Abstract:By using the data from 8 Indian radiation-sounding stations during the MONEX of May-August 1979 and the radiation measurements during the QXPMEX(the Qinghai-Xizang Plateau Meteorological Science Experiment)conducted during thesaid time and from August 1982 to July 1983, a useful expression for downward atmo-spheric radiation is presented through detailed discoussions. The expression is marked bydistinct physical implications, higher fitting accuracy and considerable universality. The regime of the downward atmospheric radiation is calculated for the first time for 218 sta-tions in the meteorological network of China and investigation done of its geographic dis-tribution and variation with latitudes, elevations and seasons, thus bringing about someinteresting results.

Abstract:Features of 30-60 day oscillation over the Qinghai-Xizang Plateau and itssurrounding areas are investigated by using the ECMWF objective analysis data during May-September 1980. It is shown that there are two branches of teleconnection wave-trains related to the 30-60 day oscillation over the plateau and its surrounding areas:one is the Qinghai-Xizang Plateau-Irkutsk-Europe-the eastern Atlantic branch andthe other is the Qinghai-Xizang Plateau-Irkutsk-Yakutsk-Kamthatka-Aleutian-branch. The 30-60 day oscillation is found on the north and south sides of the plateauand shows different vertical structures in the upper and lower troposphere. The changeof the wavetrains with time is characterized mainly by westward energy dispersion.

Abstract:The global mean temperature variation obeys the rule of square root, i. e.,thetemperature variation within 10 years is in inverse proportion to and that within 10-10⁵ years is in direct proportion to the square root of time scale. Three guesses are thusmade: (1)the climatic variation within 10-10⁵ years is controlled by the earth heat fluxvariation; (2)the oscillation of the climatic system is an inherent property of its stabili-ty,which is determined by the stability of its outer parameters; (3)the real climatic stateis always vacillating around its critical state of stability,tending toward a kind of ex-treme value principle, rather than the real "highest efficiency".

Abstract:Analysis is performed of the spectral structure of the atmosphericwaves (i. e.,harmonic spectrum along the latitudinal circle and frequency spec-trum in the time domain)simulated by the general circulation model (GCM),pro-posed by the Institute of Atmospheric Physics (IAP),Academia Sinica, and theiranomalies in an El Niño year. Results show that ultra-long waves represent theprincipal form of low-latitude waves, characterized remarkably by quasi-40-day oscillations in a given geographic locality and somewhat related to the obser-vations and significant anomalies are experienced in an El Niño year. Perhaps thepresent study is a useful attempt at the assessment of the GCM’S performancesand the expansion of its research domain.

Abstract:Based on the known thermal teleconnection between summer sea (June, Julyand August)and winter air (December,January and February),a corresponding mathe-matical model is developed through parametrization. Beginning with the thermal fore-casting equation of summer (June) sea and winter (January) air, the temporal variationof the function affected asynchronously by sea and air is analyzed, thus ascertaining thestability of the model. Thereby, long-range prediction experiments are conducted ofthe diabatic heat flow and temperature anomalies of the NH 500hPa monthly mean atmo-sphere. The independent and dependent predictions show that the long-range prediction method by use of the sea-air thermal teleconnection is applicable and has an enormous potential in its use.

Abstract:On the basis of the ECMWE grid data from November 16. 1982 to March 15,1983,the distribution of quasi-40-day low-frequency oscillations over East Asia andAustralia and the relation between the oscillations in different districts of the said areaare investigated by means of low-frequency filtering and the maximum entropy spectralanalysis. Results suggest that the behaviors of the NH mid-latitude frontal zone andthe East Asian westerly jet exhibit obvious characteristics of quasi-40-day periodic os-cillations and the same is true for the corresponding east-west movement of the westPacific subtropical high in the NH. The moving of the subtropical high causes fluctua-tions in intensity of the low-level cross-equatorial air flows of the northeast trade onthe south side of the high in the 110-180°E area, thus exerting an important impact onthe activity and interruption of the Australian monsoon. Thus, the baroclinic low-fre-quency oscillations in the NH mid-latitude are closely related to the Australian summermonsoon.

Abstract:A complet Lyapunov index spectrum is extracted by using the Shanghai day-to-day mean pressure data of 15 years (1970-1985) and the correlation matrix analy-sis. The spectrum includes not only positive, zero and negative values, but also the sumof the Lyapunov indexes, that is, ∑λ_i<0, proving once again that the short-rangeweather attractor in China’s monsoon areas is a form of chaotic movement. As the sumof the positive Lyapunov indexes reflects the overall exhalation of the system,it is theo-retically proved that the sum is equal to the Kolmogora entropy of the system. In thispaper, the sum of the positive indexes sum from =K=0. 110405 is acquired when the delayedtime τ=5, the parameter m=2,and the number of dimensions d_M=9. This is close tothe predictable time and also in good agreement with the result in the literature[2] bythe authors of the present work.

Abstract:In this study, a linear spectral model is used for simulating the structure ofthe global stationary waves at 200 hPa. The linear responses of the model atmosphere tothe zonal mean westerly wind and temperature are also investigated.

Abstract:Based on the PPI echo data obtained by digital weather radar in the rainstormarea and after filtering the weak echoes which have minor effects on the measurement ofrainfall,the movement of the strong echo blocks in the area is tracked by means of themoment invariant method. Results from the experiments on two cold-front heavy rainprocesses show that when the interval of radar detection is 20 or 30 minutes, the aver-age accuracy by this method reaches as high as 91%. In addition, on the basis of theabove experiment results and using two or three pictures in the PPI echo data, experi-ments are performed on the linear extrapolation method by which the locality of thestrong echo block in the next hour is forecasted. The results are rather inspiring.

Abstract:The energy budget in the wave-number domain is calculated for an Atlantic-Europe blocking process during October to November 1980. The relationship is exam-ined in detail between the energy evolution of ultra-long waves (wavenumber 1-3)and synoptic-scale waves (wavenumber 4-10) and the foundation, maintenance andbreakdown of the blocking high. Results indicate that the kinetic energy of ultra-longwaves controlling the blocking originates mainly from the conversion of baroclinic avail-able potential energy and the nonlinear cascade transfer of the kinetic energy of synoptic-scale waves while the available potential energy of ultra-long waves mainly from theconversion of the zonal mean available potential energy. The nonlinear interaction of thecomponents on different temporal scales also plays an important role in the foundationand maintenance of the blocking high.

Abstract:Using the 1000-500 hPa thickness data, investigation is made of the rela-tionship between the horizontal structure of the winter temperature anomaly in the low-er troposphere over the NH extratropics and the heating anomaly of the underlying sur-face. It is shown that the most intensive and widespread temperature anomaly occurs inthe Eurasian inland. When it is abnormally warm in this area, the northwestern part ofEurope and the east coast of Asia will experience extreme cold, and the lower latitudesin the central Pacific, the west coast of North America and the mid-Atlantic will be ex-tremely warm, and vice versa. It may be inferred that the coverage of the polar sea icein the area of 20-110°W has much to do with the above temperature distribution.

Abstract:Up to the present, neither the studies carried out nor the models developed athome or abroad for simulating the growth of various crops have made a breakthrough orcould be put into operation by the meteorological services. This is because special obser-vational data are required and complicated parameters have to be calculated. In this pa-per, based on the crop physiological and agrometeorological theories and consideringcrop photosynthesis, respiration and allotment of assimilated products, a simplifiedmodel is presented for the growth of late rice. In this model only conventional meteoro-logical data are needed with the pentad as the length of time-step.

Abstract:A microcomputer processing system for cloud classification using GMS bis-pectral images (the cloud classification system for short)is designed. In addition to theroutine functions, such as image quantization, sampling, storage, display and local am-plification, it can process monospectral or bispectral satellite images. For monospectralsatellite images, it can be used for 1-dimensional histogram analysis and the contraststretching and pixel frequency statistics in the arbitrary value domain, and for bispectralsatellite images, rectangle classification and spatial coherence are adopted for cloud clas-sification on the 2-dimensional histogram. Thus, the cloud classification system candisplay the cloud images and perform the precipitus classification as well as the pixelnumber and cloudiness percentage of various clouds and precipitus clouds.

Abstract:Theoretically, Doppler width can be obtained from conventional weatherradar signals by correlation analysis. However, the applicability of this method or itsactual accuracy requires further proof. Simulation is an ideal, economical and quick wayto do this. In this study, a simulation is conducted of a random Doppler multi-frequen-cy spectrum that can change the spectrum parameters and the result is close to the actualconditions. The time domain signals are obtained from the weather radar echoes bymeans of Fourier inverse transform on the multi-frequency spectrum. Thereafter, acorrelation analysis is performed of the time domain signals, yielding the lag correlationcurve and Doppler standard deviation. Analysis of the experiment results under differentconditions reveals the effects of the different SNRs and the Doppler spectrum forms onthe accuracy of the correlation method, thus providing a guideline for the application ofthe method.

Abstract:Some statistical characteristicas of the ultra-low-level jet and its evolutionare analyzed with the data gathered from the meteorological tower at Tianjin. It is preliminarily confirmed that the occurrence and development of the ultra-low-level jetbear a definite relation to the inversion layer inside the tower which has a correspondingvertical scale.

Abstract:By using the soil water and heat diffusion equation,a farmland soil water dy-narnic simulation model is presented for the semiarid, semi-humid and prone-to-drought areas. Testified by observed data in the winter wheat fields, the medel is usedto simulate the farmland soil water dynamic changes using the routine meteorologicaland agrometeorological data from the representative stations in different soil zones of thesaid areas in Shaanxi province and the eastern part of Gansu province. After modifyingthe boundary conditions,the forecasting model is developed and used to predict farmlandsoil water by means of the observed data. Results suggest that it is necessary to considerthe effects of soil temperature and its gradient. The feasibility of simulating farmlandwater using routine meteorological and agrometeorological data is also discussed.

Abstract:In this paper, a numerical model is presented for predicting the buoyantplume rise with wind in the neutral and stable stratification. The Boussinesq approxima-tion and the bent-over plume assumption are not used in the model. Instead, the dragof the wind on the plume is taken into consideration and it is assumed that the ambientturbulence has notable effects upon the path even in the early and late stages of rising.Finally, the numerical results are obtained by applying a Hamming procedure. Analysisindicates that the change of parameters within the plume is reasonable. It is found thatthe results from the model are in good agreement with the observational data in neutraland stable stratification.