OBSERVATIONS OF TEMPERATURE MICROSTRUCTURE IN THE ATMOSPHERE

In order to provide data of atmospheric temperature microstructure for the investigation of light propagation we measured fluctuations of atmospheric temperature below the height of 300 m with a platinum wire thermometer in Tianjin in May and September, 1980. The results measured in daytime revealed some properties of the temperature structure parameter and spectrum. It has been confirmed that there is a maximum in the profile of the structure parameter produced probably by the entrainment in the interfacial layer at the top of convective boundary layer. The average of CT2 in the interfacial layer and its Wyngaard calculating method are discussed, and the thickness of the interfacial layer is obtained.It is shown by spectrum analysis that a wide inertial subrange exists in the convective boundary layer and the strong turbulent zone in the free atmosphere. The spectral law with the power of -2.5 was measured within the upper half of boundary layer over the sea in vicinity of Tanggu.     

LAGRANGIAN METHOD USED IN THE RESEARCH OF ATMOSPHERIC CIRCULATION

Based on the conservation of entropy and potential vorticity in adiabatic atmospheric motion without theconsideration of friction,calculation is made of the trajectory of a particle on an isentropic surface by use ofthe data of FGGE III-b.Results of several calculation schemes of the trajectory discussed show that thelocal data interpolation and Runge-Kutta time-integral scheme is the best.The calculated trajectory reflectsthe large-scale atmospheric motion only and the small-scale motion emerges as a deviation term of thecalculated trajectory.And then the outbreak and propagation of planetary wave are studied by means ofthe deformation of a material line,with the result showing that the material line can be tracked in the trop-osphere only in a few days,beyond which the interaction between the small-scale waves and large-scale motionleads to its dramatical twisting and deformation.Therefore,the Lagrangian method is assumed to be an effectivemeans of diagnostic research in the nonlinear interaction in atmospheric circulation,in addition to the generalstudy of the atmospheric circulation.     

DEFICIT OF PARTICULATE CHLORINE AND THE NONACID RAIN IN BEIJING

The acidity of precipitation in both clean and polluted areas was calculated for atmospheric CO2 and SO2 in equilibrium with water. pH values of 5 and 4.5 were obtained. In Beijing the pH value is increased due to paniculate chlorine reactivity and rainout of CaO in the atmosphere. The increase of pH value is related to liquid water content in cloud and the elemental concentrations of paniculate Cl and Ca in the atmosphere. This mechanism may help to explain the nonacid rain observed in Beijing where the air pollution problem is serious, as viewed by SO2 concentration and paniculate burden in the atmosphere.     

SPATIAL AND TEMPORAL VARIATIONS OF THE KINEMATIC CHARACTERISTICS IN THE PROPAGATION OF ATMOSPHERIC STATIONARY WAVES

Time-mean global general circulation data are employed to analyze the temporal and spatial variations ofthe meridional gradient of zonal mean potential vorticity,the critical wavenumber n_s for horizontal wave-propagation,and the critical wavenumber K_c for vertical wave-propagation.Thereby the kinematic charac-teristics in the propagation of atmospheric stationary waves and their annual variations are studied.Resultsshow that in the troposphere n_s and K_c usually decrease with the increase of either latitude or altitude.Synoptic and near-resonant Rossby waves could be trapped during their upward and meridional propagations.These characteristics possess prominent annual variations,especially in the Northern Hemisphere.It is foundthat the spatial and temporal variations of these kinematic characteristics are in good agreement with those ofthe atmospheric wave patterns.     

REMOTE SENSING OF THE SEASONAL VARIATION IN COLUMN ABUNDANCE OF ATMOSPHERIC CH_4

Infrared solar spectra on clear days were measured automatically by an infrared solarspectrometer(ISS)with 0.4 cm~(-1) resolution developed by us.A line-by line(LBL)computationmethod was used to calculate theoretical atmospheric absorption.In the wavelength range of 3.410—3.438 μm.the absorption is mainly due to atmospheric methane and water vapor.Columnatmospheric methane was retrieved from the recorded infrared solar spectra.The seasonal variationof column atmospheric methane in Hefei has been obtained from the measuremental data of nearly18 months since the April of 1997.and found that it is similar to that of background data.Theinstruments.principles of measurement and some of results were introduced,and the results arealso discussed briefly in the paper.     

ANALYSIS OF THE TELECONNECTIONAL STRUCTURES OF THE 500-hPa HEIGHT FIELD OVER THE NH IN JANUARY

Based on the oblique mode scheme provided in the Appendix, and analysis is made of the tcleconnectional structures (TNS) of the NH 500-hPa height field in January, resulting in a series of teleconnectional patterns representative of the main features of TNS, of which the teleconnectional pattern WPAA (Western Pacific/Asian/ American) closely related to the East-Asian circulation is presented for the first time in this field of research. Contrast analysis indicates that TNS are so sensitive to the transition of seasons that a slight transition would bring about a considerable response. Hence the examination of the month-to-month TNS of the NH atmospheric circulations is indispensable.     

THE EFFECT OF THE NEGATIVE ENTROPY FLOW ON THE ORGANIZATION OF ATMOSPHERIC DISSIPATIVE STRUCTURES IN NON-EQUILIBRIUM CONDITIONS

The entropy balance equation that describes the entropy budget of atmospheric systems is derived fromthe Gibbs relation.The distribution of the entropy flows of a west-Pacific typhoon and a Bengal-Bay cycloneis calculated and thus the dissipativity of the atmospheric systems is revealed.     

KEY AREAS OF AIR-SEA INTERACTION IN GLOBAL OCEANS AND STUDY OF THE CLIMATOLOGICAL FEATURES

Seven key areas of air-sea interaction in the global oceans are determined by comprehensive analysis of the global data of monthly mean sea surface temperature (SST), surface wind, temperature, humidity, sea surface sensible heat and latent heat fluxes. The time-lag correlation between SST and each atmospheric element in each key area are focally analyzed to expose the same and the different features of air-sea interaction in different key areas. The results show that the air-sea thermal interaction is strong in each area, SST, temperature and humidity can be fairly replaced with one another, particularly in the central eastern Pacific and the south India Ocean. The dynamic effect on SST is different in different areas and in the central western Pacific such effect is more important. The correlation between sensible heat, latent heat and SST is more significant in the eastern Pacific, the western Pacific and the two major monsoon areas — the northwestern Pacific and the south India Ocean. By analyzing the sustainable correlation probability of SST and every atmospheric element in each key area, we further know that the anomalies of which element, in which area and in which period are well sustained or easily destroyed. This is beneficial not only to prediction, but also to discussion of the physical mechanism of air-sea interaction.     

THE PHOTODISSOCIATION COEFFICIENTS OF OZONE AND OXYGEN IN THE CLOUDY TURBID ATMOSPHERE

In this paper, the effects of clouds with different albedos at different altitudes as underlying surface on the photodissociation coefficients of oxygen and ozone in the turbid atmosphere, where the multi-scattering of molecules and aerosols is considered, have been investigated. In addition, the effects of doubling the ozone concentration in the tropopausc due to the atmospheric motion on the photodissociation coefficients of ozone and oxygen are also studied.     

STEPPING FORWARD TO THE 21ST CENTURY IN A SOLID FOUNDATION—IN CELEBRATION OF THE TENTH ANNIVERSARY OF ACTA METEOROLOGICA SINICA(AMS)

How time flies!It has been the tenth anniversary since AMS started publishing in 1987.AMS(English edition)is an international academic journal in atmospheric sciences edited bythe Chinese Meteorological Society.During this period,ten volumes of AMS(41 Nos.,about500 articles)were published,including three special issues:on climate,on atmospheric signals     

SIMPLIFICATION OF THE OXYGEN-ABSORPTION COEFFICIENT FORMULA IN MICROWAVE BAND

Study of the oxygen-absorption coefficient in 5mm wave band is important for remote sensing of theatmospheric temperature profile from satellites or ground.In order to obtain the atmospheric temperatureprofile rapidly and accurately,it is necessary to have a simple,but accurate formula of the oxygen-absorp-tion coefficient.In this paper,formulae of the oxygen-absorption coefficient in a certain range of tempera-ture-pressure and at a standard isobaric surface have been derived.These formulae may substitute for Meeks-Lilley formula in remote sensing of the atmosphere.     

NUMERICAL SIMULATIONS OF THE EFFECTS OF AEROSOLS IN THE ATMOSPHERIC BOUNDARY LAYER ON THE CLIMATE

The climatic effects of the atmospheric boundary aerosols are studied by the use of a three-dimensional climatemodel.Simulated results show that the climate states both at the surface and in the atmosphere change remarkably whenthe aerosols with different optical thicknesses and properties are introduced into the atmospheric boundary layer of themodel.The aerosols absorb and scatter the solar shortwave radiation,therefore,they reduce the solar energy reachingthe ground surface and decrease the surface and the soil temperatures.The temperature in the boundary layer increasesbecause of the supplementary absorption of radiation by the boundary aerosols.In the atmosphere,the temperatures atall isobaric surfaces rise up except for the 100 hPa level.The atmospheric temperatures below the 500 hPa level aredirectly influenced by the boundary aerosols,while the atmospheric temperatures above the 500 hPa level are influencedby the heating due to convective condensation and the changes in the vertical motion field.Cyclonic differential circula-tions appear over the desert areas at the low levels,and anticyclonic differential circulations exist at the upper levels inthe horizontal flow fields.The vertical motions change in correspondence with the differential circulations.The changesin precipitation are directly related to that of vertical motions.The mechanisms of climate effects of the boundaryaerosols are also discussed in this paper.     

A STUDY ON ABSORPTION CHARACTERISTICS OF THE ATMOSPHERIC WINDOW IN MICROWAVE BAND

The absorption characteristics of the atmospheric window in the microwave band (λ=8.5 mm and 3.2 cm) are studied. The results measured in Beijing by using both solar radiation method and atmospheric radiation method arc compared with the values calculated from the radiosonde data so as to analyze their correlativity. The relationship between atmospheric window absorption and total column water vapour content is also discussed. The effects of clouds on the absorption are described.     

PROBABILITY OF RECEIVED-POWER FLUCTUATION OF AN OPTICAL SYSTEM IN THE TURBULENT ATMOSPHERE

The probability of received-power fluctuation in the turbulent atmosphere is discussed with a simple and yet reasonable model for a direct-detection optical system. Good agreement was found between the theoretical results and the field experiment. Thus the analysis in this paper may be taken as a guide for the design of atmospheric optical system.     

PRELIMINARY ANALYSIS OF THE ATMOSPHERIC RADIATIVE HEATING FIELDS IN AUTUMN IN THE MID LATITUDE ARID AREAS OF CHINA

A parameterized radiation and cloud model developed at the University of Utah,U.S.A.has been used to computethe atmospheric radiative properties in Zhangye area during the pilot experiment of HEIFE in September of 1988.Somecharacteristics of atmospheric radiative heating fields during the autumn in Zhangye area have been analysed,and somequestions that merit attention in the future observation are also discussed in this paper.     

PARAMETERIZATION OF SOLAR RADIATIVE FLUX CALCULATION IN THE ATMOSPHERE

Based on the two-stream approximation a broad-band parameterization scheme for solar radiative flux calculationis presented.The whole solar spectral region from 0.2 to 3.58 μm is divided into three broad spectral intervals.The effec-tive broad-band optical depths and single scattering albedos in the atmosphere in each spectral interval can be obtainedusing parameterized formulae from known atmospheric parameters.The overlapping scattering and/or absorption ef-fects of two atmospheric constituents are considered properly.In the consideration of radiative effect of clouds in theatmosphere the single scattering albedos and backscattering parameters of clouds in each broad spectral interval are giv-en preliminarily and the cloud optical depths are determined according to the cloud liquid water content.     

AN ANALYSIS OF THE STRUCTURE OF THUNDERSTORM IN THE ATMOSPHERIC BOUNDARY LAYER

The structure of thunderstorm in the atmospheric boundary layer in Beijing area is analysed by using three-year data of tower. It is indicated that the outflow current of the thunderstorm in the lower layer is a sort of density current. An area of evident wind direction shear is found at about half an hour to one hour before the arrival of the gust front.The maximum intensity of the shear can reach 0.35sec-1.The inner structure within the density current is also very complicated. At the nocturnal stable boundary layer in summertime, the development of the convective motions is often triggered due to the instability of the Kelvin-Helmholtz wave.     

OBSERVING RESULTS OF THE ATMOSPHERIC MIXED LAYER IN BEIJING AREA AND THE EVALUATION OF THEORETICAL MODELS

In the present study the data of wind and temperature profiles and sensible heat flux observed in Beijing inJuly and December of 1986,together with the results of water tank experiments for comparison,are used to testthe prediction models of the atmospheric mixed layer with zero order and first order assumption,respectively.The results show that the entrainment rates in summer and winter used in the zero order model are 0.15 and0.10,respectively,while its value in the first order model ranges between 0.15 and 0.19 with a lower rateat the initial stage of mixed layer development.Emphasis in the study is also placed on the relationship between the entrainmert rate and the developmentof the mixed layer.     

DYNAMICAL CHARACTERISTICS OF THE STREAM FIELD OF COLD FRONT IN BOUNDARY LAYER

The motion equation of atmospheric boundary layer with cold front surface under geostrophicmomentum approximation is solved and some characteristics of the stream field for the cold frontsurface in the boundary layer are derived,for example,the slope of the cold front surface increaseswith the increases of geostrophic vorticity and the temporal tendency of geostrophic wind speed,and also increases with the decrease of the component of thermal wind speed along the motiondirection of the front:the stream field above and below the cold front surface in the boundary layerdepends on the slope of the front surface,geostrophic wind speed and its temporal and spatialdistributions.A common characteristic is that there exist updraft motion above the cold frontsurface and downdraft motion below it.     

THE NUMERICAL SIMULATION OF THE THREE-DIMEN-SIONAL TELECONNECTIONS IN THE SUMMER CIRCULATION OVER THE NORTHERN HEMISPHERE

In this paper, a quasi-geostrophic, 34-level spherical coordinate model with Rayleigh friction, Newtonian cooling and the horizontal eddy thermal diffusivity is used to simulate the three-dimensional telecon nection in the summer circulation over the Northern Hemisphere.The computed results show that the change of the heat source over the Tibetan Plateau may cause the change of the atmospheric circulation over the middle and high latitudes in the Northern Hemisphere. When the heal source over the Tibetan Plateau is enhanced, it may cause the Tibetan high to enhance over South Asia and cause the change of the atmospheric circulation over East Asia and North America, i. e., Northeast China and North Japan will be controlled by a trough, which brings about a cold summer in this area. In the same way, an anticyclone will be enhanced over the Okhotsk sea. Moreover, another trough will be formed over Alaska, while another ridge will develop to the northeast of North America. Besides, the Pacific subtropical high will be weakened. These results are in good agreement with those obtained from the observed data.