used to correct the error.

Abstract:Using the mean monthly precipitation data of recent 14 years at 7 stations in Yemen,seasonal variations of precipitation are studied.On the basis of the analysis on seasonal features of precipitation,interannual variations of summer rain fall are emphatically investigated.Results show that precipitation in Yemen has obviously seasonal changes with large positive anomalies in summer(April to September),especially in July,August,and September,and that the anomalies peak month moves up.In the last 14 years,summer precipitation takes on an increasing dency,which is more obvious in recent years.Summer precipitations anomalies exhibit remarkably interannual variation periods of about 3 and 7 years.

Abstract:In four-dimension assimilation,combining conjugate gradient metnod and genetic algorithms(DA) could remedy the shortcoming of each other.It is proved in the experiments of this papar that the scheme not only could strengthen searching ability but also could accelerate the convergent speed of optimization.We adopt standard program in programming,therefore the assimilation program is almost automatic,so we could be eased from the hard programming work and avoid most of the errors.

Abstract:A design of automotive infrared rain sensor is presented in this paper.In the system,the infrared diode of high luminance is used as the lamp-house to irradiate the windshield of automobile and Motorola MC68HC908SR12 is used as MCU.The sensor finishes the detecting and sampling of the rain drops and water on the windshield with a 10-bit A/D converter of MC68HC908SR12.It output impulse signals of different duty cycles,and those signals are then transformed to relevant volts DC through the smoothing of filter.The volts DC is able to control the rotating speed of windshield wiper.

Abstract:On the basis of a Pascal-like source language and a Delphi object model,a object-oriented scripting language is designed by using wrapping object technology.The paper studies an object technology in scripting languages,and analyses its mechanism.A case study in which a practical code is generated for the scripting object is analyzed.Results show that the object technology is simple and efficient.